diff --git a/CONTRIBUTORS b/CONTRIBUTORS index ee50a4c049aa674aa400b6ab99871438c53d37a9..1984d44c53773624a686c0af48bc1055d4fb0e5a 100644 --- a/CONTRIBUTORS +++ b/CONTRIBUTORS @@ -33,6 +33,7 @@ Aaron Jacobs Aaron Jensen Aaron Kemp Aaron Patterson +Aaron Sheah Aaron Stein Aaron Torres Aaron Zinman @@ -47,6 +48,7 @@ Adam Harvey Adam Kisala Adam Langley Adam Medzinski +Adam Mitha Adam Shannon Adam Shelton Adam Sindelar @@ -54,6 +56,8 @@ Adam Thomason Adam Williams Adam Woodbeck Adarsh Ravichandran +Adel Rodríguez +Adin Scannell Aditya Harindar Aditya Mukerjee Adrian Hesketh @@ -68,6 +72,7 @@ Afanasev Stanislav Agis Anastasopoulos Agniva De Sarker Ahmed W. Mones +Ahmet Aktürk Ahmet Alp Balkan Ahmet Soormally Ahmy Yulrizka @@ -92,11 +97,13 @@ Alberto Bertogli Alberto Donizetti Alberto García Hierro Alec Benzer +Alejandro García Montoro Aleksa Sarai Aleksandar Dezelin Aleksandr Lukinykh Aleksandr Razumov Alekseev Artem +Aleksei Tirman Alessandro Arzilli Alessandro Baffa Alex A Skinner @@ -165,6 +172,7 @@ Ali Rizvi-Santiago Aliaksandr Valialkin Alice Merrick Alif Rachmawadi +Allan Guwatudde Allan Simon Allen Li Alok Menghrajani @@ -172,6 +180,7 @@ Alwin Doss Aman Gupta Amarjeet Anand Amir Mohammad Saied +Amit Kumar Amr Mohammed Amrut Joshi An Long @@ -185,6 +194,7 @@ André Carvalho André Martins Andre Nathan Andrea Nodari +Andrea Simonini Andrea Spadaccini Andreas Auernhammer Andreas Jellinghaus @@ -244,6 +254,7 @@ Andy Pan Andy Walker Andy Wang Andy Williams +Andy Zhao Andzej Maciusovic Anfernee Yongkun Gui Angelo Bulfone @@ -269,6 +280,7 @@ Anton Kuklin Antonin Amand Antonio Antelo Antonio Bibiano +Antonio Garcia Antonio Huete Jimenez Antonio Murdaca Antonio Troina @@ -292,8 +304,10 @@ Artem Khvastunov Artem Kolin Arthur Fabre Arthur Khashaev +Artur M. Wolff Artyom Pervukhin Arvindh Rajesh Tamilmani +Ashish Bhate Ashish Gandhi Asim Shankar Assel Meher @@ -325,6 +339,7 @@ Baokun Lee Barnaby Keene Bartosz Grzybowski Bartosz Oler +Bassam Ojeil Bastian Ike Ben Burkert Ben Cartwright-Cox @@ -332,6 +347,7 @@ Ben Eitzen Ben Fried Ben Haines Ben Hoyt +Ben Hutchings Ben Kraft Ben Laurie Ben Lubar @@ -430,6 +446,7 @@ Carl Henrik Lunde Carl Jackson Carl Johnson Carl Mastrangelo +Carl Menezes Carl Shapiro Carlisia Campos Carlo Alberto Ferraris @@ -443,6 +460,7 @@ Carlos Iriarte Carlos Souza Carolyn Van Slyck Carrie Bynon +Carson Hoffman Cary Hull Case Nelson Casey Callendrello @@ -462,6 +480,7 @@ Charles Kenney Charles L. Dorian Charles Lee Charles Weill +Charlie Moog Charlotte Brandhorst-Satzkorn Chauncy Cullitan Chen Zhidong @@ -516,6 +535,7 @@ Christopher Nelson Christopher Nielsen Christopher Redden Christopher Swenson +Christopher Thomas <53317512+chrisssthomas@users.noreply.github.com> Christopher Wedgwood Christos Zoulas Christy Perez @@ -541,6 +561,8 @@ Cosmos Nicolaou Costin Chirvasuta Craig Citro Cristian Staretu +Cristo García +cui fliter Cuihtlauac ALVARADO Cuong Manh Le Curtis La Graff @@ -560,6 +582,7 @@ Dan Callahan Dan Harrington Dan Jacques Dan Johnson +Dan McArdle Dan Peterson Dan Pupius Dan Scales @@ -611,6 +634,7 @@ Dave Russell David Anderson David Barnett David Benjamin +David Black David Bond David Brophy David Bürgin <676c7473@gmail.com> @@ -654,6 +678,7 @@ Davor Kapsa Dean Eigenmann <7621705+decanus@users.noreply.github.com> Dean Prichard Deepak Jois +Deepak S Denis Bernard Denis Brandolini Denis Isaev @@ -676,8 +701,10 @@ Dhiru Kholia Dhruvdutt Jadhav Di Xiao Didier Spezia +Diego Medina Diego Siqueira Dieter Plaetinck +Dilyn Corner Dimitri Sokolyuk Dimitri Tcaciuc Dina Garmash @@ -714,6 +741,7 @@ Doug Fawley Douglas Danger Manley Drew Flower Drew Hintz +Drew Richardson Duco van Amstel Duncan Holm Dustin Carlino @@ -735,6 +763,7 @@ Egon Elbre Ehren Kret Eitan Adler Eivind Uggedal +El Mostafa Idrassi Elbert Fliek Eldar Rakhimberdin Elena Grahovac @@ -742,6 +771,7 @@ Eli Bendersky Elias Naur Elliot Morrison-Reed Ellison Leão +Elvina Yakubova Emerson Lin Emil Bektimirov Emil Hessman @@ -767,6 +797,7 @@ Eric Rescorla Eric Roshan-Eisner Eric Rutherford Eric Rykwalder +Eric Wang Erick Tryzelaar Erik Aigner Erik Dubbelboer @@ -778,6 +809,7 @@ Ernest Chiang Erwin Oegema Esko Luontola Ethan Burns +Ethan Hur Ethan Miller Euan Kemp Eugene Formanenko @@ -818,6 +850,7 @@ Felix Cornelius <9767036+fcornelius@users.noreply.github.com> Felix Geisendörfer Felix Kollmann Ferenc Szabo +Fernandez Ludovic Filip Gruszczyński Filip Haglund Filip Stanis @@ -858,6 +891,7 @@ Gabriel Nelle Gabriel Nicolas Avellaneda Gabriel Rosenhouse Gabriel Russell +Gabriel Vasile Gareth Paul Jones Garret Kelly Garrick Evans @@ -891,6 +925,8 @@ Gianguido Sora` Gideon Jan-Wessel Redelinghuys Giles Lean Giovanni Bajo +GitHub User @180909 (70465953) <734461790@qq.com> +GitHub User @6543 (24977596) <6543@obermui.de> GitHub User @aca (50316549) GitHub User @ajnirp (1688456) GitHub User @ajz01 (4744634) @@ -904,10 +940,12 @@ GitHub User @bontequero (2674999) GitHub User @cch123 (384546) GitHub User @chainhelen (7046329) GitHub User @chanxuehong (3416908) +GitHub User @Cluas (10056928) GitHub User @cncal (23520240) GitHub User @DQNEO (188741) GitHub User @Dreamacro (8615343) GitHub User @dupoxy (1143957) +GitHub User @EndlessCheng (7086966) GitHub User @erifan (31343225) GitHub User @esell (9735165) GitHub User @fatedier (7346661) @@ -916,12 +954,15 @@ GitHub User @geedchin (11672310) GitHub User @GrigoriyMikhalkin (3637857) GitHub User @hengwu0 (41297446) <41297446+hengwu0@users.noreply.github.com> GitHub User @hitzhangjie (3725760) +GitHub User @hqpko (13887251) GitHub User @itchyny (375258) GitHub User @jinmiaoluo (39730824) GitHub User @jopbrown (6345470) GitHub User @kazyshr (30496953) GitHub User @kc1212 (1093806) +GitHub User @komisan19 (18901496) GitHub User @Kropekk (13366453) +GitHub User @lhl2617 (33488131) GitHub User @linguohua (3434367) GitHub User @LotusFenn (13775899) GitHub User @ly303550688 (11519839) @@ -936,10 +977,14 @@ GitHub User @OlgaVlPetrova (44112727) GitHub User @pityonline (438222) GitHub User @po3rin (29445112) GitHub User @pokutuna (57545) +GitHub User @povsister (11040951) GitHub User @pytimer (17105586) +GitHub User @qcrao (7698088) GitHub User @ramenjuniti (32011829) GitHub User @saitarunreddy (21041941) +GitHub User @SataQiu (9354727) GitHub User @shogo-ma (9860598) +GitHub User @sivchari (55221074) GitHub User @skanehira (7888591) GitHub User @soolaugust (10558124) GitHub User @surechen (7249331) @@ -947,9 +992,12 @@ GitHub User @tatsumack (4510569) GitHub User @tell-k (26263) GitHub User @tennashi (10219626) GitHub User @uhei (2116845) +GitHub User @uji (49834542) +GitHub User @unbyte (5772358) GitHub User @uropek (39370426) GitHub User @utkarsh-extc (53217283) GitHub User @witchard (4994659) +GitHub User @wolf1996 (5901874) GitHub User @yah01 (12216890) GitHub User @yuanhh (1298735) GitHub User @zikaeroh (48577114) @@ -962,6 +1010,7 @@ Glenn Brown Glenn Lewis Gordon Klaus Gordon Tyler +Grace Han Graham King Graham Miller Grant Griffiths @@ -977,10 +1026,12 @@ Guilherme Caruso Guilherme Garnier Guilherme Goncalves Guilherme Rezende +Guilherme Souza <32180229+gqgs@users.noreply.github.com> Guillaume J. Charmes Guillaume Sottas Günther Noack Guobiao Mei +Guodong Li Guoliang Wang Gustav Paul Gustav Westling @@ -995,6 +1046,7 @@ HAMANO Tsukasa Han-Wen Nienhuys Hang Qian Hanjun Kim +Hanlin He Hanlin Shi Haoran Luo Haosdent Huang @@ -1026,18 +1078,19 @@ Herbie Ong Heschi Kreinick Hidetatsu Yaginuma Hilko Bengen +Himanshu Kishna Srivastava <28himanshu@gmail.com> Hiroaki Nakamura Hiromichi Ema Hironao OTSUBO Hiroshi Ioka Hitoshi Mitake Holden Huang -Songlin Jiang Hong Ruiqi Hongfei Tan Horacio Duran Horst Rutter Hossein Sheikh Attar +Hossein Zolfi Howard Zhang Hsin Tsao Hsin-Ho Yeh @@ -1054,11 +1107,14 @@ Ian Haken Ian Kent Ian Lance Taylor Ian Leue +Ian Mckay Ian Tay +Ian Woolf Ian Zapolsky Ibrahim AshShohail Icarus Sparry Iccha Sethi +Ichinose Shogo Idora Shinatose Ignacio Hagopian Igor Bernstein @@ -1068,6 +1124,7 @@ Igor Vashyst Igor Zhilianin Ikko Ashimine Illya Yalovyy +Ilya Chukov <56119080+Elias506@users.noreply.github.com> Ilya Sinelnikov Ilya Tocar INADA Naoki @@ -1122,6 +1179,7 @@ James Cowgill James Craig Burley James David Chalfant James Eady +James Fennell James Fysh James Gray James Hartig @@ -1178,6 +1236,7 @@ Jason Wangsadinata Javier Kohen Javier Revillas Javier Segura +Jay Chen Jay Conrod Jay Lee Jay Taylor @@ -1200,6 +1259,7 @@ Jeff Johnson Jeff R. Allen Jeff Sickel Jeff Wendling +Jeff Widman Jeffrey H Jelte Fennema Jens Frederich @@ -1210,6 +1270,7 @@ Jeremy Faller Jeremy Jackins Jeremy Jay Jeremy Schlatter +Jero Bado Jeroen Bobbeldijk Jeroen Simonetti Jérôme Doucet @@ -1251,6 +1312,8 @@ Joe Richey Joe Shaw Joe Sylve Joe Tsai +Joel Courtney +Joel Ferrier Joel Sing Joël Stemmer Joel Stemmer @@ -1260,7 +1323,9 @@ Johan Euphrosine Johan Jansson Johan Knutzen Johan Sageryd +Johannes Huning John Asmuth +John Bampton John Beisley John C Barstow John DeNero @@ -1269,6 +1334,7 @@ John Gibb John Gilik John Graham-Cumming John Howard Palevich +John Jago John Jeffery John Jenkins John Leidegren @@ -1320,6 +1386,7 @@ Josa Gesell Jose Luis Vázquez González Joseph Bonneau Joseph Holsten +Joseph Morag Josh Baum Josh Bleecher Snyder Josh Chorlton @@ -1327,12 +1394,14 @@ Josh Deprez Josh Goebel Josh Hoak Josh Holland +Josh Rickmar Josh Roppo Josh Varga Joshua Bezaleel Abednego Joshua Boelter Joshua Chase Joshua Crowgey +Joshua Harshman Joshua M. Clulow Joshua Rubin Josselin Costanzi @@ -1353,6 +1422,7 @@ Julie Qiu Julien Kauffmann Julien Salleyron Julien Schmidt +Julien Tant Julio Montes Jun Zhang Junchen Li @@ -1419,10 +1489,12 @@ Kenta Mori Kerollos Magdy Ketan Parmar Kevan Swanberg +Kevin Albertson Kevin Ballard Kevin Burke Kévin Dunglas Kevin Gillette +Kevin Herro Kevin Kirsche Kevin Klues Kevin Malachowski @@ -1457,6 +1529,7 @@ Koya IWAMURA Kris Kwiatkowski Kris Nova Kris Rousey +Krishna Birla Kristopher Watts Krzysztof Dąbrowski Kshitij Saraogi @@ -1480,6 +1553,7 @@ Lajos Papp Lakshay Garg Lann Martin Lanre Adelowo +Lapo Luchini Larry Clapp Larry Hosken Lars Jeppesen @@ -1496,6 +1570,7 @@ Leigh McCulloch Leo Antunes Leo Rudberg Leon Klingele +Leonard Wang Leonardo Comelli Leonel Quinteros Lev Shamardin @@ -1506,7 +1581,9 @@ Lily Chung Lingchao Xin Lion Yang Liz Rice +Lize Cai Lloyd Dewolf +Lluís Batlle i Rossell Lorenz Bauer Lorenz Brun Lorenz Nickel @@ -1531,6 +1608,7 @@ Lukasz Milewski Luke Champine Luke Curley Luke Granger-Brown +Luke Shumaker Luke Young Luna Duclos Luuk van Dijk @@ -1550,6 +1628,7 @@ Mal Curtis Manfred Touron Manigandan Dharmalingam Manish Goregaokar +Manlio Perillo Manoj Dayaram Mansour Rahimi Manu Garg @@ -1646,6 +1725,8 @@ Matt Joiner Matt Jones Matt Juran Matt Layher +Matt Masurka +Matt Pearring Matt Reiferson Matt Robenolt Matt Strong @@ -1659,9 +1740,12 @@ Matthew Denton Matthew Holt Matthew Horsnell Matthew Waters +Matthias Frei Matthieu Hauglustaine Matthieu Olivier Matthijs Kooijman +Mattias Appelgren +Mauricio Alvarado Max Drosdo.www Max Riveiro Max Schmitt @@ -1677,9 +1761,11 @@ Máximo Cuadros Ortiz Maxwell Krohn Maya Rashish Mayank Kumar +Mehrad Sadeghi <2012.linkinpark@gmail.com> Meir Fischer Meng Zhuo Mhd Sulhan +Mia Zhu Micah Stetson Michael Anthony Knyszek Michael Brandenburg @@ -1730,8 +1816,10 @@ Michal Franc Michał Łowicki Michal Pristas Michal Rostecki +Michal Stokluska Michalis Kargakis Michel Lespinasse +Michel Levieux Michele Di Pede Mickael Kerjean Mickey Reiss @@ -1790,7 +1878,9 @@ Muir Manders Mukesh Sharma Mura Li Mykhailo Lesyk +Nahum Shalman Naman Aggarwal +Naman Gera Nan Deng Nao Yonashiro Naoki Kanatani @@ -1818,6 +1908,7 @@ Neven Sajko Nevins Bartolomeo Niall Sheridan Nic Day +Nicholas Asimov Nicholas Katsaros Nicholas Maniscalco Nicholas Ng @@ -1847,6 +1938,7 @@ Nik Nyby Nikhil Benesch Nikita Gillmann Nikita Kryuchkov +Nikita Melekhin Nikita Vanyasin Niklas Schnelle Niko Dziemba @@ -1858,6 +1950,7 @@ Niranjan Godbole Nishanth Shanmugham Noah Campbell Noah Goldman +Noah Santschi-Cooney Noble Johnson Nodir Turakulov Noel Georgi @@ -1894,6 +1987,7 @@ Pablo Rozas Larraondo Pablo Santiago Blum de Aguiar Padraig Kitterick Pallat Anchaleechamaikorn +Pan Chenglong <1004907659@qq.com> Panos Georgiadis Pantelis Sampaziotis Paolo Giarrusso @@ -1947,6 +2041,7 @@ Paulo Casaretto Paulo Flabiano Smorigo Paulo Gomes Pavel Paulau +Pavel Watson Pavel Zinovkin Pavlo Sumkin Pawel Knap @@ -1954,6 +2049,8 @@ Pawel Szczur Paweł Szulik Pei Xian Chee Pei-Ming Wu +Pen Tree +Peng Gao Percy Wegmann Perry Abbott Petar Dambovaliev @@ -1992,6 +2089,7 @@ Philip Brown Philip Hofer Philip K. Warren Philip Nelson +Philipp Sauter Philipp Stephani Phillip Campbell <15082+phillc@users.noreply.github.com> Pierre Carru @@ -2007,6 +2105,7 @@ Poh Zi How Polina Osadcha Pontus Leitzler Povilas Versockas +Prajwal Koirala <16564273+Prajwal-Koirala@users.noreply.github.com> Prasanga Siripala Prasanna Swaminathan Prashant Agrawal @@ -2027,11 +2126,13 @@ Quim Muntal Quinn Slack Quinten Yearsley Quoc-Viet Nguyen +Rabin Gaire Radek Simko Radek Sohlich Radu Berinde Rafal Jeczalik Raghavendra Nagaraj +Rahul Bajaj Rahul Chaudhry Rahul Wadhwani Raif S. Naffah @@ -2041,12 +2142,14 @@ Rajender Reddy Kompally Ralph Corderoy Ramazan AYYILDIZ Ramesh Dharan +Randy Reddig Raph Levien Raphael Geronimi Raul Silvera Ravil Bikbulatov RaviTeja Pothana Ray Tung +Ray Wu Raymond Kazlauskas Rebecca Stambler Reilly Watson @@ -2066,6 +2169,7 @@ Richard Eric Gavaletz Richard Gibson Richard Miller Richard Musiol +Richard Pickering Richard Ulmer Richard Wilkes Rick Arnold @@ -2124,6 +2228,7 @@ Rowan Worth Rudi Kramer Rui Ueyama Ruixin Bao +Ruslan Andreev Ruslan Nigmatullin Russ Cox Russell Haering @@ -2141,6 +2246,7 @@ Ryan Seys Ryan Slade Ryan Zhang Ryoichi KATO +Ryoya Sekino Ryuji Iwata Ryuma Yoshida Ryuzo Yamamoto @@ -2176,8 +2282,10 @@ Sardorbek Pulatov Sascha Brawer Sasha Lionheart Sasha Sobol +Satoru Kitaguchi Scott Barron Scott Bell +Scott Cotton Scott Crunkleton Scott Ferguson Scott Lawrence @@ -2191,6 +2299,7 @@ Sean Chittenden Sean Christopherson Sean Dolphin Sean Harger +Sean Harrington Sean Hildebrand Sean Liao Sean Rees @@ -2212,6 +2321,7 @@ Sergey Dobrodey Sergey Frolov Sergey Glushchenko Sergey Ivanov +Sergey Kacheev Sergey Lukjanov Sergey Mishin Sergey Mudrik @@ -2223,6 +2333,7 @@ Serhat Giydiren Serhii Aheienko Seth Hoenig Seth Vargo +Shaba Abhiram Shahar Kohanim Shailesh Suryawanshi Shamil Garatuev @@ -2250,9 +2361,13 @@ Shivakumar GN Shivani Singhal Shivansh Rai Shivashis Padhi +Shoshin Nikita +Shota Sugiura Shubham Sharma +Shuhei Takahashi Shun Fan Silvan Jegen +Simão Gomes Viana Simarpreet Singh Simon Drake Simon Ferquel @@ -2267,13 +2382,16 @@ Sina Siadat Sjoerd Siebinga Sokolov Yura Song Gao +Song Lim Songjiayang +Songlin Jiang Soojin Nam Søren L. Hansen Sparrow Li Spencer Kocot Spencer Nelson Spencer Tung +Spenser Black Spring Mc Srdjan Petrovic Sridhar Venkatakrishnan @@ -2324,6 +2442,7 @@ Suyash Suzy Mueller Sven Almgren Sven Blumenstein +Sven Lee Sven Taute Sylvain Zimmer Syohei YOSHIDA @@ -2406,12 +2525,14 @@ Tiwei Bie Tobias Assarsson Tobias Columbus Tobias Klauser +Tobias Kohlbau Toby Burress Todd Kulesza Todd Neal Todd Wang Tom Anthony Tom Bergan +Tom Freudenberg Tom Heng Tom Lanyon Tom Levy @@ -2440,6 +2561,7 @@ Toshiki Shima Totoro W Travis Bischel Travis Cline +Trevor Dixon Trevor Strohman Trey Lawrence Trey Roessig @@ -2463,6 +2585,7 @@ Tzach Shabtay Tzu-Chiao Yeh Tzu-Jung Lee Udalov Max +Uddeshya Singh Ugorji Nwoke Ulf Holm Nielsen Ulrich Kunitz @@ -2475,6 +2598,7 @@ Vadim Grek Vadim Vygonets Val Polouchkine Valentin Vidic +Vaughn Iverson Vee Zhang Vega Garcia Luis Alfonso Venil Noronha @@ -2491,6 +2615,7 @@ Vincent Batts Vincent Vanackere Vinu Rajashekhar Vish Subramanian +Vishal Dalwadi Vishvananda Ishaya Visweswara R Vitaly Zdanevich @@ -2542,6 +2667,7 @@ Willem van der Schyff William Chan William Chang William Josephson +William Langford William Orr William Poussier Wisdom Omuya @@ -2550,6 +2676,7 @@ Xi Ruoyao Xia Bin Xiangdong Ji Xiaodong Liu +Xing Gao <18340825824@163.com> Xing Xing Xingqang Bai Xu Fei @@ -2571,6 +2698,7 @@ Yasha Bubnov Yasser Abdolmaleki Yasuharu Goto Yasuhiro Matsumoto +Yasutaka Shinzaki Yasuyuki Oka Yazen Shunnar Yestin Sun @@ -2583,14 +2711,18 @@ Yorman Arias Yoshiyuki Kanno Yoshiyuki Mineo Yosuke Akatsuka +Youfu Zhang Yu Heng Zhang Yu Xuan Zhang +Yu, Li-Yu Yuichi Kishimoto Yuichi Nishiwaki Yuji Yaginuma +Yuki Ito Yuki OKUSHI Yuki Yugui Sonoda Yukihiro Nishinaka <6elpinal@gmail.com> +YunQiang Su Yury Smolsky Yusuke Kagiwada Yuusei Kuwana @@ -2599,6 +2731,7 @@ Yves Junqueira Zac Bergquist Zach Bintliff Zach Gershman +Zach Hoffman Zach Jones Zachary Amsden Zachary Gershman @@ -2617,6 +2750,7 @@ Zhou Peng Ziad Hatahet Ziheng Liu Zorion Arrizabalaga +Zvonimir Pavlinovic Zyad A. Ali Максадбек Ахмедов Максим Федосеев diff --git a/api/next.txt b/api/next.txt index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..3eb7f3f797fdbabefe3c14e5dac81e1ef4fc88f7 100644 --- a/api/next.txt +++ b/api/next.txt @@ -0,0 +1,108 @@ +pkg syscall (darwin-amd64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (darwin-amd64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (darwin-amd64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (darwin-amd64), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (darwin-amd64-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (darwin-amd64-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (darwin-amd64-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (darwin-amd64-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (freebsd-386), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (freebsd-386), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (freebsd-386), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (freebsd-386), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (freebsd-386-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (freebsd-386-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (freebsd-386-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (freebsd-386-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (freebsd-amd64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (freebsd-amd64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (freebsd-amd64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (freebsd-amd64), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (freebsd-amd64-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (freebsd-amd64-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (freebsd-amd64-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (freebsd-amd64-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (freebsd-arm), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (freebsd-arm), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (freebsd-arm), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (freebsd-arm), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (freebsd-arm-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (freebsd-arm-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (freebsd-arm-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (freebsd-arm-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (linux-386), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (linux-386), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (linux-386), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (linux-386), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (linux-386-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (linux-386-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (linux-386-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (linux-386-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (linux-amd64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (linux-amd64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (linux-amd64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (linux-amd64), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (linux-amd64-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (linux-amd64-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (linux-amd64-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (linux-amd64-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (linux-arm), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (linux-arm), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (linux-arm), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (linux-arm), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (linux-arm-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (linux-arm-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (linux-arm-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (linux-arm-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-386), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-386), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-386), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-386), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-386-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-386-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-386-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-386-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-amd64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-amd64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-amd64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-amd64), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-amd64-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-amd64-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-amd64-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-amd64-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-arm), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-arm), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-arm), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-arm), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-arm-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-arm-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-arm-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-arm-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-arm64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-arm64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-arm64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-arm64), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (netbsd-arm64-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (netbsd-arm64-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (netbsd-arm64-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (netbsd-arm64-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (openbsd-386), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (openbsd-386), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (openbsd-386), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (openbsd-386), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (openbsd-386-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (openbsd-386-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (openbsd-386-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (openbsd-386-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (openbsd-amd64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (openbsd-amd64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (openbsd-amd64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (openbsd-amd64), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (openbsd-amd64-cgo), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error) +pkg syscall (openbsd-amd64-cgo), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error) +pkg syscall (openbsd-amd64-cgo), func SendtoInet4(int, []uint8, int, SockaddrInet4) error +pkg syscall (openbsd-amd64-cgo), func SendtoInet6(int, []uint8, int, SockaddrInet6) error +pkg syscall (windows-386), func WSASendtoInet4(Handle, *WSABuf, uint32, *uint32, uint32, SockaddrInet4, *Overlapped, *uint8) error +pkg syscall (windows-386), func WSASendtoInet6(Handle, *WSABuf, uint32, *uint32, uint32, SockaddrInet6, *Overlapped, *uint8) error +pkg syscall (windows-amd64), func WSASendtoInet4(Handle, *WSABuf, uint32, *uint32, uint32, SockaddrInet4, *Overlapped, *uint8) error +pkg syscall (windows-amd64), func WSASendtoInet6(Handle, *WSABuf, uint32, *uint32, uint32, SockaddrInet6, *Overlapped, *uint8) error diff --git a/doc/asm.html b/doc/asm.html index d5788000861a7afea9c621077dc49e849c2674f9..51f85eb94822a4a900bfbb205f5cbcc709e5a2f8 100644 --- a/doc/asm.html +++ b/doc/asm.html @@ -166,7 +166,7 @@ jumps and branches.
  • -SP: Stack pointer: top of stack. +SP: Stack pointer: the highest address within the local stack frame.
    • @@ -216,7 +216,7 @@ If a Go prototype does not name its result, the expected assembly name is The SP pseudo-register is a virtual stack pointer used to refer to frame-local variables and the arguments being prepared for function calls. -It points to the top of the local stack frame, so references should use negative offsets +It points to the highest address within the local stack frame, so references should use negative offsets in the range [−framesize, 0): x-8(SP), y-4(SP), and so on.

    @@ -409,7 +409,7 @@ The linker will choose one of the duplicates to use. (For TEXT items.) Don't insert the preamble to check if the stack must be split. The frame for the routine, plus anything it calls, must fit in the -spare space at the top of the stack segment. +spare space remaining in the current stack segment. Used to protect routines such as the stack splitting code itself.
  • @@ -460,7 +460,7 @@ Only valid on functions that declare a frame size of 0. TOPFRAME = 2048
    (For TEXT items.) -Function is the top of the call stack. Traceback should stop at this function. +Function is the outermost frame of the call stack. Traceback should stop at this function.
    • diff --git a/doc/go1.17.html b/doc/go1.17.html deleted file mode 100644 index 48811e6b679747040d7c858161d18eb72b31f34f..0000000000000000000000000000000000000000 --- a/doc/go1.17.html +++ /dev/null @@ -1,1211 +0,0 @@ - - - - - - -

    DRAFT RELEASE NOTES — Introduction to Go 1.17

    - -

    - - Go 1.17 is not yet released. These are work-in-progress - release notes. Go 1.17 is expected to be released in August 2021. - -

    - -

    Changes to the language

    - -

    - Go 1.17 includes three small enhancements to the language. -

    - -
      -
    • - Conversions - from slice to array pointer: An expression s of - type []T may now be converted to array pointer type - *[N]T. If a is the result of such a - conversion, then corresponding indices that are in range refer to - the same underlying elements: &a[i] == &s[i] - for 0 <= i < N. The conversion panics if - len(s) is less than N. -
      • - -
    • - unsafe.Add: - unsafe.Add(ptr, len) adds len - to ptr and returns the updated pointer - unsafe.Pointer(uintptr(ptr) + uintptr(len)). -
      • - -
    • - unsafe.Slice: - For expression ptr of type *T, - unsafe.Slice(ptr, len) returns a slice of - type []T whose underlying array starts - at ptr and whose length and capacity - are len. -
      • -
    - -

    - The package unsafe enhancements were added to simplify writing code that conforms - to unsafe.Pointer's safety - rules, but the rules remain unchanged. In particular, existing - programs that correctly use unsafe.Pointer remain - valid, and new programs must still follow the rules when - using unsafe.Add or unsafe.Slice. -

    - - -

    - Note that the new conversion from slice to array pointer is the - first case in which a type conversion can panic at run time. - Analysis tools that assume type conversions can never panic - should be updated to consider this possibility. -

    - -

    Ports

    - -

    Darwin

    - -

    - As announced in the Go 1.16 release - notes, Go 1.17 requires macOS 10.13 High Sierra or later; support - for previous versions has been discontinued. -

    - -

    Windows

    - -

    - Go 1.17 adds support of 64-bit ARM architecture on Windows (the - windows/arm64 port). This port supports cgo. -

    - -

    OpenBSD

    - -

    - The 64-bit MIPS architecture on OpenBSD (the openbsd/mips64 - port) now supports cgo. -

    - -

    - In Go 1.16, on the 64-bit x86 and 64-bit ARM architectures on - OpenBSD (the openbsd/amd64 and openbsd/arm64 - ports) system calls are made through libc, instead - of directly using machine instructions. In Go 1.17, this is also - done on the 32-bit x86 and 32-bit ARM architectures on OpenBSD - (the openbsd/386 and openbsd/arm ports). - This ensures compatibility with OpenBSD 6.9 onwards, which require - system calls to be made through libc for non-static - Go binaries. -

    - -

    ARM64

    - -

    - Go programs now maintain stack frame pointers on the 64-bit ARM - architecture on all operating systems. Previously it maintained - stack frame pointers only on Linux, macOS, and iOS. -

    - -

    loong64 GOARCH value reserved

    - -

    - The main Go compiler does not yet support the LoongArch - architecture, but we've reserved the GOARCH value - "loong64". - This means that Go files named *_loong64.go will now - be ignored by Go - tools except when that GOARCH value is being used. -

    - -

    Tools

    - -

    Go command

    - -

    Lazy module loading

    - -

    - If a module specifies go 1.17 or higher in its - go.mod file, its transitive requirements are now loaded lazily, - avoiding the need to download or read go.mod files for - otherwise-irrelevant dependencies. To support lazy loading, in Go 1.17 modules - the go command maintains explicit requirements in - the go.mod file for every dependency that provides any package - transitively imported by any package or test within the module. - See the design - document for more detail. - -

    - -

    - Because the number of additional explicit requirements in the go.mod file may - be substantial, in a Go 1.17 module the newly-added requirements - on indirect dependencies are maintained in a - separate require block from the block containing direct - dependencies. -

    - -

    - To facilitate the upgrade to lazy loading, the - go mod tidy subcommand now supports - a -go flag to set or change the go version in - the go.mod file. To enable lazy loading for an existing module - without changing the selected versions of its dependencies, run: -

    - -
    -  go mod tidy -go=1.17
-
    - -

    - By default, go mod tidy verifies that - the selected versions of dependencies relevant to the main module are the same - versions that would be used by the prior Go release (Go 1.16 for a module that - specifies go 1.17), and preserves - the go.sum entries needed by that release even for dependencies - that are not normally needed by other commands. -

    - -

    - The -compat flag allows that version to be overridden to support - older (or only newer) versions, up to the version specified by - the go directive in the go.mod file. To tidy - a go 1.17 module for Go 1.17 only, without saving - checksums for (or checking for consistency with) Go 1.16: -

    - -
    -  go mod tidy -compat=1.17
-
    - -

    - Note that even if the main module is tidied with -compat=1.17, - users who require the module from a - go 1.16 or earlier module will still be able to - use it, provided that the packages use only compatible language and library - features. -

    - -

    - The go mod graph subcommand also - supports the -go flag, which causes it to report the graph as - seen by the indicated Go version, showing dependencies that may otherwise be - pruned out by lazy loading. -

    - -

    Module deprecation comments

    - -

    - Module authors may deprecate a module by adding a - // Deprecated: - comment to go.mod, then tagging a new version. - go get now prints a warning if a module needed to - build packages named on the command line is deprecated. go - list -m -u prints deprecations for all - dependencies (use -f or -json to show the full - message). The go command considers different major versions to - be distinct modules, so this mechanism may be used, for example, to provide - users with migration instructions for a new major version. -

    - -

    go get

    - -

    - The go get -insecure flag is - deprecated and has been removed. To permit the use of insecure schemes - when fetching dependencies, please use the GOINSECURE - environment variable. The -insecure flag also bypassed module - sum validation, use GOPRIVATE or GONOSUMDB if - you need that functionality. See go help - environment for details. -

    - -

    - go get prints a deprecation warning when installing - commands outside the main module (without the -d flag). - go install cmd@version should be used - instead to install a command at a specific version, using a suffix like - @latest or @v1.2.3. In Go 1.18, the -d - flag will always be enabled, and go get will only - be used to change dependencies in go.mod. -

    - -

    go.mod files missing go directives

    - -

    - If the main module's go.mod file does not contain - a go directive and - the go command cannot update the go.mod file, the - go command now assumes go 1.11 instead of the - current release. (go mod init has added - go directives automatically since - Go 1.12.) -

    - -

    - If a module dependency lacks an explicit go.mod file, or - its go.mod file does not contain - a go directive, - the go command now assumes go 1.16 for that - dependency instead of the current release. (Dependencies developed in GOPATH - mode may lack a go.mod file, and - the vendor/modules.txt has to date never recorded - the go versions indicated by dependencies' go.mod - files.) -

    - -

    vendor contents

    - -

    - If the main module specifies go 1.17 or higher, - go mod vendor now annotates - vendor/modules.txt with the go version indicated by - each vendored module in its own go.mod file. The annotated - version is used when building the module's packages from vendored source code. -

    - -

    - If the main module specifies go 1.17 or higher, - go mod vendor now omits go.mod - and go.sum files for vendored dependencies, which can otherwise - interfere with the ability of the go command to identify the correct - module root when invoked within the vendor tree. -

    - -

    Password prompts

    - -

    - The go command by default now suppresses SSH password prompts and - Git Credential Manager prompts when fetching Git repositories using SSH, as it - already did previously for other Git password prompts. Users authenticating to - private Git repos with password-protected SSH may configure - an ssh-agent to enable the go command to use - password-protected SSH keys. -

    - -

    go mod download

    - -

    - When go mod download is invoked without - arguments, it will no longer save sums for downloaded module content to - go.sum. It may still make changes to go.mod and - go.sum needed to load the build list. This is the same as the - behavior in Go 1.15. To save sums for all modules, use go - mod download all. -

    - -

    //go:build lines

    - -

    - The go command now understands //go:build lines - and prefers them over // +build lines. The new syntax uses - boolean expressions, just like Go, and should be less error-prone. - As of this release, the new syntax is fully supported, and all Go files - should be updated to have both forms with the same meaning. To aid in - migration, gofmt now automatically - synchronizes the two forms. For more details on the syntax and migration plan, - see - https://golang.org/design/draft-gobuild. -

    - -

    go run

    - -

    - go run now accepts arguments with version suffixes - (for example, go run - example.com/cmd@v1.0.0). This causes go - run to build and run packages in module-aware mode, ignoring the - go.mod file in the current directory or any parent directory, if - there is one. This is useful for running executables without installing them or - without changing dependencies of the current module. -

    - -

    Gofmt

    - -

    - gofmt (and go fmt) now synchronizes - //go:build lines with // +build lines. If a file - only has // +build lines, they will be moved to the appropriate - location in the file, and matching //go:build lines will be - added. Otherwise, // +build lines will be overwritten based on - any existing //go:build lines. For more information, see - https://golang.org/design/draft-gobuild. -

    - -

    Vet

    - -

    New warning for mismatched //go:build and // +build lines

    - -

    - The vet tool now verifies that //go:build and - // +build lines are in the correct part of the file and - synchronized with each other. If they aren't, - gofmt can be used to fix them. For more - information, see - https://golang.org/design/draft-gobuild. -

    - -

    New warning for calling signal.Notify on unbuffered channels

    - -

    - The vet tool now warns about calls to signal.Notify - with incoming signals being sent to an unbuffered channel. Using an unbuffered channel - risks missing signals sent on them as signal.Notify does not block when - sending to a channel. For example: -

    - -
    -c := make(chan os.Signal)
-// signals are sent on c before the channel is read from.
-// This signal may be dropped as c is unbuffered.
-signal.Notify(c, os.Interrupt)
-
    - -

    - Users of signal.Notify should use channels with sufficient buffer space to keep up with the - expected signal rate. -

    - -

    New warnings for Is, As and Unwrap methods

    - -

    - The vet tool now warns about methods named As, Is or Unwrap - on types implementing the error interface that have a different signature than the - one expected by the errors package. The errors.{As,Is,Unwrap} functions - expect such methods to implement either Is(error) bool, - As(interface{}) bool, or Unwrap() error - respectively. The functions errors.{As,Is,Unwrap} will ignore methods with the same - names but a different signature. For example: -

    - -
    -type MyError struct { hint string }
-func (m MyError) Error() string { ... } // MyError implements error.
-func (MyError) Is(target interface{}) bool { ... } // target is interface{} instead of error.
-func Foo() bool {
-	x, y := MyError{"A"}, MyError{"B"}
-	return errors.Is(x, y) // returns false as x != y and MyError does not have an `Is(error) bool` function.
-}
-
    - -

    Cover

    - -

    - The cover tool now uses an optimized parser - from golang.org/x/tools/cover, which may be noticeably faster - when parsing large coverage profiles. -

    - -

    Compiler

    - -

    - Go 1.17 implements a new way of passing function arguments and results using - registers instead of the stack. - Benchmarks for a representative set of Go packages and programs show - performance improvements of about 5%, and a typical reduction in - binary size of about 2%. - This is currently enabled for Linux, macOS, and Windows on the - 64-bit x86 architecture (the linux/amd64, - darwin/amd64, and windows/amd64 ports). -

    - -

    - This change does not affect the functionality of any safe Go code - and is designed to have no impact on most assembly code. - It may affect code that violates - the unsafe.Pointer - rules when accessing function arguments, or that depends on - undocumented behavior involving comparing function code pointers. - To maintain compatibility with existing assembly functions, the - compiler generates adapter functions that convert between the new - register-based calling convention and the previous stack-based - calling convention. - These adapters are typically invisible to users, except that taking - the address of a Go function in assembly code or taking the address - of an assembly function in Go code - using reflect.ValueOf(fn).Pointer() - or unsafe.Pointer will now return the address of the - adapter. - Code that depends on the value of these code pointers may no longer - behave as expected. - Adapters also may cause a very small performance overhead in two - cases: calling an assembly function indirectly from Go via - a func value, and calling Go functions from assembly. -

    - -

    - The format of stack traces from the runtime (printed when an uncaught panic - occurs, or when runtime.Stack is called) is improved. Previously, - the function arguments were printed as hexadecimal words based on the memory - layout. Now each argument in the source code is printed separately, separated - by commas. Aggregate-typed (struct, array, string, slice, interface, and complex) - arguments are delimited by curly braces. A caveat is that the value of an - argument that only lives in a register and is not stored to memory may be - inaccurate. Function return values (which were usually inaccurate) are no longer - printed. -

    - -

    - Functions containing closures can now be inlined. - One effect of this change is that a function with a closure may - produce a distinct closure code pointer for each place that the - function is inlined. - Go function values are not directly comparable, but this change - could reveal bugs in code that uses reflect - or unsafe.Pointer to bypass this language restriction - and compare functions by code pointer. -

    - -

    Core library

    - -

    Cgo

    - -

    - The runtime/cgo package now provides a - new facility that allows to turn any Go values to a safe representation - that can be used to pass values between C and Go safely. See - runtime/cgo.Handle for more information. -

    - -

    URL query parsing

    - - -

    - The net/url and net/http packages used to accept - ";" (semicolon) as a setting separator in URL queries, in - addition to "&" (ampersand). Now, settings with non-percent-encoded - semicolons are rejected and net/http servers will log a warning to - Server.ErrorLog - when encountering one in a request URL. -

    - -

    - For example, before Go 1.17 the Query - method of the URL example?a=1;b=2&c=3 would have returned - map[a:[1] b:[2] c:[3]], while now it returns map[c:[3]]. -

    - -

    - When encountering such a query string, - URL.Query - and - Request.FormValue - ignore any settings that contain a semicolon, - ParseQuery - returns the remaining settings and an error, and - Request.ParseForm - and - Request.ParseMultipartForm - return an error but still set Request fields based on the - remaining settings. -

    - -

    - net/http users can restore the original behavior by using the new - AllowQuerySemicolons - handler wrapper. This will also suppress the ErrorLog warning. - Note that accepting semicolons as query separators can lead to security issues - if different systems interpret cache keys differently. - See issue 25192 for more information. -

    - -

    TLS strict ALPN

    - - -

    - When Config.NextProtos - is set, servers now enforce that there is an overlap between the configured - protocols and the ALPN protocols advertised by the client, if any. If there is - no mutually supported protocol, the connection is closed with the - no_application_protocol alert, as required by RFC 7301. This - helps mitigate the ALPACA cross-protocol attack. -

    - -

    - As an exception, when the value "h2" is included in the server's - Config.NextProtos, HTTP/1.1 clients will be allowed to connect as - if they didn't support ALPN. - See issue 46310 for more information. -

    - -

    Minor changes to the library

    - -

    - As always, there are various minor changes and updates to the library, - made with the Go 1 promise of compatibility - in mind. -

    - -
    archive/zip
    -
    -

    - The new methods File.OpenRaw, Writer.CreateRaw, Writer.Copy provide support for cases where performance is a primary concern. -

    -
    -
    - -
    bufio
    -
    -

    - The Writer.WriteRune method - now writes the replacement character U+FFFD for negative rune values, - as it does for other invalid runes. -

    -
    -
    - -
    bytes
    -
    -

    - The Buffer.WriteRune method - now writes the replacement character U+FFFD for negative rune values, - as it does for other invalid runes. -

    -
    -
    - -
    compress/lzw
    -
    -

    - The NewReader - function is guaranteed to return a value of the new - type Reader, - and similarly NewWriter - is guaranteed to return a value of the new - type Writer. - These new types both implement a Reset method - (Reader.Reset, - Writer.Reset) - that allows reuse of the Reader or Writer. -

    -
    -
    - -
    crypto/ed25519
    -
    -

    - The crypto/ed25519 package has been rewritten, and all - operations are now approximately twice as fast on amd64 and arm64. - The observable behavior has not otherwise changed. -

    -
    -
    - -
    crypto/elliptic
    -
    -

    - CurveParams - methods now automatically invoke faster and safer dedicated - implementations for known curves (P-224, P-256, and P-521) when - available. Note that this is a best-effort approach and applications - should avoid using the generic, not constant-time CurveParams - methods and instead use dedicated - Curve implementations - such as P256. -

    - -

    - The P521 curve - implementation has been rewritten using code generated by the - fiat-crypto project, - which is based on a formally-verified model of the arithmetic - operations. It is now constant-time and three times faster on amd64 and - arm64. The observable behavior has not otherwise changed. -

    -
    -
    - -
    crypto/rand
    -
    -

    - The crypto/rand package now uses the getentropy - syscall on macOS and the getrandom syscall on Solaris, - Illumos, and DragonFlyBSD. -

    -
    -
    - -
    crypto/tls
    -
    -

    - The new Conn.HandshakeContext - method allows the user to control cancellation of an in-progress TLS - handshake. The provided context is accessible from various callbacks through the new - ClientHelloInfo.Context and - CertificateRequestInfo.Context - methods. Canceling the context after the handshake has finished has no effect. -

    - -

    - Cipher suite ordering is now handled entirely by the - crypto/tls package. Currently, cipher suites are sorted based - on their security, performance, and hardware support taking into account - both the local and peer's hardware. The order of the - Config.CipherSuites - field is now ignored, as well as the - Config.PreferServerCipherSuites - field. Note that Config.CipherSuites still allows - applications to choose what TLS 1.0–1.2 cipher suites to enable. -

    - -

    - The 3DES cipher suites have been moved to - InsecureCipherSuites - due to fundamental block size-related - weakness. They are still enabled by default but only as a last resort, - thanks to the cipher suite ordering change above. -

    - -

    - Beginning in the next release, Go 1.18, the - Config.MinVersion - for crypto/tls clients will default to TLS 1.2, disabling TLS 1.0 - and TLS 1.1 by default. Applications will be able to override the change by - explicitly setting Config.MinVersion. - This will not affect crypto/tls servers. -

    -
    -
    - -
    crypto/x509
    -
    -

    - CreateCertificate - now returns an error if the provided private key doesn't match the - parent's public key, if any. The resulting certificate would have failed - to verify. -

    - -

    - The temporary GODEBUG=x509ignoreCN=0 flag has been removed. -

    - -

    - ParseCertificate - has been rewritten, and now consumes ~70% fewer resources. The observable - behavior has not otherwise changed, except for error messages. -

    - -

    - On BSD systems, /etc/ssl/certs is now searched for trusted - roots. This adds support for the new system trusted certificate store in - FreeBSD 12.2+. -

    - -

    - Beginning in the next release, Go 1.18, crypto/x509 will - reject certificates signed with the SHA-1 hash function. This doesn't - apply to self-signed root certificates. Practical attacks against SHA-1 - have been demonstrated in 2017 and publicly - trusted Certificate Authorities have not issued SHA-1 certificates since 2015. -

    -
    -
    - -
    database/sql
    -
    -

    - The DB.Close method now closes - the connector field if the type in this field implements the - io.Closer interface. -

    - -

    - The new - NullInt16 - and - NullByte - structs represent the int16 and byte values that may be null. These can be used as - destinations of the Scan method, - similar to NullString. -

    -
    -
    - -
    debug/elf
    -
    -

    - The SHT_MIPS_ABIFLAGS - constant has been added. -

    -
    -
    - -
    encoding/binary
    -
    -

    - binary.Uvarint will stop reading after 10 bytes to avoid - wasted computations. If more than 10 bytes are needed, the byte count returned is -11. -
    - Previous Go versions could return larger negative counts when reading incorrectly encoded varints. -

    -
    -
    - -
    encoding/csv
    -
    -

    - The new - Reader.FieldPos - method returns the line and column corresponding to the start of - a given field in the record most recently returned by - Read. -

    -
    -
    - -
    encoding/xml
    -
    -

    - When a comment appears within a - Directive, it is now replaced - with a single space instead of being completely elided. -

    - -

    - Invalid element or attribute names with leading, trailing, or multiple - colons are now stored unmodified into the - Name.Local field. -

    -
    -
    - -
    flag
    -
    -

    - Flag declarations now panic if an invalid name is specified. -

    -
    -
    - -
    go/build
    -
    -

    - The new - Context.ToolTags - field holds the build tags appropriate to the current Go - toolchain configuration. -

    -
    -
    - -
    go/format
    -
    -

    - The Source and - Node functions now - synchronize //go:build lines with // +build - lines. If a file only has // +build lines, they will be - moved to the appropriate location in the file, and matching - //go:build lines will be added. Otherwise, - // +build lines will be overwritten based on any existing - //go:build lines. For more information, see - https://golang.org/design/draft-gobuild. -

    -
    -
    - -
    go/parser
    -
    -

    - The new SkipObjectResolution - Mode value instructs the parser not to resolve identifiers to - their declaration. This may improve parsing speed. -

    -
    -
    - -
    image
    -
    -

    - The concrete image types (RGBA, Gray16 and so on) - now implement a new RGBA64Image - interface. The concrete types that previously implemented - draw.Image now also implement - draw.RGBA64Image, a - new interface in the image/draw package. -

    -
    -
    - -
    io/fs
    -
    -

    - The new FileInfoToDirEntry function converts a FileInfo to a DirEntry. -

    -
    -
    - -
    math
    -
    -

    - The math package now defines three more constants: MaxUint, MaxInt and MinInt. - For 32-bit systems their values are 2^32 - 1, 2^31 - 1 and -2^31, respectively. - For 64-bit systems their values are 2^64 - 1, 2^63 - 1 and -2^63, respectively. -

    -
    -
    - -
    mime
    -
    -

    - On Unix systems, the table of MIME types is now read from the local system's - Shared MIME-info Database - when available. -

    -
    -
    - -
    mime/multipart
    -
    -

    - Part.FileName - now applies - filepath.Base to the - return value. This mitigates potential path traversal vulnerabilities in - applications that accept multipart messages, such as net/http - servers that call - Request.FormFile. -

    -
    -
    - -
    net
    -
    -

    - The new method IP.IsPrivate reports whether an address is - a private IPv4 address according to RFC 1918 - or a local IPv6 address according RFC 4193. -

    - -

    - The Go DNS resolver now only sends one DNS query when resolving an address for an IPv4-only or IPv6-only network, - rather than querying for both address families. -

    - -

    - The ErrClosed sentinel error and - ParseError error type now implement - the net.Error interface. -

    - -

    - The ParseIP and ParseCIDR - functions now reject IPv4 addresses which contain decimal components with leading zeros. - - These components were always interpreted as decimal, but some operating systems treat them as octal. - This mismatch could hypothetically lead to security issues if a Go application was used to validate IP addresses - which were then used in their original form with non-Go applications which interpreted components as octal. Generally, - it is advisable to always re-encode values after validation, which avoids this class of parser misalignment issues. -

    -
    -
    - -
    net/http
    -
    -

    - The net/http package now uses the new - (*tls.Conn).HandshakeContext - with the Request context - when performing TLS handshakes in the client or server. -

    - -

    - Setting the Server - ReadTimeout or WriteTimeout fields to a negative value now indicates no timeout - rather than an immediate timeout. -

    - -

    - The ReadRequest function - now returns an error when the request has multiple Host headers. -

    - -

    - When producing a redirect to the cleaned version of a URL, - ServeMux now always - uses relative URLs in the Location header. Previously it - would echo the full URL of the request, which could lead to unintended - redirects if the client could be made to send an absolute request URL. -

    - -

    - When interpreting certain HTTP headers handled by net/http, - non-ASCII characters are now ignored or rejected. -

    - -

    - If - Request.ParseForm - returns an error when called by - Request.ParseMultipartForm, - the latter now continues populating - Request.MultipartForm - before returning it. -

    -
    -
    - -
    net/http/httptest
    -
    -

    - ResponseRecorder.WriteHeader - now panics when the provided code is not a valid three-digit HTTP status code. - This matches the behavior of ResponseWriter - implementations in the net/http package. -

    -
    -
    - -
    net/url
    -
    -

    - The new method Values.Has - reports whether a query parameter is set. -

    -
    -
    - -
    os
    -
    -

    - The File.WriteString method - has been optimized to not make a copy of the input string. -

    -
    -
    - -
    reflect
    -
    -

    - The new - Value.CanConvert - method reports whether a value can be converted to a type. - This may be used to avoid a panic when converting a slice to an - array pointer type if the slice is too short. - Previously it was sufficient to use - Type.ConvertibleTo - for this, but the newly permitted conversion from slice to array - pointer type can panic even if the types are convertible. -

    - -

    - The new - StructField.IsExported - and - Method.IsExported - methods report whether a struct field or type method is exported. - They provide a more readable alternative to checking whether PkgPath - is empty. -

    - -

    - The new VisibleFields function - returns all the visible fields in a struct type, including fields inside anonymous struct members. -

    - -

    - The ArrayOf function now panics when - called with a negative length. -

    - -

    - Checking the Type.ConvertibleTo method - is no longer sufficient to guarantee that a call to - Value.Convert will not panic. - It may panic when converting `[]T` to `*[N]T` if the slice's length is less than N. - See the language changes section above. -

    -
    -
    - -
    runtime/metrics
    -
    -

    - New metrics were added that track total bytes and objects allocated and freed. - A new metric tracking the distribution of goroutine scheduling latencies was - also added. -

    -
    -
    - -
    runtime/pprof
    -
    -

    - Block profiles are no longer biased to favor infrequent long events over - frequent short events. -

    -
    -
    - -
    strconv
    -
    -

    - The strconv package now uses Ulf Adams's Ryū algorithm for formatting floating-point numbers. - This algorithm improves performance on most inputs and is more than 99% faster on worst-case inputs. -

    - -

    - The new QuotedPrefix function - returns the quoted string (as understood by - Unquote) - at the start of input. -

    -
    -
    - -
    strings
    -
    -

    - The Builder.WriteRune method - now writes the replacement character U+FFFD for negative rune values, - as it does for other invalid runes. -

    -
    -
    - -
    sync/atomic
    -
    -

    - atomic.Value now has Swap and - CompareAndSwap methods that provide - additional atomic operations. -

    -
    -
    - -
    syscall
    -
    -

    -

    - The GetQueuedCompletionStatus and - PostQueuedCompletionStatus - functions are now deprecated. These functions have incorrect signatures and are superseded by - equivalents in the golang.org/x/sys/windows package. -

    - -

    - On Unix-like systems, the process group of a child process is now set with signals blocked. - This avoids sending a SIGTTOU to the child when the parent is in a background process group. -

    - -

    - The Windows version of - SysProcAttr - has two new fields. AdditionalInheritedHandles is - a list of additional handles to be inherited by the new child - process. ParentProcess permits specifying the - parent process of the new process. - -

    - The constant MSG_CMSG_CLOEXEC is now defined on - DragonFly and all OpenBSD systems (it was already defined on - some OpenBSD systems and all FreeBSD, NetBSD, and Linux systems). -

    - -

    - The constants SYS_WAIT6 and WEXITED - are now defined on NetBSD systems (SYS_WAIT6 was - already defined on DragonFly and FreeBSD systems; - WEXITED was already defined on Darwin, DragonFly, - FreeBSD, Linux, and Solaris systems). -

    -
    -
    - -
    testing
    -
    -

    - Added a new testing flag -shuffle which controls the execution order of tests and benchmarks. -

    -

    - The new - T.Setenv - and B.Setenv - methods support setting an environment variable for the duration - of the test or benchmark. -

    -
    -
    - -
    text/template/parse
    -
    -

    - The new SkipFuncCheck Mode - value changes the template parser to not verify that functions are defined. -

    -
    -
    - -
    time
    -
    -

    - The Time type now has a - GoString method that - will return a more useful value for times when printed with the - %#v format specifier in the fmt package. -

    - -

    - The new Time.IsDST method can be used to check whether the time - is in Daylight Savings Time in its configured location. -

    - -

    - The new Time.UnixMilli and - Time.UnixMicro - methods return the number of milliseconds and microseconds elapsed since - January 1, 1970 UTC respectively. -
    - The new UnixMilli and - UnixMicro functions - return the local Time corresponding to the given Unix time. -

    - -

    - The package now accepts comma "," as a separator for fractional seconds when parsing and formatting time. - The following time formats are now accepted: -

      -
    • 2006-01-02 14:06:03,999999999 -0700 MST
      • -
    • Mon Jan _2 14:06:03,120007 2006
      • -
    • Mon Jan 2 14:06:03,120007 2006
      • -
    -

    - -

    - The new constant Layout - defines the reference time. -

    -
    -
    - -
    unicode
    -
    -

    - The Is, - IsGraphic, - IsLetter, - IsLower, - IsMark, - IsNumber, - IsPrint, - IsPunct, - IsSpace, - IsSymbol, and - IsUpper functions - now return false on negative rune values, as they do for other invalid runes. -

    -
    -
    diff --git a/doc/go1.18.html b/doc/go1.18.html new file mode 100644 index 0000000000000000000000000000000000000000..df4b56c49fbd97fed1dacafb0e8891bd8f1bf247 --- /dev/null +++ b/doc/go1.18.html @@ -0,0 +1,101 @@ + + + + + + +

    DRAFT RELEASE NOTES — Introduction to Go 1.18

    + +

    + + Go 1.18 is not yet released. These are work-in-progress + release notes. Go 1.18 is expected to be released in February 2022. + +

    + +

    Changes to the language

    + +

    + TODO: complete this section +

    + +

    Ports

    + +

    + TODO: complete this section, or delete if not needed +

    + +

    Tools

    + +

    + TODO: complete this section, or delete if not needed +

    + +

    Go command

    + +

    + TODO: complete this section, or delete if not needed +

    + +

    Runtime

    + +

    + TODO: complete this section, or delete if not needed +

    + +

    Compiler

    + +

    + TODO: complete this section, or delete if not needed +

    + +

    Linker

    + +

    + TODO: complete this section, or delete if not needed +

    + +

    Core library

    + +

    + TODO: complete this section +

    + +

    Minor changes to the library

    + +

    + As always, there are various minor changes and updates to the library, + made with the Go 1 promise of compatibility + in mind. +

    + +

    + TODO: complete this section +

    + +
    syscall
    +
    +

    + The new function SyscallN + has been introduced for Windows, allowing for calls with arbitrary number + of arguments. As results, + Syscall, + Syscall6, + Syscall9, + Syscall12, + Syscall15, and + Syscall18 are + deprecated in favor of SyscallN. +

    +
    +
    \ No newline at end of file diff --git a/doc/go_spec.html b/doc/go_spec.html index 0e14a1f3b63188cbb945f22ad8896eb0f9b35268..22b616134ac48d24c2acefc637b0c8944c72401d 100644 --- a/doc/go_spec.html +++ b/doc/go_spec.html @@ -1,6 +1,6 @@ @@ -3000,6 +3000,18 @@ method value; the saved copy is then used as the receiver in any calls, which may be executed later.

    +
    +type S struct { *T }
+type T int
+func (t T) M() { print(t) }
+
+t := new(T)
+s := S{T: t}
+f := t.M                    // receiver *t is evaluated and stored in f
+g := s.M                    // receiver *(s.T) is evaluated and stored in g
+*t = 42                     // does not affect stored receivers in f and g
+
    +

    The type T may be an interface or non-interface type.

    @@ -4329,6 +4341,7 @@ a run-time panic occurs. 
     s := make([]byte, 2, 4)
 s0 := (*[0]byte)(s)      // s0 != nil
+s1 := (*[1]byte)(s[1:])  // &s1[0] == &s[1]
 s2 := (*[2]byte)(s)      // &s2[0] == &s[0]
 s4 := (*[4]byte)(s)      // panics: len([4]byte) > len(s)
 
diff --git a/lib/time/README b/lib/time/README
index aab4daa7e2df07e01a7318905eb35917d23d2bf5..0de06df13b9a4575a0f510e854d171878ec7b89d 100644
--- a/lib/time/README
+++ b/lib/time/README
@@ -4,7 +4,7 @@ The IANA asserts that the database is in the public domain.
 
 For more information, see
 https://www.iana.org/time-zones
-ftp://ftp.iana.org/tz/code/tz-link.htm
-http://tools.ietf.org/html/rfc6557
+ftp://ftp.iana.org/tz/code/tz-link.html
+https://datatracker.ietf.org/doc/html/rfc6557
 
 To rebuild the archive, read and run update.bash.
diff --git a/misc/cgo/errors/testdata/err2.go b/misc/cgo/errors/testdata/err2.go
index a90598fe35b6304434bba7253c29b1d62173dcc4..aa941584c3c2cfcaa7491f00733c4aa0244d674f 100644
--- a/misc/cgo/errors/testdata/err2.go
+++ b/misc/cgo/errors/testdata/err2.go
@@ -91,10 +91,18 @@ func main() {
 
 	// issue 26745
 	_ = func(i int) int {
-		return C.i + 1 // ERROR HERE: 14
+		// typecheck reports at column 14 ('+'), but types2 reports at
+		// column 10 ('C').
+		// TODO(mdempsky): Investigate why, and see if types2 can be
+		// updated to match typecheck behavior.
+		return C.i + 1 // ERROR HERE: \b(10|14)\b
 	}
 	_ = func(i int) {
-		C.fi(i) // ERROR HERE: 7
+		// typecheck reports at column 7 ('('), but types2 reports at
+		// column 8 ('i'). The types2 position is more correct, but
+		// updating typecheck here is fundamentally challenging because of
+		// IR limitations.
+		C.fi(i) // ERROR HERE: \b(7|8)\b
 	}
 
 	C.fi = C.fi // ERROR HERE
diff --git a/misc/cgo/gmp/fib.go b/misc/cgo/gmp/fib.go
index f1091b1c54f45e62187aa6a3776507a0af8e851c..f453fcf1843b7c13123398a212c0d8cc64935817 100644
--- a/misc/cgo/gmp/fib.go
+++ b/misc/cgo/gmp/fib.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 // Compute Fibonacci numbers with two goroutines
diff --git a/misc/cgo/gmp/pi.go b/misc/cgo/gmp/pi.go
index d5851e8e6bd389a0049d0369f960f1fc4014e090..5ea034900a9b172a92fc6b716135f6450c4f5767 100644
--- a/misc/cgo/gmp/pi.go
+++ b/misc/cgo/gmp/pi.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main
diff --git a/misc/cgo/test/cgo_thread_lock.go b/misc/cgo/test/cgo_thread_lock.go
index b1050685182287dd563a6d302ea819e1e6fbe138..3b9ac845493cd5cfd4d9a665e56e94cab2139956 100644
--- a/misc/cgo/test/cgo_thread_lock.go
+++ b/misc/cgo/test/cgo_thread_lock.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && freebsd && openbsd
 // +build linux,freebsd,openbsd
 
 package cgotest
diff --git a/misc/cgo/test/cgo_unix_test.go b/misc/cgo/test/cgo_unix_test.go
index e3d591664983befc0ef8b6bfe3f251f352f491d5..a324503a22faf06ac261c079cdb70e30c851c446 100644
--- a/misc/cgo/test/cgo_unix_test.go
+++ b/misc/cgo/test/cgo_unix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package cgotest
diff --git a/misc/cgo/test/issue18146.go b/misc/cgo/test/issue18146.go
index f92d6c7f939d22078a428f4ebfc8a80541cd0fdc..e50f9ae53016fce2f88e1b0118145635f41c19d5 100644
--- a/misc/cgo/test/issue18146.go
+++ b/misc/cgo/test/issue18146.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 // Issue 18146: pthread_create failure during syscall.Exec.
diff --git a/misc/cgo/test/issue21897.go b/misc/cgo/test/issue21897.go
index d13246bd84afdea8995c2e1ab2b5a2c69c2cc4ca..8f39252e688580af7bcd5525426cdd43dc7725a3 100644
--- a/misc/cgo/test/issue21897.go
+++ b/misc/cgo/test/issue21897.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin && cgo && !internal
 // +build darwin,cgo,!internal
 
 package cgotest
diff --git a/misc/cgo/test/issue21897b.go b/misc/cgo/test/issue21897b.go
index 08b5f4d808e240853d6b666ffd41ba2b5192d75f..50aece3528947ba2f8bd8ba2858628ffda1bf3fa 100644
--- a/misc/cgo/test/issue21897b.go
+++ b/misc/cgo/test/issue21897b.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !darwin || !cgo || internal
 // +build !darwin !cgo internal
 
 package cgotest
diff --git a/misc/cgo/test/issue4029.go b/misc/cgo/test/issue4029.go
index b2d131833a9377ac3643893b5aaa92cff4a179db..90ca08cbfb7da8b17d4b128aaf471a8dd546772f 100644
--- a/misc/cgo/test/issue4029.go
+++ b/misc/cgo/test/issue4029.go
@@ -2,7 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !windows,!static
+//go:build !windows && !static && (!darwin || (!internal_pie && !arm64))
+// +build !windows
+// +build !static
 // +build !darwin !internal_pie,!arm64
 
 // Excluded in darwin internal linking PIE mode, as dynamic export is not
diff --git a/misc/cgo/test/issue4029w.go b/misc/cgo/test/issue4029w.go
index b969bdd0fe8702a74ddfdf8bd72dfde97abe46ca..c2f59485e490d6aec158fddda918bfddf618253e 100644
--- a/misc/cgo/test/issue4029w.go
+++ b/misc/cgo/test/issue4029w.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows || static || (darwin && internal_pie) || (darwin && arm64)
 // +build windows static darwin,internal_pie darwin,arm64
 
 package cgotest
diff --git a/misc/cgo/test/issue8517.go b/misc/cgo/test/issue8517.go
index 4e431df921d1e33d4ca79faf9ea26e302a4aa6d9..7316ab0335d5cb587a50c90fa83ede25db8d649b 100644
--- a/misc/cgo/test/issue8517.go
+++ b/misc/cgo/test/issue8517.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package cgotest
diff --git a/misc/cgo/test/issue8694.go b/misc/cgo/test/issue8694.go
index 89be7ea090763a909e810bbcff1ebf4a67da6986..19071ce1595ec74a4f588ac9e274960dc0693337 100644
--- a/misc/cgo/test/issue8694.go
+++ b/misc/cgo/test/issue8694.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !android
 // +build !android
 
 package cgotest
diff --git a/misc/cgo/test/sigaltstack.go b/misc/cgo/test/sigaltstack.go
index 034cc4b3719150c379d97c0f1efa9bc7ce4747c9..6b371897a73471812c674d44c13d07fcc738c8ed 100644
--- a/misc/cgo/test/sigaltstack.go
+++ b/misc/cgo/test/sigaltstack.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows && !android
 // +build !windows,!android
 
 // Test that the Go runtime still works if C code changes the signal stack.
diff --git a/misc/cgo/test/sigprocmask.go b/misc/cgo/test/sigprocmask.go
index e2b939f05e2b4b61166f180ccd4548549765e67a..983734cc7b620c16e9a55d4449a8b829e5667d27 100644
--- a/misc/cgo/test/sigprocmask.go
+++ b/misc/cgo/test/sigprocmask.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package cgotest
diff --git a/misc/cgo/test/test_unix.go b/misc/cgo/test/test_unix.go
index 4a234469dbc6e0d826392b85447893d734fdaa5d..831b9ca625a1fbb354c30fa5da3c7358b7cc45ba 100644
--- a/misc/cgo/test/test_unix.go
+++ b/misc/cgo/test/test_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package cgotest
diff --git a/misc/cgo/test/testdata/issue43639.go b/misc/cgo/test/testdata/issue43639.go
new file mode 100644
index 0000000000000000000000000000000000000000..e755fbd4bc005f4f8289bfa726559f2cb4d8c07f
--- /dev/null
+++ b/misc/cgo/test/testdata/issue43639.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgotest
+
+// Issue 43639: No runtime test needed, make sure package cgotest/issue43639 compiles well.
+
+import _ "cgotest/issue43639"
diff --git a/misc/cgo/test/testdata/issue43639/a.go b/misc/cgo/test/testdata/issue43639/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..fe37d5e4b0f00d2feb9b4ddaccea6cbfc91d9876
--- /dev/null
+++ b/misc/cgo/test/testdata/issue43639/a.go
@@ -0,0 +1,8 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package issue43639
+
+// #cgo CFLAGS: -W -Wall -Werror
+import "C"
diff --git a/misc/cgo/testsanitizers/msan_test.go b/misc/cgo/testsanitizers/msan_test.go
index 2a3494fbfc1d3f4eff846a0f9582440c49e1db97..5ee9947a58504faa5f94e22b6419a7c46e882948 100644
--- a/misc/cgo/testsanitizers/msan_test.go
+++ b/misc/cgo/testsanitizers/msan_test.go
@@ -42,6 +42,7 @@ func TestMSAN(t *testing.T) {
 		{src: "msan5.go"},
 		{src: "msan6.go"},
 		{src: "msan7.go"},
+		{src: "msan8.go"},
 		{src: "msan_fail.go", wantErr: true},
 	}
 	for _, tc := range cases {
diff --git a/misc/cgo/testsanitizers/testdata/msan8.go b/misc/cgo/testsanitizers/testdata/msan8.go
new file mode 100644
index 0000000000000000000000000000000000000000..1cb5c5677fa758711ae44a6d04e3fdcccbe6c00e
--- /dev/null
+++ b/misc/cgo/testsanitizers/testdata/msan8.go
@@ -0,0 +1,109 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+/*
+#include 
+#include 
+#include 
+
+#include 
+
+// cgoTracebackArg is the type of the argument passed to msanGoTraceback.
+struct cgoTracebackArg {
+	uintptr_t context;
+	uintptr_t sigContext;
+	uintptr_t* buf;
+	uintptr_t max;
+};
+
+// msanGoTraceback is registered as the cgo traceback function.
+// This will be called when a signal occurs.
+void msanGoTraceback(void* parg) {
+	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
+        arg->buf[0] = 0;
+}
+
+// msanGoWait will be called with all registers undefined as far as
+// msan is concerned. It just waits for a signal.
+// Because the registers are msan-undefined, the signal handler will
+// be invoked with all registers msan-undefined.
+__attribute__((noinline))
+void msanGoWait(unsigned long a1, unsigned long a2, unsigned long a3, unsigned long a4, unsigned long a5, unsigned long a6) {
+	sigset_t mask;
+
+	sigemptyset(&mask);
+        sigsuspend(&mask);
+}
+
+// msanGoSignalThread is the thread ID of the msanGoLoop thread.
+static pthread_t msanGoSignalThread;
+
+// msanGoSignalThreadSet is used to record that msanGoSignalThread
+// has been initialized. This is accessed atomically.
+static int32_t msanGoSignalThreadSet;
+
+// uninit is explicitly poisoned, so that we can make all registers
+// undefined by calling msanGoWait.
+static unsigned long uninit;
+
+// msanGoLoop loops calling msanGoWait, with the arguments passed
+// such that msan thinks that they are undefined. msan permits
+// undefined values to be used as long as they are not used to
+// for conditionals or for memory access.
+void msanGoLoop() {
+	int i;
+
+	msanGoSignalThread = pthread_self();
+        __atomic_store_n(&msanGoSignalThreadSet, 1, __ATOMIC_SEQ_CST);
+
+	// Force uninit to be undefined for msan.
+	__msan_poison(&uninit, sizeof uninit);
+	for (i = 0; i < 100; i++) {
+		msanGoWait(uninit, uninit, uninit, uninit, uninit, uninit);
+        }
+}
+
+// msanGoReady returns whether msanGoSignalThread is set.
+int msanGoReady() {
+	return __atomic_load_n(&msanGoSignalThreadSet, __ATOMIC_SEQ_CST) != 0;
+}
+
+// msanGoSendSignal sends a signal to the msanGoLoop thread.
+void msanGoSendSignal() {
+	pthread_kill(msanGoSignalThread, SIGWINCH);
+}
+*/
+import "C"
+
+import (
+	"runtime"
+	"time"
+)
+
+func main() {
+	runtime.SetCgoTraceback(0, C.msanGoTraceback, nil, nil)
+
+	c := make(chan bool)
+	go func() {
+		defer func() { c <- true }()
+		C.msanGoLoop()
+	}()
+
+	for C.msanGoReady() == 0 {
+		time.Sleep(time.Microsecond)
+	}
+
+loop:
+	for {
+		select {
+		case <-c:
+			break loop
+		default:
+			C.msanGoSendSignal()
+			time.Sleep(time.Microsecond)
+		}
+	}
+}
diff --git a/misc/cgo/testso/noso_test.go b/misc/cgo/testso/noso_test.go
index c88aebfb02a91e13bf366973494413a9bab7d47c..1014534d62cf06962c4f17b96ebc3cfe896ded29 100644
--- a/misc/cgo/testso/noso_test.go
+++ b/misc/cgo/testso/noso_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !cgo
 // +build !cgo
 
 package so_test
diff --git a/misc/cgo/testsovar/noso_test.go b/misc/cgo/testsovar/noso_test.go
index c88aebfb02a91e13bf366973494413a9bab7d47c..1014534d62cf06962c4f17b96ebc3cfe896ded29 100644
--- a/misc/cgo/testsovar/noso_test.go
+++ b/misc/cgo/testsovar/noso_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !cgo
 // +build !cgo
 
 package so_test
diff --git a/misc/cgo/testtls/tls_test.go b/misc/cgo/testtls/tls_test.go
index 3076c2d5943b5cbc1482f504e7bbbe016ac71642..a3b67c004413aafcf305109fb893dd5ed0de09c8 100644
--- a/misc/cgo/testtls/tls_test.go
+++ b/misc/cgo/testtls/tls_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package cgotlstest
diff --git a/src/archive/tar/common.go b/src/archive/tar/common.go
index c667cfc8720b5b9db1a72184bd9fb42461916ec0..595de64725ae6ba09eef3c301d048544b37a9734 100644
--- a/src/archive/tar/common.go
+++ b/src/archive/tar/common.go
@@ -316,10 +316,10 @@ func invertSparseEntries(src []sparseEntry, size int64) []sparseEntry {
 // fileState tracks the number of logical (includes sparse holes) and physical
 // (actual in tar archive) bytes remaining for the current file.
 //
-// Invariant: LogicalRemaining >= PhysicalRemaining
+// Invariant: logicalRemaining >= physicalRemaining
 type fileState interface {
-	LogicalRemaining() int64
-	PhysicalRemaining() int64
+	logicalRemaining() int64
+	physicalRemaining() int64
 }
 
 // allowedFormats determines which formats can be used.
@@ -413,22 +413,22 @@ func (h Header) allowedFormats() (format Format, paxHdrs map[string]string, err
 
 	// Check basic fields.
 	var blk block
-	v7 := blk.V7()
-	ustar := blk.USTAR()
-	gnu := blk.GNU()
-	verifyString(h.Name, len(v7.Name()), "Name", paxPath)
-	verifyString(h.Linkname, len(v7.LinkName()), "Linkname", paxLinkpath)
-	verifyString(h.Uname, len(ustar.UserName()), "Uname", paxUname)
-	verifyString(h.Gname, len(ustar.GroupName()), "Gname", paxGname)
-	verifyNumeric(h.Mode, len(v7.Mode()), "Mode", paxNone)
-	verifyNumeric(int64(h.Uid), len(v7.UID()), "Uid", paxUid)
-	verifyNumeric(int64(h.Gid), len(v7.GID()), "Gid", paxGid)
-	verifyNumeric(h.Size, len(v7.Size()), "Size", paxSize)
-	verifyNumeric(h.Devmajor, len(ustar.DevMajor()), "Devmajor", paxNone)
-	verifyNumeric(h.Devminor, len(ustar.DevMinor()), "Devminor", paxNone)
-	verifyTime(h.ModTime, len(v7.ModTime()), "ModTime", paxMtime)
-	verifyTime(h.AccessTime, len(gnu.AccessTime()), "AccessTime", paxAtime)
-	verifyTime(h.ChangeTime, len(gnu.ChangeTime()), "ChangeTime", paxCtime)
+	v7 := blk.toV7()
+	ustar := blk.toUSTAR()
+	gnu := blk.toGNU()
+	verifyString(h.Name, len(v7.name()), "Name", paxPath)
+	verifyString(h.Linkname, len(v7.linkName()), "Linkname", paxLinkpath)
+	verifyString(h.Uname, len(ustar.userName()), "Uname", paxUname)
+	verifyString(h.Gname, len(ustar.groupName()), "Gname", paxGname)
+	verifyNumeric(h.Mode, len(v7.mode()), "Mode", paxNone)
+	verifyNumeric(int64(h.Uid), len(v7.uid()), "Uid", paxUid)
+	verifyNumeric(int64(h.Gid), len(v7.gid()), "Gid", paxGid)
+	verifyNumeric(h.Size, len(v7.size()), "Size", paxSize)
+	verifyNumeric(h.Devmajor, len(ustar.devMajor()), "Devmajor", paxNone)
+	verifyNumeric(h.Devminor, len(ustar.devMinor()), "Devminor", paxNone)
+	verifyTime(h.ModTime, len(v7.modTime()), "ModTime", paxMtime)
+	verifyTime(h.AccessTime, len(gnu.accessTime()), "AccessTime", paxAtime)
+	verifyTime(h.ChangeTime, len(gnu.changeTime()), "ChangeTime", paxCtime)
 
 	// Check for header-only types.
 	var whyOnlyPAX, whyOnlyGNU string
diff --git a/src/archive/tar/format.go b/src/archive/tar/format.go
index cfe24a5e1d339540c26feb898bfa6ce09d1813d8..21b9d9d4dbc628f7f18a370d7bb10f597b0efc70 100644
--- a/src/archive/tar/format.go
+++ b/src/archive/tar/format.go
@@ -156,28 +156,28 @@ var zeroBlock block
 type block [blockSize]byte
 
 // Convert block to any number of formats.
-func (b *block) V7() *headerV7       { return (*headerV7)(b) }
-func (b *block) GNU() *headerGNU     { return (*headerGNU)(b) }
-func (b *block) STAR() *headerSTAR   { return (*headerSTAR)(b) }
-func (b *block) USTAR() *headerUSTAR { return (*headerUSTAR)(b) }
-func (b *block) Sparse() sparseArray { return sparseArray(b[:]) }
+func (b *block) toV7() *headerV7       { return (*headerV7)(b) }
+func (b *block) toGNU() *headerGNU     { return (*headerGNU)(b) }
+func (b *block) toSTAR() *headerSTAR   { return (*headerSTAR)(b) }
+func (b *block) toUSTAR() *headerUSTAR { return (*headerUSTAR)(b) }
+func (b *block) toSparse() sparseArray { return sparseArray(b[:]) }
 
 // GetFormat checks that the block is a valid tar header based on the checksum.
 // It then attempts to guess the specific format based on magic values.
 // If the checksum fails, then FormatUnknown is returned.
-func (b *block) GetFormat() Format {
+func (b *block) getFormat() Format {
 	// Verify checksum.
 	var p parser
-	value := p.parseOctal(b.V7().Chksum())
-	chksum1, chksum2 := b.ComputeChecksum()
+	value := p.parseOctal(b.toV7().chksum())
+	chksum1, chksum2 := b.computeChecksum()
 	if p.err != nil || (value != chksum1 && value != chksum2) {
 		return FormatUnknown
 	}
 
 	// Guess the magic values.
-	magic := string(b.USTAR().Magic())
-	version := string(b.USTAR().Version())
-	trailer := string(b.STAR().Trailer())
+	magic := string(b.toUSTAR().magic())
+	version := string(b.toUSTAR().version())
+	trailer := string(b.toSTAR().trailer())
 	switch {
 	case magic == magicUSTAR && trailer == trailerSTAR:
 		return formatSTAR
@@ -190,23 +190,23 @@ func (b *block) GetFormat() Format {
 	}
 }
 
-// SetFormat writes the magic values necessary for specified format
+// setFormat writes the magic values necessary for specified format
 // and then updates the checksum accordingly.
-func (b *block) SetFormat(format Format) {
+func (b *block) setFormat(format Format) {
 	// Set the magic values.
 	switch {
 	case format.has(formatV7):
 		// Do nothing.
 	case format.has(FormatGNU):
-		copy(b.GNU().Magic(), magicGNU)
-		copy(b.GNU().Version(), versionGNU)
+		copy(b.toGNU().magic(), magicGNU)
+		copy(b.toGNU().version(), versionGNU)
 	case format.has(formatSTAR):
-		copy(b.STAR().Magic(), magicUSTAR)
-		copy(b.STAR().Version(), versionUSTAR)
-		copy(b.STAR().Trailer(), trailerSTAR)
+		copy(b.toSTAR().magic(), magicUSTAR)
+		copy(b.toSTAR().version(), versionUSTAR)
+		copy(b.toSTAR().trailer(), trailerSTAR)
 	case format.has(FormatUSTAR | FormatPAX):
-		copy(b.USTAR().Magic(), magicUSTAR)
-		copy(b.USTAR().Version(), versionUSTAR)
+		copy(b.toUSTAR().magic(), magicUSTAR)
+		copy(b.toUSTAR().version(), versionUSTAR)
 	default:
 		panic("invalid format")
 	}
@@ -214,17 +214,17 @@ func (b *block) SetFormat(format Format) {
 	// Update checksum.
 	// This field is special in that it is terminated by a NULL then space.
 	var f formatter
-	field := b.V7().Chksum()
-	chksum, _ := b.ComputeChecksum() // Possible values are 256..128776
+	field := b.toV7().chksum()
+	chksum, _ := b.computeChecksum() // Possible values are 256..128776
 	f.formatOctal(field[:7], chksum) // Never fails since 128776 < 262143
 	field[7] = ' '
 }
 
-// ComputeChecksum computes the checksum for the header block.
+// computeChecksum computes the checksum for the header block.
 // POSIX specifies a sum of the unsigned byte values, but the Sun tar used
 // signed byte values.
 // We compute and return both.
-func (b *block) ComputeChecksum() (unsigned, signed int64) {
+func (b *block) computeChecksum() (unsigned, signed int64) {
 	for i, c := range b {
 		if 148 <= i && i < 156 {
 			c = ' ' // Treat the checksum field itself as all spaces.
@@ -236,68 +236,68 @@ func (b *block) ComputeChecksum() (unsigned, signed int64) {
 }
 
 // Reset clears the block with all zeros.
-func (b *block) Reset() {
+func (b *block) reset() {
 	*b = block{}
 }
 
 type headerV7 [blockSize]byte
 
-func (h *headerV7) Name() []byte     { return h[000:][:100] }
-func (h *headerV7) Mode() []byte     { return h[100:][:8] }
-func (h *headerV7) UID() []byte      { return h[108:][:8] }
-func (h *headerV7) GID() []byte      { return h[116:][:8] }
-func (h *headerV7) Size() []byte     { return h[124:][:12] }
-func (h *headerV7) ModTime() []byte  { return h[136:][:12] }
-func (h *headerV7) Chksum() []byte   { return h[148:][:8] }
-func (h *headerV7) TypeFlag() []byte { return h[156:][:1] }
-func (h *headerV7) LinkName() []byte { return h[157:][:100] }
+func (h *headerV7) name() []byte     { return h[000:][:100] }
+func (h *headerV7) mode() []byte     { return h[100:][:8] }
+func (h *headerV7) uid() []byte      { return h[108:][:8] }
+func (h *headerV7) gid() []byte      { return h[116:][:8] }
+func (h *headerV7) size() []byte     { return h[124:][:12] }
+func (h *headerV7) modTime() []byte  { return h[136:][:12] }
+func (h *headerV7) chksum() []byte   { return h[148:][:8] }
+func (h *headerV7) typeFlag() []byte { return h[156:][:1] }
+func (h *headerV7) linkName() []byte { return h[157:][:100] }
 
 type headerGNU [blockSize]byte
 
-func (h *headerGNU) V7() *headerV7       { return (*headerV7)(h) }
-func (h *headerGNU) Magic() []byte       { return h[257:][:6] }
-func (h *headerGNU) Version() []byte     { return h[263:][:2] }
-func (h *headerGNU) UserName() []byte    { return h[265:][:32] }
-func (h *headerGNU) GroupName() []byte   { return h[297:][:32] }
-func (h *headerGNU) DevMajor() []byte    { return h[329:][:8] }
-func (h *headerGNU) DevMinor() []byte    { return h[337:][:8] }
-func (h *headerGNU) AccessTime() []byte  { return h[345:][:12] }
-func (h *headerGNU) ChangeTime() []byte  { return h[357:][:12] }
-func (h *headerGNU) Sparse() sparseArray { return sparseArray(h[386:][:24*4+1]) }
-func (h *headerGNU) RealSize() []byte    { return h[483:][:12] }
+func (h *headerGNU) v7() *headerV7       { return (*headerV7)(h) }
+func (h *headerGNU) magic() []byte       { return h[257:][:6] }
+func (h *headerGNU) version() []byte     { return h[263:][:2] }
+func (h *headerGNU) userName() []byte    { return h[265:][:32] }
+func (h *headerGNU) groupName() []byte   { return h[297:][:32] }
+func (h *headerGNU) devMajor() []byte    { return h[329:][:8] }
+func (h *headerGNU) devMinor() []byte    { return h[337:][:8] }
+func (h *headerGNU) accessTime() []byte  { return h[345:][:12] }
+func (h *headerGNU) changeTime() []byte  { return h[357:][:12] }
+func (h *headerGNU) sparse() sparseArray { return sparseArray(h[386:][:24*4+1]) }
+func (h *headerGNU) realSize() []byte    { return h[483:][:12] }
 
 type headerSTAR [blockSize]byte
 
-func (h *headerSTAR) V7() *headerV7      { return (*headerV7)(h) }
-func (h *headerSTAR) Magic() []byte      { return h[257:][:6] }
-func (h *headerSTAR) Version() []byte    { return h[263:][:2] }
-func (h *headerSTAR) UserName() []byte   { return h[265:][:32] }
-func (h *headerSTAR) GroupName() []byte  { return h[297:][:32] }
-func (h *headerSTAR) DevMajor() []byte   { return h[329:][:8] }
-func (h *headerSTAR) DevMinor() []byte   { return h[337:][:8] }
-func (h *headerSTAR) Prefix() []byte     { return h[345:][:131] }
-func (h *headerSTAR) AccessTime() []byte { return h[476:][:12] }
-func (h *headerSTAR) ChangeTime() []byte { return h[488:][:12] }
-func (h *headerSTAR) Trailer() []byte    { return h[508:][:4] }
+func (h *headerSTAR) v7() *headerV7      { return (*headerV7)(h) }
+func (h *headerSTAR) magic() []byte      { return h[257:][:6] }
+func (h *headerSTAR) version() []byte    { return h[263:][:2] }
+func (h *headerSTAR) userName() []byte   { return h[265:][:32] }
+func (h *headerSTAR) groupName() []byte  { return h[297:][:32] }
+func (h *headerSTAR) devMajor() []byte   { return h[329:][:8] }
+func (h *headerSTAR) devMinor() []byte   { return h[337:][:8] }
+func (h *headerSTAR) prefix() []byte     { return h[345:][:131] }
+func (h *headerSTAR) accessTime() []byte { return h[476:][:12] }
+func (h *headerSTAR) changeTime() []byte { return h[488:][:12] }
+func (h *headerSTAR) trailer() []byte    { return h[508:][:4] }
 
 type headerUSTAR [blockSize]byte
 
-func (h *headerUSTAR) V7() *headerV7     { return (*headerV7)(h) }
-func (h *headerUSTAR) Magic() []byte     { return h[257:][:6] }
-func (h *headerUSTAR) Version() []byte   { return h[263:][:2] }
-func (h *headerUSTAR) UserName() []byte  { return h[265:][:32] }
-func (h *headerUSTAR) GroupName() []byte { return h[297:][:32] }
-func (h *headerUSTAR) DevMajor() []byte  { return h[329:][:8] }
-func (h *headerUSTAR) DevMinor() []byte  { return h[337:][:8] }
-func (h *headerUSTAR) Prefix() []byte    { return h[345:][:155] }
+func (h *headerUSTAR) v7() *headerV7     { return (*headerV7)(h) }
+func (h *headerUSTAR) magic() []byte     { return h[257:][:6] }
+func (h *headerUSTAR) version() []byte   { return h[263:][:2] }
+func (h *headerUSTAR) userName() []byte  { return h[265:][:32] }
+func (h *headerUSTAR) groupName() []byte { return h[297:][:32] }
+func (h *headerUSTAR) devMajor() []byte  { return h[329:][:8] }
+func (h *headerUSTAR) devMinor() []byte  { return h[337:][:8] }
+func (h *headerUSTAR) prefix() []byte    { return h[345:][:155] }
 
 type sparseArray []byte
 
-func (s sparseArray) Entry(i int) sparseElem { return sparseElem(s[i*24:]) }
-func (s sparseArray) IsExtended() []byte     { return s[24*s.MaxEntries():][:1] }
-func (s sparseArray) MaxEntries() int        { return len(s) / 24 }
+func (s sparseArray) entry(i int) sparseElem { return sparseElem(s[i*24:]) }
+func (s sparseArray) isExtended() []byte     { return s[24*s.maxEntries():][:1] }
+func (s sparseArray) maxEntries() int        { return len(s) / 24 }
 
 type sparseElem []byte
 
-func (s sparseElem) Offset() []byte { return s[00:][:12] }
-func (s sparseElem) Length() []byte { return s[12:][:12] }
+func (s sparseElem) offset() []byte { return s[00:][:12] }
+func (s sparseElem) length() []byte { return s[12:][:12] }
diff --git a/src/archive/tar/reader.go b/src/archive/tar/reader.go
index 1b1d5b46891b6bc972ed6bd9bfb1efc63eef1433..4b11909bc9527d37af905cba8c33f495b83893ca 100644
--- a/src/archive/tar/reader.go
+++ b/src/archive/tar/reader.go
@@ -65,7 +65,7 @@ func (tr *Reader) next() (*Header, error) {
 	format := FormatUSTAR | FormatPAX | FormatGNU
 	for {
 		// Discard the remainder of the file and any padding.
-		if err := discard(tr.r, tr.curr.PhysicalRemaining()); err != nil {
+		if err := discard(tr.r, tr.curr.physicalRemaining()); err != nil {
 			return nil, err
 		}
 		if _, err := tryReadFull(tr.r, tr.blk[:tr.pad]); err != nil {
@@ -355,7 +355,7 @@ func (tr *Reader) readHeader() (*Header, *block, error) {
 	}
 
 	// Verify the header matches a known format.
-	format := tr.blk.GetFormat()
+	format := tr.blk.getFormat()
 	if format == FormatUnknown {
 		return nil, nil, ErrHeader
 	}
@@ -364,30 +364,30 @@ func (tr *Reader) readHeader() (*Header, *block, error) {
 	hdr := new(Header)
 
 	// Unpack the V7 header.
-	v7 := tr.blk.V7()
-	hdr.Typeflag = v7.TypeFlag()[0]
-	hdr.Name = p.parseString(v7.Name())
-	hdr.Linkname = p.parseString(v7.LinkName())
-	hdr.Size = p.parseNumeric(v7.Size())
-	hdr.Mode = p.parseNumeric(v7.Mode())
-	hdr.Uid = int(p.parseNumeric(v7.UID()))
-	hdr.Gid = int(p.parseNumeric(v7.GID()))
-	hdr.ModTime = time.Unix(p.parseNumeric(v7.ModTime()), 0)
+	v7 := tr.blk.toV7()
+	hdr.Typeflag = v7.typeFlag()[0]
+	hdr.Name = p.parseString(v7.name())
+	hdr.Linkname = p.parseString(v7.linkName())
+	hdr.Size = p.parseNumeric(v7.size())
+	hdr.Mode = p.parseNumeric(v7.mode())
+	hdr.Uid = int(p.parseNumeric(v7.uid()))
+	hdr.Gid = int(p.parseNumeric(v7.gid()))
+	hdr.ModTime = time.Unix(p.parseNumeric(v7.modTime()), 0)
 
 	// Unpack format specific fields.
 	if format > formatV7 {
-		ustar := tr.blk.USTAR()
-		hdr.Uname = p.parseString(ustar.UserName())
-		hdr.Gname = p.parseString(ustar.GroupName())
-		hdr.Devmajor = p.parseNumeric(ustar.DevMajor())
-		hdr.Devminor = p.parseNumeric(ustar.DevMinor())
+		ustar := tr.blk.toUSTAR()
+		hdr.Uname = p.parseString(ustar.userName())
+		hdr.Gname = p.parseString(ustar.groupName())
+		hdr.Devmajor = p.parseNumeric(ustar.devMajor())
+		hdr.Devminor = p.parseNumeric(ustar.devMinor())
 
 		var prefix string
 		switch {
 		case format.has(FormatUSTAR | FormatPAX):
 			hdr.Format = format
-			ustar := tr.blk.USTAR()
-			prefix = p.parseString(ustar.Prefix())
+			ustar := tr.blk.toUSTAR()
+			prefix = p.parseString(ustar.prefix())
 
 			// For Format detection, check if block is properly formatted since
 			// the parser is more liberal than what USTAR actually permits.
@@ -396,23 +396,23 @@ func (tr *Reader) readHeader() (*Header, *block, error) {
 				hdr.Format = FormatUnknown // Non-ASCII characters in block.
 			}
 			nul := func(b []byte) bool { return int(b[len(b)-1]) == 0 }
-			if !(nul(v7.Size()) && nul(v7.Mode()) && nul(v7.UID()) && nul(v7.GID()) &&
-				nul(v7.ModTime()) && nul(ustar.DevMajor()) && nul(ustar.DevMinor())) {
+			if !(nul(v7.size()) && nul(v7.mode()) && nul(v7.uid()) && nul(v7.gid()) &&
+				nul(v7.modTime()) && nul(ustar.devMajor()) && nul(ustar.devMinor())) {
 				hdr.Format = FormatUnknown // Numeric fields must end in NUL
 			}
 		case format.has(formatSTAR):
-			star := tr.blk.STAR()
-			prefix = p.parseString(star.Prefix())
-			hdr.AccessTime = time.Unix(p.parseNumeric(star.AccessTime()), 0)
-			hdr.ChangeTime = time.Unix(p.parseNumeric(star.ChangeTime()), 0)
+			star := tr.blk.toSTAR()
+			prefix = p.parseString(star.prefix())
+			hdr.AccessTime = time.Unix(p.parseNumeric(star.accessTime()), 0)
+			hdr.ChangeTime = time.Unix(p.parseNumeric(star.changeTime()), 0)
 		case format.has(FormatGNU):
 			hdr.Format = format
 			var p2 parser
-			gnu := tr.blk.GNU()
-			if b := gnu.AccessTime(); b[0] != 0 {
+			gnu := tr.blk.toGNU()
+			if b := gnu.accessTime(); b[0] != 0 {
 				hdr.AccessTime = time.Unix(p2.parseNumeric(b), 0)
 			}
-			if b := gnu.ChangeTime(); b[0] != 0 {
+			if b := gnu.changeTime(); b[0] != 0 {
 				hdr.ChangeTime = time.Unix(p2.parseNumeric(b), 0)
 			}
 
@@ -439,8 +439,8 @@ func (tr *Reader) readHeader() (*Header, *block, error) {
 			// See https://golang.org/issues/21005
 			if p2.err != nil {
 				hdr.AccessTime, hdr.ChangeTime = time.Time{}, time.Time{}
-				ustar := tr.blk.USTAR()
-				if s := p.parseString(ustar.Prefix()); isASCII(s) {
+				ustar := tr.blk.toUSTAR()
+				if s := p.parseString(ustar.prefix()); isASCII(s) {
 					prefix = s
 				}
 				hdr.Format = FormatUnknown // Buggy file is not GNU
@@ -465,38 +465,38 @@ func (tr *Reader) readOldGNUSparseMap(hdr *Header, blk *block) (sparseDatas, err
 	// Make sure that the input format is GNU.
 	// Unfortunately, the STAR format also has a sparse header format that uses
 	// the same type flag but has a completely different layout.
-	if blk.GetFormat() != FormatGNU {
+	if blk.getFormat() != FormatGNU {
 		return nil, ErrHeader
 	}
 	hdr.Format.mayOnlyBe(FormatGNU)
 
 	var p parser
-	hdr.Size = p.parseNumeric(blk.GNU().RealSize())
+	hdr.Size = p.parseNumeric(blk.toGNU().realSize())
 	if p.err != nil {
 		return nil, p.err
 	}
-	s := blk.GNU().Sparse()
-	spd := make(sparseDatas, 0, s.MaxEntries())
+	s := blk.toGNU().sparse()
+	spd := make(sparseDatas, 0, s.maxEntries())
 	for {
-		for i := 0; i < s.MaxEntries(); i++ {
+		for i := 0; i < s.maxEntries(); i++ {
 			// This termination condition is identical to GNU and BSD tar.
-			if s.Entry(i).Offset()[0] == 0x00 {
+			if s.entry(i).offset()[0] == 0x00 {
 				break // Don't return, need to process extended headers (even if empty)
 			}
-			offset := p.parseNumeric(s.Entry(i).Offset())
-			length := p.parseNumeric(s.Entry(i).Length())
+			offset := p.parseNumeric(s.entry(i).offset())
+			length := p.parseNumeric(s.entry(i).length())
 			if p.err != nil {
 				return nil, p.err
 			}
 			spd = append(spd, sparseEntry{Offset: offset, Length: length})
 		}
 
-		if s.IsExtended()[0] > 0 {
+		if s.isExtended()[0] > 0 {
 			// There are more entries. Read an extension header and parse its entries.
 			if _, err := mustReadFull(tr.r, blk[:]); err != nil {
 				return nil, err
 			}
-			s = blk.Sparse()
+			s = blk.toSparse()
 			continue
 		}
 		return spd, nil // Done
@@ -678,11 +678,13 @@ func (fr *regFileReader) WriteTo(w io.Writer) (int64, error) {
 	return io.Copy(w, struct{ io.Reader }{fr})
 }
 
-func (fr regFileReader) LogicalRemaining() int64 {
+// logicalRemaining implements fileState.logicalRemaining.
+func (fr regFileReader) logicalRemaining() int64 {
 	return fr.nb
 }
 
-func (fr regFileReader) PhysicalRemaining() int64 {
+// logicalRemaining implements fileState.physicalRemaining.
+func (fr regFileReader) physicalRemaining() int64 {
 	return fr.nb
 }
 
@@ -694,9 +696,9 @@ type sparseFileReader struct {
 }
 
 func (sr *sparseFileReader) Read(b []byte) (n int, err error) {
-	finished := int64(len(b)) >= sr.LogicalRemaining()
+	finished := int64(len(b)) >= sr.logicalRemaining()
 	if finished {
-		b = b[:sr.LogicalRemaining()]
+		b = b[:sr.logicalRemaining()]
 	}
 
 	b0 := b
@@ -724,7 +726,7 @@ func (sr *sparseFileReader) Read(b []byte) (n int, err error) {
 		return n, errMissData // Less data in dense file than sparse file
 	case err != nil:
 		return n, err
-	case sr.LogicalRemaining() == 0 && sr.PhysicalRemaining() > 0:
+	case sr.logicalRemaining() == 0 && sr.physicalRemaining() > 0:
 		return n, errUnrefData // More data in dense file than sparse file
 	case finished:
 		return n, io.EOF
@@ -746,7 +748,7 @@ func (sr *sparseFileReader) WriteTo(w io.Writer) (n int64, err error) {
 
 	var writeLastByte bool
 	pos0 := sr.pos
-	for sr.LogicalRemaining() > 0 && !writeLastByte && err == nil {
+	for sr.logicalRemaining() > 0 && !writeLastByte && err == nil {
 		var nf int64 // Size of fragment
 		holeStart, holeEnd := sr.sp[0].Offset, sr.sp[0].endOffset()
 		if sr.pos < holeStart { // In a data fragment
@@ -754,7 +756,7 @@ func (sr *sparseFileReader) WriteTo(w io.Writer) (n int64, err error) {
 			nf, err = io.CopyN(ws, sr.fr, nf)
 		} else { // In a hole fragment
 			nf = holeEnd - sr.pos
-			if sr.PhysicalRemaining() == 0 {
+			if sr.physicalRemaining() == 0 {
 				writeLastByte = true
 				nf--
 			}
@@ -779,18 +781,18 @@ func (sr *sparseFileReader) WriteTo(w io.Writer) (n int64, err error) {
 		return n, errMissData // Less data in dense file than sparse file
 	case err != nil:
 		return n, err
-	case sr.LogicalRemaining() == 0 && sr.PhysicalRemaining() > 0:
+	case sr.logicalRemaining() == 0 && sr.physicalRemaining() > 0:
 		return n, errUnrefData // More data in dense file than sparse file
 	default:
 		return n, nil
 	}
 }
 
-func (sr sparseFileReader) LogicalRemaining() int64 {
+func (sr sparseFileReader) logicalRemaining() int64 {
 	return sr.sp[len(sr.sp)-1].endOffset() - sr.pos
 }
-func (sr sparseFileReader) PhysicalRemaining() int64 {
-	return sr.fr.PhysicalRemaining()
+func (sr sparseFileReader) physicalRemaining() int64 {
+	return sr.fr.physicalRemaining()
 }
 
 type zeroReader struct{}
diff --git a/src/archive/tar/reader_test.go b/src/archive/tar/reader_test.go
index 789ddc1bc0345ae95058f6fafa7311b54c5f6c25..c31a847ec3e9db714ff59b6029f70930dac90e78 100644
--- a/src/archive/tar/reader_test.go
+++ b/src/archive/tar/reader_test.go
@@ -1021,12 +1021,12 @@ func TestParsePAX(t *testing.T) {
 
 func TestReadOldGNUSparseMap(t *testing.T) {
 	populateSparseMap := func(sa sparseArray, sps []string) []string {
-		for i := 0; len(sps) > 0 && i < sa.MaxEntries(); i++ {
-			copy(sa.Entry(i), sps[0])
+		for i := 0; len(sps) > 0 && i < sa.maxEntries(); i++ {
+			copy(sa.entry(i), sps[0])
 			sps = sps[1:]
 		}
 		if len(sps) > 0 {
-			copy(sa.IsExtended(), "\x80")
+			copy(sa.isExtended(), "\x80")
 		}
 		return sps
 	}
@@ -1034,19 +1034,19 @@ func TestReadOldGNUSparseMap(t *testing.T) {
 	makeInput := func(format Format, size string, sps ...string) (out []byte) {
 		// Write the initial GNU header.
 		var blk block
-		gnu := blk.GNU()
-		sparse := gnu.Sparse()
-		copy(gnu.RealSize(), size)
+		gnu := blk.toGNU()
+		sparse := gnu.sparse()
+		copy(gnu.realSize(), size)
 		sps = populateSparseMap(sparse, sps)
 		if format != FormatUnknown {
-			blk.SetFormat(format)
+			blk.setFormat(format)
 		}
 		out = append(out, blk[:]...)
 
 		// Write extended sparse blocks.
 		for len(sps) > 0 {
 			var blk block
-			sps = populateSparseMap(blk.Sparse(), sps)
+			sps = populateSparseMap(blk.toSparse(), sps)
 			out = append(out, blk[:]...)
 		}
 		return out
@@ -1359,7 +1359,7 @@ func TestFileReader(t *testing.T) {
 			wantCnt int64
 			wantErr error
 		}
-		testRemaining struct { // LogicalRemaining() == wantLCnt, PhysicalRemaining() == wantPCnt
+		testRemaining struct { // logicalRemaining() == wantLCnt, physicalRemaining() == wantPCnt
 			wantLCnt int64
 			wantPCnt int64
 		}
@@ -1596,11 +1596,11 @@ func TestFileReader(t *testing.T) {
 					t.Errorf("test %d.%d, expected %d more operations", i, j, len(f.ops))
 				}
 			case testRemaining:
-				if got := fr.LogicalRemaining(); got != tf.wantLCnt {
-					t.Errorf("test %d.%d, LogicalRemaining() = %d, want %d", i, j, got, tf.wantLCnt)
+				if got := fr.logicalRemaining(); got != tf.wantLCnt {
+					t.Errorf("test %d.%d, logicalRemaining() = %d, want %d", i, j, got, tf.wantLCnt)
 				}
-				if got := fr.PhysicalRemaining(); got != tf.wantPCnt {
-					t.Errorf("test %d.%d, PhysicalRemaining() = %d, want %d", i, j, got, tf.wantPCnt)
+				if got := fr.physicalRemaining(); got != tf.wantPCnt {
+					t.Errorf("test %d.%d, physicalRemaining() = %d, want %d", i, j, got, tf.wantPCnt)
 				}
 			default:
 				t.Fatalf("test %d.%d, unknown test operation: %T", i, j, tf)
diff --git a/src/archive/tar/writer.go b/src/archive/tar/writer.go
index e80498d03e39c0699a4f6d51c91fd4dda471ffa4..3729f7e82c192f685e43398a88d2777bde5c17e0 100644
--- a/src/archive/tar/writer.go
+++ b/src/archive/tar/writer.go
@@ -50,7 +50,7 @@ func (tw *Writer) Flush() error {
 	if tw.err != nil {
 		return tw.err
 	}
-	if nb := tw.curr.LogicalRemaining(); nb > 0 {
+	if nb := tw.curr.logicalRemaining(); nb > 0 {
 		return fmt.Errorf("archive/tar: missed writing %d bytes", nb)
 	}
 	if _, tw.err = tw.w.Write(zeroBlock[:tw.pad]); tw.err != nil {
@@ -117,8 +117,8 @@ func (tw *Writer) writeUSTARHeader(hdr *Header) error {
 	// Pack the main header.
 	var f formatter
 	blk := tw.templateV7Plus(hdr, f.formatString, f.formatOctal)
-	f.formatString(blk.USTAR().Prefix(), namePrefix)
-	blk.SetFormat(FormatUSTAR)
+	f.formatString(blk.toUSTAR().prefix(), namePrefix)
+	blk.setFormat(FormatUSTAR)
 	if f.err != nil {
 		return f.err // Should never happen since header is validated
 	}
@@ -208,7 +208,7 @@ func (tw *Writer) writePAXHeader(hdr *Header, paxHdrs map[string]string) error {
 	var f formatter // Ignore errors since they are expected
 	fmtStr := func(b []byte, s string) { f.formatString(b, toASCII(s)) }
 	blk := tw.templateV7Plus(hdr, fmtStr, f.formatOctal)
-	blk.SetFormat(FormatPAX)
+	blk.setFormat(FormatPAX)
 	if err := tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag); err != nil {
 		return err
 	}
@@ -250,10 +250,10 @@ func (tw *Writer) writeGNUHeader(hdr *Header) error {
 	var spb []byte
 	blk := tw.templateV7Plus(hdr, f.formatString, f.formatNumeric)
 	if !hdr.AccessTime.IsZero() {
-		f.formatNumeric(blk.GNU().AccessTime(), hdr.AccessTime.Unix())
+		f.formatNumeric(blk.toGNU().accessTime(), hdr.AccessTime.Unix())
 	}
 	if !hdr.ChangeTime.IsZero() {
-		f.formatNumeric(blk.GNU().ChangeTime(), hdr.ChangeTime.Unix())
+		f.formatNumeric(blk.toGNU().changeTime(), hdr.ChangeTime.Unix())
 	}
 	// TODO(dsnet): Re-enable this when adding sparse support.
 	// See https://golang.org/issue/22735
@@ -293,7 +293,7 @@ func (tw *Writer) writeGNUHeader(hdr *Header) error {
 			f.formatNumeric(blk.GNU().RealSize(), realSize)
 		}
 	*/
-	blk.SetFormat(FormatGNU)
+	blk.setFormat(FormatGNU)
 	if err := tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag); err != nil {
 		return err
 	}
@@ -321,28 +321,28 @@ type (
 // The block returned is only valid until the next call to
 // templateV7Plus or writeRawFile.
 func (tw *Writer) templateV7Plus(hdr *Header, fmtStr stringFormatter, fmtNum numberFormatter) *block {
-	tw.blk.Reset()
+	tw.blk.reset()
 
 	modTime := hdr.ModTime
 	if modTime.IsZero() {
 		modTime = time.Unix(0, 0)
 	}
 
-	v7 := tw.blk.V7()
-	v7.TypeFlag()[0] = hdr.Typeflag
-	fmtStr(v7.Name(), hdr.Name)
-	fmtStr(v7.LinkName(), hdr.Linkname)
-	fmtNum(v7.Mode(), hdr.Mode)
-	fmtNum(v7.UID(), int64(hdr.Uid))
-	fmtNum(v7.GID(), int64(hdr.Gid))
-	fmtNum(v7.Size(), hdr.Size)
-	fmtNum(v7.ModTime(), modTime.Unix())
+	v7 := tw.blk.toV7()
+	v7.typeFlag()[0] = hdr.Typeflag
+	fmtStr(v7.name(), hdr.Name)
+	fmtStr(v7.linkName(), hdr.Linkname)
+	fmtNum(v7.mode(), hdr.Mode)
+	fmtNum(v7.uid(), int64(hdr.Uid))
+	fmtNum(v7.gid(), int64(hdr.Gid))
+	fmtNum(v7.size(), hdr.Size)
+	fmtNum(v7.modTime(), modTime.Unix())
 
-	ustar := tw.blk.USTAR()
-	fmtStr(ustar.UserName(), hdr.Uname)
-	fmtStr(ustar.GroupName(), hdr.Gname)
-	fmtNum(ustar.DevMajor(), hdr.Devmajor)
-	fmtNum(ustar.DevMinor(), hdr.Devminor)
+	ustar := tw.blk.toUSTAR()
+	fmtStr(ustar.userName(), hdr.Uname)
+	fmtStr(ustar.groupName(), hdr.Gname)
+	fmtNum(ustar.devMajor(), hdr.Devmajor)
+	fmtNum(ustar.devMinor(), hdr.Devminor)
 
 	return &tw.blk
 }
@@ -351,7 +351,7 @@ func (tw *Writer) templateV7Plus(hdr *Header, fmtStr stringFormatter, fmtNum num
 // It uses format to encode the header format and will write data as the body.
 // It uses default values for all of the other fields (as BSD and GNU tar does).
 func (tw *Writer) writeRawFile(name, data string, flag byte, format Format) error {
-	tw.blk.Reset()
+	tw.blk.reset()
 
 	// Best effort for the filename.
 	name = toASCII(name)
@@ -361,15 +361,15 @@ func (tw *Writer) writeRawFile(name, data string, flag byte, format Format) erro
 	name = strings.TrimRight(name, "/")
 
 	var f formatter
-	v7 := tw.blk.V7()
-	v7.TypeFlag()[0] = flag
-	f.formatString(v7.Name(), name)
-	f.formatOctal(v7.Mode(), 0)
-	f.formatOctal(v7.UID(), 0)
-	f.formatOctal(v7.GID(), 0)
-	f.formatOctal(v7.Size(), int64(len(data))) // Must be < 8GiB
-	f.formatOctal(v7.ModTime(), 0)
-	tw.blk.SetFormat(format)
+	v7 := tw.blk.toV7()
+	v7.typeFlag()[0] = flag
+	f.formatString(v7.name(), name)
+	f.formatOctal(v7.mode(), 0)
+	f.formatOctal(v7.uid(), 0)
+	f.formatOctal(v7.gid(), 0)
+	f.formatOctal(v7.size(), int64(len(data))) // Must be < 8GiB
+	f.formatOctal(v7.modTime(), 0)
+	tw.blk.setFormat(format)
 	if f.err != nil {
 		return f.err // Only occurs if size condition is violated
 	}
@@ -511,10 +511,13 @@ func (fw *regFileWriter) ReadFrom(r io.Reader) (int64, error) {
 	return io.Copy(struct{ io.Writer }{fw}, r)
 }
 
-func (fw regFileWriter) LogicalRemaining() int64 {
+// logicalRemaining implements fileState.logicalRemaining.
+func (fw regFileWriter) logicalRemaining() int64 {
 	return fw.nb
 }
-func (fw regFileWriter) PhysicalRemaining() int64 {
+
+// logicalRemaining implements fileState.physicalRemaining.
+func (fw regFileWriter) physicalRemaining() int64 {
 	return fw.nb
 }
 
@@ -526,9 +529,9 @@ type sparseFileWriter struct {
 }
 
 func (sw *sparseFileWriter) Write(b []byte) (n int, err error) {
-	overwrite := int64(len(b)) > sw.LogicalRemaining()
+	overwrite := int64(len(b)) > sw.logicalRemaining()
 	if overwrite {
-		b = b[:sw.LogicalRemaining()]
+		b = b[:sw.logicalRemaining()]
 	}
 
 	b0 := b
@@ -556,7 +559,7 @@ func (sw *sparseFileWriter) Write(b []byte) (n int, err error) {
 		return n, errMissData // Not possible; implies bug in validation logic
 	case err != nil:
 		return n, err
-	case sw.LogicalRemaining() == 0 && sw.PhysicalRemaining() > 0:
+	case sw.logicalRemaining() == 0 && sw.physicalRemaining() > 0:
 		return n, errUnrefData // Not possible; implies bug in validation logic
 	case overwrite:
 		return n, ErrWriteTooLong
@@ -578,12 +581,12 @@ func (sw *sparseFileWriter) ReadFrom(r io.Reader) (n int64, err error) {
 
 	var readLastByte bool
 	pos0 := sw.pos
-	for sw.LogicalRemaining() > 0 && !readLastByte && err == nil {
+	for sw.logicalRemaining() > 0 && !readLastByte && err == nil {
 		var nf int64 // Size of fragment
 		dataStart, dataEnd := sw.sp[0].Offset, sw.sp[0].endOffset()
 		if sw.pos < dataStart { // In a hole fragment
 			nf = dataStart - sw.pos
-			if sw.PhysicalRemaining() == 0 {
+			if sw.physicalRemaining() == 0 {
 				readLastByte = true
 				nf--
 			}
@@ -613,18 +616,18 @@ func (sw *sparseFileWriter) ReadFrom(r io.Reader) (n int64, err error) {
 		return n, errMissData // Not possible; implies bug in validation logic
 	case err != nil:
 		return n, err
-	case sw.LogicalRemaining() == 0 && sw.PhysicalRemaining() > 0:
+	case sw.logicalRemaining() == 0 && sw.physicalRemaining() > 0:
 		return n, errUnrefData // Not possible; implies bug in validation logic
 	default:
 		return n, ensureEOF(rs)
 	}
 }
 
-func (sw sparseFileWriter) LogicalRemaining() int64 {
+func (sw sparseFileWriter) logicalRemaining() int64 {
 	return sw.sp[len(sw.sp)-1].endOffset() - sw.pos
 }
-func (sw sparseFileWriter) PhysicalRemaining() int64 {
-	return sw.fw.PhysicalRemaining()
+func (sw sparseFileWriter) physicalRemaining() int64 {
+	return sw.fw.physicalRemaining()
 }
 
 // zeroWriter may only be written with NULs, otherwise it returns errWriteHole.
diff --git a/src/archive/tar/writer_test.go b/src/archive/tar/writer_test.go
index a00f02d8fab698a588872ade0e5693b0d0dc0660..43f2f5976c96514cd81394e3fa9b9ebf4b10ceed 100644
--- a/src/archive/tar/writer_test.go
+++ b/src/archive/tar/writer_test.go
@@ -987,11 +987,11 @@ func TestIssue12594(t *testing.T) {
 		// The prefix field should never appear in the GNU format.
 		var blk block
 		copy(blk[:], b.Bytes())
-		prefix := string(blk.USTAR().Prefix())
+		prefix := string(blk.toUSTAR().prefix())
 		if i := strings.IndexByte(prefix, 0); i >= 0 {
 			prefix = prefix[:i] // Truncate at the NUL terminator
 		}
-		if blk.GetFormat() == FormatGNU && len(prefix) > 0 && strings.HasPrefix(name, prefix) {
+		if blk.getFormat() == FormatGNU && len(prefix) > 0 && strings.HasPrefix(name, prefix) {
 			t.Errorf("test %d, found prefix in GNU format: %s", i, prefix)
 		}
 
@@ -1029,7 +1029,7 @@ func TestFileWriter(t *testing.T) {
 			wantCnt int64
 			wantErr error
 		}
-		testRemaining struct { // LogicalRemaining() == wantLCnt, PhysicalRemaining() == wantPCnt
+		testRemaining struct { // logicalRemaining() == wantLCnt, physicalRemaining() == wantPCnt
 			wantLCnt int64
 			wantPCnt int64
 		}
@@ -1292,11 +1292,11 @@ func TestFileWriter(t *testing.T) {
 					t.Errorf("test %d.%d, expected %d more operations", i, j, len(f.ops))
 				}
 			case testRemaining:
-				if got := fw.LogicalRemaining(); got != tf.wantLCnt {
-					t.Errorf("test %d.%d, LogicalRemaining() = %d, want %d", i, j, got, tf.wantLCnt)
+				if got := fw.logicalRemaining(); got != tf.wantLCnt {
+					t.Errorf("test %d.%d, logicalRemaining() = %d, want %d", i, j, got, tf.wantLCnt)
 				}
-				if got := fw.PhysicalRemaining(); got != tf.wantPCnt {
-					t.Errorf("test %d.%d, PhysicalRemaining() = %d, want %d", i, j, got, tf.wantPCnt)
+				if got := fw.physicalRemaining(); got != tf.wantPCnt {
+					t.Errorf("test %d.%d, physicalRemaining() = %d, want %d", i, j, got, tf.wantPCnt)
 				}
 			default:
 				t.Fatalf("test %d.%d, unknown test operation: %T", i, j, tf)
diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go
index 2d53f4c7231653d651b4f3b5bb1a15325b4a33ac..c91a8d00e6c1d488a4386296bb8a20ddaf14e3bb 100644
--- a/src/archive/zip/reader.go
+++ b/src/archive/zip/reader.go
@@ -102,7 +102,7 @@ func (z *Reader) init(r io.ReaderAt, size int64) error {
 	// indicate it contains up to 1 << 128 - 1 files. Since each file has a
 	// header which will be _at least_ 30 bytes we can safely preallocate
 	// if (data size / 30) >= end.directoryRecords.
-	if (uint64(size)-end.directorySize)/30 >= end.directoryRecords {
+	if end.directorySize < uint64(size) && (uint64(size)-end.directorySize)/30 >= end.directoryRecords {
 		z.File = make([]*File, 0, end.directoryRecords)
 	}
 	z.Comment = end.comment
diff --git a/src/archive/zip/reader_test.go b/src/archive/zip/reader_test.go
index 37dafe6c8e7c448c8fa28359e07fc2cdbb73560f..afb03ace24d286dee2208d46ee3ce274a55e47f4 100644
--- a/src/archive/zip/reader_test.go
+++ b/src/archive/zip/reader_test.go
@@ -1384,3 +1384,21 @@ func TestCVE202133196(t *testing.T) {
 		t.Errorf("Archive has unexpected number of files, got %d, want 5", len(r.File))
 	}
 }
+
+func TestCVE202139293(t *testing.T) {
+	// directory size is so large, that the check in Reader.init
+	// overflows when subtracting from the archive size, causing
+	// the pre-allocation check to be bypassed.
+	data := []byte{
+		0x50, 0x4b, 0x06, 0x06, 0x05, 0x06, 0x31, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x50, 0x4b,
+		0x06, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+		0x00, 0x00, 0x50, 0x4b, 0x05, 0x06, 0x00, 0x1a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x50, 0x4b,
+		0x06, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+		0x00, 0x00, 0x00, 0x50, 0x4b, 0x05, 0x06, 0x00, 0x31, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff,
+		0xff, 0x50, 0xfe, 0x00, 0xff, 0x00, 0x3a, 0x00, 0x00, 0x00, 0xff,
+	}
+	_, err := NewReader(bytes.NewReader(data), int64(len(data)))
+	if err != ErrFormat {
+		t.Fatalf("unexpected error, got: %v, want: %v", err, ErrFormat)
+	}
+}
diff --git a/src/cmd/asm/internal/arch/arm64.go b/src/cmd/asm/internal/arch/arm64.go
index 40d828a1fea7485d3389c529f16180ecdd140bc7..24689c5ab17657816a67e7fe0b69a498e40d4c99 100644
--- a/src/cmd/asm/internal/arch/arm64.go
+++ b/src/cmd/asm/internal/arch/arm64.go
@@ -165,27 +165,21 @@ func ARM64RegisterExtension(a *obj.Addr, ext string, reg, num int16, isAmount, i
 		}
 	}
 	if reg <= arm64.REG_R31 && reg >= arm64.REG_R0 {
+		if !isAmount {
+			return errors.New("invalid register extension")
+		}
 		switch ext {
 		case "UXTB":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			if a.Type == obj.TYPE_MEM {
 				return errors.New("invalid shift for the register offset addressing mode")
 			}
 			a.Reg = arm64.REG_UXTB + Rnum
 		case "UXTH":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			if a.Type == obj.TYPE_MEM {
 				return errors.New("invalid shift for the register offset addressing mode")
 			}
 			a.Reg = arm64.REG_UXTH + Rnum
 		case "UXTW":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			// effective address of memory is a base register value and an offset register value.
 			if a.Type == obj.TYPE_MEM {
 				a.Index = arm64.REG_UXTW + Rnum
@@ -193,48 +187,33 @@ func ARM64RegisterExtension(a *obj.Addr, ext string, reg, num int16, isAmount, i
 				a.Reg = arm64.REG_UXTW + Rnum
 			}
 		case "UXTX":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			if a.Type == obj.TYPE_MEM {
 				return errors.New("invalid shift for the register offset addressing mode")
 			}
 			a.Reg = arm64.REG_UXTX + Rnum
 		case "SXTB":
-			if !isAmount {
-				return errors.New("invalid register extension")
+			if a.Type == obj.TYPE_MEM {
+				return errors.New("invalid shift for the register offset addressing mode")
 			}
 			a.Reg = arm64.REG_SXTB + Rnum
 		case "SXTH":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			if a.Type == obj.TYPE_MEM {
 				return errors.New("invalid shift for the register offset addressing mode")
 			}
 			a.Reg = arm64.REG_SXTH + Rnum
 		case "SXTW":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			if a.Type == obj.TYPE_MEM {
 				a.Index = arm64.REG_SXTW + Rnum
 			} else {
 				a.Reg = arm64.REG_SXTW + Rnum
 			}
 		case "SXTX":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			if a.Type == obj.TYPE_MEM {
 				a.Index = arm64.REG_SXTX + Rnum
 			} else {
 				a.Reg = arm64.REG_SXTX + Rnum
 			}
 		case "LSL":
-			if !isAmount {
-				return errors.New("invalid register extension")
-			}
 			a.Index = arm64.REG_LSL + Rnum
 		default:
 			return errors.New("unsupported general register extension type: " + ext)
diff --git a/src/cmd/asm/internal/asm/testdata/arm64.s b/src/cmd/asm/internal/asm/testdata/arm64.s
index d8a20edfc13039d205c10a0579ab9414a54daa54..a4b56b0696b33a8524243df796ac9c7fee0ea4be 100644
--- a/src/cmd/asm/internal/asm/testdata/arm64.s
+++ b/src/cmd/asm/internal/asm/testdata/arm64.s
@@ -334,6 +334,8 @@ TEXT	foo(SB), DUPOK|NOSPLIT, $-8
 	EONW	$0x6006000060060, R5                // EONW	$1689262177517664, R5           // 1b0c8052db00a072a5003b4a
 	ORNW	$0x6006000060060, R5                // ORNW	$1689262177517664, R5           // 1b0c8052db00a072a5003b2a
 	BICSW	$0x6006000060060, R5                // BICSW	$1689262177517664, R5           // 1b0c8052db00a072a5003b6a
+	AND	$1, ZR                              // fb0340b2ff031b8a
+	ANDW	$1, ZR                              // fb030032ff031b0a
 	// TODO: this could have better encoding
 	ANDW	$-1, R10                            // 1b0080124a011b0a
 	AND	$8, R0, RSP                         // 1f007d92
@@ -369,9 +371,9 @@ TEXT	foo(SB), DUPOK|NOSPLIT, $-8
 	MOVD	$-1, R1                       // 01008092
 	MOVD	$0x210000, R0                 // MOVD	$2162688, R0                // 2004a0d2
 	MOVD	$0xffffffffffffaaaa, R1       // MOVD	$-21846, R1                 // a1aa8a92
-	MOVW	$1, ZR
+	MOVW	$1, ZR                        // 3f008052
 	MOVW	$1, R1
-	MOVD	$1, ZR
+	MOVD	$1, ZR                        // 3f0080d2
 	MOVD	$1, R1
 	MOVK	$1, R1
 	MOVD	$0x1000100010001000, RSP      // MOVD	$1152939097061330944, RSP   // ff8304b2
@@ -386,10 +388,10 @@ TEXT	foo(SB), DUPOK|NOSPLIT, $-8
 	VMOVQ	$0x8040201008040202, $0x7040201008040201, V20         // VMOVQ	$-9205322385119247870, $8088500183983456769, V20
 
 // mov(to/from sp)
-	MOVD	$0x1002(RSP), R1              // MOVD	$4098(RSP), R1              // fb074091610b0091
-	MOVD	$0x1708(RSP), RSP             // MOVD	$5896(RSP), RSP             // fb0740917f231c91
-	MOVD	$0x2001(R7), R1               // MOVD	$8193(R7), R1               // fb08409161070091
-	MOVD	$0xffffff(R7), R1             // MOVD	$16777215(R7), R1           // fbfc7f9161ff3f91
+	MOVD	$0x1002(RSP), R1              // MOVD	$4098(RSP), R1              // e107409121080091
+	MOVD	$0x1708(RSP), RSP             // MOVD	$5896(RSP), RSP             // ff074091ff231c91
+	MOVD	$0x2001(R7), R1               // MOVD	$8193(R7), R1               // e108409121040091
+	MOVD	$0xffffff(R7), R1             // MOVD	$16777215(R7), R1           // e1fc7f9121fc3f91
 	MOVD	$-0x1(R7), R1                 // MOVD	$-1(R7), R1                 // e10400d1
 	MOVD	$-0x30(R7), R1                // MOVD	$-48(R7), R1                // e1c000d1
 	MOVD	$-0x708(R7), R1               // MOVD	$-1800(R7), R1              // e1201cd1
diff --git a/src/cmd/asm/internal/asm/testdata/arm64error.s b/src/cmd/asm/internal/asm/testdata/arm64error.s
index cf57179e43016156cf148dcbd001c54d5620b00e..8b12b166804bf4eb0f233ef2bd2893a8996213f1 100644
--- a/src/cmd/asm/internal/asm/testdata/arm64error.s
+++ b/src/cmd/asm/internal/asm/testdata/arm64error.s
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 TEXT errors(SB),$0
-	AND	$1, RSP                                          // ERROR "illegal combination"
+	AND	$1, RSP                                          // ERROR "illegal source register"
 	ANDS	$1, R0, RSP                                      // ERROR "illegal combination"
 	ADDSW	R7->32, R14, R13                                 // ERROR "shift amount out of range 0 to 31"
 	ADD	R1.UXTB<<5, R2, R3                               // ERROR "shift amount out of range 0 to 4"
@@ -419,4 +419,8 @@ TEXT errors(SB),$0
 	ADD	R1>>2, RSP, R3                                   // ERROR "illegal combination"
 	ADDS	R2<<3, R3, RSP                                   // ERROR "unexpected SP reference"
 	CMP	R1<<5, RSP                                       // ERROR "the left shift amount out of range 0 to 4"
+	MOVD.P  y+8(FP), R1                                      // ERROR "illegal combination"
+	MOVD.W  x-8(SP), R1                                      // ERROR "illegal combination"
+	LDP.P   x+8(FP), (R0, R1)                                // ERROR "illegal combination"
+	LDP.W   x+8(SP), (R0, R1)                                // ERROR "illegal combination"
 	RET
diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index 94152f4278cb04b44325a936c50d8d11887f4b3d..3badd73f7942288def0364a74b545ec2424ccda9 100644
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -59,9 +59,9 @@ func (p *Package) writeDefs() {
 	// Write C main file for using gcc to resolve imports.
 	fmt.Fprintf(fm, "int main() { return 0; }\n")
 	if *importRuntimeCgo {
-		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*), void *a, int c, __SIZE_TYPE__ ctxt) { }\n")
+		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*) __attribute__((unused)), void *a __attribute__((unused)), int c __attribute__((unused)), __SIZE_TYPE__ ctxt __attribute__((unused))) { }\n")
 		fmt.Fprintf(fm, "__SIZE_TYPE__ _cgo_wait_runtime_init_done(void) { return 0; }\n")
-		fmt.Fprintf(fm, "void _cgo_release_context(__SIZE_TYPE__ ctxt) { }\n")
+		fmt.Fprintf(fm, "void _cgo_release_context(__SIZE_TYPE__ ctxt __attribute__((unused))) { }\n")
 		fmt.Fprintf(fm, "char* _cgo_topofstack(void) { return (char*)0; }\n")
 	} else {
 		// If we're not importing runtime/cgo, we *are* runtime/cgo,
@@ -70,8 +70,8 @@ func (p *Package) writeDefs() {
 		fmt.Fprintf(fm, "__SIZE_TYPE__ _cgo_wait_runtime_init_done(void);\n")
 		fmt.Fprintf(fm, "void _cgo_release_context(__SIZE_TYPE__);\n")
 	}
-	fmt.Fprintf(fm, "void _cgo_allocate(void *a, int c) { }\n")
-	fmt.Fprintf(fm, "void _cgo_panic(void *a, int c) { }\n")
+	fmt.Fprintf(fm, "void _cgo_allocate(void *a __attribute__((unused)), int c __attribute__((unused))) { }\n")
+	fmt.Fprintf(fm, "void _cgo_panic(void *a __attribute__((unused)), int c __attribute__((unused))) { }\n")
 	fmt.Fprintf(fm, "void _cgo_reginit(void) { }\n")
 
 	// Write second Go output: definitions of _C_xxx.
diff --git a/src/cmd/compile/abi-internal.md b/src/cmd/compile/abi-internal.md
index 2bb4055083263044df3c400a52a3cf6dd27dde40..3619aea4aa261e622633ab426c3ccaaa6b0e791d 100644
--- a/src/cmd/compile/abi-internal.md
+++ b/src/cmd/compile/abi-internal.md
@@ -505,6 +505,128 @@ control bits specified by the ELF AMD64 ABI.
 
 The x87 floating-point control word is not used by Go on amd64.
 
+### arm64 architecture
+
+The arm64 architecture uses R0 – R15 for integer arguments and results.
+
+It uses F0 – F15 for floating-point arguments and results.
+
+*Rationale*: 16 integer registers and 16 floating-point registers are
+more than enough for passing arguments and results for practically all
+functions (see Appendix). While there are more registers available,
+using more registers provides little benefit. Additionally, it will add
+overhead on code paths where the number of arguments are not statically
+known (e.g. reflect call), and will consume more stack space when there
+is only limited stack space available to fit in the nosplit limit.
+
+Registers R16 and R17 are permanent scratch registers. They are also
+used as scratch registers by the linker (Go linker and external
+linker) in trampolines.
+
+Register R18 is reserved and never used. It is reserved for the OS
+on some platforms (e.g. macOS).
+
+Registers R19 – R25 are permanent scratch registers. In addition,
+R27 is a permanent scratch register used by the assembler when
+expanding instructions.
+
+Floating-point registers F16 – F31 are also permanent scratch
+registers.
+
+Special-purpose registers are as follows:
+
+| Register | Call meaning | Return meaning | Body meaning |
+| --- | --- | --- | --- |
+| RSP | Stack pointer | Same | Same |
+| R30 | Link register | Same | Scratch (non-leaf functions) |
+| R29 | Frame pointer | Same | Same |
+| R28 | Current goroutine | Same | Same |
+| R27 | Scratch | Scratch | Scratch |
+| R26 | Closure context pointer | Scratch | Scratch |
+| R18 | Reserved (not used) | Same | Same |
+| ZR  | Zero value | Same | Same |
+
+*Rationale*: These register meanings are compatible with Go’s
+stack-based calling convention.
+
+*Rationale*: The link register, R30, holds the function return
+address at the function entry. For functions that have frames
+(including most non-leaf functions), R30 is saved to stack in the
+function prologue and restored in the epilogue. Within the function
+body, R30 can be used as a scratch register.
+
+*Implementation note*: Registers with fixed meaning at calls but not
+in function bodies must be initialized by "injected" calls such as
+signal-based panics.
+
+#### Stack layout
+
+The stack pointer, RSP, grows down and is always aligned to 16 bytes.
+
+*Rationale*: The arm64 architecture requires the stack pointer to be
+16-byte aligned.
+
+A function's stack frame, after the frame is created, is laid out as
+follows:
+
+    +------------------------------+
+    | ... locals ...               |
+    | ... outgoing arguments ...   |
+    | return PC                    | ← RSP points to
+    | frame pointer on entry       |
+    +------------------------------+ ↓ lower addresses
+
+The "return PC" is loaded to the link register, R30, as part of the
+arm64 `CALL` operation.
+
+On entry, a function subtracts from RSP to open its stack frame, and
+saves the values of R30 and R29 at the bottom of the frame.
+Specifically, R30 is saved at 0(RSP) and R29 is saved at -8(RSP),
+after RSP is updated.
+
+A leaf function that does not require any stack space may omit the
+saved R30 and R29.
+
+The Go ABI's use of R29 as a frame pointer register is compatible with
+arm64 architecture requirement so that Go can inter-operate with platform
+debuggers and profilers.
+
+This stack layout is used by both register-based (ABIInternal) and
+stack-based (ABI0) calling conventions.
+
+#### Flags
+
+The arithmetic status flags (NZCV) are treated like scratch registers
+and not preserved across calls.
+All other bits in PSTATE are system flags and are not modified by Go.
+
+The floating-point status register (FPSR) is treated like scratch
+registers and not preserved across calls.
+
+At calls, the floating-point control register (FPCR) bits are always
+set as follows:
+
+| Flag | Bit | Value | Meaning |
+| --- | --- | --- | --- |
+| DN  | 25 | 0 | Propagate NaN operands |
+| FZ  | 24 | 0 | Do not flush to zero |
+| RC  | 23/22 | 0 (RN) | Round to nearest, choose even if tied |
+| IDE | 15 | 0 | Denormal operations trap disabled |
+| IXE | 12 | 0 | Inexact trap disabled |
+| UFE | 11 | 0 | Underflow trap disabled |
+| OFE | 10 | 0 | Overflow trap disabled |
+| DZE | 9 | 0 | Divide-by-zero trap disabled |
+| IOE | 8 | 0 | Invalid operations trap disabled |
+| NEP | 2 | 0 | Scalar operations do not affect higher elements in vector registers |
+| AH  | 1 | 0 | No alternate handling of de-normal inputs |
+| FIZ | 0 | 0 | Do not zero de-normals |
+
+*Rationale*: Having a fixed FPCR control configuration allows Go
+functions to use floating-point and vector (SIMD) operations without
+modifying or saving the FPCR.
+Functions are allowed to modify it between calls (as long as they
+restore it), but as of this writing Go code never does.
+
 ## Future directions
 
 ### Spill path improvements
diff --git a/src/cmd/compile/internal/amd64/galign.go b/src/cmd/compile/internal/amd64/galign.go
index 2785aa03368b782c3d5d9b5c8f983d0dac19b1d6..ca44263afc476c4eef177df64562920b13e7afdc 100644
--- a/src/cmd/compile/internal/amd64/galign.go
+++ b/src/cmd/compile/internal/amd64/galign.go
@@ -18,11 +18,10 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
-	arch.LoadRegResults = loadRegResults
+	arch.LoadRegResult = loadRegResult
 	arch.SpillArgReg = spillArgReg
 }
diff --git a/src/cmd/compile/internal/amd64/ggen.go b/src/cmd/compile/internal/amd64/ggen.go
index 1484ad5404b4797552195b597fd0e22cab00e85b..b8dce81a92d2cc9013e075b6698e8acc2b8b2fbf 100644
--- a/src/cmd/compile/internal/amd64/ggen.go
+++ b/src/cmd/compile/internal/amd64/ggen.go
@@ -57,7 +57,6 @@ func dzDI(b int64) int64 {
 func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, state *uint32) *obj.Prog {
 	const (
 		r13 = 1 << iota // if R13 is already zeroed.
-		x15             // if X15 is already zeroed. Note: in new ABI, X15 is always zero.
 	)
 
 	if cnt == 0 {
@@ -85,11 +84,6 @@ func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, state *uint32) *obj.
 		}
 		p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R13, 0, obj.TYPE_MEM, x86.REG_SP, off)
 	} else if !isPlan9 && cnt <= int64(8*types.RegSize) {
-		if !buildcfg.Experiment.RegabiG && *state&x15 == 0 {
-			p = pp.Append(p, x86.AXORPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_REG, x86.REG_X15, 0)
-			*state |= x15
-		}
-
 		for i := int64(0); i < cnt/16; i++ {
 			p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off+i*16)
 		}
@@ -98,10 +92,6 @@ func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, state *uint32) *obj.
 			p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off+cnt-int64(16))
 		}
 	} else if !isPlan9 && (cnt <= int64(128*types.RegSize)) {
-		if !buildcfg.Experiment.RegabiG && *state&x15 == 0 {
-			p = pp.Append(p, x86.AXORPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_REG, x86.REG_X15, 0)
-			*state |= x15
-		}
 		// Save DI to r12. With the amd64 Go register abi, DI can contain
 		// an incoming parameter, whereas R12 is always scratch.
 		p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_DI, 0, obj.TYPE_REG, x86.REG_R12, 0)
diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
index ca5f36e77598c6ff54b6c3288b086f40a9f999d4..30dba057d011a142bf3014a33a098c2773d8a1dc 100644
--- a/src/cmd/compile/internal/amd64/ssa.go
+++ b/src/cmd/compile/internal/amd64/ssa.go
@@ -823,7 +823,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		p.To.Reg = v.Args[0].Reg()
 		ssagen.AddAux2(&p.To, v, sc.Off64())
 	case ssa.OpAMD64MOVOstorezero:
-		if !buildcfg.Experiment.RegabiG || s.ABI != obj.ABIInternal {
+		if s.ABI != obj.ABIInternal {
 			// zero X15 manually
 			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
 		}
@@ -914,7 +914,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
 	case ssa.OpAMD64DUFFZERO:
-		if !buildcfg.Experiment.RegabiG || s.ABI != obj.ABIInternal {
+		if s.ABI != obj.ABIInternal {
 			// zero X15 manually
 			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
 		}
@@ -997,22 +997,26 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		// Closure pointer is DX.
 		ssagen.CheckLoweredGetClosurePtr(v)
 	case ssa.OpAMD64LoweredGetG:
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABIInternal {
+		if s.ABI == obj.ABIInternal {
 			v.Fatalf("LoweredGetG should not appear in ABIInternal")
 		}
 		r := v.Reg()
 		getgFromTLS(s, r)
 	case ssa.OpAMD64CALLstatic:
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABI0 && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABIInternal {
+		if s.ABI == obj.ABI0 && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABIInternal {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
 		s.Call(v)
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABIInternal && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABI0 {
+		if s.ABI == obj.ABIInternal && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABI0 {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
@@ -1304,9 +1308,11 @@ func ssaGenBlock(s *ssagen.State, b, next *ssa.Block) {
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABI0 && b.Aux.(*obj.LSym).ABI() == obj.ABIInternal {
+		if s.ABI == obj.ABI0 && b.Aux.(*obj.LSym).ABI() == obj.ABIInternal {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
@@ -1348,20 +1354,15 @@ func ssaGenBlock(s *ssagen.State, b, next *ssa.Block) {
 	}
 }
 
-func loadRegResults(s *ssagen.State, f *ssa.Func) {
-	for _, o := range f.OwnAux.ABIInfo().OutParams() {
-		n := o.Name.(*ir.Name)
-		rts, offs := o.RegisterTypesAndOffsets()
-		for i := range o.Registers {
-			p := s.Prog(loadByType(rts[i]))
-			p.From.Type = obj.TYPE_MEM
-			p.From.Name = obj.NAME_AUTO
-			p.From.Sym = n.Linksym()
-			p.From.Offset = n.FrameOffset() + offs[i]
-			p.To.Type = obj.TYPE_REG
-			p.To.Reg = ssa.ObjRegForAbiReg(o.Registers[i], f.Config)
-		}
-	}
+func loadRegResult(s *ssagen.State, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
+	p := s.Prog(loadByType(t))
+	p.From.Type = obj.TYPE_MEM
+	p.From.Name = obj.NAME_AUTO
+	p.From.Sym = n.Linksym()
+	p.From.Offset = n.FrameOffset() + off
+	p.To.Type = obj.TYPE_REG
+	p.To.Reg = reg
+	return p
 }
 
 func spillArgReg(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
diff --git a/src/cmd/compile/internal/arm/galign.go b/src/cmd/compile/internal/arm/galign.go
index d68500280d00b79376d976a39fab34286faa65a8..23e52bacbf2a3d077d7fc267859c0167283707a2 100644
--- a/src/cmd/compile/internal/arm/galign.go
+++ b/src/cmd/compile/internal/arm/galign.go
@@ -18,7 +18,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.SoftFloat = buildcfg.GOARM == 5
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/arm64/galign.go b/src/cmd/compile/internal/arm64/galign.go
index d3db37e16f43bcbbb261d75078df6c8d126b4a72..3ebd860de8f887c4c0b4dbc3934b7ed297995398 100644
--- a/src/cmd/compile/internal/arm64/galign.go
+++ b/src/cmd/compile/internal/arm64/galign.go
@@ -18,9 +18,10 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.PadFrame = padframe
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
+	arch.LoadRegResult = loadRegResult
+	arch.SpillArgReg = spillArgReg
 }
diff --git a/src/cmd/compile/internal/arm64/ssa.go b/src/cmd/compile/internal/arm64/ssa.go
index 0c997bc4b3e82adaee8e20ea5bafaf29f6a01c7b..c3319f949122bd14faf95c5317f39b62f2ffa5d1 100644
--- a/src/cmd/compile/internal/arm64/ssa.go
+++ b/src/cmd/compile/internal/arm64/ssa.go
@@ -10,6 +10,7 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/objw"
 	"cmd/compile/internal/ssa"
 	"cmd/compile/internal/ssagen"
 	"cmd/compile/internal/types"
@@ -161,6 +162,18 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		p.From.Type = obj.TYPE_REG
 		p.From.Reg = v.Args[0].Reg()
 		ssagen.AddrAuto(&p.To, v)
+	case ssa.OpArgIntReg, ssa.OpArgFloatReg:
+		// The assembler needs to wrap the entry safepoint/stack growth code with spill/unspill
+		// The loop only runs once.
+		for _, a := range v.Block.Func.RegArgs {
+			// Pass the spill/unspill information along to the assembler, offset by size of
+			// the saved LR slot.
+			addr := ssagen.SpillSlotAddr(a, arm64.REGSP, base.Ctxt.FixedFrameSize())
+			s.FuncInfo().AddSpill(
+				obj.RegSpill{Reg: a.Reg, Addr: addr, Unspill: loadByType(a.Type), Spill: storeByType(a.Type)})
+		}
+		v.Block.Func.RegArgs = nil
+		ssagen.CheckArgReg(v)
 	case ssa.OpARM64ADD,
 		ssa.OpARM64SUB,
 		ssa.OpARM64AND,
@@ -1101,8 +1114,34 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		v.Fatalf("FlagConstant op should never make it to codegen %v", v.LongString())
 	case ssa.OpARM64InvertFlags:
 		v.Fatalf("InvertFlags should never make it to codegen %v", v.LongString())
-	case ssa.OpClobber, ssa.OpClobberReg:
-		// TODO: implement for clobberdead experiment. Nop is ok for now.
+	case ssa.OpClobber:
+		// MOVW	$0xdeaddead, REGTMP
+		// MOVW	REGTMP, (slot)
+		// MOVW	REGTMP, 4(slot)
+		p := s.Prog(arm64.AMOVW)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = 0xdeaddead
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = arm64.REGTMP
+		p = s.Prog(arm64.AMOVW)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = arm64.REGTMP
+		p.To.Type = obj.TYPE_MEM
+		p.To.Reg = arm64.REGSP
+		ssagen.AddAux(&p.To, v)
+		p = s.Prog(arm64.AMOVW)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = arm64.REGTMP
+		p.To.Type = obj.TYPE_MEM
+		p.To.Reg = arm64.REGSP
+		ssagen.AddAux2(&p.To, v, v.AuxInt+4)
+	case ssa.OpClobberReg:
+		x := uint64(0xdeaddeaddeaddead)
+		p := s.Prog(arm64.AMOVD)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = int64(x)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = v.Reg()
 	default:
 		v.Fatalf("genValue not implemented: %s", v.LongString())
 	}
@@ -1266,3 +1305,22 @@ func ssaGenBlock(s *ssagen.State, b, next *ssa.Block) {
 		b.Fatalf("branch not implemented: %s", b.LongString())
 	}
 }
+
+func loadRegResult(s *ssagen.State, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
+	p := s.Prog(loadByType(t))
+	p.From.Type = obj.TYPE_MEM
+	p.From.Name = obj.NAME_AUTO
+	p.From.Sym = n.Linksym()
+	p.From.Offset = n.FrameOffset() + off
+	p.To.Type = obj.TYPE_REG
+	p.To.Reg = reg
+	return p
+}
+
+func spillArgReg(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
+	p = pp.Append(p, storeByType(t), obj.TYPE_REG, reg, 0, obj.TYPE_MEM, 0, n.FrameOffset()+off)
+	p.To.Name = obj.NAME_PARAM
+	p.To.Sym = n.Linksym()
+	p.Pos = p.Pos.WithNotStmt()
+	return p
+}
diff --git a/src/cmd/compile/internal/base/bootstrap_false.go b/src/cmd/compile/internal/base/bootstrap_false.go
new file mode 100644
index 0000000000000000000000000000000000000000..c77fcd730812d824c061d329ca0ed353d82a8b16
--- /dev/null
+++ b/src/cmd/compile/internal/base/bootstrap_false.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !compiler_bootstrap
+// +build !compiler_bootstrap
+
+package base
+
+// CompilerBootstrap reports whether the current compiler binary was
+// built with -tags=compiler_bootstrap.
+const CompilerBootstrap = false
diff --git a/src/cmd/compile/internal/base/bootstrap_true.go b/src/cmd/compile/internal/base/bootstrap_true.go
new file mode 100644
index 0000000000000000000000000000000000000000..1eb58b2f9dc1ce86ca9fb095715e685e667cbb3e
--- /dev/null
+++ b/src/cmd/compile/internal/base/bootstrap_true.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build compiler_bootstrap
+// +build compiler_bootstrap
+
+package base
+
+// CompilerBootstrap reports whether the current compiler binary was
+// built with -tags=compiler_bootstrap.
+const CompilerBootstrap = true
diff --git a/src/cmd/compile/internal/base/debug.go b/src/cmd/compile/internal/base/debug.go
index 71712ab1a56fd281f52d3befede9b833caa70fbd..e2245e1c26ea64cb01cd4a63315f68fe70c5f949 100644
--- a/src/cmd/compile/internal/base/debug.go
+++ b/src/cmd/compile/internal/base/debug.go
@@ -44,8 +44,11 @@ type DebugFlags struct {
 	Panic                int    `help:"show all compiler panics"`
 	Slice                int    `help:"print information about slice compilation"`
 	SoftFloat            int    `help:"force compiler to emit soft-float code"`
+	SyncFrames           int    `help:"how many writer stack frames to include at sync points in unified export data"`
 	TypeAssert           int    `help:"print information about type assertion inlining"`
 	TypecheckInl         int    `help:"eager typechecking of inline function bodies"`
+	Unified              int    `help:"enable unified IR construction"`
+	UnifiedQuirks        int    `help:"enable unified IR construction's quirks mode"`
 	WB                   int    `help:"print information about write barriers"`
 	ABIWrap              int    `help:"print information about ABI wrapper generation"`
 
diff --git a/src/cmd/compile/internal/base/flag.go b/src/cmd/compile/internal/base/flag.go
index 42c0c1b94b559c17ae593b9592b7ec5152e3a5f8..942659bcc0f1c6f8c1d55d80fbd6456c773de25a 100644
--- a/src/cmd/compile/internal/base/flag.go
+++ b/src/cmd/compile/internal/base/flag.go
@@ -140,6 +140,7 @@ type CmdFlags struct {
 
 // ParseFlags parses the command-line flags into Flag.
 func ParseFlags() {
+	Flag.G = 3
 	Flag.I = addImportDir
 
 	Flag.LowerC = 1
@@ -159,7 +160,11 @@ func ParseFlags() {
 	Flag.LinkShared = &Ctxt.Flag_linkshared
 	Flag.Shared = &Ctxt.Flag_shared
 	Flag.WB = true
+
 	Debug.InlFuncsWithClosures = 1
+	if buildcfg.Experiment.Unified {
+		Debug.Unified = 1
+	}
 
 	Debug.Checkptr = -1 // so we can tell whether it is set explicitly
 
diff --git a/src/cmd/compile/internal/typecheck/mapfile_mmap.go b/src/cmd/compile/internal/base/mapfile_mmap.go
similarity index 93%
rename from src/cmd/compile/internal/typecheck/mapfile_mmap.go
rename to src/cmd/compile/internal/base/mapfile_mmap.go
index 298b385bcb0f762413c6cf6f7402f0817240d005..c1616db8e9dd684027400eea36481f209d98d2b6 100644
--- a/src/cmd/compile/internal/typecheck/mapfile_mmap.go
+++ b/src/cmd/compile/internal/base/mapfile_mmap.go
@@ -5,7 +5,7 @@
 //go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build darwin dragonfly freebsd linux netbsd openbsd
 
-package typecheck
+package base
 
 import (
 	"os"
@@ -19,7 +19,7 @@ import (
 
 // mapFile returns length bytes from the file starting at the
 // specified offset as a string.
-func mapFile(f *os.File, offset, length int64) (string, error) {
+func MapFile(f *os.File, offset, length int64) (string, error) {
 	// POSIX mmap: "The implementation may require that off is a
 	// multiple of the page size."
 	x := offset & int64(os.Getpagesize()-1)
diff --git a/src/cmd/compile/internal/typecheck/mapfile_read.go b/src/cmd/compile/internal/base/mapfile_read.go
similarity index 85%
rename from src/cmd/compile/internal/typecheck/mapfile_read.go
rename to src/cmd/compile/internal/base/mapfile_read.go
index 9637ab97abe458dc19e0ead21ed0759532fc7d47..01796a9bab7c9978f0b22211d714efff01782c58 100644
--- a/src/cmd/compile/internal/typecheck/mapfile_read.go
+++ b/src/cmd/compile/internal/base/mapfile_read.go
@@ -5,14 +5,14 @@
 //go:build !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd
 // +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd
 
-package typecheck
+package base
 
 import (
 	"io"
 	"os"
 )
 
-func mapFile(f *os.File, offset, length int64) (string, error) {
+func MapFile(f *os.File, offset, length int64) (string, error) {
 	buf := make([]byte, length)
 	_, err := io.ReadFull(io.NewSectionReader(f, offset, length), buf)
 	if err != nil {
diff --git a/src/cmd/compile/internal/base/print.go b/src/cmd/compile/internal/base/print.go
index b095fd704daad807b3847bbd2916024356161af2..4afe2eb9eea3154f83456ed4ed282f04d7d1ab4a 100644
--- a/src/cmd/compile/internal/base/print.go
+++ b/src/cmd/compile/internal/base/print.go
@@ -233,6 +233,27 @@ func FatalfAt(pos src.XPos, format string, args ...interface{}) {
 	ErrorExit()
 }
 
+// Assert reports "assertion failed" with Fatalf, unless b is true.
+func Assert(b bool) {
+	if !b {
+		Fatalf("assertion failed")
+	}
+}
+
+// Assertf reports a fatal error with Fatalf, unless b is true.
+func Assertf(b bool, format string, args ...interface{}) {
+	if !b {
+		Fatalf(format, args...)
+	}
+}
+
+// AssertfAt reports a fatal error with FatalfAt, unless b is true.
+func AssertfAt(b bool, pos src.XPos, format string, args ...interface{}) {
+	if !b {
+		FatalfAt(pos, format, args...)
+	}
+}
+
 // hcrash crashes the compiler when -h is set, to find out where a message is generated.
 func hcrash() {
 	if Flag.LowerH != 0 {
diff --git a/src/cmd/compile/internal/deadcode/deadcode.go b/src/cmd/compile/internal/deadcode/deadcode.go
index 520203787f02dc97968e4cd71c577f7fc646d24d..3658c89912b85f52f30d3fcf0d94f2d9f6aa0617 100644
--- a/src/cmd/compile/internal/deadcode/deadcode.go
+++ b/src/cmd/compile/internal/deadcode/deadcode.go
@@ -38,6 +38,7 @@ func Func(fn *ir.Func) {
 		}
 	}
 
+	ir.VisitList(fn.Body, markHiddenClosureDead)
 	fn.Body = []ir.Node{ir.NewBlockStmt(base.Pos, nil)}
 }
 
@@ -62,9 +63,11 @@ func stmts(nn *ir.Nodes) {
 			if ir.IsConst(n.Cond, constant.Bool) {
 				var body ir.Nodes
 				if ir.BoolVal(n.Cond) {
+					ir.VisitList(n.Else, markHiddenClosureDead)
 					n.Else = ir.Nodes{}
 					body = n.Body
 				} else {
+					ir.VisitList(n.Body, markHiddenClosureDead)
 					n.Body = ir.Nodes{}
 					body = n.Else
 				}
@@ -150,3 +153,13 @@ func expr(n ir.Node) ir.Node {
 	}
 	return n
 }
+
+func markHiddenClosureDead(n ir.Node) {
+	if n.Op() != ir.OCLOSURE {
+		return
+	}
+	clo := n.(*ir.ClosureExpr)
+	if clo.Func.IsHiddenClosure() {
+		clo.Func.SetIsDeadcodeClosure(true)
+	}
+}
diff --git a/src/cmd/compile/internal/dwarfgen/dwarf.go b/src/cmd/compile/internal/dwarfgen/dwarf.go
index 0e22b61bc3ff4344ba1ad7c3e74f65c76a620243..30472a9ebd750ead59dc5131737b7301ce378405 100644
--- a/src/cmd/compile/internal/dwarfgen/dwarf.go
+++ b/src/cmd/compile/internal/dwarfgen/dwarf.go
@@ -214,7 +214,7 @@ func createDwarfVars(fnsym *obj.LSym, complexOK bool, fn *ir.Func, apDecls []*ir
 			Type:          base.Ctxt.Lookup(typename),
 			DeclFile:      declpos.RelFilename(),
 			DeclLine:      declpos.RelLine(),
-			DeclCol:       declpos.Col(),
+			DeclCol:       declpos.RelCol(),
 			InlIndex:      int32(inlIndex),
 			ChildIndex:    -1,
 		})
@@ -371,7 +371,7 @@ func createSimpleVar(fnsym *obj.LSym, n *ir.Name) *dwarf.Var {
 		Type:          base.Ctxt.Lookup(typename),
 		DeclFile:      declpos.RelFilename(),
 		DeclLine:      declpos.RelLine(),
-		DeclCol:       declpos.Col(),
+		DeclCol:       declpos.RelCol(),
 		InlIndex:      int32(inlIndex),
 		ChildIndex:    -1,
 	}
@@ -475,7 +475,7 @@ func createComplexVar(fnsym *obj.LSym, fn *ir.Func, varID ssa.VarID) *dwarf.Var
 		StackOffset: ssagen.StackOffset(debug.Slots[debug.VarSlots[varID][0]]),
 		DeclFile:    declpos.RelFilename(),
 		DeclLine:    declpos.RelLine(),
-		DeclCol:     declpos.Col(),
+		DeclCol:     declpos.RelCol(),
 		InlIndex:    int32(inlIndex),
 		ChildIndex:  -1,
 	}
diff --git a/src/cmd/compile/internal/dwarfgen/dwinl.go b/src/cmd/compile/internal/dwarfgen/dwinl.go
index 8adb36fc883da0614f760410fa8f6af8e7ccb25e..c785e064a7f48497b2f4304848efe5879c65cd33 100644
--- a/src/cmd/compile/internal/dwarfgen/dwinl.go
+++ b/src/cmd/compile/internal/dwarfgen/dwinl.go
@@ -244,7 +244,7 @@ func makePreinlineDclMap(fnsym *obj.LSym) map[varPos]int {
 			DeclName: unversion(n.Sym().Name),
 			DeclFile: pos.RelFilename(),
 			DeclLine: pos.RelLine(),
-			DeclCol:  pos.Col(),
+			DeclCol:  pos.RelCol(),
 		}
 		if _, found := m[vp]; found {
 			// We can see collisions (variables with the same name/file/line/col) in obfuscated or machine-generated code -- see issue 44378 for an example. Skip duplicates in such cases, since it is unlikely that a human will be debugging such code.
diff --git a/src/cmd/compile/internal/escape/assign.go b/src/cmd/compile/internal/escape/assign.go
new file mode 100644
index 0000000000000000000000000000000000000000..80697bf37b3ee6be3ae995537097ed5bcdcf810e
--- /dev/null
+++ b/src/cmd/compile/internal/escape/assign.go
@@ -0,0 +1,120 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+)
+
+// addr evaluates an addressable expression n and returns a hole
+// that represents storing into the represented location.
+func (e *escape) addr(n ir.Node) hole {
+	if n == nil || ir.IsBlank(n) {
+		// Can happen in select case, range, maybe others.
+		return e.discardHole()
+	}
+
+	k := e.heapHole()
+
+	switch n.Op() {
+	default:
+		base.Fatalf("unexpected addr: %v", n)
+	case ir.ONAME:
+		n := n.(*ir.Name)
+		if n.Class == ir.PEXTERN {
+			break
+		}
+		k = e.oldLoc(n).asHole()
+	case ir.OLINKSYMOFFSET:
+		break
+	case ir.ODOT:
+		n := n.(*ir.SelectorExpr)
+		k = e.addr(n.X)
+	case ir.OINDEX:
+		n := n.(*ir.IndexExpr)
+		e.discard(n.Index)
+		if n.X.Type().IsArray() {
+			k = e.addr(n.X)
+		} else {
+			e.discard(n.X)
+		}
+	case ir.ODEREF, ir.ODOTPTR:
+		e.discard(n)
+	case ir.OINDEXMAP:
+		n := n.(*ir.IndexExpr)
+		e.discard(n.X)
+		e.assignHeap(n.Index, "key of map put", n)
+	}
+
+	return k
+}
+
+func (e *escape) addrs(l ir.Nodes) []hole {
+	var ks []hole
+	for _, n := range l {
+		ks = append(ks, e.addr(n))
+	}
+	return ks
+}
+
+func (e *escape) assignHeap(src ir.Node, why string, where ir.Node) {
+	e.expr(e.heapHole().note(where, why), src)
+}
+
+// assignList evaluates the assignment dsts... = srcs....
+func (e *escape) assignList(dsts, srcs []ir.Node, why string, where ir.Node) {
+	ks := e.addrs(dsts)
+	for i, k := range ks {
+		var src ir.Node
+		if i < len(srcs) {
+			src = srcs[i]
+		}
+
+		if dst := dsts[i]; dst != nil {
+			// Detect implicit conversion of uintptr to unsafe.Pointer when
+			// storing into reflect.{Slice,String}Header.
+			if dst.Op() == ir.ODOTPTR && ir.IsReflectHeaderDataField(dst) {
+				e.unsafeValue(e.heapHole().note(where, why), src)
+				continue
+			}
+
+			// Filter out some no-op assignments for escape analysis.
+			if src != nil && isSelfAssign(dst, src) {
+				if base.Flag.LowerM != 0 {
+					base.WarnfAt(where.Pos(), "%v ignoring self-assignment in %v", e.curfn, where)
+				}
+				k = e.discardHole()
+			}
+		}
+
+		e.expr(k.note(where, why), src)
+	}
+
+	e.reassigned(ks, where)
+}
+
+// reassigned marks the locations associated with the given holes as
+// reassigned, unless the location represents a variable declared and
+// assigned exactly once by where.
+func (e *escape) reassigned(ks []hole, where ir.Node) {
+	if as, ok := where.(*ir.AssignStmt); ok && as.Op() == ir.OAS && as.Y == nil {
+		if dst, ok := as.X.(*ir.Name); ok && dst.Op() == ir.ONAME && dst.Defn == nil {
+			// Zero-value assignment for variable declared without an
+			// explicit initial value. Assume this is its initialization
+			// statement.
+			return
+		}
+	}
+
+	for _, k := range ks {
+		loc := k.dst
+		// Variables declared by range statements are assigned on every iteration.
+		if n, ok := loc.n.(*ir.Name); ok && n.Defn == where && where.Op() != ir.ORANGE {
+			continue
+		}
+		loc.reassigned = true
+	}
+}
diff --git a/src/cmd/compile/internal/escape/call.go b/src/cmd/compile/internal/escape/call.go
new file mode 100644
index 0000000000000000000000000000000000000000..9e5abed59142edaf7b6dba120d733f765e4cf6cb
--- /dev/null
+++ b/src/cmd/compile/internal/escape/call.go
@@ -0,0 +1,428 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/src"
+)
+
+// call evaluates a call expressions, including builtin calls. ks
+// should contain the holes representing where the function callee's
+// results flows.
+func (e *escape) call(ks []hole, call ir.Node) {
+	var init ir.Nodes
+	e.callCommon(ks, call, &init, nil)
+	if len(init) != 0 {
+		call.(*ir.CallExpr).PtrInit().Append(init...)
+	}
+}
+
+func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir.Func) {
+
+	// argumentPragma handles escape analysis of argument *argp to the
+	// given hole. If the function callee is known, pragma is the
+	// function's pragma flags; otherwise 0.
+	argumentFunc := func(fn *ir.Name, k hole, argp *ir.Node) {
+		e.rewriteArgument(argp, init, call, fn, wrapper)
+
+		e.expr(k.note(call, "call parameter"), *argp)
+	}
+
+	argument := func(k hole, argp *ir.Node) {
+		argumentFunc(nil, k, argp)
+	}
+
+	switch call.Op() {
+	default:
+		ir.Dump("esc", call)
+		base.Fatalf("unexpected call op: %v", call.Op())
+
+	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
+		call := call.(*ir.CallExpr)
+		typecheck.FixVariadicCall(call)
+		typecheck.FixMethodCall(call)
+
+		// Pick out the function callee, if statically known.
+		//
+		// TODO(mdempsky): Change fn from *ir.Name to *ir.Func, but some
+		// functions (e.g., runtime builtins, method wrappers, generated
+		// eq/hash functions) don't have it set. Investigate whether
+		// that's a concern.
+		var fn *ir.Name
+		switch call.Op() {
+		case ir.OCALLFUNC:
+			// If we have a direct call to a closure (not just one we were
+			// able to statically resolve with ir.StaticValue), mark it as
+			// such so batch.outlives can optimize the flow results.
+			if call.X.Op() == ir.OCLOSURE {
+				call.X.(*ir.ClosureExpr).Func.SetClosureCalled(true)
+			}
+
+			switch v := ir.StaticValue(call.X); v.Op() {
+			case ir.ONAME:
+				if v := v.(*ir.Name); v.Class == ir.PFUNC {
+					fn = v
+				}
+			case ir.OCLOSURE:
+				fn = v.(*ir.ClosureExpr).Func.Nname
+			case ir.OMETHEXPR:
+				fn = ir.MethodExprName(v)
+			}
+		case ir.OCALLMETH:
+			base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+		}
+
+		fntype := call.X.Type()
+		if fn != nil {
+			fntype = fn.Type()
+		}
+
+		if ks != nil && fn != nil && e.inMutualBatch(fn) {
+			for i, result := range fn.Type().Results().FieldSlice() {
+				e.expr(ks[i], ir.AsNode(result.Nname))
+			}
+		}
+
+		var recvp *ir.Node
+		if call.Op() == ir.OCALLFUNC {
+			// Evaluate callee function expression.
+			//
+			// Note: We use argument and not argumentFunc, because while
+			// call.X here may be an argument to runtime.{new,defer}proc,
+			// it's not an argument to fn itself.
+			argument(e.discardHole(), &call.X)
+		} else {
+			recvp = &call.X.(*ir.SelectorExpr).X
+		}
+
+		args := call.Args
+		if recv := fntype.Recv(); recv != nil {
+			if recvp == nil {
+				// Function call using method expression. Recevier argument is
+				// at the front of the regular arguments list.
+				recvp = &args[0]
+				args = args[1:]
+			}
+
+			argumentFunc(fn, e.tagHole(ks, fn, recv), recvp)
+		}
+
+		for i, param := range fntype.Params().FieldSlice() {
+			argumentFunc(fn, e.tagHole(ks, fn, param), &args[i])
+		}
+
+	case ir.OINLCALL:
+		call := call.(*ir.InlinedCallExpr)
+		e.stmts(call.Body)
+		for i, result := range call.ReturnVars {
+			k := e.discardHole()
+			if ks != nil {
+				k = ks[i]
+			}
+			e.expr(k, result)
+		}
+
+	case ir.OAPPEND:
+		call := call.(*ir.CallExpr)
+		args := call.Args
+
+		// Appendee slice may flow directly to the result, if
+		// it has enough capacity. Alternatively, a new heap
+		// slice might be allocated, and all slice elements
+		// might flow to heap.
+		appendeeK := ks[0]
+		if args[0].Type().Elem().HasPointers() {
+			appendeeK = e.teeHole(appendeeK, e.heapHole().deref(call, "appendee slice"))
+		}
+		argument(appendeeK, &args[0])
+
+		if call.IsDDD {
+			appendedK := e.discardHole()
+			if args[1].Type().IsSlice() && args[1].Type().Elem().HasPointers() {
+				appendedK = e.heapHole().deref(call, "appended slice...")
+			}
+			argument(appendedK, &args[1])
+		} else {
+			for i := 1; i < len(args); i++ {
+				argument(e.heapHole(), &args[i])
+			}
+		}
+
+	case ir.OCOPY:
+		call := call.(*ir.BinaryExpr)
+		argument(e.discardHole(), &call.X)
+
+		copiedK := e.discardHole()
+		if call.Y.Type().IsSlice() && call.Y.Type().Elem().HasPointers() {
+			copiedK = e.heapHole().deref(call, "copied slice")
+		}
+		argument(copiedK, &call.Y)
+
+	case ir.OPANIC:
+		call := call.(*ir.UnaryExpr)
+		argument(e.heapHole(), &call.X)
+
+	case ir.OCOMPLEX:
+		call := call.(*ir.BinaryExpr)
+		argument(e.discardHole(), &call.X)
+		argument(e.discardHole(), &call.Y)
+
+	case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+		call := call.(*ir.CallExpr)
+		fixRecoverCall(call)
+		for i := range call.Args {
+			argument(e.discardHole(), &call.Args[i])
+		}
+
+	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE:
+		call := call.(*ir.UnaryExpr)
+		argument(e.discardHole(), &call.X)
+
+	case ir.OUNSAFEADD, ir.OUNSAFESLICE:
+		call := call.(*ir.BinaryExpr)
+		argument(ks[0], &call.X)
+		argument(e.discardHole(), &call.Y)
+	}
+}
+
+// goDeferStmt analyzes a "go" or "defer" statement.
+//
+// In the process, it also normalizes the statement to always use a
+// simple function call with no arguments and no results. For example,
+// it rewrites:
+//
+//	defer f(x, y)
+//
+// into:
+//
+//	x1, y1 := x, y
+//	defer func() { f(x1, y1) }()
+func (e *escape) goDeferStmt(n *ir.GoDeferStmt) {
+	k := e.heapHole()
+	if n.Op() == ir.ODEFER && e.loopDepth == 1 {
+		// Top-level defer arguments don't escape to the heap,
+		// but they do need to last until they're invoked.
+		k = e.later(e.discardHole())
+
+		// force stack allocation of defer record, unless
+		// open-coded defers are used (see ssa.go)
+		n.SetEsc(ir.EscNever)
+	}
+
+	call := n.Call
+
+	init := n.PtrInit()
+	init.Append(ir.TakeInit(call)...)
+	e.stmts(*init)
+
+	// If the function is already a zero argument/result function call,
+	// just escape analyze it normally.
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC {
+		if sig := call.X.Type(); sig.NumParams()+sig.NumResults() == 0 {
+			if clo, ok := call.X.(*ir.ClosureExpr); ok && n.Op() == ir.OGO {
+				clo.IsGoWrap = true
+			}
+			e.expr(k, call.X)
+			return
+		}
+	}
+
+	// Create a new no-argument function that we'll hand off to defer.
+	fn := ir.NewClosureFunc(n.Pos(), true)
+	fn.SetWrapper(true)
+	fn.Nname.SetType(types.NewSignature(types.LocalPkg, nil, nil, nil, nil))
+	fn.Body = []ir.Node{call}
+
+	clo := fn.OClosure
+	if n.Op() == ir.OGO {
+		clo.IsGoWrap = true
+	}
+
+	e.callCommon(nil, call, init, fn)
+	e.closures = append(e.closures, closure{e.spill(k, clo), clo})
+
+	// Create new top level call to closure.
+	n.Call = ir.NewCallExpr(call.Pos(), ir.OCALL, clo, nil)
+	ir.WithFunc(e.curfn, func() {
+		typecheck.Stmt(n.Call)
+	})
+}
+
+// rewriteArgument rewrites the argument *argp of the given call expression.
+// fn is the static callee function, if known.
+// wrapper is the go/defer wrapper function for call, if any.
+func (e *escape) rewriteArgument(argp *ir.Node, init *ir.Nodes, call ir.Node, fn *ir.Name, wrapper *ir.Func) {
+	var pragma ir.PragmaFlag
+	if fn != nil && fn.Func != nil {
+		pragma = fn.Func.Pragma
+	}
+
+	// unsafeUintptr rewrites "uintptr(ptr)" arguments to syscall-like
+	// functions, so that ptr is kept alive and/or escaped as
+	// appropriate. unsafeUintptr also reports whether it modified arg0.
+	unsafeUintptr := func(arg0 ir.Node) bool {
+		if pragma&(ir.UintptrKeepAlive|ir.UintptrEscapes) == 0 {
+			return false
+		}
+
+		// If the argument is really a pointer being converted to uintptr,
+		// arrange for the pointer to be kept alive until the call returns,
+		// by copying it into a temp and marking that temp
+		// still alive when we pop the temp stack.
+		if arg0.Op() != ir.OCONVNOP || !arg0.Type().IsUintptr() {
+			return false
+		}
+		arg := arg0.(*ir.ConvExpr)
+
+		if !arg.X.Type().IsUnsafePtr() {
+			return false
+		}
+
+		// Create and declare a new pointer-typed temp variable.
+		tmp := e.wrapExpr(arg.Pos(), &arg.X, init, call, wrapper)
+
+		if pragma&ir.UintptrEscapes != 0 {
+			e.flow(e.heapHole().note(arg, "//go:uintptrescapes"), e.oldLoc(tmp))
+		}
+
+		if pragma&ir.UintptrKeepAlive != 0 {
+			call := call.(*ir.CallExpr)
+
+			// SSA implements CallExpr.KeepAlive using OpVarLive, which
+			// doesn't support PAUTOHEAP variables. I tried changing it to
+			// use OpKeepAlive, but that ran into issues of its own.
+			// For now, the easy solution is to explicitly copy to (yet
+			// another) new temporary variable.
+			keep := tmp
+			if keep.Class == ir.PAUTOHEAP {
+				keep = e.copyExpr(arg.Pos(), tmp, call.PtrInit(), wrapper, false)
+			}
+
+			keep.SetAddrtaken(true) // ensure SSA keeps the tmp variable
+			call.KeepAlive = append(call.KeepAlive, keep)
+		}
+
+		return true
+	}
+
+	visit := func(pos src.XPos, argp *ir.Node) {
+		// Optimize a few common constant expressions. By leaving these
+		// untouched in the call expression, we let the wrapper handle
+		// evaluating them, rather than taking up closure context space.
+		switch arg := *argp; arg.Op() {
+		case ir.OLITERAL, ir.ONIL, ir.OMETHEXPR:
+			return
+		case ir.ONAME:
+			if arg.(*ir.Name).Class == ir.PFUNC {
+				return
+			}
+		}
+
+		if unsafeUintptr(*argp) {
+			return
+		}
+
+		if wrapper != nil {
+			e.wrapExpr(pos, argp, init, call, wrapper)
+		}
+	}
+
+	// Peel away any slice lits.
+	if arg := *argp; arg.Op() == ir.OSLICELIT {
+		list := arg.(*ir.CompLitExpr).List
+		for i := range list {
+			visit(arg.Pos(), &list[i])
+		}
+	} else {
+		visit(call.Pos(), argp)
+	}
+}
+
+// wrapExpr replaces *exprp with a temporary variable copy. If wrapper
+// is non-nil, the variable will be captured for use within that
+// function.
+func (e *escape) wrapExpr(pos src.XPos, exprp *ir.Node, init *ir.Nodes, call ir.Node, wrapper *ir.Func) *ir.Name {
+	tmp := e.copyExpr(pos, *exprp, init, e.curfn, true)
+
+	if wrapper != nil {
+		// Currently for "defer i.M()" if i is nil it panics at the point
+		// of defer statement, not when deferred function is called.  We
+		// need to do the nil check outside of the wrapper.
+		if call.Op() == ir.OCALLINTER && exprp == &call.(*ir.CallExpr).X.(*ir.SelectorExpr).X {
+			check := ir.NewUnaryExpr(pos, ir.OCHECKNIL, ir.NewUnaryExpr(pos, ir.OITAB, tmp))
+			init.Append(typecheck.Stmt(check))
+		}
+
+		e.oldLoc(tmp).captured = true
+
+		tmp = ir.NewClosureVar(pos, wrapper, tmp)
+	}
+
+	*exprp = tmp
+	return tmp
+}
+
+// copyExpr creates and returns a new temporary variable within fn;
+// appends statements to init to declare and initialize it to expr;
+// and escape analyzes the data flow if analyze is true.
+func (e *escape) copyExpr(pos src.XPos, expr ir.Node, init *ir.Nodes, fn *ir.Func, analyze bool) *ir.Name {
+	if ir.HasUniquePos(expr) {
+		pos = expr.Pos()
+	}
+
+	tmp := typecheck.TempAt(pos, fn, expr.Type())
+
+	stmts := []ir.Node{
+		ir.NewDecl(pos, ir.ODCL, tmp),
+		ir.NewAssignStmt(pos, tmp, expr),
+	}
+	typecheck.Stmts(stmts)
+	init.Append(stmts...)
+
+	if analyze {
+		e.newLoc(tmp, false)
+		e.stmts(stmts)
+	}
+
+	return tmp
+}
+
+// tagHole returns a hole for evaluating an argument passed to param.
+// ks should contain the holes representing where the function
+// callee's results flows. fn is the statically-known callee function,
+// if any.
+func (e *escape) tagHole(ks []hole, fn *ir.Name, param *types.Field) hole {
+	// If this is a dynamic call, we can't rely on param.Note.
+	if fn == nil {
+		return e.heapHole()
+	}
+
+	if e.inMutualBatch(fn) {
+		return e.addr(ir.AsNode(param.Nname))
+	}
+
+	// Call to previously tagged function.
+
+	var tagKs []hole
+
+	esc := parseLeaks(param.Note)
+	if x := esc.Heap(); x >= 0 {
+		tagKs = append(tagKs, e.heapHole().shift(x))
+	}
+
+	if ks != nil {
+		for i := 0; i < numEscResults; i++ {
+			if x := esc.Result(i); x >= 0 {
+				tagKs = append(tagKs, ks[i].shift(x))
+			}
+		}
+	}
+
+	return e.teeHole(tagKs...)
+}
diff --git a/src/cmd/compile/internal/escape/desugar.go b/src/cmd/compile/internal/escape/desugar.go
new file mode 100644
index 0000000000000000000000000000000000000000..8b3cc25cf9a4a684810107e1124546d6e9b3b187
--- /dev/null
+++ b/src/cmd/compile/internal/escape/desugar.go
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+)
+
+// TODO(mdempsky): Desugaring doesn't belong during escape analysis,
+// but for now it's the most convenient place for some rewrites.
+
+// fixRecoverCall rewrites an ORECOVER call into ORECOVERFP,
+// adding an explicit frame pointer argument.
+// If call is not an ORECOVER call, it's left unmodified.
+func fixRecoverCall(call *ir.CallExpr) {
+	if call.Op() != ir.ORECOVER {
+		return
+	}
+
+	pos := call.Pos()
+
+	// FP is equal to caller's SP plus FixedFrameSize().
+	var fp ir.Node = ir.NewCallExpr(pos, ir.OGETCALLERSP, nil, nil)
+	if off := base.Ctxt.FixedFrameSize(); off != 0 {
+		fp = ir.NewBinaryExpr(fp.Pos(), ir.OADD, fp, ir.NewInt(off))
+	}
+	// TODO(mdempsky): Replace *int32 with unsafe.Pointer, without upsetting checkptr.
+	fp = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewPtr(types.Types[types.TINT32]), fp)
+
+	call.SetOp(ir.ORECOVERFP)
+	call.Args = []ir.Node{typecheck.Expr(fp)}
+}
diff --git a/src/cmd/compile/internal/escape/escape.go b/src/cmd/compile/internal/escape/escape.go
index cd56f07b6147a431cf0347e65c5c91df2d98d29d..61e0121a40aec2ea54b6829932eecd3641e00ba6 100644
--- a/src/cmd/compile/internal/escape/escape.go
+++ b/src/cmd/compile/internal/escape/escape.go
@@ -6,15 +6,11 @@ package escape
 
 import (
 	"fmt"
-	"math"
-	"strings"
 
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/logopt"
-	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
-	"cmd/internal/src"
 )
 
 // Escape analysis.
@@ -118,90 +114,8 @@ type escape struct {
 	loopDepth int
 }
 
-// An location represents an abstract location that stores a Go
-// variable.
-type location struct {
-	n         ir.Node  // represented variable or expression, if any
-	curfn     *ir.Func // enclosing function
-	edges     []edge   // incoming edges
-	loopDepth int      // loopDepth at declaration
-
-	// resultIndex records the tuple index (starting at 1) for
-	// PPARAMOUT variables within their function's result type.
-	// For non-PPARAMOUT variables it's 0.
-	resultIndex int
-
-	// derefs and walkgen are used during walkOne to track the
-	// minimal dereferences from the walk root.
-	derefs  int // >= -1
-	walkgen uint32
-
-	// dst and dstEdgeindex track the next immediate assignment
-	// destination location during walkone, along with the index
-	// of the edge pointing back to this location.
-	dst        *location
-	dstEdgeIdx int
-
-	// queued is used by walkAll to track whether this location is
-	// in the walk queue.
-	queued bool
-
-	// escapes reports whether the represented variable's address
-	// escapes; that is, whether the variable must be heap
-	// allocated.
-	escapes bool
-
-	// transient reports whether the represented expression's
-	// address does not outlive the statement; that is, whether
-	// its storage can be immediately reused.
-	transient bool
-
-	// paramEsc records the represented parameter's leak set.
-	paramEsc leaks
-
-	captured   bool // has a closure captured this variable?
-	reassigned bool // has this variable been reassigned?
-	addrtaken  bool // has this variable's address been taken?
-}
-
-// An edge represents an assignment edge between two Go variables.
-type edge struct {
-	src    *location
-	derefs int // >= -1
-	notes  *note
-}
-
-// Fmt is called from node printing to print information about escape analysis results.
-func Fmt(n ir.Node) string {
-	text := ""
-	switch n.Esc() {
-	case ir.EscUnknown:
-		break
-
-	case ir.EscHeap:
-		text = "esc(h)"
-
-	case ir.EscNone:
-		text = "esc(no)"
-
-	case ir.EscNever:
-		text = "esc(N)"
-
-	default:
-		text = fmt.Sprintf("esc(%d)", n.Esc())
-	}
-
-	if n.Op() == ir.ONAME {
-		n := n.(*ir.Name)
-		if loc, ok := n.Opt.(*location); ok && loc.loopDepth != 0 {
-			if text != "" {
-				text += " "
-			}
-			text += fmt.Sprintf("ld(%d)", loc.loopDepth)
-		}
-	}
-
-	return text
+func Funcs(all []ir.Node) {
+	ir.VisitFuncsBottomUp(all, Batch)
 }
 
 // Batch performs escape analysis on a minimal batch of
@@ -269,8 +183,14 @@ func (b *batch) initFunc(fn *ir.Func) {
 
 	// Allocate locations for local variables.
 	for _, n := range fn.Dcl {
-		if n.Op() == ir.ONAME {
-			e.newLoc(n, false)
+		e.newLoc(n, false)
+	}
+
+	// Also for hidden parameters (e.g., the ".this" parameter to a
+	// method value wrapper).
+	if fn.OClosure == nil {
+		for _, n := range fn.ClosureVars {
+			e.newLoc(n.Canonical(), false)
 		}
 	}
 
@@ -342,1771 +262,173 @@ func (b *batch) flowClosure(k hole, clo *ir.ClosureExpr) {
 	}
 }
 
-// Below we implement the methods for walking the AST and recording
-// data flow edges. Note that because a sub-expression might have
-// side-effects, it's important to always visit the entire AST.
-//
-// For example, write either:
-//
-//     if x {
-//         e.discard(n.Left)
-//     } else {
-//         e.value(k, n.Left)
-//     }
-//
-// or
-//
-//     if x {
-//         k = e.discardHole()
-//     }
-//     e.value(k, n.Left)
-//
-// Do NOT write:
-//
-//    // BAD: possibly loses side-effects within n.Left
-//    if !x {
-//        e.value(k, n.Left)
-//    }
-
-// stmt evaluates a single Go statement.
-func (e *escape) stmt(n ir.Node) {
-	if n == nil {
-		return
-	}
-
-	lno := ir.SetPos(n)
-	defer func() {
-		base.Pos = lno
-	}()
-
-	if base.Flag.LowerM > 2 {
-		fmt.Printf("%v:[%d] %v stmt: %v\n", base.FmtPos(base.Pos), e.loopDepth, e.curfn, n)
-	}
-
-	e.stmts(n.Init())
-
-	switch n.Op() {
-	default:
-		base.Fatalf("unexpected stmt: %v", n)
-
-	case ir.ODCLCONST, ir.ODCLTYPE, ir.OFALL, ir.OINLMARK:
-		// nop
-
-	case ir.OBREAK, ir.OCONTINUE, ir.OGOTO:
-		// TODO(mdempsky): Handle dead code?
-
-	case ir.OBLOCK:
-		n := n.(*ir.BlockStmt)
-		e.stmts(n.List)
-
-	case ir.ODCL:
-		// Record loop depth at declaration.
-		n := n.(*ir.Decl)
-		if !ir.IsBlank(n.X) {
-			e.dcl(n.X)
-		}
-
-	case ir.OLABEL:
-		n := n.(*ir.LabelStmt)
-		switch e.labels[n.Label] {
-		case nonlooping:
-			if base.Flag.LowerM > 2 {
-				fmt.Printf("%v:%v non-looping label\n", base.FmtPos(base.Pos), n)
-			}
-		case looping:
-			if base.Flag.LowerM > 2 {
-				fmt.Printf("%v: %v looping label\n", base.FmtPos(base.Pos), n)
-			}
-			e.loopDepth++
-		default:
-			base.Fatalf("label missing tag")
-		}
-		delete(e.labels, n.Label)
-
-	case ir.OIF:
-		n := n.(*ir.IfStmt)
-		e.discard(n.Cond)
-		e.block(n.Body)
-		e.block(n.Else)
-
-	case ir.OFOR, ir.OFORUNTIL:
-		n := n.(*ir.ForStmt)
-		e.loopDepth++
-		e.discard(n.Cond)
-		e.stmt(n.Post)
-		e.block(n.Body)
-		e.loopDepth--
-
-	case ir.ORANGE:
-		// for Key, Value = range X { Body }
-		n := n.(*ir.RangeStmt)
-
-		// X is evaluated outside the loop.
-		tmp := e.newLoc(nil, false)
-		e.expr(tmp.asHole(), n.X)
-
-		e.loopDepth++
-		ks := e.addrs([]ir.Node{n.Key, n.Value})
-		if n.X.Type().IsArray() {
-			e.flow(ks[1].note(n, "range"), tmp)
-		} else {
-			e.flow(ks[1].deref(n, "range-deref"), tmp)
-		}
-		e.reassigned(ks, n)
-
-		e.block(n.Body)
-		e.loopDepth--
-
-	case ir.OSWITCH:
-		n := n.(*ir.SwitchStmt)
+func (b *batch) finish(fns []*ir.Func) {
+	// Record parameter tags for package export data.
+	for _, fn := range fns {
+		fn.SetEsc(escFuncTagged)
 
-		if guard, ok := n.Tag.(*ir.TypeSwitchGuard); ok {
-			var ks []hole
-			if guard.Tag != nil {
-				for _, cas := range n.Cases {
-					cv := cas.Var
-					k := e.dcl(cv) // type switch variables have no ODCL.
-					if cv.Type().HasPointers() {
-						ks = append(ks, k.dotType(cv.Type(), cas, "switch case"))
-					}
-				}
+		narg := 0
+		for _, fs := range &types.RecvsParams {
+			for _, f := range fs(fn.Type()).Fields().Slice() {
+				narg++
+				f.Note = b.paramTag(fn, narg, f)
 			}
-			e.expr(e.teeHole(ks...), n.Tag.(*ir.TypeSwitchGuard).X)
-		} else {
-			e.discard(n.Tag)
-		}
-
-		for _, cas := range n.Cases {
-			e.discards(cas.List)
-			e.block(cas.Body)
-		}
-
-	case ir.OSELECT:
-		n := n.(*ir.SelectStmt)
-		for _, cas := range n.Cases {
-			e.stmt(cas.Comm)
-			e.block(cas.Body)
-		}
-	case ir.ORECV:
-		// TODO(mdempsky): Consider e.discard(n.Left).
-		n := n.(*ir.UnaryExpr)
-		e.exprSkipInit(e.discardHole(), n) // already visited n.Ninit
-	case ir.OSEND:
-		n := n.(*ir.SendStmt)
-		e.discard(n.Chan)
-		e.assignHeap(n.Value, "send", n)
-
-	case ir.OAS:
-		n := n.(*ir.AssignStmt)
-		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
-	case ir.OASOP:
-		n := n.(*ir.AssignOpStmt)
-		// TODO(mdempsky): Worry about OLSH/ORSH?
-		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
-	case ir.OAS2:
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair", n)
-
-	case ir.OAS2DOTTYPE: // v, ok = x.(type)
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair-dot-type", n)
-	case ir.OAS2MAPR: // v, ok = m[k]
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair-mapr", n)
-	case ir.OAS2RECV, ir.OSELRECV2: // v, ok = <-ch
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair-receive", n)
-
-	case ir.OAS2FUNC:
-		n := n.(*ir.AssignListStmt)
-		e.stmts(n.Rhs[0].Init())
-		ks := e.addrs(n.Lhs)
-		e.call(ks, n.Rhs[0], nil)
-		e.reassigned(ks, n)
-	case ir.ORETURN:
-		n := n.(*ir.ReturnStmt)
-		results := e.curfn.Type().Results().FieldSlice()
-		dsts := make([]ir.Node, len(results))
-		for i, res := range results {
-			dsts[i] = res.Nname.(*ir.Name)
 		}
-		e.assignList(dsts, n.Results, "return", n)
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER, ir.OCLOSE, ir.OCOPY, ir.ODELETE, ir.OPANIC, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
-		e.call(nil, n, nil)
-	case ir.OGO, ir.ODEFER:
-		n := n.(*ir.GoDeferStmt)
-		e.stmts(n.Call.Init())
-		e.call(nil, n.Call, n)
-
-	case ir.OTAILCALL:
-		// TODO(mdempsky): Treat like a normal call? esc.go used to just ignore it.
-	}
-}
-
-func (e *escape) stmts(l ir.Nodes) {
-	for _, n := range l {
-		e.stmt(n)
-	}
-}
-
-// block is like stmts, but preserves loopDepth.
-func (e *escape) block(l ir.Nodes) {
-	old := e.loopDepth
-	e.stmts(l)
-	e.loopDepth = old
-}
-
-// expr models evaluating an expression n and flowing the result into
-// hole k.
-func (e *escape) expr(k hole, n ir.Node) {
-	if n == nil {
-		return
-	}
-	e.stmts(n.Init())
-	e.exprSkipInit(k, n)
-}
-
-func (e *escape) exprSkipInit(k hole, n ir.Node) {
-	if n == nil {
-		return
-	}
-
-	lno := ir.SetPos(n)
-	defer func() {
-		base.Pos = lno
-	}()
-
-	uintptrEscapesHack := k.uintptrEscapesHack
-	k.uintptrEscapesHack = false
-
-	if uintptrEscapesHack && n.Op() == ir.OCONVNOP && n.(*ir.ConvExpr).X.Type().IsUnsafePtr() {
-		// nop
-	} else if k.derefs >= 0 && !n.Type().HasPointers() {
-		k.dst = &e.blankLoc
 	}
 
-	switch n.Op() {
-	default:
-		base.Fatalf("unexpected expr: %s %v", n.Op().String(), n)
-
-	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OTYPE, ir.OMETHEXPR, ir.OLINKSYMOFFSET:
-		// nop
-
-	case ir.ONAME:
-		n := n.(*ir.Name)
-		if n.Class == ir.PFUNC || n.Class == ir.PEXTERN {
-			return
-		}
-		if n.IsClosureVar() && n.Defn == nil {
-			return // ".this" from method value wrapper
-		}
-		e.flow(k, e.oldLoc(n))
-
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT:
-		n := n.(*ir.UnaryExpr)
-		e.discard(n.X)
-	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
-		n := n.(*ir.BinaryExpr)
-		e.discard(n.X)
-		e.discard(n.Y)
-	case ir.OANDAND, ir.OOROR:
-		n := n.(*ir.LogicalExpr)
-		e.discard(n.X)
-		e.discard(n.Y)
-	case ir.OADDR:
-		n := n.(*ir.AddrExpr)
-		e.expr(k.addr(n, "address-of"), n.X) // "address-of"
-	case ir.ODEREF:
-		n := n.(*ir.StarExpr)
-		e.expr(k.deref(n, "indirection"), n.X) // "indirection"
-	case ir.ODOT, ir.ODOTMETH, ir.ODOTINTER:
-		n := n.(*ir.SelectorExpr)
-		e.expr(k.note(n, "dot"), n.X)
-	case ir.ODOTPTR:
-		n := n.(*ir.SelectorExpr)
-		e.expr(k.deref(n, "dot of pointer"), n.X) // "dot of pointer"
-	case ir.ODOTTYPE, ir.ODOTTYPE2:
-		n := n.(*ir.TypeAssertExpr)
-		e.expr(k.dotType(n.Type(), n, "dot"), n.X)
-	case ir.OINDEX:
-		n := n.(*ir.IndexExpr)
-		if n.X.Type().IsArray() {
-			e.expr(k.note(n, "fixed-array-index-of"), n.X)
-		} else {
-			// TODO(mdempsky): Fix why reason text.
-			e.expr(k.deref(n, "dot of pointer"), n.X)
-		}
-		e.discard(n.Index)
-	case ir.OINDEXMAP:
-		n := n.(*ir.IndexExpr)
-		e.discard(n.X)
-		e.discard(n.Index)
-	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR, ir.OSLICESTR:
-		n := n.(*ir.SliceExpr)
-		e.expr(k.note(n, "slice"), n.X)
-		e.discard(n.Low)
-		e.discard(n.High)
-		e.discard(n.Max)
-
-	case ir.OCONV, ir.OCONVNOP:
-		n := n.(*ir.ConvExpr)
-		if ir.ShouldCheckPtr(e.curfn, 2) && n.Type().IsUnsafePtr() && n.X.Type().IsPtr() {
-			// When -d=checkptr=2 is enabled, treat
-			// conversions to unsafe.Pointer as an
-			// escaping operation. This allows better
-			// runtime instrumentation, since we can more
-			// easily detect object boundaries on the heap
-			// than the stack.
-			e.assignHeap(n.X, "conversion to unsafe.Pointer", n)
-		} else if n.Type().IsUnsafePtr() && n.X.Type().IsUintptr() {
-			e.unsafeValue(k, n.X)
-		} else {
-			e.expr(k, n.X)
-		}
-	case ir.OCONVIFACE:
-		n := n.(*ir.ConvExpr)
-		if !n.X.Type().IsInterface() && !types.IsDirectIface(n.X.Type()) {
-			k = e.spill(k, n)
-		}
-		e.expr(k.note(n, "interface-converted"), n.X)
-	case ir.OSLICE2ARRPTR:
-		// the slice pointer flows directly to the result
-		n := n.(*ir.ConvExpr)
-		e.expr(k, n.X)
-	case ir.ORECV:
-		n := n.(*ir.UnaryExpr)
-		e.discard(n.X)
-
-	case ir.OCALLMETH, ir.OCALLFUNC, ir.OCALLINTER, ir.OLEN, ir.OCAP, ir.OCOMPLEX, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.OCOPY, ir.OUNSAFEADD, ir.OUNSAFESLICE:
-		e.call([]hole{k}, n, nil)
-
-	case ir.ONEW:
-		n := n.(*ir.UnaryExpr)
-		e.spill(k, n)
-
-	case ir.OMAKESLICE:
-		n := n.(*ir.MakeExpr)
-		e.spill(k, n)
-		e.discard(n.Len)
-		e.discard(n.Cap)
-	case ir.OMAKECHAN:
-		n := n.(*ir.MakeExpr)
-		e.discard(n.Len)
-	case ir.OMAKEMAP:
-		n := n.(*ir.MakeExpr)
-		e.spill(k, n)
-		e.discard(n.Len)
-
-	case ir.ORECOVER:
-		// nop
-
-	case ir.OCALLPART:
-		// Flow the receiver argument to both the closure and
-		// to the receiver parameter.
-
-		n := n.(*ir.SelectorExpr)
-		closureK := e.spill(k, n)
-
-		m := n.Selection
-
-		// We don't know how the method value will be called
-		// later, so conservatively assume the result
-		// parameters all flow to the heap.
-		//
-		// TODO(mdempsky): Change ks into a callback, so that
-		// we don't have to create this slice?
-		var ks []hole
-		for i := m.Type.NumResults(); i > 0; i-- {
-			ks = append(ks, e.heapHole())
-		}
-		name, _ := m.Nname.(*ir.Name)
-		paramK := e.tagHole(ks, name, m.Type.Recv())
-
-		e.expr(e.teeHole(paramK, closureK), n.X)
-
-	case ir.OPTRLIT:
-		n := n.(*ir.AddrExpr)
-		e.expr(e.spill(k, n), n.X)
-
-	case ir.OARRAYLIT:
-		n := n.(*ir.CompLitExpr)
-		for _, elt := range n.List {
-			if elt.Op() == ir.OKEY {
-				elt = elt.(*ir.KeyExpr).Value
-			}
-			e.expr(k.note(n, "array literal element"), elt)
-		}
-
-	case ir.OSLICELIT:
-		n := n.(*ir.CompLitExpr)
-		k = e.spill(k, n)
-		k.uintptrEscapesHack = uintptrEscapesHack // for ...uintptr parameters
-
-		for _, elt := range n.List {
-			if elt.Op() == ir.OKEY {
-				elt = elt.(*ir.KeyExpr).Value
-			}
-			e.expr(k.note(n, "slice-literal-element"), elt)
-		}
-
-	case ir.OSTRUCTLIT:
-		n := n.(*ir.CompLitExpr)
-		for _, elt := range n.List {
-			e.expr(k.note(n, "struct literal element"), elt.(*ir.StructKeyExpr).Value)
+	for _, loc := range b.allLocs {
+		n := loc.n
+		if n == nil {
+			continue
 		}
-
-	case ir.OMAPLIT:
-		n := n.(*ir.CompLitExpr)
-		e.spill(k, n)
-
-		// Map keys and values are always stored in the heap.
-		for _, elt := range n.List {
-			elt := elt.(*ir.KeyExpr)
-			e.assignHeap(elt.Key, "map literal key", n)
-			e.assignHeap(elt.Value, "map literal value", n)
+		if n.Op() == ir.ONAME {
+			n := n.(*ir.Name)
+			n.Opt = nil
 		}
 
-	case ir.OCLOSURE:
-		n := n.(*ir.ClosureExpr)
-		k = e.spill(k, n)
-		e.closures = append(e.closures, closure{k, n})
+		// Update n.Esc based on escape analysis results.
 
-		if fn := n.Func; fn.IsHiddenClosure() {
-			for _, cv := range fn.ClosureVars {
-				if loc := e.oldLoc(cv); !loc.captured {
-					loc.captured = true
+		// Omit escape diagnostics for go/defer wrappers, at least for now.
+		// Historically, we haven't printed them, and test cases don't expect them.
+		// TODO(mdempsky): Update tests to expect this.
+		goDeferWrapper := n.Op() == ir.OCLOSURE && n.(*ir.ClosureExpr).Func.Wrapper()
 
-					// Ignore reassignments to the variable in straightline code
-					// preceding the first capture by a closure.
-					if loc.loopDepth == e.loopDepth {
-						loc.reassigned = false
-					}
+		if loc.escapes {
+			if n.Op() == ir.ONAME {
+				if base.Flag.CompilingRuntime {
+					base.ErrorfAt(n.Pos(), "%v escapes to heap, not allowed in runtime", n)
+				}
+				if base.Flag.LowerM != 0 {
+					base.WarnfAt(n.Pos(), "moved to heap: %v", n)
+				}
+			} else {
+				if base.Flag.LowerM != 0 && !goDeferWrapper {
+					base.WarnfAt(n.Pos(), "%v escapes to heap", n)
+				}
+				if logopt.Enabled() {
+					var e_curfn *ir.Func // TODO(mdempsky): Fix.
+					logopt.LogOpt(n.Pos(), "escape", "escape", ir.FuncName(e_curfn))
 				}
 			}
-
-			for _, n := range fn.Dcl {
-				// Add locations for local variables of the
-				// closure, if needed, in case we're not including
-				// the closure func in the batch for escape
-				// analysis (happens for escape analysis called
-				// from reflectdata.methodWrapper)
-				if n.Op() == ir.ONAME && n.Opt == nil {
-					e.with(fn).newLoc(n, false)
+			n.SetEsc(ir.EscHeap)
+		} else {
+			if base.Flag.LowerM != 0 && n.Op() != ir.ONAME && !goDeferWrapper {
+				base.WarnfAt(n.Pos(), "%v does not escape", n)
+			}
+			n.SetEsc(ir.EscNone)
+			if loc.transient {
+				switch n.Op() {
+				case ir.OCLOSURE:
+					n := n.(*ir.ClosureExpr)
+					n.SetTransient(true)
+				case ir.OMETHVALUE:
+					n := n.(*ir.SelectorExpr)
+					n.SetTransient(true)
+				case ir.OSLICELIT:
+					n := n.(*ir.CompLitExpr)
+					n.SetTransient(true)
 				}
 			}
-			e.walkFunc(fn)
 		}
-
-	case ir.ORUNES2STR, ir.OBYTES2STR, ir.OSTR2RUNES, ir.OSTR2BYTES, ir.ORUNESTR:
-		n := n.(*ir.ConvExpr)
-		e.spill(k, n)
-		e.discard(n.X)
-
-	case ir.OADDSTR:
-		n := n.(*ir.AddStringExpr)
-		e.spill(k, n)
-
-		// Arguments of OADDSTR never escape;
-		// runtime.concatstrings makes sure of that.
-		e.discards(n.List)
 	}
 }
 
-// unsafeValue evaluates a uintptr-typed arithmetic expression looking
-// for conversions from an unsafe.Pointer.
-func (e *escape) unsafeValue(k hole, n ir.Node) {
-	if n.Type().Kind() != types.TUINTPTR {
-		base.Fatalf("unexpected type %v for %v", n.Type(), n)
-	}
-	if k.addrtaken {
-		base.Fatalf("unexpected addrtaken")
-	}
-
-	e.stmts(n.Init())
-
-	switch n.Op() {
-	case ir.OCONV, ir.OCONVNOP:
-		n := n.(*ir.ConvExpr)
-		if n.X.Type().IsUnsafePtr() {
-			e.expr(k, n.X)
-		} else {
-			e.discard(n.X)
-		}
-	case ir.ODOTPTR:
-		n := n.(*ir.SelectorExpr)
-		if ir.IsReflectHeaderDataField(n) {
-			e.expr(k.deref(n, "reflect.Header.Data"), n.X)
-		} else {
-			e.discard(n.X)
+// inMutualBatch reports whether function fn is in the batch of
+// mutually recursive functions being analyzed. When this is true,
+// fn has not yet been analyzed, so its parameters and results
+// should be incorporated directly into the flow graph instead of
+// relying on its escape analysis tagging.
+func (e *escape) inMutualBatch(fn *ir.Name) bool {
+	if fn.Defn != nil && fn.Defn.Esc() < escFuncTagged {
+		if fn.Defn.Esc() == escFuncUnknown {
+			base.Fatalf("graph inconsistency: %v", fn)
 		}
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT:
-		n := n.(*ir.UnaryExpr)
-		e.unsafeValue(k, n.X)
-	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OAND, ir.OANDNOT:
-		n := n.(*ir.BinaryExpr)
-		e.unsafeValue(k, n.X)
-		e.unsafeValue(k, n.Y)
-	case ir.OLSH, ir.ORSH:
-		n := n.(*ir.BinaryExpr)
-		e.unsafeValue(k, n.X)
-		// RHS need not be uintptr-typed (#32959) and can't meaningfully
-		// flow pointers anyway.
-		e.discard(n.Y)
-	default:
-		e.exprSkipInit(e.discardHole(), n)
+		return true
 	}
+	return false
 }
 
-// discard evaluates an expression n for side-effects, but discards
-// its value.
-func (e *escape) discard(n ir.Node) {
-	e.expr(e.discardHole(), n)
-}
-
-func (e *escape) discards(l ir.Nodes) {
-	for _, n := range l {
-		e.discard(n)
-	}
-}
+const (
+	escFuncUnknown = 0 + iota
+	escFuncPlanned
+	escFuncStarted
+	escFuncTagged
+)
 
-// addr evaluates an addressable expression n and returns a hole
-// that represents storing into the represented location.
-func (e *escape) addr(n ir.Node) hole {
-	if n == nil || ir.IsBlank(n) {
-		// Can happen in select case, range, maybe others.
-		return e.discardHole()
-	}
+// Mark labels that have no backjumps to them as not increasing e.loopdepth.
+type labelState int
 
-	k := e.heapHole()
+const (
+	looping labelState = 1 + iota
+	nonlooping
+)
 
-	switch n.Op() {
-	default:
-		base.Fatalf("unexpected addr: %v", n)
-	case ir.ONAME:
-		n := n.(*ir.Name)
-		if n.Class == ir.PEXTERN {
-			break
-		}
-		k = e.oldLoc(n).asHole()
-	case ir.OLINKSYMOFFSET:
-		break
-	case ir.ODOT:
-		n := n.(*ir.SelectorExpr)
-		k = e.addr(n.X)
-	case ir.OINDEX:
-		n := n.(*ir.IndexExpr)
-		e.discard(n.Index)
-		if n.X.Type().IsArray() {
-			k = e.addr(n.X)
-		} else {
-			e.discard(n.X)
+func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
+	name := func() string {
+		if f.Sym != nil {
+			return f.Sym.Name
 		}
-	case ir.ODEREF, ir.ODOTPTR:
-		e.discard(n)
-	case ir.OINDEXMAP:
-		n := n.(*ir.IndexExpr)
-		e.discard(n.X)
-		e.assignHeap(n.Index, "key of map put", n)
+		return fmt.Sprintf("arg#%d", narg)
 	}
 
-	return k
-}
+	// Only report diagnostics for user code;
+	// not for wrappers generated around them.
+	// TODO(mdempsky): Generalize this.
+	diagnose := base.Flag.LowerM != 0 && !(fn.Wrapper() || fn.Dupok())
 
-func (e *escape) addrs(l ir.Nodes) []hole {
-	var ks []hole
-	for _, n := range l {
-		ks = append(ks, e.addr(n))
-	}
-	return ks
-}
+	if len(fn.Body) == 0 {
+		// Assume that uintptr arguments must be held live across the call.
+		// This is most important for syscall.Syscall.
+		// See golang.org/issue/13372.
+		// This really doesn't have much to do with escape analysis per se,
+		// but we are reusing the ability to annotate an individual function
+		// argument and pass those annotations along to importing code.
+		fn.Pragma |= ir.UintptrKeepAlive
 
-// reassigned marks the locations associated with the given holes as
-// reassigned, unless the location represents a variable declared and
-// assigned exactly once by where.
-func (e *escape) reassigned(ks []hole, where ir.Node) {
-	if as, ok := where.(*ir.AssignStmt); ok && as.Op() == ir.OAS && as.Y == nil {
-		if dst, ok := as.X.(*ir.Name); ok && dst.Op() == ir.ONAME && dst.Defn == nil {
-			// Zero-value assignment for variable declared without an
-			// explicit initial value. Assume this is its initialization
-			// statement.
-			return
+		if f.Type.IsUintptr() {
+			if diagnose {
+				base.WarnfAt(f.Pos, "assuming %v is unsafe uintptr", name())
+			}
+			return ""
 		}
-	}
 
-	for _, k := range ks {
-		loc := k.dst
-		// Variables declared by range statements are assigned on every iteration.
-		if n, ok := loc.n.(*ir.Name); ok && n.Defn == where && where.Op() != ir.ORANGE {
-			continue
+		if !f.Type.HasPointers() { // don't bother tagging for scalars
+			return ""
 		}
-		loc.reassigned = true
-	}
-}
 
-// assignList evaluates the assignment dsts... = srcs....
-func (e *escape) assignList(dsts, srcs []ir.Node, why string, where ir.Node) {
-	ks := e.addrs(dsts)
-	for i, k := range ks {
-		var src ir.Node
-		if i < len(srcs) {
-			src = srcs[i]
-		}
+		var esc leaks
 
-		if dst := dsts[i]; dst != nil {
-			// Detect implicit conversion of uintptr to unsafe.Pointer when
-			// storing into reflect.{Slice,String}Header.
-			if dst.Op() == ir.ODOTPTR && ir.IsReflectHeaderDataField(dst) {
-				e.unsafeValue(e.heapHole().note(where, why), src)
-				continue
+		// External functions are assumed unsafe, unless
+		// //go:noescape is given before the declaration.
+		if fn.Pragma&ir.Noescape != 0 {
+			if diagnose && f.Sym != nil {
+				base.WarnfAt(f.Pos, "%v does not escape", name())
 			}
-
-			// Filter out some no-op assignments for escape analysis.
-			if src != nil && isSelfAssign(dst, src) {
-				if base.Flag.LowerM != 0 {
-					base.WarnfAt(where.Pos(), "%v ignoring self-assignment in %v", e.curfn, where)
-				}
-				k = e.discardHole()
+		} else {
+			if diagnose && f.Sym != nil {
+				base.WarnfAt(f.Pos, "leaking param: %v", name())
 			}
+			esc.AddHeap(0)
 		}
 
-		e.expr(k.note(where, why), src)
-	}
-
-	e.reassigned(ks, where)
-}
-
-func (e *escape) assignHeap(src ir.Node, why string, where ir.Node) {
-	e.expr(e.heapHole().note(where, why), src)
-}
-
-// call evaluates a call expressions, including builtin calls. ks
-// should contain the holes representing where the function callee's
-// results flows; where is the OGO/ODEFER context of the call, if any.
-func (e *escape) call(ks []hole, call, where ir.Node) {
-	topLevelDefer := where != nil && where.Op() == ir.ODEFER && e.loopDepth == 1
-	if topLevelDefer {
-		// force stack allocation of defer record, unless
-		// open-coded defers are used (see ssa.go)
-		where.SetEsc(ir.EscNever)
-	}
-
-	argument := func(k hole, arg ir.Node) {
-		if topLevelDefer {
-			// Top level defers arguments don't escape to
-			// heap, but they do need to last until end of
-			// function.
-			k = e.later(k)
-		} else if where != nil {
-			k = e.heapHole()
-		}
-
-		e.expr(k.note(call, "call parameter"), arg)
+		return esc.Encode()
 	}
 
-	switch call.Op() {
-	default:
-		ir.Dump("esc", call)
-		base.Fatalf("unexpected call op: %v", call.Op())
-
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
-		call := call.(*ir.CallExpr)
-		typecheck.FixVariadicCall(call)
+	if fn.Pragma&ir.UintptrEscapes != 0 {
+		fn.Pragma |= ir.UintptrKeepAlive
 
-		// Pick out the function callee, if statically known.
-		var fn *ir.Name
-		switch call.Op() {
-		case ir.OCALLFUNC:
-			switch v := ir.StaticValue(call.X); {
-			case v.Op() == ir.ONAME && v.(*ir.Name).Class == ir.PFUNC:
-				fn = v.(*ir.Name)
-			case v.Op() == ir.OCLOSURE:
-				fn = v.(*ir.ClosureExpr).Func.Nname
+		if f.Type.IsUintptr() {
+			if diagnose {
+				base.WarnfAt(f.Pos, "marking %v as escaping uintptr", name())
 			}
-		case ir.OCALLMETH:
-			fn = ir.MethodExprName(call.X)
-		}
-
-		fntype := call.X.Type()
-		if fn != nil {
-			fntype = fn.Type()
-		}
-
-		if ks != nil && fn != nil && e.inMutualBatch(fn) {
-			for i, result := range fn.Type().Results().FieldSlice() {
-				e.expr(ks[i], ir.AsNode(result.Nname))
-			}
-		}
-
-		if r := fntype.Recv(); r != nil {
-			argument(e.tagHole(ks, fn, r), call.X.(*ir.SelectorExpr).X)
-		} else {
-			// Evaluate callee function expression.
-			argument(e.discardHole(), call.X)
-		}
-
-		args := call.Args
-		for i, param := range fntype.Params().FieldSlice() {
-			argument(e.tagHole(ks, fn, param), args[i])
-		}
-
-	case ir.OAPPEND:
-		call := call.(*ir.CallExpr)
-		args := call.Args
-
-		// Appendee slice may flow directly to the result, if
-		// it has enough capacity. Alternatively, a new heap
-		// slice might be allocated, and all slice elements
-		// might flow to heap.
-		appendeeK := ks[0]
-		if args[0].Type().Elem().HasPointers() {
-			appendeeK = e.teeHole(appendeeK, e.heapHole().deref(call, "appendee slice"))
-		}
-		argument(appendeeK, args[0])
-
-		if call.IsDDD {
-			appendedK := e.discardHole()
-			if args[1].Type().IsSlice() && args[1].Type().Elem().HasPointers() {
-				appendedK = e.heapHole().deref(call, "appended slice...")
-			}
-			argument(appendedK, args[1])
-		} else {
-			for _, arg := range args[1:] {
-				argument(e.heapHole(), arg)
-			}
-		}
-
-	case ir.OCOPY:
-		call := call.(*ir.BinaryExpr)
-		argument(e.discardHole(), call.X)
-
-		copiedK := e.discardHole()
-		if call.Y.Type().IsSlice() && call.Y.Type().Elem().HasPointers() {
-			copiedK = e.heapHole().deref(call, "copied slice")
-		}
-		argument(copiedK, call.Y)
-
-	case ir.OPANIC:
-		call := call.(*ir.UnaryExpr)
-		argument(e.heapHole(), call.X)
-
-	case ir.OCOMPLEX:
-		call := call.(*ir.BinaryExpr)
-		argument(e.discardHole(), call.X)
-		argument(e.discardHole(), call.Y)
-	case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
-		call := call.(*ir.CallExpr)
-		for _, arg := range call.Args {
-			argument(e.discardHole(), arg)
-		}
-	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE:
-		call := call.(*ir.UnaryExpr)
-		argument(e.discardHole(), call.X)
-
-	case ir.OUNSAFEADD, ir.OUNSAFESLICE:
-		call := call.(*ir.BinaryExpr)
-		argument(ks[0], call.X)
-		argument(e.discardHole(), call.Y)
-	}
-}
-
-// tagHole returns a hole for evaluating an argument passed to param.
-// ks should contain the holes representing where the function
-// callee's results flows. fn is the statically-known callee function,
-// if any.
-func (e *escape) tagHole(ks []hole, fn *ir.Name, param *types.Field) hole {
-	// If this is a dynamic call, we can't rely on param.Note.
-	if fn == nil {
-		return e.heapHole()
-	}
-
-	if e.inMutualBatch(fn) {
-		return e.addr(ir.AsNode(param.Nname))
-	}
-
-	// Call to previously tagged function.
-
-	if param.Note == UintptrEscapesNote {
-		k := e.heapHole()
-		k.uintptrEscapesHack = true
-		return k
-	}
-
-	var tagKs []hole
-
-	esc := parseLeaks(param.Note)
-	if x := esc.Heap(); x >= 0 {
-		tagKs = append(tagKs, e.heapHole().shift(x))
-	}
-
-	if ks != nil {
-		for i := 0; i < numEscResults; i++ {
-			if x := esc.Result(i); x >= 0 {
-				tagKs = append(tagKs, ks[i].shift(x))
-			}
-		}
-	}
-
-	return e.teeHole(tagKs...)
-}
-
-// inMutualBatch reports whether function fn is in the batch of
-// mutually recursive functions being analyzed. When this is true,
-// fn has not yet been analyzed, so its parameters and results
-// should be incorporated directly into the flow graph instead of
-// relying on its escape analysis tagging.
-func (e *escape) inMutualBatch(fn *ir.Name) bool {
-	if fn.Defn != nil && fn.Defn.Esc() < escFuncTagged {
-		if fn.Defn.Esc() == escFuncUnknown {
-			base.Fatalf("graph inconsistency: %v", fn)
-		}
-		return true
-	}
-	return false
-}
-
-// An hole represents a context for evaluation a Go
-// expression. E.g., when evaluating p in "x = **p", we'd have a hole
-// with dst==x and derefs==2.
-type hole struct {
-	dst    *location
-	derefs int // >= -1
-	notes  *note
-
-	// addrtaken indicates whether this context is taking the address of
-	// the expression, independent of whether the address will actually
-	// be stored into a variable.
-	addrtaken bool
-
-	// uintptrEscapesHack indicates this context is evaluating an
-	// argument for a //go:uintptrescapes function.
-	uintptrEscapesHack bool
-}
-
-type note struct {
-	next  *note
-	where ir.Node
-	why   string
-}
-
-func (k hole) note(where ir.Node, why string) hole {
-	if where == nil || why == "" {
-		base.Fatalf("note: missing where/why")
-	}
-	if base.Flag.LowerM >= 2 || logopt.Enabled() {
-		k.notes = ¬e{
-			next:  k.notes,
-			where: where,
-			why:   why,
-		}
-	}
-	return k
-}
-
-func (k hole) shift(delta int) hole {
-	k.derefs += delta
-	if k.derefs < -1 {
-		base.Fatalf("derefs underflow: %v", k.derefs)
-	}
-	k.addrtaken = delta < 0
-	return k
-}
-
-func (k hole) deref(where ir.Node, why string) hole { return k.shift(1).note(where, why) }
-func (k hole) addr(where ir.Node, why string) hole  { return k.shift(-1).note(where, why) }
-
-func (k hole) dotType(t *types.Type, where ir.Node, why string) hole {
-	if !t.IsInterface() && !types.IsDirectIface(t) {
-		k = k.shift(1)
-	}
-	return k.note(where, why)
-}
-
-// teeHole returns a new hole that flows into each hole of ks,
-// similar to the Unix tee(1) command.
-func (e *escape) teeHole(ks ...hole) hole {
-	if len(ks) == 0 {
-		return e.discardHole()
-	}
-	if len(ks) == 1 {
-		return ks[0]
-	}
-	// TODO(mdempsky): Optimize if there's only one non-discard hole?
-
-	// Given holes "l1 = _", "l2 = **_", "l3 = *_", ..., create a
-	// new temporary location ltmp, wire it into place, and return
-	// a hole for "ltmp = _".
-	loc := e.newLoc(nil, true)
-	for _, k := range ks {
-		// N.B., "p = &q" and "p = &tmp; tmp = q" are not
-		// semantically equivalent. To combine holes like "l1
-		// = _" and "l2 = &_", we'd need to wire them as "l1 =
-		// *ltmp" and "l2 = ltmp" and return "ltmp = &_"
-		// instead.
-		if k.derefs < 0 {
-			base.Fatalf("teeHole: negative derefs")
-		}
-
-		e.flow(k, loc)
-	}
-	return loc.asHole()
-}
-
-func (e *escape) dcl(n *ir.Name) hole {
-	if n.Curfn != e.curfn || n.IsClosureVar() {
-		base.Fatalf("bad declaration of %v", n)
-	}
-	loc := e.oldLoc(n)
-	loc.loopDepth = e.loopDepth
-	return loc.asHole()
-}
-
-// spill allocates a new location associated with expression n, flows
-// its address to k, and returns a hole that flows values to it. It's
-// intended for use with most expressions that allocate storage.
-func (e *escape) spill(k hole, n ir.Node) hole {
-	loc := e.newLoc(n, true)
-	e.flow(k.addr(n, "spill"), loc)
-	return loc.asHole()
-}
-
-// later returns a new hole that flows into k, but some time later.
-// Its main effect is to prevent immediate reuse of temporary
-// variables introduced during Order.
-func (e *escape) later(k hole) hole {
-	loc := e.newLoc(nil, false)
-	e.flow(k, loc)
-	return loc.asHole()
-}
-
-func (e *escape) newLoc(n ir.Node, transient bool) *location {
-	if e.curfn == nil {
-		base.Fatalf("e.curfn isn't set")
-	}
-	if n != nil && n.Type() != nil && n.Type().NotInHeap() {
-		base.ErrorfAt(n.Pos(), "%v is incomplete (or unallocatable); stack allocation disallowed", n.Type())
-	}
-
-	if n != nil && n.Op() == ir.ONAME {
-		n = n.(*ir.Name).Canonical()
-	}
-	loc := &location{
-		n:         n,
-		curfn:     e.curfn,
-		loopDepth: e.loopDepth,
-		transient: transient,
-	}
-	e.allLocs = append(e.allLocs, loc)
-	if n != nil {
-		if n.Op() == ir.ONAME {
-			n := n.(*ir.Name)
-			if n.Curfn != e.curfn {
-				base.Fatalf("curfn mismatch: %v != %v for %v", n.Curfn, e.curfn, n)
-			}
-
-			if n.Opt != nil {
-				base.Fatalf("%v already has a location", n)
-			}
-			n.Opt = loc
-		}
-	}
-	return loc
-}
-
-func (b *batch) oldLoc(n *ir.Name) *location {
-	if n.Canonical().Opt == nil {
-		base.Fatalf("%v has no location", n)
-	}
-	return n.Canonical().Opt.(*location)
-}
-
-func (l *location) asHole() hole {
-	return hole{dst: l}
-}
-
-func (b *batch) flow(k hole, src *location) {
-	if k.addrtaken {
-		src.addrtaken = true
-	}
-
-	dst := k.dst
-	if dst == &b.blankLoc {
-		return
-	}
-	if dst == src && k.derefs >= 0 { // dst = dst, dst = *dst, ...
-		return
-	}
-	if dst.escapes && k.derefs < 0 { // dst = &src
-		if base.Flag.LowerM >= 2 || logopt.Enabled() {
-			pos := base.FmtPos(src.n.Pos())
-			if base.Flag.LowerM >= 2 {
-				fmt.Printf("%s: %v escapes to heap:\n", pos, src.n)
-			}
-			explanation := b.explainFlow(pos, dst, src, k.derefs, k.notes, []*logopt.LoggedOpt{})
-			if logopt.Enabled() {
-				var e_curfn *ir.Func // TODO(mdempsky): Fix.
-				logopt.LogOpt(src.n.Pos(), "escapes", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", src.n), explanation)
-			}
-
-		}
-		src.escapes = true
-		return
-	}
-
-	// TODO(mdempsky): Deduplicate edges?
-	dst.edges = append(dst.edges, edge{src: src, derefs: k.derefs, notes: k.notes})
-}
-
-func (b *batch) heapHole() hole    { return b.heapLoc.asHole() }
-func (b *batch) discardHole() hole { return b.blankLoc.asHole() }
-
-// walkAll computes the minimal dereferences between all pairs of
-// locations.
-func (b *batch) walkAll() {
-	// We use a work queue to keep track of locations that we need
-	// to visit, and repeatedly walk until we reach a fixed point.
-	//
-	// We walk once from each location (including the heap), and
-	// then re-enqueue each location on its transition from
-	// transient->!transient and !escapes->escapes, which can each
-	// happen at most once. So we take Θ(len(e.allLocs)) walks.
-
-	// LIFO queue, has enough room for e.allLocs and e.heapLoc.
-	todo := make([]*location, 0, len(b.allLocs)+1)
-	enqueue := func(loc *location) {
-		if !loc.queued {
-			todo = append(todo, loc)
-			loc.queued = true
-		}
-	}
-
-	for _, loc := range b.allLocs {
-		enqueue(loc)
-	}
-	enqueue(&b.heapLoc)
-
-	var walkgen uint32
-	for len(todo) > 0 {
-		root := todo[len(todo)-1]
-		todo = todo[:len(todo)-1]
-		root.queued = false
-
-		walkgen++
-		b.walkOne(root, walkgen, enqueue)
-	}
-}
-
-// walkOne computes the minimal number of dereferences from root to
-// all other locations.
-func (b *batch) walkOne(root *location, walkgen uint32, enqueue func(*location)) {
-	// The data flow graph has negative edges (from addressing
-	// operations), so we use the Bellman-Ford algorithm. However,
-	// we don't have to worry about infinite negative cycles since
-	// we bound intermediate dereference counts to 0.
-
-	root.walkgen = walkgen
-	root.derefs = 0
-	root.dst = nil
-
-	todo := []*location{root} // LIFO queue
-	for len(todo) > 0 {
-		l := todo[len(todo)-1]
-		todo = todo[:len(todo)-1]
-
-		derefs := l.derefs
-
-		// If l.derefs < 0, then l's address flows to root.
-		addressOf := derefs < 0
-		if addressOf {
-			// For a flow path like "root = &l; l = x",
-			// l's address flows to root, but x's does
-			// not. We recognize this by lower bounding
-			// derefs at 0.
-			derefs = 0
-
-			// If l's address flows to a non-transient
-			// location, then l can't be transiently
-			// allocated.
-			if !root.transient && l.transient {
-				l.transient = false
-				enqueue(l)
-			}
-		}
-
-		if b.outlives(root, l) {
-			// l's value flows to root. If l is a function
-			// parameter and root is the heap or a
-			// corresponding result parameter, then record
-			// that value flow for tagging the function
-			// later.
-			if l.isName(ir.PPARAM) {
-				if (logopt.Enabled() || base.Flag.LowerM >= 2) && !l.escapes {
-					if base.Flag.LowerM >= 2 {
-						fmt.Printf("%s: parameter %v leaks to %s with derefs=%d:\n", base.FmtPos(l.n.Pos()), l.n, b.explainLoc(root), derefs)
-					}
-					explanation := b.explainPath(root, l)
-					if logopt.Enabled() {
-						var e_curfn *ir.Func // TODO(mdempsky): Fix.
-						logopt.LogOpt(l.n.Pos(), "leak", "escape", ir.FuncName(e_curfn),
-							fmt.Sprintf("parameter %v leaks to %s with derefs=%d", l.n, b.explainLoc(root), derefs), explanation)
-					}
-				}
-				l.leakTo(root, derefs)
-			}
-
-			// If l's address flows somewhere that
-			// outlives it, then l needs to be heap
-			// allocated.
-			if addressOf && !l.escapes {
-				if logopt.Enabled() || base.Flag.LowerM >= 2 {
-					if base.Flag.LowerM >= 2 {
-						fmt.Printf("%s: %v escapes to heap:\n", base.FmtPos(l.n.Pos()), l.n)
-					}
-					explanation := b.explainPath(root, l)
-					if logopt.Enabled() {
-						var e_curfn *ir.Func // TODO(mdempsky): Fix.
-						logopt.LogOpt(l.n.Pos(), "escape", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", l.n), explanation)
-					}
-				}
-				l.escapes = true
-				enqueue(l)
-				continue
-			}
-		}
-
-		for i, edge := range l.edges {
-			if edge.src.escapes {
-				continue
-			}
-			d := derefs + edge.derefs
-			if edge.src.walkgen != walkgen || edge.src.derefs > d {
-				edge.src.walkgen = walkgen
-				edge.src.derefs = d
-				edge.src.dst = l
-				edge.src.dstEdgeIdx = i
-				todo = append(todo, edge.src)
-			}
-		}
-	}
-}
-
-// explainPath prints an explanation of how src flows to the walk root.
-func (b *batch) explainPath(root, src *location) []*logopt.LoggedOpt {
-	visited := make(map[*location]bool)
-	pos := base.FmtPos(src.n.Pos())
-	var explanation []*logopt.LoggedOpt
-	for {
-		// Prevent infinite loop.
-		if visited[src] {
-			if base.Flag.LowerM >= 2 {
-				fmt.Printf("%s:   warning: truncated explanation due to assignment cycle; see golang.org/issue/35518\n", pos)
-			}
-			break
-		}
-		visited[src] = true
-		dst := src.dst
-		edge := &dst.edges[src.dstEdgeIdx]
-		if edge.src != src {
-			base.Fatalf("path inconsistency: %v != %v", edge.src, src)
-		}
-
-		explanation = b.explainFlow(pos, dst, src, edge.derefs, edge.notes, explanation)
-
-		if dst == root {
-			break
-		}
-		src = dst
-	}
-
-	return explanation
-}
-
-func (b *batch) explainFlow(pos string, dst, srcloc *location, derefs int, notes *note, explanation []*logopt.LoggedOpt) []*logopt.LoggedOpt {
-	ops := "&"
-	if derefs >= 0 {
-		ops = strings.Repeat("*", derefs)
-	}
-	print := base.Flag.LowerM >= 2
-
-	flow := fmt.Sprintf("   flow: %s = %s%v:", b.explainLoc(dst), ops, b.explainLoc(srcloc))
-	if print {
-		fmt.Printf("%s:%s\n", pos, flow)
-	}
-	if logopt.Enabled() {
-		var epos src.XPos
-		if notes != nil {
-			epos = notes.where.Pos()
-		} else if srcloc != nil && srcloc.n != nil {
-			epos = srcloc.n.Pos()
-		}
-		var e_curfn *ir.Func // TODO(mdempsky): Fix.
-		explanation = append(explanation, logopt.NewLoggedOpt(epos, "escflow", "escape", ir.FuncName(e_curfn), flow))
-	}
-
-	for note := notes; note != nil; note = note.next {
-		if print {
-			fmt.Printf("%s:     from %v (%v) at %s\n", pos, note.where, note.why, base.FmtPos(note.where.Pos()))
-		}
-		if logopt.Enabled() {
-			var e_curfn *ir.Func // TODO(mdempsky): Fix.
-			explanation = append(explanation, logopt.NewLoggedOpt(note.where.Pos(), "escflow", "escape", ir.FuncName(e_curfn),
-				fmt.Sprintf("     from %v (%v)", note.where, note.why)))
-		}
-	}
-	return explanation
-}
-
-func (b *batch) explainLoc(l *location) string {
-	if l == &b.heapLoc {
-		return "{heap}"
-	}
-	if l.n == nil {
-		// TODO(mdempsky): Omit entirely.
-		return "{temp}"
-	}
-	if l.n.Op() == ir.ONAME {
-		return fmt.Sprintf("%v", l.n)
-	}
-	return fmt.Sprintf("{storage for %v}", l.n)
-}
-
-// outlives reports whether values stored in l may survive beyond
-// other's lifetime if stack allocated.
-func (b *batch) outlives(l, other *location) bool {
-	// The heap outlives everything.
-	if l.escapes {
-		return true
-	}
-
-	// We don't know what callers do with returned values, so
-	// pessimistically we need to assume they flow to the heap and
-	// outlive everything too.
-	if l.isName(ir.PPARAMOUT) {
-		// Exception: Directly called closures can return
-		// locations allocated outside of them without forcing
-		// them to the heap. For example:
-		//
-		//    var u int  // okay to stack allocate
-		//    *(func() *int { return &u }()) = 42
-		if containsClosure(other.curfn, l.curfn) && l.curfn.ClosureCalled() {
-			return false
-		}
-
-		return true
-	}
-
-	// If l and other are within the same function, then l
-	// outlives other if it was declared outside other's loop
-	// scope. For example:
-	//
-	//    var l *int
-	//    for {
-	//        l = new(int)
-	//    }
-	if l.curfn == other.curfn && l.loopDepth < other.loopDepth {
-		return true
-	}
-
-	// If other is declared within a child closure of where l is
-	// declared, then l outlives it. For example:
-	//
-	//    var l *int
-	//    func() {
-	//        l = new(int)
-	//    }
-	if containsClosure(l.curfn, other.curfn) {
-		return true
-	}
-
-	return false
-}
-
-// containsClosure reports whether c is a closure contained within f.
-func containsClosure(f, c *ir.Func) bool {
-	// Common case.
-	if f == c {
-		return false
-	}
-
-	// Closures within function Foo are named like "Foo.funcN..."
-	// TODO(mdempsky): Better way to recognize this.
-	fn := f.Sym().Name
-	cn := c.Sym().Name
-	return len(cn) > len(fn) && cn[:len(fn)] == fn && cn[len(fn)] == '.'
-}
-
-// leak records that parameter l leaks to sink.
-func (l *location) leakTo(sink *location, derefs int) {
-	// If sink is a result parameter that doesn't escape (#44614)
-	// and we can fit return bits into the escape analysis tag,
-	// then record as a result leak.
-	if !sink.escapes && sink.isName(ir.PPARAMOUT) && sink.curfn == l.curfn {
-		ri := sink.resultIndex - 1
-		if ri < numEscResults {
-			// Leak to result parameter.
-			l.paramEsc.AddResult(ri, derefs)
-			return
-		}
-	}
-
-	// Otherwise, record as heap leak.
-	l.paramEsc.AddHeap(derefs)
-}
-
-func (b *batch) finish(fns []*ir.Func) {
-	// Record parameter tags for package export data.
-	for _, fn := range fns {
-		fn.SetEsc(escFuncTagged)
-
-		narg := 0
-		for _, fs := range &types.RecvsParams {
-			for _, f := range fs(fn.Type()).Fields().Slice() {
-				narg++
-				f.Note = b.paramTag(fn, narg, f)
-			}
-		}
-	}
-
-	for _, loc := range b.allLocs {
-		n := loc.n
-		if n == nil {
-			continue
-		}
-		if n.Op() == ir.ONAME {
-			n := n.(*ir.Name)
-			n.Opt = nil
-		}
-
-		// Update n.Esc based on escape analysis results.
-
-		if loc.escapes {
-			if n.Op() == ir.ONAME {
-				if base.Flag.CompilingRuntime {
-					base.ErrorfAt(n.Pos(), "%v escapes to heap, not allowed in runtime", n)
-				}
-				if base.Flag.LowerM != 0 {
-					base.WarnfAt(n.Pos(), "moved to heap: %v", n)
-				}
-			} else {
-				if base.Flag.LowerM != 0 {
-					base.WarnfAt(n.Pos(), "%v escapes to heap", n)
-				}
-				if logopt.Enabled() {
-					var e_curfn *ir.Func // TODO(mdempsky): Fix.
-					logopt.LogOpt(n.Pos(), "escape", "escape", ir.FuncName(e_curfn))
-				}
-			}
-			n.SetEsc(ir.EscHeap)
-		} else {
-			if base.Flag.LowerM != 0 && n.Op() != ir.ONAME {
-				base.WarnfAt(n.Pos(), "%v does not escape", n)
-			}
-			n.SetEsc(ir.EscNone)
-			if loc.transient {
-				switch n.Op() {
-				case ir.OCLOSURE:
-					n := n.(*ir.ClosureExpr)
-					n.SetTransient(true)
-				case ir.OCALLPART:
-					n := n.(*ir.SelectorExpr)
-					n.SetTransient(true)
-				case ir.OSLICELIT:
-					n := n.(*ir.CompLitExpr)
-					n.SetTransient(true)
-				}
-			}
-		}
-	}
-}
-
-func (l *location) isName(c ir.Class) bool {
-	return l.n != nil && l.n.Op() == ir.ONAME && l.n.(*ir.Name).Class == c
-}
-
-const numEscResults = 7
-
-// An leaks represents a set of assignment flows from a parameter
-// to the heap or to any of its function's (first numEscResults)
-// result parameters.
-type leaks [1 + numEscResults]uint8
-
-// Empty reports whether l is an empty set (i.e., no assignment flows).
-func (l leaks) Empty() bool { return l == leaks{} }
-
-// Heap returns the minimum deref count of any assignment flow from l
-// to the heap. If no such flows exist, Heap returns -1.
-func (l leaks) Heap() int { return l.get(0) }
-
-// Result returns the minimum deref count of any assignment flow from
-// l to its function's i'th result parameter. If no such flows exist,
-// Result returns -1.
-func (l leaks) Result(i int) int { return l.get(1 + i) }
-
-// AddHeap adds an assignment flow from l to the heap.
-func (l *leaks) AddHeap(derefs int) { l.add(0, derefs) }
-
-// AddResult adds an assignment flow from l to its function's i'th
-// result parameter.
-func (l *leaks) AddResult(i, derefs int) { l.add(1+i, derefs) }
-
-func (l *leaks) setResult(i, derefs int) { l.set(1+i, derefs) }
-
-func (l leaks) get(i int) int { return int(l[i]) - 1 }
-
-func (l *leaks) add(i, derefs int) {
-	if old := l.get(i); old < 0 || derefs < old {
-		l.set(i, derefs)
-	}
-}
-
-func (l *leaks) set(i, derefs int) {
-	v := derefs + 1
-	if v < 0 {
-		base.Fatalf("invalid derefs count: %v", derefs)
-	}
-	if v > math.MaxUint8 {
-		v = math.MaxUint8
-	}
-
-	l[i] = uint8(v)
-}
-
-// Optimize removes result flow paths that are equal in length or
-// longer than the shortest heap flow path.
-func (l *leaks) Optimize() {
-	// If we have a path to the heap, then there's no use in
-	// keeping equal or longer paths elsewhere.
-	if x := l.Heap(); x >= 0 {
-		for i := 0; i < numEscResults; i++ {
-			if l.Result(i) >= x {
-				l.setResult(i, -1)
-			}
-		}
-	}
-}
-
-var leakTagCache = map[leaks]string{}
-
-// Encode converts l into a binary string for export data.
-func (l leaks) Encode() string {
-	if l.Heap() == 0 {
-		// Space optimization: empty string encodes more
-		// efficiently in export data.
-		return ""
-	}
-	if s, ok := leakTagCache[l]; ok {
-		return s
-	}
-
-	n := len(l)
-	for n > 0 && l[n-1] == 0 {
-		n--
-	}
-	s := "esc:" + string(l[:n])
-	leakTagCache[l] = s
-	return s
-}
-
-// parseLeaks parses a binary string representing a leaks
-func parseLeaks(s string) leaks {
-	var l leaks
-	if !strings.HasPrefix(s, "esc:") {
-		l.AddHeap(0)
-		return l
-	}
-	copy(l[:], s[4:])
-	return l
-}
-
-func Funcs(all []ir.Node) {
-	ir.VisitFuncsBottomUp(all, Batch)
-}
-
-const (
-	escFuncUnknown = 0 + iota
-	escFuncPlanned
-	escFuncStarted
-	escFuncTagged
-)
-
-// Mark labels that have no backjumps to them as not increasing e.loopdepth.
-type labelState int
-
-const (
-	looping labelState = 1 + iota
-	nonlooping
-)
-
-func isSliceSelfAssign(dst, src ir.Node) bool {
-	// Detect the following special case.
-	//
-	//	func (b *Buffer) Foo() {
-	//		n, m := ...
-	//		b.buf = b.buf[n:m]
-	//	}
-	//
-	// This assignment is a no-op for escape analysis,
-	// it does not store any new pointers into b that were not already there.
-	// However, without this special case b will escape, because we assign to OIND/ODOTPTR.
-	// Here we assume that the statement will not contain calls,
-	// that is, that order will move any calls to init.
-	// Otherwise base ONAME value could change between the moments
-	// when we evaluate it for dst and for src.
-
-	// dst is ONAME dereference.
-	var dstX ir.Node
-	switch dst.Op() {
-	default:
-		return false
-	case ir.ODEREF:
-		dst := dst.(*ir.StarExpr)
-		dstX = dst.X
-	case ir.ODOTPTR:
-		dst := dst.(*ir.SelectorExpr)
-		dstX = dst.X
-	}
-	if dstX.Op() != ir.ONAME {
-		return false
-	}
-	// src is a slice operation.
-	switch src.Op() {
-	case ir.OSLICE, ir.OSLICE3, ir.OSLICESTR:
-		// OK.
-	case ir.OSLICEARR, ir.OSLICE3ARR:
-		// Since arrays are embedded into containing object,
-		// slice of non-pointer array will introduce a new pointer into b that was not already there
-		// (pointer to b itself). After such assignment, if b contents escape,
-		// b escapes as well. If we ignore such OSLICEARR, we will conclude
-		// that b does not escape when b contents do.
-		//
-		// Pointer to an array is OK since it's not stored inside b directly.
-		// For slicing an array (not pointer to array), there is an implicit OADDR.
-		// We check that to determine non-pointer array slicing.
-		src := src.(*ir.SliceExpr)
-		if src.X.Op() == ir.OADDR {
-			return false
-		}
-	default:
-		return false
-	}
-	// slice is applied to ONAME dereference.
-	var baseX ir.Node
-	switch base := src.(*ir.SliceExpr).X; base.Op() {
-	default:
-		return false
-	case ir.ODEREF:
-		base := base.(*ir.StarExpr)
-		baseX = base.X
-	case ir.ODOTPTR:
-		base := base.(*ir.SelectorExpr)
-		baseX = base.X
-	}
-	if baseX.Op() != ir.ONAME {
-		return false
-	}
-	// dst and src reference the same base ONAME.
-	return dstX.(*ir.Name) == baseX.(*ir.Name)
-}
-
-// isSelfAssign reports whether assignment from src to dst can
-// be ignored by the escape analysis as it's effectively a self-assignment.
-func isSelfAssign(dst, src ir.Node) bool {
-	if isSliceSelfAssign(dst, src) {
-		return true
-	}
-
-	// Detect trivial assignments that assign back to the same object.
-	//
-	// It covers these cases:
-	//	val.x = val.y
-	//	val.x[i] = val.y[j]
-	//	val.x1.x2 = val.x1.y2
-	//	... etc
-	//
-	// These assignments do not change assigned object lifetime.
-
-	if dst == nil || src == nil || dst.Op() != src.Op() {
-		return false
-	}
-
-	// The expression prefix must be both "safe" and identical.
-	switch dst.Op() {
-	case ir.ODOT, ir.ODOTPTR:
-		// Safe trailing accessors that are permitted to differ.
-		dst := dst.(*ir.SelectorExpr)
-		src := src.(*ir.SelectorExpr)
-		return ir.SameSafeExpr(dst.X, src.X)
-	case ir.OINDEX:
-		dst := dst.(*ir.IndexExpr)
-		src := src.(*ir.IndexExpr)
-		if mayAffectMemory(dst.Index) || mayAffectMemory(src.Index) {
-			return false
-		}
-		return ir.SameSafeExpr(dst.X, src.X)
-	default:
-		return false
-	}
-}
-
-// mayAffectMemory reports whether evaluation of n may affect the program's
-// memory state. If the expression can't affect memory state, then it can be
-// safely ignored by the escape analysis.
-func mayAffectMemory(n ir.Node) bool {
-	// We may want to use a list of "memory safe" ops instead of generally
-	// "side-effect free", which would include all calls and other ops that can
-	// allocate or change global state. For now, it's safer to start with the latter.
-	//
-	// We're ignoring things like division by zero, index out of range,
-	// and nil pointer dereference here.
-
-	// TODO(rsc): It seems like it should be possible to replace this with
-	// an ir.Any looking for any op that's not the ones in the case statement.
-	// But that produces changes in the compiled output detected by buildall.
-	switch n.Op() {
-	case ir.ONAME, ir.OLITERAL, ir.ONIL:
-		return false
-
-	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OMOD:
-		n := n.(*ir.BinaryExpr)
-		return mayAffectMemory(n.X) || mayAffectMemory(n.Y)
-
-	case ir.OINDEX:
-		n := n.(*ir.IndexExpr)
-		return mayAffectMemory(n.X) || mayAffectMemory(n.Index)
-
-	case ir.OCONVNOP, ir.OCONV:
-		n := n.(*ir.ConvExpr)
-		return mayAffectMemory(n.X)
-
-	case ir.OLEN, ir.OCAP, ir.ONOT, ir.OBITNOT, ir.OPLUS, ir.ONEG, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
-		n := n.(*ir.UnaryExpr)
-		return mayAffectMemory(n.X)
-
-	case ir.ODOT, ir.ODOTPTR:
-		n := n.(*ir.SelectorExpr)
-		return mayAffectMemory(n.X)
-
-	case ir.ODEREF:
-		n := n.(*ir.StarExpr)
-		return mayAffectMemory(n.X)
-
-	default:
-		return true
-	}
-}
-
-// HeapAllocReason returns the reason the given Node must be heap
-// allocated, or the empty string if it doesn't.
-func HeapAllocReason(n ir.Node) string {
-	if n == nil || n.Type() == nil {
-		return ""
-	}
-
-	// Parameters are always passed via the stack.
-	if n.Op() == ir.ONAME {
-		n := n.(*ir.Name)
-		if n.Class == ir.PPARAM || n.Class == ir.PPARAMOUT {
-			return ""
-		}
-	}
-
-	if n.Type().Width > ir.MaxStackVarSize {
-		return "too large for stack"
-	}
-
-	if (n.Op() == ir.ONEW || n.Op() == ir.OPTRLIT) && n.Type().Elem().Width > ir.MaxImplicitStackVarSize {
-		return "too large for stack"
-	}
-
-	if n.Op() == ir.OCLOSURE && typecheck.ClosureType(n.(*ir.ClosureExpr)).Size() > ir.MaxImplicitStackVarSize {
-		return "too large for stack"
-	}
-	if n.Op() == ir.OCALLPART && typecheck.PartialCallType(n.(*ir.SelectorExpr)).Size() > ir.MaxImplicitStackVarSize {
-		return "too large for stack"
-	}
-
-	if n.Op() == ir.OMAKESLICE {
-		n := n.(*ir.MakeExpr)
-		r := n.Cap
-		if r == nil {
-			r = n.Len
-		}
-		if !ir.IsSmallIntConst(r) {
-			return "non-constant size"
-		}
-		if t := n.Type(); t.Elem().Width != 0 && ir.Int64Val(r) > ir.MaxImplicitStackVarSize/t.Elem().Width {
-			return "too large for stack"
-		}
-	}
-
-	return ""
-}
-
-// This special tag is applied to uintptr variables
-// that we believe may hold unsafe.Pointers for
-// calls into assembly functions.
-const UnsafeUintptrNote = "unsafe-uintptr"
-
-// This special tag is applied to uintptr parameters of functions
-// marked go:uintptrescapes.
-const UintptrEscapesNote = "uintptr-escapes"
-
-func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
-	name := func() string {
-		if f.Sym != nil {
-			return f.Sym.Name
-		}
-		return fmt.Sprintf("arg#%d", narg)
-	}
-
-	if len(fn.Body) == 0 {
-		// Assume that uintptr arguments must be held live across the call.
-		// This is most important for syscall.Syscall.
-		// See golang.org/issue/13372.
-		// This really doesn't have much to do with escape analysis per se,
-		// but we are reusing the ability to annotate an individual function
-		// argument and pass those annotations along to importing code.
-		if f.Type.IsUintptr() {
-			if base.Flag.LowerM != 0 {
-				base.WarnfAt(f.Pos, "assuming %v is unsafe uintptr", name())
-			}
-			return UnsafeUintptrNote
-		}
-
-		if !f.Type.HasPointers() { // don't bother tagging for scalars
-			return ""
-		}
-
-		var esc leaks
-
-		// External functions are assumed unsafe, unless
-		// //go:noescape is given before the declaration.
-		if fn.Pragma&ir.Noescape != 0 {
-			if base.Flag.LowerM != 0 && f.Sym != nil {
-				base.WarnfAt(f.Pos, "%v does not escape", name())
-			}
-		} else {
-			if base.Flag.LowerM != 0 && f.Sym != nil {
-				base.WarnfAt(f.Pos, "leaking param: %v", name())
-			}
-			esc.AddHeap(0)
-		}
-
-		return esc.Encode()
-	}
-
-	if fn.Pragma&ir.UintptrEscapes != 0 {
-		if f.Type.IsUintptr() {
-			if base.Flag.LowerM != 0 {
-				base.WarnfAt(f.Pos, "marking %v as escaping uintptr", name())
-			}
-			return UintptrEscapesNote
+			return ""
 		}
 		if f.IsDDD() && f.Type.Elem().IsUintptr() {
 			// final argument is ...uintptr.
-			if base.Flag.LowerM != 0 {
+			if diagnose {
 				base.WarnfAt(f.Pos, "marking %v as escaping ...uintptr", name())
 			}
-			return UintptrEscapesNote
+			return ""
 		}
 	}
 
@@ -2125,7 +447,7 @@ func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
 	esc := loc.paramEsc
 	esc.Optimize()
 
-	if base.Flag.LowerM != 0 && !loc.escapes {
+	if diagnose && !loc.escapes {
 		if esc.Empty() {
 			base.WarnfAt(f.Pos, "%v does not escape", name())
 		}
diff --git a/src/cmd/compile/internal/escape/expr.go b/src/cmd/compile/internal/escape/expr.go
new file mode 100644
index 0000000000000000000000000000000000000000..62afb5b9288cbe1c007a16ad67a3e126e67b11e8
--- /dev/null
+++ b/src/cmd/compile/internal/escape/expr.go
@@ -0,0 +1,335 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+)
+
+// expr models evaluating an expression n and flowing the result into
+// hole k.
+func (e *escape) expr(k hole, n ir.Node) {
+	if n == nil {
+		return
+	}
+	e.stmts(n.Init())
+	e.exprSkipInit(k, n)
+}
+
+func (e *escape) exprSkipInit(k hole, n ir.Node) {
+	if n == nil {
+		return
+	}
+
+	lno := ir.SetPos(n)
+	defer func() {
+		base.Pos = lno
+	}()
+
+	if k.derefs >= 0 && !n.Type().HasPointers() {
+		k.dst = &e.blankLoc
+	}
+
+	switch n.Op() {
+	default:
+		base.Fatalf("unexpected expr: %s %v", n.Op().String(), n)
+
+	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP, ir.OTYPE, ir.OMETHEXPR, ir.OLINKSYMOFFSET:
+		// nop
+
+	case ir.ONAME:
+		n := n.(*ir.Name)
+		if n.Class == ir.PFUNC || n.Class == ir.PEXTERN {
+			return
+		}
+		e.flow(k, e.oldLoc(n))
+
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT:
+		n := n.(*ir.UnaryExpr)
+		e.discard(n.X)
+	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
+		n := n.(*ir.BinaryExpr)
+		e.discard(n.X)
+		e.discard(n.Y)
+	case ir.OANDAND, ir.OOROR:
+		n := n.(*ir.LogicalExpr)
+		e.discard(n.X)
+		e.discard(n.Y)
+	case ir.OADDR:
+		n := n.(*ir.AddrExpr)
+		e.expr(k.addr(n, "address-of"), n.X) // "address-of"
+	case ir.ODEREF:
+		n := n.(*ir.StarExpr)
+		e.expr(k.deref(n, "indirection"), n.X) // "indirection"
+	case ir.ODOT, ir.ODOTMETH, ir.ODOTINTER:
+		n := n.(*ir.SelectorExpr)
+		e.expr(k.note(n, "dot"), n.X)
+	case ir.ODOTPTR:
+		n := n.(*ir.SelectorExpr)
+		e.expr(k.deref(n, "dot of pointer"), n.X) // "dot of pointer"
+	case ir.ODOTTYPE, ir.ODOTTYPE2:
+		n := n.(*ir.TypeAssertExpr)
+		e.expr(k.dotType(n.Type(), n, "dot"), n.X)
+	case ir.ODYNAMICDOTTYPE, ir.ODYNAMICDOTTYPE2:
+		n := n.(*ir.DynamicTypeAssertExpr)
+		e.expr(k.dotType(n.Type(), n, "dot"), n.X)
+		// n.T doesn't need to be tracked; it always points to read-only storage.
+	case ir.OINDEX:
+		n := n.(*ir.IndexExpr)
+		if n.X.Type().IsArray() {
+			e.expr(k.note(n, "fixed-array-index-of"), n.X)
+		} else {
+			// TODO(mdempsky): Fix why reason text.
+			e.expr(k.deref(n, "dot of pointer"), n.X)
+		}
+		e.discard(n.Index)
+	case ir.OINDEXMAP:
+		n := n.(*ir.IndexExpr)
+		e.discard(n.X)
+		e.discard(n.Index)
+	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR, ir.OSLICESTR:
+		n := n.(*ir.SliceExpr)
+		e.expr(k.note(n, "slice"), n.X)
+		e.discard(n.Low)
+		e.discard(n.High)
+		e.discard(n.Max)
+
+	case ir.OCONV, ir.OCONVNOP:
+		n := n.(*ir.ConvExpr)
+		if ir.ShouldCheckPtr(e.curfn, 2) && n.Type().IsUnsafePtr() && n.X.Type().IsPtr() {
+			// When -d=checkptr=2 is enabled, treat
+			// conversions to unsafe.Pointer as an
+			// escaping operation. This allows better
+			// runtime instrumentation, since we can more
+			// easily detect object boundaries on the heap
+			// than the stack.
+			e.assignHeap(n.X, "conversion to unsafe.Pointer", n)
+		} else if n.Type().IsUnsafePtr() && n.X.Type().IsUintptr() {
+			e.unsafeValue(k, n.X)
+		} else {
+			e.expr(k, n.X)
+		}
+	case ir.OCONVIFACE, ir.OCONVIDATA:
+		n := n.(*ir.ConvExpr)
+		if !n.X.Type().IsInterface() && !types.IsDirectIface(n.X.Type()) {
+			k = e.spill(k, n)
+		}
+		e.expr(k.note(n, "interface-converted"), n.X)
+	case ir.OEFACE:
+		n := n.(*ir.BinaryExpr)
+		// Note: n.X is not needed because it can never point to memory that might escape.
+		e.expr(k, n.Y)
+	case ir.OIDATA, ir.OSPTR:
+		n := n.(*ir.UnaryExpr)
+		e.expr(k, n.X)
+	case ir.OSLICE2ARRPTR:
+		// the slice pointer flows directly to the result
+		n := n.(*ir.ConvExpr)
+		e.expr(k, n.X)
+	case ir.ORECV:
+		n := n.(*ir.UnaryExpr)
+		e.discard(n.X)
+
+	case ir.OCALLMETH, ir.OCALLFUNC, ir.OCALLINTER, ir.OINLCALL, ir.OLEN, ir.OCAP, ir.OCOMPLEX, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.OCOPY, ir.ORECOVER, ir.OUNSAFEADD, ir.OUNSAFESLICE:
+		e.call([]hole{k}, n)
+
+	case ir.ONEW:
+		n := n.(*ir.UnaryExpr)
+		e.spill(k, n)
+
+	case ir.OMAKESLICE:
+		n := n.(*ir.MakeExpr)
+		e.spill(k, n)
+		e.discard(n.Len)
+		e.discard(n.Cap)
+	case ir.OMAKECHAN:
+		n := n.(*ir.MakeExpr)
+		e.discard(n.Len)
+	case ir.OMAKEMAP:
+		n := n.(*ir.MakeExpr)
+		e.spill(k, n)
+		e.discard(n.Len)
+
+	case ir.OMETHVALUE:
+		// Flow the receiver argument to both the closure and
+		// to the receiver parameter.
+
+		n := n.(*ir.SelectorExpr)
+		closureK := e.spill(k, n)
+
+		m := n.Selection
+
+		// We don't know how the method value will be called
+		// later, so conservatively assume the result
+		// parameters all flow to the heap.
+		//
+		// TODO(mdempsky): Change ks into a callback, so that
+		// we don't have to create this slice?
+		var ks []hole
+		for i := m.Type.NumResults(); i > 0; i-- {
+			ks = append(ks, e.heapHole())
+		}
+		name, _ := m.Nname.(*ir.Name)
+		paramK := e.tagHole(ks, name, m.Type.Recv())
+
+		e.expr(e.teeHole(paramK, closureK), n.X)
+
+	case ir.OPTRLIT:
+		n := n.(*ir.AddrExpr)
+		e.expr(e.spill(k, n), n.X)
+
+	case ir.OARRAYLIT:
+		n := n.(*ir.CompLitExpr)
+		for _, elt := range n.List {
+			if elt.Op() == ir.OKEY {
+				elt = elt.(*ir.KeyExpr).Value
+			}
+			e.expr(k.note(n, "array literal element"), elt)
+		}
+
+	case ir.OSLICELIT:
+		n := n.(*ir.CompLitExpr)
+		k = e.spill(k, n)
+
+		for _, elt := range n.List {
+			if elt.Op() == ir.OKEY {
+				elt = elt.(*ir.KeyExpr).Value
+			}
+			e.expr(k.note(n, "slice-literal-element"), elt)
+		}
+
+	case ir.OSTRUCTLIT:
+		n := n.(*ir.CompLitExpr)
+		for _, elt := range n.List {
+			e.expr(k.note(n, "struct literal element"), elt.(*ir.StructKeyExpr).Value)
+		}
+
+	case ir.OMAPLIT:
+		n := n.(*ir.CompLitExpr)
+		e.spill(k, n)
+
+		// Map keys and values are always stored in the heap.
+		for _, elt := range n.List {
+			elt := elt.(*ir.KeyExpr)
+			e.assignHeap(elt.Key, "map literal key", n)
+			e.assignHeap(elt.Value, "map literal value", n)
+		}
+
+	case ir.OCLOSURE:
+		n := n.(*ir.ClosureExpr)
+		k = e.spill(k, n)
+		e.closures = append(e.closures, closure{k, n})
+
+		if fn := n.Func; fn.IsHiddenClosure() {
+			for _, cv := range fn.ClosureVars {
+				if loc := e.oldLoc(cv); !loc.captured {
+					loc.captured = true
+
+					// Ignore reassignments to the variable in straightline code
+					// preceding the first capture by a closure.
+					if loc.loopDepth == e.loopDepth {
+						loc.reassigned = false
+					}
+				}
+			}
+
+			for _, n := range fn.Dcl {
+				// Add locations for local variables of the
+				// closure, if needed, in case we're not including
+				// the closure func in the batch for escape
+				// analysis (happens for escape analysis called
+				// from reflectdata.methodWrapper)
+				if n.Op() == ir.ONAME && n.Opt == nil {
+					e.with(fn).newLoc(n, false)
+				}
+			}
+			e.walkFunc(fn)
+		}
+
+	case ir.ORUNES2STR, ir.OBYTES2STR, ir.OSTR2RUNES, ir.OSTR2BYTES, ir.ORUNESTR:
+		n := n.(*ir.ConvExpr)
+		e.spill(k, n)
+		e.discard(n.X)
+
+	case ir.OADDSTR:
+		n := n.(*ir.AddStringExpr)
+		e.spill(k, n)
+
+		// Arguments of OADDSTR never escape;
+		// runtime.concatstrings makes sure of that.
+		e.discards(n.List)
+
+	case ir.ODYNAMICTYPE:
+		// Nothing to do - argument is a *runtime._type (+ maybe a *runtime.itab) pointing to static data section
+	}
+}
+
+// unsafeValue evaluates a uintptr-typed arithmetic expression looking
+// for conversions from an unsafe.Pointer.
+func (e *escape) unsafeValue(k hole, n ir.Node) {
+	if n.Type().Kind() != types.TUINTPTR {
+		base.Fatalf("unexpected type %v for %v", n.Type(), n)
+	}
+	if k.addrtaken {
+		base.Fatalf("unexpected addrtaken")
+	}
+
+	e.stmts(n.Init())
+
+	switch n.Op() {
+	case ir.OCONV, ir.OCONVNOP:
+		n := n.(*ir.ConvExpr)
+		if n.X.Type().IsUnsafePtr() {
+			e.expr(k, n.X)
+		} else {
+			e.discard(n.X)
+		}
+	case ir.ODOTPTR:
+		n := n.(*ir.SelectorExpr)
+		if ir.IsReflectHeaderDataField(n) {
+			e.expr(k.deref(n, "reflect.Header.Data"), n.X)
+		} else {
+			e.discard(n.X)
+		}
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT:
+		n := n.(*ir.UnaryExpr)
+		e.unsafeValue(k, n.X)
+	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OAND, ir.OANDNOT:
+		n := n.(*ir.BinaryExpr)
+		e.unsafeValue(k, n.X)
+		e.unsafeValue(k, n.Y)
+	case ir.OLSH, ir.ORSH:
+		n := n.(*ir.BinaryExpr)
+		e.unsafeValue(k, n.X)
+		// RHS need not be uintptr-typed (#32959) and can't meaningfully
+		// flow pointers anyway.
+		e.discard(n.Y)
+	default:
+		e.exprSkipInit(e.discardHole(), n)
+	}
+}
+
+// discard evaluates an expression n for side-effects, but discards
+// its value.
+func (e *escape) discard(n ir.Node) {
+	e.expr(e.discardHole(), n)
+}
+
+func (e *escape) discards(l ir.Nodes) {
+	for _, n := range l {
+		e.discard(n)
+	}
+}
+
+// spill allocates a new location associated with expression n, flows
+// its address to k, and returns a hole that flows values to it. It's
+// intended for use with most expressions that allocate storage.
+func (e *escape) spill(k hole, n ir.Node) hole {
+	loc := e.newLoc(n, true)
+	e.flow(k.addr(n, "spill"), loc)
+	return loc.asHole()
+}
diff --git a/src/cmd/compile/internal/escape/graph.go b/src/cmd/compile/internal/escape/graph.go
new file mode 100644
index 0000000000000000000000000000000000000000..cc3d078adddf8796349ab5aa813c81615450806b
--- /dev/null
+++ b/src/cmd/compile/internal/escape/graph.go
@@ -0,0 +1,324 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/types"
+	"fmt"
+)
+
+// Below we implement the methods for walking the AST and recording
+// data flow edges. Note that because a sub-expression might have
+// side-effects, it's important to always visit the entire AST.
+//
+// For example, write either:
+//
+//     if x {
+//         e.discard(n.Left)
+//     } else {
+//         e.value(k, n.Left)
+//     }
+//
+// or
+//
+//     if x {
+//         k = e.discardHole()
+//     }
+//     e.value(k, n.Left)
+//
+// Do NOT write:
+//
+//    // BAD: possibly loses side-effects within n.Left
+//    if !x {
+//        e.value(k, n.Left)
+//    }
+
+// An location represents an abstract location that stores a Go
+// variable.
+type location struct {
+	n         ir.Node  // represented variable or expression, if any
+	curfn     *ir.Func // enclosing function
+	edges     []edge   // incoming edges
+	loopDepth int      // loopDepth at declaration
+
+	// resultIndex records the tuple index (starting at 1) for
+	// PPARAMOUT variables within their function's result type.
+	// For non-PPARAMOUT variables it's 0.
+	resultIndex int
+
+	// derefs and walkgen are used during walkOne to track the
+	// minimal dereferences from the walk root.
+	derefs  int // >= -1
+	walkgen uint32
+
+	// dst and dstEdgeindex track the next immediate assignment
+	// destination location during walkone, along with the index
+	// of the edge pointing back to this location.
+	dst        *location
+	dstEdgeIdx int
+
+	// queued is used by walkAll to track whether this location is
+	// in the walk queue.
+	queued bool
+
+	// escapes reports whether the represented variable's address
+	// escapes; that is, whether the variable must be heap
+	// allocated.
+	escapes bool
+
+	// transient reports whether the represented expression's
+	// address does not outlive the statement; that is, whether
+	// its storage can be immediately reused.
+	transient bool
+
+	// paramEsc records the represented parameter's leak set.
+	paramEsc leaks
+
+	captured   bool // has a closure captured this variable?
+	reassigned bool // has this variable been reassigned?
+	addrtaken  bool // has this variable's address been taken?
+}
+
+// An edge represents an assignment edge between two Go variables.
+type edge struct {
+	src    *location
+	derefs int // >= -1
+	notes  *note
+}
+
+func (l *location) asHole() hole {
+	return hole{dst: l}
+}
+
+// leak records that parameter l leaks to sink.
+func (l *location) leakTo(sink *location, derefs int) {
+	// If sink is a result parameter that doesn't escape (#44614)
+	// and we can fit return bits into the escape analysis tag,
+	// then record as a result leak.
+	if !sink.escapes && sink.isName(ir.PPARAMOUT) && sink.curfn == l.curfn {
+		ri := sink.resultIndex - 1
+		if ri < numEscResults {
+			// Leak to result parameter.
+			l.paramEsc.AddResult(ri, derefs)
+			return
+		}
+	}
+
+	// Otherwise, record as heap leak.
+	l.paramEsc.AddHeap(derefs)
+}
+
+func (l *location) isName(c ir.Class) bool {
+	return l.n != nil && l.n.Op() == ir.ONAME && l.n.(*ir.Name).Class == c
+}
+
+// A hole represents a context for evaluation of a Go
+// expression. E.g., when evaluating p in "x = **p", we'd have a hole
+// with dst==x and derefs==2.
+type hole struct {
+	dst    *location
+	derefs int // >= -1
+	notes  *note
+
+	// addrtaken indicates whether this context is taking the address of
+	// the expression, independent of whether the address will actually
+	// be stored into a variable.
+	addrtaken bool
+}
+
+type note struct {
+	next  *note
+	where ir.Node
+	why   string
+}
+
+func (k hole) note(where ir.Node, why string) hole {
+	if where == nil || why == "" {
+		base.Fatalf("note: missing where/why")
+	}
+	if base.Flag.LowerM >= 2 || logopt.Enabled() {
+		k.notes = ¬e{
+			next:  k.notes,
+			where: where,
+			why:   why,
+		}
+	}
+	return k
+}
+
+func (k hole) shift(delta int) hole {
+	k.derefs += delta
+	if k.derefs < -1 {
+		base.Fatalf("derefs underflow: %v", k.derefs)
+	}
+	k.addrtaken = delta < 0
+	return k
+}
+
+func (k hole) deref(where ir.Node, why string) hole { return k.shift(1).note(where, why) }
+func (k hole) addr(where ir.Node, why string) hole  { return k.shift(-1).note(where, why) }
+
+func (k hole) dotType(t *types.Type, where ir.Node, why string) hole {
+	if !t.IsInterface() && !types.IsDirectIface(t) {
+		k = k.shift(1)
+	}
+	return k.note(where, why)
+}
+
+func (b *batch) flow(k hole, src *location) {
+	if k.addrtaken {
+		src.addrtaken = true
+	}
+
+	dst := k.dst
+	if dst == &b.blankLoc {
+		return
+	}
+	if dst == src && k.derefs >= 0 { // dst = dst, dst = *dst, ...
+		return
+	}
+	if dst.escapes && k.derefs < 0 { // dst = &src
+		if base.Flag.LowerM >= 2 || logopt.Enabled() {
+			pos := base.FmtPos(src.n.Pos())
+			if base.Flag.LowerM >= 2 {
+				fmt.Printf("%s: %v escapes to heap:\n", pos, src.n)
+			}
+			explanation := b.explainFlow(pos, dst, src, k.derefs, k.notes, []*logopt.LoggedOpt{})
+			if logopt.Enabled() {
+				var e_curfn *ir.Func // TODO(mdempsky): Fix.
+				logopt.LogOpt(src.n.Pos(), "escapes", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", src.n), explanation)
+			}
+
+		}
+		src.escapes = true
+		return
+	}
+
+	// TODO(mdempsky): Deduplicate edges?
+	dst.edges = append(dst.edges, edge{src: src, derefs: k.derefs, notes: k.notes})
+}
+
+func (b *batch) heapHole() hole    { return b.heapLoc.asHole() }
+func (b *batch) discardHole() hole { return b.blankLoc.asHole() }
+
+func (b *batch) oldLoc(n *ir.Name) *location {
+	if n.Canonical().Opt == nil {
+		base.Fatalf("%v has no location", n)
+	}
+	return n.Canonical().Opt.(*location)
+}
+
+func (e *escape) newLoc(n ir.Node, transient bool) *location {
+	if e.curfn == nil {
+		base.Fatalf("e.curfn isn't set")
+	}
+	if n != nil && n.Type() != nil && n.Type().NotInHeap() {
+		base.ErrorfAt(n.Pos(), "%v is incomplete (or unallocatable); stack allocation disallowed", n.Type())
+	}
+
+	if n != nil && n.Op() == ir.ONAME {
+		if canon := n.(*ir.Name).Canonical(); n != canon {
+			base.Fatalf("newLoc on non-canonical %v (canonical is %v)", n, canon)
+		}
+	}
+	loc := &location{
+		n:         n,
+		curfn:     e.curfn,
+		loopDepth: e.loopDepth,
+		transient: transient,
+	}
+	e.allLocs = append(e.allLocs, loc)
+	if n != nil {
+		if n.Op() == ir.ONAME {
+			n := n.(*ir.Name)
+			if n.Class == ir.PPARAM && n.Curfn == nil {
+				// ok; hidden parameter
+			} else if n.Curfn != e.curfn {
+				base.Fatalf("curfn mismatch: %v != %v for %v", n.Curfn, e.curfn, n)
+			}
+
+			if n.Opt != nil {
+				base.Fatalf("%v already has a location", n)
+			}
+			n.Opt = loc
+		}
+	}
+	return loc
+}
+
+// teeHole returns a new hole that flows into each hole of ks,
+// similar to the Unix tee(1) command.
+func (e *escape) teeHole(ks ...hole) hole {
+	if len(ks) == 0 {
+		return e.discardHole()
+	}
+	if len(ks) == 1 {
+		return ks[0]
+	}
+	// TODO(mdempsky): Optimize if there's only one non-discard hole?
+
+	// Given holes "l1 = _", "l2 = **_", "l3 = *_", ..., create a
+	// new temporary location ltmp, wire it into place, and return
+	// a hole for "ltmp = _".
+	loc := e.newLoc(nil, true)
+	for _, k := range ks {
+		// N.B., "p = &q" and "p = &tmp; tmp = q" are not
+		// semantically equivalent. To combine holes like "l1
+		// = _" and "l2 = &_", we'd need to wire them as "l1 =
+		// *ltmp" and "l2 = ltmp" and return "ltmp = &_"
+		// instead.
+		if k.derefs < 0 {
+			base.Fatalf("teeHole: negative derefs")
+		}
+
+		e.flow(k, loc)
+	}
+	return loc.asHole()
+}
+
+// later returns a new hole that flows into k, but some time later.
+// Its main effect is to prevent immediate reuse of temporary
+// variables introduced during Order.
+func (e *escape) later(k hole) hole {
+	loc := e.newLoc(nil, false)
+	e.flow(k, loc)
+	return loc.asHole()
+}
+
+// Fmt is called from node printing to print information about escape analysis results.
+func Fmt(n ir.Node) string {
+	text := ""
+	switch n.Esc() {
+	case ir.EscUnknown:
+		break
+
+	case ir.EscHeap:
+		text = "esc(h)"
+
+	case ir.EscNone:
+		text = "esc(no)"
+
+	case ir.EscNever:
+		text = "esc(N)"
+
+	default:
+		text = fmt.Sprintf("esc(%d)", n.Esc())
+	}
+
+	if n.Op() == ir.ONAME {
+		n := n.(*ir.Name)
+		if loc, ok := n.Opt.(*location); ok && loc.loopDepth != 0 {
+			if text != "" {
+				text += " "
+			}
+			text += fmt.Sprintf("ld(%d)", loc.loopDepth)
+		}
+	}
+
+	return text
+}
diff --git a/src/cmd/compile/internal/escape/leaks.go b/src/cmd/compile/internal/escape/leaks.go
new file mode 100644
index 0000000000000000000000000000000000000000..4c848a5ee7859d0f2bfe3adf4118df263c0bd1f9
--- /dev/null
+++ b/src/cmd/compile/internal/escape/leaks.go
@@ -0,0 +1,106 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"math"
+	"strings"
+)
+
+const numEscResults = 7
+
+// An leaks represents a set of assignment flows from a parameter
+// to the heap or to any of its function's (first numEscResults)
+// result parameters.
+type leaks [1 + numEscResults]uint8
+
+// Empty reports whether l is an empty set (i.e., no assignment flows).
+func (l leaks) Empty() bool { return l == leaks{} }
+
+// Heap returns the minimum deref count of any assignment flow from l
+// to the heap. If no such flows exist, Heap returns -1.
+func (l leaks) Heap() int { return l.get(0) }
+
+// Result returns the minimum deref count of any assignment flow from
+// l to its function's i'th result parameter. If no such flows exist,
+// Result returns -1.
+func (l leaks) Result(i int) int { return l.get(1 + i) }
+
+// AddHeap adds an assignment flow from l to the heap.
+func (l *leaks) AddHeap(derefs int) { l.add(0, derefs) }
+
+// AddResult adds an assignment flow from l to its function's i'th
+// result parameter.
+func (l *leaks) AddResult(i, derefs int) { l.add(1+i, derefs) }
+
+func (l *leaks) setResult(i, derefs int) { l.set(1+i, derefs) }
+
+func (l leaks) get(i int) int { return int(l[i]) - 1 }
+
+func (l *leaks) add(i, derefs int) {
+	if old := l.get(i); old < 0 || derefs < old {
+		l.set(i, derefs)
+	}
+}
+
+func (l *leaks) set(i, derefs int) {
+	v := derefs + 1
+	if v < 0 {
+		base.Fatalf("invalid derefs count: %v", derefs)
+	}
+	if v > math.MaxUint8 {
+		v = math.MaxUint8
+	}
+
+	l[i] = uint8(v)
+}
+
+// Optimize removes result flow paths that are equal in length or
+// longer than the shortest heap flow path.
+func (l *leaks) Optimize() {
+	// If we have a path to the heap, then there's no use in
+	// keeping equal or longer paths elsewhere.
+	if x := l.Heap(); x >= 0 {
+		for i := 0; i < numEscResults; i++ {
+			if l.Result(i) >= x {
+				l.setResult(i, -1)
+			}
+		}
+	}
+}
+
+var leakTagCache = map[leaks]string{}
+
+// Encode converts l into a binary string for export data.
+func (l leaks) Encode() string {
+	if l.Heap() == 0 {
+		// Space optimization: empty string encodes more
+		// efficiently in export data.
+		return ""
+	}
+	if s, ok := leakTagCache[l]; ok {
+		return s
+	}
+
+	n := len(l)
+	for n > 0 && l[n-1] == 0 {
+		n--
+	}
+	s := "esc:" + string(l[:n])
+	leakTagCache[l] = s
+	return s
+}
+
+// parseLeaks parses a binary string representing a leaks
+func parseLeaks(s string) leaks {
+	var l leaks
+	if !strings.HasPrefix(s, "esc:") {
+		l.AddHeap(0)
+		return l
+	}
+	copy(l[:], s[4:])
+	return l
+}
diff --git a/src/cmd/compile/internal/escape/solve.go b/src/cmd/compile/internal/escape/solve.go
new file mode 100644
index 0000000000000000000000000000000000000000..77d6b27dd75b01178d546b18da323f1263558566
--- /dev/null
+++ b/src/cmd/compile/internal/escape/solve.go
@@ -0,0 +1,289 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/logopt"
+	"cmd/internal/src"
+	"fmt"
+	"strings"
+)
+
+// walkAll computes the minimal dereferences between all pairs of
+// locations.
+func (b *batch) walkAll() {
+	// We use a work queue to keep track of locations that we need
+	// to visit, and repeatedly walk until we reach a fixed point.
+	//
+	// We walk once from each location (including the heap), and
+	// then re-enqueue each location on its transition from
+	// transient->!transient and !escapes->escapes, which can each
+	// happen at most once. So we take Θ(len(e.allLocs)) walks.
+
+	// LIFO queue, has enough room for e.allLocs and e.heapLoc.
+	todo := make([]*location, 0, len(b.allLocs)+1)
+	enqueue := func(loc *location) {
+		if !loc.queued {
+			todo = append(todo, loc)
+			loc.queued = true
+		}
+	}
+
+	for _, loc := range b.allLocs {
+		enqueue(loc)
+	}
+	enqueue(&b.heapLoc)
+
+	var walkgen uint32
+	for len(todo) > 0 {
+		root := todo[len(todo)-1]
+		todo = todo[:len(todo)-1]
+		root.queued = false
+
+		walkgen++
+		b.walkOne(root, walkgen, enqueue)
+	}
+}
+
+// walkOne computes the minimal number of dereferences from root to
+// all other locations.
+func (b *batch) walkOne(root *location, walkgen uint32, enqueue func(*location)) {
+	// The data flow graph has negative edges (from addressing
+	// operations), so we use the Bellman-Ford algorithm. However,
+	// we don't have to worry about infinite negative cycles since
+	// we bound intermediate dereference counts to 0.
+
+	root.walkgen = walkgen
+	root.derefs = 0
+	root.dst = nil
+
+	todo := []*location{root} // LIFO queue
+	for len(todo) > 0 {
+		l := todo[len(todo)-1]
+		todo = todo[:len(todo)-1]
+
+		derefs := l.derefs
+
+		// If l.derefs < 0, then l's address flows to root.
+		addressOf := derefs < 0
+		if addressOf {
+			// For a flow path like "root = &l; l = x",
+			// l's address flows to root, but x's does
+			// not. We recognize this by lower bounding
+			// derefs at 0.
+			derefs = 0
+
+			// If l's address flows to a non-transient
+			// location, then l can't be transiently
+			// allocated.
+			if !root.transient && l.transient {
+				l.transient = false
+				enqueue(l)
+			}
+		}
+
+		if b.outlives(root, l) {
+			// l's value flows to root. If l is a function
+			// parameter and root is the heap or a
+			// corresponding result parameter, then record
+			// that value flow for tagging the function
+			// later.
+			if l.isName(ir.PPARAM) {
+				if (logopt.Enabled() || base.Flag.LowerM >= 2) && !l.escapes {
+					if base.Flag.LowerM >= 2 {
+						fmt.Printf("%s: parameter %v leaks to %s with derefs=%d:\n", base.FmtPos(l.n.Pos()), l.n, b.explainLoc(root), derefs)
+					}
+					explanation := b.explainPath(root, l)
+					if logopt.Enabled() {
+						var e_curfn *ir.Func // TODO(mdempsky): Fix.
+						logopt.LogOpt(l.n.Pos(), "leak", "escape", ir.FuncName(e_curfn),
+							fmt.Sprintf("parameter %v leaks to %s with derefs=%d", l.n, b.explainLoc(root), derefs), explanation)
+					}
+				}
+				l.leakTo(root, derefs)
+			}
+
+			// If l's address flows somewhere that
+			// outlives it, then l needs to be heap
+			// allocated.
+			if addressOf && !l.escapes {
+				if logopt.Enabled() || base.Flag.LowerM >= 2 {
+					if base.Flag.LowerM >= 2 {
+						fmt.Printf("%s: %v escapes to heap:\n", base.FmtPos(l.n.Pos()), l.n)
+					}
+					explanation := b.explainPath(root, l)
+					if logopt.Enabled() {
+						var e_curfn *ir.Func // TODO(mdempsky): Fix.
+						logopt.LogOpt(l.n.Pos(), "escape", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", l.n), explanation)
+					}
+				}
+				l.escapes = true
+				enqueue(l)
+				continue
+			}
+		}
+
+		for i, edge := range l.edges {
+			if edge.src.escapes {
+				continue
+			}
+			d := derefs + edge.derefs
+			if edge.src.walkgen != walkgen || edge.src.derefs > d {
+				edge.src.walkgen = walkgen
+				edge.src.derefs = d
+				edge.src.dst = l
+				edge.src.dstEdgeIdx = i
+				todo = append(todo, edge.src)
+			}
+		}
+	}
+}
+
+// explainPath prints an explanation of how src flows to the walk root.
+func (b *batch) explainPath(root, src *location) []*logopt.LoggedOpt {
+	visited := make(map[*location]bool)
+	pos := base.FmtPos(src.n.Pos())
+	var explanation []*logopt.LoggedOpt
+	for {
+		// Prevent infinite loop.
+		if visited[src] {
+			if base.Flag.LowerM >= 2 {
+				fmt.Printf("%s:   warning: truncated explanation due to assignment cycle; see golang.org/issue/35518\n", pos)
+			}
+			break
+		}
+		visited[src] = true
+		dst := src.dst
+		edge := &dst.edges[src.dstEdgeIdx]
+		if edge.src != src {
+			base.Fatalf("path inconsistency: %v != %v", edge.src, src)
+		}
+
+		explanation = b.explainFlow(pos, dst, src, edge.derefs, edge.notes, explanation)
+
+		if dst == root {
+			break
+		}
+		src = dst
+	}
+
+	return explanation
+}
+
+func (b *batch) explainFlow(pos string, dst, srcloc *location, derefs int, notes *note, explanation []*logopt.LoggedOpt) []*logopt.LoggedOpt {
+	ops := "&"
+	if derefs >= 0 {
+		ops = strings.Repeat("*", derefs)
+	}
+	print := base.Flag.LowerM >= 2
+
+	flow := fmt.Sprintf("   flow: %s = %s%v:", b.explainLoc(dst), ops, b.explainLoc(srcloc))
+	if print {
+		fmt.Printf("%s:%s\n", pos, flow)
+	}
+	if logopt.Enabled() {
+		var epos src.XPos
+		if notes != nil {
+			epos = notes.where.Pos()
+		} else if srcloc != nil && srcloc.n != nil {
+			epos = srcloc.n.Pos()
+		}
+		var e_curfn *ir.Func // TODO(mdempsky): Fix.
+		explanation = append(explanation, logopt.NewLoggedOpt(epos, "escflow", "escape", ir.FuncName(e_curfn), flow))
+	}
+
+	for note := notes; note != nil; note = note.next {
+		if print {
+			fmt.Printf("%s:     from %v (%v) at %s\n", pos, note.where, note.why, base.FmtPos(note.where.Pos()))
+		}
+		if logopt.Enabled() {
+			var e_curfn *ir.Func // TODO(mdempsky): Fix.
+			explanation = append(explanation, logopt.NewLoggedOpt(note.where.Pos(), "escflow", "escape", ir.FuncName(e_curfn),
+				fmt.Sprintf("     from %v (%v)", note.where, note.why)))
+		}
+	}
+	return explanation
+}
+
+func (b *batch) explainLoc(l *location) string {
+	if l == &b.heapLoc {
+		return "{heap}"
+	}
+	if l.n == nil {
+		// TODO(mdempsky): Omit entirely.
+		return "{temp}"
+	}
+	if l.n.Op() == ir.ONAME {
+		return fmt.Sprintf("%v", l.n)
+	}
+	return fmt.Sprintf("{storage for %v}", l.n)
+}
+
+// outlives reports whether values stored in l may survive beyond
+// other's lifetime if stack allocated.
+func (b *batch) outlives(l, other *location) bool {
+	// The heap outlives everything.
+	if l.escapes {
+		return true
+	}
+
+	// We don't know what callers do with returned values, so
+	// pessimistically we need to assume they flow to the heap and
+	// outlive everything too.
+	if l.isName(ir.PPARAMOUT) {
+		// Exception: Directly called closures can return
+		// locations allocated outside of them without forcing
+		// them to the heap. For example:
+		//
+		//    var u int  // okay to stack allocate
+		//    *(func() *int { return &u }()) = 42
+		if containsClosure(other.curfn, l.curfn) && l.curfn.ClosureCalled() {
+			return false
+		}
+
+		return true
+	}
+
+	// If l and other are within the same function, then l
+	// outlives other if it was declared outside other's loop
+	// scope. For example:
+	//
+	//    var l *int
+	//    for {
+	//        l = new(int)
+	//    }
+	if l.curfn == other.curfn && l.loopDepth < other.loopDepth {
+		return true
+	}
+
+	// If other is declared within a child closure of where l is
+	// declared, then l outlives it. For example:
+	//
+	//    var l *int
+	//    func() {
+	//        l = new(int)
+	//    }
+	if containsClosure(l.curfn, other.curfn) {
+		return true
+	}
+
+	return false
+}
+
+// containsClosure reports whether c is a closure contained within f.
+func containsClosure(f, c *ir.Func) bool {
+	// Common case.
+	if f == c {
+		return false
+	}
+
+	// Closures within function Foo are named like "Foo.funcN..."
+	// TODO(mdempsky): Better way to recognize this.
+	fn := f.Sym().Name
+	cn := c.Sym().Name
+	return len(cn) > len(fn) && cn[:len(fn)] == fn && cn[len(fn)] == '.'
+}
diff --git a/src/cmd/compile/internal/escape/stmt.go b/src/cmd/compile/internal/escape/stmt.go
new file mode 100644
index 0000000000000000000000000000000000000000..c71848b8a1ca678c0c78934d1b75c44e686b997f
--- /dev/null
+++ b/src/cmd/compile/internal/escape/stmt.go
@@ -0,0 +1,207 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"fmt"
+)
+
+// stmt evaluates a single Go statement.
+func (e *escape) stmt(n ir.Node) {
+	if n == nil {
+		return
+	}
+
+	lno := ir.SetPos(n)
+	defer func() {
+		base.Pos = lno
+	}()
+
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v:[%d] %v stmt: %v\n", base.FmtPos(base.Pos), e.loopDepth, e.curfn, n)
+	}
+
+	e.stmts(n.Init())
+
+	switch n.Op() {
+	default:
+		base.Fatalf("unexpected stmt: %v", n)
+
+	case ir.ODCLCONST, ir.ODCLTYPE, ir.OFALL, ir.OINLMARK:
+		// nop
+
+	case ir.OBREAK, ir.OCONTINUE, ir.OGOTO:
+		// TODO(mdempsky): Handle dead code?
+
+	case ir.OBLOCK:
+		n := n.(*ir.BlockStmt)
+		e.stmts(n.List)
+
+	case ir.ODCL:
+		// Record loop depth at declaration.
+		n := n.(*ir.Decl)
+		if !ir.IsBlank(n.X) {
+			e.dcl(n.X)
+		}
+
+	case ir.OLABEL:
+		n := n.(*ir.LabelStmt)
+		switch e.labels[n.Label] {
+		case nonlooping:
+			if base.Flag.LowerM > 2 {
+				fmt.Printf("%v:%v non-looping label\n", base.FmtPos(base.Pos), n)
+			}
+		case looping:
+			if base.Flag.LowerM > 2 {
+				fmt.Printf("%v: %v looping label\n", base.FmtPos(base.Pos), n)
+			}
+			e.loopDepth++
+		default:
+			base.Fatalf("label missing tag")
+		}
+		delete(e.labels, n.Label)
+
+	case ir.OIF:
+		n := n.(*ir.IfStmt)
+		e.discard(n.Cond)
+		e.block(n.Body)
+		e.block(n.Else)
+
+	case ir.OFOR, ir.OFORUNTIL:
+		n := n.(*ir.ForStmt)
+		e.loopDepth++
+		e.discard(n.Cond)
+		e.stmt(n.Post)
+		e.block(n.Body)
+		e.loopDepth--
+
+	case ir.ORANGE:
+		// for Key, Value = range X { Body }
+		n := n.(*ir.RangeStmt)
+
+		// X is evaluated outside the loop.
+		tmp := e.newLoc(nil, false)
+		e.expr(tmp.asHole(), n.X)
+
+		e.loopDepth++
+		ks := e.addrs([]ir.Node{n.Key, n.Value})
+		if n.X.Type().IsArray() {
+			e.flow(ks[1].note(n, "range"), tmp)
+		} else {
+			e.flow(ks[1].deref(n, "range-deref"), tmp)
+		}
+		e.reassigned(ks, n)
+
+		e.block(n.Body)
+		e.loopDepth--
+
+	case ir.OSWITCH:
+		n := n.(*ir.SwitchStmt)
+
+		if guard, ok := n.Tag.(*ir.TypeSwitchGuard); ok {
+			var ks []hole
+			if guard.Tag != nil {
+				for _, cas := range n.Cases {
+					cv := cas.Var
+					k := e.dcl(cv) // type switch variables have no ODCL.
+					if cv.Type().HasPointers() {
+						ks = append(ks, k.dotType(cv.Type(), cas, "switch case"))
+					}
+				}
+			}
+			e.expr(e.teeHole(ks...), n.Tag.(*ir.TypeSwitchGuard).X)
+		} else {
+			e.discard(n.Tag)
+		}
+
+		for _, cas := range n.Cases {
+			e.discards(cas.List)
+			e.block(cas.Body)
+		}
+
+	case ir.OSELECT:
+		n := n.(*ir.SelectStmt)
+		for _, cas := range n.Cases {
+			e.stmt(cas.Comm)
+			e.block(cas.Body)
+		}
+	case ir.ORECV:
+		// TODO(mdempsky): Consider e.discard(n.Left).
+		n := n.(*ir.UnaryExpr)
+		e.exprSkipInit(e.discardHole(), n) // already visited n.Ninit
+	case ir.OSEND:
+		n := n.(*ir.SendStmt)
+		e.discard(n.Chan)
+		e.assignHeap(n.Value, "send", n)
+
+	case ir.OAS:
+		n := n.(*ir.AssignStmt)
+		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
+	case ir.OASOP:
+		n := n.(*ir.AssignOpStmt)
+		// TODO(mdempsky): Worry about OLSH/ORSH?
+		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
+	case ir.OAS2:
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair", n)
+
+	case ir.OAS2DOTTYPE: // v, ok = x.(type)
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair-dot-type", n)
+	case ir.OAS2MAPR: // v, ok = m[k]
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair-mapr", n)
+	case ir.OAS2RECV, ir.OSELRECV2: // v, ok = <-ch
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair-receive", n)
+
+	case ir.OAS2FUNC:
+		n := n.(*ir.AssignListStmt)
+		e.stmts(n.Rhs[0].Init())
+		ks := e.addrs(n.Lhs)
+		e.call(ks, n.Rhs[0])
+		e.reassigned(ks, n)
+	case ir.ORETURN:
+		n := n.(*ir.ReturnStmt)
+		results := e.curfn.Type().Results().FieldSlice()
+		dsts := make([]ir.Node, len(results))
+		for i, res := range results {
+			dsts[i] = res.Nname.(*ir.Name)
+		}
+		e.assignList(dsts, n.Results, "return", n)
+	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER, ir.OINLCALL, ir.OCLOSE, ir.OCOPY, ir.ODELETE, ir.OPANIC, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+		e.call(nil, n)
+	case ir.OGO, ir.ODEFER:
+		n := n.(*ir.GoDeferStmt)
+		e.goDeferStmt(n)
+
+	case ir.OTAILCALL:
+		// TODO(mdempsky): Treat like a normal call? esc.go used to just ignore it.
+	}
+}
+
+func (e *escape) stmts(l ir.Nodes) {
+	for _, n := range l {
+		e.stmt(n)
+	}
+}
+
+// block is like stmts, but preserves loopDepth.
+func (e *escape) block(l ir.Nodes) {
+	old := e.loopDepth
+	e.stmts(l)
+	e.loopDepth = old
+}
+
+func (e *escape) dcl(n *ir.Name) hole {
+	if n.Curfn != e.curfn || n.IsClosureVar() {
+		base.Fatalf("bad declaration of %v", n)
+	}
+	loc := e.oldLoc(n)
+	loc.loopDepth = e.loopDepth
+	return loc.asHole()
+}
diff --git a/src/cmd/compile/internal/escape/utils.go b/src/cmd/compile/internal/escape/utils.go
new file mode 100644
index 0000000000000000000000000000000000000000..5f462ef570faaef15f9a3e37f528ba1f1d0391ae
--- /dev/null
+++ b/src/cmd/compile/internal/escape/utils.go
@@ -0,0 +1,215 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+)
+
+func isSliceSelfAssign(dst, src ir.Node) bool {
+	// Detect the following special case.
+	//
+	//	func (b *Buffer) Foo() {
+	//		n, m := ...
+	//		b.buf = b.buf[n:m]
+	//	}
+	//
+	// This assignment is a no-op for escape analysis,
+	// it does not store any new pointers into b that were not already there.
+	// However, without this special case b will escape, because we assign to OIND/ODOTPTR.
+	// Here we assume that the statement will not contain calls,
+	// that is, that order will move any calls to init.
+	// Otherwise base ONAME value could change between the moments
+	// when we evaluate it for dst and for src.
+
+	// dst is ONAME dereference.
+	var dstX ir.Node
+	switch dst.Op() {
+	default:
+		return false
+	case ir.ODEREF:
+		dst := dst.(*ir.StarExpr)
+		dstX = dst.X
+	case ir.ODOTPTR:
+		dst := dst.(*ir.SelectorExpr)
+		dstX = dst.X
+	}
+	if dstX.Op() != ir.ONAME {
+		return false
+	}
+	// src is a slice operation.
+	switch src.Op() {
+	case ir.OSLICE, ir.OSLICE3, ir.OSLICESTR:
+		// OK.
+	case ir.OSLICEARR, ir.OSLICE3ARR:
+		// Since arrays are embedded into containing object,
+		// slice of non-pointer array will introduce a new pointer into b that was not already there
+		// (pointer to b itself). After such assignment, if b contents escape,
+		// b escapes as well. If we ignore such OSLICEARR, we will conclude
+		// that b does not escape when b contents do.
+		//
+		// Pointer to an array is OK since it's not stored inside b directly.
+		// For slicing an array (not pointer to array), there is an implicit OADDR.
+		// We check that to determine non-pointer array slicing.
+		src := src.(*ir.SliceExpr)
+		if src.X.Op() == ir.OADDR {
+			return false
+		}
+	default:
+		return false
+	}
+	// slice is applied to ONAME dereference.
+	var baseX ir.Node
+	switch base := src.(*ir.SliceExpr).X; base.Op() {
+	default:
+		return false
+	case ir.ODEREF:
+		base := base.(*ir.StarExpr)
+		baseX = base.X
+	case ir.ODOTPTR:
+		base := base.(*ir.SelectorExpr)
+		baseX = base.X
+	}
+	if baseX.Op() != ir.ONAME {
+		return false
+	}
+	// dst and src reference the same base ONAME.
+	return dstX.(*ir.Name) == baseX.(*ir.Name)
+}
+
+// isSelfAssign reports whether assignment from src to dst can
+// be ignored by the escape analysis as it's effectively a self-assignment.
+func isSelfAssign(dst, src ir.Node) bool {
+	if isSliceSelfAssign(dst, src) {
+		return true
+	}
+
+	// Detect trivial assignments that assign back to the same object.
+	//
+	// It covers these cases:
+	//	val.x = val.y
+	//	val.x[i] = val.y[j]
+	//	val.x1.x2 = val.x1.y2
+	//	... etc
+	//
+	// These assignments do not change assigned object lifetime.
+
+	if dst == nil || src == nil || dst.Op() != src.Op() {
+		return false
+	}
+
+	// The expression prefix must be both "safe" and identical.
+	switch dst.Op() {
+	case ir.ODOT, ir.ODOTPTR:
+		// Safe trailing accessors that are permitted to differ.
+		dst := dst.(*ir.SelectorExpr)
+		src := src.(*ir.SelectorExpr)
+		return ir.SameSafeExpr(dst.X, src.X)
+	case ir.OINDEX:
+		dst := dst.(*ir.IndexExpr)
+		src := src.(*ir.IndexExpr)
+		if mayAffectMemory(dst.Index) || mayAffectMemory(src.Index) {
+			return false
+		}
+		return ir.SameSafeExpr(dst.X, src.X)
+	default:
+		return false
+	}
+}
+
+// mayAffectMemory reports whether evaluation of n may affect the program's
+// memory state. If the expression can't affect memory state, then it can be
+// safely ignored by the escape analysis.
+func mayAffectMemory(n ir.Node) bool {
+	// We may want to use a list of "memory safe" ops instead of generally
+	// "side-effect free", which would include all calls and other ops that can
+	// allocate or change global state. For now, it's safer to start with the latter.
+	//
+	// We're ignoring things like division by zero, index out of range,
+	// and nil pointer dereference here.
+
+	// TODO(rsc): It seems like it should be possible to replace this with
+	// an ir.Any looking for any op that's not the ones in the case statement.
+	// But that produces changes in the compiled output detected by buildall.
+	switch n.Op() {
+	case ir.ONAME, ir.OLITERAL, ir.ONIL:
+		return false
+
+	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OMOD:
+		n := n.(*ir.BinaryExpr)
+		return mayAffectMemory(n.X) || mayAffectMemory(n.Y)
+
+	case ir.OINDEX:
+		n := n.(*ir.IndexExpr)
+		return mayAffectMemory(n.X) || mayAffectMemory(n.Index)
+
+	case ir.OCONVNOP, ir.OCONV:
+		n := n.(*ir.ConvExpr)
+		return mayAffectMemory(n.X)
+
+	case ir.OLEN, ir.OCAP, ir.ONOT, ir.OBITNOT, ir.OPLUS, ir.ONEG, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
+		n := n.(*ir.UnaryExpr)
+		return mayAffectMemory(n.X)
+
+	case ir.ODOT, ir.ODOTPTR:
+		n := n.(*ir.SelectorExpr)
+		return mayAffectMemory(n.X)
+
+	case ir.ODEREF:
+		n := n.(*ir.StarExpr)
+		return mayAffectMemory(n.X)
+
+	default:
+		return true
+	}
+}
+
+// HeapAllocReason returns the reason the given Node must be heap
+// allocated, or the empty string if it doesn't.
+func HeapAllocReason(n ir.Node) string {
+	if n == nil || n.Type() == nil {
+		return ""
+	}
+
+	// Parameters are always passed via the stack.
+	if n.Op() == ir.ONAME {
+		n := n.(*ir.Name)
+		if n.Class == ir.PPARAM || n.Class == ir.PPARAMOUT {
+			return ""
+		}
+	}
+
+	if n.Type().Width > ir.MaxStackVarSize {
+		return "too large for stack"
+	}
+
+	if (n.Op() == ir.ONEW || n.Op() == ir.OPTRLIT) && n.Type().Elem().Width > ir.MaxImplicitStackVarSize {
+		return "too large for stack"
+	}
+
+	if n.Op() == ir.OCLOSURE && typecheck.ClosureType(n.(*ir.ClosureExpr)).Size() > ir.MaxImplicitStackVarSize {
+		return "too large for stack"
+	}
+	if n.Op() == ir.OMETHVALUE && typecheck.MethodValueType(n.(*ir.SelectorExpr)).Size() > ir.MaxImplicitStackVarSize {
+		return "too large for stack"
+	}
+
+	if n.Op() == ir.OMAKESLICE {
+		n := n.(*ir.MakeExpr)
+		r := n.Cap
+		if r == nil {
+			r = n.Len
+		}
+		if !ir.IsSmallIntConst(r) {
+			return "non-constant size"
+		}
+		if t := n.Type(); t.Elem().Width != 0 && ir.Int64Val(r) > ir.MaxImplicitStackVarSize/t.Elem().Width {
+			return "too large for stack"
+		}
+	}
+
+	return ""
+}
diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index 2137f1d1961abf8987383d0cd835459fb37fc2c5..9bf3c7240ac2b1aa2406d10689e313528d6e0b06 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -5,46 +5,16 @@
 package gc
 
 import (
+	"fmt"
+	"go/constant"
+
 	"cmd/compile/internal/base"
-	"cmd/compile/internal/inline"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/internal/bio"
-	"fmt"
-	"go/constant"
 )
 
-func exportf(bout *bio.Writer, format string, args ...interface{}) {
-	fmt.Fprintf(bout, format, args...)
-	if base.Debug.Export != 0 {
-		fmt.Printf(format, args...)
-	}
-}
-
-func dumpexport(bout *bio.Writer) {
-	p := &exporter{marked: make(map[*types.Type]bool)}
-	for _, n := range typecheck.Target.Exports {
-		// Must catch it here rather than Export(), because the type can be
-		// not fully set (still TFORW) when Export() is called.
-		if n.Type() != nil && n.Type().HasTParam() {
-			base.Fatalf("Cannot (yet) export a generic type: %v", n)
-		}
-		p.markObject(n)
-	}
-
-	// The linker also looks for the $$ marker - use char after $$ to distinguish format.
-	exportf(bout, "\n$$B\n") // indicate binary export format
-	off := bout.Offset()
-	typecheck.WriteExports(bout.Writer)
-	size := bout.Offset() - off
-	exportf(bout, "\n$$\n")
-
-	if base.Debug.Export != 0 {
-		fmt.Printf("BenchmarkExportSize:%s 1 %d bytes\n", base.Ctxt.Pkgpath, size)
-	}
-}
-
 func dumpasmhdr() {
 	b, err := bio.Create(base.Flag.AsmHdr)
 	if err != nil {
@@ -79,83 +49,3 @@ func dumpasmhdr() {
 
 	b.Close()
 }
-
-type exporter struct {
-	marked map[*types.Type]bool // types already seen by markType
-}
-
-// markObject visits a reachable object.
-func (p *exporter) markObject(n ir.Node) {
-	if n.Op() == ir.ONAME {
-		n := n.(*ir.Name)
-		if n.Class == ir.PFUNC {
-			inline.Inline_Flood(n, typecheck.Export)
-		}
-	}
-
-	p.markType(n.Type())
-}
-
-// markType recursively visits types reachable from t to identify
-// functions whose inline bodies may be needed.
-func (p *exporter) markType(t *types.Type) {
-	if p.marked[t] {
-		return
-	}
-	p.marked[t] = true
-
-	// If this is a named type, mark all of its associated
-	// methods. Skip interface types because t.Methods contains
-	// only their unexpanded method set (i.e., exclusive of
-	// interface embeddings), and the switch statement below
-	// handles their full method set.
-	if t.Sym() != nil && t.Kind() != types.TINTER {
-		for _, m := range t.Methods().Slice() {
-			if types.IsExported(m.Sym.Name) {
-				p.markObject(ir.AsNode(m.Nname))
-			}
-		}
-	}
-
-	// Recursively mark any types that can be produced given a
-	// value of type t: dereferencing a pointer; indexing or
-	// iterating over an array, slice, or map; receiving from a
-	// channel; accessing a struct field or interface method; or
-	// calling a function.
-	//
-	// Notably, we don't mark function parameter types, because
-	// the user already needs some way to construct values of
-	// those types.
-	switch t.Kind() {
-	case types.TPTR, types.TARRAY, types.TSLICE:
-		p.markType(t.Elem())
-
-	case types.TCHAN:
-		if t.ChanDir().CanRecv() {
-			p.markType(t.Elem())
-		}
-
-	case types.TMAP:
-		p.markType(t.Key())
-		p.markType(t.Elem())
-
-	case types.TSTRUCT:
-		for _, f := range t.FieldSlice() {
-			if types.IsExported(f.Sym.Name) || f.Embedded != 0 {
-				p.markType(f.Type)
-			}
-		}
-
-	case types.TFUNC:
-		for _, f := range t.Results().FieldSlice() {
-			p.markType(f.Type)
-		}
-
-	case types.TINTER:
-		for _, f := range t.AllMethods().Slice() {
-			if types.IsExported(f.Sym.Name) {
-				p.markType(f.Type)
-			}
-		}
-	}
-}
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index ce50cbb4c2e691ed3054d20894fc1bc722623eda..9660ef9dd57c22d18226c299b0a1934ac904a17c 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -32,6 +32,7 @@ import (
 	"log"
 	"os"
 	"runtime"
+	"sort"
 )
 
 func hidePanic() {
@@ -159,9 +160,6 @@ func Main(archInit func(*ssagen.ArchInfo)) {
 		dwarf.EnableLogging(base.Debug.DwarfInl != 0)
 	}
 	if base.Debug.SoftFloat != 0 {
-		if buildcfg.Experiment.RegabiArgs {
-			log.Fatalf("softfloat mode with GOEXPERIMENT=regabiargs not implemented ")
-		}
 		ssagen.Arch.SoftFloat = true
 	}
 
@@ -181,23 +179,41 @@ func Main(archInit func(*ssagen.ArchInfo)) {
 
 	typecheck.Target = new(ir.Package)
 
-	typecheck.NeedITab = func(t, iface *types.Type) { reflectdata.ITabAddr(t, iface) }
 	typecheck.NeedRuntimeType = reflectdata.NeedRuntimeType // TODO(rsc): TypeSym for lock?
 
 	base.AutogeneratedPos = makePos(src.NewFileBase("", ""), 1, 0)
 
 	typecheck.InitUniverse()
+	typecheck.InitRuntime()
 
 	// Parse and typecheck input.
 	noder.LoadPackage(flag.Args())
 
 	dwarfgen.RecordPackageName()
 
+	// Prepare for backend processing. This must happen before pkginit,
+	// because it generates itabs for initializing global variables.
+	ssagen.InitConfig()
+
 	// Build init task.
 	if initTask := pkginit.Task(); initTask != nil {
 		typecheck.Export(initTask)
 	}
 
+	// Stability quirk: sort top-level declarations, so we're not
+	// sensitive to the order that functions are added. In particular,
+	// the order that noder+typecheck add function closures is very
+	// subtle, and not important to reproduce.
+	//
+	// Note: This needs to happen after pkginit.Task, otherwise it risks
+	// changing the order in which top-level variables are initialized.
+	if base.Debug.UnifiedQuirks != 0 {
+		s := typecheck.Target.Decls
+		sort.SliceStable(s, func(i, j int) bool {
+			return s[i].Pos().Before(s[j].Pos())
+		})
+	}
+
 	// Eliminate some obviously dead code.
 	// Must happen after typechecking.
 	for _, n := range typecheck.Target.Decls {
@@ -252,6 +268,11 @@ func Main(archInit func(*ssagen.ArchInfo)) {
 	base.Timer.Start("fe", "escapes")
 	escape.Funcs(typecheck.Target.Decls)
 
+	// TODO(mdempsky): This is a hack. We need a proper, global work
+	// queue for scheduling function compilation so components don't
+	// need to adjust their behavior depending on when they're called.
+	reflectdata.AfterGlobalEscapeAnalysis = true
+
 	// Collect information for go:nowritebarrierrec
 	// checking. This must happen before transforming closures during Walk
 	// We'll do the final check after write barriers are
@@ -260,17 +281,7 @@ func Main(archInit func(*ssagen.ArchInfo)) {
 		ssagen.EnableNoWriteBarrierRecCheck()
 	}
 
-	// Prepare for SSA compilation.
-	// This must be before CompileITabs, because CompileITabs
-	// can trigger function compilation.
-	typecheck.InitRuntime()
-	ssagen.InitConfig()
-
-	// Just before compilation, compile itabs found on
-	// the right side of OCONVIFACE so that methods
-	// can be de-virtualized during compilation.
 	ir.CurFunc = nil
-	reflectdata.CompileITabs()
 
 	// Compile top level functions.
 	// Don't use range--walk can add functions to Target.Decls.
@@ -278,6 +289,10 @@ func Main(archInit func(*ssagen.ArchInfo)) {
 	fcount := int64(0)
 	for i := 0; i < len(typecheck.Target.Decls); i++ {
 		if fn, ok := typecheck.Target.Decls[i].(*ir.Func); ok {
+			// Don't try compiling dead hidden closure.
+			if fn.IsDeadcodeClosure() {
+				continue
+			}
 			enqueueFunc(fn)
 			fcount++
 		}
diff --git a/src/cmd/compile/internal/gc/obj.go b/src/cmd/compile/internal/gc/obj.go
index 474d718525f5b80a3adc9c47c3aad8e879830e48..c86bf5f0847be8df3b9ceeef759fa13239b01a05 100644
--- a/src/cmd/compile/internal/gc/obj.go
+++ b/src/cmd/compile/internal/gc/obj.go
@@ -7,6 +7,7 @@ package gc
 import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
+	"cmd/compile/internal/noder"
 	"cmd/compile/internal/objw"
 	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/staticdata"
@@ -103,7 +104,7 @@ func finishArchiveEntry(bout *bio.Writer, start int64, name string) {
 
 func dumpCompilerObj(bout *bio.Writer) {
 	printObjHeader(bout)
-	dumpexport(bout)
+	noder.WriteExports(bout)
 }
 
 func dumpdata() {
@@ -116,7 +117,7 @@ func dumpdata() {
 	addsignats(typecheck.Target.Externs)
 	reflectdata.WriteRuntimeTypes()
 	reflectdata.WriteTabs()
-	numPTabs, numITabs := reflectdata.CountTabs()
+	numPTabs := reflectdata.CountPTabs()
 	reflectdata.WriteImportStrings()
 	reflectdata.WriteBasicTypes()
 	dumpembeds()
@@ -157,13 +158,10 @@ func dumpdata() {
 	if numExports != len(typecheck.Target.Exports) {
 		base.Fatalf("Target.Exports changed after compile functions loop")
 	}
-	newNumPTabs, newNumITabs := reflectdata.CountTabs()
+	newNumPTabs := reflectdata.CountPTabs()
 	if newNumPTabs != numPTabs {
 		base.Fatalf("ptabs changed after compile functions loop")
 	}
-	if newNumITabs != numITabs {
-		base.Fatalf("itabs changed after compile functions loop")
-	}
 }
 
 func dumpLinkerObj(bout *bio.Writer) {
diff --git a/src/cmd/compile/internal/importer/exportdata.go b/src/cmd/compile/internal/importer/exportdata.go
index 3925a64314ea0d8d160afcc5fbc3719dbae58338..6a672be9c1bac15a5fa4cc89e69b67c21e95f4f1 100644
--- a/src/cmd/compile/internal/importer/exportdata.go
+++ b/src/cmd/compile/internal/importer/exportdata.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
diff --git a/src/cmd/compile/internal/importer/gcimporter.go b/src/cmd/compile/internal/importer/gcimporter.go
index feb18cf2c9ad78c50f2287d723246991e678e8bd..ff40be65bbeceebcbb67d3d07c4b87631ea2c904 100644
--- a/src/cmd/compile/internal/importer/gcimporter.go
+++ b/src/cmd/compile/internal/importer/gcimporter.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -156,7 +155,7 @@ func Import(packages map[string]*types2.Package, path, srcDir string, lookup fun
 		// binary export format starts with a 'c', 'd', or 'v'
 		// (from "version"). Select appropriate importer.
 		if len(data) > 0 && data[0] == 'i' {
-			_, pkg, err = iImportData(packages, data[1:], id)
+			pkg, err = ImportData(packages, string(data[1:]), id)
 		} else {
 			err = fmt.Errorf("import %q: old binary export format no longer supported (recompile library)", path)
 		}
diff --git a/src/cmd/compile/internal/importer/gcimporter_test.go b/src/cmd/compile/internal/importer/gcimporter_test.go
index 7fb8fed59cf9be1cd00471a1d0854e89d4ed1148..44c5e06cd6702306535c2c8c31d15d1fc4d8c71e 100644
--- a/src/cmd/compile/internal/importer/gcimporter_test.go
+++ b/src/cmd/compile/internal/importer/gcimporter_test.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -10,7 +9,6 @@ import (
 	"cmd/compile/internal/types2"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -64,7 +62,7 @@ const maxTime = 30 * time.Second
 
 func testDir(t *testing.T, dir string, endTime time.Time) (nimports int) {
 	dirname := filepath.Join(runtime.GOROOT(), "pkg", runtime.GOOS+"_"+runtime.GOARCH, dir)
-	list, err := ioutil.ReadDir(dirname)
+	list, err := os.ReadDir(dirname)
 	if err != nil {
 		t.Fatalf("testDir(%s): %s", dirname, err)
 	}
@@ -92,7 +90,7 @@ func testDir(t *testing.T, dir string, endTime time.Time) (nimports int) {
 }
 
 func mktmpdir(t *testing.T) string {
-	tmpdir, err := ioutil.TempDir("", "gcimporter_test")
+	tmpdir, err := os.MkdirTemp("", "gcimporter_test")
 	if err != nil {
 		t.Fatal("mktmpdir:", err)
 	}
@@ -142,7 +140,7 @@ func TestVersionHandling(t *testing.T) {
 	}
 
 	const dir = "./testdata/versions"
-	list, err := ioutil.ReadDir(dir)
+	list, err := os.ReadDir(dir)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -195,7 +193,7 @@ func TestVersionHandling(t *testing.T) {
 
 		// create file with corrupted export data
 		// 1) read file
-		data, err := ioutil.ReadFile(filepath.Join(dir, name))
+		data, err := os.ReadFile(filepath.Join(dir, name))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -212,7 +210,7 @@ func TestVersionHandling(t *testing.T) {
 		// 4) write the file
 		pkgpath += "_corrupted"
 		filename := filepath.Join(corruptdir, pkgpath) + ".a"
-		ioutil.WriteFile(filename, data, 0666)
+		os.WriteFile(filename, data, 0666)
 
 		// test that importing the corrupted file results in an error
 		_, err = Import(make(map[string]*types2.Package), pkgpath, corruptdir, nil)
@@ -261,8 +259,7 @@ var importedObjectTests = []struct {
 	{"io.Reader", "type Reader interface{Read(p []byte) (n int, err error)}"},
 	{"io.ReadWriter", "type ReadWriter interface{Reader; Writer}"},
 	{"go/ast.Node", "type Node interface{End() go/token.Pos; Pos() go/token.Pos}"},
-	// go/types.Type has grown much larger - excluded for now
-	// {"go/types.Type", "type Type interface{String() string; Underlying() Type}"},
+	{"go/types.Type", "type Type interface{String() string; Underlying() Type}"},
 }
 
 func TestImportedTypes(t *testing.T) {
@@ -457,17 +454,17 @@ func TestIssue13898(t *testing.T) {
 		t.Fatal("go/types not found")
 	}
 
-	// look for go/types2.Object type
+	// look for go/types.Object type
 	obj := lookupObj(t, goTypesPkg.Scope(), "Object")
 	typ, ok := obj.Type().(*types2.Named)
 	if !ok {
-		t.Fatalf("go/types2.Object type is %v; wanted named type", typ)
+		t.Fatalf("go/types.Object type is %v; wanted named type", typ)
 	}
 
-	// lookup go/types2.Object.Pkg method
+	// lookup go/types.Object.Pkg method
 	m, index, indirect := types2.LookupFieldOrMethod(typ, false, nil, "Pkg")
 	if m == nil {
-		t.Fatalf("go/types2.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
+		t.Fatalf("go/types.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
 	}
 
 	// the method must belong to go/types
diff --git a/src/cmd/compile/internal/importer/iimport.go b/src/cmd/compile/internal/importer/iimport.go
index 8ab0b7b98961fdefe1e4dc605a65a029979c79b1..c303126ea635c9e16a369ac0ebffbb1aae81df07 100644
--- a/src/cmd/compile/internal/importer/iimport.go
+++ b/src/cmd/compile/internal/importer/iimport.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -9,7 +8,6 @@
 package importer
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/types2"
 	"encoding/binary"
@@ -19,10 +17,11 @@ import (
 	"io"
 	"math/big"
 	"sort"
+	"strings"
 )
 
 type intReader struct {
-	*bytes.Reader
+	*strings.Reader
 	path string
 }
 
@@ -42,6 +41,21 @@ func (r *intReader) uint64() uint64 {
 	return i
 }
 
+// Keep this in sync with constants in iexport.go.
+const (
+	iexportVersionGo1_11 = 0
+	iexportVersionPosCol = 1
+	// TODO: before release, change this back to 2.
+	iexportVersionGenerics = iexportVersionPosCol
+
+	iexportVersionCurrent = iexportVersionGenerics
+)
+
+type ident struct {
+	pkg  string
+	name string
+}
+
 const predeclReserved = 32
 
 type itag uint64
@@ -57,6 +71,9 @@ const (
 	signatureType
 	structType
 	interfaceType
+	typeParamType
+	instType
+	unionType
 )
 
 const io_SeekCurrent = 1 // io.SeekCurrent (not defined in Go 1.4)
@@ -65,8 +82,8 @@ const io_SeekCurrent = 1 // io.SeekCurrent (not defined in Go 1.4)
 // and returns the number of bytes consumed and a reference to the package.
 // If the export data version is not recognized or the format is otherwise
 // compromised, an error is returned.
-func iImportData(imports map[string]*types2.Package, data []byte, path string) (_ int, pkg *types2.Package, err error) {
-	const currentVersion = 1
+func ImportData(imports map[string]*types2.Package, data, path string) (pkg *types2.Package, err error) {
+	const currentVersion = iexportVersionCurrent
 	version := int64(-1)
 	defer func() {
 		if e := recover(); e != nil {
@@ -78,13 +95,17 @@ func iImportData(imports map[string]*types2.Package, data []byte, path string) (
 		}
 	}()
 
-	r := &intReader{bytes.NewReader(data), path}
+	r := &intReader{strings.NewReader(data), path}
 
 	version = int64(r.uint64())
 	switch version {
-	case currentVersion, 0:
+	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
 	default:
-		errorf("unknown iexport format version %d", version)
+		if version > iexportVersionGenerics {
+			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
+		} else {
+			errorf("unknown iexport format version %d", version)
+		}
 	}
 
 	sLen := int64(r.uint64())
@@ -96,16 +117,20 @@ func iImportData(imports map[string]*types2.Package, data []byte, path string) (
 	r.Seek(sLen+dLen, io_SeekCurrent)
 
 	p := iimporter{
-		ipath:   path,
-		version: int(version),
+		exportVersion: version,
+		ipath:         path,
+		version:       int(version),
 
-		stringData:  stringData,
-		stringCache: make(map[uint64]string),
-		pkgCache:    make(map[uint64]*types2.Package),
+		stringData:   stringData,
+		pkgCache:     make(map[uint64]*types2.Package),
+		posBaseCache: make(map[uint64]*syntax.PosBase),
 
 		declData: declData,
 		pkgIndex: make(map[*types2.Package]map[string]uint64),
 		typCache: make(map[uint64]types2.Type),
+		// Separate map for typeparams, keyed by their package and unique
+		// name (name with subscript).
+		tparamIndex: make(map[ident]types2.Type),
 	}
 
 	for i, pt := range predeclared {
@@ -117,17 +142,22 @@ func iImportData(imports map[string]*types2.Package, data []byte, path string) (
 		pkgPathOff := r.uint64()
 		pkgPath := p.stringAt(pkgPathOff)
 		pkgName := p.stringAt(r.uint64())
-		_ = r.uint64() // package height; unused by go/types
+		pkgHeight := int(r.uint64())
 
 		if pkgPath == "" {
 			pkgPath = path
 		}
 		pkg := imports[pkgPath]
 		if pkg == nil {
-			pkg = types2.NewPackage(pkgPath, pkgName)
+			pkg = types2.NewPackageHeight(pkgPath, pkgName, pkgHeight)
 			imports[pkgPath] = pkg
-		} else if pkg.Name() != pkgName {
-			errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+		} else {
+			if pkg.Name() != pkgName {
+				errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+			}
+			if pkg.Height() != pkgHeight {
+				errorf("conflicting heights %v and %v for package %q", pkg.Height(), pkgHeight, path)
+			}
 		}
 
 		p.pkgCache[pkgPathOff] = pkg
@@ -153,10 +183,6 @@ func iImportData(imports map[string]*types2.Package, data []byte, path string) (
 		p.doDecl(localpkg, name)
 	}
 
-	for _, typ := range p.interfaceList {
-		typ.Complete()
-	}
-
 	// record all referenced packages as imports
 	list := append(([]*types2.Package)(nil), pkgList[1:]...)
 	sort.Sort(byPath(list))
@@ -165,21 +191,22 @@ func iImportData(imports map[string]*types2.Package, data []byte, path string) (
 	// package was imported completely and without errors
 	localpkg.MarkComplete()
 
-	consumed, _ := r.Seek(0, io_SeekCurrent)
-	return int(consumed), localpkg, nil
+	return localpkg, nil
 }
 
 type iimporter struct {
-	ipath   string
-	version int
+	exportVersion int64
+	ipath         string
+	version       int
 
-	stringData  []byte
-	stringCache map[uint64]string
-	pkgCache    map[uint64]*types2.Package
+	stringData   string
+	pkgCache     map[uint64]*types2.Package
+	posBaseCache map[uint64]*syntax.PosBase
 
-	declData []byte
-	pkgIndex map[*types2.Package]map[string]uint64
-	typCache map[uint64]types2.Type
+	declData    string
+	pkgIndex    map[*types2.Package]map[string]uint64
+	typCache    map[uint64]types2.Type
+	tparamIndex map[ident]types2.Type
 
 	interfaceList []*types2.Interface
 }
@@ -199,24 +226,21 @@ func (p *iimporter) doDecl(pkg *types2.Package, name string) {
 	// Reader.Reset is not available in Go 1.4.
 	// Use bytes.NewReader for now.
 	// r.declReader.Reset(p.declData[off:])
-	r.declReader = *bytes.NewReader(p.declData[off:])
+	r.declReader = *strings.NewReader(p.declData[off:])
 
 	r.obj(name)
 }
 
 func (p *iimporter) stringAt(off uint64) string {
-	if s, ok := p.stringCache[off]; ok {
-		return s
-	}
+	var x [binary.MaxVarintLen64]byte
+	n := copy(x[:], p.stringData[off:])
 
-	slen, n := binary.Uvarint(p.stringData[off:])
+	slen, n := binary.Uvarint(x[:n])
 	if n <= 0 {
 		errorf("varint failed")
 	}
 	spos := off + uint64(n)
-	s := string(p.stringData[spos : spos+slen])
-	p.stringCache[off] = s
-	return s
+	return p.stringData[spos : spos+slen]
 }
 
 func (p *iimporter) pkgAt(off uint64) *types2.Package {
@@ -228,6 +252,16 @@ func (p *iimporter) pkgAt(off uint64) *types2.Package {
 	return nil
 }
 
+func (p *iimporter) posBaseAt(off uint64) *syntax.PosBase {
+	if posBase, ok := p.posBaseCache[off]; ok {
+		return posBase
+	}
+	filename := p.stringAt(off)
+	posBase := syntax.NewTrimmedFileBase(filename, true)
+	p.posBaseCache[off] = posBase
+	return posBase
+}
+
 func (p *iimporter) typAt(off uint64, base *types2.Named) types2.Type {
 	if t, ok := p.typCache[off]; ok && (base == nil || !isInterface(t)) {
 		return t
@@ -241,7 +275,7 @@ func (p *iimporter) typAt(off uint64, base *types2.Named) types2.Type {
 	// Reader.Reset is not available in Go 1.4.
 	// Use bytes.NewReader for now.
 	// r.declReader.Reset(p.declData[off-predeclReserved:])
-	r.declReader = *bytes.NewReader(p.declData[off-predeclReserved:])
+	r.declReader = *strings.NewReader(p.declData[off-predeclReserved:])
 	t := r.doType(base)
 
 	if base == nil || !isInterface(t) {
@@ -251,12 +285,12 @@ func (p *iimporter) typAt(off uint64, base *types2.Named) types2.Type {
 }
 
 type importReader struct {
-	p          *iimporter
-	declReader bytes.Reader
-	currPkg    *types2.Package
-	prevFile   string
-	prevLine   int64
-	prevColumn int64
+	p           *iimporter
+	declReader  strings.Reader
+	currPkg     *types2.Package
+	prevPosBase *syntax.PosBase
+	prevLine    int64
+	prevColumn  int64
 }
 
 func (r *importReader) obj(name string) {
@@ -274,16 +308,28 @@ func (r *importReader) obj(name string) {
 
 		r.declare(types2.NewConst(pos, r.currPkg, name, typ, val))
 
-	case 'F':
+	case 'F', 'G':
+		var tparams []*types2.TypeParam
+		if tag == 'G' {
+			tparams = r.tparamList()
+		}
 		sig := r.signature(nil)
-
+		sig.SetTParams(tparams)
 		r.declare(types2.NewFunc(pos, r.currPkg, name, sig))
 
-	case 'T':
+	case 'T', 'U':
+		var tparams []*types2.TypeParam
+		if tag == 'U' {
+			tparams = r.tparamList()
+		}
+
 		// Types can be recursive. We need to setup a stub
 		// declaration before recursing.
 		obj := types2.NewTypeName(pos, r.currPkg, name, nil)
 		named := types2.NewNamed(obj, nil, nil)
+		if tag == 'U' {
+			named.SetTParams(tparams)
+		}
 		r.declare(obj)
 
 		underlying := r.p.typAt(r.uint64(), named).Underlying()
@@ -296,10 +342,43 @@ func (r *importReader) obj(name string) {
 				recv := r.param()
 				msig := r.signature(recv)
 
+				// If the receiver has any targs, set those as the
+				// rparams of the method (since those are the
+				// typeparams being used in the method sig/body).
+				targs := baseType(msig.Recv().Type()).TArgs()
+				if targs.Len() > 0 {
+					rparams := make([]*types2.TypeParam, targs.Len())
+					for i := range rparams {
+						rparams[i] = types2.AsTypeParam(targs.At(i))
+					}
+					msig.SetRParams(rparams)
+				}
+
 				named.AddMethod(types2.NewFunc(mpos, r.currPkg, mname, msig))
 			}
 		}
 
+	case 'P':
+		// We need to "declare" a typeparam in order to have a name that
+		// can be referenced recursively (if needed) in the type param's
+		// bound.
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected type param type")
+		}
+		name0, sub := parseSubscript(name)
+		tn := types2.NewTypeName(pos, r.currPkg, name0, nil)
+		t := (*types2.Checker)(nil).NewTypeParam(tn, nil)
+		if sub == 0 {
+			errorf("missing subscript")
+		}
+		t.SetId(sub)
+		// To handle recursive references to the typeparam within its
+		// bound, save the partial type in tparamIndex before reading the bounds.
+		id := ident{r.currPkg.Name(), name}
+		r.p.tparamIndex[id] = t
+
+		t.SetConstraint(r.typ())
+
 	case 'V':
 		typ := r.typ()
 
@@ -439,12 +518,11 @@ func (r *importReader) pos() syntax.Pos {
 		r.posv0()
 	}
 
-	if r.prevFile == "" && r.prevLine == 0 && r.prevColumn == 0 {
+	if (r.prevPosBase == nil || r.prevPosBase.Filename() == "") && r.prevLine == 0 && r.prevColumn == 0 {
 		return syntax.Pos{}
 	}
-	// TODO(gri) fix this
-	// return r.p.fake.pos(r.prevFile, int(r.prevLine), int(r.prevColumn))
-	return syntax.Pos{}
+
+	return syntax.MakePos(r.prevPosBase, uint(r.prevLine), uint(r.prevColumn))
 }
 
 func (r *importReader) posv0() {
@@ -454,7 +532,7 @@ func (r *importReader) posv0() {
 	} else if l := r.int64(); l == -1 {
 		r.prevLine += deltaNewFile
 	} else {
-		r.prevFile = r.string()
+		r.prevPosBase = r.posBase()
 		r.prevLine = l
 	}
 }
@@ -466,7 +544,7 @@ func (r *importReader) posv1() {
 		delta = r.int64()
 		r.prevLine += delta >> 1
 		if delta&1 != 0 {
-			r.prevFile = r.string()
+			r.prevPosBase = r.posBase()
 		}
 	}
 }
@@ -480,8 +558,9 @@ func isInterface(t types2.Type) bool {
 	return ok
 }
 
-func (r *importReader) pkg() *types2.Package { return r.p.pkgAt(r.uint64()) }
-func (r *importReader) string() string       { return r.p.stringAt(r.uint64()) }
+func (r *importReader) pkg() *types2.Package     { return r.p.pkgAt(r.uint64()) }
+func (r *importReader) string() string           { return r.p.stringAt(r.uint64()) }
+func (r *importReader) posBase() *syntax.PosBase { return r.p.posBaseAt(r.uint64()) }
 
 func (r *importReader) doType(base *types2.Named) types2.Type {
 	switch k := r.kind(); k {
@@ -554,6 +633,49 @@ func (r *importReader) doType(base *types2.Named) types2.Type {
 		typ := types2.NewInterfaceType(methods, embeddeds)
 		r.p.interfaceList = append(r.p.interfaceList, typ)
 		return typ
+
+	case typeParamType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected type param type")
+		}
+		pkg, name := r.qualifiedIdent()
+		id := ident{pkg.Name(), name}
+		if t, ok := r.p.tparamIndex[id]; ok {
+			// We're already in the process of importing this typeparam.
+			return t
+		}
+		// Otherwise, import the definition of the typeparam now.
+		r.p.doDecl(pkg, name)
+		return r.p.tparamIndex[id]
+
+	case instType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected instantiation type")
+		}
+		// pos does not matter for instances: they are positioned on the original
+		// type.
+		_ = r.pos()
+		len := r.uint64()
+		targs := make([]types2.Type, len)
+		for i := range targs {
+			targs[i] = r.typ()
+		}
+		baseType := r.typ()
+		// The imported instantiated type doesn't include any methods, so
+		// we must always use the methods of the base (orig) type.
+		// TODO provide a non-nil *Checker
+		t, _ := types2.Instantiate(nil, baseType, targs, false)
+		return t
+
+	case unionType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected instantiation type")
+		}
+		terms := make([]*types2.Term, r.uint64())
+		for i := range terms {
+			terms[i] = types2.NewTerm(r.bool(), r.typ())
+		}
+		return types2.NewUnion(terms)
 	}
 }
 
@@ -568,6 +690,19 @@ func (r *importReader) signature(recv *types2.Var) *types2.Signature {
 	return types2.NewSignature(recv, params, results, variadic)
 }
 
+func (r *importReader) tparamList() []*types2.TypeParam {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	xs := make([]*types2.TypeParam, n)
+	for i := range xs {
+		typ := r.typ()
+		xs[i] = types2.AsTypeParam(typ)
+	}
+	return xs
+}
+
 func (r *importReader) paramList() *types2.Tuple {
 	xs := make([]*types2.Var, r.uint64())
 	for i := range xs {
@@ -610,3 +745,33 @@ func (r *importReader) byte() byte {
 	}
 	return x
 }
+
+func baseType(typ types2.Type) *types2.Named {
+	// pointer receivers are never types2.Named types
+	if p, _ := typ.(*types2.Pointer); p != nil {
+		typ = p.Elem()
+	}
+	// receiver base types are always (possibly generic) types2.Named types
+	n, _ := typ.(*types2.Named)
+	return n
+}
+
+func parseSubscript(name string) (string, uint64) {
+	// Extract the subscript value from the type param name. We export
+	// and import the subscript value, so that all type params have
+	// unique names.
+	sub := uint64(0)
+	startsub := -1
+	for i, r := range name {
+		if '₀' <= r && r < '₀'+10 {
+			if startsub == -1 {
+				startsub = i
+			}
+			sub = sub*10 + uint64(r-'₀')
+		}
+	}
+	if startsub >= 0 {
+		name = name[:startsub]
+	}
+	return name, sub
+}
diff --git a/src/cmd/compile/internal/importer/support.go b/src/cmd/compile/internal/importer/support.go
index 40b9c7c9583fbff277c7d5a2237bdc82596384de..6ceb413601f0e83abd87cf42619b4b4104b87781 100644
--- a/src/cmd/compile/internal/importer/support.go
+++ b/src/cmd/compile/internal/importer/support.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -120,6 +119,9 @@ var predeclared = []types2.Type{
 
 	// used internally by gc; never used by this package or in .a files
 	anyType{},
+
+	// comparable
+	types2.Universe.Lookup("comparable").Type(),
 }
 
 type anyType struct{}
diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index d6b4ced4e157cd46a2dbbcc814635453f32e198e..45a533fcafc3dfd70baf0e04c75f50fe2e6f1083 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -179,6 +179,8 @@ func CanInline(fn *ir.Func) {
 		Cost: inlineMaxBudget - visitor.budget,
 		Dcl:  pruneUnusedAutos(n.Defn.(*ir.Func).Dcl, &visitor),
 		Body: inlcopylist(fn.Body),
+
+		CanDelayResults: canDelayResults(fn),
 	}
 
 	if base.Flag.LowerM > 1 {
@@ -191,60 +193,36 @@ func CanInline(fn *ir.Func) {
 	}
 }
 
-// Inline_Flood marks n's inline body for export and recursively ensures
-// all called functions are marked too.
-func Inline_Flood(n *ir.Name, exportsym func(*ir.Name)) {
-	if n == nil {
-		return
-	}
-	if n.Op() != ir.ONAME || n.Class != ir.PFUNC {
-		base.Fatalf("Inline_Flood: unexpected %v, %v, %v", n, n.Op(), n.Class)
-	}
-	fn := n.Func
-	if fn == nil {
-		base.Fatalf("Inline_Flood: missing Func on %v", n)
-	}
-	if fn.Inl == nil {
-		return
-	}
-
-	if fn.ExportInline() {
-		return
-	}
-	fn.SetExportInline(true)
-
-	typecheck.ImportedBody(fn)
-
-	var doFlood func(n ir.Node)
-	doFlood = func(n ir.Node) {
-		switch n.Op() {
-		case ir.OMETHEXPR, ir.ODOTMETH:
-			Inline_Flood(ir.MethodExprName(n), exportsym)
+// canDelayResults reports whether inlined calls to fn can delay
+// declaring the result parameter until the "return" statement.
+func canDelayResults(fn *ir.Func) bool {
+	// We can delay declaring+initializing result parameters if:
+	// (1) there's exactly one "return" statement in the inlined function;
+	// (2) it's not an empty return statement (#44355); and
+	// (3) the result parameters aren't named.
 
-		case ir.ONAME:
-			n := n.(*ir.Name)
-			switch n.Class {
-			case ir.PFUNC:
-				Inline_Flood(n, exportsym)
-				exportsym(n)
-			case ir.PEXTERN:
-				exportsym(n)
+	nreturns := 0
+	ir.VisitList(fn.Body, func(n ir.Node) {
+		if n, ok := n.(*ir.ReturnStmt); ok {
+			nreturns++
+			if len(n.Results) == 0 {
+				nreturns++ // empty return statement (case 2)
 			}
+		}
+	})
 
-		case ir.OCALLPART:
-			// Okay, because we don't yet inline indirect
-			// calls to method values.
-		case ir.OCLOSURE:
-			// VisitList doesn't visit closure bodies, so force a
-			// recursive call to VisitList on the body of the closure.
-			ir.VisitList(n.(*ir.ClosureExpr).Func.Body, doFlood)
+	if nreturns != 1 {
+		return false // not exactly one return statement (case 1)
+	}
+
+	// temporaries for return values.
+	for _, param := range fn.Type().Results().FieldSlice() {
+		if sym := types.OrigSym(param.Sym); sym != nil && !sym.IsBlank() {
+			return false // found a named result parameter (case 3)
 		}
 	}
 
-	// Recursively identify all referenced functions for
-	// reexport. We want to include even non-called functions,
-	// because after inlining they might be callable.
-	ir.VisitList(ir.Nodes(fn.Inl.Body), doFlood)
+	return true
 }
 
 // hairyVisitor visits a function body to determine its inlining
@@ -295,6 +273,19 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
 				}
 			}
 		}
+		if n.X.Op() == ir.OMETHEXPR {
+			if meth := ir.MethodExprName(n.X); meth != nil {
+				fn := meth.Func
+				if fn != nil && types.IsRuntimePkg(fn.Sym().Pkg) && fn.Sym().Name == "heapBits.nextArena" {
+					// Special case: explicitly allow
+					// mid-stack inlining of
+					// runtime.heapBits.next even though
+					// it calls slow-path
+					// runtime.heapBits.nextArena.
+					break
+				}
+			}
+		}
 
 		if ir.IsIntrinsicCall(n) {
 			// Treat like any other node.
@@ -309,28 +300,8 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
 		// Call cost for non-leaf inlining.
 		v.budget -= v.extraCallCost
 
-	// Call is okay if inlinable and we have the budget for the body.
 	case ir.OCALLMETH:
-		n := n.(*ir.CallExpr)
-		t := n.X.Type()
-		if t == nil {
-			base.Fatalf("no function type for [%p] %+v\n", n.X, n.X)
-		}
-		fn := ir.MethodExprName(n.X).Func
-		if types.IsRuntimePkg(fn.Sym().Pkg) && fn.Sym().Name == "heapBits.nextArena" {
-			// Special case: explicitly allow
-			// mid-stack inlining of
-			// runtime.heapBits.next even though
-			// it calls slow-path
-			// runtime.heapBits.nextArena.
-			break
-		}
-		if fn.Inl != nil {
-			v.budget -= fn.Inl.Cost
-			break
-		}
-		// Call cost for non-leaf inlining.
-		v.budget -= v.extraCallCost
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
 
 	// Things that are too hairy, irrespective of the budget
 	case ir.OCALL, ir.OCALLINTER:
@@ -445,7 +416,7 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
 		// and don't charge for the OBLOCK itself. The ++ undoes the -- below.
 		v.budget++
 
-	case ir.OCALLPART, ir.OSLICELIT:
+	case ir.OMETHVALUE, ir.OSLICELIT:
 		v.budget-- // Hack for toolstash -cmp.
 
 	case ir.OMETHEXPR:
@@ -499,9 +470,6 @@ func inlcopy(n ir.Node) ir.Node {
 			// x.Func.Body for iexport and local inlining.
 			oldfn := x.Func
 			newfn := ir.NewFunc(oldfn.Pos())
-			if oldfn.ClosureCalled() {
-				newfn.SetClosureCalled(true)
-			}
 			m.(*ir.ClosureExpr).Func = newfn
 			newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), oldfn.Nname.Sym())
 			// XXX OK to share fn.Type() ??
@@ -544,37 +512,6 @@ func InlineCalls(fn *ir.Func) {
 	ir.CurFunc = savefn
 }
 
-// Turn an OINLCALL into a statement.
-func inlconv2stmt(inlcall *ir.InlinedCallExpr) ir.Node {
-	n := ir.NewBlockStmt(inlcall.Pos(), nil)
-	n.List = inlcall.Init()
-	n.List.Append(inlcall.Body.Take()...)
-	return n
-}
-
-// Turn an OINLCALL into a single valued expression.
-// The result of inlconv2expr MUST be assigned back to n, e.g.
-// 	n.Left = inlconv2expr(n.Left)
-func inlconv2expr(n *ir.InlinedCallExpr) ir.Node {
-	r := n.ReturnVars[0]
-	return ir.InitExpr(append(n.Init(), n.Body...), r)
-}
-
-// Turn the rlist (with the return values) of the OINLCALL in
-// n into an expression list lumping the ninit and body
-// containing the inlined statements on the first list element so
-// order will be preserved. Used in return, oas2func and call
-// statements.
-func inlconv2list(n *ir.InlinedCallExpr) []ir.Node {
-	if n.Op() != ir.OINLCALL || len(n.ReturnVars) == 0 {
-		base.Fatalf("inlconv2list %+v\n", n)
-	}
-
-	s := n.ReturnVars
-	s[0] = ir.InitExpr(append(n.Init(), n.Body...), s[0])
-	return s
-}
-
 // inlnode recurses over the tree to find inlineable calls, which will
 // be turned into OINLCALLs by mkinlcall. When the recursion comes
 // back up will examine left, right, list, rlist, ninit, ntest, nincr,
@@ -597,7 +534,9 @@ func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.No
 	case ir.ODEFER, ir.OGO:
 		n := n.(*ir.GoDeferStmt)
 		switch call := n.Call; call.Op() {
-		case ir.OCALLFUNC, ir.OCALLMETH:
+		case ir.OCALLMETH:
+			base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+		case ir.OCALLFUNC:
 			call := call.(*ir.CallExpr)
 			call.NoInline = true
 		}
@@ -607,11 +546,18 @@ func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.No
 	case ir.OCLOSURE:
 		return n
 	case ir.OCALLMETH:
-		// Prevent inlining some reflect.Value methods when using checkptr,
-		// even when package reflect was compiled without it (#35073).
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+	case ir.OCALLFUNC:
 		n := n.(*ir.CallExpr)
-		if s := ir.MethodExprName(n.X).Sym(); base.Debug.Checkptr != 0 && types.IsReflectPkg(s.Pkg) && (s.Name == "Value.UnsafeAddr" || s.Name == "Value.Pointer") {
-			return n
+		if n.X.Op() == ir.OMETHEXPR {
+			// Prevent inlining some reflect.Value methods when using checkptr,
+			// even when package reflect was compiled without it (#35073).
+			if meth := ir.MethodExprName(n.X); meth != nil {
+				s := meth.Sym()
+				if base.Debug.Checkptr != 0 && types.IsReflectPkg(s.Pkg) && (s.Name == "Value.UnsafeAddr" || s.Name == "Value.Pointer") {
+					return n
+				}
+			}
 		}
 	}
 
@@ -619,31 +565,18 @@ func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.No
 
 	ir.EditChildren(n, edit)
 
-	if as := n; as.Op() == ir.OAS2FUNC {
-		as := as.(*ir.AssignListStmt)
-		if as.Rhs[0].Op() == ir.OINLCALL {
-			as.Rhs = inlconv2list(as.Rhs[0].(*ir.InlinedCallExpr))
-			as.SetOp(ir.OAS2)
-			as.SetTypecheck(0)
-			n = typecheck.Stmt(as)
-		}
-	}
-
 	// with all the branches out of the way, it is now time to
 	// transmogrify this node itself unless inhibited by the
 	// switch at the top of this function.
 	switch n.Op() {
-	case ir.OCALLFUNC, ir.OCALLMETH:
-		n := n.(*ir.CallExpr)
-		if n.NoInline {
-			return n
-		}
-	}
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
 
-	var call *ir.CallExpr
-	switch n.Op() {
 	case ir.OCALLFUNC:
-		call = n.(*ir.CallExpr)
+		call := n.(*ir.CallExpr)
+		if call.NoInline {
+			break
+		}
 		if base.Flag.LowerM > 3 {
 			fmt.Printf("%v:call to func %+v\n", ir.Line(n), call.X)
 		}
@@ -653,38 +586,10 @@ func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.No
 		if fn := inlCallee(call.X); fn != nil && fn.Inl != nil {
 			n = mkinlcall(call, fn, maxCost, inlMap, edit)
 		}
-
-	case ir.OCALLMETH:
-		call = n.(*ir.CallExpr)
-		if base.Flag.LowerM > 3 {
-			fmt.Printf("%v:call to meth %v\n", ir.Line(n), call.X.(*ir.SelectorExpr).Sel)
-		}
-
-		// typecheck should have resolved ODOTMETH->type, whose nname points to the actual function.
-		if call.X.Type() == nil {
-			base.Fatalf("no function type for [%p] %+v\n", call.X, call.X)
-		}
-
-		n = mkinlcall(call, ir.MethodExprName(call.X).Func, maxCost, inlMap, edit)
 	}
 
 	base.Pos = lno
 
-	if n.Op() == ir.OINLCALL {
-		ic := n.(*ir.InlinedCallExpr)
-		switch call.Use {
-		default:
-			ir.Dump("call", call)
-			base.Fatalf("call missing use")
-		case ir.CallUseExpr:
-			n = inlconv2expr(ic)
-		case ir.CallUseStmt:
-			n = inlconv2stmt(ic)
-		case ir.CallUseList:
-			// leave for caller to convert
-		}
-	}
-
 	return n
 }
 
@@ -740,7 +645,12 @@ var inlgen int
 // when producing output for debugging the compiler itself.
 var SSADumpInline = func(*ir.Func) {}
 
-// If n is a call node (OCALLFUNC or OCALLMETH), and fn is an ONAME node for a
+// NewInline allows the inliner implementation to be overridden.
+// If it returns nil, the legacy inliner will handle this call
+// instead.
+var NewInline = func(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr { return nil }
+
+// If n is a OCALLFUNC node, and fn is an ONAME node for a
 // function with an inlinable body, return an OINLCALL node that can replace n.
 // The returned node's Ninit has the parameter assignments, the Nbody is the
 // inlined function body, and (List, Rlist) contain the (input, output)
@@ -793,38 +703,90 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	defer func() {
 		inlMap[fn] = false
 	}()
-	if base.Debug.TypecheckInl == 0 {
-		typecheck.ImportedBody(fn)
+
+	typecheck.FixVariadicCall(n)
+
+	parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
+
+	sym := fn.Linksym()
+	inlIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
+
+	if base.Flag.GenDwarfInl > 0 {
+		if !sym.WasInlined() {
+			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
+			sym.Set(obj.AttrWasInlined, true)
+		}
 	}
 
-	// We have a function node, and it has an inlineable body.
-	if base.Flag.LowerM > 1 {
-		fmt.Printf("%v: inlining call to %v %v { %v }\n", ir.Line(n), fn.Sym(), fn.Type(), ir.Nodes(fn.Inl.Body))
-	} else if base.Flag.LowerM != 0 {
+	if base.Flag.LowerM != 0 {
 		fmt.Printf("%v: inlining call to %v\n", ir.Line(n), fn)
 	}
 	if base.Flag.LowerM > 2 {
 		fmt.Printf("%v: Before inlining: %+v\n", ir.Line(n), n)
 	}
 
-	SSADumpInline(fn)
+	res := NewInline(n, fn, inlIndex)
+	if res == nil {
+		res = oldInline(n, fn, inlIndex)
+	}
+
+	// transitive inlining
+	// might be nice to do this before exporting the body,
+	// but can't emit the body with inlining expanded.
+	// instead we emit the things that the body needs
+	// and each use must redo the inlining.
+	// luckily these are small.
+	ir.EditChildren(res, edit)
 
-	ninit := n.Init()
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(res), res)
+	}
 
-	// For normal function calls, the function callee expression
-	// may contain side effects (e.g., added by addinit during
-	// inlconv2expr or inlconv2list). Make sure to preserve these,
-	// if necessary (#42703).
-	if n.Op() == ir.OCALLFUNC {
-		callee := n.X
-		for callee.Op() == ir.OCONVNOP {
+	return res
+}
+
+// CalleeEffects appends any side effects from evaluating callee to init.
+func CalleeEffects(init *ir.Nodes, callee ir.Node) {
+	for {
+		switch callee.Op() {
+		case ir.ONAME, ir.OCLOSURE, ir.OMETHEXPR:
+			return // done
+
+		case ir.OCONVNOP:
 			conv := callee.(*ir.ConvExpr)
-			ninit.Append(ir.TakeInit(conv)...)
+			init.Append(ir.TakeInit(conv)...)
 			callee = conv.X
+
+		case ir.OINLCALL:
+			ic := callee.(*ir.InlinedCallExpr)
+			init.Append(ir.TakeInit(ic)...)
+			init.Append(ic.Body.Take()...)
+			callee = ic.SingleResult()
+
+		default:
+			base.FatalfAt(callee.Pos(), "unexpected callee expression: %v", callee)
 		}
-		if callee.Op() != ir.ONAME && callee.Op() != ir.OCLOSURE && callee.Op() != ir.OMETHEXPR {
-			base.Fatalf("unexpected callee expression: %v", callee)
-		}
+	}
+}
+
+// oldInline creates an InlinedCallExpr to replace the given call
+// expression. fn is the callee function to be inlined. inlIndex is
+// the inlining tree position index, for use with src.NewInliningBase
+// when rewriting positions.
+func oldInline(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	if base.Debug.TypecheckInl == 0 {
+		typecheck.ImportedBody(fn)
+	}
+
+	SSADumpInline(fn)
+
+	ninit := call.Init()
+
+	// For normal function calls, the function callee expression
+	// may contain side effects. Make sure to preserve these,
+	// if necessary (#42703).
+	if call.Op() == ir.OCALLFUNC {
+		CalleeEffects(&ninit, call.X)
 	}
 
 	// Make temp names to use instead of the originals.
@@ -854,25 +816,6 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	}
 
 	// We can delay declaring+initializing result parameters if:
-	// (1) there's exactly one "return" statement in the inlined function;
-	// (2) it's not an empty return statement (#44355); and
-	// (3) the result parameters aren't named.
-	delayretvars := true
-
-	nreturns := 0
-	ir.VisitList(ir.Nodes(fn.Inl.Body), func(n ir.Node) {
-		if n, ok := n.(*ir.ReturnStmt); ok {
-			nreturns++
-			if len(n.Results) == 0 {
-				delayretvars = false // empty return statement (case 2)
-			}
-		}
-	})
-
-	if nreturns != 1 {
-		delayretvars = false // not exactly one return statement (case 1)
-	}
-
 	// temporaries for return values.
 	var retvars []ir.Node
 	for i, t := range fn.Type().Results().Fields().Slice() {
@@ -882,7 +825,6 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 			m = inlvar(n)
 			m = typecheck.Expr(m).(*ir.Name)
 			inlvars[n] = m
-			delayretvars = false // found a named result parameter (case 3)
 		} else {
 			// anonymous return values, synthesize names for use in assignment that replaces return
 			m = retvar(t, i)
@@ -905,61 +847,23 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	// Assign arguments to the parameters' temp names.
 	as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
 	as.Def = true
-	if n.Op() == ir.OCALLMETH {
-		sel := n.X.(*ir.SelectorExpr)
-		if sel.X == nil {
-			base.Fatalf("method call without receiver: %+v", n)
-		}
-		as.Rhs.Append(sel.X)
+	if call.Op() == ir.OCALLMETH {
+		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
 	}
-	as.Rhs.Append(n.Args...)
-
-	// For non-dotted calls to variadic functions, we assign the
-	// variadic parameter's temp name separately.
-	var vas *ir.AssignStmt
+	as.Rhs.Append(call.Args...)
 
 	if recv := fn.Type().Recv(); recv != nil {
 		as.Lhs.Append(inlParam(recv, as, inlvars))
 	}
 	for _, param := range fn.Type().Params().Fields().Slice() {
-		// For ordinary parameters or variadic parameters in
-		// dotted calls, just add the variable to the
-		// assignment list, and we're done.
-		if !param.IsDDD() || n.IsDDD {
-			as.Lhs.Append(inlParam(param, as, inlvars))
-			continue
-		}
-
-		// Otherwise, we need to collect the remaining values
-		// to pass as a slice.
-
-		x := len(as.Lhs)
-		for len(as.Lhs) < len(as.Rhs) {
-			as.Lhs.Append(argvar(param.Type, len(as.Lhs)))
-		}
-		varargs := as.Lhs[x:]
-
-		vas = ir.NewAssignStmt(base.Pos, nil, nil)
-		vas.X = inlParam(param, vas, inlvars)
-		if len(varargs) == 0 {
-			vas.Y = typecheck.NodNil()
-			vas.Y.SetType(param.Type)
-		} else {
-			lit := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(param.Type), nil)
-			lit.List = varargs
-			vas.Y = lit
-		}
+		as.Lhs.Append(inlParam(param, as, inlvars))
 	}
 
 	if len(as.Rhs) != 0 {
 		ninit.Append(typecheck.Stmt(as))
 	}
 
-	if vas != nil {
-		ninit.Append(typecheck.Stmt(vas))
-	}
-
-	if !delayretvars {
+	if !fn.Inl.CanDelayResults {
 		// Zero the return parameters.
 		for _, n := range retvars {
 			ninit.Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
@@ -972,40 +876,21 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 
 	inlgen++
 
-	parent := -1
-	if b := base.Ctxt.PosTable.Pos(n.Pos()).Base(); b != nil {
-		parent = b.InliningIndex()
-	}
-
-	sym := fn.Linksym()
-	newIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
-
 	// Add an inline mark just before the inlined body.
 	// This mark is inline in the code so that it's a reasonable spot
 	// to put a breakpoint. Not sure if that's really necessary or not
 	// (in which case it could go at the end of the function instead).
 	// Note issue 28603.
-	inlMark := ir.NewInlineMarkStmt(base.Pos, types.BADWIDTH)
-	inlMark.SetPos(n.Pos().WithIsStmt())
-	inlMark.Index = int64(newIndex)
-	ninit.Append(inlMark)
-
-	if base.Flag.GenDwarfInl > 0 {
-		if !sym.WasInlined() {
-			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
-			sym.Set(obj.AttrWasInlined, true)
-		}
-	}
+	ninit.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(inlIndex)))
 
 	subst := inlsubst{
-		retlabel:     retlabel,
-		retvars:      retvars,
-		delayretvars: delayretvars,
-		inlvars:      inlvars,
-		defnMarker:   ir.NilExpr{},
-		bases:        make(map[*src.PosBase]*src.PosBase),
-		newInlIndex:  newIndex,
-		fn:           fn,
+		retlabel:    retlabel,
+		retvars:     retvars,
+		inlvars:     inlvars,
+		defnMarker:  ir.NilExpr{},
+		bases:       make(map[*src.PosBase]*src.PosBase),
+		newInlIndex: inlIndex,
+		fn:          fn,
 	}
 	subst.edit = subst.node
 
@@ -1026,26 +911,11 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 
 	//dumplist("ninit post", ninit);
 
-	call := ir.NewInlinedCallExpr(base.Pos, nil, nil)
-	*call.PtrInit() = ninit
-	call.Body = body
-	call.ReturnVars = retvars
-	call.SetType(n.Type())
-	call.SetTypecheck(1)
-
-	// transitive inlining
-	// might be nice to do this before exporting the body,
-	// but can't emit the body with inlining expanded.
-	// instead we emit the things that the body needs
-	// and each use must redo the inlining.
-	// luckily these are small.
-	ir.EditChildren(call, edit)
-
-	if base.Flag.LowerM > 2 {
-		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(call), call)
-	}
-
-	return call
+	res := ir.NewInlinedCallExpr(base.Pos, body, retvars)
+	res.SetInit(ninit)
+	res.SetType(call.Type())
+	res.SetTypecheck(1)
+	return res
 }
 
 // Every time we expand a function we generate a new set of tmpnames,
@@ -1058,8 +928,10 @@ func inlvar(var_ *ir.Name) *ir.Name {
 
 	n := typecheck.NewName(var_.Sym())
 	n.SetType(var_.Type())
+	n.SetTypecheck(1)
 	n.Class = ir.PAUTO
 	n.SetUsed(true)
+	n.SetAutoTemp(var_.AutoTemp())
 	n.Curfn = ir.CurFunc // the calling function, not the called one
 	n.SetAddrtaken(var_.Addrtaken())
 
@@ -1071,18 +943,7 @@ func inlvar(var_ *ir.Name) *ir.Name {
 func retvar(t *types.Field, i int) *ir.Name {
 	n := typecheck.NewName(typecheck.LookupNum("~R", i))
 	n.SetType(t.Type)
-	n.Class = ir.PAUTO
-	n.SetUsed(true)
-	n.Curfn = ir.CurFunc // the calling function, not the called one
-	ir.CurFunc.Dcl = append(ir.CurFunc.Dcl, n)
-	return n
-}
-
-// Synthesize a variable to store the inlined function's arguments
-// when they come from a multiple return call.
-func argvar(t *types.Type, i int) ir.Node {
-	n := typecheck.NewName(typecheck.LookupNum("~arg", i))
-	n.SetType(t.Elem())
+	n.SetTypecheck(1)
 	n.Class = ir.PAUTO
 	n.SetUsed(true)
 	n.Curfn = ir.CurFunc // the calling function, not the called one
@@ -1099,10 +960,6 @@ type inlsubst struct {
 	// Temporary result variables.
 	retvars []ir.Node
 
-	// Whether result variables should be initialized at the
-	// "return" statement.
-	delayretvars bool
-
 	inlvars map[*ir.Name]*ir.Name
 	// defnMarker is used to mark a Node for reassignment.
 	// inlsubst.clovar set this during creating new ONAME.
@@ -1157,17 +1014,21 @@ func (subst *inlsubst) fields(oldt *types.Type) []*types.Field {
 // clovar creates a new ONAME node for a local variable or param of a closure
 // inside a function being inlined.
 func (subst *inlsubst) clovar(n *ir.Name) *ir.Name {
-	// TODO(danscales): want to get rid of this shallow copy, with code like the
-	// following, but it is hard to copy all the necessary flags in a maintainable way.
-	// m := ir.NewNameAt(n.Pos(), n.Sym())
-	// m.Class = n.Class
-	// m.SetType(n.Type())
-	// m.SetTypecheck(1)
-	//if n.IsClosureVar() {
-	//	m.SetIsClosureVar(true)
-	//}
-	m := &ir.Name{}
-	*m = *n
+	m := ir.NewNameAt(n.Pos(), n.Sym())
+	m.Class = n.Class
+	m.SetType(n.Type())
+	m.SetTypecheck(1)
+	if n.IsClosureVar() {
+		m.SetIsClosureVar(true)
+	}
+	if n.Addrtaken() {
+		m.SetAddrtaken(true)
+	}
+	if n.Used() {
+		m.SetUsed(true)
+	}
+	m.Defn = n.Defn
+
 	m.Curfn = subst.newclofn
 
 	switch defn := n.Defn.(type) {
@@ -1222,8 +1083,6 @@ func (subst *inlsubst) clovar(n *ir.Name) *ir.Name {
 // closure does the necessary substitions for a ClosureExpr n and returns the new
 // closure node.
 func (subst *inlsubst) closure(n *ir.ClosureExpr) ir.Node {
-	m := ir.Copy(n)
-
 	// Prior to the subst edit, set a flag in the inlsubst to
 	// indicated that we don't want to update the source positions in
 	// the new closure. If we do this, it will appear that the closure
@@ -1231,29 +1090,16 @@ func (subst *inlsubst) closure(n *ir.ClosureExpr) ir.Node {
 	// issue #46234 for more details.
 	defer func(prev bool) { subst.noPosUpdate = prev }(subst.noPosUpdate)
 	subst.noPosUpdate = true
-	ir.EditChildren(m, subst.edit)
 
 	//fmt.Printf("Inlining func %v with closure into %v\n", subst.fn, ir.FuncName(ir.CurFunc))
 
-	// The following is similar to funcLit
 	oldfn := n.Func
-	newfn := ir.NewFunc(oldfn.Pos())
-	// These three lines are not strictly necessary, but just to be clear
-	// that new function needs to redo typechecking and inlinability.
-	newfn.SetTypecheck(0)
-	newfn.SetInlinabilityChecked(false)
-	newfn.Inl = nil
-	newfn.SetIsHiddenClosure(true)
-	newfn.Nname = ir.NewNameAt(n.Pos(), ir.BlankNode.Sym())
-	newfn.Nname.Func = newfn
+	newfn := ir.NewClosureFunc(oldfn.Pos(), true)
+
 	// Ntype can be nil for -G=3 mode.
 	if oldfn.Nname.Ntype != nil {
 		newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
 	}
-	newfn.Nname.Defn = newfn
-
-	m.(*ir.ClosureExpr).Func = newfn
-	newfn.OClosure = m.(*ir.ClosureExpr)
 
 	if subst.newclofn != nil {
 		//fmt.Printf("Inlining a closure with a nested closure\n")
@@ -1303,13 +1149,9 @@ func (subst *inlsubst) closure(n *ir.ClosureExpr) ir.Node {
 
 	// Actually create the named function for the closure, now that
 	// the closure is inlined in a specific function.
-	m.SetTypecheck(0)
-	if oldfn.ClosureCalled() {
-		typecheck.Callee(m)
-	} else {
-		typecheck.Expr(m)
-	}
-	return m
+	newclo := newfn.OClosure
+	newclo.SetInit(subst.list(n.Init()))
+	return typecheck.Expr(newclo)
 }
 
 // node recursively copies a node from the saved pristine body of the
@@ -1391,7 +1233,7 @@ func (subst *inlsubst) node(n ir.Node) ir.Node {
 			}
 			as.Rhs = subst.list(n.Results)
 
-			if subst.delayretvars {
+			if subst.fn.Inl.CanDelayResults {
 				for _, n := range as.Lhs {
 					as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
 					n.Name().Defn = as
diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index f70645f07913f8c309023d0fc84208d8e09b85b3..f526d987a7b20e6318655445319c30a7a1cda058 100644
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -142,28 +142,15 @@ func (n *BinaryExpr) SetOp(op Op) {
 	}
 }
 
-// A CallUse records how the result of the call is used:
-type CallUse byte
-
-const (
-	_ CallUse = iota
-
-	CallUseExpr // single expression result is used
-	CallUseList // list of results are used
-	CallUseStmt // results not used - call is a statement
-)
-
 // A CallExpr is a function call X(Args).
 type CallExpr struct {
 	miniExpr
 	origNode
-	X               Node
-	Args            Nodes
-	KeepAlive       []*Name // vars to be kept alive until call returns
-	IsDDD           bool
-	Use             CallUse
-	NoInline        bool
-	PreserveClosure bool // disable directClosureCall for this call
+	X         Node
+	Args      Nodes
+	KeepAlive []*Name // vars to be kept alive until call returns
+	IsDDD     bool
+	NoInline  bool
 }
 
 func NewCallExpr(pos src.XPos, op Op, fun Node, args []Node) *CallExpr {
@@ -181,8 +168,12 @@ func (n *CallExpr) SetOp(op Op) {
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OCALL, OCALLFUNC, OCALLINTER, OCALLMETH,
-		OAPPEND, ODELETE, OGETG, OMAKE, OPRINT, OPRINTN, ORECOVER:
+	case OAPPEND,
+		OCALL, OCALLFUNC, OCALLINTER, OCALLMETH,
+		ODELETE,
+		OGETG, OGETCALLERPC, OGETCALLERSP,
+		OMAKE, OPRINT, OPRINTN,
+		ORECOVER, ORECOVERFP:
 		n.op = op
 	}
 }
@@ -192,8 +183,10 @@ type ClosureExpr struct {
 	miniExpr
 	Func     *Func `mknode:"-"`
 	Prealloc *Name
+	IsGoWrap bool // whether this is wrapper closure of a go statement
 }
 
+// Deprecated: Use NewClosureFunc instead.
 func NewClosureExpr(pos src.XPos, fn *Func) *ClosureExpr {
 	n := &ClosureExpr{Func: fn}
 	n.op = OCLOSURE
@@ -277,12 +270,12 @@ func (n *ConvExpr) SetOp(op Op) {
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OCONV, OCONVIFACE, OCONVNOP, OBYTES2STR, OBYTES2STRTMP, ORUNES2STR, OSTR2BYTES, OSTR2BYTESTMP, OSTR2RUNES, ORUNESTR, OSLICE2ARRPTR:
+	case OCONV, OCONVIFACE, OCONVIDATA, OCONVNOP, OBYTES2STR, OBYTES2STRTMP, ORUNES2STR, OSTR2BYTES, OSTR2BYTESTMP, OSTR2RUNES, ORUNESTR, OSLICE2ARRPTR:
 		n.op = op
 	}
 }
 
-// An IndexExpr is an index expression X[Y].
+// An IndexExpr is an index expression X[Index].
 type IndexExpr struct {
 	miniExpr
 	X        Node
@@ -323,26 +316,24 @@ func NewKeyExpr(pos src.XPos, key, value Node) *KeyExpr {
 // A StructKeyExpr is an Field: Value composite literal key.
 type StructKeyExpr struct {
 	miniExpr
-	Field  *types.Sym
-	Value  Node
-	Offset int64
+	Field *types.Field
+	Value Node
 }
 
-func NewStructKeyExpr(pos src.XPos, field *types.Sym, value Node) *StructKeyExpr {
+func NewStructKeyExpr(pos src.XPos, field *types.Field, value Node) *StructKeyExpr {
 	n := &StructKeyExpr{Field: field, Value: value}
 	n.pos = pos
 	n.op = OSTRUCTKEY
-	n.Offset = types.BADWIDTH
 	return n
 }
 
-func (n *StructKeyExpr) Sym() *types.Sym { return n.Field }
+func (n *StructKeyExpr) Sym() *types.Sym { return n.Field.Sym }
 
 // An InlinedCallExpr is an inlined function call.
 type InlinedCallExpr struct {
 	miniExpr
 	Body       Nodes
-	ReturnVars Nodes
+	ReturnVars Nodes // must be side-effect free
 }
 
 func NewInlinedCallExpr(pos src.XPos, body, retvars []Node) *InlinedCallExpr {
@@ -354,6 +345,21 @@ func NewInlinedCallExpr(pos src.XPos, body, retvars []Node) *InlinedCallExpr {
 	return n
 }
 
+func (n *InlinedCallExpr) SingleResult() Node {
+	if have := len(n.ReturnVars); have != 1 {
+		base.FatalfAt(n.Pos(), "inlined call has %v results, expected 1", have)
+	}
+	if !n.Type().HasShape() && n.ReturnVars[0].Type().HasShape() {
+		// If the type of the call is not a shape, but the type of the return value
+		// is a shape, we need to do an implicit conversion, so the real type
+		// of n is maintained.
+		r := NewConvExpr(n.Pos(), OCONVNOP, n.Type(), n.ReturnVars[0])
+		r.SetTypecheck(1)
+		return r
+	}
+	return n.ReturnVars[0]
+}
+
 // A LogicalExpr is a expression X Op Y where Op is && or ||.
 // It is separate from BinaryExpr to make room for statements
 // that must be executed before Y but after X.
@@ -448,6 +454,20 @@ func (n *ParenExpr) SetOTYPE(t *types.Type) {
 	t.SetNod(n)
 }
 
+// A RawOrigExpr represents an arbitrary Go expression as a string value.
+// When printed in diagnostics, the string value is written out exactly as-is.
+type RawOrigExpr struct {
+	miniExpr
+	Raw string
+}
+
+func NewRawOrigExpr(pos src.XPos, op Op, raw string) *RawOrigExpr {
+	n := &RawOrigExpr{Raw: raw}
+	n.pos = pos
+	n.op = op
+	return n
+}
+
 // A ResultExpr represents a direct access to a result.
 type ResultExpr struct {
 	miniExpr
@@ -494,10 +514,15 @@ func NewNameOffsetExpr(pos src.XPos, name *Name, offset int64, typ *types.Type)
 // A SelectorExpr is a selector expression X.Sel.
 type SelectorExpr struct {
 	miniExpr
-	X         Node
-	Sel       *types.Sym
+	X Node
+	// Sel is the name of the field or method being selected, without (in the
+	// case of methods) any preceding type specifier. If the field/method is
+	// exported, than the Sym uses the local package regardless of the package
+	// of the containing type.
+	Sel *types.Sym
+	// The actual selected field - may not be filled in until typechecking.
 	Selection *types.Field
-	Prealloc  *Name // preallocated storage for OCALLPART, if any
+	Prealloc  *Name // preallocated storage for OMETHVALUE, if any
 }
 
 func NewSelectorExpr(pos src.XPos, op Op, x Node, sel *types.Sym) *SelectorExpr {
@@ -511,7 +536,7 @@ func (n *SelectorExpr) SetOp(op Op) {
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OXDOT, ODOT, ODOTPTR, ODOTMETH, ODOTINTER, OCALLPART, OMETHEXPR:
+	case OXDOT, ODOT, ODOTPTR, ODOTMETH, ODOTINTER, OMETHVALUE, OMETHEXPR:
 		n.op = op
 	}
 }
@@ -652,6 +677,38 @@ func (n *TypeAssertExpr) SetOp(op Op) {
 	}
 }
 
+// A DynamicTypeAssertExpr asserts that X is of dynamic type T.
+type DynamicTypeAssertExpr struct {
+	miniExpr
+	X Node
+	// N = not an interface
+	// E = empty interface
+	// I = nonempty interface
+	// For E->N, T is a *runtime.type for N
+	// For I->N, T is a *runtime.itab for N+I
+	// For E->I, T is a *runtime.type for I
+	// For I->I, ditto
+	// For I->E, T is a *runtime.type for interface{} (unnecessary, but just to fill in the slot)
+	// For E->E, ditto
+	T Node
+}
+
+func NewDynamicTypeAssertExpr(pos src.XPos, op Op, x, t Node) *DynamicTypeAssertExpr {
+	n := &DynamicTypeAssertExpr{X: x, T: t}
+	n.pos = pos
+	n.op = op
+	return n
+}
+
+func (n *DynamicTypeAssertExpr) SetOp(op Op) {
+	switch op {
+	default:
+		panic(n.no("SetOp " + op.String()))
+	case ODYNAMICDOTTYPE, ODYNAMICDOTTYPE2:
+		n.op = op
+	}
+}
+
 // A UnaryExpr is a unary expression Op X,
 // or Op(X) for a builtin function that does not end up being a call.
 type UnaryExpr struct {
@@ -678,6 +735,11 @@ func (n *UnaryExpr) SetOp(op Op) {
 	}
 }
 
+// Probably temporary: using Implicit() flag to mark generic function nodes that
+// are called to make getGfInfo analysis easier in one pre-order pass.
+func (n *InstExpr) Implicit() bool     { return n.flags&miniExprImplicit != 0 }
+func (n *InstExpr) SetImplicit(b bool) { n.flags.set(miniExprImplicit, b) }
+
 // An InstExpr is a generic function or type instantiation.
 type InstExpr struct {
 	miniExpr
@@ -773,6 +835,11 @@ func StaticValue(n Node) Node {
 			continue
 		}
 
+		if n.Op() == OINLCALL {
+			n = n.(*InlinedCallExpr).SingleResult()
+			continue
+		}
+
 		n1 := staticValue1(n)
 		if n1 == nil {
 			return n
@@ -1071,7 +1138,7 @@ func MethodExprName(n Node) *Name {
 // MethodExprFunc is like MethodExprName, but returns the types.Field instead.
 func MethodExprFunc(n Node) *types.Field {
 	switch n.Op() {
-	case ODOTMETH, OMETHEXPR, OCALLPART:
+	case ODOTMETH, OMETHEXPR, OMETHVALUE:
 		return n.(*SelectorExpr).Selection
 	}
 	base.Fatalf("unexpected node: %v (%v)", n, n.Op())
diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go
index f2ae0f7606ee7ba04d8b219f1330de8ecf18a121..d19fe453efc1b3a054463618a57368647b50a6a1 100644
--- a/src/cmd/compile/internal/ir/fmt.go
+++ b/src/cmd/compile/internal/ir/fmt.go
@@ -185,6 +185,7 @@ var OpPrec = []int{
 	OCLOSE:         8,
 	OCOMPLIT:       8,
 	OCONVIFACE:     8,
+	OCONVIDATA:     8,
 	OCONVNOP:       8,
 	OCONV:          8,
 	OCOPY:          8,
@@ -237,7 +238,7 @@ var OpPrec = []int{
 	ODOTTYPE:       8,
 	ODOT:           8,
 	OXDOT:          8,
-	OCALLPART:      8,
+	OMETHVALUE:     8,
 	OMETHEXPR:      8,
 	OPLUS:          7,
 	ONOT:           7,
@@ -546,7 +547,7 @@ func exprFmt(n Node, s fmt.State, prec int) {
 				n = nn.X
 				continue
 			}
-		case OCONV, OCONVNOP, OCONVIFACE:
+		case OCONV, OCONVNOP, OCONVIFACE, OCONVIDATA:
 			nn := nn.(*ConvExpr)
 			if nn.Implicit() {
 				n = nn.X
@@ -567,6 +568,11 @@ func exprFmt(n Node, s fmt.State, prec int) {
 		return
 	}
 
+	if n, ok := n.(*RawOrigExpr); ok {
+		fmt.Fprint(s, n.Raw)
+		return
+	}
+
 	switch n.Op() {
 	case OPAREN:
 		n := n.(*ParenExpr)
@@ -709,6 +715,10 @@ func exprFmt(n Node, s fmt.State, prec int) {
 				fmt.Fprintf(s, "... argument")
 				return
 			}
+			if typ := n.Type(); typ != nil {
+				fmt.Fprintf(s, "%v{%s}", typ, ellipsisIf(len(n.List) != 0))
+				return
+			}
 			if n.Ntype != nil {
 				fmt.Fprintf(s, "%v{%s}", n.Ntype, ellipsisIf(len(n.List) != 0))
 				return
@@ -752,7 +762,7 @@ func exprFmt(n Node, s fmt.State, prec int) {
 		n := n.(*StructKeyExpr)
 		fmt.Fprintf(s, "%v:%v", n.Field, n.Value)
 
-	case OXDOT, ODOT, ODOTPTR, ODOTINTER, ODOTMETH, OCALLPART, OMETHEXPR:
+	case OXDOT, ODOT, ODOTPTR, ODOTINTER, ODOTMETH, OMETHVALUE, OMETHEXPR:
 		n := n.(*SelectorExpr)
 		exprFmt(n.X, s, nprec)
 		if n.Sel == nil {
@@ -804,6 +814,7 @@ func exprFmt(n Node, s fmt.State, prec int) {
 
 	case OCONV,
 		OCONVIFACE,
+		OCONVIDATA,
 		OCONVNOP,
 		OBYTES2STR,
 		ORUNES2STR,
@@ -854,6 +865,15 @@ func exprFmt(n Node, s fmt.State, prec int) {
 		}
 		fmt.Fprintf(s, "(%.v)", n.Args)
 
+	case OINLCALL:
+		n := n.(*InlinedCallExpr)
+		// TODO(mdempsky): Print Init and/or Body?
+		if len(n.ReturnVars) == 1 {
+			fmt.Fprintf(s, "%v", n.ReturnVars[0])
+			return
+		}
+		fmt.Fprintf(s, "(.%v)", n.ReturnVars)
+
 	case OMAKEMAP, OMAKECHAN, OMAKESLICE:
 		n := n.(*MakeExpr)
 		if n.Cap != nil {
@@ -986,7 +1006,7 @@ func (l Nodes) Format(s fmt.State, verb rune) {
 
 // Dump prints the message s followed by a debug dump of n.
 func Dump(s string, n Node) {
-	fmt.Printf("%s [%p]%+v\n", s, n, n)
+	fmt.Printf("%s%+v\n", s, n)
 }
 
 // DumpList prints the message s followed by a debug dump of each node in the list.
@@ -1114,16 +1134,21 @@ func dumpNodeHeader(w io.Writer, n Node) {
 	}
 
 	if n.Pos().IsKnown() {
-		pfx := ""
+		fmt.Fprint(w, " # ")
 		switch n.Pos().IsStmt() {
 		case src.PosNotStmt:
-			pfx = "_" // "-" would be confusing
+			fmt.Fprint(w, "_") // "-" would be confusing
 		case src.PosIsStmt:
-			pfx = "+"
+			fmt.Fprint(w, "+")
+		}
+		for i, pos := range base.Ctxt.AllPos(n.Pos(), nil) {
+			if i > 0 {
+				fmt.Fprint(w, ",")
+			}
+			// TODO(mdempsky): Print line pragma details too.
+			file := filepath.Base(pos.Filename())
+			fmt.Fprintf(w, "%s:%d:%d", file, pos.Line(), pos.Col())
 		}
-		pos := base.Ctxt.PosTable.Pos(n.Pos())
-		file := filepath.Base(pos.Filename())
-		fmt.Fprintf(w, " # %s%s:%d", pfx, file, pos.Line())
 	}
 }
 
diff --git a/src/cmd/compile/internal/ir/func.go b/src/cmd/compile/internal/ir/func.go
index 20fe965711df33896e2f8025ea91b450a863dc4d..18d0b023ad6e916c94cc98bec2787e6cba4bff15 100644
--- a/src/cmd/compile/internal/ir/func.go
+++ b/src/cmd/compile/internal/ir/func.go
@@ -9,6 +9,7 @@ import (
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
 	"cmd/internal/src"
+	"fmt"
 )
 
 // A Func corresponds to a single function in a Go program
@@ -39,14 +40,14 @@ import (
 // constructs a fresh node.
 //
 // A method value (t.M) is represented by ODOTMETH/ODOTINTER
-// when it is called directly and by OCALLPART otherwise.
+// when it is called directly and by OMETHVALUE otherwise.
 // These are like method expressions, except that for ODOTMETH/ODOTINTER,
 // the method name is stored in Sym instead of Right.
-// Each OCALLPART ends up being implemented as a new
+// Each OMETHVALUE ends up being implemented as a new
 // function, a bit like a closure, with its own ODCLFUNC.
-// The OCALLPART uses n.Func to record the linkage to
+// The OMETHVALUE uses n.Func to record the linkage to
 // the generated ODCLFUNC, but there is no
-// pointer from the Func back to the OCALLPART.
+// pointer from the Func back to the OMETHVALUE.
 type Func struct {
 	miniNode
 	Body Nodes
@@ -166,6 +167,11 @@ type Inline struct {
 	// another package is imported.
 	Dcl  []*Name
 	Body []Node
+
+	// CanDelayResults reports whether it's safe for the inliner to delay
+	// initializing the result parameters until immediately before the
+	// "return" statement.
+	CanDelayResults bool
 }
 
 // A Mark represents a scope boundary.
@@ -190,13 +196,14 @@ const (
 	// true if closure inside a function; false if a simple function or a
 	// closure in a global variable initialization
 	funcIsHiddenClosure
+	funcIsDeadcodeClosure        // true if closure is deadcode
 	funcHasDefer                 // contains a defer statement
 	funcNilCheckDisabled         // disable nil checks when compiling this function
 	funcInlinabilityChecked      // inliner has already determined whether the function is inlinable
 	funcExportInline             // include inline body in export data
 	funcInstrumentBody           // add race/msan instrumentation during SSA construction
 	funcOpenCodedDeferDisallowed // can't do open-coded defers
-	funcClosureCalled            // closure is only immediately called
+	funcClosureCalled            // closure is only immediately called; used by escape analysis
 )
 
 type SymAndPos struct {
@@ -210,6 +217,7 @@ func (f *Func) ABIWrapper() bool               { return f.flags&funcABIWrapper !
 func (f *Func) Needctxt() bool                 { return f.flags&funcNeedctxt != 0 }
 func (f *Func) ReflectMethod() bool            { return f.flags&funcReflectMethod != 0 }
 func (f *Func) IsHiddenClosure() bool          { return f.flags&funcIsHiddenClosure != 0 }
+func (f *Func) IsDeadcodeClosure() bool        { return f.flags&funcIsDeadcodeClosure != 0 }
 func (f *Func) HasDefer() bool                 { return f.flags&funcHasDefer != 0 }
 func (f *Func) NilCheckDisabled() bool         { return f.flags&funcNilCheckDisabled != 0 }
 func (f *Func) InlinabilityChecked() bool      { return f.flags&funcInlinabilityChecked != 0 }
@@ -224,6 +232,7 @@ func (f *Func) SetABIWrapper(b bool)               { f.flags.set(funcABIWrapper,
 func (f *Func) SetNeedctxt(b bool)                 { f.flags.set(funcNeedctxt, b) }
 func (f *Func) SetReflectMethod(b bool)            { f.flags.set(funcReflectMethod, b) }
 func (f *Func) SetIsHiddenClosure(b bool)          { f.flags.set(funcIsHiddenClosure, b) }
+func (f *Func) SetIsDeadcodeClosure(b bool)        { f.flags.set(funcIsDeadcodeClosure, b) }
 func (f *Func) SetHasDefer(b bool)                 { f.flags.set(funcHasDefer, b) }
 func (f *Func) SetNilCheckDisabled(b bool)         { f.flags.set(funcNilCheckDisabled, b) }
 func (f *Func) SetInlinabilityChecked(b bool)      { f.flags.set(funcInlinabilityChecked, b) }
@@ -272,6 +281,17 @@ func PkgFuncName(f *Func) string {
 
 var CurFunc *Func
 
+// WithFunc invokes do with CurFunc and base.Pos set to curfn and
+// curfn.Pos(), respectively, and then restores their previous values
+// before returning.
+func WithFunc(curfn *Func, do func()) {
+	oldfn, oldpos := CurFunc, base.Pos
+	defer func() { CurFunc, base.Pos = oldfn, oldpos }()
+
+	CurFunc, base.Pos = curfn, curfn.Pos()
+	do()
+}
+
 func FuncSymName(s *types.Sym) string {
 	return s.Name + "·f"
 }
@@ -279,7 +299,7 @@ func FuncSymName(s *types.Sym) string {
 // MarkFunc marks a node as a function.
 func MarkFunc(n *Name) {
 	if n.Op() != ONAME || n.Class != Pxxx {
-		base.Fatalf("expected ONAME/Pxxx node, got %v", n)
+		base.FatalfAt(n.Pos(), "expected ONAME/Pxxx node, got %v (%v/%v)", n, n.Op(), n.Class)
 	}
 
 	n.Class = PFUNC
@@ -296,8 +316,8 @@ func ClosureDebugRuntimeCheck(clo *ClosureExpr) {
 			base.WarnfAt(clo.Pos(), "stack closure, captured vars = %v", clo.Func.ClosureVars)
 		}
 	}
-	if base.Flag.CompilingRuntime && clo.Esc() == EscHeap {
-		base.ErrorfAt(clo.Pos(), "heap-allocated closure, not allowed in runtime")
+	if base.Flag.CompilingRuntime && clo.Esc() == EscHeap && !clo.IsGoWrap {
+		base.ErrorfAt(clo.Pos(), "heap-allocated closure %s, not allowed in runtime", FuncName(clo.Func))
 	}
 }
 
@@ -306,3 +326,109 @@ func ClosureDebugRuntimeCheck(clo *ClosureExpr) {
 func IsTrivialClosure(clo *ClosureExpr) bool {
 	return len(clo.Func.ClosureVars) == 0
 }
+
+// globClosgen is like Func.Closgen, but for the global scope.
+var globClosgen int32
+
+// closureName generates a new unique name for a closure within outerfn.
+func closureName(outerfn *Func) *types.Sym {
+	pkg := types.LocalPkg
+	outer := "glob."
+	prefix := "func"
+	gen := &globClosgen
+
+	if outerfn != nil {
+		if outerfn.OClosure != nil {
+			prefix = ""
+		}
+
+		pkg = outerfn.Sym().Pkg
+		outer = FuncName(outerfn)
+
+		// There may be multiple functions named "_". In those
+		// cases, we can't use their individual Closgens as it
+		// would lead to name clashes.
+		if !IsBlank(outerfn.Nname) {
+			gen = &outerfn.Closgen
+		}
+	}
+
+	*gen++
+	return pkg.Lookup(fmt.Sprintf("%s.%s%d", outer, prefix, *gen))
+}
+
+// NewClosureFunc creates a new Func to represent a function literal.
+// If hidden is true, then the closure is marked hidden (i.e., as a
+// function literal contained within another function, rather than a
+// package-scope variable initialization expression).
+func NewClosureFunc(pos src.XPos, hidden bool) *Func {
+	fn := NewFunc(pos)
+	fn.SetIsHiddenClosure(hidden)
+
+	fn.Nname = NewNameAt(pos, BlankNode.Sym())
+	fn.Nname.Func = fn
+	fn.Nname.Defn = fn
+
+	fn.OClosure = NewClosureExpr(pos, fn)
+
+	return fn
+}
+
+// NameClosure generates a unique for the given function literal,
+// which must have appeared within outerfn.
+func NameClosure(clo *ClosureExpr, outerfn *Func) {
+	fn := clo.Func
+	if fn.IsHiddenClosure() != (outerfn != nil) {
+		base.FatalfAt(clo.Pos(), "closure naming inconsistency: hidden %v, but outer %v", fn.IsHiddenClosure(), outerfn)
+	}
+
+	name := fn.Nname
+	if !IsBlank(name) {
+		base.FatalfAt(clo.Pos(), "closure already named: %v", name)
+	}
+
+	name.SetSym(closureName(outerfn))
+	MarkFunc(name)
+}
+
+// UseClosure checks that the ginen function literal has been setup
+// correctly, and then returns it as an expression.
+// It must be called after clo.Func.ClosureVars has been set.
+func UseClosure(clo *ClosureExpr, pkg *Package) Node {
+	fn := clo.Func
+	name := fn.Nname
+
+	if IsBlank(name) {
+		base.FatalfAt(fn.Pos(), "unnamed closure func: %v", fn)
+	}
+	// Caution: clo.Typecheck() is still 0 when UseClosure is called by
+	// tcClosure.
+	if fn.Typecheck() != 1 || name.Typecheck() != 1 {
+		base.FatalfAt(fn.Pos(), "missed typecheck: %v", fn)
+	}
+	if clo.Type() == nil || name.Type() == nil {
+		base.FatalfAt(fn.Pos(), "missing types: %v", fn)
+	}
+	if !types.Identical(clo.Type(), name.Type()) {
+		base.FatalfAt(fn.Pos(), "mismatched types: %v", fn)
+	}
+
+	if base.Flag.W > 1 {
+		s := fmt.Sprintf("new closure func: %v", fn)
+		Dump(s, fn)
+	}
+
+	if pkg != nil {
+		pkg.Decls = append(pkg.Decls, fn)
+	}
+
+	if false && IsTrivialClosure(clo) {
+		// TODO(mdempsky): Investigate if we can/should optimize this
+		// case. walkClosure already handles it later, but it could be
+		// useful to recognize earlier (e.g., it might allow multiple
+		// inlined calls to a function to share a common trivial closure
+		// func, rather than cloning it for each inlined call).
+	}
+
+	return clo
+}
diff --git a/src/cmd/compile/internal/ir/name.go b/src/cmd/compile/internal/ir/name.go
index b6c68bc5e01a4b33d8b590f29658886446584fbf..a2eec05013e1092076ec62524c1f3235bc5d1fd1 100644
--- a/src/cmd/compile/internal/ir/name.go
+++ b/src/cmd/compile/internal/ir/name.go
@@ -358,39 +358,74 @@ func (n *Name) Byval() bool {
 	return n.Canonical().flags&nameByval != 0
 }
 
+// NewClosureVar returns a new closure variable for fn to refer to
+// outer variable n.
+func NewClosureVar(pos src.XPos, fn *Func, n *Name) *Name {
+	c := NewNameAt(pos, n.Sym())
+	c.Curfn = fn
+	c.Class = PAUTOHEAP
+	c.SetIsClosureVar(true)
+	c.Defn = n.Canonical()
+	c.Outer = n
+
+	c.SetType(n.Type())
+	c.SetTypecheck(n.Typecheck())
+
+	fn.ClosureVars = append(fn.ClosureVars, c)
+
+	return c
+}
+
+// NewHiddenParam returns a new hidden parameter for fn with the given
+// name and type.
+func NewHiddenParam(pos src.XPos, fn *Func, sym *types.Sym, typ *types.Type) *Name {
+	if fn.OClosure != nil {
+		base.FatalfAt(fn.Pos(), "cannot add hidden parameters to closures")
+	}
+
+	fn.SetNeedctxt(true)
+
+	// Create a fake parameter, disassociated from any real function, to
+	// pretend to capture.
+	fake := NewNameAt(pos, sym)
+	fake.Class = PPARAM
+	fake.SetType(typ)
+	fake.SetByval(true)
+
+	return NewClosureVar(pos, fn, fake)
+}
+
 // CaptureName returns a Name suitable for referring to n from within function
 // fn or from the package block if fn is nil. If n is a free variable declared
-// within a function that encloses fn, then CaptureName returns a closure
-// variable that refers to n and adds it to fn.ClosureVars. Otherwise, it simply
-// returns n.
+// within a function that encloses fn, then CaptureName returns the closure
+// variable that refers to n within fn, creating it if necessary.
+// Otherwise, it simply returns n.
 func CaptureName(pos src.XPos, fn *Func, n *Name) *Name {
-	if n.IsClosureVar() {
-		base.FatalfAt(pos, "misuse of CaptureName on closure variable: %v", n)
-	}
-	if n.Op() != ONAME || n.Curfn == nil || n.Curfn == fn {
+	if n.Op() != ONAME || n.Curfn == nil {
 		return n // okay to use directly
 	}
-	if fn == nil {
-		base.FatalfAt(pos, "package-block reference to %v, declared in %v", n, n.Curfn)
+	if n.IsClosureVar() {
+		base.FatalfAt(pos, "misuse of CaptureName on closure variable: %v", n)
 	}
 
 	c := n.Innermost
-	if c != nil && c.Curfn == fn {
+	if c == nil {
+		c = n
+	}
+	if c.Curfn == fn {
 		return c
 	}
 
+	if fn == nil {
+		base.FatalfAt(pos, "package-block reference to %v, declared in %v", n, n.Curfn)
+	}
+
 	// Do not have a closure var for the active closure yet; make one.
-	c = NewNameAt(pos, n.Sym())
-	c.Curfn = fn
-	c.Class = PAUTOHEAP
-	c.SetIsClosureVar(true)
-	c.Defn = n
+	c = NewClosureVar(pos, fn, c)
 
 	// Link into list of active closure variables.
 	// Popped from list in FinishCaptureNames.
-	c.Outer = n.Innermost
 	n.Innermost = c
-	fn.ClosureVars = append(fn.ClosureVars, c)
 
 	return c
 }
diff --git a/src/cmd/compile/internal/ir/node.go b/src/cmd/compile/internal/ir/node.go
index af559cc0820cc3e74ebd3065630e558c008e3e53..f071cb78ce56db74703f29be24d5c06802a76e18 100644
--- a/src/cmd/compile/internal/ir/node.go
+++ b/src/cmd/compile/internal/ir/node.go
@@ -159,7 +159,6 @@ const (
 	OCALLFUNC  // X(Args) (function call f(args))
 	OCALLMETH  // X(Args) (direct method call x.Method(args))
 	OCALLINTER // X(Args) (interface method call x.Method(args))
-	OCALLPART  // X.Sel (method expression x.Method, not called)
 	OCAP       // cap(X)
 	OCLOSE     // close(X)
 	OCLOSURE   // func Type { Func.Closure.Body } (func literal)
@@ -171,6 +170,7 @@ const (
 	OPTRLIT    // &X (X is composite literal)
 	OCONV      // Type(X) (type conversion)
 	OCONVIFACE // Type(X) (type conversion, to interface)
+	OCONVIDATA // Builds a data word to store X in an interface. Equivalent to IDATA(CONVIFACE(X)). Is an ir.ConvExpr.
 	OCONVNOP   // Type(X) (type conversion, no effect)
 	OCOPY      // copy(X, Y)
 	ODCL       // var X (declares X of type X.Type)
@@ -237,6 +237,7 @@ const (
 	OSLICE3ARR   // X[Low : High : Max] (X is pointer to array)
 	OSLICEHEADER // sliceheader{Ptr, Len, Cap} (Ptr is unsafe.Pointer, Len is length, Cap is capacity)
 	ORECOVER     // recover()
+	ORECOVERFP   // recover(Args) w/ explicit FP argument
 	ORECV        // <-X
 	ORUNESTR     // Type(X) (Type is string, X is rune)
 	OSELRECV2    // like OAS2: Lhs = Rhs where len(Lhs)=2, len(Rhs)=1, Rhs[0].Op = ORECV (appears as .Var of OCASE)
@@ -249,14 +250,16 @@ const (
 	OSIZEOF      // unsafe.Sizeof(X)
 	OUNSAFEADD   // unsafe.Add(X, Y)
 	OUNSAFESLICE // unsafe.Slice(X, Y)
-	OMETHEXPR    // method expression
+	OMETHEXPR    // X(Args) (method expression T.Method(args), first argument is the method receiver)
+	OMETHVALUE   // X.Sel   (method expression t.Method, not called)
 
 	// statements
 	OBLOCK // { List } (block of code)
 	OBREAK // break [Label]
 	// OCASE:  case List: Body (List==nil means default)
 	//   For OTYPESW, List is a OTYPE node for the specified type (or OLITERAL
-	//   for nil), and, if a type-switch variable is specified, Rlist is an
+	//   for nil) or an ODYNAMICTYPE indicating a runtime type for generics.
+	//   If a type-switch variable is specified, Var is an
 	//   ONAME for the version of the type-switch variable with the specified
 	//   type.
 	OCASE
@@ -317,9 +320,16 @@ const (
 	OINLMARK       // start of an inlined body, with file/line of caller. Xoffset is an index into the inline tree.
 	OLINKSYMOFFSET // offset within a name
 
+	// opcodes for generics
+	ODYNAMICDOTTYPE  // x = i.(T) where T is a type parameter (or derived from a type parameter)
+	ODYNAMICDOTTYPE2 // x, ok = i.(T) where T is a type parameter (or derived from a type parameter)
+	ODYNAMICTYPE     // a type node for type switches (represents a dynamic target type for a type switch)
+
 	// arch-specific opcodes
-	OTAILCALL // tail call to another function
-	OGETG     // runtime.getg() (read g pointer)
+	OTAILCALL    // tail call to another function
+	OGETG        // runtime.getg() (read g pointer)
+	OGETCALLERPC // runtime.getcallerpc() (continuation PC in caller frame)
+	OGETCALLERSP // runtime.getcallersp() (stack pointer in caller frame)
 
 	OEND
 )
@@ -436,18 +446,19 @@ func (s NameSet) Sorted(less func(*Name, *Name) bool) []*Name {
 	return res
 }
 
-type PragmaFlag int16
+type PragmaFlag uint16
 
 const (
 	// Func pragmas.
-	Nointerface    PragmaFlag = 1 << iota
-	Noescape                  // func parameters don't escape
-	Norace                    // func must not have race detector annotations
-	Nosplit                   // func should not execute on separate stack
-	Noinline                  // func should not be inlined
-	NoCheckPtr                // func should not be instrumented by checkptr
-	CgoUnsafeArgs             // treat a pointer to one arg as a pointer to them all
-	UintptrEscapes            // pointers converted to uintptr escape
+	Nointerface      PragmaFlag = 1 << iota
+	Noescape                    // func parameters don't escape
+	Norace                      // func must not have race detector annotations
+	Nosplit                     // func should not execute on separate stack
+	Noinline                    // func should not be inlined
+	NoCheckPtr                  // func should not be instrumented by checkptr
+	CgoUnsafeArgs               // treat a pointer to one arg as a pointer to them all
+	UintptrKeepAlive            // pointers converted to uintptr must be kept alive (compiler internal only)
+	UintptrEscapes              // pointers converted to uintptr escape
 
 	// Runtime-only func pragmas.
 	// See ../../../../runtime/README.md for detailed descriptions.
@@ -563,7 +574,7 @@ func OuterValue(n Node) Node {
 	for {
 		switch nn := n; nn.Op() {
 		case OXDOT:
-			base.Fatalf("OXDOT in walk")
+			base.FatalfAt(n.Pos(), "OXDOT in walk: %v", n)
 		case ODOT:
 			nn := nn.(*SelectorExpr)
 			n = nn.X
diff --git a/src/cmd/compile/internal/ir/node_gen.go b/src/cmd/compile/internal/ir/node_gen.go
index 22855d7163f44a6e9d51586c60cabc3c397dccff..aa41c03beb97dd9f0d136cdcd6b15409de733850 100644
--- a/src/cmd/compile/internal/ir/node_gen.go
+++ b/src/cmd/compile/internal/ir/node_gen.go
@@ -463,6 +463,62 @@ func (n *Decl) editChildren(edit func(Node) Node) {
 	}
 }
 
+func (n *DynamicType) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
+func (n *DynamicType) copy() Node {
+	c := *n
+	c.init = copyNodes(c.init)
+	return &c
+}
+func (n *DynamicType) doChildren(do func(Node) bool) bool {
+	if doNodes(n.init, do) {
+		return true
+	}
+	if n.X != nil && do(n.X) {
+		return true
+	}
+	if n.ITab != nil && do(n.ITab) {
+		return true
+	}
+	return false
+}
+func (n *DynamicType) editChildren(edit func(Node) Node) {
+	editNodes(n.init, edit)
+	if n.X != nil {
+		n.X = edit(n.X).(Node)
+	}
+	if n.ITab != nil {
+		n.ITab = edit(n.ITab).(Node)
+	}
+}
+
+func (n *DynamicTypeAssertExpr) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
+func (n *DynamicTypeAssertExpr) copy() Node {
+	c := *n
+	c.init = copyNodes(c.init)
+	return &c
+}
+func (n *DynamicTypeAssertExpr) doChildren(do func(Node) bool) bool {
+	if doNodes(n.init, do) {
+		return true
+	}
+	if n.X != nil && do(n.X) {
+		return true
+	}
+	if n.T != nil && do(n.T) {
+		return true
+	}
+	return false
+}
+func (n *DynamicTypeAssertExpr) editChildren(edit func(Node) Node) {
+	editNodes(n.init, edit)
+	if n.X != nil {
+		n.X = edit(n.X).(Node)
+	}
+	if n.T != nil {
+		n.T = edit(n.T).(Node)
+	}
+}
+
 func (n *ForStmt) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
 func (n *ForStmt) copy() Node {
 	c := *n
@@ -947,6 +1003,22 @@ func (n *RangeStmt) editChildren(edit func(Node) Node) {
 	}
 }
 
+func (n *RawOrigExpr) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
+func (n *RawOrigExpr) copy() Node {
+	c := *n
+	c.init = copyNodes(c.init)
+	return &c
+}
+func (n *RawOrigExpr) doChildren(do func(Node) bool) bool {
+	if doNodes(n.init, do) {
+		return true
+	}
+	return false
+}
+func (n *RawOrigExpr) editChildren(edit func(Node) Node) {
+	editNodes(n.init, edit)
+}
+
 func (n *ResultExpr) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
 func (n *ResultExpr) copy() Node {
 	c := *n
diff --git a/src/cmd/compile/internal/ir/op_string.go b/src/cmd/compile/internal/ir/op_string.go
index 405a0c6b3c985851c4dbbf68c5fd8990a61e06cf..b8cee718182c08889eb73e6493d0c67ddb0e7b59 100644
--- a/src/cmd/compile/internal/ir/op_string.go
+++ b/src/cmd/compile/internal/ir/op_string.go
@@ -41,18 +41,18 @@ func _() {
 	_ = x[OCALLFUNC-30]
 	_ = x[OCALLMETH-31]
 	_ = x[OCALLINTER-32]
-	_ = x[OCALLPART-33]
-	_ = x[OCAP-34]
-	_ = x[OCLOSE-35]
-	_ = x[OCLOSURE-36]
-	_ = x[OCOMPLIT-37]
-	_ = x[OMAPLIT-38]
-	_ = x[OSTRUCTLIT-39]
-	_ = x[OARRAYLIT-40]
-	_ = x[OSLICELIT-41]
-	_ = x[OPTRLIT-42]
-	_ = x[OCONV-43]
-	_ = x[OCONVIFACE-44]
+	_ = x[OCAP-33]
+	_ = x[OCLOSE-34]
+	_ = x[OCLOSURE-35]
+	_ = x[OCOMPLIT-36]
+	_ = x[OMAPLIT-37]
+	_ = x[OSTRUCTLIT-38]
+	_ = x[OARRAYLIT-39]
+	_ = x[OSLICELIT-40]
+	_ = x[OPTRLIT-41]
+	_ = x[OCONV-42]
+	_ = x[OCONVIFACE-43]
+	_ = x[OCONVIDATA-44]
 	_ = x[OCONVNOP-45]
 	_ = x[OCOPY-46]
 	_ = x[ODCL-47]
@@ -109,65 +109,72 @@ func _() {
 	_ = x[OSLICE3ARR-98]
 	_ = x[OSLICEHEADER-99]
 	_ = x[ORECOVER-100]
-	_ = x[ORECV-101]
-	_ = x[ORUNESTR-102]
-	_ = x[OSELRECV2-103]
-	_ = x[OIOTA-104]
-	_ = x[OREAL-105]
-	_ = x[OIMAG-106]
-	_ = x[OCOMPLEX-107]
-	_ = x[OALIGNOF-108]
-	_ = x[OOFFSETOF-109]
-	_ = x[OSIZEOF-110]
-	_ = x[OUNSAFEADD-111]
-	_ = x[OUNSAFESLICE-112]
-	_ = x[OMETHEXPR-113]
-	_ = x[OBLOCK-114]
-	_ = x[OBREAK-115]
-	_ = x[OCASE-116]
-	_ = x[OCONTINUE-117]
-	_ = x[ODEFER-118]
-	_ = x[OFALL-119]
-	_ = x[OFOR-120]
-	_ = x[OFORUNTIL-121]
-	_ = x[OGOTO-122]
-	_ = x[OIF-123]
-	_ = x[OLABEL-124]
-	_ = x[OGO-125]
-	_ = x[ORANGE-126]
-	_ = x[ORETURN-127]
-	_ = x[OSELECT-128]
-	_ = x[OSWITCH-129]
-	_ = x[OTYPESW-130]
-	_ = x[OFUNCINST-131]
-	_ = x[OTCHAN-132]
-	_ = x[OTMAP-133]
-	_ = x[OTSTRUCT-134]
-	_ = x[OTINTER-135]
-	_ = x[OTFUNC-136]
-	_ = x[OTARRAY-137]
-	_ = x[OTSLICE-138]
-	_ = x[OINLCALL-139]
-	_ = x[OEFACE-140]
-	_ = x[OITAB-141]
-	_ = x[OIDATA-142]
-	_ = x[OSPTR-143]
-	_ = x[OCFUNC-144]
-	_ = x[OCHECKNIL-145]
-	_ = x[OVARDEF-146]
-	_ = x[OVARKILL-147]
-	_ = x[OVARLIVE-148]
-	_ = x[ORESULT-149]
-	_ = x[OINLMARK-150]
-	_ = x[OLINKSYMOFFSET-151]
-	_ = x[OTAILCALL-152]
-	_ = x[OGETG-153]
-	_ = x[OEND-154]
+	_ = x[ORECOVERFP-101]
+	_ = x[ORECV-102]
+	_ = x[ORUNESTR-103]
+	_ = x[OSELRECV2-104]
+	_ = x[OIOTA-105]
+	_ = x[OREAL-106]
+	_ = x[OIMAG-107]
+	_ = x[OCOMPLEX-108]
+	_ = x[OALIGNOF-109]
+	_ = x[OOFFSETOF-110]
+	_ = x[OSIZEOF-111]
+	_ = x[OUNSAFEADD-112]
+	_ = x[OUNSAFESLICE-113]
+	_ = x[OMETHEXPR-114]
+	_ = x[OMETHVALUE-115]
+	_ = x[OBLOCK-116]
+	_ = x[OBREAK-117]
+	_ = x[OCASE-118]
+	_ = x[OCONTINUE-119]
+	_ = x[ODEFER-120]
+	_ = x[OFALL-121]
+	_ = x[OFOR-122]
+	_ = x[OFORUNTIL-123]
+	_ = x[OGOTO-124]
+	_ = x[OIF-125]
+	_ = x[OLABEL-126]
+	_ = x[OGO-127]
+	_ = x[ORANGE-128]
+	_ = x[ORETURN-129]
+	_ = x[OSELECT-130]
+	_ = x[OSWITCH-131]
+	_ = x[OTYPESW-132]
+	_ = x[OFUNCINST-133]
+	_ = x[OTCHAN-134]
+	_ = x[OTMAP-135]
+	_ = x[OTSTRUCT-136]
+	_ = x[OTINTER-137]
+	_ = x[OTFUNC-138]
+	_ = x[OTARRAY-139]
+	_ = x[OTSLICE-140]
+	_ = x[OINLCALL-141]
+	_ = x[OEFACE-142]
+	_ = x[OITAB-143]
+	_ = x[OIDATA-144]
+	_ = x[OSPTR-145]
+	_ = x[OCFUNC-146]
+	_ = x[OCHECKNIL-147]
+	_ = x[OVARDEF-148]
+	_ = x[OVARKILL-149]
+	_ = x[OVARLIVE-150]
+	_ = x[ORESULT-151]
+	_ = x[OINLMARK-152]
+	_ = x[OLINKSYMOFFSET-153]
+	_ = x[ODYNAMICDOTTYPE-154]
+	_ = x[ODYNAMICDOTTYPE2-155]
+	_ = x[ODYNAMICTYPE-156]
+	_ = x[OTAILCALL-157]
+	_ = x[OGETG-158]
+	_ = x[OGETCALLERPC-159]
+	_ = x[OGETCALLERSP-160]
+	_ = x[OEND-161]
 }
 
-const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCALLPARTCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECVRUNESTRSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTTCHANTMAPTSTRUCTTINTERTFUNCTARRAYTSLICEINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETTAILCALLGETGEND"
+const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVIDATACONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECOVERFPRECVRUNESTRSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRMETHVALUEBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTTCHANTMAPTSTRUCTTINTERTFUNCTARRAYTSLICEINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETDYNAMICDOTTYPEDYNAMICDOTTYPE2DYNAMICTYPETAILCALLGETGGETCALLERPCGETCALLERSPEND"
 
-var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 136, 138, 141, 151, 158, 165, 172, 176, 180, 188, 196, 205, 213, 216, 221, 228, 235, 241, 250, 258, 266, 272, 276, 285, 292, 296, 299, 306, 314, 321, 327, 330, 336, 343, 351, 355, 362, 370, 372, 374, 376, 378, 380, 382, 387, 392, 400, 403, 412, 415, 419, 427, 434, 443, 456, 459, 462, 465, 468, 471, 474, 480, 483, 486, 492, 496, 499, 503, 508, 513, 519, 524, 528, 533, 541, 549, 555, 564, 575, 582, 586, 593, 601, 605, 609, 613, 620, 627, 635, 641, 650, 661, 669, 674, 679, 683, 691, 696, 700, 703, 711, 715, 717, 722, 724, 729, 735, 741, 747, 753, 761, 766, 770, 777, 783, 788, 794, 800, 807, 812, 816, 821, 825, 830, 838, 844, 851, 858, 864, 871, 884, 892, 896, 899}
+var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 136, 138, 141, 151, 158, 165, 172, 176, 180, 188, 196, 205, 208, 213, 220, 227, 233, 242, 250, 258, 264, 268, 277, 286, 293, 297, 300, 307, 315, 322, 328, 331, 337, 344, 352, 356, 363, 371, 373, 375, 377, 379, 381, 383, 388, 393, 401, 404, 413, 416, 420, 428, 435, 444, 457, 460, 463, 466, 469, 472, 475, 481, 484, 487, 493, 497, 500, 504, 509, 514, 520, 525, 529, 534, 542, 550, 556, 565, 576, 583, 592, 596, 603, 611, 615, 619, 623, 630, 637, 645, 651, 660, 671, 679, 688, 693, 698, 702, 710, 715, 719, 722, 730, 734, 736, 741, 743, 748, 754, 760, 766, 772, 780, 785, 789, 796, 802, 807, 813, 819, 826, 831, 835, 840, 844, 849, 857, 863, 870, 877, 883, 890, 903, 917, 932, 943, 951, 955, 966, 977, 980}
 
 func (i Op) String() string {
 	if i >= Op(len(_Op_index)-1) {
diff --git a/src/cmd/compile/internal/ir/package.go b/src/cmd/compile/internal/ir/package.go
index e4b93d113eda9c89b44512e2e5957c977df15a03..3896e2b91b1177dbc41977960d7fe26648e88d6e 100644
--- a/src/cmd/compile/internal/ir/package.go
+++ b/src/cmd/compile/internal/ir/package.go
@@ -32,7 +32,4 @@ type Package struct {
 
 	// Exported (or re-exported) symbols.
 	Exports []*Name
-
-	// Map from function names of stencils to already-created stencils.
-	Stencils map[*types.Sym]*Func
 }
diff --git a/src/cmd/compile/internal/ir/scc.go b/src/cmd/compile/internal/ir/scc.go
index 83c6074170b31370e0e6c6e71f35e56533204d2b..2cfceaa1f627fa1e4d7773b828278ecd94dd902f 100644
--- a/src/cmd/compile/internal/ir/scc.go
+++ b/src/cmd/compile/internal/ir/scc.go
@@ -90,7 +90,7 @@ func (v *bottomUpVisitor) visit(n *Func) uint32 {
 			if n := n.(*Name); n.Class == PFUNC {
 				do(n.Defn)
 			}
-		case ODOTMETH, OCALLPART, OMETHEXPR:
+		case ODOTMETH, OMETHVALUE, OMETHEXPR:
 			if fn := MethodExprName(n); fn != nil {
 				do(fn.Defn)
 			}
diff --git a/src/cmd/compile/internal/ir/stmt.go b/src/cmd/compile/internal/ir/stmt.go
index 8115012f97852c030d59b0e74bdd0cad17825916..69a74b9fdd6c402a7f6d619a18dde68df07fea8f 100644
--- a/src/cmd/compile/internal/ir/stmt.go
+++ b/src/cmd/compile/internal/ir/stmt.go
@@ -244,7 +244,7 @@ func NewGoDeferStmt(pos src.XPos, op Op, call Node) *GoDeferStmt {
 	return n
 }
 
-// A IfStmt is a return statement: if Init; Cond { Then } else { Else }.
+// An IfStmt is a return statement: if Init; Cond { Body } else { Else }.
 type IfStmt struct {
 	miniStmt
 	Cond   Node
diff --git a/src/cmd/compile/internal/ir/type.go b/src/cmd/compile/internal/ir/type.go
index a903ea8cd45543faebe7c9bce30c428f318b6a1b..63dd673dcdf11c9440139583a0252b22c384cdd6 100644
--- a/src/cmd/compile/internal/ir/type.go
+++ b/src/cmd/compile/internal/ir/type.go
@@ -300,11 +300,36 @@ func (n *typeNode) CanBeNtype()       {}
 
 // TypeNode returns the Node representing the type t.
 func TypeNode(t *types.Type) Ntype {
+	return TypeNodeAt(src.NoXPos, t)
+}
+
+// TypeNodeAt is like TypeNode, but allows specifying the position
+// information if a new OTYPE needs to be constructed.
+//
+// Deprecated: Use TypeNode instead. For typical use, the position for
+// an anonymous OTYPE node should not matter. However, TypeNodeAt is
+// available for use with toolstash -cmp to refactor existing code
+// that is sensitive to OTYPE position.
+func TypeNodeAt(pos src.XPos, t *types.Type) Ntype {
 	if n := t.Obj(); n != nil {
 		if n.Type() != t {
 			base.Fatalf("type skew: %v has type %v, but expected %v", n, n.Type(), t)
 		}
 		return n.(Ntype)
 	}
-	return newTypeNode(src.NoXPos, t)
+	return newTypeNode(pos, t)
+}
+
+// A DynamicType represents the target type in a type switch.
+type DynamicType struct {
+	miniExpr
+	X    Node // a *runtime._type for the targeted type
+	ITab Node // for type switches from nonempty interfaces to non-interfaces, this is the itab for that pair.
+}
+
+func NewDynamicType(pos src.XPos, x Node) *DynamicType {
+	n := &DynamicType{X: x}
+	n.pos = pos
+	n.op = ODYNAMICTYPE
+	return n
 }
diff --git a/src/cmd/compile/internal/ir/val.go b/src/cmd/compile/internal/ir/val.go
index 03c320e205dbfdf8b6b46eb7d3d9adcc8295c46d..bfe7d2bb436c8999631fdbf364c7c766006118a5 100644
--- a/src/cmd/compile/internal/ir/val.go
+++ b/src/cmd/compile/internal/ir/val.go
@@ -66,7 +66,7 @@ func Float64Val(v constant.Value) float64 {
 
 func AssertValidTypeForConst(t *types.Type, v constant.Value) {
 	if !ValidTypeForConst(t, v) {
-		base.Fatalf("%v does not represent %v", t, v)
+		base.Fatalf("%v (%v) does not represent %v (%v)", t, t.Kind(), v, v.Kind())
 	}
 }
 
diff --git a/src/cmd/compile/internal/liveness/plive.go b/src/cmd/compile/internal/liveness/plive.go
index f5c2ef7709e515c376cc181c8e338bd51a1b33d8..2705eac4f7b9b8f4316b2e2e44efe9d589e08ef0 100644
--- a/src/cmd/compile/internal/liveness/plive.go
+++ b/src/cmd/compile/internal/liveness/plive.go
@@ -1082,6 +1082,10 @@ func (lv *liveness) showlive(v *ssa.Value, live bitvec.BitVec) {
 	if base.Flag.Live == 0 || ir.FuncName(lv.fn) == "init" || strings.HasPrefix(ir.FuncName(lv.fn), ".") {
 		return
 	}
+	if lv.fn.Wrapper() || lv.fn.Dupok() {
+		// Skip reporting liveness information for compiler-generated wrappers.
+		return
+	}
 	if !(v == nil || v.Op.IsCall()) {
 		// Historically we only printed this information at
 		// calls. Keep doing so.
diff --git a/src/cmd/compile/internal/logopt/logopt_test.go b/src/cmd/compile/internal/logopt/logopt_test.go
index 71976174b03517def512290e47d86a4980a02963..902cbc8091f1eb1e56b1c0507cd25b19b52c78c1 100644
--- a/src/cmd/compile/internal/logopt/logopt_test.go
+++ b/src/cmd/compile/internal/logopt/logopt_test.go
@@ -209,7 +209,7 @@ func s15a8(x *[15]int64) [15]int64 {
 		want(t, slogged, `{"range":{"start":{"line":11,"character":6},"end":{"line":11,"character":6}},"severity":3,"code":"isInBounds","source":"go compiler","message":""}`)
 		want(t, slogged, `{"range":{"start":{"line":7,"character":6},"end":{"line":7,"character":6}},"severity":3,"code":"canInlineFunction","source":"go compiler","message":"cost: 35"}`)
 		// escape analysis explanation
-		want(t, slogged, `{"range":{"start":{"line":7,"character":13},"end":{"line":7,"character":13}},"severity":3,"code":"leak","source":"go compiler","message":"parameter z leaks to ~r2 with derefs=0",`+
+		want(t, slogged, `{"range":{"start":{"line":7,"character":13},"end":{"line":7,"character":13}},"severity":3,"code":"leak","source":"go compiler","message":"parameter z leaks to ~r0 with derefs=0",`+
 			`"relatedInformation":[`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:    flow: y = z:"},`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:      from y := z (assign-pair)"},`+
@@ -220,8 +220,8 @@ func s15a8(x *[15]int64) [15]int64 {
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:      from \u0026y.b (address-of)"},`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":4,"character":9},"end":{"line":4,"character":9}}},"message":"inlineLoc"},`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:      from ~R0 = \u0026y.b (assign-pair)"},`+
-			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:    flow: ~r2 = ~R0:"},`+
-			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:      from return (*int)(~R0) (return)"}]}`)
+			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:    flow: ~r0 = ~R0:"},`+
+			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:      from return ~R0 (return)"}]}`)
 	})
 }
 
diff --git a/src/cmd/compile/internal/mips/galign.go b/src/cmd/compile/internal/mips/galign.go
index f892923ba038f32a370873af79a9671e55e65a1b..4e6897042ec04ce2e81fa58960a26541fa5aaeb0 100644
--- a/src/cmd/compile/internal/mips/galign.go
+++ b/src/cmd/compile/internal/mips/galign.go
@@ -21,7 +21,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.SoftFloat = (buildcfg.GOMIPS == "softfloat")
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
diff --git a/src/cmd/compile/internal/mips64/galign.go b/src/cmd/compile/internal/mips64/galign.go
index af81366e51bdf51c4cd88b55da03440da29773c6..412bc71aab270d97befa5dd3296ad381db180dcc 100644
--- a/src/cmd/compile/internal/mips64/galign.go
+++ b/src/cmd/compile/internal/mips64/galign.go
@@ -21,7 +21,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.SoftFloat = buildcfg.GOMIPS64 == "softfloat"
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/noder/codes.go b/src/cmd/compile/internal/noder/codes.go
new file mode 100644
index 0000000000000000000000000000000000000000..f8cb7729acc2287a13f626d9ab8ce495701b6711
--- /dev/null
+++ b/src/cmd/compile/internal/noder/codes.go
@@ -0,0 +1,124 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+type code interface {
+	marker() syncMarker
+	value() int
+}
+
+type codeVal int
+
+func (c codeVal) marker() syncMarker { return syncVal }
+func (c codeVal) value() int         { return int(c) }
+
+const (
+	valBool codeVal = iota
+	valString
+	valInt64
+	valBigInt
+	valBigRat
+	valBigFloat
+)
+
+type codeType int
+
+func (c codeType) marker() syncMarker { return syncType }
+func (c codeType) value() int         { return int(c) }
+
+const (
+	typeBasic codeType = iota
+	typeNamed
+	typePointer
+	typeSlice
+	typeArray
+	typeChan
+	typeMap
+	typeSignature
+	typeStruct
+	typeInterface
+	typeUnion
+	typeTypeParam
+)
+
+type codeObj int
+
+func (c codeObj) marker() syncMarker { return syncCodeObj }
+func (c codeObj) value() int         { return int(c) }
+
+const (
+	objAlias codeObj = iota
+	objConst
+	objType
+	objFunc
+	objVar
+	objStub
+)
+
+type codeStmt int
+
+func (c codeStmt) marker() syncMarker { return syncStmt1 }
+func (c codeStmt) value() int         { return int(c) }
+
+const (
+	stmtEnd codeStmt = iota
+	stmtLabel
+	stmtBlock
+	stmtExpr
+	stmtSend
+	stmtAssign
+	stmtAssignOp
+	stmtIncDec
+	stmtBranch
+	stmtCall
+	stmtReturn
+	stmtIf
+	stmtFor
+	stmtSwitch
+	stmtSelect
+
+	// TODO(mdempsky): Remove after we don't care about toolstash -cmp.
+	stmtTypeDeclHack
+)
+
+type codeExpr int
+
+func (c codeExpr) marker() syncMarker { return syncExpr }
+func (c codeExpr) value() int         { return int(c) }
+
+// TODO(mdempsky): Split expr into addr, for lvalues.
+const (
+	exprNone codeExpr = iota
+	exprConst
+	exprType  // type expression
+	exprLocal // local variable
+	exprName  // global variable or function
+	exprBlank
+	exprCompLit
+	exprFuncLit
+	exprSelector
+	exprIndex
+	exprSlice
+	exprAssert
+	exprUnaryOp
+	exprBinaryOp
+	exprCall
+	exprConvert
+)
+
+type codeDecl int
+
+func (c codeDecl) marker() syncMarker { return syncDecl }
+func (c codeDecl) value() int         { return int(c) }
+
+const (
+	declEnd codeDecl = iota
+	declFunc
+	declMethod
+	declVar
+	declOther
+)
diff --git a/src/cmd/compile/internal/noder/decl.go b/src/cmd/compile/internal/noder/decl.go
index 4ca2eb4740a4916e171d2cfe278a38c9b472e9f1..b23dd47600898f3aa104790f406ae12f7055f74c 100644
--- a/src/cmd/compile/internal/noder/decl.go
+++ b/src/cmd/compile/internal/noder/decl.go
@@ -18,43 +18,48 @@ import (
 // TODO(mdempsky): Skip blank declarations? Probably only safe
 // for declarations without pragmas.
 
-func (g *irgen) decls(decls []syntax.Decl) []ir.Node {
-	var res ir.Nodes
+func (g *irgen) decls(res *ir.Nodes, decls []syntax.Decl) {
 	for _, decl := range decls {
 		switch decl := decl.(type) {
 		case *syntax.ConstDecl:
-			g.constDecl(&res, decl)
+			g.constDecl(res, decl)
 		case *syntax.FuncDecl:
-			g.funcDecl(&res, decl)
+			g.funcDecl(res, decl)
 		case *syntax.TypeDecl:
 			if ir.CurFunc == nil {
 				continue // already handled in irgen.generate
 			}
-			g.typeDecl(&res, decl)
+			g.typeDecl(res, decl)
 		case *syntax.VarDecl:
-			g.varDecl(&res, decl)
+			g.varDecl(res, decl)
 		default:
 			g.unhandled("declaration", decl)
 		}
 	}
-	return res
 }
 
 func (g *irgen) importDecl(p *noder, decl *syntax.ImportDecl) {
-	// TODO(mdempsky): Merge with gcimports so we don't have to import
-	// packages twice.
-
 	g.pragmaFlags(decl.Pragma, 0)
 
-	ipkg := importfile(decl)
-	if ipkg == ir.Pkgs.Unsafe {
+	// Get the imported package's path, as resolved already by types2
+	// and gcimporter. This is the same path as would be computed by
+	// parseImportPath.
+	switch pkgNameOf(g.info, decl).Imported().Path() {
+	case "unsafe":
 		p.importedUnsafe = true
-	}
-	if ipkg.Path == "embed" {
+	case "embed":
 		p.importedEmbed = true
 	}
 }
 
+// pkgNameOf returns the PkgName associated with the given ImportDecl.
+func pkgNameOf(info *types2.Info, decl *syntax.ImportDecl) *types2.PkgName {
+	if name := decl.LocalPkgName; name != nil {
+		return info.Defs[name].(*types2.PkgName)
+	}
+	return info.Implicits[decl].(*types2.PkgName)
+}
+
 func (g *irgen) constDecl(out *ir.Nodes, decl *syntax.ConstDecl) {
 	g.pragmaFlags(decl.Pragma, 0)
 
@@ -90,27 +95,54 @@ func (g *irgen) funcDecl(out *ir.Nodes, decl *syntax.FuncDecl) {
 	if fn.Pragma&ir.Systemstack != 0 && fn.Pragma&ir.Nosplit != 0 {
 		base.ErrorfAt(fn.Pos(), "go:nosplit and go:systemstack cannot be combined")
 	}
+	if fn.Pragma&ir.Nointerface != 0 {
+		// Propagate //go:nointerface from Func.Pragma to Field.Nointerface.
+		// This is a bit roundabout, but this is the earliest point where we've
+		// processed the function's pragma flags, and we've also already created
+		// the Fields to represent the receiver's method set.
+		if recv := fn.Type().Recv(); recv != nil {
+			typ := types.ReceiverBaseType(recv.Type)
+			if typ.OrigSym != nil {
+				// For a generic method, we mark the methods on the
+				// base generic type, since those are the methods
+				// that will be stenciled.
+				typ = typ.OrigSym.Def.Type()
+			}
+			meth := typecheck.Lookdot1(fn, typecheck.Lookup(decl.Name.Value), typ, typ.Methods(), 0)
+			meth.SetNointerface(true)
+		}
+	}
 
 	if decl.Name.Value == "init" && decl.Recv == nil {
 		g.target.Inits = append(g.target.Inits, fn)
 	}
 
-	g.funcBody(fn, decl.Recv, decl.Type, decl.Body)
+	g.later(func() {
+		if fn.Type().HasTParam() {
+			g.topFuncIsGeneric = true
+		}
+		g.funcBody(fn, decl.Recv, decl.Type, decl.Body)
+		g.topFuncIsGeneric = false
+		if fn.Type().HasTParam() && fn.Body != nil {
+			// Set pointers to the dcls/body of a generic function/method in
+			// the Inl struct, so it is marked for export, is available for
+			// stenciling, and works with Inline_Flood().
+			fn.Inl = &ir.Inline{
+				Cost: 1,
+				Dcl:  fn.Dcl,
+				Body: fn.Body,
+			}
+		}
 
-	out.Append(fn)
+		out.Append(fn)
+	})
 }
 
 func (g *irgen) typeDecl(out *ir.Nodes, decl *syntax.TypeDecl) {
 	if decl.Alias {
 		name, _ := g.def(decl.Name)
 		g.pragmaFlags(decl.Pragma, 0)
-
-		// TODO(mdempsky): This matches how typecheckdef marks aliases for
-		// export, but this won't generalize to exporting function-scoped
-		// type aliases. We should maybe just use n.Alias() instead.
-		if ir.CurFunc == nil {
-			name.Sym().Def = ir.TypeNode(name.Type())
-		}
+		assert(name.Alias()) // should be set by irgen.obj
 
 		out.Append(ir.NewDecl(g.pos(decl), ir.ODCLTYPE, name))
 		return
@@ -154,11 +186,15 @@ func (g *irgen) typeDecl(out *ir.Nodes, decl *syntax.TypeDecl) {
 	// [mdempsky: Subtleties like these are why I always vehemently
 	// object to new type pragmas.]
 	ntyp.SetUnderlying(g.typeExpr(decl.Type))
-	if len(decl.TParamList) > 0 {
-		// Set HasTParam if there are any tparams, even if no tparams are
-		// used in the type itself (e.g., if it is an empty struct, or no
-		// fields in the struct use the tparam).
-		ntyp.SetHasTParam(true)
+
+	tparams := otyp.(*types2.Named).TParams()
+	if n := tparams.Len(); n > 0 {
+		rparams := make([]*types.Type, n)
+		for i := range rparams {
+			rparams[i] = g.typ(tparams.At(i))
+		}
+		// This will set hasTParam flag if any rparams are not concrete types.
+		ntyp.SetRParams(rparams)
 	}
 	types.ResumeCheckSize()
 
@@ -182,7 +218,6 @@ func (g *irgen) varDecl(out *ir.Nodes, decl *syntax.VarDecl) {
 	for i, name := range decl.NameList {
 		names[i], _ = g.def(name)
 	}
-	values := g.exprList(decl.Values)
 
 	if decl.Pragma != nil {
 		pragma := decl.Pragma.(*pragmas)
@@ -191,44 +226,57 @@ func (g *irgen) varDecl(out *ir.Nodes, decl *syntax.VarDecl) {
 		g.reportUnused(pragma)
 	}
 
-	var as2 *ir.AssignListStmt
-	if len(values) != 0 && len(names) != len(values) {
-		as2 = ir.NewAssignListStmt(pos, ir.OAS2, make([]ir.Node, len(names)), values)
-	}
+	do := func() {
+		values := g.exprList(decl.Values)
 
-	for i, name := range names {
-		if ir.CurFunc != nil {
-			out.Append(ir.NewDecl(pos, ir.ODCL, name))
+		var as2 *ir.AssignListStmt
+		if len(values) != 0 && len(names) != len(values) {
+			as2 = ir.NewAssignListStmt(pos, ir.OAS2, make([]ir.Node, len(names)), values)
 		}
-		if as2 != nil {
-			as2.Lhs[i] = name
-			name.Defn = as2
-		} else {
-			as := ir.NewAssignStmt(pos, name, nil)
-			if len(values) != 0 {
-				as.Y = values[i]
-				name.Defn = as
-			} else if ir.CurFunc == nil {
-				name.Defn = as
-			}
-			lhs := []ir.Node{as.X}
-			rhs := []ir.Node{}
-			if as.Y != nil {
-				rhs = []ir.Node{as.Y}
+
+		for i, name := range names {
+			if ir.CurFunc != nil {
+				out.Append(ir.NewDecl(pos, ir.ODCL, name))
 			}
-			transformAssign(as, lhs, rhs)
-			as.X = lhs[0]
-			if as.Y != nil {
-				as.Y = rhs[0]
+			if as2 != nil {
+				as2.Lhs[i] = name
+				name.Defn = as2
+			} else {
+				as := ir.NewAssignStmt(pos, name, nil)
+				if len(values) != 0 {
+					as.Y = values[i]
+					name.Defn = as
+				} else if ir.CurFunc == nil {
+					name.Defn = as
+				}
+				lhs := []ir.Node{as.X}
+				rhs := []ir.Node{}
+				if as.Y != nil {
+					rhs = []ir.Node{as.Y}
+				}
+				transformAssign(as, lhs, rhs)
+				as.X = lhs[0]
+				if as.Y != nil {
+					as.Y = rhs[0]
+				}
+				as.SetTypecheck(1)
+				out.Append(as)
 			}
-			as.SetTypecheck(1)
-			out.Append(as)
+		}
+		if as2 != nil {
+			transformAssign(as2, as2.Lhs, as2.Rhs)
+			as2.SetTypecheck(1)
+			out.Append(as2)
 		}
 	}
-	if as2 != nil {
-		transformAssign(as2, as2.Lhs, as2.Rhs)
-		as2.SetTypecheck(1)
-		out.Append(as2)
+
+	// If we're within a function, we need to process the assignment
+	// part of the variable declaration right away. Otherwise, we leave
+	// it to be handled after all top-level declarations are processed.
+	if ir.CurFunc != nil {
+		do()
+	} else {
+		g.later(do)
 	}
 }
 
diff --git a/src/cmd/compile/internal/noder/decoder.go b/src/cmd/compile/internal/noder/decoder.go
new file mode 100644
index 0000000000000000000000000000000000000000..3dc61c6a69208e93dc0e745a5af2e334ff27cc0a
--- /dev/null
+++ b/src/cmd/compile/internal/noder/decoder.go
@@ -0,0 +1,301 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"math/big"
+	"os"
+	"runtime"
+	"strings"
+
+	"cmd/compile/internal/base"
+)
+
+type pkgDecoder struct {
+	pkgPath string
+
+	elemEndsEnds [numRelocs]uint32
+	elemEnds     []uint32
+	elemData     string
+}
+
+func newPkgDecoder(pkgPath, input string) pkgDecoder {
+	pr := pkgDecoder{
+		pkgPath: pkgPath,
+	}
+
+	// TODO(mdempsky): Implement direct indexing of input string to
+	// avoid copying the position information.
+
+	r := strings.NewReader(input)
+
+	assert(binary.Read(r, binary.LittleEndian, pr.elemEndsEnds[:]) == nil)
+
+	pr.elemEnds = make([]uint32, pr.elemEndsEnds[len(pr.elemEndsEnds)-1])
+	assert(binary.Read(r, binary.LittleEndian, pr.elemEnds[:]) == nil)
+
+	pos, err := r.Seek(0, os.SEEK_CUR)
+	assert(err == nil)
+
+	pr.elemData = input[pos:]
+	assert(len(pr.elemData) == int(pr.elemEnds[len(pr.elemEnds)-1]))
+
+	return pr
+}
+
+func (pr *pkgDecoder) numElems(k reloc) int {
+	count := int(pr.elemEndsEnds[k])
+	if k > 0 {
+		count -= int(pr.elemEndsEnds[k-1])
+	}
+	return count
+}
+
+func (pr *pkgDecoder) totalElems() int {
+	return len(pr.elemEnds)
+}
+
+func (pr *pkgDecoder) absIdx(k reloc, idx int) int {
+	absIdx := idx
+	if k > 0 {
+		absIdx += int(pr.elemEndsEnds[k-1])
+	}
+	if absIdx >= int(pr.elemEndsEnds[k]) {
+		base.Fatalf("%v:%v is out of bounds; %v", k, idx, pr.elemEndsEnds)
+	}
+	return absIdx
+}
+
+func (pr *pkgDecoder) dataIdx(k reloc, idx int) string {
+	absIdx := pr.absIdx(k, idx)
+
+	var start uint32
+	if absIdx > 0 {
+		start = pr.elemEnds[absIdx-1]
+	}
+	end := pr.elemEnds[absIdx]
+
+	return pr.elemData[start:end]
+}
+
+func (pr *pkgDecoder) stringIdx(idx int) string {
+	return pr.dataIdx(relocString, idx)
+}
+
+func (pr *pkgDecoder) newDecoder(k reloc, idx int, marker syncMarker) decoder {
+	r := pr.newDecoderRaw(k, idx)
+	r.sync(marker)
+	return r
+}
+
+func (pr *pkgDecoder) newDecoderRaw(k reloc, idx int) decoder {
+	r := decoder{
+		common: pr,
+		k:      k,
+		idx:    idx,
+	}
+
+	// TODO(mdempsky) r.data.Reset(...) after #44505 is resolved.
+	r.data = *strings.NewReader(pr.dataIdx(k, idx))
+
+	r.sync(syncRelocs)
+	r.relocs = make([]relocEnt, r.len())
+	for i := range r.relocs {
+		r.sync(syncReloc)
+		r.relocs[i] = relocEnt{reloc(r.len()), r.len()}
+	}
+
+	return r
+}
+
+type decoder struct {
+	common *pkgDecoder
+
+	relocs []relocEnt
+	data   strings.Reader
+
+	k   reloc
+	idx int
+}
+
+func (r *decoder) checkErr(err error) {
+	if err != nil {
+		base.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func (r *decoder) rawUvarint() uint64 {
+	x, err := binary.ReadUvarint(&r.data)
+	r.checkErr(err)
+	return x
+}
+
+func (r *decoder) rawVarint() int64 {
+	ux := r.rawUvarint()
+
+	// Zig-zag decode.
+	x := int64(ux >> 1)
+	if ux&1 != 0 {
+		x = ^x
+	}
+	return x
+}
+
+func (r *decoder) rawReloc(k reloc, idx int) int {
+	e := r.relocs[idx]
+	assert(e.kind == k)
+	return e.idx
+}
+
+func (r *decoder) sync(mWant syncMarker) {
+	if !enableSync {
+		return
+	}
+
+	pos, _ := r.data.Seek(0, os.SEEK_CUR) // TODO(mdempsky): io.SeekCurrent after #44505 is resolved
+	mHave := syncMarker(r.rawUvarint())
+	writerPCs := make([]int, r.rawUvarint())
+	for i := range writerPCs {
+		writerPCs[i] = int(r.rawUvarint())
+	}
+
+	if mHave == mWant {
+		return
+	}
+
+	// There's some tension here between printing:
+	//
+	// (1) full file paths that tools can recognize (e.g., so emacs
+	//     hyperlinks the "file:line" text for easy navigation), or
+	//
+	// (2) short file paths that are easier for humans to read (e.g., by
+	//     omitting redundant or irrelevant details, so it's easier to
+	//     focus on the useful bits that remain).
+	//
+	// The current formatting favors the former, as it seems more
+	// helpful in practice. But perhaps the formatting could be improved
+	// to better address both concerns. For example, use relative file
+	// paths if they would be shorter, or rewrite file paths to contain
+	// "$GOROOT" (like objabi.AbsFile does) if tools can be taught how
+	// to reliably expand that again.
+
+	fmt.Printf("export data desync: package %q, section %v, index %v, offset %v\n", r.common.pkgPath, r.k, r.idx, pos)
+
+	fmt.Printf("\nfound %v, written at:\n", mHave)
+	if len(writerPCs) == 0 {
+		fmt.Printf("\t[stack trace unavailable; recompile package %q with -d=syncframes]\n", r.common.pkgPath)
+	}
+	for _, pc := range writerPCs {
+		fmt.Printf("\t%s\n", r.common.stringIdx(r.rawReloc(relocString, pc)))
+	}
+
+	fmt.Printf("\nexpected %v, reading at:\n", mWant)
+	var readerPCs [32]uintptr // TODO(mdempsky): Dynamically size?
+	n := runtime.Callers(2, readerPCs[:])
+	for _, pc := range fmtFrames(readerPCs[:n]...) {
+		fmt.Printf("\t%s\n", pc)
+	}
+
+	// We already printed a stack trace for the reader, so now we can
+	// simply exit. Printing a second one with panic or base.Fatalf
+	// would just be noise.
+	os.Exit(1)
+}
+
+func (r *decoder) bool() bool {
+	r.sync(syncBool)
+	x, err := r.data.ReadByte()
+	r.checkErr(err)
+	assert(x < 2)
+	return x != 0
+}
+
+func (r *decoder) int64() int64 {
+	r.sync(syncInt64)
+	return r.rawVarint()
+}
+
+func (r *decoder) uint64() uint64 {
+	r.sync(syncUint64)
+	return r.rawUvarint()
+}
+
+func (r *decoder) len() int   { x := r.uint64(); v := int(x); assert(uint64(v) == x); return v }
+func (r *decoder) int() int   { x := r.int64(); v := int(x); assert(int64(v) == x); return v }
+func (r *decoder) uint() uint { x := r.uint64(); v := uint(x); assert(uint64(v) == x); return v }
+
+func (r *decoder) code(mark syncMarker) int {
+	r.sync(mark)
+	return r.len()
+}
+
+func (r *decoder) reloc(k reloc) int {
+	r.sync(syncUseReloc)
+	return r.rawReloc(k, r.len())
+}
+
+func (r *decoder) string() string {
+	r.sync(syncString)
+	return r.common.stringIdx(r.reloc(relocString))
+}
+
+func (r *decoder) strings() []string {
+	res := make([]string, r.len())
+	for i := range res {
+		res[i] = r.string()
+	}
+	return res
+}
+
+func (r *decoder) rawValue() constant.Value {
+	isComplex := r.bool()
+	val := r.scalar()
+	if isComplex {
+		val = constant.BinaryOp(val, token.ADD, constant.MakeImag(r.scalar()))
+	}
+	return val
+}
+
+func (r *decoder) scalar() constant.Value {
+	switch tag := codeVal(r.code(syncVal)); tag {
+	default:
+		panic(fmt.Sprintf("unexpected scalar tag: %v", tag))
+
+	case valBool:
+		return constant.MakeBool(r.bool())
+	case valString:
+		return constant.MakeString(r.string())
+	case valInt64:
+		return constant.MakeInt64(r.int64())
+	case valBigInt:
+		return constant.Make(r.bigInt())
+	case valBigRat:
+		num := r.bigInt()
+		denom := r.bigInt()
+		return constant.Make(new(big.Rat).SetFrac(num, denom))
+	case valBigFloat:
+		return constant.Make(r.bigFloat())
+	}
+}
+
+func (r *decoder) bigInt() *big.Int {
+	v := new(big.Int).SetBytes([]byte(r.string()))
+	if r.bool() {
+		v.Neg(v)
+	}
+	return v
+}
+
+func (r *decoder) bigFloat() *big.Float {
+	v := new(big.Float).SetPrec(512)
+	assert(v.UnmarshalText([]byte(r.string())) == nil)
+	return v
+}
diff --git a/src/cmd/compile/internal/noder/encoder.go b/src/cmd/compile/internal/noder/encoder.go
new file mode 100644
index 0000000000000000000000000000000000000000..d8ab0f6255dbca273a8b2af2e8d4a725d3302876
--- /dev/null
+++ b/src/cmd/compile/internal/noder/encoder.go
@@ -0,0 +1,284 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"io"
+	"math/big"
+	"runtime"
+
+	"cmd/compile/internal/base"
+)
+
+type pkgEncoder struct {
+	elems [numRelocs][]string
+
+	stringsIdx map[string]int
+}
+
+func newPkgEncoder() pkgEncoder {
+	return pkgEncoder{
+		stringsIdx: make(map[string]int),
+	}
+}
+
+func (pw *pkgEncoder) dump(out io.Writer) {
+	writeUint32 := func(x uint32) {
+		assert(binary.Write(out, binary.LittleEndian, x) == nil)
+	}
+
+	var sum uint32
+	for _, elems := range &pw.elems {
+		sum += uint32(len(elems))
+		writeUint32(sum)
+	}
+
+	sum = 0
+	for _, elems := range &pw.elems {
+		for _, elem := range elems {
+			sum += uint32(len(elem))
+			writeUint32(sum)
+		}
+	}
+
+	for _, elems := range &pw.elems {
+		for _, elem := range elems {
+			_, err := io.WriteString(out, elem)
+			assert(err == nil)
+		}
+	}
+}
+
+func (pw *pkgEncoder) stringIdx(s string) int {
+	if idx, ok := pw.stringsIdx[s]; ok {
+		assert(pw.elems[relocString][idx] == s)
+		return idx
+	}
+
+	idx := len(pw.elems[relocString])
+	pw.elems[relocString] = append(pw.elems[relocString], s)
+	pw.stringsIdx[s] = idx
+	return idx
+}
+
+func (pw *pkgEncoder) newEncoder(k reloc, marker syncMarker) encoder {
+	e := pw.newEncoderRaw(k)
+	e.sync(marker)
+	return e
+}
+
+func (pw *pkgEncoder) newEncoderRaw(k reloc) encoder {
+	idx := len(pw.elems[k])
+	pw.elems[k] = append(pw.elems[k], "") // placeholder
+
+	return encoder{
+		p:   pw,
+		k:   k,
+		idx: idx,
+	}
+}
+
+// Encoders
+
+type encoder struct {
+	p *pkgEncoder
+
+	relocs []relocEnt
+	data   bytes.Buffer
+
+	encodingRelocHeader bool
+
+	k   reloc
+	idx int
+}
+
+func (w *encoder) flush() int {
+	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
+
+	// Backup the data so we write the relocations at the front.
+	var tmp bytes.Buffer
+	io.Copy(&tmp, &w.data)
+
+	// TODO(mdempsky): Consider writing these out separately so they're
+	// easier to strip, along with function bodies, so that we can prune
+	// down to just the data that's relevant to go/types.
+	if w.encodingRelocHeader {
+		base.Fatalf("encodingRelocHeader already true; recursive flush?")
+	}
+	w.encodingRelocHeader = true
+	w.sync(syncRelocs)
+	w.len(len(w.relocs))
+	for _, rent := range w.relocs {
+		w.sync(syncReloc)
+		w.len(int(rent.kind))
+		w.len(rent.idx)
+	}
+
+	io.Copy(&sb, &w.data)
+	io.Copy(&sb, &tmp)
+	w.p.elems[w.k][w.idx] = sb.String()
+
+	return w.idx
+}
+
+func (w *encoder) checkErr(err error) {
+	if err != nil {
+		base.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func (w *encoder) rawUvarint(x uint64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(buf[:], x)
+	_, err := w.data.Write(buf[:n])
+	w.checkErr(err)
+}
+
+func (w *encoder) rawVarint(x int64) {
+	// Zig-zag encode.
+	ux := uint64(x) << 1
+	if x < 0 {
+		ux = ^ux
+	}
+
+	w.rawUvarint(ux)
+}
+
+func (w *encoder) rawReloc(r reloc, idx int) int {
+	// TODO(mdempsky): Use map for lookup.
+	for i, rent := range w.relocs {
+		if rent.kind == r && rent.idx == idx {
+			return i
+		}
+	}
+
+	i := len(w.relocs)
+	w.relocs = append(w.relocs, relocEnt{r, idx})
+	return i
+}
+
+func (w *encoder) sync(m syncMarker) {
+	if !enableSync {
+		return
+	}
+
+	// Writing out stack frame string references requires working
+	// relocations, but writing out the relocations themselves involves
+	// sync markers. To prevent infinite recursion, we simply trim the
+	// stack frame for sync markers within the relocation header.
+	var frames []string
+	if !w.encodingRelocHeader && base.Debug.SyncFrames > 0 {
+		pcs := make([]uintptr, base.Debug.SyncFrames)
+		n := runtime.Callers(2, pcs)
+		frames = fmtFrames(pcs[:n]...)
+	}
+
+	// TODO(mdempsky): Save space by writing out stack frames as a
+	// linked list so we can share common stack frames.
+	w.rawUvarint(uint64(m))
+	w.rawUvarint(uint64(len(frames)))
+	for _, frame := range frames {
+		w.rawUvarint(uint64(w.rawReloc(relocString, w.p.stringIdx(frame))))
+	}
+}
+
+func (w *encoder) bool(b bool) bool {
+	w.sync(syncBool)
+	var x byte
+	if b {
+		x = 1
+	}
+	err := w.data.WriteByte(x)
+	w.checkErr(err)
+	return b
+}
+
+func (w *encoder) int64(x int64) {
+	w.sync(syncInt64)
+	w.rawVarint(x)
+}
+
+func (w *encoder) uint64(x uint64) {
+	w.sync(syncUint64)
+	w.rawUvarint(x)
+}
+
+func (w *encoder) len(x int)   { assert(x >= 0); w.uint64(uint64(x)) }
+func (w *encoder) int(x int)   { w.int64(int64(x)) }
+func (w *encoder) uint(x uint) { w.uint64(uint64(x)) }
+
+func (w *encoder) reloc(r reloc, idx int) {
+	w.sync(syncUseReloc)
+	w.len(w.rawReloc(r, idx))
+}
+
+func (w *encoder) code(c code) {
+	w.sync(c.marker())
+	w.len(c.value())
+}
+
+func (w *encoder) string(s string) {
+	w.sync(syncString)
+	w.reloc(relocString, w.p.stringIdx(s))
+}
+
+func (w *encoder) strings(ss []string) {
+	w.len(len(ss))
+	for _, s := range ss {
+		w.string(s)
+	}
+}
+
+func (w *encoder) rawValue(val constant.Value) {
+	if w.bool(val.Kind() == constant.Complex) {
+		w.scalar(constant.Real(val))
+		w.scalar(constant.Imag(val))
+	} else {
+		w.scalar(val)
+	}
+}
+
+func (w *encoder) scalar(val constant.Value) {
+	switch v := constant.Val(val).(type) {
+	default:
+		panic(fmt.Sprintf("unhandled %v (%v)", val, val.Kind()))
+	case bool:
+		w.code(valBool)
+		w.bool(v)
+	case string:
+		w.code(valString)
+		w.string(v)
+	case int64:
+		w.code(valInt64)
+		w.int64(v)
+	case *big.Int:
+		w.code(valBigInt)
+		w.bigInt(v)
+	case *big.Rat:
+		w.code(valBigRat)
+		w.bigInt(v.Num())
+		w.bigInt(v.Denom())
+	case *big.Float:
+		w.code(valBigFloat)
+		w.bigFloat(v)
+	}
+}
+
+func (w *encoder) bigInt(v *big.Int) {
+	b := v.Bytes()
+	w.string(string(b)) // TODO: More efficient encoding.
+	w.bool(v.Sign() < 0)
+}
+
+func (w *encoder) bigFloat(v *big.Float) {
+	b := v.Append(nil, 'p', -1)
+	w.string(string(b)) // TODO: More efficient encoding.
+}
diff --git a/src/cmd/compile/internal/noder/export.go b/src/cmd/compile/internal/noder/export.go
new file mode 100644
index 0000000000000000000000000000000000000000..1a296e22c8489b803fedf0ed2965daa1fe8be5c1
--- /dev/null
+++ b/src/cmd/compile/internal/noder/export.go
@@ -0,0 +1,65 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/typecheck"
+	"cmd/internal/bio"
+)
+
+// writeNewExportFunc is a hook that can be added to append extra
+// export data after the normal export data section. It allows
+// experimenting with new export data format designs without requiring
+// immediate support in the go/internal or x/tools importers.
+var writeNewExportFunc func(out io.Writer)
+
+func WriteExports(out *bio.Writer) {
+	// When unified IR exports are enable, we simply append it to the
+	// end of the normal export data (with compiler extensions
+	// disabled), and write an extra header giving its size.
+	//
+	// If the compiler sees this header, it knows to read the new data
+	// instead; meanwhile the go/types importers will silently ignore it
+	// and continue processing the old export instead.
+	//
+	// This allows us to experiment with changes to the new export data
+	// format without needing to update the go/internal/gcimporter or
+	// (worse) x/tools/go/gcexportdata.
+
+	useNewExport := writeNewExportFunc != nil
+
+	var old, new bytes.Buffer
+
+	typecheck.WriteExports(&old, !useNewExport)
+
+	if useNewExport {
+		writeNewExportFunc(&new)
+	}
+
+	oldLen := old.Len()
+	newLen := new.Len()
+
+	if useNewExport {
+		fmt.Fprintf(out, "\nnewexportsize %v\n", newLen)
+	}
+
+	// The linker also looks for the $$ marker - use char after $$ to distinguish format.
+	out.WriteString("\n$$B\n") // indicate binary export format
+	io.Copy(out, &old)
+	out.WriteString("\n$$\n")
+	io.Copy(out, &new)
+
+	if base.Debug.Export != 0 {
+		fmt.Printf("BenchmarkExportSize:%s 1 %d bytes\n", base.Ctxt.Pkgpath, oldLen)
+		if useNewExport {
+			fmt.Printf("BenchmarkNewExportSize:%s 1 %d bytes\n", base.Ctxt.Pkgpath, newLen)
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/noder/expr.go b/src/cmd/compile/internal/noder/expr.go
index c7695ed920435291bab7c64a0cbfdfb08b8b8a7e..58637dca39cb27afe89b457c56c615f3e90b7f56 100644
--- a/src/cmd/compile/internal/noder/expr.go
+++ b/src/cmd/compile/internal/noder/expr.go
@@ -5,6 +5,8 @@
 package noder
 
 import (
+	"fmt"
+
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/syntax"
@@ -15,6 +17,8 @@ import (
 )
 
 func (g *irgen) expr(expr syntax.Expr) ir.Node {
+	expr = unparen(expr) // skip parens; unneeded after parse+typecheck
+
 	if expr == nil {
 		return nil
 	}
@@ -46,6 +50,8 @@ func (g *irgen) expr(expr syntax.Expr) ir.Node {
 		base.FatalfAt(g.pos(expr), "unrecognized type-checker result")
 	}
 
+	base.Assert(g.exprStmtOK)
+
 	// The gc backend expects all expressions to have a concrete type, and
 	// types2 mostly satisfies this expectation already. But there are a few
 	// cases where the Go spec doesn't require converting to concrete type,
@@ -67,14 +73,16 @@ func (g *irgen) expr(expr syntax.Expr) ir.Node {
 
 	// Constant expression.
 	if tv.Value != nil {
-		return Const(g.pos(expr), g.typ(typ), tv.Value)
+		typ := g.typ(typ)
+		value := FixValue(typ, tv.Value)
+		return OrigConst(g.pos(expr), typ, value, constExprOp(expr), syntax.String(expr))
 	}
 
 	n := g.expr0(typ, expr)
 	if n.Typecheck() != 1 && n.Typecheck() != 3 {
 		base.FatalfAt(g.pos(expr), "missed typecheck: %+v", n)
 	}
-	if !g.match(n.Type(), typ, tv.HasOk()) {
+	if n.Op() != ir.OFUNCINST && !g.match(n.Type(), typ, tv.HasOk()) {
 		base.FatalfAt(g.pos(expr), "expected %L to have type %v", n, typ)
 	}
 	return n
@@ -82,6 +90,11 @@ func (g *irgen) expr(expr syntax.Expr) ir.Node {
 
 func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 	pos := g.pos(expr)
+	assert(pos.IsKnown())
+
+	// Set base.Pos for transformation code that still uses base.Pos, rather than
+	// the pos of the node being converted.
+	base.Pos = pos
 
 	switch expr := expr.(type) {
 	case *syntax.Name:
@@ -105,23 +118,30 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 		// The key for the Inferred map is the CallExpr (if inferring
 		// types required the function arguments) or the IndexExpr below
 		// (if types could be inferred without the function arguments).
-		if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.Targs) > 0 {
+		if inferred, ok := g.info.Inferred[expr]; ok && inferred.TArgs.Len() > 0 {
 			// This is the case where inferring types required the
 			// types of the function arguments.
-			targs := make([]ir.Node, len(inferred.Targs))
-			for i, targ := range inferred.Targs {
-				targs[i] = ir.TypeNode(g.typ(targ))
+			targs := make([]ir.Node, inferred.TArgs.Len())
+			for i := range targs {
+				targs[i] = ir.TypeNode(g.typ(inferred.TArgs.At(i)))
 			}
 			if fun.Op() == ir.OFUNCINST {
 				// Replace explicit type args with the full list that
-				// includes the additional inferred type args
+				// includes the additional inferred type args.
+				// Substitute the type args for the type params in
+				// the generic function's type.
 				fun.(*ir.InstExpr).Targs = targs
+				newt := g.substType(fun.Type(), fun.Type().TParams(), targs)
+				typed(newt, fun)
 			} else {
-				// Create a function instantiation here, given
-				// there are only inferred type args (e.g.
-				// min(5,6), where min is a generic function)
+				// Create a function instantiation here, given there
+				// are only inferred type args (e.g. min(5,6), where
+				// min is a generic function). Substitute the type
+				// args for the type params in the generic function's
+				// type.
 				inst := ir.NewInstExpr(pos, ir.OFUNCINST, fun, targs)
-				typed(fun.Type(), inst)
+				newt := g.substType(fun.Type(), fun.Type().TParams(), targs)
+				typed(newt, inst)
 				fun = inst
 			}
 
@@ -131,13 +151,13 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 	case *syntax.IndexExpr:
 		var targs []ir.Node
 
-		if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.Targs) > 0 {
+		if inferred, ok := g.info.Inferred[expr]; ok && inferred.TArgs.Len() > 0 {
 			// This is the partial type inference case where the types
 			// can be inferred from other type arguments without using
 			// the types of the function arguments.
-			targs = make([]ir.Node, len(inferred.Targs))
-			for i, targ := range inferred.Targs {
-				targs[i] = ir.TypeNode(g.typ(targ))
+			targs = make([]ir.Node, inferred.TArgs.Len())
+			for i := range targs {
+				targs[i] = ir.TypeNode(g.typ(inferred.TArgs.At(i)))
 			}
 		} else if _, ok := expr.Index.(*syntax.ListExpr); ok {
 			targs = g.exprList(expr.Index)
@@ -158,12 +178,16 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 			panic("Incorrect argument for generic func instantiation")
 		}
 		n := ir.NewInstExpr(pos, ir.OFUNCINST, x, targs)
-		typed(g.typ(typ), n)
+		newt := g.typ(typ)
+		// Substitute the type args for the type params in the uninstantiated
+		// function's type. If there aren't enough type args, then the rest
+		// will be inferred at the call node, so don't try the substitution yet.
+		if x.Type().TParams().NumFields() == len(targs) {
+			newt = g.substType(g.typ(typ), x.Type().TParams(), targs)
+		}
+		typed(newt, n)
 		return n
 
-	case *syntax.ParenExpr:
-		return g.expr(expr.X) // skip parens; unneeded after parse+typecheck
-
 	case *syntax.SelectorExpr:
 		// Qualified identifier.
 		if name, ok := expr.X.(*syntax.Name); ok {
@@ -193,7 +217,29 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 	}
 }
 
-// selectorExpr resolves the choice of ODOT, ODOTPTR, OCALLPART (eventually
+// substType does a normal type substition, but tparams is in the form of a field
+// list, and targs is in terms of a slice of type nodes. substType records any newly
+// instantiated types into g.instTypeList.
+func (g *irgen) substType(typ *types.Type, tparams *types.Type, targs []ir.Node) *types.Type {
+	fields := tparams.FieldSlice()
+	tparams1 := make([]*types.Type, len(fields))
+	for i, f := range fields {
+		tparams1[i] = f.Type
+	}
+	targs1 := make([]*types.Type, len(targs))
+	for i, n := range targs {
+		targs1[i] = n.Type()
+	}
+	ts := typecheck.Tsubster{
+		Tparams: tparams1,
+		Targs:   targs1,
+	}
+	newt := ts.Typ(typ)
+	g.instTypeList = append(g.instTypeList, ts.InstTypeList...)
+	return newt
+}
+
+// selectorExpr resolves the choice of ODOT, ODOTPTR, OMETHVALUE (eventually
 // ODOTMETH & ODOTINTER), and OMETHEXPR and deals with embedded fields here rather
 // than in typecheck.go.
 func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.SelectorExpr) ir.Node {
@@ -203,6 +249,44 @@ func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.Selecto
 		// only be fully transformed once it has an instantiated type.
 		n := ir.NewSelectorExpr(pos, ir.OXDOT, x, typecheck.Lookup(expr.Sel.Value))
 		typed(g.typ(typ), n)
+
+		// Fill in n.Selection for a generic method reference or a bound
+		// interface method, even though we won't use it directly, since it
+		// is useful for analysis. Specifically do not fill in for fields or
+		// other interfaces methods (method call on an interface value), so
+		// n.Selection being non-nil means a method reference for a generic
+		// type or a method reference due to a bound.
+		obj2 := g.info.Selections[expr].Obj()
+		sig := types2.AsSignature(obj2.Type())
+		if sig == nil || sig.Recv() == nil {
+			return n
+		}
+		index := g.info.Selections[expr].Index()
+		last := index[len(index)-1]
+		// recvType is the receiver of the method being called.  Because of the
+		// way methods are imported, g.obj(obj2) doesn't work across
+		// packages, so we have to lookup the method via the receiver type.
+		recvType := deref2(sig.Recv().Type())
+		if types2.AsInterface(recvType.Underlying()) != nil {
+			fieldType := n.X.Type()
+			for _, ix := range index[:len(index)-1] {
+				fieldType = fieldType.Field(ix).Type
+			}
+			if fieldType.Kind() == types.TTYPEPARAM {
+				n.Selection = fieldType.Bound().AllMethods().Index(last)
+				//fmt.Printf(">>>>> %v: Bound call %v\n", base.FmtPos(pos), n.Sel)
+			} else {
+				assert(fieldType.Kind() == types.TINTER)
+				//fmt.Printf(">>>>> %v: Interface call %v\n", base.FmtPos(pos), n.Sel)
+			}
+			return n
+		}
+
+		recvObj := types2.AsNamed(recvType).Obj()
+		recv := g.pkg(recvObj.Pkg()).Lookup(recvObj.Name()).Def
+		n.Selection = recv.Type().Methods().Index(last)
+		//fmt.Printf(">>>>> %v: Method call %v\n", base.FmtPos(pos), n.Sel)
+
 		return n
 	}
 
@@ -259,14 +343,18 @@ func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.Selecto
 			if wantPtr {
 				recvType2Base = types2.AsPointer(recvType2).Elem()
 			}
-			if len(types2.AsNamed(recvType2Base).TParams()) > 0 {
+			if types2.AsNamed(recvType2Base).TParams().Len() > 0 {
 				// recvType2 is the original generic type that is
 				// instantiated for this method call.
 				// selinfo.Recv() is the instantiated type
 				recvType2 = recvType2Base
-				// method is the generic method associated with the gen type
-				method := g.obj(types2.AsNamed(recvType2).Method(last))
-				n = ir.NewSelectorExpr(pos, ir.OCALLPART, x, method.Sym())
+				recvTypeSym := g.pkg(method2.Pkg()).Lookup(recvType2.(*types2.Named).Obj().Name())
+				recvType := recvTypeSym.Def.(*ir.Name).Type()
+				// method is the generic method associated with
+				// the base generic type. The instantiated type may not
+				// have method bodies filled in, if it was imported.
+				method := recvType.Methods().Index(last).Nname.(*ir.Name)
+				n = ir.NewSelectorExpr(pos, ir.OMETHVALUE, x, typecheck.Lookup(expr.Sel.Value))
 				n.(*ir.SelectorExpr).Selection = types.NewField(pos, method.Sym(), method.Type())
 				n.(*ir.SelectorExpr).Selection.Nname = method
 				typed(method.Type(), n)
@@ -274,9 +362,9 @@ func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.Selecto
 				// selinfo.Targs() are the types used to
 				// instantiate the type of receiver
 				targs2 := getTargs(selinfo)
-				targs := make([]ir.Node, len(targs2))
-				for i, targ2 := range targs2 {
-					targs[i] = ir.TypeNode(g.typ(targ2))
+				targs := make([]ir.Node, targs2.Len())
+				for i := range targs {
+					targs[i] = ir.TypeNode(g.typ(targs2.At(i)))
 				}
 
 				// Create function instantiation with the type
@@ -300,11 +388,8 @@ func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.Selecto
 }
 
 // getTargs gets the targs associated with the receiver of a selected method
-func getTargs(selinfo *types2.Selection) []types2.Type {
-	r := selinfo.Recv()
-	if p := types2.AsPointer(r); p != nil {
-		r = p.Elem()
-	}
+func getTargs(selinfo *types2.Selection) *types2.TypeList {
+	r := deref2(selinfo.Recv())
 	n := types2.AsNamed(r)
 	if n == nil {
 		base.Fatalf("Incorrect type for selinfo %v", selinfo)
@@ -313,13 +398,17 @@ func getTargs(selinfo *types2.Selection) []types2.Type {
 }
 
 func (g *irgen) exprList(expr syntax.Expr) []ir.Node {
+	return g.exprs(unpackListExpr(expr))
+}
+
+func unpackListExpr(expr syntax.Expr) []syntax.Expr {
 	switch expr := expr.(type) {
 	case nil:
 		return nil
 	case *syntax.ListExpr:
-		return g.exprs(expr.ElemList)
+		return expr.ElemList
 	default:
-		return []ir.Node{g.expr(expr)}
+		return []syntax.Expr{expr}
 	}
 }
 
@@ -344,11 +433,13 @@ func (g *irgen) compLit(typ types2.Type, lit *syntax.CompositeLit) ir.Node {
 	for i, elem := range lit.ElemList {
 		switch elem := elem.(type) {
 		case *syntax.KeyValueExpr:
+			var key ir.Node
 			if isStruct {
-				exprs[i] = ir.NewStructKeyExpr(g.pos(elem), g.name(elem.Key.(*syntax.Name)), g.expr(elem.Value))
+				key = ir.NewIdent(g.pos(elem.Key), g.name(elem.Key.(*syntax.Name)))
 			} else {
-				exprs[i] = ir.NewKeyExpr(g.pos(elem), g.expr(elem.Key), g.expr(elem.Value))
+				key = g.expr(elem.Key)
 			}
+			exprs[i] = ir.NewKeyExpr(g.pos(elem), key, g.expr(elem.Value))
 		default:
 			exprs[i] = g.expr(elem)
 		}
@@ -360,19 +451,13 @@ func (g *irgen) compLit(typ types2.Type, lit *syntax.CompositeLit) ir.Node {
 }
 
 func (g *irgen) funcLit(typ2 types2.Type, expr *syntax.FuncLit) ir.Node {
-	fn := ir.NewFunc(g.pos(expr))
-	fn.SetIsHiddenClosure(ir.CurFunc != nil)
+	fn := ir.NewClosureFunc(g.pos(expr), ir.CurFunc != nil)
+	ir.NameClosure(fn.OClosure, ir.CurFunc)
 
-	fn.Nname = ir.NewNameAt(g.pos(expr), typecheck.ClosureName(ir.CurFunc))
-	ir.MarkFunc(fn.Nname)
 	typ := g.typ(typ2)
-	fn.Nname.Func = fn
-	fn.Nname.Defn = fn
 	typed(typ, fn.Nname)
-	fn.SetTypecheck(1)
-
-	fn.OClosure = ir.NewClosureExpr(g.pos(expr), fn)
 	typed(typ, fn.OClosure)
+	fn.SetTypecheck(1)
 
 	g.funcBody(fn, nil, expr.Type, expr.Body)
 
@@ -386,9 +471,14 @@ func (g *irgen) funcLit(typ2 types2.Type, expr *syntax.FuncLit) ir.Node {
 		cv.SetWalkdef(1)
 	}
 
-	g.target.Decls = append(g.target.Decls, fn)
-
-	return fn.OClosure
+	if g.topFuncIsGeneric {
+		// Don't add any closure inside a generic function/method to the
+		// g.target.Decls list, even though it may not be generic itself.
+		// See issue #47514.
+		return ir.UseClosure(fn.OClosure, nil)
+	} else {
+		return ir.UseClosure(fn.OClosure, g.target)
+	}
 }
 
 func (g *irgen) typeExpr(typ syntax.Expr) *types.Type {
@@ -398,3 +488,35 @@ func (g *irgen) typeExpr(typ syntax.Expr) *types.Type {
 	}
 	return n.Type()
 }
+
+// constExprOp returns an ir.Op that represents the outermost
+// operation of the given constant expression. It's intended for use
+// with ir.RawOrigExpr.
+func constExprOp(expr syntax.Expr) ir.Op {
+	switch expr := expr.(type) {
+	default:
+		panic(fmt.Sprintf("%s: unexpected expression: %T", expr.Pos(), expr))
+
+	case *syntax.BasicLit:
+		return ir.OLITERAL
+	case *syntax.Name, *syntax.SelectorExpr:
+		return ir.ONAME
+	case *syntax.CallExpr:
+		return ir.OCALL
+	case *syntax.Operation:
+		if expr.Y == nil {
+			return unOps[expr.Op]
+		}
+		return binOps[expr.Op]
+	}
+}
+
+func unparen(expr syntax.Expr) syntax.Expr {
+	for {
+		paren, ok := expr.(*syntax.ParenExpr)
+		if !ok {
+			return expr
+		}
+		expr = paren.X
+	}
+}
diff --git a/src/cmd/compile/internal/noder/frames_go1.go b/src/cmd/compile/internal/noder/frames_go1.go
new file mode 100644
index 0000000000000000000000000000000000000000..d00e0f51f9f8f8d4fda8dc9fe3a26d6b8fb13332
--- /dev/null
+++ b/src/cmd/compile/internal/noder/frames_go1.go
@@ -0,0 +1,21 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.7
+// +build !go1.7
+
+// TODO(mdempsky): Remove after #44505 is resolved
+
+package noder
+
+import "runtime"
+
+func walkFrames(pcs []uintptr, visit frameVisitor) {
+	for _, pc := range pcs {
+		fn := runtime.FuncForPC(pc)
+		file, line := fn.FileLine(pc)
+
+		visit(file, line, fn.Name(), pc-fn.Entry())
+	}
+}
diff --git a/src/cmd/compile/internal/noder/frames_go17.go b/src/cmd/compile/internal/noder/frames_go17.go
new file mode 100644
index 0000000000000000000000000000000000000000..48d77625b41d11105e73f218164c3c3395832574
--- /dev/null
+++ b/src/cmd/compile/internal/noder/frames_go17.go
@@ -0,0 +1,25 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.7
+// +build go1.7
+
+package noder
+
+import "runtime"
+
+func walkFrames(pcs []uintptr, visit frameVisitor) {
+	if len(pcs) == 0 {
+		return
+	}
+
+	frames := runtime.CallersFrames(pcs)
+	for {
+		frame, more := frames.Next()
+		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)
+		if !more {
+			return
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/noder/helpers.go b/src/cmd/compile/internal/noder/helpers.go
index 9da0e493007a0687899eb59fe64f2eaa03d95e0c..9487e76336cea7f8938ebd8ee288ea8751d6e613 100644
--- a/src/cmd/compile/internal/noder/helpers.go
+++ b/src/cmd/compile/internal/noder/helpers.go
@@ -43,6 +43,32 @@ func Const(pos src.XPos, typ *types.Type, val constant.Value) ir.Node {
 	return typed(typ, ir.NewBasicLit(pos, val))
 }
 
+func OrigConst(pos src.XPos, typ *types.Type, val constant.Value, op ir.Op, raw string) ir.Node {
+	orig := ir.NewRawOrigExpr(pos, op, raw)
+	return ir.NewConstExpr(val, typed(typ, orig))
+}
+
+// FixValue returns val after converting and truncating it as
+// appropriate for typ.
+func FixValue(typ *types.Type, val constant.Value) constant.Value {
+	assert(typ.Kind() != types.TFORW)
+	switch {
+	case typ.IsInteger():
+		val = constant.ToInt(val)
+	case typ.IsFloat():
+		val = constant.ToFloat(val)
+	case typ.IsComplex():
+		val = constant.ToComplex(val)
+	}
+	if !typ.IsUntyped() {
+		val = typecheck.DefaultLit(ir.NewBasicLit(src.NoXPos, val), typ).Val()
+	}
+	if !typ.IsTypeParam() {
+		ir.AssertValidTypeForConst(typ, val)
+	}
+	return val
+}
+
 func Nil(pos src.XPos, typ *types.Type) ir.Node {
 	return typed(typ, ir.NewNilExpr(pos))
 }
@@ -87,15 +113,15 @@ func Binary(pos src.XPos, op ir.Op, typ *types.Type, x, y ir.Node) ir.Node {
 func Call(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool) ir.Node {
 	n := ir.NewCallExpr(pos, ir.OCALL, fun, args)
 	n.IsDDD = dots
-	// n.Use will be changed to ir.CallUseStmt in g.stmt() if this call is
-	// just a statement (any return values are ignored).
-	n.Use = ir.CallUseExpr
 
 	if fun.Op() == ir.OTYPE {
 		// Actually a type conversion, not a function call.
-		if fun.Type().HasTParam() || args[0].Type().HasTParam() {
-			// For type params, don't typecheck until we actually know
-			// the type.
+		if !fun.Type().IsInterface() &&
+			(fun.Type().HasTParam() || args[0].Type().HasTParam()) {
+			// For type params, we can transform if fun.Type() is known
+			// to be an interface (in which case a CONVIFACE node will be
+			// inserted). Otherwise, don't typecheck until we actually
+			// know the type.
 			return typed(typ, n)
 		}
 		typed(typ, n)
@@ -103,24 +129,27 @@ func Call(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool)
 	}
 
 	if fun, ok := fun.(*ir.Name); ok && fun.BuiltinOp != 0 {
-		// For Builtin ops, we currently stay with using the old
-		// typechecker to transform the call to a more specific expression
-		// and possibly use more specific ops. However, for a bunch of the
-		// ops, we delay doing the old typechecker if any of the args have
-		// type params, for a variety of reasons:
-		//
-		// OMAKE: hard to choose specific ops OMAKESLICE, etc. until arg type is known
-		// OREAL/OIMAG: can't determine type float32/float64 until arg type know
-		// OLEN/OCAP: old typechecker will complain if arg is not obviously a slice/array.
-		// OAPPEND: old typechecker will complain if arg is not obviously slice, etc.
+		// For most Builtin ops, we delay doing transformBuiltin if any of the
+		// args have type params, for a variety of reasons:
 		//
-		// We will eventually break out the transforming functionality
-		// needed for builtin's, and call it here or during stenciling, as
-		// appropriate.
+		// OMAKE: transformMake can't choose specific ops OMAKESLICE, etc.
+		//    until arg type is known
+		// OREAL/OIMAG: transformRealImag can't determine type float32/float64
+		//    until arg type known
+		// OAPPEND: transformAppend requires that the arg is a slice
+		// ODELETE: transformDelete requires that the arg is a map
+		// OALIGNOF, OSIZEOF: can be eval'ed to a constant until types known.
 		switch fun.BuiltinOp {
-		case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OLEN, ir.OCAP, ir.OAPPEND:
+		case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.ODELETE, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
 			hasTParam := false
 			for _, arg := range args {
+				if fun.BuiltinOp == ir.OOFFSETOF {
+					// It's the type of left operand of the
+					// selection that matters, not the type of
+					// the field itself (which is irrelevant for
+					// offsetof).
+					arg = arg.(*ir.SelectorExpr).X
+				}
 				if arg.Type().HasTParam() {
 					hasTParam = true
 					break
@@ -137,10 +166,8 @@ func Call(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool)
 
 	// Add information, now that we know that fun is actually being called.
 	switch fun := fun.(type) {
-	case *ir.ClosureExpr:
-		fun.Func.SetClosureCalled(true)
 	case *ir.SelectorExpr:
-		if fun.Op() == ir.OCALLPART {
+		if fun.Op() == ir.OMETHVALUE {
 			op := ir.ODOTMETH
 			if fun.X.Type().IsInterface() {
 				op = ir.ODOTINTER
@@ -152,46 +179,52 @@ func Call(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool)
 		}
 	}
 
-	if fun.Type().HasTParam() {
-		// If the fun arg is or has a type param, don't do any extra
+	if fun.Type().HasTParam() || fun.Op() == ir.OXDOT || fun.Op() == ir.OFUNCINST {
+		// If the fun arg is or has a type param, we can't do all the
 		// transformations, since we may not have needed properties yet
-		// (e.g. number of return values, etc). The type param is probably
-		// described by a structural constraint that requires it to be a
-		// certain function type, etc., but we don't want to analyze that.
-		return typed(typ, n)
-	}
-
-	if fun.Op() == ir.OXDOT {
-		if !fun.(*ir.SelectorExpr).X.Type().HasTParam() {
-			base.FatalfAt(pos, "Expecting type param receiver in %v", fun)
+		// (e.g. number of return values, etc). The same applies if a fun
+		// which is an XDOT could not be transformed yet because of a generic
+		// type in the X of the selector expression.
+		//
+		// A function instantiation (even if fully concrete) shouldn't be
+		// transformed yet, because we need to add the dictionary during the
+		// transformation.
+		//
+		// However, if we have a function type (even though it is
+		// parameterized), then we can add in any needed CONVIFACE nodes via
+		// typecheckaste(). We need to call transformArgs() to deal first
+		// with the f(g(()) case where g returns multiple return values. We
+		// can't do anything if fun is a type param (which is probably
+		// described by a structural constraint)
+		if fun.Type().Kind() == types.TFUNC {
+			transformArgs(n)
+			typecheckaste(ir.OCALL, fun, n.IsDDD, fun.Type().Params(), n.Args, true)
 		}
-		// For methods called in a generic function, don't do any extra
-		// transformations. We will do those later when we create the
-		// instantiated function and have the correct receiver type.
-		typed(typ, n)
-		return n
-	}
-	if fun.Op() != ir.OFUNCINST {
-		// If no type params, do the normal call transformations. This
-		// will convert OCALL to OCALLFUNC.
-		typed(typ, n)
-		transformCall(n)
-		return n
+		return typed(typ, n)
 	}
 
-	// Leave the op as OCALL, which indicates the call still needs typechecking.
+	// If no type params, do the normal call transformations. This
+	// will convert OCALL to OCALLFUNC.
 	typed(typ, n)
+	transformCall(n)
 	return n
 }
 
 func Compare(pos src.XPos, typ *types.Type, op ir.Op, x, y ir.Node) ir.Node {
 	n := ir.NewBinaryExpr(pos, op, x, y)
 	if x.Type().HasTParam() || y.Type().HasTParam() {
-		// Delay transformCompare() if either arg has a type param, since
-		// it needs to know the exact types to decide on any needed conversions.
-		n.SetType(typ)
-		n.SetTypecheck(3)
-		return n
+		xIsInt := x.Type().IsInterface()
+		yIsInt := y.Type().IsInterface()
+		if !(xIsInt && !yIsInt || !xIsInt && yIsInt) {
+			// If either arg is a type param, then we can still do the
+			// transformCompare() if we know that one arg is an interface
+			// and the other is not. Otherwise, we delay
+			// transformCompare(), since it needs to know the exact types
+			// to decide on any needed conversions.
+			n.SetType(typ)
+			n.SetTypecheck(3)
+			return n
+		}
 	}
 	typed(typ, n)
 	transformCompare(n)
@@ -225,7 +258,7 @@ func DotMethod(pos src.XPos, x ir.Node, index int) *ir.SelectorExpr {
 
 	// Method value.
 	typ := typecheck.NewMethodType(method.Type, nil)
-	return dot(pos, typ, ir.OCALLPART, x, method)
+	return dot(pos, typ, ir.OMETHVALUE, x, method)
 }
 
 // MethodExpr returns a OMETHEXPR node with the indicated index into the methods
@@ -321,5 +354,15 @@ var one = constant.MakeInt64(1)
 
 func IncDec(pos src.XPos, op ir.Op, x ir.Node) *ir.AssignOpStmt {
 	assert(x.Type() != nil)
-	return ir.NewAssignOpStmt(pos, op, x, typecheck.DefaultLit(ir.NewBasicLit(pos, one), x.Type()))
+	bl := ir.NewBasicLit(pos, one)
+	if x.Type().HasTParam() {
+		// If the operand is generic, then types2 will have proved it must be
+		// a type that fits with increment/decrement, so just set the type of
+		// "one" to n.Type(). This works even for types that are eventually
+		// float or complex.
+		typed(x.Type(), bl)
+	} else {
+		bl = typecheck.DefaultLit(bl, x.Type())
+	}
+	return ir.NewAssignOpStmt(pos, op, x, bl)
 }
diff --git a/src/cmd/compile/internal/noder/import.go b/src/cmd/compile/internal/noder/import.go
index 701e9001c859ea8d2819b0e2850a1604e8e0c978..48f0e4802849b01ea98a69f473b5d057b4b4d8fb 100644
--- a/src/cmd/compile/internal/noder/import.go
+++ b/src/cmd/compile/internal/noder/import.go
@@ -8,7 +8,6 @@ import (
 	"errors"
 	"fmt"
 	"internal/buildcfg"
-	"io"
 	"os"
 	pathpkg "path"
 	"runtime"
@@ -32,8 +31,24 @@ import (
 	"cmd/internal/src"
 )
 
-// Temporary import helper to get type2-based type-checking going.
+// haveLegacyImports records whether we've imported any packages
+// without a new export data section. This is useful for experimenting
+// with new export data format designs, when you need to support
+// existing tests that manually compile files with inconsistent
+// compiler flags.
+var haveLegacyImports = false
+
+// newReadImportFunc is an extension hook for experimenting with new
+// export data formats. If a new export data payload was written out
+// for an imported package by overloading writeNewExportFunc, then
+// that payload will be mapped into memory and passed to
+// newReadImportFunc.
+var newReadImportFunc = func(data string, pkg1 *types.Pkg, check *types2.Checker, packages map[string]*types2.Package) (pkg2 *types2.Package, err error) {
+	panic("unexpected new export data payload")
+}
+
 type gcimports struct {
+	check    *types2.Checker
 	packages map[string]*types2.Package
 }
 
@@ -46,13 +61,8 @@ func (m *gcimports) ImportFrom(path, srcDir string, mode types2.ImportMode) (*ty
 		panic("mode must be 0")
 	}
 
-	path, err := resolveImportPath(path)
-	if err != nil {
-		return nil, err
-	}
-
-	lookup := func(path string) (io.ReadCloser, error) { return openPackage(path) }
-	return importer.Import(m.packages, path, srcDir, lookup)
+	_, pkg, err := readImportFile(path, typecheck.Target, m.check, m.packages)
+	return pkg, err
 }
 
 func isDriveLetter(b byte) bool {
@@ -175,160 +185,242 @@ func resolveImportPath(path string) (string, error) {
 	return path, nil
 }
 
-// TODO(mdempsky): Return an error instead.
 func importfile(decl *syntax.ImportDecl) *types.Pkg {
-	if decl.Path.Kind != syntax.StringLit {
-		base.Errorf("import path must be a string")
+	path, err := parseImportPath(decl.Path)
+	if err != nil {
+		base.Errorf("%s", err)
 		return nil
 	}
 
-	path, err := strconv.Unquote(decl.Path.Value)
+	pkg, _, err := readImportFile(path, typecheck.Target, nil, nil)
 	if err != nil {
-		base.Errorf("import path must be a string")
+		base.Errorf("%s", err)
 		return nil
 	}
 
+	if pkg != ir.Pkgs.Unsafe && pkg.Height >= myheight {
+		myheight = pkg.Height + 1
+	}
+	return pkg
+}
+
+func parseImportPath(pathLit *syntax.BasicLit) (string, error) {
+	if pathLit.Kind != syntax.StringLit {
+		return "", errors.New("import path must be a string")
+	}
+
+	path, err := strconv.Unquote(pathLit.Value)
+	if err != nil {
+		return "", errors.New("import path must be a string")
+	}
+
 	if err := checkImportPath(path, false); err != nil {
-		base.Errorf("%s", err.Error())
-		return nil
+		return "", err
 	}
 
+	return path, err
+}
+
+// readImportFile reads the import file for the given package path and
+// returns its types.Pkg representation. If packages is non-nil, the
+// types2.Package representation is also returned.
+func readImportFile(path string, target *ir.Package, check *types2.Checker, packages map[string]*types2.Package) (pkg1 *types.Pkg, pkg2 *types2.Package, err error) {
 	path, err = resolveImportPath(path)
 	if err != nil {
-		base.Errorf("%s", err)
-		return nil
+		return
+	}
+
+	if path == "unsafe" {
+		pkg1, pkg2 = ir.Pkgs.Unsafe, types2.Unsafe
+
+		// TODO(mdempsky): Investigate if this actually matters. Why would
+		// the linker or runtime care whether a package imported unsafe?
+		if !pkg1.Direct {
+			pkg1.Direct = true
+			target.Imports = append(target.Imports, pkg1)
+		}
+
+		return
 	}
 
-	importpkg := types.NewPkg(path, "")
-	if importpkg.Direct {
-		return importpkg // already fully loaded
+	pkg1 = types.NewPkg(path, "")
+	if packages != nil {
+		pkg2 = packages[path]
+		assert(pkg1.Direct == (pkg2 != nil && pkg2.Complete()))
 	}
-	importpkg.Direct = true
-	typecheck.Target.Imports = append(typecheck.Target.Imports, importpkg)
 
-	if path == "unsafe" {
-		return importpkg // initialized with universe
+	if pkg1.Direct {
+		return
 	}
+	pkg1.Direct = true
+	target.Imports = append(target.Imports, pkg1)
 
 	f, err := openPackage(path)
 	if err != nil {
-		base.Errorf("could not import %q: %v", path, err)
-		base.ErrorExit()
+		return
 	}
-	imp := bio.NewReader(f)
-	defer imp.Close()
-	file := f.Name()
+	defer f.Close()
 
-	// check object header
-	p, err := imp.ReadString('\n')
+	r, end, newsize, err := findExportData(f)
 	if err != nil {
-		base.Errorf("import %s: reading input: %v", file, err)
-		base.ErrorExit()
+		return
 	}
 
-	if p == "!\n" { // package archive
-		// package export block should be first
-		sz := archive.ReadHeader(imp.Reader, "__.PKGDEF")
-		if sz <= 0 {
-			base.Errorf("import %s: not a package file", file)
-			base.ErrorExit()
-		}
-		p, err = imp.ReadString('\n')
+	if base.Debug.Export != 0 {
+		fmt.Printf("importing %s (%s)\n", path, f.Name())
+	}
+
+	if newsize != 0 {
+		// We have unified IR data. Map it, and feed to the importers.
+		end -= newsize
+		var data string
+		data, err = base.MapFile(r.File(), end, newsize)
 		if err != nil {
-			base.Errorf("import %s: reading input: %v", file, err)
-			base.ErrorExit()
+			return
 		}
-	}
 
-	if !strings.HasPrefix(p, "go object ") {
-		base.Errorf("import %s: not a go object file: %s", file, p)
-		base.ErrorExit()
-	}
-	q := objabi.HeaderString()
-	if p != q {
-		base.Errorf("import %s: object is [%s] expected [%s]", file, p, q)
-		base.ErrorExit()
-	}
+		pkg2, err = newReadImportFunc(data, pkg1, check, packages)
+	} else {
+		// We only have old data. Oh well, fall back to the legacy importers.
+		haveLegacyImports = true
 
-	// process header lines
-	for {
-		p, err = imp.ReadString('\n')
+		var c byte
+		switch c, err = r.ReadByte(); {
+		case err != nil:
+			return
+
+		case c != 'i':
+			// Indexed format is distinguished by an 'i' byte,
+			// whereas previous export formats started with 'c', 'd', or 'v'.
+			err = fmt.Errorf("unexpected package format byte: %v", c)
+			return
+		}
+
+		pos := r.Offset()
+
+		// Map string (and data) section into memory as a single large
+		// string. This reduces heap fragmentation and allows
+		// returning individual substrings very efficiently.
+		var data string
+		data, err = base.MapFile(r.File(), pos, end-pos)
 		if err != nil {
-			base.Errorf("import %s: reading input: %v", file, err)
-			base.ErrorExit()
+			return
 		}
-		if p == "\n" {
-			break // header ends with blank line
+
+		typecheck.ReadImports(pkg1, data)
+
+		if packages != nil {
+			pkg2, err = importer.ImportData(packages, data, path)
+			if err != nil {
+				return
+			}
 		}
 	}
 
-	// Expect $$B\n to signal binary import format.
+	err = addFingerprint(path, f, end)
+	return
+}
+
+// findExportData returns a *bio.Reader positioned at the start of the
+// binary export data section, and a file offset for where to stop
+// reading.
+func findExportData(f *os.File) (r *bio.Reader, end, newsize int64, err error) {
+	r = bio.NewReader(f)
+
+	// check object header
+	line, err := r.ReadString('\n')
+	if err != nil {
+		return
+	}
 
-	// look for $$
-	var c byte
-	for {
-		c, err = imp.ReadByte()
+	if line == "!\n" { // package archive
+		// package export block should be first
+		sz := int64(archive.ReadHeader(r.Reader, "__.PKGDEF"))
+		if sz <= 0 {
+			err = errors.New("not a package file")
+			return
+		}
+		end = r.Offset() + sz
+		line, err = r.ReadString('\n')
 		if err != nil {
-			break
+			return
 		}
-		if c == '$' {
-			c, err = imp.ReadByte()
-			if c == '$' || err != nil {
-				break
-			}
+	} else {
+		// Not an archive; provide end of file instead.
+		// TODO(mdempsky): I don't think this happens anymore.
+		var fi os.FileInfo
+		fi, err = f.Stat()
+		if err != nil {
+			return
 		}
+		end = fi.Size()
 	}
 
-	// get character after $$
-	if err == nil {
-		c, _ = imp.ReadByte()
+	if !strings.HasPrefix(line, "go object ") {
+		err = fmt.Errorf("not a go object file: %s", line)
+		return
+	}
+	if expect := objabi.HeaderString(); line != expect {
+		err = fmt.Errorf("object is [%s] expected [%s]", line, expect)
+		return
 	}
 
-	var fingerprint goobj.FingerprintType
-	switch c {
-	case '\n':
-		base.Errorf("cannot import %s: old export format no longer supported (recompile library)", path)
-		return nil
-
-	case 'B':
-		if base.Debug.Export != 0 {
-			fmt.Printf("importing %s (%s)\n", path, file)
+	// process header lines
+	for !strings.HasPrefix(line, "$$") {
+		if strings.HasPrefix(line, "newexportsize ") {
+			fields := strings.Fields(line)
+			newsize, err = strconv.ParseInt(fields[1], 10, 64)
+			if err != nil {
+				return
+			}
 		}
-		imp.ReadByte() // skip \n after $$B
 
-		c, err = imp.ReadByte()
+		line, err = r.ReadString('\n')
 		if err != nil {
-			base.Errorf("import %s: reading input: %v", file, err)
-			base.ErrorExit()
+			return
 		}
+	}
 
-		// Indexed format is distinguished by an 'i' byte,
-		// whereas previous export formats started with 'c', 'd', or 'v'.
-		if c != 'i' {
-			base.Errorf("import %s: unexpected package format byte: %v", file, c)
-			base.ErrorExit()
-		}
-		fingerprint = typecheck.ReadImports(importpkg, imp)
+	// Expect $$B\n to signal binary import format.
+	if line != "$$B\n" {
+		err = errors.New("old export format no longer supported (recompile library)")
+		return
+	}
+
+	return
+}
+
+// addFingerprint reads the linker fingerprint included at the end of
+// the exportdata.
+func addFingerprint(path string, f *os.File, end int64) error {
+	const eom = "\n$$\n"
+	var fingerprint goobj.FingerprintType
+
+	var buf [len(fingerprint) + len(eom)]byte
+	if _, err := f.ReadAt(buf[:], end-int64(len(buf))); err != nil {
+		return err
+	}
 
-	default:
-		base.Errorf("no import in %q", path)
-		base.ErrorExit()
+	// Caller should have given us the end position of the export data,
+	// which should end with the "\n$$\n" marker. As a consistency check
+	// to make sure we're reading at the right offset, make sure we
+	// found the marker.
+	if s := string(buf[len(fingerprint):]); s != eom {
+		return fmt.Errorf("expected $$ marker, but found %q", s)
 	}
 
+	copy(fingerprint[:], buf[:])
+
 	// assume files move (get installed) so don't record the full path
 	if base.Flag.Cfg.PackageFile != nil {
 		// If using a packageFile map, assume path_ can be recorded directly.
 		base.Ctxt.AddImport(path, fingerprint)
 	} else {
 		// For file "/Users/foo/go/pkg/darwin_amd64/math.a" record "math.a".
+		file := f.Name()
 		base.Ctxt.AddImport(file[len(file)-len(path)-len(".a"):], fingerprint)
 	}
-
-	if importpkg.Height >= myheight {
-		myheight = importpkg.Height + 1
-	}
-
-	return importpkg
+	return nil
 }
 
 // The linker uses the magic symbol prefixes "go." and "type."
@@ -431,7 +523,7 @@ func clearImports() {
 			s.Def = nil
 			continue
 		}
-		if types.IsDotAlias(s) {
+		if s.Def != nil && s.Def.Sym() != s {
 			// throw away top-level name left over
 			// from previous import . "x"
 			// We'll report errors after type checking in CheckDotImports.
diff --git a/src/cmd/compile/internal/noder/irgen.go b/src/cmd/compile/internal/noder/irgen.go
index 3e0d3285ab916ec0661ba9601149a3209138f02c..29882eb7731f836bc06ba6f767f1aa6bd74848b2 100644
--- a/src/cmd/compile/internal/noder/irgen.go
+++ b/src/cmd/compile/internal/noder/irgen.go
@@ -18,9 +18,9 @@ import (
 	"cmd/internal/src"
 )
 
-// check2 type checks a Go package using types2, and then generates IR
-// using the results.
-func check2(noders []*noder) {
+// checkFiles configures and runs the types2 checker on the given
+// parsed source files and then returns the result.
+func checkFiles(noders []*noder) (posMap, *types2.Package, *types2.Info) {
 	if base.SyntaxErrors() != 0 {
 		base.ErrorExit()
 	}
@@ -34,20 +34,22 @@ func check2(noders []*noder) {
 	}
 
 	// typechecking
+	importer := gcimports{
+		packages: make(map[string]*types2.Package),
+	}
 	conf := types2.Config{
 		GoVersion:             base.Flag.Lang,
 		IgnoreLabels:          true, // parser already checked via syntax.CheckBranches mode
 		CompilerErrorMessages: true, // use error strings matching existing compiler errors
+		AllowTypeLists:        true, // remove this line once all tests use type set syntax
 		Error: func(err error) {
 			terr := err.(types2.Error)
 			base.ErrorfAt(m.makeXPos(terr.Pos), "%s", terr.Msg)
 		},
-		Importer: &gcimports{
-			packages: make(map[string]*types2.Package),
-		},
-		Sizes: &gcSizes{},
+		Importer: &importer,
+		Sizes:    &gcSizes{},
 	}
-	info := types2.Info{
+	info := &types2.Info{
 		Types:      make(map[syntax.Expr]types2.TypeAndValue),
 		Defs:       make(map[*syntax.Name]types2.Object),
 		Uses:       make(map[*syntax.Name]types2.Object),
@@ -57,12 +59,24 @@ func check2(noders []*noder) {
 		Inferred:   make(map[syntax.Expr]types2.Inferred),
 		// expand as needed
 	}
-	pkg, err := conf.Check(base.Ctxt.Pkgpath, files, &info)
-	files = nil
+
+	pkg := types2.NewPackage(base.Ctxt.Pkgpath, "")
+	importer.check = types2.NewChecker(&conf, pkg, info)
+	err := importer.check.Files(files)
+
 	base.ExitIfErrors()
 	if err != nil {
 		base.FatalfAt(src.NoXPos, "conf.Check error: %v", err)
 	}
+
+	return m, pkg, info
+}
+
+// check2 type checks a Go package using types2, and then generates IR
+// using the results.
+func check2(noders []*noder) {
+	m, pkg, info := checkFiles(noders)
+
 	if base.Flag.G < 2 {
 		os.Exit(0)
 	}
@@ -70,7 +84,7 @@ func check2(noders []*noder) {
 	g := irgen{
 		target: typecheck.Target,
 		self:   pkg,
-		info:   &info,
+		info:   info,
 		posMap: m,
 		objs:   make(map[types2.Object]*ir.Name),
 		typs:   make(map[types2.Type]*types.Type),
@@ -82,6 +96,41 @@ func check2(noders []*noder) {
 	}
 }
 
+// gfInfo is information gathered on a generic function.
+type gfInfo struct {
+	tparams      []*types.Type
+	derivedTypes []*types.Type
+	// Nodes in generic function that requires a subdictionary. Includes
+	// method and function calls (OCALL), function values (OFUNCINST), method
+	// values/expressions (OXDOT).
+	subDictCalls []ir.Node
+	// Nodes in generic functions that are a conversion from a typeparam/derived
+	// type to a specific interface.
+	itabConvs []ir.Node
+	// For type switches on nonempty interfaces, a map from OTYPE entries of
+	// HasTParam type, to the interface type we're switching from.
+	// TODO: what if the type we're switching from is a shape type?
+	type2switchType map[ir.Node]*types.Type
+}
+
+// instInfo is information gathered on an gcshape (or fully concrete)
+// instantiation of a function.
+type instInfo struct {
+	fun       *ir.Func // The instantiated function (with body)
+	dictParam *ir.Name // The node inside fun that refers to the dictionary param
+
+	gf     *ir.Name // The associated generic function
+	gfInfo *gfInfo
+
+	startSubDict  int // Start of dict entries for subdictionaries
+	startItabConv int // Start of dict entries for itab conversions
+	dictLen       int // Total number of entries in dictionary
+
+	// Map from nodes in instantiated fun (OCALL, OCALLMETHOD, OFUNCINST, and
+	// OMETHEXPR) to the associated dictionary entry for a sub-dictionary
+	dictEntryMap map[ir.Node]int
+}
+
 type irgen struct {
 	target *ir.Package
 	self   *types2.Package
@@ -92,12 +141,52 @@ type irgen struct {
 	typs   map[types2.Type]*types.Type
 	marker dwarfgen.ScopeMarker
 
+	// laterFuncs records tasks that need to run after all declarations
+	// are processed.
+	laterFuncs []func()
+
+	// exprStmtOK indicates whether it's safe to generate expressions or
+	// statements yet.
+	exprStmtOK bool
+
 	// Fully-instantiated generic types whose methods should be instantiated
 	instTypeList []*types.Type
+
+	dnum int // for generating unique dictionary variables
+
+	// Map from generic function to information about its type params, derived
+	// types, and subdictionaries.
+	gfInfoMap map[*types.Sym]*gfInfo
+
+	// Map from a name of function that been instantiated to information about
+	// its instantiated function, associated generic function/method, and the
+	// mapping from IR nodes to dictionary entries.
+	instInfoMap map[*types.Sym]*instInfo
+
+	// dictionary syms which we need to finish, by writing out any itabconv
+	// entries.
+	dictSymsToFinalize []*delayInfo
+
+	// True when we are compiling a top-level generic function or method. Use to
+	// avoid adding closures of generic functions/methods to the target.Decls
+	// list.
+	topFuncIsGeneric bool
+}
+
+func (g *irgen) later(fn func()) {
+	g.laterFuncs = append(g.laterFuncs, fn)
+}
+
+type delayInfo struct {
+	gf    *ir.Name
+	targs []*types.Type
+	sym   *types.Sym
+	off   int
 }
 
 func (g *irgen) generate(noders []*noder) {
 	types.LocalPkg.Name = g.self.Name()
+	types.LocalPkg.Height = g.self.Height()
 	typecheck.TypecheckAllowed = true
 
 	// Prevent size calculations until we set the underlying type
@@ -107,7 +196,7 @@ func (g *irgen) generate(noders []*noder) {
 	// At this point, types2 has already handled name resolution and
 	// type checking. We just need to map from its object and type
 	// representations to those currently used by the rest of the
-	// compiler. This happens mostly in 3 passes.
+	// compiler. This happens in a few passes.
 
 	// 1. Process all import declarations. We use the compiler's own
 	// importer for this, rather than types2's gcimporter-derived one,
@@ -132,7 +221,6 @@ Outer:
 			}
 		}
 	}
-	types.LocalPkg.Height = myheight
 
 	// 2. Process all package-block type declarations. As with imports,
 	// we need to make sure all types are properly instantiated before
@@ -157,7 +245,16 @@ Outer:
 
 	// 3. Process all remaining declarations.
 	for _, declList := range declLists {
-		g.target.Decls = append(g.target.Decls, g.decls(declList)...)
+		g.decls((*ir.Nodes)(&g.target.Decls), declList)
+	}
+	g.exprStmtOK = true
+
+	// 4. Run any "later" tasks. Avoid using 'range' so that tasks can
+	// recursively queue further tasks. (Not currently utilized though.)
+	for len(g.laterFuncs) > 0 {
+		fn := g.laterFuncs[0]
+		g.laterFuncs = g.laterFuncs[1:]
+		fn()
 	}
 
 	if base.Flag.W > 1 {
@@ -167,6 +264,10 @@ Outer:
 		}
 	}
 
+	// Check for unusual case where noder2 encounters a type error that types2
+	// doesn't check for (e.g. notinheap incompatibility).
+	base.ExitIfErrors()
+
 	typecheck.DeclareUniverse()
 
 	for _, p := range noders {
@@ -175,7 +276,7 @@ Outer:
 
 		// Double check for any type-checking inconsistencies. This can be
 		// removed once we're confident in IR generation results.
-		syntax.Walk(p.file, func(n syntax.Node) bool {
+		syntax.Crawl(p.file, func(n syntax.Node) bool {
 			g.validate(n)
 			return false
 		})
@@ -184,9 +285,9 @@ Outer:
 	// Create any needed stencils of generic functions
 	g.stencil()
 
-	// For now, remove all generic functions from g.target.Decl, since they
-	// have been used for stenciling, but don't compile. TODO: We will
-	// eventually export any exportable generic functions.
+	// Remove all generic functions from g.target.Decl, since they have been
+	// used for stenciling, but don't compile. Generic functions will already
+	// have been marked for export as appropriate.
 	j := 0
 	for i, decl := range g.target.Decls {
 		if decl.Op() != ir.ODCLFUNC || !decl.Type().HasTParam() {
@@ -195,6 +296,8 @@ Outer:
 		}
 	}
 	g.target.Decls = g.target.Decls[:j]
+
+	base.Assertf(len(g.laterFuncs) == 0, "still have %d later funcs", len(g.laterFuncs))
 }
 
 func (g *irgen) unhandled(what string, p poser) {
diff --git a/src/cmd/compile/internal/noder/linker.go b/src/cmd/compile/internal/noder/linker.go
new file mode 100644
index 0000000000000000000000000000000000000000..2bc7f7c608ead06af328e49551dfb6f66e607791
--- /dev/null
+++ b/src/cmd/compile/internal/noder/linker.go
@@ -0,0 +1,296 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"io"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/reflectdata"
+	"cmd/compile/internal/types"
+	"cmd/internal/goobj"
+	"cmd/internal/obj"
+)
+
+// This file implements the unified IR linker, which combines the
+// local package's stub data with imported package data to produce a
+// complete export data file. It also rewrites the compiler's
+// extension data sections based on the results of compilation (e.g.,
+// the function inlining cost and linker symbol index assignments).
+//
+// TODO(mdempsky): Using the name "linker" here is confusing, because
+// readers are likely to mistake references to it for cmd/link. But
+// there's a shortage of good names for "something that combines
+// multiple parts into a cohesive whole"... e.g., "assembler" and
+// "compiler" are also already taken.
+
+type linker struct {
+	pw pkgEncoder
+
+	pkgs  map[string]int
+	decls map[*types.Sym]int
+}
+
+func (l *linker) relocAll(pr *pkgReader, relocs []relocEnt) []relocEnt {
+	res := make([]relocEnt, len(relocs))
+	for i, rent := range relocs {
+		rent.idx = l.relocIdx(pr, rent.kind, rent.idx)
+		res[i] = rent
+	}
+	return res
+}
+
+func (l *linker) relocIdx(pr *pkgReader, k reloc, idx int) int {
+	assert(pr != nil)
+
+	absIdx := pr.absIdx(k, idx)
+
+	if newidx := pr.newindex[absIdx]; newidx != 0 {
+		return ^newidx
+	}
+
+	var newidx int
+	switch k {
+	case relocString:
+		newidx = l.relocString(pr, idx)
+	case relocPkg:
+		newidx = l.relocPkg(pr, idx)
+	case relocObj:
+		newidx = l.relocObj(pr, idx)
+
+	default:
+		// Generic relocations.
+		//
+		// TODO(mdempsky): Deduplicate more sections? In fact, I think
+		// every section could be deduplicated. This would also be easier
+		// if we do external relocations.
+
+		w := l.pw.newEncoderRaw(k)
+		l.relocCommon(pr, &w, k, idx)
+		newidx = w.idx
+	}
+
+	pr.newindex[absIdx] = ^newidx
+
+	return newidx
+}
+
+func (l *linker) relocString(pr *pkgReader, idx int) int {
+	return l.pw.stringIdx(pr.stringIdx(idx))
+}
+
+func (l *linker) relocPkg(pr *pkgReader, idx int) int {
+	path := pr.peekPkgPath(idx)
+
+	if newidx, ok := l.pkgs[path]; ok {
+		return newidx
+	}
+
+	r := pr.newDecoder(relocPkg, idx, syncPkgDef)
+	w := l.pw.newEncoder(relocPkg, syncPkgDef)
+	l.pkgs[path] = w.idx
+
+	// TODO(mdempsky): We end up leaving an empty string reference here
+	// from when the package was originally written as "". Probably not
+	// a big deal, but a little annoying. Maybe relocating
+	// cross-references in place is the way to go after all.
+	w.relocs = l.relocAll(pr, r.relocs)
+
+	_ = r.string() // original path
+	w.string(path)
+
+	io.Copy(&w.data, &r.data)
+
+	return w.flush()
+}
+
+func (l *linker) relocObj(pr *pkgReader, idx int) int {
+	path, name, tag := pr.peekObj(idx)
+	sym := types.NewPkg(path, "").Lookup(name)
+
+	if newidx, ok := l.decls[sym]; ok {
+		return newidx
+	}
+
+	if tag == objStub && path != "builtin" && path != "unsafe" {
+		pri, ok := objReader[sym]
+		if !ok {
+			base.Fatalf("missing reader for %q.%v", path, name)
+		}
+		assert(ok)
+
+		pr = pri.pr
+		idx = pri.idx
+
+		path2, name2, tag2 := pr.peekObj(idx)
+		sym2 := types.NewPkg(path2, "").Lookup(name2)
+		assert(sym == sym2)
+		assert(tag2 != objStub)
+	}
+
+	w := l.pw.newEncoderRaw(relocObj)
+	wext := l.pw.newEncoderRaw(relocObjExt)
+	wname := l.pw.newEncoderRaw(relocName)
+	wdict := l.pw.newEncoderRaw(relocObjDict)
+
+	l.decls[sym] = w.idx
+	assert(wext.idx == w.idx)
+	assert(wname.idx == w.idx)
+	assert(wdict.idx == w.idx)
+
+	l.relocCommon(pr, &w, relocObj, idx)
+	l.relocCommon(pr, &wname, relocName, idx)
+	l.relocCommon(pr, &wdict, relocObjDict, idx)
+
+	var obj *ir.Name
+	if path == "" {
+		var ok bool
+		obj, ok = sym.Def.(*ir.Name)
+
+		// Generic types and functions and declared constraint types won't
+		// have definitions.
+		// For now, just generically copy their extension data.
+		// TODO(mdempsky): Restore assertion.
+		if !ok && false {
+			base.Fatalf("missing definition for %v", sym)
+		}
+	}
+
+	if obj != nil {
+		wext.sync(syncObject1)
+		switch tag {
+		case objFunc:
+			l.relocFuncExt(&wext, obj)
+		case objType:
+			l.relocTypeExt(&wext, obj)
+		case objVar:
+			l.relocVarExt(&wext, obj)
+		}
+		wext.flush()
+	} else {
+		l.relocCommon(pr, &wext, relocObjExt, idx)
+	}
+
+	return w.idx
+}
+
+func (l *linker) relocCommon(pr *pkgReader, w *encoder, k reloc, idx int) {
+	r := pr.newDecoderRaw(k, idx)
+	w.relocs = l.relocAll(pr, r.relocs)
+	io.Copy(&w.data, &r.data)
+	w.flush()
+}
+
+func (l *linker) pragmaFlag(w *encoder, pragma ir.PragmaFlag) {
+	w.sync(syncPragma)
+	w.int(int(pragma))
+}
+
+func (l *linker) relocFuncExt(w *encoder, name *ir.Name) {
+	w.sync(syncFuncExt)
+
+	l.pragmaFlag(w, name.Func.Pragma)
+	l.linkname(w, name)
+
+	// Relocated extension data.
+	w.bool(true)
+
+	// Record definition ABI so cross-ABI calls can be direct.
+	// This is important for the performance of calling some
+	// common functions implemented in assembly (e.g., bytealg).
+	w.uint64(uint64(name.Func.ABI))
+
+	// Escape analysis.
+	for _, fs := range &types.RecvsParams {
+		for _, f := range fs(name.Type()).FieldSlice() {
+			w.string(f.Note)
+		}
+	}
+
+	if inl := name.Func.Inl; w.bool(inl != nil) {
+		w.len(int(inl.Cost))
+		w.bool(inl.CanDelayResults)
+
+		pri, ok := bodyReader[name.Func]
+		assert(ok)
+		w.reloc(relocBody, l.relocIdx(pri.pr, relocBody, pri.idx))
+	}
+
+	w.sync(syncEOF)
+}
+
+func (l *linker) relocTypeExt(w *encoder, name *ir.Name) {
+	w.sync(syncTypeExt)
+
+	typ := name.Type()
+
+	l.pragmaFlag(w, name.Pragma())
+
+	// For type T, export the index of type descriptor symbols of T and *T.
+	l.lsymIdx(w, "", reflectdata.TypeLinksym(typ))
+	l.lsymIdx(w, "", reflectdata.TypeLinksym(typ.PtrTo()))
+
+	if typ.Kind() != types.TINTER {
+		for _, method := range typ.Methods().Slice() {
+			l.relocFuncExt(w, method.Nname.(*ir.Name))
+		}
+	}
+}
+
+func (l *linker) relocVarExt(w *encoder, name *ir.Name) {
+	w.sync(syncVarExt)
+	l.linkname(w, name)
+}
+
+func (l *linker) linkname(w *encoder, name *ir.Name) {
+	w.sync(syncLinkname)
+
+	linkname := name.Sym().Linkname
+	if !l.lsymIdx(w, linkname, name.Linksym()) {
+		w.string(linkname)
+	}
+}
+
+func (l *linker) lsymIdx(w *encoder, linkname string, lsym *obj.LSym) bool {
+	if lsym.PkgIdx > goobj.PkgIdxSelf || (lsym.PkgIdx == goobj.PkgIdxInvalid && !lsym.Indexed()) || linkname != "" {
+		w.int64(-1)
+		return false
+	}
+
+	// For a defined symbol, export its index.
+	// For re-exporting an imported symbol, pass its index through.
+	w.int64(int64(lsym.SymIdx))
+	return true
+}
+
+// @@@ Helpers
+
+// TODO(mdempsky): These should probably be removed. I think they're a
+// smell that the export data format is not yet quite right.
+
+func (pr *pkgDecoder) peekPkgPath(idx int) string {
+	r := pr.newDecoder(relocPkg, idx, syncPkgDef)
+	path := r.string()
+	if path == "" {
+		path = pr.pkgPath
+	}
+	return path
+}
+
+func (pr *pkgDecoder) peekObj(idx int) (string, string, codeObj) {
+	r := pr.newDecoder(relocName, idx, syncObject1)
+	r.sync(syncSym)
+	r.sync(syncPkg)
+	path := pr.peekPkgPath(r.reloc(relocPkg))
+	name := r.string()
+	assert(name != "")
+
+	tag := codeObj(r.code(syncCodeObj))
+
+	return path, name, tag
+}
diff --git a/src/cmd/compile/internal/noder/noder.go b/src/cmd/compile/internal/noder/noder.go
index 5fcad096c28ae5f5aa413bfc1a0ead3f7212e630..2b67a91b3f799bddc1f69927e2bd39cc669e4056 100644
--- a/src/cmd/compile/internal/noder/noder.go
+++ b/src/cmd/compile/internal/noder/noder.go
@@ -5,9 +5,11 @@
 package noder
 
 import (
+	"errors"
 	"fmt"
 	"go/constant"
 	"go/token"
+	"internal/buildcfg"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -29,8 +31,11 @@ import (
 func LoadPackage(filenames []string) {
 	base.Timer.Start("fe", "parse")
 
+	// -G=3 and unified expect generics syntax, but -G=0 does not.
+	supportsGenerics := base.Flag.G != 0 || buildcfg.Experiment.Unified
+
 	mode := syntax.CheckBranches
-	if base.Flag.G != 0 {
+	if supportsGenerics && types.AllowsGoVersion(types.LocalPkg, 1, 18) {
 		mode |= syntax.AllowGenerics
 	}
 
@@ -75,6 +80,11 @@ func LoadPackage(filenames []string) {
 	}
 	base.Timer.AddEvent(int64(lines), "lines")
 
+	if base.Debug.Unified != 0 {
+		unified(noders)
+		return
+	}
+
 	if base.Flag.G != 0 {
 		// Use types2 to type-check and possibly generate IR.
 		check2(noders)
@@ -109,25 +119,35 @@ func LoadPackage(filenames []string) {
 	//   We also defer type alias declarations until phase 2
 	//   to avoid cycles like #18640.
 	//   TODO(gri) Remove this again once we have a fix for #25838.
-
-	// Don't use range--typecheck can add closures to Target.Decls.
-	base.Timer.Start("fe", "typecheck", "top1")
-	for i := 0; i < len(typecheck.Target.Decls); i++ {
-		n := typecheck.Target.Decls[i]
-		if op := n.Op(); op != ir.ODCL && op != ir.OAS && op != ir.OAS2 && (op != ir.ODCLTYPE || !n.(*ir.Decl).X.Alias()) {
-			typecheck.Target.Decls[i] = typecheck.Stmt(n)
-		}
-	}
-
+	//
 	// Phase 2: Variable assignments.
 	//   To check interface assignments, depends on phase 1.
 
 	// Don't use range--typecheck can add closures to Target.Decls.
-	base.Timer.Start("fe", "typecheck", "top2")
-	for i := 0; i < len(typecheck.Target.Decls); i++ {
-		n := typecheck.Target.Decls[i]
-		if op := n.Op(); op == ir.ODCL || op == ir.OAS || op == ir.OAS2 || op == ir.ODCLTYPE && n.(*ir.Decl).X.Alias() {
-			typecheck.Target.Decls[i] = typecheck.Stmt(n)
+	for phase, name := range []string{"top1", "top2"} {
+		base.Timer.Start("fe", "typecheck", name)
+		for i := 0; i < len(typecheck.Target.Decls); i++ {
+			n := typecheck.Target.Decls[i]
+			op := n.Op()
+
+			// Closure function declarations are typechecked as part of the
+			// closure expression.
+			if fn, ok := n.(*ir.Func); ok && fn.OClosure != nil {
+				continue
+			}
+
+			// We don't actually add ir.ODCL nodes to Target.Decls. Make sure of that.
+			if op == ir.ODCL {
+				base.FatalfAt(n.Pos(), "unexpected top declaration: %v", op)
+			}
+
+			// Identify declarations that should be deferred to the second
+			// iteration.
+			late := op == ir.OAS || op == ir.OAS2 || op == ir.ODCLTYPE && n.(*ir.Decl).X.Alias()
+
+			if late == (phase == 1) {
+				typecheck.Target.Decls[i] = typecheck.Stmt(n)
+			}
 		}
 	}
 
@@ -136,16 +156,15 @@ func LoadPackage(filenames []string) {
 	base.Timer.Start("fe", "typecheck", "func")
 	var fcount int64
 	for i := 0; i < len(typecheck.Target.Decls); i++ {
-		n := typecheck.Target.Decls[i]
-		if n.Op() == ir.ODCLFUNC {
+		if fn, ok := typecheck.Target.Decls[i].(*ir.Func); ok {
 			if base.Flag.W > 1 {
-				s := fmt.Sprintf("\nbefore typecheck %v", n)
-				ir.Dump(s, n)
+				s := fmt.Sprintf("\nbefore typecheck %v", fn)
+				ir.Dump(s, fn)
 			}
-			typecheck.FuncBody(n.(*ir.Func))
+			typecheck.FuncBody(fn)
 			if base.Flag.W > 1 {
-				s := fmt.Sprintf("\nafter typecheck %v", n)
-				ir.Dump(s, n)
+				s := fmt.Sprintf("\nafter typecheck %v", fn)
+				ir.Dump(s, fn)
 			}
 			fcount++
 		}
@@ -172,13 +191,23 @@ func (p *noder) errorAt(pos syntax.Pos, format string, args ...interface{}) {
 	base.ErrorfAt(p.makeXPos(pos), format, args...)
 }
 
-// TODO(gri) Can we eliminate fileh in favor of absFilename?
-func fileh(name string) string {
-	return objabi.AbsFile("", name, base.Flag.TrimPath)
-}
-
-func absFilename(name string) string {
-	return objabi.AbsFile(base.Ctxt.Pathname, name, base.Flag.TrimPath)
+// trimFilename returns the "trimmed" filename of b, which is the
+// absolute filename after applying -trimpath processing. This
+// filename form is suitable for use in object files and export data.
+//
+// If b's filename has already been trimmed (i.e., because it was read
+// in from an imported package's export data), then the filename is
+// returned unchanged.
+func trimFilename(b *syntax.PosBase) string {
+	filename := b.Filename()
+	if !b.Trimmed() {
+		dir := ""
+		if b.IsFileBase() {
+			dir = base.Ctxt.Pathname
+		}
+		filename = objabi.AbsFile(dir, filename, base.Flag.TrimPath)
+	}
+	return filename
 }
 
 // noder transforms package syntax's AST into a Node tree.
@@ -449,7 +478,7 @@ func (p *noder) varDecl(decl *syntax.VarDecl) []ir.Node {
 type constState struct {
 	group  *syntax.Group
 	typ    ir.Ntype
-	values []ir.Node
+	values syntax.Expr
 	iota   int64
 }
 
@@ -467,16 +496,15 @@ func (p *noder) constDecl(decl *syntax.ConstDecl, cs *constState) []ir.Node {
 	names := p.declNames(ir.OLITERAL, decl.NameList)
 	typ := p.typeExprOrNil(decl.Type)
 
-	var values []ir.Node
 	if decl.Values != nil {
-		values = p.exprList(decl.Values)
-		cs.typ, cs.values = typ, values
+		cs.typ, cs.values = typ, decl.Values
 	} else {
 		if typ != nil {
 			base.Errorf("const declaration cannot have type without expression")
 		}
-		typ, values = cs.typ, cs.values
+		typ = cs.typ
 	}
+	values := p.exprList(cs.values)
 
 	nn := make([]ir.Node, 0, len(names))
 	for i, n := range names {
@@ -484,10 +512,16 @@ func (p *noder) constDecl(decl *syntax.ConstDecl, cs *constState) []ir.Node {
 			base.Errorf("missing value in const declaration")
 			break
 		}
+
 		v := values[i]
 		if decl.Values == nil {
-			v = ir.DeepCopy(n.Pos(), v)
+			ir.Visit(v, func(v ir.Node) {
+				if ir.HasUniquePos(v) {
+					v.SetPos(n.Pos())
+				}
+			})
 		}
+
 		typecheck.Declare(n, typecheck.DeclContext)
 
 		n.Ntype = typ
@@ -625,6 +659,9 @@ func (p *noder) params(params []*syntax.Field, dddOk bool) []*ir.Field {
 	for i, param := range params {
 		p.setlineno(param)
 		nodes = append(nodes, p.param(param, dddOk, i+1 == len(params)))
+		if i > 0 && params[i].Type == params[i-1].Type {
+			nodes[i].Ntype = nodes[i-1].Ntype
+		}
 	}
 	return nodes
 }
@@ -914,6 +951,9 @@ func (p *noder) structType(expr *syntax.StructType) ir.Node {
 		} else {
 			n = ir.NewField(p.pos(field), p.name(field.Name), p.typeExpr(field.Type), nil)
 		}
+		if i > 0 && expr.FieldList[i].Type == expr.FieldList[i-1].Type {
+			n.Ntype = l[i-1].Ntype
+		}
 		if i < len(expr.TagList) && expr.TagList[i] != nil {
 			n.Note = constant.StringVal(p.basicLit(expr.TagList[i]))
 		}
@@ -977,6 +1017,8 @@ func (p *noder) packname(expr syntax.Expr) *types.Sym {
 }
 
 func (p *noder) embedded(typ syntax.Expr) *ir.Field {
+	pos := p.pos(syntax.StartPos(typ))
+
 	op, isStar := typ.(*syntax.Operation)
 	if isStar {
 		if op.Op != syntax.Mul || op.Y != nil {
@@ -986,11 +1028,11 @@ func (p *noder) embedded(typ syntax.Expr) *ir.Field {
 	}
 
 	sym := p.packname(typ)
-	n := ir.NewField(p.pos(typ), typecheck.Lookup(sym.Name), importName(sym).(ir.Ntype), nil)
+	n := ir.NewField(pos, typecheck.Lookup(sym.Name), importName(sym).(ir.Ntype), nil)
 	n.Embedded = true
 
 	if isStar {
-		n.Ntype = ir.NewStarExpr(p.pos(op), n.Ntype)
+		n.Ntype = ir.NewStarExpr(pos, n.Ntype)
 	}
 	return n
 }
@@ -1691,7 +1733,7 @@ func (p *noder) pragma(pos syntax.Pos, blankLine bool, text string, old syntax.P
 // (primarily misuse of linker flags), other files are not.
 // See golang.org/issue/23672.
 func isCgoGeneratedFile(pos syntax.Pos) bool {
-	return strings.HasPrefix(filepath.Base(filepath.Clean(fileh(pos.Base().Filename()))), "_cgo_")
+	return strings.HasPrefix(filepath.Base(trimFilename(pos.Base())), "_cgo_")
 }
 
 // safeArg reports whether arg is a "safe" command-line argument,
@@ -1780,24 +1822,14 @@ func fakeRecv() *ir.Field {
 }
 
 func (p *noder) funcLit(expr *syntax.FuncLit) ir.Node {
-	xtype := p.typeExpr(expr.Type)
-
-	fn := ir.NewFunc(p.pos(expr))
-	fn.SetIsHiddenClosure(ir.CurFunc != nil)
-
-	fn.Nname = ir.NewNameAt(p.pos(expr), ir.BlankNode.Sym()) // filled in by tcClosure
-	fn.Nname.Func = fn
-	fn.Nname.Ntype = xtype
-	fn.Nname.Defn = fn
-
-	clo := ir.NewClosureExpr(p.pos(expr), fn)
-	fn.OClosure = clo
+	fn := ir.NewClosureFunc(p.pos(expr), ir.CurFunc != nil)
+	fn.Nname.Ntype = p.typeExpr(expr.Type)
 
 	p.funcBody(fn, expr.Body)
 
 	ir.FinishCaptureNames(base.Pos, ir.CurFunc, fn)
 
-	return clo
+	return fn.OClosure
 }
 
 // A function named init is a special case.
@@ -1841,33 +1873,14 @@ func oldname(s *types.Sym) ir.Node {
 }
 
 func varEmbed(makeXPos func(syntax.Pos) src.XPos, name *ir.Name, decl *syntax.VarDecl, pragma *pragmas, haveEmbed bool) {
-	if pragma.Embeds == nil {
-		return
-	}
-
 	pragmaEmbeds := pragma.Embeds
 	pragma.Embeds = nil
-	pos := makeXPos(pragmaEmbeds[0].Pos)
-
-	if !haveEmbed {
-		base.ErrorfAt(pos, "go:embed only allowed in Go files that import \"embed\"")
+	if len(pragmaEmbeds) == 0 {
 		return
 	}
-	if len(decl.NameList) > 1 {
-		base.ErrorfAt(pos, "go:embed cannot apply to multiple vars")
-		return
-	}
-	if decl.Values != nil {
-		base.ErrorfAt(pos, "go:embed cannot apply to var with initializer")
-		return
-	}
-	if decl.Type == nil {
-		// Should not happen, since Values == nil now.
-		base.ErrorfAt(pos, "go:embed cannot apply to var without type")
-		return
-	}
-	if typecheck.DeclContext != ir.PEXTERN {
-		base.ErrorfAt(pos, "go:embed cannot apply to var inside func")
+
+	if err := checkEmbed(decl, haveEmbed, typecheck.DeclContext != ir.PEXTERN); err != nil {
+		base.ErrorfAt(makeXPos(pragmaEmbeds[0].Pos), "%s", err)
 		return
 	}
 
@@ -1878,3 +1891,24 @@ func varEmbed(makeXPos func(syntax.Pos) src.XPos, name *ir.Name, decl *syntax.Va
 	typecheck.Target.Embeds = append(typecheck.Target.Embeds, name)
 	name.Embed = &embeds
 }
+
+func checkEmbed(decl *syntax.VarDecl, haveEmbed, withinFunc bool) error {
+	switch {
+	case !haveEmbed:
+		return errors.New("go:embed only allowed in Go files that import \"embed\"")
+	case len(decl.NameList) > 1:
+		return errors.New("go:embed cannot apply to multiple vars")
+	case decl.Values != nil:
+		return errors.New("go:embed cannot apply to var with initializer")
+	case decl.Type == nil:
+		// Should not happen, since Values == nil now.
+		return errors.New("go:embed cannot apply to var without type")
+	case withinFunc:
+		return errors.New("go:embed cannot apply to var inside func")
+	case !types.AllowsGoVersion(types.LocalPkg, 1, 16):
+		return fmt.Errorf("go:embed requires go1.16 or later (-lang was set to %s; check go.mod)", base.Flag.Lang)
+
+	default:
+		return nil
+	}
+}
diff --git a/src/cmd/compile/internal/noder/object.go b/src/cmd/compile/internal/noder/object.go
index 82cce1ace0fcff81856f1751498f009c2d5fa84b..40c0b9cf4222072d4b92e22bceb9a51b555ad932 100644
--- a/src/cmd/compile/internal/noder/object.go
+++ b/src/cmd/compile/internal/noder/object.go
@@ -29,7 +29,7 @@ func (g *irgen) use(name *syntax.Name) *ir.Name {
 	if !ok {
 		base.FatalfAt(g.pos(name), "unknown name %v", name)
 	}
-	obj := ir.CaptureName(g.pos(obj2), ir.CurFunc, g.obj(obj2))
+	obj := ir.CaptureName(g.pos(name), ir.CurFunc, g.obj(obj2))
 	if obj.Defn != nil && obj.Defn.Op() == ir.ONAME {
 		// If CaptureName created a closure variable, then transfer the
 		// type of the captured name to the new closure variable.
@@ -49,6 +49,11 @@ func (g *irgen) obj(obj types2.Object) *ir.Name {
 	// For imported objects, we use iimport directly instead of mapping
 	// the types2 representation.
 	if obj.Pkg() != g.self {
+		if sig, ok := obj.Type().(*types2.Signature); ok && sig.Recv() != nil {
+			// We can't import a method by name - must import the type
+			// and access the method from it.
+			base.FatalfAt(g.pos(obj), "tried to import a method directly")
+		}
 		sym := g.sym(obj)
 		if sym.Def != nil {
 			return sym.Def.(*ir.Name)
@@ -101,25 +106,28 @@ func (g *irgen) obj(obj types2.Object) *ir.Name {
 	case *types2.TypeName:
 		if obj.IsAlias() {
 			name = g.objCommon(pos, ir.OTYPE, g.sym(obj), class, g.typ(obj.Type()))
+			name.SetAlias(true)
 		} else {
 			name = ir.NewDeclNameAt(pos, ir.OTYPE, g.sym(obj))
 			g.objFinish(name, class, types.NewNamed(name))
 		}
 
 	case *types2.Var:
-		var sym *types.Sym
-		if class == ir.PPARAMOUT {
+		sym := g.sym(obj)
+		if class == ir.PPARAMOUT && (sym == nil || sym.IsBlank()) {
 			// Backend needs names for result parameters,
 			// even if they're anonymous or blank.
-			switch obj.Name() {
-			case "":
-				sym = typecheck.LookupNum("~r", len(ir.CurFunc.Dcl)) // 'r' for "result"
-			case "_":
-				sym = typecheck.LookupNum("~b", len(ir.CurFunc.Dcl)) // 'b' for "blank"
+			nresults := 0
+			for _, n := range ir.CurFunc.Dcl {
+				if n.Class == ir.PPARAMOUT {
+					nresults++
+				}
+			}
+			if sym == nil {
+				sym = typecheck.LookupNum("~r", nresults) // 'r' for "result"
+			} else {
+				sym = typecheck.LookupNum("~b", nresults) // 'b' for "blank"
 			}
-		}
-		if sym == nil {
-			sym = g.sym(obj)
 		}
 		name = g.objCommon(pos, ir.ONAME, sym, class, g.typ(obj.Type()))
 
@@ -164,9 +172,8 @@ func (g *irgen) objFinish(name *ir.Name, class ir.Class, typ *types.Type) {
 			break // methods are exported with their receiver type
 		}
 		if types.IsExported(sym.Name) {
-			if name.Class == ir.PFUNC && name.Type().NumTParams() > 0 {
-				base.FatalfAt(name.Pos(), "Cannot export a generic function (yet): %v", name)
-			}
+			// Generic functions can be marked for export here, even
+			// though they will not be compiled until instantiated.
 			typecheck.Export(name)
 		}
 		if base.Flag.AsmHdr != "" && !name.Sym().Asm() {
diff --git a/src/cmd/compile/internal/noder/posmap.go b/src/cmd/compile/internal/noder/posmap.go
index a6d3e2d7ef4d9ac0aa241eede47c23b2c6595e85..f22628f845f7225c3862d00ada9066eaf7c0054e 100644
--- a/src/cmd/compile/internal/noder/posmap.go
+++ b/src/cmd/compile/internal/noder/posmap.go
@@ -45,8 +45,10 @@ func (m *posMap) makeSrcPosBase(b0 *syntax.PosBase) *src.PosBase {
 	b1, ok := m.bases[b0]
 	if !ok {
 		fn := b0.Filename()
+		absfn := trimFilename(b0)
+
 		if b0.IsFileBase() {
-			b1 = src.NewFileBase(fn, absFilename(fn))
+			b1 = src.NewFileBase(fn, absfn)
 		} else {
 			// line directive base
 			p0 := b0.Pos()
@@ -55,7 +57,7 @@ func (m *posMap) makeSrcPosBase(b0 *syntax.PosBase) *src.PosBase {
 				panic("infinite recursion in makeSrcPosBase")
 			}
 			p1 := src.MakePos(m.makeSrcPosBase(p0b), p0.Line(), p0.Col())
-			b1 = src.NewLinePragmaBase(p1, fn, fileh(fn), b0.Line(), b0.Col())
+			b1 = src.NewLinePragmaBase(p1, fn, absfn, b0.Line(), b0.Col())
 		}
 		if m.bases == nil {
 			m.bases = make(map[*syntax.PosBase]*src.PosBase)
diff --git a/src/cmd/compile/internal/noder/quirks.go b/src/cmd/compile/internal/noder/quirks.go
new file mode 100644
index 0000000000000000000000000000000000000000..914c5d2bd7115663dd34df2833e12dd86fa7bdb0
--- /dev/null
+++ b/src/cmd/compile/internal/noder/quirks.go
@@ -0,0 +1,450 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"fmt"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+// This file defines helper functions useful for satisfying toolstash
+// -cmp when compared against the legacy frontend behavior, but can be
+// removed after that's no longer a concern.
+
+// quirksMode controls whether behavior specific to satisfying
+// toolstash -cmp is used.
+func quirksMode() bool {
+	return base.Debug.UnifiedQuirks != 0
+}
+
+// posBasesOf returns all of the position bases in the source files,
+// as seen in a straightforward traversal.
+//
+// This is necessary to ensure position bases (and thus file names)
+// get registered in the same order as noder would visit them.
+func posBasesOf(noders []*noder) []*syntax.PosBase {
+	seen := make(map[*syntax.PosBase]bool)
+	var bases []*syntax.PosBase
+
+	for _, p := range noders {
+		syntax.Crawl(p.file, func(n syntax.Node) bool {
+			if b := n.Pos().Base(); !seen[b] {
+				bases = append(bases, b)
+				seen[b] = true
+			}
+			return false
+		})
+	}
+
+	return bases
+}
+
+// importedObjsOf returns the imported objects (i.e., referenced
+// objects not declared by curpkg) from the parsed source files, in
+// the order that typecheck used to load their definitions.
+//
+// This is needed because loading the definitions for imported objects
+// can also add file names.
+func importedObjsOf(curpkg *types2.Package, info *types2.Info, noders []*noder) []types2.Object {
+	// This code is complex because it matches the precise order that
+	// typecheck recursively and repeatedly traverses the IR. It's meant
+	// to be thrown away eventually anyway.
+
+	seen := make(map[types2.Object]bool)
+	var objs []types2.Object
+
+	var phase int
+
+	decls := make(map[types2.Object]syntax.Decl)
+	assoc := func(decl syntax.Decl, names ...*syntax.Name) {
+		for _, name := range names {
+			obj, ok := info.Defs[name]
+			assert(ok)
+			decls[obj] = decl
+		}
+	}
+
+	for _, p := range noders {
+		syntax.Crawl(p.file, func(n syntax.Node) bool {
+			switch n := n.(type) {
+			case *syntax.ConstDecl:
+				assoc(n, n.NameList...)
+			case *syntax.FuncDecl:
+				assoc(n, n.Name)
+			case *syntax.TypeDecl:
+				assoc(n, n.Name)
+			case *syntax.VarDecl:
+				assoc(n, n.NameList...)
+			case *syntax.BlockStmt:
+				return true
+			}
+			return false
+		})
+	}
+
+	var visited map[syntax.Decl]bool
+
+	var resolveDecl func(n syntax.Decl)
+	var resolveNode func(n syntax.Node, top bool)
+
+	resolveDecl = func(n syntax.Decl) {
+		if visited[n] {
+			return
+		}
+		visited[n] = true
+
+		switch n := n.(type) {
+		case *syntax.ConstDecl:
+			resolveNode(n.Type, true)
+			resolveNode(n.Values, true)
+
+		case *syntax.FuncDecl:
+			if n.Recv != nil {
+				resolveNode(n.Recv, true)
+			}
+			resolveNode(n.Type, true)
+
+		case *syntax.TypeDecl:
+			resolveNode(n.Type, true)
+
+		case *syntax.VarDecl:
+			if n.Type != nil {
+				resolveNode(n.Type, true)
+			} else {
+				resolveNode(n.Values, true)
+			}
+		}
+	}
+
+	resolveObj := func(pos syntax.Pos, obj types2.Object) {
+		switch obj.Pkg() {
+		case nil:
+			// builtin; nothing to do
+
+		case curpkg:
+			if decl, ok := decls[obj]; ok {
+				resolveDecl(decl)
+			}
+
+		default:
+			if obj.Parent() == obj.Pkg().Scope() && !seen[obj] {
+				seen[obj] = true
+				objs = append(objs, obj)
+			}
+		}
+	}
+
+	checkdefat := func(pos syntax.Pos, n *syntax.Name) {
+		if n.Value == "_" {
+			return
+		}
+		obj, ok := info.Uses[n]
+		if !ok {
+			obj, ok = info.Defs[n]
+			if !ok {
+				return
+			}
+		}
+		if obj == nil {
+			return
+		}
+		resolveObj(pos, obj)
+	}
+	checkdef := func(n *syntax.Name) { checkdefat(n.Pos(), n) }
+
+	var later []syntax.Node
+
+	resolveNode = func(n syntax.Node, top bool) {
+		if n == nil {
+			return
+		}
+		syntax.Crawl(n, func(n syntax.Node) bool {
+			switch n := n.(type) {
+			case *syntax.Name:
+				checkdef(n)
+
+			case *syntax.SelectorExpr:
+				if name, ok := n.X.(*syntax.Name); ok {
+					if _, isPkg := info.Uses[name].(*types2.PkgName); isPkg {
+						checkdefat(n.X.Pos(), n.Sel)
+						return true
+					}
+				}
+
+			case *syntax.AssignStmt:
+				resolveNode(n.Rhs, top)
+				resolveNode(n.Lhs, top)
+				return true
+
+			case *syntax.VarDecl:
+				resolveNode(n.Values, top)
+
+			case *syntax.FuncLit:
+				if top {
+					resolveNode(n.Type, top)
+					later = append(later, n.Body)
+					return true
+				}
+
+			case *syntax.BlockStmt:
+				if phase >= 3 {
+					for _, stmt := range n.List {
+						resolveNode(stmt, false)
+					}
+				}
+				return true
+			}
+
+			return false
+		})
+	}
+
+	for phase = 1; phase <= 5; phase++ {
+		visited = map[syntax.Decl]bool{}
+
+		for _, p := range noders {
+			for _, decl := range p.file.DeclList {
+				switch decl := decl.(type) {
+				case *syntax.ConstDecl:
+					resolveDecl(decl)
+
+				case *syntax.FuncDecl:
+					resolveDecl(decl)
+					if phase >= 3 && decl.Body != nil {
+						resolveNode(decl.Body, true)
+					}
+
+				case *syntax.TypeDecl:
+					if !decl.Alias || phase >= 2 {
+						resolveDecl(decl)
+					}
+
+				case *syntax.VarDecl:
+					if phase >= 2 {
+						resolveNode(decl.Values, true)
+						resolveDecl(decl)
+					}
+				}
+			}
+
+			if phase >= 5 {
+				syntax.Crawl(p.file, func(n syntax.Node) bool {
+					if name, ok := n.(*syntax.Name); ok {
+						if obj, ok := info.Uses[name]; ok {
+							resolveObj(name.Pos(), obj)
+						}
+					}
+					return false
+				})
+			}
+		}
+
+		for i := 0; i < len(later); i++ {
+			resolveNode(later[i], true)
+		}
+		later = nil
+	}
+
+	return objs
+}
+
+// typeExprEndPos returns the position that noder would leave base.Pos
+// after parsing the given type expression.
+func typeExprEndPos(expr0 syntax.Expr) syntax.Pos {
+	for {
+		switch expr := expr0.(type) {
+		case *syntax.Name:
+			return expr.Pos()
+		case *syntax.SelectorExpr:
+			return expr.X.Pos()
+
+		case *syntax.ParenExpr:
+			expr0 = expr.X
+
+		case *syntax.Operation:
+			assert(expr.Op == syntax.Mul)
+			assert(expr.Y == nil)
+			expr0 = expr.X
+
+		case *syntax.ArrayType:
+			expr0 = expr.Elem
+		case *syntax.ChanType:
+			expr0 = expr.Elem
+		case *syntax.DotsType:
+			expr0 = expr.Elem
+		case *syntax.MapType:
+			expr0 = expr.Value
+		case *syntax.SliceType:
+			expr0 = expr.Elem
+
+		case *syntax.StructType:
+			return expr.Pos()
+
+		case *syntax.InterfaceType:
+			expr0 = lastFieldType(expr.MethodList)
+			if expr0 == nil {
+				return expr.Pos()
+			}
+
+		case *syntax.FuncType:
+			expr0 = lastFieldType(expr.ResultList)
+			if expr0 == nil {
+				expr0 = lastFieldType(expr.ParamList)
+				if expr0 == nil {
+					return expr.Pos()
+				}
+			}
+
+		case *syntax.IndexExpr: // explicit type instantiation
+			targs := unpackListExpr(expr.Index)
+			expr0 = targs[len(targs)-1]
+
+		default:
+			panic(fmt.Sprintf("%s: unexpected type expression %v", expr.Pos(), syntax.String(expr)))
+		}
+	}
+}
+
+func lastFieldType(fields []*syntax.Field) syntax.Expr {
+	if len(fields) == 0 {
+		return nil
+	}
+	return fields[len(fields)-1].Type
+}
+
+// sumPos returns the position that noder.sum would produce for
+// constant expression x.
+func sumPos(x syntax.Expr) syntax.Pos {
+	orig := x
+	for {
+		switch x1 := x.(type) {
+		case *syntax.BasicLit:
+			assert(x1.Kind == syntax.StringLit)
+			return x1.Pos()
+		case *syntax.Operation:
+			assert(x1.Op == syntax.Add && x1.Y != nil)
+			if r, ok := x1.Y.(*syntax.BasicLit); ok {
+				assert(r.Kind == syntax.StringLit)
+				x = x1.X
+				continue
+			}
+		}
+		return orig.Pos()
+	}
+}
+
+// funcParamsEndPos returns the value of base.Pos left by noder after
+// processing a function signature.
+func funcParamsEndPos(fn *ir.Func) src.XPos {
+	sig := fn.Nname.Type()
+
+	fields := sig.Results().FieldSlice()
+	if len(fields) == 0 {
+		fields = sig.Params().FieldSlice()
+		if len(fields) == 0 {
+			fields = sig.Recvs().FieldSlice()
+			if len(fields) == 0 {
+				if fn.OClosure != nil {
+					return fn.Nname.Ntype.Pos()
+				}
+				return fn.Pos()
+			}
+		}
+	}
+
+	return fields[len(fields)-1].Pos
+}
+
+type dupTypes struct {
+	origs map[types2.Type]types2.Type
+}
+
+func (d *dupTypes) orig(t types2.Type) types2.Type {
+	if orig, ok := d.origs[t]; ok {
+		return orig
+	}
+	return t
+}
+
+func (d *dupTypes) add(t, orig types2.Type) {
+	if t == orig {
+		return
+	}
+
+	if d.origs == nil {
+		d.origs = make(map[types2.Type]types2.Type)
+	}
+	assert(d.origs[t] == nil)
+	d.origs[t] = orig
+
+	switch t := t.(type) {
+	case *types2.Pointer:
+		orig := orig.(*types2.Pointer)
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Slice:
+		orig := orig.(*types2.Slice)
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Map:
+		orig := orig.(*types2.Map)
+		d.add(t.Key(), orig.Key())
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Array:
+		orig := orig.(*types2.Array)
+		assert(t.Len() == orig.Len())
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Chan:
+		orig := orig.(*types2.Chan)
+		assert(t.Dir() == orig.Dir())
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Struct:
+		orig := orig.(*types2.Struct)
+		assert(t.NumFields() == orig.NumFields())
+		for i := 0; i < t.NumFields(); i++ {
+			d.add(t.Field(i).Type(), orig.Field(i).Type())
+		}
+
+	case *types2.Interface:
+		orig := orig.(*types2.Interface)
+		assert(t.NumExplicitMethods() == orig.NumExplicitMethods())
+		assert(t.NumEmbeddeds() == orig.NumEmbeddeds())
+		for i := 0; i < t.NumExplicitMethods(); i++ {
+			d.add(t.ExplicitMethod(i).Type(), orig.ExplicitMethod(i).Type())
+		}
+		for i := 0; i < t.NumEmbeddeds(); i++ {
+			d.add(t.EmbeddedType(i), orig.EmbeddedType(i))
+		}
+
+	case *types2.Signature:
+		orig := orig.(*types2.Signature)
+		assert((t.Recv() == nil) == (orig.Recv() == nil))
+		if t.Recv() != nil {
+			d.add(t.Recv().Type(), orig.Recv().Type())
+		}
+		d.add(t.Params(), orig.Params())
+		d.add(t.Results(), orig.Results())
+
+	case *types2.Tuple:
+		orig := orig.(*types2.Tuple)
+		assert(t.Len() == orig.Len())
+		for i := 0; i < t.Len(); i++ {
+			d.add(t.At(i).Type(), orig.At(i).Type())
+		}
+
+	default:
+		assert(types2.Identical(t, orig))
+	}
+}
diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
new file mode 100644
index 0000000000000000000000000000000000000000..985453a1bb3886912710f2e8ee32df378619e6f4
--- /dev/null
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -0,0 +1,2389 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"fmt"
+	"go/constant"
+	"strings"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/deadcode"
+	"cmd/compile/internal/dwarfgen"
+	"cmd/compile/internal/inline"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/reflectdata"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+	"cmd/internal/src"
+)
+
+// TODO(mdempsky): Suppress duplicate type/const errors that can arise
+// during typecheck due to naive type substitution (e.g., see #42758).
+// I anticipate these will be handled as a consequence of adding
+// dictionaries support, so it's probably not important to focus on
+// this until after that's done.
+
+type pkgReader struct {
+	pkgDecoder
+
+	posBases []*src.PosBase
+	pkgs     []*types.Pkg
+	typs     []*types.Type
+
+	// offset for rewriting the given index into the output,
+	// but bitwise inverted so we can detect if we're missing the entry or not.
+	newindex []int
+}
+
+func newPkgReader(pr pkgDecoder) *pkgReader {
+	return &pkgReader{
+		pkgDecoder: pr,
+
+		posBases: make([]*src.PosBase, pr.numElems(relocPosBase)),
+		pkgs:     make([]*types.Pkg, pr.numElems(relocPkg)),
+		typs:     make([]*types.Type, pr.numElems(relocType)),
+
+		newindex: make([]int, pr.totalElems()),
+	}
+}
+
+type pkgReaderIndex struct {
+	pr   *pkgReader
+	idx  int
+	dict *readerDict
+}
+
+func (pri pkgReaderIndex) asReader(k reloc, marker syncMarker) *reader {
+	r := pri.pr.newReader(k, pri.idx, marker)
+	r.dict = pri.dict
+	return r
+}
+
+func (pr *pkgReader) newReader(k reloc, idx int, marker syncMarker) *reader {
+	return &reader{
+		decoder: pr.newDecoder(k, idx, marker),
+		p:       pr,
+	}
+}
+
+type reader struct {
+	decoder
+
+	p *pkgReader
+
+	ext *reader
+
+	dict *readerDict
+
+	// TODO(mdempsky): The state below is all specific to reading
+	// function bodies. It probably makes sense to split it out
+	// separately so that it doesn't take up space in every reader
+	// instance.
+
+	curfn       *ir.Func
+	locals      []*ir.Name
+	closureVars []*ir.Name
+
+	funarghack bool
+
+	// scopeVars is a stack tracking the number of variables declared in
+	// the current function at the moment each open scope was opened.
+	scopeVars         []int
+	marker            dwarfgen.ScopeMarker
+	lastCloseScopePos src.XPos
+
+	// === details for handling inline body expansion ===
+
+	// If we're reading in a function body because of inlining, this is
+	// the call that we're inlining for.
+	inlCaller    *ir.Func
+	inlCall      *ir.CallExpr
+	inlFunc      *ir.Func
+	inlTreeIndex int
+	inlPosBases  map[*src.PosBase]*src.PosBase
+
+	delayResults bool
+
+	// Label to return to.
+	retlabel *types.Sym
+
+	inlvars, retvars ir.Nodes
+}
+
+type readerDict struct {
+	// targs holds the implicit and explicit type arguments in use for
+	// reading the current object. For example:
+	//
+	//	func F[T any]() {
+	//		type X[U any] struct { t T; u U }
+	//		var _ X[string]
+	//	}
+	//
+	//	var _ = F[int]
+	//
+	// While instantiating F[int], we need to in turn instantiate
+	// X[string]. [int] and [string] are explicit type arguments for F
+	// and X, respectively; but [int] is also the implicit type
+	// arguments for X.
+	//
+	// (As an analogy to function literals, explicits are the function
+	// literal's formal parameters, while implicits are variables
+	// captured by the function literal.)
+	targs []*types.Type
+
+	// implicits counts how many of types within targs are implicit type
+	// arguments; the rest are explicit.
+	implicits int
+
+	derived      []derivedInfo // reloc index of the derived type's descriptor
+	derivedTypes []*types.Type // slice of previously computed derived types
+
+	funcs    []objInfo
+	funcsObj []ir.Node
+}
+
+func (r *reader) setType(n ir.Node, typ *types.Type) {
+	n.SetType(typ)
+	n.SetTypecheck(1)
+
+	if name, ok := n.(*ir.Name); ok {
+		name.SetWalkdef(1)
+		name.Ntype = ir.TypeNode(name.Type())
+	}
+}
+
+func (r *reader) setValue(name *ir.Name, val constant.Value) {
+	name.SetVal(val)
+	name.Defn = nil
+}
+
+// @@@ Positions
+
+func (r *reader) pos() src.XPos {
+	return base.Ctxt.PosTable.XPos(r.pos0())
+}
+
+func (r *reader) pos0() src.Pos {
+	r.sync(syncPos)
+	if !r.bool() {
+		return src.NoPos
+	}
+
+	posBase := r.posBase()
+	line := r.uint()
+	col := r.uint()
+	return src.MakePos(posBase, line, col)
+}
+
+func (r *reader) posBase() *src.PosBase {
+	return r.inlPosBase(r.p.posBaseIdx(r.reloc(relocPosBase)))
+}
+
+func (pr *pkgReader) posBaseIdx(idx int) *src.PosBase {
+	if b := pr.posBases[idx]; b != nil {
+		return b
+	}
+
+	r := pr.newReader(relocPosBase, idx, syncPosBase)
+	var b *src.PosBase
+
+	filename := r.string()
+
+	if r.bool() {
+		b = src.NewFileBase(filename, filename)
+	} else {
+		pos := r.pos0()
+		line := r.uint()
+		col := r.uint()
+		b = src.NewLinePragmaBase(pos, filename, filename, line, col)
+	}
+
+	pr.posBases[idx] = b
+	return b
+}
+
+func (r *reader) inlPosBase(oldBase *src.PosBase) *src.PosBase {
+	if r.inlCall == nil {
+		return oldBase
+	}
+
+	if newBase, ok := r.inlPosBases[oldBase]; ok {
+		return newBase
+	}
+
+	newBase := src.NewInliningBase(oldBase, r.inlTreeIndex)
+	r.inlPosBases[oldBase] = newBase
+	return newBase
+}
+
+func (r *reader) updatePos(xpos src.XPos) src.XPos {
+	pos := base.Ctxt.PosTable.Pos(xpos)
+	pos.SetBase(r.inlPosBase(pos.Base()))
+	return base.Ctxt.PosTable.XPos(pos)
+}
+
+func (r *reader) origPos(xpos src.XPos) src.XPos {
+	if r.inlCall == nil {
+		return xpos
+	}
+
+	pos := base.Ctxt.PosTable.Pos(xpos)
+	for old, new := range r.inlPosBases {
+		if pos.Base() == new {
+			pos.SetBase(old)
+			return base.Ctxt.PosTable.XPos(pos)
+		}
+	}
+
+	base.FatalfAt(xpos, "pos base missing from inlPosBases")
+	panic("unreachable")
+}
+
+// @@@ Packages
+
+func (r *reader) pkg() *types.Pkg {
+	r.sync(syncPkg)
+	return r.p.pkgIdx(r.reloc(relocPkg))
+}
+
+func (pr *pkgReader) pkgIdx(idx int) *types.Pkg {
+	if pkg := pr.pkgs[idx]; pkg != nil {
+		return pkg
+	}
+
+	pkg := pr.newReader(relocPkg, idx, syncPkgDef).doPkg()
+	pr.pkgs[idx] = pkg
+	return pkg
+}
+
+func (r *reader) doPkg() *types.Pkg {
+	path := r.string()
+	if path == "builtin" {
+		return types.BuiltinPkg
+	}
+	if path == "" {
+		path = r.p.pkgPath
+	}
+
+	name := r.string()
+	height := r.len()
+
+	pkg := types.NewPkg(path, "")
+
+	if pkg.Name == "" {
+		pkg.Name = name
+	} else {
+		assert(pkg.Name == name)
+	}
+
+	if pkg.Height == 0 {
+		pkg.Height = height
+	} else {
+		assert(pkg.Height == height)
+	}
+
+	return pkg
+}
+
+// @@@ Types
+
+func (r *reader) typ() *types.Type {
+	return r.p.typIdx(r.typInfo(), r.dict)
+}
+
+func (r *reader) typInfo() typeInfo {
+	r.sync(syncType)
+	if r.bool() {
+		return typeInfo{idx: r.len(), derived: true}
+	}
+	return typeInfo{idx: r.reloc(relocType), derived: false}
+}
+
+func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) *types.Type {
+	idx := info.idx
+	var where **types.Type
+	if info.derived {
+		where = &dict.derivedTypes[idx]
+		idx = dict.derived[idx].idx
+	} else {
+		where = &pr.typs[idx]
+	}
+
+	if typ := *where; typ != nil {
+		return typ
+	}
+
+	r := pr.newReader(relocType, idx, syncTypeIdx)
+	r.dict = dict
+
+	typ := r.doTyp()
+	assert(typ != nil)
+
+	// For recursive type declarations involving interfaces and aliases,
+	// above r.doTyp() call may have already set pr.typs[idx], so just
+	// double check and return the type.
+	//
+	// Example:
+	//
+	//     type F = func(I)
+	//
+	//     type I interface {
+	//         m(F)
+	//     }
+	//
+	// The writer writes data types in following index order:
+	//
+	//     0: func(I)
+	//     1: I
+	//     2: interface{m(func(I))}
+	//
+	// The reader resolves it in following index order:
+	//
+	//     0 -> 1 -> 2 -> 0 -> 1
+	//
+	// and can divide in logically 2 steps:
+	//
+	//  - 0 -> 1     : first time the reader reach type I,
+	//                 it creates new named type with symbol I.
+	//
+	//  - 2 -> 0 -> 1: the reader ends up reaching symbol I again,
+	//                 now the symbol I was setup in above step, so
+	//                 the reader just return the named type.
+	//
+	// Now, the functions called return, the pr.typs looks like below:
+	//
+	//  - 0 -> 1 -> 2 -> 0 : [ I ]
+	//  - 0 -> 1 -> 2      : [func(I) I ]
+	//  - 0 -> 1           : [func(I) I interface { "".m(func("".I)) }]
+	//
+	// The idx 1, corresponding with type I was resolved successfully
+	// after r.doTyp() call.
+
+	if prev := *where; prev != nil {
+		return prev
+	}
+
+	*where = typ
+
+	if !typ.IsUntyped() {
+		types.CheckSize(typ)
+	}
+
+	return typ
+}
+
+func (r *reader) doTyp() *types.Type {
+	switch tag := codeType(r.code(syncType)); tag {
+	default:
+		panic(fmt.Sprintf("unexpected type: %v", tag))
+
+	case typeBasic:
+		return *basics[r.len()]
+
+	case typeNamed:
+		obj := r.obj()
+		assert(obj.Op() == ir.OTYPE)
+		return obj.Type()
+
+	case typeTypeParam:
+		return r.dict.targs[r.len()]
+
+	case typeArray:
+		len := int64(r.uint64())
+		return types.NewArray(r.typ(), len)
+	case typeChan:
+		dir := dirs[r.len()]
+		return types.NewChan(r.typ(), dir)
+	case typeMap:
+		return types.NewMap(r.typ(), r.typ())
+	case typePointer:
+		return types.NewPtr(r.typ())
+	case typeSignature:
+		return r.signature(types.LocalPkg, nil)
+	case typeSlice:
+		return types.NewSlice(r.typ())
+	case typeStruct:
+		return r.structType()
+	case typeInterface:
+		return r.interfaceType()
+	}
+}
+
+func (r *reader) interfaceType() *types.Type {
+	tpkg := types.LocalPkg // TODO(mdempsky): Remove after iexport is gone.
+
+	nmethods, nembeddeds := r.len(), r.len()
+
+	fields := make([]*types.Field, nmethods+nembeddeds)
+	methods, embeddeds := fields[:nmethods], fields[nmethods:]
+
+	for i := range methods {
+		pos := r.pos()
+		pkg, sym := r.selector()
+		tpkg = pkg
+		mtyp := r.signature(pkg, typecheck.FakeRecv())
+		methods[i] = types.NewField(pos, sym, mtyp)
+	}
+	for i := range embeddeds {
+		embeddeds[i] = types.NewField(src.NoXPos, nil, r.typ())
+	}
+
+	if len(fields) == 0 {
+		return types.Types[types.TINTER] // empty interface
+	}
+	return r.needWrapper(types.NewInterface(tpkg, fields))
+}
+
+func (r *reader) structType() *types.Type {
+	tpkg := types.LocalPkg // TODO(mdempsky): Remove after iexport is gone.
+	fields := make([]*types.Field, r.len())
+	for i := range fields {
+		pos := r.pos()
+		pkg, sym := r.selector()
+		tpkg = pkg
+		ftyp := r.typ()
+		tag := r.string()
+		embedded := r.bool()
+
+		f := types.NewField(pos, sym, ftyp)
+		f.Note = tag
+		if embedded {
+			f.Embedded = 1
+		}
+		fields[i] = f
+	}
+	return r.needWrapper(types.NewStruct(tpkg, fields))
+}
+
+func (r *reader) signature(tpkg *types.Pkg, recv *types.Field) *types.Type {
+	r.sync(syncSignature)
+
+	params := r.params(&tpkg)
+	results := r.params(&tpkg)
+	if r.bool() { // variadic
+		params[len(params)-1].SetIsDDD(true)
+	}
+
+	return types.NewSignature(tpkg, recv, nil, params, results)
+}
+
+func (r *reader) params(tpkg **types.Pkg) []*types.Field {
+	r.sync(syncParams)
+	fields := make([]*types.Field, r.len())
+	for i := range fields {
+		*tpkg, fields[i] = r.param()
+	}
+	return fields
+}
+
+func (r *reader) param() (*types.Pkg, *types.Field) {
+	r.sync(syncParam)
+
+	pos := r.pos()
+	pkg, sym := r.localIdent()
+	typ := r.typ()
+
+	return pkg, types.NewField(pos, sym, typ)
+}
+
+// @@@ Objects
+
+var objReader = map[*types.Sym]pkgReaderIndex{}
+
+func (r *reader) obj() ir.Node {
+	r.sync(syncObject)
+
+	if r.bool() {
+		idx := r.len()
+		obj := r.dict.funcsObj[idx]
+		if obj == nil {
+			fn := r.dict.funcs[idx]
+			targs := make([]*types.Type, len(fn.explicits))
+			for i, targ := range fn.explicits {
+				targs[i] = r.p.typIdx(targ, r.dict)
+			}
+
+			obj = r.p.objIdx(fn.idx, nil, targs)
+			assert(r.dict.funcsObj[idx] == nil)
+			r.dict.funcsObj[idx] = obj
+		}
+		return obj
+	}
+
+	idx := r.reloc(relocObj)
+
+	explicits := make([]*types.Type, r.len())
+	for i := range explicits {
+		explicits[i] = r.typ()
+	}
+
+	var implicits []*types.Type
+	if r.dict != nil {
+		implicits = r.dict.targs
+	}
+
+	return r.p.objIdx(idx, implicits, explicits)
+}
+
+func (pr *pkgReader) objIdx(idx int, implicits, explicits []*types.Type) ir.Node {
+	rname := pr.newReader(relocName, idx, syncObject1)
+	_, sym := rname.qualifiedIdent()
+	tag := codeObj(rname.code(syncCodeObj))
+
+	if tag == objStub {
+		assert(!sym.IsBlank())
+		switch sym.Pkg {
+		case types.BuiltinPkg, ir.Pkgs.Unsafe:
+			return sym.Def.(ir.Node)
+		}
+		if pri, ok := objReader[sym]; ok {
+			return pri.pr.objIdx(pri.idx, nil, explicits)
+		}
+		if haveLegacyImports {
+			assert(len(explicits) == 0)
+			return typecheck.Resolve(ir.NewIdent(src.NoXPos, sym))
+		}
+		base.Fatalf("unresolved stub: %v", sym)
+	}
+
+	dict := pr.objDictIdx(sym, idx, implicits, explicits)
+
+	r := pr.newReader(relocObj, idx, syncObject1)
+	r.ext = pr.newReader(relocObjExt, idx, syncObject1)
+
+	r.dict = dict
+	r.ext.dict = dict
+
+	sym = r.mangle(sym)
+	if !sym.IsBlank() && sym.Def != nil {
+		return sym.Def.(*ir.Name)
+	}
+
+	do := func(op ir.Op, hasTParams bool) *ir.Name {
+		pos := r.pos()
+		if hasTParams {
+			r.typeParamNames()
+		}
+
+		name := ir.NewDeclNameAt(pos, op, sym)
+		name.Class = ir.PEXTERN // may be overridden later
+		if !sym.IsBlank() {
+			if sym.Def != nil {
+				base.FatalfAt(name.Pos(), "already have a definition for %v", name)
+			}
+			assert(sym.Def == nil)
+			sym.Def = name
+		}
+		return name
+	}
+
+	switch tag {
+	default:
+		panic("unexpected object")
+
+	case objAlias:
+		name := do(ir.OTYPE, false)
+		r.setType(name, r.typ())
+		name.SetAlias(true)
+		return name
+
+	case objConst:
+		name := do(ir.OLITERAL, false)
+		typ, val := r.value()
+		r.setType(name, typ)
+		r.setValue(name, val)
+		return name
+
+	case objFunc:
+		if sym.Name == "init" {
+			sym = renameinit()
+		}
+		name := do(ir.ONAME, true)
+		r.setType(name, r.signature(sym.Pkg, nil))
+
+		name.Func = ir.NewFunc(r.pos())
+		name.Func.Nname = name
+
+		r.ext.funcExt(name)
+		return name
+
+	case objType:
+		name := do(ir.OTYPE, true)
+		typ := types.NewNamed(name)
+		r.setType(name, typ)
+
+		// Important: We need to do this before SetUnderlying.
+		r.ext.typeExt(name)
+
+		// We need to defer CheckSize until we've called SetUnderlying to
+		// handle recursive types.
+		types.DeferCheckSize()
+		typ.SetUnderlying(r.typ())
+		types.ResumeCheckSize()
+
+		methods := make([]*types.Field, r.len())
+		for i := range methods {
+			methods[i] = r.method()
+		}
+		if len(methods) != 0 {
+			typ.Methods().Set(methods)
+		}
+
+		if !typ.IsPtr() {
+			r.needWrapper(typ)
+		}
+
+		return name
+
+	case objVar:
+		name := do(ir.ONAME, false)
+		r.setType(name, r.typ())
+		r.ext.varExt(name)
+		return name
+	}
+}
+
+func (r *reader) mangle(sym *types.Sym) *types.Sym {
+	if !r.hasTypeParams() {
+		return sym
+	}
+
+	var buf bytes.Buffer
+	buf.WriteString(sym.Name)
+	buf.WriteByte('[')
+	for i, targ := range r.dict.targs {
+		if i > 0 {
+			if i == r.dict.implicits {
+				buf.WriteByte(';')
+			} else {
+				buf.WriteByte(',')
+			}
+		}
+		buf.WriteString(targ.LinkString())
+	}
+	buf.WriteByte(']')
+	return sym.Pkg.Lookup(buf.String())
+}
+
+func (pr *pkgReader) objDictIdx(sym *types.Sym, idx int, implicits, explicits []*types.Type) *readerDict {
+	r := pr.newReader(relocObjDict, idx, syncObject1)
+
+	var dict readerDict
+
+	nimplicits := r.len()
+	nexplicits := r.len()
+
+	if nimplicits > len(implicits) || nexplicits != len(explicits) {
+		base.Fatalf("%v has %v+%v params, but instantiated with %v+%v args", sym, nimplicits, nexplicits, len(implicits), len(explicits))
+	}
+
+	dict.targs = append(implicits[:nimplicits:nimplicits], explicits...)
+	dict.implicits = nimplicits
+
+	// For stenciling, we can just skip over the type parameters.
+	for range dict.targs[dict.implicits:] {
+		// Skip past bounds without actually evaluating them.
+		r.sync(syncType)
+		if r.bool() {
+			r.len()
+		} else {
+			r.reloc(relocType)
+		}
+	}
+
+	dict.derived = make([]derivedInfo, r.len())
+	dict.derivedTypes = make([]*types.Type, len(dict.derived))
+	for i := range dict.derived {
+		dict.derived[i] = derivedInfo{r.reloc(relocType), r.bool()}
+	}
+
+	dict.funcs = make([]objInfo, r.len())
+	dict.funcsObj = make([]ir.Node, len(dict.funcs))
+	for i := range dict.funcs {
+		objIdx := r.reloc(relocObj)
+		targs := make([]typeInfo, r.len())
+		for j := range targs {
+			targs[j] = r.typInfo()
+		}
+		dict.funcs[i] = objInfo{idx: objIdx, explicits: targs}
+	}
+
+	return &dict
+}
+
+func (r *reader) typeParamNames() {
+	r.sync(syncTypeParamNames)
+
+	for range r.dict.targs[r.dict.implicits:] {
+		r.pos()
+		r.localIdent()
+	}
+}
+
+func (r *reader) value() (*types.Type, constant.Value) {
+	r.sync(syncValue)
+	typ := r.typ()
+	return typ, FixValue(typ, r.rawValue())
+}
+
+func (r *reader) method() *types.Field {
+	r.sync(syncMethod)
+	pos := r.pos()
+	pkg, sym := r.selector()
+	r.typeParamNames()
+	_, recv := r.param()
+	typ := r.signature(pkg, recv)
+
+	fnsym := sym
+	fnsym = ir.MethodSym(recv.Type, fnsym)
+	name := ir.NewNameAt(pos, fnsym)
+	r.setType(name, typ)
+
+	name.Func = ir.NewFunc(r.pos())
+	name.Func.Nname = name
+
+	r.ext.funcExt(name)
+
+	meth := types.NewField(name.Func.Pos(), sym, typ)
+	meth.Nname = name
+	meth.SetNointerface(name.Func.Pragma&ir.Nointerface != 0)
+
+	return meth
+}
+
+func (r *reader) qualifiedIdent() (pkg *types.Pkg, sym *types.Sym) {
+	r.sync(syncSym)
+	pkg = r.pkg()
+	if name := r.string(); name != "" {
+		sym = pkg.Lookup(name)
+	}
+	return
+}
+
+func (r *reader) localIdent() (pkg *types.Pkg, sym *types.Sym) {
+	r.sync(syncLocalIdent)
+	pkg = r.pkg()
+	if name := r.string(); name != "" {
+		sym = pkg.Lookup(name)
+	}
+	return
+}
+
+func (r *reader) selector() (origPkg *types.Pkg, sym *types.Sym) {
+	r.sync(syncSelector)
+	origPkg = r.pkg()
+	name := r.string()
+	pkg := origPkg
+	if types.IsExported(name) {
+		pkg = types.LocalPkg
+	}
+	sym = pkg.Lookup(name)
+	return
+}
+
+func (r *reader) hasTypeParams() bool {
+	return r.dict.hasTypeParams()
+}
+
+func (dict *readerDict) hasTypeParams() bool {
+	return dict != nil && len(dict.targs) != 0
+}
+
+// @@@ Compiler extensions
+
+func (r *reader) funcExt(name *ir.Name) {
+	r.sync(syncFuncExt)
+
+	name.Class = 0 // so MarkFunc doesn't complain
+	ir.MarkFunc(name)
+
+	fn := name.Func
+
+	// XXX: Workaround because linker doesn't know how to copy Pos.
+	if !fn.Pos().IsKnown() {
+		fn.SetPos(name.Pos())
+	}
+
+	// Normally, we only compile local functions, which saves redundant compilation work.
+	// n.Defn is not nil for local functions, and is nil for imported function. But for
+	// generic functions, we might have an instantiation that no other package has seen before.
+	// So we need to be conservative and compile it again.
+	//
+	// That's why name.Defn is set here, so ir.VisitFuncsBottomUp can analyze function.
+	// TODO(mdempsky,cuonglm): find a cleaner way to handle this.
+	if name.Sym().Pkg == types.LocalPkg || r.hasTypeParams() {
+		name.Defn = fn
+	}
+
+	fn.Pragma = r.pragmaFlag()
+	r.linkname(name)
+
+	typecheck.Func(fn)
+
+	if r.bool() {
+		fn.ABI = obj.ABI(r.uint64())
+
+		// Escape analysis.
+		for _, fs := range &types.RecvsParams {
+			for _, f := range fs(name.Type()).FieldSlice() {
+				f.Note = r.string()
+			}
+		}
+
+		if r.bool() {
+			fn.Inl = &ir.Inline{
+				Cost:            int32(r.len()),
+				CanDelayResults: r.bool(),
+			}
+			r.addBody(name.Func)
+		}
+	} else {
+		r.addBody(name.Func)
+	}
+	r.sync(syncEOF)
+}
+
+func (r *reader) typeExt(name *ir.Name) {
+	r.sync(syncTypeExt)
+
+	typ := name.Type()
+
+	if r.hasTypeParams() {
+		// Set "RParams" (really type arguments here, not parameters) so
+		// this type is treated as "fully instantiated". This ensures the
+		// type descriptor is written out as DUPOK and method wrappers are
+		// generated even for imported types.
+		var targs []*types.Type
+		targs = append(targs, r.dict.targs...)
+		typ.SetRParams(targs)
+	}
+
+	name.SetPragma(r.pragmaFlag())
+	if name.Pragma()&ir.NotInHeap != 0 {
+		typ.SetNotInHeap(true)
+	}
+
+	typecheck.SetBaseTypeIndex(typ, r.int64(), r.int64())
+}
+
+func (r *reader) varExt(name *ir.Name) {
+	r.sync(syncVarExt)
+	r.linkname(name)
+}
+
+func (r *reader) linkname(name *ir.Name) {
+	assert(name.Op() == ir.ONAME)
+	r.sync(syncLinkname)
+
+	if idx := r.int64(); idx >= 0 {
+		lsym := name.Linksym()
+		lsym.SymIdx = int32(idx)
+		lsym.Set(obj.AttrIndexed, true)
+	} else {
+		name.Sym().Linkname = r.string()
+	}
+}
+
+func (r *reader) pragmaFlag() ir.PragmaFlag {
+	r.sync(syncPragma)
+	return ir.PragmaFlag(r.int())
+}
+
+// @@@ Function bodies
+
+// bodyReader tracks where the serialized IR for a function's body can
+// be found.
+var bodyReader = map[*ir.Func]pkgReaderIndex{}
+
+// todoBodies holds the list of function bodies that still need to be
+// constructed.
+var todoBodies []*ir.Func
+
+func (r *reader) addBody(fn *ir.Func) {
+	pri := pkgReaderIndex{r.p, r.reloc(relocBody), r.dict}
+	bodyReader[fn] = pri
+
+	if r.curfn == nil {
+		todoBodies = append(todoBodies, fn)
+		return
+	}
+
+	pri.funcBody(fn)
+}
+
+func (pri pkgReaderIndex) funcBody(fn *ir.Func) {
+	r := pri.asReader(relocBody, syncFuncBody)
+	r.funcBody(fn)
+}
+
+func (r *reader) funcBody(fn *ir.Func) {
+	r.curfn = fn
+	r.closureVars = fn.ClosureVars
+
+	ir.WithFunc(fn, func() {
+		r.funcargs(fn)
+
+		if !r.bool() {
+			return
+		}
+
+		body := r.stmts()
+		if body == nil {
+			pos := src.NoXPos
+			if quirksMode() {
+				pos = funcParamsEndPos(fn)
+			}
+			body = []ir.Node{typecheck.Stmt(ir.NewBlockStmt(pos, nil))}
+		}
+		fn.Body = body
+		fn.Endlineno = r.pos()
+	})
+
+	r.marker.WriteTo(fn)
+}
+
+func (r *reader) funcargs(fn *ir.Func) {
+	sig := fn.Nname.Type()
+
+	if recv := sig.Recv(); recv != nil {
+		r.funcarg(recv, recv.Sym, ir.PPARAM)
+	}
+	for _, param := range sig.Params().FieldSlice() {
+		r.funcarg(param, param.Sym, ir.PPARAM)
+	}
+
+	for i, param := range sig.Results().FieldSlice() {
+		sym := types.OrigSym(param.Sym)
+
+		if sym == nil || sym.IsBlank() {
+			prefix := "~r"
+			if r.inlCall != nil {
+				prefix = "~R"
+			} else if sym != nil {
+				prefix = "~b"
+			}
+			sym = typecheck.LookupNum(prefix, i)
+		}
+
+		r.funcarg(param, sym, ir.PPARAMOUT)
+	}
+}
+
+func (r *reader) funcarg(param *types.Field, sym *types.Sym, ctxt ir.Class) {
+	if sym == nil {
+		assert(ctxt == ir.PPARAM)
+		if r.inlCall != nil {
+			r.inlvars.Append(ir.BlankNode)
+		}
+		return
+	}
+
+	name := ir.NewNameAt(r.updatePos(param.Pos), sym)
+	r.setType(name, param.Type)
+	r.addLocal(name, ctxt)
+
+	if r.inlCall == nil {
+		if !r.funarghack {
+			param.Sym = sym
+			param.Nname = name
+		}
+	} else {
+		if ctxt == ir.PPARAMOUT {
+			r.retvars.Append(name)
+		} else {
+			r.inlvars.Append(name)
+		}
+	}
+}
+
+func (r *reader) addLocal(name *ir.Name, ctxt ir.Class) {
+	assert(ctxt == ir.PAUTO || ctxt == ir.PPARAM || ctxt == ir.PPARAMOUT)
+
+	r.sync(syncAddLocal)
+	if enableSync {
+		want := r.int()
+		if have := len(r.locals); have != want {
+			base.FatalfAt(name.Pos(), "locals table has desynced")
+		}
+	}
+
+	name.SetUsed(true)
+	r.locals = append(r.locals, name)
+
+	// TODO(mdempsky): Move earlier.
+	if ir.IsBlank(name) {
+		return
+	}
+
+	if r.inlCall != nil {
+		if ctxt == ir.PAUTO {
+			name.SetInlLocal(true)
+		} else {
+			name.SetInlFormal(true)
+			ctxt = ir.PAUTO
+		}
+
+		// TODO(mdempsky): Rethink this hack.
+		if strings.HasPrefix(name.Sym().Name, "~") || base.Flag.GenDwarfInl == 0 {
+			name.SetPos(r.inlCall.Pos())
+			name.SetInlFormal(false)
+			name.SetInlLocal(false)
+		}
+	}
+
+	name.Class = ctxt
+	name.Curfn = r.curfn
+
+	r.curfn.Dcl = append(r.curfn.Dcl, name)
+
+	if ctxt == ir.PAUTO {
+		name.SetFrameOffset(0)
+	}
+}
+
+func (r *reader) useLocal() *ir.Name {
+	r.sync(syncUseObjLocal)
+	if r.bool() {
+		return r.locals[r.len()]
+	}
+	return r.closureVars[r.len()]
+}
+
+func (r *reader) openScope() {
+	r.sync(syncOpenScope)
+	pos := r.pos()
+
+	if base.Flag.Dwarf {
+		r.scopeVars = append(r.scopeVars, len(r.curfn.Dcl))
+		r.marker.Push(pos)
+	}
+}
+
+func (r *reader) closeScope() {
+	r.sync(syncCloseScope)
+	r.lastCloseScopePos = r.pos()
+
+	r.closeAnotherScope()
+}
+
+// closeAnotherScope is like closeScope, but it reuses the same mark
+// position as the last closeScope call. This is useful for "for" and
+// "if" statements, as their implicit blocks always end at the same
+// position as an explicit block.
+func (r *reader) closeAnotherScope() {
+	r.sync(syncCloseAnotherScope)
+
+	if base.Flag.Dwarf {
+		scopeVars := r.scopeVars[len(r.scopeVars)-1]
+		r.scopeVars = r.scopeVars[:len(r.scopeVars)-1]
+
+		// Quirkish: noder decides which scopes to keep before
+		// typechecking, whereas incremental typechecking during IR
+		// construction can result in new autotemps being allocated. To
+		// produce identical output, we ignore autotemps here for the
+		// purpose of deciding whether to retract the scope.
+		//
+		// This is important for net/http/fcgi, because it contains:
+		//
+		//	var body io.ReadCloser
+		//	if len(content) > 0 {
+		//		body, req.pw = io.Pipe()
+		//	} else { … }
+		//
+		// Notably, io.Pipe is inlinable, and inlining it introduces a ~R0
+		// variable at the call site.
+		//
+		// Noder does not preserve the scope where the io.Pipe() call
+		// resides, because it doesn't contain any declared variables in
+		// source. So the ~R0 variable ends up being assigned to the
+		// enclosing scope instead.
+		//
+		// However, typechecking this assignment also introduces
+		// autotemps, because io.Pipe's results need conversion before
+		// they can be assigned to their respective destination variables.
+		//
+		// TODO(mdempsky): We should probably just keep all scopes, and
+		// let dwarfgen take care of pruning them instead.
+		retract := true
+		for _, n := range r.curfn.Dcl[scopeVars:] {
+			if !n.AutoTemp() {
+				retract = false
+				break
+			}
+		}
+
+		if retract {
+			// no variables were declared in this scope, so we can retract it.
+			r.marker.Unpush()
+		} else {
+			r.marker.Pop(r.lastCloseScopePos)
+		}
+	}
+}
+
+// @@@ Statements
+
+func (r *reader) stmt() ir.Node {
+	switch stmts := r.stmts(); len(stmts) {
+	case 0:
+		return nil
+	case 1:
+		return stmts[0]
+	default:
+		return ir.NewBlockStmt(stmts[0].Pos(), stmts)
+	}
+}
+
+func (r *reader) stmts() []ir.Node {
+	assert(ir.CurFunc == r.curfn)
+	var res ir.Nodes
+
+	r.sync(syncStmts)
+	for {
+		tag := codeStmt(r.code(syncStmt1))
+		if tag == stmtEnd {
+			r.sync(syncStmtsEnd)
+			return res
+		}
+
+		if n := r.stmt1(tag, &res); n != nil {
+			res.Append(typecheck.Stmt(n))
+		}
+	}
+}
+
+func (r *reader) stmt1(tag codeStmt, out *ir.Nodes) ir.Node {
+	var label *types.Sym
+	if n := len(*out); n > 0 {
+		if ls, ok := (*out)[n-1].(*ir.LabelStmt); ok {
+			label = ls.Label
+		}
+	}
+
+	switch tag {
+	default:
+		panic("unexpected statement")
+
+	case stmtAssign:
+		pos := r.pos()
+
+		// TODO(mdempsky): After quirks mode is gone, swap these
+		// statements so we visit LHS before RHS again.
+		rhs := r.exprList()
+		names, lhs := r.assignList()
+
+		if len(rhs) == 0 {
+			for _, name := range names {
+				as := ir.NewAssignStmt(pos, name, nil)
+				as.PtrInit().Append(ir.NewDecl(pos, ir.ODCL, name))
+				out.Append(typecheck.Stmt(as))
+			}
+			return nil
+		}
+
+		if len(lhs) == 1 && len(rhs) == 1 {
+			n := ir.NewAssignStmt(pos, lhs[0], rhs[0])
+			n.Def = r.initDefn(n, names)
+			return n
+		}
+
+		n := ir.NewAssignListStmt(pos, ir.OAS2, lhs, rhs)
+		n.Def = r.initDefn(n, names)
+		return n
+
+	case stmtAssignOp:
+		op := r.op()
+		lhs := r.expr()
+		pos := r.pos()
+		rhs := r.expr()
+		return ir.NewAssignOpStmt(pos, op, lhs, rhs)
+
+	case stmtIncDec:
+		op := r.op()
+		lhs := r.expr()
+		pos := r.pos()
+		n := ir.NewAssignOpStmt(pos, op, lhs, ir.NewBasicLit(pos, one))
+		n.IncDec = true
+		return n
+
+	case stmtBlock:
+		out.Append(r.blockStmt()...)
+		return nil
+
+	case stmtBranch:
+		pos := r.pos()
+		op := r.op()
+		sym := r.optLabel()
+		return ir.NewBranchStmt(pos, op, sym)
+
+	case stmtCall:
+		pos := r.pos()
+		op := r.op()
+		call := r.expr()
+		return ir.NewGoDeferStmt(pos, op, call)
+
+	case stmtExpr:
+		return r.expr()
+
+	case stmtFor:
+		return r.forStmt(label)
+
+	case stmtIf:
+		return r.ifStmt()
+
+	case stmtLabel:
+		pos := r.pos()
+		sym := r.label()
+		return ir.NewLabelStmt(pos, sym)
+
+	case stmtReturn:
+		pos := r.pos()
+		results := r.exprList()
+		return ir.NewReturnStmt(pos, results)
+
+	case stmtSelect:
+		return r.selectStmt(label)
+
+	case stmtSend:
+		pos := r.pos()
+		ch := r.expr()
+		value := r.expr()
+		return ir.NewSendStmt(pos, ch, value)
+
+	case stmtSwitch:
+		return r.switchStmt(label)
+
+	case stmtTypeDeclHack:
+		// fake "type _ = int" declaration to prevent inlining in quirks mode.
+		assert(quirksMode())
+
+		name := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.BlankNode.Sym())
+		name.SetAlias(true)
+		r.setType(name, types.Types[types.TINT])
+
+		n := ir.NewDecl(src.NoXPos, ir.ODCLTYPE, name)
+		n.SetTypecheck(1)
+		return n
+	}
+}
+
+func (r *reader) assignList() ([]*ir.Name, []ir.Node) {
+	lhs := make([]ir.Node, r.len())
+	var names []*ir.Name
+
+	for i := range lhs {
+		if r.bool() {
+			pos := r.pos()
+			_, sym := r.localIdent()
+			typ := r.typ()
+
+			name := ir.NewNameAt(pos, sym)
+			lhs[i] = name
+			names = append(names, name)
+			r.setType(name, typ)
+			r.addLocal(name, ir.PAUTO)
+			continue
+		}
+
+		lhs[i] = r.expr()
+	}
+
+	return names, lhs
+}
+
+func (r *reader) blockStmt() []ir.Node {
+	r.sync(syncBlockStmt)
+	r.openScope()
+	stmts := r.stmts()
+	r.closeScope()
+	return stmts
+}
+
+func (r *reader) forStmt(label *types.Sym) ir.Node {
+	r.sync(syncForStmt)
+
+	r.openScope()
+
+	if r.bool() {
+		pos := r.pos()
+
+		// TODO(mdempsky): After quirks mode is gone, swap these
+		// statements so we read LHS before X again.
+		x := r.expr()
+		names, lhs := r.assignList()
+
+		body := r.blockStmt()
+		r.closeAnotherScope()
+
+		rang := ir.NewRangeStmt(pos, nil, nil, x, body)
+		if len(lhs) >= 1 {
+			rang.Key = lhs[0]
+			if len(lhs) >= 2 {
+				rang.Value = lhs[1]
+			}
+		}
+		rang.Def = r.initDefn(rang, names)
+		rang.Label = label
+		return rang
+	}
+
+	pos := r.pos()
+	init := r.stmt()
+	cond := r.expr()
+	post := r.stmt()
+	body := r.blockStmt()
+	r.closeAnotherScope()
+
+	stmt := ir.NewForStmt(pos, init, cond, post, body)
+	stmt.Label = label
+	return stmt
+}
+
+func (r *reader) ifStmt() ir.Node {
+	r.sync(syncIfStmt)
+	r.openScope()
+	pos := r.pos()
+	init := r.stmts()
+	cond := r.expr()
+	then := r.blockStmt()
+	els := r.stmts()
+	n := ir.NewIfStmt(pos, cond, then, els)
+	n.SetInit(init)
+	r.closeAnotherScope()
+	return n
+}
+
+func (r *reader) selectStmt(label *types.Sym) ir.Node {
+	r.sync(syncSelectStmt)
+
+	pos := r.pos()
+	clauses := make([]*ir.CommClause, r.len())
+	for i := range clauses {
+		if i > 0 {
+			r.closeScope()
+		}
+		r.openScope()
+
+		pos := r.pos()
+		comm := r.stmt()
+		body := r.stmts()
+
+		clauses[i] = ir.NewCommStmt(pos, comm, body)
+	}
+	if len(clauses) > 0 {
+		r.closeScope()
+	}
+	n := ir.NewSelectStmt(pos, clauses)
+	n.Label = label
+	return n
+}
+
+func (r *reader) switchStmt(label *types.Sym) ir.Node {
+	r.sync(syncSwitchStmt)
+
+	r.openScope()
+	pos := r.pos()
+	init := r.stmt()
+
+	var tag ir.Node
+	if r.bool() {
+		pos := r.pos()
+		var ident *ir.Ident
+		if r.bool() {
+			pos := r.pos()
+			sym := typecheck.Lookup(r.string())
+			ident = ir.NewIdent(pos, sym)
+		}
+		x := r.expr()
+		tag = ir.NewTypeSwitchGuard(pos, ident, x)
+	} else {
+		tag = r.expr()
+	}
+
+	tswitch, ok := tag.(*ir.TypeSwitchGuard)
+	if ok && tswitch.Tag == nil {
+		tswitch = nil
+	}
+
+	clauses := make([]*ir.CaseClause, r.len())
+	for i := range clauses {
+		if i > 0 {
+			r.closeScope()
+		}
+		r.openScope()
+
+		pos := r.pos()
+		cases := r.exprList()
+
+		clause := ir.NewCaseStmt(pos, cases, nil)
+		if tswitch != nil {
+			pos := r.pos()
+			typ := r.typ()
+
+			name := ir.NewNameAt(pos, tswitch.Tag.Sym())
+			r.setType(name, typ)
+			r.addLocal(name, ir.PAUTO)
+			clause.Var = name
+			name.Defn = tswitch
+		}
+
+		clause.Body = r.stmts()
+		clauses[i] = clause
+	}
+	if len(clauses) > 0 {
+		r.closeScope()
+	}
+	r.closeScope()
+
+	n := ir.NewSwitchStmt(pos, tag, clauses)
+	n.Label = label
+	if init != nil {
+		n.SetInit([]ir.Node{init})
+	}
+	return n
+}
+
+func (r *reader) label() *types.Sym {
+	r.sync(syncLabel)
+	name := r.string()
+	if r.inlCall != nil {
+		name = fmt.Sprintf("~%s·%d", name, inlgen)
+	}
+	return typecheck.Lookup(name)
+}
+
+func (r *reader) optLabel() *types.Sym {
+	r.sync(syncOptLabel)
+	if r.bool() {
+		return r.label()
+	}
+	return nil
+}
+
+// initDefn marks the given names as declared by defn and populates
+// its Init field with ODCL nodes. It then reports whether any names
+// were so declared, which can be used to initialize defn.Def.
+func (r *reader) initDefn(defn ir.InitNode, names []*ir.Name) bool {
+	if len(names) == 0 {
+		return false
+	}
+
+	init := make([]ir.Node, len(names))
+	for i, name := range names {
+		name.Defn = defn
+		init[i] = ir.NewDecl(name.Pos(), ir.ODCL, name)
+	}
+	defn.SetInit(init)
+	return true
+}
+
+// @@@ Expressions
+
+// expr reads and returns a typechecked expression.
+func (r *reader) expr() (res ir.Node) {
+	defer func() {
+		if res != nil && res.Typecheck() == 0 {
+			base.FatalfAt(res.Pos(), "%v missed typecheck", res)
+		}
+	}()
+
+	switch tag := codeExpr(r.code(syncExpr)); tag {
+	default:
+		panic("unhandled expression")
+
+	case exprNone:
+		return nil
+
+	case exprBlank:
+		// blank only allowed in LHS of assignments
+		// TODO(mdempsky): Handle directly in assignList instead?
+		return typecheck.AssignExpr(ir.BlankNode)
+
+	case exprLocal:
+		return typecheck.Expr(r.useLocal())
+
+	case exprName:
+		// Callee instead of Expr allows builtins
+		// TODO(mdempsky): Handle builtins directly in exprCall, like method calls?
+		return typecheck.Callee(r.obj())
+
+	case exprType:
+		// TODO(mdempsky): ir.TypeNode should probably return a typecheck'd node.
+		n := ir.TypeNode(r.typ())
+		n.SetTypecheck(1)
+		return n
+
+	case exprConst:
+		pos := r.pos()
+		typ, val := r.value()
+		op := r.op()
+		orig := r.string()
+		return typecheck.Expr(OrigConst(pos, typ, val, op, orig))
+
+	case exprCompLit:
+		return r.compLit()
+
+	case exprFuncLit:
+		return r.funcLit()
+
+	case exprSelector:
+		x := r.expr()
+		pos := r.pos()
+		_, sym := r.selector()
+		return typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, x, sym))
+
+	case exprIndex:
+		x := r.expr()
+		pos := r.pos()
+		index := r.expr()
+		return typecheck.Expr(ir.NewIndexExpr(pos, x, index))
+
+	case exprSlice:
+		x := r.expr()
+		pos := r.pos()
+		var index [3]ir.Node
+		for i := range index {
+			index[i] = r.expr()
+		}
+		op := ir.OSLICE
+		if index[2] != nil {
+			op = ir.OSLICE3
+		}
+		return typecheck.Expr(ir.NewSliceExpr(pos, op, x, index[0], index[1], index[2]))
+
+	case exprAssert:
+		x := r.expr()
+		pos := r.pos()
+		typ := r.expr().(ir.Ntype)
+		return typecheck.Expr(ir.NewTypeAssertExpr(pos, x, typ))
+
+	case exprUnaryOp:
+		op := r.op()
+		pos := r.pos()
+		x := r.expr()
+
+		switch op {
+		case ir.OADDR:
+			return typecheck.Expr(typecheck.NodAddrAt(pos, x))
+		case ir.ODEREF:
+			return typecheck.Expr(ir.NewStarExpr(pos, x))
+		}
+		return typecheck.Expr(ir.NewUnaryExpr(pos, op, x))
+
+	case exprBinaryOp:
+		op := r.op()
+		x := r.expr()
+		pos := r.pos()
+		y := r.expr()
+
+		switch op {
+		case ir.OANDAND, ir.OOROR:
+			return typecheck.Expr(ir.NewLogicalExpr(pos, op, x, y))
+		}
+		return typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
+
+	case exprCall:
+		fun := r.expr()
+		if r.bool() { // method call
+			pos := r.pos()
+			_, sym := r.selector()
+			fun = typecheck.Callee(ir.NewSelectorExpr(pos, ir.OXDOT, fun, sym))
+		}
+		pos := r.pos()
+		args := r.exprs()
+		dots := r.bool()
+		return typecheck.Call(pos, fun, args, dots)
+
+	case exprConvert:
+		typ := r.typ()
+		pos := r.pos()
+		x := r.expr()
+		return typecheck.Expr(ir.NewConvExpr(pos, ir.OCONV, typ, x))
+	}
+}
+
+func (r *reader) compLit() ir.Node {
+	r.sync(syncCompLit)
+	pos := r.pos()
+	typ0 := r.typ()
+
+	typ := typ0
+	if typ.IsPtr() {
+		typ = typ.Elem()
+	}
+	if typ.Kind() == types.TFORW {
+		base.FatalfAt(pos, "unresolved composite literal type: %v", typ)
+	}
+	isStruct := typ.Kind() == types.TSTRUCT
+
+	elems := make([]ir.Node, r.len())
+	for i := range elems {
+		elemp := &elems[i]
+
+		if isStruct {
+			sk := ir.NewStructKeyExpr(r.pos(), typ.Field(r.len()), nil)
+			*elemp, elemp = sk, &sk.Value
+		} else if r.bool() {
+			kv := ir.NewKeyExpr(r.pos(), r.expr(), nil)
+			*elemp, elemp = kv, &kv.Value
+		}
+
+		*elemp = wrapName(r.pos(), r.expr())
+	}
+
+	lit := typecheck.Expr(ir.NewCompLitExpr(pos, ir.OCOMPLIT, ir.TypeNode(typ), elems))
+	if typ0.IsPtr() {
+		lit = typecheck.Expr(typecheck.NodAddrAt(pos, lit))
+		lit.SetType(typ0)
+	}
+	return lit
+}
+
+func wrapName(pos src.XPos, x ir.Node) ir.Node {
+	// These nodes do not carry line numbers.
+	// Introduce a wrapper node to give them the correct line.
+	switch ir.Orig(x).Op() {
+	case ir.OTYPE, ir.OLITERAL:
+		if x.Sym() == nil {
+			break
+		}
+		fallthrough
+	case ir.ONAME, ir.ONONAME, ir.OPACK, ir.ONIL:
+		p := ir.NewParenExpr(pos, x)
+		p.SetImplicit(true)
+		return p
+	}
+	return x
+}
+
+func (r *reader) funcLit() ir.Node {
+	r.sync(syncFuncLit)
+
+	pos := r.pos()
+	typPos := r.pos()
+	xtype2 := r.signature(types.LocalPkg, nil)
+
+	opos := pos
+	if quirksMode() {
+		opos = r.origPos(pos)
+	}
+
+	fn := ir.NewClosureFunc(opos, r.curfn != nil)
+	clo := fn.OClosure
+	ir.NameClosure(clo, r.curfn)
+
+	r.setType(fn.Nname, xtype2)
+	if quirksMode() {
+		fn.Nname.Ntype = ir.TypeNodeAt(typPos, xtype2)
+	}
+	typecheck.Func(fn)
+	r.setType(clo, fn.Type())
+
+	fn.ClosureVars = make([]*ir.Name, 0, r.len())
+	for len(fn.ClosureVars) < cap(fn.ClosureVars) {
+		ir.NewClosureVar(r.pos(), fn, r.useLocal())
+	}
+
+	r.addBody(fn)
+
+	// TODO(mdempsky): Remove hard-coding of typecheck.Target.
+	return ir.UseClosure(clo, typecheck.Target)
+}
+
+func (r *reader) exprList() []ir.Node {
+	r.sync(syncExprList)
+	return r.exprs()
+}
+
+func (r *reader) exprs() []ir.Node {
+	r.sync(syncExprs)
+	nodes := make([]ir.Node, r.len())
+	if len(nodes) == 0 {
+		return nil // TODO(mdempsky): Unclear if this matters.
+	}
+	for i := range nodes {
+		nodes[i] = r.expr()
+	}
+	return nodes
+}
+
+func (r *reader) op() ir.Op {
+	r.sync(syncOp)
+	return ir.Op(r.len())
+}
+
+// @@@ Package initialization
+
+func (r *reader) pkgInit(self *types.Pkg, target *ir.Package) {
+	if quirksMode() {
+		for i, n := 0, r.len(); i < n; i++ {
+			// Eagerly register position bases, so their filenames are
+			// assigned stable indices.
+			posBase := r.posBase()
+			_ = base.Ctxt.PosTable.XPos(src.MakePos(posBase, 0, 0))
+		}
+
+		for i, n := 0, r.len(); i < n; i++ {
+			// Eagerly resolve imported objects, so any filenames registered
+			// in the process are assigned stable indices too.
+			_, sym := r.qualifiedIdent()
+			typecheck.Resolve(ir.NewIdent(src.NoXPos, sym))
+			assert(sym.Def != nil)
+		}
+	}
+
+	cgoPragmas := make([][]string, r.len())
+	for i := range cgoPragmas {
+		cgoPragmas[i] = r.strings()
+	}
+	target.CgoPragmas = cgoPragmas
+
+	r.pkgDecls(target)
+
+	r.sync(syncEOF)
+}
+
+func (r *reader) pkgDecls(target *ir.Package) {
+	r.sync(syncDecls)
+	for {
+		switch code := codeDecl(r.code(syncDecl)); code {
+		default:
+			panic(fmt.Sprintf("unhandled decl: %v", code))
+
+		case declEnd:
+			return
+
+		case declFunc:
+			names := r.pkgObjs(target)
+			assert(len(names) == 1)
+			target.Decls = append(target.Decls, names[0].Func)
+
+		case declMethod:
+			typ := r.typ()
+			_, sym := r.selector()
+
+			method := typecheck.Lookdot1(nil, sym, typ, typ.Methods(), 0)
+			target.Decls = append(target.Decls, method.Nname.(*ir.Name).Func)
+
+		case declVar:
+			pos := r.pos()
+			names := r.pkgObjs(target)
+			values := r.exprList()
+
+			if len(names) > 1 && len(values) == 1 {
+				as := ir.NewAssignListStmt(pos, ir.OAS2, nil, values)
+				for _, name := range names {
+					as.Lhs.Append(name)
+					name.Defn = as
+				}
+				target.Decls = append(target.Decls, as)
+			} else {
+				for i, name := range names {
+					as := ir.NewAssignStmt(pos, name, nil)
+					if i < len(values) {
+						as.Y = values[i]
+					}
+					name.Defn = as
+					target.Decls = append(target.Decls, as)
+				}
+			}
+
+			if n := r.len(); n > 0 {
+				assert(len(names) == 1)
+				embeds := make([]ir.Embed, n)
+				for i := range embeds {
+					embeds[i] = ir.Embed{Pos: r.pos(), Patterns: r.strings()}
+				}
+				names[0].Embed = &embeds
+				target.Embeds = append(target.Embeds, names[0])
+			}
+
+		case declOther:
+			r.pkgObjs(target)
+		}
+	}
+}
+
+func (r *reader) pkgObjs(target *ir.Package) []*ir.Name {
+	r.sync(syncDeclNames)
+	nodes := make([]*ir.Name, r.len())
+	for i := range nodes {
+		r.sync(syncDeclName)
+
+		name := r.obj().(*ir.Name)
+		nodes[i] = name
+
+		sym := name.Sym()
+		if sym.IsBlank() {
+			continue
+		}
+
+		switch name.Class {
+		default:
+			base.FatalfAt(name.Pos(), "unexpected class: %v", name.Class)
+
+		case ir.PEXTERN:
+			target.Externs = append(target.Externs, name)
+
+		case ir.PFUNC:
+			assert(name.Type().Recv() == nil)
+
+			// TODO(mdempsky): Cleaner way to recognize init?
+			if strings.HasPrefix(sym.Name, "init.") {
+				target.Inits = append(target.Inits, name.Func)
+			}
+		}
+
+		if types.IsExported(sym.Name) {
+			assert(!sym.OnExportList())
+			target.Exports = append(target.Exports, name)
+			sym.SetOnExportList(true)
+		}
+
+		if base.Flag.AsmHdr != "" {
+			assert(!sym.Asm())
+			target.Asms = append(target.Asms, name)
+			sym.SetAsm(true)
+		}
+	}
+
+	return nodes
+}
+
+// @@@ Inlining
+
+var inlgen = 0
+
+func InlineCall(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	// TODO(mdempsky): Turn callerfn into an explicit parameter.
+	callerfn := ir.CurFunc
+
+	pri, ok := bodyReader[fn]
+	if !ok {
+		// Assume it's an imported function or something that we don't
+		// have access to in quirks mode.
+		if haveLegacyImports {
+			return nil
+		}
+
+		base.FatalfAt(call.Pos(), "missing function body for call to %v", fn)
+	}
+
+	if fn.Inl.Body == nil {
+		expandInline(fn, pri)
+	}
+
+	r := pri.asReader(relocBody, syncFuncBody)
+
+	// TODO(mdempsky): This still feels clumsy. Can we do better?
+	tmpfn := ir.NewFunc(fn.Pos())
+	tmpfn.Nname = ir.NewNameAt(fn.Nname.Pos(), callerfn.Sym())
+	tmpfn.Closgen = callerfn.Closgen
+	defer func() { callerfn.Closgen = tmpfn.Closgen }()
+
+	r.setType(tmpfn.Nname, fn.Type())
+	r.curfn = tmpfn
+
+	r.inlCaller = callerfn
+	r.inlCall = call
+	r.inlFunc = fn
+	r.inlTreeIndex = inlIndex
+	r.inlPosBases = make(map[*src.PosBase]*src.PosBase)
+
+	r.closureVars = make([]*ir.Name, len(r.inlFunc.ClosureVars))
+	for i, cv := range r.inlFunc.ClosureVars {
+		r.closureVars[i] = cv.Outer
+	}
+
+	r.funcargs(fn)
+
+	assert(r.bool()) // have body
+	r.delayResults = fn.Inl.CanDelayResults
+
+	r.retlabel = typecheck.AutoLabel(".i")
+	inlgen++
+
+	init := ir.TakeInit(call)
+
+	// For normal function calls, the function callee expression
+	// may contain side effects. Make sure to preserve these,
+	// if necessary (#42703).
+	if call.Op() == ir.OCALLFUNC {
+		inline.CalleeEffects(&init, call.X)
+	}
+
+	var args ir.Nodes
+	if call.Op() == ir.OCALLMETH {
+		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+	}
+	args.Append(call.Args...)
+
+	// Create assignment to declare and initialize inlvars.
+	as2 := ir.NewAssignListStmt(call.Pos(), ir.OAS2, r.inlvars, args)
+	as2.Def = true
+	var as2init ir.Nodes
+	for _, name := range r.inlvars {
+		if ir.IsBlank(name) {
+			continue
+		}
+		// TODO(mdempsky): Use inlined position of name.Pos() instead?
+		name := name.(*ir.Name)
+		as2init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
+		name.Defn = as2
+	}
+	as2.SetInit(as2init)
+	init.Append(typecheck.Stmt(as2))
+
+	if !r.delayResults {
+		// If not delaying retvars, declare and zero initialize the
+		// result variables now.
+		for _, name := range r.retvars {
+			// TODO(mdempsky): Use inlined position of name.Pos() instead?
+			name := name.(*ir.Name)
+			init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
+			ras := ir.NewAssignStmt(call.Pos(), name, nil)
+			init.Append(typecheck.Stmt(ras))
+		}
+	}
+
+	// Add an inline mark just before the inlined body.
+	// This mark is inline in the code so that it's a reasonable spot
+	// to put a breakpoint. Not sure if that's really necessary or not
+	// (in which case it could go at the end of the function instead).
+	// Note issue 28603.
+	init.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(r.inlTreeIndex)))
+
+	nparams := len(r.curfn.Dcl)
+
+	ir.WithFunc(r.curfn, func() {
+		r.curfn.Body = r.stmts()
+		r.curfn.Endlineno = r.pos()
+
+		deadcode.Func(r.curfn)
+
+		// Replace any "return" statements within the function body.
+		var edit func(ir.Node) ir.Node
+		edit = func(n ir.Node) ir.Node {
+			if ret, ok := n.(*ir.ReturnStmt); ok {
+				n = typecheck.Stmt(r.inlReturn(ret))
+			}
+			ir.EditChildren(n, edit)
+			return n
+		}
+		edit(r.curfn)
+	})
+
+	body := ir.Nodes(r.curfn.Body)
+
+	// Quirk: If deadcode elimination turned a non-empty function into
+	// an empty one, we need to set the position for the empty block
+	// left behind to the the inlined position for src.NoXPos, so that
+	// an empty string gets added into the DWARF file name listing at
+	// the appropriate index.
+	if quirksMode() && len(body) == 1 {
+		if block, ok := body[0].(*ir.BlockStmt); ok && len(block.List) == 0 {
+			block.SetPos(r.updatePos(src.NoXPos))
+		}
+	}
+
+	// Quirkish: We need to eagerly prune variables added during
+	// inlining, but removed by deadcode.FuncBody above. Unused
+	// variables will get removed during stack frame layout anyway, but
+	// len(fn.Dcl) ends up influencing things like autotmp naming.
+
+	used := usedLocals(body)
+
+	for i, name := range r.curfn.Dcl {
+		if i < nparams || used.Has(name) {
+			name.Curfn = callerfn
+			callerfn.Dcl = append(callerfn.Dcl, name)
+
+			// Quirkish. TODO(mdempsky): Document why.
+			if name.AutoTemp() {
+				name.SetEsc(ir.EscUnknown)
+
+				if base.Flag.GenDwarfInl != 0 {
+					name.SetInlLocal(true)
+				} else {
+					name.SetPos(r.inlCall.Pos())
+				}
+			}
+		}
+	}
+
+	body.Append(ir.NewLabelStmt(call.Pos(), r.retlabel))
+
+	res := ir.NewInlinedCallExpr(call.Pos(), body, append([]ir.Node(nil), r.retvars...))
+	res.SetInit(init)
+	res.SetType(call.Type())
+	res.SetTypecheck(1)
+
+	// Inlining shouldn't add any functions to todoBodies.
+	assert(len(todoBodies) == 0)
+
+	return res
+}
+
+// inlReturn returns a statement that can substitute for the given
+// return statement when inlining.
+func (r *reader) inlReturn(ret *ir.ReturnStmt) *ir.BlockStmt {
+	pos := r.inlCall.Pos()
+
+	block := ir.TakeInit(ret)
+
+	if results := ret.Results; len(results) != 0 {
+		assert(len(r.retvars) == len(results))
+
+		as2 := ir.NewAssignListStmt(pos, ir.OAS2, append([]ir.Node(nil), r.retvars...), ret.Results)
+
+		if r.delayResults {
+			for _, name := range r.retvars {
+				// TODO(mdempsky): Use inlined position of name.Pos() instead?
+				name := name.(*ir.Name)
+				block.Append(ir.NewDecl(pos, ir.ODCL, name))
+				name.Defn = as2
+			}
+		}
+
+		block.Append(as2)
+	}
+
+	block.Append(ir.NewBranchStmt(pos, ir.OGOTO, r.retlabel))
+	return ir.NewBlockStmt(pos, block)
+}
+
+// expandInline reads in an extra copy of IR to populate
+// fn.Inl.{Dcl,Body}.
+func expandInline(fn *ir.Func, pri pkgReaderIndex) {
+	// TODO(mdempsky): Remove this function. It's currently needed by
+	// dwarfgen/dwarf.go:preInliningDcls, which requires fn.Inl.Dcl to
+	// create abstract function DIEs. But we should be able to provide it
+	// with the same information some other way.
+
+	fndcls := len(fn.Dcl)
+	topdcls := len(typecheck.Target.Decls)
+
+	tmpfn := ir.NewFunc(fn.Pos())
+	tmpfn.Nname = ir.NewNameAt(fn.Nname.Pos(), fn.Sym())
+	tmpfn.ClosureVars = fn.ClosureVars
+
+	{
+		r := pri.asReader(relocBody, syncFuncBody)
+		r.setType(tmpfn.Nname, fn.Type())
+
+		// Don't change parameter's Sym/Nname fields.
+		r.funarghack = true
+
+		r.funcBody(tmpfn)
+
+		ir.WithFunc(tmpfn, func() {
+			deadcode.Func(tmpfn)
+		})
+	}
+
+	used := usedLocals(tmpfn.Body)
+
+	for _, name := range tmpfn.Dcl {
+		if name.Class != ir.PAUTO || used.Has(name) {
+			name.Curfn = fn
+			fn.Inl.Dcl = append(fn.Inl.Dcl, name)
+		}
+	}
+	fn.Inl.Body = tmpfn.Body
+
+	// Double check that we didn't change fn.Dcl by accident.
+	assert(fndcls == len(fn.Dcl))
+
+	// typecheck.Stmts may have added function literals to
+	// typecheck.Target.Decls. Remove them again so we don't risk trying
+	// to compile them multiple times.
+	typecheck.Target.Decls = typecheck.Target.Decls[:topdcls]
+}
+
+// usedLocals returns a set of local variables that are used within body.
+func usedLocals(body []ir.Node) ir.NameSet {
+	var used ir.NameSet
+	ir.VisitList(body, func(n ir.Node) {
+		if n, ok := n.(*ir.Name); ok && n.Op() == ir.ONAME && n.Class == ir.PAUTO {
+			used.Add(n)
+		}
+	})
+	return used
+}
+
+// @@@ Method wrappers
+
+// needWrapperTypes lists types for which we may need to generate
+// method wrappers.
+var needWrapperTypes []*types.Type
+
+// haveWrapperTypes lists types for which we know we already have
+// method wrappers, because we found the type in an imported package.
+var haveWrapperTypes []*types.Type
+
+func (r *reader) needWrapper(typ *types.Type) *types.Type {
+	if typ.IsPtr() {
+		base.Fatalf("bad pointer type: %v", typ)
+	}
+
+	// If a type was found in an imported package, then we can assume
+	// that package (or one of its transitive dependencies) already
+	// generated method wrappers for it.
+	//
+	// Exception: If we're instantiating an imported generic type or
+	// function, we might be instantiating it with type arguments not
+	// previously seen before.
+	//
+	// TODO(mdempsky): Distinguish when a generic function or type was
+	// instantiated in an imported package so that we can add types to
+	// haveWrapperTypes instead.
+	if r.p != localPkgReader && !r.hasTypeParams() {
+		haveWrapperTypes = append(haveWrapperTypes, typ)
+	} else {
+		needWrapperTypes = append(needWrapperTypes, typ)
+	}
+
+	return typ
+}
+
+func (r *reader) wrapTypes(target *ir.Package) {
+	// always generate a wrapper for error.Error (#29304)
+	r.needWrapper(types.ErrorType)
+
+	seen := make(map[string]*types.Type)
+	addType := func(typ *types.Type) bool {
+		if typ.Sym() != nil {
+			return true
+		}
+
+		key := typ.LinkString()
+		if prev := seen[key]; prev != nil {
+			if !types.Identical(typ, prev) {
+				base.Fatalf("collision: types %v and %v have short string %q", typ, prev, key)
+			}
+			return false
+		}
+
+		seen[key] = typ
+		return true
+	}
+
+	for _, typ := range haveWrapperTypes {
+		addType(typ)
+	}
+	haveWrapperTypes = nil
+
+	for _, typ := range needWrapperTypes {
+		if addType(typ) {
+			r.wrapType(typ, target)
+		}
+	}
+	needWrapperTypes = nil
+}
+
+func (r *reader) wrapType(typ *types.Type, target *ir.Package) {
+	if !typ.IsInterface() {
+		typecheck.CalcMethods(typ)
+	}
+	for _, meth := range typ.AllMethods().Slice() {
+		if meth.Sym.IsBlank() || !meth.IsMethod() {
+			base.FatalfAt(meth.Pos, "invalid method: %v", meth)
+		}
+
+		r.methodValueWrapper(typ, meth, target)
+
+		r.methodWrapper(0, typ, meth, target)
+
+		// For non-interface types, we also want *T wrappers.
+		if !typ.IsInterface() {
+			r.methodWrapper(1, typ, meth, target)
+
+			// For not-in-heap types, *T is a scalar, not pointer shaped,
+			// so the interface wrappers use **T.
+			if typ.NotInHeap() {
+				r.methodWrapper(2, typ, meth, target)
+			}
+		}
+	}
+}
+
+func (r *reader) methodWrapper(derefs int, tbase *types.Type, method *types.Field, target *ir.Package) {
+	wrapper := tbase
+	for i := 0; i < derefs; i++ {
+		wrapper = types.NewPtr(wrapper)
+	}
+
+	sym := ir.MethodSym(wrapper, method.Sym)
+	assert(!sym.Siggen())
+	sym.SetSiggen(true)
+
+	wrappee := method.Type.Recv().Type
+	if types.Identical(wrapper, wrappee) ||
+		!types.IsMethodApplicable(wrapper, method) ||
+		!reflectdata.NeedEmit(tbase) {
+		return
+	}
+
+	// TODO(mdempsky): Use method.Pos instead?
+	pos := base.AutogeneratedPos
+
+	fn := r.newWrapperFunc(pos, sym, wrapper, method)
+
+	var recv ir.Node = fn.Nname.Type().Recv().Nname.(*ir.Name)
+
+	// For simple *T wrappers around T methods, panicwrap produces a
+	// nicer panic message.
+	if wrapper.IsPtr() && types.Identical(wrapper.Elem(), wrappee) {
+		cond := ir.NewBinaryExpr(pos, ir.OEQ, recv, types.BuiltinPkg.Lookup("nil").Def.(ir.Node))
+		then := []ir.Node{ir.NewCallExpr(pos, ir.OCALL, typecheck.LookupRuntime("panicwrap"), nil)}
+		fn.Body.Append(ir.NewIfStmt(pos, cond, then, nil))
+	}
+
+	// typecheck will add one implicit deref, if necessary,
+	// but not-in-heap types require more for their **T wrappers.
+	for i := 1; i < derefs; i++ {
+		recv = Implicit(ir.NewStarExpr(pos, recv))
+	}
+
+	addTailCall(pos, fn, recv, method)
+
+	r.finishWrapperFunc(fn, target)
+}
+
+func (r *reader) methodValueWrapper(tbase *types.Type, method *types.Field, target *ir.Package) {
+	recvType := tbase
+	if !tbase.IsInterface() {
+		recvType = method.Type.Recv().Type
+		if !types.Identical(tbase, types.ReceiverBaseType(recvType)) {
+			return
+		}
+	}
+
+	sym := ir.MethodSymSuffix(recvType, method.Sym, "-fm")
+	assert(!sym.Uniq())
+	sym.SetUniq(true)
+
+	// TODO(mdempsky): Use method.Pos instead?
+	pos := base.AutogeneratedPos
+
+	fn := r.newWrapperFunc(pos, sym, nil, method)
+	sym.Def = fn.Nname
+
+	// Declare and initialize variable holding receiver.
+	recv := ir.NewHiddenParam(pos, fn, typecheck.Lookup(".this"), recvType)
+
+	if !reflectdata.NeedEmit(tbase) {
+		typecheck.Func(fn)
+		return
+	}
+
+	addTailCall(pos, fn, recv, method)
+
+	r.finishWrapperFunc(fn, target)
+}
+
+func (r *reader) newWrapperFunc(pos src.XPos, sym *types.Sym, wrapper *types.Type, method *types.Field) *ir.Func {
+	fn := ir.NewFunc(pos)
+	fn.SetDupok(true) // TODO(mdempsky): Leave unset for local, non-generic wrappers?
+
+	name := ir.NewNameAt(pos, sym)
+	ir.MarkFunc(name)
+	name.Func = fn
+	name.Defn = fn
+	fn.Nname = name
+
+	sig := newWrapperType(wrapper, method)
+	r.setType(name, sig)
+
+	// TODO(mdempsky): De-duplicate with similar logic in funcargs.
+	defParams := func(class ir.Class, params *types.Type) {
+		for _, param := range params.FieldSlice() {
+			name := ir.NewNameAt(param.Pos, param.Sym)
+			name.Class = class
+			r.setType(name, param.Type)
+
+			name.Curfn = fn
+			fn.Dcl = append(fn.Dcl, name)
+
+			param.Nname = name
+		}
+	}
+
+	defParams(ir.PPARAM, sig.Recvs())
+	defParams(ir.PPARAM, sig.Params())
+	defParams(ir.PPARAMOUT, sig.Results())
+
+	return fn
+}
+
+func (r *reader) finishWrapperFunc(fn *ir.Func, target *ir.Package) {
+	typecheck.Func(fn)
+
+	ir.WithFunc(fn, func() {
+		typecheck.Stmts(fn.Body)
+	})
+
+	target.Decls = append(target.Decls, fn)
+}
+
+// newWrapperType returns a copy of the given signature type, but with
+// the receiver parameter type substituted with recvType.
+// If recvType is nil, newWrapperType returns a signature
+// without a receiver parameter.
+func newWrapperType(recvType *types.Type, method *types.Field) *types.Type {
+	clone := func(params []*types.Field) []*types.Field {
+		res := make([]*types.Field, len(params))
+		for i, param := range params {
+			sym := param.Sym
+			if sym == nil || sym.Name == "_" {
+				sym = typecheck.LookupNum(".anon", i)
+			}
+			res[i] = types.NewField(param.Pos, sym, param.Type)
+			res[i].SetIsDDD(param.IsDDD())
+		}
+		return res
+	}
+
+	sig := method.Type
+
+	var recv *types.Field
+	if recvType != nil {
+		recv = types.NewField(sig.Recv().Pos, typecheck.Lookup(".this"), recvType)
+	}
+	params := clone(sig.Params().FieldSlice())
+	results := clone(sig.Results().FieldSlice())
+
+	return types.NewSignature(types.NoPkg, recv, nil, params, results)
+}
+
+func addTailCall(pos src.XPos, fn *ir.Func, recv ir.Node, method *types.Field) {
+	sig := fn.Nname.Type()
+	args := make([]ir.Node, sig.NumParams())
+	for i, param := range sig.Params().FieldSlice() {
+		args[i] = param.Nname.(*ir.Name)
+	}
+
+	// TODO(mdempsky): Support creating OTAILCALL, when possible. See reflectdata.methodWrapper.
+	// Not urgent though, because tail calls are currently incompatible with regabi anyway.
+
+	fn.SetWrapper(true) // TODO(mdempsky): Leave unset for tail calls?
+
+	dot := ir.NewSelectorExpr(pos, ir.OXDOT, recv, method.Sym)
+	call := typecheck.Call(pos, dot, args, method.Type.IsVariadic()).(*ir.CallExpr)
+
+	if method.Type.NumResults() == 0 {
+		fn.Body.Append(call)
+		return
+	}
+
+	ret := ir.NewReturnStmt(pos, nil)
+	ret.Results = []ir.Node{call}
+	fn.Body.Append(ret)
+}
diff --git a/src/cmd/compile/internal/noder/reader2.go b/src/cmd/compile/internal/noder/reader2.go
new file mode 100644
index 0000000000000000000000000000000000000000..8f3f0a50e9ced72c272921604236c10fa0cd3303
--- /dev/null
+++ b/src/cmd/compile/internal/noder/reader2.go
@@ -0,0 +1,509 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"go/constant"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+type pkgReader2 struct {
+	pkgDecoder
+
+	check   *types2.Checker
+	imports map[string]*types2.Package
+
+	posBases []*syntax.PosBase
+	pkgs     []*types2.Package
+	typs     []types2.Type
+}
+
+func readPackage2(check *types2.Checker, imports map[string]*types2.Package, input pkgDecoder) *types2.Package {
+	pr := pkgReader2{
+		pkgDecoder: input,
+
+		check:   check,
+		imports: imports,
+
+		posBases: make([]*syntax.PosBase, input.numElems(relocPosBase)),
+		pkgs:     make([]*types2.Package, input.numElems(relocPkg)),
+		typs:     make([]types2.Type, input.numElems(relocType)),
+	}
+
+	r := pr.newReader(relocMeta, publicRootIdx, syncPublic)
+	pkg := r.pkg()
+	r.bool() // has init
+
+	for i, n := 0, r.len(); i < n; i++ {
+		r.obj()
+	}
+
+	r.sync(syncEOF)
+
+	pkg.MarkComplete()
+	return pkg
+}
+
+type reader2 struct {
+	decoder
+
+	p *pkgReader2
+
+	dict *reader2Dict
+}
+
+type reader2Dict struct {
+	bounds []typeInfo
+
+	tparams []*types2.TypeParam
+
+	derived      []derivedInfo
+	derivedTypes []types2.Type
+}
+
+type reader2TypeBound struct {
+	derived  bool
+	boundIdx int
+}
+
+func (pr *pkgReader2) newReader(k reloc, idx int, marker syncMarker) *reader2 {
+	return &reader2{
+		decoder: pr.newDecoder(k, idx, marker),
+		p:       pr,
+	}
+}
+
+// @@@ Positions
+
+func (r *reader2) pos() syntax.Pos {
+	r.sync(syncPos)
+	if !r.bool() {
+		return syntax.Pos{}
+	}
+
+	// TODO(mdempsky): Delta encoding.
+	posBase := r.posBase()
+	line := r.uint()
+	col := r.uint()
+	return syntax.MakePos(posBase, line, col)
+}
+
+func (r *reader2) posBase() *syntax.PosBase {
+	return r.p.posBaseIdx(r.reloc(relocPosBase))
+}
+
+func (pr *pkgReader2) posBaseIdx(idx int) *syntax.PosBase {
+	if b := pr.posBases[idx]; b != nil {
+		return b
+	}
+
+	r := pr.newReader(relocPosBase, idx, syncPosBase)
+	var b *syntax.PosBase
+
+	filename := r.string()
+
+	if r.bool() {
+		b = syntax.NewTrimmedFileBase(filename, true)
+	} else {
+		pos := r.pos()
+		line := r.uint()
+		col := r.uint()
+		b = syntax.NewLineBase(pos, filename, true, line, col)
+	}
+
+	pr.posBases[idx] = b
+	return b
+}
+
+// @@@ Packages
+
+func (r *reader2) pkg() *types2.Package {
+	r.sync(syncPkg)
+	return r.p.pkgIdx(r.reloc(relocPkg))
+}
+
+func (pr *pkgReader2) pkgIdx(idx int) *types2.Package {
+	// TODO(mdempsky): Consider using some non-nil pointer to indicate
+	// the universe scope, so we don't need to keep re-reading it.
+	if pkg := pr.pkgs[idx]; pkg != nil {
+		return pkg
+	}
+
+	pkg := pr.newReader(relocPkg, idx, syncPkgDef).doPkg()
+	pr.pkgs[idx] = pkg
+	return pkg
+}
+
+func (r *reader2) doPkg() *types2.Package {
+	path := r.string()
+	if path == "builtin" {
+		return nil // universe
+	}
+	if path == "" {
+		path = r.p.pkgPath
+	}
+
+	if pkg := r.p.imports[path]; pkg != nil {
+		return pkg
+	}
+
+	name := r.string()
+	height := r.len()
+
+	pkg := types2.NewPackageHeight(path, name, height)
+	r.p.imports[path] = pkg
+
+	// TODO(mdempsky): The list of imported packages is important for
+	// go/types, but we could probably skip populating it for types2.
+	imports := make([]*types2.Package, r.len())
+	for i := range imports {
+		imports[i] = r.pkg()
+	}
+	pkg.SetImports(imports)
+
+	return pkg
+}
+
+// @@@ Types
+
+func (r *reader2) typ() types2.Type {
+	return r.p.typIdx(r.typInfo(), r.dict)
+}
+
+func (r *reader2) typInfo() typeInfo {
+	r.sync(syncType)
+	if r.bool() {
+		return typeInfo{idx: r.len(), derived: true}
+	}
+	return typeInfo{idx: r.reloc(relocType), derived: false}
+}
+
+func (pr *pkgReader2) typIdx(info typeInfo, dict *reader2Dict) types2.Type {
+	idx := info.idx
+	var where *types2.Type
+	if info.derived {
+		where = &dict.derivedTypes[idx]
+		idx = dict.derived[idx].idx
+	} else {
+		where = &pr.typs[idx]
+	}
+
+	if typ := *where; typ != nil {
+		return typ
+	}
+
+	r := pr.newReader(relocType, idx, syncTypeIdx)
+	r.dict = dict
+
+	typ := r.doTyp()
+	assert(typ != nil)
+
+	// See comment in pkgReader.typIdx explaining how this happens.
+	if prev := *where; prev != nil {
+		return prev
+	}
+
+	*where = typ
+	return typ
+}
+
+func (r *reader2) doTyp() (res types2.Type) {
+	switch tag := codeType(r.code(syncType)); tag {
+	default:
+		base.FatalfAt(src.NoXPos, "unhandled type tag: %v", tag)
+		panic("unreachable")
+
+	case typeBasic:
+		return types2.Typ[r.len()]
+
+	case typeNamed:
+		obj, targs := r.obj()
+		name := obj.(*types2.TypeName)
+		if len(targs) != 0 {
+			t, _ := types2.Instantiate(types2.NewEnvironment(r.p.check), name.Type(), targs, false)
+			return t
+		}
+		return name.Type()
+
+	case typeTypeParam:
+		return r.dict.tparams[r.len()]
+
+	case typeArray:
+		len := int64(r.uint64())
+		return types2.NewArray(r.typ(), len)
+	case typeChan:
+		dir := types2.ChanDir(r.len())
+		return types2.NewChan(dir, r.typ())
+	case typeMap:
+		return types2.NewMap(r.typ(), r.typ())
+	case typePointer:
+		return types2.NewPointer(r.typ())
+	case typeSignature:
+		return r.signature(nil)
+	case typeSlice:
+		return types2.NewSlice(r.typ())
+	case typeStruct:
+		return r.structType()
+	case typeInterface:
+		return r.interfaceType()
+	case typeUnion:
+		return r.unionType()
+	}
+}
+
+func (r *reader2) structType() *types2.Struct {
+	fields := make([]*types2.Var, r.len())
+	var tags []string
+	for i := range fields {
+		pos := r.pos()
+		pkg, name := r.selector()
+		ftyp := r.typ()
+		tag := r.string()
+		embedded := r.bool()
+
+		fields[i] = types2.NewField(pos, pkg, name, ftyp, embedded)
+		if tag != "" {
+			for len(tags) < i {
+				tags = append(tags, "")
+			}
+			tags = append(tags, tag)
+		}
+	}
+	return types2.NewStruct(fields, tags)
+}
+
+func (r *reader2) unionType() *types2.Union {
+	terms := make([]*types2.Term, r.len())
+	for i := range terms {
+		terms[i] = types2.NewTerm(r.bool(), r.typ())
+	}
+	return types2.NewUnion(terms)
+}
+
+func (r *reader2) interfaceType() *types2.Interface {
+	methods := make([]*types2.Func, r.len())
+	embeddeds := make([]types2.Type, r.len())
+
+	for i := range methods {
+		pos := r.pos()
+		pkg, name := r.selector()
+		mtyp := r.signature(nil)
+		methods[i] = types2.NewFunc(pos, pkg, name, mtyp)
+	}
+
+	for i := range embeddeds {
+		embeddeds[i] = r.typ()
+	}
+
+	return types2.NewInterfaceType(methods, embeddeds)
+}
+
+func (r *reader2) signature(recv *types2.Var) *types2.Signature {
+	r.sync(syncSignature)
+
+	params := r.params()
+	results := r.params()
+	variadic := r.bool()
+
+	return types2.NewSignature(recv, params, results, variadic)
+}
+
+func (r *reader2) params() *types2.Tuple {
+	r.sync(syncParams)
+	params := make([]*types2.Var, r.len())
+	for i := range params {
+		params[i] = r.param()
+	}
+	return types2.NewTuple(params...)
+}
+
+func (r *reader2) param() *types2.Var {
+	r.sync(syncParam)
+
+	pos := r.pos()
+	pkg, name := r.localIdent()
+	typ := r.typ()
+
+	return types2.NewParam(pos, pkg, name, typ)
+}
+
+// @@@ Objects
+
+func (r *reader2) obj() (types2.Object, []types2.Type) {
+	r.sync(syncObject)
+
+	assert(!r.bool())
+
+	pkg, name := r.p.objIdx(r.reloc(relocObj))
+	obj := pkg.Scope().Lookup(name)
+
+	targs := make([]types2.Type, r.len())
+	for i := range targs {
+		targs[i] = r.typ()
+	}
+
+	return obj, targs
+}
+
+func (pr *pkgReader2) objIdx(idx int) (*types2.Package, string) {
+	rname := pr.newReader(relocName, idx, syncObject1)
+
+	objPkg, objName := rname.qualifiedIdent()
+	assert(objName != "")
+
+	tag := codeObj(rname.code(syncCodeObj))
+
+	if tag == objStub {
+		assert(objPkg == nil)
+		return objPkg, objName
+	}
+
+	dict := pr.objDictIdx(idx)
+
+	r := pr.newReader(relocObj, idx, syncObject1)
+	r.dict = dict
+
+	objPkg.Scope().InsertLazy(objName, func() types2.Object {
+		switch tag {
+		default:
+			panic("weird")
+
+		case objAlias:
+			pos := r.pos()
+			typ := r.typ()
+			return types2.NewTypeName(pos, objPkg, objName, typ)
+
+		case objConst:
+			pos := r.pos()
+			typ, val := r.value()
+			return types2.NewConst(pos, objPkg, objName, typ, val)
+
+		case objFunc:
+			pos := r.pos()
+			tparams := r.typeParamNames()
+			sig := r.signature(nil)
+			sig.SetTParams(tparams)
+			return types2.NewFunc(pos, objPkg, objName, sig)
+
+		case objType:
+			pos := r.pos()
+
+			return types2.NewTypeNameLazy(pos, objPkg, objName, func(named *types2.Named) (tparams []*types2.TypeParam, underlying types2.Type, methods []*types2.Func) {
+				tparams = r.typeParamNames()
+
+				// TODO(mdempsky): Rewrite receiver types to underlying is an
+				// Interface? The go/types importer does this (I think because
+				// unit tests expected that), but cmd/compile doesn't care
+				// about it, so maybe we can avoid worrying about that here.
+				underlying = r.typ().Underlying()
+
+				methods = make([]*types2.Func, r.len())
+				for i := range methods {
+					methods[i] = r.method()
+				}
+
+				return
+			})
+
+		case objVar:
+			pos := r.pos()
+			typ := r.typ()
+			return types2.NewVar(pos, objPkg, objName, typ)
+		}
+	})
+
+	return objPkg, objName
+}
+
+func (r *reader2) value() (types2.Type, constant.Value) {
+	r.sync(syncValue)
+	return r.typ(), r.rawValue()
+}
+
+func (pr *pkgReader2) objDictIdx(idx int) *reader2Dict {
+	r := pr.newReader(relocObjDict, idx, syncObject1)
+
+	var dict reader2Dict
+
+	if implicits := r.len(); implicits != 0 {
+		base.Fatalf("unexpected object with %v implicit type parameter(s)", implicits)
+	}
+
+	dict.bounds = make([]typeInfo, r.len())
+	for i := range dict.bounds {
+		dict.bounds[i] = r.typInfo()
+	}
+
+	dict.derived = make([]derivedInfo, r.len())
+	dict.derivedTypes = make([]types2.Type, len(dict.derived))
+	for i := range dict.derived {
+		dict.derived[i] = derivedInfo{r.reloc(relocType), r.bool()}
+	}
+
+	// function references follow, but reader2 doesn't need those
+
+	return &dict
+}
+
+func (r *reader2) typeParamNames() []*types2.TypeParam {
+	r.sync(syncTypeParamNames)
+
+	// Note: This code assumes it only processes objects without
+	// implement type parameters. This is currently fine, because
+	// reader2 is only used to read in exported declarations, which are
+	// always package scoped.
+
+	if len(r.dict.bounds) == 0 {
+		return nil
+	}
+
+	// Careful: Type parameter lists may have cycles. To allow for this,
+	// we construct the type parameter list in two passes: first we
+	// create all the TypeNames and TypeParams, then we construct and
+	// set the bound type.
+
+	r.dict.tparams = make([]*types2.TypeParam, len(r.dict.bounds))
+	for i := range r.dict.bounds {
+		pos := r.pos()
+		pkg, name := r.localIdent()
+
+		tname := types2.NewTypeName(pos, pkg, name, nil)
+		r.dict.tparams[i] = r.p.check.NewTypeParam(tname, nil)
+	}
+
+	for i, bound := range r.dict.bounds {
+		r.dict.tparams[i].SetConstraint(r.p.typIdx(bound, r.dict))
+	}
+
+	return r.dict.tparams
+}
+
+func (r *reader2) method() *types2.Func {
+	r.sync(syncMethod)
+	pos := r.pos()
+	pkg, name := r.selector()
+
+	rparams := r.typeParamNames()
+	sig := r.signature(r.param())
+	sig.SetRParams(rparams)
+
+	_ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
+	return types2.NewFunc(pos, pkg, name, sig)
+}
+
+func (r *reader2) qualifiedIdent() (*types2.Package, string) { return r.ident(syncSym) }
+func (r *reader2) localIdent() (*types2.Package, string)     { return r.ident(syncLocalIdent) }
+func (r *reader2) selector() (*types2.Package, string)       { return r.ident(syncSelector) }
+
+func (r *reader2) ident(marker syncMarker) (*types2.Package, string) {
+	r.sync(marker)
+	return r.pkg(), r.string()
+}
diff --git a/src/cmd/compile/internal/noder/reloc.go b/src/cmd/compile/internal/noder/reloc.go
new file mode 100644
index 0000000000000000000000000000000000000000..669a6182e62eb250dd2f0ac817e4b5712d06ece7
--- /dev/null
+++ b/src/cmd/compile/internal/noder/reloc.go
@@ -0,0 +1,42 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+// A reloc indicates a particular section within a unified IR export.
+//
+// TODO(mdempsky): Rename to "section" or something similar?
+type reloc int
+
+// A relocEnt (relocation entry) is an entry in an atom's local
+// reference table.
+//
+// TODO(mdempsky): Rename this too.
+type relocEnt struct {
+	kind reloc
+	idx  int
+}
+
+// Reserved indices within the meta relocation section.
+const (
+	publicRootIdx  = 0
+	privateRootIdx = 1
+)
+
+const (
+	relocString reloc = iota
+	relocMeta
+	relocPosBase
+	relocPkg
+	relocName
+	relocType
+	relocObj
+	relocObjExt
+	relocObjDict
+	relocBody
+
+	numRelocs = iota
+)
diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 3ebc8dff6d84322d2d5c2379e9497a87ebb1d73b..602e88c102c249f34993b6c3d52e22fcab898c58 100644
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -8,21 +8,32 @@
 package noder
 
 import (
-	"bytes"
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
+	"cmd/compile/internal/objw"
+	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
+	"cmd/internal/obj"
 	"cmd/internal/src"
 	"fmt"
-	"strings"
+	"go/constant"
 )
 
-// For catching problems as we add more features
-// TODO(danscales): remove assertions or replace with base.FatalfAt()
+// Enable extra consistency checks.
+const doubleCheck = true
+
 func assert(p bool) {
-	if !p {
-		panic("assertion failed")
+	base.Assert(p)
+}
+
+// Temporary - for outputting information on derived types, dictionaries, sub-dictionaries.
+// Turn off when running tests.
+var infoPrintMode = false
+
+func infoPrint(format string, a ...interface{}) {
+	if infoPrintMode {
+		fmt.Printf(format, a...)
 	}
 }
 
@@ -32,7 +43,8 @@ func assert(p bool) {
 // encountered already or new ones that are encountered during the stenciling
 // process.
 func (g *irgen) stencil() {
-	g.target.Stencils = make(map[*types.Sym]*ir.Func)
+	g.instInfoMap = make(map[*types.Sym]*instInfo)
+	g.gfInfoMap = make(map[*types.Sym]*gfInfo)
 
 	// Instantiate the methods of instantiated generic types that we have seen so far.
 	g.instantiateMethods()
@@ -72,56 +84,138 @@ func (g *irgen) stencil() {
 		// instantiated function if it hasn't been created yet, and change
 		// to calling that function directly.
 		modified := false
-		foundFuncInst := false
+		closureRequired := false
+		// declInfo will be non-nil exactly if we are scanning an instantiated function
+		declInfo := g.instInfoMap[decl.Sym()]
+
 		ir.Visit(decl, func(n ir.Node) {
 			if n.Op() == ir.OFUNCINST {
-				// We found a function instantiation that is not
-				// immediately called.
-				foundFuncInst = true
+				// generic F, not immediately called
+				closureRequired = true
 			}
-			if n.Op() != ir.OCALL || n.(*ir.CallExpr).X.Op() != ir.OFUNCINST {
-				return
+			if (n.Op() == ir.OMETHEXPR || n.Op() == ir.OMETHVALUE) && len(deref(n.(*ir.SelectorExpr).X.Type()).RParams()) > 0 && !types.IsInterfaceMethod(n.(*ir.SelectorExpr).Selection.Type) {
+				// T.M or x.M, where T or x is generic, but not immediately
+				// called. Not necessary if the method selected is
+				// actually for an embedded interface field.
+				closureRequired = true
+			}
+			if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OFUNCINST {
+				// We have found a function call using a generic function
+				// instantiation.
+				call := n.(*ir.CallExpr)
+				inst := call.X.(*ir.InstExpr)
+				nameNode, isMeth := g.getInstNameNode(inst)
+				targs := typecheck.TypesOf(inst.Targs)
+				st := g.getInstantiation(nameNode, targs, isMeth)
+				dictValue, usingSubdict := g.getDictOrSubdict(declInfo, n, nameNode, targs, isMeth)
+				if infoPrintMode {
+					dictkind := "Main dictionary"
+					if usingSubdict {
+						dictkind = "Sub-dictionary"
+					}
+					if inst.X.Op() == ir.OMETHVALUE {
+						fmt.Printf("%s in %v at generic method call: %v - %v\n", dictkind, decl, inst.X, call)
+					} else {
+						fmt.Printf("%s in %v at generic function call: %v - %v\n", dictkind, decl, inst.X, call)
+					}
+				}
+
+				// Transform the Call now, which changes OCALL to
+				// OCALLFUNC and does typecheckaste/assignconvfn. Do
+				// it before installing the instantiation, so we are
+				// checking against non-shape param types in
+				// typecheckaste.
+				transformCall(call)
+
+				// Replace the OFUNCINST with a direct reference to the
+				// new stenciled function
+				call.X = st.Nname
+				if inst.X.Op() == ir.OMETHVALUE {
+					// When we create an instantiation of a method
+					// call, we make it a function. So, move the
+					// receiver to be the first arg of the function
+					// call.
+					call.Args.Prepend(inst.X.(*ir.SelectorExpr).X)
+				}
+
+				// Add dictionary to argument list.
+				call.Args.Prepend(dictValue)
+				modified = true
+			}
+			if n.Op() == ir.OCALLMETH && n.(*ir.CallExpr).X.Op() == ir.ODOTMETH && len(deref(n.(*ir.CallExpr).X.Type().Recv().Type).RParams()) > 0 {
+				// Method call on a generic type, which was instantiated by stenciling.
+				// Method calls on explicitly instantiated types will have an OFUNCINST
+				// and are handled above.
+				call := n.(*ir.CallExpr)
+				meth := call.X.(*ir.SelectorExpr)
+				targs := deref(meth.Type().Recv().Type).RParams()
+
+				t := meth.X.Type()
+				baseSym := deref(t).OrigSym
+				baseType := baseSym.Def.(*ir.Name).Type()
+				var gf *ir.Name
+				for _, m := range baseType.Methods().Slice() {
+					if meth.Sel == m.Sym {
+						gf = m.Nname.(*ir.Name)
+						break
+					}
+				}
+
+				// Transform the Call now, which changes OCALL
+				// to OCALLFUNC and does typecheckaste/assignconvfn.
+				transformCall(call)
+
+				st := g.getInstantiation(gf, targs, true)
+				dictValue, usingSubdict := g.getDictOrSubdict(declInfo, n, gf, targs, true)
+				// We have to be using a subdictionary, since this is
+				// a generic method call.
+				assert(usingSubdict)
+
+				// Transform to a function call, by appending the
+				// dictionary and the receiver to the args.
+				call.SetOp(ir.OCALLFUNC)
+				call.X = st.Nname
+				call.Args.Prepend(dictValue, meth.X)
+				modified = true
 			}
-			// We have found a function call using a generic function
-			// instantiation.
-			call := n.(*ir.CallExpr)
-			inst := call.X.(*ir.InstExpr)
-			st := g.getInstantiationForNode(inst)
-			// Replace the OFUNCINST with a direct reference to the
-			// new stenciled function
-			call.X = st.Nname
-			if inst.X.Op() == ir.OCALLPART {
-				// When we create an instantiation of a method
-				// call, we make it a function. So, move the
-				// receiver to be the first arg of the function
-				// call.
-				withRecv := make([]ir.Node, len(call.Args)+1)
-				dot := inst.X.(*ir.SelectorExpr)
-				withRecv[0] = dot.X
-				copy(withRecv[1:], call.Args)
-				call.Args = withRecv
-			}
-			// Transform the Call now, which changes OCALL
-			// to OCALLFUNC and does typecheckaste/assignconvfn.
-			transformCall(call)
-			modified = true
 		})
 
-		// If we found an OFUNCINST without a corresponding call in the
-		// above decl, then traverse the nodes of decl again (with
+		// If we found a reference to a generic instantiation that wasn't an
+		// immediate call, then traverse the nodes of decl again (with
 		// EditChildren rather than Visit), where we actually change the
-		// OFUNCINST node to an ONAME for the instantiated function.
+		// reference to the instantiation to a closure that captures the
+		// dictionary, then does a direct call.
 		// EditChildren is more expensive than Visit, so we only do this
-		// in the infrequent case of an OFUNCINSt without a corresponding
+		// in the infrequent case of an OFUNCINST without a corresponding
 		// call.
-		if foundFuncInst {
+		if closureRequired {
+			modified = true
 			var edit func(ir.Node) ir.Node
+			var outer *ir.Func
+			if f, ok := decl.(*ir.Func); ok {
+				outer = f
+			}
 			edit = func(x ir.Node) ir.Node {
 				if x.Op() == ir.OFUNCINST {
-					st := g.getInstantiationForNode(x.(*ir.InstExpr))
-					return st.Nname
+					child := x.(*ir.InstExpr).X
+					if child.Op() == ir.OMETHEXPR || child.Op() == ir.OMETHVALUE {
+						// Call EditChildren on child (x.X),
+						// not x, so that we don't do
+						// buildClosure() on the
+						// METHEXPR/METHVALUE nodes as well.
+						ir.EditChildren(child, edit)
+						return g.buildClosure(outer, x)
+					}
 				}
 				ir.EditChildren(x, edit)
+				switch {
+				case x.Op() == ir.OFUNCINST:
+					return g.buildClosure(outer, x)
+				case (x.Op() == ir.OMETHEXPR || x.Op() == ir.OMETHVALUE) &&
+					len(deref(x.(*ir.SelectorExpr).X.Type()).RParams()) > 0 &&
+					!types.IsInterfaceMethod(x.(*ir.SelectorExpr).Selection.Type):
+					return g.buildClosure(outer, x)
+				}
 				return x
 			}
 			edit(decl)
@@ -137,104 +231,392 @@ func (g *irgen) stencil() {
 		g.instantiateMethods()
 	}
 
+	g.finalizeSyms()
+}
+
+// buildClosure makes a closure to implement x, a OFUNCINST or OMETHEXPR
+// of generic type. outer is the containing function (or nil if closure is
+// in a global assignment instead of a function).
+func (g *irgen) buildClosure(outer *ir.Func, x ir.Node) ir.Node {
+	pos := x.Pos()
+	var target *ir.Func   // target instantiated function/method
+	var dictValue ir.Node // dictionary to use
+	var rcvrValue ir.Node // receiver, if a method value
+	typ := x.Type()       // type of the closure
+	var outerInfo *instInfo
+	if outer != nil {
+		outerInfo = g.instInfoMap[outer.Sym()]
+	}
+	usingSubdict := false
+	valueMethod := false
+	if x.Op() == ir.OFUNCINST {
+		inst := x.(*ir.InstExpr)
+
+		// Type arguments we're instantiating with.
+		targs := typecheck.TypesOf(inst.Targs)
+
+		// Find the generic function/method.
+		var gf *ir.Name
+		if inst.X.Op() == ir.ONAME {
+			// Instantiating a generic function call.
+			gf = inst.X.(*ir.Name)
+		} else if inst.X.Op() == ir.OMETHVALUE {
+			// Instantiating a method value x.M.
+			se := inst.X.(*ir.SelectorExpr)
+			rcvrValue = se.X
+			gf = se.Selection.Nname.(*ir.Name)
+		} else {
+			panic("unhandled")
+		}
+
+		// target is the instantiated function we're trying to call.
+		// For functions, the target expects a dictionary as its first argument.
+		// For method values, the target expects a dictionary and the receiver
+		// as its first two arguments.
+		// dictValue is the value to use for the dictionary argument.
+		target = g.getInstantiation(gf, targs, rcvrValue != nil)
+		dictValue, usingSubdict = g.getDictOrSubdict(outerInfo, x, gf, targs, rcvrValue != nil)
+		if infoPrintMode {
+			dictkind := "Main dictionary"
+			if usingSubdict {
+				dictkind = "Sub-dictionary"
+			}
+			if rcvrValue == nil {
+				fmt.Printf("%s in %v for generic function value %v\n", dictkind, outer, inst.X)
+			} else {
+				fmt.Printf("%s in %v for generic method value %v\n", dictkind, outer, inst.X)
+			}
+		}
+	} else { // ir.OMETHEXPR or ir.METHVALUE
+		// Method expression T.M where T is a generic type.
+		se := x.(*ir.SelectorExpr)
+		targs := deref(se.X.Type()).RParams()
+		if len(targs) == 0 {
+			panic("bad")
+		}
+		if x.Op() == ir.OMETHVALUE {
+			rcvrValue = se.X
+		}
+
+		// se.X.Type() is the top-level type of the method expression. To
+		// correctly handle method expressions involving embedded fields,
+		// look up the generic method below using the type of the receiver
+		// of se.Selection, since that will be the type that actually has
+		// the method.
+		recv := deref(se.Selection.Type.Recv().Type)
+		if len(recv.RParams()) == 0 {
+			// The embedded type that actually has the method is not
+			// actually generic, so no need to build a closure.
+			return x
+		}
+		baseType := recv.OrigSym.Def.Type()
+		var gf *ir.Name
+		for _, m := range baseType.Methods().Slice() {
+			if se.Sel == m.Sym {
+				gf = m.Nname.(*ir.Name)
+				break
+			}
+		}
+		if !gf.Type().Recv().Type.IsPtr() {
+			// Remember if value method, so we can detect (*T).M case.
+			valueMethod = true
+		}
+		target = g.getInstantiation(gf, targs, true)
+		dictValue, usingSubdict = g.getDictOrSubdict(outerInfo, x, gf, targs, true)
+		if infoPrintMode {
+			dictkind := "Main dictionary"
+			if usingSubdict {
+				dictkind = "Sub-dictionary"
+			}
+			fmt.Printf("%s in %v for method expression %v\n", dictkind, outer, x)
+		}
+	}
+
+	// Build a closure to implement a function instantiation.
+	//
+	//   func f[T any] (int, int) (int, int) { ...whatever... }
+	//
+	// Then any reference to f[int] not directly called gets rewritten to
+	//
+	//   .dictN := ... dictionary to use ...
+	//   func(a0, a1 int) (r0, r1 int) {
+	//     return .inst.f[int](.dictN, a0, a1)
+	//   }
+	//
+	// Similarly for method expressions,
+	//
+	//   type g[T any] ....
+	//   func (rcvr g[T]) f(a0, a1 int) (r0, r1 int) { ... }
+	//
+	// Any reference to g[int].f not directly called gets rewritten to
+	//
+	//   .dictN := ... dictionary to use ...
+	//   func(rcvr g[int], a0, a1 int) (r0, r1 int) {
+	//     return .inst.g[int].f(.dictN, rcvr, a0, a1)
+	//   }
+	//
+	// Also method values
+	//
+	//   var x g[int]
+	//
+	// Any reference to x.f not directly called gets rewritten to
+	//
+	//   .dictN := ... dictionary to use ...
+	//   x2 := x
+	//   func(a0, a1 int) (r0, r1 int) {
+	//     return .inst.g[int].f(.dictN, x2, a0, a1)
+	//   }
+
+	// Make a new internal function.
+	fn, formalParams, formalResults := startClosure(pos, outer, typ)
+
+	// This is the dictionary we want to use.
+	// It may be a constant, or it may be a dictionary acquired from the outer function's dictionary.
+	// For the latter, dictVar is a variable in the outer function's scope, set to the subdictionary
+	// read from the outer function's dictionary.
+	var dictVar *ir.Name
+	var dictAssign *ir.AssignStmt
+	if outer != nil {
+		// Note: for now this is a compile-time constant, so we don't really need a closure
+		// to capture it (a wrapper function would work just as well). But eventually it
+		// will be a read of a subdictionary from the parent dictionary.
+		dictVar = ir.NewNameAt(pos, typecheck.LookupNum(".dict", g.dnum))
+		g.dnum++
+		dictVar.Class = ir.PAUTO
+		typed(types.Types[types.TUINTPTR], dictVar)
+		dictVar.Curfn = outer
+		dictAssign = ir.NewAssignStmt(pos, dictVar, dictValue)
+		dictAssign.SetTypecheck(1)
+		dictVar.Defn = dictAssign
+		outer.Dcl = append(outer.Dcl, dictVar)
+	}
+	// assign the receiver to a temporary.
+	var rcvrVar *ir.Name
+	var rcvrAssign ir.Node
+	if rcvrValue != nil {
+		rcvrVar = ir.NewNameAt(pos, typecheck.LookupNum(".rcvr", g.dnum))
+		g.dnum++
+		rcvrVar.Class = ir.PAUTO
+		typed(rcvrValue.Type(), rcvrVar)
+		rcvrVar.Curfn = outer
+		rcvrAssign = ir.NewAssignStmt(pos, rcvrVar, rcvrValue)
+		rcvrAssign.SetTypecheck(1)
+		rcvrVar.Defn = rcvrAssign
+		outer.Dcl = append(outer.Dcl, rcvrVar)
+	}
+
+	// Build body of closure. This involves just calling the wrapped function directly
+	// with the additional dictionary argument.
+
+	// First, figure out the dictionary argument.
+	var dict2Var ir.Node
+	if usingSubdict {
+		// Capture sub-dictionary calculated in the outer function
+		dict2Var = ir.CaptureName(pos, fn, dictVar)
+		typed(types.Types[types.TUINTPTR], dict2Var)
+	} else {
+		// Static dictionary, so can be used directly in the closure
+		dict2Var = dictValue
+	}
+	// Also capture the receiver variable.
+	var rcvr2Var *ir.Name
+	if rcvrValue != nil {
+		rcvr2Var = ir.CaptureName(pos, fn, rcvrVar)
+	}
+
+	// Build arguments to call inside the closure.
+	var args []ir.Node
+
+	// First the dictionary argument.
+	args = append(args, dict2Var)
+	// Then the receiver.
+	if rcvrValue != nil {
+		args = append(args, rcvr2Var)
+	}
+	// Then all the other arguments (including receiver for method expressions).
+	for i := 0; i < typ.NumParams(); i++ {
+		if x.Op() == ir.OMETHEXPR && i == 0 {
+			// If we are doing a method expression, we need to
+			// explicitly traverse any embedded fields in the receiver
+			// argument in order to call the method instantiation.
+			arg0 := formalParams[0].Nname.(ir.Node)
+			arg0 = typecheck.AddImplicitDots(ir.NewSelectorExpr(base.Pos, ir.OXDOT, arg0, x.(*ir.SelectorExpr).Sel)).X
+			if valueMethod && arg0.Type().IsPtr() {
+				// For handling the (*T).M case: if we have a pointer
+				// receiver after following all the embedded fields,
+				// but it's a value method, add a star operator.
+				arg0 = ir.NewStarExpr(arg0.Pos(), arg0)
+			}
+			args = append(args, arg0)
+		} else {
+			args = append(args, formalParams[i].Nname.(*ir.Name))
+		}
+	}
+
+	// Build call itself.
+	var innerCall ir.Node = ir.NewCallExpr(pos, ir.OCALL, target.Nname, args)
+	if len(formalResults) > 0 {
+		innerCall = ir.NewReturnStmt(pos, []ir.Node{innerCall})
+	}
+	// Finish building body of closure.
+	ir.CurFunc = fn
+	// TODO: set types directly here instead of using typecheck.Stmt
+	typecheck.Stmt(innerCall)
+	ir.CurFunc = nil
+	fn.Body = []ir.Node{innerCall}
+
+	// We're all done with the captured dictionary (and receiver, for method values).
+	ir.FinishCaptureNames(pos, outer, fn)
+
+	// Make a closure referencing our new internal function.
+	c := ir.UseClosure(fn.OClosure, g.target)
+	var init []ir.Node
+	if outer != nil {
+		init = append(init, dictAssign)
+	}
+	if rcvrValue != nil {
+		init = append(init, rcvrAssign)
+	}
+	return ir.InitExpr(init, c)
 }
 
-// instantiateMethods instantiates all the methods of all fully-instantiated
-// generic types that have been added to g.instTypeList.
+// instantiateMethods instantiates all the methods (and associated dictionaries) of
+// all fully-instantiated generic types that have been added to g.instTypeList.
 func (g *irgen) instantiateMethods() {
 	for i := 0; i < len(g.instTypeList); i++ {
 		typ := g.instTypeList[i]
-		// Get the base generic type by looking up the symbol of the
-		// generic (uninstantiated) name.
-		baseSym := typ.Sym().Pkg.Lookup(genericTypeName(typ.Sym()))
+		assert(!typ.HasShape())
+		// Mark runtime type as needed, since this ensures that the
+		// compiler puts out the needed DWARF symbols, when this
+		// instantiated type has a different package from the local
+		// package.
+		typecheck.NeedRuntimeType(typ)
+		// Lookup the method on the base generic type, since methods may
+		// not be set on imported instantiated types.
+		baseSym := typ.OrigSym
 		baseType := baseSym.Def.(*ir.Name).Type()
-		for j, m := range typ.Methods().Slice() {
-			name := m.Nname.(*ir.Name)
-			targs := make([]ir.Node, len(typ.RParams()))
-			for k, targ := range typ.RParams() {
-				targs[k] = ir.TypeNode(targ)
+		for j, _ := range typ.Methods().Slice() {
+			if baseType.Methods().Slice()[j].Nointerface() {
+				typ.Methods().Slice()[j].SetNointerface(true)
 			}
 			baseNname := baseType.Methods().Slice()[j].Nname.(*ir.Name)
-			name.Func = g.getInstantiation(baseNname, targs, true)
+			// Eagerly generate the instantiations and dictionaries that implement these methods.
+			// We don't use the instantiations here, just generate them (and any
+			// further instantiations those generate, etc.).
+			// Note that we don't set the Func for any methods on instantiated
+			// types. Their signatures don't match so that would be confusing.
+			// Direct method calls go directly to the instantiations, implemented above.
+			// Indirect method calls use wrappers generated in reflectcall. Those wrappers
+			// will use these instantiations if they are needed (for interface tables or reflection).
+			_ = g.getInstantiation(baseNname, typ.RParams(), true)
+			_ = g.getDictionarySym(baseNname, typ.RParams(), true)
 		}
 	}
 	g.instTypeList = nil
 
 }
 
-// genericSym returns the name of the base generic type for the type named by
-// sym. It simply returns the name obtained by removing everything after the
-// first bracket ("[").
-func genericTypeName(sym *types.Sym) string {
-	return sym.Name[0:strings.Index(sym.Name, "[")]
-}
-
-// getInstantiationForNode returns the function/method instantiation for a
-// InstExpr node inst.
-func (g *irgen) getInstantiationForNode(inst *ir.InstExpr) *ir.Func {
+// getInstNameNode returns the name node for the method or function being instantiated, and a bool which is true if a method is being instantiated.
+func (g *irgen) getInstNameNode(inst *ir.InstExpr) (*ir.Name, bool) {
 	if meth, ok := inst.X.(*ir.SelectorExpr); ok {
-		return g.getInstantiation(meth.Selection.Nname.(*ir.Name), inst.Targs, true)
+		return meth.Selection.Nname.(*ir.Name), true
 	} else {
-		return g.getInstantiation(inst.X.(*ir.Name), inst.Targs, false)
+		return inst.X.(*ir.Name), false
 	}
 }
 
-// getInstantiation gets the instantiantion of the function or method nameNode
-// with the type arguments targs. If the instantiated function is not already
-// cached, then it calls genericSubst to create the new instantiation.
-func (g *irgen) getInstantiation(nameNode *ir.Name, targs []ir.Node, isMeth bool) *ir.Func {
-	sym := makeInstName(nameNode.Sym(), targs, isMeth)
-	st := g.target.Stencils[sym]
-	if st == nil {
-		// If instantiation doesn't exist yet, create it and add
-		// to the list of decls.
-		st = g.genericSubst(sym, nameNode, targs, isMeth)
-		g.target.Stencils[sym] = st
-		g.target.Decls = append(g.target.Decls, st)
-		if base.Flag.W > 1 {
-			ir.Dump(fmt.Sprintf("\nstenciled %v", st), st)
+// getDictOrSubdict returns, for a method/function call or reference (node n) in an
+// instantiation (described by instInfo), a node which is accessing a sub-dictionary
+// or main/static dictionary, as needed, and also returns a boolean indicating if a
+// sub-dictionary was accessed. nameNode is the particular function or method being
+// called/referenced, and targs are the type arguments.
+func (g *irgen) getDictOrSubdict(declInfo *instInfo, n ir.Node, nameNode *ir.Name, targs []*types.Type, isMeth bool) (ir.Node, bool) {
+	var dict ir.Node
+	usingSubdict := false
+	if declInfo != nil {
+		// Get the dictionary arg via sub-dictionary reference
+		entry, ok := declInfo.dictEntryMap[n]
+		// If the entry is not found, it may be that this node did not have
+		// any type args that depend on type params, so we need a main
+		// dictionary, not a sub-dictionary.
+		if ok {
+			dict = getDictionaryEntry(n.Pos(), declInfo.dictParam, entry, declInfo.dictLen)
+			usingSubdict = true
 		}
 	}
-	return st
+	if !usingSubdict {
+		dict = g.getDictionaryValue(nameNode, targs, isMeth)
+	}
+	return dict, usingSubdict
 }
 
-// makeInstName makes the unique name for a stenciled generic function or method,
-// based on the name of the function fy=nsym and the targs. It replaces any
-// existing bracket type list in the name. makeInstName asserts that fnsym has
-// brackets in its name if and only if hasBrackets is true.
-// TODO(danscales): remove the assertions and the hasBrackets argument later.
-//
-// Names of declared generic functions have no brackets originally, so hasBrackets
-// should be false. Names of generic methods already have brackets, since the new
-// type parameter is specified in the generic type of the receiver (e.g. func
-// (func (v *value[T]).set(...) { ... } has the original name (*value[T]).set.
-//
-// The standard naming is something like: 'genFn[int,bool]' for functions and
-// '(*genType[int,bool]).methodName' for methods
-func makeInstName(fnsym *types.Sym, targs []ir.Node, hasBrackets bool) *types.Sym {
-	b := bytes.NewBufferString("")
-	name := fnsym.Name
-	i := strings.Index(name, "[")
-	assert(hasBrackets == (i >= 0))
-	if i >= 0 {
-		b.WriteString(name[0:i])
-	} else {
-		b.WriteString(name)
+// checkFetchBody checks if a generic body can be fetched, but hasn't been loaded
+// yet. If so, it imports the body.
+func checkFetchBody(nameNode *ir.Name) {
+	if nameNode.Func.Body == nil && nameNode.Func.Inl != nil {
+		// If there is no body yet but Func.Inl exists, then we can can
+		// import the whole generic body.
+		assert(nameNode.Func.Inl.Cost == 1 && nameNode.Sym().Pkg != types.LocalPkg)
+		typecheck.ImportBody(nameNode.Func)
+		assert(nameNode.Func.Inl.Body != nil)
+		nameNode.Func.Body = nameNode.Func.Inl.Body
+		nameNode.Func.Dcl = nameNode.Func.Inl.Dcl
 	}
-	b.WriteString("[")
-	for i, targ := range targs {
-		if i > 0 {
-			b.WriteString(",")
+}
+
+// getInstantiation gets the instantiantion and dictionary of the function or method nameNode
+// with the type arguments shapes. If the instantiated function is not already
+// cached, then it calls genericSubst to create the new instantiation.
+func (g *irgen) getInstantiation(nameNode *ir.Name, shapes []*types.Type, isMeth bool) *ir.Func {
+	checkFetchBody(nameNode)
+
+	// Convert any non-shape type arguments to their shape, so we can reduce the
+	// number of instantiations we have to generate. You can actually have a mix
+	// of shape and non-shape arguments, because of inferred or explicitly
+	// specified concrete type args.
+	var s1 []*types.Type
+	for i, t := range shapes {
+		if !t.HasShape() {
+			if s1 == nil {
+				s1 = make([]*types.Type, len(shapes))
+				copy(s1[0:i], shapes[0:i])
+			}
+			s1[i] = typecheck.Shapify(t)
+		} else if s1 != nil {
+			s1[i] = shapes[i]
 		}
-		b.WriteString(targ.Type().String())
 	}
-	b.WriteString("]")
-	if i >= 0 {
-		i2 := strings.Index(name[i:], "]")
-		assert(i2 >= 0)
-		b.WriteString(name[i+i2+1:])
+	if s1 != nil {
+		shapes = s1
 	}
-	return typecheck.Lookup(b.String())
+
+	sym := typecheck.MakeFuncInstSym(nameNode.Sym(), shapes, isMeth)
+	info := g.instInfoMap[sym]
+	if info == nil {
+		// If instantiation doesn't exist yet, create it and add
+		// to the list of decls.
+		gfInfo := g.getGfInfo(nameNode)
+		info = &instInfo{
+			gf:            nameNode,
+			gfInfo:        gfInfo,
+			startSubDict:  len(shapes) + len(gfInfo.derivedTypes),
+			startItabConv: len(shapes) + len(gfInfo.derivedTypes) + len(gfInfo.subDictCalls),
+			dictLen:       len(shapes) + len(gfInfo.derivedTypes) + len(gfInfo.subDictCalls) + len(gfInfo.itabConvs),
+			dictEntryMap:  make(map[ir.Node]int),
+		}
+		// genericSubst fills in info.dictParam and info.dictEntryMap.
+		st := g.genericSubst(sym, nameNode, shapes, isMeth, info)
+		info.fun = st
+		g.instInfoMap[sym] = info
+		// This ensures that the linker drops duplicates of this instantiation.
+		// All just works!
+		st.SetDupok(true)
+		g.target.Decls = append(g.target.Decls, st)
+		if base.Flag.W > 1 {
+			ir.Dump(fmt.Sprintf("\nstenciled %v", st), st)
+		}
+	}
+	return info.fun
 }
 
 // Struct containing info needed for doing the substitution as we create the
@@ -243,32 +625,30 @@ type subster struct {
 	g        *irgen
 	isMethod bool     // If a method is being instantiated
 	newf     *ir.Func // Func node for the new stenciled function
-	tparams  []*types.Field
-	targs    []ir.Node
-	// The substitution map from name nodes in the generic function to the
-	// name nodes in the new stenciled function.
-	vars map[*ir.Name]*ir.Name
+	ts       typecheck.Tsubster
+	info     *instInfo // Place to put extra info in the instantiation
 }
 
 // genericSubst returns a new function with name newsym. The function is an
 // instantiation of a generic function or method specified by namedNode with type
-// args targs. For a method with a generic receiver, it returns an instantiated
-// function type where the receiver becomes the first parameter. Otherwise the
-// instantiated method would still need to be transformed by later compiler
-// phases.
-func (g *irgen) genericSubst(newsym *types.Sym, nameNode *ir.Name, targs []ir.Node, isMethod bool) *ir.Func {
-	var tparams []*types.Field
+// args shapes. For a method with a generic receiver, it returns an instantiated
+// function type where the receiver becomes the first parameter. For either a generic
+// method or function, a dictionary parameter is the added as the very first
+// parameter. genericSubst fills in info.dictParam and info.dictEntryMap.
+func (g *irgen) genericSubst(newsym *types.Sym, nameNode *ir.Name, shapes []*types.Type, isMethod bool, info *instInfo) *ir.Func {
+	var tparams []*types.Type
 	if isMethod {
 		// Get the type params from the method receiver (after skipping
 		// over any pointer)
 		recvType := nameNode.Type().Recv().Type
 		recvType = deref(recvType)
-		tparams = make([]*types.Field, len(recvType.RParams()))
-		for i, rparam := range recvType.RParams() {
-			tparams[i] = types.NewField(src.NoXPos, nil, rparam)
-		}
+		tparams = recvType.RParams()
 	} else {
-		tparams = nameNode.Type().TParams().Fields().Slice()
+		fields := nameNode.Type().TParams().Fields().Slice()
+		tparams = make([]*types.Type, len(fields))
+		for i, f := range fields {
+			tparams[i] = f.Type
+		}
 	}
 	gf := nameNode.Func
 	// Pos of the instantiated function is same as the generic function
@@ -283,78 +663,214 @@ func (g *irgen) genericSubst(newsym *types.Sym, nameNode *ir.Name, targs []ir.No
 	// depend on ir.CurFunc being set.
 	ir.CurFunc = newf
 
-	assert(len(tparams) == len(targs))
+	assert(len(tparams) == len(shapes))
 
 	subst := &subster{
 		g:        g,
 		isMethod: isMethod,
 		newf:     newf,
-		tparams:  tparams,
-		targs:    targs,
-		vars:     make(map[*ir.Name]*ir.Name),
+		info:     info,
+		ts: typecheck.Tsubster{
+			Tparams: tparams,
+			Targs:   shapes,
+			Vars:    make(map[*ir.Name]*ir.Name),
+		},
 	}
 
-	newf.Dcl = make([]*ir.Name, len(gf.Dcl))
-	for i, n := range gf.Dcl {
-		newf.Dcl[i] = subst.node(n).(*ir.Name)
+	newf.Dcl = make([]*ir.Name, 0, len(gf.Dcl)+1)
+
+	// Create the needed dictionary param
+	dictionarySym := newsym.Pkg.Lookup(".dict")
+	dictionaryType := types.Types[types.TUINTPTR]
+	dictionaryName := ir.NewNameAt(gf.Pos(), dictionarySym)
+	typed(dictionaryType, dictionaryName)
+	dictionaryName.Class = ir.PPARAM
+	dictionaryName.Curfn = newf
+	newf.Dcl = append(newf.Dcl, dictionaryName)
+	for _, n := range gf.Dcl {
+		if n.Sym().Name == ".dict" {
+			panic("already has dictionary")
+		}
+		newf.Dcl = append(newf.Dcl, subst.localvar(n))
 	}
+	dictionaryArg := types.NewField(gf.Pos(), dictionarySym, dictionaryType)
+	dictionaryArg.Nname = dictionaryName
+	info.dictParam = dictionaryName
 
-	// Ugly: we have to insert the Name nodes of the parameters/results into
+	// We add the dictionary as the first parameter in the function signature.
+	// We also transform a method type to the corresponding function type
+	// (make the receiver be the next parameter after the dictionary).
+	oldt := nameNode.Type()
+	var args []*types.Field
+	args = append(args, dictionaryArg)
+	args = append(args, oldt.Recvs().FieldSlice()...)
+	args = append(args, oldt.Params().FieldSlice()...)
+
+	// Replace the types in the function signature via subst.fields.
+	// Ugly: also, we have to insert the Name nodes of the parameters/results into
 	// the function type. The current function type has no Nname fields set,
 	// because it came via conversion from the types2 type.
-	oldt := nameNode.Type()
-	// We also transform a generic method type to the corresponding
-	// instantiated function type where the receiver is the first parameter.
 	newt := types.NewSignature(oldt.Pkg(), nil, nil,
-		subst.fields(ir.PPARAM, append(oldt.Recvs().FieldSlice(), oldt.Params().FieldSlice()...), newf.Dcl),
+		subst.fields(ir.PPARAM, args, newf.Dcl),
 		subst.fields(ir.PPARAMOUT, oldt.Results().FieldSlice(), newf.Dcl))
 
-	newf.Nname.SetType(newt)
+	typed(newt, newf.Nname)
 	ir.MarkFunc(newf.Nname)
 	newf.SetTypecheck(1)
-	newf.Nname.SetTypecheck(1)
 
 	// Make sure name/type of newf is set before substituting the body.
 	newf.Body = subst.list(gf.Body)
+
+	// Add code to check that the dictionary is correct.
+	// TODO: must be adjusted to deal with shapes, but will go away soon when we move
+	// to many->1 shape to concrete mapping.
+	// newf.Body.Prepend(subst.checkDictionary(dictionaryName, shapes)...)
+
 	ir.CurFunc = savef
+	// Add any new, fully instantiated types seen during the substitution to
+	// g.instTypeList.
+	g.instTypeList = append(g.instTypeList, subst.ts.InstTypeList...)
+
+	if doubleCheck {
+		okConvs := map[ir.Node]bool{}
+		ir.Visit(newf, func(n ir.Node) {
+			if n.Op() == ir.OIDATA {
+				// IDATA(OCONVIFACE(x)) is ok, as we don't use the type of x.
+				// TODO: use some other op besides OCONVIFACE. ONEW might work
+				// (with appropriate direct vs. indirect interface cases).
+				okConvs[n.(*ir.UnaryExpr).X] = true
+			}
+			if n.Op() == ir.OCONVIFACE && !okConvs[n] {
+				c := n.(*ir.ConvExpr)
+				if c.X.Type().HasShape() {
+					ir.Dump("BAD FUNCTION", newf)
+					ir.Dump("BAD CONVERSION", c)
+					base.Fatalf("converting shape type to interface")
+				}
+			}
+		})
+	}
 
 	return newf
 }
 
-// node is like DeepCopy(), but creates distinct ONAME nodes, and also descends
-// into closures. It substitutes type arguments for type parameters in all the new
-// nodes.
+// localvar creates a new name node for the specified local variable and enters it
+// in subst.vars. It substitutes type arguments for type parameters in the type of
+// name as needed.
+func (subst *subster) localvar(name *ir.Name) *ir.Name {
+	m := ir.NewNameAt(name.Pos(), name.Sym())
+	if name.IsClosureVar() {
+		m.SetIsClosureVar(true)
+	}
+	m.SetType(subst.ts.Typ(name.Type()))
+	m.BuiltinOp = name.BuiltinOp
+	m.Curfn = subst.newf
+	m.Class = name.Class
+	assert(name.Class != ir.PEXTERN && name.Class != ir.PFUNC)
+	m.Func = name.Func
+	subst.ts.Vars[name] = m
+	m.SetTypecheck(1)
+	return m
+}
+
+// checkDictionary returns code that does runtime consistency checks
+// between the dictionary and the types it should contain.
+func (subst *subster) checkDictionary(name *ir.Name, targs []*types.Type) (code []ir.Node) {
+	if false {
+		return // checking turned off
+	}
+	// TODO: when moving to GCshape, this test will become harder. Call into
+	// runtime to check the expected shape is correct?
+	pos := name.Pos()
+	// Convert dictionary to *[N]uintptr
+	d := ir.NewConvExpr(pos, ir.OCONVNOP, types.Types[types.TUNSAFEPTR], name)
+	d.SetTypecheck(1)
+	d = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewArray(types.Types[types.TUINTPTR], int64(len(targs))).PtrTo(), d)
+	d.SetTypecheck(1)
+	types.CheckSize(d.Type().Elem())
+
+	// Check that each type entry in the dictionary is correct.
+	for i, t := range targs {
+		if t.HasShape() {
+			// Check the concrete type, not the shape type.
+			base.Fatalf("shape type in dictionary %s %+v\n", name.Sym().Name, t)
+		}
+		want := reflectdata.TypePtr(t)
+		typed(types.Types[types.TUINTPTR], want)
+		deref := ir.NewStarExpr(pos, d)
+		typed(d.Type().Elem(), deref)
+		idx := ir.NewConstExpr(constant.MakeUint64(uint64(i)), name) // TODO: what to set orig to?
+		typed(types.Types[types.TUINTPTR], idx)
+		got := ir.NewIndexExpr(pos, deref, idx)
+		typed(types.Types[types.TUINTPTR], got)
+		cond := ir.NewBinaryExpr(pos, ir.ONE, want, got)
+		typed(types.Types[types.TBOOL], cond)
+		panicArg := ir.NewNilExpr(pos)
+		typed(types.NewInterface(types.LocalPkg, nil), panicArg)
+		then := ir.NewUnaryExpr(pos, ir.OPANIC, panicArg)
+		then.SetTypecheck(1)
+		x := ir.NewIfStmt(pos, cond, []ir.Node{then}, nil)
+		x.SetTypecheck(1)
+		code = append(code, x)
+	}
+	return
+}
+
+// getDictionaryEntry gets the i'th entry in the dictionary dict.
+func getDictionaryEntry(pos src.XPos, dict *ir.Name, i int, size int) ir.Node {
+	// Convert dictionary to *[N]uintptr
+	// All entries in the dictionary are pointers. They all point to static data, though, so we
+	// treat them as uintptrs so the GC doesn't need to keep track of them.
+	d := ir.NewConvExpr(pos, ir.OCONVNOP, types.Types[types.TUNSAFEPTR], dict)
+	d.SetTypecheck(1)
+	d = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewArray(types.Types[types.TUINTPTR], int64(size)).PtrTo(), d)
+	d.SetTypecheck(1)
+	types.CheckSize(d.Type().Elem())
+
+	// Load entry i out of the dictionary.
+	deref := ir.NewStarExpr(pos, d)
+	typed(d.Type().Elem(), deref)
+	idx := ir.NewConstExpr(constant.MakeUint64(uint64(i)), dict) // TODO: what to set orig to?
+	typed(types.Types[types.TUINTPTR], idx)
+	r := ir.NewIndexExpr(pos, deref, idx)
+	typed(types.Types[types.TUINTPTR], r)
+	return r
+}
+
+// getDictionaryType returns a *runtime._type from the dictionary entry i (which
+// refers to a type param or a derived type that uses type params). It uses the
+// specified dictionary dictParam, rather than the one in info.dictParam.
+func getDictionaryType(info *instInfo, dictParam *ir.Name, pos src.XPos, i int) ir.Node {
+	if i < 0 || i >= info.startSubDict {
+		base.Fatalf(fmt.Sprintf("bad dict index %d", i))
+	}
+
+	r := getDictionaryEntry(pos, info.dictParam, i, info.startSubDict)
+	// change type of retrieved dictionary entry to *byte, which is the
+	// standard typing of a *runtime._type in the compiler
+	typed(types.Types[types.TUINT8].PtrTo(), r)
+	return r
+}
+
+// node is like DeepCopy(), but substitutes ONAME nodes based on subst.ts.vars, and
+// also descends into closures. It substitutes type arguments for type parameters
+// in all the new nodes.
 func (subst *subster) node(n ir.Node) ir.Node {
 	// Use closure to capture all state needed by the ir.EditChildren argument.
 	var edit func(ir.Node) ir.Node
 	edit = func(x ir.Node) ir.Node {
 		switch x.Op() {
 		case ir.OTYPE:
-			return ir.TypeNode(subst.typ(x.Type()))
+			return ir.TypeNode(subst.ts.Typ(x.Type()))
 
 		case ir.ONAME:
-			name := x.(*ir.Name)
-			if v := subst.vars[name]; v != nil {
+			if v := subst.ts.Vars[x.(*ir.Name)]; v != nil {
 				return v
 			}
-			m := ir.NewNameAt(name.Pos(), name.Sym())
-			if name.IsClosureVar() {
-				m.SetIsClosureVar(true)
-			}
-			t := x.Type()
-			if t == nil {
-				assert(name.BuiltinOp != 0)
-			} else {
-				newt := subst.typ(t)
-				m.SetType(newt)
-			}
-			m.BuiltinOp = name.BuiltinOp
-			m.Curfn = subst.newf
-			m.Class = name.Class
-			m.Func = name.Func
-			subst.vars[name] = m
-			m.SetTypecheck(1)
-			return m
+			return x
+		case ir.ONONAME:
+			// This handles the identifier in a type switch guard
+			fallthrough
 		case ir.OLITERAL, ir.ONIL:
 			if x.Sym() != nil {
 				return x
@@ -369,55 +885,66 @@ func (subst *subster) node(n ir.Node) ir.Node {
 				// an error.
 				_, isCallExpr := m.(*ir.CallExpr)
 				_, isStructKeyExpr := m.(*ir.StructKeyExpr)
-				if !isCallExpr && !isStructKeyExpr && x.Op() != ir.OPANIC &&
+				_, isKeyExpr := m.(*ir.KeyExpr)
+				if !isCallExpr && !isStructKeyExpr && !isKeyExpr && x.Op() != ir.OPANIC &&
 					x.Op() != ir.OCLOSE {
 					base.Fatalf(fmt.Sprintf("Nil type for %v", x))
 				}
 			} else if x.Op() != ir.OCLOSURE {
-				m.SetType(subst.typ(x.Type()))
+				m.SetType(subst.ts.Typ(x.Type()))
 			}
 		}
-		ir.EditChildren(m, edit)
-
-		if x.Typecheck() == 3 {
-			// These are nodes whose transforms were delayed until
-			// their instantiated type was known.
-			m.SetTypecheck(1)
-			if typecheck.IsCmp(x.Op()) {
-				transformCompare(m.(*ir.BinaryExpr))
-			} else {
-				switch x.Op() {
-				case ir.OSLICE, ir.OSLICE3:
-					transformSlice(m.(*ir.SliceExpr))
-
-				case ir.OADD:
-					m = transformAdd(m.(*ir.BinaryExpr))
 
-				case ir.OINDEX:
-					transformIndex(m.(*ir.IndexExpr))
+		for i, de := range subst.info.gfInfo.subDictCalls {
+			if de == x {
+				// Remember the dictionary entry associated with this
+				// node in the instantiated function
+				// TODO: make sure this remains correct with respect to the
+				// transformations below.
+				subst.info.dictEntryMap[m] = subst.info.startSubDict + i
+				break
+			}
+		}
 
-				case ir.OAS2:
-					as2 := m.(*ir.AssignListStmt)
-					transformAssign(as2, as2.Lhs, as2.Rhs)
+		ir.EditChildren(m, edit)
 
-				case ir.OAS:
-					as := m.(*ir.AssignStmt)
+		m.SetTypecheck(1)
+		if typecheck.IsCmp(x.Op()) {
+			transformCompare(m.(*ir.BinaryExpr))
+		} else {
+			switch x.Op() {
+			case ir.OSLICE, ir.OSLICE3:
+				transformSlice(m.(*ir.SliceExpr))
+
+			case ir.OADD:
+				m = transformAdd(m.(*ir.BinaryExpr))
+
+			case ir.OINDEX:
+				transformIndex(m.(*ir.IndexExpr))
+
+			case ir.OAS2:
+				as2 := m.(*ir.AssignListStmt)
+				transformAssign(as2, as2.Lhs, as2.Rhs)
+
+			case ir.OAS:
+				as := m.(*ir.AssignStmt)
+				if as.Y != nil {
+					// transformAssign doesn't handle the case
+					// of zeroing assignment of a dcl (rhs[0] is nil).
 					lhs, rhs := []ir.Node{as.X}, []ir.Node{as.Y}
 					transformAssign(as, lhs, rhs)
+				}
 
-				case ir.OASOP:
-					as := m.(*ir.AssignOpStmt)
-					transformCheckAssign(as, as.X)
+			case ir.OASOP:
+				as := m.(*ir.AssignOpStmt)
+				transformCheckAssign(as, as.X)
 
-				case ir.ORETURN:
-					transformReturn(m.(*ir.ReturnStmt))
+			case ir.ORETURN:
+				transformReturn(m.(*ir.ReturnStmt))
 
-				case ir.OSEND:
-					transformSend(m.(*ir.SendStmt))
+			case ir.OSEND:
+				transformSend(m.(*ir.SendStmt))
 
-				default:
-					base.Fatalf("Unexpected node with Typecheck() == 3")
-				}
 			}
 		}
 
@@ -445,11 +972,40 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			// instantiated receiver type. We need to do this now,
 			// since the access/selection to the method for the real
 			// type is very different from the selection for the type
-			// param. m will be transformed to an OCALLPART node. It
+			// param. m will be transformed to an OMETHVALUE node. It
 			// will be transformed to an ODOTMETH or ODOTINTER node if
 			// we find in the OCALL case below that the method value
 			// is actually called.
-			transformDot(m.(*ir.SelectorExpr), false)
+			mse := m.(*ir.SelectorExpr)
+			if src := mse.X.Type(); src.IsShape() {
+				// The only dot on a shape type value are methods.
+				if mse.X.Op() == ir.OTYPE {
+					// Method expression T.M
+					m = subst.g.buildClosure2(subst, m, x)
+					// No need for transformDot - buildClosure2 has already
+					// transformed to OCALLINTER/ODOTINTER.
+				} else {
+					// Implement x.M as a conversion-to-bound-interface
+					//  1) convert x to the bound interface
+					//  2) call M on that interface
+					gsrc := x.(*ir.SelectorExpr).X.Type()
+					bound := gsrc.Bound()
+					dst := bound
+					if dst.HasTParam() {
+						dst = subst.ts.Typ(dst)
+					}
+					if src.IsInterface() {
+						// If type arg is an interface (unusual case),
+						// we do a type assert to the type bound.
+						mse.X = assertToBound(subst.info, subst.info.dictParam, m.Pos(), mse.X, bound, dst)
+					} else {
+						mse.X = convertUsingDictionary(subst.info, subst.info.dictParam, m.Pos(), mse.X, x, dst, gsrc)
+					}
+					transformDot(mse, false)
+				}
+			} else {
+				transformDot(mse, false)
+			}
 			m.SetTypecheck(1)
 
 		case ir.OCALL:
@@ -458,9 +1014,11 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			case ir.OTYPE:
 				// Transform the conversion, now that we know the
 				// type argument.
-				m = transformConvCall(m.(*ir.CallExpr))
+				m = transformConvCall(call)
+				// CONVIFACE transformation was already done in node2
+				assert(m.Op() != ir.OCONVIFACE)
 
-			case ir.OCALLPART:
+			case ir.OMETHVALUE, ir.OMETHEXPR:
 				// Redo the transformation of OXDOT, now that we
 				// know the method value is being called. Then
 				// transform the call.
@@ -479,7 +1037,7 @@ func (subst *subster) node(n ir.Node) ir.Node {
 				name := call.X.Name()
 				if name.BuiltinOp != ir.OXXX {
 					switch name.BuiltinOp {
-					case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OLEN, ir.OCAP, ir.OAPPEND:
+					case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.ODELETE, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
 						// Transform these builtins now that we
 						// know the type of the args.
 						m = transformBuiltin(call)
@@ -506,41 +1064,142 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			}
 
 		case ir.OCLOSURE:
+			// We're going to create a new closure from scratch, so clear m
+			// to avoid using the ir.Copy by accident until we reassign it.
+			m = nil
+
 			x := x.(*ir.ClosureExpr)
 			// Need to duplicate x.Func.Nname, x.Func.Dcl, x.Func.ClosureVars, and
 			// x.Func.Body.
 			oldfn := x.Func
-			newfn := ir.NewFunc(oldfn.Pos())
-			if oldfn.ClosureCalled() {
-				newfn.SetClosureCalled(true)
-			}
-			newfn.SetIsHiddenClosure(true)
-			m.(*ir.ClosureExpr).Func = newfn
-			// Closure name can already have brackets, if it derives
-			// from a generic method
-			newsym := makeInstName(oldfn.Nname.Sym(), subst.targs, subst.isMethod)
-			newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), newsym)
-			newfn.Nname.Func = newfn
-			newfn.Nname.Defn = newfn
-			ir.MarkFunc(newfn.Nname)
-			newfn.OClosure = m.(*ir.ClosureExpr)
+			newfn := ir.NewClosureFunc(oldfn.Pos(), subst.newf != nil)
+			ir.NameClosure(newfn.OClosure, subst.newf)
 
 			saveNewf := subst.newf
 			ir.CurFunc = newfn
 			subst.newf = newfn
 			newfn.Dcl = subst.namelist(oldfn.Dcl)
-			newfn.ClosureVars = subst.namelist(oldfn.ClosureVars)
 
-			typed(subst.typ(oldfn.Nname.Type()), newfn.Nname)
-			typed(newfn.Nname.Type(), m)
+			// Make a closure variable for the dictionary of the
+			// containing function.
+			cdict := ir.CaptureName(oldfn.Pos(), newfn, subst.info.dictParam)
+			typed(types.Types[types.TUINTPTR], cdict)
+			ir.FinishCaptureNames(oldfn.Pos(), saveNewf, newfn)
+			newfn.ClosureVars = append(newfn.ClosureVars, subst.namelist(oldfn.ClosureVars)...)
+
+			// Copy that closure variable to a local one.
+			// Note: this allows the dictionary to be captured by child closures.
+			// See issue 47723.
+			ldict := ir.NewNameAt(x.Pos(), subst.info.gf.Sym().Pkg.Lookup(".dict"))
+			typed(types.Types[types.TUINTPTR], ldict)
+			ldict.Class = ir.PAUTO
+			ldict.Curfn = newfn
+			newfn.Dcl = append(newfn.Dcl, ldict)
+			as := ir.NewAssignStmt(x.Pos(), ldict, cdict)
+			as.SetTypecheck(1)
+			newfn.Body.Append(as)
+
+			// Create inst info for the instantiated closure. The dict
+			// param is the closure variable for the dictionary of the
+			// outer function. Since the dictionary is shared, use the
+			// same entries for startSubDict, dictLen, dictEntryMap.
+			cinfo := &instInfo{
+				fun:           newfn,
+				dictParam:     ldict,
+				gf:            subst.info.gf,
+				gfInfo:        subst.info.gfInfo,
+				startSubDict:  subst.info.startSubDict,
+				startItabConv: subst.info.startItabConv,
+				dictLen:       subst.info.dictLen,
+				dictEntryMap:  subst.info.dictEntryMap,
+			}
+			subst.g.instInfoMap[newfn.Nname.Sym()] = cinfo
+
+			typed(subst.ts.Typ(oldfn.Nname.Type()), newfn.Nname)
+			typed(newfn.Nname.Type(), newfn.OClosure)
 			newfn.SetTypecheck(1)
 
+			outerinfo := subst.info
+			subst.info = cinfo
 			// Make sure type of closure function is set before doing body.
-			newfn.Body = subst.list(oldfn.Body)
+			newfn.Body.Append(subst.list(oldfn.Body)...)
+			subst.info = outerinfo
 			subst.newf = saveNewf
 			ir.CurFunc = saveNewf
 
-			subst.g.target.Decls = append(subst.g.target.Decls, newfn)
+			m = ir.UseClosure(newfn.OClosure, subst.g.target)
+			m.(*ir.ClosureExpr).SetInit(subst.list(x.Init()))
+
+		case ir.OCONVIFACE:
+			x := x.(*ir.ConvExpr)
+			// Note: x's argument is still typed as a type parameter.
+			// m's argument now has an instantiated type.
+			if x.X.Type().HasTParam() {
+				m = convertUsingDictionary(subst.info, subst.info.dictParam, m.Pos(), m.(*ir.ConvExpr).X, x, m.Type(), x.X.Type())
+			}
+		case ir.ODOTTYPE, ir.ODOTTYPE2:
+			if !x.Type().HasTParam() {
+				break
+			}
+			dt := m.(*ir.TypeAssertExpr)
+			var rt ir.Node
+			if dt.Type().IsInterface() || dt.X.Type().IsEmptyInterface() {
+				ix := findDictType(subst.info, x.Type())
+				assert(ix >= 0)
+				rt = getDictionaryType(subst.info, subst.info.dictParam, dt.Pos(), ix)
+			} else {
+				// nonempty interface to noninterface. Need an itab.
+				ix := -1
+				for i, ic := range subst.info.gfInfo.itabConvs {
+					if ic == x {
+						ix = subst.info.startItabConv + i
+						break
+					}
+				}
+				assert(ix >= 0)
+				rt = getDictionaryEntry(dt.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
+			}
+			op := ir.ODYNAMICDOTTYPE
+			if x.Op() == ir.ODOTTYPE2 {
+				op = ir.ODYNAMICDOTTYPE2
+			}
+			m = ir.NewDynamicTypeAssertExpr(dt.Pos(), op, dt.X, rt)
+			m.SetType(dt.Type())
+			m.SetTypecheck(1)
+		case ir.OCASE:
+			if _, ok := x.(*ir.CommClause); ok {
+				// This is not a type switch. TODO: Should we use an OSWITCH case here instead of OCASE?
+				break
+			}
+			x := x.(*ir.CaseClause)
+			m := m.(*ir.CaseClause)
+			for i, c := range x.List {
+				if c.Op() == ir.OTYPE && c.Type().HasTParam() {
+					// Use a *runtime._type for the dynamic type.
+					ix := findDictType(subst.info, c.Type())
+					assert(ix >= 0)
+					dt := ir.NewDynamicType(c.Pos(), getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen))
+
+					// For type switch from nonempty interfaces to non-interfaces, we need an itab as well.
+					if !m.List[i].Type().IsInterface() {
+						if _, ok := subst.info.gfInfo.type2switchType[c]; ok {
+							// Type switch from nonempty interface. We need a *runtime.itab
+							// for the dynamic type.
+							ix := -1
+							for i, ic := range subst.info.gfInfo.itabConvs {
+								if ic == c {
+									ix = subst.info.startItabConv + i
+									break
+								}
+							}
+							assert(ix >= 0)
+							dt.ITab = getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
+						}
+					}
+					typed(m.List[i].Type(), dt)
+					m.List[i] = dt
+				}
+			}
 		}
 		return m
 	}
@@ -548,10 +1207,78 @@ func (subst *subster) node(n ir.Node) ir.Node {
 	return edit(n)
 }
 
+// findDictType looks for type t in the typeparams or derived types in the generic
+// function info.gfInfo. This will indicate the dictionary entry with the
+// correct concrete type for the associated instantiated function.
+func findDictType(info *instInfo, t *types.Type) int {
+	for i, dt := range info.gfInfo.tparams {
+		if dt == t {
+			return i
+		}
+	}
+	for i, dt := range info.gfInfo.derivedTypes {
+		if types.Identical(dt, t) {
+			return i + len(info.gfInfo.tparams)
+		}
+	}
+	return -1
+}
+
+// convertUsingDictionary converts value v from instantiated type src to an interface
+// type dst, by returning a new set of nodes that make use of a dictionary entry. src
+// is the generic (not shape) type, and gn is the original generic node of the
+// CONVIFACE node or XDOT node (for a bound method call) that is causing the
+// conversion.
+func convertUsingDictionary(info *instInfo, dictParam *ir.Name, pos src.XPos, v ir.Node, gn ir.Node, dst, src *types.Type) ir.Node {
+	assert(src.HasTParam())
+	assert(dst.IsInterface())
+
+	var rt ir.Node
+	if !dst.IsEmptyInterface() {
+		// We should have an itab entry in the dictionary. Using this itab
+		// will be more efficient than converting to an empty interface first
+		// and then type asserting to dst.
+		ix := -1
+		for i, ic := range info.gfInfo.itabConvs {
+			if ic == gn {
+				ix = info.startItabConv + i
+				break
+			}
+		}
+		assert(ix >= 0)
+		rt = getDictionaryEntry(pos, dictParam, ix, info.dictLen)
+	} else if v.Type().IsInterface() {
+		ta := ir.NewTypeAssertExpr(pos, v, nil)
+		ta.SetType(dst)
+		ta.SetTypecheck(1)
+		return ta
+	} else {
+		ix := findDictType(info, src)
+		assert(ix >= 0)
+		// Load the actual runtime._type of the type parameter from the dictionary.
+		rt = getDictionaryType(info, dictParam, pos, ix)
+	}
+
+	// Figure out what the data field of the interface will be.
+	var data ir.Node
+	if v.Type().IsInterface() {
+		data = ir.NewUnaryExpr(pos, ir.OIDATA, v)
+	} else {
+		data = ir.NewConvExpr(pos, ir.OCONVIDATA, nil, v)
+	}
+	typed(types.Types[types.TUNSAFEPTR], data)
+
+	// Build an interface from the type and data parts.
+	var i ir.Node = ir.NewBinaryExpr(pos, ir.OEFACE, rt, data)
+	typed(dst, i)
+	return i
+
+}
+
 func (subst *subster) namelist(l []*ir.Name) []*ir.Name {
 	s := make([]*ir.Name, len(l))
 	for i, n := range l {
-		s[i] = subst.node(n).(*ir.Name)
+		s[i] = subst.localvar(n)
 		if n.Defn != nil {
 			s[i].Defn = subst.node(n.Defn)
 		}
@@ -570,348 +1297,706 @@ func (subst *subster) list(l []ir.Node) []ir.Node {
 	return s
 }
 
-// tstruct substitutes type params in types of the fields of a structure type. For
-// each field, if Nname is set, tstruct also translates the Nname using
-// subst.vars, if Nname is in subst.vars. To always force the creation of a new
-// (top-level) struct, regardless of whether anything changed with the types or
-// names of the struct's fields, set force to true.
-func (subst *subster) tstruct(t *types.Type, force bool) *types.Type {
-	if t.NumFields() == 0 {
-		if t.HasTParam() {
-			// For an empty struct, we need to return a new type,
-			// since it may now be fully instantiated (HasTParam
-			// becomes false).
-			return types.NewStruct(t.Pkg(), nil)
-		}
-		return t
-	}
-	var newfields []*types.Field
-	if force {
-		newfields = make([]*types.Field, t.NumFields())
-	}
-	for i, f := range t.Fields().Slice() {
-		t2 := subst.typ(f.Type)
-		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
-			newfields = make([]*types.Field, t.NumFields())
-			for j := 0; j < i; j++ {
-				newfields[j] = t.Field(j)
-			}
-		}
-		if newfields != nil {
-			// TODO(danscales): make sure this works for the field
-			// names of embedded types (which should keep the name of
-			// the type param, not the instantiated type).
-			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
-			if f.Nname != nil {
-				// f.Nname may not be in subst.vars[] if this is
-				// a function name or a function instantiation type
-				// that we are translating
-				v := subst.vars[f.Nname.(*ir.Name)]
-				// Be careful not to put a nil var into Nname,
-				// since Nname is an interface, so it would be a
-				// non-nil interface.
-				if v != nil {
-					newfields[i].Nname = v
-				}
-			}
+// fields sets the Nname field for the Field nodes inside a type signature, based
+// on the corresponding in/out parameters in dcl. It depends on the in and out
+// parameters being in order in dcl.
+func (subst *subster) fields(class ir.Class, oldfields []*types.Field, dcl []*ir.Name) []*types.Field {
+	// Find the starting index in dcl of declarations of the class (either
+	// PPARAM or PPARAMOUT).
+	var i int
+	for i = range dcl {
+		if dcl[i].Class == class {
+			break
 		}
 	}
-	if newfields != nil {
-		return types.NewStruct(t.Pkg(), newfields)
+
+	// Create newfields nodes that are copies of the oldfields nodes, but
+	// with substitution for any type params, and with Nname set to be the node in
+	// Dcl for the corresponding PPARAM or PPARAMOUT.
+	newfields := make([]*types.Field, len(oldfields))
+	for j := range oldfields {
+		newfields[j] = oldfields[j].Copy()
+		newfields[j].Type = subst.ts.Typ(oldfields[j].Type)
+		// A PPARAM field will be missing from dcl if its name is
+		// unspecified or specified as "_". So, we compare the dcl sym
+		// with the field sym (or sym of the field's Nname node). (Unnamed
+		// results still have a name like ~r2 in their Nname node.) If
+		// they don't match, this dcl (if there is one left) must apply to
+		// a later field.
+		if i < len(dcl) && (dcl[i].Sym() == oldfields[j].Sym ||
+			(oldfields[j].Nname != nil && dcl[i].Sym() == oldfields[j].Nname.Sym())) {
+			newfields[j].Nname = dcl[i]
+			i++
+		}
+	}
+	return newfields
+}
+
+// deref does a single deref of type t, if it is a pointer type.
+func deref(t *types.Type) *types.Type {
+	if t.IsPtr() {
+		return t.Elem()
 	}
 	return t
+}
 
+// markTypeUsed marks type t as used in order to help avoid dead-code elimination of
+// needed methods.
+func markTypeUsed(t *types.Type, lsym *obj.LSym) {
+	if t.IsInterface() {
+		// Mark all the methods of the interface as used.
+		// TODO: we should really only mark the interface methods
+		// that are actually called in the application.
+		for i, _ := range t.AllMethods().Slice() {
+			reflectdata.MarkUsedIfaceMethodIndex(lsym, t, i)
+		}
+	} else {
+		// TODO: This is somewhat overkill, we really only need it
+		// for types that are put into interfaces.
+		reflectdata.MarkTypeUsedInInterface(t, lsym)
+	}
 }
 
-// tinter substitutes type params in types of the methods of an interface type.
-func (subst *subster) tinter(t *types.Type) *types.Type {
-	if t.Methods().Len() == 0 {
-		return t
+// getDictionarySym returns the dictionary for the named generic function gf, which
+// is instantiated with the type arguments targs.
+func (g *irgen) getDictionarySym(gf *ir.Name, targs []*types.Type, isMeth bool) *types.Sym {
+	if len(targs) == 0 {
+		base.Fatalf("%s should have type arguments", gf.Sym().Name)
+	}
+
+	// Enforce that only concrete types can make it to here.
+	for _, t := range targs {
+		if t.HasShape() {
+			panic(fmt.Sprintf("shape %+v in dictionary for %s", t, gf.Sym().Name))
+		}
+	}
+
+	// Get a symbol representing the dictionary.
+	sym := typecheck.MakeDictSym(gf.Sym(), targs, isMeth)
+
+	// Initialize the dictionary, if we haven't yet already.
+	lsym := sym.Linksym()
+	if len(lsym.P) > 0 {
+		// We already started creating this dictionary and its lsym.
+		return sym
+	}
+
+	info := g.getGfInfo(gf)
+
+	infoPrint("=== Creating dictionary %v\n", sym.Name)
+	off := 0
+	// Emit an entry for each targ (concrete type or gcshape).
+	for _, t := range targs {
+		infoPrint(" * %v\n", t)
+		s := reflectdata.TypeLinksym(t)
+		off = objw.SymPtr(lsym, off, s, 0)
+		markTypeUsed(t, lsym)
+	}
+	subst := typecheck.Tsubster{
+		Tparams: info.tparams,
+		Targs:   targs,
 	}
-	var newfields []*types.Field
-	for i, f := range t.Methods().Slice() {
-		t2 := subst.typ(f.Type)
-		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
-			newfields = make([]*types.Field, t.Methods().Len())
-			for j := 0; j < i; j++ {
-				newfields[j] = t.Methods().Index(j)
+	// Emit an entry for each derived type (after substituting targs)
+	for _, t := range info.derivedTypes {
+		ts := subst.Typ(t)
+		infoPrint(" - %v\n", ts)
+		s := reflectdata.TypeLinksym(ts)
+		off = objw.SymPtr(lsym, off, s, 0)
+		markTypeUsed(ts, lsym)
+	}
+	// Emit an entry for each subdictionary (after substituting targs)
+	for _, n := range info.subDictCalls {
+		var sym *types.Sym
+		switch n.Op() {
+		case ir.OCALL:
+			call := n.(*ir.CallExpr)
+			if call.X.Op() == ir.OXDOT {
+				var nameNode *ir.Name
+				se := call.X.(*ir.SelectorExpr)
+				if types.IsInterfaceMethod(se.Selection.Type) {
+					// This is a method call enabled by a type bound.
+					tmpse := ir.NewSelectorExpr(base.Pos, ir.OXDOT, se.X, se.Sel)
+					tmpse = typecheck.AddImplicitDots(tmpse)
+					tparam := tmpse.X.Type()
+					assert(tparam.IsTypeParam())
+					recvType := targs[tparam.Index()]
+					if recvType.IsInterface() || len(recvType.RParams()) == 0 {
+						// No sub-dictionary entry is
+						// actually needed, since the
+						// type arg is not an
+						// instantiated type that
+						// will have generic methods.
+						break
+					}
+					// This is a method call for an
+					// instantiated type, so we need a
+					// sub-dictionary.
+					targs := recvType.RParams()
+					genRecvType := recvType.OrigSym.Def.Type()
+					nameNode = typecheck.Lookdot1(call.X, se.Sel, genRecvType, genRecvType.Methods(), 1).Nname.(*ir.Name)
+					sym = g.getDictionarySym(nameNode, targs, true)
+				} else {
+					// This is the case of a normal
+					// method call on a generic type.
+					nameNode = call.X.(*ir.SelectorExpr).Selection.Nname.(*ir.Name)
+					subtargs := deref(call.X.(*ir.SelectorExpr).X.Type()).RParams()
+					s2targs := make([]*types.Type, len(subtargs))
+					for i, t := range subtargs {
+						s2targs[i] = subst.Typ(t)
+					}
+					sym = g.getDictionarySym(nameNode, s2targs, true)
+				}
+			} else {
+				inst := call.X.(*ir.InstExpr)
+				var nameNode *ir.Name
+				var meth *ir.SelectorExpr
+				var isMeth bool
+				if meth, isMeth = inst.X.(*ir.SelectorExpr); isMeth {
+					nameNode = meth.Selection.Nname.(*ir.Name)
+				} else {
+					nameNode = inst.X.(*ir.Name)
+				}
+				subtargs := typecheck.TypesOf(inst.Targs)
+				for i, t := range subtargs {
+					subtargs[i] = subst.Typ(t)
+				}
+				sym = g.getDictionarySym(nameNode, subtargs, isMeth)
 			}
+
+		case ir.OFUNCINST:
+			inst := n.(*ir.InstExpr)
+			nameNode := inst.X.(*ir.Name)
+			subtargs := typecheck.TypesOf(inst.Targs)
+			for i, t := range subtargs {
+				subtargs[i] = subst.Typ(t)
+			}
+			sym = g.getDictionarySym(nameNode, subtargs, false)
+
+		case ir.OXDOT:
+			selExpr := n.(*ir.SelectorExpr)
+			subtargs := deref(selExpr.X.Type()).RParams()
+			s2targs := make([]*types.Type, len(subtargs))
+			for i, t := range subtargs {
+				s2targs[i] = subst.Typ(t)
+			}
+			nameNode := selExpr.Selection.Nname.(*ir.Name)
+			sym = g.getDictionarySym(nameNode, s2targs, true)
+
+		default:
+			assert(false)
 		}
-		if newfields != nil {
-			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+
+		if sym == nil {
+			// Unused sub-dictionary entry, just emit 0.
+			off = objw.Uintptr(lsym, off, 0)
+			infoPrint(" - Unused subdict entry\n")
+		} else {
+			off = objw.SymPtr(lsym, off, sym.Linksym(), 0)
+			infoPrint(" - Subdict %v\n", sym.Name)
 		}
 	}
-	if newfields != nil {
-		return types.NewInterface(t.Pkg(), newfields)
+
+	delay := &delayInfo{
+		gf:    gf,
+		targs: targs,
+		sym:   sym,
+		off:   off,
 	}
-	return t
+	g.dictSymsToFinalize = append(g.dictSymsToFinalize, delay)
+	g.instTypeList = append(g.instTypeList, subst.InstTypeList...)
+	return sym
 }
 
-// instTypeName creates a name for an instantiated type, based on the name of the
-// generic type and the type args
-func instTypeName(name string, targs []*types.Type) string {
-	b := bytes.NewBufferString(name)
-	b.WriteByte('[')
-	for i, targ := range targs {
-		if i > 0 {
-			b.WriteByte(',')
-		}
-		b.WriteString(targ.String())
-	}
-	b.WriteByte(']')
-	return b.String()
-}
-
-// typ computes the type obtained by substituting any type parameter in t with the
-// corresponding type argument in subst. If t contains no type parameters, the
-// result is t; otherwise the result is a new type. It deals with recursive types
-// by using TFORW types and finding partially or fully created types via sym.Def.
-func (subst *subster) typ(t *types.Type) *types.Type {
-	if !t.HasTParam() && t.Kind() != types.TFUNC {
-		// Note: function types need to be copied regardless, as the
-		// types of closures may contain declarations that need
-		// to be copied. See #45738.
-		return t
-	}
-
-	if t.Kind() == types.TTYPEPARAM {
-		for i, tp := range subst.tparams {
-			if tp.Type == t {
-				return subst.targs[i].Type()
-			}
-		}
-		// If t is a simple typeparam T, then t has the name/symbol 'T'
-		// and t.Underlying() == t.
-		//
-		// However, consider the type definition: 'type P[T any] T'. We
-		// might use this definition so we can have a variant of type T
-		// that we can add new methods to. Suppose t is a reference to
-		// P[T]. t has the name 'P[T]', but its kind is TTYPEPARAM,
-		// because P[T] is defined as T. If we look at t.Underlying(), it
-		// is different, because the name of t.Underlying() is 'T' rather
-		// than 'P[T]'. But the kind of t.Underlying() is also TTYPEPARAM.
-		// In this case, we do the needed recursive substitution in the
-		// case statement below.
-		if t.Underlying() == t {
-			// t is a simple typeparam that didn't match anything in tparam
-			return t
-		}
-		// t is a more complex typeparam (e.g. P[T], as above, whose
-		// definition is just T).
-		assert(t.Sym() != nil)
-	}
-
-	var newsym *types.Sym
-	var neededTargs []*types.Type
-	var forw *types.Type
-
-	if t.Sym() != nil {
-		// Translate the type params for this type according to
-		// the tparam/targs mapping from subst.
-		neededTargs = make([]*types.Type, len(t.RParams()))
-		for i, rparam := range t.RParams() {
-			neededTargs[i] = subst.typ(rparam)
-		}
-		// For a named (defined) type, we have to change the name of the
-		// type as well. We do this first, so we can look up if we've
-		// already seen this type during this substitution or other
-		// definitions/substitutions.
-		genName := genericTypeName(t.Sym())
-		newsym = t.Sym().Pkg.Lookup(instTypeName(genName, neededTargs))
-		if newsym.Def != nil {
-			// We've already created this instantiated defined type.
-			return newsym.Def.Type()
-		}
-
-		// In order to deal with recursive generic types, create a TFORW
-		// type initially and set the Def field of its sym, so it can be
-		// found if this type appears recursively within the type.
-		forw = newIncompleteNamedType(t.Pos(), newsym)
-		//println("Creating new type by sub", newsym.Name, forw.HasTParam())
-		forw.SetRParams(neededTargs)
-	}
-
-	var newt *types.Type
+// finalizeSyms finishes up all dictionaries on g.dictSymsToFinalize, by writing out
+// any needed LSyms for itabs. The itab lsyms create wrappers which need various
+// dictionaries and method instantiations to be complete, so, to avoid recursive
+// dependencies, we finalize the itab lsyms only after all dictionaries syms and
+// instantiations have been created.
+func (g *irgen) finalizeSyms() {
+	for _, d := range g.dictSymsToFinalize {
+		infoPrint("=== Finalizing dictionary %s\n", d.sym.Name)
+
+		lsym := d.sym.Linksym()
+		info := g.getGfInfo(d.gf)
+
+		subst := typecheck.Tsubster{
+			Tparams: info.tparams,
+			Targs:   d.targs,
+		}
 
-	switch t.Kind() {
-	case types.TTYPEPARAM:
-		if t.Sym() == newsym {
-			// The substitution did not change the type.
-			return t
+		// Emit an entry for each itab
+		for _, n := range info.itabConvs {
+			var srctype, dsttype *types.Type
+			switch n.Op() {
+			case ir.OXDOT:
+				se := n.(*ir.SelectorExpr)
+				srctype = subst.Typ(se.X.Type())
+				dsttype = subst.Typ(se.X.Type().Bound())
+				found := false
+				for i, m := range dsttype.AllMethods().Slice() {
+					if se.Sel == m.Sym {
+						// Mark that this method se.Sel is
+						// used for the dsttype interface, so
+						// it won't get deadcoded.
+						reflectdata.MarkUsedIfaceMethodIndex(lsym, dsttype, i)
+						found = true
+						break
+					}
+				}
+				assert(found)
+			case ir.ODOTTYPE, ir.ODOTTYPE2:
+				srctype = subst.Typ(n.(*ir.TypeAssertExpr).Type())
+				dsttype = subst.Typ(n.(*ir.TypeAssertExpr).X.Type())
+			case ir.OCONVIFACE:
+				srctype = subst.Typ(n.(*ir.ConvExpr).X.Type())
+				dsttype = subst.Typ(n.Type())
+			case ir.OTYPE:
+				srctype = subst.Typ(n.Type())
+				dsttype = subst.Typ(info.type2switchType[n])
+			default:
+				base.Fatalf("itab entry with unknown op %s", n.Op())
+			}
+			if srctype.IsInterface() {
+				// No itab is wanted if src type is an interface. We
+				// will use a type assert instead.
+				d.off = objw.Uintptr(lsym, d.off, 0)
+				infoPrint(" + Unused itab entry for %v\n", srctype)
+			} else {
+				itabLsym := reflectdata.ITabLsym(srctype, dsttype)
+				d.off = objw.SymPtr(lsym, d.off, itabLsym, 0)
+				infoPrint(" + Itab for (%v,%v)\n", srctype, dsttype)
+			}
 		}
-		// Substitute the underlying typeparam (e.g. T in P[T], see
-		// the example describing type P[T] above).
-		newt = subst.typ(t.Underlying())
-		assert(newt != t)
 
-	case types.TARRAY:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewArray(newelem, t.NumElem())
+		objw.Global(lsym, int32(d.off), obj.DUPOK|obj.RODATA)
+		infoPrint("=== Finalized dictionary %s\n", d.sym.Name)
+
+		g.instTypeList = append(g.instTypeList, subst.InstTypeList...)
+	}
+	g.dictSymsToFinalize = nil
+}
+
+func (g *irgen) getDictionaryValue(gf *ir.Name, targs []*types.Type, isMeth bool) ir.Node {
+	sym := g.getDictionarySym(gf, targs, isMeth)
+
+	// Make (or reuse) a node referencing the dictionary symbol.
+	var n *ir.Name
+	if sym.Def != nil {
+		n = sym.Def.(*ir.Name)
+	} else {
+		n = typecheck.NewName(sym)
+		n.SetType(types.Types[types.TUINTPTR]) // should probably be [...]uintptr, but doesn't really matter
+		n.SetTypecheck(1)
+		n.Class = ir.PEXTERN
+		sym.Def = n
+	}
+
+	// Return the address of the dictionary.
+	np := typecheck.NodAddr(n)
+	// Note: treat dictionary pointers as uintptrs, so they aren't pointers
+	// with respect to GC. That saves on stack scanning work, write barriers, etc.
+	// We can get away with it because dictionaries are global variables.
+	// TODO: use a cast, or is typing directly ok?
+	np.SetType(types.Types[types.TUINTPTR])
+	np.SetTypecheck(1)
+	return np
+}
+
+// hasTParamNodes returns true if the type of any node in targs has a typeparam.
+func hasTParamNodes(targs []ir.Node) bool {
+	for _, n := range targs {
+		if n.Type().HasTParam() {
+			return true
 		}
+	}
+	return false
+}
+
+// hasTParamNodes returns true if any type in targs has a typeparam.
+func hasTParamTypes(targs []*types.Type) bool {
+	for _, t := range targs {
+		if t.HasTParam() {
+			return true
+		}
+	}
+	return false
+}
 
-	case types.TPTR:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewPtr(newelem)
+// getGfInfo get information for a generic function - type params, derived generic
+// types, and subdictionaries.
+func (g *irgen) getGfInfo(gn *ir.Name) *gfInfo {
+	infop := g.gfInfoMap[gn.Sym()]
+	if infop != nil {
+		return infop
+	}
+
+	checkFetchBody(gn)
+	var info gfInfo
+	gf := gn.Func
+	recv := gf.Type().Recv()
+	if recv != nil {
+		info.tparams = deref(recv.Type).RParams()
+	} else {
+		tparams := gn.Type().TParams().FieldSlice()
+		info.tparams = make([]*types.Type, len(tparams))
+		for i, f := range tparams {
+			info.tparams[i] = f.Type
 		}
+	}
 
-	case types.TSLICE:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewSlice(newelem)
+	for _, t := range info.tparams {
+		b := t.Bound()
+		if b.HasTParam() {
+			// If a type bound is parameterized (unusual case), then we
+			// may need its derived type to do a type assert when doing a
+			// bound call for a type arg that is an interface.
+			addType(&info, nil, b)
 		}
+	}
 
-	case types.TSTRUCT:
-		newt = subst.tstruct(t, false)
-		if newt == t {
-			newt = nil
+	for _, n := range gf.Dcl {
+		addType(&info, n, n.Type())
+	}
+
+	if infoPrintMode {
+		fmt.Printf(">>> GfInfo for %v\n", gn)
+		for _, t := range info.tparams {
+			fmt.Printf("  Typeparam %v\n", t)
 		}
+	}
 
-	case types.TFUNC:
-		newrecvs := subst.tstruct(t.Recvs(), false)
-		newparams := subst.tstruct(t.Params(), false)
-		newresults := subst.tstruct(t.Results(), false)
-		if newrecvs != t.Recvs() || newparams != t.Params() || newresults != t.Results() {
-			// If any types have changed, then the all the fields of
-			// of recv, params, and results must be copied, because they have
-			// offset fields that are dependent, and so must have an
-			// independent copy for each new signature.
-			var newrecv *types.Field
-			if newrecvs.NumFields() > 0 {
-				if newrecvs == t.Recvs() {
-					newrecvs = subst.tstruct(t.Recvs(), true)
+	var visitFunc func(ir.Node)
+	visitFunc = func(n ir.Node) {
+		if n.Op() == ir.OFUNCINST && !n.(*ir.InstExpr).Implicit() {
+			if hasTParamNodes(n.(*ir.InstExpr).Targs) {
+				infoPrint("  Closure&subdictionary required at generic function value %v\n", n.(*ir.InstExpr).X)
+				info.subDictCalls = append(info.subDictCalls, n)
+			}
+		} else if n.Op() == ir.OXDOT && !n.(*ir.SelectorExpr).Implicit() &&
+			n.(*ir.SelectorExpr).Selection != nil &&
+			len(deref(n.(*ir.SelectorExpr).X.Type()).RParams()) > 0 {
+			if hasTParamTypes(deref(n.(*ir.SelectorExpr).X.Type()).RParams()) {
+				if n.(*ir.SelectorExpr).X.Op() == ir.OTYPE {
+					infoPrint("  Closure&subdictionary required at generic meth expr %v\n", n)
+				} else {
+					infoPrint("  Closure&subdictionary required at generic meth value %v\n", n)
 				}
-				newrecv = newrecvs.Field(0)
+				info.subDictCalls = append(info.subDictCalls, n)
 			}
-			if newparams == t.Params() {
-				newparams = subst.tstruct(t.Params(), true)
+		}
+		if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OFUNCINST {
+			n.(*ir.CallExpr).X.(*ir.InstExpr).SetImplicit(true)
+			if hasTParamNodes(n.(*ir.CallExpr).X.(*ir.InstExpr).Targs) {
+				infoPrint("  Subdictionary at generic function/method call: %v - %v\n", n.(*ir.CallExpr).X.(*ir.InstExpr).X, n)
+				info.subDictCalls = append(info.subDictCalls, n)
 			}
-			if newresults == t.Results() {
-				newresults = subst.tstruct(t.Results(), true)
+		}
+		if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OXDOT &&
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).Selection != nil &&
+			len(deref(n.(*ir.CallExpr).X.(*ir.SelectorExpr).X.Type()).RParams()) > 0 {
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).SetImplicit(true)
+			if hasTParamTypes(deref(n.(*ir.CallExpr).X.(*ir.SelectorExpr).X.Type()).RParams()) {
+				infoPrint("  Subdictionary at generic method call: %v\n", n)
+				info.subDictCalls = append(info.subDictCalls, n)
 			}
-			newt = types.NewSignature(t.Pkg(), newrecv, t.TParams().FieldSlice(), newparams.FieldSlice(), newresults.FieldSlice())
 		}
-
-	case types.TINTER:
-		newt = subst.tinter(t)
-		if newt == t {
-			newt = nil
+		if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OXDOT &&
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).Selection != nil &&
+			deref(n.(*ir.CallExpr).X.(*ir.SelectorExpr).X.Type()).IsTypeParam() {
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).SetImplicit(true)
+			infoPrint("  Optional subdictionary at generic bound call: %v\n", n)
+			info.subDictCalls = append(info.subDictCalls, n)
 		}
-
-	case types.TMAP:
-		newkey := subst.typ(t.Key())
-		newval := subst.typ(t.Elem())
-		if newkey != t.Key() || newval != t.Elem() {
-			newt = types.NewMap(newkey, newval)
-		}
-
-	case types.TCHAN:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewChan(newelem, t.ChanDir())
-			if !newt.HasTParam() {
-				// TODO(danscales): not sure why I have to do this
-				// only for channels.....
-				types.CheckSize(newt)
-			}
-		}
-	}
-	if newt == nil {
-		// Even though there were typeparams in the type, there may be no
-		// change if this is a function type for a function call (which will
-		// have its own tparams/targs in the function instantiation).
-		return t
-	}
-
-	if t.Sym() == nil {
-		// Not a named type, so there was no forwarding type and there are
-		// no methods to substitute.
-		assert(t.Methods().Len() == 0)
-		return newt
-	}
-
-	forw.SetUnderlying(newt)
-	newt = forw
-
-	if t.Kind() != types.TINTER && t.Methods().Len() > 0 {
-		// Fill in the method info for the new type.
-		var newfields []*types.Field
-		newfields = make([]*types.Field, t.Methods().Len())
-		for i, f := range t.Methods().Slice() {
-			t2 := subst.typ(f.Type)
-			oldsym := f.Nname.Sym()
-			newsym := makeInstName(oldsym, subst.targs, true)
-			var nname *ir.Name
-			if newsym.Def != nil {
-				nname = newsym.Def.(*ir.Name)
-			} else {
-				nname = ir.NewNameAt(f.Pos, newsym)
-				nname.SetType(t2)
-				newsym.Def = nname
+		if n.Op() == ir.OCONVIFACE && n.Type().IsInterface() &&
+			!n.Type().IsEmptyInterface() &&
+			n.(*ir.ConvExpr).X.Type().HasTParam() {
+			infoPrint("  Itab for interface conv: %v\n", n)
+			info.itabConvs = append(info.itabConvs, n)
+		}
+		if n.Op() == ir.OXDOT && n.(*ir.SelectorExpr).X.Type().IsTypeParam() {
+			infoPrint("  Itab for bound call: %v\n", n)
+			info.itabConvs = append(info.itabConvs, n)
+		}
+		if (n.Op() == ir.ODOTTYPE || n.Op() == ir.ODOTTYPE2) && !n.(*ir.TypeAssertExpr).Type().IsInterface() && !n.(*ir.TypeAssertExpr).X.Type().IsEmptyInterface() {
+			infoPrint("  Itab for dot type: %v\n", n)
+			info.itabConvs = append(info.itabConvs, n)
+		}
+		if n.Op() == ir.OCLOSURE {
+			// Visit the closure body and add all relevant entries to the
+			// dictionary of the outer function (closure will just use
+			// the dictionary of the outer function).
+			for _, n1 := range n.(*ir.ClosureExpr).Func.Body {
+				ir.Visit(n1, visitFunc)
 			}
-			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
-			newfields[i].Nname = nname
 		}
-		newt.Methods().Set(newfields)
-		if !newt.HasTParam() {
-			// Generate all the methods for a new fully-instantiated type.
-			subst.g.instTypeList = append(subst.g.instTypeList, newt)
+		if n.Op() == ir.OSWITCH && n.(*ir.SwitchStmt).Tag != nil && n.(*ir.SwitchStmt).Tag.Op() == ir.OTYPESW && !n.(*ir.SwitchStmt).Tag.(*ir.TypeSwitchGuard).X.Type().IsEmptyInterface() {
+			for _, cc := range n.(*ir.SwitchStmt).Cases {
+				for _, c := range cc.List {
+					if c.Op() == ir.OTYPE && c.Type().HasTParam() {
+						// Type switch from a non-empty interface - might need an itab.
+						infoPrint("  Itab for type switch: %v\n", c)
+						info.itabConvs = append(info.itabConvs, c)
+						if info.type2switchType == nil {
+							info.type2switchType = map[ir.Node]*types.Type{}
+						}
+						info.type2switchType[c] = n.(*ir.SwitchStmt).Tag.(*ir.TypeSwitchGuard).X.Type()
+					}
+				}
+			}
+		}
+		addType(&info, n, n.Type())
+	}
+
+	for _, stmt := range gf.Body {
+		ir.Visit(stmt, visitFunc)
+	}
+	if infoPrintMode {
+		for _, t := range info.derivedTypes {
+			fmt.Printf("  Derived type %v\n", t)
 		}
+		fmt.Printf(">>> Done Gfinfo\n")
 	}
-	return newt
+	g.gfInfoMap[gn.Sym()] = &info
+	return &info
 }
 
-// fields sets the Nname field for the Field nodes inside a type signature, based
-// on the corresponding in/out parameters in dcl. It depends on the in and out
-// parameters being in order in dcl.
-func (subst *subster) fields(class ir.Class, oldfields []*types.Field, dcl []*ir.Name) []*types.Field {
-	// Find the starting index in dcl of declarations of the class (either
-	// PPARAM or PPARAMOUT).
-	var i int
-	for i = range dcl {
-		if dcl[i].Class == class {
-			break
+// addType adds t to info.derivedTypes if it is parameterized type (which is not
+// just a simple type param) that is different from any existing type on
+// info.derivedTypes.
+func addType(info *gfInfo, n ir.Node, t *types.Type) {
+	if t == nil || !t.HasTParam() {
+		return
+	}
+	if t.IsTypeParam() && t.Underlying() == t {
+		return
+	}
+	if t.Kind() == types.TFUNC && n != nil &&
+		(t.Recv() != nil ||
+			n.Op() == ir.ONAME && n.Name().Class == ir.PFUNC) {
+		// Don't use the type of a named generic function or method,
+		// since that is parameterized by other typeparams.
+		// (They all come from arguments of a FUNCINST node.)
+		return
+	}
+	if doubleCheck && !parameterizedBy(t, info.tparams) {
+		base.Fatalf("adding type with invalid parameters %+v", t)
+	}
+	if t.Kind() == types.TSTRUCT && t.IsFuncArgStruct() {
+		// Multiple return values are not a relevant new type (?).
+		return
+	}
+	// Ignore a derived type we've already added.
+	for _, et := range info.derivedTypes {
+		if types.Identical(t, et) {
+			return
 		}
 	}
+	info.derivedTypes = append(info.derivedTypes, t)
+}
 
-	// Create newfields nodes that are copies of the oldfields nodes, but
-	// with substitution for any type params, and with Nname set to be the node in
-	// Dcl for the corresponding PPARAM or PPARAMOUT.
-	newfields := make([]*types.Field, len(oldfields))
-	for j := range oldfields {
-		newfields[j] = oldfields[j].Copy()
-		newfields[j].Type = subst.typ(oldfields[j].Type)
-		// A param field will be missing from dcl if its name is
-		// unspecified or specified as "_". So, we compare the dcl sym
-		// with the field sym. If they don't match, this dcl (if there is
-		// one left) must apply to a later field.
-		if i < len(dcl) && dcl[i].Sym() == oldfields[j].Sym {
-			newfields[j].Nname = dcl[i]
-			i++
+// parameterizedBy returns true if t is parameterized by (at most) params.
+func parameterizedBy(t *types.Type, params []*types.Type) bool {
+	return parameterizedBy1(t, params, map[*types.Type]bool{})
+}
+func parameterizedBy1(t *types.Type, params []*types.Type, visited map[*types.Type]bool) bool {
+	if visited[t] {
+		return true
+	}
+	visited[t] = true
+
+	if t.Sym() != nil && len(t.RParams()) > 0 {
+		// This defined type is instantiated. Check the instantiating types.
+		for _, r := range t.RParams() {
+			if !parameterizedBy1(r, params, visited) {
+				return false
+			}
 		}
+		return true
+	}
+	switch t.Kind() {
+	case types.TTYPEPARAM:
+		// Check if t is one of the allowed parameters in scope.
+		for _, p := range params {
+			if p == t {
+				return true
+			}
+		}
+		// Couldn't find t in the list of allowed parameters.
+		return false
+
+	case types.TARRAY, types.TPTR, types.TSLICE, types.TCHAN:
+		return parameterizedBy1(t.Elem(), params, visited)
+
+	case types.TMAP:
+		return parameterizedBy1(t.Key(), params, visited) && parameterizedBy1(t.Elem(), params, visited)
+
+	case types.TFUNC:
+		return parameterizedBy1(t.TParams(), params, visited) && parameterizedBy1(t.Recvs(), params, visited) && parameterizedBy1(t.Params(), params, visited) && parameterizedBy1(t.Results(), params, visited)
+
+	case types.TSTRUCT:
+		for _, f := range t.Fields().Slice() {
+			if !parameterizedBy1(f.Type, params, visited) {
+				return false
+			}
+		}
+		return true
+
+	case types.TINTER:
+		for _, f := range t.Methods().Slice() {
+			if !parameterizedBy1(f.Type, params, visited) {
+				return false
+			}
+		}
+		return true
+
+	case types.TINT, types.TINT8, types.TINT16, types.TINT32, types.TINT64,
+		types.TUINT, types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64,
+		types.TUINTPTR, types.TBOOL, types.TSTRING, types.TFLOAT32, types.TFLOAT64, types.TCOMPLEX64, types.TCOMPLEX128:
+		return true
+
+	case types.TUNION:
+		for i := 0; i < t.NumTerms(); i++ {
+			tt, _ := t.Term(i)
+			if !parameterizedBy1(tt, params, visited) {
+				return false
+			}
+		}
+		return true
+
+	default:
+		base.Fatalf("bad type kind %+v", t)
+		return true
 	}
-	return newfields
 }
 
-// defer does a single defer of type t, if it is a pointer type.
-func deref(t *types.Type) *types.Type {
-	if t.IsPtr() {
-		return t.Elem()
+// startClosures starts creation of a closure that has the function type typ. It
+// creates all the formal params and results according to the type typ. On return,
+// the body and closure variables of the closure must still be filled in, and
+// ir.UseClosure() called.
+func startClosure(pos src.XPos, outer *ir.Func, typ *types.Type) (*ir.Func, []*types.Field, []*types.Field) {
+	// Make a new internal function.
+	fn := ir.NewClosureFunc(pos, outer != nil)
+	ir.NameClosure(fn.OClosure, outer)
+
+	// Build formal argument and return lists.
+	var formalParams []*types.Field  // arguments of closure
+	var formalResults []*types.Field // returns of closure
+	for i := 0; i < typ.NumParams(); i++ {
+		t := typ.Params().Field(i).Type
+		arg := ir.NewNameAt(pos, typecheck.LookupNum("a", i))
+		arg.Class = ir.PPARAM
+		typed(t, arg)
+		arg.Curfn = fn
+		fn.Dcl = append(fn.Dcl, arg)
+		f := types.NewField(pos, arg.Sym(), t)
+		f.Nname = arg
+		formalParams = append(formalParams, f)
 	}
-	return t
+	for i := 0; i < typ.NumResults(); i++ {
+		t := typ.Results().Field(i).Type
+		result := ir.NewNameAt(pos, typecheck.LookupNum("r", i)) // TODO: names not needed?
+		result.Class = ir.PPARAMOUT
+		typed(t, result)
+		result.Curfn = fn
+		fn.Dcl = append(fn.Dcl, result)
+		f := types.NewField(pos, result.Sym(), t)
+		f.Nname = result
+		formalResults = append(formalResults, f)
+	}
+
+	// Build an internal function with the right signature.
+	closureType := types.NewSignature(typ.Pkg(), nil, nil, formalParams, formalResults)
+	typed(closureType, fn.Nname)
+	typed(typ, fn.OClosure)
+	fn.SetTypecheck(1)
+	return fn, formalParams, formalResults
+
+}
+
+// assertToBound returns a new node that converts a node rcvr with interface type to
+// the 'dst' interface type.  bound is the unsubstituted form of dst.
+func assertToBound(info *instInfo, dictVar *ir.Name, pos src.XPos, rcvr ir.Node, bound, dst *types.Type) ir.Node {
+	if bound.HasTParam() {
+		ix := findDictType(info, bound)
+		assert(ix >= 0)
+		rt := getDictionaryType(info, dictVar, pos, ix)
+		rcvr = ir.NewDynamicTypeAssertExpr(pos, ir.ODYNAMICDOTTYPE, rcvr, rt)
+		typed(dst, rcvr)
+	} else {
+		rcvr = ir.NewTypeAssertExpr(pos, rcvr, nil)
+		typed(bound, rcvr)
+	}
+	return rcvr
 }
 
-// newIncompleteNamedType returns a TFORW type t with name specified by sym, such
-// that t.nod and sym.Def are set correctly.
-func newIncompleteNamedType(pos src.XPos, sym *types.Sym) *types.Type {
-	name := ir.NewDeclNameAt(pos, ir.OTYPE, sym)
-	forw := types.NewNamed(name)
-	name.SetType(forw)
-	sym.Def = name
-	return forw
+// buildClosure2 makes a closure to implement a method expression m (generic form x)
+// which has a shape type as receiver. If the receiver is exactly a shape (i.e. from
+// a typeparam), then the body of the closure converts m.X (the receiver) to the
+// interface bound type, and makes an interface call with the remaining arguments.
+//
+// The returned closure is fully substituted and has already had any needed
+// transformations done.
+func (g *irgen) buildClosure2(subst *subster, m, x ir.Node) ir.Node {
+	outer := subst.newf
+	info := subst.info
+	pos := m.Pos()
+	typ := m.Type() // type of the closure
+
+	fn, formalParams, formalResults := startClosure(pos, outer, typ)
+
+	// Capture dictionary calculated in the outer function
+	dictVar := ir.CaptureName(pos, fn, info.dictParam)
+	typed(types.Types[types.TUINTPTR], dictVar)
+
+	// Build arguments to call inside the closure.
+	var args []ir.Node
+	for i := 0; i < typ.NumParams(); i++ {
+		args = append(args, formalParams[i].Nname.(*ir.Name))
+	}
+
+	// Build call itself. This involves converting the first argument to the
+	// bound type (an interface) using the dictionary, and then making an
+	// interface call with the remaining arguments.
+	var innerCall ir.Node
+	rcvr := args[0]
+	args = args[1:]
+	assert(m.(*ir.SelectorExpr).X.Type().IsShape())
+	gsrc := x.(*ir.SelectorExpr).X.Type()
+	bound := gsrc.Bound()
+	dst := bound
+	if dst.HasTParam() {
+		dst = subst.ts.Typ(bound)
+	}
+	if m.(*ir.SelectorExpr).X.Type().IsInterface() {
+		// If type arg is an interface (unusual case), we do a type assert to
+		// the type bound.
+		rcvr = assertToBound(info, dictVar, pos, rcvr, bound, dst)
+	} else {
+		rcvr = convertUsingDictionary(info, dictVar, pos, rcvr, x, dst, gsrc)
+	}
+	dot := ir.NewSelectorExpr(pos, ir.ODOTINTER, rcvr, x.(*ir.SelectorExpr).Sel)
+	dot.Selection = typecheck.Lookdot1(dot, dot.Sel, dot.X.Type(), dot.X.Type().AllMethods(), 1)
+
+	// Do a type substitution on the generic bound, in case it is parameterized.
+	typed(subst.ts.Typ(x.(*ir.SelectorExpr).Selection.Type), dot)
+	innerCall = ir.NewCallExpr(pos, ir.OCALLINTER, dot, args)
+	t := m.Type()
+	if t.NumResults() == 0 {
+		innerCall.SetTypecheck(1)
+	} else if t.NumResults() == 1 {
+		typed(t.Results().Field(0).Type, innerCall)
+	} else {
+		typed(t.Results(), innerCall)
+	}
+	if len(formalResults) > 0 {
+		innerCall = ir.NewReturnStmt(pos, []ir.Node{innerCall})
+		innerCall.SetTypecheck(1)
+	}
+	fn.Body = []ir.Node{innerCall}
+
+	// We're all done with the captured dictionary
+	ir.FinishCaptureNames(pos, outer, fn)
+
+	// Do final checks on closure and return it.
+	return ir.UseClosure(fn.OClosure, g.target)
 }
diff --git a/src/cmd/compile/internal/noder/stmt.go b/src/cmd/compile/internal/noder/stmt.go
index 32a1483b4aabeb2fddeb646fc897ccf216cc52cb..fc1f5836ffe93708c837566d0d173efefa5f89fb 100644
--- a/src/cmd/compile/internal/noder/stmt.go
+++ b/src/cmd/compile/internal/noder/stmt.go
@@ -5,6 +5,7 @@
 package noder
 
 import (
+	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/typecheck"
@@ -27,6 +28,7 @@ func (g *irgen) stmts(stmts []syntax.Stmt) []ir.Node {
 }
 
 func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
+	base.Assert(g.exprStmtOK)
 	switch stmt := stmt.(type) {
 	case nil, *syntax.EmptyStmt:
 		return nil
@@ -35,11 +37,7 @@ func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
 	case *syntax.BlockStmt:
 		return ir.NewBlockStmt(g.pos(stmt), g.blockStmt(stmt))
 	case *syntax.ExprStmt:
-		x := g.expr(stmt.X)
-		if call, ok := x.(*ir.CallExpr); ok {
-			call.Use = ir.CallUseStmt
-		}
-		return x
+		return g.expr(stmt.X)
 	case *syntax.SendStmt:
 		n := ir.NewSendStmt(g.pos(stmt), g.expr(stmt.Chan), g.expr(stmt.Value))
 		if n.Chan.Type().HasTParam() || n.Value.Type().HasTParam() {
@@ -52,7 +50,9 @@ func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
 		n.SetTypecheck(1)
 		return n
 	case *syntax.DeclStmt:
-		return ir.NewBlockStmt(g.pos(stmt), g.decls(stmt.DeclList))
+		n := ir.NewBlockStmt(g.pos(stmt), nil)
+		g.decls(&n.List, stmt.DeclList)
+		return n
 
 	case *syntax.AssignStmt:
 		if stmt.Op != 0 && stmt.Op != syntax.Def {
@@ -61,7 +61,10 @@ func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
 			if stmt.Rhs == nil {
 				n = IncDec(g.pos(stmt), op, g.expr(stmt.Lhs))
 			} else {
-				n = ir.NewAssignOpStmt(g.pos(stmt), op, g.expr(stmt.Lhs), g.expr(stmt.Rhs))
+				// Eval rhs before lhs, for compatibility with noder1
+				rhs := g.expr(stmt.Rhs)
+				lhs := g.expr(stmt.Lhs)
+				n = ir.NewAssignOpStmt(g.pos(stmt), op, lhs, rhs)
 			}
 			if n.X.Typecheck() == 3 {
 				n.SetTypecheck(3)
@@ -72,8 +75,9 @@ func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
 			return n
 		}
 
-		names, lhs := g.assignList(stmt.Lhs, stmt.Op == syntax.Def)
+		// Eval rhs before lhs, for compatibility with noder1
 		rhs := g.exprList(stmt.Rhs)
+		names, lhs := g.assignList(stmt.Lhs, stmt.Op == syntax.Def)
 
 		// We must delay transforming the assign statement if any of the
 		// lhs or rhs nodes are also delayed, since transformAssign needs
@@ -128,6 +132,12 @@ func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
 			if e.Type().HasTParam() {
 				// Delay transforming the return statement if any of the
 				// return values have a type param.
+				if !ir.HasNamedResults(ir.CurFunc) {
+					transformArgs(n)
+					// But add CONVIFACE nodes where needed if
+					// any of the return values have interface type.
+					typecheckaste(ir.ORETURN, nil, false, ir.CurFunc.Type().Results(), n.Results, true)
+				}
 				n.SetTypecheck(3)
 				return n
 			}
@@ -266,6 +276,12 @@ func (g *irgen) forStmt(stmt *syntax.ForStmt) ir.Node {
 		key, value := unpackTwo(lhs)
 		n := ir.NewRangeStmt(g.pos(r), key, value, g.expr(r.X), g.blockStmt(stmt.Body))
 		n.Def = initDefn(n, names)
+		if key != nil {
+			transformCheckAssign(n, key)
+		}
+		if value != nil {
+			transformCheckAssign(n, value)
+		}
 		return n
 	}
 
diff --git a/src/cmd/compile/internal/noder/sync.go b/src/cmd/compile/internal/noder/sync.go
new file mode 100644
index 0000000000000000000000000000000000000000..7af558f8b207aee4f645b554a9e33981f8aaaad3
--- /dev/null
+++ b/src/cmd/compile/internal/noder/sync.go
@@ -0,0 +1,187 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"fmt"
+	"strings"
+)
+
+// enableSync controls whether sync markers are written into unified
+// IR's export data format and also whether they're expected when
+// reading them back in. They're inessential to the correct
+// functioning of unified IR, but are helpful during development to
+// detect mistakes.
+//
+// When sync is enabled, writer stack frames will also be included in
+// the export data. Currently, a fixed number of frames are included,
+// controlled by -d=syncframes (default 0).
+const enableSync = true
+
+// fmtFrames formats a backtrace for reporting reader/writer desyncs.
+func fmtFrames(pcs ...uintptr) []string {
+	res := make([]string, 0, len(pcs))
+	walkFrames(pcs, func(file string, line int, name string, offset uintptr) {
+		// Trim package from function name. It's just redundant noise.
+		name = strings.TrimPrefix(name, "cmd/compile/internal/noder.")
+
+		res = append(res, fmt.Sprintf("%s:%v: %s +0x%v", file, line, name, offset))
+	})
+	return res
+}
+
+type frameVisitor func(file string, line int, name string, offset uintptr)
+
+// syncMarker is an enum type that represents markers that may be
+// written to export data to ensure the reader and writer stay
+// synchronized.
+type syncMarker int
+
+//go:generate stringer -type=syncMarker -trimprefix=sync
+
+// TODO(mdempsky): Cleanup unneeded sync markers.
+
+// TODO(mdempsky): Split these markers into public/stable markers, and
+// private ones. Also, trim unused ones.
+const (
+	_ syncMarker = iota
+	syncNode
+	syncBool
+	syncInt64
+	syncUint64
+	syncString
+	syncPos
+	syncPkg
+	syncSym
+	syncSelector
+	syncKind
+	syncType
+	syncTypePkg
+	syncSignature
+	syncParam
+	syncOp
+	syncObject
+	syncExpr
+	syncStmt
+	syncDecl
+	syncConstDecl
+	syncFuncDecl
+	syncTypeDecl
+	syncVarDecl
+	syncPragma
+	syncValue
+	syncEOF
+	syncMethod
+	syncFuncBody
+	syncUse
+	syncUseObj
+	syncObjectIdx
+	syncTypeIdx
+	syncBOF
+	syncEntry
+	syncOpenScope
+	syncCloseScope
+	syncGlobal
+	syncLocal
+	syncDefine
+	syncDefLocal
+	syncUseLocal
+	syncDefGlobal
+	syncUseGlobal
+	syncTypeParams
+	syncUseLabel
+	syncDefLabel
+	syncFuncLit
+	syncCommonFunc
+	syncBodyRef
+	syncLinksymExt
+	syncHack
+	syncSetlineno
+	syncName
+	syncImportDecl
+	syncDeclNames
+	syncDeclName
+	syncExprList
+	syncExprs
+	syncWrapname
+	syncTypeExpr
+	syncTypeExprOrNil
+	syncChanDir
+	syncParams
+	syncCloseAnotherScope
+	syncSum
+	syncUnOp
+	syncBinOp
+	syncStructType
+	syncInterfaceType
+	syncPackname
+	syncEmbedded
+	syncStmts
+	syncStmtsFall
+	syncStmtFall
+	syncBlockStmt
+	syncIfStmt
+	syncForStmt
+	syncSwitchStmt
+	syncRangeStmt
+	syncCaseClause
+	syncCommClause
+	syncSelectStmt
+	syncDecls
+	syncLabeledStmt
+	syncCompLit
+
+	sync1
+	sync2
+	sync3
+	sync4
+
+	syncN
+	syncDefImplicit
+	syncUseName
+	syncUseObjLocal
+	syncAddLocal
+	syncBothSignature
+	syncSetUnderlying
+	syncLinkname
+	syncStmt1
+	syncStmtsEnd
+	syncDeclare
+	syncTopDecls
+	syncTopConstDecl
+	syncTopFuncDecl
+	syncTopTypeDecl
+	syncTopVarDecl
+	syncObject1
+	syncAddBody
+	syncLabel
+	syncFuncExt
+	syncMethExt
+	syncOptLabel
+	syncScalar
+	syncStmtDecls
+	syncDeclLocal
+	syncObjLocal
+	syncObjLocal1
+	syncDeclareLocal
+	syncPublic
+	syncPrivate
+	syncRelocs
+	syncReloc
+	syncUseReloc
+	syncVarExt
+	syncPkgDef
+	syncTypeExt
+	syncVal
+	syncCodeObj
+	syncPosBase
+	syncLocalIdent
+	syncTypeParamNames
+	syncTypeParamBounds
+	syncImplicitTypes
+	syncObjectName
+)
diff --git a/src/cmd/compile/internal/noder/syncmarker_string.go b/src/cmd/compile/internal/noder/syncmarker_string.go
new file mode 100644
index 0000000000000000000000000000000000000000..655cafc9502d25332bdb9c69b50a77147b701c26
--- /dev/null
+++ b/src/cmd/compile/internal/noder/syncmarker_string.go
@@ -0,0 +1,156 @@
+// Code generated by "stringer -type=syncMarker -trimprefix=sync"; DO NOT EDIT.
+
+package noder
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[syncNode-1]
+	_ = x[syncBool-2]
+	_ = x[syncInt64-3]
+	_ = x[syncUint64-4]
+	_ = x[syncString-5]
+	_ = x[syncPos-6]
+	_ = x[syncPkg-7]
+	_ = x[syncSym-8]
+	_ = x[syncSelector-9]
+	_ = x[syncKind-10]
+	_ = x[syncType-11]
+	_ = x[syncTypePkg-12]
+	_ = x[syncSignature-13]
+	_ = x[syncParam-14]
+	_ = x[syncOp-15]
+	_ = x[syncObject-16]
+	_ = x[syncExpr-17]
+	_ = x[syncStmt-18]
+	_ = x[syncDecl-19]
+	_ = x[syncConstDecl-20]
+	_ = x[syncFuncDecl-21]
+	_ = x[syncTypeDecl-22]
+	_ = x[syncVarDecl-23]
+	_ = x[syncPragma-24]
+	_ = x[syncValue-25]
+	_ = x[syncEOF-26]
+	_ = x[syncMethod-27]
+	_ = x[syncFuncBody-28]
+	_ = x[syncUse-29]
+	_ = x[syncUseObj-30]
+	_ = x[syncObjectIdx-31]
+	_ = x[syncTypeIdx-32]
+	_ = x[syncBOF-33]
+	_ = x[syncEntry-34]
+	_ = x[syncOpenScope-35]
+	_ = x[syncCloseScope-36]
+	_ = x[syncGlobal-37]
+	_ = x[syncLocal-38]
+	_ = x[syncDefine-39]
+	_ = x[syncDefLocal-40]
+	_ = x[syncUseLocal-41]
+	_ = x[syncDefGlobal-42]
+	_ = x[syncUseGlobal-43]
+	_ = x[syncTypeParams-44]
+	_ = x[syncUseLabel-45]
+	_ = x[syncDefLabel-46]
+	_ = x[syncFuncLit-47]
+	_ = x[syncCommonFunc-48]
+	_ = x[syncBodyRef-49]
+	_ = x[syncLinksymExt-50]
+	_ = x[syncHack-51]
+	_ = x[syncSetlineno-52]
+	_ = x[syncName-53]
+	_ = x[syncImportDecl-54]
+	_ = x[syncDeclNames-55]
+	_ = x[syncDeclName-56]
+	_ = x[syncExprList-57]
+	_ = x[syncExprs-58]
+	_ = x[syncWrapname-59]
+	_ = x[syncTypeExpr-60]
+	_ = x[syncTypeExprOrNil-61]
+	_ = x[syncChanDir-62]
+	_ = x[syncParams-63]
+	_ = x[syncCloseAnotherScope-64]
+	_ = x[syncSum-65]
+	_ = x[syncUnOp-66]
+	_ = x[syncBinOp-67]
+	_ = x[syncStructType-68]
+	_ = x[syncInterfaceType-69]
+	_ = x[syncPackname-70]
+	_ = x[syncEmbedded-71]
+	_ = x[syncStmts-72]
+	_ = x[syncStmtsFall-73]
+	_ = x[syncStmtFall-74]
+	_ = x[syncBlockStmt-75]
+	_ = x[syncIfStmt-76]
+	_ = x[syncForStmt-77]
+	_ = x[syncSwitchStmt-78]
+	_ = x[syncRangeStmt-79]
+	_ = x[syncCaseClause-80]
+	_ = x[syncCommClause-81]
+	_ = x[syncSelectStmt-82]
+	_ = x[syncDecls-83]
+	_ = x[syncLabeledStmt-84]
+	_ = x[syncCompLit-85]
+	_ = x[sync1-86]
+	_ = x[sync2-87]
+	_ = x[sync3-88]
+	_ = x[sync4-89]
+	_ = x[syncN-90]
+	_ = x[syncDefImplicit-91]
+	_ = x[syncUseName-92]
+	_ = x[syncUseObjLocal-93]
+	_ = x[syncAddLocal-94]
+	_ = x[syncBothSignature-95]
+	_ = x[syncSetUnderlying-96]
+	_ = x[syncLinkname-97]
+	_ = x[syncStmt1-98]
+	_ = x[syncStmtsEnd-99]
+	_ = x[syncDeclare-100]
+	_ = x[syncTopDecls-101]
+	_ = x[syncTopConstDecl-102]
+	_ = x[syncTopFuncDecl-103]
+	_ = x[syncTopTypeDecl-104]
+	_ = x[syncTopVarDecl-105]
+	_ = x[syncObject1-106]
+	_ = x[syncAddBody-107]
+	_ = x[syncLabel-108]
+	_ = x[syncFuncExt-109]
+	_ = x[syncMethExt-110]
+	_ = x[syncOptLabel-111]
+	_ = x[syncScalar-112]
+	_ = x[syncStmtDecls-113]
+	_ = x[syncDeclLocal-114]
+	_ = x[syncObjLocal-115]
+	_ = x[syncObjLocal1-116]
+	_ = x[syncDeclareLocal-117]
+	_ = x[syncPublic-118]
+	_ = x[syncPrivate-119]
+	_ = x[syncRelocs-120]
+	_ = x[syncReloc-121]
+	_ = x[syncUseReloc-122]
+	_ = x[syncVarExt-123]
+	_ = x[syncPkgDef-124]
+	_ = x[syncTypeExt-125]
+	_ = x[syncVal-126]
+	_ = x[syncCodeObj-127]
+	_ = x[syncPosBase-128]
+	_ = x[syncLocalIdent-129]
+	_ = x[syncTypeParamNames-130]
+	_ = x[syncTypeParamBounds-131]
+	_ = x[syncImplicitTypes-132]
+	_ = x[syncObjectName-133]
+}
+
+const _syncMarker_name = "NodeBoolInt64Uint64StringPosPkgSymSelectorKindTypeTypePkgSignatureParamOpObjectExprStmtDeclConstDeclFuncDeclTypeDeclVarDeclPragmaValueEOFMethodFuncBodyUseUseObjObjectIdxTypeIdxBOFEntryOpenScopeCloseScopeGlobalLocalDefineDefLocalUseLocalDefGlobalUseGlobalTypeParamsUseLabelDefLabelFuncLitCommonFuncBodyRefLinksymExtHackSetlinenoNameImportDeclDeclNamesDeclNameExprListExprsWrapnameTypeExprTypeExprOrNilChanDirParamsCloseAnotherScopeSumUnOpBinOpStructTypeInterfaceTypePacknameEmbeddedStmtsStmtsFallStmtFallBlockStmtIfStmtForStmtSwitchStmtRangeStmtCaseClauseCommClauseSelectStmtDeclsLabeledStmtCompLit1234NDefImplicitUseNameUseObjLocalAddLocalBothSignatureSetUnderlyingLinknameStmt1StmtsEndDeclareTopDeclsTopConstDeclTopFuncDeclTopTypeDeclTopVarDeclObject1AddBodyLabelFuncExtMethExtOptLabelScalarStmtDeclsDeclLocalObjLocalObjLocal1DeclareLocalPublicPrivateRelocsRelocUseRelocVarExtPkgDefTypeExtValCodeObjPosBaseLocalIdentTypeParamNamesTypeParamBoundsImplicitTypesObjectName"
+
+var _syncMarker_index = [...]uint16{0, 4, 8, 13, 19, 25, 28, 31, 34, 42, 46, 50, 57, 66, 71, 73, 79, 83, 87, 91, 100, 108, 116, 123, 129, 134, 137, 143, 151, 154, 160, 169, 176, 179, 184, 193, 203, 209, 214, 220, 228, 236, 245, 254, 264, 272, 280, 287, 297, 304, 314, 318, 327, 331, 341, 350, 358, 366, 371, 379, 387, 400, 407, 413, 430, 433, 437, 442, 452, 465, 473, 481, 486, 495, 503, 512, 518, 525, 535, 544, 554, 564, 574, 579, 590, 597, 598, 599, 600, 601, 602, 613, 620, 631, 639, 652, 665, 673, 678, 686, 693, 701, 713, 724, 735, 745, 752, 759, 764, 771, 778, 786, 792, 801, 810, 818, 827, 839, 845, 852, 858, 863, 871, 877, 883, 890, 893, 900, 907, 917, 931, 946, 959, 969}
+
+func (i syncMarker) String() string {
+	i -= 1
+	if i < 0 || i >= syncMarker(len(_syncMarker_index)-1) {
+		return "syncMarker(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	}
+	return _syncMarker_name[_syncMarker_index[i]:_syncMarker_index[i+1]]
+}
diff --git a/src/cmd/compile/internal/noder/transform.go b/src/cmd/compile/internal/noder/transform.go
index 2859089e69b91386010db02268764a66aa2de7aa..be8651d47b7b2465e2b62f626d6d36f95da7e83b 100644
--- a/src/cmd/compile/internal/noder/transform.go
+++ b/src/cmd/compile/internal/noder/transform.go
@@ -85,7 +85,15 @@ func stringtoruneslit(n *ir.ConvExpr) ir.Node {
 // etc.  Corresponds to typecheck.tcConv.
 func transformConv(n *ir.ConvExpr) ir.Node {
 	t := n.X.Type()
-	op, _ := typecheck.Convertop(n.X.Op() == ir.OLITERAL, t, n.Type())
+	op, why := typecheck.Convertop(n.X.Op() == ir.OLITERAL, t, n.Type())
+	if op == ir.OXXX {
+		// types2 currently ignores pragmas, so a 'notinheap' mismatch is the
+		// one type-related error that it does not catch. This error will be
+		// caught here by Convertop (see two checks near beginning of
+		// Convertop) and reported at the end of noding.
+		base.ErrorfAt(n.Pos(), "cannot convert %L to type %v%s", n.X, n.Type(), why)
+		return n
+	}
 	n.SetOp(op)
 	switch n.Op() {
 	case ir.OCONVNOP:
@@ -122,7 +130,8 @@ func transformConvCall(n *ir.CallExpr) ir.Node {
 }
 
 // transformCall transforms a normal function/method call. Corresponds to last half
-// (non-conversion, non-builtin part) of typecheck.tcCall.
+// (non-conversion, non-builtin part) of typecheck.tcCall. This code should work even
+// in the case of OCALL/OFUNCINST.
 func transformCall(n *ir.CallExpr) {
 	// n.Type() can be nil for calls with no return value
 	assert(n.Typecheck() == 1)
@@ -148,10 +157,11 @@ func transformCall(n *ir.CallExpr) {
 		n.SetOp(ir.OCALLFUNC)
 	}
 
-	typecheckaste(ir.OCALL, n.X, n.IsDDD, t.Params(), n.Args)
+	typecheckaste(ir.OCALL, n.X, n.IsDDD, t.Params(), n.Args, false)
+	if l.Op() == ir.ODOTMETH && len(deref(n.X.Type().Recv().Type).RParams()) == 0 {
+		typecheck.FixMethodCall(n)
+	}
 	if t.NumResults() == 1 {
-		n.SetType(l.Type().Results().Field(0).Type)
-
 		if n.Op() == ir.OCALLFUNC && n.X.Op() == ir.ONAME {
 			if sym := n.X.(*ir.Name).Sym(); types.IsRuntimePkg(sym.Pkg) && sym.Name == "getg" {
 				// Emit code for runtime.getg() directly instead of calling function.
@@ -185,7 +195,7 @@ func transformCompare(n *ir.BinaryExpr) {
 			aop, _ := typecheck.Assignop(lt, rt)
 			if aop != ir.OXXX {
 				types.CalcSize(lt)
-				if rt.IsInterface() == lt.IsInterface() || lt.Width >= 1<<16 {
+				if lt.HasTParam() || rt.IsInterface() == lt.IsInterface() || lt.Width >= 1<<16 {
 					l = ir.NewConvExpr(base.Pos, aop, rt, l)
 					l.SetTypecheck(1)
 				}
@@ -198,7 +208,7 @@ func transformCompare(n *ir.BinaryExpr) {
 			aop, _ := typecheck.Assignop(rt, lt)
 			if aop != ir.OXXX {
 				types.CalcSize(rt)
-				if rt.IsInterface() == lt.IsInterface() || rt.Width >= 1<<16 {
+				if rt.HasTParam() || rt.IsInterface() == lt.IsInterface() || rt.Width >= 1<<16 {
 					r = ir.NewConvExpr(base.Pos, aop, lt, r)
 					r.SetTypecheck(1)
 				}
@@ -303,6 +313,10 @@ assignOK:
 			r := r.(*ir.TypeAssertExpr)
 			stmt.SetOp(ir.OAS2DOTTYPE)
 			r.SetOp(ir.ODOTTYPE2)
+		case ir.ODYNAMICDOTTYPE:
+			r := r.(*ir.DynamicTypeAssertExpr)
+			stmt.SetOp(ir.OAS2DOTTYPE)
+			r.SetOp(ir.ODYNAMICDOTTYPE2)
 		default:
 			break assignOK
 		}
@@ -323,11 +337,22 @@ assignOK:
 		stmt := stmt.(*ir.AssignListStmt)
 		stmt.SetOp(ir.OAS2FUNC)
 		r := rhs[0].(*ir.CallExpr)
-		r.Use = ir.CallUseList
 		rtyp := r.Type()
 
+		mismatched := false
+		failed := false
 		for i := range lhs {
-			checkLHS(i, rtyp.Field(i).Type)
+			result := rtyp.Field(i).Type
+			checkLHS(i, result)
+
+			if lhs[i].Type() == nil || result == nil {
+				failed = true
+			} else if lhs[i] != ir.BlankNode && !types.Identical(lhs[i].Type(), result) {
+				mismatched = true
+			}
+		}
+		if mismatched && !failed {
+			typecheck.RewriteMultiValueCall(stmt, r)
 		}
 		return
 	}
@@ -340,12 +365,12 @@ assignOK:
 	}
 }
 
-// Corresponds to typecheck.typecheckargs.
+// Corresponds to typecheck.typecheckargs.  Really just deals with multi-value calls.
 func transformArgs(n ir.InitNode) {
 	var list []ir.Node
 	switch n := n.(type) {
 	default:
-		base.Fatalf("typecheckargs %+v", n.Op())
+		base.Fatalf("transformArgs %+v", n.Op())
 	case *ir.CallExpr:
 		list = n.Args
 		if n.IsDDD {
@@ -363,46 +388,13 @@ func transformArgs(n ir.InitNode) {
 		return
 	}
 
-	// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
-
 	// Save n as n.Orig for fmt.go.
 	if ir.Orig(n) == n {
 		n.(ir.OrigNode).SetOrig(ir.SepCopy(n))
 	}
 
-	as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
-	as.Rhs.Append(list...)
-
-	// If we're outside of function context, then this call will
-	// be executed during the generated init function. However,
-	// init.go hasn't yet created it. Instead, associate the
-	// temporary variables with  InitTodoFunc for now, and init.go
-	// will reassociate them later when it's appropriate.
-	static := ir.CurFunc == nil
-	if static {
-		ir.CurFunc = typecheck.InitTodoFunc
-	}
-	list = nil
-	for _, f := range t.FieldSlice() {
-		t := typecheck.Temp(f.Type)
-		as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, t))
-		as.Lhs.Append(t)
-		list = append(list, t)
-	}
-	if static {
-		ir.CurFunc = nil
-	}
-
-	switch n := n.(type) {
-	case *ir.CallExpr:
-		n.Args = list
-	case *ir.ReturnStmt:
-		n.Results = list
-	}
-
-	transformAssign(as, as.Lhs, as.Rhs)
-	as.SetTypecheck(1)
-	n.PtrInit().Append(as)
+	// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
+	typecheck.RewriteMultiValueCall(n, list[0])
 }
 
 // assignconvfn converts node n for assignment to type t. Corresponds to
@@ -416,7 +408,10 @@ func assignconvfn(n ir.Node, t *types.Type) ir.Node {
 		return n
 	}
 
-	op, _ := typecheck.Assignop(n.Type(), t)
+	op, why := typecheck.Assignop(n.Type(), t)
+	if op == ir.OXXX {
+		base.Fatalf("found illegal assignment %+v -> %+v; %s", n.Type(), t, why)
+	}
 
 	r := ir.NewConvExpr(base.Pos, op, t, n)
 	r.SetTypecheck(1)
@@ -424,8 +419,11 @@ func assignconvfn(n ir.Node, t *types.Type) ir.Node {
 	return r
 }
 
-// Corresponds to typecheck.typecheckaste.
-func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl ir.Nodes) {
+// Corresponds to typecheck.typecheckaste, but we add an extra flag convifaceOnly
+// only. If convifaceOnly is true, we only do interface conversion. We use this to do
+// early insertion of CONVIFACE nodes during noder2, when the function or args may
+// have typeparams.
+func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl ir.Nodes, convifaceOnly bool) {
 	var t *types.Type
 	var i int
 
@@ -444,7 +442,7 @@ func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl i
 			if isddd {
 				n = nl[i]
 				ir.SetPos(n)
-				if n.Type() != nil {
+				if n.Type() != nil && (!convifaceOnly || t.IsInterface()) {
 					nl[i] = assignconvfn(n, t)
 				}
 				return
@@ -454,7 +452,7 @@ func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl i
 			for ; i < len(nl); i++ {
 				n = nl[i]
 				ir.SetPos(n)
-				if n.Type() != nil {
+				if n.Type() != nil && (!convifaceOnly || t.IsInterface()) {
 					nl[i] = assignconvfn(n, t.Elem())
 				}
 			}
@@ -463,7 +461,7 @@ func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl i
 
 		n = nl[i]
 		ir.SetPos(n)
-		if n.Type() != nil {
+		if n.Type() != nil && (!convifaceOnly || t.IsInterface()) {
 			nl[i] = assignconvfn(n, t)
 		}
 		i++
@@ -485,7 +483,7 @@ func transformReturn(rs *ir.ReturnStmt) {
 		return
 	}
 
-	typecheckaste(ir.ORETURN, nil, false, ir.CurFunc.Type().Results(), nl)
+	typecheckaste(ir.ORETURN, nil, false, ir.CurFunc.Type().Results(), nl, false)
 }
 
 // transformSelect transforms a select node, creating an assignment list as needed
@@ -537,13 +535,31 @@ func transformAsOp(n *ir.AssignOpStmt) {
 }
 
 // transformDot transforms an OXDOT (or ODOT) or ODOT, ODOTPTR, ODOTMETH,
-// ODOTINTER, or OCALLPART, as appropriate. It adds in extra nodes as needed to
+// ODOTINTER, or OMETHVALUE, as appropriate. It adds in extra nodes as needed to
 // access embedded fields. Corresponds to typecheck.tcDot.
 func transformDot(n *ir.SelectorExpr, isCall bool) ir.Node {
 	assert(n.Type() != nil && n.Typecheck() == 1)
 	if n.Op() == ir.OXDOT {
 		n = typecheck.AddImplicitDots(n)
 		n.SetOp(ir.ODOT)
+
+		// Set the Selection field and typecheck flag for any new ODOT nodes
+		// added by AddImplicitDots(), and also transform to ODOTPTR if
+		// needed. Equivalent to 'n.X = typecheck(n.X, ctxExpr|ctxType)' in
+		// tcDot.
+		for n1 := n; n1.X.Op() == ir.ODOT; {
+			n1 = n1.X.(*ir.SelectorExpr)
+			if !n1.Implicit() {
+				break
+			}
+			t1 := n1.X.Type()
+			if t1.IsPtr() && !t1.Elem().IsInterface() {
+				t1 = t1.Elem()
+				n1.SetOp(ir.ODOTPTR)
+			}
+			typecheck.Lookdot(n1, t1, 0)
+			n1.SetTypecheck(1)
+		}
 	}
 
 	t := n.X.Type()
@@ -561,8 +577,9 @@ func transformDot(n *ir.SelectorExpr, isCall bool) ir.Node {
 	assert(f != nil)
 
 	if (n.Op() == ir.ODOTINTER || n.Op() == ir.ODOTMETH) && !isCall {
-		n.SetOp(ir.OCALLPART)
-		n.SetType(typecheck.MethodValueWrapper(n).Type())
+		n.SetOp(ir.OMETHVALUE)
+		// This converts a method type to a function type. See issue 47775.
+		n.SetType(typecheck.NewMethodType(n.Type(), nil))
 	}
 	return n
 }
@@ -594,7 +611,11 @@ func transformMethodExpr(n *ir.SelectorExpr) (res ir.Node) {
 
 	s := n.Sel
 	m := typecheck.Lookdot1(n, s, t, ms, 0)
-	assert(m != nil)
+	if !t.HasShape() {
+		// It's OK to not find the method if t is instantiated by shape types,
+		// because we will use the methods on the generic type anyway.
+		assert(m != nil)
+	}
 
 	n.SetOp(ir.OMETHEXPR)
 	n.Selection = m
@@ -790,7 +811,10 @@ func transformBuiltin(n *ir.CallExpr) ir.Node {
 			return transformRealImag(u1.(*ir.UnaryExpr))
 		case ir.OPANIC:
 			return transformPanic(u1.(*ir.UnaryExpr))
-		case ir.OCLOSE, ir.ONEW, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
+		case ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
+			// This corresponds to the EvalConst() call near end of typecheck().
+			return typecheck.EvalConst(u1)
+		case ir.OCLOSE, ir.ONEW:
 			// nothing more to do
 			return u1
 		}
@@ -911,9 +935,7 @@ func transformCompLit(n *ir.CompLitExpr) (res ir.Node) {
 
 				f := t.Field(i)
 				n1 = assignconvfn(n1, f.Type)
-				sk := ir.NewStructKeyExpr(base.Pos, f.Sym, n1)
-				sk.Offset = f.Offset
-				ls[i] = sk
+				ls[i] = ir.NewStructKeyExpr(base.Pos, f, n1)
 			}
 			assert(len(ls) >= t.NumFields())
 		} else {
@@ -922,33 +944,26 @@ func transformCompLit(n *ir.CompLitExpr) (res ir.Node) {
 			for i, l := range ls {
 				ir.SetPos(l)
 
-				if l.Op() == ir.OKEY {
-					kv := l.(*ir.KeyExpr)
-					key := kv.Key
-
-					// Sym might have resolved to name in other top-level
-					// package, because of import dot. Redirect to correct sym
-					// before we do the lookup.
-					s := key.Sym()
-					if id, ok := key.(*ir.Ident); ok && typecheck.DotImportRefs[id] != nil {
-						s = typecheck.Lookup(s.Name)
-					}
-
-					// An OXDOT uses the Sym field to hold
-					// the field to the right of the dot,
-					// so s will be non-nil, but an OXDOT
-					// is never a valid struct literal key.
-					assert(!(s == nil || s.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || s.IsBlank()))
+				kv := l.(*ir.KeyExpr)
+				key := kv.Key
 
-					l = ir.NewStructKeyExpr(l.Pos(), s, kv.Value)
-					ls[i] = l
+				// Sym might have resolved to name in other top-level
+				// package, because of import dot. Redirect to correct sym
+				// before we do the lookup.
+				s := key.Sym()
+				if id, ok := key.(*ir.Ident); ok && typecheck.DotImportRefs[id] != nil {
+					s = typecheck.Lookup(s.Name)
 				}
 
-				assert(l.Op() == ir.OSTRUCTKEY)
-				l := l.(*ir.StructKeyExpr)
+				// An OXDOT uses the Sym field to hold
+				// the field to the right of the dot,
+				// so s will be non-nil, but an OXDOT
+				// is never a valid struct literal key.
+				assert(!(s == nil || s.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || s.IsBlank()))
 
-				f := typecheck.Lookdot1(nil, l.Field, t, t.Fields(), 0)
-				l.Offset = f.Offset
+				f := typecheck.Lookdot1(nil, s, t, t.Fields(), 0)
+				l := ir.NewStructKeyExpr(l.Pos(), f, kv.Value)
+				ls[i] = l
 
 				l.Value = assignconvfn(l.Value, f.Type)
 			}
diff --git a/src/cmd/compile/internal/noder/types.go b/src/cmd/compile/internal/noder/types.go
index 8680559a412970277e2513fe6d1620a55d4393cc..541ed68ef30e580d157098dc14a3afec9c8fb9da 100644
--- a/src/cmd/compile/internal/noder/types.go
+++ b/src/cmd/compile/internal/noder/types.go
@@ -39,6 +39,11 @@ func (g *irgen) typ(typ types2.Type) *types.Type {
 	// recursive types have been fully constructed before we call CheckSize.
 	if res != nil && !res.IsUntyped() && !res.IsFuncArgStruct() && !res.HasTParam() {
 		types.CheckSize(res)
+		if res.IsPtr() {
+			// Pointers always have their size set, even though their element
+			// may not have its size set.
+			types.CheckSize(res.Elem())
+		}
 	}
 	return res
 }
@@ -61,15 +66,19 @@ func (g *irgen) typ1(typ types2.Type) *types.Type {
 
 // instTypeName2 creates a name for an instantiated type, base on the type args
 // (given as types2 types).
-func instTypeName2(name string, targs []types2.Type) string {
+func instTypeName2(name string, targs *types2.TypeList) string {
 	b := bytes.NewBufferString(name)
 	b.WriteByte('[')
-	for i, targ := range targs {
+	n := targs.Len()
+	for i := 0; i < n; i++ {
+		targ := targs.At(i)
 		if i > 0 {
 			b.WriteByte(',')
 		}
+		// Include package names for all types, including typeparams, to
+		// make sure type arguments are uniquely specified.
 		tname := types2.TypeString(targ,
-			func(*types2.Package) string { return "" })
+			func(pkg *types2.Package) string { return pkg.Name() })
 		if strings.Index(tname, ", ") >= 0 {
 			// types2.TypeString puts spaces after a comma in a type
 			// list, but we don't want spaces in our actual type names
@@ -89,60 +98,62 @@ func (g *irgen) typ0(typ types2.Type) *types.Type {
 	case *types2.Basic:
 		return g.basic(typ)
 	case *types2.Named:
-		if typ.TParams() != nil {
+		// If tparams is set, but targs is not, typ is a base generic
+		// type. typ is appearing as part of the source type of an alias,
+		// since that is the only use of a generic type that doesn't
+		// involve instantiation. We just translate the named type in the
+		// normal way below using g.obj().
+		if typ.TParams() != nil && typ.TArgs() != nil {
 			// typ is an instantiation of a defined (named) generic type.
 			// This instantiation should also be a defined (named) type.
 			// types2 gives us the substituted type in t.Underlying()
 			// The substituted type may or may not still have type
 			// params. We might, for example, be substituting one type
 			// param for another type param.
-
-			if typ.TArgs() == nil {
-				base.Fatalf("In typ0, Targs should be set if TParams is set")
-			}
-
-			// When converted to types.Type, typ must have a name,
-			// based on the names of the type arguments. We need a
-			// name to deal with recursive generic types (and it also
-			// looks better when printing types).
+			//
+			// When converted to types.Type, typ has a unique name,
+			// based on the names of the type arguments.
 			instName := instTypeName2(typ.Obj().Name(), typ.TArgs())
 			s := g.pkg(typ.Obj().Pkg()).Lookup(instName)
 			if s.Def != nil {
-				// We have already encountered this instantiation,
-				// so use the type we previously created, since there
+				// We have already encountered this instantiation.
+				// Use the type we previously created, since there
 				// must be exactly one instance of a defined type.
 				return s.Def.Type()
 			}
 
 			// Create a forwarding type first and put it in the g.typs
-			// map, in order to deal with recursive generic types.
-			// Fully set up the extra ntyp information (Def, RParams,
-			// which may set HasTParam) before translating the
-			// underlying type itself, so we handle recursion
-			// correctly, including via method signatures.
-			ntyp := newIncompleteNamedType(g.pos(typ.Obj().Pos()), s)
+			// map, in order to deal with recursive generic types
+			// (including via method signatures).. Set up the extra
+			// ntyp information (Def, RParams, which may set
+			// HasTParam) before translating the underlying type
+			// itself, so we handle recursion correctly.
+			ntyp := typecheck.NewIncompleteNamedType(g.pos(typ.Obj().Pos()), s)
 			g.typs[typ] = ntyp
 
 			// If ntyp still has type params, then we must be
 			// referencing something like 'value[T2]', as when
-			// specifying the generic receiver of a method,
-			// where value was defined as "type value[T any]
-			// ...". Save the type args, which will now be the
-			// new type  of the current type.
+			// specifying the generic receiver of a method, where
+			// value was defined as "type value[T any] ...". Save the
+			// type args, which will now be the new typeparams of the
+			// current type.
 			//
 			// If ntyp does not have type params, we are saving the
-			// concrete types used to instantiate this type. We'll use
-			// these when instantiating the methods of the
+			// non-generic types used to instantiate this type. We'll
+			// use these when instantiating the methods of the
 			// instantiated type.
-			rparams := make([]*types.Type, len(typ.TArgs()))
-			for i, targ := range typ.TArgs() {
-				rparams[i] = g.typ1(targ)
+			targs := typ.TArgs()
+			rparams := make([]*types.Type, targs.Len())
+			for i := range rparams {
+				rparams[i] = g.typ1(targs.At(i))
 			}
 			ntyp.SetRParams(rparams)
 			//fmt.Printf("Saw new type %v %v\n", instName, ntyp.HasTParam())
 
 			ntyp.SetUnderlying(g.typ1(typ.Underlying()))
 			g.fillinMethods(typ, ntyp)
+			// Save the symbol for the base generic type.
+			ntyp.OrigSym = g.pkg(typ.Obj().Pkg()).Lookup(typ.Obj().Name())
 			return ntyp
 		}
 		obj := g.obj(typ.Obj())
@@ -183,12 +194,9 @@ func (g *irgen) typ0(typ types2.Type) *types.Type {
 		for i := range embeddeds {
 			// TODO(mdempsky): Get embedding position.
 			e := typ.EmbeddedType(i)
-			if t := types2.AsInterface(e); t != nil && t.IsComparable() {
-				// Ignore predefined type 'comparable', since it
-				// doesn't resolve and it doesn't have any
-				// relevant methods.
-				continue
-			}
+
+			// With Go 1.18, an embedded element can be any type, not
+			// just an interface.
 			embeddeds[j] = types.NewField(src.NoXPos, nil, g.typ1(e))
 			j++
 		}
@@ -204,20 +212,39 @@ func (g *irgen) typ0(typ types2.Type) *types.Type {
 		return types.NewInterface(g.tpkg(typ), append(embeddeds, methods...))
 
 	case *types2.TypeParam:
-		tp := types.NewTypeParam(g.tpkg(typ))
 		// Save the name of the type parameter in the sym of the type.
 		// Include the types2 subscript in the sym name
-		sym := g.pkg(typ.Obj().Pkg()).Lookup(types2.TypeString(typ, func(*types2.Package) string { return "" }))
-		tp.SetSym(sym)
+		pkg := g.tpkg(typ)
+		sym := pkg.Lookup(types2.TypeString(typ, func(*types2.Package) string { return "" }))
+		if sym.Def != nil {
+			// Make sure we use the same type param type for the same
+			// name, whether it is created during types1-import or
+			// this types2-to-types1 translation.
+			return sym.Def.Type()
+		}
+		tp := types.NewTypeParam(sym, typ.Index())
+		nname := ir.NewDeclNameAt(g.pos(typ.Obj().Pos()), ir.OTYPE, sym)
+		sym.Def = nname
+		nname.SetType(tp)
+		tp.SetNod(nname)
 		// Set g.typs[typ] in case the bound methods reference typ.
 		g.typs[typ] = tp
 
-		// TODO(danscales): we don't currently need to use the bounds
-		// anywhere, so eventually we can probably remove.
-		bound := g.typ1(typ.Bound())
-		*tp.Methods() = *bound.Methods()
+		bound := g.typ1(typ.Constraint())
+		tp.SetBound(bound)
 		return tp
 
+	case *types2.Union:
+		nt := typ.Len()
+		tlist := make([]*types.Type, nt)
+		tildes := make([]bool, nt)
+		for i := range tlist {
+			t := typ.Term(i)
+			tlist[i] = g.typ1(t.Type())
+			tildes[i] = t.Tilde()
+		}
+		return types.NewUnion(tlist, tildes)
+
 	case *types2.Tuple:
 		// Tuples are used for the type of a function call (i.e. the
 		// return value of the function).
@@ -243,19 +270,24 @@ func (g *irgen) typ0(typ types2.Type) *types.Type {
 // and for actually generating the methods for instantiated types.
 func (g *irgen) fillinMethods(typ *types2.Named, ntyp *types.Type) {
 	if typ.NumMethods() != 0 {
-		targs := make([]ir.Node, len(typ.TArgs()))
-		for i, targ := range typ.TArgs() {
-			targs[i] = ir.TypeNode(g.typ1(targ))
+		targs2 := typ.TArgs()
+		targs := make([]*types.Type, targs2.Len())
+		for i := range targs {
+			targs[i] = g.typ1(targs2.At(i))
 		}
 
 		methods := make([]*types.Field, typ.NumMethods())
 		for i := range methods {
 			m := typ.Method(i)
-			meth := g.obj(m)
-			recvType := types2.AsSignature(m.Type()).Recv().Type()
-			ptr := types2.AsPointer(recvType)
-			if ptr != nil {
-				recvType = ptr.Elem()
+			recvType := deref2(types2.AsSignature(m.Type()).Recv().Type())
+			var meth *ir.Name
+			if m.Pkg() != g.self {
+				// Imported methods cannot be loaded by name (what
+				// g.obj() does) - they must be loaded via their
+				// type.
+				meth = g.obj(recvType.(*types2.Named).Obj()).Type().Methods().Index(i).Nname.(*ir.Name)
+			} else {
+				meth = g.obj(m)
 			}
 			if recvType != types2.Type(typ) {
 				// Unfortunately, meth is the type of the method of the
@@ -276,18 +308,21 @@ func (g *irgen) fillinMethods(typ *types2.Named, ntyp *types.Type) {
 				} else {
 					meth2 = ir.NewNameAt(meth.Pos(), newsym)
 					rparams := types2.AsSignature(m.Type()).RParams()
-					tparams := make([]*types.Field, len(rparams))
-					for i, rparam := range rparams {
-						tparams[i] = types.NewField(src.NoXPos, nil, g.typ1(rparam.Type()))
+					tparams := make([]*types.Type, rparams.Len())
+					for i := range tparams {
+						tparams[i] = g.typ1(rparams.At(i))
 					}
 					assert(len(tparams) == len(targs))
-					subst := &subster{
-						g:       g,
-						tparams: tparams,
-						targs:   targs,
+					ts := typecheck.Tsubster{
+						Tparams: tparams,
+						Targs:   targs,
 					}
 					// Do the substitution of the type
-					meth2.SetType(subst.typ(meth.Type()))
+					meth2.SetType(ts.Typ(meth.Type()))
+					// Add any new fully instantiated types
+					// seen during the substitution to
+					// g.instTypeList.
+					g.instTypeList = append(g.instTypeList, ts.InstTypeList...)
 					newsym.Def = meth2
 				}
 				meth = meth2
@@ -296,7 +331,7 @@ func (g *irgen) fillinMethods(typ *types2.Named, ntyp *types.Type) {
 			methods[i].Nname = meth
 		}
 		ntyp.Methods().Set(methods)
-		if !ntyp.HasTParam() {
+		if !ntyp.HasTParam() && !ntyp.HasShape() {
 			// Generate all the methods for a new fully-instantiated type.
 			g.instTypeList = append(g.instTypeList, ntyp)
 		}
@@ -305,9 +340,9 @@ func (g *irgen) fillinMethods(typ *types2.Named, ntyp *types.Type) {
 
 func (g *irgen) signature(recv *types.Field, sig *types2.Signature) *types.Type {
 	tparams2 := sig.TParams()
-	tparams := make([]*types.Field, len(tparams2))
+	tparams := make([]*types.Field, tparams2.Len())
 	for i := range tparams {
-		tp := tparams2[i]
+		tp := tparams2.At(i).Obj()
 		tparams[i] = types.NewField(g.pos(tp), g.sym(tp), g.typ1(tp.Type()))
 	}
 
@@ -346,7 +381,7 @@ func (g *irgen) selector(obj types2.Object) *types.Sym {
 	return pkg.Lookup(name)
 }
 
-// tpkg returns the package that a function, interface, or struct type
+// tpkg returns the package that a function, interface, struct, or typeparam type
 // expression appeared in.
 //
 // Caveat: For the degenerate types "func()", "interface{}", and
@@ -356,36 +391,39 @@ func (g *irgen) selector(obj types2.Object) *types.Sym {
 // particular types is because go/types does *not* report it for
 // them. So in practice this limitation is probably moot.
 func (g *irgen) tpkg(typ types2.Type) *types.Pkg {
-	anyObj := func() types2.Object {
-		switch typ := typ.(type) {
-		case *types2.Signature:
-			if recv := typ.Recv(); recv != nil {
-				return recv
-			}
-			if params := typ.Params(); params.Len() > 0 {
-				return params.At(0)
-			}
-			if results := typ.Results(); results.Len() > 0 {
-				return results.At(0)
-			}
-		case *types2.Struct:
-			if typ.NumFields() > 0 {
-				return typ.Field(0)
-			}
-		case *types2.Interface:
-			if typ.NumExplicitMethods() > 0 {
-				return typ.ExplicitMethod(0)
-			}
-		}
-		return nil
-	}
-
-	if obj := anyObj(); obj != nil {
+	if obj := anyObj(typ); obj != nil {
 		return g.pkg(obj.Pkg())
 	}
 	return types.LocalPkg
 }
 
+// anyObj returns some object accessible from typ, if any.
+func anyObj(typ types2.Type) types2.Object {
+	switch typ := typ.(type) {
+	case *types2.Signature:
+		if recv := typ.Recv(); recv != nil {
+			return recv
+		}
+		if params := typ.Params(); params.Len() > 0 {
+			return params.At(0)
+		}
+		if results := typ.Results(); results.Len() > 0 {
+			return results.At(0)
+		}
+	case *types2.Struct:
+		if typ.NumFields() > 0 {
+			return typ.Field(0)
+		}
+	case *types2.Interface:
+		if typ.NumExplicitMethods() > 0 {
+			return typ.ExplicitMethod(0)
+		}
+	case *types2.TypeParam:
+		return typ.Obj()
+	}
+	return nil
+}
+
 func (g *irgen) basic(typ *types2.Basic) *types.Type {
 	switch typ.Name() {
 	case "byte":
@@ -430,3 +468,11 @@ var dirs = [...]types.ChanDir{
 	types2.SendOnly: types.Csend,
 	types2.RecvOnly: types.Crecv,
 }
+
+// deref2 does a single deref of types2 type t, if it is a pointer type.
+func deref2(t types2.Type) types2.Type {
+	if ptr := types2.AsPointer(t); ptr != nil {
+		t = ptr.Elem()
+	}
+	return t
+}
diff --git a/src/cmd/compile/internal/noder/unified.go b/src/cmd/compile/internal/noder/unified.go
new file mode 100644
index 0000000000000000000000000000000000000000..9f80ca000de317e8ca1ec2b03f05afe92922f691
--- /dev/null
+++ b/src/cmd/compile/internal/noder/unified.go
@@ -0,0 +1,340 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"fmt"
+	"internal/goversion"
+	"io"
+	"runtime"
+	"sort"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/inline"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+// localPkgReader holds the package reader used for reading the local
+// package. It exists so the unified IR linker can refer back to it
+// later.
+var localPkgReader *pkgReader
+
+// unified construct the local package's IR from syntax's AST.
+//
+// The pipeline contains 2 steps:
+//
+// (1) Generate package export data "stub".
+//
+// (2) Generate package IR from package export data.
+//
+// The package data "stub" at step (1) contains everything from the local package,
+// but nothing that have been imported. When we're actually writing out export data
+// to the output files (see writeNewExport function), we run the "linker", which does
+// a few things:
+//
+// + Updates compiler extensions data (e.g., inlining cost, escape analysis results).
+//
+// + Handles re-exporting any transitive dependencies.
+//
+// + Prunes out any unnecessary details (e.g., non-inlineable functions, because any
+//   downstream importers only care about inlinable functions).
+//
+// The source files are typechecked twice, once before writing export data
+// using types2 checker, once after read export data using gc/typecheck.
+// This duplication of work will go away once we always use types2 checker,
+// we can remove the gc/typecheck pass. The reason it is still here:
+//
+// + It reduces engineering costs in maintaining a fork of typecheck
+//   (e.g., no need to backport fixes like CL 327651).
+//
+// + It makes it easier to pass toolstash -cmp.
+//
+// + Historically, we would always re-run the typechecker after import, even though
+//   we know the imported data is valid. It's not ideal, but also not causing any
+//   problem either.
+//
+// + There's still transformation that being done during gc/typecheck, like rewriting
+//   multi-valued function call, or transform ir.OINDEX -> ir.OINDEXMAP.
+//
+// Using syntax+types2 tree, which already has a complete representation of generics,
+// the unified IR has the full typed AST for doing introspection during step (1).
+// In other words, we have all necessary information to build the generic IR form
+// (see writer.captureVars for an example).
+func unified(noders []*noder) {
+	inline.NewInline = InlineCall
+
+	if !quirksMode() {
+		writeNewExportFunc = writeNewExport
+	} else if base.Flag.G != 0 {
+		base.Errorf("cannot use -G and -d=quirksmode together")
+	}
+
+	newReadImportFunc = func(data string, pkg1 *types.Pkg, check *types2.Checker, packages map[string]*types2.Package) (pkg2 *types2.Package, err error) {
+		pr := newPkgDecoder(pkg1.Path, data)
+
+		// Read package descriptors for both types2 and compiler backend.
+		readPackage(newPkgReader(pr), pkg1)
+		pkg2 = readPackage2(check, packages, pr)
+		return
+	}
+
+	data := writePkgStub(noders)
+
+	// We already passed base.Flag.Lang to types2 to handle validating
+	// the user's source code. Bump it up now to the current version and
+	// re-parse, so typecheck doesn't complain if we construct IR that
+	// utilizes newer Go features.
+	base.Flag.Lang = fmt.Sprintf("go1.%d", goversion.Version)
+	types.ParseLangFlag()
+
+	assert(types.LocalPkg.Path == "")
+	types.LocalPkg.Height = 0 // reset so pkgReader.pkgIdx doesn't complain
+	target := typecheck.Target
+
+	typecheck.TypecheckAllowed = true
+
+	localPkgReader = newPkgReader(newPkgDecoder(types.LocalPkg.Path, data))
+	readPackage(localPkgReader, types.LocalPkg)
+
+	r := localPkgReader.newReader(relocMeta, privateRootIdx, syncPrivate)
+	r.ext = r
+	r.pkgInit(types.LocalPkg, target)
+
+	// Type-check any top-level assignments. We ignore non-assignments
+	// here because other declarations are typechecked as they're
+	// constructed.
+	for i, ndecls := 0, len(target.Decls); i < ndecls; i++ {
+		switch n := target.Decls[i]; n.Op() {
+		case ir.OAS, ir.OAS2:
+			target.Decls[i] = typecheck.Stmt(n)
+		}
+	}
+
+	// Don't use range--bodyIdx can add closures to todoBodies.
+	for len(todoBodies) > 0 {
+		// The order we expand bodies doesn't matter, so pop from the end
+		// to reduce todoBodies reallocations if it grows further.
+		fn := todoBodies[len(todoBodies)-1]
+		todoBodies = todoBodies[:len(todoBodies)-1]
+
+		pri, ok := bodyReader[fn]
+		assert(ok)
+		pri.funcBody(fn)
+
+		// Instantiated generic function: add to Decls for typechecking
+		// and compilation.
+		if fn.OClosure == nil && len(pri.dict.targs) != 0 {
+			target.Decls = append(target.Decls, fn)
+		}
+	}
+	todoBodies = nil
+
+	if !quirksMode() {
+		// TODO(mdempsky): Investigate generating wrappers in quirks mode too.
+		r.wrapTypes(target)
+	}
+
+	// Check that nothing snuck past typechecking.
+	for _, n := range target.Decls {
+		if n.Typecheck() == 0 {
+			base.FatalfAt(n.Pos(), "missed typecheck: %v", n)
+		}
+
+		// For functions, check that at least their first statement (if
+		// any) was typechecked too.
+		if fn, ok := n.(*ir.Func); ok && len(fn.Body) != 0 {
+			if stmt := fn.Body[0]; stmt.Typecheck() == 0 {
+				base.FatalfAt(stmt.Pos(), "missed typecheck: %v", stmt)
+			}
+		}
+	}
+
+	base.ExitIfErrors() // just in case
+}
+
+// writePkgStub type checks the given parsed source files,
+// writes an export data package stub representing them,
+// and returns the result.
+func writePkgStub(noders []*noder) string {
+	m, pkg, info := checkFiles(noders)
+
+	pw := newPkgWriter(m, pkg, info)
+
+	pw.collectDecls(noders)
+
+	publicRootWriter := pw.newWriter(relocMeta, syncPublic)
+	privateRootWriter := pw.newWriter(relocMeta, syncPrivate)
+
+	assert(publicRootWriter.idx == publicRootIdx)
+	assert(privateRootWriter.idx == privateRootIdx)
+
+	{
+		w := publicRootWriter
+		w.pkg(pkg)
+		w.bool(false) // has init; XXX
+
+		scope := pkg.Scope()
+		names := scope.Names()
+		w.len(len(names))
+		for _, name := range scope.Names() {
+			w.obj(scope.Lookup(name), nil)
+		}
+
+		w.sync(syncEOF)
+		w.flush()
+	}
+
+	{
+		w := privateRootWriter
+		w.ext = w
+		w.pkgInit(noders)
+		w.flush()
+	}
+
+	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
+	pw.dump(&sb)
+
+	// At this point, we're done with types2. Make sure the package is
+	// garbage collected.
+	freePackage(pkg)
+
+	return sb.String()
+}
+
+// freePackage ensures the given package is garbage collected.
+func freePackage(pkg *types2.Package) {
+	// The GC test below relies on a precise GC that runs finalizers as
+	// soon as objects are unreachable. Our implementation provides
+	// this, but other/older implementations may not (e.g., Go 1.4 does
+	// not because of #22350). To avoid imposing unnecessary
+	// restrictions on the GOROOT_BOOTSTRAP toolchain, we skip the test
+	// during bootstrapping.
+	if base.CompilerBootstrap {
+		return
+	}
+
+	// Set a finalizer on pkg so we can detect if/when it's collected.
+	done := make(chan struct{})
+	runtime.SetFinalizer(pkg, func(*types2.Package) { close(done) })
+
+	// Important: objects involved in cycles are not finalized, so zero
+	// out pkg to break its cycles and allow the finalizer to run.
+	*pkg = types2.Package{}
+
+	// It typically takes just 1 or 2 cycles to release pkg, but it
+	// doesn't hurt to try a few more times.
+	for i := 0; i < 10; i++ {
+		select {
+		case <-done:
+			return
+		default:
+			runtime.GC()
+		}
+	}
+
+	base.Fatalf("package never finalized")
+}
+
+func readPackage(pr *pkgReader, importpkg *types.Pkg) {
+	r := pr.newReader(relocMeta, publicRootIdx, syncPublic)
+
+	pkg := r.pkg()
+	assert(pkg == importpkg)
+
+	if r.bool() {
+		sym := pkg.Lookup(".inittask")
+		task := ir.NewNameAt(src.NoXPos, sym)
+		task.Class = ir.PEXTERN
+		sym.Def = task
+	}
+
+	for i, n := 0, r.len(); i < n; i++ {
+		r.sync(syncObject)
+		assert(!r.bool())
+		idx := r.reloc(relocObj)
+		assert(r.len() == 0)
+
+		path, name, code := r.p.peekObj(idx)
+		if code != objStub {
+			objReader[types.NewPkg(path, "").Lookup(name)] = pkgReaderIndex{pr, idx, nil}
+		}
+	}
+}
+
+func writeNewExport(out io.Writer) {
+	l := linker{
+		pw: newPkgEncoder(),
+
+		pkgs:  make(map[string]int),
+		decls: make(map[*types.Sym]int),
+	}
+
+	publicRootWriter := l.pw.newEncoder(relocMeta, syncPublic)
+	assert(publicRootWriter.idx == publicRootIdx)
+
+	var selfPkgIdx int
+
+	{
+		pr := localPkgReader
+		r := pr.newDecoder(relocMeta, publicRootIdx, syncPublic)
+
+		r.sync(syncPkg)
+		selfPkgIdx = l.relocIdx(pr, relocPkg, r.reloc(relocPkg))
+
+		r.bool() // has init
+
+		for i, n := 0, r.len(); i < n; i++ {
+			r.sync(syncObject)
+			assert(!r.bool())
+			idx := r.reloc(relocObj)
+			assert(r.len() == 0)
+
+			xpath, xname, xtag := pr.peekObj(idx)
+			assert(xpath == pr.pkgPath)
+			assert(xtag != objStub)
+
+			if types.IsExported(xname) {
+				l.relocIdx(pr, relocObj, idx)
+			}
+		}
+
+		r.sync(syncEOF)
+	}
+
+	{
+		var idxs []int
+		for _, idx := range l.decls {
+			idxs = append(idxs, idx)
+		}
+		sort.Ints(idxs)
+
+		w := publicRootWriter
+
+		w.sync(syncPkg)
+		w.reloc(relocPkg, selfPkgIdx)
+
+		w.bool(typecheck.Lookup(".inittask").Def != nil)
+
+		w.len(len(idxs))
+		for _, idx := range idxs {
+			w.sync(syncObject)
+			w.bool(false)
+			w.reloc(relocObj, idx)
+			w.len(0)
+		}
+
+		w.sync(syncEOF)
+		w.flush()
+	}
+
+	l.pw.dump(out)
+}
diff --git a/src/cmd/compile/internal/noder/unified_test.go b/src/cmd/compile/internal/noder/unified_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..96cc66f775d3895060e6ca69c9ad3c92ce5067a0
--- /dev/null
+++ b/src/cmd/compile/internal/noder/unified_test.go
@@ -0,0 +1,153 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder_test
+
+import (
+	"encoding/json"
+	"flag"
+	exec "internal/execabs"
+	"os"
+	"reflect"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+var (
+	flagPkgs     = flag.String("pkgs", "std", "list of packages to compare (ignored in -short mode)")
+	flagAll      = flag.Bool("all", false, "enable testing of all GOOS/GOARCH targets")
+	flagParallel = flag.Bool("parallel", false, "test GOOS/GOARCH targets in parallel")
+)
+
+// TestUnifiedCompare implements a test similar to running:
+//
+//	$ go build -toolexec="toolstash -cmp" std
+//
+// The -pkgs flag controls the list of packages tested.
+//
+// By default, only the native GOOS/GOARCH target is enabled. The -all
+// flag enables testing of non-native targets. The -parallel flag
+// additionally enables testing of targets in parallel.
+//
+// Caution: Testing all targets is very resource intensive! On an IBM
+// P920 (dual Intel Xeon Gold 6154 CPUs; 36 cores, 192GB RAM), testing
+// all targets in parallel takes about 5 minutes. Using the 'go test'
+// command's -run flag for subtest matching is recommended for less
+// powerful machines.
+func TestUnifiedCompare(t *testing.T) {
+	targets, err := exec.Command("go", "tool", "dist", "list").Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, target := range strings.Fields(string(targets)) {
+		t.Run(target, func(t *testing.T) {
+			parts := strings.Split(target, "/")
+			goos, goarch := parts[0], parts[1]
+
+			if !(*flagAll || goos == runtime.GOOS && goarch == runtime.GOARCH) {
+				t.Skip("skipping non-native target (use -all to enable)")
+			}
+			if *flagParallel {
+				t.Parallel()
+			}
+
+			pkgs1 := loadPackages(t, goos, goarch, "-d=unified=0 -d=inlfuncswithclosures=0 -d=unifiedquirks=1 -G=0")
+			pkgs2 := loadPackages(t, goos, goarch, "-d=unified=1 -d=inlfuncswithclosures=0 -d=unifiedquirks=1 -G=0")
+
+			if len(pkgs1) != len(pkgs2) {
+				t.Fatalf("length mismatch: %v != %v", len(pkgs1), len(pkgs2))
+			}
+
+			for i := range pkgs1 {
+				pkg1 := pkgs1[i]
+				pkg2 := pkgs2[i]
+
+				path := pkg1.ImportPath
+				if path != pkg2.ImportPath {
+					t.Fatalf("mismatched paths: %q != %q", path, pkg2.ImportPath)
+				}
+
+				// Packages that don't have any source files (e.g., packages
+				// unsafe, embed/internal/embedtest, and cmd/internal/moddeps).
+				if pkg1.Export == "" && pkg2.Export == "" {
+					continue
+				}
+
+				if pkg1.BuildID == pkg2.BuildID {
+					t.Errorf("package %q: build IDs unexpectedly matched", path)
+				}
+
+				// Unlike toolstash -cmp, we're comparing the same compiler
+				// binary against itself, just with different flags. So we
+				// don't need to worry about skipping over mismatched version
+				// strings, but we do need to account for differing build IDs.
+				//
+				// Fortunately, build IDs are cryptographic 256-bit hashes,
+				// and cmd/go provides us with them up front. So we can just
+				// use them as delimeters to split the files, and then check
+				// that the substrings are all equal.
+				file1 := strings.Split(readFile(t, pkg1.Export), pkg1.BuildID)
+				file2 := strings.Split(readFile(t, pkg2.Export), pkg2.BuildID)
+				if !reflect.DeepEqual(file1, file2) {
+					t.Errorf("package %q: compile output differs", path)
+				}
+			}
+		})
+	}
+}
+
+type pkg struct {
+	ImportPath string
+	Export     string
+	BuildID    string
+	Incomplete bool
+}
+
+func loadPackages(t *testing.T, goos, goarch, gcflags string) []pkg {
+	args := []string{"list", "-e", "-export", "-json", "-gcflags=all=" + gcflags, "--"}
+	if testing.Short() {
+		t.Log("short testing mode; only testing package runtime")
+		args = append(args, "runtime")
+	} else {
+		args = append(args, strings.Fields(*flagPkgs)...)
+	}
+
+	cmd := exec.Command("go", args...)
+	cmd.Env = append(os.Environ(), "GOOS="+goos, "GOARCH="+goarch)
+	cmd.Stderr = os.Stderr
+	t.Logf("running %v", cmd)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := cmd.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	var res []pkg
+	for dec := json.NewDecoder(stdout); dec.More(); {
+		var pkg pkg
+		if err := dec.Decode(&pkg); err != nil {
+			t.Fatal(err)
+		}
+		if pkg.Incomplete {
+			t.Fatalf("incomplete package: %q", pkg.ImportPath)
+		}
+		res = append(res, pkg)
+	}
+	if err := cmd.Wait(); err != nil {
+		t.Fatal(err)
+	}
+	return res
+}
+
+func readFile(t *testing.T, name string) string {
+	buf, err := os.ReadFile(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(buf)
+}
diff --git a/src/cmd/compile/internal/noder/validate.go b/src/cmd/compile/internal/noder/validate.go
index b926222c89c417ccf7a691f3fc9fe60a0c68e1ae..dcacae7480c2975c50182aeb72d46d31e374d4f4 100644
--- a/src/cmd/compile/internal/noder/validate.go
+++ b/src/cmd/compile/internal/noder/validate.go
@@ -55,7 +55,15 @@ func (g *irgen) validate(n syntax.Node) {
 	case *syntax.CallExpr:
 		tv := g.info.Types[n.Fun]
 		if tv.IsBuiltin() {
-			switch builtin := n.Fun.(type) {
+			fun := n.Fun
+			for {
+				builtin, ok := fun.(*syntax.ParenExpr)
+				if !ok {
+					break
+				}
+				fun = builtin.X
+			}
+			switch builtin := fun.(type) {
 			case *syntax.Name:
 				g.validateBuiltin(builtin.Value, n)
 			case *syntax.SelectorExpr:
@@ -73,7 +81,16 @@ func (g *irgen) validateBuiltin(name string, call *syntax.CallExpr) {
 		// Check that types2+gcSizes calculates sizes the same
 		// as cmd/compile does.
 
-		got, ok := constant.Int64Val(g.info.Types[call].Value)
+		tv := g.info.Types[call]
+		if !tv.IsValue() {
+			base.FatalfAt(g.pos(call), "expected a value")
+		}
+
+		if tv.Value == nil {
+			break // unsafe op is not a constant, so no further validation
+		}
+
+		got, ok := constant.Int64Val(tv.Value)
 		if !ok {
 			base.FatalfAt(g.pos(call), "expected int64 constant value")
 		}
diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
new file mode 100644
index 0000000000000000000000000000000000000000..1405c77161cbbc07dbc3828b044b087b43074b79
--- /dev/null
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -0,0 +1,1882 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"fmt"
+	"go/constant"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+)
+
+type pkgWriter struct {
+	pkgEncoder
+
+	m      posMap
+	curpkg *types2.Package
+	info   *types2.Info
+
+	posBasesIdx map[*syntax.PosBase]int
+	pkgsIdx     map[*types2.Package]int
+	typsIdx     map[types2.Type]int
+	globalsIdx  map[types2.Object]int
+
+	funDecls map[*types2.Func]*syntax.FuncDecl
+	typDecls map[*types2.TypeName]typeDeclGen
+
+	linknames  map[types2.Object]string
+	cgoPragmas [][]string
+
+	dups dupTypes
+}
+
+func newPkgWriter(m posMap, pkg *types2.Package, info *types2.Info) *pkgWriter {
+	return &pkgWriter{
+		pkgEncoder: newPkgEncoder(),
+
+		m:      m,
+		curpkg: pkg,
+		info:   info,
+
+		pkgsIdx:    make(map[*types2.Package]int),
+		globalsIdx: make(map[types2.Object]int),
+		typsIdx:    make(map[types2.Type]int),
+
+		posBasesIdx: make(map[*syntax.PosBase]int),
+
+		funDecls: make(map[*types2.Func]*syntax.FuncDecl),
+		typDecls: make(map[*types2.TypeName]typeDeclGen),
+
+		linknames: make(map[types2.Object]string),
+	}
+}
+
+func (pw *pkgWriter) errorf(p poser, msg string, args ...interface{}) {
+	base.ErrorfAt(pw.m.pos(p), msg, args...)
+}
+
+func (pw *pkgWriter) fatalf(p poser, msg string, args ...interface{}) {
+	base.FatalfAt(pw.m.pos(p), msg, args...)
+}
+
+func (pw *pkgWriter) unexpected(what string, p poser) {
+	pw.fatalf(p, "unexpected %s: %v (%T)", what, p, p)
+}
+
+type writer struct {
+	p *pkgWriter
+
+	encoder
+
+	// For writing out object descriptions, ext points to the extension
+	// writer for where we can write the compiler's private extension
+	// details for the object.
+	//
+	// TODO(mdempsky): This is a little hacky, but works easiest with
+	// the way things are currently.
+	ext *writer
+
+	// TODO(mdempsky): We should be able to prune localsIdx whenever a
+	// scope closes, and then maybe we can just use the same map for
+	// storing the TypeParams too (as their TypeName instead).
+
+	// variables declared within this function
+	localsIdx map[*types2.Var]int
+
+	closureVars    []posObj
+	closureVarsIdx map[*types2.Var]int
+
+	dict    *writerDict
+	derived bool
+}
+
+// A writerDict tracks types and objects that are used by a declaration.
+type writerDict struct {
+	implicits []*types2.TypeName
+
+	// derived is a slice of type indices for computing derived types
+	// (i.e., types that depend on the declaration's type parameters).
+	derived []derivedInfo
+
+	// derivedIdx maps a Type to its corresponding index within the
+	// derived slice, if present.
+	derivedIdx map[types2.Type]int
+
+	// funcs lists references to generic functions that were
+	// instantiated with derived types (i.e., that require
+	// sub-dictionaries when called at run time).
+	funcs []objInfo
+}
+
+type derivedInfo struct {
+	idx    int
+	needed bool
+}
+
+type typeInfo struct {
+	idx     int
+	derived bool
+}
+
+type objInfo struct {
+	idx       int        // index for the generic function declaration
+	explicits []typeInfo // info for the type arguments
+}
+
+func (info objInfo) anyDerived() bool {
+	for _, explicit := range info.explicits {
+		if explicit.derived {
+			return true
+		}
+	}
+	return false
+}
+
+func (info objInfo) equals(other objInfo) bool {
+	if info.idx != other.idx {
+		return false
+	}
+	assert(len(info.explicits) == len(other.explicits))
+	for i, targ := range info.explicits {
+		if targ != other.explicits[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func (pw *pkgWriter) newWriter(k reloc, marker syncMarker) *writer {
+	return &writer{
+		encoder: pw.newEncoder(k, marker),
+		p:       pw,
+	}
+}
+
+// @@@ Positions
+
+func (w *writer) pos(p poser) {
+	w.sync(syncPos)
+	pos := p.Pos()
+
+	// TODO(mdempsky): Track down the remaining cases here and fix them.
+	if !w.bool(pos.IsKnown()) {
+		return
+	}
+
+	// TODO(mdempsky): Delta encoding. Also, if there's a b-side, update
+	// its position base too (but not vice versa!).
+	w.posBase(pos.Base())
+	w.uint(pos.Line())
+	w.uint(pos.Col())
+}
+
+func (w *writer) posBase(b *syntax.PosBase) {
+	w.reloc(relocPosBase, w.p.posBaseIdx(b))
+}
+
+func (pw *pkgWriter) posBaseIdx(b *syntax.PosBase) int {
+	if idx, ok := pw.posBasesIdx[b]; ok {
+		return idx
+	}
+
+	w := pw.newWriter(relocPosBase, syncPosBase)
+	w.p.posBasesIdx[b] = w.idx
+
+	w.string(trimFilename(b))
+
+	if !w.bool(b.IsFileBase()) {
+		w.pos(b)
+		w.uint(b.Line())
+		w.uint(b.Col())
+	}
+
+	return w.flush()
+}
+
+// @@@ Packages
+
+func (w *writer) pkg(pkg *types2.Package) {
+	w.sync(syncPkg)
+	w.reloc(relocPkg, w.p.pkgIdx(pkg))
+}
+
+func (pw *pkgWriter) pkgIdx(pkg *types2.Package) int {
+	if idx, ok := pw.pkgsIdx[pkg]; ok {
+		return idx
+	}
+
+	w := pw.newWriter(relocPkg, syncPkgDef)
+	pw.pkgsIdx[pkg] = w.idx
+
+	if pkg == nil {
+		w.string("builtin")
+	} else {
+		var path string
+		if pkg != w.p.curpkg {
+			path = pkg.Path()
+		}
+		w.string(path)
+		w.string(pkg.Name())
+		w.len(pkg.Height())
+
+		w.len(len(pkg.Imports()))
+		for _, imp := range pkg.Imports() {
+			w.pkg(imp)
+		}
+	}
+
+	return w.flush()
+}
+
+// @@@ Types
+
+func (w *writer) typ(typ types2.Type) {
+	w.typInfo(w.p.typIdx(typ, w.dict))
+}
+
+func (w *writer) typInfo(info typeInfo) {
+	w.sync(syncType)
+	if w.bool(info.derived) {
+		w.len(info.idx)
+		w.derived = true
+	} else {
+		w.reloc(relocType, info.idx)
+	}
+}
+
+// typIdx returns the index where the export data description of type
+// can be read back in. If no such index exists yet, it's created.
+//
+// typIdx also reports whether typ is a derived type; that is, whether
+// its identity depends on type parameters.
+func (pw *pkgWriter) typIdx(typ types2.Type, dict *writerDict) typeInfo {
+	if quirksMode() {
+		typ = pw.dups.orig(typ)
+	}
+
+	if idx, ok := pw.typsIdx[typ]; ok {
+		return typeInfo{idx: idx, derived: false}
+	}
+	if dict != nil {
+		if idx, ok := dict.derivedIdx[typ]; ok {
+			return typeInfo{idx: idx, derived: true}
+		}
+	}
+
+	w := pw.newWriter(relocType, syncTypeIdx)
+	w.dict = dict
+
+	switch typ := typ.(type) {
+	default:
+		base.Fatalf("unexpected type: %v (%T)", typ, typ)
+
+	case *types2.Basic:
+		switch kind := typ.Kind(); {
+		case kind == types2.Invalid:
+			base.Fatalf("unexpected types2.Invalid")
+
+		case types2.Typ[kind] == typ:
+			w.code(typeBasic)
+			w.len(int(kind))
+
+		default:
+			// Handle "byte" and "rune" as references to their TypeName.
+			obj := types2.Universe.Lookup(typ.Name())
+			assert(obj.Type() == typ)
+
+			w.code(typeNamed)
+			w.obj(obj, nil)
+		}
+
+	case *types2.Named:
+		// Type aliases can refer to uninstantiated generic types, so we
+		// might see len(TParams) != 0 && len(TArgs) == 0 here.
+		// TODO(mdempsky): Revisit after #46477 is resolved.
+		assert(typ.TParams().Len() == typ.TArgs().Len() || typ.TArgs().Len() == 0)
+
+		// TODO(mdempsky): Why do we need to loop here?
+		orig := typ
+		for orig.TArgs() != nil {
+			orig = orig.Orig()
+		}
+
+		w.code(typeNamed)
+		w.obj(orig.Obj(), typ.TArgs())
+
+	case *types2.TypeParam:
+		index := func() int {
+			for idx, name := range w.dict.implicits {
+				if name.Type().(*types2.TypeParam) == typ {
+					return idx
+				}
+			}
+
+			return len(w.dict.implicits) + typ.Index()
+		}()
+
+		w.derived = true
+		w.code(typeTypeParam)
+		w.len(index)
+
+	case *types2.Array:
+		w.code(typeArray)
+		w.uint64(uint64(typ.Len()))
+		w.typ(typ.Elem())
+
+	case *types2.Chan:
+		w.code(typeChan)
+		w.len(int(typ.Dir()))
+		w.typ(typ.Elem())
+
+	case *types2.Map:
+		w.code(typeMap)
+		w.typ(typ.Key())
+		w.typ(typ.Elem())
+
+	case *types2.Pointer:
+		w.code(typePointer)
+		w.typ(typ.Elem())
+
+	case *types2.Signature:
+		assert(typ.TParams() == nil)
+		w.code(typeSignature)
+		w.signature(typ)
+
+	case *types2.Slice:
+		w.code(typeSlice)
+		w.typ(typ.Elem())
+
+	case *types2.Struct:
+		w.code(typeStruct)
+		w.structType(typ)
+
+	case *types2.Interface:
+		w.code(typeInterface)
+		w.interfaceType(typ)
+
+	case *types2.Union:
+		w.code(typeUnion)
+		w.unionType(typ)
+	}
+
+	if w.derived {
+		idx := len(dict.derived)
+		dict.derived = append(dict.derived, derivedInfo{idx: w.flush()})
+		dict.derivedIdx[typ] = idx
+		return typeInfo{idx: idx, derived: true}
+	}
+
+	pw.typsIdx[typ] = w.idx
+	return typeInfo{idx: w.flush(), derived: false}
+}
+
+func (w *writer) structType(typ *types2.Struct) {
+	w.len(typ.NumFields())
+	for i := 0; i < typ.NumFields(); i++ {
+		f := typ.Field(i)
+		w.pos(f)
+		w.selector(f)
+		w.typ(f.Type())
+		w.string(typ.Tag(i))
+		w.bool(f.Embedded())
+	}
+}
+
+func (w *writer) unionType(typ *types2.Union) {
+	w.len(typ.Len())
+	for i := 0; i < typ.Len(); i++ {
+		t := typ.Term(i)
+		w.bool(t.Tilde())
+		w.typ(t.Type())
+	}
+}
+
+func (w *writer) interfaceType(typ *types2.Interface) {
+	w.len(typ.NumExplicitMethods())
+	w.len(typ.NumEmbeddeds())
+
+	for i := 0; i < typ.NumExplicitMethods(); i++ {
+		m := typ.ExplicitMethod(i)
+		sig := m.Type().(*types2.Signature)
+		assert(sig.TParams() == nil)
+
+		w.pos(m)
+		w.selector(m)
+		w.signature(sig)
+	}
+
+	for i := 0; i < typ.NumEmbeddeds(); i++ {
+		w.typ(typ.EmbeddedType(i))
+	}
+}
+
+func (w *writer) signature(sig *types2.Signature) {
+	w.sync(syncSignature)
+	w.params(sig.Params())
+	w.params(sig.Results())
+	w.bool(sig.Variadic())
+}
+
+func (w *writer) params(typ *types2.Tuple) {
+	w.sync(syncParams)
+	w.len(typ.Len())
+	for i := 0; i < typ.Len(); i++ {
+		w.param(typ.At(i))
+	}
+}
+
+func (w *writer) param(param *types2.Var) {
+	w.sync(syncParam)
+	w.pos(param)
+	w.localIdent(param)
+	w.typ(param.Type())
+}
+
+// @@@ Objects
+
+func (w *writer) obj(obj types2.Object, explicits *types2.TypeList) {
+	explicitInfos := make([]typeInfo, explicits.Len())
+	for i := range explicitInfos {
+		explicitInfos[i] = w.p.typIdx(explicits.At(i), w.dict)
+	}
+	info := objInfo{idx: w.p.objIdx(obj), explicits: explicitInfos}
+
+	if _, ok := obj.(*types2.Func); ok && info.anyDerived() {
+		idx := -1
+		for i, prev := range w.dict.funcs {
+			if prev.equals(info) {
+				idx = i
+			}
+		}
+		if idx < 0 {
+			idx = len(w.dict.funcs)
+			w.dict.funcs = append(w.dict.funcs, info)
+		}
+
+		// TODO(mdempsky): Push up into expr; this shouldn't appear
+		// outside of expression context.
+		w.sync(syncObject)
+		w.bool(true)
+		w.len(idx)
+		return
+	}
+
+	// TODO(mdempsky): Push up into typIdx; this shouldn't be needed
+	// except while writing out types.
+	if isDefinedType(obj) && obj.Pkg() == w.p.curpkg {
+		decl, ok := w.p.typDecls[obj.(*types2.TypeName)]
+		assert(ok)
+		if len(decl.implicits) != 0 {
+			w.derived = true
+		}
+	}
+
+	w.sync(syncObject)
+	w.bool(false)
+	w.reloc(relocObj, info.idx)
+
+	w.len(len(info.explicits))
+	for _, info := range info.explicits {
+		w.typInfo(info)
+	}
+}
+
+func (pw *pkgWriter) objIdx(obj types2.Object) int {
+	if idx, ok := pw.globalsIdx[obj]; ok {
+		return idx
+	}
+
+	dict := &writerDict{
+		derivedIdx: make(map[types2.Type]int),
+	}
+
+	if isDefinedType(obj) && obj.Pkg() == pw.curpkg {
+		decl, ok := pw.typDecls[obj.(*types2.TypeName)]
+		assert(ok)
+		dict.implicits = decl.implicits
+	}
+
+	w := pw.newWriter(relocObj, syncObject1)
+	w.ext = pw.newWriter(relocObjExt, syncObject1)
+	wname := pw.newWriter(relocName, syncObject1)
+	wdict := pw.newWriter(relocObjDict, syncObject1)
+
+	pw.globalsIdx[obj] = w.idx // break cycles
+	assert(w.ext.idx == w.idx)
+	assert(wname.idx == w.idx)
+	assert(wdict.idx == w.idx)
+
+	w.dict = dict
+	w.ext.dict = dict
+
+	code := w.doObj(obj)
+	w.flush()
+	w.ext.flush()
+
+	wname.qualifiedIdent(obj)
+	wname.code(code)
+	wname.flush()
+
+	wdict.objDict(obj, w.dict)
+	wdict.flush()
+
+	return w.idx
+}
+
+func (w *writer) doObj(obj types2.Object) codeObj {
+	if obj.Pkg() != w.p.curpkg {
+		return objStub
+	}
+
+	switch obj := obj.(type) {
+	default:
+		w.p.unexpected("object", obj)
+		panic("unreachable")
+
+	case *types2.Const:
+		w.pos(obj)
+		w.value(obj.Type(), obj.Val())
+		return objConst
+
+	case *types2.Func:
+		decl, ok := w.p.funDecls[obj]
+		assert(ok)
+		sig := obj.Type().(*types2.Signature)
+
+		w.pos(obj)
+		w.typeParamNames(sig.TParams())
+		w.signature(sig)
+		w.pos(decl)
+		w.ext.funcExt(obj)
+		return objFunc
+
+	case *types2.TypeName:
+		decl, ok := w.p.typDecls[obj]
+		assert(ok)
+
+		if obj.IsAlias() {
+			w.pos(obj)
+			w.typ(obj.Type())
+			return objAlias
+		}
+
+		named := obj.Type().(*types2.Named)
+		assert(named.TArgs() == nil)
+
+		w.pos(obj)
+		w.typeParamNames(named.TParams())
+		w.ext.typeExt(obj)
+		w.typExpr(decl.Type)
+
+		w.len(named.NumMethods())
+		for i := 0; i < named.NumMethods(); i++ {
+			w.method(named.Method(i))
+		}
+
+		return objType
+
+	case *types2.Var:
+		w.pos(obj)
+		w.typ(obj.Type())
+		w.ext.varExt(obj)
+		return objVar
+	}
+}
+
+// typExpr writes the type represented by the given expression.
+func (w *writer) typExpr(expr syntax.Expr) {
+	tv, ok := w.p.info.Types[expr]
+	assert(ok)
+	assert(tv.IsType())
+	w.typ(tv.Type)
+}
+
+func (w *writer) value(typ types2.Type, val constant.Value) {
+	w.sync(syncValue)
+	w.typ(typ)
+	w.rawValue(val)
+}
+
+// objDict writes the dictionary needed for reading the given object.
+func (w *writer) objDict(obj types2.Object, dict *writerDict) {
+	// TODO(mdempsky): Split objDict into multiple entries? reader.go
+	// doesn't care about the type parameter bounds, and reader2.go
+	// doesn't care about referenced functions.
+
+	w.dict = dict // TODO(mdempsky): This is a bit sketchy.
+
+	w.len(len(dict.implicits))
+
+	tparams := objTypeParams(obj)
+	ntparams := tparams.Len()
+	w.len(ntparams)
+	for i := 0; i < ntparams; i++ {
+		w.typ(tparams.At(i).Constraint())
+	}
+
+	nderived := len(dict.derived)
+	w.len(nderived)
+	for _, typ := range dict.derived {
+		w.reloc(relocType, typ.idx)
+		w.bool(typ.needed)
+	}
+
+	nfuncs := len(dict.funcs)
+	w.len(nfuncs)
+	for _, fn := range dict.funcs {
+		w.reloc(relocObj, fn.idx)
+		w.len(len(fn.explicits))
+		for _, targ := range fn.explicits {
+			w.typInfo(targ)
+		}
+	}
+
+	assert(len(dict.derived) == nderived)
+	assert(len(dict.funcs) == nfuncs)
+}
+
+func (w *writer) typeParamNames(tparams *types2.TParamList) {
+	w.sync(syncTypeParamNames)
+
+	ntparams := tparams.Len()
+	for i := 0; i < ntparams; i++ {
+		tparam := tparams.At(i).Obj()
+		w.pos(tparam)
+		w.localIdent(tparam)
+	}
+}
+
+func (w *writer) method(meth *types2.Func) {
+	decl, ok := w.p.funDecls[meth]
+	assert(ok)
+	sig := meth.Type().(*types2.Signature)
+
+	w.sync(syncMethod)
+	w.pos(meth)
+	w.selector(meth)
+	w.typeParamNames(sig.RParams())
+	w.param(sig.Recv())
+	w.signature(sig)
+
+	w.pos(decl) // XXX: Hack to workaround linker limitations.
+	w.ext.funcExt(meth)
+}
+
+// qualifiedIdent writes out the name of an object declared at package
+// scope. (For now, it's also used to refer to local defined types.)
+func (w *writer) qualifiedIdent(obj types2.Object) {
+	w.sync(syncSym)
+
+	name := obj.Name()
+	if isDefinedType(obj) && obj.Pkg() == w.p.curpkg {
+		decl, ok := w.p.typDecls[obj.(*types2.TypeName)]
+		assert(ok)
+		if decl.gen != 0 {
+			// TODO(mdempsky): Find a better solution than embedding middle
+			// dot in the symbol name; this is terrible.
+			name = fmt.Sprintf("%s·%v", name, decl.gen)
+		}
+	}
+
+	w.pkg(obj.Pkg())
+	w.string(name)
+}
+
+// TODO(mdempsky): We should be able to omit pkg from both localIdent
+// and selector, because they should always be known from context.
+// However, past frustrations with this optimization in iexport make
+// me a little nervous to try it again.
+
+// localIdent writes the name of a locally declared object (i.e.,
+// objects that can only be accessed by name, within the context of a
+// particular function).
+func (w *writer) localIdent(obj types2.Object) {
+	assert(!isGlobal(obj))
+	w.sync(syncLocalIdent)
+	w.pkg(obj.Pkg())
+	w.string(obj.Name())
+}
+
+// selector writes the name of a field or method (i.e., objects that
+// can only be accessed using selector expressions).
+func (w *writer) selector(obj types2.Object) {
+	w.sync(syncSelector)
+	w.pkg(obj.Pkg())
+	w.string(obj.Name())
+}
+
+// @@@ Compiler extensions
+
+func (w *writer) funcExt(obj *types2.Func) {
+	decl, ok := w.p.funDecls[obj]
+	assert(ok)
+
+	// TODO(mdempsky): Extend these pragma validation flags to account
+	// for generics. E.g., linkname probably doesn't make sense at
+	// least.
+
+	pragma := asPragmaFlag(decl.Pragma)
+	if pragma&ir.Systemstack != 0 && pragma&ir.Nosplit != 0 {
+		w.p.errorf(decl, "go:nosplit and go:systemstack cannot be combined")
+	}
+
+	if decl.Body != nil {
+		if pragma&ir.Noescape != 0 {
+			w.p.errorf(decl, "can only use //go:noescape with external func implementations")
+		}
+	} else {
+		if base.Flag.Complete || decl.Name.Value == "init" {
+			// Linknamed functions are allowed to have no body. Hopefully
+			// the linkname target has a body. See issue 23311.
+			if _, ok := w.p.linknames[obj]; !ok {
+				w.p.errorf(decl, "missing function body")
+			}
+		}
+	}
+
+	sig, block := obj.Type().(*types2.Signature), decl.Body
+	body, closureVars := w.p.bodyIdx(w.p.curpkg, sig, block, w.dict)
+	assert(len(closureVars) == 0)
+
+	w.sync(syncFuncExt)
+	w.pragmaFlag(pragma)
+	w.linkname(obj)
+	w.bool(false) // stub extension
+	w.reloc(relocBody, body)
+	w.sync(syncEOF)
+}
+
+func (w *writer) typeExt(obj *types2.TypeName) {
+	decl, ok := w.p.typDecls[obj]
+	assert(ok)
+
+	w.sync(syncTypeExt)
+
+	w.pragmaFlag(asPragmaFlag(decl.Pragma))
+
+	// No LSym.SymIdx info yet.
+	w.int64(-1)
+	w.int64(-1)
+}
+
+func (w *writer) varExt(obj *types2.Var) {
+	w.sync(syncVarExt)
+	w.linkname(obj)
+}
+
+func (w *writer) linkname(obj types2.Object) {
+	w.sync(syncLinkname)
+	w.int64(-1)
+	w.string(w.p.linknames[obj])
+}
+
+func (w *writer) pragmaFlag(p ir.PragmaFlag) {
+	w.sync(syncPragma)
+	w.int(int(p))
+}
+
+// @@@ Function bodies
+
+func (pw *pkgWriter) bodyIdx(pkg *types2.Package, sig *types2.Signature, block *syntax.BlockStmt, dict *writerDict) (idx int, closureVars []posObj) {
+	w := pw.newWriter(relocBody, syncFuncBody)
+	w.dict = dict
+
+	w.funcargs(sig)
+	if w.bool(block != nil) {
+		w.stmts(block.List)
+		w.pos(block.Rbrace)
+	}
+
+	return w.flush(), w.closureVars
+}
+
+func (w *writer) funcargs(sig *types2.Signature) {
+	do := func(params *types2.Tuple, result bool) {
+		for i := 0; i < params.Len(); i++ {
+			w.funcarg(params.At(i), result)
+		}
+	}
+
+	if recv := sig.Recv(); recv != nil {
+		w.funcarg(recv, false)
+	}
+	do(sig.Params(), false)
+	do(sig.Results(), true)
+}
+
+func (w *writer) funcarg(param *types2.Var, result bool) {
+	if param.Name() != "" || result {
+		w.addLocal(param)
+	}
+}
+
+func (w *writer) addLocal(obj *types2.Var) {
+	w.sync(syncAddLocal)
+	idx := len(w.localsIdx)
+	if enableSync {
+		w.int(idx)
+	}
+	if w.localsIdx == nil {
+		w.localsIdx = make(map[*types2.Var]int)
+	}
+	w.localsIdx[obj] = idx
+}
+
+func (w *writer) useLocal(pos syntax.Pos, obj *types2.Var) {
+	w.sync(syncUseObjLocal)
+
+	if idx, ok := w.localsIdx[obj]; w.bool(ok) {
+		w.len(idx)
+		return
+	}
+
+	idx, ok := w.closureVarsIdx[obj]
+	if !ok {
+		if w.closureVarsIdx == nil {
+			w.closureVarsIdx = make(map[*types2.Var]int)
+		}
+		idx = len(w.closureVars)
+		w.closureVars = append(w.closureVars, posObj{pos, obj})
+		w.closureVarsIdx[obj] = idx
+	}
+	w.len(idx)
+}
+
+func (w *writer) openScope(pos syntax.Pos) {
+	w.sync(syncOpenScope)
+	w.pos(pos)
+}
+
+func (w *writer) closeScope(pos syntax.Pos) {
+	w.sync(syncCloseScope)
+	w.pos(pos)
+	w.closeAnotherScope()
+}
+
+func (w *writer) closeAnotherScope() {
+	w.sync(syncCloseAnotherScope)
+}
+
+// @@@ Statements
+
+func (w *writer) stmt(stmt syntax.Stmt) {
+	var stmts []syntax.Stmt
+	if stmt != nil {
+		stmts = []syntax.Stmt{stmt}
+	}
+	w.stmts(stmts)
+}
+
+func (w *writer) stmts(stmts []syntax.Stmt) {
+	w.sync(syncStmts)
+	for _, stmt := range stmts {
+		w.stmt1(stmt)
+	}
+	w.code(stmtEnd)
+	w.sync(syncStmtsEnd)
+}
+
+func (w *writer) stmt1(stmt syntax.Stmt) {
+	switch stmt := stmt.(type) {
+	default:
+		w.p.unexpected("statement", stmt)
+
+	case nil, *syntax.EmptyStmt:
+		return
+
+	case *syntax.AssignStmt:
+		switch {
+		case stmt.Rhs == nil:
+			w.code(stmtIncDec)
+			w.op(binOps[stmt.Op])
+			w.expr(stmt.Lhs)
+			w.pos(stmt)
+
+		case stmt.Op != 0 && stmt.Op != syntax.Def:
+			w.code(stmtAssignOp)
+			w.op(binOps[stmt.Op])
+			w.expr(stmt.Lhs)
+			w.pos(stmt)
+			w.expr(stmt.Rhs)
+
+		default:
+			w.code(stmtAssign)
+			w.pos(stmt)
+			w.exprList(stmt.Rhs)
+			w.assignList(stmt.Lhs)
+		}
+
+	case *syntax.BlockStmt:
+		w.code(stmtBlock)
+		w.blockStmt(stmt)
+
+	case *syntax.BranchStmt:
+		w.code(stmtBranch)
+		w.pos(stmt)
+		w.op(branchOps[stmt.Tok])
+		w.optLabel(stmt.Label)
+
+	case *syntax.CallStmt:
+		w.code(stmtCall)
+		w.pos(stmt)
+		w.op(callOps[stmt.Tok])
+		w.expr(stmt.Call)
+
+	case *syntax.DeclStmt:
+		for _, decl := range stmt.DeclList {
+			w.declStmt(decl)
+		}
+
+	case *syntax.ExprStmt:
+		w.code(stmtExpr)
+		w.expr(stmt.X)
+
+	case *syntax.ForStmt:
+		w.code(stmtFor)
+		w.forStmt(stmt)
+
+	case *syntax.IfStmt:
+		w.code(stmtIf)
+		w.ifStmt(stmt)
+
+	case *syntax.LabeledStmt:
+		w.code(stmtLabel)
+		w.pos(stmt)
+		w.label(stmt.Label)
+		w.stmt1(stmt.Stmt)
+
+	case *syntax.ReturnStmt:
+		w.code(stmtReturn)
+		w.pos(stmt)
+		w.exprList(stmt.Results)
+
+	case *syntax.SelectStmt:
+		w.code(stmtSelect)
+		w.selectStmt(stmt)
+
+	case *syntax.SendStmt:
+		w.code(stmtSend)
+		w.pos(stmt)
+		w.expr(stmt.Chan)
+		w.expr(stmt.Value)
+
+	case *syntax.SwitchStmt:
+		w.code(stmtSwitch)
+		w.switchStmt(stmt)
+	}
+}
+
+func (w *writer) assignList(expr syntax.Expr) {
+	exprs := unpackListExpr(expr)
+	w.len(len(exprs))
+
+	for _, expr := range exprs {
+		if name, ok := expr.(*syntax.Name); ok && name.Value != "_" {
+			if obj, ok := w.p.info.Defs[name]; ok {
+				obj := obj.(*types2.Var)
+
+				w.bool(true)
+				w.pos(obj)
+				w.localIdent(obj)
+				w.typ(obj.Type())
+
+				// TODO(mdempsky): Minimize locals index size by deferring
+				// this until the variables actually come into scope.
+				w.addLocal(obj)
+				continue
+			}
+		}
+
+		w.bool(false)
+		w.expr(expr)
+	}
+}
+
+func (w *writer) declStmt(decl syntax.Decl) {
+	switch decl := decl.(type) {
+	default:
+		w.p.unexpected("declaration", decl)
+
+	case *syntax.ConstDecl:
+
+	case *syntax.TypeDecl:
+		// Quirk: The legacy inliner doesn't support inlining functions
+		// with type declarations. Unified IR doesn't have any need to
+		// write out type declarations explicitly (they're always looked
+		// up via global index tables instead), so we just write out a
+		// marker so the reader knows to synthesize a fake declaration to
+		// prevent inlining.
+		if quirksMode() {
+			w.code(stmtTypeDeclHack)
+		}
+
+	case *syntax.VarDecl:
+		values := unpackListExpr(decl.Values)
+
+		// Quirk: When N variables are declared with N initialization
+		// values, we need to decompose that into N interleaved
+		// declarations+initializations, because it leads to different
+		// (albeit semantically equivalent) code generation.
+		if quirksMode() && len(decl.NameList) == len(values) {
+			for i, name := range decl.NameList {
+				w.code(stmtAssign)
+				w.pos(decl)
+				w.exprList(values[i])
+				w.assignList(name)
+			}
+			break
+		}
+
+		w.code(stmtAssign)
+		w.pos(decl)
+		w.exprList(decl.Values)
+		w.assignList(namesAsExpr(decl.NameList))
+	}
+}
+
+func (w *writer) blockStmt(stmt *syntax.BlockStmt) {
+	w.sync(syncBlockStmt)
+	w.openScope(stmt.Pos())
+	w.stmts(stmt.List)
+	w.closeScope(stmt.Rbrace)
+}
+
+func (w *writer) forStmt(stmt *syntax.ForStmt) {
+	w.sync(syncForStmt)
+	w.openScope(stmt.Pos())
+
+	if rang, ok := stmt.Init.(*syntax.RangeClause); w.bool(ok) {
+		w.pos(rang)
+		w.expr(rang.X)
+		w.assignList(rang.Lhs)
+	} else {
+		w.pos(stmt)
+		w.stmt(stmt.Init)
+		w.expr(stmt.Cond)
+		w.stmt(stmt.Post)
+	}
+
+	w.blockStmt(stmt.Body)
+	w.closeAnotherScope()
+}
+
+func (w *writer) ifStmt(stmt *syntax.IfStmt) {
+	w.sync(syncIfStmt)
+	w.openScope(stmt.Pos())
+	w.pos(stmt)
+	w.stmt(stmt.Init)
+	w.expr(stmt.Cond)
+	w.blockStmt(stmt.Then)
+	w.stmt(stmt.Else)
+	w.closeAnotherScope()
+}
+
+func (w *writer) selectStmt(stmt *syntax.SelectStmt) {
+	w.sync(syncSelectStmt)
+
+	w.pos(stmt)
+	w.len(len(stmt.Body))
+	for i, clause := range stmt.Body {
+		if i > 0 {
+			w.closeScope(clause.Pos())
+		}
+		w.openScope(clause.Pos())
+
+		w.pos(clause)
+		w.stmt(clause.Comm)
+		w.stmts(clause.Body)
+	}
+	if len(stmt.Body) > 0 {
+		w.closeScope(stmt.Rbrace)
+	}
+}
+
+func (w *writer) switchStmt(stmt *syntax.SwitchStmt) {
+	w.sync(syncSwitchStmt)
+
+	w.openScope(stmt.Pos())
+	w.pos(stmt)
+	w.stmt(stmt.Init)
+
+	if guard, ok := stmt.Tag.(*syntax.TypeSwitchGuard); w.bool(ok) {
+		w.pos(guard)
+		if tag := guard.Lhs; w.bool(tag != nil) {
+			w.pos(tag)
+			w.string(tag.Value)
+		}
+		w.expr(guard.X)
+	} else {
+		w.expr(stmt.Tag)
+	}
+
+	w.len(len(stmt.Body))
+	for i, clause := range stmt.Body {
+		if i > 0 {
+			w.closeScope(clause.Pos())
+		}
+		w.openScope(clause.Pos())
+
+		w.pos(clause)
+		w.exprList(clause.Cases)
+
+		if obj, ok := w.p.info.Implicits[clause]; ok {
+			// TODO(mdempsky): These pos details are quirkish, but also
+			// necessary so the variable's position is correct for DWARF
+			// scope assignment later. It would probably be better for us to
+			// instead just set the variable's DWARF scoping info earlier so
+			// we can give it the correct position information.
+			pos := clause.Pos()
+			if typs := unpackListExpr(clause.Cases); len(typs) != 0 {
+				pos = typeExprEndPos(typs[len(typs)-1])
+			}
+			w.pos(pos)
+
+			obj := obj.(*types2.Var)
+			w.typ(obj.Type())
+			w.addLocal(obj)
+		}
+
+		w.stmts(clause.Body)
+	}
+	if len(stmt.Body) > 0 {
+		w.closeScope(stmt.Rbrace)
+	}
+
+	w.closeScope(stmt.Rbrace)
+}
+
+func (w *writer) label(label *syntax.Name) {
+	w.sync(syncLabel)
+
+	// TODO(mdempsky): Replace label strings with dense indices.
+	w.string(label.Value)
+}
+
+func (w *writer) optLabel(label *syntax.Name) {
+	w.sync(syncOptLabel)
+	if w.bool(label != nil) {
+		w.label(label)
+	}
+}
+
+// @@@ Expressions
+
+func (w *writer) expr(expr syntax.Expr) {
+	expr = unparen(expr) // skip parens; unneeded after typecheck
+
+	obj, targs := lookupObj(w.p.info, expr)
+
+	if tv, ok := w.p.info.Types[expr]; ok {
+		// TODO(mdempsky): Be more judicious about which types are marked as "needed".
+		w.needType(tv.Type)
+
+		if tv.IsType() {
+			w.code(exprType)
+			w.typ(tv.Type)
+			return
+		}
+
+		if tv.Value != nil {
+			pos := expr.Pos()
+			if quirksMode() {
+				if obj != nil {
+					// Quirk: IR (and thus iexport) doesn't track position
+					// information for uses of declared objects.
+					pos = syntax.Pos{}
+				} else if tv.Value.Kind() == constant.String {
+					// Quirk: noder.sum picks a particular position for certain
+					// string concatenations.
+					pos = sumPos(expr)
+				}
+			}
+
+			w.code(exprConst)
+			w.pos(pos)
+			w.value(tv.Type, tv.Value)
+
+			// TODO(mdempsky): These details are only important for backend
+			// diagnostics. Explore writing them out separately.
+			w.op(constExprOp(expr))
+			w.string(syntax.String(expr))
+			return
+		}
+	}
+
+	if obj != nil {
+		if isGlobal(obj) {
+			w.code(exprName)
+			w.obj(obj, targs)
+			return
+		}
+
+		obj := obj.(*types2.Var)
+		assert(targs.Len() == 0)
+
+		w.code(exprLocal)
+		w.useLocal(expr.Pos(), obj)
+		return
+	}
+
+	switch expr := expr.(type) {
+	default:
+		w.p.unexpected("expression", expr)
+
+	case nil: // absent slice index, for condition, or switch tag
+		w.code(exprNone)
+
+	case *syntax.Name:
+		assert(expr.Value == "_")
+		w.code(exprBlank)
+
+	case *syntax.CompositeLit:
+		w.code(exprCompLit)
+		w.compLit(expr)
+
+	case *syntax.FuncLit:
+		w.code(exprFuncLit)
+		w.funcLit(expr)
+
+	case *syntax.SelectorExpr:
+		sel, ok := w.p.info.Selections[expr]
+		assert(ok)
+
+		w.code(exprSelector)
+		w.expr(expr.X)
+		w.pos(expr)
+		w.selector(sel.Obj())
+
+	case *syntax.IndexExpr:
+		tv, ok := w.p.info.Types[expr.Index]
+		assert(ok && tv.IsValue())
+
+		w.code(exprIndex)
+		w.expr(expr.X)
+		w.pos(expr)
+		w.expr(expr.Index)
+
+	case *syntax.SliceExpr:
+		w.code(exprSlice)
+		w.expr(expr.X)
+		w.pos(expr)
+		for _, n := range &expr.Index {
+			w.expr(n)
+		}
+
+	case *syntax.AssertExpr:
+		w.code(exprAssert)
+		w.expr(expr.X)
+		w.pos(expr)
+		w.expr(expr.Type)
+
+	case *syntax.Operation:
+		if expr.Y == nil {
+			w.code(exprUnaryOp)
+			w.op(unOps[expr.Op])
+			w.pos(expr)
+			w.expr(expr.X)
+			break
+		}
+
+		w.code(exprBinaryOp)
+		w.op(binOps[expr.Op])
+		w.expr(expr.X)
+		w.pos(expr)
+		w.expr(expr.Y)
+
+	case *syntax.CallExpr:
+		tv, ok := w.p.info.Types[expr.Fun]
+		assert(ok)
+		if tv.IsType() {
+			assert(len(expr.ArgList) == 1)
+			assert(!expr.HasDots)
+
+			w.code(exprConvert)
+			w.typ(tv.Type)
+			w.pos(expr)
+			w.expr(expr.ArgList[0])
+			break
+		}
+
+		writeFunExpr := func() {
+			if selector, ok := unparen(expr.Fun).(*syntax.SelectorExpr); ok {
+				if sel, ok := w.p.info.Selections[selector]; ok && sel.Kind() == types2.MethodVal {
+					w.expr(selector.X)
+					w.bool(true) // method call
+					w.pos(selector)
+					w.selector(sel.Obj())
+					return
+				}
+			}
+
+			if inf, ok := w.p.info.Inferred[expr]; ok {
+				obj, _ := lookupObj(w.p.info, expr.Fun)
+				assert(obj != nil)
+
+				// As if w.expr(expr.Fun), but using inf.TArgs instead.
+				w.code(exprName)
+				w.obj(obj, inf.TArgs)
+			} else {
+				w.expr(expr.Fun)
+			}
+			w.bool(false) // not a method call (i.e., normal function call)
+		}
+
+		w.code(exprCall)
+		writeFunExpr()
+		w.pos(expr)
+		w.exprs(expr.ArgList)
+		w.bool(expr.HasDots)
+	}
+}
+
+func (w *writer) compLit(lit *syntax.CompositeLit) {
+	tv, ok := w.p.info.Types[lit]
+	assert(ok)
+
+	w.sync(syncCompLit)
+	w.pos(lit)
+	w.typ(tv.Type)
+
+	typ := tv.Type
+	if ptr, ok := typ.Underlying().(*types2.Pointer); ok {
+		typ = ptr.Elem()
+	}
+	str, isStruct := typ.Underlying().(*types2.Struct)
+
+	w.len(len(lit.ElemList))
+	for i, elem := range lit.ElemList {
+		if isStruct {
+			if kv, ok := elem.(*syntax.KeyValueExpr); ok {
+				// use position of expr.Key rather than of elem (which has position of ':')
+				w.pos(kv.Key)
+				w.len(fieldIndex(w.p.info, str, kv.Key.(*syntax.Name)))
+				elem = kv.Value
+			} else {
+				w.pos(elem)
+				w.len(i)
+			}
+		} else {
+			if kv, ok := elem.(*syntax.KeyValueExpr); w.bool(ok) {
+				// use position of expr.Key rather than of elem (which has position of ':')
+				w.pos(kv.Key)
+				w.expr(kv.Key)
+				elem = kv.Value
+			}
+		}
+		w.pos(elem)
+		w.expr(elem)
+	}
+}
+
+func (w *writer) funcLit(expr *syntax.FuncLit) {
+	tv, ok := w.p.info.Types[expr]
+	assert(ok)
+	sig := tv.Type.(*types2.Signature)
+
+	body, closureVars := w.p.bodyIdx(w.p.curpkg, sig, expr.Body, w.dict)
+
+	w.sync(syncFuncLit)
+	w.pos(expr)
+	w.pos(expr.Type) // for QuirksMode
+	w.signature(sig)
+
+	w.len(len(closureVars))
+	for _, cv := range closureVars {
+		w.pos(cv.pos)
+		if quirksMode() {
+			cv.pos = expr.Body.Rbrace
+		}
+		w.useLocal(cv.pos, cv.obj)
+	}
+
+	w.reloc(relocBody, body)
+}
+
+type posObj struct {
+	pos syntax.Pos
+	obj *types2.Var
+}
+
+func (w *writer) exprList(expr syntax.Expr) {
+	w.sync(syncExprList)
+	w.exprs(unpackListExpr(expr))
+}
+
+func (w *writer) exprs(exprs []syntax.Expr) {
+	if len(exprs) == 0 {
+		assert(exprs == nil)
+	}
+
+	w.sync(syncExprs)
+	w.len(len(exprs))
+	for _, expr := range exprs {
+		w.expr(expr)
+	}
+}
+
+func (w *writer) op(op ir.Op) {
+	// TODO(mdempsky): Remove in favor of explicit codes? Would make
+	// export data more stable against internal refactorings, but low
+	// priority at the moment.
+	assert(op != 0)
+	w.sync(syncOp)
+	w.len(int(op))
+}
+
+func (w *writer) needType(typ types2.Type) {
+	// Decompose tuple into component element types.
+	if typ, ok := typ.(*types2.Tuple); ok {
+		for i := 0; i < typ.Len(); i++ {
+			w.needType(typ.At(i).Type())
+		}
+		return
+	}
+
+	if info := w.p.typIdx(typ, w.dict); info.derived {
+		w.dict.derived[info.idx].needed = true
+	}
+}
+
+// @@@ Package initialization
+
+// Caution: This code is still clumsy, because toolstash -cmp is
+// particularly sensitive to it.
+
+type typeDeclGen struct {
+	*syntax.TypeDecl
+	gen int
+
+	// Implicit type parameters in scope at this type declaration.
+	implicits []*types2.TypeName
+}
+
+type fileImports struct {
+	importedEmbed, importedUnsafe bool
+}
+
+type declCollector struct {
+	pw         *pkgWriter
+	typegen    *int
+	file       *fileImports
+	withinFunc bool
+	implicits  []*types2.TypeName
+}
+
+func (c *declCollector) withTParams(obj types2.Object) *declCollector {
+	tparams := objTypeParams(obj)
+	n := tparams.Len()
+	if n == 0 {
+		return c
+	}
+
+	copy := *c
+	copy.implicits = copy.implicits[:len(copy.implicits):len(copy.implicits)]
+	for i := 0; i < n; i++ {
+		copy.implicits = append(copy.implicits, tparams.At(i).Obj())
+	}
+	return ©
+}
+
+func (c *declCollector) Visit(n syntax.Node) syntax.Visitor {
+	pw := c.pw
+
+	switch n := n.(type) {
+	case *syntax.File:
+		pw.checkPragmas(n.Pragma, ir.GoBuildPragma, false)
+
+	case *syntax.ImportDecl:
+		pw.checkPragmas(n.Pragma, 0, false)
+
+		switch pkgNameOf(pw.info, n).Imported().Path() {
+		case "embed":
+			c.file.importedEmbed = true
+		case "unsafe":
+			c.file.importedUnsafe = true
+		}
+
+	case *syntax.ConstDecl:
+		pw.checkPragmas(n.Pragma, 0, false)
+
+	case *syntax.FuncDecl:
+		pw.checkPragmas(n.Pragma, funcPragmas, false)
+
+		obj := pw.info.Defs[n.Name].(*types2.Func)
+		pw.funDecls[obj] = n
+
+		return c.withTParams(obj)
+
+	case *syntax.TypeDecl:
+		obj := pw.info.Defs[n.Name].(*types2.TypeName)
+		d := typeDeclGen{TypeDecl: n, implicits: c.implicits}
+
+		if n.Alias {
+			pw.checkPragmas(n.Pragma, 0, false)
+		} else {
+			pw.checkPragmas(n.Pragma, typePragmas, false)
+
+			// Assign a unique ID to function-scoped defined types.
+			if c.withinFunc {
+				*c.typegen++
+				d.gen = *c.typegen
+			}
+		}
+
+		pw.typDecls[obj] = d
+
+		// TODO(mdempsky): Omit? Not strictly necessary; only matters for
+		// type declarations within function literals within parameterized
+		// type declarations, but types2 the function literals will be
+		// constant folded away.
+		return c.withTParams(obj)
+
+	case *syntax.VarDecl:
+		pw.checkPragmas(n.Pragma, 0, true)
+
+		if p, ok := n.Pragma.(*pragmas); ok && len(p.Embeds) > 0 {
+			if err := checkEmbed(n, c.file.importedEmbed, c.withinFunc); err != nil {
+				pw.errorf(p.Embeds[0].Pos, "%s", err)
+			}
+		}
+
+		// Workaround for #46208. For variable declarations that
+		// declare multiple variables and have an explicit type
+		// expression, the type expression is evaluated multiple
+		// times. This affects toolstash -cmp, because iexport is
+		// sensitive to *types.Type pointer identity.
+		if quirksMode() && n.Type != nil {
+			tv, ok := pw.info.Types[n.Type]
+			assert(ok)
+			assert(tv.IsType())
+			for _, name := range n.NameList {
+				obj := pw.info.Defs[name].(*types2.Var)
+				pw.dups.add(obj.Type(), tv.Type)
+			}
+		}
+
+	case *syntax.BlockStmt:
+		if !c.withinFunc {
+			copy := *c
+			copy.withinFunc = true
+			return ©
+		}
+	}
+
+	return c
+}
+
+func (pw *pkgWriter) collectDecls(noders []*noder) {
+	var typegen int
+	for _, p := range noders {
+		var file fileImports
+
+		syntax.Walk(p.file, &declCollector{
+			pw:      pw,
+			typegen: &typegen,
+			file:    &file,
+		})
+
+		pw.cgoPragmas = append(pw.cgoPragmas, p.pragcgobuf...)
+
+		for _, l := range p.linknames {
+			if !file.importedUnsafe {
+				pw.errorf(l.pos, "//go:linkname only allowed in Go files that import \"unsafe\"")
+				continue
+			}
+
+			switch obj := pw.curpkg.Scope().Lookup(l.local).(type) {
+			case *types2.Func, *types2.Var:
+				if _, ok := pw.linknames[obj]; !ok {
+					pw.linknames[obj] = l.remote
+				} else {
+					pw.errorf(l.pos, "duplicate //go:linkname for %s", l.local)
+				}
+
+			default:
+				// TODO(mdempsky): Enable after #42938 is fixed.
+				if false {
+					pw.errorf(l.pos, "//go:linkname must refer to declared function or variable")
+				}
+			}
+		}
+	}
+}
+
+func (pw *pkgWriter) checkPragmas(p syntax.Pragma, allowed ir.PragmaFlag, embedOK bool) {
+	if p == nil {
+		return
+	}
+	pragma := p.(*pragmas)
+
+	for _, pos := range pragma.Pos {
+		if pos.Flag&^allowed != 0 {
+			pw.errorf(pos.Pos, "misplaced compiler directive")
+		}
+	}
+
+	if !embedOK {
+		for _, e := range pragma.Embeds {
+			pw.errorf(e.Pos, "misplaced go:embed directive")
+		}
+	}
+}
+
+func (w *writer) pkgInit(noders []*noder) {
+	if quirksMode() {
+		posBases := posBasesOf(noders)
+		w.len(len(posBases))
+		for _, posBase := range posBases {
+			w.posBase(posBase)
+		}
+
+		objs := importedObjsOf(w.p.curpkg, w.p.info, noders)
+		w.len(len(objs))
+		for _, obj := range objs {
+			w.qualifiedIdent(obj)
+		}
+	}
+
+	w.len(len(w.p.cgoPragmas))
+	for _, cgoPragma := range w.p.cgoPragmas {
+		w.strings(cgoPragma)
+	}
+
+	w.sync(syncDecls)
+	for _, p := range noders {
+		for _, decl := range p.file.DeclList {
+			w.pkgDecl(decl)
+		}
+	}
+	w.code(declEnd)
+
+	w.sync(syncEOF)
+}
+
+func (w *writer) pkgDecl(decl syntax.Decl) {
+	switch decl := decl.(type) {
+	default:
+		w.p.unexpected("declaration", decl)
+
+	case *syntax.ImportDecl:
+
+	case *syntax.ConstDecl:
+		w.code(declOther)
+		w.pkgObjs(decl.NameList...)
+
+	case *syntax.FuncDecl:
+		if decl.Name.Value == "_" {
+			break // skip blank functions
+		}
+
+		obj := w.p.info.Defs[decl.Name].(*types2.Func)
+		sig := obj.Type().(*types2.Signature)
+
+		if sig.RParams() != nil || sig.TParams() != nil {
+			break // skip generic functions
+		}
+
+		if recv := sig.Recv(); recv != nil {
+			w.code(declMethod)
+			w.typ(recvBase(recv))
+			w.selector(obj)
+			break
+		}
+
+		w.code(declFunc)
+		w.pkgObjs(decl.Name)
+
+	case *syntax.TypeDecl:
+		if len(decl.TParamList) != 0 {
+			break // skip generic type decls
+		}
+
+		if decl.Name.Value == "_" {
+			break // skip blank type decls
+		}
+
+		name := w.p.info.Defs[decl.Name].(*types2.TypeName)
+		// Skip type declarations for interfaces that are only usable as
+		// type parameter bounds.
+		if iface, ok := name.Type().Underlying().(*types2.Interface); ok && iface.IsConstraint() {
+			break
+		}
+
+		// Skip aliases to uninstantiated generic types.
+		// TODO(mdempsky): Revisit after #46477 is resolved.
+		if name.IsAlias() {
+			named, ok := name.Type().(*types2.Named)
+			if ok && named.TParams().Len() != 0 && named.TArgs().Len() == 0 {
+				break
+			}
+		}
+
+		w.code(declOther)
+		w.pkgObjs(decl.Name)
+
+	case *syntax.VarDecl:
+		w.code(declVar)
+		w.pos(decl)
+		w.pkgObjs(decl.NameList...)
+		w.exprList(decl.Values)
+
+		var embeds []pragmaEmbed
+		if p, ok := decl.Pragma.(*pragmas); ok {
+			embeds = p.Embeds
+		}
+		w.len(len(embeds))
+		for _, embed := range embeds {
+			w.pos(embed.Pos)
+			w.strings(embed.Patterns)
+		}
+	}
+}
+
+func (w *writer) pkgObjs(names ...*syntax.Name) {
+	w.sync(syncDeclNames)
+	w.len(len(names))
+
+	for _, name := range names {
+		obj, ok := w.p.info.Defs[name]
+		assert(ok)
+
+		w.sync(syncDeclName)
+		w.obj(obj, nil)
+	}
+}
+
+// @@@ Helpers
+
+// isDefinedType reports whether obj is a defined type.
+func isDefinedType(obj types2.Object) bool {
+	if obj, ok := obj.(*types2.TypeName); ok {
+		return !obj.IsAlias()
+	}
+	return false
+}
+
+// isGlobal reports whether obj was declared at package scope.
+//
+// Caveat: blank objects are not declared.
+func isGlobal(obj types2.Object) bool {
+	return obj.Parent() == obj.Pkg().Scope()
+}
+
+// lookupObj returns the object that expr refers to, if any. If expr
+// is an explicit instantiation of a generic object, then the type
+// arguments are returned as well.
+func lookupObj(info *types2.Info, expr syntax.Expr) (obj types2.Object, targs *types2.TypeList) {
+	if index, ok := expr.(*syntax.IndexExpr); ok {
+		if inf, ok := info.Inferred[index]; ok {
+			targs = inf.TArgs
+		} else {
+			args := unpackListExpr(index.Index)
+
+			if len(args) == 1 {
+				tv, ok := info.Types[args[0]]
+				assert(ok)
+				if tv.IsValue() {
+					return // normal index expression
+				}
+			}
+
+			list := make([]types2.Type, len(args))
+			for i, arg := range args {
+				tv, ok := info.Types[arg]
+				assert(ok)
+				assert(tv.IsType())
+				list[i] = tv.Type
+			}
+			targs = types2.NewTypeList(list)
+		}
+
+		expr = index.X
+	}
+
+	// Strip package qualifier, if present.
+	if sel, ok := expr.(*syntax.SelectorExpr); ok {
+		if !isPkgQual(info, sel) {
+			return // normal selector expression
+		}
+		expr = sel.Sel
+	}
+
+	if name, ok := expr.(*syntax.Name); ok {
+		obj, _ = info.Uses[name]
+	}
+	return
+}
+
+// isPkgQual reports whether the given selector expression is a
+// package-qualified identifier.
+func isPkgQual(info *types2.Info, sel *syntax.SelectorExpr) bool {
+	if name, ok := sel.X.(*syntax.Name); ok {
+		_, isPkgName := info.Uses[name].(*types2.PkgName)
+		return isPkgName
+	}
+	return false
+}
+
+// recvBase returns the base type for the given receiver parameter.
+func recvBase(recv *types2.Var) *types2.Named {
+	typ := recv.Type()
+	if ptr, ok := typ.(*types2.Pointer); ok {
+		typ = ptr.Elem()
+	}
+	return typ.(*types2.Named)
+}
+
+// namesAsExpr returns a list of names as a syntax.Expr.
+func namesAsExpr(names []*syntax.Name) syntax.Expr {
+	if len(names) == 1 {
+		return names[0]
+	}
+
+	exprs := make([]syntax.Expr, len(names))
+	for i, name := range names {
+		exprs[i] = name
+	}
+	return &syntax.ListExpr{ElemList: exprs}
+}
+
+// fieldIndex returns the index of the struct field named by key.
+func fieldIndex(info *types2.Info, str *types2.Struct, key *syntax.Name) int {
+	field := info.Uses[key].(*types2.Var)
+
+	for i := 0; i < str.NumFields(); i++ {
+		if str.Field(i) == field {
+			return i
+		}
+	}
+
+	panic(fmt.Sprintf("%s: %v is not a field of %v", key.Pos(), field, str))
+}
+
+// objTypeParams returns the type parameters on the given object.
+func objTypeParams(obj types2.Object) *types2.TParamList {
+	switch obj := obj.(type) {
+	case *types2.Func:
+		sig := obj.Type().(*types2.Signature)
+		if sig.Recv() != nil {
+			return sig.RParams()
+		}
+		return sig.TParams()
+	case *types2.TypeName:
+		if !obj.IsAlias() {
+			return obj.Type().(*types2.Named).TParams()
+		}
+	}
+	return nil
+}
+
+func asPragmaFlag(p syntax.Pragma) ir.PragmaFlag {
+	if p == nil {
+		return 0
+	}
+	return p.(*pragmas).Flag
+}
diff --git a/src/cmd/compile/internal/pkginit/initorder.go b/src/cmd/compile/internal/pkginit/initorder.go
index 97d69629fbae9e5167ec68abe39c9264a8c979cc..0aad63a69f6b05fa6c9a41a5c5fb65d9cf092d16 100644
--- a/src/cmd/compile/internal/pkginit/initorder.go
+++ b/src/cmd/compile/internal/pkginit/initorder.go
@@ -304,7 +304,7 @@ func (d *initDeps) visit(n ir.Node) {
 		n := n.(*ir.ClosureExpr)
 		d.inspectList(n.Func.Body)
 
-	case ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
+	case ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
 		d.foundDep(ir.MethodExprName(n))
 	}
 }
diff --git a/src/cmd/compile/internal/ppc64/galign.go b/src/cmd/compile/internal/ppc64/galign.go
index 590290fa371008db507ade8df55c54b4bc160f69..bff3e38f42dfef97e9b7013ffa1f93cbbfb568f6 100644
--- a/src/cmd/compile/internal/ppc64/galign.go
+++ b/src/cmd/compile/internal/ppc64/galign.go
@@ -20,7 +20,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnopdefer
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ppc64/ggen.go b/src/cmd/compile/internal/ppc64/ggen.go
index c76962cfb811334d577ffc49b427533f0a8517b8..3ae6422bf9e26b0a1fb08e1f94f3a17a8965d3f1 100644
--- a/src/cmd/compile/internal/ppc64/ggen.go
+++ b/src/cmd/compile/internal/ppc64/ggen.go
@@ -53,30 +53,3 @@ func ginsnop(pp *objw.Progs) *obj.Prog {
 	p.To.Reg = ppc64.REG_R0
 	return p
 }
-
-func ginsnopdefer(pp *objw.Progs) *obj.Prog {
-	// On PPC64 two nops are required in the defer case.
-	//
-	// (see gc/cgen.go, gc/plive.go -- copy of comment below)
-	//
-	// On ppc64, when compiling Go into position
-	// independent code on ppc64le we insert an
-	// instruction to reload the TOC pointer from the
-	// stack as well. See the long comment near
-	// jmpdefer in runtime/asm_ppc64.s for why.
-	// If the MOVD is not needed, insert a hardware NOP
-	// so that the same number of instructions are used
-	// on ppc64 in both shared and non-shared modes.
-
-	ginsnop(pp)
-	if base.Ctxt.Flag_shared {
-		p := pp.Prog(ppc64.AMOVD)
-		p.From.Type = obj.TYPE_MEM
-		p.From.Offset = 24
-		p.From.Reg = ppc64.REGSP
-		p.To.Type = obj.TYPE_REG
-		p.To.Reg = ppc64.REG_R2
-		return p
-	}
-	return ginsnop(pp)
-}
diff --git a/src/cmd/compile/internal/reflectdata/alg.go b/src/cmd/compile/internal/reflectdata/alg.go
index 0707e0b61caf4861033d424acc525d028a2bf484..36ad389647ff984c4f7fa026644ea60a8aad47fd 100644
--- a/src/cmd/compile/internal/reflectdata/alg.go
+++ b/src/cmd/compile/internal/reflectdata/alg.go
@@ -679,8 +679,7 @@ func EqString(s, t ir.Node) (eqlen *ir.BinaryExpr, eqmem *ir.CallExpr) {
 
 	fn := typecheck.LookupRuntime("memequal")
 	fn = typecheck.SubstArgTypes(fn, types.Types[types.TUINT8], types.Types[types.TUINT8])
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, []ir.Node{sptr, tptr, ir.Copy(slen)})
-	typecheck.Call(call)
+	call := typecheck.Call(base.Pos, fn, []ir.Node{sptr, tptr, ir.Copy(slen)}, false).(*ir.CallExpr)
 
 	cmp := ir.NewBinaryExpr(base.Pos, ir.OEQ, slen, tlen)
 	cmp = typecheck.Expr(cmp).(*ir.BinaryExpr)
@@ -716,8 +715,7 @@ func EqInterface(s, t ir.Node) (eqtab *ir.BinaryExpr, eqdata *ir.CallExpr) {
 	sdata.SetTypecheck(1)
 	tdata.SetTypecheck(1)
 
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, []ir.Node{stab, sdata, tdata})
-	typecheck.Call(call)
+	call := typecheck.Call(base.Pos, fn, []ir.Node{stab, sdata, tdata}, false).(*ir.CallExpr)
 
 	cmp := ir.NewBinaryExpr(base.Pos, ir.OEQ, stab, ttab)
 	cmp = typecheck.Expr(cmp).(*ir.BinaryExpr)
diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index eb9a8a6c9bc73ade1974d19e63cdbe225224935f..9b9efe04a2e1309ed8bb167fca4d55374942fc77 100644
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -28,35 +28,27 @@ import (
 	"cmd/internal/src"
 )
 
-type itabEntry struct {
-	t, itype *types.Type
-	lsym     *obj.LSym // symbol of the itab itself
-
-	// symbols of each method in
-	// the itab, sorted by byte offset;
-	// filled in by CompileITabs
-	entries []*obj.LSym
-}
-
 type ptabEntry struct {
 	s *types.Sym
 	t *types.Type
 }
 
-func CountTabs() (numPTabs, numITabs int) {
-	return len(ptabs), len(itabs)
+func CountPTabs() int {
+	return len(ptabs)
 }
 
 // runtime interface and reflection data structures
 var (
-	signatmu    sync.Mutex // protects signatset and signatslice
-	signatset   = make(map[*types.Type]struct{})
-	signatslice []*types.Type
+	// protects signatset and signatslice
+	signatmu sync.Mutex
+	// Tracking which types need runtime type descriptor
+	signatset = make(map[*types.Type]struct{})
+	// Queue of types wait to be generated runtime type descriptor
+	signatslice []typeAndStr
 
 	gcsymmu  sync.Mutex // protects gcsymset and gcsymslice
 	gcsymset = make(map[*types.Type]struct{})
 
-	itabs []itabEntry
 	ptabs []*ir.Name
 )
 
@@ -313,6 +305,10 @@ func MapIterType(t *types.Type) *types.Type {
 // methods returns the methods of the non-interface type t, sorted by name.
 // Generates stub functions as needed.
 func methods(t *types.Type) []*typeSig {
+	if t.HasShape() {
+		// Shape types have no methods.
+		return nil
+	}
 	// method type
 	mt := types.ReceiverBaseType(t)
 
@@ -321,13 +317,6 @@ func methods(t *types.Type) []*typeSig {
 	}
 	typecheck.CalcMethods(mt)
 
-	// type stored in interface word
-	it := t
-
-	if !types.IsDirectIface(it) {
-		it = types.NewPtr(t)
-	}
-
 	// make list of methods for t,
 	// generating code if necessary.
 	var ms []*typeSig
@@ -355,8 +344,8 @@ func methods(t *types.Type) []*typeSig {
 
 		sig := &typeSig{
 			name:  f.Sym,
-			isym:  methodWrapper(it, f),
-			tsym:  methodWrapper(t, f),
+			isym:  methodWrapper(t, f, true),
+			tsym:  methodWrapper(t, f, false),
 			type_: typecheck.NewMethodType(f.Type, t),
 			mtype: typecheck.NewMethodType(f.Type, nil),
 		}
@@ -394,7 +383,7 @@ func imethods(t *types.Type) []*typeSig {
 		// IfaceType.Method is not in the reflect data.
 		// Generate the method body, so that compiled
 		// code can refer to it.
-		methodWrapper(t, f)
+		methodWrapper(t, f, false)
 	}
 
 	return methods
@@ -735,7 +724,7 @@ func dcommontype(lsym *obj.LSym, t *types.Type) int {
 	}
 
 	exported := false
-	p := t.LongString()
+	p := t.NameString()
 	// If we're writing out type T,
 	// we are very likely to write out type *T as well.
 	// Use the string "*T"[1:] for "T", so that the two
@@ -799,11 +788,11 @@ func dcommontype(lsym *obj.LSym, t *types.Type) int {
 // TrackSym returns the symbol for tracking use of field/method f, assumed
 // to be a member of struct/interface type t.
 func TrackSym(t *types.Type, f *types.Field) *obj.LSym {
-	return base.PkgLinksym("go.track", t.ShortString()+"."+f.Sym.Name, obj.ABI0)
+	return base.PkgLinksym("go.track", t.LinkString()+"."+f.Sym.Name, obj.ABI0)
 }
 
 func TypeSymPrefix(prefix string, t *types.Type) *types.Sym {
-	p := prefix + "." + t.ShortString()
+	p := prefix + "." + t.LinkString()
 	s := types.TypeSymLookup(p)
 
 	// This function is for looking up type-related generated functions
@@ -848,16 +837,28 @@ func TypePtr(t *types.Type) *ir.AddrExpr {
 	return typecheck.Expr(typecheck.NodAddr(n)).(*ir.AddrExpr)
 }
 
-func ITabAddr(t, itype *types.Type) *ir.AddrExpr {
-	if t == nil || (t.IsPtr() && t.Elem() == nil) || t.IsUntyped() || !itype.IsInterface() || itype.IsEmptyInterface() {
-		base.Fatalf("ITabAddr(%v, %v)", t, itype)
-	}
-	s, existed := ir.Pkgs.Itab.LookupOK(t.ShortString() + "," + itype.ShortString())
+// ITabLsym returns the LSym representing the itab for concreate type typ
+// implementing interface iface.
+func ITabLsym(typ, iface *types.Type) *obj.LSym {
+	s, existed := ir.Pkgs.Itab.LookupOK(typ.LinkString() + "," + iface.LinkString())
+	lsym := s.Linksym()
+
 	if !existed {
-		itabs = append(itabs, itabEntry{t: t, itype: itype, lsym: s.Linksym()})
+		writeITab(lsym, typ, iface)
 	}
+	return lsym
+}
 
+// ITabAddr returns an expression representing a pointer to the itab
+// for concrete type typ implementing interface iface.
+func ITabAddr(typ, iface *types.Type) *ir.AddrExpr {
+	s, existed := ir.Pkgs.Itab.LookupOK(typ.LinkString() + "," + iface.LinkString())
 	lsym := s.Linksym()
+
+	if !existed {
+		writeITab(lsym, typ, iface)
+	}
+
 	n := ir.NewLinksymExpr(base.Pos, lsym, types.Types[types.TUINT8])
 	return typecheck.Expr(typecheck.NodAddr(n)).(*ir.AddrExpr)
 }
@@ -945,25 +946,27 @@ func writeType(t *types.Type) *obj.LSym {
 	if t.IsPtr() && t.Sym() == nil && t.Elem().Sym() != nil {
 		tbase = t.Elem()
 	}
+	if tbase.Kind() == types.TFORW {
+		base.Fatalf("unresolved defined type: %v", tbase)
+	}
+
 	dupok := 0
-	if tbase.Sym() == nil {
+	if tbase.Sym() == nil || tbase.HasShape() { // TODO(mdempsky): Probably need DUPOK for instantiated types too.
 		dupok = obj.DUPOK
 	}
 
-	if base.Ctxt.Pkgpath != "runtime" || (tbase != types.Types[tbase.Kind()] && tbase != types.ByteType && tbase != types.RuneType && tbase != types.ErrorType) { // int, float, etc
-		// named types from other files are defined only by those files
-		if tbase.Sym() != nil && tbase.Sym().Pkg != types.LocalPkg {
-			if i := typecheck.BaseTypeIndex(t); i >= 0 {
-				lsym.Pkg = tbase.Sym().Pkg.Prefix
-				lsym.SymIdx = int32(i)
-				lsym.Set(obj.AttrIndexed, true)
-			}
-			return lsym
-		}
-		// TODO(mdempsky): Investigate whether this can happen.
-		if tbase.Kind() == types.TFORW {
-			return lsym
+	if !NeedEmit(tbase) {
+		if i := typecheck.BaseTypeIndex(t); i >= 0 {
+			lsym.Pkg = tbase.Sym().Pkg.Prefix
+			lsym.SymIdx = int32(i)
+			lsym.Set(obj.AttrIndexed, true)
 		}
+
+		// TODO(mdempsky): Investigate whether this still happens.
+		// If we know we don't need to emit code for a type,
+		// we should have a link-symbol index for it.
+		// See also TODO in NeedEmit.
+		return lsym
 	}
 
 	ot := 0
@@ -1226,108 +1229,25 @@ func InterfaceMethodOffset(ityp *types.Type, i int64) int64 {
 	return int64(commonSize()+4*types.PtrSize+uncommonSize(ityp)) + i*8
 }
 
-// for each itabEntry, gather the methods on
-// the concrete type that implement the interface
-func CompileITabs() {
-	for i := range itabs {
-		tab := &itabs[i]
-		methods := genfun(tab.t, tab.itype)
-		if len(methods) == 0 {
-			continue
-		}
-		tab.entries = methods
-	}
-}
-
-// for the given concrete type and interface
-// type, return the (sorted) set of methods
-// on the concrete type that implement the interface
-func genfun(t, it *types.Type) []*obj.LSym {
-	if t == nil || it == nil {
-		return nil
-	}
-	sigs := imethods(it)
-	methods := methods(t)
-	out := make([]*obj.LSym, 0, len(sigs))
-	// TODO(mdempsky): Short circuit before calling methods(t)?
-	// See discussion on CL 105039.
-	if len(sigs) == 0 {
-		return nil
-	}
-
-	// both sigs and methods are sorted by name,
-	// so we can find the intersect in a single pass
-	for _, m := range methods {
-		if m.name == sigs[0].name {
-			out = append(out, m.isym)
-			sigs = sigs[1:]
-			if len(sigs) == 0 {
-				break
-			}
-		}
-	}
-
-	if len(sigs) != 0 {
-		base.Fatalf("incomplete itab")
-	}
-
-	return out
-}
-
-// ITabSym uses the information gathered in
-// CompileITabs to de-virtualize interface methods.
-// Since this is called by the SSA backend, it shouldn't
-// generate additional Nodes, Syms, etc.
-func ITabSym(it *obj.LSym, offset int64) *obj.LSym {
-	var syms []*obj.LSym
-	if it == nil {
-		return nil
-	}
-
-	for i := range itabs {
-		e := &itabs[i]
-		if e.lsym == it {
-			syms = e.entries
-			break
-		}
-	}
-	if syms == nil {
-		return nil
-	}
-
-	// keep this arithmetic in sync with *itab layout
-	methodnum := int((offset - 2*int64(types.PtrSize) - 8) / int64(types.PtrSize))
-	if methodnum >= len(syms) {
-		return nil
-	}
-	return syms[methodnum]
-}
-
 // NeedRuntimeType ensures that a runtime type descriptor is emitted for t.
 func NeedRuntimeType(t *types.Type) {
 	if t.HasTParam() {
-		// Generic types don't have a runtime type descriptor (but will
-		// have a dictionary)
+		// Generic types don't really exist at run-time and have no runtime
+		// type descriptor.  But we do write out shape types.
 		return
 	}
 	if _, ok := signatset[t]; !ok {
 		signatset[t] = struct{}{}
-		signatslice = append(signatslice, t)
+		signatslice = append(signatslice, typeAndStr{t: t, short: types.TypeSymName(t), regular: t.String()})
 	}
 }
 
 func WriteRuntimeTypes() {
-	// Process signatset. Use a loop, as writeType adds
-	// entries to signatset while it is being processed.
-	signats := make([]typeAndStr, len(signatslice))
+	// Process signatslice. Use a loop, as writeType adds
+	// entries to signatslice while it is being processed.
 	for len(signatslice) > 0 {
-		signats = signats[:0]
-		// Transfer entries to a slice and sort, for reproducible builds.
-		for _, t := range signatslice {
-			signats = append(signats, typeAndStr{t: t, short: types.TypeSymName(t), regular: t.String()})
-			delete(signatset, t)
-		}
-		signatslice = signatslice[:0]
+		signats := signatslice
+		// Sort for reproducible builds.
 		sort.Sort(typesByString(signats))
 		for _, ts := range signats {
 			t := ts.t
@@ -1336,6 +1256,7 @@ func WriteRuntimeTypes() {
 				writeType(types.NewPtr(t))
 			}
 		}
+		signatslice = signatslice[len(signats):]
 	}
 
 	// Emit GC data symbols.
@@ -1349,29 +1270,66 @@ func WriteRuntimeTypes() {
 	}
 }
 
-func WriteTabs() {
-	// process itabs
-	for _, i := range itabs {
-		// dump empty itab symbol into i.sym
-		// type itab struct {
-		//   inter  *interfacetype
-		//   _type  *_type
-		//   hash   uint32
-		//   _      [4]byte
-		//   fun    [1]uintptr // variable sized
-		// }
-		o := objw.SymPtr(i.lsym, 0, writeType(i.itype), 0)
-		o = objw.SymPtr(i.lsym, o, writeType(i.t), 0)
-		o = objw.Uint32(i.lsym, o, types.TypeHash(i.t)) // copy of type hash
-		o += 4                                          // skip unused field
-		for _, fn := range genfun(i.t, i.itype) {
-			o = objw.SymPtrWeak(i.lsym, o, fn, 0) // method pointer for each method
-		}
-		// Nothing writes static itabs, so they are read only.
-		objw.Global(i.lsym, int32(o), int16(obj.DUPOK|obj.RODATA))
-		i.lsym.Set(obj.AttrContentAddressable, true)
+// writeITab writes the itab for concrete type typ implementing
+// interface iface.
+func writeITab(lsym *obj.LSym, typ, iface *types.Type) {
+	// TODO(mdempsky): Fix methodWrapper, geneq, and genhash (and maybe
+	// others) to stop clobbering these.
+	oldpos, oldfn := base.Pos, ir.CurFunc
+	defer func() { base.Pos, ir.CurFunc = oldpos, oldfn }()
+
+	if typ == nil || (typ.IsPtr() && typ.Elem() == nil) || typ.IsUntyped() || iface == nil || !iface.IsInterface() || iface.IsEmptyInterface() {
+		base.Fatalf("writeITab(%v, %v)", typ, iface)
 	}
 
+	sigs := iface.AllMethods().Slice()
+	entries := make([]*obj.LSym, 0, len(sigs))
+
+	// both sigs and methods are sorted by name,
+	// so we can find the intersection in a single pass
+	for _, m := range methods(typ) {
+		if m.name == sigs[0].Sym {
+			entries = append(entries, m.isym)
+			if m.isym == nil {
+				panic("NO ISYM")
+			}
+			sigs = sigs[1:]
+			if len(sigs) == 0 {
+				break
+			}
+		}
+		if sigs[0].Sym.Name == "==" {
+			sigs = sigs[1:]
+			if len(sigs) == 0 {
+				break
+			}
+		}
+	}
+	if len(sigs) != 0 {
+		base.Fatalf("incomplete itab")
+	}
+
+	// dump empty itab symbol into i.sym
+	// type itab struct {
+	//   inter  *interfacetype
+	//   _type  *_type
+	//   hash   uint32
+	//   _      [4]byte
+	//   fun    [1]uintptr // variable sized
+	// }
+	o := objw.SymPtr(lsym, 0, writeType(iface), 0)
+	o = objw.SymPtr(lsym, o, writeType(typ), 0)
+	o = objw.Uint32(lsym, o, types.TypeHash(typ)) // copy of type hash
+	o += 4                                        // skip unused field
+	for _, fn := range entries {
+		o = objw.SymPtrWeak(lsym, o, fn, 0) // method pointer for each method
+	}
+	// Nothing writes static itabs, so they are read only.
+	objw.Global(lsym, int32(o), int16(obj.DUPOK|obj.RODATA))
+	lsym.Set(obj.AttrContentAddressable, true)
+}
+
+func WriteTabs() {
 	// process ptabs
 	if types.LocalPkg.Name == "main" && len(ptabs) > 0 {
 		ot := 0
@@ -1453,7 +1411,7 @@ func WriteBasicTypes() {
 
 type typeAndStr struct {
 	t       *types.Type
-	short   string
+	short   string // "short" here means NameString
 	regular string
 }
 
@@ -1466,8 +1424,13 @@ func (a typesByString) Less(i, j int) bool {
 	}
 	// When the only difference between the types is whether
 	// they refer to byte or uint8, such as **byte vs **uint8,
-	// the types' ShortStrings can be identical.
+	// the types' NameStrings can be identical.
 	// To preserve deterministic sort ordering, sort these by String().
+	//
+	// TODO(mdempsky): This all seems suspect. Using LinkString would
+	// avoid naming collisions, and there shouldn't be a reason to care
+	// about "byte" vs "uint8": they share the same runtime type
+	// descriptor anyway.
 	if a[i].regular != a[j].regular {
 		return a[i].regular < a[j].regular
 	}
@@ -1741,6 +1704,49 @@ func CollectPTabs() {
 	}
 }
 
+// NeedEmit reports whether typ is a type that we need to emit code
+// for (e.g., runtime type descriptors, method wrappers).
+func NeedEmit(typ *types.Type) bool {
+	// TODO(mdempsky): Export data should keep track of which anonymous
+	// and instantiated types were emitted, so at least downstream
+	// packages can skip re-emitting them.
+	//
+	// Perhaps we can just generalize the linker-symbol indexing to
+	// track the index of arbitrary types, not just defined types, and
+	// use its presence to detect this. The same idea would work for
+	// instantiated generic functions too.
+
+	switch sym := typ.Sym(); {
+	case sym == nil:
+		// Anonymous type; possibly never seen before or ever again.
+		// Need to emit to be safe (however, see TODO above).
+		return true
+
+	case sym.Pkg == types.LocalPkg:
+		// Local defined type; our responsibility.
+		return true
+
+	case base.Ctxt.Pkgpath == "runtime" && (sym.Pkg == types.BuiltinPkg || sym.Pkg == ir.Pkgs.Unsafe):
+		// Package runtime is responsible for including code for builtin
+		// types (predeclared and package unsafe).
+		return true
+
+	case typ.IsFullyInstantiated():
+		// Instantiated type; possibly instantiated with unique type arguments.
+		// Need to emit to be safe (however, see TODO above).
+		return true
+
+	case typ.HasShape():
+		// Shape type; need to emit even though it lives in the .shape package.
+		// TODO: make sure the linker deduplicates them (see dupok in writeType above).
+		return true
+
+	default:
+		// Should have been emitted by an imported package.
+		return false
+	}
+}
+
 // Generate a wrapper function to convert from
 // a receiver of type T to a receiver of type U.
 // That is,
@@ -1761,7 +1767,45 @@ func CollectPTabs() {
 //
 //	rcvr - U
 //	method - M func (t T)(), a TFIELD type struct
-func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
+//
+// Also wraps methods on instantiated generic types for use in itab entries.
+// For an instantiated generic type G[int], we generate wrappers like:
+// G[int] pointer shaped:
+//	func (x G[int]) f(arg) {
+//		.inst.G[int].f(dictionary, x, arg)
+// 	}
+// G[int] not pointer shaped:
+//	func (x *G[int]) f(arg) {
+//		.inst.G[int].f(dictionary, *x, arg)
+// 	}
+// These wrappers are always fully stenciled.
+func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSym {
+	orig := rcvr
+	if forItab && !types.IsDirectIface(rcvr) {
+		rcvr = rcvr.PtrTo()
+	}
+
+	generic := false
+	// We don't need a dictionary if we are reaching a method (possibly via an
+	// embedded field) which is an interface method.
+	if !types.IsInterfaceMethod(method.Type) {
+		rcvr1 := rcvr
+		if rcvr1.IsPtr() {
+			rcvr1 = rcvr.Elem()
+		}
+		if len(rcvr1.RParams()) > 0 {
+			// If rcvr has rparams, remember method as generic, which
+			// means we need to add a dictionary to the wrapper.
+			generic = true
+			targs := rcvr1.RParams()
+			for _, t := range targs {
+				if t.HasShape() {
+					base.Fatalf("method on type instantiated with shapes targ:%+v rcvr:%+v", t, rcvr)
+				}
+			}
+		}
+	}
+
 	newnam := ir.MethodSym(rcvr, method.Sym)
 	lsym := newnam.Linksym()
 	if newnam.Siggen() {
@@ -1769,19 +1813,18 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 	}
 	newnam.SetSiggen(true)
 
-	if types.Identical(rcvr, method.Type.Recv().Type) {
+	// Except in quirks mode, unified IR creates its own wrappers.
+	if base.Debug.Unified != 0 && base.Debug.UnifiedQuirks == 0 {
 		return lsym
 	}
 
-	// Only generate (*T).M wrappers for T.M in T's own package.
-	if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type &&
-		rcvr.Elem().Sym() != nil && rcvr.Elem().Sym().Pkg != types.LocalPkg {
+	// For generic methods, we need to generate the wrapper even if the receiver
+	// types are identical, because we want to add the dictionary.
+	if !generic && types.Identical(rcvr, method.Type.Recv().Type) {
 		return lsym
 	}
 
-	// Only generate I.M wrappers for I in I's own package
-	// but keep doing it for error.Error (was issue #29304).
-	if rcvr.IsInterface() && rcvr.Sym() != nil && rcvr.Sym().Pkg != types.LocalPkg && rcvr != types.ErrorType {
+	if !NeedEmit(rcvr) || rcvr.IsPtr() && !NeedEmit(rcvr.Elem()) {
 		return lsym
 	}
 
@@ -1802,9 +1845,10 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 	nthis := ir.AsNode(tfn.Type().Recv().Nname)
 
 	methodrcvr := method.Type.Recv().Type
+	indirect := rcvr.IsPtr() && rcvr.Elem() == methodrcvr
 
 	// generate nil pointer check for better error
-	if rcvr.IsPtr() && rcvr.Elem() == methodrcvr {
+	if indirect {
 		// generating wrapper from *T to T.
 		n := ir.NewIfStmt(base.Pos, nil, nil, nil)
 		n.Cond = ir.NewBinaryExpr(base.Pos, ir.OEQ, nthis, typecheck.NodNil())
@@ -1814,7 +1858,6 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 	}
 
 	dot := typecheck.AddImplicitDots(ir.NewSelectorExpr(base.Pos, ir.OXDOT, nthis, method.Sym))
-
 	// generate call
 	// It's not possible to use a tail call when dynamic linking on ppc64le. The
 	// bad scenario is when a local call is made to the wrapper: the wrapper will
@@ -1826,7 +1869,7 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 	// Disable tailcall for RegabiArgs for now. The IR does not connect the
 	// arguments with the OTAILCALL node, and the arguments are not marshaled
 	// correctly.
-	if !base.Flag.Cfg.Instrumenting && rcvr.IsPtr() && methodrcvr.IsPtr() && method.Embedded != 0 && !types.IsInterfaceMethod(method.Type) && !(base.Ctxt.Arch.Name == "ppc64le" && base.Ctxt.Flag_dynlink) && !buildcfg.Experiment.RegabiArgs {
+	if !base.Flag.Cfg.Instrumenting && rcvr.IsPtr() && methodrcvr.IsPtr() && method.Embedded != 0 && !types.IsInterfaceMethod(method.Type) && !(base.Ctxt.Arch.Name == "ppc64le" && base.Ctxt.Flag_dynlink) && !buildcfg.Experiment.RegabiArgs && !generic {
 		// generate tail call: adjust pointer receiver and jump to embedded method.
 		left := dot.X // skip final .M
 		if !left.Type().IsPtr() {
@@ -1837,8 +1880,68 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 		fn.Body.Append(ir.NewTailCallStmt(base.Pos, method.Nname.(*ir.Name)))
 	} else {
 		fn.SetWrapper(true) // ignore frame for panic+recover matching
-		call := ir.NewCallExpr(base.Pos, ir.OCALL, dot, nil)
-		call.Args = ir.ParamNames(tfn.Type())
+		var call *ir.CallExpr
+
+		if generic && dot.X != nthis {
+			// TODO: for now, we don't try to generate dictionary wrappers for
+			// any methods involving embedded fields, because we're not
+			// generating the needed dictionaries in instantiateMethods.
+			generic = false
+		}
+
+		if generic {
+			var args []ir.Node
+			var targs []*types.Type
+			if rcvr.IsPtr() {
+				targs = rcvr.Elem().RParams()
+			} else {
+				targs = rcvr.RParams()
+			}
+			// The wrapper for an auto-generated pointer/non-pointer
+			// receiver method should share the same dictionary as the
+			// corresponding original (user-written) method.
+			baseOrig := orig
+			if baseOrig.IsPtr() && !method.Type.Recv().Type.IsPtr() {
+				baseOrig = baseOrig.Elem()
+			} else if !baseOrig.IsPtr() && method.Type.Recv().Type.IsPtr() {
+				baseOrig = types.NewPtr(baseOrig)
+			}
+			args = append(args, getDictionary(ir.MethodSym(baseOrig, method.Sym), targs))
+			if indirect {
+				args = append(args, ir.NewStarExpr(base.Pos, dot.X))
+			} else if methodrcvr.IsPtr() && methodrcvr.Elem() == dot.X.Type() {
+				// Case where method call is via a non-pointer
+				// embedded field with a pointer method.
+				args = append(args, typecheck.NodAddrAt(base.Pos, dot.X))
+			} else {
+				args = append(args, dot.X)
+			}
+			args = append(args, ir.ParamNames(tfn.Type())...)
+
+			// Target method uses shaped names.
+			targs2 := make([]*types.Type, len(targs))
+			for i, t := range targs {
+				targs2[i] = typecheck.Shapify(t)
+			}
+			targs = targs2
+
+			sym := typecheck.MakeFuncInstSym(ir.MethodSym(methodrcvr, method.Sym), targs, true)
+			if sym.Def == nil {
+				// Currently we make sure that we have all the instantiations
+				// we need by generating them all in ../noder/stencil.go:instantiateMethods
+				// TODO: maybe there's a better, more incremental way to generate
+				// only the instantiations we need?
+				base.Fatalf("instantiation %s not found", sym.Name)
+			}
+			target := ir.AsNode(sym.Def)
+			call = ir.NewCallExpr(base.Pos, ir.OCALL, target, args)
+			// Fill-in the generic method node that was not filled in
+			// in instantiateMethod.
+			method.Nname = fn.Nname
+		} else {
+			call = ir.NewCallExpr(base.Pos, ir.OCALL, dot, nil)
+			call.Args = ir.ParamNames(tfn.Type())
+		}
 		call.IsDDD = tfn.Type().IsVariadic()
 		if method.Type.NumResults() > 0 {
 			ret := ir.NewReturnStmt(base.Pos, nil)
@@ -1858,13 +1961,10 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 	ir.CurFunc = fn
 	typecheck.Stmts(fn.Body)
 
-	// Inline calls within (*T).M wrappers. This is safe because we only
-	// generate those wrappers within the same compilation unit as (T).M.
-	// TODO(mdempsky): Investigate why we can't enable this more generally.
-	if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type && rcvr.Elem().Sym() != nil {
+	if AfterGlobalEscapeAnalysis {
 		inline.InlineCalls(fn)
+		escape.Batch([]*ir.Func{fn}, false)
 	}
-	escape.Batch([]*ir.Func{fn}, false)
 
 	ir.CurFunc = nil
 	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
@@ -1872,11 +1972,21 @@ func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
 	return lsym
 }
 
+// AfterGlobalEscapeAnalysis tracks whether package gc has already
+// performed the main, global escape analysis pass. If so,
+// methodWrapper takes responsibility for escape analyzing any
+// generated wrappers.
+var AfterGlobalEscapeAnalysis bool
+
 var ZeroSize int64
 
 // MarkTypeUsedInInterface marks that type t is converted to an interface.
 // This information is used in the linker in dead method elimination.
 func MarkTypeUsedInInterface(t *types.Type, from *obj.LSym) {
+	if t.HasShape() {
+		// Shape types shouldn't be put in interfaces, so we shouldn't ever get here.
+		base.Fatalf("shape types have no methods %+v", t)
+	}
 	tsym := TypeLinksym(t)
 	// Emit a marker relocation. The linker will know the type is converted
 	// to an interface if "from" is reachable.
@@ -1897,9 +2007,60 @@ func MarkUsedIfaceMethod(n *ir.CallExpr) {
 	tsym := TypeLinksym(ityp)
 	r := obj.Addrel(ir.CurFunc.LSym)
 	r.Sym = tsym
-	// dot.Xoffset is the method index * PtrSize (the offset of code pointer
+	// dot.Offset() is the method index * PtrSize (the offset of code pointer
 	// in itab).
 	midx := dot.Offset() / int64(types.PtrSize)
 	r.Add = InterfaceMethodOffset(ityp, midx)
 	r.Type = objabi.R_USEIFACEMETHOD
 }
+
+// MarkUsedIfaceMethodIndex marks that that method number ix (in the AllMethods list)
+// of interface type ityp is used, and should be attached to lsym.
+func MarkUsedIfaceMethodIndex(lsym *obj.LSym, ityp *types.Type, ix int) {
+	tsym := TypeLinksym(ityp)
+	r := obj.Addrel(lsym)
+	r.Sym = tsym
+	r.Add = InterfaceMethodOffset(ityp, int64(ix))
+	r.Type = objabi.R_USEIFACEMETHOD
+}
+
+// getDictionary returns the dictionary for the given named generic function
+// or method, with the given type arguments.
+func getDictionary(gf *types.Sym, targs []*types.Type) ir.Node {
+	if len(targs) == 0 {
+		base.Fatalf("%s should have type arguments", gf.Name)
+	}
+	for _, t := range targs {
+		if t.HasShape() {
+			base.Fatalf("dictionary for %s should only use concrete types: %+v", gf.Name, t)
+		}
+	}
+
+	sym := typecheck.MakeDictSym(gf, targs, true)
+
+	// Initialize the dictionary, if we haven't yet already.
+	if lsym := sym.Linksym(); len(lsym.P) == 0 {
+		base.Fatalf("Dictionary should have already been generated: %s.%s", sym.Pkg.Path, sym.Name)
+	}
+
+	// Make (or reuse) a node referencing the dictionary symbol.
+	var n *ir.Name
+	if sym.Def != nil {
+		n = sym.Def.(*ir.Name)
+	} else {
+		n = typecheck.NewName(sym)
+		n.SetType(types.Types[types.TUINTPTR]) // should probably be [...]uintptr, but doesn't really matter
+		n.SetTypecheck(1)
+		n.Class = ir.PEXTERN
+		sym.Def = n
+	}
+
+	// Return the address of the dictionary.
+	np := typecheck.NodAddr(n)
+	// Note: treat dictionary pointers as uintptrs, so they aren't pointers
+	// with respect to GC. That saves on stack scanning work, write barriers, etc.
+	// We can get away with it because dictionaries are global variables.
+	np.SetType(types.Types[types.TUINTPTR])
+	np.SetTypecheck(1)
+	return np
+}
diff --git a/src/cmd/compile/internal/riscv64/galign.go b/src/cmd/compile/internal/riscv64/galign.go
index 338248a7cf27ab13b71ec4ed25f90a015fdc6511..846ed8fb3802e43d603abe6bb0de2617a177dca8 100644
--- a/src/cmd/compile/internal/riscv64/galign.go
+++ b/src/cmd/compile/internal/riscv64/galign.go
@@ -16,7 +16,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.MAXWIDTH = 1 << 50
 
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 	arch.ZeroRange = zeroRange
 
 	arch.SSAMarkMoves = ssaMarkMoves
diff --git a/src/cmd/compile/internal/riscv64/ssa.go b/src/cmd/compile/internal/riscv64/ssa.go
index 64a9b3b33b9aca34cfd15284ff14eb765a67d52a..d3cbb4ec24b17530e49e656484f66e5cc86b322c 100644
--- a/src/cmd/compile/internal/riscv64/ssa.go
+++ b/src/cmd/compile/internal/riscv64/ssa.go
@@ -282,6 +282,42 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		p.Reg = r1
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = r
+	case ssa.OpRISCV64LoweredMuluhilo:
+		r0 := v.Args[0].Reg()
+		r1 := v.Args[1].Reg()
+		p := s.Prog(riscv.AMULHU)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = r1
+		p.Reg = r0
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = v.Reg0()
+		p1 := s.Prog(riscv.AMUL)
+		p1.From.Type = obj.TYPE_REG
+		p1.From.Reg = r1
+		p1.Reg = r0
+		p1.To.Type = obj.TYPE_REG
+		p1.To.Reg = v.Reg1()
+	case ssa.OpRISCV64LoweredMuluover:
+		r0 := v.Args[0].Reg()
+		r1 := v.Args[1].Reg()
+		p := s.Prog(riscv.AMULHU)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = r1
+		p.Reg = r0
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = v.Reg1()
+		p1 := s.Prog(riscv.AMUL)
+		p1.From.Type = obj.TYPE_REG
+		p1.From.Reg = r1
+		p1.Reg = r0
+		p1.To.Type = obj.TYPE_REG
+		p1.To.Reg = v.Reg0()
+		p2 := s.Prog(riscv.ASNEZ)
+		p2.From.Type = obj.TYPE_REG
+		p2.From.Reg = v.Reg1()
+		p2.To.Type = obj.TYPE_REG
+		p2.To.Reg = v.Reg1()
+
 	case ssa.OpRISCV64FSQRTS, ssa.OpRISCV64FNEGS, ssa.OpRISCV64FSQRTD, ssa.OpRISCV64FNEGD,
 		ssa.OpRISCV64FMVSX, ssa.OpRISCV64FMVDX,
 		ssa.OpRISCV64FCVTSW, ssa.OpRISCV64FCVTSL, ssa.OpRISCV64FCVTWS, ssa.OpRISCV64FCVTLS,
diff --git a/src/cmd/compile/internal/s390x/galign.go b/src/cmd/compile/internal/s390x/galign.go
index b004a2db0a39b3f61c9b8e1d93d648d3d44bcd0a..d880834c220d91c763667614a46b241fb23484bb 100644
--- a/src/cmd/compile/internal/s390x/galign.go
+++ b/src/cmd/compile/internal/s390x/galign.go
@@ -16,7 +16,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ssa/config.go b/src/cmd/compile/internal/ssa/config.go
index a8393a19995a5f922a419fdd899acedf76a12bef..32e3a0860e3dadc9417063665566082e824a021c 100644
--- a/src/cmd/compile/internal/ssa/config.go
+++ b/src/cmd/compile/internal/ssa/config.go
@@ -149,12 +149,6 @@ type Frontend interface {
 	// for the parts of that compound type.
 	SplitSlot(parent *LocalSlot, suffix string, offset int64, t *types.Type) LocalSlot
 
-	// DerefItab dereferences an itab function
-	// entry, given the symbol of the itab and
-	// the byte offset of the function pointer.
-	// It may return nil.
-	DerefItab(sym *obj.LSym, offset int64) *obj.LSym
-
 	// Line returns a string describing the given position.
 	Line(src.XPos) string
 
@@ -177,7 +171,7 @@ type Frontend interface {
 }
 
 // NewConfig returns a new configuration object for the given architecture.
-func NewConfig(arch string, types Types, ctxt *obj.Link, optimize bool) *Config {
+func NewConfig(arch string, types Types, ctxt *obj.Link, optimize, softfloat bool) *Config {
 	c := &Config{arch: arch, Types: types}
 	c.useAvg = true
 	c.useHmul = true
@@ -196,7 +190,7 @@ func NewConfig(arch string, types Types, ctxt *obj.Link, optimize bool) *Config
 		c.floatParamRegs = paramFloatRegAMD64
 		c.FPReg = framepointerRegAMD64
 		c.LinkReg = linkRegAMD64
-		c.hasGReg = buildcfg.Experiment.RegabiG
+		c.hasGReg = true
 	case "386":
 		c.PtrSize = 4
 		c.RegSize = 4
@@ -228,6 +222,8 @@ func NewConfig(arch string, types Types, ctxt *obj.Link, optimize bool) *Config
 		c.registers = registersARM64[:]
 		c.gpRegMask = gpRegMaskARM64
 		c.fpRegMask = fpRegMaskARM64
+		c.intParamRegs = paramIntRegARM64
+		c.floatParamRegs = paramFloatRegARM64
 		c.FPReg = framepointerRegARM64
 		c.LinkReg = linkRegARM64
 		c.hasGReg = true
@@ -324,6 +320,10 @@ func NewConfig(arch string, types Types, ctxt *obj.Link, optimize bool) *Config
 	c.optimize = optimize
 	c.useSSE = true
 	c.UseFMA = true
+	c.SoftFloat = softfloat
+	if softfloat {
+		c.floatParamRegs = nil // no FP registers in softfloat mode
+	}
 
 	c.ABI0 = abi.NewABIConfig(0, 0, ctxt.FixedFrameSize())
 	c.ABI1 = abi.NewABIConfig(len(c.intParamRegs), len(c.floatParamRegs), ctxt.FixedFrameSize())
diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
index 7e973ab20591fb8ae42eddcc542f6ca6c1c67451..a8c6c26dadc0eea1e0a7c8952727ddacf0d5dbc6 100644
--- a/src/cmd/compile/internal/ssa/expand_calls.go
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -215,7 +215,7 @@ func (x *expandState) isAlreadyExpandedAggregateType(t *types.Type) bool {
 		return false
 	}
 	return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice() ||
-		t.Size() > x.regSize && t.IsInteger()
+		(t.Size() > x.regSize && (t.IsInteger() || (x.f.Config.SoftFloat && t.IsFloat())))
 }
 
 // offsetFrom creates an offset from a pointer, simplifying chained offsets and offsets from SP
@@ -380,6 +380,12 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
 		// The OpLoad was created to load the single field of the IData
 		// This case removes that StructSelect.
 		if leafType != selector.Type {
+			if x.f.Config.SoftFloat && selector.Type.IsFloat() {
+				if x.debug {
+					x.Printf("---OpLoad, break\n")
+				}
+				break // softfloat pass will take care of that
+			}
 			x.f.Fatalf("Unexpected Load as selector, leaf=%s, selector=%s\n", leaf.LongString(), selector.LongString())
 		}
 		leaf.copyOf(selector)
@@ -525,11 +531,11 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
 
 	case OpComplexReal:
 		ls := x.rewriteSelect(leaf, selector.Args[0], offset, regOffset)
-		locs = x.splitSlots(ls, ".real", 0, leafType)
+		locs = x.splitSlots(ls, ".real", 0, selector.Type)
 
 	case OpComplexImag:
-		ls := x.rewriteSelect(leaf, selector.Args[0], offset+leafType.Width, regOffset+RO_complex_imag) // result is FloatNN, width of result is offset of imaginary part.
-		locs = x.splitSlots(ls, ".imag", leafType.Width, leafType)
+		ls := x.rewriteSelect(leaf, selector.Args[0], offset+selector.Type.Width, regOffset+RO_complex_imag) // result is FloatNN, width of result is offset of imaginary part.
+		locs = x.splitSlots(ls, ".imag", selector.Type.Width, selector.Type)
 
 	case OpStringLen, OpSliceLen:
 		ls := x.rewriteSelect(leaf, selector.Args[0], offset+x.ptrSize, regOffset+RO_slice_len)
diff --git a/src/cmd/compile/internal/ssa/export_test.go b/src/cmd/compile/internal/ssa/export_test.go
index 8ed8a0c4a6e3b725f5f621b0ea8855a3a6b9bac7..6d3c0f3ccbda17fb89ef7b4152fcf5a1f570c589 100644
--- a/src/cmd/compile/internal/ssa/export_test.go
+++ b/src/cmd/compile/internal/ssa/export_test.go
@@ -39,7 +39,7 @@ func testConfigArch(tb testing.TB, arch string) *Conf {
 		tb.Fatal("testTypes is 64-bit only")
 	}
 	c := &Conf{
-		config: NewConfig(arch, testTypes, ctxt, true),
+		config: NewConfig(arch, testTypes, ctxt, true, false),
 		tb:     tb,
 	}
 	return c
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index 4cd00732fc3f5e5f8a4098f6a0b0261f01c9a4a8..45c023831729f6458697c346f5082627b64bd47c 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -460,7 +460,7 @@
 (IsInBounds idx len) => (SETB (CMPQ idx len))
 (IsSliceInBounds idx len) => (SETBE (CMPQ idx len))
 (NilCheck ...) => (LoweredNilCheck ...)
-(GetG mem) && !(buildcfg.Experiment.RegabiG && v.Block.Func.OwnAux.Fn.ABI() == obj.ABIInternal) => (LoweredGetG mem) // only lower in old ABI. in new ABI we have a G register.
+(GetG mem) && v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal => (LoweredGetG mem) // only lower in old ABI. in new ABI we have a G register.
 (GetClosurePtr ...) => (LoweredGetClosurePtr ...)
 (GetCallerPC ...) => (LoweredGetCallerPC ...)
 (GetCallerSP ...) => (LoweredGetCallerSP ...)
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64.rules b/src/cmd/compile/internal/ssa/gen/ARM64.rules
index 62699f290c2149e6308c4f0d3d82b9b20e3d7738..530e48bcb259a4e84a039d2896b020c93967386b 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64.rules
+++ b/src/cmd/compile/internal/ssa/gen/ARM64.rules
@@ -2868,3 +2868,12 @@
 	&& isInlinableMemmove(dst, src, sz, config)
 	&& clobber(s1, s2, s3, call)
 	=> (Move [sz] dst src mem)
+
+// Match post-lowering calls, register version.
+(SelectN [0] call:(CALLstatic {sym} dst src (MOVDconst [sz]) mem))
+	&& sz >= 0
+	&& isSameCall(sym, "runtime.memmove")
+	&& call.Uses == 1
+	&& isInlinableMemmove(dst, src, sz, config)
+	&& clobber(call)
+	=> (Move [sz] dst src mem)
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
index 18a5666b40f0dfcce916f12efb228ee6b2ec1100..5de0b5f02031fc2ac980278a6becde57a0f5f407 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
@@ -482,9 +482,9 @@ func init() {
 		{name: "CSETM", argLength: 1, reg: readflags, asm: "CSETM", aux: "CCop"}, // auxint(flags) ? -1 : 0
 
 		// function calls
-		{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                                               // call static function aux.(*obj.LSym).  arg0=mem, auxint=argsize, returns mem
-		{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R26"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure.  arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
-		{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                         // call fn by pointer.  arg0=codeptr, arg1=mem, auxint=argsize, returns mem
+		{name: "CALLstatic", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                                               // call static function aux.(*obj.LSym).  last arg=mem, auxint=argsize, returns mem
+		{name: "CALLclosure", argLength: -1, reg: regInfo{inputs: []regMask{gpsp, buildReg("R26"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure.  arg0=codeptr, arg1=closure, last arg=mem, auxint=argsize, returns mem
+		{name: "CALLinter", argLength: -1, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                         // call fn by pointer.  arg0=codeptr, last arg=mem, auxint=argsize, returns mem
 
 		// pseudo-ops
 		{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true, faultOnNilArg0: true}, // panic if arg0 is nil.  arg1=mem.
@@ -759,15 +759,17 @@ func init() {
 	}
 
 	archs = append(archs, arch{
-		name:            "ARM64",
-		pkg:             "cmd/internal/obj/arm64",
-		genfile:         "../../arm64/ssa.go",
-		ops:             ops,
-		blocks:          blocks,
-		regnames:        regNamesARM64,
-		gpregmask:       gp,
-		fpregmask:       fp,
-		framepointerreg: -1, // not used
-		linkreg:         int8(num["R30"]),
+		name:               "ARM64",
+		pkg:                "cmd/internal/obj/arm64",
+		genfile:            "../../arm64/ssa.go",
+		ops:                ops,
+		blocks:             blocks,
+		regnames:           regNamesARM64,
+		ParamIntRegNames:   "R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15",
+		ParamFloatRegNames: "F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15",
+		gpregmask:          gp,
+		fpregmask:          fp,
+		framepointerreg:    -1, // not used
+		linkreg:            int8(num["R30"]),
 	})
 }
diff --git a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
index f7198b90c32e48ce940e6b52530aee7dea47c4fb..d7d8a33a0a10a52f8bd19ddb5ab2f5bbdc14e1cc 100644
--- a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main
diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64.rules b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
index 9cdd62edbe01c004f4b79951d38a4d5cd123a2a3..4eb48e3928f587f5537fd984e779eb8da2aa497a 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64.rules
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
@@ -29,6 +29,8 @@
 (Sub64F ...) => (FSUBD ...)
 
 (Mul64 ...) => (MUL  ...)
+(Mul64uhilo ...) => (LoweredMuluhilo ...)
+(Mul64uover ...) => (LoweredMuluover ...)
 (Mul32 ...) => (MULW ...)
 (Mul16 x y) => (MULW (SignExt16to32 x) (SignExt16to32 y))
 (Mul8 x y)  => (MULW (SignExt8to32 x)  (SignExt8to32 y))
@@ -586,6 +588,10 @@
 (BNEZ (SEQZ x) yes no) => (BEQZ x yes no)
 (BNEZ (SNEZ x) yes no) => (BNEZ x yes no)
 
+// Absorb NEG into branch when possible.
+(BEQZ x:(NEG y) yes no) && x.Uses == 1 => (BEQZ y yes no)
+(BNEZ x:(NEG y) yes no) && x.Uses == 1 => (BNEZ y yes no)
+
 // Convert BEQZ/BNEZ into more optimal branch conditions.
 (BEQZ (SUB x y) yes no) => (BEQ x y yes no)
 (BNEZ (SUB x y) yes no) => (BNE x y yes no)
@@ -594,11 +600,15 @@
 (BEQZ (SLTU x y) yes no) => (BGEU x y yes no)
 (BNEZ (SLTU x y) yes no) => (BLTU x y yes no)
 
-// Convert branch with zero to BEQZ/BNEZ.
+// Convert branch with zero to more optimal branch zero.
 (BEQ (MOVDconst [0]) cond yes no) => (BEQZ cond yes no)
 (BEQ cond (MOVDconst [0]) yes no) => (BEQZ cond yes no)
 (BNE (MOVDconst [0]) cond yes no) => (BNEZ cond yes no)
 (BNE cond (MOVDconst [0]) yes no) => (BNEZ cond yes no)
+(BLT (MOVDconst [0]) cond yes no) => (BGTZ cond yes no)
+(BLT cond (MOVDconst [0]) yes no) => (BLTZ cond yes no)
+(BGE (MOVDconst [0]) cond yes no) => (BLEZ cond yes no)
+(BGE cond (MOVDconst [0]) yes no) => (BGEZ cond yes no)
 
 // Store zero
 (MOVBstore [off] {sym} ptr (MOVDconst [0]) mem) => (MOVBstorezero [off] {sym} ptr mem)
diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go b/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
index 0774d4c654f95728d024eee48fef23444567a82b..d36daa8b839a6f0fb73021a0d0b856f886b4bfe4 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
@@ -123,6 +123,7 @@ func init() {
 		gp01     = regInfo{outputs: []regMask{gpMask}}
 		gp11     = regInfo{inputs: []regMask{gpMask}, outputs: []regMask{gpMask}}
 		gp21     = regInfo{inputs: []regMask{gpMask, gpMask}, outputs: []regMask{gpMask}}
+		gp22     = regInfo{inputs: []regMask{gpMask, gpMask}, outputs: []regMask{gpMask, gpMask}}
 		gpload   = regInfo{inputs: []regMask{gpspsbMask, 0}, outputs: []regMask{gpMask}}
 		gp11sb   = regInfo{inputs: []regMask{gpspsbMask}, outputs: []regMask{gpMask}}
 		gpxchg   = regInfo{inputs: []regMask{gpspsbgMask, gpgMask}, outputs: []regMask{gpMask}}
@@ -157,6 +158,9 @@ func init() {
 		{name: "MULW", argLength: 2, reg: gp21, asm: "MULW", commutative: true, typ: "Int32"},
 		{name: "MULH", argLength: 2, reg: gp21, asm: "MULH", commutative: true, typ: "Int64"},
 		{name: "MULHU", argLength: 2, reg: gp21, asm: "MULHU", commutative: true, typ: "UInt64"},
+		{name: "LoweredMuluhilo", argLength: 2, reg: gp22, resultNotInArgs: true}, // arg0 * arg1, return (hi, lo)
+		{name: "LoweredMuluover", argLength: 2, reg: gp22, resultNotInArgs: true}, // arg0 * arg1, return (64 bits of arg0*arg1, overflow)
+
 		{name: "DIV", argLength: 2, reg: gp21, asm: "DIV", typ: "Int64"}, // arg0 / arg1
 		{name: "DIVU", argLength: 2, reg: gp21, asm: "DIVU", typ: "UInt64"},
 		{name: "DIVW", argLength: 2, reg: gp21, asm: "DIVW", typ: "Int32"},
diff --git a/src/cmd/compile/internal/ssa/gen/dec64Ops.go b/src/cmd/compile/internal/ssa/gen/dec64Ops.go
index 8c5883bc5691348147d6845b20af96e961007100..78fcea885aa8b250304d0064e32ad0b03f52bc8e 100644
--- a/src/cmd/compile/internal/ssa/gen/dec64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/dec64Ops.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main
diff --git a/src/cmd/compile/internal/ssa/gen/decOps.go b/src/cmd/compile/internal/ssa/gen/decOps.go
index b826481c9fbb2fdcb90b41742d66561f88a64014..d5cd79378c76a3041e007bc197c171f7272a4bda 100644
--- a/src/cmd/compile/internal/ssa/gen/decOps.go
+++ b/src/cmd/compile/internal/ssa/gen/decOps.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 1c37fbe0db4a49b7c7ff6d6a9668a6fdc745218a..8ce13abed30aa693d1625609767319e1c94263a2 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -2069,6 +2069,8 @@ const (
 	OpRISCV64MULW
 	OpRISCV64MULH
 	OpRISCV64MULHU
+	OpRISCV64LoweredMuluhilo
+	OpRISCV64LoweredMuluover
 	OpRISCV64DIV
 	OpRISCV64DIVU
 	OpRISCV64DIVW
@@ -20664,7 +20666,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:         "CALLstatic",
 		auxType:      auxCallOff,
-		argLen:       1,
+		argLen:       -1,
 		clobberFlags: true,
 		call:         true,
 		reg: regInfo{
@@ -20674,7 +20676,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:         "CALLclosure",
 		auxType:      auxCallOff,
-		argLen:       3,
+		argLen:       -1,
 		clobberFlags: true,
 		call:         true,
 		reg: regInfo{
@@ -20688,7 +20690,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:         "CALLinter",
 		auxType:      auxCallOff,
-		argLen:       2,
+		argLen:       -1,
 		clobberFlags: true,
 		call:         true,
 		reg: regInfo{
@@ -27603,6 +27605,36 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:            "LoweredMuluhilo",
+		argLen:          2,
+		resultNotInArgs: true,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+				{1, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+			outputs: []outputInfo{
+				{0, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+				{1, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+		},
+	},
+	{
+		name:            "LoweredMuluover",
+		argLen:          2,
+		resultNotInArgs: true,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+				{1, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+			outputs: []outputInfo{
+				{0, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+				{1, 1006632948}, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+		},
+	},
 	{
 		name:   "DIV",
 		argLen: 2,
@@ -36400,8 +36432,8 @@ var registersARM64 = [...]Register{
 	{62, arm64.REG_F31, -1, "F31"},
 	{63, 0, -1, "SB"},
 }
-var paramIntRegARM64 = []int8(nil)
-var paramFloatRegARM64 = []int8(nil)
+var paramIntRegARM64 = []int8{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
+var paramFloatRegARM64 = []int8{31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46}
 var gpRegMaskARM64 = regMask(670826495)
 var fpRegMaskARM64 = regMask(9223372034707292160)
 var specialRegMaskARM64 = regMask(0)
diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go
index 3b90b8769c2f1d8ffe484b0ab40d832aea650175..28fac6ccd0422bfdeeb9fcd34d21008835b2e20c 100644
--- a/src/cmd/compile/internal/ssa/regalloc.go
+++ b/src/cmd/compile/internal/ssa/regalloc.go
@@ -620,20 +620,20 @@ func (s *regAllocState) init(f *Func) {
 	}
 	if s.f.Config.ctxt.Flag_dynlink {
 		switch s.f.Config.arch {
-		case "amd64":
-			s.allocatable &^= 1 << 15 // R15
-		case "arm":
-			s.allocatable &^= 1 << 9 // R9
-		case "ppc64le": // R2 already reserved.
-			// nothing to do
-		case "arm64":
-			// nothing to do?
 		case "386":
 			// nothing to do.
 			// Note that for Flag_shared (position independent code)
 			// we do need to be careful, but that carefulness is hidden
 			// in the rewrite rules so we always have a free register
 			// available for global load/stores. See gen/386.rules (search for Flag_shared).
+		case "amd64":
+			s.allocatable &^= 1 << 15 // R15
+		case "arm":
+			s.allocatable &^= 1 << 9 // R9
+		case "arm64":
+			// nothing to do
+		case "ppc64le": // R2 already reserved.
+			// nothing to do
 		case "s390x":
 			s.allocatable &^= 1 << 11 // R11
 		default:
@@ -1865,23 +1865,6 @@ func (s *regAllocState) regalloc(f *Func) {
 }
 
 func (s *regAllocState) placeSpills() {
-	f := s.f
-
-	// Precompute some useful info.
-	phiRegs := make([]regMask, f.NumBlocks())
-	for _, b := range s.visitOrder {
-		var m regMask
-		for _, v := range b.Values {
-			if v.Op != OpPhi {
-				break
-			}
-			if r, ok := f.getHome(v.ID).(*Register); ok {
-				m |= regMask(1) << uint(r.num)
-			}
-		}
-		phiRegs[b.ID] = m
-	}
-
 	mustBeFirst := func(op Op) bool {
 		return op.isLoweredGetClosurePtr() || op == OpPhi || op == OpArgIntReg || op == OpArgFloatReg
 	}
diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index 375c4d5a5605f531b6b5ab761be276f41d72031b..115d5639333d89fd876f6fabbe7713d6a8fa77bd 100644
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -745,27 +745,21 @@ func uaddOvf(a, b int64) bool {
 	return uint64(a)+uint64(b) < uint64(a)
 }
 
-// de-virtualize an InterCall
-// 'sym' is the symbol for the itab
-func devirt(v *Value, aux Aux, sym Sym, offset int64) *AuxCall {
-	f := v.Block.Func
-	n, ok := sym.(*obj.LSym)
-	if !ok {
+// loadLSymOffset simulates reading a word at an offset into a
+// read-only symbol's runtime memory. If it would read a pointer to
+// another symbol, that symbol is returned. Otherwise, it returns nil.
+func loadLSymOffset(lsym *obj.LSym, offset int64) *obj.LSym {
+	if lsym.Type != objabi.SRODATA {
 		return nil
 	}
-	lsym := f.fe.DerefItab(n, offset)
-	if f.pass.debug > 0 {
-		if lsym != nil {
-			f.Warnl(v.Pos, "de-virtualizing call")
-		} else {
-			f.Warnl(v.Pos, "couldn't de-virtualize call")
+
+	for _, r := range lsym.R {
+		if int64(r.Off) == offset && r.Type&^objabi.R_WEAK == objabi.R_ADDR && r.Add == 0 {
+			return r.Sym
 		}
 	}
-	if lsym == nil {
-		return nil
-	}
-	va := aux.(*AuxCall)
-	return StaticAuxCall(lsym, va.abiInfo)
+
+	return nil
 }
 
 // de-virtualize an InterLECall
@@ -776,18 +770,14 @@ func devirtLESym(v *Value, aux Aux, sym Sym, offset int64) *obj.LSym {
 		return nil
 	}
 
-	f := v.Block.Func
-	lsym := f.fe.DerefItab(n, offset)
-	if f.pass.debug > 0 {
+	lsym := loadLSymOffset(n, offset)
+	if f := v.Block.Func; f.pass.debug > 0 {
 		if lsym != nil {
 			f.Warnl(v.Pos, "de-virtualizing call")
 		} else {
 			f.Warnl(v.Pos, "couldn't de-virtualize call")
 		}
 	}
-	if lsym == nil {
-		return nil
-	}
 	return lsym
 }
 
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index 5045ba7351f447ce13814b8ee6b3580cb9ed7ea6..89d32c06572cff466f3390c6757a84f0c839a25f 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -3,7 +3,6 @@
 
 package ssa
 
-import "internal/buildcfg"
 import "math"
 import "cmd/internal/obj"
 import "cmd/compile/internal/types"
@@ -29339,11 +29338,11 @@ func rewriteValueAMD64_OpFloor(v *Value) bool {
 func rewriteValueAMD64_OpGetG(v *Value) bool {
 	v_0 := v.Args[0]
 	// match: (GetG mem)
-	// cond: !(buildcfg.Experiment.RegabiG && v.Block.Func.OwnAux.Fn.ABI() == obj.ABIInternal)
+	// cond: v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal
 	// result: (LoweredGetG mem)
 	for {
 		mem := v_0
-		if !(!(buildcfg.Experiment.RegabiG && v.Block.Func.OwnAux.Fn.ABI() == obj.ABIInternal)) {
+		if !(v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal) {
 			break
 		}
 		v.reset(OpAMD64LoweredGetG)
diff --git a/src/cmd/compile/internal/ssa/rewriteARM64.go b/src/cmd/compile/internal/ssa/rewriteARM64.go
index 3cdc4d36cb5a400fbb419aa5b896074bc5243d61..f7840c5503975476d26d3d9531762cd5d41123a9 100644
--- a/src/cmd/compile/internal/ssa/rewriteARM64.go
+++ b/src/cmd/compile/internal/ssa/rewriteARM64.go
@@ -25997,7 +25997,7 @@ func rewriteValueARM64_OpSelectN(v *Value) bool {
 			break
 		}
 		call := v_0
-		if call.Op != OpARM64CALLstatic {
+		if call.Op != OpARM64CALLstatic || len(call.Args) != 1 {
 			break
 		}
 		sym := auxToCall(call.Aux)
@@ -26031,6 +26031,34 @@ func rewriteValueARM64_OpSelectN(v *Value) bool {
 		v.AddArg3(dst, src, mem)
 		return true
 	}
+	// match: (SelectN [0] call:(CALLstatic {sym} dst src (MOVDconst [sz]) mem))
+	// cond: sz >= 0 && isSameCall(sym, "runtime.memmove") && call.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(call)
+	// result: (Move [sz] dst src mem)
+	for {
+		if auxIntToInt64(v.AuxInt) != 0 {
+			break
+		}
+		call := v_0
+		if call.Op != OpARM64CALLstatic || len(call.Args) != 4 {
+			break
+		}
+		sym := auxToCall(call.Aux)
+		mem := call.Args[3]
+		dst := call.Args[0]
+		src := call.Args[1]
+		call_2 := call.Args[2]
+		if call_2.Op != OpARM64MOVDconst {
+			break
+		}
+		sz := auxIntToInt64(call_2.AuxInt)
+		if !(sz >= 0 && isSameCall(sym, "runtime.memmove") && call.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(call)) {
+			break
+		}
+		v.reset(OpMove)
+		v.AuxInt = int64ToAuxInt(sz)
+		v.AddArg3(dst, src, mem)
+		return true
+	}
 	return false
 }
 func rewriteValueARM64_OpSlicemask(v *Value) bool {
diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index 431fb1aaf66e0dd288704707d9ed909780533d4b..641be038dba02800393c8835afcacfbf5c25a805 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -356,6 +356,12 @@ func rewriteValueRISCV64(v *Value) bool {
 	case OpMul64F:
 		v.Op = OpRISCV64FMULD
 		return true
+	case OpMul64uhilo:
+		v.Op = OpRISCV64LoweredMuluhilo
+		return true
+	case OpMul64uover:
+		v.Op = OpRISCV64LoweredMuluover
+		return true
 	case OpMul8:
 		return rewriteValueRISCV64_OpMul8(v)
 	case OpNeg16:
@@ -6096,6 +6102,18 @@ func rewriteBlockRISCV64(b *Block) bool {
 			b.resetWithControl(BlockRISCV64BEQZ, x)
 			return true
 		}
+		// match: (BEQZ x:(NEG y) yes no)
+		// cond: x.Uses == 1
+		// result: (BEQZ y yes no)
+		for b.Controls[0].Op == OpRISCV64NEG {
+			x := b.Controls[0]
+			y := x.Args[0]
+			if !(x.Uses == 1) {
+				break
+			}
+			b.resetWithControl(BlockRISCV64BEQZ, y)
+			return true
+		}
 		// match: (BEQZ (SUB x y) yes no)
 		// result: (BEQ x y yes no)
 		for b.Controls[0].Op == OpRISCV64SUB {
@@ -6123,6 +6141,52 @@ func rewriteBlockRISCV64(b *Block) bool {
 			b.resetWithControl2(BlockRISCV64BGEU, x, y)
 			return true
 		}
+	case BlockRISCV64BGE:
+		// match: (BGE (MOVDconst [0]) cond yes no)
+		// result: (BLEZ cond yes no)
+		for b.Controls[0].Op == OpRISCV64MOVDconst {
+			v_0 := b.Controls[0]
+			if auxIntToInt64(v_0.AuxInt) != 0 {
+				break
+			}
+			cond := b.Controls[1]
+			b.resetWithControl(BlockRISCV64BLEZ, cond)
+			return true
+		}
+		// match: (BGE cond (MOVDconst [0]) yes no)
+		// result: (BGEZ cond yes no)
+		for b.Controls[1].Op == OpRISCV64MOVDconst {
+			cond := b.Controls[0]
+			v_1 := b.Controls[1]
+			if auxIntToInt64(v_1.AuxInt) != 0 {
+				break
+			}
+			b.resetWithControl(BlockRISCV64BGEZ, cond)
+			return true
+		}
+	case BlockRISCV64BLT:
+		// match: (BLT (MOVDconst [0]) cond yes no)
+		// result: (BGTZ cond yes no)
+		for b.Controls[0].Op == OpRISCV64MOVDconst {
+			v_0 := b.Controls[0]
+			if auxIntToInt64(v_0.AuxInt) != 0 {
+				break
+			}
+			cond := b.Controls[1]
+			b.resetWithControl(BlockRISCV64BGTZ, cond)
+			return true
+		}
+		// match: (BLT cond (MOVDconst [0]) yes no)
+		// result: (BLTZ cond yes no)
+		for b.Controls[1].Op == OpRISCV64MOVDconst {
+			cond := b.Controls[0]
+			v_1 := b.Controls[1]
+			if auxIntToInt64(v_1.AuxInt) != 0 {
+				break
+			}
+			b.resetWithControl(BlockRISCV64BLTZ, cond)
+			return true
+		}
 	case BlockRISCV64BNE:
 		// match: (BNE (MOVDconst [0]) cond yes no)
 		// result: (BNEZ cond yes no)
@@ -6163,6 +6227,18 @@ func rewriteBlockRISCV64(b *Block) bool {
 			b.resetWithControl(BlockRISCV64BNEZ, x)
 			return true
 		}
+		// match: (BNEZ x:(NEG y) yes no)
+		// cond: x.Uses == 1
+		// result: (BNEZ y yes no)
+		for b.Controls[0].Op == OpRISCV64NEG {
+			x := b.Controls[0]
+			y := x.Args[0]
+			if !(x.Uses == 1) {
+				break
+			}
+			b.resetWithControl(BlockRISCV64BNEZ, y)
+			return true
+		}
 		// match: (BNEZ (SUB x y) yes no)
 		// result: (BNE x y yes no)
 		for b.Controls[0].Op == OpRISCV64SUB {
diff --git a/src/cmd/compile/internal/ssa/schedule.go b/src/cmd/compile/internal/ssa/schedule.go
index 4e3e5e75e358d7f1d75a0a5c2888efdfe8fe398a..c5130b2ee50b99157fd86c04c245d926cebf03be 100644
--- a/src/cmd/compile/internal/ssa/schedule.go
+++ b/src/cmd/compile/internal/ssa/schedule.go
@@ -220,7 +220,7 @@ func schedule(f *Func) {
 			// unless they are phi values (which must be first).
 			// OpArg also goes first -- if it is stack it register allocates
 			// to a LoadReg, if it is register it is from the beginning anyway.
-			if c.Op == OpPhi || c.Op == OpArg {
+			if score[c.ID] == ScorePhi || score[c.ID] == ScoreArg {
 				continue
 			}
 			score[c.ID] = ScoreControl
diff --git a/src/cmd/compile/internal/ssa/softfloat.go b/src/cmd/compile/internal/ssa/softfloat.go
index a8a8f836294b9790c4864f9674aa4dad2b94fe7c..351f824a9f579a2f8d4675e0be4d6d2a256631f2 100644
--- a/src/cmd/compile/internal/ssa/softfloat.go
+++ b/src/cmd/compile/internal/ssa/softfloat.go
@@ -63,6 +63,7 @@ func softfloat(f *Func) {
 					v.Aux = f.Config.Types.UInt32
 				case 8:
 					v.Aux = f.Config.Types.UInt64
+					newInt64 = true
 				default:
 					v.Fatalf("bad float type with size %d", size)
 				}
diff --git a/src/cmd/compile/internal/ssa/writebarrier.go b/src/cmd/compile/internal/ssa/writebarrier.go
index 419d91d0d367e609dcf9874cced1a58c04acdb4a..d7510965f6b31a6b9a3b83e76ab9ab1587834449 100644
--- a/src/cmd/compile/internal/ssa/writebarrier.go
+++ b/src/cmd/compile/internal/ssa/writebarrier.go
@@ -552,6 +552,9 @@ func IsStackAddr(v *Value) bool {
 
 // IsGlobalAddr reports whether v is known to be an address of a global (or nil).
 func IsGlobalAddr(v *Value) bool {
+	for v.Op == OpOffPtr || v.Op == OpAddPtr || v.Op == OpPtrIndex || v.Op == OpCopy {
+		v = v.Args[0]
+	}
 	if v.Op == OpAddr && v.Args[0].Op == OpSB {
 		return true // address of a global
 	}
diff --git a/src/cmd/compile/internal/ssagen/abi.go b/src/cmd/compile/internal/ssagen/abi.go
index e460adaf95d143f2403f40a0ab0607a68ef2ffb1..6d8c53e7225fd93893852a1348171be89cc1d7f2 100644
--- a/src/cmd/compile/internal/ssagen/abi.go
+++ b/src/cmd/compile/internal/ssagen/abi.go
@@ -152,6 +152,9 @@ func (s *SymABIs) GenABIWrappers() {
 		// Apply definitions.
 		defABI, hasDefABI := s.defs[symName]
 		if hasDefABI {
+			if len(fn.Body) != 0 {
+				base.ErrorfAt(fn.Pos(), "%v defined in both Go and assembly", fn)
+			}
 			fn.ABI = defABI
 		}
 
diff --git a/src/cmd/compile/internal/ssagen/arch.go b/src/cmd/compile/internal/ssagen/arch.go
index 7215f42c059a147272500b7916df51287e7bdd7b..483e45cad43c7445c46032111434fffe16cd62a7 100644
--- a/src/cmd/compile/internal/ssagen/arch.go
+++ b/src/cmd/compile/internal/ssagen/arch.go
@@ -29,8 +29,7 @@ type ArchInfo struct {
 	// at function entry, and it is ok to clobber registers.
 	ZeroRange func(*objw.Progs, *obj.Prog, int64, int64, *uint32) *obj.Prog
 
-	Ginsnop      func(*objw.Progs) *obj.Prog
-	Ginsnopdefer func(*objw.Progs) *obj.Prog // special ginsnop for deferreturn
+	Ginsnop func(*objw.Progs) *obj.Prog
 
 	// SSAMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
 	SSAMarkMoves func(*State, *ssa.Block)
@@ -42,10 +41,10 @@ type ArchInfo struct {
 	// for all values in the block before SSAGenBlock.
 	SSAGenBlock func(s *State, b, next *ssa.Block)
 
-	// LoadRegResults emits instructions that loads register-assigned results
-	// into registers. They are already in memory (PPARAMOUT nodes).
-	// Used in open-coded defer return path.
-	LoadRegResults func(s *State, f *ssa.Func)
+	// LoadRegResult emits instructions that loads register-assigned result
+	// at n+off (n is PPARAMOUT) to register reg. The result is already in
+	// memory. Used in open-coded defer return path.
+	LoadRegResult func(s *State, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog
 
 	// SpillArgReg emits instructions that spill reg to n+off.
 	SpillArgReg func(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog
diff --git a/src/cmd/compile/internal/ssagen/pgen.go b/src/cmd/compile/internal/ssagen/pgen.go
index 62567535d76caccdd37e1fdea3996b51a0fac13c..93157bfa11b56a93592ce93dc9f0bf621b307782 100644
--- a/src/cmd/compile/internal/ssagen/pgen.go
+++ b/src/cmd/compile/internal/ssagen/pgen.go
@@ -114,7 +114,10 @@ func (s *ssafn) AllocFrame(f *ssa.Func) {
 		}
 	}
 
-	sort.Sort(byStackVar(fn.Dcl))
+	// Use sort.Stable instead of sort.Sort so stack layout (and thus
+	// compiler output) is less sensitive to frontend changes that
+	// introduce or remove unused variables.
+	sort.Stable(byStackVar(fn.Dcl))
 
 	// Reassign stack offsets of the locals that are used.
 	lastHasPtr := false
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index dfa76006de790110b05def67fe3d8a4451584245..39d3b206ac6e1b5f259acd4dd72c5dbd376f0814 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -87,8 +87,7 @@ func InitConfig() {
 	_ = types.NewPtr(types.Types[types.TINT64])                             // *int64
 	_ = types.NewPtr(types.ErrorType)                                       // *error
 	types.NewPtrCacheEnabled = false
-	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0)
-	ssaConfig.SoftFloat = Arch.SoftFloat
+	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0, Arch.SoftFloat)
 	ssaConfig.Race = base.Flag.Race
 	ssaCaches = make([]ssa.Cache, base.Flag.LowerC)
 
@@ -279,18 +278,6 @@ func regAbiForFuncType(ft *types.Func) bool {
 	return np > 0 && strings.Contains(ft.Params.FieldType(np-1).String(), magicLastTypeName)
 }
 
-// getParam returns the Field of ith param of node n (which is a
-// function/method/interface call), where the receiver of a method call is
-// considered as the 0th parameter. This does not include the receiver of an
-// interface call.
-func getParam(n *ir.CallExpr, i int) *types.Field {
-	t := n.X.Type()
-	if n.Op() == ir.OCALLMETH {
-		base.Fatalf("OCALLMETH missed by walkCall")
-	}
-	return t.Params().Field(i)
-}
-
 // dvarint writes a varint v to the funcdata in symbol x and returns the new offset
 func dvarint(x *obj.LSym, off int, v int64) int {
 	if v < 0 || v > 1e9 {
@@ -324,66 +311,21 @@ func dvarint(x *obj.LSym, off int, v int64) int {
 // for stack variables are specified as the number of bytes below varp (pointer to the
 // top of the local variables) for their starting address. The format is:
 //
-//  - Max total argument size among all the defers
 //  - Offset of the deferBits variable
 //  - Number of defers in the function
 //  - Information about each defer call, in reverse order of appearance in the function:
-//    - Total argument size of the call
 //    - Offset of the closure value to call
-//    - Number of arguments (including interface receiver or method receiver as first arg)
-//    - Information about each argument
-//      - Offset of the stored defer argument in this function's frame
-//      - Size of the argument
-//      - Offset of where argument should be placed in the args frame when making call
 func (s *state) emitOpenDeferInfo() {
 	x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
 	s.curfn.LSym.Func().OpenCodedDeferInfo = x
 	off := 0
-
-	// Compute maxargsize (max size of arguments for all defers)
-	// first, so we can output it first to the funcdata
-	var maxargsize int64
-	for i := len(s.openDefers) - 1; i >= 0; i-- {
-		r := s.openDefers[i]
-		argsize := r.n.X.Type().ArgWidth() // TODO register args: but maybe use of abi0 will make this easy
-		if argsize > maxargsize {
-			maxargsize = argsize
-		}
-	}
-	off = dvarint(x, off, maxargsize)
 	off = dvarint(x, off, -s.deferBitsTemp.FrameOffset())
 	off = dvarint(x, off, int64(len(s.openDefers)))
 
 	// Write in reverse-order, for ease of running in that order at runtime
 	for i := len(s.openDefers) - 1; i >= 0; i-- {
 		r := s.openDefers[i]
-		off = dvarint(x, off, r.n.X.Type().ArgWidth())
 		off = dvarint(x, off, -r.closureNode.FrameOffset())
-		numArgs := len(r.argNodes)
-		if r.rcvrNode != nil {
-			// If there's an interface receiver, treat/place it as the first
-			// arg. (If there is a method receiver, it's already included as
-			// first arg in r.argNodes.)
-			numArgs++
-		}
-		off = dvarint(x, off, int64(numArgs))
-		argAdjust := 0 // presence of receiver offsets the parameter count.
-		if r.rcvrNode != nil {
-			off = dvarint(x, off, -okOffset(r.rcvrNode.FrameOffset()))
-			off = dvarint(x, off, s.config.PtrSize)
-			off = dvarint(x, off, 0) // This is okay because defer records use ABI0 (for now)
-			argAdjust++
-		}
-
-		// TODO(register args) assume abi0 for this?
-		ab := s.f.ABI0
-		pri := ab.ABIAnalyzeFuncType(r.n.X.Type().FuncType())
-		for j, arg := range r.argNodes {
-			f := getParam(r.n, j)
-			off = dvarint(x, off, -okOffset(arg.FrameOffset()))
-			off = dvarint(x, off, f.Type.Size())
-			off = dvarint(x, off, okOffset(pri.InParam(j+argAdjust).FrameOffset(pri)))
-		}
 	}
 }
 
@@ -580,7 +522,7 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 	}
 
 	// Populate closure variables.
-	if !fn.ClosureCalled() {
+	if fn.Needctxt() {
 		clo := s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr)
 		offset := int64(types.PtrSize) // PtrSize to skip past function entry PC field
 		for _, n := range fn.ClosureVars {
@@ -650,7 +592,6 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
 	// clear if naming conventions are respected in autogenerated code.
 	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
-	// TODO non-amd64 architectures have link registers etc that may require adjustment here.
 	for _, p := range params.InParams() {
 		typs, offs := p.RegisterTypesAndOffsets()
 		for i, t := range typs {
@@ -865,16 +806,6 @@ type openDeferInfo struct {
 	// function, method, or interface call, to store a closure that panic
 	// processing can use for this defer.
 	closureNode *ir.Name
-	// If defer call is interface call, the address of the argtmp where the
-	// receiver is stored
-	rcvr *ssa.Value
-	// The node representing the argtmp where the receiver is stored
-	rcvrNode *ir.Name
-	// The addresses of the argtmps where the evaluated arguments of the defer
-	// function call are stored.
-	argVals []*ssa.Value
-	// The nodes representing the argtmps where the args of the defer are stored
-	argNodes []*ir.Name
 }
 
 type state struct {
@@ -1491,7 +1422,12 @@ func (s *state) stmt(n ir.Node) {
 
 	case ir.OAS2DOTTYPE:
 		n := n.(*ir.AssignListStmt)
-		res, resok := s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
+		var res, resok *ssa.Value
+		if n.Rhs[0].Op() == ir.ODOTTYPE2 {
+			res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
+		} else {
+			res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
+		}
 		deref := false
 		if !TypeOK(n.Rhs[0].Type()) {
 			if res.Op != ssa.OpLoad {
@@ -2748,6 +2684,11 @@ func (s *state) expr(n ir.Node) *ssa.Value {
 		res, _ := s.dottype(n, false)
 		return res
 
+	case ir.ODYNAMICDOTTYPE:
+		n := n.(*ir.DynamicTypeAssertExpr)
+		res, _ := s.dynamicDottype(n, false)
+		return res
+
 	// binary ops
 	case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
 		n := n.(*ir.BinaryExpr)
@@ -3183,7 +3124,7 @@ func (s *state) expr(n ir.Node) *ssa.Value {
 		}
 		fallthrough
 
-	case ir.OCALLINTER, ir.OCALLMETH:
+	case ir.OCALLINTER:
 		n := n.(*ir.CallExpr)
 		return s.callResult(n, callNormal)
 
@@ -3191,6 +3132,14 @@ func (s *state) expr(n ir.Node) *ssa.Value {
 		n := n.(*ir.CallExpr)
 		return s.newValue1(ssa.OpGetG, n.Type(), s.mem())
 
+	case ir.OGETCALLERPC:
+		n := n.(*ir.CallExpr)
+		return s.newValue0(ssa.OpGetCallerPC, n.Type())
+
+	case ir.OGETCALLERSP:
+		n := n.(*ir.CallExpr)
+		return s.newValue0(ssa.OpGetCallerSP, n.Type())
+
 	case ir.OAPPEND:
 		return s.append(n.(*ir.CallExpr), false)
 
@@ -3703,6 +3652,16 @@ func softfloatInit() {
 // TODO: do not emit sfcall if operation can be optimized to constant in later
 // opt phase
 func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
+	f2i := func(t *types.Type) *types.Type {
+		switch t.Kind() {
+		case types.TFLOAT32:
+			return types.Types[types.TUINT32]
+		case types.TFLOAT64:
+			return types.Types[types.TUINT64]
+		}
+		return t
+	}
+
 	if callDef, ok := softFloatOps[op]; ok {
 		switch op {
 		case ssa.OpLess32F,
@@ -3715,7 +3674,19 @@ func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
 			args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
 		}
 
-		result := s.rtcall(callDef.rtfn, true, []*types.Type{types.Types[callDef.rtype]}, args...)[0]
+		// runtime functions take uints for floats and returns uints.
+		// Convert to uints so we use the right calling convention.
+		for i, a := range args {
+			if a.Type.IsFloat() {
+				args[i] = s.newValue1(ssa.OpCopy, f2i(a.Type), a)
+			}
+		}
+
+		rt := types.Types[callDef.rtype]
+		result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
+		if rt.IsFloat() {
+			result = s.newValue1(ssa.OpCopy, rt, result)
+		}
 		if op == ssa.OpNeq32F || op == ssa.OpNeq64F {
 			result = s.newValue1(ssa.OpNot, result.Type, result)
 		}
@@ -3808,7 +3779,7 @@ func InitTables() {
 			}
 			return s.newValue2(ssa.OpMul64uover, types.NewTuple(types.Types[types.TUINT], types.Types[types.TUINT]), args[0], args[1])
 		},
-		sys.AMD64, sys.I386, sys.MIPS64)
+		sys.AMD64, sys.I386, sys.MIPS64, sys.RISCV64)
 	add("runtime", "KeepAlive",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			data := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, args[0])
@@ -4534,9 +4505,9 @@ func InitTables() {
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			return s.newValue2(ssa.OpMul64uhilo, types.NewTuple(types.Types[types.TUINT64], types.Types[types.TUINT64]), args[0], args[1])
 		},
-		sys.AMD64, sys.ARM64, sys.PPC64, sys.S390X, sys.MIPS64)
-	alias("math/bits", "Mul", "math/bits", "Mul64", sys.ArchAMD64, sys.ArchARM64, sys.ArchPPC64, sys.ArchPPC64LE, sys.ArchS390X, sys.ArchMIPS64, sys.ArchMIPS64LE)
-	alias("runtime/internal/math", "Mul64", "math/bits", "Mul64", sys.ArchAMD64, sys.ArchARM64, sys.ArchPPC64, sys.ArchPPC64LE, sys.ArchS390X, sys.ArchMIPS64, sys.ArchMIPS64LE)
+		sys.AMD64, sys.ARM64, sys.PPC64, sys.S390X, sys.MIPS64, sys.RISCV64)
+	alias("math/bits", "Mul", "math/bits", "Mul64", sys.ArchAMD64, sys.ArchARM64, sys.ArchPPC64, sys.ArchPPC64LE, sys.ArchS390X, sys.ArchMIPS64, sys.ArchMIPS64LE, sys.ArchRISCV64)
+	alias("runtime/internal/math", "Mul64", "math/bits", "Mul64", sys.ArchAMD64, sys.ArchARM64, sys.ArchPPC64, sys.ArchPPC64LE, sys.ArchS390X, sys.ArchMIPS64, sys.ArchMIPS64LE, sys.ArchRISCV64)
 	addF("math/bits", "Add64",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			return s.newValue3(ssa.OpAdd64carry, types.NewTuple(types.Types[types.TUINT64], types.Types[types.TUINT64]), args[0], args[1], args[2])
@@ -4687,17 +4658,14 @@ func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
 	return args
 }
 
-// openDeferRecord adds code to evaluate and store the args for an open-code defer
+// openDeferRecord adds code to evaluate and store the function for an open-code defer
 // call, and records info about the defer, so we can generate proper code on the
 // exit paths. n is the sub-node of the defer node that is the actual function
-// call. We will also record funcdata information on where the args are stored
+// call. We will also record funcdata information on where the function is stored
 // (as well as the deferBits variable), and this will enable us to run the proper
 // defer calls during panics.
 func (s *state) openDeferRecord(n *ir.CallExpr) {
-	var args []*ssa.Value
-	var argNodes []*ir.Name
-
-	if buildcfg.Experiment.RegabiDefer && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
+	if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.X.Type().NumResults() != 0 {
 		s.Fatalf("defer call with arguments or results: %v", n)
 	}
 
@@ -4705,48 +4673,20 @@ func (s *state) openDeferRecord(n *ir.CallExpr) {
 		n: n,
 	}
 	fn := n.X
-	if n.Op() == ir.OCALLFUNC {
-		// We must always store the function value in a stack slot for the
-		// runtime panic code to use. But in the defer exit code, we will
-		// call the function directly if it is a static function.
-		closureVal := s.expr(fn)
-		closure := s.openDeferSave(nil, fn.Type(), closureVal)
-		opendefer.closureNode = closure.Aux.(*ir.Name)
-		if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
-			opendefer.closure = closure
-		}
-	} else if n.Op() == ir.OCALLMETH {
-		base.Fatalf("OCALLMETH missed by walkCall")
-	} else {
-		if fn.Op() != ir.ODOTINTER {
-			base.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
-		}
-		fn := fn.(*ir.SelectorExpr)
-		closure, rcvr := s.getClosureAndRcvr(fn)
-		opendefer.closure = s.openDeferSave(nil, closure.Type, closure)
-		// Important to get the receiver type correct, so it is recognized
-		// as a pointer for GC purposes.
-		opendefer.rcvr = s.openDeferSave(nil, fn.Type().Recv().Type, rcvr)
-		opendefer.closureNode = opendefer.closure.Aux.(*ir.Name)
-		opendefer.rcvrNode = opendefer.rcvr.Aux.(*ir.Name)
-	}
-	for _, argn := range n.Args {
-		var v *ssa.Value
-		if TypeOK(argn.Type()) {
-			v = s.openDeferSave(nil, argn.Type(), s.expr(argn))
-		} else {
-			v = s.openDeferSave(argn, argn.Type(), nil)
-		}
-		args = append(args, v)
-		argNodes = append(argNodes, v.Aux.(*ir.Name))
+	// We must always store the function value in a stack slot for the
+	// runtime panic code to use. But in the defer exit code, we will
+	// call the function directly if it is a static function.
+	closureVal := s.expr(fn)
+	closure := s.openDeferSave(fn.Type(), closureVal)
+	opendefer.closureNode = closure.Aux.(*ir.Name)
+	if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
+		opendefer.closure = closure
 	}
-	opendefer.argVals = args
-	opendefer.argNodes = argNodes
 	index := len(s.openDefers)
 	s.openDefers = append(s.openDefers, opendefer)
 
 	// Update deferBits only after evaluation and storage to stack of
-	// args/receiver/interface is successful.
+	// the function is successful.
 	bitvalue := s.constInt8(types.Types[types.TUINT8], 1< 0 {
-				base.WarnfAt(n.Pos(), "type assertion inlined")
+				base.WarnfAt(pos, "type assertion inlined")
 			}
 
 			// Get itab/type field from input.
@@ -6225,7 +6117,7 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 			// Conversion succeeds iff that field is not nil.
 			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
 
-			if n.X.Type().IsEmptyInterface() && commaok {
+			if src.IsEmptyInterface() && commaok {
 				// Converting empty interface to empty interface with ,ok is just a nil check.
 				return iface, cond
 			}
@@ -6247,7 +6139,7 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 
 				// On success, return (perhaps modified) input interface.
 				s.startBlock(bOk)
-				if n.X.Type().IsEmptyInterface() {
+				if src.IsEmptyInterface() {
 					res = iface // Use input interface unchanged.
 					return
 				}
@@ -6255,7 +6147,7 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 				off := s.newValue1I(ssa.OpOffPtr, byteptr, int64(types.PtrSize), itab)
 				typ := s.load(byteptr, off)
 				idata := s.newValue1(ssa.OpIData, byteptr, iface)
-				res = s.newValue2(ssa.OpIMake, n.Type(), typ, idata)
+				res = s.newValue2(ssa.OpIMake, dst, typ, idata)
 				return
 			}
 
@@ -6277,62 +6169,62 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 			bFail.AddEdgeTo(bEnd)
 			s.startBlock(bEnd)
 			idata := s.newValue1(ssa.OpIData, byteptr, iface)
-			res = s.newValue2(ssa.OpIMake, n.Type(), s.variable(typVar, byteptr), idata)
+			res = s.newValue2(ssa.OpIMake, dst, s.variable(typVar, byteptr), idata)
 			resok = cond
 			delete(s.vars, typVar)
 			return
 		}
 		// converting to a nonempty interface needs a runtime call.
 		if base.Debug.TypeAssert > 0 {
-			base.WarnfAt(n.Pos(), "type assertion not inlined")
+			base.WarnfAt(pos, "type assertion not inlined")
 		}
 		if !commaok {
 			fn := ir.Syms.AssertI2I
-			if n.X.Type().IsEmptyInterface() {
+			if src.IsEmptyInterface() {
 				fn = ir.Syms.AssertE2I
 			}
 			data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
 			tab := s.newValue1(ssa.OpITab, byteptr, iface)
 			tab = s.rtcall(fn, true, []*types.Type{byteptr}, target, tab)[0]
-			return s.newValue2(ssa.OpIMake, n.Type(), tab, data), nil
+			return s.newValue2(ssa.OpIMake, dst, tab, data), nil
 		}
 		fn := ir.Syms.AssertI2I2
-		if n.X.Type().IsEmptyInterface() {
+		if src.IsEmptyInterface() {
 			fn = ir.Syms.AssertE2I2
 		}
-		res = s.rtcall(fn, true, []*types.Type{n.Type()}, target, iface)[0]
-		resok = s.newValue2(ssa.OpNeqInter, types.Types[types.TBOOL], res, s.constInterface(n.Type()))
+		res = s.rtcall(fn, true, []*types.Type{dst}, target, iface)[0]
+		resok = s.newValue2(ssa.OpNeqInter, types.Types[types.TBOOL], res, s.constInterface(dst))
 		return
 	}
 
 	if base.Debug.TypeAssert > 0 {
-		base.WarnfAt(n.Pos(), "type assertion inlined")
+		base.WarnfAt(pos, "type assertion inlined")
 	}
 
 	// Converting to a concrete type.
-	direct := types.IsDirectIface(n.Type())
+	direct := types.IsDirectIface(dst)
 	itab := s.newValue1(ssa.OpITab, byteptr, iface) // type word of interface
 	if base.Debug.TypeAssert > 0 {
-		base.WarnfAt(n.Pos(), "type assertion inlined")
+		base.WarnfAt(pos, "type assertion inlined")
 	}
-	var targetITab *ssa.Value
-	if n.X.Type().IsEmptyInterface() {
+	var wantedFirstWord *ssa.Value
+	if src.IsEmptyInterface() {
 		// Looking for pointer to target type.
-		targetITab = target
+		wantedFirstWord = target
 	} else {
 		// Looking for pointer to itab for target type and source interface.
-		targetITab = s.expr(n.Itab)
+		wantedFirstWord = targetItab
 	}
 
 	var tmp ir.Node     // temporary for use with large types
 	var addr *ssa.Value // address of tmp
-	if commaok && !TypeOK(n.Type()) {
+	if commaok && !TypeOK(dst) {
 		// unSSAable type, use temporary.
 		// TODO: get rid of some of these temporaries.
-		tmp, addr = s.temp(n.Pos(), n.Type())
+		tmp, addr = s.temp(pos, dst)
 	}
 
-	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, targetITab)
+	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
 	b := s.endBlock()
 	b.Kind = ssa.BlockIf
 	b.SetControl(cond)
@@ -6346,8 +6238,8 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 	if !commaok {
 		// on failure, panic by calling panicdottype
 		s.startBlock(bFail)
-		taddr := s.reflectType(n.X.Type())
-		if n.X.Type().IsEmptyInterface() {
+		taddr := s.reflectType(src)
+		if src.IsEmptyInterface() {
 			s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
 		} else {
 			s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
@@ -6356,10 +6248,10 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 		// on success, return data from interface
 		s.startBlock(bOk)
 		if direct {
-			return s.newValue1(ssa.OpIData, n.Type(), iface), nil
+			return s.newValue1(ssa.OpIData, dst, iface), nil
 		}
-		p := s.newValue1(ssa.OpIData, types.NewPtr(n.Type()), iface)
-		return s.load(n.Type(), p), nil
+		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
+		return s.load(dst, p), nil
 	}
 
 	// commaok is the more complicated case because we have
@@ -6373,14 +6265,14 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 	s.startBlock(bOk)
 	if tmp == nil {
 		if direct {
-			s.vars[valVar] = s.newValue1(ssa.OpIData, n.Type(), iface)
+			s.vars[valVar] = s.newValue1(ssa.OpIData, dst, iface)
 		} else {
-			p := s.newValue1(ssa.OpIData, types.NewPtr(n.Type()), iface)
-			s.vars[valVar] = s.load(n.Type(), p)
+			p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
+			s.vars[valVar] = s.load(dst, p)
 		}
 	} else {
-		p := s.newValue1(ssa.OpIData, types.NewPtr(n.Type()), iface)
-		s.move(n.Type(), addr, p)
+		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
+		s.move(dst, addr, p)
 	}
 	s.vars[okVar] = s.constBool(true)
 	s.endBlock()
@@ -6389,9 +6281,9 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 	// type assertion failed
 	s.startBlock(bFail)
 	if tmp == nil {
-		s.vars[valVar] = s.zeroVal(n.Type())
+		s.vars[valVar] = s.zeroVal(dst)
 	} else {
-		s.zero(n.Type(), addr)
+		s.zero(dst, addr)
 	}
 	s.vars[okVar] = s.constBool(false)
 	s.endBlock()
@@ -6400,10 +6292,10 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 	// merge point
 	s.startBlock(bEnd)
 	if tmp == nil {
-		res = s.variable(valVar, n.Type())
+		res = s.variable(valVar, dst)
 		delete(s.vars, valVar)
 	} else {
-		res = s.load(n.Type(), addr)
+		res = s.load(dst, addr)
 		s.vars[memVar] = s.newValue1A(ssa.OpVarKill, types.TypeMem, tmp.(*ir.Name), s.mem())
 	}
 	resok = s.variable(okVar, types.Types[types.TBOOL])
@@ -6921,8 +6813,12 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 		// recovers a panic, it will return to caller with right results.
 		// The results are already in memory, because they are not SSA'd
 		// when the function has defers (see canSSAName).
-		if f.OwnAux.ABIInfo().OutRegistersUsed() != 0 {
-			Arch.LoadRegResults(&s, f)
+		for _, o := range f.OwnAux.ABIInfo().OutParams() {
+			n := o.Name.(*ir.Name)
+			rts, offs := o.RegisterTypesAndOffsets()
+			for i := range o.Registers {
+				Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
+			}
 		}
 
 		pp.Prog(obj.ARET)
@@ -7460,18 +7356,6 @@ func (s *State) PrepareCall(v *ssa.Value) {
 
 	call, ok := v.Aux.(*ssa.AuxCall)
 
-	if ok && call.Fn == ir.Syms.Deferreturn {
-		// Deferred calls will appear to be returning to
-		// the CALL deferreturn(SB) that we are about to emit.
-		// However, the stack trace code will show the line
-		// of the instruction byte before the return PC.
-		// To avoid that being an unrelated instruction,
-		// insert an actual hardware NOP that will have the right line number.
-		// This is different from obj.ANOP, which is a virtual no-op
-		// that doesn't make it into the instruction stream.
-		Arch.Ginsnopdefer(s.pp)
-	}
-
 	if ok {
 		// Record call graph information for nowritebarrierrec
 		// analysis.
@@ -7542,10 +7426,6 @@ func (e *ssafn) Auto(pos src.XPos, t *types.Type) *ir.Name {
 	return typecheck.TempAt(pos, e.curfn, t) // Note: adds new auto to e.curfn.Func.Dcl list
 }
 
-func (e *ssafn) DerefItab(it *obj.LSym, offset int64) *obj.LSym {
-	return reflectdata.ITabSym(it, offset)
-}
-
 // SplitSlot returns a slot representing the data of parent starting at offset.
 func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
 	node := parent.N
@@ -7676,9 +7556,8 @@ func max8(a, b int8) int8 {
 	return b
 }
 
-// deferstruct makes a runtime._defer structure, with additional space for
-// stksize bytes of args.
-func deferstruct(stksize int64) *types.Type {
+// deferstruct makes a runtime._defer structure.
+func deferstruct() *types.Type {
 	makefield := func(name string, typ *types.Type) *types.Field {
 		// Unlike the global makefield function, this one needs to set Pkg
 		// because these types might be compared (in SSA CSE sorting).
@@ -7686,13 +7565,9 @@ func deferstruct(stksize int64) *types.Type {
 		sym := &types.Sym{Name: name, Pkg: types.LocalPkg}
 		return types.NewField(src.NoXPos, sym, typ)
 	}
-	argtype := types.NewArray(types.Types[types.TUINT8], stksize)
-	argtype.Width = stksize
-	argtype.Align = 1
 	// These fields must match the ones in runtime/runtime2.go:_defer and
-	// cmd/compile/internal/gc/ssa.go:(*state).call.
+	// (*state).call above.
 	fields := []*types.Field{
-		makefield("siz", types.Types[types.TUINT32]),
 		makefield("started", types.Types[types.TBOOL]),
 		makefield("heap", types.Types[types.TBOOL]),
 		makefield("openDefer", types.Types[types.TBOOL]),
@@ -7704,10 +7579,9 @@ func deferstruct(stksize int64) *types.Type {
 		makefield("fn", types.Types[types.TUINTPTR]),
 		makefield("_panic", types.Types[types.TUINTPTR]),
 		makefield("link", types.Types[types.TUINTPTR]),
-		makefield("framepc", types.Types[types.TUINTPTR]),
-		makefield("varp", types.Types[types.TUINTPTR]),
 		makefield("fd", types.Types[types.TUINTPTR]),
-		makefield("args", argtype),
+		makefield("varp", types.Types[types.TUINTPTR]),
+		makefield("framepc", types.Types[types.TUINTPTR]),
 	}
 
 	// build struct holding the above fields
diff --git a/src/cmd/compile/internal/staticdata/data.go b/src/cmd/compile/internal/staticdata/data.go
index abb0bba646e0caacf183e436cc084784b5907250..f25d8d8ec541f8a68aea5a513e4ae222397549fa 100644
--- a/src/cmd/compile/internal/staticdata/data.go
+++ b/src/cmd/compile/internal/staticdata/data.go
@@ -92,6 +92,10 @@ func StringSym(pos src.XPos, s string) (data *obj.LSym) {
 	return symdata
 }
 
+// maxFileSize is the maximum file size permitted by the linker
+// (see issue #9862).
+const maxFileSize = int64(2e9)
+
 // fileStringSym returns a symbol for the contents and the size of file.
 // If readonly is true, the symbol shares storage with any literal string
 // or other file with the same content and is placed in a read-only section.
@@ -133,12 +137,12 @@ func fileStringSym(pos src.XPos, file string, readonly bool, hash []byte) (*obj.
 		}
 		return sym, size, nil
 	}
-	if size > 2e9 {
+	if size > maxFileSize {
 		// ggloblsym takes an int32,
 		// and probably the rest of the toolchain
 		// can't handle such big symbols either.
 		// See golang.org/issue/9862.
-		return nil, 0, fmt.Errorf("file too large")
+		return nil, 0, fmt.Errorf("file too large (%d bytes > %d bytes)", size, maxFileSize)
 	}
 
 	// File is too big to read and keep in memory.
diff --git a/src/cmd/compile/internal/staticdata/embed.go b/src/cmd/compile/internal/staticdata/embed.go
index 8936c4f5b44e44c7f03edf81a137e49eb68ac564..0730d346b2402da1c9e7ea65f8bc1106b3559ed2 100644
--- a/src/cmd/compile/internal/staticdata/embed.go
+++ b/src/cmd/compile/internal/staticdata/embed.go
@@ -108,13 +108,6 @@ func WriteEmbed(v *ir.Name) {
 	// TODO(mdempsky): User errors should be reported by the frontend.
 
 	commentPos := (*v.Embed)[0].Pos
-	if !types.AllowsGoVersion(types.LocalPkg, 1, 16) {
-		prevPos := base.Pos
-		base.Pos = commentPos
-		base.ErrorfVers("go1.16", "go:embed")
-		base.Pos = prevPos
-		return
-	}
 	if base.Flag.Cfg.Embed.Patterns == nil {
 		base.ErrorfAt(commentPos, "invalid go:embed: build system did not supply embed configuration")
 		return
diff --git a/src/cmd/compile/internal/staticinit/sched.go b/src/cmd/compile/internal/staticinit/sched.go
index 0c97b6de747660541c604beb3c7f4046f8dae10a..9329a469899981f8865212de82e51b7b5aa9a3cb 100644
--- a/src/cmd/compile/internal/staticinit/sched.go
+++ b/src/cmd/compile/internal/staticinit/sched.go
@@ -403,10 +403,10 @@ func (s *Schedule) initplan(n ir.Node) {
 				base.Fatalf("initplan structlit")
 			}
 			a := a.(*ir.StructKeyExpr)
-			if a.Field.IsBlank() {
+			if a.Sym().IsBlank() {
 				continue
 			}
-			s.addvalue(p, a.Offset, a.Value)
+			s.addvalue(p, a.Field.Offset, a.Value)
 		}
 
 	case ir.OMAPLIT:
diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go
index e7b8840b337e679bb11e32ef844c1bf32764412a..c477ddd45d52adc83629294db9126a1cff5e9833 100644
--- a/src/cmd/compile/internal/syntax/parser.go
+++ b/src/cmd/compile/internal/syntax/parser.go
@@ -146,11 +146,13 @@ func (p *parser) updateBase(pos Pos, tline, tcol uint, text string) {
 	// If we have a column (//line filename:line:col form),
 	// an empty filename means to use the previous filename.
 	filename := text[:i-1] // lop off ":line"
+	trimmed := false
 	if filename == "" && ok2 {
 		filename = p.base.Filename()
+		trimmed = p.base.Trimmed()
 	}
 
-	p.base = NewLineBase(pos, filename, line, col)
+	p.base = NewLineBase(pos, filename, trimmed, line, col)
 }
 
 func commentText(s string) string {
@@ -604,7 +606,7 @@ func (p *parser) typeDecl(group *Group) Decl {
 			} else {
 				// x is the array length expression
 				if debug && x == nil {
-					panic("internal error: nil expression")
+					panic("length expression is nil")
 				}
 				d.Type = p.arrayType(pos, x)
 			}
@@ -1049,7 +1051,16 @@ loop:
 			}
 
 			// x[i:...
-			p.want(_Colon)
+			// For better error message, don't simply use p.want(_Colon) here (issue #47704).
+			if !p.got(_Colon) {
+				if p.mode&AllowGenerics == 0 {
+					p.syntaxError("expecting : or ]")
+					p.advance(_Colon, _Rbrack)
+				} else {
+					p.syntaxError("expecting comma, : or ]")
+					p.advance(_Comma, _Colon, _Rbrack)
+				}
+			}
 			p.xnest++
 			t := new(SliceExpr)
 			t.pos = pos
@@ -1100,7 +1111,7 @@ loop:
 					complit_ok = true
 				}
 			case *IndexExpr:
-				if p.xnest >= 0 {
+				if p.xnest >= 0 && !isValue(t) {
 					// x is possibly a composite literal type
 					complit_ok = true
 				}
@@ -1127,6 +1138,21 @@ loop:
 	return x
 }
 
+// isValue reports whether x syntactically must be a value (and not a type) expression.
+func isValue(x Expr) bool {
+	switch x := x.(type) {
+	case *BasicLit, *CompositeLit, *FuncLit, *SliceExpr, *AssertExpr, *TypeSwitchGuard, *CallExpr:
+		return true
+	case *Operation:
+		return x.Op != Mul || x.Y != nil // *T may be a type
+	case *ParenExpr:
+		return isValue(x.X)
+	case *IndexExpr:
+		return isValue(x.X) || isValue(x.Index)
+	}
+	return false
+}
+
 // Element = Expression | LiteralValue .
 func (p *parser) bare_complitexpr() Expr {
 	if trace {
@@ -1443,6 +1469,18 @@ func (p *parser) interfaceType() *InterfaceType {
 				}
 				return false
 			}
+
+		default:
+			if p.mode&AllowGenerics != 0 {
+				pos := p.pos()
+				if t := p.typeOrNil(); t != nil {
+					f := new(Field)
+					f.pos = pos
+					f.Type = t
+					typ.MethodList = append(typ.MethodList, p.embeddedElem(f))
+					return false
+				}
+			}
 		}
 
 		if p.mode&AllowGenerics != 0 {
diff --git a/src/cmd/compile/internal/syntax/pos.go b/src/cmd/compile/internal/syntax/pos.go
index baebcc995c759bbcb4719600e658b0a4920f881a..1494c0989fb11a1258649f6f0e45c39f7e147747 100644
--- a/src/cmd/compile/internal/syntax/pos.go
+++ b/src/cmd/compile/internal/syntax/pos.go
@@ -133,13 +133,19 @@ type PosBase struct {
 	pos       Pos
 	filename  string
 	line, col uint32
+	trimmed   bool // whether -trimpath has been applied
 }
 
 // NewFileBase returns a new PosBase for the given filename.
 // A file PosBase's position is relative to itself, with the
 // position being filename:1:1.
 func NewFileBase(filename string) *PosBase {
-	base := &PosBase{MakePos(nil, linebase, colbase), filename, linebase, colbase}
+	return NewTrimmedFileBase(filename, false)
+}
+
+// NewTrimmedFileBase is like NewFileBase, but allows specifying Trimmed.
+func NewTrimmedFileBase(filename string, trimmed bool) *PosBase {
+	base := &PosBase{MakePos(nil, linebase, colbase), filename, linebase, colbase, trimmed}
 	base.pos.base = base
 	return base
 }
@@ -149,8 +155,8 @@ func NewFileBase(filename string) *PosBase {
 // the comment containing the line directive. For a directive in a line comment,
 // that position is the beginning of the next line (i.e., the newline character
 // belongs to the line comment).
-func NewLineBase(pos Pos, filename string, line, col uint) *PosBase {
-	return &PosBase{pos, filename, sat32(line), sat32(col)}
+func NewLineBase(pos Pos, filename string, trimmed bool, line, col uint) *PosBase {
+	return &PosBase{pos, filename, sat32(line), sat32(col), trimmed}
 }
 
 func (base *PosBase) IsFileBase() bool {
@@ -188,6 +194,13 @@ func (base *PosBase) Col() uint {
 	return uint(base.col)
 }
 
+func (base *PosBase) Trimmed() bool {
+	if base == nil {
+		return false
+	}
+	return base.trimmed
+}
+
 func sat32(x uint) uint32 {
 	if x > PosMax {
 		return PosMax
diff --git a/src/cmd/compile/internal/syntax/positions.go b/src/cmd/compile/internal/syntax/positions.go
index b00f86c67cdab32322449056a2caf9c7e7aa7a50..93596559a02328a3a23296c15ffa2983630a20a1 100644
--- a/src/cmd/compile/internal/syntax/positions.go
+++ b/src/cmd/compile/internal/syntax/positions.go
@@ -12,7 +12,7 @@ func StartPos(n Node) Pos {
 	for m := n; ; {
 		switch n := m.(type) {
 		case nil:
-			panic("internal error: nil")
+			panic("nil node")
 
 		// packages
 		case *File:
@@ -124,7 +124,7 @@ func EndPos(n Node) Pos {
 	for m := n; ; {
 		switch n := m.(type) {
 		case nil:
-			panic("internal error: nil")
+			panic("nil node")
 
 		// packages
 		case *File:
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2 b/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2
index 0d27603a5837a2747922d9c1e52802b840ca8c4e..822d0287e7490ada0681ce74a10de3ab0122c765 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2
@@ -9,10 +9,10 @@ import "math"
 // Numeric is type bound that matches any numeric type.
 // It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		float32 | ~float64 |
+		complex64 | ~complex128
 }
 
 func DotProduct[T Numeric](s1, s2 []T) T {
@@ -42,14 +42,14 @@ func AbsDifference[T NumericAbs[T]](a, b T) T {
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		float32 | ~float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // OrderedAbs is a helper type that defines an Abs method for
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2 b/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2
index e5cfba061254165a62c45bc04a2ea055033785d1..42efb4252755c2400bf9b334f2b048b70fa3017f 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2
@@ -46,12 +46,12 @@ type _ struct{ T[int] }
 // interfaces
 type _ interface{
 	m()
-	type int
+	~int
 }
 
 type _ interface{
-	type int, float, string
-	type complex128
+	~int | ~float | ~string
+	~complex128
 	underlying(underlying underlying) underlying
 }
 
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2 b/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2
index 6e2104a5150da8fead95d91dc7cdad447fc59f8d..f3deb703b6770077251c213c517e252c84b98161 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2
@@ -175,12 +175,12 @@ type _ interface {
 // Interface type lists can contain any type, incl. *Named types.
 // Verify that we use the underlying type to compute the operational type.
 type MyInt int
-func add1[T interface{type MyInt}](x T) T {
+func add1[T interface{ ~MyInt }](x T) T {
 	return x + 1
 }
 
 type MyString string
-func double[T interface{type MyInt, MyString}](x T) T {
+func double[T interface{ ~MyInt | ~MyString }](x T) T {
 	return x + x
 }
 
@@ -189,15 +189,15 @@ func double[T interface{type MyInt, MyString}](x T) T {
 // type lists.
 
 type E0 interface {
-	type int, bool, string
+	~int | ~bool | ~string
 }
 
 type E1 interface {
-	type int, float64, string
+	~int | ~float64 | ~string
 }
 
 type E2 interface {
-	type float64
+	~float64
 }
 
 type I0 interface {
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2 b/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2
index f78037f0f5d033c63236e8246644b2b401509713..111f7c10042389ce70c659529f95cc279b06edf3 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2
@@ -48,22 +48,22 @@ func swapswap[A, B any](a A, b B) (A, B) {
 
 type F[A, B any] func(A, B) (B, A)
 
-func min[T interface{ type int }](x, y T) T {
+func min[T interface{ ~int }](x, y T) T {
         if x < y {
                 return x
         }
         return y
 }
 
-func _[T interface{type int, float32}](x, y T) bool { return x < y }
+func _[T interface{ ~int | ~float32 }](x, y T) bool { return x < y }
 func _[T any](x, y T) bool { return x /* ERROR cannot compare */ < y }
-func _[T interface{type int, float32, bool}](x, y T) bool { return x /* ERROR cannot compare */ < y }
+func _[T interface{ ~int | ~float32 | ~bool }](x, y T) bool { return x /* ERROR cannot compare */ < y }
 
 func _[T C1[T]](x, y T) bool { return x /* ERROR cannot compare */ < y }
 func _[T C2[T]](x, y T) bool { return x < y }
 
 type C1[T any] interface{}
-type C2[T any] interface{ type int, float32 }
+type C2[T any] interface{ ~int | ~float32 }
 
 func new[T any]() *T {
         var x T
@@ -91,40 +91,40 @@ var _ = f3[int, rune, bool](1, struct{x rune}{}, nil)
 // indexing
 
 func _[T any] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type [10]int, *[20]int, map[string]int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type string, []byte }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int, [1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string, []rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[10]int | ~*[20]int | ~map[string]int }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~string | ~[]byte }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int | ~[1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string | ~[]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
 
 // slicing
 // TODO(gri) implement this
 
-func _[T interface{ type string }] (x T, i, j, k int) { _ = x /* ERROR invalid operation */ [i:j:k] }
+func _[T interface{ ~string }] (x T, i, j, k int) { _ = x /* ERROR invalid operation */ [i:j:k] }
 
 // len/cap built-ins
 
 func _[T any](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = len(x) }
-func _[T interface{ type [10]int }](x T) { _ = len(x) }
-func _[T interface{ type []byte }](x T) { _ = len(x) }
-func _[T interface{ type map[int]int }](x T) { _ = len(x) }
-func _[T interface{ type chan int }](x T) { _ = len(x) }
-func _[T interface{ type string, []byte, chan int }](x T) { _ = len(x) }
+func _[T interface{ ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = len(x) }
+func _[T interface{ ~[10]int }](x T) { _ = len(x) }
+func _[T interface{ ~[]byte }](x T) { _ = len(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = len(x) }
+func _[T interface{ ~chan int }](x T) { _ = len(x) }
+func _[T interface{ ~string | ~[]byte | ~chan int }](x T) { _ = len(x) }
 
 func _[T any](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type [10]int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte }](x T) { _ = cap(x) }
-func _[T interface{ type map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type chan int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte, chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~[10]int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte }](x T) { _ = cap(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte | ~chan int }](x T) { _ = cap(x) }
 
 // range iteration
 
@@ -132,7 +132,7 @@ func _[T interface{}](x T) {
         for range x /* ERROR cannot range */ {}
 }
 
-func _[T interface{ type string, []string }](x T) {
+func _[T interface{ ~string | ~[]string }](x T) {
         for range x {}
         for i := range x { _ = i }
         for i, _ := range x { _ = i }
@@ -144,23 +144,23 @@ func _[T interface{ type string, []string }](x T) {
 }
 
 
-func _[T interface{ type string, []rune, map[int]rune }](x T) {
+func _[T interface{ ~string | ~[]rune | ~map[int]rune }](x T) {
         for _, e := range x { _ = e }
         for i, e := range x { _ = i; _ = e }
 }
 
-func _[T interface{ type string, []rune, map[string]rune }](x T) {
+func _[T interface{ ~string | ~[]rune | ~map[string]rune }](x T) {
         for _, e := range x { _ = e }
         for i, e := range x /* ERROR must have the same key type */ { _ = e }
 }
 
-func _[T interface{ type string, chan int }](x T) {
+func _[T interface{ ~string | ~chan int }](x T) {
         for range x {}
         for i := range x { _ = i }
         for i, _ := range x { _ = i } // TODO(gri) should get an error here: channels only return one value
 }
 
-func _[T interface{ type string, chan<-int }](x T) {
+func _[T interface{ ~string | ~chan<-int }](x T) {
         for i := range x /* ERROR send-only channel */ { _ = i }
 }
 
@@ -388,7 +388,7 @@ func _[T any](x T) {
 	}
 }
 
-func _[T interface{type int}](x T) {
+func _[T interface{ ~int }](x T) {
 	_ = x /* ERROR not an interface */ .(int)
 	switch x /* ERROR not an interface */ .(type) {
 	}
diff --git a/src/cmd/compile/internal/syntax/testdata/interface.go2 b/src/cmd/compile/internal/syntax/testdata/interface.go2
index a817327a43f4c289e55b541880974981c1b54278..b399d7514889f39c5e8889088dd2c4ada0d2c857 100644
--- a/src/cmd/compile/internal/syntax/testdata/interface.go2
+++ b/src/cmd/compile/internal/syntax/testdata/interface.go2
@@ -25,7 +25,6 @@ type _ interface {
 	~int | ~string
 }
 
-
 type _ interface {
 	m()
 	~int
@@ -34,3 +33,48 @@ type _ interface {
 	~int | ~string
 	type bool, int, float64
 }
+
+type _ interface {
+	int
+	[]byte
+	[10]int
+	struct{}
+	*int
+	func()
+	interface{}
+	map[string]int
+	chan T
+	chan<- T
+	<-chan T
+	T[int]
+}
+
+type _ interface {
+	int | string
+	[]byte | string
+	[10]int | string
+	struct{} | string
+	*int | string
+	func() | string
+	interface{} | string
+	map[string]int | string
+	chan T | string
+	chan<- T | string
+	<-chan T | string
+	T[int] | string
+}
+
+type _ interface {
+	~int | string
+	~[]byte | string
+	~[10]int | string
+	~struct{} | string
+	~*int | string
+	~func() | string
+	~interface{} | string
+	~map[string]int | string
+	~chan T | string
+	~chan<- T | string
+	~<-chan T | string
+	~T[int] | string
+}
diff --git a/src/cmd/compile/internal/syntax/testdata/issue46558.src b/src/cmd/compile/internal/syntax/testdata/issue46558.src
new file mode 100644
index 0000000000000000000000000000000000000000..a22b6008258464503dd41b037a3094dccec10ebb
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue46558.src
@@ -0,0 +1,14 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func F(s string) {
+	switch s[0] {
+	case 'a':
+		case s[2] { // ERROR unexpected {
+		case 'b':
+		}
+	}
+} // ERROR non-declaration statement
diff --git a/src/cmd/compile/internal/syntax/testdata/issue47704.go2 b/src/cmd/compile/internal/syntax/testdata/issue47704.go2
new file mode 100644
index 0000000000000000000000000000000000000000..4e65857f3b191c8f94523f39ed8bc999d421258d
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue47704.go2
@@ -0,0 +1,18 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// error messages for parser in generic mode
+func _() {
+	_ = m[] // ERROR expecting operand
+	_ = m[x,]
+	_ = m[x /* ERROR unexpected a */ a b c d]
+}
+
+// test case from the issue
+func f(m map[int]int) int {
+	return m[0 // ERROR expecting comma, \: or \]
+		]
+}
diff --git a/src/cmd/compile/internal/syntax/testdata/issue47704.src b/src/cmd/compile/internal/syntax/testdata/issue47704.src
new file mode 100644
index 0000000000000000000000000000000000000000..0156af7d8d1b040963c3a707a17f44a636c77f01
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue47704.src
@@ -0,0 +1,18 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// error messages for parser in non-generic mode
+func _() {
+	_ = m[]   // ERROR expecting operand
+	_ = m[x,] // ERROR unexpected comma, expecting \: or \]
+	_ = m[x /* ERROR unexpected a */ a b c d]
+}
+
+// test case from the issue
+func f(m map[int]int) int {
+	return m[0 // ERROR expecting \: or \]
+		]
+}
diff --git a/src/cmd/compile/internal/syntax/walk.go b/src/cmd/compile/internal/syntax/walk.go
index c26e97a0d8f88771986be07a4a300ff98b993f4e..b02584420488442a3e284d5b611fa025001bd59e 100644
--- a/src/cmd/compile/internal/syntax/walk.go
+++ b/src/cmd/compile/internal/syntax/walk.go
@@ -8,31 +8,73 @@ package syntax
 
 import "fmt"
 
-// Walk traverses a syntax in pre-order: It starts by calling f(root);
-// root must not be nil. If f returns false (== "continue"), Walk calls
+// Inspect traverses an AST in pre-order: It starts by calling
+// f(node); node must not be nil. If f returns true, Inspect invokes f
+// recursively for each of the non-nil children of node, followed by a
+// call of f(nil).
+//
+// See Walk for caveats about shared nodes.
+func Inspect(root Node, f func(Node) bool) {
+	Walk(root, inspector(f))
+}
+
+type inspector func(Node) bool
+
+func (v inspector) Visit(node Node) Visitor {
+	if v(node) {
+		return v
+	}
+	return nil
+}
+
+// Crawl traverses a syntax in pre-order: It starts by calling f(root);
+// root must not be nil. If f returns false (== "continue"), Crawl calls
 // f recursively for each of the non-nil children of that node; if f
-// returns true (== "stop"), Walk does not traverse the respective node's
+// returns true (== "stop"), Crawl does not traverse the respective node's
 // children.
+//
+// See Walk for caveats about shared nodes.
+//
+// Deprecated: Use Inspect instead.
+func Crawl(root Node, f func(Node) bool) {
+	Inspect(root, func(node Node) bool {
+		return node != nil && !f(node)
+	})
+}
+
+// Walk traverses an AST in pre-order: It starts by calling
+// v.Visit(node); node must not be nil. If the visitor w returned by
+// v.Visit(node) is not nil, Walk is invoked recursively with visitor
+// w for each of the non-nil children of node, followed by a call of
+// w.Visit(nil).
+//
 // Some nodes may be shared among multiple parent nodes (e.g., types in
 // field lists such as type T in "a, b, c T"). Such shared nodes are
 // walked multiple times.
 // TODO(gri) Revisit this design. It may make sense to walk those nodes
 //           only once. A place where this matters is types2.TestResolveIdents.
-func Walk(root Node, f func(Node) bool) {
-	w := walker{f}
-	w.node(root)
+func Walk(root Node, v Visitor) {
+	walker{v}.node(root)
+}
+
+// A Visitor's Visit method is invoked for each node encountered by Walk.
+// If the result visitor w is not nil, Walk visits each of the children
+// of node with the visitor w, followed by a call of w.Visit(nil).
+type Visitor interface {
+	Visit(node Node) (w Visitor)
 }
 
 type walker struct {
-	f func(Node) bool
+	v Visitor
 }
 
-func (w *walker) node(n Node) {
+func (w walker) node(n Node) {
 	if n == nil {
-		panic("invalid syntax tree: nil node")
+		panic("nil node")
 	}
 
-	if w.f(n) {
+	w.v = w.v.Visit(n)
+	if w.v == nil {
 		return
 	}
 
@@ -285,33 +327,35 @@ func (w *walker) node(n Node) {
 	default:
 		panic(fmt.Sprintf("internal error: unknown node type %T", n))
 	}
+
+	w.v.Visit(nil)
 }
 
-func (w *walker) declList(list []Decl) {
+func (w walker) declList(list []Decl) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) exprList(list []Expr) {
+func (w walker) exprList(list []Expr) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) stmtList(list []Stmt) {
+func (w walker) stmtList(list []Stmt) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) nameList(list []*Name) {
+func (w walker) nameList(list []*Name) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) fieldList(list []*Field) {
+func (w walker) fieldList(list []*Field) {
 	for _, n := range list {
 		w.node(n)
 	}
diff --git a/src/cmd/compile/internal/test/abiutils_test.go b/src/cmd/compile/internal/test/abiutils_test.go
index b752c486126dc37acfb08bef3ee8205f5ab032e2..839546bcb8a726f46b40d04b937656b6e131dd44 100644
--- a/src/cmd/compile/internal/test/abiutils_test.go
+++ b/src/cmd/compile/internal/test/abiutils_test.go
@@ -33,6 +33,8 @@ func TestMain(m *testing.M) {
 	base.Ctxt.DiagFunc = base.Errorf
 	base.Ctxt.DiagFlush = base.FlushErrors
 	base.Ctxt.Bso = bufio.NewWriter(os.Stdout)
+	types.LocalPkg = types.NewPkg("", "local")
+	types.LocalPkg.Prefix = `""`
 	types.PtrSize = ssagen.Arch.LinkArch.PtrSize
 	types.RegSize = ssagen.Arch.LinkArch.RegSize
 	typecheck.InitUniverse()
@@ -309,8 +311,8 @@ func TestABIUtilsInterfaces(t *testing.T) {
 	ei := types.Types[types.TINTER] // interface{}
 	pei := types.NewPtr(ei)         // *interface{}
 	fldt := mkFuncType(types.FakeRecvType(), []*types.Type{},
-		[]*types.Type{types.UntypedString})
-	field := types.NewField(src.NoXPos, nil, fldt)
+		[]*types.Type{types.Types[types.TSTRING]})
+	field := types.NewField(src.NoXPos, typecheck.Lookup("F"), fldt)
 	nei := types.NewInterface(types.LocalPkg, []*types.Field{field})
 	i16 := types.Types[types.TINT16]
 	tb := types.Types[types.TBOOL]
@@ -322,12 +324,12 @@ func TestABIUtilsInterfaces(t *testing.T) {
         IN 0: R{ I0 I1 I2 } spilloffset: 0 typ: struct { int16; int16; bool }
         IN 1: R{ I3 I4 } spilloffset: 8 typ: interface {}
         IN 2: R{ I5 I6 } spilloffset: 24 typ: interface {}
-        IN 3: R{ I7 I8 } spilloffset: 40 typ: interface { () untyped string }
+        IN 3: R{ I7 I8 } spilloffset: 40 typ: interface { F() string }
         IN 4: R{ } offset: 0 typ: *interface {}
-        IN 5: R{ } offset: 8 typ: interface { () untyped string }
+        IN 5: R{ } offset: 8 typ: interface { F() string }
         IN 6: R{ } offset: 24 typ: int16
         OUT 0: R{ I0 I1 } spilloffset: -1 typ: interface {}
-        OUT 1: R{ I2 I3 } spilloffset: -1 typ: interface { () untyped string }
+        OUT 1: R{ I2 I3 } spilloffset: -1 typ: interface { F() string }
         OUT 2: R{ I4 } spilloffset: -1 typ: *interface {}
         offsetToSpillArea: 32 spillAreaSize: 56
 `)
diff --git a/src/cmd/compile/internal/test/inl_test.go b/src/cmd/compile/internal/test/inl_test.go
index 6f100033cf5b8b9666c458ce82b894db12d2a914..bbdbe0c37ca6269d1e0efe117fddcf9a9cda922b 100644
--- a/src/cmd/compile/internal/test/inl_test.go
+++ b/src/cmd/compile/internal/test/inl_test.go
@@ -42,13 +42,10 @@ func TestIntendedInlining(t *testing.T) {
 			"bucketMask",
 			"bucketShift",
 			"chanbuf",
-			"deferArgs",
-			"deferclass",
 			"evacuated",
 			"fastlog2",
 			"fastrand",
 			"float64bits",
-			"funcPC",
 			"getArgInfoFast",
 			"getm",
 			"getMCache",
@@ -65,7 +62,6 @@ func TestIntendedInlining(t *testing.T) {
 			"subtract1",
 			"subtractb",
 			"tophash",
-			"totaldefersize",
 			"(*bmap).keys",
 			"(*bmap).overflow",
 			"(*waitq).enqueue",
diff --git a/src/cmd/compile/internal/typecheck/bexport.go b/src/cmd/compile/internal/typecheck/bexport.go
index 4a84bb13fa48ebfc63eb1dd36a5b7206af21a5c5..cc7f91f9372af4665131f801bf459cde47dd0aac 100644
--- a/src/cmd/compile/internal/typecheck/bexport.go
+++ b/src/cmd/compile/internal/typecheck/bexport.go
@@ -96,6 +96,9 @@ func predeclared() []*types.Type {
 
 			// any type, for builtin export data
 			types.Types[types.TANY],
+
+			// comparable
+			types.ComparableType,
 		}
 	}
 	return predecl
diff --git a/src/cmd/compile/internal/typecheck/builtin.go b/src/cmd/compile/internal/typecheck/builtin.go
index 833b17b4148ed5ab022e0b859084573227151ed3..3f177d91732c03a601794338961d16d59b34945c 100644
--- a/src/cmd/compile/internal/typecheck/builtin.go
+++ b/src/cmd/compile/internal/typecheck/builtin.go
@@ -71,137 +71,135 @@ var runtimeDecls = [...]struct {
 	{"slicecopy", funcTag, 54},
 	{"decoderune", funcTag, 55},
 	{"countrunes", funcTag, 56},
-	{"convI2I", funcTag, 57},
-	{"convT16", funcTag, 59},
-	{"convT32", funcTag, 61},
-	{"convT64", funcTag, 62},
-	{"convTstring", funcTag, 63},
-	{"convTslice", funcTag, 66},
-	{"convT2E", funcTag, 67},
-	{"convT2Enoptr", funcTag, 67},
-	{"convT2I", funcTag, 67},
-	{"convT2Inoptr", funcTag, 67},
-	{"assertE2I", funcTag, 68},
-	{"assertE2I2", funcTag, 57},
-	{"assertI2I", funcTag, 68},
-	{"assertI2I2", funcTag, 57},
-	{"panicdottypeE", funcTag, 69},
-	{"panicdottypeI", funcTag, 69},
-	{"panicnildottype", funcTag, 70},
-	{"ifaceeq", funcTag, 72},
-	{"efaceeq", funcTag, 72},
-	{"fastrand", funcTag, 73},
-	{"makemap64", funcTag, 75},
-	{"makemap", funcTag, 76},
-	{"makemap_small", funcTag, 77},
-	{"mapaccess1", funcTag, 78},
-	{"mapaccess1_fast32", funcTag, 79},
-	{"mapaccess1_fast64", funcTag, 80},
-	{"mapaccess1_faststr", funcTag, 81},
-	{"mapaccess1_fat", funcTag, 82},
-	{"mapaccess2", funcTag, 83},
-	{"mapaccess2_fast32", funcTag, 84},
-	{"mapaccess2_fast64", funcTag, 85},
-	{"mapaccess2_faststr", funcTag, 86},
-	{"mapaccess2_fat", funcTag, 87},
-	{"mapassign", funcTag, 78},
-	{"mapassign_fast32", funcTag, 79},
-	{"mapassign_fast32ptr", funcTag, 88},
-	{"mapassign_fast64", funcTag, 80},
-	{"mapassign_fast64ptr", funcTag, 88},
-	{"mapassign_faststr", funcTag, 81},
-	{"mapiterinit", funcTag, 89},
-	{"mapdelete", funcTag, 89},
-	{"mapdelete_fast32", funcTag, 90},
-	{"mapdelete_fast64", funcTag, 91},
-	{"mapdelete_faststr", funcTag, 92},
-	{"mapiternext", funcTag, 93},
-	{"mapclear", funcTag, 94},
-	{"makechan64", funcTag, 96},
-	{"makechan", funcTag, 97},
-	{"chanrecv1", funcTag, 99},
-	{"chanrecv2", funcTag, 100},
-	{"chansend1", funcTag, 102},
+	{"convI2I", funcTag, 58},
+	{"convT", funcTag, 59},
+	{"convTnoptr", funcTag, 59},
+	{"convT16", funcTag, 61},
+	{"convT32", funcTag, 63},
+	{"convT64", funcTag, 64},
+	{"convTstring", funcTag, 65},
+	{"convTslice", funcTag, 68},
+	{"assertE2I", funcTag, 69},
+	{"assertE2I2", funcTag, 70},
+	{"assertI2I", funcTag, 69},
+	{"assertI2I2", funcTag, 70},
+	{"panicdottypeE", funcTag, 71},
+	{"panicdottypeI", funcTag, 71},
+	{"panicnildottype", funcTag, 72},
+	{"ifaceeq", funcTag, 73},
+	{"efaceeq", funcTag, 73},
+	{"fastrand", funcTag, 74},
+	{"makemap64", funcTag, 76},
+	{"makemap", funcTag, 77},
+	{"makemap_small", funcTag, 78},
+	{"mapaccess1", funcTag, 79},
+	{"mapaccess1_fast32", funcTag, 80},
+	{"mapaccess1_fast64", funcTag, 81},
+	{"mapaccess1_faststr", funcTag, 82},
+	{"mapaccess1_fat", funcTag, 83},
+	{"mapaccess2", funcTag, 84},
+	{"mapaccess2_fast32", funcTag, 85},
+	{"mapaccess2_fast64", funcTag, 86},
+	{"mapaccess2_faststr", funcTag, 87},
+	{"mapaccess2_fat", funcTag, 88},
+	{"mapassign", funcTag, 79},
+	{"mapassign_fast32", funcTag, 80},
+	{"mapassign_fast32ptr", funcTag, 89},
+	{"mapassign_fast64", funcTag, 81},
+	{"mapassign_fast64ptr", funcTag, 89},
+	{"mapassign_faststr", funcTag, 82},
+	{"mapiterinit", funcTag, 90},
+	{"mapdelete", funcTag, 90},
+	{"mapdelete_fast32", funcTag, 91},
+	{"mapdelete_fast64", funcTag, 92},
+	{"mapdelete_faststr", funcTag, 93},
+	{"mapiternext", funcTag, 94},
+	{"mapclear", funcTag, 95},
+	{"makechan64", funcTag, 97},
+	{"makechan", funcTag, 98},
+	{"chanrecv1", funcTag, 100},
+	{"chanrecv2", funcTag, 101},
+	{"chansend1", funcTag, 103},
 	{"closechan", funcTag, 30},
-	{"writeBarrier", varTag, 104},
-	{"typedmemmove", funcTag, 105},
-	{"typedmemclr", funcTag, 106},
-	{"typedslicecopy", funcTag, 107},
-	{"selectnbsend", funcTag, 108},
-	{"selectnbrecv", funcTag, 109},
-	{"selectsetpc", funcTag, 110},
-	{"selectgo", funcTag, 111},
+	{"writeBarrier", varTag, 105},
+	{"typedmemmove", funcTag, 106},
+	{"typedmemclr", funcTag, 107},
+	{"typedslicecopy", funcTag, 108},
+	{"selectnbsend", funcTag, 109},
+	{"selectnbrecv", funcTag, 110},
+	{"selectsetpc", funcTag, 111},
+	{"selectgo", funcTag, 112},
 	{"block", funcTag, 9},
-	{"makeslice", funcTag, 112},
-	{"makeslice64", funcTag, 113},
-	{"makeslicecopy", funcTag, 114},
-	{"growslice", funcTag, 116},
-	{"unsafeslice", funcTag, 117},
-	{"unsafeslice64", funcTag, 118},
-	{"unsafeslicecheckptr", funcTag, 118},
-	{"memmove", funcTag, 119},
-	{"memclrNoHeapPointers", funcTag, 120},
-	{"memclrHasPointers", funcTag, 120},
-	{"memequal", funcTag, 121},
-	{"memequal0", funcTag, 122},
-	{"memequal8", funcTag, 122},
-	{"memequal16", funcTag, 122},
-	{"memequal32", funcTag, 122},
-	{"memequal64", funcTag, 122},
-	{"memequal128", funcTag, 122},
-	{"f32equal", funcTag, 123},
-	{"f64equal", funcTag, 123},
-	{"c64equal", funcTag, 123},
-	{"c128equal", funcTag, 123},
-	{"strequal", funcTag, 123},
-	{"interequal", funcTag, 123},
-	{"nilinterequal", funcTag, 123},
-	{"memhash", funcTag, 124},
-	{"memhash0", funcTag, 125},
-	{"memhash8", funcTag, 125},
-	{"memhash16", funcTag, 125},
-	{"memhash32", funcTag, 125},
-	{"memhash64", funcTag, 125},
-	{"memhash128", funcTag, 125},
-	{"f32hash", funcTag, 125},
-	{"f64hash", funcTag, 125},
-	{"c64hash", funcTag, 125},
-	{"c128hash", funcTag, 125},
-	{"strhash", funcTag, 125},
-	{"interhash", funcTag, 125},
-	{"nilinterhash", funcTag, 125},
-	{"int64div", funcTag, 126},
-	{"uint64div", funcTag, 127},
-	{"int64mod", funcTag, 126},
-	{"uint64mod", funcTag, 127},
-	{"float64toint64", funcTag, 128},
-	{"float64touint64", funcTag, 129},
-	{"float64touint32", funcTag, 130},
-	{"int64tofloat64", funcTag, 131},
-	{"uint64tofloat64", funcTag, 132},
-	{"uint32tofloat64", funcTag, 133},
-	{"complex128div", funcTag, 134},
-	{"getcallerpc", funcTag, 135},
-	{"getcallersp", funcTag, 135},
+	{"makeslice", funcTag, 113},
+	{"makeslice64", funcTag, 114},
+	{"makeslicecopy", funcTag, 115},
+	{"growslice", funcTag, 117},
+	{"unsafeslice", funcTag, 118},
+	{"unsafeslice64", funcTag, 119},
+	{"unsafeslicecheckptr", funcTag, 119},
+	{"memmove", funcTag, 120},
+	{"memclrNoHeapPointers", funcTag, 121},
+	{"memclrHasPointers", funcTag, 121},
+	{"memequal", funcTag, 122},
+	{"memequal0", funcTag, 123},
+	{"memequal8", funcTag, 123},
+	{"memequal16", funcTag, 123},
+	{"memequal32", funcTag, 123},
+	{"memequal64", funcTag, 123},
+	{"memequal128", funcTag, 123},
+	{"f32equal", funcTag, 124},
+	{"f64equal", funcTag, 124},
+	{"c64equal", funcTag, 124},
+	{"c128equal", funcTag, 124},
+	{"strequal", funcTag, 124},
+	{"interequal", funcTag, 124},
+	{"nilinterequal", funcTag, 124},
+	{"memhash", funcTag, 125},
+	{"memhash0", funcTag, 126},
+	{"memhash8", funcTag, 126},
+	{"memhash16", funcTag, 126},
+	{"memhash32", funcTag, 126},
+	{"memhash64", funcTag, 126},
+	{"memhash128", funcTag, 126},
+	{"f32hash", funcTag, 126},
+	{"f64hash", funcTag, 126},
+	{"c64hash", funcTag, 126},
+	{"c128hash", funcTag, 126},
+	{"strhash", funcTag, 126},
+	{"interhash", funcTag, 126},
+	{"nilinterhash", funcTag, 126},
+	{"int64div", funcTag, 127},
+	{"uint64div", funcTag, 128},
+	{"int64mod", funcTag, 127},
+	{"uint64mod", funcTag, 128},
+	{"float64toint64", funcTag, 129},
+	{"float64touint64", funcTag, 130},
+	{"float64touint32", funcTag, 131},
+	{"int64tofloat64", funcTag, 132},
+	{"uint64tofloat64", funcTag, 133},
+	{"uint32tofloat64", funcTag, 134},
+	{"complex128div", funcTag, 135},
+	{"getcallerpc", funcTag, 136},
+	{"getcallersp", funcTag, 136},
 	{"racefuncenter", funcTag, 31},
 	{"racefuncexit", funcTag, 9},
 	{"raceread", funcTag, 31},
 	{"racewrite", funcTag, 31},
-	{"racereadrange", funcTag, 136},
-	{"racewriterange", funcTag, 136},
-	{"msanread", funcTag, 136},
-	{"msanwrite", funcTag, 136},
-	{"msanmove", funcTag, 137},
-	{"checkptrAlignment", funcTag, 138},
-	{"checkptrArithmetic", funcTag, 140},
-	{"libfuzzerTraceCmp1", funcTag, 141},
-	{"libfuzzerTraceCmp2", funcTag, 142},
-	{"libfuzzerTraceCmp4", funcTag, 143},
-	{"libfuzzerTraceCmp8", funcTag, 144},
-	{"libfuzzerTraceConstCmp1", funcTag, 141},
-	{"libfuzzerTraceConstCmp2", funcTag, 142},
-	{"libfuzzerTraceConstCmp4", funcTag, 143},
-	{"libfuzzerTraceConstCmp8", funcTag, 144},
+	{"racereadrange", funcTag, 137},
+	{"racewriterange", funcTag, 137},
+	{"msanread", funcTag, 137},
+	{"msanwrite", funcTag, 137},
+	{"msanmove", funcTag, 138},
+	{"checkptrAlignment", funcTag, 139},
+	{"checkptrArithmetic", funcTag, 141},
+	{"libfuzzerTraceCmp1", funcTag, 142},
+	{"libfuzzerTraceCmp2", funcTag, 143},
+	{"libfuzzerTraceCmp4", funcTag, 144},
+	{"libfuzzerTraceCmp8", funcTag, 145},
+	{"libfuzzerTraceConstCmp1", funcTag, 142},
+	{"libfuzzerTraceConstCmp2", funcTag, 143},
+	{"libfuzzerTraceConstCmp4", funcTag, 144},
+	{"libfuzzerTraceConstCmp8", funcTag, 145},
 	{"x86HasPOPCNT", varTag, 6},
 	{"x86HasSSE41", varTag, 6},
 	{"x86HasFMA", varTag, 6},
@@ -224,7 +222,7 @@ func params(tlist ...*types.Type) []*types.Field {
 }
 
 func runtimeTypes() []*types.Type {
-	var typs [145]*types.Type
+	var typs [146]*types.Type
 	typs[0] = types.ByteType
 	typs[1] = types.NewPtr(typs[0])
 	typs[2] = types.Types[types.TANY]
@@ -282,93 +280,94 @@ func runtimeTypes() []*types.Type {
 	typs[54] = newSig(params(typs[3], typs[15], typs[3], typs[15], typs[5]), params(typs[15]))
 	typs[55] = newSig(params(typs[28], typs[15]), params(typs[46], typs[15]))
 	typs[56] = newSig(params(typs[28]), params(typs[15]))
-	typs[57] = newSig(params(typs[1], typs[2]), params(typs[2]))
-	typs[58] = types.Types[types.TUINT16]
-	typs[59] = newSig(params(typs[58]), params(typs[7]))
-	typs[60] = types.Types[types.TUINT32]
+	typs[57] = types.NewPtr(typs[5])
+	typs[58] = newSig(params(typs[1], typs[57]), params(typs[57]))
+	typs[59] = newSig(params(typs[1], typs[3]), params(typs[7]))
+	typs[60] = types.Types[types.TUINT16]
 	typs[61] = newSig(params(typs[60]), params(typs[7]))
-	typs[62] = newSig(params(typs[24]), params(typs[7]))
-	typs[63] = newSig(params(typs[28]), params(typs[7]))
-	typs[64] = types.Types[types.TUINT8]
-	typs[65] = types.NewSlice(typs[64])
-	typs[66] = newSig(params(typs[65]), params(typs[7]))
-	typs[67] = newSig(params(typs[1], typs[3]), params(typs[2]))
-	typs[68] = newSig(params(typs[1], typs[1]), params(typs[1]))
-	typs[69] = newSig(params(typs[1], typs[1], typs[1]), nil)
-	typs[70] = newSig(params(typs[1]), nil)
-	typs[71] = types.NewPtr(typs[5])
-	typs[72] = newSig(params(typs[71], typs[7], typs[7]), params(typs[6]))
-	typs[73] = newSig(nil, params(typs[60]))
-	typs[74] = types.NewMap(typs[2], typs[2])
-	typs[75] = newSig(params(typs[1], typs[22], typs[3]), params(typs[74]))
-	typs[76] = newSig(params(typs[1], typs[15], typs[3]), params(typs[74]))
-	typs[77] = newSig(nil, params(typs[74]))
-	typs[78] = newSig(params(typs[1], typs[74], typs[3]), params(typs[3]))
-	typs[79] = newSig(params(typs[1], typs[74], typs[60]), params(typs[3]))
-	typs[80] = newSig(params(typs[1], typs[74], typs[24]), params(typs[3]))
-	typs[81] = newSig(params(typs[1], typs[74], typs[28]), params(typs[3]))
-	typs[82] = newSig(params(typs[1], typs[74], typs[3], typs[1]), params(typs[3]))
-	typs[83] = newSig(params(typs[1], typs[74], typs[3]), params(typs[3], typs[6]))
-	typs[84] = newSig(params(typs[1], typs[74], typs[60]), params(typs[3], typs[6]))
-	typs[85] = newSig(params(typs[1], typs[74], typs[24]), params(typs[3], typs[6]))
-	typs[86] = newSig(params(typs[1], typs[74], typs[28]), params(typs[3], typs[6]))
-	typs[87] = newSig(params(typs[1], typs[74], typs[3], typs[1]), params(typs[3], typs[6]))
-	typs[88] = newSig(params(typs[1], typs[74], typs[7]), params(typs[3]))
-	typs[89] = newSig(params(typs[1], typs[74], typs[3]), nil)
-	typs[90] = newSig(params(typs[1], typs[74], typs[60]), nil)
-	typs[91] = newSig(params(typs[1], typs[74], typs[24]), nil)
-	typs[92] = newSig(params(typs[1], typs[74], typs[28]), nil)
-	typs[93] = newSig(params(typs[3]), nil)
-	typs[94] = newSig(params(typs[1], typs[74]), nil)
-	typs[95] = types.NewChan(typs[2], types.Cboth)
-	typs[96] = newSig(params(typs[1], typs[22]), params(typs[95]))
-	typs[97] = newSig(params(typs[1], typs[15]), params(typs[95]))
-	typs[98] = types.NewChan(typs[2], types.Crecv)
-	typs[99] = newSig(params(typs[98], typs[3]), nil)
-	typs[100] = newSig(params(typs[98], typs[3]), params(typs[6]))
-	typs[101] = types.NewChan(typs[2], types.Csend)
-	typs[102] = newSig(params(typs[101], typs[3]), nil)
-	typs[103] = types.NewArray(typs[0], 3)
-	typs[104] = types.NewStruct(types.NoPkg, []*types.Field{types.NewField(src.NoXPos, Lookup("enabled"), typs[6]), types.NewField(src.NoXPos, Lookup("pad"), typs[103]), types.NewField(src.NoXPos, Lookup("needed"), typs[6]), types.NewField(src.NoXPos, Lookup("cgo"), typs[6]), types.NewField(src.NoXPos, Lookup("alignme"), typs[24])})
-	typs[105] = newSig(params(typs[1], typs[3], typs[3]), nil)
-	typs[106] = newSig(params(typs[1], typs[3]), nil)
-	typs[107] = newSig(params(typs[1], typs[3], typs[15], typs[3], typs[15]), params(typs[15]))
-	typs[108] = newSig(params(typs[101], typs[3]), params(typs[6]))
-	typs[109] = newSig(params(typs[3], typs[98]), params(typs[6], typs[6]))
-	typs[110] = newSig(params(typs[71]), nil)
-	typs[111] = newSig(params(typs[1], typs[1], typs[71], typs[15], typs[15], typs[6]), params(typs[15], typs[6]))
-	typs[112] = newSig(params(typs[1], typs[15], typs[15]), params(typs[7]))
-	typs[113] = newSig(params(typs[1], typs[22], typs[22]), params(typs[7]))
-	typs[114] = newSig(params(typs[1], typs[15], typs[15], typs[7]), params(typs[7]))
-	typs[115] = types.NewSlice(typs[2])
-	typs[116] = newSig(params(typs[1], typs[115], typs[15]), params(typs[115]))
-	typs[117] = newSig(params(typs[1], typs[7], typs[15]), nil)
-	typs[118] = newSig(params(typs[1], typs[7], typs[22]), nil)
-	typs[119] = newSig(params(typs[3], typs[3], typs[5]), nil)
-	typs[120] = newSig(params(typs[7], typs[5]), nil)
-	typs[121] = newSig(params(typs[3], typs[3], typs[5]), params(typs[6]))
-	typs[122] = newSig(params(typs[3], typs[3]), params(typs[6]))
-	typs[123] = newSig(params(typs[7], typs[7]), params(typs[6]))
-	typs[124] = newSig(params(typs[7], typs[5], typs[5]), params(typs[5]))
-	typs[125] = newSig(params(typs[7], typs[5]), params(typs[5]))
-	typs[126] = newSig(params(typs[22], typs[22]), params(typs[22]))
-	typs[127] = newSig(params(typs[24], typs[24]), params(typs[24]))
-	typs[128] = newSig(params(typs[20]), params(typs[22]))
-	typs[129] = newSig(params(typs[20]), params(typs[24]))
-	typs[130] = newSig(params(typs[20]), params(typs[60]))
-	typs[131] = newSig(params(typs[22]), params(typs[20]))
-	typs[132] = newSig(params(typs[24]), params(typs[20]))
-	typs[133] = newSig(params(typs[60]), params(typs[20]))
-	typs[134] = newSig(params(typs[26], typs[26]), params(typs[26]))
-	typs[135] = newSig(nil, params(typs[5]))
-	typs[136] = newSig(params(typs[5], typs[5]), nil)
-	typs[137] = newSig(params(typs[5], typs[5], typs[5]), nil)
-	typs[138] = newSig(params(typs[7], typs[1], typs[5]), nil)
-	typs[139] = types.NewSlice(typs[7])
-	typs[140] = newSig(params(typs[7], typs[139]), nil)
-	typs[141] = newSig(params(typs[64], typs[64]), nil)
-	typs[142] = newSig(params(typs[58], typs[58]), nil)
+	typs[62] = types.Types[types.TUINT32]
+	typs[63] = newSig(params(typs[62]), params(typs[7]))
+	typs[64] = newSig(params(typs[24]), params(typs[7]))
+	typs[65] = newSig(params(typs[28]), params(typs[7]))
+	typs[66] = types.Types[types.TUINT8]
+	typs[67] = types.NewSlice(typs[66])
+	typs[68] = newSig(params(typs[67]), params(typs[7]))
+	typs[69] = newSig(params(typs[1], typs[1]), params(typs[1]))
+	typs[70] = newSig(params(typs[1], typs[2]), params(typs[2]))
+	typs[71] = newSig(params(typs[1], typs[1], typs[1]), nil)
+	typs[72] = newSig(params(typs[1]), nil)
+	typs[73] = newSig(params(typs[57], typs[7], typs[7]), params(typs[6]))
+	typs[74] = newSig(nil, params(typs[62]))
+	typs[75] = types.NewMap(typs[2], typs[2])
+	typs[76] = newSig(params(typs[1], typs[22], typs[3]), params(typs[75]))
+	typs[77] = newSig(params(typs[1], typs[15], typs[3]), params(typs[75]))
+	typs[78] = newSig(nil, params(typs[75]))
+	typs[79] = newSig(params(typs[1], typs[75], typs[3]), params(typs[3]))
+	typs[80] = newSig(params(typs[1], typs[75], typs[62]), params(typs[3]))
+	typs[81] = newSig(params(typs[1], typs[75], typs[24]), params(typs[3]))
+	typs[82] = newSig(params(typs[1], typs[75], typs[28]), params(typs[3]))
+	typs[83] = newSig(params(typs[1], typs[75], typs[3], typs[1]), params(typs[3]))
+	typs[84] = newSig(params(typs[1], typs[75], typs[3]), params(typs[3], typs[6]))
+	typs[85] = newSig(params(typs[1], typs[75], typs[62]), params(typs[3], typs[6]))
+	typs[86] = newSig(params(typs[1], typs[75], typs[24]), params(typs[3], typs[6]))
+	typs[87] = newSig(params(typs[1], typs[75], typs[28]), params(typs[3], typs[6]))
+	typs[88] = newSig(params(typs[1], typs[75], typs[3], typs[1]), params(typs[3], typs[6]))
+	typs[89] = newSig(params(typs[1], typs[75], typs[7]), params(typs[3]))
+	typs[90] = newSig(params(typs[1], typs[75], typs[3]), nil)
+	typs[91] = newSig(params(typs[1], typs[75], typs[62]), nil)
+	typs[92] = newSig(params(typs[1], typs[75], typs[24]), nil)
+	typs[93] = newSig(params(typs[1], typs[75], typs[28]), nil)
+	typs[94] = newSig(params(typs[3]), nil)
+	typs[95] = newSig(params(typs[1], typs[75]), nil)
+	typs[96] = types.NewChan(typs[2], types.Cboth)
+	typs[97] = newSig(params(typs[1], typs[22]), params(typs[96]))
+	typs[98] = newSig(params(typs[1], typs[15]), params(typs[96]))
+	typs[99] = types.NewChan(typs[2], types.Crecv)
+	typs[100] = newSig(params(typs[99], typs[3]), nil)
+	typs[101] = newSig(params(typs[99], typs[3]), params(typs[6]))
+	typs[102] = types.NewChan(typs[2], types.Csend)
+	typs[103] = newSig(params(typs[102], typs[3]), nil)
+	typs[104] = types.NewArray(typs[0], 3)
+	typs[105] = types.NewStruct(types.NoPkg, []*types.Field{types.NewField(src.NoXPos, Lookup("enabled"), typs[6]), types.NewField(src.NoXPos, Lookup("pad"), typs[104]), types.NewField(src.NoXPos, Lookup("needed"), typs[6]), types.NewField(src.NoXPos, Lookup("cgo"), typs[6]), types.NewField(src.NoXPos, Lookup("alignme"), typs[24])})
+	typs[106] = newSig(params(typs[1], typs[3], typs[3]), nil)
+	typs[107] = newSig(params(typs[1], typs[3]), nil)
+	typs[108] = newSig(params(typs[1], typs[3], typs[15], typs[3], typs[15]), params(typs[15]))
+	typs[109] = newSig(params(typs[102], typs[3]), params(typs[6]))
+	typs[110] = newSig(params(typs[3], typs[99]), params(typs[6], typs[6]))
+	typs[111] = newSig(params(typs[57]), nil)
+	typs[112] = newSig(params(typs[1], typs[1], typs[57], typs[15], typs[15], typs[6]), params(typs[15], typs[6]))
+	typs[113] = newSig(params(typs[1], typs[15], typs[15]), params(typs[7]))
+	typs[114] = newSig(params(typs[1], typs[22], typs[22]), params(typs[7]))
+	typs[115] = newSig(params(typs[1], typs[15], typs[15], typs[7]), params(typs[7]))
+	typs[116] = types.NewSlice(typs[2])
+	typs[117] = newSig(params(typs[1], typs[116], typs[15]), params(typs[116]))
+	typs[118] = newSig(params(typs[1], typs[7], typs[15]), nil)
+	typs[119] = newSig(params(typs[1], typs[7], typs[22]), nil)
+	typs[120] = newSig(params(typs[3], typs[3], typs[5]), nil)
+	typs[121] = newSig(params(typs[7], typs[5]), nil)
+	typs[122] = newSig(params(typs[3], typs[3], typs[5]), params(typs[6]))
+	typs[123] = newSig(params(typs[3], typs[3]), params(typs[6]))
+	typs[124] = newSig(params(typs[7], typs[7]), params(typs[6]))
+	typs[125] = newSig(params(typs[7], typs[5], typs[5]), params(typs[5]))
+	typs[126] = newSig(params(typs[7], typs[5]), params(typs[5]))
+	typs[127] = newSig(params(typs[22], typs[22]), params(typs[22]))
+	typs[128] = newSig(params(typs[24], typs[24]), params(typs[24]))
+	typs[129] = newSig(params(typs[20]), params(typs[22]))
+	typs[130] = newSig(params(typs[20]), params(typs[24]))
+	typs[131] = newSig(params(typs[20]), params(typs[62]))
+	typs[132] = newSig(params(typs[22]), params(typs[20]))
+	typs[133] = newSig(params(typs[24]), params(typs[20]))
+	typs[134] = newSig(params(typs[62]), params(typs[20]))
+	typs[135] = newSig(params(typs[26], typs[26]), params(typs[26]))
+	typs[136] = newSig(nil, params(typs[5]))
+	typs[137] = newSig(params(typs[5], typs[5]), nil)
+	typs[138] = newSig(params(typs[5], typs[5], typs[5]), nil)
+	typs[139] = newSig(params(typs[7], typs[1], typs[5]), nil)
+	typs[140] = types.NewSlice(typs[7])
+	typs[141] = newSig(params(typs[7], typs[140]), nil)
+	typs[142] = newSig(params(typs[66], typs[66]), nil)
 	typs[143] = newSig(params(typs[60], typs[60]), nil)
-	typs[144] = newSig(params(typs[24], typs[24]), nil)
+	typs[144] = newSig(params(typs[62], typs[62]), nil)
+	typs[145] = newSig(params(typs[24], typs[24]), nil)
 	return typs[:]
 }
diff --git a/src/cmd/compile/internal/typecheck/builtin/runtime.go b/src/cmd/compile/internal/typecheck/builtin/runtime.go
index 2b29ea3c08ca72be0b35a2db22755490f76a4f11..605b9042880ca2e18fdee04d7b4048d89c6a071d 100644
--- a/src/cmd/compile/internal/typecheck/builtin/runtime.go
+++ b/src/cmd/compile/internal/typecheck/builtin/runtime.go
@@ -84,10 +84,15 @@ func decoderune(string, int) (retv rune, retk int)
 func countrunes(string) int
 
 // Non-empty-interface to non-empty-interface conversion.
-func convI2I(typ *byte, elem any) (ret any)
+func convI2I(typ *byte, itab *uintptr) (ret *uintptr)
 
-// Specialized type-to-interface conversion.
-// These return only a data pointer.
+// Convert non-interface type to the data word of a (empty or nonempty) interface.
+func convT(typ *byte, elem *any) unsafe.Pointer
+
+// Same as convT, for types with no pointers in them.
+func convTnoptr(typ *byte, elem *any) unsafe.Pointer
+
+// Specialized versions of convT for specific types.
 // These functions take concrete types in the runtime. But they may
 // be used for a wider range of types, which have the same memory
 // layout as the parameter type. The compiler converts the
@@ -99,14 +104,6 @@ func convT64(val uint64) unsafe.Pointer
 func convTstring(val string) unsafe.Pointer
 func convTslice(val []uint8) unsafe.Pointer
 
-// Type to empty-interface conversion.
-func convT2E(typ *byte, elem *any) (ret any)
-func convT2Enoptr(typ *byte, elem *any) (ret any)
-
-// Type to non-empty-interface conversion.
-func convT2I(tab *byte, elem *any) (ret any)
-func convT2Inoptr(tab *byte, elem *any) (ret any)
-
 // interface type assertions x.(T)
 func assertE2I(inter *byte, typ *byte) *byte
 func assertE2I2(inter *byte, eface any) (ret any)
diff --git a/src/cmd/compile/internal/typecheck/const.go b/src/cmd/compile/internal/typecheck/const.go
index 761b043794062d7dbb4c985d99319b35ba24f3eb..c27cf0e6465316284081afd08dd542d283dbdb68 100644
--- a/src/cmd/compile/internal/typecheck/const.go
+++ b/src/cmd/compile/internal/typecheck/const.go
@@ -881,7 +881,9 @@ func evalunsafe(n ir.Node) int64 {
 	case ir.OOFFSETOF:
 		// must be a selector.
 		n := n.(*ir.UnaryExpr)
-		if n.X.Op() != ir.OXDOT {
+		// ODOT and ODOTPTR are allowed in case the OXDOT transformation has
+		// already happened (e.g. during -G=3 stenciling).
+		if n.X.Op() != ir.OXDOT && n.X.Op() != ir.ODOT && n.X.Op() != ir.ODOTPTR {
 			base.Errorf("invalid expression %v", n)
 			return 0
 		}
@@ -901,7 +903,7 @@ func evalunsafe(n ir.Node) int64 {
 		switch tsel.Op() {
 		case ir.ODOT, ir.ODOTPTR:
 			break
-		case ir.OCALLPART:
+		case ir.OMETHVALUE:
 			base.Errorf("invalid expression %v: argument is a method value", n)
 			return 0
 		default:
diff --git a/src/cmd/compile/internal/typecheck/crawler.go b/src/cmd/compile/internal/typecheck/crawler.go
new file mode 100644
index 0000000000000000000000000000000000000000..9a348b9f37401dc28a557192486eaa5893390dbf
--- /dev/null
+++ b/src/cmd/compile/internal/typecheck/crawler.go
@@ -0,0 +1,231 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typecheck
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+)
+
+// crawlExports crawls the type/object graph rooted at the given list
+// of exported objects. Any functions that are found to be potentially
+// callable by importers are marked with ExportInline so that
+// iexport.go knows to re-export their inline body.
+func crawlExports(exports []*ir.Name) {
+	p := crawler{
+		marked:   make(map[*types.Type]bool),
+		embedded: make(map[*types.Type]bool),
+	}
+	for _, n := range exports {
+		p.markObject(n)
+	}
+}
+
+type crawler struct {
+	marked   map[*types.Type]bool // types already seen by markType
+	embedded map[*types.Type]bool // types already seen by markEmbed
+}
+
+// markObject visits a reachable object.
+func (p *crawler) markObject(n *ir.Name) {
+	if n.Op() == ir.ONAME && n.Class == ir.PFUNC {
+		p.markInlBody(n)
+	}
+
+	// If a declared type name is reachable, users can embed it in their
+	// own types, which makes even its unexported methods reachable.
+	if n.Op() == ir.OTYPE {
+		p.markEmbed(n.Type())
+	}
+
+	p.markType(n.Type())
+}
+
+// markType recursively visits types reachable from t to identify
+// functions whose inline bodies may be needed.
+func (p *crawler) markType(t *types.Type) {
+	if t.IsInstantiatedGeneric() {
+		// Re-instantiated types don't add anything new, so don't follow them.
+		return
+	}
+	if p.marked[t] {
+		return
+	}
+	p.marked[t] = true
+
+	// If this is a defined type, mark all of its associated
+	// methods. Skip interface types because t.Methods contains
+	// only their unexpanded method set (i.e., exclusive of
+	// interface embeddings), and the switch statement below
+	// handles their full method set.
+	if t.Sym() != nil && t.Kind() != types.TINTER {
+		for _, m := range t.Methods().Slice() {
+			if types.IsExported(m.Sym.Name) {
+				p.markObject(m.Nname.(*ir.Name))
+			}
+		}
+	}
+
+	// Recursively mark any types that can be produced given a
+	// value of type t: dereferencing a pointer; indexing or
+	// iterating over an array, slice, or map; receiving from a
+	// channel; accessing a struct field or interface method; or
+	// calling a function.
+	//
+	// Notably, we don't mark function parameter types, because
+	// the user already needs some way to construct values of
+	// those types.
+	switch t.Kind() {
+	case types.TPTR, types.TARRAY, types.TSLICE:
+		p.markType(t.Elem())
+
+	case types.TCHAN:
+		if t.ChanDir().CanRecv() {
+			p.markType(t.Elem())
+		}
+
+	case types.TMAP:
+		p.markType(t.Key())
+		p.markType(t.Elem())
+
+	case types.TSTRUCT:
+		for _, f := range t.FieldSlice() {
+			if types.IsExported(f.Sym.Name) || f.Embedded != 0 {
+				p.markType(f.Type)
+			}
+		}
+
+	case types.TFUNC:
+		for _, f := range t.Results().FieldSlice() {
+			p.markType(f.Type)
+		}
+
+	case types.TINTER:
+		// TODO(danscales) - will have to deal with the types in interface
+		// elements here when implemented in types2 and represented in types1.
+		for _, f := range t.AllMethods().Slice() {
+			if types.IsExported(f.Sym.Name) {
+				p.markType(f.Type)
+			}
+		}
+
+	case types.TTYPEPARAM:
+		// No other type that needs to be followed.
+	}
+}
+
+// markEmbed is similar to markType, but handles finding methods that
+// need to be re-exported because t can be embedded in user code
+// (possibly transitively).
+func (p *crawler) markEmbed(t *types.Type) {
+	if t.IsPtr() {
+		// Defined pointer type; not allowed to embed anyway.
+		if t.Sym() != nil {
+			return
+		}
+		t = t.Elem()
+	}
+
+	if t.IsInstantiatedGeneric() {
+		// Re-instantiated types don't add anything new, so don't follow them.
+		return
+	}
+
+	if p.embedded[t] {
+		return
+	}
+	p.embedded[t] = true
+
+	// If t is a defined type, then re-export all of its methods. Unlike
+	// in markType, we include even unexported methods here, because we
+	// still need to generate wrappers for them, even if the user can't
+	// refer to them directly.
+	if t.Sym() != nil && t.Kind() != types.TINTER {
+		for _, m := range t.Methods().Slice() {
+			p.markObject(m.Nname.(*ir.Name))
+		}
+	}
+
+	// If t is a struct, recursively visit its embedded fields.
+	if t.IsStruct() {
+		for _, f := range t.FieldSlice() {
+			if f.Embedded != 0 {
+				p.markEmbed(f.Type)
+			}
+		}
+	}
+}
+
+// markInlBody marks n's inline body for export and recursively
+// ensures all called functions are marked too.
+func (p *crawler) markInlBody(n *ir.Name) {
+	if n == nil {
+		return
+	}
+	if n.Op() != ir.ONAME || n.Class != ir.PFUNC {
+		base.Fatalf("markInlBody: unexpected %v, %v, %v", n, n.Op(), n.Class)
+	}
+	fn := n.Func
+	if fn == nil {
+		base.Fatalf("markInlBody: missing Func on %v", n)
+	}
+	if fn.Inl == nil {
+		return
+	}
+
+	if fn.ExportInline() {
+		return
+	}
+	fn.SetExportInline(true)
+
+	ImportedBody(fn)
+
+	var doFlood func(n ir.Node)
+	doFlood = func(n ir.Node) {
+		switch n.Op() {
+		case ir.OMETHEXPR, ir.ODOTMETH:
+			p.markInlBody(ir.MethodExprName(n))
+
+		case ir.ONAME:
+			n := n.(*ir.Name)
+			switch n.Class {
+			case ir.PFUNC:
+				p.markInlBody(n)
+				Export(n)
+			case ir.PEXTERN:
+				Export(n)
+			}
+			p.checkGenericType(n.Type())
+		case ir.OTYPE:
+			p.checkGenericType(n.Type())
+		case ir.OMETHVALUE:
+			// Okay, because we don't yet inline indirect
+			// calls to method values.
+		case ir.OCLOSURE:
+			// VisitList doesn't visit closure bodies, so force a
+			// recursive call to VisitList on the body of the closure.
+			ir.VisitList(n.(*ir.ClosureExpr).Func.Body, doFlood)
+		}
+	}
+
+	// Recursively identify all referenced functions for
+	// reexport. We want to include even non-called functions,
+	// because after inlining they might be callable.
+	ir.VisitList(fn.Inl.Body, doFlood)
+}
+
+// checkGenerictype ensures that we call markType() on any base generic type that
+// is written to the export file (even if not explicitly marked
+// for export), so its methods will be available for inlining if needed.
+func (p *crawler) checkGenericType(t *types.Type) {
+	if t != nil && t.HasTParam() {
+		if t.OrigSym != nil {
+			// Convert to the base generic type.
+			t = t.OrigSym.Def.Type()
+		}
+		p.markType(t)
+	}
+}
diff --git a/src/cmd/compile/internal/typecheck/dcl.go b/src/cmd/compile/internal/typecheck/dcl.go
index 5b771e3c0b1d836cb915efcd776aba3820464d41..472d8d2b8ad832ca08aa97e7a035efbd3bdcefae 100644
--- a/src/cmd/compile/internal/typecheck/dcl.go
+++ b/src/cmd/compile/internal/typecheck/dcl.go
@@ -6,7 +6,7 @@ package typecheck
 
 import (
 	"fmt"
-	"strconv"
+	"sync"
 
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
@@ -363,12 +363,10 @@ func funcargs(nt *ir.FuncType) {
 	}
 
 	// declare the out arguments.
-	gen := len(nt.Params)
-	for _, n := range nt.Results {
+	for i, n := range nt.Results {
 		if n.Sym == nil {
 			// Name so that escape analysis can track it. ~r stands for 'result'.
-			n.Sym = LookupNum("~r", gen)
-			gen++
+			n.Sym = LookupNum("~r", i)
 		}
 		if n.Sym.IsBlank() {
 			// Give it a name so we can assign to it during return. ~b stands for 'blank'.
@@ -377,8 +375,7 @@ func funcargs(nt *ir.FuncType) {
 			//	func g() int
 			// f is allowed to use a plain 'return' with no arguments, while g is not.
 			// So the two cases must be distinguished.
-			n.Sym = LookupNum("~b", gen)
-			gen++
+			n.Sym = LookupNum("~b", i)
 		}
 
 		funcarg(n, ir.PPARAMOUT)
@@ -431,6 +428,7 @@ func TempAt(pos src.XPos, curfn *ir.Func, t *types.Type) *ir.Name {
 	n := ir.NewNameAt(pos, s)
 	s.Def = n
 	n.SetType(t)
+	n.SetTypecheck(1)
 	n.Class = ir.PAUTO
 	n.SetEsc(ir.EscNever)
 	n.Curfn = curfn
@@ -443,20 +441,50 @@ func TempAt(pos src.XPos, curfn *ir.Func, t *types.Type) *ir.Name {
 	return n
 }
 
+var (
+	autotmpnamesmu sync.Mutex
+	autotmpnames   []string
+)
+
 // autotmpname returns the name for an autotmp variable numbered n.
 func autotmpname(n int) string {
-	// Give each tmp a different name so that they can be registerized.
-	// Add a preceding . to avoid clashing with legal names.
-	const prefix = ".autotmp_"
-	// Start with a buffer big enough to hold a large n.
-	b := []byte(prefix + "      ")[:len(prefix)]
-	b = strconv.AppendInt(b, int64(n), 10)
-	return types.InternString(b)
+	autotmpnamesmu.Lock()
+	defer autotmpnamesmu.Unlock()
+
+	// Grow autotmpnames, if needed.
+	if n >= len(autotmpnames) {
+		autotmpnames = append(autotmpnames, make([]string, n+1-len(autotmpnames))...)
+		autotmpnames = autotmpnames[:cap(autotmpnames)]
+	}
+
+	s := autotmpnames[n]
+	if s == "" {
+		// Give each tmp a different name so that they can be registerized.
+		// Add a preceding . to avoid clashing with legal names.
+		prefix := ".autotmp_%d"
+
+		// In quirks mode, pad out the number to stabilize variable
+		// sorting. This ensures autotmps 8 and 9 sort the same way even
+		// if they get renumbered to 9 and 10, respectively.
+		if base.Debug.UnifiedQuirks != 0 {
+			prefix = ".autotmp_%06d"
+		}
+
+		s = fmt.Sprintf(prefix, n)
+		autotmpnames[n] = s
+	}
+	return s
 }
 
 // f is method type, with receiver.
 // return function type, receiver as first argument (or not).
 func NewMethodType(sig *types.Type, recv *types.Type) *types.Type {
+	if sig.HasTParam() {
+		base.Fatalf("NewMethodType with type parameters in signature %+v", sig)
+	}
+	if recv != nil && recv.HasTParam() {
+		base.Fatalf("NewMethodType with type parameters in receiver %+v", recv)
+	}
 	nrecvs := 0
 	if recv != nil {
 		nrecvs++
diff --git a/src/cmd/compile/internal/typecheck/export.go b/src/cmd/compile/internal/typecheck/export.go
index 63d0a1ec6c656ce23e504458eacb456e01d12783..30726d4327f7ce8edf3d0879d73d939f094d90b0 100644
--- a/src/cmd/compile/internal/typecheck/export.go
+++ b/src/cmd/compile/internal/typecheck/export.go
@@ -15,22 +15,22 @@ import (
 
 // importalias declares symbol s as an imported type alias with type t.
 // ipkg is the package being imported
-func importalias(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
-	return importobj(ipkg, pos, s, ir.OTYPE, ir.PEXTERN, t)
+func importalias(pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
+	return importobj(pos, s, ir.OTYPE, ir.PEXTERN, t)
 }
 
 // importconst declares symbol s as an imported constant with type t and value val.
 // ipkg is the package being imported
-func importconst(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type, val constant.Value) *ir.Name {
-	n := importobj(ipkg, pos, s, ir.OLITERAL, ir.PEXTERN, t)
+func importconst(pos src.XPos, s *types.Sym, t *types.Type, val constant.Value) *ir.Name {
+	n := importobj(pos, s, ir.OLITERAL, ir.PEXTERN, t)
 	n.SetVal(val)
 	return n
 }
 
 // importfunc declares symbol s as an imported function with type t.
 // ipkg is the package being imported
-func importfunc(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
-	n := importobj(ipkg, pos, s, ir.ONAME, ir.PFUNC, t)
+func importfunc(pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
+	n := importobj(pos, s, ir.ONAME, ir.PFUNC, t)
 	n.Func = ir.NewFunc(pos)
 	n.Func.Nname = n
 	return n
@@ -38,8 +38,8 @@ func importfunc(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.
 
 // importobj declares symbol s as an imported object representable by op.
 // ipkg is the package being imported
-func importobj(ipkg *types.Pkg, pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class, t *types.Type) *ir.Name {
-	n := importsym(ipkg, pos, s, op, ctxt)
+func importobj(pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class, t *types.Type) *ir.Name {
+	n := importsym(pos, s, op, ctxt)
 	n.SetType(t)
 	if ctxt == ir.PFUNC {
 		n.Sym().SetFunc(true)
@@ -47,7 +47,7 @@ func importobj(ipkg *types.Pkg, pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Cl
 	return n
 }
 
-func importsym(ipkg *types.Pkg, pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class) *ir.Name {
+func importsym(pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class) *ir.Name {
 	if n := s.PkgDef(); n != nil {
 		base.Fatalf("importsym of symbol that already exists: %v", n)
 	}
@@ -61,14 +61,14 @@ func importsym(ipkg *types.Pkg, pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Cl
 // importtype returns the named type declared by symbol s.
 // If no such type has been declared yet, a forward declaration is returned.
 // ipkg is the package being imported
-func importtype(ipkg *types.Pkg, pos src.XPos, s *types.Sym) *ir.Name {
-	n := importsym(ipkg, pos, s, ir.OTYPE, ir.PEXTERN)
+func importtype(pos src.XPos, s *types.Sym) *ir.Name {
+	n := importsym(pos, s, ir.OTYPE, ir.PEXTERN)
 	n.SetType(types.NewNamed(n))
 	return n
 }
 
 // importvar declares symbol s as an imported variable with type t.
 // ipkg is the package being imported
-func importvar(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
-	return importobj(ipkg, pos, s, ir.ONAME, ir.PEXTERN, t)
+func importvar(pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
+	return importobj(pos, s, ir.ONAME, ir.PEXTERN, t)
 }
diff --git a/src/cmd/compile/internal/typecheck/expr.go b/src/cmd/compile/internal/typecheck/expr.go
index 24d141e8a2ce9149573b481b42541d353a2be704..7e974dfda863a0bc378d68fc0be98a8ec30bb222 100644
--- a/src/cmd/compile/internal/typecheck/expr.go
+++ b/src/cmd/compile/internal/typecheck/expr.go
@@ -311,14 +311,23 @@ func tcCompLit(n *ir.CompLitExpr) (res ir.Node) {
 
 				f := t.Field(i)
 				s := f.Sym
-				if s != nil && !types.IsExported(s.Name) && s.Pkg != types.LocalPkg {
-					base.Errorf("implicit assignment of unexported field '%s' in %v literal", s.Name, t)
+
+				// Do the test for assigning to unexported fields.
+				// But if this is an instantiated function, then
+				// the function has already been typechecked. In
+				// that case, don't do the test, since it can fail
+				// for the closure structs created in
+				// walkClosure(), because the instantiated
+				// function is compiled as if in the source
+				// package of the generic function.
+				if !(ir.CurFunc != nil && strings.Index(ir.CurFunc.Nname.Sym().Name, "[") >= 0) {
+					if s != nil && !types.IsExported(s.Name) && s.Pkg != types.LocalPkg {
+						base.Errorf("implicit assignment of unexported field '%s' in %v literal", s.Name, t)
+					}
 				}
 				// No pushtype allowed here. Must name fields for that.
 				n1 = AssignConv(n1, f.Type, "field value")
-				sk := ir.NewStructKeyExpr(base.Pos, f.Sym, n1)
-				sk.Offset = f.Offset
-				ls[i] = sk
+				ls[i] = ir.NewStructKeyExpr(base.Pos, f, n1)
 			}
 			if len(ls) < t.NumFields() {
 				base.Errorf("too few values in %v", n)
@@ -328,77 +337,33 @@ func tcCompLit(n *ir.CompLitExpr) (res ir.Node) {
 
 			// keyed list
 			ls := n.List
-			for i, l := range ls {
-				ir.SetPos(l)
-
-				if l.Op() == ir.OKEY {
-					kv := l.(*ir.KeyExpr)
-					key := kv.Key
-
-					// Sym might have resolved to name in other top-level
-					// package, because of import dot. Redirect to correct sym
-					// before we do the lookup.
-					s := key.Sym()
-					if id, ok := key.(*ir.Ident); ok && DotImportRefs[id] != nil {
-						s = Lookup(s.Name)
-					}
-
-					// An OXDOT uses the Sym field to hold
-					// the field to the right of the dot,
-					// so s will be non-nil, but an OXDOT
-					// is never a valid struct literal key.
-					if s == nil || s.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || s.IsBlank() {
-						base.Errorf("invalid field name %v in struct initializer", key)
-						continue
-					}
-
-					l = ir.NewStructKeyExpr(l.Pos(), s, kv.Value)
-					ls[i] = l
-				}
-
-				if l.Op() != ir.OSTRUCTKEY {
-					if !errored {
-						base.Errorf("mixture of field:value and value initializers")
-						errored = true
-					}
-					ls[i] = Expr(ls[i])
-					continue
-				}
-				l := l.(*ir.StructKeyExpr)
-
-				f := Lookdot1(nil, l.Field, t, t.Fields(), 0)
-				if f == nil {
-					if ci := Lookdot1(nil, l.Field, t, t.Fields(), 2); ci != nil { // Case-insensitive lookup.
-						if visible(ci.Sym) {
-							base.Errorf("unknown field '%v' in struct literal of type %v (but does have %v)", l.Field, t, ci.Sym)
-						} else if nonexported(l.Field) && l.Field.Name == ci.Sym.Name { // Ensure exactness before the suggestion.
-							base.Errorf("cannot refer to unexported field '%v' in struct literal of type %v", l.Field, t)
-						} else {
-							base.Errorf("unknown field '%v' in struct literal of type %v", l.Field, t)
+			for i, n := range ls {
+				ir.SetPos(n)
+
+				sk, ok := n.(*ir.StructKeyExpr)
+				if !ok {
+					kv, ok := n.(*ir.KeyExpr)
+					if !ok {
+						if !errored {
+							base.Errorf("mixture of field:value and value initializers")
+							errored = true
 						}
+						ls[i] = Expr(n)
 						continue
 					}
-					var f *types.Field
-					p, _ := dotpath(l.Field, t, &f, true)
-					if p == nil || f.IsMethod() {
-						base.Errorf("unknown field '%v' in struct literal of type %v", l.Field, t)
+
+					sk = tcStructLitKey(t, kv)
+					if sk == nil {
 						continue
 					}
-					// dotpath returns the parent embedded types in reverse order.
-					var ep []string
-					for ei := len(p) - 1; ei >= 0; ei-- {
-						ep = append(ep, p[ei].field.Sym.Name)
-					}
-					ep = append(ep, l.Field.Name)
-					base.Errorf("cannot use promoted field %v in struct literal of type %v", strings.Join(ep, "."), t)
-					continue
+
+					fielddup(sk.Sym().Name, hash)
 				}
-				fielddup(f.Sym.Name, hash)
-				l.Offset = f.Offset
 
 				// No pushtype allowed here. Tried and rejected.
-				l.Value = Expr(l.Value)
-				l.Value = AssignConv(l.Value, f.Type, "field value")
+				sk.Value = Expr(sk.Value)
+				sk.Value = AssignConv(sk.Value, sk.Field.Type, "field value")
+				ls[i] = sk
 			}
 		}
 
@@ -409,6 +374,60 @@ func tcCompLit(n *ir.CompLitExpr) (res ir.Node) {
 	return n
 }
 
+// tcStructLitKey typechecks an OKEY node that appeared within a
+// struct literal.
+func tcStructLitKey(typ *types.Type, kv *ir.KeyExpr) *ir.StructKeyExpr {
+	key := kv.Key
+
+	// Sym might have resolved to name in other top-level
+	// package, because of import dot. Redirect to correct sym
+	// before we do the lookup.
+	sym := key.Sym()
+	if id, ok := key.(*ir.Ident); ok && DotImportRefs[id] != nil {
+		sym = Lookup(sym.Name)
+	}
+
+	// An OXDOT uses the Sym field to hold
+	// the field to the right of the dot,
+	// so s will be non-nil, but an OXDOT
+	// is never a valid struct literal key.
+	if sym == nil || sym.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || sym.IsBlank() {
+		base.Errorf("invalid field name %v in struct initializer", key)
+		return nil
+	}
+
+	if f := Lookdot1(nil, sym, typ, typ.Fields(), 0); f != nil {
+		return ir.NewStructKeyExpr(kv.Pos(), f, kv.Value)
+	}
+
+	if ci := Lookdot1(nil, sym, typ, typ.Fields(), 2); ci != nil { // Case-insensitive lookup.
+		if visible(ci.Sym) {
+			base.Errorf("unknown field '%v' in struct literal of type %v (but does have %v)", sym, typ, ci.Sym)
+		} else if nonexported(sym) && sym.Name == ci.Sym.Name { // Ensure exactness before the suggestion.
+			base.Errorf("cannot refer to unexported field '%v' in struct literal of type %v", sym, typ)
+		} else {
+			base.Errorf("unknown field '%v' in struct literal of type %v", sym, typ)
+		}
+		return nil
+	}
+
+	var f *types.Field
+	p, _ := dotpath(sym, typ, &f, true)
+	if p == nil || f.IsMethod() {
+		base.Errorf("unknown field '%v' in struct literal of type %v", sym, typ)
+		return nil
+	}
+
+	// dotpath returns the parent embedded types in reverse order.
+	var ep []string
+	for ei := len(p) - 1; ei >= 0; ei-- {
+		ep = append(ep, p[ei].field.Sym.Name)
+	}
+	ep = append(ep, sym.Name)
+	base.Errorf("cannot use promoted field %v in struct literal of type %v", strings.Join(ep, "."), typ)
+	return nil
+}
+
 // tcConv typechecks an OCONV node.
 func tcConv(n *ir.ConvExpr) ir.Node {
 	types.CheckSize(n.Type()) // ensure width is calculated for backend
@@ -522,8 +541,8 @@ func tcDot(n *ir.SelectorExpr, top int) ir.Node {
 	}
 
 	if (n.Op() == ir.ODOTINTER || n.Op() == ir.ODOTMETH) && top&ctxCallee == 0 {
-		n.SetOp(ir.OCALLPART)
-		n.SetType(MethodValueWrapper(n).Type())
+		n.SetOp(ir.OMETHVALUE)
+		n.SetType(NewMethodType(n.Type(), nil))
 	}
 	return n
 }
diff --git a/src/cmd/compile/internal/typecheck/func.go b/src/cmd/compile/internal/typecheck/func.go
index fbcc784627d6ce8d64bb17eab49b7a679af10ab5..7dec65c1d6875fd54f305557bd7cca485e5da9f8 100644
--- a/src/cmd/compile/internal/typecheck/func.go
+++ b/src/cmd/compile/internal/typecheck/func.go
@@ -8,28 +8,29 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
+	"cmd/internal/src"
 
 	"fmt"
 	"go/constant"
 	"go/token"
 )
 
-// package all the arguments that match a ... T parameter into a []T.
-func MakeDotArgs(typ *types.Type, args []ir.Node) ir.Node {
+// MakeDotArgs package all the arguments that match a ... T parameter into a []T.
+func MakeDotArgs(pos src.XPos, typ *types.Type, args []ir.Node) ir.Node {
 	var n ir.Node
 	if len(args) == 0 {
-		n = NodNil()
+		n = ir.NewNilExpr(pos)
 		n.SetType(typ)
 	} else {
-		lit := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
-		lit.List.Append(args...)
+		args = append([]ir.Node(nil), args...)
+		lit := ir.NewCompLitExpr(pos, ir.OCOMPLIT, ir.TypeNode(typ), args)
 		lit.SetImplicit(true)
 		n = lit
 	}
 
 	n = Expr(n)
 	if n.Type() == nil {
-		base.Fatalf("mkdotargslice: typecheck failed")
+		base.FatalfAt(pos, "mkdotargslice: typecheck failed")
 	}
 	return n
 }
@@ -47,7 +48,7 @@ func FixVariadicCall(call *ir.CallExpr) {
 
 	args := call.Args
 	extra := args[vi:]
-	slice := MakeDotArgs(vt, extra)
+	slice := MakeDotArgs(call.Pos(), vt, extra)
 	for i := range extra {
 		extra[i] = nil // allow GC
 	}
@@ -56,6 +57,25 @@ func FixVariadicCall(call *ir.CallExpr) {
 	call.IsDDD = true
 }
 
+// FixMethodCall rewrites a method call t.M(...) into a function call T.M(t, ...).
+func FixMethodCall(call *ir.CallExpr) {
+	if call.X.Op() != ir.ODOTMETH {
+		return
+	}
+
+	dot := call.X.(*ir.SelectorExpr)
+
+	fn := Expr(ir.NewSelectorExpr(dot.Pos(), ir.OXDOT, ir.TypeNode(dot.X.Type()), dot.Selection.Sym))
+
+	args := make([]ir.Node, 1+len(call.Args))
+	args[0] = dot.X
+	copy(args[1:], call.Args)
+
+	call.SetOp(ir.OCALLFUNC)
+	call.X = fn
+	call.Args = args
+}
+
 // ClosureType returns the struct type used to hold all the information
 // needed in the closure for clo (clo must be a OCLOSURE node).
 // The address of a variable of the returned type can be cast to a func.
@@ -73,8 +93,25 @@ func ClosureType(clo *ir.ClosureExpr) *types.Type {
 	// The information appears in the binary in the form of type descriptors;
 	// the struct is unnamed so that closures in multiple packages with the
 	// same struct type can share the descriptor.
+
+	// Make sure the .F field is in the same package as the rest of the
+	// fields. This deals with closures in instantiated functions, which are
+	// compiled as if from the source package of the generic function.
+	var pkg *types.Pkg
+	if len(clo.Func.ClosureVars) == 0 {
+		pkg = types.LocalPkg
+	} else {
+		for _, v := range clo.Func.ClosureVars {
+			if pkg == nil {
+				pkg = v.Sym().Pkg
+			} else if pkg != v.Sym().Pkg {
+				base.Fatalf("Closure variables from multiple packages")
+			}
+		}
+	}
+
 	fields := []*types.Field{
-		types.NewField(base.Pos, Lookup(".F"), types.Types[types.TUINTPTR]),
+		types.NewField(base.Pos, pkg.Lookup(".F"), types.Types[types.TUINTPTR]),
 	}
 	for _, v := range clo.Func.ClosureVars {
 		typ := v.Type()
@@ -88,10 +125,10 @@ func ClosureType(clo *ir.ClosureExpr) *types.Type {
 	return typ
 }
 
-// PartialCallType returns the struct type used to hold all the information
-// needed in the closure for n (n must be a OCALLPART node).
-// The address of a variable of the returned type can be cast to a func.
-func PartialCallType(n *ir.SelectorExpr) *types.Type {
+// MethodValueType returns the struct type used to hold all the information
+// needed in the closure for a OMETHVALUE node. The address of a variable of
+// the returned type can be cast to a func.
+func MethodValueType(n *ir.SelectorExpr) *types.Type {
 	t := types.NewStruct(types.NoPkg, []*types.Field{
 		types.NewField(base.Pos, Lookup("F"), types.Types[types.TUINTPTR]),
 		types.NewField(base.Pos, Lookup("R"), n.X.Type()),
@@ -181,153 +218,38 @@ func fnpkg(fn *ir.Name) *types.Pkg {
 	return fn.Sym().Pkg
 }
 
-// ClosureName generates a new unique name for a closure within
-// outerfunc.
-func ClosureName(outerfunc *ir.Func) *types.Sym {
-	outer := "glob."
-	prefix := "func"
-	gen := &globClosgen
-
-	if outerfunc != nil {
-		if outerfunc.OClosure != nil {
-			prefix = ""
-		}
-
-		outer = ir.FuncName(outerfunc)
-
-		// There may be multiple functions named "_". In those
-		// cases, we can't use their individual Closgens as it
-		// would lead to name clashes.
-		if !ir.IsBlank(outerfunc.Nname) {
-			gen = &outerfunc.Closgen
-		}
-	}
-
-	*gen++
-	return Lookup(fmt.Sprintf("%s.%s%d", outer, prefix, *gen))
-}
-
-// globClosgen is like Func.Closgen, but for the global scope.
-var globClosgen int32
-
-// MethodValueWrapper returns the DCLFUNC node representing the
-// wrapper function (*-fm) needed for the given method value. If the
-// wrapper function hasn't already been created yet, it's created and
-// added to Target.Decls.
-//
-// TODO(mdempsky): Move into walk. This isn't part of type checking.
-func MethodValueWrapper(dot *ir.SelectorExpr) *ir.Func {
-	if dot.Op() != ir.OCALLPART {
-		base.Fatalf("MethodValueWrapper: unexpected %v (%v)", dot, dot.Op())
-	}
-
-	t0 := dot.Type()
-	meth := dot.Sel
-	rcvrtype := dot.X.Type()
-	sym := ir.MethodSymSuffix(rcvrtype, meth, "-fm")
-
-	if sym.Uniq() {
-		return sym.Def.(*ir.Func)
-	}
-	sym.SetUniq(true)
-
-	savecurfn := ir.CurFunc
-	saveLineNo := base.Pos
-	ir.CurFunc = nil
-
-	// Set line number equal to the line number where the method is declared.
-	if pos := dot.Selection.Pos; pos.IsKnown() {
-		base.Pos = pos
-	}
-	// Note: !dot.Selection.Pos.IsKnown() happens for method expressions where
-	// the method is implicitly declared. The Error method of the
-	// built-in error type is one such method.  We leave the line
-	// number at the use of the method expression in this
-	// case. See issue 29389.
-
-	tfn := ir.NewFuncType(base.Pos, nil,
-		NewFuncParams(t0.Params(), true),
-		NewFuncParams(t0.Results(), false))
-
-	fn := DeclFunc(sym, tfn)
-	fn.SetDupok(true)
-	fn.SetNeedctxt(true)
-	fn.SetWrapper(true)
-
-	// Declare and initialize variable holding receiver.
-	ptr := ir.NewNameAt(base.Pos, Lookup(".this"))
-	ptr.Class = ir.PAUTOHEAP
-	ptr.SetType(rcvrtype)
-	ptr.Curfn = fn
-	ptr.SetIsClosureVar(true)
-	ptr.SetByval(true)
-	fn.ClosureVars = append(fn.ClosureVars, ptr)
-
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, ir.NewSelectorExpr(base.Pos, ir.OXDOT, ptr, meth), nil)
-	call.Args = ir.ParamNames(tfn.Type())
-	call.IsDDD = tfn.Type().IsVariadic()
-
-	var body ir.Node = call
-	if t0.NumResults() != 0 {
-		ret := ir.NewReturnStmt(base.Pos, nil)
-		ret.Results = []ir.Node{call}
-		body = ret
-	}
-
-	fn.Body = []ir.Node{body}
-	FinishFuncBody()
-
-	Func(fn)
-	// Need to typecheck the body of the just-generated wrapper.
-	// typecheckslice() requires that Curfn is set when processing an ORETURN.
-	ir.CurFunc = fn
-	Stmts(fn.Body)
-	sym.Def = fn
-	Target.Decls = append(Target.Decls, fn)
-	ir.CurFunc = savecurfn
-	base.Pos = saveLineNo
-
-	return fn
-}
-
 // tcClosure typechecks an OCLOSURE node. It also creates the named
 // function associated with the closure.
 // TODO: This creation of the named function should probably really be done in a
 // separate pass from type-checking.
-func tcClosure(clo *ir.ClosureExpr, top int) {
+func tcClosure(clo *ir.ClosureExpr, top int) ir.Node {
 	fn := clo.Func
+
+	// We used to allow IR builders to typecheck the underlying Func
+	// themselves, but that led to too much variety and inconsistency
+	// around who's responsible for naming the function, typechecking
+	// it, or adding it to Target.Decls.
+	//
+	// It's now all or nothing. Callers are still allowed to do these
+	// themselves, but then they assume responsibility for all of them.
+	if fn.Typecheck() == 1 {
+		base.FatalfAt(fn.Pos(), "underlying closure func already typechecked: %v", fn)
+	}
+
 	// Set current associated iota value, so iota can be used inside
 	// function in ConstSpec, see issue #22344
 	if x := getIotaValue(); x >= 0 {
 		fn.Iota = x
 	}
 
-	fn.SetClosureCalled(top&ctxCallee != 0)
-
-	// Do not typecheck fn twice, otherwise, we will end up pushing
-	// fn to Target.Decls multiple times, causing InitLSym called twice.
-	// See #30709
-	if fn.Typecheck() == 1 {
-		clo.SetType(fn.Type())
-		return
-	}
-
-	// Don't give a name and add to Target.Decls if we are typechecking an inlined
-	// body in ImportedBody(), since we only want to create the named function
-	// when the closure is actually inlined (and then we force a typecheck
-	// explicitly in (*inlsubst).node()).
-	if !inTypeCheckInl {
-		fn.Nname.SetSym(ClosureName(ir.CurFunc))
-		ir.MarkFunc(fn.Nname)
-	}
+	ir.NameClosure(clo, ir.CurFunc)
 	Func(fn)
-	clo.SetType(fn.Type())
 
 	// Type check the body now, but only if we're inside a function.
 	// At top level (in a variable initialization: curfn==nil) we're not
 	// ready to type check code yet; we'll check it later, because the
 	// underlying closure function we create is added to Target.Decls.
-	if ir.CurFunc != nil && clo.Type() != nil {
+	if ir.CurFunc != nil {
 		oldfn := ir.CurFunc
 		ir.CurFunc = fn
 		Stmts(fn.Body)
@@ -353,14 +275,17 @@ func tcClosure(clo *ir.ClosureExpr, top int) {
 	}
 	fn.ClosureVars = fn.ClosureVars[:out]
 
-	if base.Flag.W > 1 {
-		s := fmt.Sprintf("New closure func: %s", ir.FuncName(fn))
-		ir.Dump(s, fn)
-	}
-	if !inTypeCheckInl {
-		// Add function to Target.Decls once only when we give it a name
-		Target.Decls = append(Target.Decls, fn)
+	clo.SetType(fn.Type())
+
+	target := Target
+	if inTypeCheckInl {
+		// We're typechecking an imported function, so it's not actually
+		// part of Target. Skip adding it to Target.Decls so we don't
+		// compile it again.
+		target = nil
 	}
+
+	return ir.UseClosure(clo, target)
 }
 
 // type check function definition
@@ -390,10 +315,6 @@ func tcFunc(n *ir.Func) {
 
 // tcCall typechecks an OCALL node.
 func tcCall(n *ir.CallExpr, top int) ir.Node {
-	n.Use = ir.CallUseExpr
-	if top == ctxStmt {
-		n.Use = ir.CallUseStmt
-	}
 	Stmts(n.Init()) // imported rewritten f(g()) calls (#30907)
 	n.X = typecheck(n.X, ctxExpr|ctxType|ctxCallee)
 	if n.X.Diag() {
@@ -509,6 +430,7 @@ func tcCall(n *ir.CallExpr, top int) ir.Node {
 	}
 
 	typecheckaste(ir.OCALL, n.X, n.IsDDD, t.Params(), n.Args, func() string { return fmt.Sprintf("argument to %v", n.X) })
+	FixMethodCall(n)
 	if t.NumResults() == 0 {
 		return n
 	}
@@ -979,6 +901,21 @@ func tcRecover(n *ir.CallExpr) ir.Node {
 	return n
 }
 
+// tcRecoverFP typechecks an ORECOVERFP node.
+func tcRecoverFP(n *ir.CallExpr) ir.Node {
+	if len(n.Args) != 1 {
+		base.FatalfAt(n.Pos(), "wrong number of arguments: %v", n)
+	}
+
+	n.Args[0] = Expr(n.Args[0])
+	if !n.Args[0].Type().IsPtrShaped() {
+		base.FatalfAt(n.Pos(), "%L is not pointer shaped", n.Args[0])
+	}
+
+	n.SetType(types.Types[types.TINTER])
+	return n
+}
+
 // tcUnsafeAdd typechecks an OUNSAFEADD node.
 func tcUnsafeAdd(n *ir.BinaryExpr) *ir.BinaryExpr {
 	if !types.AllowsGoVersion(curpkg(), 1, 17) {
diff --git a/src/cmd/compile/internal/typecheck/iexport.go b/src/cmd/compile/internal/typecheck/iexport.go
index 64d68ef62550d8a4b5c2d3046336e48c46c8352c..75d61157833686cbcc843ef1375df36001789080 100644
--- a/src/cmd/compile/internal/typecheck/iexport.go
+++ b/src/cmd/compile/internal/typecheck/iexport.go
@@ -173,6 +173,8 @@
 //     }
 //
 //
+//  TODO(danscales): fill in doc for 'type TypeParamType' and 'type InstType'
+//
 //     type Signature struct {
 //         Params   []Param
 //         Results  []Param
@@ -202,7 +204,6 @@
 package typecheck
 
 import (
-	"bufio"
 	"bytes"
 	"crypto/md5"
 	"encoding/binary"
@@ -221,9 +222,18 @@ import (
 )
 
 // Current indexed export format version. Increase with each format change.
-// 1: added column details to Pos
 // 0: Go1.11 encoding
-const iexportVersion = 1
+// 1: added column details to Pos
+// 2: added information for generic function/types (currently unstable)
+const (
+	iexportVersionGo1_11 = 0
+	iexportVersionPosCol = 1
+	// TODO: before release, change this back to 2.  Kept at previous version
+	// for now (for testing).
+	iexportVersionGenerics = iexportVersionPosCol
+
+	iexportVersionCurrent = iexportVersionGenerics
+)
 
 // predeclReserved is the number of type offsets reserved for types
 // implicitly declared in the universe block.
@@ -244,6 +254,9 @@ const (
 	signatureType
 	structType
 	interfaceType
+	typeParamType
+	instType
+	unionType
 )
 
 const (
@@ -251,13 +264,22 @@ const (
 	magic = 0x6742937dc293105
 )
 
-func WriteExports(out *bufio.Writer) {
+// WriteExports writes the indexed export format to out. If extensions
+// is true, then the compiler-only extensions are included.
+func WriteExports(out io.Writer, extensions bool) {
+	if extensions {
+		// If we're exporting inline bodies, invoke the crawler to mark
+		// which bodies to include.
+		crawlExports(Target.Exports)
+	}
+
 	p := iexporter{
 		allPkgs:     map[*types.Pkg]bool{},
 		stringIndex: map[string]uint64{},
 		declIndex:   map[*types.Sym]uint64{},
 		inlineIndex: map[*types.Sym]uint64{},
 		typIndex:    map[*types.Type]uint64{},
+		extensions:  extensions,
 	}
 
 	for i, pt := range predeclared() {
@@ -293,7 +315,7 @@ func WriteExports(out *bufio.Writer) {
 	// Assemble header.
 	var hdr intWriter
 	hdr.WriteByte('i')
-	hdr.uint64(iexportVersion)
+	hdr.uint64(iexportVersionCurrent)
 	hdr.uint64(uint64(p.strings.Len()))
 	hdr.uint64(dataLen)
 
@@ -379,6 +401,8 @@ type iexporter struct {
 	declIndex   map[*types.Sym]uint64
 	inlineIndex map[*types.Sym]uint64
 	typIndex    map[*types.Type]uint64
+
+	extensions bool
 }
 
 // stringOff returns the offset of s within the string section.
@@ -449,7 +473,9 @@ func (p *iexporter) doDecl(n *ir.Name) {
 			w.tag('V')
 			w.pos(n.Pos())
 			w.typ(n.Type())
-			w.varExt(n)
+			if w.p.extensions {
+				w.varExt(n)
+			}
 
 		case ir.PFUNC:
 			if ir.IsMethod(n) {
@@ -457,10 +483,25 @@ func (p *iexporter) doDecl(n *ir.Name) {
 			}
 
 			// Function.
-			w.tag('F')
+			if n.Type().TParams().NumFields() == 0 {
+				w.tag('F')
+			} else {
+				w.tag('G')
+			}
 			w.pos(n.Pos())
+			// The tparam list of the function type is the
+			// declaration of the type params. So, write out the type
+			// params right now. Then those type params will be
+			// referenced via their type offset (via typOff) in all
+			// other places in the signature and function that they
+			// are used.
+			if n.Type().TParams().NumFields() > 0 {
+				w.tparamList(n.Type().TParams().FieldSlice())
+			}
 			w.signature(n.Type())
-			w.funcExt(n)
+			if w.p.extensions {
+				w.funcExt(n)
+			}
 
 		default:
 			base.Fatalf("unexpected class: %v, %v", n, n.Class)
@@ -476,10 +517,25 @@ func (p *iexporter) doDecl(n *ir.Name) {
 		w.tag('C')
 		w.pos(n.Pos())
 		w.value(n.Type(), n.Val())
-		w.constExt(n)
+		if w.p.extensions {
+			w.constExt(n)
+		}
 
 	case ir.OTYPE:
-		if types.IsDotAlias(n.Sym()) {
+		if n.Type().IsTypeParam() && n.Type().Underlying() == n.Type() {
+			// Even though it has local scope, a typeparam requires a
+			// declaration via its package and unique name, because it
+			// may be referenced within its type bound during its own
+			// definition.
+			w.tag('P')
+			// A typeparam has a name, and has a type bound rather
+			// than an underlying type.
+			w.pos(n.Pos())
+			w.typ(n.Type().Bound())
+			break
+		}
+
+		if n.Alias() {
 			// Alias.
 			w.tag('A')
 			w.pos(n.Pos())
@@ -488,9 +544,18 @@ func (p *iexporter) doDecl(n *ir.Name) {
 		}
 
 		// Defined type.
-		w.tag('T')
+		if len(n.Type().RParams()) == 0 {
+			w.tag('T')
+		} else {
+			w.tag('U')
+		}
 		w.pos(n.Pos())
 
+		if len(n.Type().RParams()) > 0 {
+			// Export type parameters, if any, needed for this type
+			w.typeList(n.Type().RParams())
+		}
+
 		underlying := n.Type().Underlying()
 		if underlying == types.ErrorType.Underlying() {
 			// For "type T error", use error as the
@@ -505,22 +570,31 @@ func (p *iexporter) doDecl(n *ir.Name) {
 
 		t := n.Type()
 		if t.IsInterface() {
-			w.typeExt(t)
+			if w.p.extensions {
+				w.typeExt(t)
+			}
 			break
 		}
 
-		ms := t.Methods()
-		w.uint64(uint64(ms.Len()))
-		for _, m := range ms.Slice() {
+		// Sort methods, for consistency with types2.
+		methods := append([]*types.Field(nil), t.Methods().Slice()...)
+		if base.Debug.UnifiedQuirks != 0 {
+			sort.Sort(types.MethodsByName(methods))
+		}
+
+		w.uint64(uint64(len(methods)))
+		for _, m := range methods {
 			w.pos(m.Pos)
 			w.selector(m.Sym)
 			w.param(m.Type.Recv())
 			w.signature(m.Type)
 		}
 
-		w.typeExt(t)
-		for _, m := range ms.Slice() {
-			w.methExt(m)
+		if w.p.extensions {
+			w.typeExt(t)
+			for _, m := range methods {
+				w.methExt(m)
+			}
 		}
 
 	default:
@@ -803,8 +877,46 @@ func (w *exportWriter) startType(k itag) {
 }
 
 func (w *exportWriter) doTyp(t *types.Type) {
-	if t.Sym() != nil {
-		if t.Sym().Pkg == types.BuiltinPkg || t.Sym().Pkg == ir.Pkgs.Unsafe {
+	s := t.Sym()
+	if s != nil && t.OrigSym != nil {
+		assert(base.Flag.G > 0)
+		// This is an instantiated type - could be a re-instantiation like
+		// Value[T2] or a full instantiation like Value[int].
+		if strings.Index(s.Name, "[") < 0 {
+			base.Fatalf("incorrect name for instantiated type")
+		}
+		w.startType(instType)
+		w.pos(t.Pos())
+		// Export the type arguments for the instantiated type. The
+		// instantiated type could be in a method header (e.g. "func (v
+		// *Value[T2]) set (...) { ... }"), so the type args are "new"
+		// typeparams. Or the instantiated type could be in a
+		// function/method body, so the type args are either concrete
+		// types or existing typeparams from the function/method header.
+		w.typeList(t.RParams())
+		// Export a reference to the base type.
+		baseType := t.OrigSym.Def.(*ir.Name).Type()
+		w.typ(baseType)
+		return
+	}
+
+	// The 't.Underlying() == t' check is to confirm this is a base typeparam
+	// type, rather than a defined type with typeparam underlying type, like:
+	// type orderedAbs[T any] T
+	if t.IsTypeParam() && t.Underlying() == t {
+		assert(base.Flag.G > 0)
+		if s.Pkg == types.BuiltinPkg || s.Pkg == ir.Pkgs.Unsafe {
+			base.Fatalf("builtin type missing from typIndex: %v", t)
+		}
+		// Write out the first use of a type param as a qualified ident.
+		// This will force a "declaration" of the type param.
+		w.startType(typeParamType)
+		w.qualifiedIdent(t.Obj().(*ir.Name))
+		return
+	}
+
+	if s != nil {
+		if s.Pkg == types.BuiltinPkg || s.Pkg == ir.Pkgs.Unsafe {
 			base.Fatalf("builtin type missing from typIndex: %v", t)
 		}
 
@@ -865,6 +977,14 @@ func (w *exportWriter) doTyp(t *types.Type) {
 			}
 		}
 
+		// Sort methods and embedded types, for consistency with types2.
+		// Note: embedded types may be anonymous, and types2 sorts them
+		// with sort.Stable too.
+		if base.Debug.UnifiedQuirks != 0 {
+			sort.Sort(types.MethodsByName(methods))
+			sort.Stable(types.EmbeddedsByName(embeddeds))
+		}
+
 		w.startType(interfaceType)
 		w.setPkg(t.Pkg(), true)
 
@@ -881,6 +1001,19 @@ func (w *exportWriter) doTyp(t *types.Type) {
 			w.signature(f.Type)
 		}
 
+	case types.TUNION:
+		assert(base.Flag.G > 0)
+		// TODO(danscales): possibly put out the tilde bools in more
+		// compact form.
+		w.startType(unionType)
+		nt := t.NumTerms()
+		w.uint64(uint64(nt))
+		for i := 0; i < nt; i++ {
+			typ, tilde := t.Term(i)
+			w.bool(tilde)
+			w.typ(typ)
+		}
+
 	default:
 		base.Fatalf("unexpected type: %v", t)
 	}
@@ -906,6 +1039,23 @@ func (w *exportWriter) signature(t *types.Type) {
 	}
 }
 
+func (w *exportWriter) typeList(ts []*types.Type) {
+	w.uint64(uint64(len(ts)))
+	for _, rparam := range ts {
+		w.typ(rparam)
+	}
+}
+
+func (w *exportWriter) tparamList(fs []*types.Field) {
+	w.uint64(uint64(len(fs)))
+	for _, f := range fs {
+		if !f.Type.IsTypeParam() {
+			base.Fatalf("unexpected non-typeparam")
+		}
+		w.typ(f.Type)
+	}
+}
+
 func (w *exportWriter) paramList(fs []*types.Field) {
 	w.uint64(uint64(len(fs)))
 	for _, f := range fs {
@@ -948,26 +1098,50 @@ func constTypeOf(typ *types.Type) constant.Kind {
 }
 
 func (w *exportWriter) value(typ *types.Type, v constant.Value) {
-	ir.AssertValidTypeForConst(typ, v)
 	w.typ(typ)
+	var kind constant.Kind
+	var valType *types.Type
+
+	if typ.IsTypeParam() {
+		// A constant will have a TYPEPARAM type if it appears in a place
+		// where it must match that typeparam type (e.g. in a binary
+		// operation with a variable of that typeparam type). If so, then
+		// we must write out its actual constant kind as well, so its
+		// constant val can be read in properly during import.
+		kind = v.Kind()
+		w.int64(int64(kind))
+
+		switch kind {
+		case constant.Int:
+			valType = types.Types[types.TINT64]
+		case constant.Float:
+			valType = types.Types[types.TFLOAT64]
+		case constant.Complex:
+			valType = types.Types[types.TCOMPLEX128]
+		}
+	} else {
+		ir.AssertValidTypeForConst(typ, v)
+		kind = constTypeOf(typ)
+		valType = typ
+	}
 
-	// Each type has only one admissible constant representation,
-	// so we could type switch directly on v.U here. However,
-	// switching on the type increases symmetry with import logic
-	// and provides a useful consistency check.
+	// Each type has only one admissible constant representation, so we could
+	// type switch directly on v.Kind() here. However, switching on the type
+	// (in the non-typeparam case) increases symmetry with import logic and
+	// provides a useful consistency check.
 
-	switch constTypeOf(typ) {
+	switch kind {
 	case constant.Bool:
 		w.bool(constant.BoolVal(v))
 	case constant.String:
 		w.string(constant.StringVal(v))
 	case constant.Int:
-		w.mpint(v, typ)
+		w.mpint(v, valType)
 	case constant.Float:
-		w.mpfloat(v, typ)
+		w.mpfloat(v, valType)
 	case constant.Complex:
-		w.mpfloat(constant.Real(v), typ)
-		w.mpfloat(constant.Imag(v), typ)
+		w.mpfloat(constant.Real(v), valType)
+		w.mpfloat(constant.Imag(v), valType)
 	}
 }
 
@@ -1185,10 +1359,14 @@ func (w *exportWriter) funcExt(n *ir.Name) {
 		}
 	}
 
-	// Inline body.
+	// Write out inline body or body of a generic function/method.
+	if n.Type().HasTParam() && n.Func.Body != nil && n.Func.Inl == nil {
+		base.FatalfAt(n.Pos(), "generic function is not marked inlineable")
+	}
 	if n.Func.Inl != nil {
 		w.uint64(1 + uint64(n.Func.Inl.Cost))
-		if n.Func.ExportInline() {
+		w.bool(n.Func.Inl.CanDelayResults)
+		if n.Func.ExportInline() || n.Type().HasTParam() {
 			w.p.doInline(n)
 		}
 
@@ -1432,7 +1610,12 @@ func (w *exportWriter) commList(cases []*ir.CommClause) {
 	w.uint64(uint64(len(cases)))
 	for _, cas := range cases {
 		w.pos(cas.Pos())
-		w.node(cas.Comm)
+		defaultCase := cas.Comm == nil
+		w.bool(defaultCase)
+		if !defaultCase {
+			// Only call w.node for non-default cause (cas.Comm is non-nil)
+			w.node(cas.Comm)
+		}
 		w.stmtList(cas.Body)
 	}
 }
@@ -1460,7 +1643,9 @@ func (w *exportWriter) expr(n ir.Node) {
 	// (somewhat closely following the structure of exprfmt in fmt.go)
 	case ir.ONIL:
 		n := n.(*ir.NilExpr)
-		if !n.Type().HasNil() {
+		// If n is a typeparam, it will have already been checked
+		// for proper use by the types2 typechecker.
+		if !n.Type().IsTypeParam() && !n.Type().HasNil() {
 			base.Fatalf("unexpected type for nil: %v", n.Type())
 		}
 		w.op(ir.ONIL)
@@ -1469,7 +1654,11 @@ func (w *exportWriter) expr(n ir.Node) {
 
 	case ir.OLITERAL:
 		w.op(ir.OLITERAL)
-		w.pos(n.Pos())
+		if ir.HasUniquePos(n) {
+			w.pos(n.Pos())
+		} else {
+			w.pos(src.NoXPos)
+		}
 		w.value(n.Type(), n.Val())
 
 	case ir.ONAME:
@@ -1488,6 +1677,16 @@ func (w *exportWriter) expr(n ir.Node) {
 		// We don't need a type here, as the type will be provided at the
 		// declaration of n.
 		w.op(ir.ONAME)
+
+		// This handles the case where we haven't yet transformed a call
+		// to a builtin, so we must write out the builtin as a name in the
+		// builtin package.
+		isBuiltin := n.BuiltinOp != ir.OXXX
+		w.bool(isBuiltin)
+		if isBuiltin {
+			w.string(n.Sym().Name)
+			break
+		}
 		w.localName(n)
 
 	// case OPACK, ONONAME:
@@ -1585,12 +1784,11 @@ func (w *exportWriter) expr(n ir.Node) {
 	// case OSTRUCTKEY:
 	//	unreachable - handled in case OSTRUCTLIT by elemList
 
-	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
+	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
 		n := n.(*ir.SelectorExpr)
 		if go117ExportTypes {
-			if n.Op() == ir.OXDOT {
-				base.Fatalf("shouldn't encounter XDOT  in new exporter")
-			}
+			// For go117ExportTypes, we usually see all ops except
+			// OXDOT, but we can see OXDOT for generic functions.
 			w.op(n.Op())
 		} else {
 			w.op(ir.OXDOT)
@@ -1600,11 +1798,16 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.exoticSelector(n.Sel)
 		if go117ExportTypes {
 			w.exoticType(n.Type())
-			if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER {
+			if n.Op() == ir.OXDOT {
+				// n.Selection for method references will be
+				// reconstructed during import.
+				w.bool(n.Selection != nil)
+			} else if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER {
 				w.exoticField(n.Selection)
 			}
-			// n.Selection is not required for OMETHEXPR, ODOTMETH, and OCALLPART. It will
-			// be reconstructed during import.
+			// n.Selection is not required for OMETHEXPR, ODOTMETH, and OMETHVALUE. It will
+			// be reconstructed during import.  n.Selection is computed during
+			// transformDot() for OXDOT.
 		}
 
 	case ir.ODOTTYPE, ir.ODOTTYPE2:
@@ -1629,7 +1832,7 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.expr(n.X)
 		w.expr(n.Index)
 		if go117ExportTypes {
-			w.typ(n.Type())
+			w.exoticType(n.Type())
 			if n.Op() == ir.OINDEXMAP {
 				w.bool(n.Assigned)
 			}
@@ -1677,7 +1880,7 @@ func (w *exportWriter) expr(n ir.Node) {
 			w.op(ir.OEND)
 		}
 
-	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVIDATA, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
 		n := n.(*ir.ConvExpr)
 		if go117ExportTypes {
 			w.op(n.Op())
@@ -1732,7 +1935,6 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.bool(n.IsDDD)
 		if go117ExportTypes {
 			w.exoticType(n.Type())
-			w.uint64(uint64(n.Use))
 		}
 
 	case ir.OMAKEMAP, ir.OMAKECHAN, ir.OMAKESLICE:
@@ -1759,8 +1961,16 @@ func (w *exportWriter) expr(n ir.Node) {
 			w.op(ir.OEND)
 		}
 
+	case ir.OLINKSYMOFFSET:
+		n := n.(*ir.LinksymOffsetExpr)
+		w.op(ir.OLINKSYMOFFSET)
+		w.pos(n.Pos())
+		w.string(n.Linksym.Name)
+		w.uint64(uint64(n.Offset_))
+		w.typ(n.Type())
+
 	// unary expressions
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV:
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV, ir.OIDATA:
 		n := n.(*ir.UnaryExpr)
 		w.op(n.Op())
 		w.pos(n.Pos())
@@ -1796,7 +2006,7 @@ func (w *exportWriter) expr(n ir.Node) {
 
 	// binary expressions
 	case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OEQ, ir.OGE, ir.OGT, ir.OLE, ir.OLT,
-		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR:
+		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR, ir.OEFACE:
 		n := n.(*ir.BinaryExpr)
 		w.op(n.Op())
 		w.pos(n.Pos())
@@ -1829,6 +2039,26 @@ func (w *exportWriter) expr(n ir.Node) {
 		// if exporting, DCLCONST should just be removed as its usage
 		// has already been replaced with literals
 
+	case ir.OFUNCINST:
+		n := n.(*ir.InstExpr)
+		w.op(ir.OFUNCINST)
+		w.pos(n.Pos())
+		w.expr(n.X)
+		w.uint64(uint64(len(n.Targs)))
+		for _, targ := range n.Targs {
+			w.typ(targ.Type())
+		}
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
+
+	case ir.OSELRECV2:
+		n := n.(*ir.AssignListStmt)
+		w.op(ir.OSELRECV2)
+		w.pos(n.Pos())
+		w.exprList(n.Lhs)
+		w.exprList(n.Rhs)
+
 	default:
 		base.Fatalf("cannot export %v (%d) node\n"+
 			"\t==> please file an issue and assign to gri@", n.Op(), int(n.Op()))
@@ -1864,11 +2094,8 @@ func (w *exportWriter) fieldList(list ir.Nodes) {
 	for _, n := range list {
 		n := n.(*ir.StructKeyExpr)
 		w.pos(n.Pos())
-		w.selector(n.Field)
+		w.exoticField(n.Field)
 		w.expr(n.Value)
-		if go117ExportTypes {
-			w.uint64(uint64(n.Offset))
-		}
 	}
 }
 
@@ -1902,8 +2129,15 @@ func (w *exportWriter) localIdent(s *types.Sym) {
 		return
 	}
 
-	// TODO(mdempsky): Fix autotmp hack.
-	if i := strings.LastIndex(name, "."); i >= 0 && !strings.HasPrefix(name, ".autotmp_") {
+	// The name of autotmp variables isn't important; they just need to
+	// be unique. To stabilize the export data, simply write out "$" as
+	// a marker and let the importer generate its own unique name.
+	if strings.HasPrefix(name, ".autotmp_") {
+		w.string("$autotmp")
+		return
+	}
+
+	if i := strings.LastIndex(name, "."); i >= 0 && !strings.HasPrefix(name, ".dict") { // TODO: just use autotmp names for dictionaries?
 		base.Fatalf("unexpected dot in identifier: %v", name)
 	}
 
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 37f5a7bba0ac9a351c2373c969e8dce025b57185..a1a3ac3e8ad7617cfaafb9676a691219b0f844c3 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -11,7 +11,6 @@ import (
 	"encoding/binary"
 	"fmt"
 	"go/constant"
-	"io"
 	"math/big"
 	"os"
 	"strings"
@@ -19,8 +18,6 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
-	"cmd/internal/bio"
-	"cmd/internal/goobj"
 	"cmd/internal/obj"
 	"cmd/internal/src"
 )
@@ -94,7 +91,7 @@ func importReaderFor(sym *types.Sym, importers map[*types.Sym]iimporterAndOffset
 }
 
 type intReader struct {
-	*bio.Reader
+	*strings.Reader
 	pkg *types.Pkg
 }
 
@@ -116,33 +113,34 @@ func (r *intReader) uint64() uint64 {
 	return i
 }
 
-func ReadImports(pkg *types.Pkg, in *bio.Reader) (fingerprint goobj.FingerprintType) {
-	ird := &intReader{in, pkg}
+func ReadImports(pkg *types.Pkg, data string) {
+	ird := &intReader{strings.NewReader(data), pkg}
 
 	version := ird.uint64()
-	if version != iexportVersion {
-		base.Errorf("import %q: unknown export format version %d", pkg.Path, version)
+	switch version {
+	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
+	default:
+		if version > iexportVersionGenerics {
+			base.Errorf("import %q: unstable export format version %d, just recompile", pkg.Path, version)
+		} else {
+			base.Errorf("import %q: unknown export format version %d", pkg.Path, version)
+		}
 		base.ErrorExit()
 	}
 
-	sLen := ird.uint64()
-	dLen := ird.uint64()
-
-	// Map string (and data) section into memory as a single large
-	// string. This reduces heap fragmentation and allows
-	// returning individual substrings very efficiently.
-	data, err := mapFile(in.File(), in.Offset(), int64(sLen+dLen))
-	if err != nil {
-		base.Errorf("import %q: mapping input: %v", pkg.Path, err)
-		base.ErrorExit()
-	}
-	stringData := data[:sLen]
-	declData := data[sLen:]
+	sLen := int64(ird.uint64())
+	dLen := int64(ird.uint64())
 
-	in.MustSeek(int64(sLen+dLen), os.SEEK_CUR)
+	// TODO(mdempsky): Replace os.SEEK_CUR with io.SeekCurrent after
+	// #44505 is fixed.
+	whence, _ := ird.Seek(0, os.SEEK_CUR)
+	stringData := data[whence : whence+sLen]
+	declData := data[whence+sLen : whence+sLen+dLen]
+	ird.Seek(sLen+dLen, os.SEEK_CUR)
 
 	p := &iimporter{
-		ipkg: pkg,
+		exportVersion: version,
+		ipkg:          pkg,
 
 		pkgCache:     map[uint64]*types.Pkg{},
 		posBaseCache: map[uint64]*src.PosBase{},
@@ -200,18 +198,11 @@ func ReadImports(pkg *types.Pkg, in *bio.Reader) (fingerprint goobj.FingerprintT
 			}
 		}
 	}
-
-	// Fingerprint.
-	_, err = io.ReadFull(in, fingerprint[:])
-	if err != nil {
-		base.Errorf("import %s: error reading fingerprint", pkg.Path)
-		base.ErrorExit()
-	}
-	return fingerprint
 }
 
 type iimporter struct {
-	ipkg *types.Pkg
+	exportVersion uint64
+	ipkg          *types.Pkg
 
 	pkgCache     map[uint64]*types.Pkg
 	posBaseCache map[uint64]*src.PosBase
@@ -273,6 +264,7 @@ type importReader struct {
 	// Slice of all dcls for function, including any interior closures
 	allDcls        []*ir.Name
 	allClosureVars []*ir.Name
+	autotmpgen     int
 }
 
 func (p *iimporter) newReader(off uint64, pkg *types.Pkg) *importReader {
@@ -302,37 +294,53 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
 	case 'A':
 		typ := r.typ()
 
-		return importalias(r.p.ipkg, pos, sym, typ)
+		return importalias(pos, sym, typ)
 
 	case 'C':
 		typ := r.typ()
 		val := r.value(typ)
 
-		n := importconst(r.p.ipkg, pos, sym, typ, val)
+		n := importconst(pos, sym, typ, val)
 		r.constExt(n)
 		return n
 
-	case 'F':
-		typ := r.signature(nil)
+	case 'F', 'G':
+		var tparams []*types.Field
+		if tag == 'G' {
+			tparams = r.tparamList()
+		}
+		typ := r.signature(nil, tparams)
 
-		n := importfunc(r.p.ipkg, pos, sym, typ)
+		n := importfunc(pos, sym, typ)
 		r.funcExt(n)
 		return n
 
-	case 'T':
+	case 'T', 'U':
+		var rparams []*types.Type
+		if tag == 'U' {
+			rparams = r.typeList()
+		}
+
 		// Types can be recursive. We need to setup a stub
 		// declaration before recursing.
-		n := importtype(r.p.ipkg, pos, sym)
+		n := importtype(pos, sym)
 		t := n.Type()
+		if tag == 'U' {
+			t.SetRParams(rparams)
+		}
 
 		// We also need to defer width calculations until
 		// after the underlying type has been assigned.
 		types.DeferCheckSize()
+		deferDoInst()
 		underlying := r.typ()
 		t.SetUnderlying(underlying)
-		types.ResumeCheckSize()
 
 		if underlying.IsInterface() {
+			// Finish up all type instantiations and CheckSize calls
+			// now that a top-level type is fully constructed.
+			resumeDoInst()
+			types.ResumeCheckSize()
 			r.typeExt(t)
 			return n
 		}
@@ -342,7 +350,7 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
 			mpos := r.pos()
 			msym := r.selector()
 			recv := r.param()
-			mtyp := r.signature(recv)
+			mtyp := r.signature(recv, nil)
 
 			// MethodSym already marked m.Sym as a function.
 			m := ir.NewNameAt(mpos, ir.MethodSym(recv.Type, msym))
@@ -358,16 +366,43 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
 		}
 		t.Methods().Set(ms)
 
+		// Finish up all instantiations and CheckSize calls now
+		// that a top-level type is fully constructed.
+		resumeDoInst()
+		types.ResumeCheckSize()
+
 		r.typeExt(t)
 		for _, m := range ms {
 			r.methExt(m)
 		}
 		return n
 
+	case 'P':
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected type param type")
+		}
+		if sym.Def != nil {
+			// Make sure we use the same type param type for the same
+			// name, whether it is created during types1-import or
+			// this types2-to-types1 translation.
+			return sym.Def.(*ir.Name)
+		}
+		// The typeparam index is set at the point where the containing type
+		// param list is imported.
+		t := types.NewTypeParam(sym, 0)
+		// Nname needed to save the pos.
+		nname := ir.NewDeclNameAt(pos, ir.OTYPE, sym)
+		sym.Def = nname
+		nname.SetType(t)
+		t.SetNod(nname)
+
+		t.SetBound(r.typ())
+		return nname
+
 	case 'V':
 		typ := r.typ()
 
-		n := importvar(r.p.ipkg, pos, sym, typ)
+		n := importvar(pos, sym, typ)
 		r.varExt(n)
 		return n
 
@@ -377,27 +412,47 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
 	}
 }
 
-func (p *importReader) value(typ *types.Type) constant.Value {
-	switch constTypeOf(typ) {
+func (r *importReader) value(typ *types.Type) constant.Value {
+	var kind constant.Kind
+	var valType *types.Type
+
+	if typ.IsTypeParam() {
+		// If a constant had a typeparam type, then we wrote out its
+		// actual constant kind as well.
+		kind = constant.Kind(r.int64())
+		switch kind {
+		case constant.Int:
+			valType = types.Types[types.TINT64]
+		case constant.Float:
+			valType = types.Types[types.TFLOAT64]
+		case constant.Complex:
+			valType = types.Types[types.TCOMPLEX128]
+		}
+	} else {
+		kind = constTypeOf(typ)
+		valType = typ
+	}
+
+	switch kind {
 	case constant.Bool:
-		return constant.MakeBool(p.bool())
+		return constant.MakeBool(r.bool())
 	case constant.String:
-		return constant.MakeString(p.string())
+		return constant.MakeString(r.string())
 	case constant.Int:
 		var i big.Int
-		p.mpint(&i, typ)
+		r.mpint(&i, valType)
 		return constant.Make(&i)
 	case constant.Float:
-		return p.float(typ)
+		return r.float(valType)
 	case constant.Complex:
-		return makeComplex(p.float(typ), p.float(typ))
+		return makeComplex(r.float(valType), r.float(valType))
 	}
 
 	base.Fatalf("unexpected value type: %v", typ)
 	panic("unreachable")
 }
 
-func (p *importReader) mpint(x *big.Int, typ *types.Type) {
+func (r *importReader) mpint(x *big.Int, typ *types.Type) {
 	signed, maxBytes := intSize(typ)
 
 	maxSmall := 256 - maxBytes
@@ -408,7 +463,7 @@ func (p *importReader) mpint(x *big.Int, typ *types.Type) {
 		maxSmall = 256
 	}
 
-	n, _ := p.ReadByte()
+	n, _ := r.ReadByte()
 	if uint(n) < maxSmall {
 		v := int64(n)
 		if signed {
@@ -429,30 +484,30 @@ func (p *importReader) mpint(x *big.Int, typ *types.Type) {
 		base.Fatalf("weird decoding: %v, %v => %v", n, signed, v)
 	}
 	b := make([]byte, v)
-	p.Read(b)
+	r.Read(b)
 	x.SetBytes(b)
 	if signed && n&1 != 0 {
 		x.Neg(x)
 	}
 }
 
-func (p *importReader) float(typ *types.Type) constant.Value {
+func (r *importReader) float(typ *types.Type) constant.Value {
 	var mant big.Int
-	p.mpint(&mant, typ)
+	r.mpint(&mant, typ)
 	var f big.Float
 	f.SetInt(&mant)
 	if f.Sign() != 0 {
-		f.SetMantExp(&f, int(p.int64()))
+		f.SetMantExp(&f, int(r.int64()))
 	}
 	return constant.Make(&f)
 }
 
-func (p *importReader) mprat(orig constant.Value) constant.Value {
-	if !p.bool() {
+func (r *importReader) mprat(orig constant.Value) constant.Value {
+	if !r.bool() {
 		return orig
 	}
 	var rat big.Rat
-	rat.SetString(p.string())
+	rat.SetString(r.string())
 	return constant.Make(&rat)
 }
 
@@ -462,8 +517,15 @@ func (r *importReader) ident(selector bool) *types.Sym {
 		return nil
 	}
 	pkg := r.currPkg
-	if selector && types.IsExported(name) {
-		pkg = types.LocalPkg
+	if selector {
+		if types.IsExported(name) {
+			pkg = types.LocalPkg
+		}
+	} else {
+		if name == "$autotmp" {
+			name = autotmpname(r.autotmpgen)
+			r.autotmpgen++
+		}
 	}
 	return pkg.Lookup(name)
 }
@@ -503,7 +565,14 @@ func (r *importReader) pos() src.XPos {
 }
 
 func (r *importReader) typ() *types.Type {
-	return r.p.typAt(r.uint64())
+	// If this is a top-level type call, defer type instantiations until the
+	// type is fully constructed.
+	types.DeferCheckSize()
+	deferDoInst()
+	t := r.p.typAt(r.uint64())
+	resumeDoInst()
+	types.ResumeCheckSize()
+	return t
 }
 
 func (r *importReader) exoticType() *types.Type {
@@ -641,7 +710,13 @@ func (p *iimporter) typAt(off uint64) *types.Type {
 		// are pushed to compile queue, then draining from the queue for compiling.
 		// During this process, the size calculation is disabled, so it is not safe for
 		// calculating size during SSA generation anymore. See issue #44732.
-		types.CheckSize(t)
+		//
+		// No need to calc sizes for re-instantiated generic types, and
+		// they are not necessarily resolved until the top-level type is
+		// defined (because of recursive types).
+		if t.OrigSym == nil || !t.HasTParam() {
+			types.CheckSize(t)
+		}
 		p.typCache[off] = t
 	}
 	return t
@@ -680,7 +755,7 @@ func (r *importReader) typ1() *types.Type {
 
 	case signatureType:
 		r.setPkg()
-		return r.signature(nil)
+		return r.signature(nil, nil)
 
 	case structType:
 		r.setPkg()
@@ -718,16 +793,64 @@ func (r *importReader) typ1() *types.Type {
 		for i := range methods {
 			pos := r.pos()
 			sym := r.selector()
-			typ := r.signature(fakeRecvField())
+			typ := r.signature(fakeRecvField(), nil)
 
 			methods[i] = types.NewField(pos, sym, typ)
 		}
 
+		if len(embeddeds)+len(methods) == 0 {
+			return types.Types[types.TINTER]
+		}
+
 		t := types.NewInterface(r.currPkg, append(embeddeds, methods...))
 
 		// Ensure we expand the interface in the frontend (#25055).
 		types.CheckSize(t)
 		return t
+
+	case typeParamType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected type param type")
+		}
+		// Similar to code for defined types, since we "declared"
+		// typeparams to deal with recursion (typeparam is used within its
+		// own type bound).
+		ident := r.qualifiedIdent()
+		if ident.Sym().Def != nil {
+			return ident.Sym().Def.(*ir.Name).Type()
+		}
+		n := expandDecl(ident)
+		if n.Op() != ir.OTYPE {
+			base.Fatalf("expected OTYPE, got %v: %v, %v", n.Op(), n.Sym(), n)
+		}
+		return n.Type()
+
+	case instType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected instantiation type")
+		}
+		pos := r.pos()
+		len := r.uint64()
+		targs := make([]*types.Type, len)
+		for i := range targs {
+			targs[i] = r.typ()
+		}
+		baseType := r.typ()
+		t := Instantiate(pos, baseType, targs)
+		return t
+
+	case unionType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected instantiation type")
+		}
+		nt := int(r.uint64())
+		terms := make([]*types.Type, nt)
+		tildes := make([]bool, nt)
+		for i := range terms {
+			tildes[i] = r.bool()
+			terms[i] = r.typ()
+		}
+		return types.NewUnion(terms, tildes)
 	}
 }
 
@@ -735,13 +858,42 @@ func (r *importReader) kind() itag {
 	return itag(r.uint64())
 }
 
-func (r *importReader) signature(recv *types.Field) *types.Type {
+func (r *importReader) signature(recv *types.Field, tparams []*types.Field) *types.Type {
 	params := r.paramList()
 	results := r.paramList()
 	if n := len(params); n > 0 {
 		params[n-1].SetIsDDD(r.bool())
 	}
-	return types.NewSignature(r.currPkg, recv, nil, params, results)
+	return types.NewSignature(r.currPkg, recv, tparams, params, results)
+}
+
+func (r *importReader) typeList() []*types.Type {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	ts := make([]*types.Type, n)
+	for i := range ts {
+		ts[i] = r.typ()
+		if ts[i].IsTypeParam() {
+			ts[i].SetIndex(i)
+		}
+	}
+	return ts
+}
+
+func (r *importReader) tparamList() []*types.Field {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	fs := make([]*types.Field, n)
+	for i := range fs {
+		typ := r.typ()
+		typ.SetIndex(i)
+		fs[i] = types.NewField(typ.Pos(), typ.Sym(), typ)
+	}
+	return fs
 }
 
 func (r *importReader) paramList() []*types.Field {
@@ -809,7 +961,9 @@ func (r *importReader) funcExt(n *ir.Name) {
 
 	n.Func.ABI = obj.ABI(r.uint64())
 
-	n.SetPragma(ir.PragmaFlag(r.uint64()))
+	// Make sure //go:noinline pragma is imported (so stenciled functions have
+	// same noinline status as the corresponding generic function.)
+	n.Func.Pragma = ir.PragmaFlag(r.uint64())
 
 	// Escape analysis.
 	for _, fs := range &types.RecvsParams {
@@ -821,7 +975,8 @@ func (r *importReader) funcExt(n *ir.Name) {
 	// Inline body.
 	if u := r.uint64(); u > 0 {
 		n.Func.Inl = &ir.Inline{
-			Cost: int32(u - 1),
+			Cost:            int32(u - 1),
+			CanDelayResults: r.bool(),
 		}
 		n.Func.Endlineno = r.pos()
 	}
@@ -852,7 +1007,13 @@ func (r *importReader) symIdx(s *types.Sym) {
 
 func (r *importReader) typeExt(t *types.Type) {
 	t.SetNotInHeap(r.bool())
-	i, pi := r.int64(), r.int64()
+	SetBaseTypeIndex(t, r.int64(), r.int64())
+}
+
+func SetBaseTypeIndex(t *types.Type, i, pi int64) {
+	if t.Obj() == nil {
+		base.Fatalf("SetBaseTypeIndex on non-defined type %v", t)
+	}
 	if i != -1 && pi != -1 {
 		typeSymIdx[t] = [2]int64{i, pi}
 	}
@@ -860,6 +1021,7 @@ func (r *importReader) typeExt(t *types.Type) {
 
 // Map imported type T to the index of type descriptor symbols of T and *T,
 // so we can use index to reference the symbol.
+// TODO(mdempsky): Store this information directly in the Type's Name.
 var typeSymIdx = make(map[*types.Type][2]int64)
 
 func BaseTypeIndex(t *types.Type) int64 {
@@ -936,6 +1098,10 @@ func (r *importReader) funcBody(fn *ir.Func) {
 	fn.Inl.Body = body
 
 	r.curfn = outerfn
+	if base.Flag.W >= 3 {
+		fmt.Printf("Imported for %v", fn)
+		ir.DumpList("", fn.Inl.Body)
+	}
 }
 
 func (r *importReader) readNames(fn *ir.Func) []*ir.Name {
@@ -1032,7 +1198,13 @@ func (r *importReader) caseList(switchExpr ir.Node) []*ir.CaseClause {
 func (r *importReader) commList() []*ir.CommClause {
 	cases := make([]*ir.CommClause, r.uint64())
 	for i := range cases {
-		cases[i] = ir.NewCommStmt(r.pos(), r.node(), r.stmtList())
+		pos := r.pos()
+		defaultCase := r.bool()
+		var comm ir.Node
+		if !defaultCase {
+			comm = r.node()
+		}
+		cases[i] = ir.NewCommStmt(pos, comm, r.stmtList())
 	}
 	return cases
 }
@@ -1095,6 +1267,10 @@ func (r *importReader) node() ir.Node {
 		return n
 
 	case ir.ONAME:
+		isBuiltin := r.bool()
+		if isBuiltin {
+			return types.BuiltinPkg.Lookup(r.string()).Def.(*ir.Name)
+		}
 		return r.localName()
 
 	// case OPACK, ONONAME:
@@ -1117,28 +1293,18 @@ func (r *importReader) node() ir.Node {
 	case ir.OCLOSURE:
 		//println("Importing CLOSURE")
 		pos := r.pos()
-		typ := r.signature(nil)
+		typ := r.signature(nil, nil)
 
 		// All the remaining code below is similar to (*noder).funcLit(), but
 		// with Dcls and ClosureVars lists already set up
-		fn := ir.NewFunc(pos)
-		fn.SetIsHiddenClosure(true)
-		fn.Nname = ir.NewNameAt(pos, ir.BlankNode.Sym())
-		fn.Nname.Func = fn
-		fn.Nname.Ntype = ir.TypeNode(typ)
-		fn.Nname.Defn = fn
+		fn := ir.NewClosureFunc(pos, true)
 		fn.Nname.SetType(typ)
 
 		cvars := make([]*ir.Name, r.int64())
 		for i := range cvars {
 			cvars[i] = ir.CaptureName(r.pos(), fn, r.localName().Canonical())
-			if go117ExportTypes {
-				if cvars[i].Type() != nil || cvars[i].Defn == nil {
-					base.Fatalf("bad import of closure variable")
-				}
-				// Closure variable should have Defn set, which is its captured
-				// variable, and it gets the same type as the captured variable.
-				cvars[i].SetType(cvars[i].Defn.Type())
+			if go117ExportTypes && cvars[i].Defn == nil {
+				base.Fatalf("bad import of closure variable")
 			}
 		}
 		fn.ClosureVars = cvars
@@ -1159,12 +1325,10 @@ func (r *importReader) node() ir.Node {
 
 		ir.FinishCaptureNames(pos, r.curfn, fn)
 
-		clo := ir.NewClosureExpr(pos, fn)
-		fn.OClosure = clo
+		clo := fn.OClosure
 		if go117ExportTypes {
 			clo.SetType(typ)
 		}
-
 		return clo
 
 	case ir.OSTRUCTLIT:
@@ -1202,35 +1366,54 @@ func (r *importReader) node() ir.Node {
 	// case OSTRUCTKEY:
 	//	unreachable - handled in case OSTRUCTLIT by elemList
 
-	case ir.OXDOT:
-		// see parser.new_dotname
-		if go117ExportTypes {
-			base.Fatalf("shouldn't encounter XDOT in new importer")
-		}
-		return ir.NewSelectorExpr(r.pos(), ir.OXDOT, r.expr(), r.exoticSelector())
-
-	case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
-		if !go117ExportTypes {
-			// unreachable - mapped to case OXDOT by exporter
+	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
+		// For !go117ExportTypes,  we should only see OXDOT.
+		// For go117ExportTypes, we usually see all the other ops, but can see
+		// OXDOT for generic functions.
+		if op != ir.OXDOT && !go117ExportTypes {
 			goto error
 		}
 		pos := r.pos()
 		expr := r.expr()
 		sel := r.exoticSelector()
 		n := ir.NewSelectorExpr(pos, op, expr, sel)
-		n.SetType(r.exoticType())
-		switch op {
-		case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER:
-			n.Selection = r.exoticField()
-		case ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
-			// These require a Lookup to link to the correct declaration.
-			rcvrType := expr.Type()
-			typ := n.Type()
-			n.Selection = Lookdot(n, rcvrType, 1)
-			if op == ir.OCALLPART || op == ir.OMETHEXPR {
-				// Lookdot clobbers the opcode and type, undo that.
-				n.SetOp(op)
-				n.SetType(typ)
+		if go117ExportTypes {
+			n.SetType(r.exoticType())
+			switch op {
+			case ir.OXDOT:
+				hasSelection := r.bool()
+				// We reconstruct n.Selection for method calls on
+				// generic types and method calls due to type param
+				// bounds.  Otherwise, n.Selection is nil.
+				if hasSelection {
+					n1 := ir.NewSelectorExpr(pos, op, expr, sel)
+					AddImplicitDots(n1)
+					var m *types.Field
+					if n1.X.Type().IsTypeParam() {
+						genType := n1.X.Type().Bound()
+						m = Lookdot1(n1, sel, genType, genType.AllMethods(), 1)
+					} else {
+						genType := types.ReceiverBaseType(n1.X.Type())
+						if genType.IsInstantiatedGeneric() {
+							genType = genType.OrigSym.Def.Type()
+						}
+						m = Lookdot1(n1, sel, genType, genType.Methods(), 1)
+					}
+					assert(m != nil)
+					n.Selection = m
+				}
+			case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER:
+				n.Selection = r.exoticField()
+			case ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
+				// These require a Lookup to link to the correct declaration.
+				rcvrType := expr.Type()
+				typ := n.Type()
+				n.Selection = Lookdot(n, rcvrType, 1)
+				if op == ir.OMETHVALUE || op == ir.OMETHEXPR {
+					// Lookdot clobbers the opcode and type, undo that.
+					n.SetOp(op)
+					n.SetType(typ)
+				}
 			}
 		}
 		return n
@@ -1247,7 +1430,7 @@ func (r *importReader) node() ir.Node {
 		n := ir.NewIndexExpr(r.pos(), r.expr(), r.expr())
 		if go117ExportTypes {
 			n.SetOp(op)
-			n.SetType(r.typ())
+			n.SetType(r.exoticType())
 			if op == ir.OINDEXMAP {
 				n.Assigned = r.bool()
 			}
@@ -1267,7 +1450,7 @@ func (r *importReader) node() ir.Node {
 		}
 		return n
 
-	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVIDATA, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
 		if !go117ExportTypes && op != ir.OCONV {
 			// 	unreachable - mapped to OCONV case by exporter
 			goto error
@@ -1318,7 +1501,6 @@ func (r *importReader) node() ir.Node {
 		n.IsDDD = r.bool()
 		if go117ExportTypes {
 			n.SetType(r.exoticType())
-			n.Use = ir.CallUse(r.uint64())
 		}
 		return n
 
@@ -1343,8 +1525,15 @@ func (r *importReader) node() ir.Node {
 		n.Args.Append(r.exprList()...)
 		return n
 
+	case ir.OLINKSYMOFFSET:
+		pos := r.pos()
+		name := r.string()
+		off := r.uint64()
+		typ := r.typ()
+		return ir.NewLinksymOffsetExpr(pos, Lookup(name).Linksym(), int64(off), typ)
+
 	// unary expressions
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV:
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV, ir.OIDATA:
 		n := ir.NewUnaryExpr(r.pos(), op, r.expr())
 		if go117ExportTypes {
 			n.SetType(r.typ())
@@ -1368,7 +1557,7 @@ func (r *importReader) node() ir.Node {
 
 	// binary expressions
 	case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OEQ, ir.OGE, ir.OGT, ir.OLE, ir.OLT,
-		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR:
+		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR, ir.OEFACE:
 		n := ir.NewBinaryExpr(r.pos(), op, r.expr(), r.expr())
 		if go117ExportTypes {
 			n.SetType(r.typ())
@@ -1496,6 +1685,26 @@ func (r *importReader) node() ir.Node {
 	case ir.OEND:
 		return nil
 
+	case ir.OFUNCINST:
+		pos := r.pos()
+		x := r.expr()
+		ntargs := r.uint64()
+		var targs []ir.Node
+		if ntargs > 0 {
+			targs = make([]ir.Node, ntargs)
+			for i := range targs {
+				targs[i] = ir.TypeNode(r.typ())
+			}
+		}
+		n := ir.NewInstExpr(pos, ir.OFUNCINST, x, targs)
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
+
+	case ir.OSELRECV2:
+		return ir.NewAssignListStmt(r.pos(), ir.OSELRECV2, r.exprList(), r.exprList())
+
 	default:
 		base.Fatalf("cannot import %v (%d) node\n"+
 			"\t==> please file an issue and assign to gri@", op, int(op))
@@ -1517,11 +1726,7 @@ func (r *importReader) op() ir.Op {
 func (r *importReader) fieldList() []ir.Node {
 	list := make([]ir.Node, r.uint64())
 	for i := range list {
-		x := ir.NewStructKeyExpr(r.pos(), r.selector(), r.expr())
-		if go117ExportTypes {
-			x.Offset = int64(r.uint64())
-		}
-		list[i] = x
+		list[i] = ir.NewStructKeyExpr(r.pos(), r.exoticField(), r.expr())
 	}
 	return list
 }
@@ -1544,3 +1749,120 @@ func builtinCall(pos src.XPos, op ir.Op) *ir.CallExpr {
 	}
 	return ir.NewCallExpr(pos, ir.OCALL, ir.NewIdent(base.Pos, types.BuiltinPkg.Lookup(ir.OpNames[op])), nil)
 }
+
+// NewIncompleteNamedType returns a TFORW type t with name specified by sym, such
+// that t.nod and sym.Def are set correctly.
+func NewIncompleteNamedType(pos src.XPos, sym *types.Sym) *types.Type {
+	name := ir.NewDeclNameAt(pos, ir.OTYPE, sym)
+	forw := types.NewNamed(name)
+	name.SetType(forw)
+	sym.Def = name
+	return forw
+}
+
+// Instantiate creates a new named type which is the instantiation of the base
+// named generic type, with the specified type args.
+func Instantiate(pos src.XPos, baseType *types.Type, targs []*types.Type) *types.Type {
+	baseSym := baseType.Sym()
+	if strings.Index(baseSym.Name, "[") >= 0 {
+		base.Fatalf("arg to Instantiate is not a base generic type")
+	}
+	name := InstTypeName(baseSym.Name, targs)
+	instSym := baseSym.Pkg.Lookup(name)
+	if instSym.Def != nil {
+		// May match existing type from previous import or
+		// types2-to-types1 conversion, or from in-progress instantiation
+		// in the current type import stack.
+		return instSym.Def.Type()
+	}
+
+	t := NewIncompleteNamedType(baseType.Pos(), instSym)
+	t.SetRParams(targs)
+	t.OrigSym = baseSym
+
+	// baseType may still be TFORW or its methods may not be fully filled in
+	// (since we are in the middle of importing it). So, delay call to
+	// substInstType until we get back up to the top of the current top-most
+	// type import.
+	deferredInstStack = append(deferredInstStack, t)
+
+	return t
+}
+
+var deferredInstStack []*types.Type
+var deferInst int
+
+// deferDoInst defers substitution on instantiated types until we are at the
+// top-most defined type, so the base types are fully defined.
+func deferDoInst() {
+	deferInst++
+}
+
+func resumeDoInst() {
+	if deferInst == 1 {
+		for len(deferredInstStack) > 0 {
+			t := deferredInstStack[0]
+			deferredInstStack = deferredInstStack[1:]
+			substInstType(t, t.OrigSym.Def.(*ir.Name).Type(), t.RParams())
+		}
+	}
+	deferInst--
+}
+
+// doInst creates a new instantiation type (which will be added to
+// deferredInstStack for completion later) for an incomplete type encountered
+// during a type substitution for an instantiation. This is needed for
+// instantiations of mutually recursive types.
+func doInst(t *types.Type) *types.Type {
+	return Instantiate(t.Pos(), t.OrigSym.Def.(*ir.Name).Type(), t.RParams())
+}
+
+// substInstType completes the instantiation of a generic type by doing a
+// substitution on the underlying type itself and any methods. t is the
+// instantiation being created, baseType is the base generic type, and targs are
+// the type arguments that baseType is being instantiated with.
+func substInstType(t *types.Type, baseType *types.Type, targs []*types.Type) {
+	subst := Tsubster{
+		Tparams:       baseType.RParams(),
+		Targs:         targs,
+		SubstForwFunc: doInst,
+	}
+	t.SetUnderlying(subst.Typ(baseType.Underlying()))
+
+	newfields := make([]*types.Field, baseType.Methods().Len())
+	for i, f := range baseType.Methods().Slice() {
+		if !f.IsMethod() || types.IsInterfaceMethod(f.Type) {
+			// Do a normal substitution if this is a non-method (which
+			// means this must be an interface used as a constraint) or
+			// an interface method.
+			t2 := subst.Typ(f.Type)
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+			continue
+		}
+		recvType := f.Type.Recv().Type
+		if recvType.IsPtr() {
+			recvType = recvType.Elem()
+		}
+		// Substitute in the method using the type params used in the
+		// method (not the type params in the definition of the generic type).
+		msubst := Tsubster{
+			Tparams:       recvType.RParams(),
+			Targs:         targs,
+			SubstForwFunc: doInst,
+		}
+		t2 := msubst.Typ(f.Type)
+		oldsym := f.Nname.Sym()
+		newsym := MakeFuncInstSym(oldsym, targs, true)
+		var nname *ir.Name
+		if newsym.Def != nil {
+			nname = newsym.Def.(*ir.Name)
+		} else {
+			nname = ir.NewNameAt(f.Pos, newsym)
+			nname.SetType(t2)
+			newsym.Def = nname
+		}
+		newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+		newfields[i].Nname = nname
+	}
+	t.Methods().Set(newfields)
+}
diff --git a/src/cmd/compile/internal/typecheck/stmt.go b/src/cmd/compile/internal/typecheck/stmt.go
index 922a01bfbe9aa7d6dea6ab34e03e5955ef883105..c322d490e5b2a07ac6524afd40900b182bd18392 100644
--- a/src/cmd/compile/internal/typecheck/stmt.go
+++ b/src/cmd/compile/internal/typecheck/stmt.go
@@ -172,6 +172,10 @@ assignOK:
 			r := r.(*ir.TypeAssertExpr)
 			stmt.SetOp(ir.OAS2DOTTYPE)
 			r.SetOp(ir.ODOTTYPE2)
+		case ir.ODYNAMICDOTTYPE:
+			r := r.(*ir.DynamicTypeAssertExpr)
+			stmt.SetOp(ir.OAS2DOTTYPE)
+			r.SetOp(ir.ODYNAMICDOTTYPE2)
 		default:
 			break assignOK
 		}
@@ -201,7 +205,6 @@ assignOK:
 		stmt := stmt.(*ir.AssignListStmt)
 		stmt.SetOp(ir.OAS2FUNC)
 		r := rhs[0].(*ir.CallExpr)
-		r.Use = ir.CallUseList
 		rtyp := r.Type()
 
 		mismatched := false
@@ -217,7 +220,7 @@ assignOK:
 			}
 		}
 		if mismatched && !failed {
-			rewriteMultiValueCall(stmt, r)
+			RewriteMultiValueCall(stmt, r)
 		}
 		return
 	}
@@ -237,6 +240,15 @@ func plural(n int) string {
 	return "s"
 }
 
+// tcCheckNil typechecks an OCHECKNIL node.
+func tcCheckNil(n *ir.UnaryExpr) ir.Node {
+	n.X = Expr(n.X)
+	if !n.X.Type().IsPtrShaped() {
+		base.FatalfAt(n.Pos(), "%L is not pointer shaped", n.X)
+	}
+	return n
+}
+
 // tcFor typechecks an OFOR node.
 func tcFor(n *ir.ForStmt) ir.Node {
 	Stmts(n.Init())
@@ -653,29 +665,18 @@ func tcSwitchType(n *ir.SwitchStmt) {
 }
 
 type typeSet struct {
-	m map[string][]typeSetEntry
-}
-
-type typeSetEntry struct {
-	pos src.XPos
-	typ *types.Type
+	m map[string]src.XPos
 }
 
 func (s *typeSet) add(pos src.XPos, typ *types.Type) {
 	if s.m == nil {
-		s.m = make(map[string][]typeSetEntry)
+		s.m = make(map[string]src.XPos)
 	}
 
-	// LongString does not uniquely identify types, so we need to
-	// disambiguate collisions with types.Identical.
-	// TODO(mdempsky): Add a method that *is* unique.
-	ls := typ.LongString()
-	prevs := s.m[ls]
-	for _, prev := range prevs {
-		if types.Identical(typ, prev.typ) {
-			base.ErrorfAt(pos, "duplicate case %v in type switch\n\tprevious case at %s", typ, base.FmtPos(prev.pos))
-			return
-		}
+	ls := typ.LinkString()
+	if prev, ok := s.m[ls]; ok {
+		base.ErrorfAt(pos, "duplicate case %v in type switch\n\tprevious case at %s", typ, base.FmtPos(prev))
+		return
 	}
-	s.m[ls] = append(prevs, typeSetEntry{pos, typ})
+	s.m[ls] = pos
 }
diff --git a/src/cmd/compile/internal/typecheck/subr.go b/src/cmd/compile/internal/typecheck/subr.go
index 9ee7a94b1f24af5bea061042a8d471c8c4758b69..7ae10ef40652d6e5116b7cc3890ccdfc435f7d73 100644
--- a/src/cmd/compile/internal/typecheck/subr.go
+++ b/src/cmd/compile/internal/typecheck/subr.go
@@ -5,6 +5,7 @@
 package typecheck
 
 import (
+	"bytes"
 	"fmt"
 	"sort"
 	"strconv"
@@ -352,9 +353,10 @@ func Assignop(src, dst *types.Type) (ir.Op, string) {
 		return ir.OCONVNOP, ""
 	}
 
-	// 2. src and dst have identical underlying types
-	// and either src or dst is not a named type or
-	// both are empty interface types.
+	// 2. src and dst have identical underlying types and
+	//   a. either src or dst is not a named type, or
+	//   b. both are empty interface types, or
+	//   c. at least one is a gcshape type.
 	// For assignable but different non-empty interface types,
 	// we want to recompute the itab. Recomputing the itab ensures
 	// that itabs are unique (thus an interface with a compile-time
@@ -371,21 +373,24 @@ func Assignop(src, dst *types.Type) (ir.Op, string) {
 			// which need to have their itab updated.
 			return ir.OCONVNOP, ""
 		}
+		if src.IsShape() || dst.IsShape() {
+			// Conversion between a shape type and one of the types
+			// it represents also needs no conversion.
+			return ir.OCONVNOP, ""
+		}
 	}
 
 	// 3. dst is an interface type and src implements dst.
 	if dst.IsInterface() && src.Kind() != types.TNIL {
 		var missing, have *types.Field
 		var ptr int
+		if src.IsShape() {
+			// Shape types implement things they have already
+			// been typechecked to implement, even if they
+			// don't have the methods for them.
+			return ir.OCONVIFACE, ""
+		}
 		if implements(src, dst, &missing, &have, &ptr) {
-			// Call NeedITab/ITabAddr so that (src, dst)
-			// gets added to itabs early, which allows
-			// us to de-virtualize calls through this
-			// type/interface pair later. See CompileITabs in reflect.go
-			if types.IsDirectIface(src) && !dst.IsEmptyInterface() {
-				NeedITab(src, dst)
-			}
-
 			return ir.OCONVIFACE, ""
 		}
 
@@ -722,13 +727,23 @@ func ifacelookdot(s *types.Sym, t *types.Type, ignorecase bool) (m *types.Field,
 	return m, followptr
 }
 
+// implements reports whether t implements the interface iface. t can be
+// an interface, a type parameter, or a concrete type. If implements returns
+// false, it stores a method of iface that is not implemented in *m. If the
+// method name matches but the type is wrong, it additionally stores the type
+// of the method (on t) in *samename.
 func implements(t, iface *types.Type, m, samename **types.Field, ptr *int) bool {
 	t0 := t
 	if t == nil {
 		return false
 	}
 
-	if t.IsInterface() {
+	if t.IsInterface() || t.IsTypeParam() {
+		if t.IsTypeParam() {
+			// A typeparam satisfies an interface if its type bound
+			// has all the methods of that interface.
+			t = t.Bound()
+		}
 		i := 0
 		tms := t.AllMethods().Slice()
 		for _, im := range iface.AllMethods().Slice() {
@@ -874,3 +889,504 @@ var slist []symlink
 type symlink struct {
 	field *types.Field
 }
+
+// TypesOf converts a list of nodes to a list
+// of types of those nodes.
+func TypesOf(x []ir.Node) []*types.Type {
+	r := make([]*types.Type, len(x))
+	for i, n := range x {
+		r[i] = n.Type()
+	}
+	return r
+}
+
+// addTargs writes out the targs to buffer b as a comma-separated list enclosed by
+// brackets.
+func addTargs(b *bytes.Buffer, targs []*types.Type) {
+	b.WriteByte('[')
+	for i, targ := range targs {
+		if i > 0 {
+			b.WriteByte(',')
+		}
+		// Use NameString(), which includes the package name for the local
+		// package, to make sure that type arguments (including type params),
+		// are uniquely specified.
+		tstring := targ.NameString()
+		// types1 uses "interface {" and types2 uses "interface{" - convert
+		// to consistent types2 format.  Same for "struct {"
+		tstring = strings.Replace(tstring, "interface {", "interface{", -1)
+		tstring = strings.Replace(tstring, "struct {", "struct{", -1)
+		b.WriteString(tstring)
+	}
+	b.WriteString("]")
+}
+
+// InstTypeName creates a name for an instantiated type, based on the name of the
+// generic type and the type args.
+func InstTypeName(name string, targs []*types.Type) string {
+	b := bytes.NewBufferString(name)
+	addTargs(b, targs)
+	return b.String()
+}
+
+// makeInstName1 returns the name of the generic function instantiated with the
+// given types, which can have type params or shapes, or be concrete types. name is
+// the name of the generic function or method.
+func makeInstName1(name string, targs []*types.Type, hasBrackets bool) string {
+	b := bytes.NewBufferString("")
+	i := strings.Index(name, "[")
+	assert(hasBrackets == (i >= 0))
+	if i >= 0 {
+		b.WriteString(name[0:i])
+	} else {
+		b.WriteString(name)
+	}
+	addTargs(b, targs)
+	if i >= 0 {
+		i2 := strings.LastIndex(name[i:], "]")
+		assert(i2 >= 0)
+		b.WriteString(name[i+i2+1:])
+	}
+	return b.String()
+}
+
+// MakeFuncInstSym makes the unique sym for a stenciled generic function or method,
+// based on the name of the function fnsym and the targs. It replaces any
+// existing bracket type list in the name. MakeInstName asserts that fnsym has
+// brackets in its name if and only if hasBrackets is true.
+//
+// Names of declared generic functions have no brackets originally, so hasBrackets
+// should be false. Names of generic methods already have brackets, since the new
+// type parameter is specified in the generic type of the receiver (e.g. func
+// (func (v *value[T]).set(...) { ... } has the original name (*value[T]).set.
+//
+// The standard naming is something like: 'genFn[int,bool]' for functions and
+// '(*genType[int,bool]).methodName' for methods
+func MakeFuncInstSym(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
+	return gf.Pkg.Lookup(makeInstName1(gf.Name, targs, hasBrackets))
+}
+
+func MakeDictSym(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
+	for _, targ := range targs {
+		if targ.HasTParam() {
+			fmt.Printf("FUNCTION %s\n", gf.Name)
+			for _, targ := range targs {
+				fmt.Printf("  PARAM %+v\n", targ)
+			}
+			panic("dictionary should always have concrete type args")
+		}
+	}
+	name := makeInstName1(gf.Name, targs, hasBrackets)
+	name = ".dict." + name
+	return gf.Pkg.Lookup(name)
+}
+
+func assert(p bool) {
+	base.Assert(p)
+}
+
+// General type substituter, for replacing typeparams with type args.
+type Tsubster struct {
+	Tparams []*types.Type
+	Targs   []*types.Type
+	// If non-nil, the substitution map from name nodes in the generic function to the
+	// name nodes in the new stenciled function.
+	Vars map[*ir.Name]*ir.Name
+	// New fully-instantiated generic types whose methods should be instantiated.
+	InstTypeList []*types.Type
+	// If non-nil, function to substitute an incomplete (TFORW) type.
+	SubstForwFunc func(*types.Type) *types.Type
+}
+
+// Typ computes the type obtained by substituting any type parameter in t with the
+// corresponding type argument in subst. If t contains no type parameters, the
+// result is t; otherwise the result is a new type. It deals with recursive types
+// by using TFORW types and finding partially or fully created types via sym.Def.
+func (ts *Tsubster) Typ(t *types.Type) *types.Type {
+	if !t.HasTParam() && t.Kind() != types.TFUNC {
+		// Note: function types need to be copied regardless, as the
+		// types of closures may contain declarations that need
+		// to be copied. See #45738.
+		return t
+	}
+
+	if t.IsTypeParam() {
+		for i, tp := range ts.Tparams {
+			if tp == t {
+				return ts.Targs[i]
+			}
+		}
+		// If t is a simple typeparam T, then t has the name/symbol 'T'
+		// and t.Underlying() == t.
+		//
+		// However, consider the type definition: 'type P[T any] T'. We
+		// might use this definition so we can have a variant of type T
+		// that we can add new methods to. Suppose t is a reference to
+		// P[T]. t has the name 'P[T]', but its kind is TTYPEPARAM,
+		// because P[T] is defined as T. If we look at t.Underlying(), it
+		// is different, because the name of t.Underlying() is 'T' rather
+		// than 'P[T]'. But the kind of t.Underlying() is also TTYPEPARAM.
+		// In this case, we do the needed recursive substitution in the
+		// case statement below.
+		if t.Underlying() == t {
+			// t is a simple typeparam that didn't match anything in tparam
+			return t
+		}
+		// t is a more complex typeparam (e.g. P[T], as above, whose
+		// definition is just T).
+		assert(t.Sym() != nil)
+	}
+
+	var newsym *types.Sym
+	var neededTargs []*types.Type
+	var targsChanged bool
+	var forw *types.Type
+
+	if t.Sym() != nil {
+		// Translate the type params for this type according to
+		// the tparam/targs mapping from subst.
+		neededTargs = make([]*types.Type, len(t.RParams()))
+		for i, rparam := range t.RParams() {
+			neededTargs[i] = ts.Typ(rparam)
+			if !types.Identical(neededTargs[i], rparam) {
+				targsChanged = true
+			}
+		}
+		// For a named (defined) type, we have to change the name of the
+		// type as well. We do this first, so we can look up if we've
+		// already seen this type during this substitution or other
+		// definitions/substitutions.
+		genName := genericTypeName(t.Sym())
+		newsym = t.Sym().Pkg.Lookup(InstTypeName(genName, neededTargs))
+		if newsym.Def != nil {
+			// We've already created this instantiated defined type.
+			return newsym.Def.Type()
+		}
+
+		// In order to deal with recursive generic types, create a TFORW
+		// type initially and set the Def field of its sym, so it can be
+		// found if this type appears recursively within the type.
+		forw = NewIncompleteNamedType(t.Pos(), newsym)
+		//println("Creating new type by sub", newsym.Name, forw.HasTParam())
+		forw.SetRParams(neededTargs)
+		// Copy the OrigSym from the re-instantiated type (which is the sym of
+		// the base generic type).
+		assert(t.OrigSym != nil)
+		forw.OrigSym = t.OrigSym
+	}
+
+	var newt *types.Type
+
+	switch t.Kind() {
+	case types.TTYPEPARAM:
+		if t.Sym() == newsym && !targsChanged {
+			// The substitution did not change the type.
+			return t
+		}
+		// Substitute the underlying typeparam (e.g. T in P[T], see
+		// the example describing type P[T] above).
+		newt = ts.Typ(t.Underlying())
+		assert(newt != t)
+
+	case types.TARRAY:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewArray(newelem, t.NumElem())
+		}
+
+	case types.TPTR:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewPtr(newelem)
+		}
+
+	case types.TSLICE:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewSlice(newelem)
+		}
+
+	case types.TSTRUCT:
+		newt = ts.tstruct(t, targsChanged)
+		if newt == t {
+			newt = nil
+		}
+
+	case types.TFUNC:
+		newrecvs := ts.tstruct(t.Recvs(), false)
+		newparams := ts.tstruct(t.Params(), false)
+		newresults := ts.tstruct(t.Results(), false)
+		// Translate the tparams of a signature.
+		newtparams := ts.tstruct(t.TParams(), false)
+		if newrecvs != t.Recvs() || newparams != t.Params() ||
+			newresults != t.Results() || newtparams != t.TParams() || targsChanged {
+			// If any types have changed, then the all the fields of
+			// of recv, params, and results must be copied, because they have
+			// offset fields that are dependent, and so must have an
+			// independent copy for each new signature.
+			var newrecv *types.Field
+			if newrecvs.NumFields() > 0 {
+				if newrecvs == t.Recvs() {
+					newrecvs = ts.tstruct(t.Recvs(), true)
+				}
+				newrecv = newrecvs.Field(0)
+			}
+			if newparams == t.Params() {
+				newparams = ts.tstruct(t.Params(), true)
+			}
+			if newresults == t.Results() {
+				newresults = ts.tstruct(t.Results(), true)
+			}
+			var tparamfields []*types.Field
+			if newtparams.HasTParam() {
+				tparamfields = newtparams.FieldSlice()
+			} else {
+				// Completely remove the tparams from the resulting
+				// signature, if the tparams are now concrete types.
+				tparamfields = nil
+			}
+			newt = types.NewSignature(t.Pkg(), newrecv, tparamfields,
+				newparams.FieldSlice(), newresults.FieldSlice())
+		}
+
+	case types.TINTER:
+		newt = ts.tinter(t)
+		if newt == t && !targsChanged {
+			newt = nil
+		}
+
+	case types.TMAP:
+		newkey := ts.Typ(t.Key())
+		newval := ts.Typ(t.Elem())
+		if newkey != t.Key() || newval != t.Elem() || targsChanged {
+			newt = types.NewMap(newkey, newval)
+		}
+
+	case types.TCHAN:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewChan(newelem, t.ChanDir())
+			if !newt.HasTParam() {
+				// TODO(danscales): not sure why I have to do this
+				// only for channels.....
+				types.CheckSize(newt)
+			}
+		}
+	case types.TFORW:
+		if ts.SubstForwFunc != nil {
+			newt = ts.SubstForwFunc(t)
+		} else {
+			assert(false)
+		}
+	case types.TINT, types.TINT8, types.TINT16, types.TINT32, types.TINT64,
+		types.TUINT, types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64,
+		types.TUINTPTR, types.TBOOL, types.TSTRING, types.TFLOAT32, types.TFLOAT64, types.TCOMPLEX64, types.TCOMPLEX128:
+		newt = t.Underlying()
+	case types.TUNION:
+		nt := t.NumTerms()
+		newterms := make([]*types.Type, nt)
+		tildes := make([]bool, nt)
+		changed := false
+		for i := 0; i < nt; i++ {
+			term, tilde := t.Term(i)
+			tildes[i] = tilde
+			newterms[i] = ts.Typ(term)
+			if newterms[i] != term {
+				changed = true
+			}
+		}
+		if changed {
+			newt = types.NewUnion(newterms, tildes)
+		}
+	default:
+		panic(fmt.Sprintf("Bad type in (*TSubster).Typ: %v", t.Kind()))
+	}
+	if newt == nil {
+		// Even though there were typeparams in the type, there may be no
+		// change if this is a function type for a function call (which will
+		// have its own tparams/targs in the function instantiation).
+		return t
+	}
+
+	if t.Sym() == nil && t.Kind() != types.TINTER {
+		// Not a named type or interface type, so there was no forwarding type
+		// and there are no methods to substitute.
+		assert(t.Methods().Len() == 0)
+		return newt
+	}
+
+	if forw != nil {
+		forw.SetUnderlying(newt)
+		newt = forw
+	}
+
+	if t.Kind() != types.TINTER && t.Methods().Len() > 0 {
+		// Fill in the method info for the new type.
+		var newfields []*types.Field
+		newfields = make([]*types.Field, t.Methods().Len())
+		for i, f := range t.Methods().Slice() {
+			t2 := ts.Typ(f.Type)
+			oldsym := f.Nname.Sym()
+			newsym := MakeFuncInstSym(oldsym, ts.Targs, true)
+			var nname *ir.Name
+			if newsym.Def != nil {
+				nname = newsym.Def.(*ir.Name)
+			} else {
+				nname = ir.NewNameAt(f.Pos, newsym)
+				nname.SetType(t2)
+				newsym.Def = nname
+			}
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+			newfields[i].Nname = nname
+		}
+		newt.Methods().Set(newfields)
+		if !newt.HasTParam() && !newt.HasShape() {
+			// Generate all the methods for a new fully-instantiated type.
+			ts.InstTypeList = append(ts.InstTypeList, newt)
+		}
+	}
+	return newt
+}
+
+// tstruct substitutes type params in types of the fields of a structure type. For
+// each field, tstruct copies the Nname, and translates it if Nname is in
+// ts.vars. To always force the creation of a new (top-level) struct,
+// regardless of whether anything changed with the types or names of the struct's
+// fields, set force to true.
+func (ts *Tsubster) tstruct(t *types.Type, force bool) *types.Type {
+	if t.NumFields() == 0 {
+		if t.HasTParam() {
+			// For an empty struct, we need to return a new type,
+			// since it may now be fully instantiated (HasTParam
+			// becomes false).
+			return types.NewStruct(t.Pkg(), nil)
+		}
+		return t
+	}
+	var newfields []*types.Field
+	if force {
+		newfields = make([]*types.Field, t.NumFields())
+	}
+	for i, f := range t.Fields().Slice() {
+		t2 := ts.Typ(f.Type)
+		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
+			newfields = make([]*types.Field, t.NumFields())
+			for j := 0; j < i; j++ {
+				newfields[j] = t.Field(j)
+			}
+		}
+		if newfields != nil {
+			// TODO(danscales): make sure this works for the field
+			// names of embedded types (which should keep the name of
+			// the type param, not the instantiated type).
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+			newfields[i].Embedded = f.Embedded
+			if f.IsDDD() {
+				newfields[i].SetIsDDD(true)
+			}
+			if f.Nointerface() {
+				newfields[i].SetNointerface(true)
+			}
+			if f.Nname != nil && ts.Vars != nil {
+				v := ts.Vars[f.Nname.(*ir.Name)]
+				if v != nil {
+					// This is the case where we are
+					// translating the type of the function we
+					// are substituting, so its dcls are in
+					// the subst.ts.vars table, and we want to
+					// change to reference the new dcl.
+					newfields[i].Nname = v
+				} else {
+					// This is the case where we are
+					// translating the type of a function
+					// reference inside the function we are
+					// substituting, so we leave the Nname
+					// value as is.
+					newfields[i].Nname = f.Nname
+				}
+			}
+		}
+	}
+	if newfields != nil {
+		return types.NewStruct(t.Pkg(), newfields)
+	}
+	return t
+
+}
+
+// tinter substitutes type params in types of the methods of an interface type.
+func (ts *Tsubster) tinter(t *types.Type) *types.Type {
+	if t.Methods().Len() == 0 {
+		return t
+	}
+	var newfields []*types.Field
+	for i, f := range t.Methods().Slice() {
+		t2 := ts.Typ(f.Type)
+		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
+			newfields = make([]*types.Field, t.Methods().Len())
+			for j := 0; j < i; j++ {
+				newfields[j] = t.Methods().Index(j)
+			}
+		}
+		if newfields != nil {
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+		}
+	}
+	if newfields != nil {
+		return types.NewInterface(t.Pkg(), newfields)
+	}
+	return t
+}
+
+// genericSym returns the name of the base generic type for the type named by
+// sym. It simply returns the name obtained by removing everything after the
+// first bracket ("[").
+func genericTypeName(sym *types.Sym) string {
+	return sym.Name[0:strings.Index(sym.Name, "[")]
+}
+
+// Shapify takes a concrete type and returns a GCshape type that can
+// be used in place of the input type and still generate identical code.
+// No methods are added - all methods calls directly on a shape should
+// be done by converting to an interface using the dictionary.
+//
+// TODO: this could take the generic function and base its decisions
+// on how that generic function uses this type argument. For instance,
+// if it doesn't use it as a function argument/return value, then
+// we don't need to distinguish int64 and float64 (because they only
+// differ in how they get passed as arguments). For now, we only
+// unify two different types if they are identical in every possible way.
+func Shapify(t *types.Type) *types.Type {
+	assert(!t.HasShape())
+	// Map all types with the same underlying type to the same shape.
+	u := t.Underlying()
+
+	// All pointers have the same shape.
+	// TODO: Make unsafe.Pointer the same shape as normal pointers.
+	if u.Kind() == types.TPTR {
+		u = types.Types[types.TUINT8].PtrTo()
+	}
+
+	if s := shaped[u]; s != nil {
+		return s
+	}
+
+	sym := shapePkg.Lookup(u.LinkString())
+	name := ir.NewDeclNameAt(u.Pos(), ir.OTYPE, sym)
+	s := types.NewNamed(name)
+	s.SetUnderlying(u)
+	s.SetIsShape(true)
+	s.SetHasShape(true)
+	name.SetType(s)
+	name.SetTypecheck(1)
+	shaped[u] = s
+	return s
+}
+
+var shaped = map[*types.Type]*types.Type{}
+
+var shapePkg = types.NewPkg(".shape", ".shape")
diff --git a/src/cmd/compile/internal/typecheck/syms.go b/src/cmd/compile/internal/typecheck/syms.go
index f29af82db2cc25670a60ef4192fd5623a4ee4806..ed3aaecc5a2a2a777cd748d22eca98f4b65f2ce1 100644
--- a/src/cmd/compile/internal/typecheck/syms.go
+++ b/src/cmd/compile/internal/typecheck/syms.go
@@ -75,9 +75,9 @@ func InitRuntime() {
 		typ := typs[d.typ]
 		switch d.tag {
 		case funcTag:
-			importfunc(ir.Pkgs.Runtime, src.NoXPos, sym, typ)
+			importfunc(src.NoXPos, sym, typ)
 		case varTag:
-			importvar(ir.Pkgs.Runtime, src.NoXPos, sym, typ)
+			importvar(src.NoXPos, sym, typ)
 		default:
 			base.Fatalf("unhandled declaration tag %v", d.tag)
 		}
diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/src/cmd/compile/internal/typecheck/typecheck.go
index 359f66236969fb4e34867ba35ea9d56b9480f5ba..db1b11c4cfd0a952a4aa22f1b4d3751381d25e19 100644
--- a/src/cmd/compile/internal/typecheck/typecheck.go
+++ b/src/cmd/compile/internal/typecheck/typecheck.go
@@ -13,6 +13,7 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
+	"cmd/internal/src"
 )
 
 // Function collecting autotmps generated during typechecking,
@@ -24,7 +25,6 @@ var inimport bool // set during import
 var TypecheckAllowed bool
 
 var (
-	NeedITab        = func(t, itype *types.Type) {}
 	NeedRuntimeType = func(*types.Type) {}
 )
 
@@ -35,18 +35,10 @@ func Stmt(n ir.Node) ir.Node       { return typecheck(n, ctxStmt) }
 func Exprs(exprs []ir.Node) { typecheckslice(exprs, ctxExpr) }
 func Stmts(stmts []ir.Node) { typecheckslice(stmts, ctxStmt) }
 
-func Call(call *ir.CallExpr) {
-	t := call.X.Type()
-	if t == nil {
-		panic("misuse of Call")
-	}
-	ctx := ctxStmt
-	if t.NumResults() > 0 {
-		ctx = ctxExpr | ctxMultiOK
-	}
-	if typecheck(call, ctx) != call {
-		panic("bad typecheck")
-	}
+func Call(pos src.XPos, callee ir.Node, args []ir.Node, dots bool) ir.Node {
+	call := ir.NewCallExpr(pos, ir.OCALL, callee, args)
+	call.IsDDD = dots
+	return typecheck(call, ctxStmt|ctxExpr)
 }
 
 func Callee(n ir.Node) ir.Node {
@@ -59,8 +51,8 @@ func FuncBody(n *ir.Func) {
 	Stmts(n.Body)
 	CheckUnused(n)
 	CheckReturn(n)
-	if base.Errors() > errorsBefore {
-		n.Body = nil // type errors; do not compile
+	if ir.IsBlank(n.Nname) || base.Errors() > errorsBefore {
+		n.Body = nil // blank function or type errors; do not compile
 	}
 }
 
@@ -777,6 +769,10 @@ func typecheck1(n ir.Node, top int) ir.Node {
 		n := n.(*ir.CallExpr)
 		return tcRecover(n)
 
+	case ir.ORECOVERFP:
+		n := n.(*ir.CallExpr)
+		return tcRecoverFP(n)
+
 	case ir.OUNSAFEADD:
 		n := n.(*ir.BinaryExpr)
 		return tcUnsafeAdd(n)
@@ -787,11 +783,7 @@ func typecheck1(n ir.Node, top int) ir.Node {
 
 	case ir.OCLOSURE:
 		n := n.(*ir.ClosureExpr)
-		tcClosure(n, top)
-		if n.Type() == nil {
-			return n
-		}
-		return n
+		return tcClosure(n, top)
 
 	case ir.OITAB:
 		n := n.(*ir.UnaryExpr)
@@ -814,6 +806,14 @@ func typecheck1(n ir.Node, top int) ir.Node {
 		n.SetType(types.Types[types.TUINTPTR])
 		return n
 
+	case ir.OGETCALLERPC, ir.OGETCALLERSP:
+		n := n.(*ir.CallExpr)
+		if len(n.Args) != 0 {
+			base.FatalfAt(n.Pos(), "unexpected arguments: %v", n)
+		}
+		n.SetType(types.Types[types.TUINTPTR])
+		return n
+
 	case ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
 		n.X = Expr(n.X)
@@ -881,6 +881,10 @@ func typecheck1(n ir.Node, top int) ir.Node {
 		n := n.(*ir.TailCallStmt)
 		return n
 
+	case ir.OCHECKNIL:
+		n := n.(*ir.UnaryExpr)
+		return tcCheckNil(n)
+
 	case ir.OSELECT:
 		tcSelect(n.(*ir.SelectStmt))
 		return n
@@ -951,12 +955,12 @@ func typecheckargs(n ir.InitNode) {
 	}
 
 	// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
-	rewriteMultiValueCall(n, list[0])
+	RewriteMultiValueCall(n, list[0])
 }
 
-// rewriteMultiValueCall rewrites multi-valued f() to use temporaries,
+// RewriteMultiValueCall rewrites multi-valued f() to use temporaries,
 // so the backend wouldn't need to worry about tuple-valued expressions.
-func rewriteMultiValueCall(n ir.InitNode, call ir.Node) {
+func RewriteMultiValueCall(n ir.InitNode, call ir.Node) {
 	// If we're outside of function context, then this call will
 	// be executed during the generated init function. However,
 	// init.go hasn't yet created it. Instead, associate the
@@ -1913,11 +1917,6 @@ func typecheckdef(n *ir.Name) {
 					n.SetDiag(true)
 					goto ret
 				}
-				// For package-level type aliases, set n.Sym.Def so we can identify
-				// it as a type alias during export. See also #31959.
-				if n.Curfn == nil {
-					n.Sym().Def = n.Ntype
-				}
 			}
 			break
 		}
diff --git a/src/cmd/compile/internal/typecheck/universe.go b/src/cmd/compile/internal/typecheck/universe.go
index de185ab94471d640c834341e2a38432ff43acc09..54f3c89c24544cff2d1ad345726e9e74b4573274 100644
--- a/src/cmd/compile/internal/typecheck/universe.go
+++ b/src/cmd/compile/internal/typecheck/universe.go
@@ -158,6 +158,15 @@ func InitUniverse() {
 	s.Def = n
 	types.CalcSize(types.ErrorType)
 
+	// comparable type (interface)
+	s = types.BuiltinPkg.Lookup("comparable")
+	n = ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, s)
+	types.ComparableType = types.NewNamed(n)
+	types.ComparableType.SetUnderlying(makeComparableInterface())
+	n.SetType(types.ComparableType)
+	s.Def = n
+	types.CalcSize(types.ComparableType)
+
 	types.Types[types.TUNSAFEPTR] = defBasic(types.TUNSAFEPTR, ir.Pkgs.Unsafe, "Pointer")
 
 	// simple aliases
@@ -338,6 +347,12 @@ func makeErrorInterface() *types.Type {
 	return types.NewInterface(types.NoPkg, []*types.Field{method})
 }
 
+func makeComparableInterface() *types.Type {
+	sig := types.NewSignature(types.NoPkg, fakeRecvField(), nil, nil, nil)
+	method := types.NewField(src.NoXPos, Lookup("=="), sig)
+	return types.NewInterface(types.NoPkg, []*types.Field{method})
+}
+
 // DeclareUniverse makes the universe block visible within the current package.
 func DeclareUniverse() {
 	// Operationally, this is similar to a dot import of builtinpkg, except
diff --git a/src/cmd/compile/internal/types/fmt.go b/src/cmd/compile/internal/types/fmt.go
index 8b988952a78d2c689714ddfe2d61260fcdb75e19..0824f6d0936161fdf126760284c613a1eb5f09fc 100644
--- a/src/cmd/compile/internal/types/fmt.go
+++ b/src/cmd/compile/internal/types/fmt.go
@@ -239,17 +239,37 @@ func (t *Type) String() string {
 	return tconv(t, 0, fmtGo)
 }
 
-// ShortString generates a short description of t.
-// It is used in autogenerated method names, reflection,
-// and itab names.
-func (t *Type) ShortString() string {
+// LinkString returns an unexpanded string description of t, suitable
+// for use in link symbols. "Unexpanded" here means that the
+// description uses `"".` to qualify identifiers from the current
+// package, and "expansion" refers to the renaming step performed by
+// the linker to replace these qualifiers with proper `path/to/pkg.`
+// qualifiers.
+//
+// After expansion, the description corresponds to type identity. That
+// is, for any pair of types t1 and t2, Identical(t1, t2) and
+// expand(t1.LinkString()) == expand(t2.LinkString()) report the same
+// value.
+//
+// Within a single compilation unit, LinkString always returns the
+// same unexpanded description for identical types. Thus it's safe to
+// use as a map key to implement a type-identity-keyed map. However,
+// make sure all LinkString calls used for this purpose happen within
+// the same compile process; the string keys are not stable across
+// multiple processes.
+func (t *Type) LinkString() string {
 	return tconv(t, 0, fmtTypeID)
 }
 
-// LongString generates a complete description of t.
-// It is useful for reflection,
-// or when a unique fingerprint or hash of a type is required.
-func (t *Type) LongString() string {
+// NameString generates a user-readable, mostly unique string
+// description of t. NameString always returns the same description
+// for identical types, even across compilation units.
+//
+// NameString qualifies identifiers by package name, so it has
+// collisions when different packages share the same names and
+// identifiers. It also does not distinguish function-scope defined
+// types from package-scoped defined types or from each other.
+func (t *Type) NameString() string {
 	return tconv(t, 0, fmtTypeIDName)
 }
 
@@ -316,31 +336,34 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 
 	// Unless the 'L' flag was specified, if the type has a name, just print that name.
 	if verb != 'L' && t.Sym() != nil && t != Types[t.Kind()] {
-		switch mode {
-		case fmtTypeID, fmtTypeIDName:
-			if verb == 'S' {
-				if t.Vargen != 0 {
-					sconv2(b, t.Sym(), 'S', mode)
-					fmt.Fprintf(b, "·%d", t.Vargen)
-					return
-				}
-				sconv2(b, t.Sym(), 'S', mode)
-				return
-			}
+		// Default to 'v' if verb is invalid.
+		if verb != 'S' {
+			verb = 'v'
+		}
 
-			if mode == fmtTypeIDName {
-				sconv2(b, t.Sym(), 'v', fmtTypeIDName)
-				return
+		// In unified IR, function-scope defined types will have a ·N
+		// suffix embedded directly in their Name. Trim this off for
+		// non-fmtTypeID modes.
+		sym := t.Sym()
+		if mode != fmtTypeID {
+			i := len(sym.Name)
+			for i > 0 && sym.Name[i-1] >= '0' && sym.Name[i-1] <= '9' {
+				i--
 			}
-
-			if t.Sym().Pkg == LocalPkg && t.Vargen != 0 {
-				sconv2(b, t.Sym(), 'v', mode)
-				fmt.Fprintf(b, "·%d", t.Vargen)
-				return
+			const dot = "·"
+			if i >= len(dot) && sym.Name[i-len(dot):i] == dot {
+				sym = &Sym{Pkg: sym.Pkg, Name: sym.Name[:i-len(dot)]}
 			}
 		}
-
-		sconv2(b, t.Sym(), 'v', mode)
+		sconv2(b, sym, verb, mode)
+
+		// TODO(mdempsky): Investigate including Vargen in fmtTypeIDName
+		// output too. It seems like it should, but that mode is currently
+		// used in string representation used by reflection, which is
+		// user-visible and doesn't expect this.
+		if mode == fmtTypeID && t.Vargen != 0 {
+			fmt.Fprintf(b, "·%d", t.Vargen)
+		}
 		return
 	}
 
@@ -567,6 +590,18 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 			b.WriteString(fmt.Sprintf("%p", t))
 		}
 
+	case TUNION:
+		for i := 0; i < t.NumTerms(); i++ {
+			if i > 0 {
+				b.WriteString("|")
+			}
+			elem, tilde := t.Term(i)
+			if tilde {
+				b.WriteString("~")
+			}
+			tconv2(b, elem, 0, mode, visited)
+		}
+
 	case Txxx:
 		b.WriteString("Txxx")
 
@@ -671,7 +706,7 @@ func FmtConst(v constant.Value, sharp bool) string {
 
 // TypeHash computes a hash value for type t to use in type switch statements.
 func TypeHash(t *Type) uint32 {
-	p := t.LongString()
+	p := t.NameString()
 
 	// Using MD5 is overkill, but reduces accidental collisions.
 	h := md5.Sum([]byte(p))
diff --git a/src/cmd/compile/internal/types/identity.go b/src/cmd/compile/internal/types/identity.go
index dde9f5185687ad6869d0961f85928df97e8a133b..2e9e2f4fd849e1e1d338be8543eccf550a6e0383 100644
--- a/src/cmd/compile/internal/types/identity.go
+++ b/src/cmd/compile/internal/types/identity.go
@@ -4,8 +4,11 @@
 
 package types
 
-// Identical reports whether t1 and t2 are identical types, following
-// the spec rules. Receiver parameter types are ignored.
+// Identical reports whether t1 and t2 are identical types, following the spec rules.
+// Receiver parameter types are ignored. Named (defined) types are only equal if they
+// are pointer-equal - i.e. there must be a unique types.Type for each specific named
+// type. Also, a type containing a shape type is considered identical to another type
+// (shape or not) if their underlying types are the same, or they are both pointers.
 func Identical(t1, t2 *Type) bool {
 	return identical(t1, t2, true, nil)
 }
@@ -29,6 +32,14 @@ func identical(t1, t2 *Type, cmpTags bool, assumedEqual map[typePair]struct{}) b
 		return false
 	}
 	if t1.sym != nil || t2.sym != nil {
+		if t1.HasShape() || t2.HasShape() {
+			switch t1.kind {
+			case TINT8, TUINT8, TINT16, TUINT16, TINT32, TUINT32, TINT64, TUINT64, TINT, TUINT, TUINTPTR, TCOMPLEX64, TCOMPLEX128, TFLOAT32, TFLOAT64, TBOOL, TSTRING, TPTR, TUNSAFEPTR:
+				return true
+			}
+			// fall through to unnamed type comparison for complex types.
+			goto cont
+		}
 		// Special case: we keep byte/uint8 and rune/int32
 		// separate for error messages. Treat them as equal.
 		switch t1.kind {
@@ -40,6 +51,7 @@ func identical(t1, t2 *Type, cmpTags bool, assumedEqual map[typePair]struct{}) b
 			return false
 		}
 	}
+cont:
 
 	// Any cyclic type must go through a named type, and if one is
 	// named, it is only identical to the other if they are the
diff --git a/src/cmd/compile/internal/types/kind_string.go b/src/cmd/compile/internal/types/kind_string.go
index ae24a58b9219d483b710e69af65ce892bf7759e8..3e6a8bc064edf4cf0306d959eda9d07ca05346a5 100644
--- a/src/cmd/compile/internal/types/kind_string.go
+++ b/src/cmd/compile/internal/types/kind_string.go
@@ -38,20 +38,21 @@ func _() {
 	_ = x[TSTRING-27]
 	_ = x[TUNSAFEPTR-28]
 	_ = x[TTYPEPARAM-29]
-	_ = x[TIDEAL-30]
-	_ = x[TNIL-31]
-	_ = x[TBLANK-32]
-	_ = x[TFUNCARGS-33]
-	_ = x[TCHANARGS-34]
-	_ = x[TSSA-35]
-	_ = x[TTUPLE-36]
-	_ = x[TRESULTS-37]
-	_ = x[NTYPE-38]
+	_ = x[TUNION-30]
+	_ = x[TIDEAL-31]
+	_ = x[TNIL-32]
+	_ = x[TBLANK-33]
+	_ = x[TFUNCARGS-34]
+	_ = x[TCHANARGS-35]
+	_ = x[TSSA-36]
+	_ = x[TTUPLE-37]
+	_ = x[TRESULTS-38]
+	_ = x[NTYPE-39]
 }
 
-const _Kind_name = "xxxINT8UINT8INT16UINT16INT32UINT32INT64UINT64INTUINTUINTPTRCOMPLEX64COMPLEX128FLOAT32FLOAT64BOOLPTRFUNCSLICEARRAYSTRUCTCHANMAPINTERFORWANYSTRINGUNSAFEPTRTYPEPARAMIDEALNILBLANKFUNCARGSCHANARGSSSATUPLERESULTSNTYPE"
+const _Kind_name = "xxxINT8UINT8INT16UINT16INT32UINT32INT64UINT64INTUINTUINTPTRCOMPLEX64COMPLEX128FLOAT32FLOAT64BOOLPTRFUNCSLICEARRAYSTRUCTCHANMAPINTERFORWANYSTRINGUNSAFEPTRTYPEPARAMUNIONIDEALNILBLANKFUNCARGSCHANARGSSSATUPLERESULTSNTYPE"
 
-var _Kind_index = [...]uint8{0, 3, 7, 12, 17, 23, 28, 34, 39, 45, 48, 52, 59, 68, 78, 85, 92, 96, 99, 103, 108, 113, 119, 123, 126, 131, 135, 138, 144, 153, 162, 167, 170, 175, 183, 191, 194, 199, 206, 211}
+var _Kind_index = [...]uint8{0, 3, 7, 12, 17, 23, 28, 34, 39, 45, 48, 52, 59, 68, 78, 85, 92, 96, 99, 103, 108, 113, 119, 123, 126, 131, 135, 138, 144, 153, 162, 167, 172, 175, 180, 188, 196, 199, 204, 211, 216}
 
 func (i Kind) String() string {
 	if i >= Kind(len(_Kind_index)-1) {
diff --git a/src/cmd/compile/internal/types/pkg.go b/src/cmd/compile/internal/types/pkg.go
index a6d2e2007b0424d4927ef5cda15fb67d94d27186..f63a357f0d092921835d7b31896777780a0eabcd 100644
--- a/src/cmd/compile/internal/types/pkg.go
+++ b/src/cmd/compile/internal/types/pkg.go
@@ -137,7 +137,3 @@ func CleanroomDo(f func()) {
 	f()
 	pkgMap = saved
 }
-
-func IsDotAlias(sym *Sym) bool {
-	return sym.Def != nil && sym.Def.Sym() != sym
-}
diff --git a/src/cmd/compile/internal/types/size.go b/src/cmd/compile/internal/types/size.go
index f0e695ab964ac532dbeb3ad2bfdcae2e1e8479c2..89391ade683af97f1faa2a547a40b3fc4feab83f 100644
--- a/src/cmd/compile/internal/types/size.go
+++ b/src/cmd/compile/internal/types/size.go
@@ -90,6 +90,26 @@ func expandiface(t *Type) {
 		methods = append(methods, m)
 	}
 
+	{
+		methods := t.Methods().Slice()
+		sort.SliceStable(methods, func(i, j int) bool {
+			mi, mj := methods[i], methods[j]
+
+			// Sort embedded types by type name (if any).
+			if mi.Sym == nil && mj.Sym == nil {
+				return mi.Type.Sym().Less(mj.Type.Sym())
+			}
+
+			// Sort methods before embedded types.
+			if mi.Sym == nil || mj.Sym == nil {
+				return mi.Sym != nil
+			}
+
+			// Sort methods by symbol name.
+			return mi.Sym.Less(mj.Sym)
+		})
+	}
+
 	for _, m := range t.Methods().Slice() {
 		if m.Sym == nil {
 			continue
@@ -104,8 +124,17 @@ func expandiface(t *Type) {
 			continue
 		}
 
+		if m.Type.IsUnion() {
+			continue
+		}
+
+		// In 1.18, embedded types can be anything. In Go 1.17, we disallow
+		// embedding anything other than interfaces.
 		if !m.Type.IsInterface() {
-			base.ErrorfAt(m.Pos, "interface contains embedded non-interface %v", m.Type)
+			if AllowsGoVersion(t.Pkg(), 1, 18) {
+				continue
+			}
+			base.ErrorfAt(m.Pos, "interface contains embedded non-interface, non-union %v", m.Type)
 			m.SetBroke(true)
 			t.SetBroke(true)
 			// Add to fields so that error messages
@@ -120,10 +149,15 @@ func expandiface(t *Type) {
 		// (including broken ones, if any) and add to t's
 		// method set.
 		for _, t1 := range m.Type.AllMethods().Slice() {
-			// Use m.Pos rather than t1.Pos to preserve embedding position.
 			f := NewField(m.Pos, t1.Sym, t1.Type)
 			addMethod(f, false)
+
+			// Clear position after typechecking, for consistency with types2.
+			f.Pos = src.NoXPos
 		}
+
+		// Clear position after typechecking, for consistency with types2.
+		m.Pos = src.NoXPos
 	}
 
 	sort.Sort(MethodsByName(methods))
@@ -405,6 +439,12 @@ func CalcSize(t *Type) {
 		t.Align = uint8(PtrSize)
 		expandiface(t)
 
+	case TUNION:
+		// Always part of an interface for now, so size/align don't matter.
+		// Pretend a union is represented like an interface.
+		w = 2 * int64(PtrSize)
+		t.Align = uint8(PtrSize)
+
 	case TCHAN: // implemented as pointer
 		w = int64(PtrSize)
 
diff --git a/src/cmd/compile/internal/types/sizeof_test.go b/src/cmd/compile/internal/types/sizeof_test.go
index 702893874214874080dfa1a148048303279050d9..7349e52a73e8499e9cc5e0fa48fe48c6125aa3f5 100644
--- a/src/cmd/compile/internal/types/sizeof_test.go
+++ b/src/cmd/compile/internal/types/sizeof_test.go
@@ -21,7 +21,7 @@ func TestSizeof(t *testing.T) {
 		_64bit uintptr     // size on 64bit platforms
 	}{
 		{Sym{}, 44, 72},
-		{Type{}, 60, 104},
+		{Type{}, 64, 112},
 		{Map{}, 20, 40},
 		{Forward{}, 20, 32},
 		{Func{}, 28, 48},
diff --git a/src/cmd/compile/internal/types/sort.go b/src/cmd/compile/internal/types/sort.go
index dc59b064153282cd0808a0fd3d2b4d51cd98680b..765c070cd94193c4c37db0f4415d1ee3ea06b031 100644
--- a/src/cmd/compile/internal/types/sort.go
+++ b/src/cmd/compile/internal/types/sort.go
@@ -4,11 +4,16 @@
 
 package types
 
-// MethodsByName sorts methods by symbol.
+// MethodsByName sorts methods by name.
 type MethodsByName []*Field
 
-func (x MethodsByName) Len() int { return len(x) }
+func (x MethodsByName) Len() int           { return len(x) }
+func (x MethodsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+func (x MethodsByName) Less(i, j int) bool { return x[i].Sym.Less(x[j].Sym) }
 
-func (x MethodsByName) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+// EmbeddedsByName sorts embedded types by name.
+type EmbeddedsByName []*Field
 
-func (x MethodsByName) Less(i, j int) bool { return x[i].Sym.Less(x[j].Sym) }
+func (x EmbeddedsByName) Len() int           { return len(x) }
+func (x EmbeddedsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+func (x EmbeddedsByName) Less(i, j int) bool { return x[i].Type.Sym().Less(x[j].Type.Sym()) }
diff --git a/src/cmd/compile/internal/types/sym.go b/src/cmd/compile/internal/types/sym.go
index 534cf7e2376d726e9d3cb3568de4b4d7c5ea9125..fb642f52f881418302738b26d3665f8d2040441f 100644
--- a/src/cmd/compile/internal/types/sym.go
+++ b/src/cmd/compile/internal/types/sym.go
@@ -110,6 +110,14 @@ func (a *Sym) Less(b *Sym) bool {
 		return false
 	}
 
+	// Nil before non-nil.
+	if a == nil {
+		return true
+	}
+	if b == nil {
+		return false
+	}
+
 	// Exported symbols before non-exported.
 	ea := IsExported(a.Name)
 	eb := IsExported(b.Name)
diff --git a/src/cmd/compile/internal/types/type.go b/src/cmd/compile/internal/types/type.go
index 1a9aa6916a2faca5a12a999226cea51cef0c4234..875b0ba82f1ec5407d3b7fd82063a55b09412b08 100644
--- a/src/cmd/compile/internal/types/type.go
+++ b/src/cmd/compile/internal/types/type.go
@@ -8,6 +8,7 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/internal/src"
 	"fmt"
+	"strings"
 	"sync"
 )
 
@@ -73,6 +74,7 @@ const (
 	TSTRING
 	TUNSAFEPTR
 	TTYPEPARAM
+	TUNION
 
 	// pseudo-types for literals
 	TIDEAL // untyped numeric constants
@@ -121,6 +123,8 @@ var (
 
 	// Predeclared error interface type.
 	ErrorType *Type
+	// Predeclared comparable interface type.
+	ComparableType *Type
 
 	// Types to represent untyped string and boolean constants.
 	UntypedString = New(TSTRING)
@@ -151,7 +155,7 @@ type Type struct {
 	// TARRAY: *Array
 	// TSLICE: Slice
 	// TSSA: string
-	// TTYPEPARAM:  *Interface (though we may not need to store/use the Interface info)
+	// TTYPEPARAM:  *Typeparam
 	Extra interface{}
 
 	// Width is the width of this Type in bytes.
@@ -182,12 +186,19 @@ type Type struct {
 	flags bitset8
 
 	// For defined (named) generic types, a pointer to the list of type params
-	// (in order) of this type that need to be instantiated. For
-	// fully-instantiated generic types, this is the targs used to instantiate
-	// them (which are used when generating the corresponding instantiated
-	// methods). rparams is only set for named types that are generic or are
-	// fully-instantiated from a generic type, and is otherwise set to nil.
+	// (in order) of this type that need to be instantiated. For instantiated
+	// generic types, this is the targs used to instantiate them. These targs
+	// may be typeparams (for re-instantiated types such as Value[T2]) or
+	// concrete types (for fully instantiated types such as Value[int]).
+	// rparams is only set for named types that are generic or are fully
+	// instantiated from a generic type, and is otherwise set to nil.
+	// TODO(danscales): choose a better name.
 	rparams *[]*Type
+
+	// For an instantiated generic type, the symbol for the base generic type.
+	// This backpointer is useful, because the base type is the type that has
+	// the method bodies.
+	OrigSym *Sym
 }
 
 func (*Type) CanBeAnSSAAux() {}
@@ -199,6 +210,8 @@ const (
 	typeDeferwidth             // width computation has been deferred and type is on deferredTypeStack
 	typeRecur
 	typeHasTParam // there is a typeparam somewhere in the type (generic function or type)
+	typeIsShape   // represents a set of closely related types, for generics
+	typeHasShape  // there is a shape somewhere in the type
 )
 
 func (t *Type) NotInHeap() bool  { return t.flags&typeNotInHeap != 0 }
@@ -207,13 +220,21 @@ func (t *Type) Noalg() bool      { return t.flags&typeNoalg != 0 }
 func (t *Type) Deferwidth() bool { return t.flags&typeDeferwidth != 0 }
 func (t *Type) Recur() bool      { return t.flags&typeRecur != 0 }
 func (t *Type) HasTParam() bool  { return t.flags&typeHasTParam != 0 }
+func (t *Type) IsShape() bool    { return t.flags&typeIsShape != 0 }
+func (t *Type) HasShape() bool   { return t.flags&typeHasShape != 0 }
 
 func (t *Type) SetNotInHeap(b bool)  { t.flags.set(typeNotInHeap, b) }
 func (t *Type) SetBroke(b bool)      { t.flags.set(typeBroke, b) }
 func (t *Type) SetNoalg(b bool)      { t.flags.set(typeNoalg, b) }
 func (t *Type) SetDeferwidth(b bool) { t.flags.set(typeDeferwidth, b) }
 func (t *Type) SetRecur(b bool)      { t.flags.set(typeRecur, b) }
-func (t *Type) SetHasTParam(b bool)  { t.flags.set(typeHasTParam, b) }
+
+// Generic types should never have alg functions.
+func (t *Type) SetHasTParam(b bool) { t.flags.set(typeHasTParam, b); t.flags.set(typeNoalg, b) }
+
+// Should always do SetHasShape(true) when doing SeIsShape(true).
+func (t *Type) SetIsShape(b bool)  { t.flags.set(typeIsShape, b) }
+func (t *Type) SetHasShape(b bool) { t.flags.set(typeHasShape, b) }
 
 // Kind returns the kind of type t.
 func (t *Type) Kind() Kind { return t.kind }
@@ -255,9 +276,6 @@ func (t *Type) SetRParams(rparams []*Type) {
 		base.Fatalf("Setting nil or zero-length rparams")
 	}
 	t.rparams = &rparams
-	if t.HasTParam() {
-		return
-	}
 	// HasTParam should be set if any rparam is or has a type param. This is
 	// to handle the case of a generic type which doesn't reference any of its
 	// type params (e.g. most commonly, an empty struct).
@@ -266,9 +284,33 @@ func (t *Type) SetRParams(rparams []*Type) {
 			t.SetHasTParam(true)
 			break
 		}
+		if rparam.HasShape() {
+			t.SetHasShape(true)
+			break
+		}
 	}
 }
 
+// IsBaseGeneric returns true if t is a generic type (not reinstantiated with
+// another type params or fully instantiated.
+func (t *Type) IsBaseGeneric() bool {
+	return len(t.RParams()) > 0 && strings.Index(t.Sym().Name, "[") < 0
+}
+
+// IsInstantiatedGeneric returns t if t ia generic type that has been
+// reinstantiated with new typeparams (i.e. is not fully instantiated).
+func (t *Type) IsInstantiatedGeneric() bool {
+	return len(t.RParams()) > 0 && strings.Index(t.Sym().Name, "[") >= 0 &&
+		t.HasTParam()
+}
+
+// IsFullyInstantiated reports whether t is a fully instantiated generic type; i.e. an
+// instantiated generic type where all type arguments are non-generic or fully
+// instantiated generic types.
+func (t *Type) IsFullyInstantiated() bool {
+	return len(t.RParams()) > 0 && !t.HasTParam()
+}
+
 // NoPkg is a nil *Pkg value for clarity.
 // It's intended for use when constructing types that aren't exported
 // and thus don't need to be associated with any package.
@@ -377,6 +419,18 @@ type Interface struct {
 	pkg *Pkg
 }
 
+// Typeparam contains Type fields specific to typeparam types.
+type Typeparam struct {
+	index int // type parameter index in source order, starting at 0
+	bound *Type
+}
+
+// Union contains Type fields specific to union types.
+type Union struct {
+	terms  []*Type
+	tildes []bool // whether terms[i] is of form ~T
+}
+
 // Ptr contains Type fields specific to pointer types.
 type Ptr struct {
 	Elem *Type // element type
@@ -558,7 +612,9 @@ func New(et Kind) *Type {
 	case TRESULTS:
 		t.Extra = new(Results)
 	case TTYPEPARAM:
-		t.Extra = new(Interface)
+		t.Extra = new(Typeparam)
+	case TUNION:
+		t.Extra = new(Union)
 	}
 	return t
 }
@@ -574,6 +630,9 @@ func NewArray(elem *Type, bound int64) *Type {
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -592,6 +651,9 @@ func NewSlice(elem *Type) *Type {
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -604,6 +666,9 @@ func NewChan(elem *Type, dir ChanDir) *Type {
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -614,6 +679,9 @@ func NewTuple(t1, t2 *Type) *Type {
 	if t1.HasTParam() || t2.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if t1.HasShape() || t2.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -645,6 +713,9 @@ func NewMap(k, v *Type) *Type {
 	if k.HasTParam() || v.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if k.HasShape() || v.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -669,6 +740,9 @@ func NewPtr(elem *Type) *Type {
 			// when this entry was cached.
 			t.SetHasTParam(true)
 		}
+		if elem.HasShape() {
+			t.SetHasShape(true)
+		}
 		return t
 	}
 
@@ -682,6 +756,9 @@ func NewPtr(elem *Type) *Type {
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -825,6 +902,8 @@ func (t *Type) copy() *Type {
 	case TARRAY:
 		x := *t.Extra.(*Array)
 		nt.Extra = &x
+	case TTYPEPARAM:
+		base.Fatalf("typeparam types cannot be copied")
 	case TTUPLE, TSSA, TRESULTS:
 		base.Fatalf("ssa types cannot be copied")
 	}
@@ -925,7 +1004,7 @@ func (t *Type) FuncArgs() *Type {
 	return t.Extra.(FuncArgs).T
 }
 
-// IsFuncArgStruct reports whether t is a struct representing function parameters.
+// IsFuncArgStruct reports whether t is a struct representing function parameters or results.
 func (t *Type) IsFuncArgStruct() bool {
 	return t.kind == TSTRUCT && t.Extra.(*Struct).Funarg != FunargNone
 }
@@ -1436,6 +1515,14 @@ func (t *Type) IsInterface() bool {
 	return t.kind == TINTER
 }
 
+func (t *Type) IsUnion() bool {
+	return t.kind == TUNION
+}
+
+func (t *Type) IsTypeParam() bool {
+	return t.kind == TTYPEPARAM
+}
+
 // IsEmptyInterface reports whether t is an empty interface type.
 func (t *Type) IsEmptyInterface() bool {
 	return t.IsInterface() && t.AllMethods().Len() == 0
@@ -1708,6 +1795,9 @@ func (t *Type) SetUnderlying(underlying *Type) {
 	if underlying.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if underlying.HasShape() {
+		t.SetHasShape(true)
+	}
 
 	// spec: "The declared type does not inherit any methods bound
 	// to the existing type, but the method set of an interface
@@ -1739,6 +1829,15 @@ func fieldsHasTParam(fields []*Field) bool {
 	return false
 }
 
+func fieldsHasShape(fields []*Field) bool {
+	for _, f := range fields {
+		if f.Type != nil && f.Type.HasShape() {
+			return true
+		}
+	}
+	return false
+}
+
 // NewBasic returns a new basic type of the given kind.
 func NewBasic(kind Kind, obj Object) *Type {
 	t := New(kind)
@@ -1758,6 +1857,10 @@ func NewInterface(pkg *Pkg, methods []*Field) *Type {
 			t.SetHasTParam(true)
 			break
 		}
+		if f.Type != nil && f.Type.HasShape() {
+			t.SetHasShape(true)
+			break
+		}
 	}
 	if anyBroke(methods) {
 		t.SetBroke(true)
@@ -1766,14 +1869,75 @@ func NewInterface(pkg *Pkg, methods []*Field) *Type {
 	return t
 }
 
-// NewTypeParam returns a new type param.
-func NewTypeParam(pkg *Pkg) *Type {
+// NewTypeParam returns a new type param with the specified sym (package and name)
+// and specified index within the typeparam list.
+func NewTypeParam(sym *Sym, index int) *Type {
 	t := New(TTYPEPARAM)
-	t.Extra.(*Interface).pkg = pkg
+	t.sym = sym
+	t.Extra.(*Typeparam).index = index
 	t.SetHasTParam(true)
 	return t
 }
 
+// Index returns the index of the type param within its param list.
+func (t *Type) Index() int {
+	t.wantEtype(TTYPEPARAM)
+	return t.Extra.(*Typeparam).index
+}
+
+// SetIndex sets the index of the type param within its param list.
+func (t *Type) SetIndex(i int) {
+	t.wantEtype(TTYPEPARAM)
+	t.Extra.(*Typeparam).index = i
+}
+
+// SetBound sets the bound of a typeparam.
+func (t *Type) SetBound(bound *Type) {
+	t.wantEtype(TTYPEPARAM)
+	t.Extra.(*Typeparam).bound = bound
+}
+
+// Bound returns the bound of a typeparam.
+func (t *Type) Bound() *Type {
+	t.wantEtype(TTYPEPARAM)
+	return t.Extra.(*Typeparam).bound
+}
+
+// NewUnion returns a new union with the specified set of terms (types). If
+// tildes[i] is true, then terms[i] represents ~T, rather than just T.
+func NewUnion(terms []*Type, tildes []bool) *Type {
+	t := New(TUNION)
+	if len(terms) != len(tildes) {
+		base.Fatalf("Mismatched terms and tildes for NewUnion")
+	}
+	t.Extra.(*Union).terms = terms
+	t.Extra.(*Union).tildes = tildes
+	nt := len(terms)
+	for i := 0; i < nt; i++ {
+		if terms[i].HasTParam() {
+			t.SetHasTParam(true)
+		}
+		if terms[i].HasShape() {
+			t.SetHasShape(true)
+		}
+	}
+	return t
+}
+
+// NumTerms returns the number of terms in a union type.
+func (t *Type) NumTerms() int {
+	t.wantEtype(TUNION)
+	return len(t.Extra.(*Union).terms)
+}
+
+// Term returns ith term of a union type as (term, tilde). If tilde is true, term
+// represents ~T, rather than just T.
+func (t *Type) Term(i int) (*Type, bool) {
+	t.wantEtype(TUNION)
+	u := t.Extra.(*Union)
+	return u.terms[i], u.tildes[i]
+}
+
 const BOGUS_FUNARG_OFFSET = -1000000000
 
 func unzeroFieldOffsets(f []*Field) {
@@ -1817,6 +1981,9 @@ func NewSignature(pkg *Pkg, recv *Field, tparams, params, results []*Field) *Typ
 		fieldsHasTParam(results) {
 		t.SetHasTParam(true)
 	}
+	if fieldsHasShape(recvs) || fieldsHasShape(params) || fieldsHasShape(results) {
+		t.SetHasShape(true)
+	}
 
 	return t
 }
@@ -1832,6 +1999,9 @@ func NewStruct(pkg *Pkg, fields []*Field) *Type {
 	if fieldsHasTParam(fields) {
 		t.SetHasTParam(true)
 	}
+	if fieldsHasShape(fields) {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -2028,7 +2198,7 @@ func TypeSymLookup(name string) *Sym {
 }
 
 func TypeSymName(t *Type) string {
-	name := t.ShortString()
+	name := t.LinkString()
 	// Use a separate symbol name for Noalg types for #17752.
 	if TypeHasNoAlg(t) {
 		name = "noalg." + name
diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index 2939dcc0bdf27356ae1c5a99abfd44c836004060..b2938b84da1e6abfd9a06734a2139fc7fdfd0f0c 100644
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -55,6 +55,18 @@ func (err Error) FullError() string {
 	return fmt.Sprintf("%s: %s", err.Pos, err.Full)
 }
 
+// An ArgumentError holds an error that is associated with an argument.
+type ArgumentError struct {
+	index int
+	error
+}
+
+// Index returns the positional index of the argument associated with the
+// error.
+func (e ArgumentError) Index() int {
+	return e.index
+}
+
 // An Importer resolves import paths to Packages.
 //
 // CAUTION: This interface does not support the import of locally
@@ -125,6 +137,12 @@ type Config struct {
 	// TODO(gri) Consolidate error messages and remove this flag.
 	CompilerErrorMessages bool
 
+	// If AllowTypeLists is set, the type list syntax is permitted
+	// in an interface in addition to the type set syntax.
+	// TODO(gri) Remove once type lists are no longer supported by
+	//           the parser.
+	AllowTypeLists bool
+
 	// If go115UsesCgo is set, the type checker expects the
 	// _cgo_gotypes.go file generated by running cmd/cgo to be
 	// provided as a package source file. Qualified identifiers
@@ -355,7 +373,7 @@ func (tv TypeAndValue) HasOk() bool {
 // Inferred reports the inferred type arguments and signature
 // for a parameterized function call that uses type inference.
 type Inferred struct {
-	Targs []Type
+	TArgs *TypeList
 	Sig   *Signature
 }
 
@@ -424,11 +442,11 @@ func Implements(V Type, T *Interface) bool {
 // Identical reports whether x and y are identical types.
 // Receivers of Signature types are ignored.
 func Identical(x, y Type) bool {
-	return (*Checker)(nil).identical(x, y)
+	return identical(x, y, true, nil)
 }
 
 // IdenticalIgnoreTags reports whether x and y are identical types if tags are ignored.
 // Receivers of Signature types are ignored.
 func IdenticalIgnoreTags(x, y Type) bool {
-	return (*Checker)(nil).identicalIgnoreTags(x, y)
+	return identical(x, y, false, nil)
 }
diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index 873390c1e9280d6b961ad02592e52e16f39096c3..039a6c0e5e7ffe1344bdd411dfc407a4ebdd04ce 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -17,10 +17,6 @@ import (
 	. "cmd/compile/internal/types2"
 )
 
-func unimplemented() {
-	panic("unimplemented")
-}
-
 // genericPkg is a source prefix for packages that contain generic code.
 const genericPkg = "package generic_"
 
@@ -329,27 +325,29 @@ func TestTypesInfo(t *testing.T) {
 		{brokenPkg + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string]invalid type`},
 
 		// parameterized functions
-		{genericPkg + `p0; func f[T any](T); var _ = f[int]`, `f`, `func[T₁ interface{}](T₁)`},
-		{genericPkg + `p1; func f[T any](T); var _ = f[int]`, `f[int]`, `func(int)`},
-		{genericPkg + `p2; func f[T any](T); func _() { f(42) }`, `f`, `func[T₁ interface{}](T₁)`},
-		{genericPkg + `p3; func f[T any](T); func _() { f(42) }`, `f(42)`, `()`},
+		{genericPkg + `p0; func f[T any](T) {}; var _ = f[int]`, `f`, `func[generic_p0.T₁ interface{}](generic_p0.T₁)`},
+		{genericPkg + `p1; func f[T any](T) {}; var _ = f[int]`, `f[int]`, `func(int)`},
+		{genericPkg + `p2; func f[T any](T) {}; func _() { f(42) }`, `f`, `func[generic_p2.T₁ interface{}](generic_p2.T₁)`},
+		{genericPkg + `p3; func f[T any](T) {}; func _() { f(42) }`, `f(42)`, `()`},
 
 		// type parameters
 		{genericPkg + `t0; type t[] int; var _ t`, `t`, `generic_t0.t`}, // t[] is a syntax error that is ignored in this test in favor of t
-		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[P₁ interface{}]`},
-		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[P₁ interface{}]`},
-		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[P₁, Q₂ interface{}]`},
-		{brokenPkg + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t[P₁, Q₂ interface{m()}]`},
+		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[generic_t1.P₁ interface{}]`},
+		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[generic_t2.P₁ interface{}]`},
+		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[generic_t3.P₁, generic_t3.Q₂ interface{}]`},
+		{brokenPkg + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t[broken_t4.P₁, broken_t4.Q₂ interface{m()}]`},
 
 		// instantiated types must be sanitized
 		{genericPkg + `g0; type t[P any] int; var x struct{ f t[int] }; var _ = x.f`, `x.f`, `generic_g0.t[int]`},
 
 		// issue 45096
-		{genericPkg + `issue45096; func _[T interface{ type int8, int16, int32  }](x T) { _ = x < 0 }`, `0`, `T₁`},
+		{genericPkg + `issue45096; func _[T interface{ ~int8 | ~int16 | ~int32 }](x T) { _ = x < 0 }`, `0`, `generic_issue45096.T₁`},
+
+		// issue 47895
+		{`package p; import "unsafe"; type S struct { f int }; var s S; var _ = unsafe.Offsetof(s.f)`, `s.f`, `int`},
 	}
 
 	for _, test := range tests {
-		ResetId() // avoid renumbering of type parameter ids when adding tests
 		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, brokenPkg) {
@@ -390,60 +388,60 @@ func TestInferredInfo(t *testing.T) {
 		targs []string
 		sig   string
 	}{
-		{genericPkg + `p0; func f[T any](T); func _() { f(42) }`,
+		{genericPkg + `p0; func f[T any](T) {}; func _() { f(42) }`,
 			`f`,
 			[]string{`int`},
 			`func(int)`,
 		},
-		{genericPkg + `p1; func f[T any](T) T; func _() { f('@') }`,
+		{genericPkg + `p1; func f[T any](T) T { panic(0) }; func _() { f('@') }`,
 			`f`,
 			[]string{`rune`},
 			`func(rune) rune`,
 		},
-		{genericPkg + `p2; func f[T any](...T) T; func _() { f(0i) }`,
+		{genericPkg + `p2; func f[T any](...T) T { panic(0) }; func _() { f(0i) }`,
 			`f`,
 			[]string{`complex128`},
 			`func(...complex128) complex128`,
 		},
-		{genericPkg + `p3; func f[A, B, C any](A, *B, []C); func _() { f(1.2, new(string), []byte{}) }`,
+		{genericPkg + `p3; func f[A, B, C any](A, *B, []C) {}; func _() { f(1.2, new(string), []byte{}) }`,
 			`f`,
 			[]string{`float64`, `string`, `byte`},
 			`func(float64, *string, []byte)`,
 		},
-		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B); func _() { f(1.2, new(byte)) }`,
+		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
 			`f`,
 			[]string{`float64`, `byte`},
 			`func(float64, *byte, ...[]byte)`,
 		},
 
 		// we don't know how to translate these but we can type-check them
-		{genericPkg + `q0; type T struct{}; func (T) m[P any](P); func _(x T) { x.m(42) }`,
+		{genericPkg + `q0; type T struct{}; func (T) m[P any](P) {}; func _(x T) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(int)`,
 		},
-		{genericPkg + `q1; type T struct{}; func (T) m[P any](P) P; func _(x T) { x.m(42) }`,
+		{genericPkg + `q1; type T struct{}; func (T) m[P any](P) P { panic(0) }; func _(x T) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(int) int`,
 		},
-		{genericPkg + `q2; type T struct{}; func (T) m[P any](...P) P; func _(x T) { x.m(42) }`,
+		{genericPkg + `q2; type T struct{}; func (T) m[P any](...P) P { panic(0) }; func _(x T) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(...int) int`,
 		},
-		{genericPkg + `q3; type T struct{}; func (T) m[A, B, C any](A, *B, []C); func _(x T) { x.m(1.2, new(string), []byte{}) }`,
+		{genericPkg + `q3; type T struct{}; func (T) m[A, B, C any](A, *B, []C) {}; func _(x T) { x.m(1.2, new(string), []byte{}) }`,
 			`x.m`,
 			[]string{`float64`, `string`, `byte`},
 			`func(float64, *string, []byte)`,
 		},
-		{genericPkg + `q4; type T struct{}; func (T) m[A, B any](A, *B, ...[]B); func _(x T) { x.m(1.2, new(byte)) }`,
+		{genericPkg + `q4; type T struct{}; func (T) m[A, B any](A, *B, ...[]B) {}; func _(x T) { x.m(1.2, new(byte)) }`,
 			`x.m`,
 			[]string{`float64`, `byte`},
 			`func(float64, *byte, ...[]byte)`,
 		},
 
-		{genericPkg + `r0; type T[P any] struct{}; func (_ T[P]) m[Q any](Q); func _[P any](x T[P]) { x.m(42) }`,
+		{genericPkg + `r0; type T[P any] struct{}; func (_ T[P]) m[Q any](Q) {}; func _[P any](x T[P]) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(int)`,
@@ -455,38 +453,38 @@ func TestInferredInfo(t *testing.T) {
 		// 	`func(float64)`,
 		// },
 
-		{genericPkg + `s1; func f[T any, P interface{type *T}](x T); func _(x string) { f(x) }`,
+		{genericPkg + `s1; func f[T any, P interface{~*T}](x T) {}; func _(x string) { f(x) }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func(x string)`,
 		},
-		{genericPkg + `s2; func f[T any, P interface{type *T}](x []T); func _(x []int) { f(x) }`,
+		{genericPkg + `s2; func f[T any, P interface{~*T}](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `*int`},
 			`func(x []int)`,
 		},
-		{genericPkg + `s3; type C[T any] interface{type chan<- T}; func f[T any, P C[T]](x []T); func _(x []int) { f(x) }`,
+		{genericPkg + `s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`},
 			`func(x []int)`,
 		},
-		{genericPkg + `s4; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T); func _(x []int) { f(x) }`,
+		{genericPkg + `s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func(x []int)`,
 		},
 
-		{genericPkg + `t1; func f[T any, P interface{type *T}]() T; func _() { _ = f[string] }`,
+		{genericPkg + `t1; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = f[string] }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func() string`,
 		},
-		{genericPkg + `t2; type C[T any] interface{type chan<- T}; func f[T any, P C[T]]() []T; func _() { _ = f[int] }`,
+		{genericPkg + `t2; type C[T any] interface{~chan<- T}; func f[T any, P C[T]]() []T { return nil }; func _() { _ = f[int] }`,
 			`f`,
 			[]string{`int`, `chan<- int`},
 			`func() []int`,
 		},
-		{genericPkg + `t3; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T; func _() { _ = f[int] }`,
+		{genericPkg + `t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func() []int`,
@@ -502,7 +500,7 @@ func TestInferredInfo(t *testing.T) {
 		}
 
 		// look for inferred type arguments and signature
-		var targs []Type
+		var targs *TypeList
 		var sig *Signature
 		for call, inf := range info.Inferred {
 			var fun syntax.Expr
@@ -515,7 +513,7 @@ func TestInferredInfo(t *testing.T) {
 				panic(fmt.Sprintf("unexpected call expression type %T", call))
 			}
 			if syntax.String(fun) == test.fun {
-				targs = inf.Targs
+				targs = inf.TArgs
 				sig = inf.Sig
 				break
 			}
@@ -526,11 +524,12 @@ func TestInferredInfo(t *testing.T) {
 		}
 
 		// check that type arguments are correct
-		if len(targs) != len(test.targs) {
-			t.Errorf("package %s: got %d type arguments; want %d", name, len(targs), len(test.targs))
+		if targs.Len() != len(test.targs) {
+			t.Errorf("package %s: got %d type arguments; want %d", name, targs.Len(), len(test.targs))
 			continue
 		}
-		for i, targ := range targs {
+		for i := 0; i < targs.Len(); i++ {
+			targ := targs.At(i)
 			if got := targ.String(); got != test.targs[i] {
 				t.Errorf("package %s, %d. type argument: got %s; want %s", name, i, got, test.targs[i])
 				continue
@@ -1166,8 +1165,6 @@ func (m testImporter) Import(path string) (*Package, error) {
 }
 
 func TestSelection(t *testing.T) {
-	t.Skip("requires fixes around source positions")
-
 	selections := make(map[*syntax.SelectorExpr]*Selection)
 
 	imports := make(testImporter)
@@ -1291,11 +1288,9 @@ func main() {
 	for e, sel := range selections {
 		_ = sel.String() // assertion: must not panic
 
-		unimplemented()
-		_ = e
-		// start := fset.Position(e.Pos()).Offset
-		// end := fset.Position(e.End()).Offset
-		// syntax := mainSrc[start:end] // (all SelectorExprs are in main, not lib)
+		start := indexFor(mainSrc, syntax.StartPos(e))
+		end := indexFor(mainSrc, syntax.EndPos(e))
+		segment := mainSrc[start:end] // (all SelectorExprs are in main, not lib)
 
 		direct := "."
 		if sel.Indirect() {
@@ -1305,13 +1300,11 @@ func main() {
 			sel.String(),
 			fmt.Sprintf("%s%v", direct, sel.Index()),
 		}
-		unimplemented()
-		_ = got
-		// want := wantOut[syntax]
-		// if want != got {
-		// 	t.Errorf("%s: got %q; want %q", syntax, got, want)
-		// }
-		// delete(wantOut, syntax)
+		want := wantOut[segment]
+		if want != got {
+			t.Errorf("%s: got %q; want %q", segment, got, want)
+		}
+		delete(wantOut, segment)
 
 		// We must explicitly assert properties of the
 		// Signature's receiver since it doesn't participate
@@ -1321,19 +1314,31 @@ func main() {
 			got := sig.Recv().Type()
 			want := sel.Recv()
 			if !Identical(got, want) {
-				unimplemented()
-				// t.Errorf("%s: Recv() = %s, want %s", syntax, got, want)
+				t.Errorf("%s: Recv() = %s, want %s", segment, got, want)
 			}
 		} else if sig != nil && sig.Recv() != nil {
 			t.Errorf("%s: signature has receiver %s", sig, sig.Recv().Type())
 		}
 	}
 	// Assert that all wantOut entries were used exactly once.
-	for syntax := range wantOut {
-		t.Errorf("no syntax.Selection found with syntax %q", syntax)
+	for segment := range wantOut {
+		t.Errorf("no syntax.Selection found with syntax %q", segment)
 	}
 }
 
+// indexFor returns the index into s corresponding to the position pos.
+func indexFor(s string, pos syntax.Pos) int {
+	i, line := 0, 1 // string index and corresponding line
+	target := int(pos.Line())
+	for line < target && i < len(s) {
+		if s[i] == '\n' {
+			line++
+		}
+		i++
+	}
+	return i + int(pos.Col()-1) // columns are 1-based
+}
+
 func TestIssue8518(t *testing.T) {
 	imports := make(testImporter)
 	conf := Config{
@@ -1568,6 +1573,14 @@ func F(){
 	}
 }
 
+var nopos syntax.Pos
+
+// newDefined creates a new defined type named T with the given underlying type.
+func newDefined(underlying Type) *Named {
+	tname := NewTypeName(nopos, nil, "T", nil)
+	return NewNamed(tname, underlying, nil)
+}
+
 func TestConvertibleTo(t *testing.T) {
 	for _, test := range []struct {
 		v, t Type
@@ -1847,3 +1860,88 @@ func f(x T) T { return foo.F(x) }
 		}
 	}
 }
+
+func TestInstantiate(t *testing.T) {
+	// eventually we like more tests but this is a start
+	const src = genericPkg + "p; type T[P any] *T[P]"
+	pkg, err := pkgFor(".", src, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// type T should have one type parameter
+	T := pkg.Scope().Lookup("T").Type().(*Named)
+	if n := T.TParams().Len(); n != 1 {
+		t.Fatalf("expected 1 type parameter; found %d", n)
+	}
+
+	// instantiation should succeed (no endless recursion)
+	// even with a nil *Checker
+	res, err := Instantiate(nil, T, []Type{Typ[Int]}, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// instantiated type should point to itself
+	if p := res.Underlying().(*Pointer).Elem(); p != res {
+		t.Fatalf("unexpected result type: %s points to %s", res, p)
+	}
+}
+
+func TestInstantiateErrors(t *testing.T) {
+	tests := []struct {
+		src    string // by convention, T must be the type being instantiated
+		targs  []Type
+		wantAt int // -1 indicates no error
+	}{
+		{"type T[P interface{~string}] int", []Type{Typ[Int]}, 0},
+		{"type T[P1 interface{int}, P2 interface{~string}] int", []Type{Typ[Int], Typ[Int]}, 1},
+		{"type T[P1 any, P2 interface{~[]P1}] int", []Type{Typ[Int], NewSlice(Typ[String])}, 1},
+		{"type T[P1 interface{~[]P2}, P2 any] int", []Type{NewSlice(Typ[String]), Typ[Int]}, 0},
+	}
+
+	for _, test := range tests {
+		src := genericPkg + "p; " + test.src
+		pkg, err := pkgFor(".", src, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		T := pkg.Scope().Lookup("T").Type().(*Named)
+
+		_, err = Instantiate(nil, T, test.targs, true)
+		if err == nil {
+			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
+		}
+
+		gotAt := err.(ArgumentError).Index()
+		if gotAt != test.wantAt {
+			t.Errorf("Instantate(%v, %v): error at index %d, want index %d", T, test.targs, gotAt, test.wantAt)
+		}
+	}
+}
+
+func TestInstanceIdentity(t *testing.T) {
+	imports := make(testImporter)
+	conf := Config{Importer: imports}
+	makePkg := func(src string) {
+		f, err := parseSrc("", src)
+		if err != nil {
+			t.Fatal(err)
+		}
+		name := f.PkgName.Value
+		pkg, err := conf.Check(name, []*syntax.File{f}, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		imports[name] = pkg
+	}
+	makePkg(genericPkg + `lib; type T[P any] struct{}`)
+	makePkg(genericPkg + `a; import "generic_lib"; var A generic_lib.T[int]`)
+	makePkg(genericPkg + `b; import "generic_lib"; var B generic_lib.T[int]`)
+	a := imports["generic_a"].Scope().Lookup("A")
+	b := imports["generic_b"].Scope().Lookup("B")
+	if !Identical(a.Type(), b.Type()) {
+		t.Errorf("mismatching types: a.A: %s, b.B: %s", a.Type(), b.Type())
+	}
+}
diff --git a/src/cmd/compile/internal/types2/array.go b/src/cmd/compile/internal/types2/array.go
new file mode 100644
index 0000000000000000000000000000000000000000..502d49bc25770f7bdcb3f03ba89652e64318b3c8
--- /dev/null
+++ b/src/cmd/compile/internal/types2/array.go
@@ -0,0 +1,25 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// An Array represents an array type.
+type Array struct {
+	len  int64
+	elem Type
+}
+
+// NewArray returns a new array type for the given element type and length.
+// A negative length indicates an unknown length.
+func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
+
+// Len returns the length of array a.
+// A negative result indicates an unknown length.
+func (a *Array) Len() int64 { return a.len }
+
+// Elem returns element type of array a.
+func (a *Array) Elem() Type { return a.elem }
+
+func (a *Array) Underlying() Type { return a }
+func (a *Array) String() string   { return TypeString(a, nil) }
diff --git a/src/cmd/compile/internal/types2/assignments.go b/src/cmd/compile/internal/types2/assignments.go
index 583118c8b235c5e6ac6a419e97add3e402c1cd47..6184fc2ea506c1c4d29ec292211095e7177d3041 100644
--- a/src/cmd/compile/internal/types2/assignments.go
+++ b/src/cmd/compile/internal/types2/assignments.go
@@ -68,7 +68,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 	// x.typ is typed
 
 	// A generic (non-instantiated) function value cannot be assigned to a variable.
-	if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+	if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 		check.errorf(x, "cannot use generic function %s without instantiation in %s", x, context)
 	}
 
diff --git a/src/cmd/compile/internal/types2/basic.go b/src/cmd/compile/internal/types2/basic.go
new file mode 100644
index 0000000000000000000000000000000000000000..2fd973cafbc5e66022c8455e9073237e15de2c64
--- /dev/null
+++ b/src/cmd/compile/internal/types2/basic.go
@@ -0,0 +1,82 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// BasicKind describes the kind of basic type.
+type BasicKind int
+
+const (
+	Invalid BasicKind = iota // type is invalid
+
+	// predeclared types
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	String
+	UnsafePointer
+
+	// types for untyped values
+	UntypedBool
+	UntypedInt
+	UntypedRune
+	UntypedFloat
+	UntypedComplex
+	UntypedString
+	UntypedNil
+
+	// aliases
+	Byte = Uint8
+	Rune = Int32
+)
+
+// BasicInfo is a set of flags describing properties of a basic type.
+type BasicInfo int
+
+// Properties of basic types.
+const (
+	IsBoolean BasicInfo = 1 << iota
+	IsInteger
+	IsUnsigned
+	IsFloat
+	IsComplex
+	IsString
+	IsUntyped
+
+	IsOrdered   = IsInteger | IsFloat | IsString
+	IsNumeric   = IsInteger | IsFloat | IsComplex
+	IsConstType = IsBoolean | IsNumeric | IsString
+)
+
+// A Basic represents a basic type.
+type Basic struct {
+	kind BasicKind
+	info BasicInfo
+	name string
+}
+
+// Kind returns the kind of basic type b.
+func (b *Basic) Kind() BasicKind { return b.kind }
+
+// Info returns information about properties of basic type b.
+func (b *Basic) Info() BasicInfo { return b.info }
+
+// Name returns the name of basic type b.
+func (b *Basic) Name() string { return b.name }
+
+func (b *Basic) Underlying() Type { return b }
+func (b *Basic) String() string   { return TypeString(b, nil) }
diff --git a/src/cmd/compile/internal/types2/builtins.go b/src/cmd/compile/internal/types2/builtins.go
index f90e06f226791ddb7630c8b5c6d79788378bf486..87295fe0e709bc9580c74942348432fb4332ed84 100644
--- a/src/cmd/compile/internal/types2/builtins.go
+++ b/src/cmd/compile/internal/types2/builtins.go
@@ -46,7 +46,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 	default:
 		// make argument getter
 		xlist, _ := check.exprList(call.ArgList, false)
-		arg = func(x *operand, i int) { *x = *xlist[i]; x.typ = expand(x.typ) }
+		arg = func(x *operand, i int) { *x = *xlist[i] }
 		nargs = len(xlist)
 		// evaluate first argument, if present
 		if nargs > 0 {
@@ -144,7 +144,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		mode := invalid
 		var typ Type
 		var val constant.Value
-		switch typ = implicitArrayDeref(optype(x.typ)); t := typ.(type) {
+		switch typ = arrayPtrDeref(under(x.typ)); t := typ.(type) {
 		case *Basic:
 			if isString(t) && id == _Len {
 				if x.mode == constant_ {
@@ -178,9 +178,9 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 				mode = value
 			}
 
-		case *Sum:
-			if t.is(func(t Type) bool {
-				switch t := under(t).(type) {
+		case *TypeParam:
+			if t.underIs(func(t Type) bool {
+				switch t := arrayPtrDeref(t).(type) {
 				case *Basic:
 					if isString(t) && id == _Len {
 						return true
@@ -212,19 +212,23 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 	case _Close:
 		// close(c)
-		c := asChan(x.typ)
-		if c == nil {
-			check.errorf(x, invalidArg+"%s is not a channel", x)
-			return
-		}
-		if c.dir == RecvOnly {
-			check.errorf(x, invalidArg+"%s must not be a receive-only channel", x)
+		if !underIs(x.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.errorf(x, invalidOp+"cannot close non-channel %s", x)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.errorf(x, invalidOp+"cannot close receive-only channel %s", x)
+				return false
+			}
+			return true
+		}) {
 			return
 		}
-
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, c))
+			check.recordBuiltinType(call.Fun, makeSig(nil, x.typ))
 		}
 
 	case _Complex:
@@ -281,7 +285,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		// both argument types must be identical
-		if !check.identical(x.typ, y.typ) {
+		if !Identical(x.typ, y.typ) {
 			check.errorf(x, invalidOp+"%v (mismatched types %s and %s)", call, x.typ, y.typ)
 			return
 		}
@@ -332,13 +336,15 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			return
 		}
 		var src Type
-		switch t := optype(y.typ).(type) {
+		switch t := under(y.typ).(type) {
 		case *Basic:
 			if isString(y.typ) {
 				src = universeByte
 			}
 		case *Slice:
 			src = t.elem
+		case *TypeParam:
+			check.error(x, "copy on generic operands not yet implemented")
 		}
 
 		if dst == nil || src == nil {
@@ -346,7 +352,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			return
 		}
 
-		if !check.identical(dst, src) {
+		if !Identical(dst, src) {
 			check.errorf(x, invalidArg+"arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
 			return
 		}
@@ -358,25 +364,40 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		x.typ = Typ[Int]
 
 	case _Delete:
-		// delete(m, k)
-		m := asMap(x.typ)
-		if m == nil {
-			check.errorf(x, invalidArg+"%s is not a map", x)
+		// delete(map_, key)
+		// map_ must be a map type or a type parameter describing map types.
+		// The key cannot be a type parameter for now.
+		map_ := x.typ
+		var key Type
+		if !underIs(map_, func(u Type) bool {
+			map_, _ := u.(*Map)
+			if map_ == nil {
+				check.errorf(x, invalidArg+"%s is not a map", x)
+				return false
+			}
+			if key != nil && !Identical(map_.key, key) {
+				check.errorf(x, invalidArg+"maps of %s must have identical key types", x)
+				return false
+			}
+			key = map_.key
+			return true
+		}) {
 			return
 		}
+
 		arg(x, 1) // k
 		if x.mode == invalid {
 			return
 		}
 
-		check.assignment(x, m.key, "argument to delete")
+		check.assignment(x, key, "argument to delete")
 		if x.mode == invalid {
 			return
 		}
 
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
+			check.recordBuiltinType(call.Fun, makeSig(nil, map_, key))
 		}
 
 	case _Imag, _Real:
@@ -451,39 +472,21 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			return
 		}
 
-		min, max := -1, 10
-		var valid func(t Type) bool
-		valid = func(t Type) bool {
-			var m int
-			switch t := optype(t).(type) {
-			case *Slice:
-				m = 2
-			case *Map, *Chan:
-				m = 1
-			case *Sum:
-				return t.is(valid)
-			default:
-				return false
-			}
-			if m > min {
-				min = m
-			}
-			if m+1 < max {
-				max = m + 1
-			}
-			return true
-		}
-
-		if !valid(T) {
+		var min int // minimum number of arguments
+		switch optype(T).(type) {
+		case *Slice:
+			min = 2
+		case *Map, *Chan:
+			min = 1
+		case *top:
+			check.errorf(arg0, invalidArg+"cannot make %s; type parameter has no structural type", arg0)
+			return
+		default:
 			check.errorf(arg0, invalidArg+"cannot make %s; type must be slice, map, or channel", arg0)
 			return
 		}
-		if nargs < min || max < nargs {
-			if min == max {
-				check.errorf(call, "%v expects %d arguments; found %d", call, min, nargs)
-			} else {
-				check.errorf(call, "%v expects %d or %d arguments; found %d", call, min, max, nargs)
-			}
+		if nargs < min || min+1 < nargs {
+			check.errorf(call, invalidOp+"%v expects %d or %d arguments; found %d", call, min, min+1, nargs)
 			return
 		}
 
@@ -603,19 +606,22 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 	case _Alignof:
 		// unsafe.Alignof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.errorf(call, invalidOp+"unsafe.Alignof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Alignof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Offsetof:
 		// unsafe.Offsetof(x T) uintptr, where x must be a selector
@@ -635,7 +641,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 		base := derefStructPtr(x.typ)
 		sel := selx.Sel.Value
-		obj, index, indirect := check.lookupFieldOrMethod(base, false, check.pkg, sel)
+		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
 		switch obj.(type) {
 		case nil:
 			check.errorf(x, invalidArg+"%s has no single field %s", base, sel)
@@ -653,30 +659,52 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			return
 		}
 
-		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
+		// TODO(gri) Should we pass x.typ instead of base (and have indirect report if derefStructPtr indirected)?
 		check.recordSelection(selx, FieldVal, base, obj, index, false)
 
-		offs := check.conf.offsetof(base, index)
-		x.mode = constant_
-		x.val = constant.MakeInt64(offs)
+		// record the selector expression (was bug - issue #47895)
+		{
+			mode := value
+			if x.mode == variable || indirect {
+				mode = variable
+			}
+			check.record(&operand{mode, selx, obj.Type(), nil, 0})
+		}
+
+		// The field offset is considered a variable even if the field is declared before
+		// the part of the struct which is variable-sized. This makes both the rules
+		// simpler and also permits (or at least doesn't prevent) a compiler from re-
+		// arranging struct fields if it wanted to.
+		if hasVarSize(base) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], obj.Type()))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.offsetof(base, index))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Sizeof:
 		// unsafe.Sizeof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.errorf(call, invalidOp+"unsafe.Sizeof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Sizeof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Slice:
 		// unsafe.Slice(ptr *T, len IntegerType) []T
@@ -748,6 +776,25 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 	return true
 }
 
+// hasVarSize reports if the size of type t is variable due to type parameters.
+func hasVarSize(t Type) bool {
+	switch t := under(t).(type) {
+	case *Array:
+		return hasVarSize(t.elem)
+	case *Struct:
+		for _, f := range t.fields {
+			if hasVarSize(f.typ) {
+				return true
+			}
+		}
+	case *TypeParam:
+		return true
+	case *Named, *Union, *top:
+		unreachable()
+	}
+	return false
+}
+
 // applyTypeFunc applies f to x. If x is a type parameter,
 // the result is a type parameter constrained by an new
 // interface bound. The type bounds for that interface
@@ -759,10 +806,10 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
 	if tp := asTypeParam(x); tp != nil {
 		// Test if t satisfies the requirements for the argument
 		// type and collect possible result types at the same time.
-		var rtypes []Type
-		if !tp.Bound().is(func(x Type) bool {
-			if r := f(x); r != nil {
-				rtypes = append(rtypes, r)
+		var terms []*Term
+		if !tp.iface().typeSet().is(func(t *term) bool {
+			if r := f(t.typ); r != nil {
+				terms = append(terms, NewTerm(t.tilde, r))
 				return true
 			}
 			return false
@@ -775,11 +822,12 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
 		//           uses of real() where the result is used to
 		//           define type and initialize a variable?
 
-		// construct a suitable new type parameter
-		tpar := NewTypeName(nopos, nil /* = Universe pkg */, "", nil)
-		ptyp := check.NewTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
-		tsum := NewSum(rtypes)
-		ptyp.bound = &Interface{types: tsum, allMethods: markComplete, allTypes: tsum}
+		// Construct a suitable new type parameter for the sum type. The
+		// type param is placed in the current package so export/import
+		// works as expected.
+		tpar := NewTypeName(nopos, check.pkg, "", nil)
+		ptyp := check.NewTypeParam(tpar, NewInterfaceType(nil, []Type{NewUnion(terms)})) // assigns type to tpar as a side-effect
+		ptyp.index = tp.index
 
 		return ptyp
 	}
@@ -803,10 +851,9 @@ func makeSig(res Type, args ...Type) *Signature {
 	return &Signature{params: params, results: result}
 }
 
-// implicitArrayDeref returns A if typ is of the form *A and A is an array;
+// arrayPtrDeref returns A if typ is of the form *A and A is an array;
 // otherwise it returns typ.
-//
-func implicitArrayDeref(typ Type) Type {
+func arrayPtrDeref(typ Type) Type {
 	if p, ok := typ.(*Pointer); ok {
 		if a := asArray(p.base); a != nil {
 			return a
diff --git a/src/cmd/compile/internal/types2/builtins_test.go b/src/cmd/compile/internal/types2/builtins_test.go
index 82c786b86ea20e5f8775d533b34d7cca8dadb3c1..52dbba1cb9810980fab197fee4e2b6d879085dc5 100644
--- a/src/cmd/compile/internal/types2/builtins_test.go
+++ b/src/cmd/compile/internal/types2/builtins_test.go
@@ -7,6 +7,7 @@ package types2_test
 import (
 	"cmd/compile/internal/syntax"
 	"fmt"
+	"strings"
 	"testing"
 
 	. "cmd/compile/internal/types2"
@@ -111,12 +112,15 @@ var builtinCalls = []struct {
 
 	{"Alignof", `_ = unsafe.Alignof(0)`, `invalid type`},                 // constant
 	{"Alignof", `var x struct{}; _ = unsafe.Alignof(x)`, `invalid type`}, // constant
+	{"Alignof", `var x P; _ = unsafe.Alignof(x)`, `func(p.P₁) uintptr`},
 
 	{"Offsetof", `var x struct{f bool}; _ = unsafe.Offsetof(x.f)`, `invalid type`},           // constant
 	{"Offsetof", `var x struct{_ int; f bool}; _ = unsafe.Offsetof((&x).f)`, `invalid type`}, // constant
+	{"Offsetof", `var x struct{_ int; f P}; _ = unsafe.Offsetof((&x).f)`, `func(p.P₁) uintptr`},
 
 	{"Sizeof", `_ = unsafe.Sizeof(0)`, `invalid type`},                 // constant
 	{"Sizeof", `var x struct{}; _ = unsafe.Sizeof(x)`, `invalid type`}, // constant
+	{"Sizeof", `var x P; _ = unsafe.Sizeof(x)`, `func(p.P₁) uintptr`},
 
 	{"Slice", `var p *int; _ = unsafe.Slice(p, 1)`, `func(*int, int) []int`},
 	{"Slice", `var p *byte; var n uintptr; _ = unsafe.Slice(p, n)`, `func(*byte, uintptr) []byte`},
@@ -149,9 +153,14 @@ func TestBuiltinSignatures(t *testing.T) {
 	}
 }
 
+func parseGenericSrc(path, src string) (*syntax.File, error) {
+	errh := func(error) {} // dummy error handler so that parsing continues in presence of errors
+	return syntax.Parse(syntax.NewFileBase(path), strings.NewReader(src), errh, nil, syntax.AllowGenerics)
+}
+
 func testBuiltinSignature(t *testing.T, name, src0, want string) {
-	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _() { %s }`, src0)
-	f, err := parseSrc("", src)
+	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _[P any]() { %s }`, src0)
+	f, err := parseGenericSrc("", src)
 	if err != nil {
 		t.Errorf("%s: %s", src0, err)
 		return
diff --git a/src/cmd/compile/internal/types2/call.go b/src/cmd/compile/internal/types2/call.go
index 6d149340b285b3e6bd8fc241e7dd5a50a8036370..538fdc0fb70ec4b3738e574e83582a9f36db0c91 100644
--- a/src/cmd/compile/internal/types2/call.go
+++ b/src/cmd/compile/internal/types2/call.go
@@ -26,7 +26,7 @@ func (check *Checker) funcInst(x *operand, inst *syntax.IndexExpr) {
 
 	// check number of type arguments (got) vs number of type parameters (want)
 	sig := x.typ.(*Signature)
-	got, want := len(targs), len(sig.tparams)
+	got, want := len(targs), sig.TParams().Len()
 	if !useConstraintTypeInference && got != want || got > want {
 		check.errorf(xlist[got-1], "got %d type arguments but want %d", got, want)
 		x.mode = invalid
@@ -37,7 +37,7 @@ func (check *Checker) funcInst(x *operand, inst *syntax.IndexExpr) {
 	// if we don't have enough type arguments, try type inference
 	inferred := false
 	if got < want {
-		targs = check.infer(inst.Pos(), sig.tparams, targs, nil, nil, true)
+		targs = check.infer(inst.Pos(), sig.TParams().list(), targs, nil, nil, true)
 		if targs == nil {
 			// error was already reported
 			x.mode = invalid
@@ -57,7 +57,7 @@ func (check *Checker) funcInst(x *operand, inst *syntax.IndexExpr) {
 
 	// instantiate function signature
 	res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
-	assert(res.tparams == nil) // signature is not generic anymore
+	assert(res.TParams().Len() == 0) // signature is not generic anymore
 	if inferred {
 		check.recordInferred(inst, targs, res)
 	}
@@ -99,7 +99,6 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 			check.expr(x, call.ArgList[0])
 			if x.mode != invalid {
 				if t := asInterface(T); t != nil {
-					check.completeInterface(nopos, t)
 					if t.IsConstraint() {
 						check.errorf(call, "cannot use interface %s in conversion (contains type list or is comparable)", T)
 						break
@@ -156,7 +155,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 		assert(len(targs) == len(xlist))
 
 		// check number of type arguments (got) vs number of type parameters (want)
-		got, want := len(targs), len(sig.tparams)
+		got, want := len(targs), sig.TParams().Len()
 		if got > want {
 			check.errorf(xlist[want], "got %d type arguments but want %d", got, want)
 			check.use(call.ArgList...)
@@ -190,7 +189,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 
 	// if type inference failed, a parametrized result must be invalidated
 	// (operands cannot have a parametrized type)
-	if x.mode == value && len(sig.tparams) > 0 && isParameterized(sig.tparams, x.typ) {
+	if x.mode == value && sig.TParams().Len() > 0 && isParameterized(sig.TParams().list(), x.typ) {
 		x.mode = invalid
 	}
 
@@ -318,24 +317,24 @@ func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []T
 	}
 
 	// infer type arguments and instantiate signature if necessary
-	if len(sig.tparams) > 0 {
+	if sig.TParams().Len() > 0 {
 		// TODO(gri) provide position information for targs so we can feed
 		//           it to the instantiate call for better error reporting
-		targs = check.infer(call.Pos(), sig.tparams, targs, sigParams, args, true)
+		targs := check.infer(call.Pos(), sig.TParams().list(), targs, sigParams, args, true)
 		if targs == nil {
 			return // error already reported
 		}
 
 		// compute result signature
 		rsig = check.instantiate(call.Pos(), sig, targs, nil).(*Signature)
-		assert(rsig.tparams == nil) // signature is not generic anymore
+		assert(rsig.TParams().Len() == 0) // signature is not generic anymore
 		check.recordInferred(call, targs, rsig)
 
 		// Optimization: Only if the parameter list was adjusted do we
 		// need to compute it from the adjusted list; otherwise we can
 		// simply use the result signature's parameter list.
 		if adjusted {
-			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.tparams, targs)).(*Tuple)
+			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.TParams().list(), targs), nil).(*Tuple)
 		} else {
 			sigParams = rsig.params
 		}
@@ -468,7 +467,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 
 	check.instantiatedOperand(x)
 
-	obj, index, indirect = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
+	obj, index, indirect = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
 	if obj == nil {
 		switch {
 		case index != nil:
@@ -480,11 +479,10 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 			var why string
 			if tpar := asTypeParam(x.typ); tpar != nil {
 				// Type parameter bounds don't specify fields, so don't mention "field".
-				switch obj := tpar.Bound().obj.(type) {
-				case nil:
+				if tname := tpar.iface().obj; tname != nil {
+					why = check.sprintf("interface %s has no method %s", tname.name, sel)
+				} else {
 					why = check.sprintf("type bound for %s has no method %s", x.typ, sel)
-				case *TypeName:
-					why = check.sprintf("interface %s has no method %s", obj.name, sel)
 				}
 			} else {
 				why = check.sprintf("type %s has no field or method %s", x.typ, sel)
@@ -498,7 +496,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 				} else {
 					changeCase = string(unicode.ToUpper(r)) + sel[1:]
 				}
-				if obj, _, _ = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
+				if obj, _, _ = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
 					why += ", but does have " + changeCase
 				}
 			}
@@ -518,7 +516,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 		// the signature accordingly.
 		// TODO(gri) factor this code out
 		sig := m.typ.(*Signature)
-		if len(sig.rparams) > 0 {
+		if sig.RParams().Len() > 0 {
 			// For inference to work, we must use the receiver type
 			// matching the receiver in the actual method declaration.
 			// If the method is embedded, the matching receiver is the
@@ -547,7 +545,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 			// the receiver type arguments here, the receiver must be be otherwise invalid
 			// and an error has been reported elsewhere.
 			arg := operand{mode: variable, expr: x.expr, typ: recv}
-			targs := check.infer(m.pos, sig.rparams, nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
+			targs := check.infer(m.pos, sig.RParams().list(), nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
 			//check.dump("### inferred targs = %s", targs)
 			if targs == nil {
 				// We may reach here if there were other errors (see issue #40056).
@@ -557,7 +555,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 			// (If we modify m, some tests will fail; possibly because the m is in use.)
 			// TODO(gri) investigate and provide a correct explanation here
 			copy := *m
-			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.rparams, targs))
+			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.RParams().list(), targs), nil)
 			obj = ©
 		}
 		// TODO(gri) we also need to do substitution for parameterized interface methods
@@ -576,17 +574,37 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 
 		check.recordSelection(e, MethodExpr, x.typ, m, index, indirect)
 
-		// the receiver type becomes the type of the first function
-		// argument of the method expression's function type
-		var params []*Var
 		sig := m.typ.(*Signature)
+		if sig.recv == nil {
+			check.error(e, "illegal cycle in method declaration")
+			goto Error
+		}
+
+		// The receiver type becomes the type of the first function
+		// argument of the method expression's function type.
+		var params []*Var
 		if sig.params != nil {
 			params = sig.params.vars
 		}
+		// Be consistent about named/unnamed parameters. This is not needed
+		// for type-checking, but the newly constructed signature may appear
+		// in an error message and then have mixed named/unnamed parameters.
+		// (An alternative would be to not print parameter names in errors,
+		// but it's useful to see them; this is cheap and method expressions
+		// are rare.)
+		name := ""
+		if len(params) > 0 && params[0].name != "" {
+			// name needed
+			name = sig.recv.name
+			if name == "" {
+				name = "_"
+			}
+		}
+		params = append([]*Var{NewVar(sig.recv.pos, sig.recv.pkg, name, x.typ)}, params...)
 		x.mode = value
 		x.typ = &Signature{
 			tparams:  sig.tparams,
-			params:   NewTuple(append([]*Var{NewVar(nopos, check.pkg, "_", x.typ)}, params...)...),
+			params:   NewTuple(params...),
 			results:  sig.results,
 			variadic: sig.variadic,
 		}
diff --git a/src/cmd/compile/internal/types2/chan.go b/src/cmd/compile/internal/types2/chan.go
new file mode 100644
index 0000000000000000000000000000000000000000..77650dfb09daad6b56df0138063676b381b84fcc
--- /dev/null
+++ b/src/cmd/compile/internal/types2/chan.go
@@ -0,0 +1,35 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Chan represents a channel type.
+type Chan struct {
+	dir  ChanDir
+	elem Type
+}
+
+// A ChanDir value indicates a channel direction.
+type ChanDir int
+
+// The direction of a channel is indicated by one of these constants.
+const (
+	SendRecv ChanDir = iota
+	SendOnly
+	RecvOnly
+)
+
+// NewChan returns a new channel type for the given direction and element type.
+func NewChan(dir ChanDir, elem Type) *Chan {
+	return &Chan{dir: dir, elem: elem}
+}
+
+// Dir returns the direction of channel c.
+func (c *Chan) Dir() ChanDir { return c.dir }
+
+// Elem returns the element type of channel c.
+func (c *Chan) Elem() Type { return c.elem }
+
+func (c *Chan) Underlying() Type { return c }
+func (c *Chan) String() string   { return TypeString(c, nil) }
diff --git a/src/cmd/compile/internal/types2/check.go b/src/cmd/compile/internal/types2/check.go
index 8d6cd1edab9d4c61cd1f1d5d7a99798def7fdcde..4226b4de82020a1739ef989407ef0d83538c54eb 100644
--- a/src/cmd/compile/internal/types2/check.go
+++ b/src/cmd/compile/internal/types2/check.go
@@ -71,7 +71,7 @@ type importKey struct {
 // A dotImportKey describes a dot-imported object in the given scope.
 type dotImportKey struct {
 	scope *Scope
-	obj   Object
+	name  string
 }
 
 // A Checker maintains the state of the type checker.
@@ -82,11 +82,11 @@ type Checker struct {
 	conf *Config
 	pkg  *Package
 	*Info
-	version version                     // accepted language version
-	objMap  map[Object]*declInfo        // maps package-level objects and (non-interface) methods to declaration info
-	impMap  map[importKey]*Package      // maps (import path, source directory) to (complete or fake) package
-	posMap  map[*Interface][]syntax.Pos // maps interface types to lists of embedded interface positions
-	typMap  map[string]*Named           // maps an instantiated named type hash to a *Named type
+	version version                // accepted language version
+	nextID  uint64                 // unique Id for type parameters (first valid Id is 1)
+	objMap  map[Object]*declInfo   // maps package-level objects and (non-interface) methods to declaration info
+	impMap  map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
+	typMap  map[string]*Named      // maps an instantiated named type hash to a *Named type
 
 	// pkgPathMap maps package names to the set of distinct import paths we've
 	// seen for that name, anywhere in the import graph. It is used for
@@ -188,7 +188,6 @@ func NewChecker(conf *Config, pkg *Package, info *Info) *Checker {
 		version: version,
 		objMap:  make(map[Object]*declInfo),
 		impMap:  make(map[importKey]*Package),
-		posMap:  make(map[*Interface][]syntax.Pos),
 		typMap:  make(map[string]*Named),
 	}
 }
@@ -283,11 +282,6 @@ func (check *Checker) checkFiles(files []*syntax.File) (err error) {
 	print("== recordUntyped ==")
 	check.recordUntyped()
 
-	if check.Info != nil {
-		print("== sanitizeInfo ==")
-		sanitizeInfo(check.Info)
-	}
-
 	check.pkg.complete = true
 
 	// no longer needed - release memory
@@ -422,7 +416,7 @@ func (check *Checker) recordInferred(call syntax.Expr, targs []Type, sig *Signat
 	assert(call != nil)
 	assert(sig != nil)
 	if m := check.Inferred; m != nil {
-		m[call] = Inferred{targs, sig}
+		m[call] = Inferred{NewTypeList(targs), sig}
 	}
 }
 
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index 30201e2b7f4232a147d17a2bdbc8cbb5bc301be3..6c26a4c4468d5688b9f7fc3ab1e106f38a461754 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -93,7 +93,7 @@ func (x *operand) convertibleTo(check *Checker, T Type) bool {
 	V := x.typ
 	Vu := under(V)
 	Tu := under(T)
-	if check.identicalIgnoreTags(Vu, Tu) {
+	if IdenticalIgnoreTags(Vu, Tu) {
 		return true
 	}
 
@@ -101,7 +101,7 @@ func (x *operand) convertibleTo(check *Checker, T Type) bool {
 	// have identical underlying types if tags are ignored"
 	if V, ok := V.(*Pointer); ok {
 		if T, ok := T.(*Pointer); ok {
-			if check.identicalIgnoreTags(under(V.base), under(T.base)) {
+			if IdenticalIgnoreTags(under(V.base), under(T.base)) {
 				return true
 			}
 		}
@@ -142,7 +142,7 @@ func (x *operand) convertibleTo(check *Checker, T Type) bool {
 	if s := asSlice(V); s != nil {
 		if p := asPointer(T); p != nil {
 			if a := asArray(p.Elem()); a != nil {
-				if check.identical(s.Elem(), a.Elem()) {
+				if Identical(s.Elem(), a.Elem()) {
 					if check == nil || check.allowVersion(check.pkg, 1, 17) {
 						return true
 					}
diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go
index 1333e4c0eca323c2725b8c24ea733d7919258ff6..342e1090de5ca5ba4682b5f3cc2acf0ca9f4b069 100644
--- a/src/cmd/compile/internal/types2/decl.go
+++ b/src/cmd/compile/internal/types2/decl.go
@@ -317,6 +317,8 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo {
 		}
 
 	case *Named:
+		t.expand(check.typMap)
+
 		// don't touch the type if it is from a different package or the Universe scope
 		// (doing so would lead to a race condition - was issue #35049)
 		if t.obj.pkg != check.pkg {
@@ -338,7 +340,7 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo {
 			// cycle detected
 			for i, tn := range path {
 				if t.obj.pkg != check.pkg {
-					panic("internal error: type cycle via package-external type")
+					panic("type cycle via package-external type")
 				}
 				if tn == t.obj {
 					check.cycleError(path[i:])
@@ -346,12 +348,9 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo {
 					return t.info
 				}
 			}
-			panic("internal error: cycle start not found")
+			panic("cycle start not found")
 		}
 		return t.info
-
-	case *instance:
-		return check.validType(t.expand(), path)
 	}
 
 	return valid
@@ -515,75 +514,6 @@ func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init syntax.Expr) {
 	check.initVars(lhs, []syntax.Expr{init}, nopos)
 }
 
-// under returns the expanded underlying type of n0; possibly by following
-// forward chains of named types. If an underlying type is found, resolve
-// the chain by setting the underlying type for each defined type in the
-// chain before returning it. If no underlying type is found or a cycle
-// is detected, the result is Typ[Invalid]. If a cycle is detected and
-// n0.check != nil, the cycle is reported.
-func (n0 *Named) under() Type {
-	u := n0.underlying
-	if u == nil {
-		return Typ[Invalid]
-	}
-
-	// If the underlying type of a defined type is not a defined
-	// type, then that is the desired underlying type.
-	n := asNamed(u)
-	if n == nil {
-		return u // common case
-	}
-
-	// Otherwise, follow the forward chain.
-	seen := map[*Named]int{n0: 0}
-	path := []Object{n0.obj}
-	for {
-		u = n.underlying
-		if u == nil {
-			u = Typ[Invalid]
-			break
-		}
-		n1 := asNamed(u)
-		if n1 == nil {
-			break // end of chain
-		}
-
-		seen[n] = len(seen)
-		path = append(path, n.obj)
-		n = n1
-
-		if i, ok := seen[n]; ok {
-			// cycle
-			// TODO(gri) revert this to a method on Checker. Having a possibly
-			// nil Checker on Named and TypeParam is too subtle.
-			if n0.check != nil {
-				n0.check.cycleError(path[i:])
-			}
-			u = Typ[Invalid]
-			break
-		}
-	}
-
-	for n := range seen {
-		// We should never have to update the underlying type of an imported type;
-		// those underlying types should have been resolved during the import.
-		// Also, doing so would lead to a race condition (was issue #31749).
-		// Do this check always, not just in debug more (it's cheap).
-		if n0.check != nil && n.obj.pkg != n0.check.pkg {
-			panic("internal error: imported type with unresolved underlying type")
-		}
-		n.underlying = u
-	}
-
-	return u
-}
-
-func (n *Named) setUnderlying(typ Type) {
-	if n != nil {
-		n.underlying = typ
-	}
-}
-
 func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named) {
 	assert(obj.typ == nil)
 
@@ -599,8 +529,8 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named
 		alias = false
 	}
 
+	// alias declaration
 	if alias {
-		// type alias declaration
 		if !check.allowVersion(check.pkg, 1, 9) {
 			if check.conf.CompilerErrorMessages {
 				check.error(tdecl, "type aliases only supported as of -lang=go1.9")
@@ -611,111 +541,94 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named
 
 		obj.typ = Typ[Invalid]
 		obj.typ = check.anyType(tdecl.Type)
+		return
+	}
 
-	} else {
-		// defined type declaration
-
-		named := check.newNamed(obj, nil, nil, nil, nil)
-		def.setUnderlying(named)
-
-		if tdecl.TParamList != nil {
-			check.openScope(tdecl, "type parameters")
-			defer check.closeScope()
-			named.tparams = check.collectTypeParams(tdecl.TParamList)
-		}
-
-		// determine underlying type of named
-		named.fromRHS = check.definedType(tdecl.Type, named)
+	// type definition or generic type declaration
+	named := check.newNamed(obj, nil, nil, nil, nil)
+	def.setUnderlying(named)
 
-		// The underlying type of named may be itself a named type that is
-		// incomplete:
-		//
-		//	type (
-		//		A B
-		//		B *C
-		//		C A
-		//	)
-		//
-		// The type of C is the (named) type of A which is incomplete,
-		// and which has as its underlying type the named type B.
-		// Determine the (final, unnamed) underlying type by resolving
-		// any forward chain.
-		// TODO(gri) Investigate if we can just use named.fromRHS here
-		//           and rely on lazy computation of the underlying type.
-		named.underlying = under(named)
+	if tdecl.TParamList != nil {
+		check.openScope(tdecl, "type parameters")
+		defer check.closeScope()
+		named.tparams = check.collectTypeParams(tdecl.TParamList)
 	}
 
+	// determine underlying type of named
+	named.fromRHS = check.definedType(tdecl.Type, named)
+	assert(named.fromRHS != nil)
+	// The underlying type of named may be itself a named type that is
+	// incomplete:
+	//
+	//	type (
+	//		A B
+	//		B *C
+	//		C A
+	//	)
+	//
+	// The type of C is the (named) type of A which is incomplete,
+	// and which has as its underlying type the named type B.
+	// Determine the (final, unnamed) underlying type by resolving
+	// any forward chain.
+	// TODO(gri) Investigate if we can just use named.fromRHS here
+	//           and rely on lazy computation of the underlying type.
+	named.underlying = under(named)
+
+	// If the RHS is a type parameter, it must be from this type declaration.
+	if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.TParams().list(), tpar) < 0 {
+		check.errorf(tdecl.Type, "cannot use function type parameter %s as RHS in type declaration", tpar)
+		named.underlying = Typ[Invalid]
+	}
 }
 
-func (check *Checker) collectTypeParams(list []*syntax.Field) (tparams []*TypeName) {
-	// Type parameter lists should not be empty. The parser will
-	// complain but we still may get an incorrect AST: ignore it.
-	if len(list) == 0 {
-		return
-	}
+func (check *Checker) collectTypeParams(list []*syntax.Field) *TParamList {
+	tparams := make([]*TypeParam, len(list))
 
-	// Declare type parameters up-front, with empty interface as type bound.
+	// Declare type parameters up-front.
 	// The scope of type parameters starts at the beginning of the type parameter
-	// list (so we can have mutually recursive parameterized interfaces).
-	for _, f := range list {
-		tparams = check.declareTypeParam(tparams, f.Name)
+	// list (so we can have mutually recursive parameterized type bounds).
+	for i, f := range list {
+		tparams[i] = check.declareTypeParam(f.Name)
 	}
 
 	var bound Type
-	for i, j := 0, 0; i < len(list); i = j {
-		f := list[i]
-
-		// determine the range of type parameters list[i:j] with identical type bound
-		// (declared as in (type a, b, c B))
-		j = i + 1
-		for j < len(list) && list[j].Type == f.Type {
-			j++
-		}
-
-		// this should never be the case, but be careful
-		if f.Type == nil {
-			continue
-		}
-
-		// The predeclared identifier "any" is visible only as a constraint
-		// in a type parameter list. Look for it before general constraint
-		// resolution.
-		if tident, _ := unparen(f.Type).(*syntax.Name); tident != nil && tident.Value == "any" && check.lookup("any") == nil {
-			bound = universeAny
-		} else {
-			bound = check.typ(f.Type)
-		}
-
-		// type bound must be an interface
-		// TODO(gri) We should delay the interface check because
-		//           we may not have a complete interface yet:
-		//           type C(type T C) interface {}
-		//           (issue #39724).
-		if _, ok := under(bound).(*Interface); ok {
-			// set the type bounds
-			for i < j {
-				tparams[i].typ.(*TypeParam).bound = bound
-				i++
-			}
-		} else if bound != Typ[Invalid] {
-			check.errorf(f.Type, "%s is not an interface", bound)
+	for i, f := range list {
+		// Optimization: Re-use the previous type bound if it hasn't changed.
+		// This also preserves the grouped output of type parameter lists
+		// when printing type strings.
+		if i == 0 || f.Type != list[i-1].Type {
+			bound = check.boundType(f.Type)
 		}
+		tparams[i].bound = bound
 	}
 
-	return
+	return bindTParams(tparams)
 }
 
-func (check *Checker) declareTypeParam(tparams []*TypeName, name *syntax.Name) []*TypeName {
-	tpar := NewTypeName(name.Pos(), check.pkg, name.Value, nil)
-	check.NewTypeParam(tpar, len(tparams), &emptyInterface) // assigns type to tpar as a side-effect
-	check.declare(check.scope, name, tpar, check.scope.pos) // TODO(gri) check scope position
-	tparams = append(tparams, tpar)
+func (check *Checker) declareTypeParam(name *syntax.Name) *TypeParam {
+	tname := NewTypeName(name.Pos(), check.pkg, name.Value, nil)
+	tpar := check.NewTypeParam(tname, nil)                   // assigns type to tname as a side-effect
+	check.declare(check.scope, name, tname, check.scope.pos) // TODO(gri) check scope position
+	return tpar
+}
 
-	if check.conf.Trace {
-		check.trace(name.Pos(), "type param = %v", tparams[len(tparams)-1])
+// boundType type-checks the type expression e and returns its type, or Typ[Invalid].
+// The type must be an interface, including the predeclared type "any".
+func (check *Checker) boundType(e syntax.Expr) Type {
+	// The predeclared identifier "any" is visible only as a type bound in a type parameter list.
+	// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+	if name, _ := unparen(e).(*syntax.Name); name != nil && name.Value == "any" && check.lookup("any") == universeAny {
+		return universeAny.Type()
 	}
 
-	return tparams
+	bound := check.typ(e)
+	check.later(func() {
+		u := under(bound)
+		if _, ok := u.(*Interface); !ok && u != Typ[Invalid] {
+			check.errorf(e, "%s is not an interface", bound)
+		}
+	})
+	return bound
 }
 
 func (check *Checker) collectMethods(obj *TypeName) {
@@ -737,7 +650,8 @@ func (check *Checker) collectMethods(obj *TypeName) {
 	// and field names must be distinct."
 	base := asNamed(obj.typ) // shouldn't fail but be conservative
 	if base != nil {
-		if t, _ := base.underlying.(*Struct); t != nil {
+		u := safeUnderlying(base) // base should be expanded, but use safeUnderlying to be conservative
+		if t, _ := u.(*Struct); t != nil {
 			for _, fld := range t.fields {
 				if fld.name != "_" {
 					assert(mset.insert(fld) == nil)
@@ -779,6 +693,7 @@ func (check *Checker) collectMethods(obj *TypeName) {
 		}
 
 		if base != nil {
+			base.load() // TODO(mdempsky): Probably unnecessary.
 			base.methods = append(base.methods, m)
 		}
 	}
@@ -805,6 +720,10 @@ func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
 	check.funcType(sig, fdecl.Recv, fdecl.TParamList, fdecl.Type)
 	obj.color_ = saved
 
+	if len(fdecl.TParamList) > 0 && fdecl.Body == nil {
+		check.softErrorf(fdecl, "parameterized function is missing function body")
+	}
+
 	// function body must be type-checked after global declarations
 	// (functions implemented elsewhere have no body)
 	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
diff --git a/src/cmd/compile/internal/types2/errorcalls_test.go b/src/cmd/compile/internal/types2/errorcalls_test.go
index 28bb33aaffd00443da31ca7086caa1e8cfba37f2..80b05f9f0f06883022a9333d84d93c233f4c7294 100644
--- a/src/cmd/compile/internal/types2/errorcalls_test.go
+++ b/src/cmd/compile/internal/types2/errorcalls_test.go
@@ -18,7 +18,7 @@ func TestErrorCalls(t *testing.T) {
 	}
 
 	for _, file := range files {
-		syntax.Walk(file, func(n syntax.Node) bool {
+		syntax.Crawl(file, func(n syntax.Node) bool {
 			call, _ := n.(*syntax.CallExpr)
 			if call == nil {
 				return false
diff --git a/src/cmd/compile/internal/types2/errors.go b/src/cmd/compile/internal/types2/errors.go
index af4ecb2300a58cbfe5e8eeae32220fe72129ba2d..a68273271b7434493f60ad45609e12b8f18b2070 100644
--- a/src/cmd/compile/internal/types2/errors.go
+++ b/src/cmd/compile/internal/types2/errors.go
@@ -88,7 +88,7 @@ func sprintf(qf Qualifier, format string, args ...interface{}) string {
 		case nil:
 			arg = ""
 		case operand:
-			panic("internal error: should always pass *operand")
+			panic("got operand instead of *operand")
 		case *operand:
 			arg = operandString(a, qf)
 		case syntax.Pos:
@@ -111,7 +111,7 @@ func (check *Checker) qualifier(pkg *Package) string {
 		if check.pkgPathMap == nil {
 			check.pkgPathMap = make(map[string]map[string]bool)
 			check.seenPkgMap = make(map[*Package]bool)
-			check.markImports(pkg)
+			check.markImports(check.pkg)
 		}
 		// If the same package name was used by multiple packages, display the full path.
 		if len(check.pkgPathMap[pkg.name]) > 1 {
@@ -148,7 +148,7 @@ func (check *Checker) sprintf(format string, args ...interface{}) string {
 
 func (check *Checker) report(err *error_) {
 	if err.empty() {
-		panic("internal error: reporting no error")
+		panic("no error to report")
 	}
 	check.err(err.pos(), err.msg(check.qualifier), err.soft)
 }
diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index 23b79656bb5fb0dabb7c769a27bcb86e10e68b7a..d108093dacc08644588fea76bb424d4391ab2369 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -157,6 +157,14 @@ var op2str2 = [...]string{
 	syntax.Shl: "shift",
 }
 
+func underIs(typ Type, f func(Type) bool) bool {
+	u := under(typ)
+	if tpar, _ := u.(*TypeParam); tpar != nil {
+		return tpar.underIs(f)
+	}
+	return f(u)
+}
+
 func (check *Checker) unary(x *operand, e *syntax.Operation) {
 	check.expr(x, e.X)
 	if x.mode == invalid {
@@ -177,19 +185,29 @@ func (check *Checker) unary(x *operand, e *syntax.Operation) {
 		return
 
 	case syntax.Recv:
-		typ := asChan(x.typ)
-		if typ == nil {
-			check.errorf(x, invalidOp+"cannot receive from non-channel %s", x)
-			x.mode = invalid
-			return
-		}
-		if typ.dir == SendOnly {
-			check.errorf(x, invalidOp+"cannot receive from send-only channel %s", x)
+		var elem Type
+		if !underIs(x.typ, func(u Type) bool {
+			ch, _ := u.(*Chan)
+			if ch == nil {
+				check.errorf(x, invalidOp+"cannot receive from non-channel %s", x)
+				return false
+			}
+			if ch.dir == SendOnly {
+				check.errorf(x, invalidOp+"cannot receive from send-only channel %s", x)
+				return false
+			}
+			if elem != nil && !Identical(ch.elem, elem) {
+				check.errorf(x, invalidOp+"channels of %s must have the same element type", x)
+				return false
+			}
+			elem = ch.elem
+			return true
+		}) {
 			x.mode = invalid
 			return
 		}
 		x.mode = commaok
-		x.typ = typ.elem
+		x.typ = elem
 		check.hasCallOrRecv = true
 		return
 	}
@@ -643,7 +661,7 @@ func (check *Checker) updateExprVal(x syntax.Expr, val constant.Value) {
 func (check *Checker) convertUntyped(x *operand, target Type) {
 	newType, val, code := check.implicitTypeAndValue(x, target)
 	if code != 0 {
-		check.invalidConversion(code, x, target.Underlying())
+		check.invalidConversion(code, x, safeUnderlying(target))
 		x.mode = invalid
 		return
 	}
@@ -664,7 +682,6 @@ func (check *Checker) convertUntyped(x *operand, target Type) {
 // If x is a constant operand, the returned constant.Value will be the
 // representation of x in this context.
 func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, constant.Value, errorCode) {
-	target = expand(target)
 	if x.mode == invalid || isTyped(x.typ) || target == Typ[Invalid] {
 		return x.typ, nil, 0
 	}
@@ -691,7 +708,7 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 		return nil, nil, _InvalidUntypedConversion
 	}
 
-	switch t := optype(target).(type) {
+	switch t := under(target).(type) {
 	case *Basic:
 		if x.mode == constant_ {
 			v, code := check.representation(x, t)
@@ -723,8 +740,8 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 		default:
 			return nil, nil, _InvalidUntypedConversion
 		}
-	case *Sum:
-		ok := t.is(func(t Type) bool {
+	case *TypeParam:
+		ok := t.underIs(func(t Type) bool {
 			target, _, _ := check.implicitTypeAndValue(x, t)
 			return target != nil
 		})
@@ -735,7 +752,6 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 		// Update operand types to the default type rather than the target
 		// (interface) type: values must have concrete dynamic types.
 		// Untyped nil was handled upfront.
-		check.completeInterface(nopos, t)
 		if !t.Empty() {
 			return nil, nil, _InvalidUntypedConversion // cannot assign untyped values to non-empty interfaces
 		}
@@ -972,14 +988,28 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
 		return
 	}
 
-	check.convertUntyped(x, y.typ)
-	if x.mode == invalid {
-		return
+	canMix := func(x, y *operand) bool {
+		if IsInterface(x.typ) || IsInterface(y.typ) {
+			return true
+		}
+		if isBoolean(x.typ) != isBoolean(y.typ) {
+			return false
+		}
+		if isString(x.typ) != isString(y.typ) {
+			return false
+		}
+		return true
 	}
-	check.convertUntyped(&y, x.typ)
-	if y.mode == invalid {
-		x.mode = invalid
-		return
+	if canMix(x, &y) {
+		check.convertUntyped(x, y.typ)
+		if x.mode == invalid {
+			return
+		}
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			x.mode = invalid
+			return
+		}
 	}
 
 	if isComparison(op) {
@@ -987,7 +1017,7 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
 		return
 	}
 
-	if !check.identical(x.typ, y.typ) {
+	if !Identical(x.typ, y.typ) {
 		// only report an error if we have valid types
 		// (otherwise we had an error reported elsewhere already)
 		if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
@@ -1316,7 +1346,7 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 					xkey := keyVal(x.val)
 					if asInterface(utyp.key) != nil {
 						for _, vtyp := range visited[xkey] {
-							if check.identical(vtyp, x.typ) {
+							if Identical(vtyp, x.typ) {
 								duplicate = true
 								break
 							}
@@ -1448,13 +1478,24 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 				case typexpr:
 					x.typ = &Pointer{base: x.typ}
 				default:
-					if typ := asPointer(x.typ); typ != nil {
-						x.mode = variable
-						x.typ = typ.base
-					} else {
-						check.errorf(x, invalidOp+"cannot indirect %s", x)
+					var base Type
+					if !underIs(x.typ, func(u Type) bool {
+						p, _ := u.(*Pointer)
+						if p == nil {
+							check.errorf(x, invalidOp+"cannot indirect %s", x)
+							return false
+						}
+						if base != nil && !Identical(p.base, base) {
+							check.errorf(x, invalidOp+"pointers of %s must have identical base types", x)
+							return false
+						}
+						base = p.base
+						return true
+					}) {
 						goto Error
 					}
+					x.mode = variable
+					x.typ = base
 				}
 				break
 			}
@@ -1537,7 +1578,7 @@ func (check *Checker) typeAssertion(pos syntax.Pos, x *operand, xtyp *Interface,
 	}
 	var msg string
 	if wrongType != nil {
-		if check.identical(method.typ, wrongType.typ) {
+		if Identical(method.typ, wrongType.typ) {
 			msg = fmt.Sprintf("missing method %s (%s has pointer receiver)", method.name, method.name)
 		} else {
 			msg = fmt.Sprintf("wrong type for method %s (have %s, want %s)", method.name, wrongType.typ, method.typ)
diff --git a/src/cmd/compile/internal/types2/index.go b/src/cmd/compile/internal/types2/index.go
index c94017a8fb9b98c29d55707f867b0c15bcbb3e50..e8755a1a68ea3872d1cf5e205eb50c21ca8f9d15 100644
--- a/src/cmd/compile/internal/types2/index.go
+++ b/src/cmd/compile/internal/types2/index.go
@@ -32,7 +32,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 		return false
 
 	case value:
-		if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+		if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 			// function instantiation
 			return true
 		}
@@ -41,7 +41,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 	// ordinary index expression
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			valid = true
@@ -80,7 +80,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 		index := check.singleIndex(e)
 		if index == nil {
 			x.mode = invalid
-			return
+			return false
 		}
 		var key operand
 		check.expr(&key, index)
@@ -89,87 +89,80 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 		x.mode = mapindex
 		x.typ = typ.elem
 		x.expr = e
-		return
+		return false
 
-	case *Sum:
-		// A sum type can be indexed if all of the sum's types
-		// support indexing and have the same index and element
-		// type. Special rules apply for maps in the sum type.
-		var tkey, telem Type // key is for map types only
-		nmaps := 0           // number of map types in sum type
-		if typ.is(func(t Type) bool {
-			var e Type
-			switch t := under(t).(type) {
+	case *TypeParam:
+		// TODO(gri) report detailed failure cause for better error messages
+		var tkey, telem Type // tkey != nil if we have maps
+		if typ.underIs(func(u Type) bool {
+			var key, elem Type
+			alen := int64(-1) // valid if >= 0
+			switch t := u.(type) {
 			case *Basic:
-				if isString(t) {
-					e = universeByte
+				if !isString(t) {
+					return false
 				}
+				elem = universeByte
 			case *Array:
-				e = t.elem
+				elem = t.elem
+				alen = t.len
 			case *Pointer:
-				if t := asArray(t.base); t != nil {
-					e = t.elem
+				a, _ := under(t.base).(*Array)
+				if a == nil {
+					return false
 				}
+				elem = a.elem
+				alen = a.len
 			case *Slice:
-				e = t.elem
+				elem = t.elem
 			case *Map:
-				// If there are multiple maps in the sum type,
-				// they must have identical key types.
-				// TODO(gri) We may be able to relax this rule
-				// but it becomes complicated very quickly.
-				if tkey != nil && !Identical(t.key, tkey) {
+				key = t.key
+				elem = t.elem
+			default:
+				return false
+			}
+			assert(elem != nil)
+			if telem == nil {
+				// first type
+				tkey, telem = key, elem
+				length = alen
+			} else {
+				// all map keys must be identical (incl. all nil)
+				if !Identical(key, tkey) {
 					return false
 				}
-				tkey = t.key
-				e = t.elem
-				nmaps++
-			case *TypeParam:
-				check.errorf(x, "type of %s contains a type parameter - cannot index (implementation restriction)", x)
-			case *instance:
-				panic("unimplemented")
-			}
-			if e == nil || telem != nil && !Identical(e, telem) {
-				return false
+				// all element types must be identical
+				if !Identical(elem, telem) {
+					return false
+				}
+				tkey, telem = key, elem
+				// track the minimal length for arrays
+				if alen >= 0 && alen < length {
+					length = alen
+				}
 			}
-			telem = e
 			return true
 		}) {
-			// If there are maps, the index expression must be assignable
-			// to the map key type (as for simple map index expressions).
-			if nmaps > 0 {
+			// For maps, the index expression must be assignable to the map key type.
+			if tkey != nil {
 				index := check.singleIndex(e)
 				if index == nil {
 					x.mode = invalid
-					return
+					return false
 				}
 				var key operand
 				check.expr(&key, index)
 				check.assignment(&key, tkey, "map index")
 				// ok to continue even if indexing failed - map element type is known
-
-				// If there are only maps, we are done.
-				if nmaps == len(typ.types) {
-					x.mode = mapindex
-					x.typ = telem
-					x.expr = e
-					return
-				}
-
-				// Otherwise we have mix of maps and other types. For
-				// now we require that the map key be an integer type.
-				// TODO(gri) This is probably not good enough.
-				valid = isInteger(tkey)
-				// avoid 2nd indexing error if indexing failed above
-				if !valid && key.mode == invalid {
-					x.mode = invalid
-					return
-				}
-				x.mode = value // map index expressions are not addressable
-			} else {
-				// no maps
-				valid = true
-				x.mode = variable
+				x.mode = mapindex
+				x.typ = telem
+				x.expr = e
+				return false
 			}
+
+			// no maps
+			valid = true
+			x.mode = variable
 			x.typ = telem
 		}
 	}
@@ -177,13 +170,13 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 	if !valid {
 		check.errorf(x, invalidOp+"cannot index %s", x)
 		x.mode = invalid
-		return
+		return false
 	}
 
 	index := check.singleIndex(e)
 	if index == nil {
 		x.mode = invalid
-		return
+		return false
 	}
 
 	// In pathological (invalid) cases (e.g.: type T1 [][[]T1{}[0][0]]T0)
@@ -206,7 +199,7 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			if e.Full {
@@ -246,7 +239,7 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
 		valid = true
 		// x.typ doesn't change
 
-	case *Sum, *TypeParam:
+	case *TypeParam:
 		check.error(x, "generic slice expressions not yet implemented")
 		x.mode = invalid
 		return
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index f37d7f6477e96ab29bb8d0e6705cb65b0dd8cb37..5badecc0700e2f2f6154eb82d1e40868fce658f2 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -28,7 +28,7 @@ const useConstraintTypeInference = true
 //
 // Constraint type inference is used after each step to expand the set of type arguments.
 //
-func (check *Checker) infer(pos syntax.Pos, tparams []*TypeName, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
+func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
 	if debug {
 		defer func() {
 			assert(result == nil || len(result) == len(tparams))
@@ -83,18 +83,18 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeName, targs []Type, p
 
 	// Substitute type arguments for their respective type parameters in params,
 	// if any. Note that nil targs entries are ignored by check.subst.
-	// TODO(gri) Can we avoid this (we're setting known type argumemts below,
+	// TODO(gri) Can we avoid this (we're setting known type arguments below,
 	//           but that doesn't impact the isParameterized check for now).
 	if params.Len() > 0 {
 		smap := makeSubstMap(tparams, targs)
-		params = check.subst(nopos, params, smap).(*Tuple)
+		params = check.subst(nopos, params, smap, nil).(*Tuple)
 	}
 
 	// --- 2 ---
 	// Unify parameter and argument types for generic parameters with typed arguments
 	// and collect the indices of generic parameters with untyped arguments.
 	// Terminology: generic parameter = function parameter with a type-parameterized type
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 
 	// Set the type arguments which we know already.
@@ -122,12 +122,12 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeName, targs []Type, p
 				}
 			}
 			if allFailed {
-				check.errorf(arg, "%s %s of %s does not match %s (cannot infer %s)", kind, targ, arg.expr, tpar, typeNamesString(tparams))
+				check.errorf(arg, "%s %s of %s does not match %s (cannot infer %s)", kind, targ, arg.expr, tpar, typeParamsString(tparams))
 				return
 			}
 		}
 		smap := makeSubstMap(tparams, targs)
-		inferred := check.subst(arg.Pos(), tpar, smap)
+		inferred := check.subst(arg.Pos(), tpar, smap, nil)
 		if inferred != tpar {
 			check.errorf(arg, "%s %s of %s does not match inferred type %s for %s", kind, targ, arg.expr, inferred, tpar)
 		} else {
@@ -222,23 +222,23 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeName, targs []Type, p
 	assert(targs != nil && index >= 0 && targs[index] == nil)
 	tpar := tparams[index]
 	if report {
-		check.errorf(pos, "cannot infer %s (%s) (%s)", tpar.name, tpar.pos, targs)
+		check.errorf(pos, "cannot infer %s (%s) (%s)", tpar.obj.name, tpar.obj.pos, targs)
 	}
 	return nil
 }
 
-// typeNamesString produces a string containing all the
-// type names in list suitable for human consumption.
-func typeNamesString(list []*TypeName) string {
+// typeParamsString produces a string of the type parameter names
+// in list suitable for human consumption.
+func typeParamsString(list []*TypeParam) string {
 	// common cases
 	n := len(list)
 	switch n {
 	case 0:
 		return ""
 	case 1:
-		return list[0].name
+		return list[0].obj.name
 	case 2:
-		return list[0].name + " and " + list[1].name
+		return list[0].obj.name + " and " + list[1].obj.name
 	}
 
 	// general case (n > 2)
@@ -248,15 +248,15 @@ func typeNamesString(list []*TypeName) string {
 		if i > 0 {
 			b.WriteString(", ")
 		}
-		b.WriteString(tname.name)
+		b.WriteString(tname.obj.name)
 	}
 	b.WriteString(", and ")
-	b.WriteString(list[n-1].name)
+	b.WriteString(list[n-1].obj.name)
 	return b.String()
 }
 
 // IsParameterized reports whether typ contains any of the type parameters of tparams.
-func isParameterized(tparams []*TypeName, typ Type) bool {
+func isParameterized(tparams []*TypeParam, typ Type) bool {
 	w := tpWalker{
 		seen:    make(map[Type]bool),
 		tparams: tparams,
@@ -266,7 +266,7 @@ func isParameterized(tparams []*TypeName, typ Type) bool {
 
 type tpWalker struct {
 	seen    map[Type]bool
-	tparams []*TypeName
+	tparams []*TypeParam
 }
 
 func (w *tpWalker) isParameterized(typ Type) (res bool) {
@@ -280,7 +280,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 	}()
 
 	switch t := typ.(type) {
-	case nil, *Basic: // TODO(gri) should nil be handled here?
+	case nil, *top, *Basic: // TODO(gri) should nil be handled here?
 		break
 
 	case *Array:
@@ -307,9 +307,6 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 			}
 		}
 
-	case *Sum:
-		return w.isParameterizedList(t.types)
-
 	case *Signature:
 		// t.tparams may not be nil if we are looking at a signature
 		// of a generic function type (or an interface method) that is
@@ -321,24 +318,15 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 		return w.isParameterized(t.params) || w.isParameterized(t.results)
 
 	case *Interface:
-		if t.allMethods != nil {
-			// interface is complete - quick test
-			for _, m := range t.allMethods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
+		tset := t.typeSet()
+		for _, m := range tset.methods {
+			if w.isParameterized(m.typ) {
+				return true
 			}
-			return w.isParameterizedList(unpack(t.allTypes))
 		}
-
-		return t.iterate(func(t *Interface) bool {
-			for _, m := range t.methods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
-			}
-			return w.isParameterizedList(unpack(t.types))
-		}, nil)
+		return tset.is(func(t *term) bool {
+			return w.isParameterized(t.typ)
+		})
 
 	case *Map:
 		return w.isParameterized(t.key) || w.isParameterized(t.elem)
@@ -347,14 +335,11 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 		return w.isParameterized(t.elem)
 
 	case *Named:
-		return w.isParameterizedList(t.targs)
+		return w.isParameterizedTypeList(t.targs.list())
 
 	case *TypeParam:
 		// t must be one of w.tparams
-		return t.index < len(w.tparams) && w.tparams[t.index].typ == t
-
-	case *instance:
-		return w.isParameterizedList(t.targs)
+		return t.index < len(w.tparams) && w.tparams[t.index] == t
 
 	default:
 		unreachable()
@@ -363,7 +348,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 	return false
 }
 
-func (w *tpWalker) isParameterizedList(list []Type) bool {
+func (w *tpWalker) isParameterizedTypeList(list []Type) bool {
 	for _, t := range list {
 		if w.isParameterized(t) {
 			return true
@@ -380,12 +365,12 @@ func (w *tpWalker) isParameterizedList(list []Type) bool {
 // first type argument in that list that couldn't be inferred (and thus is nil). If all
 // type arguments were inferred successfully, index is < 0. The number of type arguments
 // provided may be less than the number of type parameters, but there must be at least one.
-func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (types []Type, index int) {
+func (check *Checker) inferB(tparams []*TypeParam, targs []Type, report bool) (types []Type, index int) {
 	assert(len(tparams) >= len(targs) && len(targs) > 0)
 
 	// Setup bidirectional unification between those structural bounds
 	// and the corresponding type arguments (which may be nil!).
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 	u.y = u.x // type parameters between LHS and RHS of unification are identical
 
@@ -398,12 +383,12 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 
 	// Unify type parameters with their structural constraints, if any.
 	for _, tpar := range tparams {
-		typ := tpar.typ.(*TypeParam)
-		sbound := check.structuralType(typ.bound)
+		typ := tpar
+		sbound := typ.structuralType()
 		if sbound != nil {
 			if !u.unify(typ, sbound) {
 				if report {
-					check.errorf(tpar, "%s does not match %s", tpar, sbound)
+					check.errorf(tpar.obj, "%s does not match %s", tpar.obj, sbound)
 				}
 				return nil, 0
 			}
@@ -412,8 +397,8 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
 	// arguments for which there were structural constraints. The newly inferred non-
-	// nil entries may still contain references to other type parameters. For instance,
-	// for [A any, B interface{type []C}, C interface{type *A}], if A == int
+	// nil entries may still contain references to other type parameters.
+	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
 	// until nothing changes anymore.
@@ -442,7 +427,7 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 		n := 0
 		for _, index := range dirty {
 			t0 := types[index]
-			if t1 := check.subst(nopos, t0, smap); t1 != t0 {
+			if t1 := check.subst(nopos, t0, smap, nil); t1 != t0 {
 				types[index] = t1
 				dirty[n] = index
 				n++
@@ -472,16 +457,3 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 
 	return
 }
-
-// structuralType returns the structural type of a constraint, if any.
-func (check *Checker) structuralType(constraint Type) Type {
-	if iface, _ := under(constraint).(*Interface); iface != nil {
-		check.completeInterface(nopos, iface)
-		types := unpack(iface.allTypes)
-		if len(types) == 1 {
-			return types[0]
-		}
-		return nil
-	}
-	return constraint
-}
diff --git a/src/cmd/compile/internal/types2/instantiate.go b/src/cmd/compile/internal/types2/instantiate.go
index 0df52e851c9de4b6f02726325ad1698fb73c060e..8bea63ec862a7f950ad1211594cf7b6effda2ec7 100644
--- a/src/cmd/compile/internal/types2/instantiate.go
+++ b/src/cmd/compile/internal/types2/instantiate.go
@@ -2,30 +2,155 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// This file implements instantiation of generic types
+// through substitution of type parameters by type arguments.
+
 package types2
 
 import (
 	"cmd/compile/internal/syntax"
+	"errors"
 	"fmt"
 )
 
-// Instantiate instantiates the type typ with the given type arguments.
-// typ must be a *Named or a *Signature type, it must be generic, and
-// its number of type parameters must match the number of provided type
-// arguments. The result is a new, instantiated (not generic) type of
-// the same kind (either a *Named or a *Signature). The type arguments
-// are not checked against the constraints of the type parameters.
-// Any methods attached to a *Named are simply copied; they are not
-// instantiated.
-func Instantiate(pos syntax.Pos, typ Type, targs []Type) (res Type) {
-	// TODO(gri) This code is basically identical to the prolog
-	//           in Checker.instantiate. Factor.
-	var tparams []*TypeName
+// An Environment is an opaque type checking environment. It may be used to
+// share identical type instances across type checked packages or calls to
+// Instantiate.
+type Environment struct {
+	// For now, Environment just hides a Checker.
+	// Eventually, we strive to remove the need for a checker.
+	check *Checker
+}
+
+// NewEnvironment returns a new Environment, initialized with the given
+// Checker, or nil.
+func NewEnvironment(check *Checker) *Environment {
+	return &Environment{check}
+}
+
+// Instantiate instantiates the type typ with the given type arguments targs.
+// typ must be a *Named or a *Signature type, and its number of type parameters
+// must match the number of provided type arguments. The result is a new,
+// instantiated (not parameterized) type of the same kind (either a *Named or a
+// *Signature). Any methods attached to a *Named are simply copied; they are
+// not instantiated.
+//
+// If env is non-nil, it may be used to de-dupe the instance against previous
+// instances with the same identity. This functionality is implemented for
+// environments with non-nil Checkers.
+//
+// If verify is set and constraint satisfaction fails, the returned error may
+// be of dynamic type ArgumentError indicating which type argument did not
+// satisfy its corresponding type parameter constraint, and why.
+//
+// TODO(rfindley): change this function to also return an error if lengths of
+// tparams and targs do not match.
+func Instantiate(env *Environment, typ Type, targs []Type, validate bool) (Type, error) {
+	var check *Checker
+	if env != nil {
+		check = env.check
+	}
+	inst := check.instance(nopos, typ, targs)
+
+	var err error
+	if validate {
+		var tparams []*TypeParam
+		switch t := typ.(type) {
+		case *Named:
+			tparams = t.TParams().list()
+		case *Signature:
+			tparams = t.TParams().list()
+		}
+		if i, err := check.verify(nopos, tparams, targs); err != nil {
+			return inst, ArgumentError{i, err}
+		}
+	}
+
+	return inst, err
+}
+
+// instantiate creates an instance and defers verification of constraints to
+// later in the type checking pass. For Named types the resulting instance will
+// be unexpanded.
+func (check *Checker) instantiate(pos syntax.Pos, typ Type, targs []Type, posList []syntax.Pos) (res Type) {
+	assert(check != nil)
+	if check.conf.Trace {
+		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
+		check.indent++
+		defer func() {
+			check.indent--
+			var under Type
+			if res != nil {
+				// Calling under() here may lead to endless instantiations.
+				// Test case: type T[P any] T[P]
+				// TODO(gri) investigate if that's a bug or to be expected.
+				under = safeUnderlying(res)
+			}
+			check.trace(pos, "=> %s (under = %s)", res, under)
+		}()
+	}
+
+	inst := check.instance(pos, typ, targs)
+
+	assert(len(posList) <= len(targs))
+	check.later(func() {
+		// Collect tparams again because lazily loaded *Named types may not have
+		// had tparams set up above.
+		var tparams []*TypeParam
+		switch t := typ.(type) {
+		case *Named:
+			tparams = t.TParams().list()
+		case *Signature:
+			tparams = t.TParams().list()
+		}
+		// Avoid duplicate errors; instantiate will have complained if tparams
+		// and targs do not have the same length.
+		if len(tparams) == len(targs) {
+			if i, err := check.verify(pos, tparams, targs); err != nil {
+				// best position for error reporting
+				pos := pos
+				if i < len(posList) {
+					pos = posList[i]
+				}
+				check.softErrorf(pos, err.Error())
+			}
+		}
+	})
+	return inst
+}
+
+// instance creates a type or function instance using the given original type
+// typ and arguments targs. For Named types the resulting instance will be
+// unexpanded.
+func (check *Checker) instance(pos syntax.Pos, typ Type, targs []Type) (res Type) {
+	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
 	switch t := typ.(type) {
 	case *Named:
-		tparams = t.tparams
+		h := instantiatedHash(t, targs)
+		if check != nil {
+			// typ may already have been instantiated with identical type arguments. In
+			// that case, re-use the existing instance.
+			if named := check.typMap[h]; named != nil {
+				return named
+			}
+		}
+
+		tname := NewTypeName(pos, t.obj.pkg, t.obj.name, nil)
+		named := check.newNamed(tname, t, nil, nil, nil) // methods and tparams are set when named is loaded
+		named.targs = NewTypeList(targs)
+		named.instance = &instance{pos}
+		if check != nil {
+			check.typMap[h] = named
+		}
+		res = named
 	case *Signature:
-		tparams = t.tparams
+		tparams := t.TParams()
+		if !check.validateTArgLen(pos, tparams.Len(), len(targs)) {
+			return Typ[Invalid]
+		}
+		if tparams.Len() == 0 {
+			return typ // nothing to do (minor optimization)
+		}
 		defer func() {
 			// If we had an unexpected failure somewhere don't panic below when
 			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
@@ -44,20 +169,125 @@ func Instantiate(pos syntax.Pos, typ Type, targs []Type) (res Type) {
 			// anymore; we need to set tparams to nil.
 			res.(*Signature).tparams = nil
 		}()
-
+		res = check.subst(pos, typ, makeSubstMap(tparams.list(), targs), nil)
 	default:
+		// only types and functions can be generic
 		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
 	}
+	return res
+}
 
-	// the number of supplied types must match the number of type parameters
-	if len(targs) != len(tparams) {
-		panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams)))
+// validateTArgLen verifies that the length of targs and tparams matches,
+// reporting an error if not. If validation fails and check is nil,
+// validateTArgLen panics.
+func (check *Checker) validateTArgLen(pos syntax.Pos, ntparams, ntargs int) bool {
+	if ntargs != ntparams {
+		// TODO(gri) provide better error message
+		if check != nil {
+			check.errorf(pos, "got %d arguments but %d type parameters", ntargs, ntparams)
+			return false
+		}
+		panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, ntargs, ntparams))
 	}
+	return true
+}
 
-	if len(tparams) == 0 {
-		return typ // nothing to do (minor optimization)
+func (check *Checker) verify(pos syntax.Pos, tparams []*TypeParam, targs []Type) (int, error) {
+	smap := makeSubstMap(tparams, targs)
+	for i, tpar := range tparams {
+		// stop checking bounds after the first failure
+		if err := check.satisfies(pos, targs[i], tpar, smap); err != nil {
+			return i, err
+		}
 	}
+	return -1, nil
+}
 
-	smap := makeSubstMap(tparams, targs)
-	return (*Checker)(nil).subst(pos, typ, smap)
+// satisfies reports whether the type argument targ satisfies the constraint of type parameter
+// parameter tpar (after any of its type parameters have been substituted through smap).
+// A suitable error is reported if the result is false.
+// TODO(gri) This should be a method of interfaces or type sets.
+func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap substMap) error {
+	iface := tpar.iface()
+	if iface.Empty() {
+		return nil // no type bound
+	}
+
+	// TODO(rfindley): it would be great if users could pass in a qualifier here,
+	// rather than falling back to verbose qualification. Maybe this can be part
+	// of a the shared environment.
+	var qf Qualifier
+	if check != nil {
+		qf = check.qualifier
+	}
+	errorf := func(format string, args ...interface{}) error {
+		return errors.New(sprintf(qf, format, args...))
+	}
+
+	// The type parameter bound is parameterized with the same type parameters
+	// as the instantiated type; before we can use it for bounds checking we
+	// need to instantiate it with the type arguments with which we instantiate
+	// the parameterized type.
+	iface = check.subst(pos, iface, smap, nil).(*Interface)
+
+	// if iface is comparable, targ must be comparable
+	// TODO(gri) the error messages needs to be better, here
+	if iface.IsComparable() && !Comparable(targ) {
+		if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsAll() {
+			return errorf("%s has no constraints", targ)
+		}
+		return errorf("%s does not satisfy comparable", targ)
+	}
+
+	// targ must implement iface (methods)
+	// - check only if we have methods
+	if iface.NumMethods() > 0 {
+		// If the type argument is a pointer to a type parameter, the type argument's
+		// method set is empty.
+		// TODO(gri) is this what we want? (spec question)
+		if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
+			return errorf("%s has no methods", targ)
+		}
+		if m, wrong := check.missingMethod(targ, iface, true); m != nil {
+			// TODO(gri) needs to print updated name to avoid major confusion in error message!
+			//           (print warning for now)
+			// Old warning:
+			// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
+			if wrong != nil {
+				// TODO(gri) This can still report uninstantiated types which makes the error message
+				//           more difficult to read then necessary.
+				return errorf("%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
+					targ, tpar.bound, wrong, m,
+				)
+			}
+			return errorf("%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
+		}
+	}
+
+	// targ's underlying type must also be one of the interface types listed, if any
+	if !iface.typeSet().hasTerms() {
+		return nil // nothing to do
+	}
+
+	// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
+	// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
+	if targ := asTypeParam(targ); targ != nil {
+		targBound := targ.iface()
+		if !targBound.typeSet().hasTerms() {
+			return errorf("%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
+		}
+		if !targBound.typeSet().subsetOf(iface.typeSet()) {
+			// TODO(gri) need better error message
+			return errorf("%s does not satisfy %s", targ, tpar.bound)
+		}
+		return nil
+	}
+
+	// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
+	if !iface.typeSet().includes(targ) {
+		// TODO(gri) better error message
+		return errorf("%s does not satisfy %s", targ, tpar.bound)
+	}
+
+	return nil
 }
diff --git a/src/cmd/compile/internal/types2/interface.go b/src/cmd/compile/internal/types2/interface.go
new file mode 100644
index 0000000000000000000000000000000000000000..ccd3de0a6e66bfa0fc6c3754723a11b9322bfade
--- /dev/null
+++ b/src/cmd/compile/internal/types2/interface.go
@@ -0,0 +1,226 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "cmd/compile/internal/syntax"
+
+// ----------------------------------------------------------------------------
+// API
+
+// An Interface represents an interface type.
+type Interface struct {
+	obj       *TypeName     // corresponding declared object; or nil (for better error messages)
+	methods   []*Func       // ordered list of explicitly declared methods
+	embeddeds []Type        // ordered list of explicitly embedded elements
+	embedPos  *[]syntax.Pos // positions of embedded elements; or nil (for error messages) - use pointer to save space
+	complete  bool          // indicates that all fields (except for tset) are set up
+
+	tset *_TypeSet // type set described by this interface, computed lazily
+}
+
+// typeSet returns the type set for interface t.
+func (t *Interface) typeSet() *_TypeSet { return computeInterfaceTypeSet(nil, nopos, t) }
+
+// emptyInterface represents the empty interface
+var emptyInterface = Interface{complete: true, tset: &topTypeSet}
+
+// NewInterface returns a new interface for the given methods and embedded types.
+// NewInterface takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+//
+// Deprecated: Use NewInterfaceType instead which allows arbitrary embedded types.
+func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
+	tnames := make([]Type, len(embeddeds))
+	for i, t := range embeddeds {
+		tnames[i] = t
+	}
+	return NewInterfaceType(methods, tnames)
+}
+
+// NewInterfaceType returns a new interface for the given methods and embedded types.
+// NewInterfaceType takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
+	if len(methods) == 0 && len(embeddeds) == 0 {
+		return &emptyInterface
+	}
+
+	// set method receivers if necessary
+	typ := new(Interface)
+	for _, m := range methods {
+		if sig := m.typ.(*Signature); sig.recv == nil {
+			sig.recv = NewVar(m.pos, m.pkg, "", typ)
+		}
+	}
+
+	// sort for API stability
+	sortMethods(methods)
+
+	typ.methods = methods
+	typ.embeddeds = embeddeds
+	typ.complete = true
+
+	return typ
+}
+
+// NumExplicitMethods returns the number of explicitly declared methods of interface t.
+func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
+
+// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
+
+// NumEmbeddeds returns the number of embedded types in interface t.
+func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
+
+// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
+// The result is nil if the i'th embedded type is not a defined type.
+//
+// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
+func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
+
+// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
+func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
+
+// NumMethods returns the total number of methods of interface t.
+func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
+
+// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
+
+// Empty reports whether t is the empty interface.
+func (t *Interface) Empty() bool { return t.typeSet().IsAll() }
+
+// IsComparable reports whether each type in interface t's type set is comparable.
+func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
+
+// IsConstraint reports whether interface t is not just a method set.
+func (t *Interface) IsConstraint() bool { return !t.typeSet().IsMethodSet() }
+
+func (t *Interface) Underlying() Type { return t }
+func (t *Interface) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType, def *Named) {
+	var tlist []syntax.Expr // types collected from all type lists
+	var tname *syntax.Name  // most recent "type" name
+
+	addEmbedded := func(pos syntax.Pos, typ Type) {
+		ityp.embeddeds = append(ityp.embeddeds, typ)
+		if ityp.embedPos == nil {
+			ityp.embedPos = new([]syntax.Pos)
+		}
+		*ityp.embedPos = append(*ityp.embedPos, pos)
+	}
+
+	for _, f := range iface.MethodList {
+		if f.Name == nil {
+			// We have an embedded type; possibly a union of types.
+			addEmbedded(posFor(f.Type), parseUnion(check, flattenUnion(nil, f.Type)))
+			continue
+		}
+		// f.Name != nil
+
+		// We have a method with name f.Name, or a type of a type list (f.Name.Value == "type").
+		name := f.Name.Value
+		if name == "_" {
+			if check.conf.CompilerErrorMessages {
+				check.error(f.Name, "methods must have a unique non-blank name")
+			} else {
+				check.error(f.Name, "invalid method name _")
+			}
+			continue // ignore
+		}
+
+		// TODO(gri) Remove type list handling once the parser doesn't accept type lists anymore.
+		if name == "type" {
+			// Report an error for the first type list per interface
+			// if we don't allow type lists, but continue.
+			if !check.conf.AllowTypeLists && tlist == nil {
+				check.softErrorf(f.Name, "use generalized embedding syntax instead of a type list")
+			}
+			// For now, collect all type list entries as if it
+			// were a single union, where each union element is
+			// of the form ~T.
+			op := new(syntax.Operation)
+			// We should also set the position (but there is no setter);
+			// we don't care because this code will eventually go away.
+			op.Op = syntax.Tilde
+			op.X = f.Type
+			tlist = append(tlist, op)
+			// Report an error if we have multiple type lists in an
+			// interface, but only if they are permitted in the first place.
+			if check.conf.AllowTypeLists && tname != nil && tname != f.Name {
+				check.error(f.Name, "cannot have multiple type lists in an interface")
+			}
+			tname = f.Name
+			continue
+		}
+
+		typ := check.typ(f.Type)
+		sig, _ := typ.(*Signature)
+		if sig == nil {
+			if typ != Typ[Invalid] {
+				check.errorf(f.Type, invalidAST+"%s is not a method signature", typ)
+			}
+			continue // ignore
+		}
+
+		// Always type-check method type parameters but complain if they are not enabled.
+		// (This extra check is needed here because interface method signatures don't have
+		// a receiver specification.)
+		if sig.tparams != nil && !acceptMethodTypeParams {
+			check.error(f.Type, "methods cannot have type parameters")
+		}
+
+		// use named receiver type if available (for better error messages)
+		var recvTyp Type = ityp
+		if def != nil {
+			recvTyp = def
+		}
+		sig.recv = NewVar(f.Name.Pos(), check.pkg, "", recvTyp)
+
+		m := NewFunc(f.Name.Pos(), check.pkg, name, sig)
+		check.recordDef(f.Name, m)
+		ityp.methods = append(ityp.methods, m)
+	}
+
+	// If we saw a type list, add it like an embedded union.
+	if tlist != nil {
+		// Types T in a type list are added as ~T expressions but we don't
+		// have the position of the '~'. Use the first type position instead.
+		addEmbedded(tlist[0].(*syntax.Operation).X.Pos(), parseUnion(check, tlist))
+	}
+
+	// All methods and embedded elements for this interface are collected;
+	// i.e., this interface is may be used in a type set computation.
+	ityp.complete = true
+
+	if len(ityp.methods) == 0 && len(ityp.embeddeds) == 0 {
+		// empty interface
+		ityp.tset = &topTypeSet
+		return
+	}
+
+	// sort for API stability
+	// (don't sort embeddeds: they must correspond to *embedPos entries)
+	sortMethods(ityp.methods)
+
+	// Compute type set with a non-nil *Checker as soon as possible
+	// to report any errors. Subsequent uses of type sets will use
+	// this computed type set and won't need to pass in a *Checker.
+	check.later(func() { computeInterfaceTypeSet(check, iface.Pos(), ityp) })
+}
+
+func flattenUnion(list []syntax.Expr, x syntax.Expr) []syntax.Expr {
+	if o, _ := x.(*syntax.Operation); o != nil && o.Op == syntax.Or {
+		list = flattenUnion(list, o.X)
+		x = o.Y
+	}
+	return append(list, x)
+}
diff --git a/src/cmd/compile/internal/types2/issues_test.go b/src/cmd/compile/internal/types2/issues_test.go
index e716a48038510a2320c02524c4375d0bdaa9ef6f..9890b79323ac81dfe0347532b831b1cf2f635513 100644
--- a/src/cmd/compile/internal/types2/issues_test.go
+++ b/src/cmd/compile/internal/types2/issues_test.go
@@ -321,7 +321,7 @@ func TestIssue25627(t *testing.T) {
 			}
 		}
 
-		syntax.Walk(f, func(n syntax.Node) bool {
+		syntax.Crawl(f, func(n syntax.Node) bool {
 			if decl, _ := n.(*syntax.TypeDecl); decl != nil {
 				if tv, ok := info.Types[decl.Type]; ok && decl.Name.Value == "T" {
 					want := strings.Count(src, ";") + 1
@@ -402,8 +402,9 @@ func TestIssue28282(t *testing.T) {
 	// create type interface { error }
 	et := Universe.Lookup("error").Type()
 	it := NewInterfaceType(nil, []Type{et})
-	it.Complete()
 	// verify that after completing the interface, the embedded method remains unchanged
+	// (interfaces are "completed" lazily now, so the completion happens implicitly when
+	// accessing Method(0))
 	want := et.Underlying().(*Interface).Method(0)
 	got := it.Method(0)
 	if got != want {
diff --git a/src/cmd/compile/internal/types2/labels.go b/src/cmd/compile/internal/types2/labels.go
index d3206988b54b69d41fd525e6ba9beec487b3e8ba..6f02e2fc969b084f4c86496ff8e9cc0999be2f6c 100644
--- a/src/cmd/compile/internal/types2/labels.go
+++ b/src/cmd/compile/internal/types2/labels.go
@@ -32,7 +32,8 @@ func (check *Checker) labels(body *syntax.BlockStmt) {
 	}
 
 	// spec: "It is illegal to define a label that is never used."
-	for _, obj := range all.elems {
+	for name, obj := range all.elems {
+		obj = resolve(name, obj)
 		if lbl := obj.(*Label); !lbl.used {
 			check.softErrorf(lbl.pos, "label %s declared but not used", lbl.name)
 		}
diff --git a/src/cmd/compile/internal/types2/lookup.go b/src/cmd/compile/internal/types2/lookup.go
index 78299502e9c00d9ab176733912a31c60d2602a50..d0718e51e2d5848a583410a1bf781d495e35ed28 100644
--- a/src/cmd/compile/internal/types2/lookup.go
+++ b/src/cmd/compile/internal/types2/lookup.go
@@ -6,6 +6,11 @@
 
 package types2
 
+// Internal use of LookupFieldOrMethod: If the obj result is a method
+// associated with a concrete (non-interface) type, the method's signature
+// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
+// the method's type.
+
 // LookupFieldOrMethod looks up a field or method with given package and name
 // in T and returns the corresponding *Var or *Func, an index sequence, and a
 // bool indicating if there were any pointer indirections on the path to the
@@ -33,19 +38,6 @@ package types2
 //	the method's formal receiver base type, nor was the receiver addressable.
 //
 func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
-	return (*Checker)(nil).lookupFieldOrMethod(T, addressable, pkg, name)
-}
-
-// Internal use of Checker.lookupFieldOrMethod: If the obj result is a method
-// associated with a concrete (non-interface) type, the method's signature
-// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
-// the method's type.
-// TODO(gri) Now that we provide the *Checker, we can probably remove this
-// caveat by calling Checker.objDecl from lookupFieldOrMethod. Investigate.
-
-// lookupFieldOrMethod is like the external version but completes interfaces
-// as necessary.
-func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// Methods cannot be associated to a named pointer type
 	// (spec: "The type denoted by T is called the receiver base type;
 	// it must not be a pointer or interface type and it must be declared
@@ -54,8 +46,8 @@ func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package
 	// pointer type but discard the result if it is a method since we would
 	// not have found it for T (see also issue 8590).
 	if t := asNamed(T); t != nil {
-		if p, _ := t.underlying.(*Pointer); p != nil {
-			obj, index, indirect = check.rawLookupFieldOrMethod(p, false, pkg, name)
+		if p, _ := safeUnderlying(t).(*Pointer); p != nil {
+			obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
 			if _, ok := obj.(*Func); ok {
 				return nil, nil, false
 			}
@@ -63,7 +55,7 @@ func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package
 		}
 	}
 
-	return check.rawLookupFieldOrMethod(T, addressable, pkg, name)
+	return lookupFieldOrMethod(T, addressable, pkg, name)
 }
 
 // TODO(gri) The named type consolidation and seen maps below must be
@@ -71,10 +63,9 @@ func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package
 //           types always have only one representation (even when imported
 //           indirectly via different packages.)
 
-// rawLookupFieldOrMethod should only be called by lookupFieldOrMethod and missingMethod.
-func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+// lookupFieldOrMethod should only be called by LookupFieldOrMethod and missingMethod.
+func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// WARNING: The code in this function is extremely subtle - do not modify casually!
-	//          This function and NewMethodSet should be kept in sync.
 
 	if name == "_" {
 		return // blank fields/methods are never found
@@ -82,10 +73,15 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 
 	typ, isPtr := deref(T)
 
-	// *typ where typ is an interface has no methods.
-	// Be cautious: typ may be nil (issue 39634, crash #3).
-	if typ == nil || isPtr && IsInterface(typ) {
-		return
+	// *typ where typ is an interface or type parameter has no methods.
+	if isPtr {
+		// don't look at under(typ) here - was bug (issue #47747)
+		if _, ok := typ.(*TypeParam); ok {
+			return
+		}
+		if _, ok := under(typ).(*Interface); ok {
+			return
+		}
 	}
 
 	// Start with typ as single entry at shallowest depth.
@@ -126,6 +122,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 				seen[named] = true
 
 				// look for a matching attached method
+				named.load()
 				if i, m := lookupMethod(named.methods, pkg, name); m != nil {
 					// potential match
 					// caution: method may not have a proper signature yet
@@ -181,9 +178,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 
 			case *Interface:
 				// look for a matching method
-				// TODO(gri) t.allMethods is sorted - use binary search
-				check.completeInterface(nopos, t)
-				if i, m := lookupMethod(t.allMethods, pkg, name); m != nil {
+				if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -194,7 +189,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 				}
 
 			case *TypeParam:
-				if i, m := lookupMethod(t.Bound().allMethods, pkg, name); m != nil {
+				if i, m := t.iface().typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -229,7 +224,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 			return
 		}
 
-		current = check.consolidateMultiples(next)
+		current = consolidateMultiples(next)
 	}
 
 	return nil, nil, false // not found
@@ -246,7 +241,7 @@ type embeddedType struct {
 // consolidateMultiples collects multiple list entries with the same type
 // into a single entry marked as containing multiples. The result is the
 // consolidated list.
-func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
+func consolidateMultiples(list []embeddedType) []embeddedType {
 	if len(list) <= 1 {
 		return list // at most one entry - nothing to do
 	}
@@ -254,7 +249,7 @@ func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
 	n := 0                     // number of entries w/ unique type
 	prev := make(map[Type]int) // index at which type was previously seen
 	for _, e := range list {
-		if i, found := check.lookupType(prev, e.typ); found {
+		if i, found := lookupType(prev, e.typ); found {
 			list[i].multiples = true
 			// ignore this entry
 		} else {
@@ -266,14 +261,14 @@ func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
 	return list[:n]
 }
 
-func (check *Checker) lookupType(m map[Type]int, typ Type) (int, bool) {
+func lookupType(m map[Type]int, typ Type) (int, bool) {
 	// fast path: maybe the types are equal
 	if i, found := m[typ]; found {
 		return i, true
 	}
 
 	for t, i := range m {
-		if check.identical(t, typ) {
+		if Identical(t, typ) {
 			return i, true
 		}
 	}
@@ -306,22 +301,18 @@ func MissingMethod(V Type, T *Interface, static bool) (method *Func, wrongType b
 // To improve error messages, also report the wrong signature
 // when the method exists on *V instead of V.
 func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method, wrongType *Func) {
-	check.completeInterface(nopos, T)
-
 	// fast path for common case
 	if T.Empty() {
 		return
 	}
 
 	if ityp := asInterface(V); ityp != nil {
-		check.completeInterface(nopos, ityp)
-		// TODO(gri) allMethods is sorted - can do this more efficiently
-		for _, m := range T.allMethods {
-			_, f := lookupMethod(ityp.allMethods, m.pkg, m.name)
+		// TODO(gri) the methods are sorted - could do this more efficiently
+		for _, m := range T.typeSet().methods {
+			_, f := ityp.typeSet().LookupMethod(m.pkg, m.name)
 
 			if f == nil {
-				// if m is the magic method == we're ok (interfaces are comparable)
-				if m.name == "==" || !static {
+				if !static {
 					continue
 				}
 				return m, f
@@ -330,17 +321,20 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 			// both methods must have the same number of type parameters
 			ftyp := f.typ.(*Signature)
 			mtyp := m.typ.(*Signature)
-			if len(ftyp.tparams) != len(mtyp.tparams) {
+			if ftyp.TParams().Len() != mtyp.TParams().Len() {
 				return m, f
 			}
+			if !acceptMethodTypeParams && ftyp.TParams().Len() > 0 {
+				panic("method with type parameters")
+			}
 
 			// If the methods have type parameters we don't care whether they
 			// are the same or not, as long as they match up. Use unification
 			// to see if they can be made to match.
 			// TODO(gri) is this always correct? what about type bounds?
 			// (Alternative is to rename/subst type parameters and compare.)
-			u := newUnifier(check, true)
-			u.x.init(ftyp.tparams)
+			u := newUnifier(true)
+			u.x.init(ftyp.TParams().list())
 			if !u.unify(ftyp, mtyp) {
 				return m, f
 			}
@@ -352,14 +346,14 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 	// A concrete type implements T if it implements all methods of T.
 	Vd, _ := deref(V)
 	Vn := asNamed(Vd)
-	for _, m := range T.allMethods {
+	for _, m := range T.typeSet().methods {
 		// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
-		obj, _, _ := check.rawLookupFieldOrMethod(V, false, m.pkg, m.name)
+		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
 
 		// Check if *V implements this method of T.
 		if obj == nil {
 			ptr := NewPointer(V)
-			obj, _, _ = check.rawLookupFieldOrMethod(ptr, false, m.pkg, m.name)
+			obj, _, _ = lookupFieldOrMethod(ptr, false, m.pkg, m.name)
 			if obj != nil {
 				return m, obj.(*Func)
 			}
@@ -368,10 +362,6 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// we must have a method (not a field of matching function type)
 		f, _ := obj.(*Func)
 		if f == nil {
-			// if m is the magic method == and V is comparable, we're ok
-			if m.name == "==" && Comparable(V) {
-				continue
-			}
 			return m, nil
 		}
 
@@ -383,9 +373,12 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// both methods must have the same number of type parameters
 		ftyp := f.typ.(*Signature)
 		mtyp := m.typ.(*Signature)
-		if len(ftyp.tparams) != len(mtyp.tparams) {
+		if ftyp.TParams().Len() != mtyp.TParams().Len() {
 			return m, f
 		}
+		if !acceptMethodTypeParams && ftyp.TParams().Len() > 0 {
+			panic("method with type parameters")
+		}
 
 		// If V is a (instantiated) generic type, its methods are still
 		// parameterized using the original (declaration) receiver type
@@ -394,17 +387,17 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// In order to compare the signatures, substitute the receiver
 		// type parameters of ftyp with V's instantiation type arguments.
 		// This lazily instantiates the signature of method f.
-		if Vn != nil && len(Vn.tparams) > 0 {
+		if Vn != nil && Vn.TParams().Len() > 0 {
 			// Be careful: The number of type arguments may not match
 			// the number of receiver parameters. If so, an error was
 			// reported earlier but the length discrepancy is still
 			// here. Exit early in this case to prevent an assertion
 			// failure in makeSubstMap.
 			// TODO(gri) Can we avoid this check by fixing the lengths?
-			if len(ftyp.rparams) != len(Vn.targs) {
+			if len(ftyp.RParams().list()) != Vn.targs.Len() {
 				return
 			}
-			ftyp = check.subst(nopos, ftyp, makeSubstMap(ftyp.rparams, Vn.targs)).(*Signature)
+			ftyp = check.subst(nopos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs.list()), nil).(*Signature)
 		}
 
 		// If the methods have type parameters we don't care whether they
@@ -412,8 +405,21 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// to see if they can be made to match.
 		// TODO(gri) is this always correct? what about type bounds?
 		// (Alternative is to rename/subst type parameters and compare.)
-		u := newUnifier(check, true)
-		u.x.init(ftyp.tparams)
+		u := newUnifier(true)
+		if ftyp.TParams().Len() > 0 {
+			// We reach here only if we accept method type parameters.
+			// In this case, unification must consider any receiver
+			// and method type parameters as "free" type parameters.
+			assert(acceptMethodTypeParams)
+			// We don't have a test case for this at the moment since
+			// we can't parse method type parameters. Keeping the
+			// unimplemented call so that we test this code if we
+			// enable method type parameters.
+			unimplemented()
+			u.x.init(append(ftyp.RParams().list(), ftyp.TParams().list()...))
+		} else {
+			u.x.init(ftyp.RParams().list())
+		}
 		if !u.unify(ftyp, mtyp) {
 			return m, f
 		}
diff --git a/src/cmd/compile/internal/types2/map.go b/src/cmd/compile/internal/types2/map.go
new file mode 100644
index 0000000000000000000000000000000000000000..0d3464caae728b7b0207365264170337666953ad
--- /dev/null
+++ b/src/cmd/compile/internal/types2/map.go
@@ -0,0 +1,24 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Map represents a map type.
+type Map struct {
+	key, elem Type
+}
+
+// NewMap returns a new map for the given key and element types.
+func NewMap(key, elem Type) *Map {
+	return &Map{key: key, elem: elem}
+}
+
+// Key returns the key type of map m.
+func (m *Map) Key() Type { return m.key }
+
+// Elem returns the element type of map m.
+func (m *Map) Elem() Type { return m.elem }
+
+func (t *Map) Underlying() Type { return t }
+func (t *Map) String() string   { return TypeString(t, nil) }
diff --git a/src/cmd/compile/internal/types2/named.go b/src/cmd/compile/internal/types2/named.go
new file mode 100644
index 0000000000000000000000000000000000000000..a3a2595a22218b1ccd47e1be0594012c7c1d334e
--- /dev/null
+++ b/src/cmd/compile/internal/types2/named.go
@@ -0,0 +1,295 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"cmd/compile/internal/syntax"
+	"sync"
+)
+
+// TODO(gri) Clean up Named struct below; specifically the fromRHS field (can we use underlying?).
+
+// A Named represents a named (defined) type.
+type Named struct {
+	check      *Checker
+	info       typeInfo    // for cycle detection
+	obj        *TypeName   // corresponding declared object for declared types; placeholder for instantiated types
+	orig       *Named      // original, uninstantiated type
+	fromRHS    Type        // type (on RHS of declaration) this *Named type is derived from (for cycle reporting)
+	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
+	instance   *instance   // position information for lazy instantiation, or nil
+	tparams    *TParamList // type parameters, or nil
+	targs      *TypeList   // type arguments (after instantiation), or nil
+	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
+
+	resolve func(*Named) ([]*TypeParam, Type, []*Func)
+	once    sync.Once
+}
+
+// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
+// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
+// The underlying type must not be a *Named.
+func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
+	if _, ok := underlying.(*Named); ok {
+		panic("underlying type must not be *Named")
+	}
+	return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods)
+}
+
+func (t *Named) load() *Named {
+	// If t is an instantiated type, it derives its methods and tparams from its
+	// base type. Since we expect type parameters and methods to be set after a
+	// call to load, we must load the base and copy here.
+	//
+	// underlying is set when t is expanded.
+	//
+	// By convention, a type instance is loaded iff its tparams are set.
+	if t.targs.Len() > 0 && t.tparams == nil {
+		t.orig.load()
+		t.tparams = t.orig.tparams
+		t.methods = t.orig.methods
+	}
+	if t.resolve == nil {
+		return t
+	}
+
+	t.once.Do(func() {
+		// TODO(mdempsky): Since we're passing t to resolve anyway
+		// (necessary because types2 expects the receiver type for methods
+		// on defined interface types to be the Named rather than the
+		// underlying Interface), maybe it should just handle calling
+		// SetTParams, SetUnderlying, and AddMethod instead?  Those
+		// methods would need to support reentrant calls though.  It would
+		// also make the API more future-proof towards further extensions
+		// (like SetTParams).
+
+		tparams, underlying, methods := t.resolve(t)
+
+		switch underlying.(type) {
+		case nil, *Named:
+			panic("invalid underlying type")
+		}
+
+		t.tparams = bindTParams(tparams)
+		t.underlying = underlying
+		t.methods = methods
+	})
+	return t
+}
+
+// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
+func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams *TParamList, methods []*Func) *Named {
+	typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods}
+	if typ.orig == nil {
+		typ.orig = typ
+	}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	// Ensure that typ is always expanded, at which point the check field can be
+	// nilled out.
+	//
+	// Note that currently we cannot nil out check inside typ.under(), because
+	// it's possible that typ is expanded multiple times.
+	//
+	// TODO(gri): clean this up so that under is the only function mutating
+	//            named types.
+	if check != nil {
+		check.later(func() {
+			switch typ.under().(type) {
+			case *Named:
+				panic("unexpanded underlying type")
+			}
+			typ.check = nil
+		})
+	}
+	return typ
+}
+
+// Obj returns the type name for the declaration defining the named type t. For
+// instantiated types, this is the type name of the base type.
+func (t *Named) Obj() *TypeName {
+	return t.orig.obj // for non-instances this is the same as t.obj
+}
+
+// Orig returns the original generic type an instantiated type is derived from.
+// If t is not an instantiated type, the result is t.
+func (t *Named) Orig() *Named { return t.orig }
+
+// TODO(gri) Come up with a better representation and API to distinguish
+//           between parameterized instantiated and non-instantiated types.
+
+// TParams returns the type parameters of the named type t, or nil.
+// The result is non-nil for an (originally) parameterized type even if it is instantiated.
+func (t *Named) TParams() *TParamList { return t.load().tparams }
+
+// SetTParams sets the type parameters of the named type t.
+func (t *Named) SetTParams(tparams []*TypeParam) { t.load().tparams = bindTParams(tparams) }
+
+// TArgs returns the type arguments used to instantiate the named type t.
+func (t *Named) TArgs() *TypeList { return t.targs }
+
+// NumMethods returns the number of explicit methods whose receiver is named type t.
+func (t *Named) NumMethods() int { return len(t.load().methods) }
+
+// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
+func (t *Named) Method(i int) *Func { return t.load().methods[i] }
+
+// SetUnderlying sets the underlying type and marks t as complete.
+func (t *Named) SetUnderlying(underlying Type) {
+	if underlying == nil {
+		panic("underlying type must not be nil")
+	}
+	if _, ok := underlying.(*Named); ok {
+		panic("underlying type must not be *Named")
+	}
+	t.load().underlying = underlying
+}
+
+// AddMethod adds method m unless it is already in the method list.
+func (t *Named) AddMethod(m *Func) {
+	t.load()
+	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
+		t.methods = append(t.methods, m)
+	}
+}
+
+func (t *Named) Underlying() Type { return t.load().expand(nil).underlying }
+func (t *Named) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// under returns the expanded underlying type of n0; possibly by following
+// forward chains of named types. If an underlying type is found, resolve
+// the chain by setting the underlying type for each defined type in the
+// chain before returning it. If no underlying type is found or a cycle
+// is detected, the result is Typ[Invalid]. If a cycle is detected and
+// n0.check != nil, the cycle is reported.
+func (n0 *Named) under() Type {
+	u := n0.Underlying()
+
+	// If the underlying type of a defined type is not a defined
+	// (incl. instance) type, then that is the desired underlying
+	// type.
+	var n1 *Named
+	switch u1 := u.(type) {
+	case nil:
+		return Typ[Invalid]
+	default:
+		// common case
+		return u
+	case *Named:
+		// handled below
+		n1 = u1
+	}
+
+	if n0.check == nil {
+		panic("Named.check == nil but type is incomplete")
+	}
+
+	// Invariant: after this point n0 as well as any named types in its
+	// underlying chain should be set up when this function exits.
+	check := n0.check
+	n := n0
+
+	seen := make(map[*Named]int) // types that need their underlying resolved
+	var path []Object            // objects encountered, for cycle reporting
+
+loop:
+	for {
+		seen[n] = len(seen)
+		path = append(path, n.obj)
+		n = n1
+		if i, ok := seen[n]; ok {
+			// cycle
+			check.cycleError(path[i:])
+			u = Typ[Invalid]
+			break
+		}
+		u = n.Underlying()
+		switch u1 := u.(type) {
+		case nil:
+			u = Typ[Invalid]
+			break loop
+		default:
+			break loop
+		case *Named:
+			// Continue collecting *Named types in the chain.
+			n1 = u1
+		}
+	}
+
+	for n := range seen {
+		// We should never have to update the underlying type of an imported type;
+		// those underlying types should have been resolved during the import.
+		// Also, doing so would lead to a race condition (was issue #31749).
+		// Do this check always, not just in debug mode (it's cheap).
+		if n.obj.pkg != check.pkg {
+			panic("imported type with unresolved underlying type")
+		}
+		n.underlying = u
+	}
+
+	return u
+}
+
+func (n *Named) setUnderlying(typ Type) {
+	if n != nil {
+		n.underlying = typ
+	}
+}
+
+// instance holds position information for use in lazy instantiation.
+//
+// TODO(rfindley): instance is probably unnecessary now. See if it can be
+// eliminated.
+type instance struct {
+	pos syntax.Pos // position of type instantiation; for error reporting only
+}
+
+// expand ensures that the underlying type of n is instantiated.
+// The underlying type will be Typ[Invalid] if there was an error.
+func (n *Named) expand(typMap map[string]*Named) *Named {
+	if n.instance != nil {
+		// n must be loaded before instantiation, in order to have accurate
+		// tparams. This is done implicitly by the call to n.TParams, but making it
+		// explicit is harmless: load is idempotent.
+		n.load()
+		var u Type
+		if n.check.validateTArgLen(n.instance.pos, n.tparams.Len(), n.targs.Len()) {
+			if typMap == nil {
+				if n.check != nil {
+					typMap = n.check.typMap
+				} else {
+					// If we're instantiating lazily, we might be outside the scope of a
+					// type-checking pass. In that case we won't have a pre-existing
+					// typMap, but don't want to create a duplicate of the current instance
+					// in the process of expansion.
+					h := instantiatedHash(n.orig, n.targs.list())
+					typMap = map[string]*Named{h: n}
+				}
+			}
+			u = n.check.subst(n.instance.pos, n.orig.underlying, makeSubstMap(n.TParams().list(), n.targs.list()), typMap)
+		} else {
+			u = Typ[Invalid]
+		}
+		n.underlying = u
+		n.fromRHS = u
+		n.instance = nil
+	}
+	return n
+}
+
+// safeUnderlying returns the underlying of typ without expanding instances, to
+// avoid infinite recursion.
+//
+// TODO(rfindley): eliminate this function or give it a better name.
+func safeUnderlying(typ Type) Type {
+	if t, _ := typ.(*Named); t != nil {
+		return t.load().underlying
+	}
+	return typ.Underlying()
+}
diff --git a/src/cmd/compile/internal/types2/object.go b/src/cmd/compile/internal/types2/object.go
index 844bc34b6a3d1e7034880d667b48b1bedcef87f2..c1466f24edf16a3235a46f6ad1897fb802e7e87b 100644
--- a/src/cmd/compile/internal/types2/object.go
+++ b/src/cmd/compile/internal/types2/object.go
@@ -186,6 +186,45 @@ func (obj *object) sameId(pkg *Package, name string) bool {
 	return pkg.path == obj.pkg.path
 }
 
+// less reports whether object a is ordered before object b.
+//
+// Objects are ordered nil before non-nil, exported before
+// non-exported, then by name, and finally (for non-exported
+// functions) by package height and path.
+func (a *object) less(b *object) bool {
+	if a == b {
+		return false
+	}
+
+	// Nil before non-nil.
+	if a == nil {
+		return true
+	}
+	if b == nil {
+		return false
+	}
+
+	// Exported functions before non-exported.
+	ea := isExported(a.name)
+	eb := isExported(b.name)
+	if ea != eb {
+		return ea
+	}
+
+	// Order by name and then (for non-exported names) by package.
+	if a.name != b.name {
+		return a.name < b.name
+	}
+	if !ea {
+		if a.pkg.height != b.pkg.height {
+			return a.pkg.height < b.pkg.height
+		}
+		return a.pkg.path < b.pkg.path
+	}
+
+	return false
+}
+
 // A PkgName represents an imported Go package.
 // PkgNames don't have a type.
 type PkgName struct {
@@ -237,6 +276,14 @@ func NewTypeName(pos syntax.Pos, pkg *Package, name string, typ Type) *TypeName
 	return &TypeName{object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}}
 }
 
+// NewTypeNameLazy returns a new defined type like NewTypeName, but it
+// lazily calls resolve to finish constructing the Named object.
+func NewTypeNameLazy(pos syntax.Pos, pkg *Package, name string, resolve func(named *Named) (tparams []*TypeParam, underlying Type, methods []*Func)) *TypeName {
+	obj := NewTypeName(pos, pkg, name, nil)
+	NewNamed(obj, nil, nil).resolve = resolve
+	return obj
+}
+
 // IsAlias reports whether obj is an alias name for a type.
 func (obj *TypeName) IsAlias() bool {
 	switch t := obj.typ.(type) {
@@ -329,36 +376,6 @@ func (obj *Func) FullName() string {
 // Scope returns the scope of the function's body block.
 func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope }
 
-// Less reports whether function a is ordered before function b.
-//
-// Functions are ordered exported before non-exported, then by name,
-// and finally (for non-exported functions) by package path.
-//
-// TODO(gri) The compiler also sorts by package height before package
-//           path for non-exported names.
-func (a *Func) less(b *Func) bool {
-	if a == b {
-		return false
-	}
-
-	// Exported functions before non-exported.
-	ea := isExported(a.name)
-	eb := isExported(b.name)
-	if ea != eb {
-		return ea
-	}
-
-	// Order by name and then (for non-exported names) by package.
-	if a.name != b.name {
-		return a.name < b.name
-	}
-	if !ea {
-		return a.pkg.path < b.pkg.path
-	}
-
-	return false
-}
-
 func (*Func) isDependency() {} // a function may be a dependency of an initialization expression
 
 // A Label represents a declared label.
@@ -458,6 +475,9 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 		if _, ok := typ.(*Basic); ok {
 			return
 		}
+		if named, _ := typ.(*Named); named != nil && named.TParams().Len() > 0 {
+			writeTParamList(buf, named.TParams().list(), qf, nil)
+		}
 		if tname.IsAlias() {
 			buf.WriteString(" =")
 		} else {
diff --git a/src/cmd/compile/internal/types2/object_test.go b/src/cmd/compile/internal/types2/object_test.go
index 7f63c793325721dca1512a4628d970e31f523892..a86733a5c99a12824f36121d9a8f935910eb8599 100644
--- a/src/cmd/compile/internal/types2/object_test.go
+++ b/src/cmd/compile/internal/types2/object_test.go
@@ -25,7 +25,7 @@ func TestIsAlias(t *testing.T) {
 	check(Unsafe.Scope().Lookup("Pointer").(*TypeName), false)
 	for _, name := range Universe.Names() {
 		if obj, _ := Universe.Lookup(name).(*TypeName); obj != nil {
-			check(obj, name == "byte" || name == "rune")
+			check(obj, name == "any" || name == "byte" || name == "rune")
 		}
 	}
 
diff --git a/src/cmd/compile/internal/types2/operand.go b/src/cmd/compile/internal/types2/operand.go
index 455d8b5dd1df22c40fb3b0bf12d8f8b914ed1ea9..19326b83428e90ddc6b2df98ffc04634108a12a7 100644
--- a/src/cmd/compile/internal/types2/operand.go
+++ b/src/cmd/compile/internal/types2/operand.go
@@ -176,16 +176,20 @@ func operandString(x *operand, qf Qualifier) string {
 	if hasType {
 		if x.typ != Typ[Invalid] {
 			var intro string
-			switch {
-			case isGeneric(x.typ):
-				intro = " of generic type "
-			case asTypeParam(x.typ) != nil:
-				intro = " of type parameter type "
-			default:
+			var tpar *TypeParam
+			if isGeneric(x.typ) {
+				intro = " of parameterized type "
+			} else if tpar = asTypeParam(x.typ); tpar != nil {
+				intro = " of type parameter "
+			} else {
 				intro = " of type "
 			}
 			buf.WriteString(intro)
 			WriteType(&buf, x.typ, qf)
+			if tpar != nil {
+				buf.WriteString(" constrained by ")
+				WriteType(&buf, tpar.bound, qf) // do not compute interface type sets here
+			}
 		} else {
 			buf.WriteString(" with invalid type")
 		}
@@ -248,20 +252,35 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 
 	V := x.typ
 
+	const debugAssignableTo = false
+	if debugAssignableTo && check != nil {
+		check.dump("V = %s", V)
+		check.dump("T = %s", T)
+	}
+
 	// x's type is identical to T
-	if check.identical(V, T) {
+	if Identical(V, T) {
 		return true, 0
 	}
 
 	Vu := optype(V)
 	Tu := optype(T)
 
+	if debugAssignableTo && check != nil {
+		check.dump("Vu = %s", Vu)
+		check.dump("Tu = %s", Tu)
+	}
+
 	// x is an untyped value representable by a value of type T.
 	if isUntyped(Vu) {
-		if t, ok := Tu.(*Sum); ok {
-			return t.is(func(t Type) bool {
+		if t, ok := under(T).(*TypeParam); ok {
+			return t.is(func(t *term) bool {
 				// TODO(gri) this could probably be more efficient
-				ok, _ := x.assignableTo(check, t, reason)
+				if t.tilde {
+					// TODO(gri) We need to check assignability
+					//           for the underlying type of x.
+				}
+				ok, _ := x.assignableTo(check, t.typ, reason)
 				return ok
 			}), _IncompatibleAssign
 		}
@@ -272,7 +291,7 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 
 	// x's type V and T have identical underlying types
 	// and at least one of V or T is not a named type
-	if check.identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
+	if Identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
 		return true, 0
 	}
 
@@ -281,7 +300,7 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 		if m, wrongType := check.missingMethod(V, Ti, true); m != nil /* Implements(V, Ti) */ {
 			if reason != nil {
 				if wrongType != nil {
-					if check.identical(m.typ, wrongType.typ) {
+					if Identical(m.typ, wrongType.typ) {
 						*reason = fmt.Sprintf("missing method %s (%s has pointer receiver)", m.name, m.name)
 					} else {
 						*reason = fmt.Sprintf("wrong type for method %s (have %s, want %s)", m.Name(), wrongType.typ, m.typ)
@@ -300,7 +319,7 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 	// type, x's type V and T have identical element types,
 	// and at least one of V or T is not a named type
 	if Vc, ok := Vu.(*Chan); ok && Vc.dir == SendRecv {
-		if Tc, ok := Tu.(*Chan); ok && check.identical(Vc.elem, Tc.elem) {
+		if Tc, ok := Tu.(*Chan); ok && Identical(Vc.elem, Tc.elem) {
 			return !isNamed(V) || !isNamed(T), _InvalidChanAssign
 		}
 	}
diff --git a/src/cmd/compile/internal/types2/package.go b/src/cmd/compile/internal/types2/package.go
index 31b1e7178771f5db37264b4886b8b3604e03b4b3..8044e7e6a76ce25254bcacab3599d547698e64a6 100644
--- a/src/cmd/compile/internal/types2/package.go
+++ b/src/cmd/compile/internal/types2/package.go
@@ -13,8 +13,9 @@ type Package struct {
 	path     string
 	name     string
 	scope    *Scope
-	complete bool
 	imports  []*Package
+	height   int
+	complete bool
 	fake     bool // scope lookup errors are silently dropped if package is fake (internal use only)
 	cgo      bool // uses of this package will be rewritten into uses of declarations from _cgo_gotypes.go
 }
@@ -22,8 +23,14 @@ type Package struct {
 // NewPackage returns a new Package for the given package path and name.
 // The package is not complete and contains no explicit imports.
 func NewPackage(path, name string) *Package {
+	return NewPackageHeight(path, name, 0)
+}
+
+// NewPackageHeight is like NewPackage, but allows specifying the
+// package's height.
+func NewPackageHeight(path, name string, height int) *Package {
 	scope := NewScope(Universe, nopos, nopos, fmt.Sprintf("package %q", path))
-	return &Package{path: path, name: name, scope: scope}
+	return &Package{path: path, name: name, scope: scope, height: height}
 }
 
 // Path returns the package path.
@@ -32,13 +39,22 @@ func (pkg *Package) Path() string { return pkg.path }
 // Name returns the package name.
 func (pkg *Package) Name() string { return pkg.name }
 
+// Height returns the package height.
+func (pkg *Package) Height() int { return pkg.height }
+
 // SetName sets the package name.
 func (pkg *Package) SetName(name string) { pkg.name = name }
 
 // Scope returns the (complete or incomplete) package scope
 // holding the objects declared at package level (TypeNames,
 // Consts, Vars, and Funcs).
-func (pkg *Package) Scope() *Scope { return pkg.scope }
+// For a nil pkg receiver, Scope returns the Universe scope.
+func (pkg *Package) Scope() *Scope {
+	if pkg != nil {
+		return pkg.scope
+	}
+	return Universe
+}
 
 // A package is complete if its scope contains (at least) all
 // exported objects; otherwise it is incomplete.
diff --git a/src/cmd/compile/internal/types2/pointer.go b/src/cmd/compile/internal/types2/pointer.go
new file mode 100644
index 0000000000000000000000000000000000000000..63055fc6b056a76822d261a2913b502f9fab2476
--- /dev/null
+++ b/src/cmd/compile/internal/types2/pointer.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Pointer represents a pointer type.
+type Pointer struct {
+	base Type // element type
+}
+
+// NewPointer returns a new pointer type for the given element (base) type.
+func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
+
+// Elem returns the element type for the given pointer p.
+func (p *Pointer) Elem() Type { return p.base }
+
+func (p *Pointer) Underlying() Type { return p }
+func (p *Pointer) String() string   { return TypeString(p, nil) }
diff --git a/src/cmd/compile/internal/types2/predicates.go b/src/cmd/compile/internal/types2/predicates.go
index ae186a0b5d1efd402335101d6caa125ff277c3a2..3ccafef990c0073a931c0d51f59522f9db743af0 100644
--- a/src/cmd/compile/internal/types2/predicates.go
+++ b/src/cmd/compile/internal/types2/predicates.go
@@ -10,7 +10,7 @@ package types2
 // isNamed may be called with types that are not fully set up.
 func isNamed(typ Type) bool {
 	switch typ.(type) {
-	case *Basic, *Named, *TypeParam, *instance:
+	case *Basic, *Named, *TypeParam:
 		return true
 	}
 	return false
@@ -21,15 +21,15 @@ func isNamed(typ Type) bool {
 func isGeneric(typ Type) bool {
 	// A parameterized type is only instantiated if it doesn't have an instantiation already.
 	named, _ := typ.(*Named)
-	return named != nil && named.obj != nil && named.tparams != nil && named.targs == nil
+	return named != nil && named.obj != nil && named.targs == nil && named.TParams() != nil
 }
 
 func is(typ Type, what BasicInfo) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.info&what != 0
-	case *Sum:
-		return t.is(func(typ Type) bool { return is(typ, what) })
+	case *TypeParam:
+		return t.underIs(func(t Type) bool { return is(t, what) })
 	}
 	return false
 }
@@ -56,10 +56,7 @@ func isNumericOrString(typ Type) bool { return is(typ, IsNumeric|IsString) }
 // are not fully set up.
 func isTyped(typ Type) bool {
 	// isTyped is called with types that are not fully
-	// set up. Must not call Basic()!
-	// A *Named or *instance type is always typed, so
-	// we only need to check if we have a true *Basic
-	// type.
+	// set up. Must not call asBasic()!
 	t, _ := typ.(*Basic)
 	return t == nil || t.info&IsUntyped == 0
 }
@@ -96,19 +93,7 @@ func comparable(T Type, seen map[Type]bool) bool {
 	}
 	seen[T] = true
 
-	// If T is a type parameter not constrained by any type
-	// list (i.e., it's underlying type is the top type),
-	// T is comparable if it has the == method. Otherwise,
-	// the underlying type "wins". For instance
-	//
-	//     interface{ comparable; type []byte }
-	//
-	// is not comparable because []byte is not comparable.
-	if t := asTypeParam(T); t != nil && optype(t) == theTop {
-		return t.Bound().IsComparable()
-	}
-
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		// assume invalid types to be comparable
 		// to avoid follow-up errors
@@ -124,42 +109,25 @@ func comparable(T Type, seen map[Type]bool) bool {
 		return true
 	case *Array:
 		return comparable(t.elem, seen)
-	case *Sum:
-		pred := func(t Type) bool {
-			return comparable(t, seen)
-		}
-		return t.is(pred)
 	case *TypeParam:
-		return t.Bound().IsComparable()
+		return t.iface().IsComparable()
 	}
 	return false
 }
 
 // hasNil reports whether a type includes the nil value.
 func hasNil(typ Type) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.kind == UnsafePointer
 	case *Slice, *Pointer, *Signature, *Interface, *Map, *Chan:
 		return true
-	case *Sum:
-		return t.is(hasNil)
+	case *TypeParam:
+		return t.underIs(hasNil)
 	}
 	return false
 }
 
-// identical reports whether x and y are identical types.
-// Receivers of Signature types are ignored.
-func (check *Checker) identical(x, y Type) bool {
-	return check.identical0(x, y, true, nil)
-}
-
-// identicalIgnoreTags reports whether x and y are identical types if tags are ignored.
-// Receivers of Signature types are ignored.
-func (check *Checker) identicalIgnoreTags(x, y Type) bool {
-	return check.identical0(x, y, false, nil)
-}
-
 // An ifacePair is a node in a stack of interface type pairs compared for identity.
 type ifacePair struct {
 	x, y *Interface
@@ -171,11 +139,7 @@ func (p *ifacePair) identical(q *ifacePair) bool {
 }
 
 // For changes to this code the corresponding changes should be made to unifier.nify.
-func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
-	// types must be expanded for comparison
-	x = expandf(x)
-	y = expandf(y)
-
+func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	if x == y {
 		return true
 	}
@@ -195,13 +159,13 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 		if y, ok := y.(*Array); ok {
 			// If one or both array lengths are unknown (< 0) due to some error,
 			// assume they are the same to avoid spurious follow-on errors.
-			return (x.len < 0 || y.len < 0 || x.len == y.len) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return (x.len < 0 || y.len < 0 || x.len == y.len) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Slice:
 		// Two slice types are identical if they have identical element types.
 		if y, ok := y.(*Slice); ok {
-			return check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Struct:
@@ -216,7 +180,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 					if f.embedded != g.embedded ||
 						cmpTags && x.Tag(i) != y.Tag(i) ||
 						!f.sameId(g.pkg, g.name) ||
-						!check.identical0(f.typ, g.typ, cmpTags, p) {
+						!identical(f.typ, g.typ, cmpTags, p) {
 						return false
 					}
 				}
@@ -227,7 +191,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Pointer:
 		// Two pointer types are identical if they have identical base types.
 		if y, ok := y.(*Pointer); ok {
-			return check.identical0(x.base, y.base, cmpTags, p)
+			return identical(x.base, y.base, cmpTags, p)
 		}
 
 	case *Tuple:
@@ -238,7 +202,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 				if x != nil {
 					for i, v := range x.vars {
 						w := y.vars[i]
-						if !check.identical0(v.typ, w.typ, cmpTags, p) {
+						if !identical(v.typ, w.typ, cmpTags, p) {
 							return false
 						}
 					}
@@ -256,49 +220,27 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 		// parameter names.
 		if y, ok := y.(*Signature); ok {
 			return x.variadic == y.variadic &&
-				check.identicalTParams(x.tparams, y.tparams, cmpTags, p) &&
-				check.identical0(x.params, y.params, cmpTags, p) &&
-				check.identical0(x.results, y.results, cmpTags, p)
-		}
-
-	case *Sum:
-		// Two sum types are identical if they contain the same types.
-		// (Sum types always consist of at least two types. Also, the
-		// the set (list) of types in a sum type consists of unique
-		// types - each type appears exactly once. Thus, two sum types
-		// must contain the same number of types to have chance of
-		// being equal.
-		if y, ok := y.(*Sum); ok && len(x.types) == len(y.types) {
-			// Every type in x.types must be in y.types.
-			// Quadratic algorithm, but probably good enough for now.
-			// TODO(gri) we need a fast quick type ID/hash for all types.
-		L:
-			for _, x := range x.types {
-				for _, y := range y.types {
-					if Identical(x, y) {
-						continue L // x is in y.types
-					}
-				}
-				return false // x is not in y.types
-			}
-			return true
+				identicalTParams(x.TParams().list(), y.TParams().list(), cmpTags, p) &&
+				identical(x.params, y.params, cmpTags, p) &&
+				identical(x.results, y.results, cmpTags, p)
 		}
 
 	case *Interface:
+		// Two interface types are identical if they describe the same type sets.
+		// With the existing implementation restriction, this simplifies to:
+		//
 		// Two interface types are identical if they have the same set of methods with
-		// the same names and identical function types. Lower-case method names from
-		// different packages are always different. The order of the methods is irrelevant.
+		// the same names and identical function types, and if any type restrictions
+		// are the same. Lower-case method names from different packages are always
+		// different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if check != nil {
-				check.completeInterface(nopos, x)
-				check.completeInterface(nopos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !xset.terms.equal(yset.terms) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -335,7 +277,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 				}
 				for i, f := range a {
 					g := b[i]
-					if f.Id() != g.Id() || !check.identical0(f.typ, g.typ, cmpTags, q) {
+					if f.Id() != g.Id() || !identical(f.typ, g.typ, cmpTags, q) {
 						return false
 					}
 				}
@@ -346,20 +288,44 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Map:
 		// Two map types are identical if they have identical key and value types.
 		if y, ok := y.(*Map); ok {
-			return check.identical0(x.key, y.key, cmpTags, p) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.key, y.key, cmpTags, p) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Chan:
 		// Two channel types are identical if they have identical value types
 		// and the same direction.
 		if y, ok := y.(*Chan); ok {
-			return x.dir == y.dir && check.identical0(x.elem, y.elem, cmpTags, p)
+			return x.dir == y.dir && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Named:
 		// Two named types are identical if their type names originate
 		// in the same type declaration.
 		if y, ok := y.(*Named); ok {
+			x.expand(nil)
+			y.expand(nil)
+
+			xargs := x.TArgs().list()
+			yargs := y.TArgs().list()
+
+			if len(xargs) != len(yargs) {
+				return false
+			}
+
+			if len(xargs) > 0 {
+				// Instances are identical if their original type and type arguments
+				// are identical.
+				if !Identical(x.orig, y.orig) {
+					return false
+				}
+				for i, xa := range xargs {
+					if !Identical(xa, yargs[i]) {
+						return false
+					}
+				}
+				return true
+			}
+
 			// TODO(gri) Why is x == y not sufficient? And if it is,
 			//           we can just return false here because x == y
 			//           is caught in the very beginning of this function.
@@ -369,13 +335,9 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *TypeParam:
 		// nothing to do (x and y being equal is caught in the very beginning of this function)
 
-	// case *instance:
-	//	unreachable since types are expanded
-
-	case *bottom, *top:
-		// Either both types are theBottom, or both are theTop in which
-		// case the initial x == y check will have caught them. Otherwise
-		// they are not identical.
+	case *top:
+		// Either both types are theTop in which case the initial x == y check
+		// will have caught them. Otherwise they are not identical.
 
 	case nil:
 		// avoid a crash in case of nil type
@@ -387,13 +349,13 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	return false
 }
 
-func (check *Checker) identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
+func identicalTParams(x, y []*TypeParam, cmpTags bool, p *ifacePair) bool {
 	if len(x) != len(y) {
 		return false
 	}
 	for i, x := range x {
 		y := y[i]
-		if !check.identical0(x.typ.(*TypeParam).bound, y.typ.(*TypeParam).bound, cmpTags, p) {
+		if !identical(x.bound, y.bound, cmpTags, p) {
 			return false
 		}
 	}
diff --git a/src/cmd/compile/internal/types2/resolver.go b/src/cmd/compile/internal/types2/resolver.go
index fa30650bd444f3d995b1939e897783e6ef50b768..018a20cfb2dc69722ce32b9e15aa3985d6538205 100644
--- a/src/cmd/compile/internal/types2/resolver.go
+++ b/src/cmd/compile/internal/types2/resolver.go
@@ -196,6 +196,7 @@ func (check *Checker) importPackage(pos syntax.Pos, path, dir string) *Package {
 // methods with receiver base type names.
 func (check *Checker) collectObjects() {
 	pkg := check.pkg
+	pkg.height = 0
 
 	// pkgImports is the set of packages already imported by any package file seen
 	// so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
@@ -253,6 +254,15 @@ func (check *Checker) collectObjects() {
 					continue
 				}
 
+				if imp == Unsafe {
+					// typecheck ignores imports of package unsafe for
+					// calculating height.
+					// TODO(mdempsky): Revisit this. This seems fine, but I
+					// don't remember explicitly considering this case.
+				} else if h := imp.height + 1; h > pkg.height {
+					pkg.height = h
+				}
+
 				// local name overrides imported package name
 				name := imp.name
 				if s.LocalPkgName != nil {
@@ -265,7 +275,7 @@ func (check *Checker) collectObjects() {
 				}
 
 				if name == "init" {
-					check.error(s.LocalPkgName, "cannot import package as init - init must be a func")
+					check.error(s, "cannot import package as init - init must be a func")
 					continue
 				}
 
@@ -298,22 +308,26 @@ func (check *Checker) collectObjects() {
 						check.dotImportMap = make(map[dotImportKey]*PkgName)
 					}
 					// merge imported scope with file scope
-					for _, obj := range imp.scope.elems {
+					for name, obj := range imp.scope.elems {
+						// Note: Avoid eager resolve(name, obj) here, so we only
+						// resolve dot-imported objects as needed.
+
 						// A package scope may contain non-exported objects,
 						// do not import them!
-						if obj.Exported() {
+						if isExported(name) {
 							// declare dot-imported object
 							// (Do not use check.declare because it modifies the object
 							// via Object.setScopePos, which leads to a race condition;
 							// the object may be imported into more than one file scope
 							// concurrently. See issue #32154.)
-							if alt := fileScope.Insert(obj); alt != nil {
+							if alt := fileScope.Lookup(name); alt != nil {
 								var err error_
-								err.errorf(s.LocalPkgName, "%s redeclared in this block", obj.Name())
+								err.errorf(s.LocalPkgName, "%s redeclared in this block", alt.Name())
 								err.recordAltDecl(alt)
 								check.report(&err)
 							} else {
-								check.dotImportMap[dotImportKey{fileScope, obj}] = pkgName
+								fileScope.insert(name, obj)
+								check.dotImportMap[dotImportKey{fileScope, name}] = pkgName
 							}
 						}
 					}
@@ -459,8 +473,9 @@ func (check *Checker) collectObjects() {
 
 	// verify that objects in package and file scopes have different names
 	for _, scope := range fileScopes {
-		for _, obj := range scope.elems {
-			if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
+		for name, obj := range scope.elems {
+			if alt := pkg.scope.Lookup(name); alt != nil {
+				obj = resolve(name, obj)
 				var err error_
 				if pkg, ok := obj.(*PkgName); ok {
 					err.errorf(alt, "%s already declared through import of %s", alt.Name(), pkg.Imported())
diff --git a/src/cmd/compile/internal/types2/resolver_test.go b/src/cmd/compile/internal/types2/resolver_test.go
index aee435ff5fb6cd7e0aa6d0d34028290197e71968..a02abce081b8334e3bb57bb0444ff6bced209e79 100644
--- a/src/cmd/compile/internal/types2/resolver_test.go
+++ b/src/cmd/compile/internal/types2/resolver_test.go
@@ -143,7 +143,7 @@ func TestResolveIdents(t *testing.T) {
 
 	// check that qualified identifiers are resolved
 	for _, f := range files {
-		syntax.Walk(f, func(n syntax.Node) bool {
+		syntax.Crawl(f, func(n syntax.Node) bool {
 			if s, ok := n.(*syntax.SelectorExpr); ok {
 				if x, ok := s.X.(*syntax.Name); ok {
 					obj := uses[x]
@@ -177,7 +177,7 @@ func TestResolveIdents(t *testing.T) {
 	foundDefs := make(map[*syntax.Name]bool)
 	var both []string
 	for _, f := range files {
-		syntax.Walk(f, func(n syntax.Node) bool {
+		syntax.Crawl(f, func(n syntax.Node) bool {
 			if x, ok := n.(*syntax.Name); ok {
 				var objects int
 				if _, found := uses[x]; found {
diff --git a/src/cmd/compile/internal/types2/sanitize.go b/src/cmd/compile/internal/types2/sanitize.go
deleted file mode 100644
index 64a2dedc7d83d9972af155599757891b41e8a549..0000000000000000000000000000000000000000
--- a/src/cmd/compile/internal/types2/sanitize.go
+++ /dev/null
@@ -1,202 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package types2
-
-// sanitizeInfo walks the types contained in info to ensure that all instances
-// are expanded.
-//
-// This includes some objects that may be shared across concurrent
-// type-checking passes (such as those in the universe scope), so we are
-// careful here not to write types that are already sanitized. This avoids a
-// data race as any shared types should already be sanitized.
-func sanitizeInfo(info *Info) {
-	var s sanitizer = make(map[Type]Type)
-
-	// Note: Some map entries are not references.
-	// If modified, they must be assigned back.
-
-	for e, tv := range info.Types {
-		if typ := s.typ(tv.Type); typ != tv.Type {
-			tv.Type = typ
-			info.Types[e] = tv
-		}
-	}
-
-	for e, inf := range info.Inferred {
-		changed := false
-		for i, targ := range inf.Targs {
-			if typ := s.typ(targ); typ != targ {
-				inf.Targs[i] = typ
-				changed = true
-			}
-		}
-		if typ := s.typ(inf.Sig); typ != inf.Sig {
-			inf.Sig = typ.(*Signature)
-			changed = true
-		}
-		if changed {
-			info.Inferred[e] = inf
-		}
-	}
-
-	for _, obj := range info.Defs {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	for _, obj := range info.Uses {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	// TODO(gri) sanitize as needed
-	// - info.Implicits
-	// - info.Selections
-	// - info.Scopes
-	// - info.InitOrder
-}
-
-type sanitizer map[Type]Type
-
-func (s sanitizer) typ(typ Type) Type {
-	if typ == nil {
-		return nil
-	}
-
-	if t, found := s[typ]; found {
-		return t
-	}
-	s[typ] = typ
-
-	switch t := typ.(type) {
-	case *Basic, *bottom, *top:
-		// nothing to do
-
-	case *Array:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Slice:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Struct:
-		s.varList(t.fields)
-
-	case *Pointer:
-		if base := s.typ(t.base); base != t.base {
-			t.base = base
-		}
-
-	case *Tuple:
-		s.tuple(t)
-
-	case *Signature:
-		s.var_(t.recv)
-		s.tuple(t.params)
-		s.tuple(t.results)
-
-	case *Sum:
-		s.typeList(t.types)
-
-	case *Interface:
-		s.funcList(t.methods)
-		if types := s.typ(t.types); types != t.types {
-			t.types = types
-		}
-		s.typeList(t.embeddeds)
-		s.funcList(t.allMethods)
-		if allTypes := s.typ(t.allTypes); allTypes != t.allTypes {
-			t.allTypes = allTypes
-		}
-
-	case *Map:
-		if key := s.typ(t.key); key != t.key {
-			t.key = key
-		}
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Chan:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Named:
-		if orig := s.typ(t.fromRHS); orig != t.fromRHS {
-			t.fromRHS = orig
-		}
-		if under := s.typ(t.underlying); under != t.underlying {
-			t.underlying = under
-		}
-		s.typeList(t.targs)
-		s.funcList(t.methods)
-
-	case *TypeParam:
-		if bound := s.typ(t.bound); bound != t.bound {
-			t.bound = bound
-		}
-
-	case *instance:
-		typ = t.expand()
-		s[t] = typ
-
-	default:
-		panic("unimplemented")
-	}
-
-	return typ
-}
-
-func (s sanitizer) var_(v *Var) {
-	if v != nil {
-		if typ := s.typ(v.typ); typ != v.typ {
-			v.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) varList(list []*Var) {
-	for _, v := range list {
-		s.var_(v)
-	}
-}
-
-func (s sanitizer) tuple(t *Tuple) {
-	if t != nil {
-		s.varList(t.vars)
-	}
-}
-
-func (s sanitizer) func_(f *Func) {
-	if f != nil {
-		if typ := s.typ(f.typ); typ != f.typ {
-			f.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) funcList(list []*Func) {
-	for _, f := range list {
-		s.func_(f)
-	}
-}
-
-func (s sanitizer) typeList(list []Type) {
-	for i, t := range list {
-		if typ := s.typ(t); typ != t {
-			list[i] = typ
-		}
-	}
-}
diff --git a/src/cmd/compile/internal/types2/scope.go b/src/cmd/compile/internal/types2/scope.go
index ade0a79b31d11daf4fab28c7094d15b8175f22b7..095875d94b0d9ecec9d318d6456a0420abbd7442 100644
--- a/src/cmd/compile/internal/types2/scope.go
+++ b/src/cmd/compile/internal/types2/scope.go
@@ -13,6 +13,7 @@ import (
 	"io"
 	"sort"
 	"strings"
+	"sync"
 )
 
 // A Scope maintains a set of objects and links to its containing
@@ -22,6 +23,7 @@ import (
 type Scope struct {
 	parent   *Scope
 	children []*Scope
+	number   int               // parent.children[number-1] is this scope; 0 if there is no parent
 	elems    map[string]Object // lazily allocated
 	pos, end syntax.Pos        // scope extent; may be invalid
 	comment  string            // for debugging only
@@ -31,10 +33,11 @@ type Scope struct {
 // NewScope returns a new, empty scope contained in the given parent
 // scope, if any. The comment is for debugging only.
 func NewScope(parent *Scope, pos, end syntax.Pos, comment string) *Scope {
-	s := &Scope{parent, nil, nil, pos, end, comment, false}
+	s := &Scope{parent, nil, 0, nil, pos, end, comment, false}
 	// don't add children to Universe scope!
 	if parent != nil && parent != Universe {
 		parent.children = append(parent.children, s)
+		s.number = len(parent.children)
 	}
 	return s
 }
@@ -66,7 +69,7 @@ func (s *Scope) Child(i int) *Scope { return s.children[i] }
 // Lookup returns the object in scope s with the given name if such an
 // object exists; otherwise the result is nil.
 func (s *Scope) Lookup(name string) Object {
-	return s.elems[name]
+	return resolve(name, s.elems[name])
 }
 
 // LookupParent follows the parent chain of scopes starting with s until
@@ -81,7 +84,7 @@ func (s *Scope) Lookup(name string) Object {
 // whose scope is the scope of the package that exported them.
 func (s *Scope) LookupParent(name string, pos syntax.Pos) (*Scope, Object) {
 	for ; s != nil; s = s.parent {
-		if obj := s.elems[name]; obj != nil && (!pos.IsKnown() || obj.scopePos().Cmp(pos) <= 0) {
+		if obj := s.Lookup(name); obj != nil && (!pos.IsKnown() || obj.scopePos().Cmp(pos) <= 0) {
 			return s, obj
 		}
 	}
@@ -95,19 +98,38 @@ func (s *Scope) LookupParent(name string, pos syntax.Pos) (*Scope, Object) {
 // if not already set, and returns nil.
 func (s *Scope) Insert(obj Object) Object {
 	name := obj.Name()
-	if alt := s.elems[name]; alt != nil {
+	if alt := s.Lookup(name); alt != nil {
 		return alt
 	}
-	if s.elems == nil {
-		s.elems = make(map[string]Object)
-	}
-	s.elems[name] = obj
+	s.insert(name, obj)
 	if obj.Parent() == nil {
 		obj.setParent(s)
 	}
 	return nil
 }
 
+// InsertLazy is like Insert, but allows deferring construction of the
+// inserted object until it's accessed with Lookup. The Object
+// returned by resolve must have the same name as given to InsertLazy.
+// If s already contains an alternative object with the same name,
+// InsertLazy leaves s unchanged and returns false. Otherwise it
+// records the binding and returns true. The object's parent scope
+// will be set to s after resolve is called.
+func (s *Scope) InsertLazy(name string, resolve func() Object) bool {
+	if s.elems[name] != nil {
+		return false
+	}
+	s.insert(name, &lazyObject{parent: s, resolve: resolve})
+	return true
+}
+
+func (s *Scope) insert(name string, obj Object) {
+	if s.elems == nil {
+		s.elems = make(map[string]Object)
+	}
+	s.elems[name] = obj
+}
+
 // Squash merges s with its parent scope p by adding all
 // objects of s to p, adding all children of s to the
 // children of p, and removing s from p's children.
@@ -117,7 +139,8 @@ func (s *Scope) Insert(obj Object) Object {
 func (s *Scope) Squash(err func(obj, alt Object)) {
 	p := s.parent
 	assert(p != nil)
-	for _, obj := range s.elems {
+	for name, obj := range s.elems {
+		obj = resolve(name, obj)
 		obj.setParent(nil)
 		if alt := p.Insert(obj); alt != nil {
 			err(obj, alt)
@@ -196,7 +219,7 @@ func (s *Scope) WriteTo(w io.Writer, n int, recurse bool) {
 
 	indn1 := indn + ind
 	for _, name := range s.Names() {
-		fmt.Fprintf(w, "%s%s\n", indn1, s.elems[name])
+		fmt.Fprintf(w, "%s%s\n", indn1, s.Lookup(name))
 	}
 
 	if recurse {
@@ -214,3 +237,57 @@ func (s *Scope) String() string {
 	s.WriteTo(&buf, 0, false)
 	return buf.String()
 }
+
+// A lazyObject represents an imported Object that has not been fully
+// resolved yet by its importer.
+type lazyObject struct {
+	parent  *Scope
+	resolve func() Object
+	obj     Object
+	once    sync.Once
+}
+
+// resolve returns the Object represented by obj, resolving lazy
+// objects as appropriate.
+func resolve(name string, obj Object) Object {
+	if lazy, ok := obj.(*lazyObject); ok {
+		lazy.once.Do(func() {
+			obj := lazy.resolve()
+
+			if _, ok := obj.(*lazyObject); ok {
+				panic("recursive lazy object")
+			}
+			if obj.Name() != name {
+				panic("lazy object has unexpected name")
+			}
+
+			if obj.Parent() == nil {
+				obj.setParent(lazy.parent)
+			}
+			lazy.obj = obj
+		})
+
+		obj = lazy.obj
+	}
+	return obj
+}
+
+// stub implementations so *lazyObject implements Object and we can
+// store them directly into Scope.elems.
+func (*lazyObject) Parent() *Scope                        { panic("unreachable") }
+func (*lazyObject) Pos() syntax.Pos                       { panic("unreachable") }
+func (*lazyObject) Pkg() *Package                         { panic("unreachable") }
+func (*lazyObject) Name() string                          { panic("unreachable") }
+func (*lazyObject) Type() Type                            { panic("unreachable") }
+func (*lazyObject) Exported() bool                        { panic("unreachable") }
+func (*lazyObject) Id() string                            { panic("unreachable") }
+func (*lazyObject) String() string                        { panic("unreachable") }
+func (*lazyObject) order() uint32                         { panic("unreachable") }
+func (*lazyObject) color() color                          { panic("unreachable") }
+func (*lazyObject) setType(Type)                          { panic("unreachable") }
+func (*lazyObject) setOrder(uint32)                       { panic("unreachable") }
+func (*lazyObject) setColor(color color)                  { panic("unreachable") }
+func (*lazyObject) setParent(*Scope)                      { panic("unreachable") }
+func (*lazyObject) sameId(pkg *Package, name string) bool { panic("unreachable") }
+func (*lazyObject) scopePos() syntax.Pos                  { panic("unreachable") }
+func (*lazyObject) setScopePos(pos syntax.Pos)            { panic("unreachable") }
diff --git a/src/cmd/compile/internal/types2/signature.go b/src/cmd/compile/internal/types2/signature.go
new file mode 100644
index 0000000000000000000000000000000000000000..f1bf60ae8e38743557d7e453d762efc7c64f6ffa
--- /dev/null
+++ b/src/cmd/compile/internal/types2/signature.go
@@ -0,0 +1,393 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"cmd/compile/internal/syntax"
+	"fmt"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Signature represents a (non-builtin) function or method type.
+// The receiver is ignored when comparing signatures for identity.
+type Signature struct {
+	// We need to keep the scope in Signature (rather than passing it around
+	// and store it in the Func Object) because when type-checking a function
+	// literal we call the general type checker which returns a general Type.
+	// We then unpack the *Signature and use the scope for the literal body.
+	rparams  *TParamList // receiver type parameters from left to right, or nil
+	tparams  *TParamList // type parameters from left to right, or nil
+	scope    *Scope      // function scope, present for package-local signatures
+	recv     *Var        // nil if not a method
+	params   *Tuple      // (incoming) parameters from left to right; or nil
+	results  *Tuple      // (outgoing) results from left to right; or nil
+	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
+}
+
+// NewSignature returns a new function type for the given receiver, parameters,
+// and results, either of which may be nil. If variadic is set, the function
+// is variadic, it must have at least one parameter, and the last parameter
+// must be of unnamed slice type.
+func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
+	if variadic {
+		n := params.Len()
+		if n == 0 {
+			panic("variadic function must have at least one parameter")
+		}
+		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
+			panic("variadic parameter must be of unnamed slice type")
+		}
+	}
+	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
+}
+
+// Recv returns the receiver of signature s (if a method), or nil if a
+// function. It is ignored when comparing signatures for identity.
+//
+// For an abstract method, Recv returns the enclosing interface either
+// as a *Named or an *Interface. Due to embedding, an interface may
+// contain methods whose receiver type is a different interface.
+func (s *Signature) Recv() *Var { return s.recv }
+
+// TParams returns the type parameters of signature s, or nil.
+func (s *Signature) TParams() *TParamList { return s.tparams }
+
+// SetTParams sets the type parameters of signature s.
+func (s *Signature) SetTParams(tparams []*TypeParam) { s.tparams = bindTParams(tparams) }
+
+// RParams returns the receiver type parameters of signature s, or nil.
+func (s *Signature) RParams() *TParamList { return s.rparams }
+
+// SetRParams sets the receiver type params of signature s.
+func (s *Signature) SetRParams(rparams []*TypeParam) { s.rparams = bindTParams(rparams) }
+
+// Params returns the parameters of signature s, or nil.
+func (s *Signature) Params() *Tuple { return s.params }
+
+// Results returns the results of signature s, or nil.
+func (s *Signature) Results() *Tuple { return s.results }
+
+// Variadic reports whether the signature s is variadic.
+func (s *Signature) Variadic() bool { return s.variadic }
+
+func (s *Signature) Underlying() Type { return s }
+func (s *Signature) String() string   { return TypeString(s, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// Disabled by default, but enabled when running tests (via types_test.go).
+var acceptMethodTypeParams bool
+
+// funcType type-checks a function or method type.
+func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) {
+	check.openScope(ftyp, "function")
+	check.scope.isFunc = true
+	check.recordScope(ftyp, check.scope)
+	sig.scope = check.scope
+	defer check.closeScope()
+
+	var recvTyp syntax.Expr // rewritten receiver type; valid if != nil
+	if recvPar != nil {
+		// collect generic receiver type parameters, if any
+		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
+		// - the receiver specification acts as local declaration for its type parameters, which may be blank
+		_, rname, rparams := check.unpackRecv(recvPar.Type, true)
+		if len(rparams) > 0 {
+			// Blank identifiers don't get declared and regular type-checking of the instantiated
+			// parameterized receiver type expression fails in Checker.collectParams of receiver.
+			// Identify blank type parameters and substitute each with a unique new identifier named
+			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
+			// name.
+			var smap map[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers
+			for i, p := range rparams {
+				if p.Value == "_" {
+					new := *p
+					new.Value = fmt.Sprintf("%d_", i)
+					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
+					if smap == nil {
+						smap = make(map[*syntax.Name]*syntax.Name)
+					}
+					smap[p] = &new
+				}
+			}
+			if smap != nil {
+				// blank identifiers were found => use rewritten receiver type
+				recvTyp = isubst(recvPar.Type, smap)
+			}
+			rlist := make([]*TypeParam, len(rparams))
+			for i, rparam := range rparams {
+				rlist[i] = check.declareTypeParam(rparam)
+			}
+			sig.rparams = bindTParams(rlist)
+			// determine receiver type to get its type parameters
+			// and the respective type parameter bounds
+			var recvTParams []*TypeParam
+			if rname != nil {
+				// recv should be a Named type (otherwise an error is reported elsewhere)
+				// Also: Don't report an error via genericType since it will be reported
+				//       again when we type-check the signature.
+				// TODO(gri) maybe the receiver should be marked as invalid instead?
+				if recv := asNamed(check.genericType(rname, false)); recv != nil {
+					recvTParams = recv.TParams().list()
+				}
+			}
+			// provide type parameter bounds
+			// - only do this if we have the right number (otherwise an error is reported elsewhere)
+			if sig.RParams().Len() == len(recvTParams) {
+				// We have a list of *TypeNames but we need a list of Types.
+				list := make([]Type, sig.RParams().Len())
+				for i, t := range sig.RParams().list() {
+					list[i] = t
+				}
+				smap := makeSubstMap(recvTParams, list)
+				for i, tpar := range sig.RParams().list() {
+					bound := recvTParams[i].bound
+					// bound is (possibly) parameterized in the context of the
+					// receiver type declaration. Substitute parameters for the
+					// current context.
+					// TODO(gri) should we assume now that bounds always exist?
+					//           (no bound == empty interface)
+					if bound != nil {
+						bound = check.subst(tpar.obj.pos, bound, smap, nil)
+						tpar.bound = bound
+					}
+				}
+			}
+		}
+	}
+
+	if tparams != nil {
+		sig.tparams = check.collectTypeParams(tparams)
+		// Always type-check method type parameters but complain if they are not enabled.
+		// (A separate check is needed when type-checking interface method signatures because
+		// they don't have a receiver specification.)
+		if recvPar != nil && !acceptMethodTypeParams {
+			check.error(ftyp, "methods cannot have type parameters")
+		}
+	}
+
+	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
+	// declarations and then squash that scope into the parent scope (and report any redeclarations at
+	// that time).
+	scope := NewScope(check.scope, nopos, nopos, "function body (temp. scope)")
+	var recvList []*Var // TODO(gri) remove the need for making a list here
+	if recvPar != nil {
+		recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any
+	}
+	params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true)
+	results, _ := check.collectParams(scope, ftyp.ResultList, nil, false)
+	scope.Squash(func(obj, alt Object) {
+		var err error_
+		err.errorf(obj, "%s redeclared in this block", obj.Name())
+		err.recordAltDecl(alt)
+		check.report(&err)
+	})
+
+	if recvPar != nil {
+		// recv parameter list present (may be empty)
+		// spec: "The receiver is specified via an extra parameter section preceding the
+		// method name. That parameter section must declare a single parameter, the receiver."
+		var recv *Var
+		switch len(recvList) {
+		case 0:
+			// error reported by resolver
+			recv = NewParam(nopos, nil, "", Typ[Invalid]) // ignore recv below
+		default:
+			// more than one receiver
+			check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver")
+			fallthrough // continue with first receiver
+		case 1:
+			recv = recvList[0]
+		}
+
+		// TODO(gri) We should delay rtyp expansion to when we actually need the
+		//           receiver; thus all checks here should be delayed to later.
+		rtyp, _ := deref(recv.typ)
+
+		// spec: "The receiver type must be of the form T or *T where T is a type name."
+		// (ignore invalid types - error was reported before)
+		if rtyp != Typ[Invalid] {
+			var err string
+			switch T := rtyp.(type) {
+			case *Named:
+				T.expand(nil)
+				// spec: "The type denoted by T is called the receiver base type; it must not
+				// be a pointer or interface type and it must be declared in the same package
+				// as the method."
+				if T.obj.pkg != check.pkg {
+					err = "type not defined in this package"
+					if check.conf.CompilerErrorMessages {
+						check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+						err = ""
+					}
+				} else {
+					// The underlying type of a receiver base type can be a type parameter;
+					// e.g. for methods with a generic receiver T[P] with type T[P any] P.
+					underIs(T, func(u Type) bool {
+						switch u := u.(type) {
+						case *Basic:
+							// unsafe.Pointer is treated like a regular pointer
+							if u.kind == UnsafePointer {
+								err = "unsafe.Pointer"
+								return false
+							}
+						case *Pointer, *Interface:
+							err = "pointer or interface type"
+							return false
+						}
+						return true
+					})
+				}
+			case *Basic:
+				err = "basic or unnamed type"
+				if check.conf.CompilerErrorMessages {
+					check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+					err = ""
+				}
+			default:
+				check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
+			}
+			if err != "" {
+				check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err)
+				// ok to continue
+			}
+		}
+		sig.recv = recv
+	}
+
+	sig.params = NewTuple(params...)
+	sig.results = NewTuple(results...)
+	sig.variadic = variadic
+}
+
+// collectParams declares the parameters of list in scope and returns the corresponding
+// variable list. If type0 != nil, it is used instead of the first type in list.
+func (check *Checker) collectParams(scope *Scope, list []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) {
+	if list == nil {
+		return
+	}
+
+	var named, anonymous bool
+
+	var typ Type
+	var prev syntax.Expr
+	for i, field := range list {
+		ftype := field.Type
+		// type-check type of grouped fields only once
+		if ftype != prev {
+			prev = ftype
+			if i == 0 && type0 != nil {
+				ftype = type0
+			}
+			if t, _ := ftype.(*syntax.DotsType); t != nil {
+				ftype = t.Elem
+				if variadicOk && i == len(list)-1 {
+					variadic = true
+				} else {
+					check.softErrorf(t, "can only use ... with final parameter in list")
+					// ignore ... and continue
+				}
+			}
+			typ = check.varType(ftype)
+		}
+		// The parser ensures that f.Tag is nil and we don't
+		// care if a constructed AST contains a non-nil tag.
+		if field.Name != nil {
+			// named parameter
+			name := field.Name.Value
+			if name == "" {
+				check.error(field.Name, invalidAST+"anonymous parameter")
+				// ok to continue
+			}
+			par := NewParam(field.Name.Pos(), check.pkg, name, typ)
+			check.declare(scope, field.Name, par, scope.pos)
+			params = append(params, par)
+			named = true
+		} else {
+			// anonymous parameter
+			par := NewParam(field.Pos(), check.pkg, "", typ)
+			check.recordImplicit(field, par)
+			params = append(params, par)
+			anonymous = true
+		}
+	}
+
+	if named && anonymous {
+		check.error(list[0], invalidAST+"list contains both named and anonymous parameters")
+		// ok to continue
+	}
+
+	// For a variadic function, change the last parameter's type from T to []T.
+	// Since we type-checked T rather than ...T, we also need to retro-actively
+	// record the type for ...T.
+	if variadic {
+		last := params[len(params)-1]
+		last.typ = &Slice{elem: last.typ}
+		check.recordTypeAndValue(list[len(list)-1].Type, typexpr, last.typ, nil)
+	}
+
+	return
+}
+
+// isubst returns an x with identifiers substituted per the substitution map smap.
+// isubst only handles the case of (valid) method receiver type expressions correctly.
+func isubst(x syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr {
+	switch n := x.(type) {
+	case *syntax.Name:
+		if alt := smap[n]; alt != nil {
+			return alt
+		}
+	// case *syntax.StarExpr:
+	// 	X := isubst(n.X, smap)
+	// 	if X != n.X {
+	// 		new := *n
+	// 		new.X = X
+	// 		return &new
+	// 	}
+	case *syntax.Operation:
+		if n.Op == syntax.Mul && n.Y == nil {
+			X := isubst(n.X, smap)
+			if X != n.X {
+				new := *n
+				new.X = X
+				return &new
+			}
+		}
+	case *syntax.IndexExpr:
+		Index := isubst(n.Index, smap)
+		if Index != n.Index {
+			new := *n
+			new.Index = Index
+			return &new
+		}
+	case *syntax.ListExpr:
+		var elems []syntax.Expr
+		for i, elem := range n.ElemList {
+			new := isubst(elem, smap)
+			if new != elem {
+				if elems == nil {
+					elems = make([]syntax.Expr, len(n.ElemList))
+					copy(elems, n.ElemList)
+				}
+				elems[i] = new
+			}
+		}
+		if elems != nil {
+			new := *n
+			new.ElemList = elems
+			return &new
+		}
+	case *syntax.ParenExpr:
+		return isubst(n.X, smap) // no need to keep parentheses
+	default:
+		// Other receiver type expressions are invalid.
+		// It's fine to ignore those here as they will
+		// be checked elsewhere.
+	}
+	return x
+}
diff --git a/src/cmd/compile/internal/types2/sizeof_test.go b/src/cmd/compile/internal/types2/sizeof_test.go
index 236feb0404ebbd84d894690d7227a352a29ba896..5be369d84389c873b7395212a6779ccdb5611cd3 100644
--- a/src/cmd/compile/internal/types2/sizeof_test.go
+++ b/src/cmd/compile/internal/types2/sizeof_test.go
@@ -26,15 +26,14 @@ func TestSizeof(t *testing.T) {
 		{Struct{}, 24, 48},
 		{Pointer{}, 8, 16},
 		{Tuple{}, 12, 24},
-		{Signature{}, 44, 88},
-		{Sum{}, 12, 24},
-		{Interface{}, 60, 120},
+		{Signature{}, 28, 56},
+		{Union{}, 16, 32},
+		{Interface{}, 40, 80},
 		{Map{}, 16, 32},
 		{Chan{}, 12, 24},
-		{Named{}, 68, 136},
+		{Named{}, 72, 136},
 		{TypeParam{}, 28, 48},
-		{instance{}, 52, 96},
-		{bottom{}, 0, 0},
+		{term{}, 12, 24},
 		{top{}, 0, 0},
 
 		// Objects
@@ -48,8 +47,9 @@ func TestSizeof(t *testing.T) {
 		{Nil{}, 56, 88},
 
 		// Misc
-		{Scope{}, 56, 96},
+		{Scope{}, 60, 104},
 		{Package{}, 40, 80},
+		{_TypeSet{}, 28, 56},
 	}
 
 	for _, test := range tests {
diff --git a/src/cmd/compile/internal/types2/sizes.go b/src/cmd/compile/internal/types2/sizes.go
index aa0fbf40fced43115bd43e899920214bd11e5b47..6a3d19d8eaf293971266e4424ab57e97698092b1 100644
--- a/src/cmd/compile/internal/types2/sizes.go
+++ b/src/cmd/compile/internal/types2/sizes.go
@@ -48,7 +48,7 @@ type StdSizes struct {
 func (s *StdSizes) Alignof(T Type) int64 {
 	// For arrays and structs, alignment is defined in terms
 	// of alignment of the elements and fields, respectively.
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Array:
 		// spec: "For a variable x of array type: unsafe.Alignof(x)
 		// is the same as unsafe.Alignof(x[0]), but at least 1."
@@ -73,6 +73,8 @@ func (s *StdSizes) Alignof(T Type) int64 {
 		if t.Info()&IsString != 0 {
 			return s.WordSize
 		}
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	a := s.Sizeof(T) // may be 0
 	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
@@ -118,7 +120,7 @@ var basicSizes = [...]byte{
 }
 
 func (s *StdSizes) Sizeof(T Type) int64 {
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		assert(isTyped(T))
 		k := t.kind
@@ -148,10 +150,10 @@ func (s *StdSizes) Sizeof(T Type) int64 {
 		}
 		offsets := s.Offsetsof(t.fields)
 		return offsets[n-1] + s.Sizeof(t.fields[n-1].typ)
-	case *Sum:
-		panic("Sizeof unimplemented for type sum")
 	case *Interface:
 		return s.WordSize * 2
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	return s.WordSize // catch-all
 }
diff --git a/src/cmd/compile/internal/types2/slice.go b/src/cmd/compile/internal/types2/slice.go
new file mode 100644
index 0000000000000000000000000000000000000000..9c22a6fb1b6853f06a03fa0c0f7967aeed1b1aeb
--- /dev/null
+++ b/src/cmd/compile/internal/types2/slice.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Slice represents a slice type.
+type Slice struct {
+	elem Type
+}
+
+// NewSlice returns a new slice type for the given element type.
+func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
+
+// Elem returns the element type of slice s.
+func (s *Slice) Elem() Type { return s.elem }
+
+func (s *Slice) Underlying() Type { return s }
+func (s *Slice) String() string   { return TypeString(s, nil) }
diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index c3e646c80c142d91434991bc5f37d57ab20d4225..7865c2d4f45fe399ae96e77d0993f0585b5a026d 100644
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -14,7 +14,7 @@ import (
 
 func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body *syntax.BlockStmt, iota constant.Value) {
 	if check.conf.IgnoreFuncBodies {
-		panic("internal error: function body not ignored")
+		panic("function body not ignored")
 	}
 
 	if check.conf.Trace {
@@ -64,7 +64,8 @@ func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body
 
 func (check *Checker) usage(scope *Scope) {
 	var unused []*Var
-	for _, elem := range scope.elems {
+	for name, elem := range scope.elems {
+		elem = resolve(name, elem)
 		if v, _ := elem.(*Var); v != nil && !v.used {
 			unused = append(unused, v)
 		}
@@ -255,7 +256,7 @@ L:
 			// look for duplicate types for a given value
 			// (quadratic algorithm, but these lists tend to be very short)
 			for _, vt := range seen[val] {
-				if check.identical(v.typ, vt.typ) {
+				if Identical(v.typ, vt.typ) {
 					var err error_
 					err.errorf(&v, "duplicate case %s in expression switch", &v)
 					err.errorf(vt.pos, "previous case")
@@ -281,7 +282,7 @@ L:
 		// look for duplicate types
 		// (quadratic algorithm, but type switches tend to be reasonably small)
 		for t, other := range seen {
-			if T == nil && t == nil || T != nil && t != nil && check.identical(T, t) {
+			if T == nil && t == nil || T != nil && t != nil && Identical(T, t) {
 				// talk about "case" rather than "type" because of nil case
 				Ts := "nil"
 				if T != nil {
@@ -351,25 +352,33 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		check.errorf(&x, "%s %s", &x, msg)
 
 	case *syntax.SendStmt:
-		var ch, x operand
+		var ch, val operand
 		check.expr(&ch, s.Chan)
-		check.expr(&x, s.Value)
-		if ch.mode == invalid || x.mode == invalid {
+		check.expr(&val, s.Value)
+		if ch.mode == invalid || val.mode == invalid {
 			return
 		}
-
-		tch := asChan(ch.typ)
-		if tch == nil {
-			check.errorf(s, invalidOp+"cannot send to non-chan type %s", ch.typ)
-			return
-		}
-
-		if tch.dir == RecvOnly {
-			check.errorf(s, invalidOp+"cannot send to receive-only type %s", tch)
+		var elem Type
+		if !underIs(ch.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.errorf(s, invalidOp+"cannot send to non-channel %s", &ch)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.errorf(s, invalidOp+"cannot send to receive-only channel %s", &ch)
+				return false
+			}
+			if elem != nil && !Identical(uch.elem, elem) {
+				check.errorf(s, invalidOp+"channels of %s must have the same element type", &ch)
+				return false
+			}
+			elem = uch.elem
+			return true
+		}) {
 			return
 		}
-
-		check.assignment(&x, tch.elem, "send")
+		check.assignment(&val, elem, "send")
 
 	case *syntax.AssignStmt:
 		lhs := unpackExpr(s.Lhs)
@@ -780,9 +789,9 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 	// determine key/value types
 	var key, val Type
 	if x.mode != invalid {
+		// Ranging over a type parameter is permitted if it has a structural type.
 		typ := optype(x.typ)
 		if _, ok := typ.(*Chan); ok && sValue != nil {
-			// TODO(gri) this also needs to happen for channels in generic variables
 			check.softErrorf(sValue, "range over %s permits only one iteration variable", &x)
 			// ok to continue
 		}
@@ -891,7 +900,7 @@ func isVarName(x syntax.Expr) bool {
 // variables are used or present; this matters if we range over a generic
 // type where not all keys or values are of the same type.
 func rangeKeyVal(typ Type, wantKey, wantVal bool) (Type, Type, string) {
-	switch typ := typ.(type) {
+	switch typ := arrayPtrDeref(typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			return Typ[Int], universeRune, "" // use 'rune' name
@@ -900,10 +909,6 @@ func rangeKeyVal(typ Type, wantKey, wantVal bool) (Type, Type, string) {
 		return Typ[Int], typ.elem, ""
 	case *Slice:
 		return Typ[Int], typ.elem, ""
-	case *Pointer:
-		if typ := asArray(typ.base); typ != nil {
-			return Typ[Int], typ.elem, ""
-		}
 	case *Map:
 		return typ.key, typ.elem, ""
 	case *Chan:
@@ -912,32 +917,9 @@ func rangeKeyVal(typ Type, wantKey, wantVal bool) (Type, Type, string) {
 			msg = "receive from send-only channel"
 		}
 		return typ.elem, Typ[Invalid], msg
-	case *Sum:
-		first := true
-		var key, val Type
-		var msg string
-		typ.is(func(t Type) bool {
-			k, v, m := rangeKeyVal(under(t), wantKey, wantVal)
-			if k == nil || m != "" {
-				key, val, msg = k, v, m
-				return false
-			}
-			if first {
-				key, val, msg = k, v, m
-				first = false
-				return true
-			}
-			if wantKey && !Identical(key, k) {
-				key, val, msg = nil, nil, "all possible values must have the same key type"
-				return false
-			}
-			if wantVal && !Identical(val, v) {
-				key, val, msg = nil, nil, "all possible values must have the same element type"
-				return false
-			}
-			return true
-		})
-		return key, val, msg
+	case *top:
+		// we have a type parameter with no structural type
+		return nil, nil, "no structural type"
 	}
 	return nil, nil, ""
 }
diff --git a/src/cmd/compile/internal/types2/struct.go b/src/cmd/compile/internal/types2/struct.go
new file mode 100644
index 0000000000000000000000000000000000000000..f0c27c015043975601acf2c023575e6ac0b76ad9
--- /dev/null
+++ b/src/cmd/compile/internal/types2/struct.go
@@ -0,0 +1,213 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"cmd/compile/internal/syntax"
+	"strconv"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Struct represents a struct type.
+type Struct struct {
+	fields []*Var
+	tags   []string // field tags; nil if there are no tags
+}
+
+// NewStruct returns a new struct with the given fields and corresponding field tags.
+// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
+// only as long as required to hold the tag with the largest index i. Consequently,
+// if no field has a tag, tags may be nil.
+func NewStruct(fields []*Var, tags []string) *Struct {
+	var fset objset
+	for _, f := range fields {
+		if f.name != "_" && fset.insert(f) != nil {
+			panic("multiple fields with the same name")
+		}
+	}
+	if len(tags) > len(fields) {
+		panic("more tags than fields")
+	}
+	return &Struct{fields: fields, tags: tags}
+}
+
+// NumFields returns the number of fields in the struct (including blank and embedded fields).
+func (s *Struct) NumFields() int { return len(s.fields) }
+
+// Field returns the i'th field for 0 <= i < NumFields().
+func (s *Struct) Field(i int) *Var { return s.fields[i] }
+
+// Tag returns the i'th field tag for 0 <= i < NumFields().
+func (s *Struct) Tag(i int) string {
+	if i < len(s.tags) {
+		return s.tags[i]
+	}
+	return ""
+}
+
+func (s *Struct) Underlying() Type { return s }
+func (s *Struct) String() string   { return TypeString(s, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) structType(styp *Struct, e *syntax.StructType) {
+	if e.FieldList == nil {
+		return
+	}
+
+	// struct fields and tags
+	var fields []*Var
+	var tags []string
+
+	// for double-declaration checks
+	var fset objset
+
+	// current field typ and tag
+	var typ Type
+	var tag string
+	add := func(ident *syntax.Name, embedded bool, pos syntax.Pos) {
+		if tag != "" && tags == nil {
+			tags = make([]string, len(fields))
+		}
+		if tags != nil {
+			tags = append(tags, tag)
+		}
+
+		name := ident.Value
+		fld := NewField(pos, check.pkg, name, typ, embedded)
+		// spec: "Within a struct, non-blank field names must be unique."
+		if name == "_" || check.declareInSet(&fset, pos, fld) {
+			fields = append(fields, fld)
+			check.recordDef(ident, fld)
+		}
+	}
+
+	// addInvalid adds an embedded field of invalid type to the struct for
+	// fields with errors; this keeps the number of struct fields in sync
+	// with the source as long as the fields are _ or have different names
+	// (issue #25627).
+	addInvalid := func(ident *syntax.Name, pos syntax.Pos) {
+		typ = Typ[Invalid]
+		tag = ""
+		add(ident, true, pos)
+	}
+
+	var prev syntax.Expr
+	for i, f := range e.FieldList {
+		// Fields declared syntactically with the same type (e.g.: a, b, c T)
+		// share the same type expression. Only check type if it's a new type.
+		if i == 0 || f.Type != prev {
+			typ = check.varType(f.Type)
+			prev = f.Type
+		}
+		tag = ""
+		if i < len(e.TagList) {
+			tag = check.tag(e.TagList[i])
+		}
+		if f.Name != nil {
+			// named field
+			add(f.Name, false, f.Name.Pos())
+		} else {
+			// embedded field
+			// spec: "An embedded type must be specified as a type name T or as a
+			// pointer to a non-interface type name *T, and T itself may not be a
+			// pointer type."
+			pos := syntax.StartPos(f.Type)
+			name := embeddedFieldIdent(f.Type)
+			if name == nil {
+				check.errorf(pos, "invalid embedded field type %s", f.Type)
+				name = &syntax.Name{Value: "_"} // TODO(gri) need to set position to pos
+				addInvalid(name, pos)
+				continue
+			}
+			add(name, true, pos)
+
+			// Because we have a name, typ must be of the form T or *T, where T is the name
+			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
+			// We must delay this check to the end because we don't want to instantiate
+			// (via under(t)) a possibly incomplete type.
+			embeddedTyp := typ // for closure below
+			embeddedPos := pos
+			check.later(func() {
+				t, isPtr := deref(embeddedTyp)
+				switch t := under(t).(type) {
+				case *Basic:
+					if t == Typ[Invalid] {
+						// error was reported before
+						return
+					}
+					// unsafe.Pointer is treated like a regular pointer
+					if t.kind == UnsafePointer {
+						check.error(embeddedPos, "embedded field type cannot be unsafe.Pointer")
+					}
+				case *Pointer:
+					check.error(embeddedPos, "embedded field type cannot be a pointer")
+				case *TypeParam:
+					check.error(embeddedPos, "embedded field type cannot be a (pointer to a) type parameter")
+				case *Interface:
+					if isPtr {
+						check.error(embeddedPos, "embedded field type cannot be a pointer to an interface")
+					}
+				}
+			})
+		}
+	}
+
+	styp.fields = fields
+	styp.tags = tags
+}
+
+func embeddedFieldIdent(e syntax.Expr) *syntax.Name {
+	switch e := e.(type) {
+	case *syntax.Name:
+		return e
+	case *syntax.Operation:
+		if base := ptrBase(e); base != nil {
+			// *T is valid, but **T is not
+			if op, _ := base.(*syntax.Operation); op == nil || ptrBase(op) == nil {
+				return embeddedFieldIdent(e.X)
+			}
+		}
+	case *syntax.SelectorExpr:
+		return e.Sel
+	case *syntax.IndexExpr:
+		return embeddedFieldIdent(e.X)
+	}
+	return nil // invalid embedded field
+}
+
+func (check *Checker) declareInSet(oset *objset, pos syntax.Pos, obj Object) bool {
+	if alt := oset.insert(obj); alt != nil {
+		var err error_
+		err.errorf(pos, "%s redeclared", obj.Name())
+		err.recordAltDecl(alt)
+		check.report(&err)
+		return false
+	}
+	return true
+}
+
+func (check *Checker) tag(t *syntax.BasicLit) string {
+	// If t.Bad, an error was reported during parsing.
+	if t != nil && !t.Bad {
+		if t.Kind == syntax.StringLit {
+			if val, err := strconv.Unquote(t.Value); err == nil {
+				return val
+			}
+		}
+		check.errorf(t, invalidAST+"incorrect tag syntax: %q", t.Value)
+	}
+	return ""
+}
+
+func ptrBase(x *syntax.Operation) syntax.Expr {
+	if x.Op == syntax.Mul && x.Y == nil {
+		return x.X
+	}
+	return nil
+}
diff --git a/src/cmd/compile/internal/types2/subst.go b/src/cmd/compile/internal/types2/subst.go
index c8e428c1832311bed33fa8abf7965a01c3dce2a4..918e5f3043b59ed7844499a936caceeb18f74f59 100644
--- a/src/cmd/compile/internal/types2/subst.go
+++ b/src/cmd/compile/internal/types2/subst.go
@@ -2,215 +2,46 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements instantiation of generic types
-// through substitution of type parameters by actual
-// types.
+// This file implements type parameter substitution.
 
 package types2
 
 import (
 	"bytes"
 	"cmd/compile/internal/syntax"
-	"fmt"
 )
 
-type substMap struct {
-	// The targs field is currently needed for *Named type substitution.
-	// TODO(gri) rewrite that code, get rid of this field, and make this
-	//           struct just the map (proj)
-	targs []Type
-	proj  map[*TypeParam]Type
-}
+type substMap map[*TypeParam]Type
 
 // makeSubstMap creates a new substitution map mapping tpars[i] to targs[i].
 // If targs[i] is nil, tpars[i] is not substituted.
-func makeSubstMap(tpars []*TypeName, targs []Type) *substMap {
+func makeSubstMap(tpars []*TypeParam, targs []Type) substMap {
 	assert(len(tpars) == len(targs))
-	proj := make(map[*TypeParam]Type, len(tpars))
+	proj := make(substMap, len(tpars))
 	for i, tpar := range tpars {
-		// We must expand type arguments otherwise *instance
-		// types end up as components in composite types.
-		// TODO(gri) explain why this causes problems, if it does
-		targ := expand(targs[i]) // possibly nil
-		targs[i] = targ
-		proj[tpar.typ.(*TypeParam)] = targ
+		proj[tpar] = targs[i]
 	}
-	return &substMap{targs, proj}
-}
-
-func (m *substMap) String() string {
-	return fmt.Sprintf("%s", m.proj)
+	return proj
 }
 
-func (m *substMap) empty() bool {
-	return len(m.proj) == 0
+func (m substMap) empty() bool {
+	return len(m) == 0
 }
 
-func (m *substMap) lookup(tpar *TypeParam) Type {
-	if t := m.proj[tpar]; t != nil {
+func (m substMap) lookup(tpar *TypeParam) Type {
+	if t := m[tpar]; t != nil {
 		return t
 	}
 	return tpar
 }
 
-func (check *Checker) instantiate(pos syntax.Pos, typ Type, targs []Type, poslist []syntax.Pos) (res Type) {
-	if check.conf.Trace {
-		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
-		check.indent++
-		defer func() {
-			check.indent--
-			var under Type
-			if res != nil {
-				// Calling under() here may lead to endless instantiations.
-				// Test case: type T[P any] T[P]
-				// TODO(gri) investigate if that's a bug or to be expected.
-				under = res.Underlying()
-			}
-			check.trace(pos, "=> %s (under = %s)", res, under)
-		}()
-	}
-
-	assert(len(poslist) <= len(targs))
-
-	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
-	var tparams []*TypeName
-	switch t := typ.(type) {
-	case *Named:
-		tparams = t.tparams
-	case *Signature:
-		tparams = t.tparams
-		defer func() {
-			// If we had an unexpected failure somewhere don't panic below when
-			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
-			// is returned.
-			if _, ok := res.(*Signature); !ok {
-				return
-			}
-			// If the signature doesn't use its type parameters, subst
-			// will not make a copy. In that case, make a copy now (so
-			// we can set tparams to nil w/o causing side-effects).
-			if t == res {
-				copy := *t
-				res = ©
-			}
-			// After instantiating a generic signature, it is not generic
-			// anymore; we need to set tparams to nil.
-			res.(*Signature).tparams = nil
-		}()
-
-	default:
-		check.dump("%v: cannot instantiate %v", pos, typ)
-		unreachable() // only defined types and (defined) functions can be generic
-
-	}
-
-	// the number of supplied types must match the number of type parameters
-	if len(targs) != len(tparams) {
-		// TODO(gri) provide better error message
-		check.errorf(pos, "got %d arguments but %d type parameters", len(targs), len(tparams))
-		return Typ[Invalid]
-	}
-
-	if len(tparams) == 0 {
-		return typ // nothing to do (minor optimization)
-	}
-
-	smap := makeSubstMap(tparams, targs)
-
-	// check bounds
-	for i, tname := range tparams {
-		tpar := tname.typ.(*TypeParam)
-		iface := tpar.Bound()
-		if iface.Empty() {
-			continue // no type bound
-		}
-
-		targ := targs[i]
-
-		// best position for error reporting
-		pos := pos
-		if i < len(poslist) {
-			pos = poslist[i]
-		}
-
-		// The type parameter bound is parameterized with the same type parameters
-		// as the instantiated type; before we can use it for bounds checking we
-		// need to instantiate it with the type arguments with which we instantiate
-		// the parameterized type.
-		iface = check.subst(pos, iface, smap).(*Interface)
-
-		// targ must implement iface (methods)
-		// - check only if we have methods
-		check.completeInterface(nopos, iface)
-		if len(iface.allMethods) > 0 {
-			// If the type argument is a pointer to a type parameter, the type argument's
-			// method set is empty.
-			// TODO(gri) is this what we want? (spec question)
-			if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
-				check.errorf(pos, "%s has no methods", targ)
-				break
-			}
-			if m, wrong := check.missingMethod(targ, iface, true); m != nil {
-				// TODO(gri) needs to print updated name to avoid major confusion in error message!
-				//           (print warning for now)
-				// Old warning:
-				// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
-				if m.name == "==" {
-					// We don't want to report "missing method ==".
-					check.softErrorf(pos, "%s does not satisfy comparable", targ)
-				} else if wrong != nil {
-					// TODO(gri) This can still report uninstantiated types which makes the error message
-					//           more difficult to read then necessary.
-					check.softErrorf(pos,
-						"%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
-						targ, tpar.bound, wrong, m,
-					)
-				} else {
-					check.softErrorf(pos, "%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
-				}
-				break
-			}
-		}
-
-		// targ's underlying type must also be one of the interface types listed, if any
-		if iface.allTypes == nil {
-			continue // nothing to do
-		}
-
-		// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
-		// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
-		if targ := asTypeParam(targ); targ != nil {
-			targBound := targ.Bound()
-			if targBound.allTypes == nil {
-				check.softErrorf(pos, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
-				break
-			}
-			for _, t := range unpack(targBound.allTypes) {
-				if !iface.isSatisfiedBy(t) {
-					// TODO(gri) match this error message with the one below (or vice versa)
-					check.softErrorf(pos, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, t, iface.allTypes)
-					break
-				}
-			}
-			break
-		}
-
-		// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
-		if !iface.isSatisfiedBy(targ) {
-			check.softErrorf(pos, "%s does not satisfy %s (%s not found in %s)", targ, tpar.bound, under(targ), iface.allTypes)
-			break
-		}
-	}
-
-	return check.subst(pos, typ, smap)
-}
-
-// subst returns the type typ with its type parameters tpars replaced by
-// the corresponding type arguments targs, recursively.
-// subst is functional in the sense that it doesn't modify the incoming
-// type. If a substitution took place, the result type is different from
-// from the incoming type.
-func (check *Checker) subst(pos syntax.Pos, typ Type, smap *substMap) Type {
+// subst returns the type typ with its type parameters tpars replaced by the
+// corresponding type arguments targs, recursively. subst doesn't modify the
+// incoming type. If a substitution took place, the result type is different
+// from from the incoming type.
+//
+// If the given typMap is non-nil, it is used in lieu of check.typMap.
+func (check *Checker) subst(pos syntax.Pos, typ Type, smap substMap, typMap map[string]*Named) Type {
 	if smap.empty() {
 		return typ
 	}
@@ -224,15 +55,33 @@ func (check *Checker) subst(pos syntax.Pos, typ Type, smap *substMap) Type {
 	}
 
 	// general case
-	subst := subster{check, pos, make(map[Type]Type), smap}
+	var subst subster
+	subst.pos = pos
+	subst.smap = smap
+
+	if check != nil {
+		subst.check = check
+		if typMap == nil {
+			typMap = check.typMap
+		}
+	}
+	if typMap == nil {
+		// If we don't have a *Checker and its global type map,
+		// use a local version. Besides avoiding duplicate work,
+		// the type map prevents infinite recursive substitution
+		// for recursive types (example: type T[P any] *T[P]).
+		typMap = make(map[string]*Named)
+	}
+	subst.typMap = typMap
+
 	return subst.typ(typ)
 }
 
 type subster struct {
-	check *Checker
-	pos   syntax.Pos
-	cache map[Type]Type
-	smap  *substMap
+	pos    syntax.Pos
+	smap   substMap
+	check  *Checker // nil if called via Instantiate
+	typMap map[string]*Named
 }
 
 func (subst *subster) typ(typ Type) Type {
@@ -241,7 +90,7 @@ func (subst *subster) typ(typ Type) Type {
 		// Call typOrNil if it's possible that typ is nil.
 		panic("nil typ")
 
-	case *Basic, *bottom, *top:
+	case *Basic, *top:
 		// nothing to do
 
 	case *Array:
@@ -290,29 +139,20 @@ func (subst *subster) typ(typ Type) Type {
 			}
 		}
 
-	case *Sum:
-		types, copied := subst.typeList(t.types)
+	case *Union:
+		terms, copied := subst.termlist(t.terms)
 		if copied {
-			// Don't do it manually, with a Sum literal: the new
-			// types list may not be unique and NewSum may remove
-			// duplicates.
-			return NewSum(types)
+			// term list substitution may introduce duplicate terms (unlikely but possible).
+			// This is ok; lazy type set computation will determine the actual type set
+			// in normal form.
+			return &Union{terms, nil}
 		}
 
 	case *Interface:
 		methods, mcopied := subst.funcList(t.methods)
-		types := t.types
-		if t.types != nil {
-			types = subst.typ(t.types)
-		}
 		embeddeds, ecopied := subst.typeList(t.embeddeds)
-		if mcopied || types != t.types || ecopied {
-			iface := &Interface{methods: methods, types: types, embeddeds: embeddeds}
-			if subst.check == nil {
-				panic("internal error: cannot instantiate interfaces yet")
-			}
-			subst.check.posMap[iface] = subst.check.posMap[t] // satisfy completeInterface requirement
-			subst.check.completeInterface(nopos, iface)
+		if mcopied || ecopied {
+			iface := &Interface{methods: methods, embeddeds: embeddeds, complete: t.complete}
 			return iface
 		}
 
@@ -342,77 +182,70 @@ func (subst *subster) typ(typ Type) Type {
 			}
 		}
 
-		if t.tparams == nil {
+		if t.TParams().Len() == 0 {
 			dump(">>> %s is not parameterized", t)
 			return t // type is not parameterized
 		}
 
-		var new_targs []Type
-
-		if len(t.targs) > 0 {
-			// already instantiated
-			dump(">>> %s already instantiated", t)
-			assert(len(t.targs) == len(t.tparams))
-			// For each (existing) type argument targ, determine if it needs
-			// to be substituted; i.e., if it is or contains a type parameter
-			// that has a type argument for it.
-			for i, targ := range t.targs {
-				dump(">>> %d targ = %s", i, targ)
-				new_targ := subst.typ(targ)
-				if new_targ != targ {
-					dump(">>> substituted %d targ %s => %s", i, targ, new_targ)
-					if new_targs == nil {
-						new_targs = make([]Type, len(t.tparams))
-						copy(new_targs, t.targs)
-					}
-					new_targs[i] = new_targ
+		var newTArgs []Type
+		assert(t.targs.Len() == t.TParams().Len())
+
+		// already instantiated
+		dump(">>> %s already instantiated", t)
+		// For each (existing) type argument targ, determine if it needs
+		// to be substituted; i.e., if it is or contains a type parameter
+		// that has a type argument for it.
+		for i, targ := range t.targs.list() {
+			dump(">>> %d targ = %s", i, targ)
+			new_targ := subst.typ(targ)
+			if new_targ != targ {
+				dump(">>> substituted %d targ %s => %s", i, targ, new_targ)
+				if newTArgs == nil {
+					newTArgs = make([]Type, t.TParams().Len())
+					copy(newTArgs, t.targs.list())
 				}
+				newTArgs[i] = new_targ
 			}
+		}
 
-			if new_targs == nil {
-				dump(">>> nothing to substitute in %s", t)
-				return t // nothing to substitute
-			}
-		} else {
-			// not yet instantiated
-			dump(">>> first instantiation of %s", t)
-			new_targs = subst.smap.targs
+		if newTArgs == nil {
+			dump(">>> nothing to substitute in %s", t)
+			return t // nothing to substitute
 		}
 
 		// before creating a new named type, check if we have this one already
-		h := instantiatedHash(t, new_targs)
+		h := instantiatedHash(t, newTArgs)
 		dump(">>> new type hash: %s", h)
-		if subst.check != nil {
-			if named, found := subst.check.typMap[h]; found {
-				dump(">>> found %s", named)
-				subst.cache[t] = named
-				return named
-			}
+		if named, found := subst.typMap[h]; found {
+			dump(">>> found %s", named)
+			return named
 		}
 
-		// create a new named type and populate caches to avoid endless recursion
+		// Create a new named type and populate typMap to avoid endless recursion.
+		// The position used here is irrelevant because validation only occurs on t
+		// (we don't call validType on named), but we use subst.pos to help with
+		// debugging.
 		tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil)
-		named := subst.check.newNamed(tname, t, t.underlying, t.tparams, t.methods) // method signatures are updated lazily
-		named.targs = new_targs
-		if subst.check != nil {
-			subst.check.typMap[h] = named
-		}
-		subst.cache[t] = named
+		t.load()
+		// It's ok to provide a nil *Checker because the newly created type
+		// doesn't need to be (lazily) expanded; it's expanded below.
+		named := (*Checker)(nil).newNamed(tname, t.orig, nil, t.tparams, t.methods) // t is loaded, so tparams and methods are available
+		named.targs = NewTypeList(newTArgs)
+		subst.typMap[h] = named
+		t.expand(subst.typMap) // must happen after typMap update to avoid infinite recursion
 
 		// do the substitution
-		dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, new_targs)
+		dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTArgs)
 		named.underlying = subst.typOrNil(t.underlying)
-		named.fromRHS = named.underlying // for cycle detection (Checker.validType)
+		dump(">>> underlying: %v", named.underlying)
+		assert(named.underlying != nil)
+		named.fromRHS = named.underlying // for consistency, though no cycle detection is necessary
 
 		return named
 
 	case *TypeParam:
 		return subst.smap.lookup(t)
 
-	case *instance:
-		// TODO(gri) can we avoid the expansion here and just substitute the type parameters?
-		return subst.typ(t.expand())
-
 	default:
 		unimplemented()
 	}
@@ -420,14 +253,17 @@ func (subst *subster) typ(typ Type) Type {
 	return typ
 }
 
-// TODO(gri) Eventually, this should be more sophisticated.
-//           It won't work correctly for locally declared types.
+var instanceHashing = 0
+
 func instantiatedHash(typ *Named, targs []Type) string {
+	assert(instanceHashing == 0)
+	instanceHashing++
 	var buf bytes.Buffer
 	writeTypeName(&buf, typ.obj, nil)
 	buf.WriteByte('[')
 	writeTypeList(&buf, targs, nil, nil)
 	buf.WriteByte(']')
+	instanceHashing--
 
 	// With respect to the represented type, whether a
 	// type is fully expanded or stored as instance
@@ -545,3 +381,21 @@ func (subst *subster) typeList(in []Type) (out []Type, copied bool) {
 	}
 	return
 }
+
+func (subst *subster) termlist(in []*Term) (out []*Term, copied bool) {
+	out = in
+	for i, t := range in {
+		if u := subst.typ(t.typ); u != t.typ {
+			if !copied {
+				// first function that got substituted => allocate new out slice
+				// and copy all functions
+				new := make([]*Term, len(in))
+				copy(new, out)
+				out = new
+				copied = true
+			}
+			out[i] = NewTerm(t.tilde, u)
+		}
+	}
+	return
+}
diff --git a/src/cmd/compile/internal/types2/termlist.go b/src/cmd/compile/internal/types2/termlist.go
new file mode 100644
index 0000000000000000000000000000000000000000..378ba6b8f4c024d02f18f090526899e720017c9b
--- /dev/null
+++ b/src/cmd/compile/internal/types2/termlist.go
@@ -0,0 +1,167 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "bytes"
+
+// A termlist represents the type set represented by the union
+// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
+// A termlist is in normal form if all terms are disjoint.
+// termlist operations don't require the operands to be in
+// normal form.
+type termlist []*term
+
+// allTermlist represents the set of all types.
+// It is in normal form.
+var allTermlist = termlist{new(term)}
+
+// String prints the termlist exactly (without normalization).
+func (xl termlist) String() string {
+	if len(xl) == 0 {
+		return "∅"
+	}
+	var buf bytes.Buffer
+	for i, x := range xl {
+		if i > 0 {
+			buf.WriteString(" ∪ ")
+		}
+		buf.WriteString(x.String())
+	}
+	return buf.String()
+}
+
+// isEmpty reports whether the termlist xl represents the empty set of types.
+func (xl termlist) isEmpty() bool {
+	// If there's a non-nil term, the entire list is not empty.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// isAll reports whether the termlist xl represents the set of all types.
+func (xl termlist) isAll() bool {
+	// If there's a 𝓤 term, the entire list is 𝓤.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil && x.typ == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// norm returns the normal form of xl.
+func (xl termlist) norm() termlist {
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	used := make([]bool, len(xl))
+	var rl termlist
+	for i, xi := range xl {
+		if xi == nil || used[i] {
+			continue
+		}
+		for j := i + 1; j < len(xl); j++ {
+			xj := xl[j]
+			if xj == nil || used[j] {
+				continue
+			}
+			if u1, u2 := xi.union(xj); u2 == nil {
+				// If we encounter a 𝓤 term, the entire list is 𝓤.
+				// Exit early.
+				// (Note that this is not just an optimization;
+				// if we continue, we may end up with a 𝓤 term
+				// and other terms and the result would not be
+				// in normal form.)
+				if u1.typ == nil {
+					return allTermlist
+				}
+				xi = u1
+				used[j] = true // xj is now unioned into xi - ignore it in future iterations
+			}
+		}
+		rl = append(rl, xi)
+	}
+	return rl
+}
+
+// If the type set represented by xl is specified by a single (non-𝓤) term,
+// structuralType returns that type. Otherwise it returns nil.
+func (xl termlist) structuralType() Type {
+	if nl := xl.norm(); len(nl) == 1 {
+		return nl[0].typ // if nl.isAll() then typ is nil, which is ok
+	}
+	return nil
+}
+
+// union returns the union xl ∪ yl.
+func (xl termlist) union(yl termlist) termlist {
+	return append(xl, yl...).norm()
+}
+
+// intersect returns the intersection xl ∩ yl.
+func (xl termlist) intersect(yl termlist) termlist {
+	if xl.isEmpty() || yl.isEmpty() {
+		return nil
+	}
+
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	var rl termlist
+	for _, x := range xl {
+		for _, y := range yl {
+			if r := x.intersect(y); r != nil {
+				rl = append(rl, r)
+			}
+		}
+	}
+	return rl.norm()
+}
+
+// equal reports whether xl and yl represent the same type set.
+func (xl termlist) equal(yl termlist) bool {
+	// TODO(gri) this should be more efficient
+	return xl.subsetOf(yl) && yl.subsetOf(xl)
+}
+
+// includes reports whether t ∈ xl.
+func (xl termlist) includes(t Type) bool {
+	for _, x := range xl {
+		if x.includes(t) {
+			return true
+		}
+	}
+	return false
+}
+
+// supersetOf reports whether y ⊆ xl.
+func (xl termlist) supersetOf(y *term) bool {
+	for _, x := range xl {
+		if y.subsetOf(x) {
+			return true
+		}
+	}
+	return false
+}
+
+// subsetOf reports whether xl ⊆ yl.
+func (xl termlist) subsetOf(yl termlist) bool {
+	if yl.isEmpty() {
+		return xl.isEmpty()
+	}
+
+	// each term x of xl must be a subset of yl
+	for _, x := range xl {
+		if !yl.supersetOf(x) {
+			return false // x is not a subset yl
+		}
+	}
+	return true
+}
diff --git a/src/cmd/compile/internal/types2/termlist_test.go b/src/cmd/compile/internal/types2/termlist_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..ed1330d26fcb28b87b9ed2cbe3203840086b6d96
--- /dev/null
+++ b/src/cmd/compile/internal/types2/termlist_test.go
@@ -0,0 +1,313 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"strings"
+	"testing"
+)
+
+// maketl makes a term list from a string of the term list.
+func maketl(s string) termlist {
+	s = strings.ReplaceAll(s, " ", "")
+	names := strings.Split(s, "∪")
+	r := make(termlist, len(names))
+	for i, n := range names {
+		r[i] = testTerm(n)
+	}
+	return r
+}
+
+func TestTermlistAll(t *testing.T) {
+	if !allTermlist.isAll() {
+		t.Errorf("allTermlist is not the set of all types")
+	}
+}
+
+func TestTermlistString(t *testing.T) {
+	for _, want := range []string{
+		"∅",
+		"𝓤",
+		"int",
+		"~int",
+		"myInt",
+		"∅ ∪ ∅",
+		"𝓤 ∪ 𝓤",
+		"∅ ∪ 𝓤 ∪ int",
+		"∅ ∪ 𝓤 ∪ int ∪ myInt",
+	} {
+		if got := maketl(want).String(); got != want {
+			t.Errorf("(%v).String() == %v", want, got)
+		}
+	}
+}
+
+func TestTermlistIsEmpty(t *testing.T) {
+	for test, want := range map[string]bool{
+		"∅":             true,
+		"∅ ∪ ∅":         true,
+		"∅ ∪ ∅ ∪ 𝓤":     false,
+		"∅ ∪ ∅ ∪ myInt": false,
+		"𝓤":             false,
+		"𝓤 ∪ int":       false,
+		"𝓤 ∪ myInt ∪ ∅": false,
+	} {
+		xl := maketl(test)
+		got := xl.isEmpty()
+		if got != want {
+			t.Errorf("(%v).isEmpty() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistIsAll(t *testing.T) {
+	for test, want := range map[string]bool{
+		"∅":             false,
+		"∅ ∪ ∅":         false,
+		"int ∪ ~string": false,
+		"~int ∪ myInt":  false,
+		"∅ ∪ ∅ ∪ 𝓤":     true,
+		"𝓤":             true,
+		"𝓤 ∪ int":       true,
+		"myInt ∪ 𝓤":     true,
+	} {
+		xl := maketl(test)
+		got := xl.isAll()
+		if got != want {
+			t.Errorf("(%v).isAll() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistNorm(t *testing.T) {
+	for _, test := range []struct {
+		xl, want string
+	}{
+		{"∅", "∅"},
+		{"∅ ∪ ∅", "∅"},
+		{"∅ ∪ int", "int"},
+		{"∅ ∪ myInt", "myInt"},
+		{"𝓤 ∪ int", "𝓤"},
+		{"𝓤 ∪ myInt", "𝓤"},
+		{"int ∪ myInt", "int ∪ myInt"},
+		{"~int ∪ int", "~int"},
+		{"~int ∪ myInt", "~int"},
+		{"int ∪ ~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤 ∪ ~string ∪ int", "𝓤"},
+		{"~int ∪ string ∪ myInt ∪ ~string ∪ int", "~int ∪ ~string"},
+	} {
+		xl := maketl(test.xl)
+		got := maketl(test.xl).norm()
+		if got.String() != test.want {
+			t.Errorf("(%v).norm() = %v; want %v", xl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistStructuralType(t *testing.T) {
+	// helper to deal with nil types
+	tstring := func(typ Type) string {
+		if typ == nil {
+			return "nil"
+		}
+		return typ.String()
+	}
+
+	for test, want := range map[string]string{
+		"∅":                 "nil",
+		"𝓤":                 "nil",
+		"int":               "int",
+		"myInt":             "myInt",
+		"~int":              "int",
+		"~int ∪ string":     "nil",
+		"~int ∪ myInt":      "int",
+		"∅ ∪ int":           "int",
+		"∅ ∪ ~int":          "int",
+		"∅ ∪ ~int ∪ string": "nil",
+	} {
+		xl := maketl(test)
+		got := tstring(xl.structuralType())
+		if got != want {
+			t.Errorf("(%v).structuralType() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistUnion(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl, want string
+	}{
+
+		{"∅", "∅", "∅"},
+		{"∅", "𝓤", "𝓤"},
+		{"∅", "int", "int"},
+		{"𝓤", "~int", "𝓤"},
+		{"int", "~int", "~int"},
+		{"int", "string", "int ∪ string"},
+		{"int", "myInt", "int ∪ myInt"},
+		{"~int", "myInt", "~int"},
+		{"int ∪ string", "~string", "int ∪ ~string"},
+		{"~int ∪ string", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ string ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ myInt ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "𝓤"},
+		{"~int ∪ string ∪ myInt", "~string ∪ int", "~int ∪ ~string"},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.union(yl).String()
+		if got != test.want {
+			t.Errorf("(%v).union(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistIntersect(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl, want string
+	}{
+
+		{"∅", "∅", "∅"},
+		{"∅", "𝓤", "∅"},
+		{"∅", "int", "∅"},
+		{"∅", "myInt", "∅"},
+		{"𝓤", "~int", "~int"},
+		{"𝓤", "myInt", "myInt"},
+		{"int", "~int", "int"},
+		{"int", "string", "∅"},
+		{"int", "myInt", "∅"},
+		{"~int", "myInt", "myInt"},
+		{"int ∪ string", "~string", "string"},
+		{"~int ∪ string", "~string ∪ int", "int ∪ string"},
+		{"~int ∪ string ∪ ∅", "~string ∪ int", "int ∪ string"},
+		{"~int ∪ myInt ∪ ∅", "~string ∪ int", "int"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ myInt", "~string ∪ int", "int ∪ string"},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.intersect(yl).String()
+		if got != test.want {
+			t.Errorf("(%v).intersect(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistEqual(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl string
+		want   bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", false},
+		{"𝓤", "𝓤", true},
+		{"𝓤 ∪ int", "𝓤", true},
+		{"𝓤 ∪ int", "string ∪ 𝓤", true},
+		{"𝓤 ∪ myInt", "string ∪ 𝓤", true},
+		{"int ∪ ~string", "string ∪ int", false},
+		{"~int ∪ string", "string ∪ myInt", false},
+		{"int ∪ ~string ∪ ∅", "string ∪ int ∪ ~string", true},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.equal(yl)
+		if got != test.want {
+			t.Errorf("(%v).equal(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistIncludes(t *testing.T) {
+	for _, test := range []struct {
+		xl, typ string
+		want    bool
+	}{
+		{"∅", "int", false},
+		{"𝓤", "int", true},
+		{"~int", "int", true},
+		{"int", "string", false},
+		{"~int", "string", false},
+		{"~int", "myInt", true},
+		{"int ∪ string", "string", true},
+		{"~int ∪ string", "int", true},
+		{"~int ∪ string", "myInt", true},
+		{"~int ∪ myInt ∪ ∅", "myInt", true},
+		{"myInt ∪ ∅ ∪ 𝓤", "int", true},
+	} {
+		xl := maketl(test.xl)
+		yl := testTerm(test.typ).typ
+		got := xl.includes(yl)
+		if got != test.want {
+			t.Errorf("(%v).includes(%v) = %v; want %v", test.xl, yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistSupersetOf(t *testing.T) {
+	for _, test := range []struct {
+		xl, typ string
+		want    bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", false},
+		{"∅", "int", false},
+		{"𝓤", "∅", true},
+		{"𝓤", "𝓤", true},
+		{"𝓤", "int", true},
+		{"𝓤", "~int", true},
+		{"𝓤", "myInt", true},
+		{"~int", "int", true},
+		{"~int", "~int", true},
+		{"~int", "myInt", true},
+		{"int", "~int", false},
+		{"myInt", "~int", false},
+		{"int", "string", false},
+		{"~int", "string", false},
+		{"int ∪ string", "string", true},
+		{"int ∪ string", "~string", false},
+		{"~int ∪ string", "int", true},
+		{"~int ∪ string", "myInt", true},
+		{"~int ∪ string ∪ ∅", "string", true},
+		{"~string ∪ ∅ ∪ 𝓤", "myInt", true},
+	} {
+		xl := maketl(test.xl)
+		y := testTerm(test.typ)
+		got := xl.supersetOf(y)
+		if got != test.want {
+			t.Errorf("(%v).supersetOf(%v) = %v; want %v", test.xl, y, got, test.want)
+		}
+	}
+}
+
+func TestTermlistSubsetOf(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl string
+		want   bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", true},
+		{"𝓤", "∅", false},
+		{"𝓤", "𝓤", true},
+		{"int", "int ∪ string", true},
+		{"~int", "int ∪ string", false},
+		{"~int", "myInt ∪ string", false},
+		{"myInt", "~int ∪ string", true},
+		{"~int", "string ∪ string ∪ int ∪ ~int", true},
+		{"myInt", "string ∪ string ∪ ~int", true},
+		{"int ∪ string", "string", false},
+		{"int ∪ string", "string ∪ int", true},
+		{"int ∪ ~string", "string ∪ int", false},
+		{"myInt ∪ ~string", "string ∪ int ∪ 𝓤", true},
+		{"int ∪ ~string", "string ∪ int ∪ ∅ ∪ string", false},
+		{"int ∪ myInt", "string ∪ ~int ∪ ∅ ∪ string", true},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.subsetOf(yl)
+		if got != test.want {
+			t.Errorf("(%v).subsetOf(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/types2/testdata/check/builtins.go2 b/src/cmd/compile/internal/types2/testdata/check/builtins.go2
index 3918d836b5277a8a71d46380b441b1a29d409bd7..0cfea93bf6d500a9a7883ed3baffd04fc702e9e0 100644
--- a/src/cmd/compile/internal/types2/testdata/check/builtins.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/builtins.go2
@@ -6,48 +6,222 @@
 
 package builtins
 
-type Bmc interface {
-	type map[rune]string, chan int
+import "unsafe"
+
+// close
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
+}
+
+func _[T C0](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
+}
+
+func _[T C1](ch T) {
+	close(ch)
+}
+
+func _[T C2](ch T) {
+	close(ch /* ERROR cannot close receive-only channel */)
+}
+
+func _[T C3](ch T) {
+	close(ch)
+}
+
+func _[T C4](ch T) {
+	close(ch)
+}
+
+func _[T C5[X], X any](ch T) {
+	close(ch)
+}
+
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface { map[string]int | map[string]float64 }
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func _[T any](m T) {
+	delete(m /* ERROR not a map */, "foo")
 }
 
-type Bms interface {
-	type map[string]int, []int
+func _[T M0](m T) {
+	delete(m /* ERROR not a map */, "foo")
 }
 
-type Bcs interface {
-	type chan bool, []float64
+func _[T M1](m T) {
+	delete(m, "foo")
 }
 
-type Bss interface {
-	type []int, []string
+func _[T M2](m T) {
+	delete(m, "foo")
+	delete(m, 0 /* ERROR cannot use .* as string */)
 }
 
-func _[T any] () {
-	_ = make(T /* ERROR invalid argument */ )
-	_ = make(T /* ERROR invalid argument */ , 10)
-	_ = make(T /* ERROR invalid argument */ , 10, 20)
+func _[T M3](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
 }
 
-func _[T Bmc] () {
-	_ = make(T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 1 or 2 arguments */ (T, 10, 20)
+func _[T M4[rune, V], V any](m T) {
+	delete(m, 'k')
 }
 
-func _[T Bms] () {
-	_ = make /* ERROR expects 2 arguments */ (T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
+func _[T M4[K, V], K comparable, V any](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
 }
 
-func _[T Bcs] () {
-	_ = make /* ERROR expects 2 arguments */ (T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
+// make
+
+func _[
+	S1 interface{ []int },
+	S2 interface{ []int | chan int },
+
+	M1 interface{ map[string]int },
+	M2 interface{ map[string]int | chan int },
+
+	C1 interface{ chan int },
+	C2 interface{ chan int | chan string },
+]() {
+	type S0 []int
+	_ = make([]int, 10)
+	_ = make(S0, 10)
+	_ = make(S1, 10)
+	_ = make /* ERROR not enough arguments */ ()
+	_ = make /* ERROR expects 2 or 3 arguments */ (S1)
+	_ = make(S1, 10, 20)
+	_ = make /* ERROR expects 2 or 3 arguments */ (S1, 10, 20, 30)
+	_ = make(S2 /* ERROR cannot make .* no structural type */ , 10)
+
+	type M0 map[string]int
+	_ = make(map[string]int)
+	_ = make(M0)
+	_ = make(M1)
+	_ = make(M1, 10)
+	_ = make/* ERROR expects 1 or 2 arguments */(M1, 10, 20)
+	_ = make(M2 /* ERROR cannot make .* no structural type */ )
+
+	type C0 chan int
+	_ = make(chan int)
+	_ = make(C0)
+	_ = make(C1)
+	_ = make(C1, 10)
+	_ = make/* ERROR expects 1 or 2 arguments */(C1, 10, 20)
+	_ = make(C2 /* ERROR cannot make .* no structural type */ )
 }
 
-func _[T Bss] () {
-	_ = make /* ERROR expects 2 or 3 arguments */ (T)
-	_ = make(T, 10)
-	_ = make(T, 10, 20)
+// unsafe.Alignof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Alignof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Alignof(p)
+	assert(pp == 8)
+	const ll = unsafe.Alignof(l)
+	assert(ll == 8)
+	const ff = unsafe.Alignof(f)
+	assert(ff == 8)
+	const ii = unsafe.Alignof(i)
+	assert(ii == 8)
+	const cc = unsafe.Alignof(c)
+	assert(cc == 8)
+	const mm = unsafe.Alignof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Offsetof
+
+func _[T comparable]() {
+	var (
+		b struct{ _, f int64 }
+		a struct{ _, f [10]T }
+		s struct{ _, f struct{ f T } }
+		p struct{ _, f *T }
+		l struct{ _, f []T }
+		f struct{ _, f func(T) }
+		i struct{ _, f interface{ m() T } }
+		c struct{ _, f chan T }
+		m struct{ _, f map[T]T }
+		t struct{ _, f T }
+	)
+
+	const bb = unsafe.Offsetof(b.f)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Offsetof(p.f)
+	assert(pp == 8)
+	const ll = unsafe.Offsetof(l.f)
+	assert(ll == 24)
+	const ff = unsafe.Offsetof(f.f)
+	assert(ff == 8)
+	const ii = unsafe.Offsetof(i.f)
+	assert(ii == 16)
+	const cc = unsafe.Offsetof(c.f)
+	assert(cc == 8)
+	const mm = unsafe.Offsetof(m.f)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Sizeof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Sizeof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Sizeof(p)
+	assert(pp == 8)
+	const ll = unsafe.Sizeof(l)
+	assert(ll == 24)
+	const ff = unsafe.Sizeof(f)
+	assert(ff == 8)
+	const ii = unsafe.Sizeof(i)
+	assert(ii == 16)
+	const cc = unsafe.Sizeof(c)
+	assert(cc == 8)
+	const mm = unsafe.Sizeof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
 }
diff --git a/src/cmd/compile/internal/types2/testdata/check/builtins.src b/src/cmd/compile/internal/types2/testdata/check/builtins.src
index 6d1f47129b9c16d2935a66c6eb97a740550041ae..17e4068d6546ea22080d5cd3f4bb3049aa119498 100644
--- a/src/cmd/compile/internal/types2/testdata/check/builtins.src
+++ b/src/cmd/compile/internal/types2/testdata/check/builtins.src
@@ -144,7 +144,7 @@ func close1() {
 	var r <-chan int
 	close() // ERROR not enough arguments
 	close(1, 2) // ERROR too many arguments
-	close(42 /* ERROR not a channel */)
+	close(42 /* ERROR cannot close non-channel */)
 	close(r /* ERROR receive-only channel */)
 	close(c)
 	_ = close /* ERROR used as value */ (c)
diff --git a/src/cmd/compile/internal/types2/testdata/check/const0.src b/src/cmd/compile/internal/types2/testdata/check/const0.src
index 5608b1549ba8d7774c2463fa9faab3702673f061..3cffdf904c87feb265ee5b1293d07be185e17372 100644
--- a/src/cmd/compile/internal/types2/testdata/check/const0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/const0.src
@@ -27,7 +27,7 @@ const (
 	ub1 = true
 	ub2 = 2 < 1
 	ub3 = ui1 == uf1
-	ub4 = true /* ERROR "cannot convert" */ == 0
+	ub4 = true /* ERROR "mismatched types untyped bool and untyped int" */ == 0
 
 	// integer values
 	ui0 = 0
diff --git a/src/cmd/compile/internal/types2/testdata/check/cycles4.src b/src/cmd/compile/internal/types2/testdata/check/cycles4.src
index 445babca68bc3db73a1cc192f366480171fbc659..924aabf475f9640cdfa6da8834fa9a8db6aa0a2b 100644
--- a/src/cmd/compile/internal/types2/testdata/check/cycles4.src
+++ b/src/cmd/compile/internal/types2/testdata/check/cycles4.src
@@ -4,6 +4,8 @@
 
 package p
 
+import "unsafe"
+
 // Check that all methods of T are collected before
 // determining the result type of m (which embeds
 // all methods of T).
@@ -13,7 +15,7 @@ type T interface {
 	E
 }
 
-var _ = T.m(nil).m().e()
+var _ int = T.m(nil).m().e()
 
 type E interface {
 	e() int
@@ -22,7 +24,7 @@ type E interface {
 // Check that unresolved forward chains are followed
 // (see also comment in resolver.go, checker.typeDecl).
 
-var _ = C.m(nil).m().e()
+var _ int = C.m(nil).m().e()
 
 type A B
 
@@ -108,3 +110,12 @@ type Element interface {
 type Event interface {
 	Target() Element
 }
+
+// Check that accessing an interface method too early doesn't lead
+// to follow-on errors due to an incorrectly computed type set.
+
+type T8 interface {
+	m() [unsafe.Sizeof(T8.m /* ERROR undefined */ )]int
+}
+
+var _ = T8.m // no error expected here
diff --git a/src/cmd/compile/internal/types2/testdata/check/decls0.src b/src/cmd/compile/internal/types2/testdata/check/decls0.src
index e78d8867e0995b38ae8d2d936143937839a5a808..f051a4f2acb812bd511661ee35a90a4c0f8f69c9 100644
--- a/src/cmd/compile/internal/types2/testdata/check/decls0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/decls0.src
@@ -4,7 +4,7 @@
 
 // type declarations
 
-package decls0
+package go1_17 // don't permit non-interface elements in interfaces
 
 import "unsafe"
 
@@ -185,10 +185,10 @@ func f2(x *f2 /* ERROR "not a type" */ ) {}
 func f3() (x f3 /* ERROR "not a type" */ ) { return }
 func f4() (x *f4 /* ERROR "not a type" */ ) { return }
 
-func (S0) m1(x S0 /* ERROR value .* is not a type */ .m1) {}
-func (S0) m2(x *S0 /* ERROR value .* is not a type */ .m2) {}
-func (S0) m3() (x S0 /* ERROR value .* is not a type */ .m3) { return }
-func (S0) m4() (x *S0 /* ERROR value .* is not a type */ .m4) { return }
+func (S0) m1(x S0 /* ERROR illegal cycle in method declaration */ .m1) {}
+func (S0) m2(x *S0 /* ERROR illegal cycle in method declaration */ .m2) {}
+func (S0) m3() (x S0 /* ERROR illegal cycle in method declaration */ .m3) { return }
+func (S0) m4() (x *S0 /* ERROR illegal cycle in method declaration */ .m4) { return }
 
 // interfaces may not have any blank methods
 type BlankI interface {
diff --git a/src/cmd/compile/internal/types2/testdata/check/decls1.src b/src/cmd/compile/internal/types2/testdata/check/decls1.src
index e6beb7835897bc12ae90eed4c1007b956ac33a21..1167ced366e2bff73453c5bf09559c54c8f0ece4 100644
--- a/src/cmd/compile/internal/types2/testdata/check/decls1.src
+++ b/src/cmd/compile/internal/types2/testdata/check/decls1.src
@@ -83,7 +83,7 @@ var (
 
 // Constant expression initializations
 var (
-	v1 = 1 /* ERROR "cannot convert" */ + "foo"
+	v1 = 1 /* ERROR "mismatched types untyped int and untyped string" */ + "foo"
 	v2 = c + 255
 	v3 = c + 256 /* ERROR "overflows" */
 	v4 = r + 2147483647
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr1.src b/src/cmd/compile/internal/types2/testdata/check/expr1.src
index 4ead815158f61e2dbbb91dec8e7feabef4a3923c..85ad234bbbf46833d33c6328b38192c5a9bd88d4 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr1.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr1.src
@@ -111,10 +111,10 @@ type mystring string
 func _(x, y string, z mystring) {
 	x = x + "foo"
 	x = x /* ERROR not defined */ - "foo"
-	x = x + 1 // ERROR cannot convert
+	x = x + 1 // ERROR mismatched types string and untyped int
 	x = x + y
 	x = x /* ERROR not defined */ - y
-	x = x * 10 // ERROR cannot convert
+	x = x * 10 // ERROR mismatched types string and untyped int
 }
 
 func f() (a, b int) { return }
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr2.src b/src/cmd/compile/internal/types2/testdata/check/expr2.src
index 0c959e8011944f0ce42b89bc193e448628bc762f..f9726b5de53202c301757e36ea5bde812cd3db24 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr2.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr2.src
@@ -10,7 +10,7 @@ func _bool() {
 	const t = true == true
 	const f = true == false
 	_ = t /* ERROR "cannot compare" */ < f
-	_ = 0 /* ERROR "cannot convert" */ == t
+	_ = 0 /* ERROR "mismatched types untyped int and untyped bool" */ == t
 	var b bool
 	var x, y float32
 	b = x < y
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr3.src b/src/cmd/compile/internal/types2/testdata/check/expr3.src
index eab3f72c4d5ff0d323151f3c3b9feff11cf29de3..fd28421dc89bebb56bd26d3dbafeee77613ba768 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr3.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr3.src
@@ -104,7 +104,7 @@ func indexes() {
 	var ok mybool
 	_, ok = m["bar"]
 	_ = ok
-	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "cannot convert"
+	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "mismatched types int and untyped string"
 
 	var t string
 	_ = t[- /* ERROR "negative" */ 1]
diff --git a/src/cmd/compile/internal/types2/testdata/check/issues.go2 b/src/cmd/compile/internal/types2/testdata/check/issues.go2
index 1c73b5da9219c04c1b2a479f594fc7d315ab3948..effc2db7ae3d1e47e314b85969b24c23edef8bae 100644
--- a/src/cmd/compile/internal/types2/testdata/check/issues.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/issues.go2
@@ -24,25 +24,23 @@ func _() {
 	eql[io.Reader](nil, nil)
 }
 
-// If we have a receiver of pointer type (below: *T) we must ignore
-// the pointer in the implementation of the method lookup because
-// the type bound of T is an interface and pointer to interface types
-// have no methods and then the lookup would fail.
+// If we have a receiver of pointer to type parameter type (below: *T)
+// we don't have any methods, like for interfaces.
 type C[T any] interface {
     m()
 }
 
 // using type bound C
 func _[T C[T]](x *T) {
-	x.m()
+	x.m /* ERROR x\.m undefined */ ()
 }
 
 // using an interface literal as bound
 func _[T interface{ m() }](x *T) {
-	x.m()
+	x.m /* ERROR x\.m undefined */ ()
 }
 
-func f2[_ interface{ m1(); m2() }]()
+func f2[_ interface{ m1(); m2() }]() {}
 
 type T struct{}
 func (T) m1()
@@ -57,15 +55,15 @@ func _() {
 // type with a type list constraint, all of the type argument's types in its
 // bound, but at least one (!), must be in the type list of the bound of the
 // corresponding parameterized type's type parameter.
-type T1[P interface{type uint}] struct{}
+type T1[P interface{~uint}] struct{}
 
 func _[P any]() {
-    _ = T1[P /* ERROR P has no type constraints */ ]{}
+    _ = T1[P /* ERROR P has no constraints */ ]{}
 }
 
 // This is the original (simplified) program causing the same issue.
 type Unsigned interface {
-	type uint
+	~uint
 }
 
 type T2[U Unsigned] struct {
@@ -76,8 +74,8 @@ func (u T2[U]) Add1() U {
     return u.s + 1
 }
 
-func NewT2[U any]() T2[U /* ERROR U has no type constraints */ ] {
-    return T2[U /* ERROR U has no type constraints */ ]{}
+func NewT2[U any]() T2[U /* ERROR U has no constraints */ ] {
+    return T2[U /* ERROR U has no constraints */ ]{}
 }
 
 func _() {
@@ -156,7 +154,7 @@ type inf2[T any] struct{ inf2 /* ERROR illegal cycle */ [T] }
 // predicate disjunction in the implementation was wrong because if a type list
 // contains both an integer and a floating-point type, the type parameter is
 // neither an integer or a floating-point number.
-func convert[T1, T2 interface{type int, uint, float32}](v T1) T2 {
+func convert[T1, T2 interface{~int | ~uint | ~float32}](v T1) T2 {
 	return T2(v)
 }
 
@@ -168,12 +166,12 @@ func _() {
 // both numeric, or both strings. The implementation had the same problem
 // with this check as the conversion issue above (issue #39623).
 
-func issue39623[T interface{type int, string}](x, y T) T {
+func issue39623[T interface{~int | ~string}](x, y T) T {
 	return x + y
 }
 
 // Simplified, from https://go2goplay.golang.org/p/efS6x6s-9NI:
-func Sum[T interface{type int, string}](s []T) (sum T) {
+func Sum[T interface{~int | ~string}](s []T) (sum T) {
 	for _, v := range s {
 		sum += v
 	}
@@ -182,19 +180,19 @@ func Sum[T interface{type int, string}](s []T) (sum T) {
 
 // Assignability of an unnamed pointer type to a type parameter that
 // has a matching underlying type.
-func _[T interface{}, PT interface{type *T}] (x T) PT {
+func _[T interface{}, PT interface{~*T}] (x T) PT {
     return &x
 }
 
 // Indexing of generic types containing type parameters in their type list:
-func at[T interface{ type []E }, E interface{}](x T, i int) E {
+func at[T interface{ ~[]E }, E interface{}](x T, i int) E {
         return x[i]
 }
 
 // A generic type inside a function acts like a named type. Its underlying
 // type is itself, its "operational type" is defined by the type list in
 // the tybe bound, if any.
-func _[T interface{type int}](x T) {
+func _[T interface{~int}](x T) {
 	type myint int
 	var _ int = int(x)
 	var _ T = 42
@@ -203,24 +201,24 @@ func _[T interface{type int}](x T) {
 
 // Indexing a generic type with an array type bound checks length.
 // (Example by mdempsky@.)
-func _[T interface { type [10]int }](x T) {
+func _[T interface { ~[10]int }](x T) {
 	_ = x[9] // ok
 	_ = x[20 /* ERROR out of bounds */ ]
 }
 
 // Pointer indirection of a generic type.
-func _[T interface{ type *int }](p T) int {
+func _[T interface{ ~*int }](p T) int {
 	return *p
 }
 
 // Channel sends and receives on generic types.
-func _[T interface{ type chan int }](ch T) int {
+func _[T interface{ ~chan int }](ch T) int {
 	ch <- 0
 	return <- ch
 }
 
 // Calling of a generic variable.
-func _[T interface{ type func() }](f T) {
+func _[T interface{ ~func() }](f T) {
 	f()
 	go f()
 }
@@ -232,9 +230,9 @@ func _[T interface{ type func() }](f T) {
 // type parameter that was substituted with a defined type.
 // Test case from an (originally) failing example.
 
-type sliceOf[E any] interface{ type []E }
+type sliceOf[E any] interface{ ~[]E }
 
-func append[T interface{}, S sliceOf[T], T2 interface{ type T }](s S, t ...T2) S
+func append[T interface{}, S sliceOf[T], T2 interface{}](s S, t ...T2) S { panic(0) }
 
 var f           func()
 var cancelSlice []context.CancelFunc
@@ -242,7 +240,7 @@ var _ = append[context.CancelFunc, []context.CancelFunc, context.CancelFunc](can
 
 // A generic function must be instantiated with a type, not a value.
 
-func g[T any](T) T
+func g[T any](T) T { panic(0) }
 
 var _ = g[int]
 var _ = g[nil /* ERROR is not a type */ ]
diff --git a/src/cmd/compile/internal/types2/testdata/check/issues.src b/src/cmd/compile/internal/types2/testdata/check/issues.src
index 21aa208cc769d2b872dbf1c46cacf1e7ae9d2382..692ed37ef4b9e881f788155fbd1f030201952564 100644
--- a/src/cmd/compile/internal/types2/testdata/check/issues.src
+++ b/src/cmd/compile/internal/types2/testdata/check/issues.src
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package issues
+package go1_17 // don't permit non-interface elements in interfaces
 
 import (
 	"fmt"
-	syn "cmd/compile/internal/syntax"
+	syn "regexp/syntax"
 	t1 "text/template"
 	t2 "html/template"
 )
@@ -329,10 +329,10 @@ func (... /* ERROR can only use ... with final parameter in list */ TT) f()
 func issue28281g() (... /* ERROR can only use ... with final parameter in list */ TT)
 
 // Issue #26234: Make various field/method lookup errors easier to read by matching cmd/compile's output
-func issue26234a(f *syn.File) {
+func issue26234a(f *syn.Prog) {
 	// The error message below should refer to the actual package name (syntax)
 	// not the local package name (syn).
-	f.foo /* ERROR f.foo undefined \(type \*syntax.File has no field or method foo\) */
+	f.foo /* ERROR f\.foo undefined \(type \*syntax\.Prog has no field or method foo\) */
 }
 
 type T struct {
@@ -357,11 +357,11 @@ func issue35895() {
 	var _ T = 0 // ERROR cannot use 0 \(untyped int constant\) as T
 
 	// There is only one package with name syntax imported, only use the (global) package name in error messages.
-	var _ *syn.File = 0 // ERROR cannot use 0 \(untyped int constant\) as \*syntax.File
+	var _ *syn.Prog = 0 // ERROR cannot use 0 \(untyped int constant\) as \*syntax.Prog
 
 	// Because both t1 and t2 have the same global package name (template),
 	// qualify packages with full path name in this case.
-	var _ t1.Template = t2 /* ERROR cannot use .* \(value of type "html/template".Template\) as "text/template".Template */ .Template{}
+	var _ t1.Template = t2 /* ERROR cannot use .* \(value of type .html/template.\.Template\) as .text/template.\.Template */ .Template{}
 }
 
 func issue42989(s uint) {
diff --git a/src/cmd/compile/internal/types2/testdata/check/linalg.go2 b/src/cmd/compile/internal/types2/testdata/check/linalg.go2
index 0d27603a5837a2747922d9c1e52802b840ca8c4e..efc090a1d1f0b788dd8977cf551ed2d77a40a108 100644
--- a/src/cmd/compile/internal/types2/testdata/check/linalg.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/linalg.go2
@@ -9,10 +9,10 @@ import "math"
 // Numeric is type bound that matches any numeric type.
 // It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
 }
 
 func DotProduct[T Numeric](s1, s2 []T) T {
@@ -42,14 +42,14 @@ func AbsDifference[T NumericAbs[T]](a, b T) T {
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // OrderedAbs is a helper type that defines an Abs method for
diff --git a/src/cmd/compile/internal/types2/testdata/check/map2.go2 b/src/cmd/compile/internal/types2/testdata/check/map2.go2
index 2833445662de813d6d3eeed95978c8342316b29f..be2c49f621efeff4b22a42ca683a5084224a210a 100644
--- a/src/cmd/compile/internal/types2/testdata/check/map2.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/map2.go2
@@ -114,7 +114,7 @@ func (it *Iterator[K, V]) Next() (K, V, bool) {
 
 // chans
 
-func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T])
+func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T]) { panic(0) }
 
 // A sender is used to send values to a Receiver.
 type chans_Sender[T any] struct {
diff --git a/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2 b/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2
index c2f282bae11a9817620365e445a9bc8b3f3b310f..1b406593f888a47fc8eb7682c142c9725402a9bc 100644
--- a/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2
@@ -10,7 +10,7 @@ package p
 
 type S struct{}
 
-func (S) m[T any](v T)
+func (S) m[T any](v T) {}
 
 // TODO(gri) Once we collect interface method type parameters
 //           in the parser, we can enable these tests again.
diff --git a/src/cmd/compile/internal/types2/testdata/check/stmt0.src b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
index bedcbe5fce3573f8aea5c8c8b2fb73786c0a9b17..d744f2ba814d593f0df5fb200b069bef1ab45cae 100644
--- a/src/cmd/compile/internal/types2/testdata/check/stmt0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
@@ -49,18 +49,18 @@ func assignments1() {
 	b = true
 
 	i += 1
-	i += "foo" /* ERROR "cannot convert.*int" */
+	i += "foo" /* ERROR "mismatched types int and untyped string" */
 
 	f -= 1
 	f /= 0
 	f = float32(0)/0 /* ERROR "division by zero" */
-	f -= "foo" /* ERROR "cannot convert.*float64" */
+	f -= "foo" /* ERROR "mismatched types float64 and untyped string" */
 
 	c *= 1
 	c /= 0
 
 	s += "bar"
-	s += 1 /* ERROR "cannot convert.*string" */
+	s += 1 /* ERROR "mismatched types string and untyped int" */
 
 	var u64 uint64
 	u64 += 1< 0 {
 		x0 = x[0]
@@ -118,9 +118,9 @@ func max[T interface{ type int }](x ...T) T {
 // Thus even if a type can be inferred successfully, the function
 // call may not be valid.
 
-func fboth[T any](chan T)
-func frecv[T any](<-chan T)
-func fsend[T any](chan<- T)
+func fboth[T any](chan T) {}
+func frecv[T any](<-chan T) {}
+func fsend[T any](chan<- T) {}
 
 func _() {
 	var both chan int
@@ -140,9 +140,9 @@ func _() {
 	fsend(send)
 }
 
-func ffboth[T any](func(chan T))
-func ffrecv[T any](func(<-chan T))
-func ffsend[T any](func(chan<- T))
+func ffboth[T any](func(chan T)) {}
+func ffrecv[T any](func(<-chan T)) {}
+func ffsend[T any](func(chan<- T)) {}
 
 func _() {
 	var both func(chan int)
@@ -169,9 +169,9 @@ func _() {
 // assignment is permitted, parameter passing is permitted as well,
 // so type inference should be able to handle these cases well.
 
-func g1[T any]([]T)
-func g2[T any]([]T, T)
-func g3[T any](*T, ...T)
+func g1[T any]([]T) {}
+func g2[T any]([]T, T) {}
+func g3[T any](*T, ...T) {}
 
 func _() {
 	type intSlize []int
@@ -195,7 +195,7 @@ func _() {
 
 // Here's a realistic example.
 
-func append[T any](s []T, t ...T) []T
+func append[T any](s []T, t ...T) []T { panic(0) }
 
 func _() {
 	var f func()
@@ -208,8 +208,12 @@ func _() {
 // (that would indicate a slice type). Thus, generic functions cannot
 // have empty type parameter lists, either. This is a syntax error.
 
-func h[] /* ERROR empty type parameter list */ ()
+func h[] /* ERROR empty type parameter list */ () {}
 
 func _() {
 	h[] /* ERROR operand */ ()
 }
+
+// Parameterized functions must have a function body.
+
+func _ /* ERROR missing function body */ [P any]()
diff --git a/src/cmd/compile/internal/types2/testdata/examples/inference.go2 b/src/cmd/compile/internal/types2/testdata/examples/inference.go2
index b47ce75805480539dcdf5fbef2ff350f6fc9cafe..e169aec74660bad3c4c3719ac8d07d2fe37e0872 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/inference.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/inference.go2
@@ -7,10 +7,10 @@
 package p
 
 type Ordered interface {
-	type int, float64, string
+	~int|~float64|~string
 }
 
-func min[T Ordered](x, y T) T
+func min[T Ordered](x, y T) T { panic(0) }
 
 func _() {
 	// min can be called with explicit instantiation.
@@ -37,7 +37,7 @@ func _() {
 	_ = min("foo", "bar")
 }
 
-func mixed[T1, T2, T3 any](T1, T2, T3)
+func mixed[T1, T2, T3 any](T1, T2, T3) {}
 
 func _() {
 	// mixed can be called with explicit instantiation.
@@ -54,7 +54,7 @@ func _() {
 	mixed[int, string](1.1 /* ERROR cannot use 1.1 */ , "", false)
 }
 
-func related1[Slice interface{type []Elem}, Elem any](s Slice, e Elem)
+func related1[Slice interface{~[]Elem}, Elem any](s Slice, e Elem) {}
 
 func _() {
 	// related1 can be called with explicit instantiation.
@@ -78,7 +78,7 @@ func _() {
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{type []Elem}](e Elem, s Slice)
+func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice) {}
 
 func _() {
 	// related2 can be called with explicit instantiation.
diff --git a/src/cmd/compile/internal/types2/testdata/examples/methods.go2 b/src/cmd/compile/internal/types2/testdata/examples/methods.go2
index 76c6539e1b7e7de019b7031025274eee082be8d7..4e87041e54771391056937e8b8e5424df025f5c5 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/methods.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/methods.go2
@@ -6,6 +6,8 @@
 
 package p
 
+import "unsafe"
+
 // Parameterized types may have methods.
 type T1[A any] struct{ a A }
 
@@ -94,3 +96,18 @@ func (_ T2[_, _, _]) _() int { return 42 }
 type T0 struct{}
 func (T0) _() {}
 func (T1[A]) _() {}
+
+// A generic receiver type may constrain its type parameter such
+// that it must be a pointer type. Such receiver types are not
+// permitted.
+type T3a[P interface{ ~int | ~string | ~float64 }] P
+
+func (T3a[_]) m() {} // this is ok
+
+type T3b[P interface{ ~unsafe.Pointer }] P
+
+func (T3b /* ERROR invalid receiver */ [_]) m() {}
+
+type T3c[P interface{ *int | *string }] P
+
+func (T3c /* ERROR invalid receiver */ [_]) m() {}
diff --git a/src/cmd/compile/internal/types2/testdata/examples/operations.go2 b/src/cmd/compile/internal/types2/testdata/examples/operations.go2
new file mode 100644
index 0000000000000000000000000000000000000000..18e4d6080c59f0307c55e94bf389e4109eb88a7f
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/examples/operations.go2
@@ -0,0 +1,29 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// indirection
+
+func _[P any](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ int }](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ *int }](p P) {
+        _ = *p
+}
+
+func _[P interface{ *int | *string }](p P) {
+        _ = *p // ERROR must have identical base types
+}
+
+type intPtr *int
+
+func _[P interface{ *int | intPtr } ](p P) {
+        var _ int = *p
+}
diff --git a/src/cmd/compile/internal/types2/testdata/examples/types.go2 b/src/cmd/compile/internal/types2/testdata/examples/types.go2
index a7825ed2d9bf7c421c23c9fb78549ce889d2fe91..9ee014452c5500c956ea4072328aaea36109c321 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/types.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/types.go2
@@ -155,30 +155,40 @@ type _ struct {
 	List /* ERROR List redeclared */ [int]
 }
 
+// Issue #45639: We don't allow this anymore. Keep this code
+//               in case we decide to revisit this decision.
+//
 // It's possible to declare local types whose underlying types
 // are type parameters. As with ordinary type definitions, the
 // types underlying properties are "inherited" but the methods
 // are not.
-func _[T interface{ m(); type int }]() {
-	type L T
-	var x L
-
-	// m is not defined on L (it is not "inherited" from
-	// its underlying type).
-	x.m /* ERROR x.m undefined */ ()
-
-	// But the properties of T, such that as that it supports
-	// the operations of the types given by its type bound,
-	// are also the properties of L.
-	x++
-	_ = x - x
-
-	// On the other hand, if we define a local alias for T,
-	// that alias stands for T as expected.
-	type A = T
-	var y A
-	y.m()
-	_ = y < 0
+// func _[T interface{ m(); ~int }]() {
+// 	type L T
+// 	var x L
+// 
+// 	// m is not defined on L (it is not "inherited" from
+// 	// its underlying type).
+// 	x.m /* ERROR x.m undefined */ ()
+// 
+// 	// But the properties of T, such that as that it supports
+// 	// the operations of the types given by its type bound,
+// 	// are also the properties of L.
+// 	x++
+// 	_ = x - x
+// 
+// 	// On the other hand, if we define a local alias for T,
+// 	// that alias stands for T as expected.
+// 	type A = T
+// 	var y A
+// 	y.m()
+// 	_ = y < 0
+// }
+
+// It is not permitted to declare a local type whose underlying
+// type is a type parameter not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
 }
 
 // As a special case, an explicit type argument may be omitted
@@ -206,15 +216,15 @@ type B0 interface {}
 type B1[_ any] interface{}
 type B2[_, _ any] interface{}
 
-func _[T1 B0]()
-func _[T1 B1[T1]]()
-func _[T1 B2 /* ERROR cannot use generic type .* without instantiation */ ]()
+func _[T1 B0]() {}
+func _[T1 B1[T1]]() {}
+func _[T1 B2 /* ERROR cannot use generic type .* without instantiation */ ]() {}
 
-func _[T1, T2 B0]()
-func _[T1 B1[T1], T2 B1[T2]]()
-func _[T1, T2 B2 /* ERROR cannot use generic type .* without instantiation */ ]()
+func _[T1, T2 B0]() {}
+func _[T1 B1[T1], T2 B1[T2]]() {}
+func _[T1, T2 B2 /* ERROR cannot use generic type .* without instantiation */ ]() {}
 
-func _[T1 B0, T2 B1[T2]]() // here B1 applies to T2
+func _[T1 B0, T2 B1[T2]]() {} // here B1 applies to T2
 
 // When the type argument is left away, the type bound is
 // instantiated for each type parameter with that type
@@ -232,11 +242,11 @@ func _[A Adder[A], B Adder[B], C Adder[A]]() {
 // The type of variables (incl. parameters and return values) cannot
 // be an interface with type constraints or be/embed comparable.
 type I interface {
-	type int
+	~int
 }
 
 var (
-	_ interface /* ERROR contains type constraints */ {type int}
+	_ interface /* ERROR contains type constraints */ {~int}
 	_ I /* ERROR contains type constraints */
 )
 
@@ -267,7 +277,7 @@ func _() {
 // (If a type list contains just a single const type, we could
 // allow it, but such type lists don't make much sense in the
 // first place.)
-func _[T interface { type int, float64 }]() {
+func _[T interface{~int|~float64}]() {
 	// not valid
 	const _ = T /* ERROR not constant */ (0)
 	const _ T /* ERROR invalid constant type T */ = 1
@@ -277,3 +287,19 @@ func _[T interface { type int, float64 }]() {
 	var _ T = 1
 	_ = T(0)
 }
+
+// It is possible to create composite literals of type parameter
+// type as long as it's possible to create a composite literal
+// of the structural type of the type parameter's constraint.
+func _[P interface{ ~[]int }]() P {
+	return P{}
+	return P{1, 2, 3}
+}
+
+func _[P interface{ ~[]E }, E interface{ map[string]P } ]() P {
+	x := P{}
+	return P{{}}
+	return P{E{}}
+	return P{E{"foo": x}}
+	return P{{"foo": x}, {}}
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2
index 2c1299feb09519d7499d09d937abf4abfb3f00bd..8d14f8acaf825937d8d77d59533978ddd87f58d9 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2
@@ -31,13 +31,14 @@ type x7[A any] struct{ foo7 }
 func main7() { var _ foo7 = x7[int]{} }
 
 // crash 8
-type foo8[A any] interface { type A }
-func bar8[A foo8[A]](a A) {}
-func main8() {}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// type foo8[A any] interface { ~A }
+// func bar8[A foo8[A]](a A) {}
+// func main8() {}
 
 // crash 9
-type foo9[A any] interface { type foo9 /* ERROR interface contains type constraints */ [A] }
-func _() { var _ = new(foo9 /* ERROR interface contains type constraints */ [int]) }
+type foo9[A any] interface { foo9 /* ERROR illegal cycle */ [A] }
+func _() { var _ = new(foo9 /* ERROR illegal cycle */ [int]) }
 
 // crash 12
 var u /* ERROR cycle */ , i [func /* ERROR used as value */ /* ERROR used as value */ (u, c /* ERROR undeclared */ /* ERROR undeclared */ ) {}(0, len /* ERROR must be called */ /* ERROR must be called */ )]c /* ERROR undeclared */ /* ERROR undeclared */
@@ -49,7 +50,7 @@ func (G15 /* ERROR generic type .* without instantiation */ ) p()
 
 // crash 16
 type Foo16[T any] r16 /* ERROR not a type */
-func r16[T any]() Foo16[Foo16[T]]
+func r16[T any]() Foo16[Foo16[T]] { panic(0) }
 
 // crash 17
 type Y17 interface{ c() }
@@ -57,7 +58,7 @@ type Z17 interface {
 	c() Y17
 	Y17 /* ERROR duplicate method */
 }
-func F17[T Z17](T)
+func F17[T Z17](T) {}
 
 // crash 18
 type o18[T any] []func(_ o18[[]_ /* ERROR cannot use _ */ ])
@@ -87,5 +88,5 @@ type T26 = interface{ F26[ /* ERROR cannot have type parameters */ Z any]() }
 func F26[Z any]() T26 { return F26 /* ERROR without instantiation */ /* ERROR missing method */ [] /* ERROR operand */ }
 
 // crash 27
-func e27[T any]() interface{ x27 /* ERROR not a type */ }
+func e27[T any]() interface{ x27 /* ERROR not a type */ } { panic(0) }
 func x27() { e27( /* ERROR cannot infer T */ ) }
\ No newline at end of file
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2
index 9bc26f35461345eb2f0d5728ba39fe793774723d..e56bc3547582d190f110b6f70a231e9e38012572 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2
@@ -4,16 +4,19 @@
 
 package p
 
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+
+/*
 import "fmt"
 
 // Minimal test case.
-func _[T interface{type T}](x T) T{
+func _[T interface{~T}](x T) T{
 	return x
 }
 
 // Test case from issue.
 type constr[T any] interface {
-	type T
+	~T
 }
 
 func Print[T constr[T]](s []T) {
@@ -25,3 +28,4 @@ func Print[T constr[T]](s []T) {
 func f() {
 	Print([]string{"Hello, ", "playground\n"})
 }
+*/
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2
index 316ab1982e89cf3635b1b1b16b3356f70a4d2b4f..301c13be41cce2b5fce7cec228cac0d9f1504f63 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2
@@ -4,11 +4,20 @@
 
 package p
 
-type Number interface {
-	int     /* ERROR int is not an interface */
-	float64 /* ERROR float64 is not an interface */
+type Number1 interface {
+	// embedding non-interface types is permitted
+	int
+	float64
 }
 
-func Add[T Number](a, b T) T {
+func Add1[T Number1](a, b T) T {
 	return a /* ERROR not defined */ + b
 }
+
+type Number2 interface {
+	int|float64
+}
+
+func Add2[T Number2](a, b T) T {
+	return a + b
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2
index 75491e7e26f00cd5b1d0ce771d471724ae7cdf9e..72f83997c2460a5496556cb1d294b9e260550c5d 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2
@@ -8,7 +8,7 @@ type T0 interface{
 }
 
 type T1 interface{
-	type int
+	~int
 }
 
 type T2 interface{
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2
index df621a4c1730db66648dd23c898a1238bdfce332..85eb0a78fe284a21b464b612bc7efafa8820b3ed 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2
@@ -7,5 +7,7 @@ package p
 // Do not report a duplicate type error for this type list.
 // (Check types after interfaces have been completed.)
 type _ interface {
-	type interface{ Error() string }, interface{ String() string }
+	// TODO(gri) Once we have full type sets we can enable this again.
+	// Fow now we don't permit interfaces in type lists.
+	// type interface{ Error() string }, interface{ String() string }
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2
index 55464e6b7759f09016050e541868a72b50e1dca1..d5311ed3e7538e9350a0df3dc23b137a88503ae4 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2
@@ -6,4 +6,4 @@ package p
 
 // A constraint must be an interface; it cannot
 // be a type parameter, for instance.
-func _[A interface{ type interface{} }, B A /* ERROR not an interface */ ]()
+func _[A interface{ ~int }, B A /* ERROR not an interface */ ]() {}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2
index e19b6770bfe4bd21462434f97ace29659a02c4ed..62dc45a59601eecc43e0b23fd09123cf00fbf57d 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2
@@ -4,13 +4,13 @@
 
 package p
 
-func f1[T1, T2 any](T1, T2, struct{a T1; b T2})
+func f1[T1, T2 any](T1, T2, struct{a T1; b T2}) {}
 func _() {
 	f1(42, string("foo"), struct /* ERROR does not match inferred type struct\{a int; b string\} */ {a, b int}{})
 }
 
 // simplified test case from issue
-func f2[T any](_ []T, _ func(T))
+func f2[T any](_ []T, _ func(T)) {}
 func _() {
 	f2([]string{}, func /* ERROR does not match inferred type func\(string\) */ (f []byte) {})
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2
index b7ab68818e9587897e7f916730644a3dc1f0af8b..257b73a2fbeff15a934f4daf4798952578bad9d5 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2
@@ -4,14 +4,14 @@
 
 package p
 
-func _[T interface{type map[string]int}](x T) {
+func _[T interface{~map[string]int}](x T) {
 	_ = x == nil
 }
 
 // simplified test case from issue
 
 type PathParamsConstraint interface {
-        type map[string]string, []struct{key, value string}
+        ~map[string]string | ~[]struct{key, value string}
 }
 
 type PathParams[T PathParamsConstraint] struct {
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2
index 76e7e369ca12bb6718272a2de41dfc7f6617d848..0da6e103fd1139b48d6d26e6d9b9ec9cee7ac5db 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2
@@ -8,8 +8,8 @@ package p
 
 type E0[P any] P
 type E1[P any] *P
-type E2[P any] struct{ P }
-type E3[P any] struct{ *P }
+type E2[P any] struct{ _ P }
+type E3[P any] struct{ _ *P }
 
 type T0 /* ERROR illegal cycle */ struct {
         _ E0[T0]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2
index c2b460902cc643b5537834e489f3213f551fe6f7..e38e57268d63d1fd00012274bd8ea23bc2a7c7df 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2
@@ -5,5 +5,5 @@
 package p
 
 type T[P any] interface{
-	P // ERROR P is a type parameter, not an interface
+	P // ERROR cannot embed a type parameter
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2
index 3db4eae0123930db81b5ff193e58ff802678878a..d703da90a2176a3e975f5a62cad5cf5b3f665faf 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2
@@ -7,7 +7,7 @@ package p
 type policy[K, V any] interface{}
 type LRU[K, V any] struct{}
 
-func NewCache[K, V any](p policy[K, V])
+func NewCache[K, V any](p policy[K, V]) {}
 
 func _() {
 	var lru LRU[int, string]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2
index 8948d61caa477fff40ac7f773946d0377df734e4..0981a335da3aa91cc12538ddc976f1e34e428e6d 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2
@@ -8,7 +8,7 @@ type A[T any] int
 
 func (A[T]) m(A[T])
 
-func f[P interface{m(P)}]()
+func f[P interface{m(P)}]() {}
 
 func _() {
 	_ = f[A[int]]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2
index 747aab49dd1639b79bbf7eb0efcf84787b337c4c..a3f3eecca098c6dbbace1dbc19eee13069484b6c 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2
@@ -10,6 +10,6 @@ func _() {
 
 type S struct {}
 
-func NewS[T any]() *S
+func NewS[T any]() *S { panic(0) }
 
 func (_ *S /* ERROR S is not a generic type */ [T]) M()
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2
index 5d97855f8a172ff414ae86c5112b500059a3142b..c78f9a1fa040892e7ebec27753100db2867752b2 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2
@@ -7,6 +7,6 @@ package p
 import "unsafe"
 
 func _[T any](x T) {
-	_ = unsafe /* ERROR undefined */ .Alignof(x)
-	_ = unsafe /* ERROR undefined */ .Sizeof(x)
+	_ = unsafe.Alignof(x)
+	_ = unsafe.Sizeof(x)
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2
index 0269c3a62ce6d0d10d92f0f2cb4e0ce8e82129cf..58d0f69f6503164328feb8990baa1d4bbf201c52 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2
@@ -6,8 +6,8 @@ package p
 
 type T[_ any] int
 
-func f[_ any]()
-func g[_, _ any]()
+func f[_ any]() {}
+func g[_, _ any]() {}
 
 func _() {
 	_ = f[T /* ERROR without instantiation */ ]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40789.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40789.go2
new file mode 100644
index 0000000000000000000000000000000000000000..9eea4ad60a6647380606f70fd998febab618db8c
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40789.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func main() {
+	m := map[string]int{
+		"a": 6,
+		"b": 7,
+	}
+	fmt.Println(copyMap[map[string]int, string, int](m))
+}
+
+type Map[K comparable, V any] interface {
+	map[K] V
+}
+
+func copyMap[M Map[K, V], K comparable, V any](m M) M {
+	m1 := make(M)
+	for k, v := range m {
+		m1[k] = v
+	}
+	return m1
+}
+
+// simpler test case from the same issue
+
+type A[X comparable] interface {
+	[]X
+}
+
+func f[B A[X], X comparable]() B {
+	return nil
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2
index 61f766bcbd7891ef16f8ca6396349e1ff43159f6..4642ab60fc8edaf7f78c709459f29b549258e33f 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2
@@ -7,7 +7,7 @@ package p
 // Test case from issue.
 
 type Nat interface {
-	type Zero, Succ
+	Zero|Succ
 }
 
 type Zero struct{}
@@ -22,7 +22,7 @@ type I1 interface {
 }
 
 type I2 interface {
-	type int
+	~int
 }
 
 type I3 interface {
@@ -47,7 +47,7 @@ type _ struct{
 }
 
 type _ struct{
-	I3 // ERROR interface contains type constraints
+	I3 // ERROR interface is .* comparable
 }
 
 // General composite types.
@@ -59,19 +59,19 @@ type (
 	_ []I1 // ERROR interface is .* comparable
 	_ []I2 // ERROR interface contains type constraints
 
-	_ *I3 // ERROR interface contains type constraints
+	_ *I3 // ERROR interface is .* comparable
 	_ map[I1 /* ERROR interface is .* comparable */ ]I2 // ERROR interface contains type constraints
-	_ chan I3 // ERROR interface contains type constraints
+	_ chan I3 // ERROR interface is .* comparable
 	_ func(I1 /* ERROR interface is .* comparable */ )
 	_ func() I2 // ERROR interface contains type constraints
 )
 
 // Other cases.
 
-var _ = [...]I3 /* ERROR interface contains type constraints */ {}
+var _ = [...]I3 /* ERROR interface is .* comparable */ {}
 
 func _(x interface{}) {
-	_ = x.(I3 /* ERROR interface contains type constraints */ )
+	_ = x.(I3 /* ERROR interface is .* comparable */ )
 }
 
 type T1[_ any] struct{}
@@ -79,9 +79,9 @@ type T3[_, _, _ any] struct{}
 var _ T1[I2 /* ERROR interface contains type constraints */ ]
 var _ T3[int, I2 /* ERROR interface contains type constraints */ , float32]
 
-func f1[_ any]() int
+func f1[_ any]() int { panic(0) }
 var _ = f1[I2 /* ERROR interface contains type constraints */ ]()
-func f3[_, _, _ any]() int
+func f3[_, _, _ any]() int { panic(0) }
 var _ = f3[int, I2 /* ERROR interface contains type constraints */ , float32]()
 
 func _(x interface{}) {
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2
index 698cb8a16bad26194a40f5893e7a1d493b30083c..bf0031f5d244305720afb8c8d2f2710c5b8bbaf9 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2
@@ -17,7 +17,7 @@ func _[T any](x interface{}){
 }
 
 type constraint interface {
-	type int
+	~int
 }
 
 func _[T constraint](x interface{}){
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2
new file mode 100644
index 0000000000000000000000000000000000000000..6cc3801cc96b8b38ed8ef4c9ea6e4a8ad6c54081
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2
@@ -0,0 +1,58 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | <-chan T }
+
+func _[T any](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C0](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C1](ch T) {
+	<-ch
+}
+
+func _[T C2](ch T) {
+	<-ch
+}
+
+func _[T C3](ch T) {
+	<-ch // ERROR channels of ch .* must have the same element type
+}
+
+func _[T C4](ch T) {
+	<-ch // ERROR cannot receive from send-only channel
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	x = <-ch
+}
+
+// test case from issue, slightly modified
+type RecvChan[T any] interface {
+	~chan T | ~<-chan T
+}
+
+func _[T any, C RecvChan[T]](ch C) T {
+	return <-ch
+}
+
+func f[T any, C interface{ chan T }](ch C) T {
+	return <-ch
+}
+
+func _(ch chan int) {
+	var x int = f(ch) // test constraint type inference for this case
+	_ = x
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
index b1e42497e8586c500d11985f0df6c70249927949..b8ba0ad4a70915b4edaca42bb24ca60f1088a2bd 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{type *Q}, G interface{type *R}, Q, R any](q Q, r R) {}
+func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2
index 65662cdc7662938f72e41f4770149277cbdaedda..29379591057a6148a38cc0ff6ede246c527ee79e 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2
@@ -13,7 +13,7 @@ type N[T any] struct{}
 var _ N[] /* ERROR expecting type */
 
 type I interface {
-	type map[int]int, []int
+	~[]int
 }
 
 func _[T I](i, j int) {
@@ -27,6 +27,5 @@ func _[T I](i, j int) {
 	_ = s[i, j /* ERROR more than one index */ ]
 
 	var t T
-	// TODO(gri) fix multiple error below
-	_ = t[i, j /* ERROR more than one index */ /* ERROR more than one index */ ]
+	_ = t[i, j /* ERROR more than one index */ ]
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45639.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45639.go2
new file mode 100644
index 0000000000000000000000000000000000000000..441fb4cb346211c684e0a9e51247102b89ed7048
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45639.go2
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package P
+
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
index 7678e348ef99ce2733eaa741fcd3e3b1d13e0e46..f25b9d2b266c45010da8e8d857ad4e4427bc64d8 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
@@ -5,7 +5,7 @@
 package issue45985
 
 // TODO(gri): this error should be on app[int] below.
-func app[S /* ERROR "type S = S does not match" */ interface{ type []T }, T any](s S, e T) S {
+func app[S /* ERROR "type S = S does not match" */ interface{ ~[]T }, T any](s S, e T) S {
     return append(s, e)
 }
 
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46090.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46090.go2
new file mode 100644
index 0000000000000000000000000000000000000000..81b31974c8dc0207e0833d51c845b978ce26cef4
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46090.go2
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The predeclared type comparable is not visible before Go 1.18.
+
+package go1_17
+
+type _ comparable // ERROR undeclared
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46275.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46275.go2
new file mode 100644
index 0000000000000000000000000000000000000000..f41ae26e4bdda6fd5815434d0c96887006154a9b
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46275.go2
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package issue46275
+
+type N[T any] struct {
+        *N[T]
+        t T
+}
+
+func (n *N[T]) Elem() T {
+        return n.t
+}
+
+type I interface {
+        Elem() string
+}
+
+func _() {
+        var n1 *N[string]
+        var _ I = n1
+        type NS N[string]
+        var n2 *NS
+        var _ I = n2
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src
new file mode 100644
index 0000000000000000000000000000000000000000..da1f1ffbbaf6c2d29054d9d65f9226199e426363
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src
@@ -0,0 +1,28 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type T1 struct{}
+func (t T1) m(int) {}
+var f1 func(T1)
+
+type T2 struct{}
+func (t T2) m(x int) {}
+var f2 func(T2)
+
+type T3 struct{}
+func (T3) m(int) {}
+var f3 func(T3)
+
+type T4 struct{}
+func (T4) m(x int) {}
+var f4 func(T4)
+
+func _() {
+	f1 = T1 /* ERROR func\(T1, int\) */ .m
+	f2 = T2 /* ERROR func\(t T2, x int\) */ .m
+	f3 = T3 /* ERROR func\(T3, int\) */ .m
+	f4 = T4 /* ERROR func\(_ T4, x int\) */ .m
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2
new file mode 100644
index 0000000000000000000000000000000000000000..b184f9b5b7dfbf7255d9bd6587fb78acce371fb6
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Mer interface { M() }
+
+func F[T Mer](p *T) {
+	p.M /* ERROR p\.M undefined */ ()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+
+func _() {
+	F(new(MyMer))
+	F[Mer](nil)
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2
new file mode 100644
index 0000000000000000000000000000000000000000..00828eb997be5cfe834b3f8ea5679c038b9633c9
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2
@@ -0,0 +1,40 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	ch /* ERROR cannot send to non-channel */ <- 0
+}
+
+func _[T C0](ch T) {
+	ch /* ERROR cannot send to non-channel */ <- 0
+}
+
+func _[T C1](ch T) {
+	ch <- 0
+}
+
+func _[T C2](ch T) {
+	ch /* ERROR cannot send to receive-only channel */ <- 0
+}
+
+func _[T C3](ch T) {
+	ch /* ERROR channels of ch .* must have the same element type */ <- 0
+}
+
+func _[T C4](ch T) {
+	ch <- 0
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	ch <- x
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47127.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47127.go2
new file mode 100644
index 0000000000000000000000000000000000000000..108d600a38a6c9ce9075ca792ab7abf4077f1d8e
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47127.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Embedding of stand-alone type parameters is not permitted.
+
+package p
+
+type (
+        _[P any] interface{ *P | []P | chan P | map[string]P }
+        _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+)
+
+func _[P any]() {
+        type (
+                _[P any] interface{ *P | []P | chan P | map[string]P }
+                _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+
+                _ interface{ *P | []P | chan P | map[string]P }
+                _ interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+        )
+}
+
+func _[P any, Q interface{ *P | []P | chan P | map[string]P }]() {}
+func _[P any, Q interface{ P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ ~P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ int | P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }]() {}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47411.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47411.go2
new file mode 100644
index 0000000000000000000000000000000000000000..77281a19a2032cf3ac8a250f8a3280fbbca342ef
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47411.go2
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f[_ comparable]() {}
+func g[_ interface{interface{comparable; ~int|~string}}]() {}
+
+func _[P comparable,
+        Q interface{ comparable; ~int|~string },
+        R any,                               // not comparable
+        S interface{ comparable; ~func() },  // not comparable
+]() {
+        _ = f[int]
+        _ = f[P]
+        _ = f[Q]
+        _ = f[func( /* ERROR does not satisfy comparable */ )]
+        _ = f[R /* ERROR R has no constraints */ ]
+
+        _ = g[int]
+        _ = g[P /* ERROR P has no type constraints */ ]
+        _ = g[Q]
+        _ = g[func( /* ERROR does not satisfy comparable */ )]
+        _ = g[R /* ERROR R has no constraints */ ]
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47747.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47747.go2
new file mode 100644
index 0000000000000000000000000000000000000000..af52056bef2ad91606a289f3168aa28a4ca13624
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47747.go2
@@ -0,0 +1,68 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type T1[P any] P
+
+func (T1[_]) m() {}
+
+func _[P any](x *T1[P]) {
+        // x.m exists because x is of type *T1 where T1 is a defined type
+        // (even though under(T1) is a type parameter)
+        x.m()
+}
+
+
+func _[P interface{ m() }](x P) {
+        x.m()
+        // (&x).m doesn't exist because &x is of type *P
+        // and pointers to type parameters don't have methods
+        (&x).m /* ERROR \*P has no field or method m */ ()
+}
+
+
+type T2 interface{ m() }
+
+func _(x *T2) {
+        // x.m doesn't exists because x is of type *T2
+        // and pointers to interfaces don't have methods
+        x.m /* ERROR \*T2 has no field or method m */()
+}
+
+// Test case 1 from issue
+
+type Fooer1[t any] interface {
+	Foo(Barer[t])
+}
+type Barer[t any] interface {
+	Bar(t)
+}
+
+type Foo1[t any] t
+type Bar[t any] t
+
+func (l Foo1[t]) Foo(v Barer[t]) { v.Bar(t(l)) }
+func (b *Bar[t]) Bar(l t)        { *b = Bar[t](l) }
+
+func _[t any](f Fooer1[t]) t {
+	var b Bar[t]
+	f.Foo(&b)
+	return t(b)
+}
+
+// Test case 2 from issue
+
+type Fooer2[t any] interface {
+	Foo()
+}
+
+type Foo2[t any] t
+
+func (f *Foo2[t]) Foo() {}
+
+func _[t any](v t) {
+	var f = Foo2[t](v)
+	_ = Fooer2[t](&f)
+}
diff --git a/src/cmd/compile/internal/types2/tuple.go b/src/cmd/compile/internal/types2/tuple.go
new file mode 100644
index 0000000000000000000000000000000000000000..a3946beab573412b102946ab04e6c5eb78ca8b1c
--- /dev/null
+++ b/src/cmd/compile/internal/types2/tuple.go
@@ -0,0 +1,36 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
+// Tuples are used as components of signatures and to represent the type of multiple
+// assignments; they are not first class types of Go.
+type Tuple struct {
+	vars []*Var
+}
+
+// NewTuple returns a new tuple for the given variables.
+func NewTuple(x ...*Var) *Tuple {
+	if len(x) > 0 {
+		return &Tuple{vars: x}
+	}
+	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
+	//           it's too subtle and causes problems.
+	return nil
+}
+
+// Len returns the number variables of tuple t.
+func (t *Tuple) Len() int {
+	if t != nil {
+		return len(t.vars)
+	}
+	return 0
+}
+
+// At returns the i'th variable of tuple t.
+func (t *Tuple) At(i int) *Var { return t.vars[i] }
+
+func (t *Tuple) Underlying() Type { return t }
+func (t *Tuple) String() string   { return TypeString(t, nil) }
diff --git a/src/cmd/compile/internal/types2/type.go b/src/cmd/compile/internal/types2/type.go
index e6c260ff6790c6663438ad62ce3e21b232712a1a..4b8642aa9629df7b22af72ae22dd71c08b28e05d 100644
--- a/src/cmd/compile/internal/types2/type.go
+++ b/src/cmd/compile/internal/types2/type.go
@@ -4,12 +4,6 @@
 
 package types2
 
-import (
-	"cmd/compile/internal/syntax"
-	"fmt"
-	"sync/atomic"
-)
-
 // A Type represents a type of Go.
 // All types implement the Type interface.
 type Type interface {
@@ -22,895 +16,55 @@ type Type interface {
 	String() string
 }
 
-// BasicKind describes the kind of basic type.
-type BasicKind int
-
-const (
-	Invalid BasicKind = iota // type is invalid
-
-	// predeclared types
-	Bool
-	Int
-	Int8
-	Int16
-	Int32
-	Int64
-	Uint
-	Uint8
-	Uint16
-	Uint32
-	Uint64
-	Uintptr
-	Float32
-	Float64
-	Complex64
-	Complex128
-	String
-	UnsafePointer
-
-	// types for untyped values
-	UntypedBool
-	UntypedInt
-	UntypedRune
-	UntypedFloat
-	UntypedComplex
-	UntypedString
-	UntypedNil
-
-	// aliases
-	Byte = Uint8
-	Rune = Int32
-)
-
-// BasicInfo is a set of flags describing properties of a basic type.
-type BasicInfo int
-
-// Properties of basic types.
-const (
-	IsBoolean BasicInfo = 1 << iota
-	IsInteger
-	IsUnsigned
-	IsFloat
-	IsComplex
-	IsString
-	IsUntyped
-
-	IsOrdered   = IsInteger | IsFloat | IsString
-	IsNumeric   = IsInteger | IsFloat | IsComplex
-	IsConstType = IsBoolean | IsNumeric | IsString
-)
-
-// A Basic represents a basic type.
-type Basic struct {
-	kind BasicKind
-	info BasicInfo
-	name string
-}
-
-// Kind returns the kind of basic type b.
-func (b *Basic) Kind() BasicKind { return b.kind }
-
-// Info returns information about properties of basic type b.
-func (b *Basic) Info() BasicInfo { return b.info }
-
-// Name returns the name of basic type b.
-func (b *Basic) Name() string { return b.name }
-
-// An Array represents an array type.
-type Array struct {
-	len  int64
-	elem Type
-}
-
-// NewArray returns a new array type for the given element type and length.
-// A negative length indicates an unknown length.
-func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
-
-// Len returns the length of array a.
-// A negative result indicates an unknown length.
-func (a *Array) Len() int64 { return a.len }
-
-// Elem returns element type of array a.
-func (a *Array) Elem() Type { return a.elem }
-
-// A Slice represents a slice type.
-type Slice struct {
-	elem Type
-}
-
-// NewSlice returns a new slice type for the given element type.
-func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
-
-// Elem returns the element type of slice s.
-func (s *Slice) Elem() Type { return s.elem }
-
-// A Struct represents a struct type.
-type Struct struct {
-	fields []*Var
-	tags   []string // field tags; nil if there are no tags
-}
-
-// NewStruct returns a new struct with the given fields and corresponding field tags.
-// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
-// only as long as required to hold the tag with the largest index i. Consequently,
-// if no field has a tag, tags may be nil.
-func NewStruct(fields []*Var, tags []string) *Struct {
-	var fset objset
-	for _, f := range fields {
-		if f.name != "_" && fset.insert(f) != nil {
-			panic("multiple fields with the same name")
-		}
-	}
-	if len(tags) > len(fields) {
-		panic("more tags than fields")
-	}
-	return &Struct{fields: fields, tags: tags}
-}
-
-// NumFields returns the number of fields in the struct (including blank and embedded fields).
-func (s *Struct) NumFields() int { return len(s.fields) }
-
-// Field returns the i'th field for 0 <= i < NumFields().
-func (s *Struct) Field(i int) *Var { return s.fields[i] }
-
-// Tag returns the i'th field tag for 0 <= i < NumFields().
-func (s *Struct) Tag(i int) string {
-	if i < len(s.tags) {
-		return s.tags[i]
-	}
-	return ""
-}
-
-// A Pointer represents a pointer type.
-type Pointer struct {
-	base Type // element type
-}
-
-// NewPointer returns a new pointer type for the given element (base) type.
-func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
-
-// Elem returns the element type for the given pointer p.
-func (p *Pointer) Elem() Type { return p.base }
-
-// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
-// Tuples are used as components of signatures and to represent the type of multiple
-// assignments; they are not first class types of Go.
-type Tuple struct {
-	vars []*Var
-}
-
-// NewTuple returns a new tuple for the given variables.
-func NewTuple(x ...*Var) *Tuple {
-	if len(x) > 0 {
-		return &Tuple{vars: x}
-	}
-	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
-	//           it's too subtle and causes problems.
-	return nil
-}
-
-// Len returns the number variables of tuple t.
-func (t *Tuple) Len() int {
-	if t != nil {
-		return len(t.vars)
-	}
-	return 0
-}
-
-// At returns the i'th variable of tuple t.
-func (t *Tuple) At(i int) *Var { return t.vars[i] }
-
-// A Signature represents a (non-builtin) function or method type.
-// The receiver is ignored when comparing signatures for identity.
-type Signature struct {
-	// We need to keep the scope in Signature (rather than passing it around
-	// and store it in the Func Object) because when type-checking a function
-	// literal we call the general type checker which returns a general Type.
-	// We then unpack the *Signature and use the scope for the literal body.
-	rparams  []*TypeName // receiver type parameters from left to right; or nil
-	tparams  []*TypeName // type parameters from left to right; or nil
-	scope    *Scope      // function scope, present for package-local signatures
-	recv     *Var        // nil if not a method
-	params   *Tuple      // (incoming) parameters from left to right; or nil
-	results  *Tuple      // (outgoing) results from left to right; or nil
-	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
-}
-
-// NewSignature returns a new function type for the given receiver, parameters,
-// and results, either of which may be nil. If variadic is set, the function
-// is variadic, it must have at least one parameter, and the last parameter
-// must be of unnamed slice type.
-func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
-	if variadic {
-		n := params.Len()
-		if n == 0 {
-			panic("types2.NewSignature: variadic function must have at least one parameter")
-		}
-		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
-			panic("types2.NewSignature: variadic parameter must be of unnamed slice type")
-		}
-	}
-	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
-}
-
-// Recv returns the receiver of signature s (if a method), or nil if a
-// function. It is ignored when comparing signatures for identity.
-//
-// For an abstract method, Recv returns the enclosing interface either
-// as a *Named or an *Interface. Due to embedding, an interface may
-// contain methods whose receiver type is a different interface.
-func (s *Signature) Recv() *Var { return s.recv }
-
-// TParams returns the type parameters of signature s, or nil.
-func (s *Signature) TParams() []*TypeName { return s.tparams }
-
-// RParams returns the receiver type params of signature s, or nil.
-func (s *Signature) RParams() []*TypeName { return s.rparams }
-
-// SetTParams sets the type parameters of signature s.
-func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = tparams }
-
-// Params returns the parameters of signature s, or nil.
-func (s *Signature) Params() *Tuple { return s.params }
-
-// Results returns the results of signature s, or nil.
-func (s *Signature) Results() *Tuple { return s.results }
-
-// Variadic reports whether the signature s is variadic.
-func (s *Signature) Variadic() bool { return s.variadic }
-
-// A Sum represents a set of possible types.
-// Sums are currently used to represent type lists of interfaces
-// and thus the underlying types of type parameters; they are not
-// first class types of Go.
-type Sum struct {
-	types []Type // types are unique
-}
-
-// NewSum returns a new Sum type consisting of the provided
-// types if there are more than one. If there is exactly one
-// type, it returns that type. If the list of types is empty
-// the result is nil.
-func NewSum(types []Type) Type {
-	if len(types) == 0 {
-		return nil
-	}
-
-	// What should happen if types contains a sum type?
-	// Do we flatten the types list? For now we check
-	// and panic. This should not be possible for the
-	// current use case of type lists.
-	// TODO(gri) Come up with the rules for sum types.
-	for _, t := range types {
-		if _, ok := t.(*Sum); ok {
-			panic("sum type contains sum type - unimplemented")
-		}
-	}
-
-	if len(types) == 1 {
-		return types[0]
-	}
-	return &Sum{types: types}
-}
-
-// is reports whether all types in t satisfy pred.
-func (s *Sum) is(pred func(Type) bool) bool {
-	if s == nil {
-		return false
-	}
-	for _, t := range s.types {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// An Interface represents an interface type.
-type Interface struct {
-	methods   []*Func // ordered list of explicitly declared methods
-	types     Type    // (possibly a Sum) type declared with a type list (TODO(gri) need better field name)
-	embeddeds []Type  // ordered list of explicitly embedded types
-
-	allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)
-	allTypes   Type    // intersection of all embedded and locally declared types  (TODO(gri) need better field name)
-
-	obj Object // type declaration defining this interface; or nil (for better error messages)
-}
-
-// unpack unpacks a type into a list of types.
-// TODO(gri) Try to eliminate the need for this function.
-func unpack(typ Type) []Type {
-	if typ == nil {
-		return nil
-	}
-	if sum := asSum(typ); sum != nil {
-		return sum.types
-	}
-	return []Type{typ}
-}
-
-// is reports whether interface t represents types that all satisfy pred.
-func (t *Interface) is(pred func(Type) bool) bool {
-	if t.allTypes == nil {
-		return false // we must have at least one type! (was bug)
-	}
-	for _, t := range unpack(t.allTypes) {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// emptyInterface represents the empty (completed) interface
-var emptyInterface = Interface{allMethods: markComplete}
-
-// markComplete is used to mark an empty interface as completely
-// set up by setting the allMethods field to a non-nil empty slice.
-var markComplete = make([]*Func, 0)
-
-// NewInterface returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type.
-// NewInterface takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-//
-// Deprecated: Use NewInterfaceType instead which allows any (even non-defined) interface types
-// to be embedded. This is necessary for interfaces that embed alias type names referring to
-// non-defined (literal) interface types.
-func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
-	tnames := make([]Type, len(embeddeds))
-	for i, t := range embeddeds {
-		tnames[i] = t
-	}
-	return NewInterfaceType(methods, tnames)
-}
-
-// NewInterfaceType returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type (this property is not
-// verified for defined types, which may be in the process of being set up and which don't
-// have a valid underlying type yet).
-// NewInterfaceType takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
-	if len(methods) == 0 && len(embeddeds) == 0 {
-		return &emptyInterface
-	}
-
-	// set method receivers if necessary
-	typ := new(Interface)
-	for _, m := range methods {
-		if sig := m.typ.(*Signature); sig.recv == nil {
-			sig.recv = NewVar(m.pos, m.pkg, "", typ)
-		}
-	}
-
-	// All embedded types should be interfaces; however, defined types
-	// may not yet be fully resolved. Only verify that non-defined types
-	// are interfaces. This matches the behavior of the code before the
-	// fix for #25301 (issue #25596).
-	for _, t := range embeddeds {
-		if _, ok := t.(*Named); !ok && !IsInterface(t) {
-			panic("embedded type is not an interface")
-		}
-	}
-
-	// sort for API stability
-	sortMethods(methods)
-	sortTypes(embeddeds)
-
-	typ.methods = methods
-	typ.embeddeds = embeddeds
-	return typ
-}
-
-// NumExplicitMethods returns the number of explicitly declared methods of interface t.
-func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
-
-// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
-// The methods are ordered by their unique Id.
-func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
-
-// NumEmbeddeds returns the number of embedded types in interface t.
-func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
-
-// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
-// The result is nil if the i'th embedded type is not a defined type.
-//
-// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
-func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
-
-// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
-func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
-
-// NumMethods returns the total number of methods of interface t.
-// The interface must have been completed.
-func (t *Interface) NumMethods() int { t.assertCompleteness(); return len(t.allMethods) }
-
-func (t *Interface) assertCompleteness() {
-	if t.allMethods == nil {
-		panic("interface is incomplete")
-	}
-}
-
-// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
-// The methods are ordered by their unique Id.
-// The interface must have been completed.
-func (t *Interface) Method(i int) *Func { t.assertCompleteness(); return t.allMethods[i] }
-
-// Empty reports whether t is the empty interface.
-func (t *Interface) Empty() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		// A non-nil allTypes may still be empty and represents the bottom type.
-		return len(t.allMethods) == 0 && t.allTypes == nil
-	}
-	return !t.iterate(func(t *Interface) bool {
-		return len(t.methods) > 0 || t.types != nil
-	}, nil)
-}
-
-// HasTypeList reports whether interface t has a type list, possibly from an embedded type.
-func (t *Interface) HasTypeList() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		return t.allTypes != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		return t.types != nil
-	}, nil)
-}
-
-// IsComparable reports whether interface t is or embeds the predeclared interface "comparable".
-func (t *Interface) IsComparable() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// IsConstraint reports t.HasTypeList() || t.IsComparable().
-func (t *Interface) IsConstraint() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		if t.allTypes != nil {
-			return true
-		}
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		if t.types != nil {
-			return true
-		}
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// iterate calls f with t and then with any embedded interface of t, recursively, until f returns true.
-// iterate reports whether any call to f returned true.
-func (t *Interface) iterate(f func(*Interface) bool, seen map[*Interface]bool) bool {
-	if f(t) {
-		return true
-	}
-	for _, e := range t.embeddeds {
-		// e should be an interface but be careful (it may be invalid)
-		if e := asInterface(e); e != nil {
-			// Cyclic interfaces such as "type E interface { E }" are not permitted
-			// but they are still constructed and we need to detect such cycles.
-			if seen[e] {
-				continue
-			}
-			if seen == nil {
-				seen = make(map[*Interface]bool)
-			}
-			seen[e] = true
-			if e.iterate(f, seen) {
-				return true
-			}
-		}
-	}
-	return false
-}
-
-// isSatisfiedBy reports whether interface t's type list is satisfied by the type typ.
-// If the type list is empty (absent), typ trivially satisfies the interface.
-// TODO(gri) This is not a great name. Eventually, we should have a more comprehensive
-//           "implements" predicate.
-func (t *Interface) isSatisfiedBy(typ Type) bool {
-	t.Complete()
-	if t.allTypes == nil {
-		return true
-	}
-	types := unpack(t.allTypes)
-	return includes(types, typ) || includes(types, under(typ))
-}
-
-// Complete computes the interface's method set. It must be called by users of
-// NewInterfaceType and NewInterface after the interface's embedded types are
-// fully defined and before using the interface type in any way other than to
-// form other types. The interface must not contain duplicate methods or a
-// panic occurs. Complete returns the receiver.
-func (t *Interface) Complete() *Interface {
-	// TODO(gri) consolidate this method with Checker.completeInterface
-	if t.allMethods != nil {
-		return t
-	}
-
-	t.allMethods = markComplete // avoid infinite recursion
-
-	var todo []*Func
-	var methods []*Func
-	var seen objset
-	addMethod := func(m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-		case explicit:
-			panic("duplicate method " + m.name)
-		default:
-			// check method signatures after all locally embedded interfaces are computed
-			todo = append(todo, m, other.(*Func))
-		}
-	}
-
-	for _, m := range t.methods {
-		addMethod(m, true)
-	}
-
-	allTypes := t.types
+// top represents the top of the type lattice.
+// It is the underlying type of a type parameter that
+// can be satisfied by any type (ignoring methods),
+// because its type constraint contains no restrictions
+// besides methods.
+type top struct{}
 
-	for _, typ := range t.embeddeds {
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				panic(fmt.Sprintf("%s is not an interface", typ))
-			}
-			continue
-		}
-		etyp.Complete()
-		for _, m := range etyp.allMethods {
-			addMethod(m, false)
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
+// theTop is the singleton top type.
+var theTop = &top{}
 
-	for i := 0; i < len(todo); i += 2 {
-		m := todo[i]
-		other := todo[i+1]
-		if !Identical(m.typ, other.typ) {
-			panic("duplicate method " + m.name)
-		}
-	}
+func (t *top) Underlying() Type { return t }
+func (t *top) String() string   { return TypeString(t, nil) }
 
-	if methods != nil {
-		sortMethods(methods)
-		t.allMethods = methods
+// under returns the true expanded underlying type.
+// If it doesn't exist, the result is Typ[Invalid].
+// under must only be called when a type is known
+// to be fully set up.
+func under(t Type) Type {
+	// TODO(gri) is this correct for *Union?
+	if n := asNamed(t); n != nil {
+		return n.under()
 	}
-	t.allTypes = allTypes
-
 	return t
 }
 
-// A Map represents a map type.
-type Map struct {
-	key, elem Type
-}
-
-// NewMap returns a new map for the given key and element types.
-func NewMap(key, elem Type) *Map {
-	return &Map{key: key, elem: elem}
-}
-
-// Key returns the key type of map m.
-func (m *Map) Key() Type { return m.key }
-
-// Elem returns the element type of map m.
-func (m *Map) Elem() Type { return m.elem }
-
-// A Chan represents a channel type.
-type Chan struct {
-	dir  ChanDir
-	elem Type
-}
-
-// A ChanDir value indicates a channel direction.
-type ChanDir int
-
-// The direction of a channel is indicated by one of these constants.
-const (
-	SendRecv ChanDir = iota
-	SendOnly
-	RecvOnly
-)
-
-// NewChan returns a new channel type for the given direction and element type.
-func NewChan(dir ChanDir, elem Type) *Chan {
-	return &Chan{dir: dir, elem: elem}
-}
-
-// Dir returns the direction of channel c.
-func (c *Chan) Dir() ChanDir { return c.dir }
-
-// Elem returns the element type of channel c.
-func (c *Chan) Elem() Type { return c.elem }
-
-// TODO(gri) Clean up Named struct below; specifically the fromRHS field (can we use underlying?).
-
-// A Named represents a named (defined) type.
-type Named struct {
-	check      *Checker    // for Named.under implementation
-	info       typeInfo    // for cycle detection
-	obj        *TypeName   // corresponding declared object
-	orig       *Named      // original, uninstantiated type
-	fromRHS    Type        // type (on RHS of declaration) this *Named type is derived from (for cycle reporting)
-	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
-	tparams    []*TypeName // type parameters, or nil
-	targs      []Type      // type arguments (after instantiation), or nil
-	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
-}
-
-// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
-// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
-// The underlying type must not be a *Named.
-func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
-	if _, ok := underlying.(*Named); ok {
-		panic("types2.NewNamed: underlying type must not be *Named")
-	}
-	return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods)
-}
-
-// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
-func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams []*TypeName, methods []*Func) *Named {
-	typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods}
-	if typ.orig == nil {
-		typ.orig = typ
-	}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	return typ
-}
-
-// Obj returns the type name for the named type t.
-func (t *Named) Obj() *TypeName { return t.obj }
-
-// Orig returns the original generic type an instantiated type is derived from.
-// If t is not an instantiated type, the result is t.
-func (t *Named) Orig() *Named { return t.orig }
-
-// TODO(gri) Come up with a better representation and API to distinguish
-//           between parameterized instantiated and non-instantiated types.
-
-// TParams returns the type parameters of the named type t, or nil.
-// The result is non-nil for an (originally) parameterized type even if it is instantiated.
-func (t *Named) TParams() []*TypeName { return t.tparams }
-
-// SetTParams sets the type parameters of the named type t.
-func (t *Named) SetTParams(tparams []*TypeName) { t.tparams = tparams }
-
-// TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
-func (t *Named) TArgs() []Type { return t.targs }
-
-// SetTArgs sets the type arguments of the named type t.
-func (t *Named) SetTArgs(args []Type) { t.targs = args }
-
-// NumMethods returns the number of explicit methods whose receiver is named type t.
-func (t *Named) NumMethods() int { return len(t.methods) }
-
-// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
-func (t *Named) Method(i int) *Func { return t.methods[i] }
-
-// SetUnderlying sets the underlying type and marks t as complete.
-func (t *Named) SetUnderlying(underlying Type) {
-	if underlying == nil {
-		panic("types2.Named.SetUnderlying: underlying type must not be nil")
-	}
-	if _, ok := underlying.(*Named); ok {
-		panic("types2.Named.SetUnderlying: underlying type must not be *Named")
-	}
-	t.underlying = underlying
-}
-
-// AddMethod adds method m unless it is already in the method list.
-func (t *Named) AddMethod(m *Func) {
-	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
-		t.methods = append(t.methods, m)
-	}
-}
-
-// Note: This is a uint32 rather than a uint64 because the
-// respective 64 bit atomic instructions are not available
-// on all platforms.
-var lastId uint32
-
-// nextId returns a value increasing monotonically by 1 with
-// each call, starting with 1. It may be called concurrently.
-func nextId() uint64 { return uint64(atomic.AddUint32(&lastId, 1)) }
-
-// A TypeParam represents a type parameter type.
-type TypeParam struct {
-	check *Checker  // for lazy type bound completion
-	id    uint64    // unique id, for debugging only
-	obj   *TypeName // corresponding type name
-	index int       // type parameter index in source order, starting at 0
-	bound Type      // *Named or *Interface; underlying type is always *Interface
-}
-
-// Obj returns the type name for the type parameter t.
-func (t *TypeParam) Obj() *TypeName { return t.obj }
-
-// NewTypeParam returns a new TypeParam.
-func (check *Checker) NewTypeParam(obj *TypeName, index int, bound Type) *TypeParam {
-	assert(bound != nil)
-	typ := &TypeParam{check: check, id: nextId(), obj: obj, index: index, bound: bound}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	return typ
-}
-
-func (t *TypeParam) Bound() *Interface {
-	iface := asInterface(t.bound)
-	// use the type bound position if we have one
-	pos := nopos
-	if n, _ := t.bound.(*Named); n != nil {
-		pos = n.obj.pos
-	}
-	// TODO(gri) switch this to an unexported method on Checker.
-	t.check.completeInterface(pos, iface)
-	return iface
-}
-
 // optype returns a type's operational type. Except for
 // type parameters, the operational type is the same
 // as the underlying type (as returned by under). For
-// Type parameters, the operational type is determined
-// by the corresponding type bound's type list. The
-// result may be the bottom or top type, but it is never
-// the incoming type parameter.
+// Type parameters, the operational type is the structural
+// type, if any; otherwise it's the top type.
+// The result is never the incoming type parameter.
 func optype(typ Type) Type {
 	if t := asTypeParam(typ); t != nil {
+		// TODO(gri) review accuracy of this comment
 		// If the optype is typ, return the top type as we have
 		// no information. It also prevents infinite recursion
 		// via the asTypeParam converter function. This can happen
 		// for a type parameter list of the form:
 		// (type T interface { type T }).
 		// See also issue #39680.
-		if u := t.Bound().allTypes; u != nil && u != typ {
-			// u != typ and u is a type parameter => under(u) != typ, so this is ok
-			return under(u)
+		if u := t.structuralType(); u != nil {
+			assert(u != typ) // "naked" type parameters cannot be embedded
+			return u
 		}
 		return theTop
 	}
 	return under(typ)
 }
 
-// An instance represents an instantiated generic type syntactically
-// (without expanding the instantiation). Type instances appear only
-// during type-checking and are replaced by their fully instantiated
-// (expanded) types before the end of type-checking.
-type instance struct {
-	check   *Checker     // for lazy instantiation
-	pos     syntax.Pos   // position of type instantiation; for error reporting only
-	base    *Named       // parameterized type to be instantiated
-	targs   []Type       // type arguments
-	poslist []syntax.Pos // position of each targ; for error reporting only
-	value   Type         // base(targs...) after instantiation or Typ[Invalid]; nil if not yet set
-}
-
-// expand returns the instantiated (= expanded) type of t.
-// The result is either an instantiated *Named type, or
-// Typ[Invalid] if there was an error.
-func (t *instance) expand() Type {
-	v := t.value
-	if v == nil {
-		v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist)
-		if v == nil {
-			v = Typ[Invalid]
-		}
-		t.value = v
-	}
-	// After instantiation we must have an invalid or a *Named type.
-	if debug && v != Typ[Invalid] {
-		_ = v.(*Named)
-	}
-	return v
-}
-
-// expand expands a type instance into its instantiated
-// type and leaves all other types alone. expand does
-// not recurse.
-func expand(typ Type) Type {
-	if t, _ := typ.(*instance); t != nil {
-		return t.expand()
-	}
-	return typ
-}
-
-// expandf is set to expand.
-// Call expandf when calling expand causes compile-time cycle error.
-var expandf func(Type) Type
-
-func init() { expandf = expand }
-
-// bottom represents the bottom of the type lattice.
-// It is the underlying type of a type parameter that
-// cannot be satisfied by any type, usually because
-// the intersection of type constraints left nothing).
-type bottom struct{}
-
-// theBottom is the singleton bottom type.
-var theBottom = &bottom{}
-
-// top represents the top of the type lattice.
-// It is the underlying type of a type parameter that
-// can be satisfied by any type (ignoring methods),
-// usually because the type constraint has no type
-// list.
-type top struct{}
-
-// theTop is the singleton top type.
-var theTop = &top{}
-
-// Type-specific implementations of Underlying.
-func (t *Basic) Underlying() Type     { return t }
-func (t *Array) Underlying() Type     { return t }
-func (t *Slice) Underlying() Type     { return t }
-func (t *Struct) Underlying() Type    { return t }
-func (t *Pointer) Underlying() Type   { return t }
-func (t *Tuple) Underlying() Type     { return t }
-func (t *Signature) Underlying() Type { return t }
-func (t *Sum) Underlying() Type       { return t }
-func (t *Interface) Underlying() Type { return t }
-func (t *Map) Underlying() Type       { return t }
-func (t *Chan) Underlying() Type      { return t }
-func (t *Named) Underlying() Type     { return t.underlying }
-func (t *TypeParam) Underlying() Type { return t }
-func (t *instance) Underlying() Type  { return t }
-func (t *bottom) Underlying() Type    { return t }
-func (t *top) Underlying() Type       { return t }
-
-// Type-specific implementations of String.
-func (t *Basic) String() string     { return TypeString(t, nil) }
-func (t *Array) String() string     { return TypeString(t, nil) }
-func (t *Slice) String() string     { return TypeString(t, nil) }
-func (t *Struct) String() string    { return TypeString(t, nil) }
-func (t *Pointer) String() string   { return TypeString(t, nil) }
-func (t *Tuple) String() string     { return TypeString(t, nil) }
-func (t *Signature) String() string { return TypeString(t, nil) }
-func (t *Sum) String() string       { return TypeString(t, nil) }
-func (t *Interface) String() string { return TypeString(t, nil) }
-func (t *Map) String() string       { return TypeString(t, nil) }
-func (t *Chan) String() string      { return TypeString(t, nil) }
-func (t *Named) String() string     { return TypeString(t, nil) }
-func (t *TypeParam) String() string { return TypeString(t, nil) }
-func (t *instance) String() string  { return TypeString(t, nil) }
-func (t *bottom) String() string    { return TypeString(t, nil) }
-func (t *top) String() string       { return TypeString(t, nil) }
-
-// under returns the true expanded underlying type.
-// If it doesn't exist, the result is Typ[Invalid].
-// under must only be called when a type is known
-// to be fully set up.
-func under(t Type) Type {
-	// TODO(gri) is this correct for *Sum?
-	if n := asNamed(t); n != nil {
-		return n.under()
-	}
-	return t
-}
-
 // Converters
 //
 // A converter must only be called when a type is
@@ -944,39 +98,26 @@ func asPointer(t Type) *Pointer {
 	return op
 }
 
-// asTuple is not needed - not provided
-
 func asSignature(t Type) *Signature {
 	op, _ := optype(t).(*Signature)
 	return op
 }
 
-func asSum(t Type) *Sum {
-	op, _ := optype(t).(*Sum)
-	return op
-}
+// If the argument to asInterface, asNamed, or asTypeParam is of the respective type
+// (possibly after expanding an instance type), these methods return that type.
+// Otherwise the result is nil.
 
+// asInterface does not need to look at optype (type sets don't contain interfaces)
 func asInterface(t Type) *Interface {
-	op, _ := optype(t).(*Interface)
-	return op
-}
-
-func asMap(t Type) *Map {
-	op, _ := optype(t).(*Map)
-	return op
-}
-
-func asChan(t Type) *Chan {
-	op, _ := optype(t).(*Chan)
-	return op
+	u, _ := under(t).(*Interface)
+	return u
 }
 
-// If the argument to asNamed and asTypeParam is of the respective types
-// (possibly after expanding an instance type), these methods return that type.
-// Otherwise the result is nil.
-
 func asNamed(t Type) *Named {
-	e, _ := expand(t).(*Named)
+	e, _ := t.(*Named)
+	if e != nil {
+		e.expand(nil)
+	}
 	return e
 }
 
@@ -991,3 +132,4 @@ func AsPointer(t Type) *Pointer     { return asPointer(t) }
 func AsNamed(t Type) *Named         { return asNamed(t) }
 func AsSignature(t Type) *Signature { return asSignature(t) }
 func AsInterface(t Type) *Interface { return asInterface(t) }
+func AsTypeParam(t Type) *TypeParam { return asTypeParam(t) }
diff --git a/src/cmd/compile/internal/types2/typelists.go b/src/cmd/compile/internal/types2/typelists.go
new file mode 100644
index 0000000000000000000000000000000000000000..3258a5e9f87301809fd4227bf6ce992afbfb3ee1
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typelists.go
@@ -0,0 +1,69 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// TParamList holds a list of type parameters.
+type TParamList struct{ tparams []*TypeParam }
+
+// Len returns the number of type parameters in the list.
+// It is safe to call on a nil receiver.
+func (l *TParamList) Len() int { return len(l.list()) }
+
+// At returns the i'th type parameter in the list.
+func (l *TParamList) At(i int) *TypeParam { return l.tparams[i] }
+
+// list is for internal use where we expect a []*TypeParam.
+// TODO(rfindley): list should probably be eliminated: we can pass around a
+// TParamList instead.
+func (l *TParamList) list() []*TypeParam {
+	if l == nil {
+		return nil
+	}
+	return l.tparams
+}
+
+// TypeList holds a list of types.
+type TypeList struct{ types []Type }
+
+// NewTypeList returns a new TypeList with the types in list.
+func NewTypeList(list []Type) *TypeList {
+	if len(list) == 0 {
+		return nil
+	}
+	return &TypeList{list}
+}
+
+// Len returns the number of types in the list.
+// It is safe to call on a nil receiver.
+func (l *TypeList) Len() int { return len(l.list()) }
+
+// At returns the i'th type in the list.
+func (l *TypeList) At(i int) Type { return l.types[i] }
+
+// list is for internal use where we expect a []Type.
+// TODO(rfindley): list should probably be eliminated: we can pass around a
+// TypeList instead.
+func (l *TypeList) list() []Type {
+	if l == nil {
+		return nil
+	}
+	return l.types
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func bindTParams(list []*TypeParam) *TParamList {
+	if len(list) == 0 {
+		return nil
+	}
+	for i, typ := range list {
+		if typ.index >= 0 {
+			panic("type parameter bound more than once")
+		}
+		typ.index = i
+	}
+	return &TParamList{tparams: list}
+}
diff --git a/src/cmd/compile/internal/types2/typeparam.go b/src/cmd/compile/internal/types2/typeparam.go
new file mode 100644
index 0000000000000000000000000000000000000000..445337fee88ed85b5a8bd6f3e661ff2cd4815682
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeparam.go
@@ -0,0 +1,108 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "sync/atomic"
+
+// Note: This is a uint32 rather than a uint64 because the
+// respective 64 bit atomic instructions are not available
+// on all platforms.
+var lastID uint32
+
+// nextID returns a value increasing monotonically by 1 with
+// each call, starting with 1. It may be called concurrently.
+func nextID() uint64 { return uint64(atomic.AddUint32(&lastID, 1)) }
+
+// A TypeParam represents a type parameter type.
+type TypeParam struct {
+	check *Checker  // for lazy type bound completion
+	id    uint64    // unique id, for debugging only
+	obj   *TypeName // corresponding type name
+	index int       // type parameter index in source order, starting at 0
+	// TODO(rfindley): this could also be Typ[Invalid]. Verify that this is handled correctly.
+	bound Type // *Named or *Interface; underlying type is always *Interface
+}
+
+// Obj returns the type name for the type parameter t.
+func (t *TypeParam) Obj() *TypeName { return t.obj }
+
+// NewTypeParam returns a new TypeParam. Type parameters may be set on a Named
+// or Signature type by calling SetTParams. Setting a type parameter on more
+// than one type will result in a panic.
+//
+// The bound argument can be nil, and set later via SetBound.
+func (check *Checker) NewTypeParam(obj *TypeName, bound Type) *TypeParam {
+	// Always increment lastID, even if it is not used.
+	id := nextID()
+	if check != nil {
+		check.nextID++
+		id = check.nextID
+	}
+	typ := &TypeParam{check: check, id: id, obj: obj, index: -1, bound: bound}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	return typ
+}
+
+// Index returns the index of the type param within its param list.
+func (t *TypeParam) Index() int {
+	return t.index
+}
+
+// SetId sets the unique id of a type param. Should only be used for type params
+// in imported generic types.
+func (t *TypeParam) SetId(id uint64) {
+	t.id = id
+}
+
+// Constraint returns the type constraint specified for t.
+func (t *TypeParam) Constraint() Type {
+	// compute the type set if possible (we may not have an interface)
+	if iface, _ := under(t.bound).(*Interface); iface != nil {
+		// use the type bound position if we have one
+		pos := nopos
+		if n, _ := t.bound.(*Named); n != nil {
+			pos = n.obj.pos
+		}
+		computeInterfaceTypeSet(t.check, pos, iface)
+	}
+	return t.bound
+}
+
+// SetConstraint sets the type constraint for t.
+func (t *TypeParam) SetConstraint(bound Type) {
+	if bound == nil {
+		panic("nil constraint")
+	}
+	t.bound = bound
+}
+
+func (t *TypeParam) Underlying() Type { return t }
+func (t *TypeParam) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// iface returns the constraint interface of t.
+func (t *TypeParam) iface() *Interface {
+	if iface, _ := under(t.Constraint()).(*Interface); iface != nil {
+		return iface
+	}
+	return &emptyInterface
+}
+
+// structuralType returns the structural type of the type parameter's constraint; or nil.
+func (t *TypeParam) structuralType() Type {
+	return t.iface().typeSet().structuralType()
+}
+
+func (t *TypeParam) is(f func(*term) bool) bool {
+	return t.iface().typeSet().is(f)
+}
+
+func (t *TypeParam) underIs(f func(Type) bool) bool {
+	return t.iface().typeSet().underIs(f)
+}
diff --git a/src/cmd/compile/internal/types2/types_test.go b/src/cmd/compile/internal/types2/types_test.go
index 096402148d38ad481815ad916e00664dfd0419c2..1525844f2dfcc2cbf07784b75afe6cfb9bbdd9ab 100644
--- a/src/cmd/compile/internal/types2/types_test.go
+++ b/src/cmd/compile/internal/types2/types_test.go
@@ -4,14 +4,9 @@
 
 package types2
 
-import "sync/atomic"
-
 func init() {
 	acceptMethodTypeParams = true
 }
 
-// Upon calling ResetId, nextId starts with 1 again.
-// It may be called concurrently. This is only needed
-// for tests where we may want to have a consistent
-// numbering for each individual test case.
-func ResetId() { atomic.StoreUint32(&lastId, 0) }
+// Debug is set if types2 is built with debug mode enabled.
+const Debug = debug
diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go
new file mode 100644
index 0000000000000000000000000000000000000000..14596b68a30295d090277bfabcfc8ada16682756
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeset.go
@@ -0,0 +1,392 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"bytes"
+	"cmd/compile/internal/syntax"
+	"fmt"
+	"sort"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A _TypeSet represents the type set of an interface.
+type _TypeSet struct {
+	comparable bool // if set, the interface is or embeds comparable
+	// TODO(gri) consider using a set for the methods for faster lookup
+	methods []*Func  // all methods of the interface; sorted by unique ID
+	terms   termlist // type terms of the type set
+}
+
+// IsEmpty reports whether type set s is the empty set.
+func (s *_TypeSet) IsEmpty() bool { return s.terms.isEmpty() }
+
+// IsAll reports whether type set s is the set of all types (corresponding to the empty interface).
+func (s *_TypeSet) IsAll() bool {
+	return !s.comparable && len(s.methods) == 0 && s.terms.isAll()
+}
+
+// TODO(gri) IsMethodSet is not a great name for this predicate. Find a better one.
+
+// IsMethodSet reports whether the type set s is described by a single set of methods.
+func (s *_TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isAll() }
+
+// IsComparable reports whether each type in the set is comparable.
+func (s *_TypeSet) IsComparable() bool {
+	if s.terms.isAll() {
+		return s.comparable
+	}
+	return s.is(func(t *term) bool {
+		return Comparable(t.typ)
+	})
+}
+
+// TODO(gri) IsTypeSet is not a great name for this predicate. Find a better one.
+
+// IsTypeSet reports whether the type set s is represented by a finite set of underlying types.
+func (s *_TypeSet) IsTypeSet() bool {
+	return !s.comparable && len(s.methods) == 0
+}
+
+// NumMethods returns the number of methods available.
+func (s *_TypeSet) NumMethods() int { return len(s.methods) }
+
+// Method returns the i'th method of type set s for 0 <= i < s.NumMethods().
+// The methods are ordered by their unique ID.
+func (s *_TypeSet) Method(i int) *Func { return s.methods[i] }
+
+// LookupMethod returns the index of and method with matching package and name, or (-1, nil).
+func (s *_TypeSet) LookupMethod(pkg *Package, name string) (int, *Func) {
+	// TODO(gri) s.methods is sorted - consider binary search
+	return lookupMethod(s.methods, pkg, name)
+}
+
+func (s *_TypeSet) String() string {
+	switch {
+	case s.IsEmpty():
+		return "∅"
+	case s.IsAll():
+		return "𝓤"
+	}
+
+	hasMethods := len(s.methods) > 0
+	hasTerms := s.hasTerms()
+
+	var buf bytes.Buffer
+	buf.WriteByte('{')
+	if s.comparable {
+		buf.WriteString(" comparable")
+		if hasMethods || hasTerms {
+			buf.WriteByte(';')
+		}
+	}
+	for i, m := range s.methods {
+		if i > 0 {
+			buf.WriteByte(';')
+		}
+		buf.WriteByte(' ')
+		buf.WriteString(m.String())
+	}
+	if hasMethods && hasTerms {
+		buf.WriteByte(';')
+	}
+	if hasTerms {
+		buf.WriteString(s.terms.String())
+	}
+	buf.WriteString(" }") // there was at least one method or term
+
+	return buf.String()
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (s *_TypeSet) hasTerms() bool              { return !s.terms.isAll() }
+func (s *_TypeSet) structuralType() Type        { return s.terms.structuralType() }
+func (s *_TypeSet) includes(t Type) bool        { return s.terms.includes(t) }
+func (s1 *_TypeSet) subsetOf(s2 *_TypeSet) bool { return s1.terms.subsetOf(s2.terms) }
+
+// TODO(gri) TypeSet.is and TypeSet.underIs should probably also go into termlist.go
+
+var topTerm = term{false, theTop}
+
+func (s *_TypeSet) is(f func(*term) bool) bool {
+	if len(s.terms) == 0 {
+		return false
+	}
+	for _, t := range s.terms {
+		// Terms represent the top term with a nil type.
+		// The rest of the type checker uses the top type
+		// instead. Convert.
+		// TODO(gri) investigate if we can do without this
+		if t.typ == nil {
+			t = &topTerm
+		}
+		if !f(t) {
+			return false
+		}
+	}
+	return true
+}
+
+func (s *_TypeSet) underIs(f func(Type) bool) bool {
+	if len(s.terms) == 0 {
+		return false
+	}
+	for _, t := range s.terms {
+		// see corresponding comment in TypeSet.is
+		u := t.typ
+		if u == nil {
+			u = theTop
+		}
+		// t == under(t) for ~t terms
+		if !t.tilde {
+			u = under(u)
+		}
+		if debug {
+			assert(Identical(u, under(u)))
+		}
+		if !f(u) {
+			return false
+		}
+	}
+	return true
+}
+
+// topTypeSet may be used as type set for the empty interface.
+var topTypeSet = _TypeSet{terms: allTermlist}
+
+// computeInterfaceTypeSet may be called with check == nil.
+func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_TypeSet {
+	if ityp.tset != nil {
+		return ityp.tset
+	}
+
+	// If the interface is not fully set up yet, the type set will
+	// not be complete, which may lead to errors when using the the
+	// type set (e.g. missing method). Don't compute a partial type
+	// set (and don't store it!), so that we still compute the full
+	// type set eventually. Instead, return the top type set and
+	// let any follow-on errors play out.
+	if !ityp.complete {
+		return &topTypeSet
+	}
+
+	if check != nil && check.conf.Trace {
+		// Types don't generally have position information.
+		// If we don't have a valid pos provided, try to use
+		// one close enough.
+		if !pos.IsKnown() && len(ityp.methods) > 0 {
+			pos = ityp.methods[0].pos
+		}
+
+		check.trace(pos, "type set for %s", ityp)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(pos, "=> %s ", ityp.typeSet())
+		}()
+	}
+
+	// An infinitely expanding interface (due to a cycle) is detected
+	// elsewhere (Checker.validType), so here we simply assume we only
+	// have valid interfaces. Mark the interface as complete to avoid
+	// infinite recursion if the validType check occurs later for some
+	// reason.
+	ityp.tset = &_TypeSet{terms: allTermlist} // TODO(gri) is this sufficient?
+
+	// Methods of embedded interfaces are collected unchanged; i.e., the identity
+	// of a method I.m's Func Object of an interface I is the same as that of
+	// the method m in an interface that embeds interface I. On the other hand,
+	// if a method is embedded via multiple overlapping embedded interfaces, we
+	// don't provide a guarantee which "original m" got chosen for the embedding
+	// interface. See also issue #34421.
+	//
+	// If we don't care to provide this identity guarantee anymore, instead of
+	// reusing the original method in embeddings, we can clone the method's Func
+	// Object and give it the position of a corresponding embedded interface. Then
+	// we can get rid of the mpos map below and simply use the cloned method's
+	// position.
+
+	var todo []*Func
+	var seen objset
+	var methods []*Func
+	mpos := make(map[*Func]syntax.Pos) // method specification or method embedding position, for good error messages
+	addMethod := func(pos syntax.Pos, m *Func, explicit bool) {
+		switch other := seen.insert(m); {
+		case other == nil:
+			methods = append(methods, m)
+			mpos[m] = pos
+		case explicit:
+			if check == nil {
+				panic(fmt.Sprintf("%s: duplicate method %s", m.pos, m.name))
+			}
+			// check != nil
+			var err error_
+			err.errorf(pos, "duplicate method %s", m.name)
+			err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
+			check.report(&err)
+		default:
+			// We have a duplicate method name in an embedded (not explicitly declared) method.
+			// Check method signatures after all types are computed (issue #33656).
+			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
+			// error here as well (even though we could do it eagerly) because it's the same
+			// error message.
+			if check == nil {
+				// check method signatures after all locally embedded interfaces are computed
+				todo = append(todo, m, other.(*Func))
+				break
+			}
+			// check != nil
+			check.later(func() {
+				if !check.allowVersion(m.pkg, 1, 14) || !Identical(m.typ, other.Type()) {
+					var err error_
+					err.errorf(pos, "duplicate method %s", m.name)
+					err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
+					check.report(&err)
+				}
+			})
+		}
+	}
+
+	for _, m := range ityp.methods {
+		addMethod(m.pos, m, true)
+	}
+
+	// collect embedded elements
+	var allTerms = allTermlist
+	for i, typ := range ityp.embeddeds {
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
+		var pos syntax.Pos // embedding position
+		if ityp.embedPos != nil {
+			pos = (*ityp.embedPos)[i]
+		}
+		var terms termlist
+		switch u := under(typ).(type) {
+		case *Interface:
+			tset := computeInterfaceTypeSet(check, pos, u)
+			if tset.comparable {
+				ityp.tset.comparable = true
+			}
+			for _, m := range tset.methods {
+				addMethod(pos, m, false) // use embedding position pos rather than m.pos
+			}
+			terms = tset.terms
+		case *Union:
+			tset := computeUnionTypeSet(check, pos, u)
+			if tset == &invalidTypeSet {
+				continue // ignore invalid unions
+			}
+			terms = tset.terms
+		case *TypeParam:
+			// Embedding stand-alone type parameters is not permitted.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if typ == Typ[Invalid] {
+				continue
+			}
+			if check != nil && !check.allowVersion(check.pkg, 1, 18) {
+				check.errorf(pos, "%s is not an interface", typ)
+				continue
+			}
+			terms = termlist{{false, typ}}
+		}
+		// The type set of an interface is the intersection
+		// of the type sets of all its elements.
+		// Intersection cannot produce longer termlists and
+		// thus cannot overflow.
+		allTerms = allTerms.intersect(terms)
+	}
+	ityp.embedPos = nil // not needed anymore (errors have been reported)
+
+	// process todo's (this only happens if check == nil)
+	for i := 0; i < len(todo); i += 2 {
+		m := todo[i]
+		other := todo[i+1]
+		if !Identical(m.typ, other.typ) {
+			panic(fmt.Sprintf("%s: duplicate method %s", m.pos, m.name))
+		}
+	}
+
+	if methods != nil {
+		sortMethods(methods)
+		ityp.tset.methods = methods
+	}
+	ityp.tset.terms = allTerms
+
+	return ityp.tset
+}
+
+func sortMethods(list []*Func) {
+	sort.Sort(byUniqueMethodName(list))
+}
+
+func assertSortedMethods(list []*Func) {
+	if !debug {
+		panic("assertSortedMethods called outside debug mode")
+	}
+	if !sort.IsSorted(byUniqueMethodName(list)) {
+		panic("methods not sorted")
+	}
+}
+
+// byUniqueMethodName method lists can be sorted by their unique method names.
+type byUniqueMethodName []*Func
+
+func (a byUniqueMethodName) Len() int           { return len(a) }
+func (a byUniqueMethodName) Less(i, j int) bool { return a[i].less(&a[j].object) }
+func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+// invalidTypeSet is a singleton type set to signal an invalid type set
+// due to an error. It's also a valid empty type set, so consumers of
+// type sets may choose to ignore it.
+var invalidTypeSet _TypeSet
+
+// computeUnionTypeSet may be called with check == nil.
+// The result is &invalidTypeSet if the union overflows.
+func computeUnionTypeSet(check *Checker, pos syntax.Pos, utyp *Union) *_TypeSet {
+	if utyp.tset != nil {
+		return utyp.tset
+	}
+
+	// avoid infinite recursion (see also computeInterfaceTypeSet)
+	utyp.tset = new(_TypeSet)
+
+	var allTerms termlist
+	for _, t := range utyp.terms {
+		var terms termlist
+		switch u := under(t.typ).(type) {
+		case *Interface:
+			terms = computeInterfaceTypeSet(check, pos, u).terms
+		case *TypeParam:
+			// A stand-alone type parameters is not permitted as union term.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if t.typ == Typ[Invalid] {
+				continue
+			}
+			terms = termlist{(*term)(t)}
+		}
+		// The type set of a union expression is the union
+		// of the type sets of each term.
+		allTerms = allTerms.union(terms)
+		if len(allTerms) > maxTermCount {
+			if check != nil {
+				check.errorf(pos, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+			}
+			utyp.tset = &invalidTypeSet
+			return utyp.tset
+		}
+	}
+	utyp.tset.terms = allTerms
+
+	return utyp.tset
+}
diff --git a/src/cmd/compile/internal/types2/typeset_test.go b/src/cmd/compile/internal/types2/typeset_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..0e14d523c8be46dc148603b244f5d544a2206939
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeset_test.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "testing"
+
+func TestInvalidTypeSet(t *testing.T) {
+	if !invalidTypeSet.IsEmpty() {
+		t.Error("invalidTypeSet is not empty")
+	}
+}
+
+// TODO(gri) add more tests
diff --git a/src/cmd/compile/internal/types2/typestring.go b/src/cmd/compile/internal/types2/typestring.go
index 40016697b7c90f99c6319f0dae6c9079f3db0767..2c34d036db8cbff8e9783fe85ae5530c52868fd1 100644
--- a/src/cmd/compile/internal/types2/typestring.go
+++ b/src/cmd/compile/internal/types2/typestring.go
@@ -39,27 +39,6 @@ func RelativeTo(pkg *Package) Qualifier {
 	}
 }
 
-// If gcCompatibilityMode is set, printing of types is modified
-// to match the representation of some types in the gc compiler:
-//
-//	- byte and rune lose their alias name and simply stand for
-//	  uint8 and int32 respectively
-//	- embedded interfaces get flattened (the embedding info is lost,
-//	  and certain recursive interface types cannot be printed anymore)
-//
-// This makes it easier to compare packages computed with the type-
-// checker vs packages imported from gc export data.
-//
-// Caution: This flag affects all uses of WriteType, globally.
-// It is only provided for testing in conjunction with
-// gc-generated data.
-//
-// This flag is exported in the x/tools/go/types package. We don't
-// need it at the moment in the std repo and so we don't export it
-// anymore. We should eventually try to remove it altogether.
-// TODO(gri) remove this
-var gcCompatibilityMode bool
-
 // TypeString returns the string representation of typ.
 // The Qualifier controls the printing of
 // package-level objects, and may be nil.
@@ -106,16 +85,6 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 				break
 			}
 		}
-
-		if gcCompatibilityMode {
-			// forget the alias names
-			switch t.kind {
-			case Byte:
-				t = Typ[Uint8]
-			case Rune:
-				t = Typ[Int32]
-			}
-		}
 		buf.WriteString(t.name)
 
 	case *Array:
@@ -157,80 +126,39 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		buf.WriteString("func")
 		writeSignature(buf, t, qf, visited)
 
-	case *Sum:
-		for i, t := range t.types {
+	case *Union:
+		// Unions only appear as (syntactic) embedded elements
+		// in interfaces and syntactically cannot be empty.
+		if t.Len() == 0 {
+			panic("empty union")
+		}
+		for i, t := range t.terms {
 			if i > 0 {
-				buf.WriteString(", ")
+				buf.WriteByte('|')
 			}
-			writeType(buf, t, qf, visited)
+			if t.tilde {
+				buf.WriteByte('~')
+			}
+			writeType(buf, t.typ, qf, visited)
 		}
 
 	case *Interface:
-		// We write the source-level methods and embedded types rather
-		// than the actual method set since resolved method signatures
-		// may have non-printable cycles if parameters have embedded
-		// interface types that (directly or indirectly) embed the
-		// current interface. For instance, consider the result type
-		// of m:
-		//
-		//     type T interface{
-		//         m() interface{ T }
-		//     }
-		//
 		buf.WriteString("interface{")
-		empty := true
-		if gcCompatibilityMode {
-			// print flattened interface
-			// (useful to compare against gc-generated interfaces)
-			for i, m := range t.allMethods {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				buf.WriteString(m.name)
-				writeSignature(buf, m.typ.(*Signature), qf, visited)
-				empty = false
-			}
-			if !empty && t.allTypes != nil {
-				buf.WriteString("; ")
-			}
-			if t.allTypes != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.allTypes, qf, visited)
-			}
-		} else {
-			// print explicit interface methods and embedded types
-			for i, m := range t.methods {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				buf.WriteString(m.name)
-				writeSignature(buf, m.typ.(*Signature), qf, visited)
-				empty = false
-			}
-			if !empty && t.types != nil {
+		first := true
+		for _, m := range t.methods {
+			if !first {
 				buf.WriteString("; ")
 			}
-			if t.types != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.types, qf, visited)
-				empty = false
-			}
-			if !empty && len(t.embeddeds) > 0 {
-				buf.WriteString("; ")
-			}
-			for i, typ := range t.embeddeds {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				writeType(buf, typ, qf, visited)
-				empty = false
-			}
+			first = false
+			buf.WriteString(m.name)
+			writeSignature(buf, m.typ.(*Signature), qf, visited)
 		}
-		if t.allMethods == nil || len(t.methods) > len(t.allMethods) {
-			if !empty {
-				buf.WriteByte(' ')
+		for _, typ := range t.embeddeds {
+			if !first {
+				buf.WriteString("; ")
 			}
-			buf.WriteString("/* incomplete */")
+			first = false
+			writeType(buf, typ, qf, visited)
 		}
 		buf.WriteByte('}')
 
@@ -255,7 +183,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		case RecvOnly:
 			s = "<-chan "
 		default:
-			panic("unreachable")
+			unreachable()
 		}
 		buf.WriteString(s)
 		if parens {
@@ -267,39 +195,40 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		}
 
 	case *Named:
+		if t.instance != nil {
+			buf.WriteByte(instanceMarker)
+		}
 		writeTypeName(buf, t.obj, qf)
 		if t.targs != nil {
 			// instantiated type
 			buf.WriteByte('[')
-			writeTypeList(buf, t.targs, qf, visited)
+			writeTypeList(buf, t.targs.list(), qf, visited)
 			buf.WriteByte(']')
-		} else if t.tparams != nil {
+		} else if t.TParams().Len() != 0 {
 			// parameterized type
-			writeTParamList(buf, t.tparams, qf, visited)
+			writeTParamList(buf, t.TParams().list(), qf, visited)
 		}
 
 	case *TypeParam:
 		s := "?"
 		if t.obj != nil {
+			// Optionally write out package for typeparams (like Named).
+			// TODO(danscales): this is required for import/export, so
+			// we maybe need a separate function that won't be changed
+			// for debugging purposes.
+			if t.obj.pkg != nil {
+				writePackage(buf, t.obj.pkg, qf)
+			}
 			s = t.obj.name
 		}
 		buf.WriteString(s + subscript(t.id))
 
-	case *instance:
-		buf.WriteByte(instanceMarker) // indicate "non-evaluated" syntactic instance
-		writeTypeName(buf, t.base.obj, qf)
-		buf.WriteByte('[')
-		writeTypeList(buf, t.targs, qf, visited)
-		buf.WriteByte(']')
-
-	case *bottom:
-		buf.WriteString("⊥")
-
 	case *top:
 		buf.WriteString("⊤")
 
 	default:
 		// For externally defined implementations of Type.
+		// Note: In this case cycles won't be caught.
 		buf.WriteString(t.String())
 	}
 }
@@ -313,29 +242,32 @@ func writeTypeList(buf *bytes.Buffer, list []Type, qf Qualifier, visited []Type)
 	}
 }
 
-func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited []Type) {
+func writeTParamList(buf *bytes.Buffer, list []*TypeParam, qf Qualifier, visited []Type) {
 	buf.WriteString("[")
 	var prev Type
-	for i, p := range list {
-		// TODO(gri) support 'any' sugar here.
-		var b Type = &emptyInterface
-		if t, _ := p.typ.(*TypeParam); t != nil && t.bound != nil {
-			b = t.bound
+	for i, tpar := range list {
+		// Determine the type parameter and its constraint.
+		// list is expected to hold type parameter names,
+		// but don't crash if that's not the case.
+		var bound Type
+		if tpar != nil {
+			bound = tpar.bound // should not be nil but we want to see it if it is
 		}
+
 		if i > 0 {
-			if b != prev {
-				// type bound changed - write previous one before advancing
+			if bound != prev {
+				// bound changed - write previous one before advancing
 				buf.WriteByte(' ')
 				writeType(buf, prev, qf, visited)
 			}
 			buf.WriteString(", ")
 		}
-		prev = b
+		prev = bound
 
-		if t, _ := p.typ.(*TypeParam); t != nil {
-			writeType(buf, t, qf, visited)
+		if tpar != nil {
+			writeType(buf, tpar, qf, visited)
 		} else {
-			buf.WriteString(p.name)
+			buf.WriteString(tpar.obj.name)
 		}
 	}
 	if prev != nil {
@@ -346,17 +278,38 @@ func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited
 }
 
 func writeTypeName(buf *bytes.Buffer, obj *TypeName, qf Qualifier) {
-	s := ""
-	if obj != nil {
-		if obj.pkg != nil {
-			writePackage(buf, obj.pkg, qf)
+	if obj == nil {
+		buf.WriteString("")
+		return
+	}
+	if obj.pkg != nil {
+		writePackage(buf, obj.pkg, qf)
+	}
+	buf.WriteString(obj.name)
+
+	if instanceHashing != 0 {
+		// For local defined types, use the (original!) TypeName's scope
+		// numbers to disambiguate.
+		typ := obj.typ.(*Named)
+		// TODO(gri) Figure out why typ.orig != typ.orig.orig sometimes
+		//           and whether the loop can iterate more than twice.
+		//           (It seems somehow connected to instance types.)
+		for typ.orig != typ {
+			typ = typ.orig
 		}
-		// TODO(gri): function-local named types should be displayed
-		// differently from named types at package level to avoid
-		// ambiguity.
-		s = obj.name
+		writeScopeNumbers(buf, typ.obj.parent)
+	}
+}
+
+// writeScopeNumbers writes the number sequence for this scope to buf
+// in the form ".i.j.k" where i, j, k, etc. stand for scope numbers.
+// If a scope is nil or has no parent (such as a package scope), nothing
+// is written.
+func writeScopeNumbers(buf *bytes.Buffer, s *Scope) {
+	if s != nil && s.number > 0 {
+		writeScopeNumbers(buf, s.parent)
+		fmt.Fprintf(buf, ".%d", s.number)
 	}
-	buf.WriteString(s)
 }
 
 func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
@@ -379,7 +332,7 @@ func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visi
 					// special case:
 					// append(s, "foo"...) leads to signature func([]byte, string...)
 					if t := asBasic(typ); t == nil || t.kind != String {
-						panic("internal error: string type expected")
+						panic("expected string type")
 					}
 					writeType(buf, typ, qf, visited)
 					buf.WriteString("...")
@@ -401,8 +354,8 @@ func WriteSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier) {
 }
 
 func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
-	if sig.tparams != nil {
-		writeTParamList(buf, sig.tparams, qf, visited)
+	if sig.TParams().Len() != 0 {
+		writeTParamList(buf, sig.TParams().list(), qf, visited)
 	}
 
 	writeTuple(buf, sig.params, sig.variadic, qf, visited)
diff --git a/src/cmd/compile/internal/types2/typestring_test.go b/src/cmd/compile/internal/types2/typestring_test.go
index d98e9a5ade6e9bbe0a3c60b03d9dd472425c35a9..0ed29349610912978106e64705ff8207182a6823 100644
--- a/src/cmd/compile/internal/types2/typestring_test.go
+++ b/src/cmd/compile/internal/types2/typestring_test.go
@@ -91,7 +91,8 @@ var independentTestTypes = []testEntry{
 	dup("interface{}"),
 	dup("interface{m()}"),
 	dup(`interface{String() string; m(int) float32}`),
-	dup(`interface{type int, float32, complex128}`),
+	dup("interface{int|float32|complex128}"),
+	dup("interface{int|~float32|~complex128}"),
 
 	// maps
 	dup("map[string]int"),
@@ -135,60 +136,6 @@ func TestTypeString(t *testing.T) {
 	}
 }
 
-var nopos syntax.Pos
-
-func TestIncompleteInterfaces(t *testing.T) {
-	sig := NewSignature(nil, nil, nil, false)
-	m := NewFunc(nopos, nil, "m", sig)
-	for _, test := range []struct {
-		typ  *Interface
-		want string
-	}{
-		{new(Interface), "interface{/* incomplete */}"},
-		{new(Interface).Complete(), "interface{}"},
-
-		{NewInterface(nil, nil), "interface{}"},
-		{NewInterface(nil, nil).Complete(), "interface{}"},
-		{NewInterface([]*Func{}, nil), "interface{}"},
-		{NewInterface([]*Func{}, nil).Complete(), "interface{}"},
-		{NewInterface(nil, []*Named{}), "interface{}"},
-		{NewInterface(nil, []*Named{}).Complete(), "interface{}"},
-		{NewInterface([]*Func{m}, nil), "interface{m() /* incomplete */}"},
-		{NewInterface([]*Func{m}, nil).Complete(), "interface{m()}"},
-		{NewInterface(nil, []*Named{newDefined(new(Interface).Complete())}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(new(Interface).Complete())}).Complete(), "interface{T}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil))}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil).Complete())}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil).Complete())}).Complete(), "interface{T}"},
-
-		{NewInterfaceType(nil, nil), "interface{}"},
-		{NewInterfaceType(nil, nil).Complete(), "interface{}"},
-		{NewInterfaceType([]*Func{}, nil), "interface{}"},
-		{NewInterfaceType([]*Func{}, nil).Complete(), "interface{}"},
-		{NewInterfaceType(nil, []Type{}), "interface{}"},
-		{NewInterfaceType(nil, []Type{}).Complete(), "interface{}"},
-		{NewInterfaceType([]*Func{m}, nil), "interface{m() /* incomplete */}"},
-		{NewInterfaceType([]*Func{m}, nil).Complete(), "interface{m()}"},
-		{NewInterfaceType(nil, []Type{new(Interface).Complete()}), "interface{interface{} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{new(Interface).Complete()}).Complete(), "interface{interface{}}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil)}), "interface{interface{m() /* incomplete */} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil).Complete()}), "interface{interface{m()} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil).Complete()}).Complete(), "interface{interface{m()}}"},
-	} {
-		got := test.typ.String()
-		if got != test.want {
-			t.Errorf("got: %s, want: %s", got, test.want)
-		}
-	}
-}
-
-// newDefined creates a new defined type named T with the given underlying type.
-// Helper function for use with TestIncompleteInterfaces only.
-func newDefined(underlying Type) *Named {
-	tname := NewTypeName(nopos, nil, "T", nil)
-	return NewNamed(tname, underlying, nil)
-}
-
 func TestQualifiedTypeString(t *testing.T) {
 	p, _ := pkgFor("p.go", "package p; type T int", nil)
 	q, _ := pkgFor("q.go", "package q", nil)
diff --git a/src/cmd/compile/internal/types2/typeterm.go b/src/cmd/compile/internal/types2/typeterm.go
new file mode 100644
index 0000000000000000000000000000000000000000..1d7223f13c42c013e06c8d8f1fb9cf4b423a7fb2
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeterm.go
@@ -0,0 +1,166 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A term describes elementary type sets:
+//
+//   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
+//   𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
+//   T:  &term{false, T}  == {T}                    // set of type T
+//  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
+//
+type term struct {
+	tilde bool // valid if typ != nil
+	typ   Type
+}
+
+func (x *term) String() string {
+	switch {
+	case x == nil:
+		return "∅"
+	case x.typ == nil:
+		return "𝓤"
+	case x.tilde:
+		return "~" + x.typ.String()
+	default:
+		return x.typ.String()
+	}
+}
+
+// equal reports whether x and y represent the same type set.
+func (x *term) equal(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return x == y
+	case x.typ == nil || y.typ == nil:
+		return x.typ == y.typ
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	return x.tilde == y.tilde && Identical(x.typ, y.typ)
+}
+
+// union returns the union x ∪ y: zero, one, or two non-nil terms.
+func (x *term) union(y *term) (_, _ *term) {
+	// easy cases
+	switch {
+	case x == nil && y == nil:
+		return nil, nil // ∅ ∪ ∅ == ∅
+	case x == nil:
+		return y, nil // ∅ ∪ y == y
+	case y == nil:
+		return x, nil // x ∪ ∅ == x
+	case x.typ == nil:
+		return x, nil // 𝓤 ∪ y == 𝓤
+	case y.typ == nil:
+		return y, nil // x ∪ 𝓤 == 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∪ ~t == ~t
+	// ~t ∪  T == ~t
+	//  T ∪ ~t == ~t
+	//  T ∪  T ==  T
+	if x.tilde || !y.tilde {
+		return x, nil
+	}
+	return y, nil
+}
+
+// intersect returns the intersection x ∩ y.
+func (x *term) intersect(y *term) *term {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
+	case x.typ == nil:
+		return y // 𝓤 ∩ y == y
+	case y.typ == nil:
+		return x // x ∩ 𝓤 == x
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return nil // x ∩ y == ∅ if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∩ ~t == ~t
+	// ~t ∩  T ==  T
+	//  T ∩ ~t ==  T
+	//  T ∩  T ==  T
+	if !x.tilde || y.tilde {
+		return x
+	}
+	return y
+}
+
+// includes reports whether t ∈ x.
+func (x *term) includes(t Type) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return false // t ∈ ∅ == false
+	case x.typ == nil:
+		return true // t ∈ 𝓤 == true
+	}
+	// ∅ ⊂ x ⊂ 𝓤
+
+	u := t
+	if x.tilde {
+		u = under(u)
+	}
+	return Identical(x.typ, u)
+}
+
+// subsetOf reports whether x ⊆ y.
+func (x *term) subsetOf(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return true // ∅ ⊆ y == true
+	case y == nil:
+		return false // x ⊆ ∅ == false since x != ∅
+	case y.typ == nil:
+		return true // x ⊆ 𝓤 == true
+	case x.typ == nil:
+		return false // 𝓤 ⊆ y == false since y != 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return false // x ⊆ y == false if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ⊆ ~t == true
+	// ~t ⊆ T == false
+	//  T ⊆ ~t == true
+	//  T ⊆  T == true
+	return !x.tilde || y.tilde
+}
+
+// disjoint reports whether x ∩ y == ∅.
+// x.typ and y.typ must not be nil.
+func (x *term) disjoint(y *term) bool {
+	if debug && (x.typ == nil || y.typ == nil) {
+		panic("invalid argument(s)")
+	}
+	ux := x.typ
+	if y.tilde {
+		ux = under(ux)
+	}
+	uy := y.typ
+	if x.tilde {
+		uy = under(uy)
+	}
+	return !Identical(ux, uy)
+}
diff --git a/src/cmd/compile/internal/types2/typeterm_test.go b/src/cmd/compile/internal/types2/typeterm_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..5a5c1fa4477d9e0da4a5a4d72a4505bce65856e1
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeterm_test.go
@@ -0,0 +1,239 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"strings"
+	"testing"
+)
+
+var myInt = func() Type {
+	tname := NewTypeName(nopos, nil, "myInt", nil)
+	return NewNamed(tname, Typ[Int], nil)
+}()
+
+var testTerms = map[string]*term{
+	"∅":       nil,
+	"𝓤":       {},
+	"int":     {false, Typ[Int]},
+	"~int":    {true, Typ[Int]},
+	"string":  {false, Typ[String]},
+	"~string": {true, Typ[String]},
+	"myInt":   {false, myInt},
+}
+
+func TestTermString(t *testing.T) {
+	for want, x := range testTerms {
+		if got := x.String(); got != want {
+			t.Errorf("%v.String() == %v; want %v", x, got, want)
+		}
+	}
+}
+
+func split(s string, n int) []string {
+	r := strings.Split(s, " ")
+	if len(r) != n {
+		panic("invalid test case: " + s)
+	}
+	return r
+}
+
+func testTerm(name string) *term {
+	r, ok := testTerms[name]
+	if !ok {
+		panic("invalid test argument: " + name)
+	}
+	return r
+}
+
+func TestTermEqual(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"𝓤 𝓤 T",
+		"int int T",
+		"~int ~int T",
+		"myInt myInt T",
+		"∅ 𝓤 F",
+		"∅ int F",
+		"∅ ~int F",
+		"𝓤 int F",
+		"𝓤 ~int F",
+		"𝓤 myInt F",
+		"int ~int F",
+		"int myInt F",
+		"~int myInt F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+		// equal is symmetric
+		x, y = y, x
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermUnion(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅ ∅",
+		"∅ 𝓤 𝓤 ∅",
+		"∅ int int ∅",
+		"∅ ~int ~int ∅",
+		"∅ myInt myInt ∅",
+		"𝓤 𝓤 𝓤 ∅",
+		"𝓤 int 𝓤 ∅",
+		"𝓤 ~int 𝓤 ∅",
+		"𝓤 myInt 𝓤 ∅",
+		"int int int ∅",
+		"int ~int ~int ∅",
+		"int string int string",
+		"int ~string int ~string",
+		"int myInt int myInt",
+		"~int ~string ~int ~string",
+		"~int myInt ~int ∅",
+
+		// union is symmetric, but the result order isn't - repeat symmetric cases explictly
+		"𝓤 ∅ 𝓤 ∅",
+		"int ∅ int ∅",
+		"~int ∅ ~int ∅",
+		"myInt ∅ myInt ∅",
+		"int 𝓤 𝓤 ∅",
+		"~int 𝓤 𝓤 ∅",
+		"myInt 𝓤 𝓤 ∅",
+		"~int int ~int ∅",
+		"string int string int",
+		"~string int ~string int",
+		"myInt int myInt int",
+		"~string ~int ~string ~int",
+		"myInt ~int ~int ∅",
+	} {
+		args := split(test, 4)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want1 := testTerm(args[2])
+		want2 := testTerm(args[3])
+		if got1, got2 := x.union(y); !got1.equal(want1) || !got2.equal(want2) {
+			t.Errorf("%v.union(%v) = %v, %v; want %v, %v", x, y, got1, got2, want1, want2)
+		}
+	}
+}
+
+func TestTermIntersection(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅",
+		"∅ 𝓤 ∅",
+		"∅ int ∅",
+		"∅ ~int ∅",
+		"∅ myInt ∅",
+		"𝓤 𝓤 𝓤",
+		"𝓤 int int",
+		"𝓤 ~int ~int",
+		"𝓤 myInt myInt",
+		"int int int",
+		"int ~int int",
+		"int string ∅",
+		"int ~string ∅",
+		"int string ∅",
+		"~int ~string ∅",
+		"~int myInt myInt",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := testTerm(args[2])
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+		// intersect is symmetric
+		x, y = y, x
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermIncludes(t *testing.T) {
+	for _, test := range []string{
+		"∅ int F",
+		"𝓤 int T",
+		"int int T",
+		"~int int T",
+		"~int myInt T",
+		"string int F",
+		"~string int F",
+		"myInt int F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1]).typ
+		want := args[2] == "T"
+		if got := x.includes(y); got != want {
+			t.Errorf("%v.includes(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermSubsetOf(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"𝓤 𝓤 T",
+		"int int T",
+		"~int ~int T",
+		"myInt myInt T",
+		"∅ 𝓤 T",
+		"∅ int T",
+		"∅ ~int T",
+		"∅ myInt T",
+		"𝓤 int F",
+		"𝓤 ~int F",
+		"𝓤 myInt F",
+		"int ~int T",
+		"int myInt F",
+		"~int myInt F",
+		"myInt int F",
+		"myInt ~int T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.subsetOf(y); got != want {
+			t.Errorf("%v.subsetOf(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermDisjoint(t *testing.T) {
+	for _, test := range []string{
+		"int int F",
+		"~int ~int F",
+		"int ~int F",
+		"int string T",
+		"int ~string T",
+		"int myInt T",
+		"~int ~string T",
+		"~int myInt F",
+		"string myInt T",
+		"~string myInt T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+		// disjoint is symmetric
+		x, y = y, x
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/types2/typexpr.go b/src/cmd/compile/internal/types2/typexpr.go
index e64d804c30b8ccc59a9c5532d714a624109c0cca..241c6d35fe4e91fe7b43dc9525cbcd6b43370d05 100644
--- a/src/cmd/compile/internal/types2/typexpr.go
+++ b/src/cmd/compile/internal/types2/typexpr.go
@@ -10,14 +10,9 @@ import (
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"go/constant"
-	"sort"
-	"strconv"
 	"strings"
 )
 
-// Disabled by default, but enabled when running tests (via types_test.go).
-var acceptMethodTypeParams bool
-
 // ident type-checks identifier e and initializes x with the value or type of e.
 // If an error occurred, x.mode is set to invalid.
 // For the meaning of def, see Checker.definedType, below.
@@ -30,7 +25,8 @@ func (check *Checker) ident(x *operand, e *syntax.Name, def *Named, wantType boo
 	// Note that we cannot use check.lookup here because the returned scope
 	// may be different from obj.Parent(). See also Scope.LookupParent doc.
 	scope, obj := check.scope.LookupParent(e.Value, check.pos)
-	if obj == nil {
+	switch obj {
+	case nil:
 		if e.Value == "_" {
 			check.error(e, "cannot use _ as value or type")
 		} else {
@@ -41,6 +37,16 @@ func (check *Checker) ident(x *operand, e *syntax.Name, def *Named, wantType boo
 			}
 		}
 		return
+	case universeAny, universeComparable:
+		if !check.allowVersion(check.pkg, 1, 18) {
+			check.errorf(e, "undeclared name: %s (requires version go1.18 or later)", e.Value)
+			return
+		}
+		// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+		if obj == universeAny {
+			check.error(e, "cannot use any outside constraint position")
+			return
+		}
 	}
 	check.recordUse(e, obj)
 
@@ -63,7 +69,7 @@ func (check *Checker) ident(x *operand, e *syntax.Name, def *Named, wantType boo
 	// If so, mark the respective package as used.
 	// (This code is only needed for dot-imports. Without them,
 	// we only have to mark variables, see *Var case below).
-	if pkgName := check.dotImportMap[dotImportKey{scope, obj}]; pkgName != nil {
+	if pkgName := check.dotImportMap[dotImportKey{scope, obj.Name()}]; pkgName != nil {
 		pkgName.used = true
 	}
 
@@ -141,18 +147,18 @@ func (check *Checker) varType(e syntax.Expr) Type {
 // ordinaryType reports an error if typ is an interface type containing
 // type lists or is (or embeds) the predeclared type comparable.
 func (check *Checker) ordinaryType(pos syntax.Pos, typ Type) {
-	// We don't want to call under() (via Interface) or complete interfaces while we
+	// We don't want to call under() (via asInterface) or complete interfaces while we
 	// are in the middle of type-checking parameter declarations that might belong to
 	// interface methods. Delay this check to the end of type-checking.
 	check.later(func() {
 		if t := asInterface(typ); t != nil {
-			check.completeInterface(pos, t) // TODO(gri) is this the correct position?
-			if t.allTypes != nil {
-				check.softErrorf(pos, "interface contains type constraints (%s)", t.allTypes)
-				return
-			}
-			if t.IsComparable() {
-				check.softErrorf(pos, "interface is (or embeds) comparable")
+			tset := computeInterfaceTypeSet(check, pos, t) // TODO(gri) is this the correct position?
+			if !tset.IsMethodSet() {
+				if tset.comparable {
+					check.softErrorf(pos, "interface is (or embeds) comparable")
+				} else {
+					check.softErrorf(pos, "interface contains type constraints")
+				}
 			}
 		}
 	})
@@ -198,238 +204,6 @@ func (check *Checker) genericType(e syntax.Expr, reportErr bool) Type {
 	return typ
 }
 
-// isubst returns an x with identifiers substituted per the substitution map smap.
-// isubst only handles the case of (valid) method receiver type expressions correctly.
-func isubst(x syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr {
-	switch n := x.(type) {
-	case *syntax.Name:
-		if alt := smap[n]; alt != nil {
-			return alt
-		}
-	// case *syntax.StarExpr:
-	// 	X := isubst(n.X, smap)
-	// 	if X != n.X {
-	// 		new := *n
-	// 		new.X = X
-	// 		return &new
-	// 	}
-	case *syntax.Operation:
-		if n.Op == syntax.Mul && n.Y == nil {
-			X := isubst(n.X, smap)
-			if X != n.X {
-				new := *n
-				new.X = X
-				return &new
-			}
-		}
-	case *syntax.IndexExpr:
-		Index := isubst(n.Index, smap)
-		if Index != n.Index {
-			new := *n
-			new.Index = Index
-			return &new
-		}
-	case *syntax.ListExpr:
-		var elems []syntax.Expr
-		for i, elem := range n.ElemList {
-			new := isubst(elem, smap)
-			if new != elem {
-				if elems == nil {
-					elems = make([]syntax.Expr, len(n.ElemList))
-					copy(elems, n.ElemList)
-				}
-				elems[i] = new
-			}
-		}
-		if elems != nil {
-			new := *n
-			new.ElemList = elems
-			return &new
-		}
-	case *syntax.ParenExpr:
-		return isubst(n.X, smap) // no need to keep parentheses
-	default:
-		// Other receiver type expressions are invalid.
-		// It's fine to ignore those here as they will
-		// be checked elsewhere.
-	}
-	return x
-}
-
-// funcType type-checks a function or method type.
-func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) {
-	check.openScope(ftyp, "function")
-	check.scope.isFunc = true
-	check.recordScope(ftyp, check.scope)
-	sig.scope = check.scope
-	defer check.closeScope()
-
-	var recvTyp syntax.Expr // rewritten receiver type; valid if != nil
-	if recvPar != nil {
-		// collect generic receiver type parameters, if any
-		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
-		// - the receiver specification acts as local declaration for its type parameters, which may be blank
-		_, rname, rparams := check.unpackRecv(recvPar.Type, true)
-		if len(rparams) > 0 {
-			// Blank identifiers don't get declared and regular type-checking of the instantiated
-			// parameterized receiver type expression fails in Checker.collectParams of receiver.
-			// Identify blank type parameters and substitute each with a unique new identifier named
-			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
-			// name.
-			var smap map[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers
-			for i, p := range rparams {
-				if p.Value == "_" {
-					new := *p
-					new.Value = fmt.Sprintf("%d_", i)
-					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
-					if smap == nil {
-						smap = make(map[*syntax.Name]*syntax.Name)
-					}
-					smap[p] = &new
-				}
-			}
-			if smap != nil {
-				// blank identifiers were found => use rewritten receiver type
-				recvTyp = isubst(recvPar.Type, smap)
-			}
-			// TODO(gri) rework declareTypeParams
-			sig.rparams = nil
-			for _, rparam := range rparams {
-				sig.rparams = check.declareTypeParam(sig.rparams, rparam)
-			}
-			// determine receiver type to get its type parameters
-			// and the respective type parameter bounds
-			var recvTParams []*TypeName
-			if rname != nil {
-				// recv should be a Named type (otherwise an error is reported elsewhere)
-				// Also: Don't report an error via genericType since it will be reported
-				//       again when we type-check the signature.
-				// TODO(gri) maybe the receiver should be marked as invalid instead?
-				if recv := asNamed(check.genericType(rname, false)); recv != nil {
-					recvTParams = recv.tparams
-				}
-			}
-			// provide type parameter bounds
-			// - only do this if we have the right number (otherwise an error is reported elsewhere)
-			if len(sig.rparams) == len(recvTParams) {
-				// We have a list of *TypeNames but we need a list of Types.
-				list := make([]Type, len(sig.rparams))
-				for i, t := range sig.rparams {
-					list[i] = t.typ
-				}
-				smap := makeSubstMap(recvTParams, list)
-				for i, tname := range sig.rparams {
-					bound := recvTParams[i].typ.(*TypeParam).bound
-					// bound is (possibly) parameterized in the context of the
-					// receiver type declaration. Substitute parameters for the
-					// current context.
-					// TODO(gri) should we assume now that bounds always exist?
-					//           (no bound == empty interface)
-					if bound != nil {
-						bound = check.subst(tname.pos, bound, smap)
-						tname.typ.(*TypeParam).bound = bound
-					}
-				}
-			}
-		}
-	}
-
-	if tparams != nil {
-		sig.tparams = check.collectTypeParams(tparams)
-		// Always type-check method type parameters but complain if they are not enabled.
-		// (A separate check is needed when type-checking interface method signatures because
-		// they don't have a receiver specification.)
-		if recvPar != nil && !acceptMethodTypeParams {
-			check.error(ftyp, "methods cannot have type parameters")
-		}
-	}
-
-	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
-	// declarations and then squash that scope into the parent scope (and report any redeclarations at
-	// that time).
-	scope := NewScope(check.scope, nopos, nopos, "function body (temp. scope)")
-	var recvList []*Var // TODO(gri) remove the need for making a list here
-	if recvPar != nil {
-		recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any
-	}
-	params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true)
-	results, _ := check.collectParams(scope, ftyp.ResultList, nil, false)
-	scope.Squash(func(obj, alt Object) {
-		var err error_
-		err.errorf(obj, "%s redeclared in this block", obj.Name())
-		err.recordAltDecl(alt)
-		check.report(&err)
-	})
-
-	if recvPar != nil {
-		// recv parameter list present (may be empty)
-		// spec: "The receiver is specified via an extra parameter section preceding the
-		// method name. That parameter section must declare a single parameter, the receiver."
-		var recv *Var
-		switch len(recvList) {
-		case 0:
-			// error reported by resolver
-			recv = NewParam(nopos, nil, "", Typ[Invalid]) // ignore recv below
-		default:
-			// more than one receiver
-			check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver")
-			fallthrough // continue with first receiver
-		case 1:
-			recv = recvList[0]
-		}
-
-		// TODO(gri) We should delay rtyp expansion to when we actually need the
-		//           receiver; thus all checks here should be delayed to later.
-		rtyp, _ := deref(recv.typ)
-		rtyp = expand(rtyp)
-
-		// spec: "The receiver type must be of the form T or *T where T is a type name."
-		// (ignore invalid types - error was reported before)
-		if t := rtyp; t != Typ[Invalid] {
-			var err string
-			if T := asNamed(t); T != nil {
-				// spec: "The type denoted by T is called the receiver base type; it must not
-				// be a pointer or interface type and it must be declared in the same package
-				// as the method."
-				if T.obj.pkg != check.pkg {
-					err = "type not defined in this package"
-					if check.conf.CompilerErrorMessages {
-						check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
-						err = ""
-					}
-				} else {
-					switch u := optype(T).(type) {
-					case *Basic:
-						// unsafe.Pointer is treated like a regular pointer
-						if u.kind == UnsafePointer {
-							err = "unsafe.Pointer"
-						}
-					case *Pointer, *Interface:
-						err = "pointer or interface type"
-					}
-				}
-			} else if T := asBasic(t); T != nil {
-				err = "basic or unnamed type"
-				if check.conf.CompilerErrorMessages {
-					check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
-					err = ""
-				}
-			} else {
-				check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
-			}
-			if err != "" {
-				check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err)
-				// ok to continue
-			}
-		}
-		sig.recv = recv
-	}
-
-	sig.params = NewTuple(params...)
-	sig.results = NewTuple(results...)
-	sig.variadic = variadic
-}
-
 // goTypeName returns the Go type name for typ and
 // removes any occurrences of "types2." from that name.
 func goTypeName(typ Type) string {
@@ -451,7 +225,7 @@ func (check *Checker) typInternal(e0 syntax.Expr, def *Named) (T Type) {
 				// Test case: type T[P any] *T[P]
 				// TODO(gri) investigate if that's a bug or to be expected
 				// (see also analogous comment in Checker.instantiate).
-				under = T.Underlying()
+				under = safeUnderlying(T)
 			}
 			if T == under {
 				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
@@ -647,44 +421,36 @@ func (check *Checker) typOrNil(e syntax.Expr) Type {
 	return Typ[Invalid]
 }
 
-func (check *Checker) instantiatedType(x syntax.Expr, targs []syntax.Expr, def *Named) Type {
-	b := check.genericType(x, true) // TODO(gri) what about cycles?
-	if b == Typ[Invalid] {
-		return b // error already reported
+func (check *Checker) instantiatedType(x syntax.Expr, targsx []syntax.Expr, def *Named) Type {
+	gtyp := check.genericType(x, true)
+	if gtyp == Typ[Invalid] {
+		return gtyp // error already reported
 	}
-	base := asNamed(b)
+	base, _ := gtyp.(*Named)
 	if base == nil {
-		unreachable() // should have been caught by genericType
+		panic(fmt.Sprintf("%v: cannot instantiate %v", x.Pos(), gtyp))
 	}
 
-	// create a new type instance rather than instantiate the type
-	// TODO(gri) should do argument number check here rather than
-	//           when instantiating the type?
-	typ := new(instance)
-	def.setUnderlying(typ)
-
-	typ.check = check
-	typ.pos = x.Pos()
-	typ.base = base
-
-	// evaluate arguments (always)
-	typ.targs = check.typeList(targs)
-	if typ.targs == nil {
+	// evaluate arguments
+	targs := check.typeList(targsx)
+	if targs == nil {
 		def.setUnderlying(Typ[Invalid]) // avoid later errors due to lazy instantiation
 		return Typ[Invalid]
 	}
 
-	// determine argument positions (for error reporting)
-	typ.poslist = make([]syntax.Pos, len(targs))
-	for i, arg := range targs {
-		typ.poslist[i] = syntax.StartPos(arg)
+	// determine argument positions
+	posList := make([]syntax.Pos, len(targs))
+	for i, arg := range targsx {
+		posList[i] = syntax.StartPos(arg)
 	}
 
+	typ := check.instantiate(x.Pos(), base, targs, posList)
+	def.setUnderlying(typ)
+
 	// make sure we check instantiation works at least once
 	// and that the resulting type is valid
 	check.later(func() {
-		t := typ.expand()
-		check.validType(t, nil)
+		check.validType(typ, nil)
 	})
 
 	return typ
@@ -732,537 +498,3 @@ func (check *Checker) typeList(list []syntax.Expr) []Type {
 	}
 	return res
 }
-
-// collectParams declares the parameters of list in scope and returns the corresponding
-// variable list. If type0 != nil, it is used instead of the first type in list.
-func (check *Checker) collectParams(scope *Scope, list []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) {
-	if list == nil {
-		return
-	}
-
-	var named, anonymous bool
-
-	var typ Type
-	var prev syntax.Expr
-	for i, field := range list {
-		ftype := field.Type
-		// type-check type of grouped fields only once
-		if ftype != prev {
-			prev = ftype
-			if i == 0 && type0 != nil {
-				ftype = type0
-			}
-			if t, _ := ftype.(*syntax.DotsType); t != nil {
-				ftype = t.Elem
-				if variadicOk && i == len(list)-1 {
-					variadic = true
-				} else {
-					check.softErrorf(t, "can only use ... with final parameter in list")
-					// ignore ... and continue
-				}
-			}
-			typ = check.varType(ftype)
-		}
-		// The parser ensures that f.Tag is nil and we don't
-		// care if a constructed AST contains a non-nil tag.
-		if field.Name != nil {
-			// named parameter
-			name := field.Name.Value
-			if name == "" {
-				check.error(field.Name, invalidAST+"anonymous parameter")
-				// ok to continue
-			}
-			par := NewParam(field.Name.Pos(), check.pkg, name, typ)
-			check.declare(scope, field.Name, par, scope.pos)
-			params = append(params, par)
-			named = true
-		} else {
-			// anonymous parameter
-			par := NewParam(ftype.Pos(), check.pkg, "", typ)
-			check.recordImplicit(field, par)
-			params = append(params, par)
-			anonymous = true
-		}
-	}
-
-	if named && anonymous {
-		check.error(list[0], invalidAST+"list contains both named and anonymous parameters")
-		// ok to continue
-	}
-
-	// For a variadic function, change the last parameter's type from T to []T.
-	// Since we type-checked T rather than ...T, we also need to retro-actively
-	// record the type for ...T.
-	if variadic {
-		last := params[len(params)-1]
-		last.typ = &Slice{elem: last.typ}
-		check.recordTypeAndValue(list[len(list)-1].Type, typexpr, last.typ, nil)
-	}
-
-	return
-}
-
-func (check *Checker) declareInSet(oset *objset, pos syntax.Pos, obj Object) bool {
-	if alt := oset.insert(obj); alt != nil {
-		var err error_
-		err.errorf(pos, "%s redeclared", obj.Name())
-		err.recordAltDecl(alt)
-		check.report(&err)
-		return false
-	}
-	return true
-}
-
-func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType, def *Named) {
-	var tname *syntax.Name // most recent "type" name
-	var types []syntax.Expr
-	for _, f := range iface.MethodList {
-		if f.Name != nil {
-			// We have a method with name f.Name, or a type
-			// of a type list (f.Name.Value == "type").
-			name := f.Name.Value
-			if name == "_" {
-				if check.conf.CompilerErrorMessages {
-					check.error(f.Name, "methods must have a unique non-blank name")
-				} else {
-					check.error(f.Name, "invalid method name _")
-				}
-				continue // ignore
-			}
-
-			if name == "type" {
-				// Always collect all type list entries, even from
-				// different type lists, under the assumption that
-				// the author intended to include all types.
-				types = append(types, f.Type)
-				if tname != nil && tname != f.Name {
-					check.error(f.Name, "cannot have multiple type lists in an interface")
-				}
-				tname = f.Name
-				continue
-			}
-
-			typ := check.typ(f.Type)
-			sig, _ := typ.(*Signature)
-			if sig == nil {
-				if typ != Typ[Invalid] {
-					check.errorf(f.Type, invalidAST+"%s is not a method signature", typ)
-				}
-				continue // ignore
-			}
-
-			// Always type-check method type parameters but complain if they are not enabled.
-			// (This extra check is needed here because interface method signatures don't have
-			// a receiver specification.)
-			if sig.tparams != nil && !acceptMethodTypeParams {
-				check.error(f.Type, "methods cannot have type parameters")
-			}
-
-			// use named receiver type if available (for better error messages)
-			var recvTyp Type = ityp
-			if def != nil {
-				recvTyp = def
-			}
-			sig.recv = NewVar(f.Name.Pos(), check.pkg, "", recvTyp)
-
-			m := NewFunc(f.Name.Pos(), check.pkg, name, sig)
-			check.recordDef(f.Name, m)
-			ityp.methods = append(ityp.methods, m)
-		} else {
-			// We have an embedded type. completeInterface will
-			// eventually verify that we have an interface.
-			ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
-			check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
-		}
-	}
-
-	// type constraints
-	ityp.types = NewSum(check.collectTypeConstraints(iface.Pos(), types))
-
-	if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
-		// empty interface
-		ityp.allMethods = markComplete
-		return
-	}
-
-	// sort for API stability
-	sortMethods(ityp.methods)
-	sortTypes(ityp.embeddeds)
-
-	check.later(func() { check.completeInterface(iface.Pos(), ityp) })
-}
-
-func (check *Checker) completeInterface(pos syntax.Pos, ityp *Interface) {
-	if ityp.allMethods != nil {
-		return
-	}
-
-	// completeInterface may be called via the LookupFieldOrMethod,
-	// MissingMethod, Identical, or IdenticalIgnoreTags external API
-	// in which case check will be nil. In this case, type-checking
-	// must be finished and all interfaces should have been completed.
-	if check == nil {
-		panic("internal error: incomplete interface")
-	}
-
-	if check.conf.Trace {
-		// Types don't generally have position information.
-		// If we don't have a valid pos provided, try to use
-		// one close enough.
-		if !pos.IsKnown() && len(ityp.methods) > 0 {
-			pos = ityp.methods[0].pos
-		}
-
-		check.trace(pos, "complete %s", ityp)
-		check.indent++
-		defer func() {
-			check.indent--
-			check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
-		}()
-	}
-
-	// An infinitely expanding interface (due to a cycle) is detected
-	// elsewhere (Checker.validType), so here we simply assume we only
-	// have valid interfaces. Mark the interface as complete to avoid
-	// infinite recursion if the validType check occurs later for some
-	// reason.
-	ityp.allMethods = markComplete
-
-	// Methods of embedded interfaces are collected unchanged; i.e., the identity
-	// of a method I.m's Func Object of an interface I is the same as that of
-	// the method m in an interface that embeds interface I. On the other hand,
-	// if a method is embedded via multiple overlapping embedded interfaces, we
-	// don't provide a guarantee which "original m" got chosen for the embedding
-	// interface. See also issue #34421.
-	//
-	// If we don't care to provide this identity guarantee anymore, instead of
-	// reusing the original method in embeddings, we can clone the method's Func
-	// Object and give it the position of a corresponding embedded interface. Then
-	// we can get rid of the mpos map below and simply use the cloned method's
-	// position.
-
-	var seen objset
-	var methods []*Func
-	mpos := make(map[*Func]syntax.Pos) // method specification or method embedding position, for good error messages
-	addMethod := func(pos syntax.Pos, m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-			mpos[m] = pos
-		case explicit:
-			var err error_
-			err.errorf(pos, "duplicate method %s", m.name)
-			err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
-			check.report(&err)
-		default:
-			// We have a duplicate method name in an embedded (not explicitly declared) method.
-			// Check method signatures after all types are computed (issue #33656).
-			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
-			// error here as well (even though we could do it eagerly) because it's the same
-			// error message.
-			check.later(func() {
-				if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
-					var err error_
-					err.errorf(pos, "duplicate method %s", m.name)
-					err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
-					check.report(&err)
-				}
-			})
-		}
-	}
-
-	for _, m := range ityp.methods {
-		addMethod(m.pos, m, true)
-	}
-
-	// collect types
-	allTypes := ityp.types
-
-	posList := check.posMap[ityp]
-	for i, typ := range ityp.embeddeds {
-		pos := posList[i] // embedding position
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				var format string
-				if _, ok := utyp.(*TypeParam); ok {
-					format = "%s is a type parameter, not an interface"
-				} else {
-					format = "%s is not an interface"
-				}
-				check.errorf(pos, format, typ)
-			}
-			continue
-		}
-		check.completeInterface(pos, etyp)
-		for _, m := range etyp.allMethods {
-			addMethod(pos, m, false) // use embedding position pos rather than m.pos
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
-
-	if methods != nil {
-		sortMethods(methods)
-		ityp.allMethods = methods
-	}
-	ityp.allTypes = allTypes
-}
-
-// intersect computes the intersection of the types x and y.
-// Note: A incomming nil type stands for the top type. A top
-// type result is returned as nil.
-func intersect(x, y Type) (r Type) {
-	defer func() {
-		if r == theTop {
-			r = nil
-		}
-	}()
-
-	switch {
-	case x == theBottom || y == theBottom:
-		return theBottom
-	case x == nil || x == theTop:
-		return y
-	case y == nil || x == theTop:
-		return x
-	}
-
-	xtypes := unpack(x)
-	ytypes := unpack(y)
-	// Compute the list rtypes which includes only
-	// types that are in both xtypes and ytypes.
-	// Quadratic algorithm, but good enough for now.
-	// TODO(gri) fix this
-	var rtypes []Type
-	for _, x := range xtypes {
-		if includes(ytypes, x) {
-			rtypes = append(rtypes, x)
-		}
-	}
-
-	if rtypes == nil {
-		return theBottom
-	}
-	return NewSum(rtypes)
-}
-
-func sortTypes(list []Type) {
-	sort.Stable(byUniqueTypeName(list))
-}
-
-// byUniqueTypeName named type lists can be sorted by their unique type names.
-type byUniqueTypeName []Type
-
-func (a byUniqueTypeName) Len() int           { return len(a) }
-func (a byUniqueTypeName) Less(i, j int) bool { return sortName(a[i]) < sortName(a[j]) }
-func (a byUniqueTypeName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func sortName(t Type) string {
-	if named := asNamed(t); named != nil {
-		return named.obj.Id()
-	}
-	return ""
-}
-
-func sortMethods(list []*Func) {
-	sort.Sort(byUniqueMethodName(list))
-}
-
-func assertSortedMethods(list []*Func) {
-	if !debug {
-		panic("internal error: assertSortedMethods called outside debug mode")
-	}
-	if !sort.IsSorted(byUniqueMethodName(list)) {
-		panic("internal error: methods not sorted")
-	}
-}
-
-// byUniqueMethodName method lists can be sorted by their unique method names.
-type byUniqueMethodName []*Func
-
-func (a byUniqueMethodName) Len() int           { return len(a) }
-func (a byUniqueMethodName) Less(i, j int) bool { return a[i].less(a[j]) }
-func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func (check *Checker) tag(t *syntax.BasicLit) string {
-	// If t.Bad, an error was reported during parsing.
-	if t != nil && !t.Bad {
-		if t.Kind == syntax.StringLit {
-			if val, err := strconv.Unquote(t.Value); err == nil {
-				return val
-			}
-		}
-		check.errorf(t, invalidAST+"incorrect tag syntax: %q", t.Value)
-	}
-	return ""
-}
-
-func (check *Checker) structType(styp *Struct, e *syntax.StructType) {
-	if e.FieldList == nil {
-		return
-	}
-
-	// struct fields and tags
-	var fields []*Var
-	var tags []string
-
-	// for double-declaration checks
-	var fset objset
-
-	// current field typ and tag
-	var typ Type
-	var tag string
-	add := func(ident *syntax.Name, embedded bool, pos syntax.Pos) {
-		if tag != "" && tags == nil {
-			tags = make([]string, len(fields))
-		}
-		if tags != nil {
-			tags = append(tags, tag)
-		}
-
-		name := ident.Value
-		fld := NewField(pos, check.pkg, name, typ, embedded)
-		// spec: "Within a struct, non-blank field names must be unique."
-		if name == "_" || check.declareInSet(&fset, pos, fld) {
-			fields = append(fields, fld)
-			check.recordDef(ident, fld)
-		}
-	}
-
-	// addInvalid adds an embedded field of invalid type to the struct for
-	// fields with errors; this keeps the number of struct fields in sync
-	// with the source as long as the fields are _ or have different names
-	// (issue #25627).
-	addInvalid := func(ident *syntax.Name, pos syntax.Pos) {
-		typ = Typ[Invalid]
-		tag = ""
-		add(ident, true, pos)
-	}
-
-	var prev syntax.Expr
-	for i, f := range e.FieldList {
-		// Fields declared syntactically with the same type (e.g.: a, b, c T)
-		// share the same type expression. Only check type if it's a new type.
-		if i == 0 || f.Type != prev {
-			typ = check.varType(f.Type)
-			prev = f.Type
-		}
-		tag = ""
-		if i < len(e.TagList) {
-			tag = check.tag(e.TagList[i])
-		}
-		if f.Name != nil {
-			// named field
-			add(f.Name, false, f.Name.Pos())
-		} else {
-			// embedded field
-			// spec: "An embedded type must be specified as a type name T or as a
-			// pointer to a non-interface type name *T, and T itself may not be a
-			// pointer type."
-			pos := syntax.StartPos(f.Type)
-			name := embeddedFieldIdent(f.Type)
-			if name == nil {
-				check.errorf(pos, "invalid embedded field type %s", f.Type)
-				name = &syntax.Name{Value: "_"} // TODO(gri) need to set position to pos
-				addInvalid(name, pos)
-				continue
-			}
-			add(name, true, pos)
-
-			// Because we have a name, typ must be of the form T or *T, where T is the name
-			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
-			// We must delay this check to the end because we don't want to instantiate
-			// (via under(t)) a possibly incomplete type.
-			embeddedTyp := typ // for closure below
-			embeddedPos := pos
-			check.later(func() {
-				t, isPtr := deref(embeddedTyp)
-				switch t := optype(t).(type) {
-				case *Basic:
-					if t == Typ[Invalid] {
-						// error was reported before
-						return
-					}
-					// unsafe.Pointer is treated like a regular pointer
-					if t.kind == UnsafePointer {
-						check.error(embeddedPos, "embedded field type cannot be unsafe.Pointer")
-					}
-				case *Pointer:
-					check.error(embeddedPos, "embedded field type cannot be a pointer")
-				case *Interface:
-					if isPtr {
-						check.error(embeddedPos, "embedded field type cannot be a pointer to an interface")
-					}
-				}
-			})
-		}
-	}
-
-	styp.fields = fields
-	styp.tags = tags
-}
-
-func embeddedFieldIdent(e syntax.Expr) *syntax.Name {
-	switch e := e.(type) {
-	case *syntax.Name:
-		return e
-	case *syntax.Operation:
-		if base := ptrBase(e); base != nil {
-			// *T is valid, but **T is not
-			if op, _ := base.(*syntax.Operation); op == nil || ptrBase(op) == nil {
-				return embeddedFieldIdent(e.X)
-			}
-		}
-	case *syntax.SelectorExpr:
-		return e.Sel
-	case *syntax.IndexExpr:
-		return embeddedFieldIdent(e.X)
-	}
-	return nil // invalid embedded field
-}
-
-func (check *Checker) collectTypeConstraints(pos syntax.Pos, types []syntax.Expr) []Type {
-	list := make([]Type, 0, len(types)) // assume all types are correct
-	for _, texpr := range types {
-		if texpr == nil {
-			check.error(pos, invalidAST+"missing type constraint")
-			continue
-		}
-		list = append(list, check.varType(texpr))
-	}
-
-	// Ensure that each type is only present once in the type list.  Types may be
-	// interfaces, which may not be complete yet. It's ok to do this check at the
-	// end because it's not a requirement for correctness of the code.
-	// Note: This is a quadratic algorithm, but type lists tend to be short.
-	check.later(func() {
-		for i, t := range list {
-			if t := asInterface(t); t != nil {
-				check.completeInterface(types[i].Pos(), t)
-			}
-			if includes(list[:i], t) {
-				check.softErrorf(types[i], "duplicate type %s in type list", t)
-			}
-		}
-	})
-
-	return list
-}
-
-// includes reports whether typ is in list
-func includes(list []Type, typ Type) bool {
-	for _, e := range list {
-		if Identical(typ, e) {
-			return true
-		}
-	}
-	return false
-}
-
-func ptrBase(x *syntax.Operation) syntax.Expr {
-	if x.Op == syntax.Mul && x.Y == nil {
-		return x.X
-	}
-	return nil
-}
diff --git a/src/cmd/compile/internal/types2/unify.go b/src/cmd/compile/internal/types2/unify.go
index e1832bbb2a36232cd00a04e2e195ae51711938fe..d4fbebc11b382e51dd995a3db79f4b8694bf8718 100644
--- a/src/cmd/compile/internal/types2/unify.go
+++ b/src/cmd/compile/internal/types2/unify.go
@@ -6,7 +6,10 @@
 
 package types2
 
-import "bytes"
+import (
+	"bytes"
+	"fmt"
+)
 
 // The unifier maintains two separate sets of type parameters x and y
 // which are used to resolve type parameters in the x and y arguments
@@ -34,7 +37,6 @@ import "bytes"
 // and the respective types inferred for each type parameter.
 // A unifier is created by calling newUnifier.
 type unifier struct {
-	check *Checker
 	exact bool
 	x, y  tparamsList // x and y must initialized via tparamsList.init
 	types []Type      // inferred types, shared by x and y
@@ -45,8 +47,8 @@ type unifier struct {
 // exactly. If exact is not set, a named type's underlying type
 // is considered if unification would fail otherwise, and the
 // direction of channels is ignored.
-func newUnifier(check *Checker, exact bool) *unifier {
-	u := &unifier{check: check, exact: exact}
+func newUnifier(exact bool) *unifier {
+	u := &unifier{exact: exact}
 	u.x.unifier = u
 	u.y.unifier = u
 	return u
@@ -60,7 +62,7 @@ func (u *unifier) unify(x, y Type) bool {
 // A tparamsList describes a list of type parameters and the types inferred for them.
 type tparamsList struct {
 	unifier *unifier
-	tparams []*TypeName
+	tparams []*TypeParam
 	// For each tparams element, there is a corresponding type slot index in indices.
 	// index  < 0: unifier.types[-index-1] == nil
 	// index == 0: no type slot allocated yet
@@ -75,11 +77,11 @@ type tparamsList struct {
 func (d *tparamsList) String() string {
 	var buf bytes.Buffer
 	buf.WriteByte('[')
-	for i, tname := range d.tparams {
+	for i, tpar := range d.tparams {
 		if i > 0 {
 			buf.WriteString(", ")
 		}
-		writeType(&buf, tname.typ, nil, nil)
+		writeType(&buf, tpar, nil, nil)
 		buf.WriteString(": ")
 		writeType(&buf, d.at(i), nil, nil)
 	}
@@ -90,13 +92,13 @@ func (d *tparamsList) String() string {
 // init initializes d with the given type parameters.
 // The type parameters must be in the order in which they appear in their declaration
 // (this ensures that the tparams indices match the respective type parameter index).
-func (d *tparamsList) init(tparams []*TypeName) {
+func (d *tparamsList) init(tparams []*TypeParam) {
 	if len(tparams) == 0 {
 		return
 	}
 	if debug {
 		for i, tpar := range tparams {
-			assert(i == tpar.typ.(*TypeParam).index)
+			assert(i == tpar.index)
 		}
 	}
 	d.tparams = tparams
@@ -148,10 +150,17 @@ func (u *unifier) join(i, j int) bool {
 // If typ is a type parameter of d, index returns the type parameter index.
 // Otherwise, the result is < 0.
 func (d *tparamsList) index(typ Type) int {
-	if t, ok := typ.(*TypeParam); ok {
-		if i := t.index; i < len(d.tparams) && d.tparams[i].typ == t {
-			return i
-		}
+	if tpar, ok := typ.(*TypeParam); ok {
+		return tparamIndex(d.tparams, tpar)
+	}
+	return -1
+}
+
+// If tpar is a type parameter in list, tparamIndex returns the type parameter index.
+// Otherwise, the result is < 0. tpar must not be nil.
+func tparamIndex(list []*TypeParam, tpar *TypeParam) int {
+	if i := tpar.index; i < len(list) && list[i] == tpar {
+		return i
 	}
 	return -1
 }
@@ -220,10 +229,6 @@ func (u *unifier) nifyEq(x, y Type, p *ifacePair) bool {
 // code the corresponding changes should be made here.
 // Must not be called directly from outside the unifier.
 func (u *unifier) nify(x, y Type, p *ifacePair) bool {
-	// types must be expanded for comparison
-	x = expand(x)
-	y = expand(y)
-
 	if !u.exact {
 		// If exact unification is known to fail because we attempt to
 		// match a type name against an unnamed type literal, consider
@@ -352,25 +357,18 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
 				u.nify(x.results, y.results, p)
 		}
 
-	case *Sum:
-		// This should not happen with the current internal use of sum types.
-		panic("type inference across sum types not implemented")
-
 	case *Interface:
 		// Two interface types are identical if they have the same set of methods with
 		// the same names and identical function types. Lower-case method names from
 		// different packages are always different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if u.check != nil {
-				u.check.completeInterface(nopos, x)
-				u.check.completeInterface(nopos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !xset.terms.equal(yset.terms) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -428,19 +426,20 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
 		}
 
 	case *Named:
-		// Two named types are identical if their type names originate
-		// in the same type declaration.
-		// if y, ok := y.(*Named); ok {
-		// 	return x.obj == y.obj
-		// }
 		if y, ok := y.(*Named); ok {
+			x.expand(nil)
+			y.expand(nil)
+
+			xargs := x.targs.list()
+			yargs := y.targs.list()
+
 			// TODO(gri) This is not always correct: two types may have the same names
 			//           in the same package if one of them is nested in a function.
 			//           Extremely unlikely but we need an always correct solution.
 			if x.obj.pkg == y.obj.pkg && x.obj.name == y.obj.name {
-				assert(len(x.targs) == len(y.targs))
-				for i, x := range x.targs {
-					if !u.nify(x, y.targs[i], p) {
+				assert(len(xargs) == len(yargs))
+				for i, x := range xargs {
+					if !u.nify(x, yargs[i], p) {
 						return false
 					}
 				}
@@ -454,15 +453,11 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
 		// are identical if they originate in the same declaration.
 		return x == y
 
-	// case *instance:
-	//	unreachable since types are expanded
-
 	case nil:
 		// avoid a crash in case of nil type
 
 	default:
-		u.check.dump("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams)
-		unreachable()
+		panic(fmt.Sprintf("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams))
 	}
 
 	return false
diff --git a/src/cmd/compile/internal/types2/union.go b/src/cmd/compile/internal/types2/union.go
new file mode 100644
index 0000000000000000000000000000000000000000..933e5a295185530169bd2a101436795ac0f54bae
--- /dev/null
+++ b/src/cmd/compile/internal/types2/union.go
@@ -0,0 +1,150 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "cmd/compile/internal/syntax"
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Union represents a union of terms embedded in an interface.
+type Union struct {
+	terms []*Term   // list of syntactical terms (not a canonicalized termlist)
+	tset  *_TypeSet // type set described by this union, computed lazily
+}
+
+// NewUnion returns a new Union type with the given terms.
+// It is an error to create an empty union; they are syntactically not possible.
+func NewUnion(terms []*Term) *Union {
+	if len(terms) == 0 {
+		panic("empty union")
+	}
+	return &Union{terms, nil}
+}
+
+func (u *Union) Len() int         { return len(u.terms) }
+func (u *Union) Term(i int) *Term { return u.terms[i] }
+
+func (u *Union) Underlying() Type { return u }
+func (u *Union) String() string   { return TypeString(u, nil) }
+
+// A Term represents a term in a Union.
+type Term term
+
+// NewTerm returns a new union term.
+func NewTerm(tilde bool, typ Type) *Term { return &Term{tilde, typ} }
+
+func (t *Term) Tilde() bool    { return t.tilde }
+func (t *Term) Type() Type     { return t.typ }
+func (t *Term) String() string { return (*term)(t).String() }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// Avoid excessive type-checking times due to quadratic termlist operations.
+const maxTermCount = 100
+
+// parseUnion parses the given list of type expressions tlist as a union of
+// those expressions. The result is a Union type, or Typ[Invalid] for some
+// errors.
+func parseUnion(check *Checker, tlist []syntax.Expr) Type {
+	var terms []*Term
+	for _, x := range tlist {
+		tilde, typ := parseTilde(check, x)
+		if len(tlist) == 1 && !tilde {
+			return typ // single type (optimization)
+		}
+		if len(terms) >= maxTermCount {
+			check.errorf(x, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+			return Typ[Invalid]
+		}
+		terms = append(terms, NewTerm(tilde, typ))
+	}
+
+	// Check validity of terms.
+	// Do this check later because it requires types to be set up.
+	// Note: This is a quadratic algorithm, but unions tend to be short.
+	check.later(func() {
+		for i, t := range terms {
+			if t.typ == Typ[Invalid] {
+				continue
+			}
+
+			x := tlist[i]
+			pos := syntax.StartPos(x)
+			// We may not know the position of x if it was a typechecker-
+			// introduced ~T term for a type list entry T. Use the position
+			// of T instead.
+			// TODO(gri) remove this test once we don't support type lists anymore
+			if !pos.IsKnown() {
+				if op, _ := x.(*syntax.Operation); op != nil {
+					pos = syntax.StartPos(op.X)
+				}
+			}
+
+			u := under(t.typ)
+			f, _ := u.(*Interface)
+			if t.tilde {
+				if f != nil {
+					check.errorf(x, "invalid use of ~ (%s is an interface)", t.typ)
+					continue // don't report another error for t
+				}
+
+				if !Identical(u, t.typ) {
+					check.errorf(x, "invalid use of ~ (underlying type of %s is %s)", t.typ, u)
+					continue // don't report another error for t
+				}
+			}
+
+			// Stand-alone embedded interfaces are ok and are handled by the single-type case
+			// in the beginning. Embedded interfaces with tilde are excluded above. If we reach
+			// here, we must have at least two terms in the union.
+			if f != nil && !f.typeSet().IsTypeSet() {
+				check.errorf(pos, "cannot use %s in union (interface contains methods)", t)
+				continue // don't report another error for t
+			}
+
+			// Report overlapping (non-disjoint) terms such as
+			// a|a, a|~a, ~a|~a, and ~a|A (where under(A) == a).
+			if j := overlappingTerm(terms[:i], t); j >= 0 {
+				check.softErrorf(pos, "overlapping terms %s and %s", t, terms[j])
+			}
+		}
+	})
+
+	return &Union{terms, nil}
+}
+
+func parseTilde(check *Checker, x syntax.Expr) (tilde bool, typ Type) {
+	if op, _ := x.(*syntax.Operation); op != nil && op.Op == syntax.Tilde {
+		x = op.X
+		tilde = true
+	}
+	typ = check.anyType(x)
+	// embedding stand-alone type parameters is not permitted (issue #47127).
+	if _, ok := under(typ).(*TypeParam); ok {
+		check.error(x, "cannot embed a type parameter")
+		typ = Typ[Invalid]
+	}
+	return
+}
+
+// overlappingTerm reports the index of the term x in terms which is
+// overlapping (not disjoint) from y. The result is < 0 if there is no
+// such term.
+func overlappingTerm(terms []*Term, y *Term) int {
+	for i, x := range terms {
+		// disjoint requires non-nil, non-top arguments
+		if debug {
+			if x == nil || x.typ == nil || y == nil || y.typ == nil {
+				panic("empty or top union term")
+			}
+		}
+		if !(*term)(x).disjoint((*term)(y)) {
+			return i
+		}
+	}
+	return -1
+}
diff --git a/src/cmd/compile/internal/types2/universe.go b/src/cmd/compile/internal/types2/universe.go
index 76d4e55e84b59127dd4d3b5d9335a37c8369d0a8..a615b4c8760086d1b29fa8c4b89b665aa0ddeb9e 100644
--- a/src/cmd/compile/internal/types2/universe.go
+++ b/src/cmd/compile/internal/types2/universe.go
@@ -20,11 +20,12 @@ var Universe *Scope
 var Unsafe *Package
 
 var (
-	universeIota  *Const
-	universeByte  *Basic // uint8 alias, but has name "byte"
-	universeRune  *Basic // int32 alias, but has name "rune"
-	universeAny   *Interface
-	universeError *Named
+	universeIota       Object
+	universeByte       Type // uint8 alias, but has name "byte"
+	universeRune       Type // int32 alias, but has name "rune"
+	universeAny        Object
+	universeError      Type
+	universeComparable Object
 )
 
 // Typ contains the predeclared *Basic types indexed by their
@@ -77,20 +78,30 @@ func defPredeclaredTypes() {
 		def(NewTypeName(nopos, nil, t.name, t))
 	}
 
-	// any
-	// (Predeclared and entered into universe scope so we do all the
-	// usual checks; but removed again from scope later since it's
-	// only visible as constraint in a type parameter list.)
+	// type any = interface{}
 	def(NewTypeName(nopos, nil, "any", &emptyInterface))
 
-	// Error has a nil package in its qualified name since it is in no package
+	// type error interface{ Error() string }
 	{
+		obj := NewTypeName(nopos, nil, "error", nil)
+		obj.setColor(black)
 		res := NewVar(nopos, nil, "", Typ[String])
-		sig := &Signature{results: NewTuple(res)}
+		sig := NewSignature(nil, nil, NewTuple(res), false)
 		err := NewFunc(nopos, nil, "Error", sig)
-		typ := &Named{underlying: NewInterfaceType([]*Func{err}, nil).Complete()}
+		ityp := &Interface{obj, []*Func{err}, nil, nil, true, nil}
+		computeInterfaceTypeSet(nil, nopos, ityp) // prevent races due to lazy computation of tset
+		typ := NewNamed(obj, ityp, nil)
 		sig.recv = NewVar(nopos, nil, "", typ)
-		def(NewTypeName(nopos, nil, "error", typ))
+		def(obj)
+	}
+
+	// type comparable interface{ /* type set marked comparable */ }
+	{
+		obj := NewTypeName(nopos, nil, "comparable", nil)
+		obj.setColor(black)
+		ityp := &Interface{obj, nil, nil, nil, true, &_TypeSet{true, nil, allTermlist}}
+		NewNamed(obj, ityp, nil)
+		def(obj)
 	}
 }
 
@@ -200,33 +211,6 @@ func DefPredeclaredTestFuncs() {
 	def(newBuiltin(_Trace))
 }
 
-func defPredeclaredComparable() {
-	// The "comparable" interface can be imagined as defined like
-	//
-	// type comparable interface {
-	//         == () untyped bool
-	//         != () untyped bool
-	// }
-	//
-	// == and != cannot be user-declared but we can declare
-	// a magic method == and check for its presence when needed.
-
-	// Define interface { == () }. We don't care about the signature
-	// for == so leave it empty except for the receiver, which is
-	// set up later to match the usual interface method assumptions.
-	sig := new(Signature)
-	eql := NewFunc(nopos, nil, "==", sig)
-	iface := NewInterfaceType([]*Func{eql}, nil).Complete()
-
-	// set up the defined type for the interface
-	obj := NewTypeName(nopos, nil, "comparable", nil)
-	named := NewNamed(obj, iface, nil)
-	obj.color_ = black
-	sig.recv = NewVar(nopos, nil, "", named) // complete == signature
-
-	def(obj)
-}
-
 func init() {
 	Universe = NewScope(nil, nopos, nopos, "universe")
 	Unsafe = NewPackage("unsafe", "unsafe")
@@ -236,16 +220,13 @@ func init() {
 	defPredeclaredConsts()
 	defPredeclaredNil()
 	defPredeclaredFuncs()
-	defPredeclaredComparable()
-
-	universeIota = Universe.Lookup("iota").(*Const)
-	universeByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
-	universeRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
-	universeAny = Universe.Lookup("any").(*TypeName).typ.(*Interface)
-	universeError = Universe.Lookup("error").(*TypeName).typ.(*Named)
 
-	// "any" is only visible as constraint in a type parameter list
-	delete(Universe.elems, "any")
+	universeIota = Universe.Lookup("iota")
+	universeByte = Universe.Lookup("byte").Type()
+	universeRune = Universe.Lookup("rune").Type()
+	universeAny = Universe.Lookup("any")
+	universeError = Universe.Lookup("error").Type()
+	universeComparable = Universe.Lookup("comparable")
 }
 
 // Objects with names containing blanks are internal and not entered into
@@ -277,6 +258,6 @@ func def(obj Object) {
 		}
 	}
 	if scope.Insert(obj) != nil {
-		panic("internal error: double declaration")
+		panic("double declaration of predeclared identifier")
 	}
 }
diff --git a/src/cmd/compile/internal/walk/assign.go b/src/cmd/compile/internal/walk/assign.go
index 6d697a53ae3aaa14442a21f9f4e15880bbfe75c2..d4c1aafdc121dcbb9226341618e94c0f1c6bc67f 100644
--- a/src/cmd/compile/internal/walk/assign.go
+++ b/src/cmd/compile/internal/walk/assign.go
@@ -429,6 +429,7 @@ func readsMemory(n ir.Node) bool {
 		ir.OBITNOT,
 		ir.OCONV,
 		ir.OCONVIFACE,
+		ir.OCONVIDATA,
 		ir.OCONVNOP,
 		ir.ODIV,
 		ir.ODOT,
diff --git a/src/cmd/compile/internal/walk/builtin.go b/src/cmd/compile/internal/walk/builtin.go
index 14efc05e32753727502e42f4e805ebe134522125..af4f8f482286629dd6df9f0b6d8ac6e0d41604f8 100644
--- a/src/cmd/compile/internal/walk/builtin.go
+++ b/src/cmd/compile/internal/walk/builtin.go
@@ -641,16 +641,9 @@ func walkPrint(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
 	return walkStmt(typecheck.Stmt(r))
 }
 
-// walkRecover walks an ORECOVER node.
-func walkRecover(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
-	// Call gorecover with the FP of this frame.
-	// FP is equal to caller's SP plus FixedFrameSize().
-	var fp ir.Node = mkcall("getcallersp", types.Types[types.TUINTPTR], init)
-	if off := base.Ctxt.FixedFrameSize(); off != 0 {
-		fp = ir.NewBinaryExpr(fp.Pos(), ir.OADD, fp, ir.NewInt(off))
-	}
-	fp = ir.NewConvExpr(fp.Pos(), ir.OCONVNOP, types.NewPtr(types.Types[types.TINT32]), fp)
-	return mkcall("gorecover", nn.Type(), init, fp)
+// walkRecover walks an ORECOVERFP node.
+func walkRecoverFP(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
+	return mkcall("gorecover", nn.Type(), init, walkExpr(nn.Args[0], init))
 }
 
 func walkUnsafeSlice(n *ir.BinaryExpr, init *ir.Nodes) ir.Node {
diff --git a/src/cmd/compile/internal/walk/closure.go b/src/cmd/compile/internal/walk/closure.go
index 2194e1c5b0c7a3fd9f5ed01a57bb1e8aeb613238..902e01ef388ee39ee5046905c1edd024cd27921d 100644
--- a/src/cmd/compile/internal/walk/closure.go
+++ b/src/cmd/compile/internal/walk/closure.go
@@ -37,14 +37,6 @@ func directClosureCall(n *ir.CallExpr) {
 		return // leave for walkClosure to handle
 	}
 
-	// If wrapGoDefer() in the order phase has flagged this call,
-	// avoid eliminating the closure even if there is a direct call to
-	// (the closure is needed to simplify the register ABI). See
-	// wrapGoDefer for more details.
-	if n.PreserveClosure {
-		return
-	}
-
 	// We are going to insert captured variables before input args.
 	var params []*types.Field
 	var decls []*ir.Name
@@ -122,6 +114,9 @@ func walkClosure(clo *ir.ClosureExpr, init *ir.Nodes) ir.Node {
 	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
 	clos.SetEsc(clo.Esc())
 	clos.List = append([]ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, clofn.Nname)}, closureArgs(clo)...)
+	for i, value := range clos.List {
+		clos.List[i] = ir.NewStructKeyExpr(base.Pos, typ.Field(i), value)
+	}
 
 	addr := typecheck.NodAddr(clos)
 	addr.SetEsc(clo.Esc())
@@ -161,7 +156,7 @@ func closureArgs(clo *ir.ClosureExpr) []ir.Node {
 	return args
 }
 
-func walkCallPart(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
+func walkMethodValue(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 	// Create closure in the form of a composite literal.
 	// For x.M with receiver (x) type T, the generated code looks like:
 	//
@@ -175,18 +170,16 @@ func walkCallPart(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 		n.X = cheapExpr(n.X, init)
 		n.X = walkExpr(n.X, nil)
 
-		tab := typecheck.Expr(ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X))
-
-		c := ir.NewUnaryExpr(base.Pos, ir.OCHECKNIL, tab)
-		c.SetTypecheck(1)
-		init.Append(c)
+		tab := ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X)
+		check := ir.NewUnaryExpr(base.Pos, ir.OCHECKNIL, tab)
+		init.Append(typecheck.Stmt(check))
 	}
 
-	typ := typecheck.PartialCallType(n)
+	typ := typecheck.MethodValueType(n)
 
 	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
 	clos.SetEsc(n.Esc())
-	clos.List = []ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, typecheck.MethodValueWrapper(n).Nname), n.X}
+	clos.List = []ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, methodValueWrapper(n)), n.X}
 
 	addr := typecheck.NodAddr(clos)
 	addr.SetEsc(n.Esc())
@@ -205,3 +198,74 @@ func walkCallPart(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 
 	return walkExpr(cfn, init)
 }
+
+// methodValueWrapper returns the ONAME node representing the
+// wrapper function (*-fm) needed for the given method value. If the
+// wrapper function hasn't already been created yet, it's created and
+// added to typecheck.Target.Decls.
+func methodValueWrapper(dot *ir.SelectorExpr) *ir.Name {
+	if dot.Op() != ir.OMETHVALUE {
+		base.Fatalf("methodValueWrapper: unexpected %v (%v)", dot, dot.Op())
+	}
+
+	t0 := dot.Type()
+	meth := dot.Sel
+	rcvrtype := dot.X.Type()
+	sym := ir.MethodSymSuffix(rcvrtype, meth, "-fm")
+
+	if sym.Uniq() {
+		return sym.Def.(*ir.Name)
+	}
+	sym.SetUniq(true)
+
+	savecurfn := ir.CurFunc
+	saveLineNo := base.Pos
+	ir.CurFunc = nil
+
+	// Set line number equal to the line number where the method is declared.
+	if pos := dot.Selection.Pos; pos.IsKnown() {
+		base.Pos = pos
+	}
+	// Note: !dot.Selection.Pos.IsKnown() happens for method expressions where
+	// the method is implicitly declared. The Error method of the
+	// built-in error type is one such method.  We leave the line
+	// number at the use of the method expression in this
+	// case. See issue 29389.
+
+	tfn := ir.NewFuncType(base.Pos, nil,
+		typecheck.NewFuncParams(t0.Params(), true),
+		typecheck.NewFuncParams(t0.Results(), false))
+
+	fn := typecheck.DeclFunc(sym, tfn)
+	fn.SetDupok(true)
+	fn.SetWrapper(true)
+
+	// Declare and initialize variable holding receiver.
+	ptr := ir.NewHiddenParam(base.Pos, fn, typecheck.Lookup(".this"), rcvrtype)
+
+	call := ir.NewCallExpr(base.Pos, ir.OCALL, ir.NewSelectorExpr(base.Pos, ir.OXDOT, ptr, meth), nil)
+	call.Args = ir.ParamNames(tfn.Type())
+	call.IsDDD = tfn.Type().IsVariadic()
+
+	var body ir.Node = call
+	if t0.NumResults() != 0 {
+		ret := ir.NewReturnStmt(base.Pos, nil)
+		ret.Results = []ir.Node{call}
+		body = ret
+	}
+
+	fn.Body = []ir.Node{body}
+	typecheck.FinishFuncBody()
+
+	typecheck.Func(fn)
+	// Need to typecheck the body of the just-generated wrapper.
+	// typecheckslice() requires that Curfn is set when processing an ORETURN.
+	ir.CurFunc = fn
+	typecheck.Stmts(fn.Body)
+	sym.Def = fn.Nname
+	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
+	ir.CurFunc = savecurfn
+	base.Pos = saveLineNo
+
+	return fn.Nname
+}
diff --git a/src/cmd/compile/internal/walk/complit.go b/src/cmd/compile/internal/walk/complit.go
index abd920d64612ff720dbfc27e6b37d6ce32f64e7f..e8e941dd915c9e19312b4a9e1d770b6a97b68541 100644
--- a/src/cmd/compile/internal/walk/complit.go
+++ b/src/cmd/compile/internal/walk/complit.go
@@ -218,11 +218,11 @@ func fixedlit(ctxt initContext, kind initKind, n *ir.CompLitExpr, var_ ir.Node,
 	case ir.OSTRUCTLIT:
 		splitnode = func(rn ir.Node) (ir.Node, ir.Node) {
 			r := rn.(*ir.StructKeyExpr)
-			if r.Field.IsBlank() || isBlank {
+			if r.Sym().IsBlank() || isBlank {
 				return ir.BlankNode, r.Value
 			}
 			ir.SetPos(r)
-			return ir.NewSelectorExpr(base.Pos, ir.ODOT, var_, r.Field), r.Value
+			return ir.NewSelectorExpr(base.Pos, ir.ODOT, var_, r.Sym()), r.Value
 		}
 	default:
 		base.Fatalf("fixedlit bad op: %v", n.Op())
@@ -440,8 +440,8 @@ func maplit(n *ir.CompLitExpr, m ir.Node, init *ir.Nodes) {
 		tk := types.NewArray(n.Type().Key(), int64(len(entries)))
 		te := types.NewArray(n.Type().Elem(), int64(len(entries)))
 
-		tk.SetNoalg(true)
-		te.SetNoalg(true)
+		// TODO(#47904): mark tk and te NoAlg here once the
+		// compiler/linker can handle NoAlg types correctly.
 
 		types.CalcSize(tk)
 		types.CalcSize(te)
diff --git a/src/cmd/compile/internal/walk/convert.go b/src/cmd/compile/internal/walk/convert.go
index 26e17a126f22151a542fecf9026002846baa82ca..27a07ce4b6085031262d6e8590703fcceaa0114b 100644
--- a/src/cmd/compile/internal/walk/convert.go
+++ b/src/cmd/compile/internal/walk/convert.go
@@ -41,46 +41,98 @@ func walkConv(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 
 // walkConvInterface walks an OCONVIFACE node.
 func walkConvInterface(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
+
 	n.X = walkExpr(n.X, init)
 
 	fromType := n.X.Type()
 	toType := n.Type()
-
-	if !fromType.IsInterface() && !ir.IsBlank(ir.CurFunc.Nname) { // skip unnamed functions (func _())
+	if !fromType.IsInterface() && !ir.IsBlank(ir.CurFunc.Nname) {
+		// skip unnamed functions (func _())
 		reflectdata.MarkTypeUsedInInterface(fromType, ir.CurFunc.LSym)
 	}
 
-	// typeword generates the type word of the interface value.
-	typeword := func() ir.Node {
+	if !fromType.IsInterface() {
+		var typeWord ir.Node
 		if toType.IsEmptyInterface() {
-			return reflectdata.TypePtr(fromType)
+			typeWord = reflectdata.TypePtr(fromType)
+		} else {
+			typeWord = reflectdata.ITabAddr(fromType, toType)
 		}
-		return reflectdata.ITabAddr(fromType, toType)
-	}
-
-	// Optimize convT2E or convT2I as a two-word copy when T is pointer-shaped.
-	if types.IsDirectIface(fromType) {
-		l := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeword(), n.X)
+		l := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeWord, dataWord(n.X, init, n.Esc() != ir.EscNone))
 		l.SetType(toType)
 		l.SetTypecheck(n.Typecheck())
 		return l
 	}
+	if fromType.IsEmptyInterface() {
+		base.Fatalf("OCONVIFACE can't operate on an empty interface")
+	}
 
-	// Optimize convT2{E,I} for many cases in which T is not pointer-shaped,
-	// by using an existing addressable value identical to n.Left
-	// or creating one on the stack.
+	// Evaluate the input interface.
+	c := typecheck.Temp(fromType)
+	init.Append(ir.NewAssignStmt(base.Pos, c, n.X))
+
+	// Grab its parts.
+	itab := ir.NewUnaryExpr(base.Pos, ir.OITAB, c)
+	itab.SetType(types.Types[types.TUINTPTR].PtrTo())
+	itab.SetTypecheck(1)
+	data := ir.NewUnaryExpr(base.Pos, ir.OIDATA, c)
+	data.SetType(types.Types[types.TUINT8].PtrTo()) // Type is generic pointer - we're just passing it through.
+	data.SetTypecheck(1)
+
+	var typeWord ir.Node
+	if toType.IsEmptyInterface() {
+		// Implement interface to empty interface conversion.
+		// res = itab
+		// if res != nil {
+		//    res = res.type
+		// }
+		typeWord = typecheck.Temp(types.NewPtr(types.Types[types.TUINT8]))
+		init.Append(ir.NewAssignStmt(base.Pos, typeWord, itab))
+		nif := ir.NewIfStmt(base.Pos, typecheck.Expr(ir.NewBinaryExpr(base.Pos, ir.ONE, typeWord, typecheck.NodNil())), nil, nil)
+		nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, typeWord, itabType(typeWord))}
+		init.Append(nif)
+	} else {
+		// Must be converting I2I (more specific to less specific interface).
+		// res = convI2I(toType, itab)
+		fn := typecheck.LookupRuntime("convI2I")
+		types.CalcSize(fn.Type())
+		call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, nil)
+		call.Args = []ir.Node{reflectdata.TypePtr(toType), itab}
+		typeWord = walkExpr(typecheck.Expr(call), init)
+	}
+
+	// Build the result.
+	// e = iface{typeWord, data}
+	e := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeWord, data)
+	e.SetType(toType) // assign type manually, typecheck doesn't understand OEFACE.
+	e.SetTypecheck(1)
+	return e
+}
+
+// Returns the data word (the second word) used to represent n in an interface.
+// n must not be of interface type.
+// esc describes whether the result escapes.
+func dataWord(n ir.Node, init *ir.Nodes, escapes bool) ir.Node {
+	fromType := n.Type()
+
+	// If it's a pointer, it is its own representation.
+	if types.IsDirectIface(fromType) {
+		return n
+	}
+
+	// Try a bunch of cases to avoid an allocation.
 	var value ir.Node
 	switch {
 	case fromType.Size() == 0:
-		// n.Left is zero-sized. Use zerobase.
-		cheapExpr(n.X, init) // Evaluate n.Left for side-effects. See issue 19246.
+		// n is zero-sized. Use zerobase.
+		cheapExpr(n, init) // Evaluate n for side-effects. See issue 19246.
 		value = ir.NewLinksymExpr(base.Pos, ir.Syms.Zerobase, types.Types[types.TUINTPTR])
 	case fromType.IsBoolean() || (fromType.Size() == 1 && fromType.IsInteger()):
-		// n.Left is a bool/byte. Use staticuint64s[n.Left * 8] on little-endian
-		// and staticuint64s[n.Left * 8 + 7] on big-endian.
-		n.X = cheapExpr(n.X, init)
-		// byteindex widens n.Left so that the multiplication doesn't overflow.
-		index := ir.NewBinaryExpr(base.Pos, ir.OLSH, byteindex(n.X), ir.NewInt(3))
+		// n is a bool/byte. Use staticuint64s[n * 8] on little-endian
+		// and staticuint64s[n * 8 + 7] on big-endian.
+		n = cheapExpr(n, init)
+		// byteindex widens n so that the multiplication doesn't overflow.
+		index := ir.NewBinaryExpr(base.Pos, ir.OLSH, byteindex(n), ir.NewInt(3))
 		if ssagen.Arch.LinkArch.ByteOrder == binary.BigEndian {
 			index = ir.NewBinaryExpr(base.Pos, ir.OADD, index, ir.NewInt(7))
 		}
@@ -90,118 +142,71 @@ func walkConvInterface(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 		xe := ir.NewIndexExpr(base.Pos, staticuint64s, index)
 		xe.SetBounded(true)
 		value = xe
-	case n.X.Op() == ir.ONAME && n.X.(*ir.Name).Class == ir.PEXTERN && n.X.(*ir.Name).Readonly():
-		// n.Left is a readonly global; use it directly.
-		value = n.X
-	case !fromType.IsInterface() && n.Esc() == ir.EscNone && fromType.Width <= 1024:
-		// n.Left does not escape. Use a stack temporary initialized to n.Left.
+	case n.Op() == ir.ONAME && n.(*ir.Name).Class == ir.PEXTERN && n.(*ir.Name).Readonly():
+		// n is a readonly global; use it directly.
+		value = n
+	case !escapes && fromType.Width <= 1024:
+		// n does not escape. Use a stack temporary initialized to n.
 		value = typecheck.Temp(fromType)
-		init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, value, n.X)))
+		init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, value, n)))
 	}
-
 	if value != nil {
-		// Value is identical to n.Left.
-		// Construct the interface directly: {type/itab, &value}.
-		l := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeword(), typecheck.Expr(typecheck.NodAddr(value)))
-		l.SetType(toType)
-		l.SetTypecheck(n.Typecheck())
-		return l
-	}
-
-	// Implement interface to empty interface conversion.
-	// tmp = i.itab
-	// if tmp != nil {
-	//    tmp = tmp.type
-	// }
-	// e = iface{tmp, i.data}
-	if toType.IsEmptyInterface() && fromType.IsInterface() && !fromType.IsEmptyInterface() {
-		// Evaluate the input interface.
-		c := typecheck.Temp(fromType)
-		init.Append(ir.NewAssignStmt(base.Pos, c, n.X))
-
-		// Get the itab out of the interface.
-		tmp := typecheck.Temp(types.NewPtr(types.Types[types.TUINT8]))
-		init.Append(ir.NewAssignStmt(base.Pos, tmp, typecheck.Expr(ir.NewUnaryExpr(base.Pos, ir.OITAB, c))))
-
-		// Get the type out of the itab.
-		nif := ir.NewIfStmt(base.Pos, typecheck.Expr(ir.NewBinaryExpr(base.Pos, ir.ONE, tmp, typecheck.NodNil())), nil, nil)
-		nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, tmp, itabType(tmp))}
-		init.Append(nif)
-
-		// Build the result.
-		e := ir.NewBinaryExpr(base.Pos, ir.OEFACE, tmp, ifaceData(n.Pos(), c, types.NewPtr(types.Types[types.TUINT8])))
-		e.SetType(toType) // assign type manually, typecheck doesn't understand OEFACE.
-		e.SetTypecheck(1)
-		return e
+		// The interface data word is &value.
+		return typecheck.Expr(typecheck.NodAddr(value))
 	}
 
-	fnname, argType, needsaddr := convFuncName(fromType, toType)
-
-	if !needsaddr && !fromType.IsInterface() {
-		// Use a specialized conversion routine that only returns a data pointer.
-		// ptr = convT2X(val)
-		// e = iface{typ/tab, ptr}
-		fn := typecheck.LookupRuntime(fnname)
-		types.CalcSize(fromType)
+	// Time to do an allocation. We'll call into the runtime for that.
+	fnname, argType, needsaddr := dataWordFuncName(fromType)
+	fn := typecheck.LookupRuntime(fnname)
 
-		arg := n.X
+	var args []ir.Node
+	if needsaddr {
+		// Types of large or unknown size are passed by reference.
+		// Orderexpr arranged for n to be a temporary for all
+		// the conversions it could see. Comparison of an interface
+		// with a non-interface, especially in a switch on interface value
+		// with non-interface cases, is not visible to order.stmt, so we
+		// have to fall back on allocating a temp here.
+		if !ir.IsAddressable(n) {
+			n = copyExpr(n, fromType, init)
+		}
+		fn = typecheck.SubstArgTypes(fn, fromType)
+		args = []ir.Node{reflectdata.TypePtr(fromType), typecheck.NodAddr(n)}
+	} else {
+		// Use a specialized conversion routine that takes the type being
+		// converted by value, not by pointer.
+		var arg ir.Node
 		switch {
 		case fromType == argType:
 			// already in the right type, nothing to do
+			arg = n
 		case fromType.Kind() == argType.Kind(),
 			fromType.IsPtrShaped() && argType.IsPtrShaped():
 			// can directly convert (e.g. named type to underlying type, or one pointer to another)
-			arg = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, argType, arg)
+			// TODO: never happens because pointers are directIface?
+			arg = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, argType, n)
 		case fromType.IsInteger() && argType.IsInteger():
 			// can directly convert (e.g. int32 to uint32)
-			arg = ir.NewConvExpr(n.Pos(), ir.OCONV, argType, arg)
+			arg = ir.NewConvExpr(n.Pos(), ir.OCONV, argType, n)
 		default:
 			// unsafe cast through memory
-			arg = copyExpr(arg, arg.Type(), init)
+			arg = copyExpr(n, fromType, init)
 			var addr ir.Node = typecheck.NodAddr(arg)
 			addr = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, argType.PtrTo(), addr)
 			arg = ir.NewStarExpr(n.Pos(), addr)
 			arg.SetType(argType)
 		}
-
-		call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, nil)
-		call.Args = []ir.Node{arg}
-		e := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeword(), safeExpr(walkExpr(typecheck.Expr(call), init), init))
-		e.SetType(toType)
-		e.SetTypecheck(1)
-		return e
-	}
-
-	var tab ir.Node
-	if fromType.IsInterface() {
-		// convI2I
-		tab = reflectdata.TypePtr(toType)
-	} else {
-		// convT2x
-		tab = typeword()
+		args = []ir.Node{arg}
 	}
-
-	v := n.X
-	if needsaddr {
-		// Types of large or unknown size are passed by reference.
-		// Orderexpr arranged for n.Left to be a temporary for all
-		// the conversions it could see. Comparison of an interface
-		// with a non-interface, especially in a switch on interface value
-		// with non-interface cases, is not visible to order.stmt, so we
-		// have to fall back on allocating a temp here.
-		if !ir.IsAddressable(v) {
-			v = copyExpr(v, v.Type(), init)
-		}
-		v = typecheck.NodAddr(v)
-	}
-
-	types.CalcSize(fromType)
-	fn := typecheck.LookupRuntime(fnname)
-	fn = typecheck.SubstArgTypes(fn, fromType, toType)
-	types.CalcSize(fn.Type())
 	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, nil)
-	call.Args = []ir.Node{tab, v}
-	return walkExpr(typecheck.Expr(call), init)
+	call.Args = args
+	return safeExpr(walkExpr(typecheck.Expr(call), init), init)
+}
+
+// walkConvIData walks an OCONVIDATA node.
+func walkConvIData(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
+	n.X = walkExpr(n.X, init)
+	return dataWord(n.X, init, n.Esc() != ir.EscNone)
 }
 
 // walkBytesRunesToString walks an OBYTES2STR or ORUNES2STR node.
@@ -312,50 +317,35 @@ func walkStringToRunes(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 	return mkcall("stringtoslicerune", n.Type(), init, a, typecheck.Conv(n.X, types.Types[types.TSTRING]))
 }
 
-// convFuncName builds the runtime function name for interface conversion.
-// It also returns the argument type that the runtime function takes, and
-// whether the function expects the data by address.
-// Not all names are possible. For example, we never generate convE2E or convE2I.
-func convFuncName(from, to *types.Type) (fnname string, argType *types.Type, needsaddr bool) {
-	tkind := to.Tie()
-	switch from.Tie() {
-	case 'I':
-		if tkind == 'I' {
-			return "convI2I", types.Types[types.TINTER], false
-		}
-	case 'T':
+// dataWordFuncName returns the name of the function used to convert a value of type "from"
+// to the data word of an interface.
+// argType is the type the argument needs to be coerced to.
+// needsaddr reports whether the value should be passed (needaddr==false) or its address (needsaddr==true).
+func dataWordFuncName(from *types.Type) (fnname string, argType *types.Type, needsaddr bool) {
+	if from.IsInterface() {
+		base.Fatalf("can only handle non-interfaces")
+	}
+	switch {
+	case from.Size() == 2 && from.Align == 2:
+		return "convT16", types.Types[types.TUINT16], false
+	case from.Size() == 4 && from.Align == 4 && !from.HasPointers():
+		return "convT32", types.Types[types.TUINT32], false
+	case from.Size() == 8 && from.Align == types.Types[types.TUINT64].Align && !from.HasPointers():
+		return "convT64", types.Types[types.TUINT64], false
+	}
+	if sc := from.SoleComponent(); sc != nil {
 		switch {
-		case from.Size() == 2 && from.Align == 2:
-			return "convT16", types.Types[types.TUINT16], false
-		case from.Size() == 4 && from.Align == 4 && !from.HasPointers():
-			return "convT32", types.Types[types.TUINT32], false
-		case from.Size() == 8 && from.Align == types.Types[types.TUINT64].Align && !from.HasPointers():
-			return "convT64", types.Types[types.TUINT64], false
-		}
-		if sc := from.SoleComponent(); sc != nil {
-			switch {
-			case sc.IsString():
-				return "convTstring", types.Types[types.TSTRING], false
-			case sc.IsSlice():
-				return "convTslice", types.NewSlice(types.Types[types.TUINT8]), false // the element type doesn't matter
-			}
+		case sc.IsString():
+			return "convTstring", types.Types[types.TSTRING], false
+		case sc.IsSlice():
+			return "convTslice", types.NewSlice(types.Types[types.TUINT8]), false // the element type doesn't matter
 		}
+	}
 
-		switch tkind {
-		case 'E':
-			if !from.HasPointers() {
-				return "convT2Enoptr", types.Types[types.TUNSAFEPTR], true
-			}
-			return "convT2E", types.Types[types.TUNSAFEPTR], true
-		case 'I':
-			if !from.HasPointers() {
-				return "convT2Inoptr", types.Types[types.TUNSAFEPTR], true
-			}
-			return "convT2I", types.Types[types.TUNSAFEPTR], true
-		}
+	if from.HasPointers() {
+		return "convT", types.Types[types.TUNSAFEPTR], true
 	}
-	base.Fatalf("unknown conv func %c2%c", from.Tie(), to.Tie())
-	panic("unreachable")
+	return "convTnoptr", types.Types[types.TUNSAFEPTR], true
 }
 
 // rtconvfn returns the parameter and result types that will be used by a
@@ -462,7 +452,9 @@ func walkCheckPtrArithmetic(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 	// TODO(mdempsky): Make stricter. We only need to exempt
 	// reflect.Value.Pointer and reflect.Value.UnsafeAddr.
 	switch n.X.Op() {
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
+	case ir.OCALLMETH:
+		base.FatalfAt(n.X.Pos(), "OCALLMETH missed by typecheck")
+	case ir.OCALLFUNC, ir.OCALLINTER:
 		return n
 	}
 
@@ -499,7 +491,7 @@ func walkCheckPtrArithmetic(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 
 	cheap := cheapExpr(n, init)
 
-	slice := typecheck.MakeDotArgs(types.NewSlice(types.Types[types.TUNSAFEPTR]), originals)
+	slice := typecheck.MakeDotArgs(base.Pos, types.NewSlice(types.Types[types.TUNSAFEPTR]), originals)
 	slice.SetEsc(ir.EscNone)
 
 	init.Append(mkcall("checkptrArithmetic", nil, init, typecheck.ConvNop(cheap, types.Types[types.TUNSAFEPTR]), slice))
diff --git a/src/cmd/compile/internal/walk/expr.go b/src/cmd/compile/internal/walk/expr.go
index 2fb907710bbbda09f6cdae70ba6a2fd734d84175..26e225440a73d5ed2d35c282d4d879222e828944 100644
--- a/src/cmd/compile/internal/walk/expr.go
+++ b/src/cmd/compile/internal/walk/expr.go
@@ -82,7 +82,7 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		base.Fatalf("walkExpr: switch 1 unknown op %+v", n.Op())
 		panic("unreachable")
 
-	case ir.ONONAME, ir.OGETG:
+	case ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP:
 		return n
 
 	case ir.OTYPE, ir.ONAME, ir.OLITERAL, ir.ONIL, ir.OLINKSYMOFFSET:
@@ -136,6 +136,10 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		n := n.(*ir.TypeAssertExpr)
 		return walkDotType(n, init)
 
+	case ir.ODYNAMICDOTTYPE, ir.ODYNAMICDOTTYPE2:
+		n := n.(*ir.DynamicTypeAssertExpr)
+		return walkDynamicDotType(n, init)
+
 	case ir.OLEN, ir.OCAP:
 		n := n.(*ir.UnaryExpr)
 		return walkLenCap(n, init)
@@ -161,13 +165,13 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		n := n.(*ir.UnaryExpr)
 		return mkcall("gopanic", nil, init, n.X)
 
-	case ir.ORECOVER:
-		return walkRecover(n.(*ir.CallExpr), init)
+	case ir.ORECOVERFP:
+		return walkRecoverFP(n.(*ir.CallExpr), init)
 
 	case ir.OCFUNC:
 		return n
 
-	case ir.OCALLINTER, ir.OCALLFUNC, ir.OCALLMETH:
+	case ir.OCALLINTER, ir.OCALLFUNC:
 		n := n.(*ir.CallExpr)
 		return walkCall(n, init)
 
@@ -206,6 +210,10 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		n := n.(*ir.ConvExpr)
 		return walkConvInterface(n, init)
 
+	case ir.OCONVIDATA:
+		n := n.(*ir.ConvExpr)
+		return walkConvIData(n, init)
+
 	case ir.OCONV, ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
 		return walkConv(n, init)
@@ -308,8 +316,8 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 	case ir.OCLOSURE:
 		return walkClosure(n.(*ir.ClosureExpr), init)
 
-	case ir.OCALLPART:
-		return walkCallPart(n.(*ir.SelectorExpr), init)
+	case ir.OMETHVALUE:
+		return walkMethodValue(n.(*ir.SelectorExpr), init)
 	}
 
 	// No return! Each case must return (or panic),
@@ -487,9 +495,12 @@ func walkAddString(n *ir.AddStringExpr, init *ir.Nodes) ir.Node {
 	return r1
 }
 
-// walkCall walks an OCALLFUNC, OCALLINTER, or OCALLMETH node.
+// walkCall walks an OCALLFUNC or OCALLINTER node.
 func walkCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
-	if n.Op() == ir.OCALLINTER || n.Op() == ir.OCALLMETH {
+	if n.Op() == ir.OCALLMETH {
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+	}
+	if n.Op() == ir.OCALLINTER || n.X.Op() == ir.OMETHEXPR {
 		// We expect both interface call reflect.Type.Method and concrete
 		// call reflect.(*rtype).Method.
 		usemethod(n)
@@ -549,20 +560,8 @@ func walkCall1(n *ir.CallExpr, init *ir.Nodes) {
 	}
 	n.SetWalked(true)
 
-	// If this is a method call t.M(...),
-	// rewrite into a function call T.M(t, ...).
-	// TODO(mdempsky): Do this right after type checking.
 	if n.Op() == ir.OCALLMETH {
-		withRecv := make([]ir.Node, len(n.Args)+1)
-		dot := n.X.(*ir.SelectorExpr)
-		withRecv[0] = dot.X
-		copy(withRecv[1:], n.Args)
-		n.Args = withRecv
-
-		dot = ir.NewSelectorExpr(dot.Pos(), ir.OXDOT, ir.TypeNode(dot.X.Type()), dot.Selection.Sym)
-
-		n.SetOp(ir.OCALLFUNC)
-		n.X = typecheck.Expr(dot)
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
 	}
 
 	args := n.Args
@@ -671,6 +670,13 @@ func walkDotType(n *ir.TypeAssertExpr, init *ir.Nodes) ir.Node {
 	return n
 }
 
+// walkDynamicdotType walks an ODYNAMICDOTTYPE or ODYNAMICDOTTYPE2 node.
+func walkDynamicDotType(n *ir.DynamicTypeAssertExpr, init *ir.Nodes) ir.Node {
+	n.X = walkExpr(n.X, init)
+	n.T = walkExpr(n.T, init)
+	return n
+}
+
 // walkIndex walks an OINDEX node.
 func walkIndex(n *ir.IndexExpr, init *ir.Nodes) ir.Node {
 	n.X = walkExpr(n.X, init)
@@ -931,56 +937,55 @@ func bounded(n ir.Node, max int64) bool {
 	return false
 }
 
-// usemethod checks interface method calls for uses of reflect.Type.Method.
+// usemethod checks calls for uses of reflect.Type.{Method,MethodByName}.
 func usemethod(n *ir.CallExpr) {
-	t := n.X.Type()
+	// Don't mark reflect.(*rtype).Method, etc. themselves in the reflect package.
+	// Those functions may be alive via the itab, which should not cause all methods
+	// alive. We only want to mark their callers.
+	if base.Ctxt.Pkgpath == "reflect" {
+		switch ir.CurFunc.Nname.Sym().Name { // TODO: is there a better way than hardcoding the names?
+		case "(*rtype).Method", "(*rtype).MethodByName", "(*interfaceType).Method", "(*interfaceType).MethodByName":
+			return
+		}
+	}
 
-	// Looking for either of:
-	//	Method(int) reflect.Method
-	//	MethodByName(string) (reflect.Method, bool)
-	//
-	// TODO(crawshaw): improve precision of match by working out
-	//                 how to check the method name.
-	if n := t.NumParams(); n != 1 {
+	dot, ok := n.X.(*ir.SelectorExpr)
+	if !ok {
 		return
 	}
-	if n := t.NumResults(); n != 1 && n != 2 {
+
+	// Looking for either direct method calls and interface method calls of:
+	//	reflect.Type.Method       - func(int) reflect.Method
+	//	reflect.Type.MethodByName - func(string) (reflect.Method, bool)
+	var pKind types.Kind
+
+	switch dot.Sel.Name {
+	case "Method":
+		pKind = types.TINT
+	case "MethodByName":
+		pKind = types.TSTRING
+	default:
 		return
 	}
-	p0 := t.Params().Field(0)
-	res0 := t.Results().Field(0)
-	var res1 *types.Field
-	if t.NumResults() == 2 {
-		res1 = t.Results().Field(1)
-	}
 
-	if res1 == nil {
-		if p0.Type.Kind() != types.TINT {
-			return
-		}
-	} else {
-		if !p0.Type.IsString() {
-			return
-		}
-		if !res1.Type.IsBoolean() {
-			return
-		}
+	t := dot.Selection.Type
+	if t.NumParams() != 1 || t.Params().Field(0).Type.Kind() != pKind {
+		return
 	}
-
-	// Don't mark reflect.(*rtype).Method, etc. themselves in the reflect package.
-	// Those functions may be alive via the itab, which should not cause all methods
-	// alive. We only want to mark their callers.
-	if base.Ctxt.Pkgpath == "reflect" {
-		switch ir.CurFunc.Nname.Sym().Name { // TODO: is there a better way than hardcoding the names?
-		case "(*rtype).Method", "(*rtype).MethodByName", "(*interfaceType).Method", "(*interfaceType).MethodByName":
+	switch t.NumResults() {
+	case 1:
+		// ok
+	case 2:
+		if t.Results().Field(1).Type.Kind() != types.TBOOL {
 			return
 		}
+	default:
+		return
 	}
 
-	// Note: Don't rely on res0.Type.String() since its formatting depends on multiple factors
-	//       (including global variables such as numImports - was issue #19028).
-	// Also need to check for reflect package itself (see Issue #38515).
-	if s := res0.Type.Sym(); s != nil && s.Name == "Method" && types.IsReflectPkg(s.Pkg) {
+	// Check that first result type is "reflect.Method". Note that we have to check sym name and sym package
+	// separately, as we can't check for exact string "reflect.Method" reliably (e.g., see #19028 and #38515).
+	if s := t.Results().Field(0).Type.Sym(); s != nil && s.Name == "Method" && types.IsReflectPkg(s.Pkg) {
 		ir.CurFunc.SetReflectMethod(true)
 		// The LSym is initialized at this point. We need to set the attribute on the LSym.
 		ir.CurFunc.LSym.Set(obj.AttrReflectMethod, true)
diff --git a/src/cmd/compile/internal/walk/order.go b/src/cmd/compile/internal/walk/order.go
index b733d3a29f67cc18a924462a0a4c8983a8e8bf7b..6e336f565cf73735c0b46a24eba826aca932d859 100644
--- a/src/cmd/compile/internal/walk/order.go
+++ b/src/cmd/compile/internal/walk/order.go
@@ -7,10 +7,8 @@ package walk
 import (
 	"fmt"
 	"go/constant"
-	"internal/buildcfg"
 
 	"cmd/compile/internal/base"
-	"cmd/compile/internal/escape"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/staticinit"
@@ -53,7 +51,7 @@ import (
 type orderState struct {
 	out  []ir.Node             // list of generated statements
 	temp []*ir.Name            // stack of temporary variables
-	free map[string][]*ir.Name // free list of unused temporaries, by type.LongString().
+	free map[string][]*ir.Name // free list of unused temporaries, by type.LinkString().
 	edit func(ir.Node) ir.Node // cached closure of o.exprNoLHS
 }
 
@@ -78,20 +76,14 @@ func (o *orderState) append(stmt ir.Node) {
 // If clear is true, newTemp emits code to zero the temporary.
 func (o *orderState) newTemp(t *types.Type, clear bool) *ir.Name {
 	var v *ir.Name
-	// Note: LongString is close to the type equality we want,
-	// but not exactly. We still need to double-check with types.Identical.
-	key := t.LongString()
-	a := o.free[key]
-	for i, n := range a {
-		if types.Identical(t, n.Type()) {
-			v = a[i]
-			a[i] = a[len(a)-1]
-			a = a[:len(a)-1]
-			o.free[key] = a
-			break
+	key := t.LinkString()
+	if a := o.free[key]; len(a) > 0 {
+		v = a[len(a)-1]
+		if !types.Identical(t, v.Type()) {
+			base.Fatalf("expected %L to have type %v", v, t)
 		}
-	}
-	if v == nil {
+		o.free[key] = a[:len(a)-1]
+	} else {
 		v = typecheck.Temp(t)
 	}
 	if clear {
@@ -372,7 +364,7 @@ func (o *orderState) markTemp() ordermarker {
 // which must have been returned by markTemp.
 func (o *orderState) popTemp(mark ordermarker) {
 	for _, n := range o.temp[mark:] {
-		key := n.Type().LongString()
+		key := n.Type().LinkString()
 		o.free[key] = append(o.free[key], n)
 	}
 	o.temp = o.temp[:mark]
@@ -514,15 +506,18 @@ func (o *orderState) init(n ir.Node) {
 }
 
 // call orders the call expression n.
-// n.Op is OCALLMETH/OCALLFUNC/OCALLINTER or a builtin like OCOPY.
+// n.Op is OCALLFUNC/OCALLINTER or a builtin like OCOPY.
 func (o *orderState) call(nn ir.Node) {
 	if len(nn.Init()) > 0 {
 		// Caller should have already called o.init(nn).
 		base.Fatalf("%v with unexpected ninit", nn.Op())
 	}
+	if nn.Op() == ir.OCALLMETH {
+		base.FatalfAt(nn.Pos(), "OCALLMETH missed by typecheck")
+	}
 
 	// Builtin functions.
-	if nn.Op() != ir.OCALLFUNC && nn.Op() != ir.OCALLMETH && nn.Op() != ir.OCALLINTER {
+	if nn.Op() != ir.OCALLFUNC && nn.Op() != ir.OCALLINTER {
 		switch n := nn.(type) {
 		default:
 			base.Fatalf("unexpected call: %+v", n)
@@ -554,39 +549,6 @@ func (o *orderState) call(nn ir.Node) {
 
 	n.X = o.expr(n.X, nil)
 	o.exprList(n.Args)
-
-	if n.Op() == ir.OCALLINTER {
-		return
-	}
-	keepAlive := func(arg ir.Node) {
-		// If the argument is really a pointer being converted to uintptr,
-		// arrange for the pointer to be kept alive until the call returns,
-		// by copying it into a temp and marking that temp
-		// still alive when we pop the temp stack.
-		if arg.Op() == ir.OCONVNOP {
-			arg := arg.(*ir.ConvExpr)
-			if arg.X.Type().IsUnsafePtr() {
-				x := o.copyExpr(arg.X)
-				arg.X = x
-				x.SetAddrtaken(true) // ensure SSA keeps the x variable
-				n.KeepAlive = append(n.KeepAlive, x)
-			}
-		}
-	}
-
-	// Check for "unsafe-uintptr" tag provided by escape analysis.
-	for i, param := range n.X.Type().Params().FieldSlice() {
-		if param.Note == escape.UnsafeUintptrNote || param.Note == escape.UintptrEscapesNote {
-			if arg := n.Args[i]; arg.Op() == ir.OSLICELIT {
-				arg := arg.(*ir.CompLitExpr)
-				for _, elt := range arg.List {
-					keepAlive(elt)
-				}
-			} else {
-				keepAlive(arg)
-			}
-		}
-	}
 }
 
 // mapAssign appends n to o.out.
@@ -693,9 +655,20 @@ func (o *orderState) stmt(n ir.Node) {
 		n := n.(*ir.AssignListStmt)
 		t := o.markTemp()
 		o.exprList(n.Lhs)
-		o.init(n.Rhs[0])
-		o.call(n.Rhs[0])
-		o.as2func(n)
+		call := n.Rhs[0]
+		o.init(call)
+		if ic, ok := call.(*ir.InlinedCallExpr); ok {
+			o.stmtList(ic.Body)
+
+			n.SetOp(ir.OAS2)
+			n.Rhs = ic.ReturnVars
+
+			o.exprList(n.Rhs)
+			o.out = append(o.out, n)
+		} else {
+			o.call(call)
+			o.as2func(n)
+		}
 		o.cleanTemp(t)
 
 	// Special: use temporary variables to hold result,
@@ -713,6 +686,10 @@ func (o *orderState) stmt(n ir.Node) {
 		case ir.ODOTTYPE2:
 			r := r.(*ir.TypeAssertExpr)
 			r.X = o.expr(r.X, nil)
+		case ir.ODYNAMICDOTTYPE2:
+			r := r.(*ir.DynamicTypeAssertExpr)
+			r.X = o.expr(r.X, nil)
+			r.T = o.expr(r.T, nil)
 		case ir.ORECV:
 			r := r.(*ir.UnaryExpr)
 			r.X = o.expr(r.X, nil)
@@ -748,14 +725,25 @@ func (o *orderState) stmt(n ir.Node) {
 		o.out = append(o.out, n)
 
 	// Special: handle call arguments.
-	case ir.OCALLFUNC, ir.OCALLINTER, ir.OCALLMETH:
+	case ir.OCALLFUNC, ir.OCALLINTER:
 		n := n.(*ir.CallExpr)
 		t := o.markTemp()
 		o.call(n)
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
-	case ir.OCLOSE, ir.ORECV:
+	case ir.OINLCALL:
+		n := n.(*ir.InlinedCallExpr)
+		o.stmtList(n.Body)
+
+		// discard results; double-check for no side effects
+		for _, result := range n.ReturnVars {
+			if staticinit.AnySideEffects(result) {
+				base.FatalfAt(result.Pos(), "inlined call result has side effects: %v", result)
+			}
+		}
+
+	case ir.OCHECKNIL, ir.OCLOSE, ir.OPANIC, ir.ORECV:
 		n := n.(*ir.UnaryExpr)
 		t := o.markTemp()
 		n.X = o.expr(n.X, nil)
@@ -770,10 +758,10 @@ func (o *orderState) stmt(n ir.Node) {
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
-	case ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+	case ir.OPRINT, ir.OPRINTN, ir.ORECOVERFP:
 		n := n.(*ir.CallExpr)
 		t := o.markTemp()
-		o.exprList(n.Args)
+		o.call(n)
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
@@ -783,16 +771,6 @@ func (o *orderState) stmt(n ir.Node) {
 		t := o.markTemp()
 		o.init(n.Call)
 		o.call(n.Call)
-		if n.Call.Op() == ir.ORECOVER {
-			// Special handling of "defer recover()". We need to evaluate the FP
-			// argument before wrapping.
-			var init ir.Nodes
-			n.Call = walkRecover(n.Call.(*ir.CallExpr), &init)
-			o.stmtList(init)
-		}
-		if buildcfg.Experiment.RegabiDefer {
-			o.wrapGoDefer(n)
-		}
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
@@ -830,16 +808,6 @@ func (o *orderState) stmt(n ir.Node) {
 		orderBlock(&n.Else, o.free)
 		o.out = append(o.out, n)
 
-	case ir.OPANIC:
-		n := n.(*ir.UnaryExpr)
-		t := o.markTemp()
-		n.X = o.expr(n.X, nil)
-		if !n.X.Type().IsEmptyInterface() {
-			base.FatalfAt(n.Pos(), "bad argument to panic: %L", n.X)
-		}
-		o.out = append(o.out, n)
-		o.cleanTemp(t)
-
 	case ir.ORANGE:
 		// n.Right is the expression being ranged over.
 		// order it, and then make a copy if we need one.
@@ -1192,23 +1160,26 @@ func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
 
 	// concrete type (not interface) argument might need an addressable
 	// temporary to pass to the runtime conversion routine.
-	case ir.OCONVIFACE:
+	case ir.OCONVIFACE, ir.OCONVIDATA:
 		n := n.(*ir.ConvExpr)
 		n.X = o.expr(n.X, nil)
 		if n.X.Type().IsInterface() {
 			return n
 		}
-		if _, _, needsaddr := convFuncName(n.X.Type(), n.Type()); needsaddr || isStaticCompositeLiteral(n.X) {
+		if _, _, needsaddr := dataWordFuncName(n.X.Type()); needsaddr || isStaticCompositeLiteral(n.X) {
 			// Need a temp if we need to pass the address to the conversion function.
 			// We also process static composite literal node here, making a named static global
-			// whose address we can put directly in an interface (see OCONVIFACE case in walk).
+			// whose address we can put directly in an interface (see OCONVIFACE/OCONVIDATA case in walk).
 			n.X = o.addrTemp(n.X)
 		}
 		return n
 
 	case ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
-		if n.Type().IsKind(types.TUNSAFEPTR) && n.X.Type().IsKind(types.TUINTPTR) && (n.X.Op() == ir.OCALLFUNC || n.X.Op() == ir.OCALLINTER || n.X.Op() == ir.OCALLMETH) {
+		if n.X.Op() == ir.OCALLMETH {
+			base.FatalfAt(n.X.Pos(), "OCALLMETH missed by typecheck")
+		}
+		if n.Type().IsKind(types.TUNSAFEPTR) && n.X.Type().IsKind(types.TUINTPTR) && (n.X.Op() == ir.OCALLFUNC || n.X.Op() == ir.OCALLINTER) {
 			call := n.X.(*ir.CallExpr)
 			// When reordering unsafe.Pointer(f()) into a separate
 			// statement, the conversion and function call must stay
@@ -1261,9 +1232,12 @@ func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
 		o.out = append(o.out, nif)
 		return r
 
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+		panic("unreachable")
+
 	case ir.OCALLFUNC,
 		ir.OCALLINTER,
-		ir.OCALLMETH,
 		ir.OCAP,
 		ir.OCOMPLEX,
 		ir.OCOPY,
@@ -1275,7 +1249,7 @@ func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
 		ir.OMAKESLICECOPY,
 		ir.ONEW,
 		ir.OREAL,
-		ir.ORECOVER,
+		ir.ORECOVERFP,
 		ir.OSTR2BYTES,
 		ir.OSTR2BYTESTMP,
 		ir.OSTR2RUNES:
@@ -1293,6 +1267,11 @@ func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
 		}
 		return n
 
+	case ir.OINLCALL:
+		n := n.(*ir.InlinedCallExpr)
+		o.stmtList(n.Body)
+		return n.SingleResult()
+
 	case ir.OAPPEND:
 		// Check for append(x, make([]T, y)...) .
 		n := n.(*ir.CallExpr)
@@ -1327,11 +1306,11 @@ func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
 		}
 		return n
 
-	case ir.OCALLPART:
+	case ir.OMETHVALUE:
 		n := n.(*ir.SelectorExpr)
 		n.X = o.expr(n.X, nil)
 		if n.Transient() {
-			t := typecheck.PartialCallType(n)
+			t := typecheck.MethodValueType(n)
 			n.Prealloc = o.newTemp(t, false)
 		}
 		return n
@@ -1498,313 +1477,6 @@ func (o *orderState) as2ok(n *ir.AssignListStmt) {
 	o.stmt(typecheck.Stmt(as))
 }
 
-var wrapGoDefer_prgen int
-
-// wrapGoDefer wraps the target of a "go" or "defer" statement with a
-// new "function with no arguments" closure. Specifically, it converts
-//
-//   defer f(x, y)
-//
-// to
-//
-//   x1, y1 := x, y
-//   defer func() { f(x1, y1) }()
-//
-// This is primarily to enable a quicker bringup of defers under the
-// new register ABI; by doing this conversion, we can simplify the
-// code in the runtime that invokes defers on the panic path.
-func (o *orderState) wrapGoDefer(n *ir.GoDeferStmt) {
-	call := n.Call
-
-	var callX ir.Node        // thing being called
-	var callArgs []ir.Node   // call arguments
-	var keepAlive []*ir.Name // KeepAlive list from call, if present
-
-	// A helper to recreate the call within the closure.
-	var mkNewCall func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node
-
-	// Defer calls come in many shapes and sizes; not all of them
-	// are ir.CallExpr's. Examine the type to see what we're dealing with.
-	switch x := call.(type) {
-	case *ir.CallExpr:
-		callX = x.X
-		callArgs = x.Args
-		keepAlive = x.KeepAlive
-		mkNewCall = func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node {
-			newcall := ir.NewCallExpr(pos, op, fun, args)
-			newcall.IsDDD = x.IsDDD
-			return ir.Node(newcall)
-		}
-	case *ir.UnaryExpr: // ex: OCLOSE
-		callArgs = []ir.Node{x.X}
-		mkNewCall = func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node {
-			if len(args) != 1 {
-				panic("internal error, expecting single arg")
-			}
-			return ir.Node(ir.NewUnaryExpr(pos, op, args[0]))
-		}
-	case *ir.BinaryExpr: // ex: OCOPY
-		callArgs = []ir.Node{x.X, x.Y}
-		mkNewCall = func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node {
-			if len(args) != 2 {
-				panic("internal error, expecting two args")
-			}
-			return ir.Node(ir.NewBinaryExpr(pos, op, args[0], args[1]))
-		}
-	default:
-		panic("unhandled op")
-	}
-
-	// No need to wrap if called func has no args, no receiver, and no results.
-	// However in the case of "defer func() { ... }()" we need to
-	// protect against the possibility of directClosureCall rewriting
-	// things so that the call does have arguments.
-	//
-	// Do wrap method calls (OCALLMETH, OCALLINTER), because it has
-	// a receiver.
-	//
-	// Also do wrap builtin functions, because they may be expanded to
-	// calls with arguments (e.g. ORECOVER).
-	//
-	// TODO: maybe not wrap if the called function has no arguments and
-	// only in-register results?
-	if len(callArgs) == 0 && call.Op() == ir.OCALLFUNC && callX.Type().NumResults() == 0 {
-		if c, ok := call.(*ir.CallExpr); ok && callX != nil && callX.Op() == ir.OCLOSURE {
-			cloFunc := callX.(*ir.ClosureExpr).Func
-			cloFunc.SetClosureCalled(false)
-			c.PreserveClosure = true
-		}
-		return
-	}
-
-	if c, ok := call.(*ir.CallExpr); ok {
-		// To simplify things, turn f(a, b, []T{c, d, e}...) back
-		// into f(a, b, c, d, e) -- when the final call is run through the
-		// type checker below, it will rebuild the proper slice literal.
-		undoVariadic(c)
-		callX = c.X
-		callArgs = c.Args
-	}
-
-	// This is set to true if the closure we're generating escapes
-	// (needs heap allocation).
-	cloEscapes := func() bool {
-		if n.Op() == ir.OGO {
-			// For "go", assume that all closures escape.
-			return true
-		}
-		// For defer, just use whatever result escape analysis
-		// has determined for the defer.
-		return n.Esc() != ir.EscNever
-	}()
-
-	// A helper for making a copy of an argument. Note that it is
-	// not safe to use o.copyExpr(arg) if we're putting a
-	// reference to the temp into the closure (as opposed to
-	// copying it in by value), since in the by-reference case we
-	// need a temporary whose lifetime extends to the end of the
-	// function (as opposed to being local to the current block or
-	// statement being ordered).
-	mkArgCopy := func(arg ir.Node) *ir.Name {
-		t := arg.Type()
-		byval := t.Size() <= 128 || cloEscapes
-		var argCopy *ir.Name
-		if byval {
-			argCopy = o.copyExpr(arg)
-		} else {
-			argCopy = typecheck.Temp(t)
-			o.append(ir.NewAssignStmt(base.Pos, argCopy, arg))
-		}
-		// The value of 128 below is meant to be consistent with code
-		// in escape analysis that picks byval/byaddr based on size.
-		argCopy.SetByval(byval)
-		return argCopy
-	}
-
-	// getUnsafeArg looks for an unsafe.Pointer arg that has been
-	// previously captured into the call's keepalive list, returning
-	// the name node for it if found.
-	getUnsafeArg := func(arg ir.Node) *ir.Name {
-		// Look for uintptr(unsafe.Pointer(name))
-		if arg.Op() != ir.OCONVNOP {
-			return nil
-		}
-		if !arg.Type().IsUintptr() {
-			return nil
-		}
-		if !arg.(*ir.ConvExpr).X.Type().IsUnsafePtr() {
-			return nil
-		}
-		arg = arg.(*ir.ConvExpr).X
-		argname, ok := arg.(*ir.Name)
-		if !ok {
-			return nil
-		}
-		for i := range keepAlive {
-			if argname == keepAlive[i] {
-				return argname
-			}
-		}
-		return nil
-	}
-
-	// Copy the arguments to the function into temps.
-	//
-	// For calls with uintptr(unsafe.Pointer(...)) args that are being
-	// kept alive (see code in (*orderState).call that does this), use
-	// the existing arg copy instead of creating a new copy.
-	unsafeArgs := make([]*ir.Name, len(callArgs))
-	origArgs := callArgs
-	var newNames []*ir.Name
-	for i := range callArgs {
-		arg := callArgs[i]
-		var argname *ir.Name
-		unsafeArgName := getUnsafeArg(arg)
-		if unsafeArgName != nil {
-			// arg has been copied already, use keepalive copy
-			argname = unsafeArgName
-			unsafeArgs[i] = unsafeArgName
-		} else {
-			argname = mkArgCopy(arg)
-		}
-		newNames = append(newNames, argname)
-	}
-
-	// Deal with cases where the function expression (what we're
-	// calling) is not a simple function symbol.
-	var fnExpr *ir.Name
-	var methSelectorExpr *ir.SelectorExpr
-	if callX != nil {
-		switch {
-		case callX.Op() == ir.ODOTMETH || callX.Op() == ir.ODOTINTER:
-			// Handle defer of a method call, e.g. "defer v.MyMethod(x, y)"
-			n := callX.(*ir.SelectorExpr)
-			n.X = mkArgCopy(n.X)
-			methSelectorExpr = n
-			if callX.Op() == ir.ODOTINTER {
-				// Currently for "defer i.M()" if i is nil it panics at the
-				// point of defer statement, not when deferred function is called.
-				// (I think there is an issue discussing what is the intended
-				// behavior but I cannot find it.)
-				// We need to do the nil check outside of the wrapper.
-				tab := typecheck.Expr(ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X))
-				c := ir.NewUnaryExpr(n.Pos(), ir.OCHECKNIL, tab)
-				c.SetTypecheck(1)
-				o.append(c)
-			}
-		case !(callX.Op() == ir.ONAME && callX.(*ir.Name).Class == ir.PFUNC):
-			// Deal with "defer returnsafunc()(x, y)" (for
-			// example) by copying the callee expression.
-			fnExpr = mkArgCopy(callX)
-			if callX.Op() == ir.OCLOSURE {
-				// For "defer func(...)", in addition to copying the
-				// closure into a temp, mark it as no longer directly
-				// called.
-				callX.(*ir.ClosureExpr).Func.SetClosureCalled(false)
-			}
-		}
-	}
-
-	// Create a new no-argument function that we'll hand off to defer.
-	var noFuncArgs []*ir.Field
-	noargst := ir.NewFuncType(base.Pos, nil, noFuncArgs, nil)
-	wrapGoDefer_prgen++
-	outerfn := ir.CurFunc
-	wrapname := fmt.Sprintf("%v·dwrap·%d", outerfn, wrapGoDefer_prgen)
-	sym := types.LocalPkg.Lookup(wrapname)
-	fn := typecheck.DeclFunc(sym, noargst)
-	fn.SetIsHiddenClosure(true)
-	fn.SetWrapper(true)
-
-	// helper for capturing reference to a var declared in an outer scope.
-	capName := func(pos src.XPos, fn *ir.Func, n *ir.Name) *ir.Name {
-		t := n.Type()
-		cv := ir.CaptureName(pos, fn, n)
-		cv.SetType(t)
-		return typecheck.Expr(cv).(*ir.Name)
-	}
-
-	// Call args (x1, y1) need to be captured as part of the newly
-	// created closure.
-	newCallArgs := []ir.Node{}
-	for i := range newNames {
-		var arg ir.Node
-		arg = capName(callArgs[i].Pos(), fn, newNames[i])
-		if unsafeArgs[i] != nil {
-			arg = ir.NewConvExpr(arg.Pos(), origArgs[i].Op(), origArgs[i].Type(), arg)
-		}
-		newCallArgs = append(newCallArgs, arg)
-	}
-	// Also capture the function or method expression (if needed) into
-	// the closure.
-	if fnExpr != nil {
-		callX = capName(callX.Pos(), fn, fnExpr)
-	}
-	if methSelectorExpr != nil {
-		methSelectorExpr.X = capName(callX.Pos(), fn, methSelectorExpr.X.(*ir.Name))
-	}
-	ir.FinishCaptureNames(n.Pos(), outerfn, fn)
-
-	// This flags a builtin as opposed to a regular call.
-	irregular := (call.Op() != ir.OCALLFUNC &&
-		call.Op() != ir.OCALLMETH &&
-		call.Op() != ir.OCALLINTER)
-
-	// Construct new function body:  f(x1, y1)
-	op := ir.OCALL
-	if irregular {
-		op = call.Op()
-	}
-	newcall := mkNewCall(call.Pos(), op, callX, newCallArgs)
-
-	// Type-check the result.
-	if !irregular {
-		typecheck.Call(newcall.(*ir.CallExpr))
-	} else {
-		typecheck.Stmt(newcall)
-	}
-
-	// Finalize body, register function on the main decls list.
-	fn.Body = []ir.Node{newcall}
-	typecheck.FinishFuncBody()
-	typecheck.Func(fn)
-	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
-
-	// Create closure expr
-	clo := ir.NewClosureExpr(n.Pos(), fn)
-	fn.OClosure = clo
-	clo.SetType(fn.Type())
-
-	// Set escape properties for closure.
-	if n.Op() == ir.OGO {
-		// For "go", assume that the closure is going to escape
-		// (with an exception for the runtime, which doesn't
-		// permit heap-allocated closures).
-		if base.Ctxt.Pkgpath != "runtime" {
-			clo.SetEsc(ir.EscHeap)
-		}
-	} else {
-		// For defer, just use whatever result escape analysis
-		// has determined for the defer.
-		if n.Esc() == ir.EscNever {
-			clo.SetTransient(true)
-			clo.SetEsc(ir.EscNone)
-		}
-	}
-
-	// Create new top level call to closure over argless function.
-	topcall := ir.NewCallExpr(n.Pos(), ir.OCALL, clo, []ir.Node{})
-	typecheck.Call(topcall)
-
-	// Tag the call to insure that directClosureCall doesn't undo our work.
-	topcall.PreserveClosure = true
-
-	fn.SetClosureCalled(false)
-
-	// Finally, point the defer statement at the newly generated call.
-	n.Call = topcall
-}
-
 // isFuncPCIntrinsic returns whether n is a direct call of internal/abi.FuncPCABIxxx functions.
 func isFuncPCIntrinsic(n *ir.CallExpr) bool {
 	if n.Op() != ir.OCALLFUNC || n.X.Op() != ir.ONAME {
diff --git a/src/cmd/compile/internal/walk/stmt.go b/src/cmd/compile/internal/walk/stmt.go
index 0bf76680c4626546f00fee0890a4418a157c77b5..4581bca3dfe42da847008085e9d62f9944305171 100644
--- a/src/cmd/compile/internal/walk/stmt.go
+++ b/src/cmd/compile/internal/walk/stmt.go
@@ -7,7 +7,6 @@ package walk
 import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
-	"cmd/compile/internal/typecheck"
 )
 
 // The result of walkStmt MUST be assigned back to n, e.g.
@@ -41,7 +40,6 @@ func walkStmt(n ir.Node) ir.Node {
 		ir.OAS2MAPR,
 		ir.OCLOSE,
 		ir.OCOPY,
-		ir.OCALLMETH,
 		ir.OCALLINTER,
 		ir.OCALL,
 		ir.OCALLFUNC,
@@ -50,7 +48,7 @@ func walkStmt(n ir.Node) ir.Node {
 		ir.OPRINT,
 		ir.OPRINTN,
 		ir.OPANIC,
-		ir.ORECOVER,
+		ir.ORECOVERFP,
 		ir.OGETG:
 		if n.Typecheck() == 0 {
 			base.Fatalf("missing typecheck: %+v", n)
@@ -187,33 +185,28 @@ func walkFor(n *ir.ForStmt) ir.Node {
 	return n
 }
 
+// validGoDeferCall reports whether call is a valid call to appear in
+// a go or defer statement; that is, whether it's a regular function
+// call without arguments or results.
+func validGoDeferCall(call ir.Node) bool {
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC && len(call.KeepAlive) == 0 {
+		sig := call.X.Type()
+		return sig.NumParams()+sig.NumResults() == 0
+	}
+	return false
+}
+
 // walkGoDefer walks an OGO or ODEFER node.
 func walkGoDefer(n *ir.GoDeferStmt) ir.Node {
-	var init ir.Nodes
-	switch call := n.Call; call.Op() {
-	case ir.OPRINT, ir.OPRINTN:
-		call := call.(*ir.CallExpr)
-		n.Call = wrapCall(call, &init)
-
-	case ir.ODELETE:
-		call := call.(*ir.CallExpr)
-		n.Call = wrapCall(call, &init)
+	if !validGoDeferCall(n.Call) {
+		base.FatalfAt(n.Pos(), "invalid %v call: %v", n.Op(), n.Call)
+	}
 
-	case ir.OCOPY:
-		call := call.(*ir.BinaryExpr)
-		n.Call = walkCopy(call, &init, true)
+	var init ir.Nodes
 
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
-		call := call.(*ir.CallExpr)
-		if len(call.KeepAlive) > 0 {
-			n.Call = wrapCall(call, &init)
-		} else {
-			n.Call = walkExpr(call, &init)
-		}
+	call := n.Call.(*ir.CallExpr)
+	call.X = walkExpr(call.X, &init)
 
-	default:
-		n.Call = walkExpr(call, &init)
-	}
 	if len(init) > 0 {
 		init.Append(n)
 		return ir.NewBlockStmt(n.Pos(), init)
@@ -228,110 +221,3 @@ func walkIf(n *ir.IfStmt) ir.Node {
 	walkStmtList(n.Else)
 	return n
 }
-
-// Rewrite
-//	go builtin(x, y, z)
-// into
-//	go func(a1, a2, a3) {
-//		builtin(a1, a2, a3)
-//	}(x, y, z)
-// for print, println, and delete.
-//
-// Rewrite
-//	go f(x, y, uintptr(unsafe.Pointer(z)))
-// into
-//	go func(a1, a2, a3) {
-//		f(a1, a2, uintptr(a3))
-//	}(x, y, unsafe.Pointer(z))
-// for function contains unsafe-uintptr arguments.
-
-var wrapCall_prgen int
-
-// The result of wrapCall MUST be assigned back to n, e.g.
-// 	n.Left = wrapCall(n.Left, init)
-func wrapCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
-	if len(n.Init()) != 0 {
-		walkStmtList(n.Init())
-		init.Append(ir.TakeInit(n)...)
-	}
-
-	isBuiltinCall := n.Op() != ir.OCALLFUNC && n.Op() != ir.OCALLMETH && n.Op() != ir.OCALLINTER
-
-	// Turn f(a, b, []T{c, d, e}...) back into f(a, b, c, d, e).
-	if !isBuiltinCall && n.IsDDD {
-		undoVariadic(n)
-	}
-
-	wrapArgs := n.Args
-	// If there's a receiver argument, it needs to be passed through the wrapper too.
-	if n.Op() == ir.OCALLMETH || n.Op() == ir.OCALLINTER {
-		recv := n.X.(*ir.SelectorExpr).X
-		wrapArgs = append([]ir.Node{recv}, wrapArgs...)
-	}
-
-	// origArgs keeps track of what argument is uintptr-unsafe/unsafe-uintptr conversion.
-	origArgs := make([]ir.Node, len(wrapArgs))
-	var funcArgs []*ir.Field
-	for i, arg := range wrapArgs {
-		s := typecheck.LookupNum("a", i)
-		if !isBuiltinCall && arg.Op() == ir.OCONVNOP && arg.Type().IsUintptr() && arg.(*ir.ConvExpr).X.Type().IsUnsafePtr() {
-			origArgs[i] = arg
-			arg = arg.(*ir.ConvExpr).X
-			wrapArgs[i] = arg
-		}
-		funcArgs = append(funcArgs, ir.NewField(base.Pos, s, nil, arg.Type()))
-	}
-	t := ir.NewFuncType(base.Pos, nil, funcArgs, nil)
-
-	wrapCall_prgen++
-	sym := typecheck.LookupNum("wrap·", wrapCall_prgen)
-	fn := typecheck.DeclFunc(sym, t)
-
-	args := ir.ParamNames(t.Type())
-	for i, origArg := range origArgs {
-		if origArg == nil {
-			continue
-		}
-		args[i] = ir.NewConvExpr(base.Pos, origArg.Op(), origArg.Type(), args[i])
-	}
-	if n.Op() == ir.OCALLMETH || n.Op() == ir.OCALLINTER {
-		// Move wrapped receiver argument back to its appropriate place.
-		recv := typecheck.Expr(args[0])
-		n.X.(*ir.SelectorExpr).X = recv
-		args = args[1:]
-	}
-	call := ir.NewCallExpr(base.Pos, n.Op(), n.X, args)
-	if !isBuiltinCall {
-		call.SetOp(ir.OCALL)
-		call.IsDDD = n.IsDDD
-	}
-	fn.Body = []ir.Node{call}
-
-	typecheck.FinishFuncBody()
-
-	typecheck.Func(fn)
-	typecheck.Stmts(fn.Body)
-	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
-
-	call = ir.NewCallExpr(base.Pos, ir.OCALL, fn.Nname, wrapArgs)
-	return walkExpr(typecheck.Stmt(call), init)
-}
-
-// undoVariadic turns a call to a variadic function of the form
-//
-//      f(a, b, []T{c, d, e}...)
-//
-// back into
-//
-//      f(a, b, c, d, e)
-//
-func undoVariadic(call *ir.CallExpr) {
-	if call.IsDDD {
-		last := len(call.Args) - 1
-		if va := call.Args[last]; va.Op() == ir.OSLICELIT {
-			va := va.(*ir.CompLitExpr)
-			call.Args = append(call.Args[:last], va.List...)
-			call.IsDDD = false
-		}
-	}
-}
diff --git a/src/cmd/compile/internal/walk/switch.go b/src/cmd/compile/internal/walk/switch.go
index 162de018f637ef5a329d8a31cab1f64cc7906b54..3705c5b19265d9a4f5a4c5cf9d36cfba3cf94ac5 100644
--- a/src/cmd/compile/internal/walk/switch.go
+++ b/src/cmd/compile/internal/walk/switch.go
@@ -360,10 +360,10 @@ func walkSwitchType(sw *ir.SwitchStmt) {
 			}
 
 			if singleType != nil && singleType.IsInterface() {
-				s.Add(ncase.Pos(), n1.Type(), caseVar, jmp)
+				s.Add(ncase.Pos(), n1, caseVar, jmp)
 				caseVarInitialized = true
 			} else {
-				s.Add(ncase.Pos(), n1.Type(), nil, jmp)
+				s.Add(ncase.Pos(), n1, nil, jmp)
 			}
 		}
 
@@ -377,6 +377,17 @@ func walkSwitchType(sw *ir.SwitchStmt) {
 				}
 				val = ifaceData(ncase.Pos(), s.facename, singleType)
 			}
+			if len(ncase.List) == 1 && ncase.List[0].Op() == ir.ODYNAMICTYPE {
+				dt := ncase.List[0].(*ir.DynamicType)
+				x := ir.NewDynamicTypeAssertExpr(ncase.Pos(), ir.ODYNAMICDOTTYPE, val, dt.X)
+				if dt.ITab != nil {
+					// TODO: make ITab a separate field in DynamicTypeAssertExpr?
+					x.T = dt.ITab
+				}
+				x.SetType(caseVar.Type())
+				x.SetTypecheck(1)
+				val = x
+			}
 			l := []ir.Node{
 				ir.NewDecl(ncase.Pos(), ir.ODCL, caseVar),
 				ir.NewAssignStmt(ncase.Pos(), caseVar, val),
@@ -446,7 +457,8 @@ type typeClause struct {
 	body ir.Nodes
 }
 
-func (s *typeSwitch) Add(pos src.XPos, typ *types.Type, caseVar *ir.Name, jmp ir.Node) {
+func (s *typeSwitch) Add(pos src.XPos, n1 ir.Node, caseVar *ir.Name, jmp ir.Node) {
+	typ := n1.Type()
 	var body ir.Nodes
 	if caseVar != nil {
 		l := []ir.Node{
@@ -462,9 +474,25 @@ func (s *typeSwitch) Add(pos src.XPos, typ *types.Type, caseVar *ir.Name, jmp ir
 	// cv, ok = iface.(type)
 	as := ir.NewAssignListStmt(pos, ir.OAS2, nil, nil)
 	as.Lhs = []ir.Node{caseVar, s.okname} // cv, ok =
-	dot := ir.NewTypeAssertExpr(pos, s.facename, nil)
-	dot.SetType(typ) // iface.(type)
-	as.Rhs = []ir.Node{dot}
+	switch n1.Op() {
+	case ir.OTYPE:
+		// Static type assertion (non-generic)
+		dot := ir.NewTypeAssertExpr(pos, s.facename, nil)
+		dot.SetType(typ) // iface.(type)
+		as.Rhs = []ir.Node{dot}
+	case ir.ODYNAMICTYPE:
+		// Dynamic type assertion (generic)
+		dt := n1.(*ir.DynamicType)
+		dot := ir.NewDynamicTypeAssertExpr(pos, ir.ODYNAMICDOTTYPE, s.facename, dt.X)
+		if dt.ITab != nil {
+			dot.T = dt.ITab
+		}
+		dot.SetType(typ)
+		dot.SetTypecheck(1)
+		as.Rhs = []ir.Node{dot}
+	default:
+		base.Fatalf("unhandled type case %s", n1.Op())
+	}
 	appendWalkStmt(&body, as)
 
 	// if ok { goto label }
@@ -473,9 +501,10 @@ func (s *typeSwitch) Add(pos src.XPos, typ *types.Type, caseVar *ir.Name, jmp ir
 	nif.Body = []ir.Node{jmp}
 	body.Append(nif)
 
-	if !typ.IsInterface() {
+	if n1.Op() == ir.OTYPE && !typ.IsInterface() {
+		// Defer static, noninterface cases so they can be binary searched by hash.
 		s.clauses = append(s.clauses, typeClause{
-			hash: types.TypeHash(typ),
+			hash: types.TypeHash(n1.Type()),
 			body: body,
 		})
 		return
diff --git a/src/cmd/compile/internal/walk/walk.go b/src/cmd/compile/internal/walk/walk.go
index 26da6e314574431ef88187128097d4c644f00c1d..a9bbc9a54f66708abbf1c84bfa4c12ac12df1b21 100644
--- a/src/cmd/compile/internal/walk/walk.go
+++ b/src/cmd/compile/internal/walk/walk.go
@@ -113,8 +113,7 @@ func vmkcall(fn ir.Node, t *types.Type, init *ir.Nodes, va []ir.Node) *ir.CallEx
 		base.Fatalf("vmkcall %v needs %v args got %v", fn, n, len(va))
 	}
 
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, va)
-	typecheck.Call(call)
+	call := typecheck.Call(base.Pos, fn, va, false).(*ir.CallExpr)
 	call.SetType(t)
 	return walkExpr(call, init).(*ir.CallExpr)
 }
@@ -308,12 +307,12 @@ func mayCall(n ir.Node) bool {
 		default:
 			base.FatalfAt(n.Pos(), "mayCall %+v", n)
 
-		case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER,
+		case ir.OCALLFUNC, ir.OCALLINTER,
 			ir.OUNSAFEADD, ir.OUNSAFESLICE:
 			return true
 
 		case ir.OINDEX, ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR, ir.OSLICESTR,
-			ir.ODEREF, ir.ODOTPTR, ir.ODOTTYPE, ir.ODIV, ir.OMOD, ir.OSLICE2ARRPTR:
+			ir.ODEREF, ir.ODOTPTR, ir.ODOTTYPE, ir.ODYNAMICDOTTYPE, ir.ODIV, ir.OMOD, ir.OSLICE2ARRPTR:
 			// These ops might panic, make sure they are done
 			// before we start marshaling args for a call. See issue 16760.
 			return true
@@ -343,7 +342,7 @@ func mayCall(n ir.Node) bool {
 			ir.OCAP, ir.OIMAG, ir.OLEN, ir.OREAL,
 			ir.OCONVNOP, ir.ODOT,
 			ir.OCFUNC, ir.OIDATA, ir.OITAB, ir.OSPTR,
-			ir.OBYTES2STRTMP, ir.OGETG, ir.OSLICEHEADER:
+			ir.OBYTES2STRTMP, ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP, ir.OSLICEHEADER:
 			// ok: operations that don't require function calls.
 			// Expand as needed.
 		}
diff --git a/src/cmd/compile/internal/wasm/ssa.go b/src/cmd/compile/internal/wasm/ssa.go
index 31b09016eb98296a3838bc39125dbb3f4f73a101..0b2ca3fdbb83af3573a2af995d795ffd7bd80718 100644
--- a/src/cmd/compile/internal/wasm/ssa.go
+++ b/src/cmd/compile/internal/wasm/ssa.go
@@ -24,7 +24,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zeroRange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
@@ -126,7 +125,11 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 	case ssa.OpWasmLoweredStaticCall, ssa.OpWasmLoweredClosureCall, ssa.OpWasmLoweredInterCall:
 		s.PrepareCall(v)
 		if call, ok := v.Aux.(*ssa.AuxCall); ok && call.Fn == ir.Syms.Deferreturn {
-			// add a resume point before call to deferreturn so it can be called again via jmpdefer
+			// The runtime needs to inject jumps to
+			// deferreturn calls using the address in
+			// _func.deferreturn. Hence, the call to
+			// deferreturn must itself be a resumption
+			// point so it gets a target PC.
 			s.Prog(wasm.ARESUMEPOINT)
 		}
 		if v.Op == ssa.OpWasmLoweredClosureCall {
diff --git a/src/cmd/compile/internal/x86/galign.go b/src/cmd/compile/internal/x86/galign.go
index 00a20e429f1d6112cbf985e0b3c8706b187b0356..5565bd32c765b36debf7cde83eab4f3d2d8a71dd 100644
--- a/src/cmd/compile/internal/x86/galign.go
+++ b/src/cmd/compile/internal/x86/galign.go
@@ -34,7 +34,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 }
diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 1abb03bcc56b2a881df3b82fcd81481a28f173d1..33a329e48b71712564be4ba8f1ae67655940a09c 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -48,8 +48,6 @@ var (
 	exe              string
 	defaultcc        map[string]string
 	defaultcxx       map[string]string
-	defaultcflags    string
-	defaultldflags   string
 	defaultpkgconfig string
 	defaultldso      string
 
@@ -209,9 +207,6 @@ func xinit() {
 	defaultcc = compilerEnv("CC", cc)
 	defaultcxx = compilerEnv("CXX", cxx)
 
-	defaultcflags = os.Getenv("CFLAGS")
-	defaultldflags = os.Getenv("LDFLAGS")
-
 	b = os.Getenv("PKG_CONFIG")
 	if b == "" {
 		b = "pkg-config"
@@ -1263,14 +1258,19 @@ func cmdbootstrap() {
 	timelog("start", "dist bootstrap")
 	defer timelog("end", "dist bootstrap")
 
-	var noBanner bool
+	var noBanner, noClean bool
 	var debug bool
 	flag.BoolVar(&rebuildall, "a", rebuildall, "rebuild all")
 	flag.BoolVar(&debug, "d", debug, "enable debugging of bootstrap process")
 	flag.BoolVar(&noBanner, "no-banner", noBanner, "do not print banner")
+	flag.BoolVar(&noClean, "no-clean", noClean, "print deprecation warning")
 
 	xflagparse(0)
 
+	if noClean {
+		xprintf("warning: --no-clean is deprecated and has no effect; use 'go install std cmd' instead\n")
+	}
+
 	// Set GOPATH to an internal directory. We shouldn't actually
 	// need to store files here, since the toolchain won't
 	// depend on modules outside of vendor directories, but if
diff --git a/src/cmd/dist/test.go b/src/cmd/dist/test.go
index f40fa926dfd398b2c8adf239122358ef49e358cc..a104b5c8f3185ff1214f8f96562b16254ca8f5ba 100644
--- a/src/cmd/dist/test.go
+++ b/src/cmd/dist/test.go
@@ -491,19 +491,6 @@ func (t *tester) registerTests() {
 		})
 	}
 
-	// Test go/... cmd/gofmt with type parameters enabled.
-	if !t.compileOnly {
-		t.tests = append(t.tests, distTest{
-			name:    "tyepparams",
-			heading: "go/... and cmd/gofmt tests with tag typeparams",
-			fn: func(dt *distTest) error {
-				t.addCmd(dt, "src", t.goTest(), t.timeout(300), "-tags=typeparams", "go/...")
-				t.addCmd(dt, "src", t.goTest(), t.timeout(300), "-tags=typeparams", "cmd/gofmt")
-				return nil
-			},
-		})
-	}
-
 	if t.iOS() && !t.compileOnly {
 		t.tests = append(t.tests, distTest{
 			name:    "x509omitbundledroots",
diff --git a/src/cmd/go.mod b/src/cmd/go.mod
index b0a3f480458854a3f0b7c29a96ec2171a74636e6..b12d1991b9c740404eed89dd41e4977c811ea52a 100644
--- a/src/cmd/go.mod
+++ b/src/cmd/go.mod
@@ -1,6 +1,6 @@
 module cmd
 
-go 1.17
+go 1.18
 
 require (
 	github.com/google/pprof v0.0.0-20210506205249-923b5ab0fc1a
@@ -10,6 +10,6 @@ require (
 	golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61
 	golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 // indirect
 	golang.org/x/term v0.0.0-20210503060354-a79de5458b56
-	golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6
+	golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 )
diff --git a/src/cmd/go.sum b/src/cmd/go.sum
index bf237d40bcf4f511a3ade9f7bedcdfff3e018b9c..1db50ca3028a014cf3ae432d0406611fa4b63fb2 100644
--- a/src/cmd/go.sum
+++ b/src/cmd/go.sum
@@ -5,41 +5,18 @@ github.com/google/pprof v0.0.0-20210506205249-923b5ab0fc1a h1:jmAp/2PZAScNd62lTD
 github.com/google/pprof v0.0.0-20210506205249-923b5ab0fc1a/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639 h1:mV02weKRL81bEnm8A0HT1/CAelMQDBuQIfLw8n+d6xI=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
-github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 golang.org/x/arch v0.0.0-20210502124803-cbf565b21d1e h1:pv3V0NlNSh5Q6AX/StwGLBjcLS7UN4m4Gq+V+uSecqM=
 golang.org/x/arch v0.0.0-20210502124803-cbf565b21d1e/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e h1:8foAy0aoO5GkqCvAEJ4VC4P3zksTg4X4aJCDpZzmgQI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
-golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61 h1:gQY3CVezomIImcWCpxp6Mhj+fXCOZ+gD8/88326LVqw=
 golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 h1:yhBbb4IRs2HS9PPlAg6DMC6mUOKexJBNsLf4Z+6En1Q=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210503060354-a79de5458b56 h1:b8jxX3zqjpqb2LklXPzKSGJhzyxCOZSz8ncv8Nv+y7w=
 golang.org/x/term v0.0.0-20210503060354-a79de5458b56/go.mod h1:tfny5GFUkzUvx4ps4ajbZsCe5lw1metzhBm9T3x7oIY=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6 h1:er++nfKy5Irv8JPDfJ68QzoVKQ6MBF7cf5xC15O4Zy0=
-golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151 h1:jHjT6WuVKEMzjJgrS1+r1wk54oxwqumUnvtn0QZXyXE=
+golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=
diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index e0973acbf4569bdfd02f79f5ee0cd5fbbd1e96ae..425aa831d88b8ac3673d4893ff6897eef8d353ff 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -1503,7 +1503,8 @@
 // used. That subset is: 'atomic', 'bool', 'buildtags', 'errorsas',
 // 'ifaceassert', 'nilfunc', 'printf', and 'stringintconv'. You can see
 // the documentation for these and other vet tests via "go doc cmd/vet".
-// To disable the running of go vet, use the -vet=off flag.
+// To disable the running of go vet, use the -vet=off flag. To run all
+// checks, use the -vet=all flag.
 //
 // All test output and summary lines are printed to the go command's
 // standard output, even if the test printed them to its own standard
@@ -1544,16 +1545,16 @@
 // The rule for a match in the cache is that the run involves the same
 // test binary and the flags on the command line come entirely from a
 // restricted set of 'cacheable' test flags, defined as -benchtime, -cpu,
-// -list, -parallel, -run, -short, and -v. If a run of go test has any test
-// or non-test flags outside this set, the result is not cached. To
-// disable test caching, use any test flag or argument other than the
-// cacheable flags. The idiomatic way to disable test caching explicitly
-// is to use -count=1. Tests that open files within the package's source
-// root (usually $GOPATH) or that consult environment variables only
-// match future runs in which the files and environment variables are unchanged.
-// A cached test result is treated as executing in no time at all,
-// so a successful package test result will be cached and reused
-// regardless of -timeout setting.
+// -list, -parallel, -run, -short, -timeout, -failfast, and -v.
+// If a run of go test has any test or non-test flags outside this set,
+// the result is not cached. To disable test caching, use any test flag
+// or argument other than the cacheable flags. The idiomatic way to disable
+// test caching explicitly is to use -count=1. Tests that open files within
+// the package's source root (usually $GOPATH) or that consult environment
+// variables only match future runs in which the files and environment
+// variables are unchanged. A cached test result is treated as executing
+// in no time at all,so a successful package test result will be cached and
+// reused regardless of -timeout setting.
 //
 // In addition to the build flags, the flags handled by 'go test' itself are:
 //
@@ -2756,6 +2757,10 @@
 // 	-failfast
 // 	    Do not start new tests after the first test failure.
 //
+// 	-json
+// 	    Log verbose output and test results in JSON. This presents the
+// 	    same information as the -v flag in a machine-readable format.
+//
 // 	-list regexp
 // 	    List tests, benchmarks, or examples matching the regular expression.
 // 	    No tests, benchmarks or examples will be run. This will only
diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index 6ce276537babd88765937e1f7ec0f3c98cc5ac68..b13191f678ddb9f4ea8671768a800067185882e0 100644
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -806,7 +806,9 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 		"src/internal/abi",
 		"src/internal/bytealg",
 		"src/internal/cpu",
+		"src/internal/goarch",
 		"src/internal/goexperiment",
+		"src/internal/goos",
 		"src/math/bits",
 		"src/unsafe",
 		filepath.Join("pkg", runtime.GOOS+"_"+runtime.GOARCH),
diff --git a/src/cmd/go/internal/modcmd/vendor.go b/src/cmd/go/internal/modcmd/vendor.go
index a51ac21751adf340f61fbcf5e4b7f8f31508f742..1effcea1a01ce4d920f25cd060d410ea982aa8ef 100644
--- a/src/cmd/go/internal/modcmd/vendor.go
+++ b/src/cmd/go/internal/modcmd/vendor.go
@@ -243,7 +243,7 @@ func vendorPkg(vdir, pkg string) {
 	if err != nil {
 		if errors.As(err, &noGoError) {
 			return // No source files in this package are built. Skip embeds in ignored files.
-		} else if !errors.As(err, &multiplePackageError) { // multiplePackgeErrors are okay, but others are not.
+		} else if !errors.As(err, &multiplePackageError) { // multiplePackageErrors are OK, but others are not.
 			base.Fatalf("internal error: failed to find embedded files of %s: %v\n", pkg, err)
 		}
 	}
diff --git a/src/cmd/go/internal/modfetch/codehost/git.go b/src/cmd/go/internal/modfetch/codehost/git.go
index 4d4964edf447ebb7e963acd2c0defb74bb5957f6..a782de56ff95a9caa8a07d9076042e7dc2238b36 100644
--- a/src/cmd/go/internal/modfetch/codehost/git.go
+++ b/src/cmd/go/internal/modfetch/codehost/git.go
@@ -170,59 +170,63 @@ func (r *gitRepo) loadLocalTags() {
 }
 
 // loadRefs loads heads and tags references from the remote into the map r.refs.
-// Should only be called as r.refsOnce.Do(r.loadRefs).
-func (r *gitRepo) loadRefs() {
-	// The git protocol sends all known refs and ls-remote filters them on the client side,
-	// so we might as well record both heads and tags in one shot.
-	// Most of the time we only care about tags but sometimes we care about heads too.
-	out, gitErr := Run(r.dir, "git", "ls-remote", "-q", r.remote)
-	if gitErr != nil {
-		if rerr, ok := gitErr.(*RunError); ok {
-			if bytes.Contains(rerr.Stderr, []byte("fatal: could not read Username")) {
-				rerr.HelpText = "Confirm the import path was entered correctly.\nIf this is a private repository, see https://golang.org/doc/faq#git_https for additional information."
+// The result is cached in memory.
+func (r *gitRepo) loadRefs() (map[string]string, error) {
+	r.refsOnce.Do(func() {
+		// The git protocol sends all known refs and ls-remote filters them on the client side,
+		// so we might as well record both heads and tags in one shot.
+		// Most of the time we only care about tags but sometimes we care about heads too.
+		out, gitErr := Run(r.dir, "git", "ls-remote", "-q", r.remote)
+		if gitErr != nil {
+			if rerr, ok := gitErr.(*RunError); ok {
+				if bytes.Contains(rerr.Stderr, []byte("fatal: could not read Username")) {
+					rerr.HelpText = "Confirm the import path was entered correctly.\nIf this is a private repository, see https://golang.org/doc/faq#git_https for additional information."
+				}
 			}
-		}
 
-		// If the remote URL doesn't exist at all, ideally we should treat the whole
-		// repository as nonexistent by wrapping the error in a notExistError.
-		// For HTTP and HTTPS, that's easy to detect: we'll try to fetch the URL
-		// ourselves and see what code it serves.
-		if u, err := url.Parse(r.remoteURL); err == nil && (u.Scheme == "http" || u.Scheme == "https") {
-			if _, err := web.GetBytes(u); errors.Is(err, fs.ErrNotExist) {
-				gitErr = notExistError{gitErr}
+			// If the remote URL doesn't exist at all, ideally we should treat the whole
+			// repository as nonexistent by wrapping the error in a notExistError.
+			// For HTTP and HTTPS, that's easy to detect: we'll try to fetch the URL
+			// ourselves and see what code it serves.
+			if u, err := url.Parse(r.remoteURL); err == nil && (u.Scheme == "http" || u.Scheme == "https") {
+				if _, err := web.GetBytes(u); errors.Is(err, fs.ErrNotExist) {
+					gitErr = notExistError{gitErr}
+				}
 			}
-		}
 
-		r.refsErr = gitErr
-		return
-	}
-
-	r.refs = make(map[string]string)
-	for _, line := range strings.Split(string(out), "\n") {
-		f := strings.Fields(line)
-		if len(f) != 2 {
-			continue
+			r.refsErr = gitErr
+			return
 		}
-		if f[1] == "HEAD" || strings.HasPrefix(f[1], "refs/heads/") || strings.HasPrefix(f[1], "refs/tags/") {
-			r.refs[f[1]] = f[0]
+
+		refs := make(map[string]string)
+		for _, line := range strings.Split(string(out), "\n") {
+			f := strings.Fields(line)
+			if len(f) != 2 {
+				continue
+			}
+			if f[1] == "HEAD" || strings.HasPrefix(f[1], "refs/heads/") || strings.HasPrefix(f[1], "refs/tags/") {
+				refs[f[1]] = f[0]
+			}
 		}
-	}
-	for ref, hash := range r.refs {
-		if strings.HasSuffix(ref, "^{}") { // record unwrapped annotated tag as value of tag
-			r.refs[strings.TrimSuffix(ref, "^{}")] = hash
-			delete(r.refs, ref)
+		for ref, hash := range refs {
+			if strings.HasSuffix(ref, "^{}") { // record unwrapped annotated tag as value of tag
+				refs[strings.TrimSuffix(ref, "^{}")] = hash
+				delete(refs, ref)
+			}
 		}
-	}
+		r.refs = refs
+	})
+	return r.refs, r.refsErr
 }
 
 func (r *gitRepo) Tags(prefix string) ([]string, error) {
-	r.refsOnce.Do(r.loadRefs)
-	if r.refsErr != nil {
-		return nil, r.refsErr
+	refs, err := r.loadRefs()
+	if err != nil {
+		return nil, err
 	}
 
 	tags := []string{}
-	for ref := range r.refs {
+	for ref := range refs {
 		if !strings.HasPrefix(ref, "refs/tags/") {
 			continue
 		}
@@ -237,14 +241,14 @@ func (r *gitRepo) Tags(prefix string) ([]string, error) {
 }
 
 func (r *gitRepo) Latest() (*RevInfo, error) {
-	r.refsOnce.Do(r.loadRefs)
-	if r.refsErr != nil {
-		return nil, r.refsErr
+	refs, err := r.loadRefs()
+	if err != nil {
+		return nil, err
 	}
-	if r.refs["HEAD"] == "" {
+	if refs["HEAD"] == "" {
 		return nil, ErrNoCommits
 	}
-	return r.Stat(r.refs["HEAD"])
+	return r.Stat(refs["HEAD"])
 }
 
 // findRef finds some ref name for the given hash,
@@ -252,8 +256,11 @@ func (r *gitRepo) Latest() (*RevInfo, error) {
 // There may be multiple ref names for a given hash,
 // in which case this returns some name - it doesn't matter which.
 func (r *gitRepo) findRef(hash string) (ref string, ok bool) {
-	r.refsOnce.Do(r.loadRefs)
-	for ref, h := range r.refs {
+	refs, err := r.loadRefs()
+	if err != nil {
+		return "", false
+	}
+	for ref, h := range refs {
 		if h == hash {
 			return ref, true
 		}
@@ -295,29 +302,32 @@ func (r *gitRepo) stat(rev string) (*RevInfo, error) {
 	// Maybe rev is the name of a tag or branch on the remote server.
 	// Or maybe it's the prefix of a hash of a named ref.
 	// Try to resolve to both a ref (git name) and full (40-hex-digit) commit hash.
-	r.refsOnce.Do(r.loadRefs)
+	refs, err := r.loadRefs()
+	if err != nil {
+		return nil, err
+	}
 	// loadRefs may return an error if git fails, for example segfaults, or
 	// could not load a private repo, but defer checking to the else block
 	// below, in case we already have the rev in question in the local cache.
 	var ref, hash string
-	if r.refs["refs/tags/"+rev] != "" {
+	if refs["refs/tags/"+rev] != "" {
 		ref = "refs/tags/" + rev
-		hash = r.refs[ref]
+		hash = refs[ref]
 		// Keep rev as is: tags are assumed not to change meaning.
-	} else if r.refs["refs/heads/"+rev] != "" {
+	} else if refs["refs/heads/"+rev] != "" {
 		ref = "refs/heads/" + rev
-		hash = r.refs[ref]
+		hash = refs[ref]
 		rev = hash // Replace rev, because meaning of refs/heads/foo can change.
-	} else if rev == "HEAD" && r.refs["HEAD"] != "" {
+	} else if rev == "HEAD" && refs["HEAD"] != "" {
 		ref = "HEAD"
-		hash = r.refs[ref]
+		hash = refs[ref]
 		rev = hash // Replace rev, because meaning of HEAD can change.
 	} else if len(rev) >= minHashDigits && len(rev) <= 40 && AllHex(rev) {
 		// At the least, we have a hash prefix we can look up after the fetch below.
 		// Maybe we can map it to a full hash using the known refs.
 		prefix := rev
 		// Check whether rev is prefix of known ref hash.
-		for k, h := range r.refs {
+		for k, h := range refs {
 			if strings.HasPrefix(h, prefix) {
 				if hash != "" && hash != h {
 					// Hash is an ambiguous hash prefix.
@@ -335,9 +345,6 @@ func (r *gitRepo) stat(rev string) (*RevInfo, error) {
 			hash = rev
 		}
 	} else {
-		if r.refsErr != nil {
-			return nil, r.refsErr
-		}
 		return nil, &UnknownRevisionError{Rev: rev}
 	}
 
@@ -535,12 +542,12 @@ func (r *gitRepo) ReadFileRevs(revs []string, file string, maxSize int64) (map[s
 
 	// Build list of known remote refs that might help.
 	var redo []string
-	r.refsOnce.Do(r.loadRefs)
-	if r.refsErr != nil {
-		return nil, r.refsErr
+	refs, err := r.loadRefs()
+	if err != nil {
+		return nil, err
 	}
 	for _, tag := range need {
-		if r.refs["refs/tags/"+tag] != "" {
+		if refs["refs/tags/"+tag] != "" {
 			redo = append(redo, tag)
 		}
 	}
diff --git a/src/cmd/go/internal/modload/buildlist.go b/src/cmd/go/internal/modload/buildlist.go
index 4fbe563cb832c911bfff31dbb58162660eb5d302..9989bb5b2a47e4afe137e9fa4018edd1bccd9e71 100644
--- a/src/cmd/go/internal/modload/buildlist.go
+++ b/src/cmd/go/internal/modload/buildlist.go
@@ -196,6 +196,19 @@ func (rs *Requirements) rootSelected(path string) (version string, ok bool) {
 	return "", false
 }
 
+// hasRedundantRoot returns true if the root list contains multiple requirements
+// of the same module or a requirement on any version of the main module.
+// Redundant requirements should be pruned, but they may influence version
+// selection.
+func (rs *Requirements) hasRedundantRoot() bool {
+	for i, m := range rs.rootModules {
+		if MainModules.Contains(m.Path) || (i > 0 && m.Path == rs.rootModules[i-1].Path) {
+			return true
+		}
+	}
+	return false
+}
+
 // Graph returns the graph of module requirements loaded from the current
 // root modules (as reported by RootModules).
 //
@@ -897,6 +910,12 @@ func updateLazyRoots(ctx context.Context, direct map[string]bool, rs *Requiremen
 		// and (trivially) version.
 
 		if !rootsUpgraded {
+			if cfg.BuildMod != "mod" {
+				// The only changes to the root set (if any) were to remove duplicates.
+				// The requirements are consistent (if perhaps redundant), so keep the
+				// original rs to preserve its ModuleGraph.
+				return rs, nil
+			}
 			// The root set has converged: every root going into this iteration was
 			// already at its selected version, although we have have removed other
 			// (redundant) roots for the same path.
diff --git a/src/cmd/go/internal/modload/init.go b/src/cmd/go/internal/modload/init.go
index 1a91b83148a702ff0ac84200284ca894368726c2..896c61d19dd971a07c83ef4b8396e96dd1646e85 100644
--- a/src/cmd/go/internal/modload/init.go
+++ b/src/cmd/go/internal/modload/init.go
@@ -674,6 +674,18 @@ func loadModFile(ctx context.Context) (rs *Requirements, needCommit bool) {
 		checkVendorConsistency(index, modFile)
 		rs.initVendor(vendorList)
 	}
+
+	if rs.hasRedundantRoot() {
+		// If any module path appears more than once in the roots, we know that the
+		// go.mod file needs to be updated even though we have not yet loaded any
+		// transitive dependencies.
+		var err error
+		rs, err = updateRoots(ctx, rs.direct, rs, nil, nil, false)
+		if err != nil {
+			base.Fatalf("go: %v", err)
+		}
+	}
+
 	if MainModules.Index(mainModule).goVersionV == "" {
 		// TODO(#45551): Do something more principled instead of checking
 		// cfg.CmdName directly here.
@@ -734,6 +746,13 @@ func CreateModFile(ctx context.Context, modPath string) {
 			}
 		}
 		base.Fatalf("go: %v", err)
+	} else if _, _, ok := module.SplitPathVersion(modPath); !ok {
+		if strings.HasPrefix(modPath, "gopkg.in/") {
+			invalidMajorVersionMsg := fmt.Errorf("module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN:\n\tgo mod init %s", suggestGopkgIn(modPath))
+			base.Fatalf(`go: invalid module path "%v": %v`, modPath, invalidMajorVersionMsg)
+		}
+		invalidMajorVersionMsg := fmt.Errorf("major version suffixes must be in the form of /vN and are only allowed for v2 or later:\n\tgo mod init %s", suggestModulePath(modPath))
+		base.Fatalf(`go: invalid module path "%v": %v`, modPath, invalidMajorVersionMsg)
 	}
 
 	fmt.Fprintf(os.Stderr, "go: creating new go.mod: module %s\n", modPath)
@@ -750,7 +769,12 @@ func CreateModFile(ctx context.Context, modPath string) {
 		base.Fatalf("go: %v", err)
 	}
 
-	commitRequirements(ctx, modFileGoVersion(), requirementsFromModFiles(ctx, []*modfile.File{modFile}))
+	rs := requirementsFromModFiles(ctx, []*modfile.File{modFile})
+	rs, err = updateRoots(ctx, rs.direct, rs, nil, nil, false)
+	if err != nil {
+		base.Fatalf("go: %v", err)
+	}
+	commitRequirements(ctx, modFileGoVersion(), rs)
 
 	// Suggest running 'go mod tidy' unless the project is empty. Even if we
 	// imported all the correct requirements above, we're probably missing
@@ -930,7 +954,6 @@ func requirementsFromModFiles(ctx context.Context, modFiles []*modfile.File) *Re
 			}
 
 			roots = append(roots, r.Mod)
-			mPathCount[r.Mod.Path]++
 			if !r.Indirect {
 				direct[r.Mod.Path] = true
 			}
@@ -938,21 +961,6 @@ func requirementsFromModFiles(ctx context.Context, modFiles []*modfile.File) *Re
 	}
 	module.Sort(roots)
 	rs := newRequirements(modDepthFromGoVersion(modFileGoVersion()), roots, direct)
-
-	// If any module path appears more than once in the roots, we know that the
-	// go.mod file needs to be updated even though we have not yet loaded any
-	// transitive dependencies.
-	for _, n := range mPathCount {
-		if n > 1 {
-			var err error
-			rs, err = updateRoots(ctx, rs.direct, rs, nil, nil, false)
-			if err != nil {
-				base.Fatalf("go: %v", err)
-			}
-			break
-		}
-	}
-
 	return rs
 }
 
@@ -1541,3 +1549,56 @@ const (
 func modkey(m module.Version) module.Version {
 	return module.Version{Path: m.Path, Version: m.Version + "/go.mod"}
 }
+
+func suggestModulePath(path string) string {
+	var m string
+
+	i := len(path)
+	for i > 0 && ('0' <= path[i-1] && path[i-1] <= '9' || path[i-1] == '.') {
+		i--
+	}
+	url := path[:i]
+	url = strings.TrimSuffix(url, "/v")
+	url = strings.TrimSuffix(url, "/")
+
+	f := func(c rune) bool {
+		return c > '9' || c < '0'
+	}
+	s := strings.FieldsFunc(path[i:], f)
+	if len(s) > 0 {
+		m = s[0]
+	}
+	m = strings.TrimLeft(m, "0")
+	if m == "" || m == "1" {
+		return url + "/v2"
+	}
+
+	return url + "/v" + m
+}
+
+func suggestGopkgIn(path string) string {
+	var m string
+	i := len(path)
+	for i > 0 && (('0' <= path[i-1] && path[i-1] <= '9') || (path[i-1] == '.')) {
+		i--
+	}
+	url := path[:i]
+	url = strings.TrimSuffix(url, ".v")
+	url = strings.TrimSuffix(url, "/v")
+	url = strings.TrimSuffix(url, "/")
+
+	f := func(c rune) bool {
+		return c > '9' || c < '0'
+	}
+	s := strings.FieldsFunc(path, f)
+	if len(s) > 0 {
+		m = s[0]
+	}
+
+	m = strings.TrimLeft(m, "0")
+
+	if m == "" {
+		return url + ".v1"
+	}
+	return url + ".v" + m
+}
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 5e02a397a63828952cf04011645b0ca5a7763bdb..d65f54f2bd2bc76df929fcfbaf094ec46220cafa 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -79,7 +79,8 @@ binary. Only a high-confidence subset of the default go vet checks are
 used. That subset is: 'atomic', 'bool', 'buildtags', 'errorsas',
 'ifaceassert', 'nilfunc', 'printf', and 'stringintconv'. You can see
 the documentation for these and other vet tests via "go doc cmd/vet".
-To disable the running of go vet, use the -vet=off flag.
+To disable the running of go vet, use the -vet=off flag. To run all
+checks, use the -vet=all flag.
 
 All test output and summary lines are printed to the go command's
 standard output, even if the test printed them to its own standard
@@ -120,16 +121,16 @@ elapsed time in the summary line.
 The rule for a match in the cache is that the run involves the same
 test binary and the flags on the command line come entirely from a
 restricted set of 'cacheable' test flags, defined as -benchtime, -cpu,
--list, -parallel, -run, -short, and -v. If a run of go test has any test
-or non-test flags outside this set, the result is not cached. To
-disable test caching, use any test flag or argument other than the
-cacheable flags. The idiomatic way to disable test caching explicitly
-is to use -count=1. Tests that open files within the package's source
-root (usually $GOPATH) or that consult environment variables only
-match future runs in which the files and environment variables are unchanged.
-A cached test result is treated as executing in no time at all,
-so a successful package test result will be cached and reused
-regardless of -timeout setting.
+-list, -parallel, -run, -short, -timeout, -failfast, and -v.
+If a run of go test has any test or non-test flags outside this set,
+the result is not cached. To disable test caching, use any test flag
+or argument other than the cacheable flags. The idiomatic way to disable
+test caching explicitly is to use -count=1. Tests that open files within
+the package's source root (usually $GOPATH) or that consult environment
+variables only match future runs in which the files and environment
+variables are unchanged. A cached test result is treated as executing
+in no time at all,so a successful package test result will be cached and
+reused regardless of -timeout setting.
 
 In addition to the build flags, the flags handled by 'go test' itself are:
 
@@ -243,6 +244,10 @@ control the execution of any test:
 	-failfast
 	    Do not start new tests after the first test failure.
 
+	-json
+	    Log verbose output and test results in JSON. This presents the
+	    same information as the -v flag in a machine-readable format.
+
 	-list regexp
 	    List tests, benchmarks, or examples matching the regular expression.
 	    No tests, benchmarks or examples will be run. This will only
@@ -1349,6 +1354,7 @@ func (c *runCache) tryCacheWithID(b *work.Builder, a *work.Action, id string) bo
 			"-test.run",
 			"-test.short",
 			"-test.timeout",
+			"-test.failfast",
 			"-test.v":
 			// These are cacheable.
 			// Note that this list is documented above,
diff --git a/src/cmd/go/internal/test/testflag.go b/src/cmd/go/internal/test/testflag.go
index f129346d0dac3cc47fdb02b97d3d4d047ceea5ff..97a9ef38b979a7f2b0253372f5b8e2bc69ab33b7 100644
--- a/src/cmd/go/internal/test/testflag.go
+++ b/src/cmd/go/internal/test/testflag.go
@@ -5,6 +5,10 @@
 package test
 
 import (
+	"cmd/go/internal/base"
+	"cmd/go/internal/cfg"
+	"cmd/go/internal/cmdflag"
+	"cmd/go/internal/work"
 	"errors"
 	"flag"
 	"fmt"
@@ -13,11 +17,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-
-	"cmd/go/internal/base"
-	"cmd/go/internal/cfg"
-	"cmd/go/internal/cmdflag"
-	"cmd/go/internal/work"
 )
 
 //go:generate go run ./genflags.go
@@ -135,6 +134,7 @@ type outputdirFlag struct {
 func (f *outputdirFlag) String() string {
 	return f.abs
 }
+
 func (f *outputdirFlag) Set(value string) (err error) {
 	if value == "" {
 		f.abs = ""
@@ -143,6 +143,7 @@ func (f *outputdirFlag) Set(value string) (err error) {
 	}
 	return err
 }
+
 func (f *outputdirFlag) getAbs() string {
 	if f.abs == "" {
 		return base.Cwd()
@@ -151,8 +152,12 @@ func (f *outputdirFlag) getAbs() string {
 }
 
 // vetFlag implements the special parsing logic for the -vet flag:
-// a comma-separated list, with a distinguished value "off" and
-// a boolean tracking whether it was set explicitly.
+// a comma-separated list, with distinguished values "all" and
+// "off", plus a boolean tracking whether it was set explicitly.
+//
+// "all" is encoded as vetFlag{true, false, nil}, since it will
+// pass no flags to the vet binary, and by default, it runs all
+// analyzers.
 type vetFlag struct {
 	explicit bool
 	off      bool
@@ -160,7 +165,10 @@ type vetFlag struct {
 }
 
 func (f *vetFlag) String() string {
-	if f.off {
+	switch {
+	case !f.off && !f.explicit && len(f.flags) == 0:
+		return "all"
+	case f.off:
 		return "off"
 	}
 
@@ -175,32 +183,38 @@ func (f *vetFlag) String() string {
 }
 
 func (f *vetFlag) Set(value string) error {
-	if value == "" {
+	switch {
+	case value == "":
 		*f = vetFlag{flags: defaultVetFlags}
 		return nil
-	}
-
-	if value == "off" {
-		*f = vetFlag{
-			explicit: true,
-			off:      true,
-		}
-		return nil
-	}
-
-	if strings.Contains(value, "=") {
+	case strings.Contains(value, "="):
 		return fmt.Errorf("-vet argument cannot contain equal signs")
-	}
-	if strings.Contains(value, " ") {
+	case strings.Contains(value, " "):
 		return fmt.Errorf("-vet argument is comma-separated list, cannot contain spaces")
 	}
 	*f = vetFlag{explicit: true}
+	var single string
 	for _, arg := range strings.Split(value, ",") {
-		if arg == "" {
+		switch arg {
+		case "":
 			return fmt.Errorf("-vet argument contains empty list element")
+		case "all":
+			single = arg
+			*f = vetFlag{explicit: true}
+			continue
+		case "off":
+			single = arg
+			*f = vetFlag{
+				explicit: true,
+				off:      true,
+			}
+			continue
 		}
 		f.flags = append(f.flags, "-"+arg)
 	}
+	if len(f.flags) > 1 && single != "" {
+		return fmt.Errorf("-vet does not accept %q in a list with other analyzers", single)
+	}
 	return nil
 }
 
diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index 1fc825de47d45e095211f9386c74ebdce1ec22f0..eee8adca94d8bca54436324922ad99c957422034 100644
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -29,6 +29,18 @@ import (
 // The 'path' used for GOROOT_FINAL when -trimpath is specified
 const trimPathGoRootFinal = "go"
 
+var runtimePackages = map[string]struct{}{
+	"internal/abi":            struct{}{},
+	"internal/bytealg":        struct{}{},
+	"internal/cpu":            struct{}{},
+	"internal/goarch":         struct{}{},
+	"internal/goos":           struct{}{},
+	"runtime":                 struct{}{},
+	"runtime/internal/atomic": struct{}{},
+	"runtime/internal/math":   struct{}{},
+	"runtime/internal/sys":    struct{}{},
+}
+
 // The Go toolchain.
 
 type gcToolchain struct{}
@@ -88,11 +100,8 @@ func (gcToolchain) gc(b *Builder, a *Action, archive string, importcfg, embedcfg
 	if p.Standard {
 		gcargs = append(gcargs, "-std")
 	}
-	compilingRuntime := p.Standard && (p.ImportPath == "runtime" || strings.HasPrefix(p.ImportPath, "runtime/internal"))
-	// The runtime package imports a couple of general internal packages.
-	if p.Standard && (p.ImportPath == "internal/cpu" || p.ImportPath == "internal/bytealg" || p.ImportPath == "internal/abi") {
-		compilingRuntime = true
-	}
+	_, compilingRuntime := runtimePackages[p.ImportPath]
+	compilingRuntime = compilingRuntime && p.Standard
 	if compilingRuntime {
 		// runtime compiles with a special gc flag to check for
 		// memory allocations that are invalid in the runtime package,
@@ -365,6 +374,11 @@ func asmArgs(a *Action, p *load.Package) []interface{} {
 		args = append(args, "-compiling-runtime")
 	}
 
+	if cfg.Goarch == "386" {
+		// Define GO386_value from cfg.GO386.
+		args = append(args, "-D", "GO386_"+cfg.GO386)
+	}
+
 	if cfg.Goarch == "mips" || cfg.Goarch == "mipsle" {
 		// Define GOMIPS_value from cfg.GOMIPS.
 		args = append(args, "-D", "GOMIPS_"+cfg.GOMIPS)
diff --git a/src/cmd/go/internal/work/init.go b/src/cmd/go/internal/work/init.go
index 022137390f8fb32e8613ff5aaf79581a775dbf3b..7acee3dd55082055cbb3c00508a4af64958a61a0 100644
--- a/src/cmd/go/internal/work/init.go
+++ b/src/cmd/go/internal/work/init.go
@@ -40,6 +40,10 @@ func BuildInit() {
 		cfg.BuildPkgdir = p
 	}
 
+	if cfg.BuildP <= 0 {
+		base.Fatalf("go: -p must be a positive integer: %v\n", cfg.BuildP)
+	}
+
 	// Make sure CC, CXX, and FC are absolute paths.
 	for _, key := range []string{"CC", "CXX", "FC"} {
 		value := cfg.Getenv(key)
diff --git a/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.0.0+incompatible.txt b/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.0.0+incompatible.txt
index 35c3f277103df132a0588eb4fe5ef6ca4689e18f..00076d74fc2f8868a1e78de129bcbe6a6fbf1d51 100644
--- a/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.0.0+incompatible.txt
+++ b/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.0.0+incompatible.txt
@@ -1,6 +1,6 @@
 Written by hand.
 Test case for getting a package that has been moved to a nested module,
-with a +incompatible verison (and thus no go.mod file) at the root module.
+with a +incompatible version (and thus no go.mod file) at the root module.
 
 -- .mod --
 module example.com/split-incompatible
diff --git a/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.1.0-pre+incompatible.txt b/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.1.0-pre+incompatible.txt
index 917fc0f55992efa69f6767a486fd2a2908bded95..bb1c1fecc9d2713360069cf593b6df89e6e1c303 100644
--- a/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.1.0-pre+incompatible.txt
+++ b/src/cmd/go/testdata/mod/example.com_split-incompatible_v2.1.0-pre+incompatible.txt
@@ -1,6 +1,6 @@
 Written by hand.
 Test case for getting a package that has been moved to a nested module,
-with a +incompatible verison (and thus no go.mod file) at the root module.
+with a +incompatible version (and thus no go.mod file) at the root module.
 
 -- .mod --
 module example.com/split-incompatible
diff --git a/src/cmd/go/testdata/script/build_negative_p.txt b/src/cmd/go/testdata/script/build_negative_p.txt
new file mode 100644
index 0000000000000000000000000000000000000000..9123907dc87a40e41803c145433602aada4db3dd
--- /dev/null
+++ b/src/cmd/go/testdata/script/build_negative_p.txt
@@ -0,0 +1,5 @@
+! go build -p=-1 example.go
+stderr 'go: -p must be a positive integer: -1'
+
+-- example.go --
+package example
\ No newline at end of file
diff --git a/src/cmd/go/testdata/script/mod_init_invalid_major.txt b/src/cmd/go/testdata/script/mod_init_invalid_major.txt
new file mode 100644
index 0000000000000000000000000000000000000000..ae93e70d6307ff6e432c193d5db86bb187e24808
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_init_invalid_major.txt
@@ -0,0 +1,82 @@
+env GO111MODULE=on
+env GOFLAGS=-mod=mod
+
+! go mod init example.com/user/repo/v0
+stderr '(?s)^go: invalid module path "example.com/user/repo/v0": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v2$'
+
+! go mod init example.com/user/repo/v02
+stderr '(?s)^go: invalid module path "example.com/user/repo/v02": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v2$'
+
+! go mod init example.com/user/repo/v023
+stderr '(?s)^go: invalid module path "example.com/user/repo/v023": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v23$'
+
+! go mod init example.com/user/repo/v1
+stderr '(?s)^go: invalid module path "example.com/user/repo/v1": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v2$'
+
+! go mod init example.com/user/repo/v2.0
+stderr '(?s)^go: invalid module path "example.com/user/repo/v2.0": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v2$'
+
+! go mod init example.com/user/repo/v2.1.4
+stderr '(?s)^go: invalid module path "example.com/user/repo/v2.1.4": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v2$'
+
+! go mod init example.com/user/repo/v3.5
+stderr '(?s)^go: invalid module path "example.com/user/repo/v3.5": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v3$'
+
+! go mod init example.com/user/repo/v4.1.4
+stderr '(?s)^go: invalid module path "example.com/user/repo/v4.1.4": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v4$'
+
+! go mod init example.com/user/repo/v.2.3
+stderr '(?s)^go: invalid module path "example.com/user/repo/v.2.3": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v2$'
+
+! go mod init example.com/user/repo/v.5.3
+stderr '(?s)^go: invalid module path "example.com/user/repo/v.5.3": major version suffixes must be in the form of /vN and are only allowed for v2 or later(.*)go mod init example.com/user/repo/v5$'
+
+! go mod init gopkg.in/pkg
+stderr '(?s)^go: invalid module path "gopkg.in/pkg": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg/v0
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg/v0": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg/v1
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg/v1": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg/v2
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg/v2": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v2$'
+
+! go mod init gopkg.in/user/pkg.v
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg.v": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg.v0.1
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg.v0.1": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg.v.1
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg.v.1": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg.v01
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg.v01": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v1$'
+
+! go mod init gopkg.in/user/pkg.v.2.3
+stderr '(?s)^go: invalid module path "gopkg.in/user/pkg.v.2.3": module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN(.*)go mod init gopkg.in/user/pkg.v2$'
+
+# module paths with a trailing dot are rejected as invalid import paths
+! go mod init example.com/user/repo/v2.
+stderr '(?s)^go: malformed module path "example.com/user/repo/v2.": trailing dot in path element$'
+
+! go mod init example.com/user/repo/v2..
+stderr '(?s)^go: malformed module path "example.com/user/repo/v2..": trailing dot in path element$'
+
+! go mod init gopkg.in/user/pkg.v.2.
+stderr '(?s)^go: malformed module path "gopkg.in/user/pkg.v.2.": trailing dot in path element$'
+
+! go mod init gopkg.in/user/pkg.v.2..
+stderr '(?s)^go: malformed module path "gopkg.in/user/pkg.v.2..": trailing dot in path element$'
+
+# module paths with spaces are also rejected
+! go mod init 'foo bar'
+stderr '(?s)^go: malformed module path "foo bar": invalid char '' ''$'
+
+! go mod init 'foo  bar baz'
+stderr '(?s)^go: malformed module path "foo  bar baz": invalid char '' ''$'
diff --git a/src/cmd/go/testdata/script/mod_lazy_import_allmod.txt b/src/cmd/go/testdata/script/mod_lazy_import_allmod.txt
index 97718c4513b55bffd6819544119f32b74b734173..60d4187b1178aec7deb1a5e554fe55d936899d76 100644
--- a/src/cmd/go/testdata/script/mod_lazy_import_allmod.txt
+++ b/src/cmd/go/testdata/script/mod_lazy_import_allmod.txt
@@ -66,7 +66,7 @@ stdout '^b v0.1.0 '
 ! stdout '^c '
 
 # After adding a new direct import of b/y,
-# the existing verison of b should be promoted to a root,
+# the existing version of b should be promoted to a root,
 # bringing the version of c required by b into the build list.
 
 cp m.go.new m.go
diff --git a/src/cmd/go/testdata/script/mod_tidy_compat.txt b/src/cmd/go/testdata/script/mod_tidy_compat.txt
index e6edef5ee3b78c83a59063f990bf4527f2493b99..29cae17881191e397279f8155966b2a41536ca3e 100644
--- a/src/cmd/go/testdata/script/mod_tidy_compat.txt
+++ b/src/cmd/go/testdata/script/mod_tidy_compat.txt
@@ -20,7 +20,7 @@ env MODFMT='{{with .Module}}{{.Path}} {{.Version}}{{end}}'
 # + ---- example.net/lazy v0.1.0 ---- example.com/version v1.0.1
 #
 # Go 1.17 avoids loading the go.mod file for example.com/version v1.0.1
-# (because it is lower than the verison explicitly required by m,
+# (because it is lower than the version explicitly required by m,
 # and the module that requires it — m — specifies 'go 1.17').
 #
 # That go.mod file happens not to affect the final 1.16 module graph anyway,
diff --git a/src/cmd/go/testdata/script/mod_tidy_lazy_self.txt b/src/cmd/go/testdata/script/mod_tidy_lazy_self.txt
index ffcea186035574da7373494a69c3dc3ce050298c..9abbabd2ebe47345e3e1cbe9067a9e98fcf76b7f 100644
--- a/src/cmd/go/testdata/script/mod_tidy_lazy_self.txt
+++ b/src/cmd/go/testdata/script/mod_tidy_lazy_self.txt
@@ -2,18 +2,13 @@
 # 'go mod tidy' should not panic if the main module initially
 # requires an older version of itself.
 
+# A module may require an older version of itself without error. This is
+# inconsistent (the required version is never selected), but we still get
+# a reproducible build list.
+go list -m all
+stdout '^golang.org/issue/46078$'
 
-# A module that explicitly requires an older version of itself should be
-# rejected as inconsistent: we enforce that every explicit requirement is the
-# selected version of its module path, but the selected version of the main
-# module is always itself — not some explicit version.
-
-! go list -m all
-stderr '^go: updates to go\.mod needed; to update it:\n\tgo mod tidy$'
-
-
-# The suggested 'go mod tidy' command should succeed (not crash).
-
+# 'go mod tidy' should fix this (and not crash).
 go mod tidy
 
 
diff --git a/src/cmd/go/testdata/script/mod_vendor_goversion.txt b/src/cmd/go/testdata/script/mod_vendor_goversion.txt
index aa4cb41171a5199aaf94fd8566d050798ec31fff..7f1966c8e890fc1826ad029e90cc5b2c78dfc958 100644
--- a/src/cmd/go/testdata/script/mod_vendor_goversion.txt
+++ b/src/cmd/go/testdata/script/mod_vendor_goversion.txt
@@ -26,7 +26,7 @@ go mod vendor
 
 ! grep 1.17 vendor/modules.txt
 ! go build example.net/need117
-stderr '^vendor[/\\]example\.net[/\\]need117[/\\]need117.go:5:18: .*\n\tconversion of slices to array pointers only supported as of -lang=go1\.17'
+stderr '^vendor[/\\]example\.net[/\\]need117[/\\]need117.go:5:1[89]: .*conversion of slices to array pointers only supported as of -lang=go1\.17'
 
 ! grep 1.13 vendor/modules.txt
 go build example.net/bad114
diff --git a/src/cmd/go/testdata/script/mod_vendor_redundant_requirement.txt b/src/cmd/go/testdata/script/mod_vendor_redundant_requirement.txt
new file mode 100644
index 0000000000000000000000000000000000000000..3f6f5c5276b9752f9445840181aa9689801731f5
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_vendor_redundant_requirement.txt
@@ -0,0 +1,29 @@
+# 'go list -mod=vendor' should succeed even when go.mod contains redundant
+# requirements. Verifies #47565.
+go list -mod=vendor
+
+-- go.mod --
+module m
+
+go 1.17
+
+require example.com/m v0.0.0
+require example.com/m v0.0.0
+
+replace example.com/m v0.0.0 => ./m
+-- m/go.mod --
+module example.com/m
+
+go 1.17
+-- m/m.go --
+package m
+-- use.go --
+package use
+
+import _ "example.com/m"
+-- vendor/example.com/m/m.go --
+package m
+-- vendor/modules.txt --
+# example.com/m v0.0.0 => ./m
+## explicit; go 1.17
+example.com/m
diff --git a/src/cmd/go/testdata/script/test_cache_inputs.txt b/src/cmd/go/testdata/script/test_cache_inputs.txt
index d694a30994710e70145469998b3fd086b5f2964f..3705c700d10bc905f7cfdd63657a1ca7e3dbe1f0 100644
--- a/src/cmd/go/testdata/script/test_cache_inputs.txt
+++ b/src/cmd/go/testdata/script/test_cache_inputs.txt
@@ -108,6 +108,12 @@ go test testcache -run=Benchtime -bench=Benchtime -benchtime=1x
 go test testcache -run=Benchtime -bench=Benchtime -benchtime=1x
 ! stdout '\(cached\)'
 
+# golang.org/issue/47355: that includes the `-failfast` argument.
+go test testcache -run=TestOSArgs -failfast
+! stdout '\(cached\)'
+go test testcache -run=TestOSArgs -failfast
+stdout '\(cached\)'
+
 # Executables within GOROOT and GOPATH should affect caching,
 # even if the test does not stat them explicitly.
 
diff --git a/src/cmd/go/testdata/script/test_vet.txt b/src/cmd/go/testdata/script/test_vet.txt
index 5af26b54f9141bb189bbf15b55edef6fa09c0919..2e0ae1956a00f124653f4a7021bca93da2eea2b0 100644
--- a/src/cmd/go/testdata/script/test_vet.txt
+++ b/src/cmd/go/testdata/script/test_vet.txt
@@ -16,6 +16,11 @@ go test -vet=off p1.go
 ! stderr '[\\/]vet.*-shift'
 stdout '\[no test files\]'
 
+# ensure all runs non-default vet
+! go test -vet=all ./vetall/...
+stderr 'using resp before checking for errors'
+
+
 # Test issue #22890
 go test m/vetcycle
 stdout 'm/vetcycle.*\[no test files\]'
@@ -51,6 +56,21 @@ import "fmt"
 func F() {
 	fmt.Printf("%d") // oops
 }
+-- vetall/p.go --
+package p
+
+import "net/http"
+
+func F() {
+	resp, err := http.Head("example.com")
+	defer resp.Body.Close()
+	if err != nil {
+		panic(err)
+	}
+	// (defer statement belongs here)
+}
+-- vetall/p_test.go --
+package p
 -- vetcycle/p.go --
 package p
 
diff --git a/src/cmd/go/testdata/script/work.txt b/src/cmd/go/testdata/script/work.txt
index 095d6ff1745e5fca9c13d85bdb2a0037f5c95bf0..529c1c0bfd944a4aca0cf4843aa8814187e917f1 100644
--- a/src/cmd/go/testdata/script/work.txt
+++ b/src/cmd/go/testdata/script/work.txt
@@ -50,7 +50,7 @@ go build -n -workfile=off -o foo foo.go
 go build -n -o foo foo.go
 
 -- go.work.dup --
-go 1.17
+go 1.18
 
 directory (
   a
@@ -58,14 +58,14 @@ directory (
   ../src/a
 )
 -- go.work.want --
-go 1.17
+go 1.18
 
 directory (
 	./a
 	./b
 )
 -- go.work.d --
-go 1.17
+go 1.18
 
 directory (
 	a
diff --git a/src/cmd/go/testdata/script/work_edit.txt b/src/cmd/go/testdata/script/work_edit.txt
index 0717086ee7c2aa07a6109727f0a63b3557d40ef0..0de4069865d5a53ad40ebb1e02e887e09c799719 100644
--- a/src/cmd/go/testdata/script/work_edit.txt
+++ b/src/cmd/go/testdata/script/work_edit.txt
@@ -34,11 +34,11 @@ go mod editwork -print -fmt -workfile unformatted
 cmp stdout formatted
 
 -- go.work.want_initial --
-go 1.17
+go 1.18
 
 directory m
 -- go.work.want_directory_n --
-go 1.17
+go 1.18
 
 directory (
 	m
@@ -132,7 +132,7 @@ replace x.1 v1.4.0 => ../z
 	]
 }
 -- unformatted --
-go 1.17
+go 1.18
  directory (
  a
   b
@@ -143,7 +143,7 @@ go 1.17
                             x.1 v1.4.0 => ../z
                             )
 -- formatted --
-go 1.17
+go 1.18
 
 directory (
 	a
diff --git a/src/cmd/gofmt/gofmt_test.go b/src/cmd/gofmt/gofmt_test.go
index f0d3f8780f40e135f2e86f8d21e1feb61dbfecbd..9ef7676214c9f53a93aea54c39edae9580f0090c 100644
--- a/src/cmd/gofmt/gofmt_test.go
+++ b/src/cmd/gofmt/gofmt_test.go
@@ -54,8 +54,6 @@ func gofmtFlags(filename string, maxLines int) string {
 	return ""
 }
 
-var typeParamsEnabled = false
-
 func runTest(t *testing.T, in, out string) {
 	// process flags
 	*simplifyAST = false
@@ -78,11 +76,6 @@ func runTest(t *testing.T, in, out string) {
 		case "-stdin":
 			// fake flag - pretend input is from stdin
 			stdin = true
-		case "-G":
-			// fake flag - test is for generic code
-			if !typeParamsEnabled {
-				return
-			}
 		default:
 			t.Errorf("unrecognized flag name: %s", name)
 		}
diff --git a/src/cmd/gofmt/testdata/typeparams.golden b/src/cmd/gofmt/testdata/typeparams.golden
index 35f08d13792c70e458b0d14fe2c63b9c8c441d74..f71bd130db4ab075aa5f8296ff6315958688c82f 100644
--- a/src/cmd/gofmt/testdata/typeparams.golden
+++ b/src/cmd/gofmt/testdata/typeparams.golden
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//gofmt -G
+//gofmt
 
 package typeparams
 
diff --git a/src/cmd/gofmt/testdata/typeparams.input b/src/cmd/gofmt/testdata/typeparams.input
index 7f3212c8e4a8d833045b8e066dd6d515f9ac1f42..5d4c53d9f767a97e0f9cff8be06b8a2662e9004b 100644
--- a/src/cmd/gofmt/testdata/typeparams.input
+++ b/src/cmd/gofmt/testdata/typeparams.input
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//gofmt -G
+//gofmt
 
 package typeparams
 
diff --git a/src/cmd/internal/buildid/buildid_test.go b/src/cmd/internal/buildid/buildid_test.go
index e832f9987e582eb9b262c50f12aa4c8abae23fef..4895a49e1118a29c2546c5985aed6660ca70fbd0 100644
--- a/src/cmd/internal/buildid/buildid_test.go
+++ b/src/cmd/internal/buildid/buildid_test.go
@@ -177,3 +177,11 @@ func TestExcludedReader(t *testing.T) {
 		}
 	}
 }
+
+func TestEmptyID(t *testing.T) {
+	r := strings.NewReader("aha!")
+	matches, hash, err := FindAndHash(r, "", 1000)
+	if matches != nil || hash != ([32]byte{}) || err == nil || !strings.Contains(err.Error(), "no id") {
+		t.Errorf("FindAndHash: want nil, [32]byte{}, no id specified, got %v, %v, %v", matches, hash, err)
+	}
+}
diff --git a/src/cmd/internal/buildid/rewrite.go b/src/cmd/internal/buildid/rewrite.go
index a7928959c483da9f467fefb6209030c8d34b030d..8814950db0d83f142aaf551b1a2071e4ac59b66d 100644
--- a/src/cmd/internal/buildid/rewrite.go
+++ b/src/cmd/internal/buildid/rewrite.go
@@ -22,6 +22,9 @@ func FindAndHash(r io.Reader, id string, bufSize int) (matches []int64, hash [32
 	if bufSize == 0 {
 		bufSize = 31 * 1024 // bufSize+little will likely fit in 32 kB
 	}
+	if len(id) == 0 {
+		return nil, [32]byte{}, fmt.Errorf("buildid.FindAndHash: no id specified")
+	}
 	if len(id) > bufSize {
 		return nil, [32]byte{}, fmt.Errorf("buildid.FindAndHash: buffer too small")
 	}
diff --git a/src/cmd/internal/dwarf/dwarf.go b/src/cmd/internal/dwarf/dwarf.go
index 54c4c4d56d70719e2987dcee43e488b2f326bfec..4e163db020f959751c7fcc79ae8c9838116013e9 100644
--- a/src/cmd/internal/dwarf/dwarf.go
+++ b/src/cmd/internal/dwarf/dwarf.go
@@ -1266,7 +1266,7 @@ func PutAbstractFunc(ctxt Context, s *FnState) error {
 // its corresponding 'abstract' DIE (containing location-independent
 // attributes such as name, type, etc). Inlined subroutine DIEs can
 // have other inlined subroutine DIEs as children.
-func putInlinedFunc(ctxt Context, s *FnState, callersym Sym, callIdx int) error {
+func putInlinedFunc(ctxt Context, s *FnState, callIdx int) error {
 	ic := s.InlCalls.Calls[callIdx]
 	callee := ic.AbsFunSym
 
@@ -1277,7 +1277,7 @@ func putInlinedFunc(ctxt Context, s *FnState, callersym Sym, callIdx int) error
 	Uleb128put(ctxt, s.Info, int64(abbrev))
 
 	if logDwarf {
-		ctxt.Logf("putInlinedFunc(caller=%v,callee=%v,abbrev=%d)\n", callersym, callee, abbrev)
+		ctxt.Logf("putInlinedFunc(callee=%v,abbrev=%d)\n", callee, abbrev)
 	}
 
 	// Abstract origin.
@@ -1312,8 +1312,7 @@ func putInlinedFunc(ctxt Context, s *FnState, callersym Sym, callIdx int) error
 
 	// Children of this inline.
 	for _, sib := range inlChildren(callIdx, &s.InlCalls) {
-		absfn := s.InlCalls.Calls[sib].AbsFunSym
-		err := putInlinedFunc(ctxt, s, absfn, sib)
+		err := putInlinedFunc(ctxt, s, sib)
 		if err != nil {
 			return err
 		}
@@ -1354,8 +1353,7 @@ func PutConcreteFunc(ctxt Context, s *FnState) error {
 
 	// Inlined subroutines.
 	for _, sib := range inlChildren(-1, &s.InlCalls) {
-		absfn := s.InlCalls.Calls[sib].AbsFunSym
-		err := putInlinedFunc(ctxt, s, absfn, sib)
+		err := putInlinedFunc(ctxt, s, sib)
 		if err != nil {
 			return err
 		}
@@ -1402,8 +1400,7 @@ func PutDefaultFunc(ctxt Context, s *FnState) error {
 
 	// Inlined subroutines.
 	for _, sib := range inlChildren(-1, &s.InlCalls) {
-		absfn := s.InlCalls.Calls[sib].AbsFunSym
-		err := putInlinedFunc(ctxt, s, absfn, sib)
+		err := putInlinedFunc(ctxt, s, sib)
 		if err != nil {
 			return err
 		}
diff --git a/src/cmd/internal/goobj/builtinlist.go b/src/cmd/internal/goobj/builtinlist.go
index 9f248137daabce0eb9b07e93cecb8b73c274f1dd..608c0d72223e4ee2d181b7248b8895da076eda33 100644
--- a/src/cmd/internal/goobj/builtinlist.go
+++ b/src/cmd/internal/goobj/builtinlist.go
@@ -33,6 +33,7 @@ var builtins = [...]struct {
 	{"runtime.goPanicSlice3BU", 1},
 	{"runtime.goPanicSlice3C", 1},
 	{"runtime.goPanicSlice3CU", 1},
+	{"runtime.goPanicSliceConvert", 1},
 	{"runtime.printbool", 1},
 	{"runtime.printfloat", 1},
 	{"runtime.printint", 1},
@@ -129,6 +130,8 @@ var builtins = [...]struct {
 	{"runtime.makeslice64", 1},
 	{"runtime.makeslicecopy", 1},
 	{"runtime.growslice", 1},
+	{"runtime.unsafeslice", 1},
+	{"runtime.unsafeslice64", 1},
 	{"runtime.memmove", 1},
 	{"runtime.memclrNoHeapPointers", 1},
 	{"runtime.memclrHasPointers", 1},
@@ -203,7 +206,9 @@ var builtins = [...]struct {
 	{"runtime.newproc", 1},
 	{"runtime.panicoverflow", 1},
 	{"runtime.sigpanic", 1},
-	{"runtime.gcWriteBarrier", 0},
+	{"runtime.gcWriteBarrier", 1},
+	{"runtime.duffzero", 1},
+	{"runtime.duffcopy", 1},
 	{"runtime.morestack", 0},
 	{"runtime.morestackc", 0},
 	{"runtime.morestack_noctxt", 0},
diff --git a/src/cmd/internal/goobj/mkbuiltin.go b/src/cmd/internal/goobj/mkbuiltin.go
index 18b969586cceda54f55d97cb010b610032a33888..c9995fcedef8eee70bc68b8477c13fc4697dc313 100644
--- a/src/cmd/internal/goobj/mkbuiltin.go
+++ b/src/cmd/internal/goobj/mkbuiltin.go
@@ -151,7 +151,9 @@ var fextras = [...]extra{
 	{"sigpanic", 1},
 
 	// compiler backend inserted calls
-	{"gcWriteBarrier", 0}, // asm function, ABI0
+	{"gcWriteBarrier", 1},
+	{"duffzero", 1},
+	{"duffcopy", 1},
 
 	// assembler backend inserted calls
 	{"morestack", 0},        // asm function, ABI0
diff --git a/src/cmd/internal/obj/arm/asm5.go b/src/cmd/internal/obj/arm/asm5.go
index ccf5f9e7f8d959da412e76835290e8f694b85599..7b1682776e5316ad657f49a361329300eab6098c 100644
--- a/src/cmd/internal/obj/arm/asm5.go
+++ b/src/cmd/internal/obj/arm/asm5.go
@@ -355,11 +355,10 @@ var oprange [ALAST & obj.AMask][]Optab
 var xcmp [C_GOK + 1][C_GOK + 1]bool
 
 var (
-	deferreturn *obj.LSym
-	symdiv      *obj.LSym
-	symdivu     *obj.LSym
-	symmod      *obj.LSym
-	symmodu     *obj.LSym
+	symdiv  *obj.LSym
+	symdivu *obj.LSym
+	symmod  *obj.LSym
+	symmodu *obj.LSym
 )
 
 // Note about encoding: Prog.scond holds the condition encoding,
@@ -1219,8 +1218,6 @@ func buildop(ctxt *obj.Link) {
 		return
 	}
 
-	deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
-
 	symdiv = ctxt.Lookup("runtime._div")
 	symdivu = ctxt.Lookup("runtime._divu")
 	symmod = ctxt.Lookup("runtime._mod")
diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index d99afa3d27606f362798eeeed403e8e1420dc4c2..8db25cf9675a80c3651b742c268bbecd5758559b 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -361,12 +361,12 @@ var optab = []Optab{
 	{AANDS, C_REG, C_NONE, C_NONE, C_REG, 1, 4, 0, 0, 0},
 	{ATST, C_REG, C_REG, C_NONE, C_NONE, 1, 4, 0, 0, 0},
 	{AAND, C_MBCON, C_REG, C_NONE, C_RSP, 53, 4, 0, 0, 0},
-	{AAND, C_MBCON, C_NONE, C_NONE, C_REG, 53, 4, 0, 0, 0},
+	{AAND, C_MBCON, C_NONE, C_NONE, C_RSP, 53, 4, 0, 0, 0},
 	{AANDS, C_MBCON, C_REG, C_NONE, C_REG, 53, 4, 0, 0, 0},
 	{AANDS, C_MBCON, C_NONE, C_NONE, C_REG, 53, 4, 0, 0, 0},
 	{ATST, C_MBCON, C_REG, C_NONE, C_NONE, 53, 4, 0, 0, 0},
 	{AAND, C_BITCON, C_REG, C_NONE, C_RSP, 53, 4, 0, 0, 0},
-	{AAND, C_BITCON, C_NONE, C_NONE, C_REG, 53, 4, 0, 0, 0},
+	{AAND, C_BITCON, C_NONE, C_NONE, C_RSP, 53, 4, 0, 0, 0},
 	{AANDS, C_BITCON, C_REG, C_NONE, C_REG, 53, 4, 0, 0, 0},
 	{AANDS, C_BITCON, C_NONE, C_NONE, C_REG, 53, 4, 0, 0, 0},
 	{ATST, C_BITCON, C_REG, C_NONE, C_NONE, 53, 4, 0, 0, 0},
@@ -404,6 +404,8 @@ var optab = []Optab{
 	/* TODO: MVN C_SHIFT */
 
 	/* MOVs that become MOVK/MOVN/MOVZ/ADD/SUB/OR */
+	{AMOVW, C_MBCON, C_NONE, C_NONE, C_REG, 32, 4, 0, 0, 0},
+	{AMOVD, C_MBCON, C_NONE, C_NONE, C_REG, 32, 4, 0, 0, 0},
 	{AMOVW, C_MOVCON, C_NONE, C_NONE, C_REG, 32, 4, 0, 0, 0},
 	{AMOVD, C_MOVCON, C_NONE, C_NONE, C_REG, 32, 4, 0, 0, 0},
 	{AMOVW, C_BITCON, C_NONE, C_NONE, C_RSP, 32, 4, 0, 0, 0},
@@ -415,7 +417,7 @@ var optab = []Optab{
 
 	{AMOVK, C_VCON, C_NONE, C_NONE, C_REG, 33, 4, 0, 0, 0},
 	{AMOVD, C_AACON, C_NONE, C_NONE, C_RSP, 4, 4, REGFROM, 0, 0},
-	{AMOVD, C_AACON2, C_NONE, C_NONE, C_RSP, 4, 8, REGFROM, 0, 0},
+	{AMOVD, C_AACON2, C_NONE, C_NONE, C_RSP, 4, 8, REGFROM, NOTUSETMP, 0},
 
 	/* load long effective stack address (load int32 offset and add) */
 	{AMOVD, C_LACON, C_NONE, C_NONE, C_RSP, 34, 8, REGSP, LFROM, 0},
@@ -692,13 +694,12 @@ var optab = []Optab{
 	{AFMOVD, C_FREG, C_NONE, C_NONE, C_ROFF, 99, 4, 0, 0, 0},
 
 	/* pre/post-indexed/signed-offset load/store register pair
-	   (unscaled, signed 10-bit quad-aligned and long offset) */
+	   (unscaled, signed 10-bit quad-aligned and long offset).
+	The pre/post-indexed format only supports OREG cases because
+	the RSP and pseudo registers are not allowed to be modified
+	in this way. */
 	{AFLDPQ, C_NQAUTO_16, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, 0},
-	{AFLDPQ, C_NQAUTO_16, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPRE},
-	{AFLDPQ, C_NQAUTO_16, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPOST},
 	{AFLDPQ, C_PQAUTO_16, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, 0},
-	{AFLDPQ, C_PQAUTO_16, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPRE},
-	{AFLDPQ, C_PQAUTO_16, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPOST},
 	{AFLDPQ, C_UAUTO4K, C_NONE, C_NONE, C_PAIR, 74, 8, REGSP, 0, 0},
 	{AFLDPQ, C_NAUTO4K, C_NONE, C_NONE, C_PAIR, 74, 8, REGSP, 0, 0},
 	{AFLDPQ, C_LAUTO, C_NONE, C_NONE, C_PAIR, 75, 12, REGSP, LFROM, 0},
@@ -714,11 +715,7 @@ var optab = []Optab{
 	{AFLDPQ, C_ADDR, C_NONE, C_NONE, C_PAIR, 88, 12, 0, 0, 0},
 
 	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_NQAUTO_16, 67, 4, REGSP, 0, 0},
-	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_NQAUTO_16, 67, 4, REGSP, 0, C_XPRE},
-	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_NQAUTO_16, 67, 4, REGSP, 0, C_XPOST},
 	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_PQAUTO_16, 67, 4, REGSP, 0, 0},
-	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_PQAUTO_16, 67, 4, REGSP, 0, C_XPRE},
-	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_PQAUTO_16, 67, 4, REGSP, 0, C_XPOST},
 	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_UAUTO4K, 76, 8, REGSP, 0, 0},
 	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_NAUTO4K, 76, 8, REGSP, 0, 0},
 	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_LAUTO, 77, 12, REGSP, LTO, 0},
@@ -734,11 +731,7 @@ var optab = []Optab{
 	{AFSTPQ, C_PAIR, C_NONE, C_NONE, C_ADDR, 87, 12, 0, 0, 0},
 
 	{ALDP, C_NPAUTO, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, 0},
-	{ALDP, C_NPAUTO, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPRE},
-	{ALDP, C_NPAUTO, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPOST},
 	{ALDP, C_PPAUTO, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, 0},
-	{ALDP, C_PPAUTO, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPRE},
-	{ALDP, C_PPAUTO, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPOST},
 	{ALDP, C_UAUTO4K, C_NONE, C_NONE, C_PAIR, 74, 8, REGSP, 0, 0},
 	{ALDP, C_NAUTO4K, C_NONE, C_NONE, C_PAIR, 74, 8, REGSP, 0, 0},
 	{ALDP, C_LAUTO, C_NONE, C_NONE, C_PAIR, 75, 12, REGSP, LFROM, 0},
@@ -754,11 +747,7 @@ var optab = []Optab{
 	{ALDP, C_ADDR, C_NONE, C_NONE, C_PAIR, 88, 12, 0, 0, 0},
 
 	{ASTP, C_PAIR, C_NONE, C_NONE, C_NPAUTO, 67, 4, REGSP, 0, 0},
-	{ASTP, C_PAIR, C_NONE, C_NONE, C_NPAUTO, 67, 4, REGSP, 0, C_XPRE},
-	{ASTP, C_PAIR, C_NONE, C_NONE, C_NPAUTO, 67, 4, REGSP, 0, C_XPOST},
 	{ASTP, C_PAIR, C_NONE, C_NONE, C_PPAUTO, 67, 4, REGSP, 0, 0},
-	{ASTP, C_PAIR, C_NONE, C_NONE, C_PPAUTO, 67, 4, REGSP, 0, C_XPRE},
-	{ASTP, C_PAIR, C_NONE, C_NONE, C_PPAUTO, 67, 4, REGSP, 0, C_XPOST},
 	{ASTP, C_PAIR, C_NONE, C_NONE, C_UAUTO4K, 76, 8, REGSP, 0, 0},
 	{ASTP, C_PAIR, C_NONE, C_NONE, C_NAUTO4K, 76, 8, REGSP, 0, 0},
 	{ASTP, C_PAIR, C_NONE, C_NONE, C_LAUTO, 77, 12, REGSP, LTO, 0},
@@ -775,11 +764,7 @@ var optab = []Optab{
 
 	// differ from LDP/STP for C_NSAUTO_4/C_PSAUTO_4/C_NSOREG_4/C_PSOREG_4
 	{ALDPW, C_NSAUTO_4, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, 0},
-	{ALDPW, C_NSAUTO_4, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPRE},
-	{ALDPW, C_NSAUTO_4, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPOST},
 	{ALDPW, C_PSAUTO_4, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, 0},
-	{ALDPW, C_PSAUTO_4, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPRE},
-	{ALDPW, C_PSAUTO_4, C_NONE, C_NONE, C_PAIR, 66, 4, REGSP, 0, C_XPOST},
 	{ALDPW, C_UAUTO4K, C_NONE, C_NONE, C_PAIR, 74, 8, REGSP, 0, 0},
 	{ALDPW, C_NAUTO4K, C_NONE, C_NONE, C_PAIR, 74, 8, REGSP, 0, 0},
 	{ALDPW, C_LAUTO, C_NONE, C_NONE, C_PAIR, 75, 12, REGSP, LFROM, 0},
@@ -795,11 +780,7 @@ var optab = []Optab{
 	{ALDPW, C_ADDR, C_NONE, C_NONE, C_PAIR, 88, 12, 0, 0, 0},
 
 	{ASTPW, C_PAIR, C_NONE, C_NONE, C_NSAUTO_4, 67, 4, REGSP, 0, 0},
-	{ASTPW, C_PAIR, C_NONE, C_NONE, C_NSAUTO_4, 67, 4, REGSP, 0, C_XPRE},
-	{ASTPW, C_PAIR, C_NONE, C_NONE, C_NSAUTO_4, 67, 4, REGSP, 0, C_XPOST},
 	{ASTPW, C_PAIR, C_NONE, C_NONE, C_PSAUTO_4, 67, 4, REGSP, 0, 0},
-	{ASTPW, C_PAIR, C_NONE, C_NONE, C_PSAUTO_4, 67, 4, REGSP, 0, C_XPRE},
-	{ASTPW, C_PAIR, C_NONE, C_NONE, C_PSAUTO_4, 67, 4, REGSP, 0, C_XPOST},
 	{ASTPW, C_PAIR, C_NONE, C_NONE, C_UAUTO4K, 76, 8, REGSP, 0, 0},
 	{ASTPW, C_PAIR, C_NONE, C_NONE, C_NAUTO4K, 76, 8, REGSP, 0, 0},
 	{ASTPW, C_PAIR, C_NONE, C_NONE, C_LAUTO, 77, 12, REGSP, LTO, 0},
@@ -2089,13 +2070,18 @@ func cmp(a int, b int) bool {
 			return true
 		}
 
+	case C_MBCON:
+		if b == C_ABCON0 {
+			return true
+		}
+
 	case C_BITCON:
 		if b == C_ABCON0 || b == C_ABCON || b == C_MBCON {
 			return true
 		}
 
 	case C_MOVCON:
-		if b == C_MBCON || b == C_ZCON || b == C_ADDCON0 || b == C_AMCON {
+		if b == C_MBCON || b == C_ZCON || b == C_ADDCON0 || b == C_ABCON0 || b == C_AMCON {
 			return true
 		}
 
@@ -3299,8 +3285,10 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		}
 
 		if int(o.size) == 8 {
-			o1 = c.oaddi(p, op, v&0xfff000, r, REGTMP)
-			o2 = c.oaddi(p, op, v&0x000fff, REGTMP, rt)
+			// NOTE: this case does not use REGTMP. If it ever does,
+			// remove the NOTUSETMP flag in optab.
+			o1 = c.oaddi(p, op, v&0xfff000, r, rt)
+			o2 = c.oaddi(p, op, v&0x000fff, rt, rt)
 			break
 		}
 
@@ -4198,6 +4186,10 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		if r == 0 {
 			r = rt
 		}
+		if r == REG_RSP {
+			c.ctxt.Diag("illegal source register: %v", p)
+			break
+		}
 		mode := 64
 		v := uint64(p.From.Offset)
 		switch p.As {
@@ -7039,8 +7031,8 @@ func (c *ctxt7) omovlit(as obj.As, p *obj.Prog, a *obj.Addr, dr int) uint32 {
 
 // load a constant (MOVCON or BITCON) in a into rt
 func (c *ctxt7) omovconst(as obj.As, p *obj.Prog, a *obj.Addr, rt int) (o1 uint32) {
-	if cls := oclass(a); cls == C_BITCON || cls == C_ABCON || cls == C_ABCON0 {
-		// or $bitcon, REGZERO, rt
+	if cls := oclass(a); (cls == C_BITCON || cls == C_ABCON || cls == C_ABCON0) && rt != REGZERO {
+		// or $bitcon, REGZERO, rt. rt can't be ZR.
 		mode := 64
 		var as1 obj.As
 		switch as {
diff --git a/src/cmd/internal/obj/arm64/obj7.go b/src/cmd/internal/obj/arm64/obj7.go
index e41fb3bb7531cb01e7c8319343c2c2cb5730d3ea..a043d0972c9a9cdff2e5ea3b82ac06042a09d79f 100644
--- a/src/cmd/internal/obj/arm64/obj7.go
+++ b/src/cmd/internal/obj/arm64/obj7.go
@@ -52,7 +52,7 @@ var complements = []obj.As{
 }
 
 func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
-	// MOV	g_stackguard(g), R1
+	// MOV	g_stackguard(g), RT1
 	p = obj.Appendp(p, c.newprog)
 
 	p.As = AMOVD
@@ -63,7 +63,7 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 		p.From.Offset = 3 * int64(c.ctxt.Arch.PtrSize) // G.stackguard1
 	}
 	p.To.Type = obj.TYPE_REG
-	p.To.Reg = REG_R1
+	p.To.Reg = REGRT1
 
 	// Mark the stack bound check and morestack call async nonpreemptible.
 	// If we get preempted here, when resumed the preemption request is
@@ -74,25 +74,25 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	q := (*obj.Prog)(nil)
 	if framesize <= objabi.StackSmall {
 		// small stack: SP < stackguard
-		//	MOV	SP, R2
-		//	CMP	stackguard, R2
+		//	MOV	SP, RT2
+		//	CMP	stackguard, RT2
 		p = obj.Appendp(p, c.newprog)
 
 		p.As = AMOVD
 		p.From.Type = obj.TYPE_REG
 		p.From.Reg = REGSP
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = REG_R2
+		p.To.Reg = REGRT2
 
 		p = obj.Appendp(p, c.newprog)
 		p.As = ACMP
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = REG_R1
-		p.Reg = REG_R2
+		p.From.Reg = REGRT1
+		p.Reg = REGRT2
 	} else if framesize <= objabi.StackBig {
 		// large stack: SP-framesize < stackguard-StackSmall
-		//	SUB	$(framesize-StackSmall), SP, R2
-		//	CMP	stackguard, R2
+		//	SUB	$(framesize-StackSmall), SP, RT2
+		//	CMP	stackguard, RT2
 		p = obj.Appendp(p, c.newprog)
 
 		p.As = ASUB
@@ -100,13 +100,13 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 		p.From.Offset = int64(framesize) - objabi.StackSmall
 		p.Reg = REGSP
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = REG_R2
+		p.To.Reg = REGRT2
 
 		p = obj.Appendp(p, c.newprog)
 		p.As = ACMP
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = REG_R1
-		p.Reg = REG_R2
+		p.From.Reg = REGRT1
+		p.Reg = REGRT2
 	} else {
 		// Such a large stack we need to protect against underflow.
 		// The runtime guarantees SP > objabi.StackBig, but
@@ -115,10 +115,10 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 		// stack guard to incorrectly succeed. We explicitly
 		// guard against underflow.
 		//
-		//	SUBS	$(framesize-StackSmall), SP, R2
+		//	SUBS	$(framesize-StackSmall), SP, RT2
 		//	// On underflow, jump to morestack
 		//	BLO	label_of_call_to_morestack
-		//	CMP	stackguard, R2
+		//	CMP	stackguard, RT2
 
 		p = obj.Appendp(p, c.newprog)
 		p.As = ASUBS
@@ -126,7 +126,7 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 		p.From.Offset = int64(framesize) - objabi.StackSmall
 		p.Reg = REGSP
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = REG_R2
+		p.To.Reg = REGRT2
 
 		p = obj.Appendp(p, c.newprog)
 		q = p
@@ -136,8 +136,8 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 		p = obj.Appendp(p, c.newprog)
 		p.As = ACMP
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = REG_R1
-		p.Reg = REG_R2
+		p.From.Reg = REGRT1
+		p.Reg = REGRT2
 	}
 
 	// BLS	do-morestack
@@ -161,17 +161,20 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
 	pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
 
+	if q != nil {
+		q.To.SetTarget(pcdata)
+	}
+	bls.To.SetTarget(pcdata)
+
+	spill := c.cursym.Func().SpillRegisterArgs(pcdata, c.newprog)
+
 	// MOV	LR, R3
-	movlr := obj.Appendp(pcdata, c.newprog)
+	movlr := obj.Appendp(spill, c.newprog)
 	movlr.As = AMOVD
 	movlr.From.Type = obj.TYPE_REG
 	movlr.From.Reg = REGLINK
 	movlr.To.Type = obj.TYPE_REG
 	movlr.To.Reg = REG_R3
-	if q != nil {
-		q.To.SetTarget(movlr)
-	}
-	bls.To.SetTarget(movlr)
 
 	debug := movlr
 	if false {
@@ -196,7 +199,8 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	}
 	call.To.Sym = c.ctxt.Lookup(morestack)
 
-	pcdata = c.ctxt.EndUnsafePoint(call, c.newprog, -1)
+	unspill := c.cursym.Func().UnspillRegisterArgs(call, c.newprog)
+	pcdata = c.ctxt.EndUnsafePoint(unspill, c.newprog, -1)
 
 	// B	start
 	jmp := obj.Appendp(pcdata, c.newprog)
@@ -301,7 +305,9 @@ func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
 	// for both 32-bit and 64-bit. 32-bit ops will
 	// zero the high 32-bit of the destination register
 	// anyway.
-	if (isANDWop(p.As) || isADDWop(p.As) || p.As == AMOVW) && p.From.Type == obj.TYPE_CONST {
+	// For MOVW, the destination register can't be ZR,
+	// so don't bother rewriting it in this situation.
+	if (isANDWop(p.As) || isADDWop(p.As) || p.As == AMOVW && p.To.Reg != REGZERO) && p.From.Type == obj.TYPE_CONST {
 		v := p.From.Offset & 0xffffffff
 		p.From.Offset = v | v<<32
 	}
@@ -321,9 +327,9 @@ func (c *ctxt7) rewriteToUseGot(p *obj.Prog) {
 		//     CALL REGTMP
 		var sym *obj.LSym
 		if p.As == obj.ADUFFZERO {
-			sym = c.ctxt.Lookup("runtime.duffzero")
+			sym = c.ctxt.LookupABI("runtime.duffzero", obj.ABIInternal)
 		} else {
-			sym = c.ctxt.Lookup("runtime.duffcopy")
+			sym = c.ctxt.LookupABI("runtime.duffcopy", obj.ABIInternal)
 		}
 		offset := p.To.Offset
 		p.As = AMOVD
@@ -631,38 +637,38 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			if c.cursym.Func().Text.From.Sym.Wrapper() {
 				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
 				//
-				//	MOV  g_panic(g), R1
+				//	MOV  g_panic(g), RT1
 				//	CBNZ checkargp
 				// end:
 				//	NOP
 				// ... function body ...
 				// checkargp:
-				//	MOV  panic_argp(R1), R2
-				//	ADD  $(autosize+8), RSP, R3
-				//	CMP  R2, R3
+				//	MOV  panic_argp(RT1), RT2
+				//	ADD  $(autosize+8), RSP, R20
+				//	CMP  RT2, R20
 				//	BNE  end
-				//	ADD  $8, RSP, R4
-				//	MOVD R4, panic_argp(R1)
+				//	ADD  $8, RSP, R20
+				//	MOVD R20, panic_argp(RT1)
 				//	B    end
 				//
 				// The NOP is needed to give the jumps somewhere to land.
 				// It is a liblink NOP, not an ARM64 NOP: it encodes to 0 instruction bytes.
 				q = q1
 
-				// MOV g_panic(g), R1
+				// MOV g_panic(g), RT1
 				q = obj.Appendp(q, c.newprog)
 				q.As = AMOVD
 				q.From.Type = obj.TYPE_MEM
 				q.From.Reg = REGG
 				q.From.Offset = 4 * int64(c.ctxt.Arch.PtrSize) // G.panic
 				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_R1
+				q.To.Reg = REGRT1
 
-				// CBNZ R1, checkargp
+				// CBNZ RT1, checkargp
 				cbnz := obj.Appendp(q, c.newprog)
 				cbnz.As = ACBNZ
 				cbnz.From.Type = obj.TYPE_REG
-				cbnz.From.Reg = REG_R1
+				cbnz.From.Reg = REGRT1
 				cbnz.To.Type = obj.TYPE_BRANCH
 
 				// Empty branch target at the top of the function body
@@ -674,33 +680,33 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				for last = end; last.Link != nil; last = last.Link {
 				}
 
-				// MOV panic_argp(R1), R2
+				// MOV panic_argp(RT1), RT2
 				mov := obj.Appendp(last, c.newprog)
 				mov.As = AMOVD
 				mov.From.Type = obj.TYPE_MEM
-				mov.From.Reg = REG_R1
+				mov.From.Reg = REGRT1
 				mov.From.Offset = 0 // Panic.argp
 				mov.To.Type = obj.TYPE_REG
-				mov.To.Reg = REG_R2
+				mov.To.Reg = REGRT2
 
 				// CBNZ branches to the MOV above
 				cbnz.To.SetTarget(mov)
 
-				// ADD $(autosize+8), SP, R3
+				// ADD $(autosize+8), SP, R20
 				q = obj.Appendp(mov, c.newprog)
 				q.As = AADD
 				q.From.Type = obj.TYPE_CONST
 				q.From.Offset = int64(c.autosize) + 8
 				q.Reg = REGSP
 				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_R3
+				q.To.Reg = REG_R20
 
-				// CMP R2, R3
+				// CMP RT2, R20
 				q = obj.Appendp(q, c.newprog)
 				q.As = ACMP
 				q.From.Type = obj.TYPE_REG
-				q.From.Reg = REG_R2
-				q.Reg = REG_R3
+				q.From.Reg = REGRT2
+				q.Reg = REG_R20
 
 				// BNE end
 				q = obj.Appendp(q, c.newprog)
@@ -708,22 +714,22 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q.To.Type = obj.TYPE_BRANCH
 				q.To.SetTarget(end)
 
-				// ADD $8, SP, R4
+				// ADD $8, SP, R20
 				q = obj.Appendp(q, c.newprog)
 				q.As = AADD
 				q.From.Type = obj.TYPE_CONST
 				q.From.Offset = 8
 				q.Reg = REGSP
 				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_R4
+				q.To.Reg = REG_R20
 
-				// MOV R4, panic_argp(R1)
+				// MOV R20, panic_argp(RT1)
 				q = obj.Appendp(q, c.newprog)
 				q.As = AMOVD
 				q.From.Type = obj.TYPE_REG
-				q.From.Reg = REG_R4
+				q.From.Reg = REG_R20
 				q.To.Type = obj.TYPE_MEM
-				q.To.Reg = REG_R1
+				q.To.Reg = REGRT1
 				q.To.Offset = 0 // Panic.argp
 
 				// B end
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index 24fb5a19dec5b1dd48f7da55a4dd79be40ac2fe7..01466ea73606a6e7dadc86d939ee87a3b8df4db2 100644
--- a/src/cmd/internal/obj/objfile.go
+++ b/src/cmd/internal/obj/objfile.go
@@ -452,6 +452,11 @@ func (w *writer) contentHash(s *LSym) goobj.HashType {
 		binary.LittleEndian.PutUint64(tmp[6:14], uint64(r.Add))
 		h.Write(tmp[:])
 		rs := r.Sym
+		if rs == nil {
+			fmt.Printf("symbol: %s\n", s)
+			fmt.Printf("relocation: %#v\n", r)
+			panic("nil symbol target in relocation")
+		}
 		switch rs.PkgIdx {
 		case goobj.PkgIdxHashed64:
 			h.Write([]byte{0})
diff --git a/src/cmd/internal/obj/textflag.go b/src/cmd/internal/obj/textflag.go
index 881e1922031d8780a127cf8fdc85476b1b90de0a..5ae75027c2f2b544f7b7eb91d3f03fe7d33a7353 100644
--- a/src/cmd/internal/obj/textflag.go
+++ b/src/cmd/internal/obj/textflag.go
@@ -49,8 +49,8 @@ const (
 	// Function can call reflect.Type.Method or reflect.Type.MethodByName.
 	REFLECTMETHOD = 1024
 
-	// Function is the top of the call stack. Call stack unwinders should stop
-	// at this function.
+	// Function is the outermost frame of the call stack. Call stack unwinders
+	// should stop at this function.
 	TOPFRAME = 2048
 
 	// Function is an ABI wrapper.
diff --git a/src/cmd/internal/obj/wasm/wasmobj.go b/src/cmd/internal/obj/wasm/wasmobj.go
index ceeae7a257cdcc33313b85c31715fe53ead79a74..4d276db678041b0d4c9b80d75475c1e565a80d87 100644
--- a/src/cmd/internal/obj/wasm/wasmobj.go
+++ b/src/cmd/internal/obj/wasm/wasmobj.go
@@ -129,8 +129,6 @@ var (
 	morestackNoCtxt *obj.LSym
 	gcWriteBarrier  *obj.LSym
 	sigpanic        *obj.LSym
-	deferreturn     *obj.LSym
-	jmpdefer        *obj.LSym
 )
 
 const (
@@ -143,10 +141,6 @@ func instinit(ctxt *obj.Link) {
 	morestackNoCtxt = ctxt.Lookup("runtime.morestack_noctxt")
 	gcWriteBarrier = ctxt.LookupABI("runtime.gcWriteBarrier", obj.ABIInternal)
 	sigpanic = ctxt.LookupABI("runtime.sigpanic", obj.ABIInternal)
-	deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
-	// jmpdefer is defined in assembly as ABI0. The compiler will
-	// generate a direct ABI0 call from Go, so look for that.
-	jmpdefer = ctxt.LookupABI(`"".jmpdefer`, obj.ABI0)
 }
 
 func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
@@ -423,12 +417,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 				pcAfterCall-- // sigpanic expects to be called without advancing the pc
 			}
 
-			// jmpdefer manipulates the return address on the stack so deferreturn gets called repeatedly.
-			// Model this in WebAssembly with a loop.
-			if call.To.Sym == deferreturn {
-				p = appendp(p, ALoop)
-			}
-
 			// SP -= 8
 			p = appendp(p, AGet, regAddr(REG_SP))
 			p = appendp(p, AI32Const, constAddr(8))
@@ -479,15 +467,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 				break
 			}
 
-			// jmpdefer removes the frame of deferreturn from the Go stack.
-			// However, its WebAssembly function still returns normally,
-			// so we need to return from deferreturn without removing its
-			// stack frame (no RET), because the frame is already gone.
-			if call.To.Sym == jmpdefer {
-				p = appendp(p, AReturn)
-				break
-			}
-
 			// return value of call is on the top of the stack, indicating whether to unwind the WebAssembly stack
 			if call.As == ACALLNORESUME && call.To.Sym != sigpanic { // sigpanic unwinds the stack, but it never resumes
 				// trying to unwind WebAssembly stack but call has no resume point, terminate with error
@@ -500,21 +479,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 				unwindExitBranches = append(unwindExitBranches, p)
 			}
 
-			// jump to before the call if jmpdefer has reset the return address to the call's PC
-			if call.To.Sym == deferreturn {
-				// get PC_B from -8(SP)
-				p = appendp(p, AGet, regAddr(REG_SP))
-				p = appendp(p, AI32Const, constAddr(8))
-				p = appendp(p, AI32Sub)
-				p = appendp(p, AI32Load16U, constAddr(0))
-				p = appendp(p, ATee, regAddr(REG_PC_B))
-
-				p = appendp(p, AI32Const, constAddr(call.Pc))
-				p = appendp(p, AI32Eq)
-				p = appendp(p, ABrIf, constAddr(0))
-				p = appendp(p, AEnd) // end of Loop
-			}
-
 		case obj.ARET, ARETUNWIND:
 			ret := *p
 			p.As = obj.ANOP
diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index 17fa76727e6212061f46548664530c88570ff734..331a98dfef9a00df9399016f1c9daa2f07505aed 100644
--- a/src/cmd/internal/obj/x86/asm6.go
+++ b/src/cmd/internal/obj/x86/asm6.go
@@ -43,7 +43,6 @@ import (
 
 var (
 	plan9privates *obj.LSym
-	deferreturn   *obj.LSym
 )
 
 // Instruction layout.
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index e2732d53e3067b4d21c7774d84b180a90908ee22..183ca2ebe910cd7e15b02c738e2e69cf4aa48dbd 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -35,7 +35,6 @@ import (
 	"cmd/internal/objabi"
 	"cmd/internal/src"
 	"cmd/internal/sys"
-	"internal/buildcfg"
 	"log"
 	"math"
 	"path"
@@ -647,13 +646,12 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 
 	var regg int16
 	if !p.From.Sym.NoSplit() || p.From.Sym.Wrapper() {
-		if ctxt.Arch.Family == sys.AMD64 && buildcfg.Experiment.RegabiG && cursym.ABI() == obj.ABIInternal {
+		if ctxt.Arch.Family == sys.AMD64 && cursym.ABI() == obj.ABIInternal {
 			regg = REGG // use the g register directly in ABIInternal
 		} else {
 			p = obj.Appendp(p, newprog)
 			regg = REG_CX
 			if ctxt.Arch.Family == sys.AMD64 {
-				// Using this register means that stacksplit works w/ //go:registerparams even when !buildcfg.Experiment.RegabiG
 				regg = REGG // == REG_R14
 			}
 			p = load_g(ctxt, p, newprog, regg) // load g into regg
diff --git a/src/cmd/internal/objabi/funcid.go b/src/cmd/internal/objabi/funcid.go
index 93ebd7be943205e9044d5f0fe66fb66f9bda8d82..68f6a26a76ca4c8deb8d5d4f61e671480c111c8d 100644
--- a/src/cmd/internal/objabi/funcid.go
+++ b/src/cmd/internal/objabi/funcid.go
@@ -34,7 +34,6 @@ const (
 	FuncID_gogo
 	FuncID_gopanic
 	FuncID_handleAsyncEvent
-	FuncID_jmpdefer
 	FuncID_mcall
 	FuncID_morestack
 	FuncID_mstart
@@ -60,7 +59,6 @@ var funcIDs = map[string]FuncID{
 	"gogo":             FuncID_gogo,
 	"gopanic":          FuncID_gopanic,
 	"handleAsyncEvent": FuncID_handleAsyncEvent,
-	"jmpdefer":         FuncID_jmpdefer,
 	"main":             FuncID_runtime_main,
 	"mcall":            FuncID_mcall,
 	"morestack":        FuncID_morestack,
@@ -74,7 +72,6 @@ var funcIDs = map[string]FuncID{
 	// Don't show in call stack but otherwise not special.
 	"deferreturn":       FuncID_wrapper,
 	"runOpenDeferFrame": FuncID_wrapper,
-	"reflectcallSave":   FuncID_wrapper,
 	"deferCallSave":     FuncID_wrapper,
 }
 
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 416e5da39838fe73a68f663c6914869571a444ba..dd5dafc21b2361346c862c2a5af5a5abdb5b1a46 100644
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -408,6 +408,9 @@ func (d *deadcodePass) decodeMethodSig(ldr *loader.Loader, arch *sys.Arch, symId
 // Decode the method of interface type symbol symIdx at offset off.
 func (d *deadcodePass) decodeIfaceMethod(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, off int64) methodsig {
 	p := ldr.Data(symIdx)
+	if p == nil {
+		panic(fmt.Sprintf("missing symbol %q", ldr.SymName(symIdx)))
+	}
 	if decodetypeKind(arch, p)&kindMask != kindInterface {
 		panic(fmt.Sprintf("symbol %q is not an interface", ldr.SymName(symIdx)))
 	}
diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index c53d2408cbe5105fd9011b416e2d2d738241200d..98ab248e13f7034a9240ee900817aaf23e733491 100644
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -1190,7 +1190,7 @@ func (d *dwctxt) writeDirFileTables(unit *sym.CompilationUnit, lsu *loader.Symbo
 		// We can't use something that may be dead-code
 		// eliminated from a binary here. proc.go contains
 		// main and the scheduler, so it's not going anywhere.
-		if i := strings.Index(name, "runtime/proc.go"); i >= 0 {
+		if i := strings.Index(name, "runtime/proc.go"); i >= 0 && unit.Lib.Pkg == "runtime" {
 			d.dwmu.Lock()
 			if gdbscript == "" {
 				k := strings.Index(name, "runtime/proc.go")
diff --git a/src/cmd/link/internal/ld/dwarf_test.go b/src/cmd/link/internal/ld/dwarf_test.go
index 2f59c2fe0aa9484a0294170ad7e21fa6a0710ca0..543dd5caac7454ade0419564fdc0bff028e38e15 100644
--- a/src/cmd/link/internal/ld/dwarf_test.go
+++ b/src/cmd/link/internal/ld/dwarf_test.go
@@ -101,8 +101,11 @@ func gobuild(t *testing.T, dir string, testfile string, gcflags string) *builtFi
 	}
 
 	cmd := exec.Command(testenv.GoToolPath(t), "build", gcflags, "-o", dst, src)
-	if b, err := cmd.CombinedOutput(); err != nil {
-		t.Logf("build: %s\n", b)
+	b, err := cmd.CombinedOutput()
+	if len(b) != 0 {
+		t.Logf("## build output:\n%s", b)
+	}
+	if err != nil {
 		t.Fatalf("build error: %v", err)
 	}
 
diff --git a/src/cmd/link/internal/ld/elf.go b/src/cmd/link/internal/ld/elf.go
index 81011638bc5fae6b52cf2898d2849dced105c74d..93f974c5e032dc7ed0b9059014cca4b2e64000c0 100644
--- a/src/cmd/link/internal/ld/elf.go
+++ b/src/cmd/link/internal/ld/elf.go
@@ -16,6 +16,7 @@ import (
 	"fmt"
 	"internal/buildcfg"
 	"path/filepath"
+	"runtime"
 	"sort"
 	"strings"
 )
@@ -480,10 +481,6 @@ func Elfwritedynent(arch *sys.Arch, s *loader.SymbolBuilder, tag elf.DynTag, val
 	}
 }
 
-func elfwritedynentsym(ctxt *Link, s *loader.SymbolBuilder, tag elf.DynTag, t loader.Sym) {
-	Elfwritedynentsymplus(ctxt, s, tag, t, 0)
-}
-
 func Elfwritedynentsymplus(ctxt *Link, s *loader.SymbolBuilder, tag elf.DynTag, t loader.Sym, add int64) {
 	if elf64 {
 		s.AddUint64(ctxt.Arch, uint64(tag))
@@ -1472,24 +1469,24 @@ func (ctxt *Link) doelf() {
 		/*
 		 * .dynamic table
 		 */
-		elfwritedynentsym(ctxt, dynamic, elf.DT_HASH, hash.Sym())
+		elfWriteDynEntSym(ctxt, dynamic, elf.DT_HASH, hash.Sym())
 
-		elfwritedynentsym(ctxt, dynamic, elf.DT_SYMTAB, dynsym.Sym())
+		elfWriteDynEntSym(ctxt, dynamic, elf.DT_SYMTAB, dynsym.Sym())
 		if elf64 {
 			Elfwritedynent(ctxt.Arch, dynamic, elf.DT_SYMENT, ELF64SYMSIZE)
 		} else {
 			Elfwritedynent(ctxt.Arch, dynamic, elf.DT_SYMENT, ELF32SYMSIZE)
 		}
-		elfwritedynentsym(ctxt, dynamic, elf.DT_STRTAB, dynstr.Sym())
+		elfWriteDynEntSym(ctxt, dynamic, elf.DT_STRTAB, dynstr.Sym())
 		elfwritedynentsymsize(ctxt, dynamic, elf.DT_STRSZ, dynstr.Sym())
 		if elfRelType == ".rela" {
 			rela := ldr.LookupOrCreateSym(".rela", 0)
-			elfwritedynentsym(ctxt, dynamic, elf.DT_RELA, rela)
+			elfWriteDynEntSym(ctxt, dynamic, elf.DT_RELA, rela)
 			elfwritedynentsymsize(ctxt, dynamic, elf.DT_RELASZ, rela)
 			Elfwritedynent(ctxt.Arch, dynamic, elf.DT_RELAENT, ELF64RELASIZE)
 		} else {
 			rel := ldr.LookupOrCreateSym(".rel", 0)
-			elfwritedynentsym(ctxt, dynamic, elf.DT_REL, rel)
+			elfWriteDynEntSym(ctxt, dynamic, elf.DT_REL, rel)
 			elfwritedynentsymsize(ctxt, dynamic, elf.DT_RELSZ, rel)
 			Elfwritedynent(ctxt.Arch, dynamic, elf.DT_RELENT, ELF32RELSIZE)
 		}
@@ -1499,9 +1496,9 @@ func (ctxt *Link) doelf() {
 		}
 
 		if ctxt.IsPPC64() {
-			elfwritedynentsym(ctxt, dynamic, elf.DT_PLTGOT, plt.Sym())
+			elfWriteDynEntSym(ctxt, dynamic, elf.DT_PLTGOT, plt.Sym())
 		} else {
-			elfwritedynentsym(ctxt, dynamic, elf.DT_PLTGOT, gotplt.Sym())
+			elfWriteDynEntSym(ctxt, dynamic, elf.DT_PLTGOT, gotplt.Sym())
 		}
 
 		if ctxt.IsPPC64() {
@@ -1749,7 +1746,7 @@ func asmbElf(ctxt *Link) {
 		sh.Flags = uint64(elf.SHF_ALLOC)
 		sh.Addralign = 1
 
-		if interpreter == "" && buildcfg.GO_LDSO != "" {
+		if interpreter == "" && buildcfg.GOOS == runtime.GOOS && buildcfg.GOARCH == runtime.GOARCH && buildcfg.GO_LDSO != "" {
 			interpreter = buildcfg.GO_LDSO
 		}
 
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 4cfee4a1e7729a42e5756a9c502e200080493cf6..494fea5e724c1dae4578e6664e2f79356278621f 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -698,7 +698,9 @@ func (ctxt *Link) linksetup() {
 		Peinit(ctxt)
 	}
 
-	if ctxt.HeadType == objabi.Hdarwin && ctxt.LinkMode == LinkExternal {
+	if ctxt.LinkMode == LinkExternal {
+		// When external linking, we are creating an object file. The
+		// absolute address is irrelevant.
 		*FlagTextAddr = 0
 	}
 
diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go
index 05fd30236949671419e6fd0e7efa13b7763b575c..70e3e1284b9a1ac621741d2c6f843511257fc126 100644
--- a/src/cmd/link/internal/ld/pcln.go
+++ b/src/cmd/link/internal/ld/pcln.go
@@ -129,11 +129,10 @@ func computeDeferReturn(ctxt *Link, deferReturnSym, s loader.Sym) uint32 {
 	for ri := 0; ri < relocs.Count(); ri++ {
 		r := relocs.At(ri)
 		if target.IsWasm() && r.Type() == objabi.R_ADDR {
-			// Wasm does not have a live variable set at the deferreturn
-			// call itself. Instead it has one identified by the
-			// resumption point immediately preceding the deferreturn.
-			// The wasm code has a R_ADDR relocation which is used to
-			// set the resumption point to PC_B.
+			// wasm/ssa.go generates an ARESUMEPOINT just
+			// before the deferreturn call. The "PC" of
+			// the deferreturn call is stored in the
+			// R_ADDR relocation on the ARESUMEPOINT.
 			lastWasmAddr = uint32(r.Add())
 		}
 		if r.Type().IsDirectCall() && (r.Sym() == deferReturnSym || ldr.IsDeferReturnTramp(r.Sym())) {
diff --git a/src/cmd/link/internal/ld/pe.go b/src/cmd/link/internal/ld/pe.go
index 8eb4231c3ab2895f095e2b1197e92d60659eb177..871bf8de2b158f3710bc9125e12e995954b47a1f 100644
--- a/src/cmd/link/internal/ld/pe.go
+++ b/src/cmd/link/internal/ld/pe.go
@@ -1061,6 +1061,8 @@ func Peinit(ctxt *Link) {
 		// linker will honour that requirement.
 		PESECTALIGN = 32
 		PEFILEALIGN = 0
+		// We are creating an object file. The absolute address is irrelevant.
+		PEBASE = 0
 	}
 
 	var sh [16]pe.SectionHeader32
diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index 00f557875a939a0dc1addf0d9319ae64e628b1c0..1f5e333cfd54cd4848f139abf8113e65b825709f 100644
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -300,6 +300,7 @@ func putplan9sym(ctxt *Link, ldr *loader.Loader, s loader.Sym, char SymbolType)
 	ctxt.Out.Write8(uint8(t + 0x80)) /* 0x80 is variable length */
 
 	name := ldr.SymName(s)
+	name = mangleABIName(ctxt, ldr, s, name)
 	ctxt.Out.WriteString(name)
 	ctxt.Out.Write8(0)
 
diff --git a/src/cmd/link/internal/loadelf/ldelf.go b/src/cmd/link/internal/loadelf/ldelf.go
index c6956297f6c79f8ba62b7e68a6609a0579353b97..b4f565a153f658147b8dac5a4f6b2cd745c644c4 100644
--- a/src/cmd/link/internal/loadelf/ldelf.go
+++ b/src/cmd/link/internal/loadelf/ldelf.go
@@ -22,7 +22,7 @@ import (
 
 /*
 Derived from Plan 9 from User Space's src/libmach/elf.h, elf.c
-http://code.swtch.com/plan9port/src/tip/src/libmach/
+https://github.com/9fans/plan9port/tree/master/src/libmach/
 
 	Copyright © 2004 Russ Cox.
 	Portions Copyright © 2008-2010 Google Inc.
diff --git a/src/cmd/link/internal/loadmacho/ldmacho.go b/src/cmd/link/internal/loadmacho/ldmacho.go
index e7d9eebc33f792236e84bc0a9ae725756963f098..5402ecd74848522e9a23131796b7081631c9badb 100644
--- a/src/cmd/link/internal/loadmacho/ldmacho.go
+++ b/src/cmd/link/internal/loadmacho/ldmacho.go
@@ -18,7 +18,7 @@ import (
 
 /*
 Derived from Plan 9 from User Space's src/libmach/elf.h, elf.c
-http://code.swtch.com/plan9port/src/tip/src/libmach/
+https://github.com/9fans/plan9port/tree/master/src/libmach/
 
 	Copyright © 2004 Russ Cox.
 	Portions Copyright © 2008-2010 Google Inc.
diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 77d42cceda84b0f12bb240150de602b1cc515775..2b0b2dc4a17f932fe6d4e4e968f15eed8cbb4986 100644
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -547,14 +547,13 @@ const testFuncAlignSrc = `
 package main
 import (
 	"fmt"
-	"reflect"
 )
 func alignPc()
+var alignPcFnAddr uintptr
 
 func main() {
-	addr := reflect.ValueOf(alignPc).Pointer()
-	if (addr % 512) != 0 {
-		fmt.Printf("expected 512 bytes alignment, got %v\n", addr)
+	if alignPcFnAddr % 512 != 0 {
+		fmt.Printf("expected 512 bytes alignment, got %v\n", alignPcFnAddr)
 	} else {
 		fmt.Printf("PASS")
 	}
@@ -569,6 +568,9 @@ TEXT	·alignPc(SB),NOSPLIT, $0-0
 	PCALIGN	$512
 	MOVD	$3, R1
 	RET
+
+GLOBL	·alignPcFnAddr(SB),RODATA,$8
+DATA	·alignPcFnAddr(SB)/8,$·alignPc(SB)
 `
 
 // TestFuncAlign verifies that the address of a function can be aligned
diff --git a/src/cmd/trace/annotations.go b/src/cmd/trace/annotations.go
index 9b45457436bda9966ec698eea03b55718a468f24..1c0dad56d849e6af89f30f5cf405e0598d72f967 100644
--- a/src/cmd/trace/annotations.go
+++ b/src/cmd/trace/annotations.go
@@ -407,10 +407,7 @@ func (tasks allTasks) task(taskID uint64) *taskDesc {
 		return t
 	}
 
-	t = &taskDesc{
-		id:         taskID,
-		goroutines: make(map[uint64]struct{}),
-	}
+	t = newTaskDesc(taskID)
 	tasks[taskID] = t
 	return t
 }
diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
index eb0016b18f15356465370b9398516059e0b8e79c..7b82d0b6ddb5a5f3ceaa1501ef7b92fb128066f6 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
@@ -51,6 +51,11 @@ type asmArch struct {
 	bigEndian bool
 	stack     string
 	lr        bool
+	// retRegs is a list of registers for return value in register ABI (ABIInternal).
+	// For now, as we only check whether we write to any result, here we only need to
+	// include the first integer register and first floating-point register. Accessing
+	// any of them counts as writing to result.
+	retRegs []string
 	// calculated during initialization
 	sizes    types.Sizes
 	intSize  int
@@ -79,8 +84,8 @@ type asmVar struct {
 var (
 	asmArch386      = asmArch{name: "386", bigEndian: false, stack: "SP", lr: false}
 	asmArchArm      = asmArch{name: "arm", bigEndian: false, stack: "R13", lr: true}
-	asmArchArm64    = asmArch{name: "arm64", bigEndian: false, stack: "RSP", lr: true}
-	asmArchAmd64    = asmArch{name: "amd64", bigEndian: false, stack: "SP", lr: false}
+	asmArchArm64    = asmArch{name: "arm64", bigEndian: false, stack: "RSP", lr: true, retRegs: []string{"R0", "F0"}}
+	asmArchAmd64    = asmArch{name: "amd64", bigEndian: false, stack: "SP", lr: false, retRegs: []string{"AX", "X0"}}
 	asmArchMips     = asmArch{name: "mips", bigEndian: true, stack: "R29", lr: true}
 	asmArchMipsLE   = asmArch{name: "mipsle", bigEndian: false, stack: "R29", lr: true}
 	asmArchMips64   = asmArch{name: "mips64", bigEndian: true, stack: "R29", lr: true}
@@ -137,7 +142,7 @@ var (
 	asmSP        = re(`[^+\-0-9](([0-9]+)\(([A-Z0-9]+)\))`)
 	asmOpcode    = re(`^\s*(?:[A-Z0-9a-z_]+:)?\s*([A-Z]+)\s*([^,]*)(?:,\s*(.*))?`)
 	ppc64Suff    = re(`([BHWD])(ZU|Z|U|BR)?$`)
-	abiSuff      = re(`^(.+)$`)
+	abiSuff      = re(`^(.+)<(ABI.+)>$`)
 )
 
 func run(pass *analysis.Pass) (interface{}, error) {
@@ -185,6 +190,7 @@ Files:
 		var (
 			fn                 *asmFunc
 			fnName             string
+			abi                string
 			localSize, argSize int
 			wroteSP            bool
 			noframe            bool
@@ -195,18 +201,22 @@ Files:
 		flushRet := func() {
 			if fn != nil && fn.vars["ret"] != nil && !haveRetArg && len(retLine) > 0 {
 				v := fn.vars["ret"]
+				resultStr := fmt.Sprintf("%d-byte ret+%d(FP)", v.size, v.off)
+				if abi == "ABIInternal" {
+					resultStr = "result register"
+				}
 				for _, line := range retLine {
-					pass.Reportf(analysisutil.LineStart(tf, line), "[%s] %s: RET without writing to %d-byte ret+%d(FP)", arch, fnName, v.size, v.off)
+					pass.Reportf(analysisutil.LineStart(tf, line), "[%s] %s: RET without writing to %s", arch, fnName, resultStr)
 				}
 			}
 			retLine = nil
 		}
-		trimABI := func(fnName string) string {
+		trimABI := func(fnName string) (string, string) {
 			m := abiSuff.FindStringSubmatch(fnName)
 			if m != nil {
-				return m[1]
+				return m[1], m[2]
 			}
-			return fnName
+			return fnName, ""
 		}
 		for lineno, line := range lines {
 			lineno++
@@ -273,11 +283,12 @@ Files:
 						// log.Printf("%s:%d: [%s] cannot check cross-package assembly function: %s is in package %s", fname, lineno, arch, fnName, pkgPath)
 						fn = nil
 						fnName = ""
+						abi = ""
 						continue
 					}
 				}
 				// Trim off optional ABI selector.
-				fnName := trimABI(fnName)
+				fnName, abi = trimABI(fnName)
 				flag := m[3]
 				fn = knownFunc[fnName][arch]
 				if fn != nil {
@@ -305,6 +316,7 @@ Files:
 				flushRet()
 				fn = nil
 				fnName = ""
+				abi = ""
 				continue
 			}
 
@@ -335,6 +347,15 @@ Files:
 				haveRetArg = true
 			}
 
+			if abi == "ABIInternal" && !haveRetArg {
+				for _, reg := range archDef.retRegs {
+					if strings.Contains(line, reg) {
+						haveRetArg = true
+						break
+					}
+				}
+			}
+
 			for _, m := range asmSP.FindAllStringSubmatch(line, -1) {
 				if m[3] != archDef.stack || wroteSP || noframe {
 					continue
diff --git a/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go b/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
index b949fc840791ccdc34a4251e71de764b82b71d08..5fe75b14c7573bf2d7140c00d2a3cbb0f3b19468 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
@@ -439,8 +439,10 @@ func (a *application) apply(parent ast.Node, name string, iter *iterator, n ast.
 		}
 
 	default:
-		if typeparams.IsListExpr(n) {
-			a.applyList(n, "ElemList")
+		if ix := typeparams.GetIndexExprData(n); ix != nil {
+			a.apply(n, "X", nil, ix.X)
+			// *ast.IndexExpr was handled above, so n must be an *ast.MultiIndexExpr.
+			a.applyList(n, "Indices")
 		} else {
 			panic(fmt.Sprintf("Apply: unexpected node type %T", n))
 		}
diff --git a/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go b/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go
index cffd7acbee71b88f064022bcb7e617aa1024b5a7..81e8fdcf0c1e5879ce93a73bd5a4ee9c6297b83e 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go
@@ -58,7 +58,7 @@ type Path string
 // - The only OT operator is Object.Type,
 //   which we encode as '.' because dot cannot appear in an identifier.
 // - The TT operators are encoded as [EKPRU].
-// - The OT operators are encoded as [AFMO];
+// - The TO operators are encoded as [AFMO];
 //   three of these (At,Field,Method) require an integer operand,
 //   which is encoded as a string of decimal digits.
 //   These indices are stable across different representations
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go
index ac377035ec63a342841c4e458a5e6b313e2475e2..c1038163f1a929cd19efd25915e522bad03d0964 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go
@@ -27,23 +27,23 @@ const (
 // RuneRoles detects the roles of each byte rune in an input string and stores it in the output
 // slice. The rune role depends on the input type. Stops when it parsed all the runes in the string
 // or when it filled the output. If output is nil, then it gets created.
-func RuneRoles(str string, reuse []RuneRole) []RuneRole {
+func RuneRoles(candidate []byte, reuse []RuneRole) []RuneRole {
 	var output []RuneRole
-	if cap(reuse) < len(str) {
-		output = make([]RuneRole, 0, len(str))
+	if cap(reuse) < len(candidate) {
+		output = make([]RuneRole, 0, len(candidate))
 	} else {
 		output = reuse[:0]
 	}
 
 	prev, prev2 := rtNone, rtNone
-	for i := 0; i < len(str); i++ {
-		r := rune(str[i])
+	for i := 0; i < len(candidate); i++ {
+		r := rune(candidate[i])
 
 		role := RNone
 
 		curr := rtLower
-		if str[i] <= unicode.MaxASCII {
-			curr = runeType(rt[str[i]] - '0')
+		if candidate[i] <= unicode.MaxASCII {
+			curr = runeType(rt[candidate[i]] - '0')
 		}
 
 		if curr == rtLower {
@@ -58,7 +58,7 @@ func RuneRoles(str string, reuse []RuneRole) []RuneRole {
 			if prev == rtUpper {
 				// This and previous characters are both upper case.
 
-				if i+1 == len(str) {
+				if i+1 == len(candidate) {
 					// This is last character, previous was also uppercase -> this is UCTail
 					// i.e., (current char is C): aBC / BC / ABC
 					role = RUCTail
@@ -118,11 +118,26 @@ func LastSegment(input string, roles []RuneRole) string {
 	return input[start+1 : end+1]
 }
 
-// ToLower transforms the input string to lower case, which is stored in the output byte slice.
+// fromChunks copies string chunks into the given buffer.
+func fromChunks(chunks []string, buffer []byte) []byte {
+	ii := 0
+	for _, chunk := range chunks {
+		for i := 0; i < len(chunk); i++ {
+			if ii >= cap(buffer) {
+				break
+			}
+			buffer[ii] = chunk[i]
+			ii++
+		}
+	}
+	return buffer[:ii]
+}
+
+// toLower transforms the input string to lower case, which is stored in the output byte slice.
 // The lower casing considers only ASCII values - non ASCII values are left unmodified.
 // Stops when parsed all input or when it filled the output slice. If output is nil, then it gets
 // created.
-func ToLower(input string, reuse []byte) []byte {
+func toLower(input []byte, reuse []byte) []byte {
 	output := reuse
 	if cap(reuse) < len(input) {
 		output = make([]byte, len(input))
@@ -130,7 +145,7 @@ func ToLower(input string, reuse []byte) []byte {
 
 	for i := 0; i < len(input); i++ {
 		r := rune(input[i])
-		if r <= unicode.MaxASCII {
+		if input[i] <= unicode.MaxASCII {
 			if 'A' <= r && r <= 'Z' {
 				r += 'a' - 'A'
 			}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go
index 16a643097de750828ba35e5648d6eda42563f06d..265cdcf1604c06cb5607369d60253e077af2871d 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go
@@ -51,8 +51,12 @@ type Matcher struct {
 	lastCandidateLen     int // in bytes
 	lastCandidateMatched bool
 
-	// Here we save the last candidate in lower-case. This is basically a byte slice we reuse for
-	// performance reasons, so the slice is not reallocated for every candidate.
+	// Reusable buffers to avoid allocating for every candidate.
+	//  - inputBuf stores the concatenated input chunks
+	//  - lowerBuf stores the last candidate in lower-case
+	//  - rolesBuf stores the calculated roles for each rune in the last
+	//    candidate.
+	inputBuf [MaxInputSize]byte
 	lowerBuf [MaxInputSize]byte
 	rolesBuf [MaxInputSize]RuneRole
 }
@@ -72,7 +76,7 @@ func NewMatcher(pattern string) *Matcher {
 
 	m := &Matcher{
 		pattern:      pattern,
-		patternLower: ToLower(pattern, nil),
+		patternLower: toLower([]byte(pattern), nil),
 	}
 
 	for i, c := range m.patternLower {
@@ -88,7 +92,7 @@ func NewMatcher(pattern string) *Matcher {
 		m.patternShort = m.patternLower
 	}
 
-	m.patternRoles = RuneRoles(pattern, nil)
+	m.patternRoles = RuneRoles([]byte(pattern), nil)
 
 	if len(pattern) > 0 {
 		maxCharScore := 4
@@ -102,10 +106,15 @@ func NewMatcher(pattern string) *Matcher {
 // This is not designed for parallel use. Multiple candidates must be scored sequentially.
 // Returns a score between 0 and 1 (0 - no match, 1 - perfect match).
 func (m *Matcher) Score(candidate string) float32 {
+	return m.ScoreChunks([]string{candidate})
+}
+
+func (m *Matcher) ScoreChunks(chunks []string) float32 {
+	candidate := fromChunks(chunks, m.inputBuf[:])
 	if len(candidate) > MaxInputSize {
 		candidate = candidate[:MaxInputSize]
 	}
-	lower := ToLower(candidate, m.lowerBuf[:])
+	lower := toLower(candidate, m.lowerBuf[:])
 	m.lastCandidateLen = len(candidate)
 
 	if len(m.pattern) == 0 {
@@ -174,7 +183,7 @@ func (m *Matcher) MatchedRanges() []int {
 	return ret
 }
 
-func (m *Matcher) match(candidate string, candidateLower []byte) bool {
+func (m *Matcher) match(candidate []byte, candidateLower []byte) bool {
 	i, j := 0, 0
 	for ; i < len(candidateLower) && j < len(m.patternLower); i++ {
 		if candidateLower[i] == m.patternLower[j] {
@@ -192,7 +201,7 @@ func (m *Matcher) match(candidate string, candidateLower []byte) bool {
 	return true
 }
 
-func (m *Matcher) computeScore(candidate string, candidateLower []byte) int {
+func (m *Matcher) computeScore(candidate []byte, candidateLower []byte) int {
 	pattLen, candLen := len(m.pattern), len(candidate)
 
 	for j := 0; j <= len(m.pattern); j++ {
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/symbol.go b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/symbol.go
new file mode 100644
index 0000000000000000000000000000000000000000..062f491fb5ce6e79b47ad6aaf6afbcf20ba11c58
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/symbol.go
@@ -0,0 +1,224 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fuzzy
+
+import (
+	"unicode"
+)
+
+// SymbolMatcher implements a fuzzy matching algorithm optimized for Go symbols
+// of the form:
+//  example.com/path/to/package.object.field
+//
+// Knowing that we are matching symbols like this allows us to make the
+// following optimizations:
+//  - We can incorporate right-to-left relevance directly into the score
+//    calculation.
+//  - We can match from right to left, discarding leading bytes if the input is
+//    too long.
+//  - We just take the right-most match without losing too much precision. This
+//    allows us to use an O(n) algorithm.
+//  - We can operate directly on chunked strings; in many cases we will
+//    be storing the package path and/or package name separately from the
+//    symbol or identifiers, so doing this avoids allocating strings.
+//  - We can return the index of the right-most match, allowing us to trim
+//    irrelevant qualification.
+//
+// This implementation is experimental, serving as a reference fast algorithm
+// to compare to the fuzzy algorithm implemented by Matcher.
+type SymbolMatcher struct {
+	// Using buffers of length 256 is both a reasonable size for most qualified
+	// symbols, and makes it easy to avoid bounds checks by using uint8 indexes.
+	pattern     [256]rune
+	patternLen  uint8
+	inputBuffer [256]rune   // avoid allocating when considering chunks
+	roles       [256]uint32 // which roles does a rune play (word start, etc.)
+	segments    [256]uint8  // how many segments from the right is each rune
+}
+
+const (
+	segmentStart uint32 = 1 << iota
+	wordStart
+	separator
+)
+
+// NewSymbolMatcher creates a SymbolMatcher that may be used to match the given
+// search pattern.
+//
+// Currently this matcher only accepts case-insensitive fuzzy patterns.
+//
+// TODO(rfindley):
+//  - implement smart-casing
+//  - implement space-separated groups
+//  - implement ', ^, and $ modifiers
+//
+// An empty pattern matches no input.
+func NewSymbolMatcher(pattern string) *SymbolMatcher {
+	m := &SymbolMatcher{}
+	for _, p := range pattern {
+		m.pattern[m.patternLen] = unicode.ToLower(p)
+		m.patternLen++
+		if m.patternLen == 255 || int(m.patternLen) == len(pattern) {
+			// break at 255 so that we can represent patternLen with a uint8.
+			break
+		}
+	}
+	return m
+}
+
+// Match looks for the right-most match of the search pattern within the symbol
+// represented by concatenating the given chunks, returning its offset and
+// score.
+//
+// If a match is found, the first return value will hold the absolute byte
+// offset within all chunks for the start of the symbol. In other words, the
+// index of the match within strings.Join(chunks, ""). If no match is found,
+// the first return value will be -1.
+//
+// The second return value will be the score of the match, which is always
+// between 0 and 1, inclusive. A score of 0 indicates no match.
+func (m *SymbolMatcher) Match(chunks []string) (int, float64) {
+	// Explicit behavior for an empty pattern.
+	//
+	// As a minor optimization, this also avoids nilness checks later on, since
+	// the compiler can prove that m != nil.
+	if m.patternLen == 0 {
+		return -1, 0
+	}
+
+	// First phase: populate the input buffer with lower-cased runes.
+	//
+	// We could also check for a forward match here, but since we'd have to write
+	// the entire input anyway this has negligible impact on performance.
+
+	var (
+		inputLen  = uint8(0)
+		modifiers = wordStart | segmentStart
+	)
+
+input:
+	for _, chunk := range chunks {
+		for _, r := range chunk {
+			if r == '.' || r == '/' {
+				modifiers |= separator
+			}
+			// optimization: avoid calls to unicode.ToLower, which can't be inlined.
+			l := r
+			if r <= unicode.MaxASCII {
+				if 'A' <= r && r <= 'Z' {
+					l = r + 'a' - 'A'
+				}
+			} else {
+				l = unicode.ToLower(r)
+			}
+			if l != r {
+				modifiers |= wordStart
+			}
+			m.inputBuffer[inputLen] = l
+			m.roles[inputLen] = modifiers
+			inputLen++
+			if m.roles[inputLen-1]&separator != 0 {
+				modifiers = wordStart | segmentStart
+			} else {
+				modifiers = 0
+			}
+			// TODO: we should prefer the right-most input if it overflows, rather
+			//       than the left-most as we're doing here.
+			if inputLen == 255 {
+				break input
+			}
+		}
+	}
+
+	// Second phase: find the right-most match, and count segments from the
+	// right.
+
+	var (
+		pi    = uint8(m.patternLen - 1) // pattern index
+		p     = m.pattern[pi]           // pattern rune
+		start = -1                      // start offset of match
+		rseg  = uint8(0)
+	)
+	const maxSeg = 3 // maximum number of segments from the right to count, for scoring purposes.
+
+	for ii := inputLen - 1; ; ii-- {
+		r := m.inputBuffer[ii]
+		if rseg < maxSeg && m.roles[ii]&separator != 0 {
+			rseg++
+		}
+		m.segments[ii] = rseg
+		if p == r {
+			if pi == 0 {
+				start = int(ii)
+				break
+			}
+			pi--
+			p = m.pattern[pi]
+		}
+		// Don't check ii >= 0 in the loop condition: ii is a uint8.
+		if ii == 0 {
+			break
+		}
+	}
+
+	if start < 0 {
+		// no match: skip scoring
+		return -1, 0
+	}
+
+	// Third phase: find the shortest match, and compute the score.
+
+	// Score is the average score for each character.
+	//
+	// A character score is the multiple of:
+	//   1. 1.0 if the character starts a segment, .8 if the character start a
+	//      mid-segment word, otherwise 0.6. This carries over to immediately
+	//      following characters.
+	//   2. 1.0 if the character is part of the last segment, otherwise
+	//      1.0-.2*, with a max segment count of 3.
+	//
+	// This is a very naive algorithm, but it is fast. There's lots of prior art
+	// here, and we should leverage it. For example, we could explicitly consider
+	// character distance, and exact matches of words or segments.
+	//
+	// Also note that this might not actually find the highest scoring match, as
+	// doing so could require a non-linear algorithm, depending on how the score
+	// is calculated.
+
+	pi = 0
+	p = m.pattern[pi]
+
+	const (
+		segStreak  = 1.0
+		wordStreak = 0.8
+		noStreak   = 0.6
+		perSegment = 0.2 // we count at most 3 segments above
+	)
+
+	streakBonus := noStreak
+	totScore := 0.0
+	for ii := uint8(start); ii < inputLen; ii++ {
+		r := m.inputBuffer[ii]
+		if r == p {
+			pi++
+			p = m.pattern[pi]
+			// Note: this could be optimized with some bit operations.
+			switch {
+			case m.roles[ii]&segmentStart != 0 && segStreak > streakBonus:
+				streakBonus = segStreak
+			case m.roles[ii]&wordStart != 0 && wordStreak > streakBonus:
+				streakBonus = wordStreak
+			}
+			totScore += streakBonus * (1.0 - float64(m.segments[ii])*perSegment)
+			if pi >= m.patternLen {
+				break
+			}
+		} else {
+			streakBonus = noStreak
+		}
+	}
+
+	return start, totScore / float64(m.patternLen)
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/doc.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/common.go
similarity index 59%
rename from src/cmd/vendor/golang.org/x/tools/internal/typeparams/doc.go
rename to src/cmd/vendor/golang.org/x/tools/internal/typeparams/common.go
index 5583947e21ffcbc433c176605c96d7db01997b21..9fc6b4beb88759089fb243529f6fc13df934de50 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/doc.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/common.go
@@ -9,3 +9,17 @@
 // This package exists to make it easier for tools to work with generic code,
 // while also compiling against older Go versions.
 package typeparams
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// A IndexExprData holds data from both ast.IndexExpr and the new
+// ast.MultiIndexExpr, which was introduced in Go 1.18.
+type IndexExprData struct {
+	X       ast.Expr   // expression
+	Lbrack  token.Pos  // position of "["
+	Indices []ast.Expr // index expressions
+	Rbrack  token.Pos  // position of "]"
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
index 3a0abc7c18ee02ea3658a7094f084d426b94b967..e975e476f668995555cdfac1c3eddbd1979c3d5f 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !typeparams || !go1.17
-// +build !typeparams !go1.17
+//go:build !typeparams || !go1.18
+// +build !typeparams !go1.18
 
 package typeparams
 
@@ -18,17 +18,25 @@ import (
 // environment.
 const Enabled = false
 
-// UnpackIndex extracts all index expressions from e. For non-generic code this
-// is always one expression: e.Index, but may be more than one expression for
-// generic type instantiation.
-func UnpackIndex(e *ast.IndexExpr) []ast.Expr {
-	return []ast.Expr{e.Index}
-}
-
-// IsListExpr reports whether n is an *ast.ListExpr, which is a new node type
-// introduced to hold type arguments for generic type instantiation.
-func IsListExpr(n ast.Node) bool {
-	return false
+// GetIndexExprData extracts data from AST nodes that represent index
+// expressions.
+//
+// For an ast.IndexExpr, the resulting IndexExprData will have exactly one
+// index expression. For an ast.MultiIndexExpr (go1.18+), it may have a
+// variable number of index expressions.
+//
+// For nodes that don't represent index expressions, GetIndexExprData returns
+// nil.
+func GetIndexExprData(n ast.Node) *IndexExprData {
+	if e, _ := n.(*ast.IndexExpr); e != nil {
+		return &IndexExprData{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}
+	}
+	return nil
 }
 
 // ForTypeDecl extracts the (possibly nil) type parameter node list from n.
@@ -47,11 +55,6 @@ func ForSignature(*types.Signature) []*types.TypeName {
 	return nil
 }
 
-// HasTypeSet reports if iface has a type set.
-func HasTypeSet(*types.Interface) bool {
-	return false
-}
-
 // IsComparable reports if iface is the comparable interface.
 func IsComparable(*types.Interface) bool {
 	return false
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
index 6b7958af060d80d4896667f28cc022fab2f4a165..be6b0525f6134769d487e4db317afd6ae5e64e78 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams && go1.17
-// +build typeparams,go1.17
+//go:build typeparams && go1.18
+// +build typeparams,go1.18
 
 package typeparams
 
@@ -18,26 +18,30 @@ import (
 // environment.
 const Enabled = true
 
-// UnpackIndex extracts all index expressions from e. For non-generic code this
-// is always one expression: e.Index, but may be more than one expression for
-// generic type instantiation.
-func UnpackIndex(e *ast.IndexExpr) []ast.Expr {
-	if x, _ := e.Index.(*ast.ListExpr); x != nil {
-		return x.ElemList
-	}
-	if e.Index != nil {
-		return []ast.Expr{e.Index}
+// GetIndexExprData extracts data from AST nodes that represent index
+// expressions.
+//
+// For an ast.IndexExpr, the resulting IndexExprData will have exactly one
+// index expression. For an ast.MultiIndexExpr (go1.18+), it may have a
+// variable number of index expressions.
+//
+// For nodes that don't represent index expressions, GetIndexExprData returns
+// nil.
+func GetIndexExprData(n ast.Node) *IndexExprData {
+	switch e := n.(type) {
+	case *ast.IndexExpr:
+		return &IndexExprData{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}
+	case *ast.MultiIndexExpr:
+		return (*IndexExprData)(e)
 	}
 	return nil
 }
 
-// IsListExpr reports whether n is an *ast.ListExpr, which is a new node type
-// introduced to hold type arguments for generic type instantiation.
-func IsListExpr(n ast.Node) bool {
-	_, ok := n.(*ast.ListExpr)
-	return ok
-}
-
 // ForTypeDecl extracts the (possibly nil) type parameter node list from n.
 func ForTypeDecl(n *ast.TypeSpec) *ast.FieldList {
 	return n.TParams
@@ -54,12 +58,7 @@ func ForFuncDecl(n *ast.FuncDecl) *ast.FieldList {
 // ForSignature extracts the (possibly empty) type parameter object list from
 // sig.
 func ForSignature(sig *types.Signature) []*types.TypeName {
-	return sig.TParams()
-}
-
-// HasTypeSet reports if iface has a type set.
-func HasTypeSet(iface *types.Interface) bool {
-	return iface.HasTypeList()
+	return tparamsSlice(sig.TParams())
 }
 
 // IsComparable reports if iface is the comparable interface.
@@ -76,7 +75,18 @@ func IsConstraint(iface *types.Interface) bool {
 // ForNamed extracts the (possibly empty) type parameter object list from
 // named.
 func ForNamed(named *types.Named) []*types.TypeName {
-	return named.TParams()
+	return tparamsSlice(named.TParams())
+}
+
+func tparamsSlice(tparams *types.TypeParams) []*types.TypeName {
+	if tparams.Len() == 0 {
+		return nil
+	}
+	result := make([]*types.TypeName, tparams.Len())
+	for i := 0; i < tparams.Len(); i++ {
+		result[i] = tparams.At(i)
+	}
+	return result
 }
 
 // NamedTArgs extracts the (possibly empty) type argument list from named.
diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index e032ccc2c753243907ec79e19c250b1c7b615993..eed06a9f5017213987dd533144dc809937f39b54 100644
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -48,7 +48,7 @@ golang.org/x/sys/windows
 # golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 ## explicit; go 1.17
 golang.org/x/term
-# golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6
+# golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151
 ## explicit; go 1.17
 golang.org/x/tools/cover
 golang.org/x/tools/go/analysis
diff --git a/src/cmd/vet/testdata/print/print.go b/src/cmd/vet/testdata/print/print.go
index be42a377175bb6f12b28155c54e621cf74f8a6c7..46240e87bfd837c275b2f430091b1954bd06072f 100644
--- a/src/cmd/vet/testdata/print/print.go
+++ b/src/cmd/vet/testdata/print/print.go
@@ -491,10 +491,10 @@ type recursiveStringer int
 func (s recursiveStringer) String() string {
 	_ = fmt.Sprintf("%d", s)
 	_ = fmt.Sprintf("%#v", s)
-	_ = fmt.Sprintf("%v", s)  // ERROR "Sprintf format %v with arg s causes recursive \(cmd/vet/testdata/print\.recursiveStringer\)\.String method call"
-	_ = fmt.Sprintf("%v", &s) // ERROR "Sprintf format %v with arg &s causes recursive \(cmd/vet/testdata/print\.recursiveStringer\)\.String method call"
+	_ = fmt.Sprintf("%v", s)  // ERROR "Sprintf format %v with arg s causes recursive .*String method call"
+	_ = fmt.Sprintf("%v", &s) // ERROR "Sprintf format %v with arg &s causes recursive .*String method call"
 	_ = fmt.Sprintf("%T", s)  // ok; does not recursively call String
-	return fmt.Sprintln(s)    // ERROR "Sprintln arg s causes recursive call to \(cmd/vet/testdata/print\.recursiveStringer\)\.String method"
+	return fmt.Sprintln(s)    // ERROR "Sprintln arg s causes recursive call to .*String method"
 }
 
 type recursivePtrStringer int
@@ -502,7 +502,7 @@ type recursivePtrStringer int
 func (p *recursivePtrStringer) String() string {
 	_ = fmt.Sprintf("%v", *p)
 	_ = fmt.Sprint(&p)     // ok; prints address
-	return fmt.Sprintln(p) // ERROR "Sprintln arg p causes recursive call to \(\*cmd/vet/testdata/print\.recursivePtrStringer\)\.String method"
+	return fmt.Sprintln(p) // ERROR "Sprintln arg p causes recursive call to .*String method"
 }
 
 type BoolFormatter bool
diff --git a/src/crypto/ed25519/internal/edwards25519/tables.go b/src/crypto/ed25519/internal/edwards25519/tables.go
index beec956bf7e0a5d6df19297844808413d5f20708..5ca40f7bfa7a87f1b54ff65ced24d56db7142e6a 100644
--- a/src/crypto/ed25519/internal/edwards25519/tables.go
+++ b/src/crypto/ed25519/internal/edwards25519/tables.go
@@ -40,7 +40,7 @@ func (v *projLookupTable) FromP3(q *Point) {
 	for i := 0; i < 7; i++ {
 		// Compute (i+1)*Q as Q + i*Q and convert to a ProjCached
 		// This is needlessly complicated because the API has explicit
-		// recievers instead of creating stack objects and relying on RVO
+		// receivers instead of creating stack objects and relying on RVO
 		v.points[i+1].FromP3(tmpP3.fromP1xP1(tmpP1xP1.Add(q, &v.points[i])))
 	}
 }
diff --git a/src/crypto/rand/rand_getentropy.go b/src/crypto/rand/rand_getentropy.go
index f82018a4951c743c82f15c28b82262b601112f27..dd725372ad918a85d533b3dc30e213d49616bcd7 100644
--- a/src/crypto/rand/rand_getentropy.go
+++ b/src/crypto/rand/rand_getentropy.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build darwin || openbsd
-// +build darwin openbsd
+//go:build (darwin && !ios) || openbsd
+// +build darwin,!ios openbsd
 
 package rand
 
diff --git a/src/crypto/sha256/sha256.go b/src/crypto/sha256/sha256.go
index e1cccf65a60307517d7adecf7dcefdbd47d88aa5..659531dc716f7f7109edd9c851b2a19d0aef477c 100644
--- a/src/crypto/sha256/sha256.go
+++ b/src/crypto/sha256/sha256.go
@@ -259,12 +259,12 @@ func Sum256(data []byte) [Size]byte {
 }
 
 // Sum224 returns the SHA224 checksum of the data.
-func Sum224(data []byte) (sum224 [Size224]byte) {
+func Sum224(data []byte) [Size224]byte {
 	var d digest
 	d.is224 = true
 	d.Reset()
 	d.Write(data)
 	sum := d.checkSum()
-	copy(sum224[:], sum[:Size224])
-	return
+	ap := (*[Size224]byte)(sum[:])
+	return *ap
 }
diff --git a/src/crypto/sha512/sha512.go b/src/crypto/sha512/sha512.go
index 9c143a2a2817786095b94b2775db18210ff3a7be..d5715558c0484b40706d37e6957849e1874dc1b7 100644
--- a/src/crypto/sha512/sha512.go
+++ b/src/crypto/sha512/sha512.go
@@ -337,31 +337,31 @@ func Sum512(data []byte) [Size]byte {
 }
 
 // Sum384 returns the SHA384 checksum of the data.
-func Sum384(data []byte) (sum384 [Size384]byte) {
+func Sum384(data []byte) [Size384]byte {
 	d := digest{function: crypto.SHA384}
 	d.Reset()
 	d.Write(data)
 	sum := d.checkSum()
-	copy(sum384[:], sum[:Size384])
-	return
+	ap := (*[Size384]byte)(sum[:])
+	return *ap
 }
 
 // Sum512_224 returns the Sum512/224 checksum of the data.
-func Sum512_224(data []byte) (sum224 [Size224]byte) {
+func Sum512_224(data []byte) [Size224]byte {
 	d := digest{function: crypto.SHA512_224}
 	d.Reset()
 	d.Write(data)
 	sum := d.checkSum()
-	copy(sum224[:], sum[:Size224])
-	return
+	ap := (*[Size224]byte)(sum[:])
+	return *ap
 }
 
 // Sum512_256 returns the Sum512/256 checksum of the data.
-func Sum512_256(data []byte) (sum256 [Size256]byte) {
+func Sum512_256(data []byte) [Size256]byte {
 	d := digest{function: crypto.SHA512_256}
 	d.Reset()
 	d.Write(data)
 	sum := d.checkSum()
-	copy(sum256[:], sum[:Size256])
-	return
+	ap := (*[Size256]byte)(sum[:])
+	return *ap
 }
diff --git a/src/crypto/x509/parser.go b/src/crypto/x509/parser.go
index f085162a4e88be3d998cdb1bdfebb61282cdee0f..c2770f3f08dc0a2812ee93627a4662f1c1d7c95f 100644
--- a/src/crypto/x509/parser.go
+++ b/src/crypto/x509/parser.go
@@ -214,16 +214,16 @@ func parseValidity(der cryptobyte.String) (time.Time, time.Time, error) {
 func parseExtension(der cryptobyte.String) (pkix.Extension, error) {
 	var ext pkix.Extension
 	if !der.ReadASN1ObjectIdentifier(&ext.Id) {
-		return ext, errors.New("x509: malformed extention OID field")
+		return ext, errors.New("x509: malformed extension OID field")
 	}
 	if der.PeekASN1Tag(cryptobyte_asn1.BOOLEAN) {
 		if !der.ReadASN1Boolean(&ext.Critical) {
-			return ext, errors.New("x509: malformed extention critical field")
+			return ext, errors.New("x509: malformed extension critical field")
 		}
 	}
 	var val cryptobyte.String
 	if !der.ReadASN1(&val, cryptobyte_asn1.OCTET_STRING) {
-		return ext, errors.New("x509: malformed extention value field")
+		return ext, errors.New("x509: malformed extension value field")
 	}
 	ext.Value = val
 	return ext, nil
diff --git a/src/go.mod b/src/go.mod
index 379dcf504e5316fe43a502bc12e92411650dd9d6..1fb8cbfcbe07155891d25e5e60ccd8fbf5062dc4 100644
--- a/src/go.mod
+++ b/src/go.mod
@@ -1,6 +1,6 @@
 module std
 
-go 1.17
+go 1.18
 
 require (
 	golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e
diff --git a/src/go.sum b/src/go.sum
index 6e869b96f711b2edf6bbbd876a638649313c6b98..b3de6c526c98c72c2029a8c354706653dba751b5 100644
--- a/src/go.sum
+++ b/src/go.sum
@@ -1,15 +1,8 @@
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e h1:8foAy0aoO5GkqCvAEJ4VC4P3zksTg4X4aJCDpZzmgQI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
-golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210510120150-4163338589ed h1:p9UgmWI9wKpfYmgaV/IZKGdXc5qEK45tDwwwDyjS26I=
 golang.org/x/net v0.0.0-20210510120150-4163338589ed/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 h1:yhBbb4IRs2HS9PPlAg6DMC6mUOKexJBNsLf4Z+6En1Q=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7-0.20210503195748-5c7c50ebbd4f h1:yQJrRE0hDxDFmZLlRaw+3vusO4fwNHgHIjUOMO7bHYI=
 golang.org/x/text v0.3.7-0.20210503195748-5c7c50ebbd4f/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
-golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 337c87fd797351c344bf3e4b2ea01c20b3235c2e..b0f133056425652958430342ca433dce4b732656 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -344,6 +344,15 @@ type (
 		Rbrack token.Pos // position of "]"
 	}
 
+	// A MultiIndexExpr node represents an expression followed by multiple
+	// indices.
+	MultiIndexExpr struct {
+		X       Expr      // expression
+		Lbrack  token.Pos // position of "["
+		Indices []Expr    // index expressions
+		Rbrack  token.Pos // position of "]"
+	}
+
 	// A SliceExpr node represents an expression followed by slice indices.
 	SliceExpr struct {
 		X      Expr      // expression
@@ -440,6 +449,14 @@ type (
 
 	// Pointer types are represented via StarExpr nodes.
 
+	// A FuncType node represents a function type.
+	FuncType struct {
+		Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
+		TParams *FieldList // type parameters; or nil
+		Params  *FieldList // (incoming) parameters; non-nil
+		Results *FieldList // (outgoing) results; or nil
+	}
+
 	// An InterfaceType node represents an interface type.
 	InterfaceType struct {
 		Interface  token.Pos  // position of "interface" keyword
@@ -479,6 +496,7 @@ func (x *CompositeLit) Pos() token.Pos {
 func (x *ParenExpr) Pos() token.Pos      { return x.Lparen }
 func (x *SelectorExpr) Pos() token.Pos   { return x.X.Pos() }
 func (x *IndexExpr) Pos() token.Pos      { return x.X.Pos() }
+func (x *MultiIndexExpr) Pos() token.Pos { return x.X.Pos() }
 func (x *SliceExpr) Pos() token.Pos      { return x.X.Pos() }
 func (x *TypeAssertExpr) Pos() token.Pos { return x.X.Pos() }
 func (x *CallExpr) Pos() token.Pos       { return x.Fun.Pos() }
@@ -512,6 +530,7 @@ func (x *CompositeLit) End() token.Pos   { return x.Rbrace + 1 }
 func (x *ParenExpr) End() token.Pos      { return x.Rparen + 1 }
 func (x *SelectorExpr) End() token.Pos   { return x.Sel.End() }
 func (x *IndexExpr) End() token.Pos      { return x.Rbrack + 1 }
+func (x *MultiIndexExpr) End() token.Pos { return x.Rbrack + 1 }
 func (x *SliceExpr) End() token.Pos      { return x.Rbrack + 1 }
 func (x *TypeAssertExpr) End() token.Pos { return x.Rparen + 1 }
 func (x *CallExpr) End() token.Pos       { return x.Rparen + 1 }
@@ -543,6 +562,7 @@ func (*CompositeLit) exprNode()   {}
 func (*ParenExpr) exprNode()      {}
 func (*SelectorExpr) exprNode()   {}
 func (*IndexExpr) exprNode()      {}
+func (*MultiIndexExpr) exprNode() {}
 func (*SliceExpr) exprNode()      {}
 func (*TypeAssertExpr) exprNode() {}
 func (*CallExpr) exprNode()       {}
@@ -892,6 +912,16 @@ type (
 		Values  []Expr        // initial values; or nil
 		Comment *CommentGroup // line comments; or nil
 	}
+
+	// A TypeSpec node represents a type declaration (TypeSpec production).
+	TypeSpec struct {
+		Doc     *CommentGroup // associated documentation; or nil
+		Name    *Ident        // type name
+		TParams *FieldList    // type parameters; or nil
+		Assign  token.Pos     // position of '=', if any
+		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
+		Comment *CommentGroup // line comments; or nil
+	}
 )
 
 // Pos and End implementations for spec nodes.
diff --git a/src/go/ast/ast_notypeparams.go b/src/go/ast/ast_notypeparams.go
deleted file mode 100644
index fa132fba85892fca8fa79cc321eff5d75e42150d..0000000000000000000000000000000000000000
--- a/src/go/ast/ast_notypeparams.go
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package ast
-
-import "go/token"
-
-type (
-	// A FuncType node represents a function type.
-	FuncType struct {
-		Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
-		Params  *FieldList // (incoming) parameters; non-nil
-		Results *FieldList // (outgoing) results; or nil
-	}
-
-	// A TypeSpec node represents a type declaration (TypeSpec production).
-	TypeSpec struct {
-		Doc     *CommentGroup // associated documentation; or nil
-		Name    *Ident        // type name
-		Assign  token.Pos     // position of '=', if any
-		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
-		Comment *CommentGroup // line comments; or nil
-	}
-)
diff --git a/src/go/ast/ast_typeparams.go b/src/go/ast/ast_typeparams.go
deleted file mode 100644
index 24fdc5f1317e5f2cd1a6c27be8aac26bc8873273..0000000000000000000000000000000000000000
--- a/src/go/ast/ast_typeparams.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package ast
-
-import "go/token"
-
-type (
-	// A FuncType node represents a function type.
-	FuncType struct {
-		Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
-		TParams *FieldList // type parameters; or nil
-		Params  *FieldList // (incoming) parameters; non-nil
-		Results *FieldList // (outgoing) results; or nil
-	}
-
-	// A TypeSpec node represents a type declaration (TypeSpec production).
-	TypeSpec struct {
-		Doc     *CommentGroup // associated documentation; or nil
-		Name    *Ident        // type name
-		TParams *FieldList    // type parameters; or nil
-		Assign  token.Pos     // position of '=', if any
-		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
-		Comment *CommentGroup // line comments; or nil
-	}
-
-	// A ListExpr node represents a list of expressions separated by commas.
-	// ListExpr nodes are used as index in IndexExpr nodes representing type
-	// or function instantiations with more than one type argument.
-	ListExpr struct {
-		ElemList []Expr
-	}
-)
-
-func (*ListExpr) exprNode() {}
-func (x *ListExpr) Pos() token.Pos {
-	if len(x.ElemList) > 0 {
-		return x.ElemList[0].Pos()
-	}
-	return token.NoPos
-}
-func (x *ListExpr) End() token.Pos {
-	if len(x.ElemList) > 0 {
-		return x.ElemList[len(x.ElemList)-1].End()
-	}
-	return token.NoPos
-}
diff --git a/src/go/ast/walk.go b/src/go/ast/walk.go
index 9224264e291e2fc8904fc208d94d0915f2e626f4..c8abc40972842157dfaee016b5d669829ba51cf8 100644
--- a/src/go/ast/walk.go
+++ b/src/go/ast/walk.go
@@ -4,6 +4,8 @@
 
 package ast
 
+import "fmt"
+
 // A Visitor's Visit method is invoked for each node encountered by Walk.
 // If the result visitor w is not nil, Walk visits each of the children
 // of node with the visitor w, followed by a call of w.Visit(nil).
@@ -114,6 +116,12 @@ func Walk(v Visitor, node Node) {
 		Walk(v, n.X)
 		Walk(v, n.Index)
 
+	case *MultiIndexExpr:
+		Walk(v, n.X)
+		for _, index := range n.Indices {
+			Walk(v, index)
+		}
+
 	case *SliceExpr:
 		Walk(v, n.X)
 		if n.Low != nil {
@@ -161,7 +169,9 @@ func Walk(v Visitor, node Node) {
 		Walk(v, n.Fields)
 
 	case *FuncType:
-		walkFuncTypeParams(v, n)
+		if n.TParams != nil {
+			Walk(v, n.TParams)
+		}
 		if n.Params != nil {
 			Walk(v, n.Params)
 		}
@@ -316,7 +326,9 @@ func Walk(v Visitor, node Node) {
 			Walk(v, n.Doc)
 		}
 		Walk(v, n.Name)
-		walkTypeSpecParams(v, n)
+		if n.TParams != nil {
+			Walk(v, n.TParams)
+		}
 		Walk(v, n.Type)
 		if n.Comment != nil {
 			Walk(v, n.Comment)
@@ -363,7 +375,7 @@ func Walk(v Visitor, node Node) {
 		}
 
 	default:
-		walkOtherNodes(v, n)
+		panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
 	}
 
 	v.Visit(nil)
diff --git a/src/go/ast/walk_notypeparams.go b/src/go/ast/walk_notypeparams.go
deleted file mode 100644
index d43e13dd11ad76dffeadc38b85f7b0507247877f..0000000000000000000000000000000000000000
--- a/src/go/ast/walk_notypeparams.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package ast
-
-import "fmt"
-
-func walkFuncTypeParams(v Visitor, n *FuncType) {}
-func walkTypeSpecParams(v Visitor, n *TypeSpec) {}
-
-func walkOtherNodes(v Visitor, n Node) {
-	panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
-}
diff --git a/src/go/ast/walk_typeparams.go b/src/go/ast/walk_typeparams.go
deleted file mode 100644
index b6621335b8ec41e18186dc25cee6e561ec35884c..0000000000000000000000000000000000000000
--- a/src/go/ast/walk_typeparams.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package ast
-
-import (
-	"fmt"
-)
-
-func walkFuncTypeParams(v Visitor, n *FuncType) {
-	if n.TParams != nil {
-		Walk(v, n.TParams)
-	}
-}
-
-func walkTypeSpecParams(v Visitor, n *TypeSpec) {
-	if n.TParams != nil {
-		Walk(v, n.TParams)
-	}
-}
-
-func walkOtherNodes(v Visitor, n Node) {
-	if e, ok := n.(*ListExpr); ok {
-		if e != nil {
-			for _, elem := range e.ElemList {
-				Walk(v, elem)
-			}
-		}
-	} else {
-		panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
-	}
-}
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index 45e2f25df74da3444f3256f52ea8ab6cdf23b616..80f8e1a00d70b66a1033bb242f230e8ce0b47d2f 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -71,17 +71,19 @@ var depsRules = `
 	# No dependencies allowed for any of these packages.
 	NONE
 	< container/list, container/ring,
-	  internal/cfg, internal/cpu, internal/goexperiment,
+	  internal/cfg, internal/cpu, internal/goarch,
+	  internal/goexperiment, internal/goos,
 	  internal/goversion, internal/nettrace,
 	  unicode/utf8, unicode/utf16, unicode,
 	  unsafe;
 
-	# These packages depend only on unsafe.
-	unsafe
+	# These packages depend only on internal/goarch and unsafe.
+	internal/goarch, unsafe
 	< internal/abi;
 
 	# RUNTIME is the core runtime group of packages, all of them very light-weight.
-	internal/abi, internal/cpu, internal/goexperiment, unsafe
+	internal/abi, internal/cpu, internal/goarch,
+	internal/goexperiment, internal/goos, unsafe
 	< internal/bytealg
 	< internal/itoa
 	< internal/unsafeheader
diff --git a/src/go/constant/kind_string.go b/src/go/constant/kind_string.go
new file mode 100644
index 0000000000000000000000000000000000000000..700332511d8b7c2e4af13609a171f21974e72dbd
--- /dev/null
+++ b/src/go/constant/kind_string.go
@@ -0,0 +1,28 @@
+// Code generated by "stringer -type Kind"; DO NOT EDIT.
+
+package constant
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Unknown-0]
+	_ = x[Bool-1]
+	_ = x[String-2]
+	_ = x[Int-3]
+	_ = x[Float-4]
+	_ = x[Complex-5]
+}
+
+const _Kind_name = "UnknownBoolStringIntFloatComplex"
+
+var _Kind_index = [...]uint8{0, 7, 11, 17, 20, 25, 32}
+
+func (i Kind) String() string {
+	if i < 0 || i >= Kind(len(_Kind_index)-1) {
+		return "Kind(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Kind_name[_Kind_index[i]:_Kind_index[i+1]]
+}
diff --git a/src/go/constant/value.go b/src/go/constant/value.go
index 78cb3f896f535cd7fddd64a2f2b34e03f1ec81dd..014e873100de6e02a426dec50f6aed921764c6db 100644
--- a/src/go/constant/value.go
+++ b/src/go/constant/value.go
@@ -24,6 +24,8 @@ import (
 	"unicode/utf8"
 )
 
+//go:generate stringer -type Kind
+
 // Kind specifies the kind of value represented by a Value.
 type Kind int
 
diff --git a/src/go/internal/gcimporter/gcimporter_test.go b/src/go/internal/gcimporter/gcimporter_test.go
index 3c76aafde39947ef49d9e42dd8107b5d753c210b..286b8a63471e6851dd14d06dc8650e859adf881c 100644
--- a/src/go/internal/gcimporter/gcimporter_test.go
+++ b/src/go/internal/gcimporter/gcimporter_test.go
@@ -138,6 +138,7 @@ func TestVersionHandling(t *testing.T) {
 	skipSpecialPlatforms(t)
 
 	// This package only handles gc export data.
+	// Disable test until we put in the new export version.
 	if runtime.Compiler != "gc" {
 		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
 	}
diff --git a/src/go/internal/gcimporter/iimport.go b/src/go/internal/gcimporter/iimport.go
index 76d47d08f1f88a9a11a4761604aba4d753d5fe5f..dbc9b3a83e8ddeccec4a6c4687779536293b4a15 100644
--- a/src/go/internal/gcimporter/iimport.go
+++ b/src/go/internal/gcimporter/iimport.go
@@ -41,6 +41,16 @@ func (r *intReader) uint64() uint64 {
 	return i
 }
 
+// Keep this in sync with constants in iexport.go.
+const (
+	iexportVersionGo1_11 = 0
+	iexportVersionPosCol = 1
+	// TODO: before release, change this back to 2.
+	iexportVersionGenerics = iexportVersionPosCol
+
+	iexportVersionCurrent = iexportVersionGenerics
+)
+
 const predeclReserved = 32
 
 type itag uint64
@@ -56,6 +66,8 @@ const (
 	signatureType
 	structType
 	interfaceType
+	typeParamType
+	instType
 )
 
 // iImportData imports a package from the serialized package data
@@ -63,7 +75,7 @@ const (
 // If the export data version is not recognized or the format is otherwise
 // compromised, an error is returned.
 func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataReader *bufio.Reader, path string) (pkg *types.Package, err error) {
-	const currentVersion = 1
+	const currentVersion = iexportVersionCurrent
 	version := int64(-1)
 	defer func() {
 		if e := recover(); e != nil {
@@ -79,9 +91,13 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataRea
 
 	version = int64(r.uint64())
 	switch version {
-	case currentVersion, 0:
+	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
 	default:
-		errorf("unknown iexport format version %d", version)
+		if version > iexportVersionGenerics {
+			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
+		} else {
+			errorf("unknown iexport format version %d", version)
+		}
 	}
 
 	sLen := int64(r.uint64())
@@ -95,8 +111,9 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataRea
 	declData := data[sLen:]
 
 	p := iimporter{
-		ipath:   path,
-		version: int(version),
+		exportVersion: version,
+		ipath:         path,
+		version:       int(version),
 
 		stringData:  stringData,
 		stringCache: make(map[uint64]string),
@@ -172,8 +189,9 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataRea
 }
 
 type iimporter struct {
-	ipath   string
-	version int
+	exportVersion int64
+	ipath         string
+	version       int
 
 	stringData  []byte
 	stringCache map[uint64]string
@@ -276,6 +294,9 @@ func (r *importReader) obj(name string) {
 
 		r.declare(types.NewFunc(pos, r.currPkg, name, sig))
 
+	case 'G':
+		errorf("unexpected parameterized function/method")
+
 	case 'T':
 		// Types can be recursive. We need to setup a stub
 		// declaration before recursing.
@@ -297,6 +318,9 @@ func (r *importReader) obj(name string) {
 			}
 		}
 
+	case 'U':
+		errorf("unexpected parameterized type")
+
 	case 'V':
 		typ := r.typ()
 
@@ -549,6 +573,14 @@ func (r *importReader) doType(base *types.Named) types.Type {
 		typ := types.NewInterfaceType(methods, embeddeds)
 		r.p.interfaceList = append(r.p.interfaceList, typ)
 		return typ
+
+	case typeParamType:
+		errorf("do not handle type param types yet")
+		return nil
+
+	case instType:
+		errorf("do not handle instantiated types yet")
+		return nil
 	}
 }
 
diff --git a/src/go/internal/gcimporter/support.go b/src/go/internal/gcimporter/support.go
index b8bb14dc490e2a1a47e24adc60be69304e7414a3..09810dd85b8b5949550b729debdbc5e7f04690cf 100644
--- a/src/go/internal/gcimporter/support.go
+++ b/src/go/internal/gcimporter/support.go
@@ -122,6 +122,9 @@ var predeclared = []types.Type{
 
 	// used internally by gc; never used by this package or in .a files
 	anyType{},
+
+	// comparable
+	types.Universe.Lookup("comparable").Type(),
 }
 
 type anyType struct{}
diff --git a/src/go/internal/typeparams/notypeparams.go b/src/go/internal/typeparams/notypeparams.go
deleted file mode 100644
index 2ceafaac1c356d95958c92b727f7756fb858d044..0000000000000000000000000000000000000000
--- a/src/go/internal/typeparams/notypeparams.go
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package typeparams
-
-import (
-	"go/ast"
-)
-
-const Enabled = false
-
-func PackExpr(list []ast.Expr) ast.Expr {
-	switch len(list) {
-	case 1:
-		return list[0]
-	default:
-		// The parser should not attempt to pack multiple expressions into an
-		// IndexExpr if type params are disabled.
-		panic("multiple index expressions are unsupported without type params")
-	}
-}
-
-func UnpackExpr(expr ast.Expr) []ast.Expr {
-	return []ast.Expr{expr}
-}
-
-func IsListExpr(n ast.Node) bool {
-	return false
-}
-
-func Get(ast.Node) *ast.FieldList {
-	return nil
-}
-
-func Set(node ast.Node, params *ast.FieldList) {
-}
diff --git a/src/go/internal/typeparams/typeparams.go b/src/go/internal/typeparams/typeparams.go
index 871e95d9984d7ad8bc54b01464233609323d65f6..3191654d4f8607ef48b5c7c682336ee6ac50137c 100644
--- a/src/go/internal/typeparams/typeparams.go
+++ b/src/go/internal/typeparams/typeparams.go
@@ -2,48 +2,57 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
 package typeparams
 
 import (
 	"fmt"
 	"go/ast"
+	"go/token"
 )
 
-const Enabled = true
-
-func PackExpr(list []ast.Expr) ast.Expr {
-	switch len(list) {
+func PackIndexExpr(x ast.Expr, lbrack token.Pos, exprs []ast.Expr, rbrack token.Pos) ast.Expr {
+	switch len(exprs) {
 	case 0:
-		// Return an empty ListExpr here, rather than nil, as IndexExpr.Index must
-		// never be nil.
-		// TODO(rFindley) would a BadExpr be more appropriate here?
-		return &ast.ListExpr{}
+		panic("internal error: PackIndexExpr with empty expr slice")
 	case 1:
-		return list[0]
+		return &ast.IndexExpr{
+			X:      x,
+			Lbrack: lbrack,
+			Index:  exprs[0],
+			Rbrack: rbrack,
+		}
 	default:
-		return &ast.ListExpr{ElemList: list}
+		return &ast.MultiIndexExpr{
+			X:       x,
+			Lbrack:  lbrack,
+			Indices: exprs,
+			Rbrack:  rbrack,
+		}
 	}
 }
 
-// TODO(gri) Should find a more efficient solution that doesn't
-//           require introduction of a new slice for simple
-//           expressions.
-func UnpackExpr(x ast.Expr) []ast.Expr {
-	if x, _ := x.(*ast.ListExpr); x != nil {
-		return x.ElemList
-	}
-	if x != nil {
-		return []ast.Expr{x}
-	}
-	return nil
+// IndexExpr wraps an ast.IndexExpr or ast.MultiIndexExpr into the
+// MultiIndexExpr interface.
+//
+// Orig holds the original ast.Expr from which this IndexExpr was derived.
+type IndexExpr struct {
+	Orig ast.Expr // the wrapped expr, which may be distinct from MultiIndexExpr below.
+	*ast.MultiIndexExpr
 }
 
-func IsListExpr(n ast.Node) bool {
-	_, ok := n.(*ast.ListExpr)
-	return ok
+func UnpackIndexExpr(n ast.Node) *IndexExpr {
+	switch e := n.(type) {
+	case *ast.IndexExpr:
+		return &IndexExpr{e, &ast.MultiIndexExpr{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}}
+	case *ast.MultiIndexExpr:
+		return &IndexExpr{e, e}
+	}
+	return nil
 }
 
 func Get(n ast.Node) *ast.FieldList {
diff --git a/src/go/parser/error_test.go b/src/go/parser/error_test.go
index f4f0a5240ac801e71ce64c7e868025afb97780b4..f35ba0b50173c9b8fcd8f2d8f7c52f20c503510e 100644
--- a/src/go/parser/error_test.go
+++ b/src/go/parser/error_test.go
@@ -186,16 +186,14 @@ func TestErrors(t *testing.T) {
 	}
 	for _, d := range list {
 		name := d.Name()
-		if !d.IsDir() && !strings.HasPrefix(name, ".") && (strings.HasSuffix(name, ".src") || strings.HasSuffix(name, ".go2")) {
-			mode := DeclarationErrors | AllErrors
-			if strings.HasSuffix(name, ".go2") {
-				if !typeparams.Enabled {
-					continue
+		t.Run(name, func(t *testing.T) {
+			if !d.IsDir() && !strings.HasPrefix(name, ".") && (strings.HasSuffix(name, ".src") || strings.HasSuffix(name, ".go2")) {
+				mode := DeclarationErrors | AllErrors
+				if !strings.HasSuffix(name, ".go2") {
+					mode |= typeparams.DisallowParsing
 				}
-			} else {
-				mode |= typeparams.DisallowParsing
+				checkErrors(t, filepath.Join(testdata, name), nil, mode, true)
 			}
-			checkErrors(t, filepath.Join(testdata, name), nil, mode, true)
-		}
+		})
 	}
 }
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index f10c8650afd0bf15461f712a8694e03bd02f7ab3..bdc2ad308c862084f43ed18c96a65f955d64978a 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -77,7 +77,7 @@ func (p *parser) init(fset *token.FileSet, filename string, src []byte, mode Mod
 }
 
 func (p *parser) parseTypeParams() bool {
-	return typeparams.Enabled && p.mode&typeparams.DisallowParsing == 0
+	return p.mode&typeparams.DisallowParsing == 0
 }
 
 // ----------------------------------------------------------------------------
@@ -600,7 +600,7 @@ func (p *parser) parseArrayFieldOrTypeInstance(x *ast.Ident) (*ast.Ident, ast.Ex
 	}
 
 	// x[P], x[P1, P2], ...
-	return nil, &ast.IndexExpr{X: x, Lbrack: lbrack, Index: typeparams.PackExpr(args), Rbrack: rbrack}
+	return nil, typeparams.PackIndexExpr(x, lbrack, args, rbrack)
 }
 
 func (p *parser) parseFieldDecl() *ast.Field {
@@ -980,6 +980,7 @@ func (p *parser) parseMethodSpec() *ast.Field {
 				list := []ast.Expr{x}
 				if p.atComma("type argument list", token.RBRACK) {
 					p.exprLev++
+					p.next()
 					for p.tok != token.RBRACK && p.tok != token.EOF {
 						list = append(list, p.parseType())
 						if !p.atComma("type argument list", token.RBRACK) {
@@ -990,7 +991,7 @@ func (p *parser) parseMethodSpec() *ast.Field {
 					p.exprLev--
 				}
 				rbrack := p.expectClosing(token.RBRACK, "type argument list")
-				typ = &ast.IndexExpr{X: ident, Lbrack: lbrack, Index: typeparams.PackExpr(list), Rbrack: rbrack}
+				typ = typeparams.PackIndexExpr(ident, lbrack, list, rbrack)
 			}
 		case p.tok == token.LPAREN:
 			// ordinary method
@@ -1011,11 +1012,56 @@ func (p *parser) parseMethodSpec() *ast.Field {
 			typ = p.parseTypeInstance(typ)
 		}
 	}
-	p.expectSemi() // call before accessing p.linecomment
 
-	spec := &ast.Field{Doc: doc, Names: idents, Type: typ, Comment: p.lineComment}
+	// Comment is added at the callsite: the field below may joined with
+	// additional type specs using '|'.
+	// TODO(rfindley) this should be refactored.
+	// TODO(rfindley) add more tests for comment handling.
+	return &ast.Field{Doc: doc, Names: idents, Type: typ}
+}
 
-	return spec
+func (p *parser) embeddedElem(f *ast.Field) *ast.Field {
+	if p.trace {
+		defer un(trace(p, "EmbeddedElem"))
+	}
+	if f == nil {
+		f = new(ast.Field)
+		f.Type = p.embeddedTerm()
+	}
+	for p.tok == token.OR {
+		t := new(ast.BinaryExpr)
+		t.OpPos = p.pos
+		t.Op = token.OR
+		p.next()
+		t.X = f.Type
+		t.Y = p.embeddedTerm()
+		f.Type = t
+	}
+	return f
+}
+
+func (p *parser) embeddedTerm() ast.Expr {
+	if p.trace {
+		defer un(trace(p, "EmbeddedTerm"))
+	}
+	if p.tok == token.TILDE {
+		t := new(ast.UnaryExpr)
+		t.OpPos = p.pos
+		t.Op = token.TILDE
+		p.next()
+		t.X = p.parseType()
+		return t
+	}
+
+	t := p.tryIdentOrType()
+	if t == nil {
+		pos := p.pos
+		p.errorExpected(pos, "~ term or type")
+		p.advance(exprEnd)
+		return &ast.BadExpr{From: pos, To: p.pos}
+	}
+
+	return t
 }
 
 func (p *parser) parseInterfaceType() *ast.InterfaceType {
@@ -1025,11 +1071,28 @@ func (p *parser) parseInterfaceType() *ast.InterfaceType {
 
 	pos := p.expect(token.INTERFACE)
 	lbrace := p.expect(token.LBRACE)
+
 	var list []*ast.Field
-	for p.tok == token.IDENT || p.parseTypeParams() && p.tok == token.TYPE {
-		if p.tok == token.IDENT {
-			list = append(list, p.parseMethodSpec())
-		} else {
+
+parseElements:
+	for {
+		switch {
+		case p.tok == token.IDENT:
+			f := p.parseMethodSpec()
+			if f.Names == nil && p.parseTypeParams() {
+				f = p.embeddedElem(f)
+			}
+			p.expectSemi()
+			f.Comment = p.lineComment
+			list = append(list, f)
+		case p.tok == token.TILDE && p.parseTypeParams():
+			f := p.embeddedElem(nil)
+			p.expectSemi()
+			f.Comment = p.lineComment
+			list = append(list, f)
+		case p.tok == token.TYPE && p.parseTypeParams():
+			// TODO(rfindley): remove TypeList syntax and refactor the clauses above.
+
 			// all types in a type list share the same field name "type"
 			// (since type is a keyword, a Go program cannot have that field name)
 			name := []*ast.Ident{{NamePos: p.pos, Name: "type"}}
@@ -1039,8 +1102,22 @@ func (p *parser) parseInterfaceType() *ast.InterfaceType {
 				list = append(list, &ast.Field{Names: name, Type: typ})
 			}
 			p.expectSemi()
+		case p.parseTypeParams():
+			if t := p.tryIdentOrType(); t != nil {
+				f := new(ast.Field)
+				f.Type = t
+				f = p.embeddedElem(f)
+				p.expectSemi()
+				f.Comment = p.lineComment
+				list = append(list, f)
+			} else {
+				break parseElements
+			}
+		default:
+			break parseElements
 		}
 	}
+
 	// TODO(rfindley): the error produced here could be improved, since we could
 	// accept a identifier, 'type', or a '}' at this point.
 	rbrace := p.expect(token.RBRACE)
@@ -1101,7 +1178,6 @@ func (p *parser) parseTypeInstance(typ ast.Expr) ast.Expr {
 	}
 
 	opening := p.expect(token.LBRACK)
-
 	p.exprLev++
 	var list []ast.Expr
 	for p.tok != token.RBRACK && p.tok != token.EOF {
@@ -1115,7 +1191,17 @@ func (p *parser) parseTypeInstance(typ ast.Expr) ast.Expr {
 
 	closing := p.expectClosing(token.RBRACK, "type argument list")
 
-	return &ast.IndexExpr{X: typ, Lbrack: opening, Index: typeparams.PackExpr(list), Rbrack: closing}
+	if len(list) == 0 {
+		p.errorExpected(closing, "type argument list")
+		return &ast.IndexExpr{
+			X:      typ,
+			Lbrack: opening,
+			Index:  &ast.BadExpr{From: opening + 1, To: closing},
+			Rbrack: closing,
+		}
+	}
+
+	return typeparams.PackIndexExpr(typ, opening, list, closing)
 }
 
 func (p *parser) tryIdentOrType() ast.Expr {
@@ -1378,7 +1464,7 @@ func (p *parser) parseIndexOrSliceOrInstance(x ast.Expr) ast.Expr {
 	}
 
 	// instance expression
-	return &ast.IndexExpr{X: x, Lbrack: lbrack, Index: typeparams.PackExpr(args), Rbrack: rbrack}
+	return typeparams.PackIndexExpr(x, lbrack, args, rbrack)
 }
 
 func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
@@ -1480,6 +1566,7 @@ func (p *parser) checkExpr(x ast.Expr) ast.Expr {
 		panic("unreachable")
 	case *ast.SelectorExpr:
 	case *ast.IndexExpr:
+	case *ast.MultiIndexExpr:
 	case *ast.SliceExpr:
 	case *ast.TypeAssertExpr:
 		// If t.Type == nil we have a type assertion of the form
@@ -1569,7 +1656,7 @@ func (p *parser) parsePrimaryExpr() (x ast.Expr) {
 					return
 				}
 				// x is possibly a composite literal type
-			case *ast.IndexExpr:
+			case *ast.IndexExpr, *ast.MultiIndexExpr:
 				if p.exprLev < 0 {
 					return
 				}
diff --git a/src/go/parser/resolver_test.go b/src/go/parser/resolver_test.go
index 625c009c914d8342eebcbfbe2649f2ed786ac44d..0c06c592d5fea1e91785163ac186840f49d5c6ae 100644
--- a/src/go/parser/resolver_test.go
+++ b/src/go/parser/resolver_test.go
@@ -41,11 +41,7 @@ func TestResolution(t *testing.T) {
 			path := filepath.Join(dir, fi.Name())
 			src := readFile(path) // panics on failure
 			var mode Mode
-			if strings.HasSuffix(path, ".go2") {
-				if !typeparams.Enabled {
-					t.Skip("type params are not enabled")
-				}
-			} else {
+			if !strings.HasSuffix(path, ".go2") {
 				mode |= typeparams.DisallowParsing
 			}
 			file, err := ParseFile(fset, path, src, mode)
diff --git a/src/go/parser/short_test.go b/src/go/parser/short_test.go
index 67fef15665583db4e4a1ba7aad93a081b8c9bfc9..bfc6f6714b9f59f0bb31079709f620a184aba0b4 100644
--- a/src/go/parser/short_test.go
+++ b/src/go/parser/short_test.go
@@ -133,9 +133,6 @@ func TestValid(t *testing.T) {
 		}
 	})
 	t.Run("tparams", func(t *testing.T) {
-		if !typeparams.Enabled {
-			t.Skip("type params are not enabled")
-		}
 		for _, src := range valids {
 			checkErrors(t, src, src, DeclarationErrors|AllErrors, false)
 		}
@@ -200,10 +197,12 @@ var invalids = []string{
 	`package p; func (type /* ERROR "found 'type'" */ T)(T) _()`,
 	`package p; type _[A+B, /* ERROR "expected ']'" */ ] int`,
 
-	// TODO: this error should be positioned on the ':'
+	// TODO(rfindley): this error should be positioned on the ':'
 	`package p; var a = a[[]int:[ /* ERROR "expected expression" */ ]int];`,
-	// TODO: the compiler error is better here: "cannot parenthesize embedded type"
-	`package p; type I1 interface{}; type I2 interface{ (/* ERROR "expected '}', found '\('" */ I1) }`,
+
+	// TODO(rfindley): the compiler error is better here: "cannot parenthesize embedded type"
+	// TODO(rfindley): confirm that parenthesized types should now be accepted.
+	// `package p; type I1 interface{}; type I2 interface{ (/* ERROR "expected '}', found '\('" */ I1) }`,
 
 	// issue 8656
 	`package p; func f() (a b string /* ERROR "missing ','" */ , ok bool)`,
@@ -266,9 +265,6 @@ func TestInvalid(t *testing.T) {
 		}
 	})
 	t.Run("tparams", func(t *testing.T) {
-		if !typeparams.Enabled {
-			t.Skip("type params are not enabled")
-		}
 		for _, src := range invalids {
 			checkErrors(t, src, src, DeclarationErrors|AllErrors, true)
 		}
diff --git a/src/go/parser/testdata/interface.go2 b/src/go/parser/testdata/interface.go2
new file mode 100644
index 0000000000000000000000000000000000000000..b399d7514889f39c5e8889088dd2c4ada0d2c857
--- /dev/null
+++ b/src/go/parser/testdata/interface.go2
@@ -0,0 +1,80 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains test cases for interfaces containing
+// constraint elements.
+//
+// For now, we accept both ordinary type lists and the
+// more complex constraint elements.
+
+package p
+
+type _ interface {
+	m()
+	type int
+	type int, string
+	E
+}
+
+type _ interface {
+	m()
+	~int
+	int | string
+	int | ~string
+	~int | ~string
+}
+
+type _ interface {
+	m()
+	~int
+	T[int, string] | string
+	int | ~T[string, struct{}]
+	~int | ~string
+	type bool, int, float64
+}
+
+type _ interface {
+	int
+	[]byte
+	[10]int
+	struct{}
+	*int
+	func()
+	interface{}
+	map[string]int
+	chan T
+	chan<- T
+	<-chan T
+	T[int]
+}
+
+type _ interface {
+	int | string
+	[]byte | string
+	[10]int | string
+	struct{} | string
+	*int | string
+	func() | string
+	interface{} | string
+	map[string]int | string
+	chan T | string
+	chan<- T | string
+	<-chan T | string
+	T[int] | string
+}
+
+type _ interface {
+	~int | string
+	~[]byte | string
+	~[10]int | string
+	~struct{} | string
+	~*int | string
+	~func() | string
+	~interface{} | string
+	~map[string]int | string
+	~chan T | string
+	~chan<- T | string
+	~<-chan T | string
+	~T[int] | string
+}
diff --git a/src/go/printer/nodes.go b/src/go/printer/nodes.go
index 913281ea6c14b7b13ef6e95f9233a1c808e518b1..239fcbde1c8b4cc3d6b8a5b4082d8f8a996b03b4 100644
--- a/src/go/printer/nodes.go
+++ b/src/go/printer/nodes.go
@@ -871,17 +871,15 @@ func (p *printer) expr1(expr ast.Expr, prec1, depth int) {
 		// TODO(gri): should treat[] like parentheses and undo one level of depth
 		p.expr1(x.X, token.HighestPrec, 1)
 		p.print(x.Lbrack, token.LBRACK)
-		// Note: we're a bit defensive here to handle the case of a ListExpr of
-		// length 1.
-		if list := typeparams.UnpackExpr(x.Index); len(list) > 0 {
-			if len(list) > 1 {
-				p.exprList(x.Lbrack, list, depth+1, commaTerm, x.Rbrack, false)
-			} else {
-				p.expr0(list[0], depth+1)
-			}
-		} else {
-			p.expr0(x.Index, depth+1)
-		}
+		p.expr0(x.Index, depth+1)
+		p.print(x.Rbrack, token.RBRACK)
+
+	case *ast.MultiIndexExpr:
+		// TODO(gri): as for IndexExpr, should treat [] like parentheses and undo
+		// one level of depth
+		p.expr1(x.X, token.HighestPrec, 1)
+		p.print(x.Lbrack, token.LBRACK)
+		p.exprList(x.Lbrack, x.Indices, depth+1, commaTerm, x.Rbrack, false)
 		p.print(x.Rbrack, token.RBRACK)
 
 	case *ast.SliceExpr:
diff --git a/src/go/printer/printer_test.go b/src/go/printer/printer_test.go
index 20c97b8c08173065e23a2be9795b90beb904201f..ff8be4ae97a75ff5a1f1b645009ca13858188caa 100644
--- a/src/go/printer/printer_test.go
+++ b/src/go/printer/printer_test.go
@@ -10,7 +10,6 @@ import (
 	"flag"
 	"fmt"
 	"go/ast"
-	"go/internal/typeparams"
 	"go/parser"
 	"go/token"
 	"io"
@@ -222,9 +221,6 @@ var data = []entry{
 func TestFiles(t *testing.T) {
 	t.Parallel()
 	for _, e := range data {
-		if !typeparams.Enabled && e.mode&allowTypeParams != 0 {
-			continue
-		}
 		source := filepath.Join(dataDir, e.source)
 		golden := filepath.Join(dataDir, e.golden)
 		mode := e.mode
diff --git a/src/go/scanner/scanner.go b/src/go/scanner/scanner.go
index f08e28cdd6b72b35da5b669a0592b88c6e012c53..ca4b5264cfedf6414189ed26003c77e25951e539 100644
--- a/src/go/scanner/scanner.go
+++ b/src/go/scanner/scanner.go
@@ -969,6 +969,8 @@ scanAgain:
 			}
 		case '|':
 			tok = s.switch3(token.OR, token.OR_ASSIGN, '|', token.LOR)
+		case '~':
+			tok = token.TILDE
 		default:
 			// next reports unexpected BOMs - don't repeat
 			if ch != bom {
diff --git a/src/go/scanner/scanner_test.go b/src/go/scanner/scanner_test.go
index db123c32e01d59e9d46fa6429efcefb9fc60bdff..de45e16606052ac6af07fe4b01868d5819685331 100644
--- a/src/go/scanner/scanner_test.go
+++ b/src/go/scanner/scanner_test.go
@@ -40,7 +40,7 @@ type elt struct {
 	class int
 }
 
-var tokens = [...]elt{
+var tokens = []elt{
 	// Special tokens
 	{token.COMMENT, "/* a comment */", special},
 	{token.COMMENT, "// a comment \n", special},
@@ -149,6 +149,7 @@ var tokens = [...]elt{
 	{token.RBRACE, "}", operator},
 	{token.SEMICOLON, ";", operator},
 	{token.COLON, ":", operator},
+	{token.TILDE, "~", operator},
 
 	// Keywords
 	{token.BREAK, "break", keyword},
diff --git a/src/go/token/position.go b/src/go/token/position.go
index 0d7982c67059374be2c291fd3bd312b7a3e950d8..ce4af039237ce6f3cb12005e8f34fe8430ad04a5 100644
--- a/src/go/token/position.go
+++ b/src/go/token/position.go
@@ -540,7 +540,7 @@ func searchInts(a []int, x int) int {
 	// TODO(gri): Remove this when compilers have caught up.
 	i, j := 0, len(a)
 	for i < j {
-		h := i + (j-i)>>1 // avoid overflow when computing h
+		h := int(uint(i+j) >> 1) // avoid overflow when computing h
 		// i ≤ h < j
 		if a[h] <= x {
 			i = h + 1
diff --git a/src/go/token/token.go b/src/go/token/token.go
index 96a1079ec37c4668969721700df0a682087c00f9..d22e575661a2df95726266b65c512fbdda7c5838 100644
--- a/src/go/token/token.go
+++ b/src/go/token/token.go
@@ -125,6 +125,11 @@ const (
 	TYPE
 	VAR
 	keyword_end
+
+	additional_beg
+	// additional tokens, handled in an ad-hoc manner
+	TILDE
+	additional_end
 )
 
 var tokens = [...]string{
@@ -225,6 +230,8 @@ var tokens = [...]string{
 	SWITCH: "switch",
 	TYPE:   "type",
 	VAR:    "var",
+
+	TILDE: "~",
 }
 
 // String returns the string corresponding to the token tok.
@@ -304,7 +311,9 @@ func (tok Token) IsLiteral() bool { return literal_beg < tok && tok < literal_en
 // IsOperator returns true for tokens corresponding to operators and
 // delimiters; it returns false otherwise.
 //
-func (tok Token) IsOperator() bool { return operator_beg < tok && tok < operator_end }
+func (tok Token) IsOperator() bool {
+	return (operator_beg < tok && tok < operator_end) || tok == TILDE
+}
 
 // IsKeyword returns true for tokens corresponding to keywords;
 // it returns false otherwise.
diff --git a/src/go/types/api.go b/src/go/types/api.go
index 8c0d9d22bf26aa671f6bf65c7676dc2bf806a78a..5beeff530c002f9cfa2566ba672f36d7fc7dc055 100644
--- a/src/go/types/api.go
+++ b/src/go/types/api.go
@@ -34,6 +34,8 @@ import (
 	"go/token"
 )
 
+const allowTypeLists = false
+
 // An Error describes a type-checking error; it implements the error interface.
 // A "soft" error is an error that still permits a valid interpretation of a
 // package (such as "unused variable"); "hard" errors may lead to unpredictable
@@ -60,6 +62,18 @@ func (err Error) Error() string {
 	return fmt.Sprintf("%s: %s", err.Fset.Position(err.Pos), err.Msg)
 }
 
+// An ArgumentError holds an error associated with an argument index.
+type ArgumentError struct {
+	index int
+	error
+}
+
+// Index returns the positional index of the argument associated with the
+// error.
+func (e ArgumentError) Index() int {
+	return e.index
+}
+
 // An Importer resolves import paths to Packages.
 //
 // CAUTION: This interface does not support the import of locally
@@ -101,12 +115,12 @@ type ImporterFrom interface {
 // A Config specifies the configuration for type checking.
 // The zero value for Config is a ready-to-use default configuration.
 type Config struct {
-	// goVersion describes the accepted Go language version. The string
+	// GoVersion describes the accepted Go language version. The string
 	// must follow the format "go%d.%d" (e.g. "go1.12") or it must be
 	// empty; an empty string indicates the latest language version.
 	// If the format is invalid, invoking the type checker will cause a
 	// panic.
-	goVersion string
+	GoVersion string
 
 	// If IgnoreFuncBodies is set, function bodies are not
 	// type-checked.
@@ -160,7 +174,101 @@ func srcimporter_setUsesCgo(conf *Config) {
 	conf.go115UsesCgo = true
 }
 
-// The Info struct is found in api_notypeparams.go and api_typeparams.go.
+// Info holds result type information for a type-checked package.
+// Only the information for which a map is provided is collected.
+// If the package has type errors, the collected information may
+// be incomplete.
+type Info struct {
+	// Types maps expressions to their types, and for constant
+	// expressions, also their values. Invalid expressions are
+	// omitted.
+	//
+	// For (possibly parenthesized) identifiers denoting built-in
+	// functions, the recorded signatures are call-site specific:
+	// if the call result is not a constant, the recorded type is
+	// an argument-specific signature. Otherwise, the recorded type
+	// is invalid.
+	//
+	// The Types map does not record the type of every identifier,
+	// only those that appear where an arbitrary expression is
+	// permitted. For instance, the identifier f in a selector
+	// expression x.f is found only in the Selections map, the
+	// identifier z in a variable declaration 'var z int' is found
+	// only in the Defs map, and identifiers denoting packages in
+	// qualified identifiers are collected in the Uses map.
+	Types map[ast.Expr]TypeAndValue
+
+	// Inferred maps calls of parameterized functions that use
+	// type inference to the inferred type arguments and signature
+	// of the function called. The recorded "call" expression may be
+	// an *ast.CallExpr (as in f(x)), or an *ast.IndexExpr (s in f[T]).
+	Inferred map[ast.Expr]Inferred
+
+	// Defs maps identifiers to the objects they define (including
+	// package names, dots "." of dot-imports, and blank "_" identifiers).
+	// For identifiers that do not denote objects (e.g., the package name
+	// in package clauses, or symbolic variables t in t := x.(type) of
+	// type switch headers), the corresponding objects are nil.
+	//
+	// For an embedded field, Defs returns the field *Var it defines.
+	//
+	// Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
+	Defs map[*ast.Ident]Object
+
+	// Uses maps identifiers to the objects they denote.
+	//
+	// For an embedded field, Uses returns the *TypeName it denotes.
+	//
+	// Invariant: Uses[id].Pos() != id.Pos()
+	Uses map[*ast.Ident]Object
+
+	// Implicits maps nodes to their implicitly declared objects, if any.
+	// The following node and object types may appear:
+	//
+	//     node               declared object
+	//
+	//     *ast.ImportSpec    *PkgName for imports without renames
+	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
+	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
+	//
+	Implicits map[ast.Node]Object
+
+	// Selections maps selector expressions (excluding qualified identifiers)
+	// to their corresponding selections.
+	Selections map[*ast.SelectorExpr]*Selection
+
+	// Scopes maps ast.Nodes to the scopes they define. Package scopes are not
+	// associated with a specific node but with all files belonging to a package.
+	// Thus, the package scope can be found in the type-checked Package object.
+	// Scopes nest, with the Universe scope being the outermost scope, enclosing
+	// the package scope, which contains (one or more) files scopes, which enclose
+	// function scopes which in turn enclose statement and function literal scopes.
+	// Note that even though package-level functions are declared in the package
+	// scope, the function scopes are embedded in the file scope of the file
+	// containing the function declaration.
+	//
+	// The following node types may appear in Scopes:
+	//
+	//     *ast.File
+	//     *ast.FuncType
+	//     *ast.BlockStmt
+	//     *ast.IfStmt
+	//     *ast.SwitchStmt
+	//     *ast.TypeSwitchStmt
+	//     *ast.CaseClause
+	//     *ast.CommClause
+	//     *ast.ForStmt
+	//     *ast.RangeStmt
+	//
+	Scopes map[ast.Node]*Scope
+
+	// InitOrder is the list of package-level initializers in the order in which
+	// they must be executed. Initializers referring to variables related by an
+	// initialization dependency appear in topological order, the others appear
+	// in source order. Variables without an initialization expression do not
+	// appear in this list.
+	InitOrder []*Initializer
+}
 
 // TypeOf returns the type of expression e, or nil if not found.
 // Precondition: the Types, Uses and Defs maps are populated.
@@ -252,10 +360,10 @@ func (tv TypeAndValue) HasOk() bool {
 	return tv.mode == commaok || tv.mode == mapindex
 }
 
-// _Inferred reports the _Inferred type arguments and signature
+// Inferred reports the Inferred type arguments and signature
 // for a parameterized function call that uses type inference.
-type _Inferred struct {
-	Targs []Type
+type Inferred struct {
+	TArgs *TypeList
 	Sig   *Signature
 }
 
@@ -324,11 +432,11 @@ func Implements(V Type, T *Interface) bool {
 // Identical reports whether x and y are identical types.
 // Receivers of Signature types are ignored.
 func Identical(x, y Type) bool {
-	return (*Checker)(nil).identical(x, y)
+	return identical(x, y, true, nil)
 }
 
 // IdenticalIgnoreTags reports whether x and y are identical types if tags are ignored.
 // Receivers of Signature types are ignored.
 func IdenticalIgnoreTags(x, y Type) bool {
-	return (*Checker)(nil).identicalIgnoreTags(x, y)
+	return identical(x, y, false, nil)
 }
diff --git a/src/go/types/api_notypeparams.go b/src/go/types/api_notypeparams.go
deleted file mode 100644
index 9f7cb7eccf266ef78b7df7375ba21f0525f82b0d..0000000000000000000000000000000000000000
--- a/src/go/types/api_notypeparams.go
+++ /dev/null
@@ -1,104 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package types
-
-import "go/ast"
-
-// Info holds result type information for a type-checked package.
-// Only the information for which a map is provided is collected.
-// If the package has type errors, the collected information may
-// be incomplete.
-type Info struct {
-	// Types maps expressions to their types, and for constant
-	// expressions, also their values. Invalid expressions are
-	// omitted.
-	//
-	// For (possibly parenthesized) identifiers denoting built-in
-	// functions, the recorded signatures are call-site specific:
-	// if the call result is not a constant, the recorded type is
-	// an argument-specific signature. Otherwise, the recorded type
-	// is invalid.
-	//
-	// The Types map does not record the type of every identifier,
-	// only those that appear where an arbitrary expression is
-	// permitted. For instance, the identifier f in a selector
-	// expression x.f is found only in the Selections map, the
-	// identifier z in a variable declaration 'var z int' is found
-	// only in the Defs map, and identifiers denoting packages in
-	// qualified identifiers are collected in the Uses map.
-	Types map[ast.Expr]TypeAndValue
-
-	// Defs maps identifiers to the objects they define (including
-	// package names, dots "." of dot-imports, and blank "_" identifiers).
-	// For identifiers that do not denote objects (e.g., the package name
-	// in package clauses, or symbolic variables t in t := x.(type) of
-	// type switch headers), the corresponding objects are nil.
-	//
-	// For an embedded field, Defs returns the field *Var it defines.
-	//
-	// Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
-	Defs map[*ast.Ident]Object
-
-	// Uses maps identifiers to the objects they denote.
-	//
-	// For an embedded field, Uses returns the *TypeName it denotes.
-	//
-	// Invariant: Uses[id].Pos() != id.Pos()
-	Uses map[*ast.Ident]Object
-
-	// Implicits maps nodes to their implicitly declared objects, if any.
-	// The following node and object types may appear:
-	//
-	//     node               declared object
-	//
-	//     *ast.ImportSpec    *PkgName for imports without renames
-	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
-	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
-	//
-	Implicits map[ast.Node]Object
-
-	// Selections maps selector expressions (excluding qualified identifiers)
-	// to their corresponding selections.
-	Selections map[*ast.SelectorExpr]*Selection
-
-	// Scopes maps ast.Nodes to the scopes they define. Package scopes are not
-	// associated with a specific node but with all files belonging to a package.
-	// Thus, the package scope can be found in the type-checked Package object.
-	// Scopes nest, with the Universe scope being the outermost scope, enclosing
-	// the package scope, which contains (one or more) files scopes, which enclose
-	// function scopes which in turn enclose statement and function literal scopes.
-	// Note that even though package-level functions are declared in the package
-	// scope, the function scopes are embedded in the file scope of the file
-	// containing the function declaration.
-	//
-	// The following node types may appear in Scopes:
-	//
-	//     *ast.File
-	//     *ast.FuncType
-	//     *ast.BlockStmt
-	//     *ast.IfStmt
-	//     *ast.SwitchStmt
-	//     *ast.TypeSwitchStmt
-	//     *ast.CaseClause
-	//     *ast.CommClause
-	//     *ast.ForStmt
-	//     *ast.RangeStmt
-	//
-	Scopes map[ast.Node]*Scope
-
-	// InitOrder is the list of package-level initializers in the order in which
-	// they must be executed. Initializers referring to variables related by an
-	// initialization dependency appear in topological order, the others appear
-	// in source order. Variables without an initialization expression do not
-	// appear in this list.
-	InitOrder []*Initializer
-}
-
-func getInferred(info *Info) map[ast.Expr]_Inferred {
-	return nil
-}
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index f964c656f93f9dc97cfdf3ae8ac4e80c93aaced5..1e7d6f2cfafe5c13336445581c1bea55f9acda43 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -343,16 +343,16 @@ func TestTypesInfo(t *testing.T) {
 		{broken + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string][-1]int`},
 
 		// parameterized functions
-		{genericPkg + `p0; func f[T any](T); var _ = f[int]`, `f`, `func[T₁ interface{}](T₁)`},
-		{genericPkg + `p1; func f[T any](T); var _ = f[int]`, `f[int]`, `func(int)`},
-		{genericPkg + `p2; func f[T any](T); func _() { f(42) }`, `f`, `func[T₁ interface{}](T₁)`},
-		{genericPkg + `p3; func f[T any](T); func _() { f(42) }`, `f(42)`, `()`},
+		{genericPkg + `p0; func f[T any](T) {}; var _ = f[int]`, `f`, `func[generic_p0.T₁ interface{}](generic_p0.T₁)`},
+		{genericPkg + `p1; func f[T any](T) {}; var _ = f[int]`, `f[int]`, `func(int)`},
+		{genericPkg + `p2; func f[T any](T) {}; func _() { f(42) }`, `f`, `func[generic_p2.T₁ interface{}](generic_p2.T₁)`},
+		{genericPkg + `p3; func f[T any](T) {}; func _() { f(42) }`, `f(42)`, `()`},
 
 		// type parameters
 		{genericPkg + `t0; type t[] int; var _ t`, `t`, `generic_t0.t`}, // t[] is a syntax error that is ignored in this test in favor of t
-		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[P₁ interface{}]`},
-		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[P₁ interface{}]`},
-		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[P₁, Q₂ interface{}]`},
+		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[generic_t1.P₁ interface{}]`},
+		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[generic_t2.P₁ interface{}]`},
+		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[generic_t3.P₁, generic_t3.Q₂ interface{}]`},
 
 		// TODO (rFindley): compare with types2, which resolves the type broken_t4.t[P₁, Q₂ interface{m()}] here
 		{broken + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t`},
@@ -361,14 +361,13 @@ func TestTypesInfo(t *testing.T) {
 		{genericPkg + `g0; type t[P any] int; var x struct{ f t[int] }; var _ = x.f`, `x.f`, `generic_g0.t[int]`},
 
 		// issue 45096
-		{genericPkg + `issue45096; func _[T interface{ type int8, int16, int32  }](x T) { _ = x < 0 }`, `0`, `T₁`},
+		{genericPkg + `issue45096; func _[T interface{ ~int8 | ~int16 | ~int32  }](x T) { _ = x < 0 }`, `0`, `generic_issue45096.T₁`},
+
+		// issue 47895
+		{`package p; import "unsafe"; type S struct { f int }; var s S; var _ = unsafe.Offsetof(s.f)`, `s.f`, `int`},
 	}
 
 	for _, test := range tests {
-		ResetId() // avoid renumbering of type parameter ids when adding tests
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, broken) {
@@ -402,6 +401,130 @@ func TestTypesInfo(t *testing.T) {
 	}
 }
 
+func TestInferredInfo(t *testing.T) {
+	var tests = []struct {
+		src   string
+		fun   string
+		targs []string
+		sig   string
+	}{
+		{genericPkg + `p0; func f[T any](T) {}; func _() { f(42) }`,
+			`f`,
+			[]string{`int`},
+			`func(int)`,
+		},
+		{genericPkg + `p1; func f[T any](T) T { panic(0) }; func _() { f('@') }`,
+			`f`,
+			[]string{`rune`},
+			`func(rune) rune`,
+		},
+		{genericPkg + `p2; func f[T any](...T) T { panic(0) }; func _() { f(0i) }`,
+			`f`,
+			[]string{`complex128`},
+			`func(...complex128) complex128`,
+		},
+		{genericPkg + `p3; func f[A, B, C any](A, *B, []C) {}; func _() { f(1.2, new(string), []byte{}) }`,
+			`f`,
+			[]string{`float64`, `string`, `byte`},
+			`func(float64, *string, []byte)`,
+		},
+		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
+			`f`,
+			[]string{`float64`, `byte`},
+			`func(float64, *byte, ...[]byte)`,
+		},
+
+		{genericPkg + `s1; func f[T any, P interface{~*T}](x T) {}; func _(x string) { f(x) }`,
+			`f`,
+			[]string{`string`, `*string`},
+			`func(x string)`,
+		},
+		{genericPkg + `s2; func f[T any, P interface{~*T}](x []T) {}; func _(x []int) { f(x) }`,
+			`f`,
+			[]string{`int`, `*int`},
+			`func(x []int)`,
+		},
+		{genericPkg + `s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
+			`f`,
+			[]string{`int`, `chan<- int`},
+			`func(x []int)`,
+		},
+		{genericPkg + `s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
+			`f`,
+			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+			`func(x []int)`,
+		},
+
+		{genericPkg + `t1; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = f[string] }`,
+			`f`,
+			[]string{`string`, `*string`},
+			`func() string`,
+		},
+		{genericPkg + `t2; type C[T any] interface{~chan<- T}; func f[T any, P C[T]]() []T { return nil }; func _() { _ = f[int] }`,
+			`f`,
+			[]string{`int`, `chan<- int`},
+			`func() []int`,
+		},
+		{genericPkg + `t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
+			`f`,
+			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+			`func() []int`,
+		},
+	}
+
+	for _, test := range tests {
+		info := Info{}
+		info.Inferred = make(map[ast.Expr]Inferred)
+		name, err := mayTypecheck(t, "InferredInfo", test.src, &info)
+		if err != nil {
+			t.Errorf("package %s: %v", name, err)
+			continue
+		}
+
+		// look for inferred type arguments and signature
+		var targs *TypeList
+		var sig *Signature
+		for call, inf := range info.Inferred {
+			var fun ast.Expr
+			switch x := call.(type) {
+			case *ast.CallExpr:
+				fun = x.Fun
+			case *ast.IndexExpr:
+				fun = x.X
+			default:
+				panic(fmt.Sprintf("unexpected call expression type %T", call))
+			}
+			if ExprString(fun) == test.fun {
+				targs = inf.TArgs
+				sig = inf.Sig
+				break
+			}
+		}
+		if targs == nil {
+			t.Errorf("package %s: no inferred information found for %s", name, test.fun)
+			continue
+		}
+
+		// check that type arguments are correct
+		if targs.Len() != len(test.targs) {
+			t.Errorf("package %s: got %d type arguments; want %d", name, targs.Len(), len(test.targs))
+			continue
+		}
+		for i := 0; i < targs.Len(); i++ {
+			targ := targs.At(i)
+			if got := targ.String(); got != test.targs[i] {
+				t.Errorf("package %s, %d. type argument: got %s; want %s", name, i, got, test.targs[i])
+				continue
+			}
+		}
+
+		// check that signature is correct
+		if got := sig.String(); got != test.sig {
+			t.Errorf("package %s: got %s; want %s", name, got, test.sig)
+		}
+	}
+}
+
 func TestDefsInfo(t *testing.T) {
 	var tests = []struct {
 		src  string
@@ -424,9 +547,6 @@ func TestDefsInfo(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{
 			Defs: make(map[*ast.Ident]Object),
 		}
@@ -472,9 +592,6 @@ func TestUsesInfo(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{
 			Uses: make(map[*ast.Ident]Object),
 		}
@@ -1433,6 +1550,13 @@ func F(){
 	}
 }
 
+// newDefined creates a new defined type named T with the given underlying type.
+// Helper function for use with TestIncompleteInterfaces only.
+func newDefined(underlying Type) *Named {
+	tname := NewTypeName(token.NoPos, nil, "T", nil)
+	return NewNamed(tname, underlying, nil)
+}
+
 func TestConvertibleTo(t *testing.T) {
 	for _, test := range []struct {
 		v, t Type
@@ -1716,3 +1840,89 @@ func f(x T) T { return foo.F(x) }
 		}
 	}
 }
+
+func TestInstantiate(t *testing.T) {
+	// eventually we like more tests but this is a start
+	const src = genericPkg + "p; type T[P any] *T[P]"
+	pkg, err := pkgFor(".", src, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// type T should have one type parameter
+	T := pkg.Scope().Lookup("T").Type().(*Named)
+	if n := T.TParams().Len(); n != 1 {
+		t.Fatalf("expected 1 type parameter; found %d", n)
+	}
+
+	// instantiation should succeed (no endless recursion)
+	// even with a nil *Checker
+	res, err := Instantiate(nil, T, []Type{Typ[Int]}, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// instantiated type should point to itself
+	if p := res.Underlying().(*Pointer).Elem(); p != res {
+		t.Fatalf("unexpected result type: %s points to %s", res, p)
+	}
+}
+
+func TestInstantiateErrors(t *testing.T) {
+	tests := []struct {
+		src    string // by convention, T must be the type being instantiated
+		targs  []Type
+		wantAt int // -1 indicates no error
+	}{
+		{"type T[P interface{~string}] int", []Type{Typ[Int]}, 0},
+		{"type T[P1 interface{int}, P2 interface{~string}] int", []Type{Typ[Int], Typ[Int]}, 1},
+		{"type T[P1 any, P2 interface{~[]P1}] int", []Type{Typ[Int], NewSlice(Typ[String])}, 1},
+		{"type T[P1 interface{~[]P2}, P2 any] int", []Type{NewSlice(Typ[String]), Typ[Int]}, 0},
+	}
+
+	for _, test := range tests {
+		src := genericPkg + "p; " + test.src
+		pkg, err := pkgFor(".", src, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		T := pkg.Scope().Lookup("T").Type().(*Named)
+
+		_, err = Instantiate(nil, T, test.targs, true)
+		if err == nil {
+			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
+		}
+
+		gotAt := err.(ArgumentError).Index()
+		if gotAt != test.wantAt {
+			t.Errorf("Instantate(%v, %v): error at index %d, want index %d", T, test.targs, gotAt, test.wantAt)
+		}
+	}
+}
+
+func TestInstanceIdentity(t *testing.T) {
+	imports := make(testImporter)
+	conf := Config{Importer: imports}
+	makePkg := func(src string) {
+		fset := token.NewFileSet()
+		f, err := parser.ParseFile(fset, "", src, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+		name := f.Name.Name
+		pkg, err := conf.Check(name, fset, []*ast.File{f}, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		imports[name] = pkg
+	}
+	makePkg(genericPkg + `lib; type T[P any] struct{}`)
+	makePkg(genericPkg + `a; import "generic_lib"; var A generic_lib.T[int]`)
+	makePkg(genericPkg + `b; import "generic_lib"; var B generic_lib.T[int]`)
+	a := imports["generic_a"].Scope().Lookup("A")
+	b := imports["generic_b"].Scope().Lookup("B")
+	if !Identical(a.Type(), b.Type()) {
+		t.Errorf("mismatching types: a.A: %s, b.B: %s", a.Type(), b.Type())
+	}
+}
diff --git a/src/go/types/api_typeparams.go b/src/go/types/api_typeparams.go
deleted file mode 100644
index ed744c4dba6a151623c283bbb396f4d9933ad555..0000000000000000000000000000000000000000
--- a/src/go/types/api_typeparams.go
+++ /dev/null
@@ -1,53 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package types
-
-import (
-	"go/ast"
-)
-
-type (
-	Inferred  = _Inferred
-	Sum       = _Sum
-	TypeParam = _TypeParam
-)
-
-func NewSum(types []Type) Type { return _NewSum(types) }
-
-func (s *Signature) TParams() []*TypeName           { return s._TParams() }
-func (s *Signature) SetTParams(tparams []*TypeName) { s._SetTParams(tparams) }
-
-func (t *Interface) HasTypeList() bool  { return t._HasTypeList() }
-func (t *Interface) IsComparable() bool { return t._IsComparable() }
-func (t *Interface) IsConstraint() bool { return t._IsConstraint() }
-
-func (t *Named) TParams() []*TypeName { return t._TParams() }
-func (t *Named) TArgs() []Type        { return t._TArgs() }
-func (t *Named) SetTArgs(args []Type) { t._SetTArgs(args) }
-
-// Info is documented in api_notypeparams.go.
-type Info struct {
-	Types map[ast.Expr]TypeAndValue
-
-	// Inferred maps calls of parameterized functions that use type inference to
-	// the Inferred type arguments and signature of the function called. The
-	// recorded "call" expression may be an *ast.CallExpr (as in f(x)), or an
-	// *ast.IndexExpr (s in f[T]).
-	Inferred map[ast.Expr]_Inferred
-
-	Defs       map[*ast.Ident]Object
-	Uses       map[*ast.Ident]Object
-	Implicits  map[ast.Node]Object
-	Selections map[*ast.SelectorExpr]*Selection
-	Scopes     map[ast.Node]*Scope
-	InitOrder  []*Initializer
-}
-
-func getInferred(info *Info) map[ast.Expr]_Inferred {
-	return info.Inferred
-}
diff --git a/src/go/types/api_typeparams_test.go b/src/go/types/api_typeparams_test.go
deleted file mode 100644
index 15c9bf09f9dfccc8910369422b1218f341535621..0000000000000000000000000000000000000000
--- a/src/go/types/api_typeparams_test.go
+++ /dev/null
@@ -1,139 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package types_test
-
-import (
-	"fmt"
-	"go/ast"
-	"testing"
-
-	. "go/types"
-)
-
-func TestInferredInfo(t *testing.T) {
-	var tests = []struct {
-		src   string
-		fun   string
-		targs []string
-		sig   string
-	}{
-		{genericPkg + `p0; func f[T any](T); func _() { f(42) }`,
-			`f`,
-			[]string{`int`},
-			`func(int)`,
-		},
-		{genericPkg + `p1; func f[T any](T) T; func _() { f('@') }`,
-			`f`,
-			[]string{`rune`},
-			`func(rune) rune`,
-		},
-		{genericPkg + `p2; func f[T any](...T) T; func _() { f(0i) }`,
-			`f`,
-			[]string{`complex128`},
-			`func(...complex128) complex128`,
-		},
-		{genericPkg + `p3; func f[A, B, C any](A, *B, []C); func _() { f(1.2, new(string), []byte{}) }`,
-			`f`,
-			[]string{`float64`, `string`, `byte`},
-			`func(float64, *string, []byte)`,
-		},
-		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B); func _() { f(1.2, new(byte)) }`,
-			`f`,
-			[]string{`float64`, `byte`},
-			`func(float64, *byte, ...[]byte)`,
-		},
-
-		{genericPkg + `s1; func f[T any, P interface{type *T}](x T); func _(x string) { f(x) }`,
-			`f`,
-			[]string{`string`, `*string`},
-			`func(x string)`,
-		},
-		{genericPkg + `s2; func f[T any, P interface{type *T}](x []T); func _(x []int) { f(x) }`,
-			`f`,
-			[]string{`int`, `*int`},
-			`func(x []int)`,
-		},
-		{genericPkg + `s3; type C[T any] interface{type chan<- T}; func f[T any, P C[T]](x []T); func _(x []int) { f(x) }`,
-			`f`,
-			[]string{`int`, `chan<- int`},
-			`func(x []int)`,
-		},
-		{genericPkg + `s4; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T); func _(x []int) { f(x) }`,
-			`f`,
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
-			`func(x []int)`,
-		},
-
-		{genericPkg + `t1; func f[T any, P interface{type *T}]() T; func _() { _ = f[string] }`,
-			`f`,
-			[]string{`string`, `*string`},
-			`func() string`,
-		},
-		{genericPkg + `t2; type C[T any] interface{type chan<- T}; func f[T any, P C[T]]() []T; func _() { _ = f[int] }`,
-			`f`,
-			[]string{`int`, `chan<- int`},
-			`func() []int`,
-		},
-		{genericPkg + `t3; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T; func _() { _ = f[int] }`,
-			`f`,
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
-			`func() []int`,
-		},
-	}
-
-	for _, test := range tests {
-		info := Info{}
-		info.Inferred = make(map[ast.Expr]Inferred)
-		name, err := mayTypecheck(t, "InferredInfo", test.src, &info)
-		if err != nil {
-			t.Errorf("package %s: %v", name, err)
-			continue
-		}
-
-		// look for inferred type arguments and signature
-		var targs []Type
-		var sig *Signature
-		for call, inf := range info.Inferred {
-			var fun ast.Expr
-			switch x := call.(type) {
-			case *ast.CallExpr:
-				fun = x.Fun
-			case *ast.IndexExpr:
-				fun = x.X
-			default:
-				panic(fmt.Sprintf("unexpected call expression type %T", call))
-			}
-			if ExprString(fun) == test.fun {
-				targs = inf.Targs
-				sig = inf.Sig
-				break
-			}
-		}
-		if targs == nil {
-			t.Errorf("package %s: no inferred information found for %s", name, test.fun)
-			continue
-		}
-
-		// check that type arguments are correct
-		if len(targs) != len(test.targs) {
-			t.Errorf("package %s: got %d type arguments; want %d", name, len(targs), len(test.targs))
-			continue
-		}
-		for i, targ := range targs {
-			if got := targ.String(); got != test.targs[i] {
-				t.Errorf("package %s, %d. type argument: got %s; want %s", name, i, got, test.targs[i])
-				continue
-			}
-		}
-
-		// check that signature is correct
-		if got := sig.String(); got != test.sig {
-			t.Errorf("package %s: got %s; want %s", name, got, test.sig)
-		}
-	}
-}
diff --git a/src/go/types/array.go b/src/go/types/array.go
new file mode 100644
index 0000000000000000000000000000000000000000..5b28474bb339ec682481cf623c29399ad81b24bd
--- /dev/null
+++ b/src/go/types/array.go
@@ -0,0 +1,25 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// An Array represents an array type.
+type Array struct {
+	len  int64
+	elem Type
+}
+
+// NewArray returns a new array type for the given element type and length.
+// A negative length indicates an unknown length.
+func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
+
+// Len returns the length of array a.
+// A negative result indicates an unknown length.
+func (a *Array) Len() int64 { return a.len }
+
+// Elem returns element type of array a.
+func (a *Array) Elem() Type { return a.elem }
+
+func (t *Array) Underlying() Type { return t }
+func (t *Array) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index 18eae62184028ade83978e76483ebc20ba8c1102..595f426e1090a209c589edb80f305bd0ab146a68 100644
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -71,7 +71,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 	}
 
 	// A generic (non-instantiated) function value cannot be assigned to a variable.
-	if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+	if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 		check.errorf(x, _Todo, "cannot use generic function %s without instantiation in %s", x, context)
 	}
 
diff --git a/src/go/types/basic.go b/src/go/types/basic.go
new file mode 100644
index 0000000000000000000000000000000000000000..215923f6573a560f422a2201b5330d6fe853094b
--- /dev/null
+++ b/src/go/types/basic.go
@@ -0,0 +1,82 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// BasicKind describes the kind of basic type.
+type BasicKind int
+
+const (
+	Invalid BasicKind = iota // type is invalid
+
+	// predeclared types
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	String
+	UnsafePointer
+
+	// types for untyped values
+	UntypedBool
+	UntypedInt
+	UntypedRune
+	UntypedFloat
+	UntypedComplex
+	UntypedString
+	UntypedNil
+
+	// aliases
+	Byte = Uint8
+	Rune = Int32
+)
+
+// BasicInfo is a set of flags describing properties of a basic type.
+type BasicInfo int
+
+// Properties of basic types.
+const (
+	IsBoolean BasicInfo = 1 << iota
+	IsInteger
+	IsUnsigned
+	IsFloat
+	IsComplex
+	IsString
+	IsUntyped
+
+	IsOrdered   = IsInteger | IsFloat | IsString
+	IsNumeric   = IsInteger | IsFloat | IsComplex
+	IsConstType = IsBoolean | IsNumeric | IsString
+)
+
+// A Basic represents a basic type.
+type Basic struct {
+	kind BasicKind
+	info BasicInfo
+	name string
+}
+
+// Kind returns the kind of basic type b.
+func (b *Basic) Kind() BasicKind { return b.kind }
+
+// Info returns information about properties of basic type b.
+func (b *Basic) Info() BasicInfo { return b.info }
+
+// Name returns the name of basic type b.
+func (b *Basic) Name() string { return b.name }
+
+func (t *Basic) Underlying() Type { return t }
+func (t *Basic) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 2a2d54da88227a60bcb6f5c3dfbf019db61faed4..698435bc207be0e5c1f853bf61754f6e570f1443 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -47,7 +47,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 	default:
 		// make argument getter
 		xlist, _ := check.exprList(call.Args, false)
-		arg = func(x *operand, i int) { *x = *xlist[i]; x.typ = expand(x.typ) }
+		arg = func(x *operand, i int) { *x = *xlist[i] }
 		nargs = len(xlist)
 		// evaluate first argument, if present
 		if nargs > 0 {
@@ -145,7 +145,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		mode := invalid
 		var typ Type
 		var val constant.Value
-		switch typ = implicitArrayDeref(optype(x.typ)); t := typ.(type) {
+		switch typ = arrayPtrDeref(under(x.typ)); t := typ.(type) {
 		case *Basic:
 			if isString(t) && id == _Len {
 				if x.mode == constant_ {
@@ -179,9 +179,9 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 				mode = value
 			}
 
-		case *_Sum:
-			if t.is(func(t Type) bool {
-				switch t := under(t).(type) {
+		case *TypeParam:
+			if t.underIs(func(t Type) bool {
+				switch t := arrayPtrDeref(t).(type) {
 				case *Basic:
 					if isString(t) && id == _Len {
 						return true
@@ -217,19 +217,23 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 
 	case _Close:
 		// close(c)
-		c := asChan(x.typ)
-		if c == nil {
-			check.invalidArg(x, _InvalidClose, "%s is not a channel", x)
-			return
-		}
-		if c.dir == RecvOnly {
-			check.invalidArg(x, _InvalidClose, "%s must not be a receive-only channel", x)
+		if !underIs(x.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.invalidOp(x, _InvalidClose, "cannot close non-channel %s", x)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.invalidOp(x, _InvalidClose, "cannot close receive-only channel %s", x)
+				return false
+			}
+			return true
+		}) {
 			return
 		}
-
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, c))
+			check.recordBuiltinType(call.Fun, makeSig(nil, x.typ))
 		}
 
 	case _Complex:
@@ -286,7 +290,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		// both argument types must be identical
-		if !check.identical(x.typ, y.typ) {
+		if !Identical(x.typ, y.typ) {
 			check.invalidArg(x, _InvalidComplex, "mismatched types %s and %s", x.typ, y.typ)
 			return
 		}
@@ -337,13 +341,15 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 		var src Type
-		switch t := optype(y.typ).(type) {
+		switch t := under(y.typ).(type) {
 		case *Basic:
 			if isString(y.typ) {
 				src = universeByte
 			}
 		case *Slice:
 			src = t.elem
+		case *TypeParam:
+			check.error(x, _Todo, "copy on generic operands not yet implemented")
 		}
 
 		if dst == nil || src == nil {
@@ -351,7 +357,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 
-		if !check.identical(dst, src) {
+		if !Identical(dst, src) {
 			check.invalidArg(x, _InvalidCopy, "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
 			return
 		}
@@ -363,25 +369,40 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		x.typ = Typ[Int]
 
 	case _Delete:
-		// delete(m, k)
-		m := asMap(x.typ)
-		if m == nil {
-			check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
+		// delete(map_, key)
+		// map_ must be a map type or a type parameter describing map types.
+		// The key cannot be a type parameter for now.
+		map_ := x.typ
+		var key Type
+		if !underIs(map_, func(u Type) bool {
+			map_, _ := u.(*Map)
+			if map_ == nil {
+				check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
+				return false
+			}
+			if key != nil && !Identical(map_.key, key) {
+				check.invalidArg(x, _Todo, "maps of %s must have identical key types", x)
+				return false
+			}
+			key = map_.key
+			return true
+		}) {
 			return
 		}
+
 		arg(x, 1) // k
 		if x.mode == invalid {
 			return
 		}
 
-		check.assignment(x, m.key, "argument to delete")
+		check.assignment(x, key, "argument to delete")
 		if x.mode == invalid {
 			return
 		}
 
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
+			check.recordBuiltinType(call.Fun, makeSig(nil, map_, key))
 		}
 
 	case _Imag, _Real:
@@ -460,39 +481,21 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 
-		min, max := -1, 10
-		var valid func(t Type) bool
-		valid = func(t Type) bool {
-			var m int
-			switch t := optype(t).(type) {
-			case *Slice:
-				m = 2
-			case *Map, *Chan:
-				m = 1
-			case *_Sum:
-				return t.is(valid)
-			default:
-				return false
-			}
-			if m > min {
-				min = m
-			}
-			if m+1 < max {
-				max = m + 1
-			}
-			return true
-		}
-
-		if !valid(T) {
+		var min int // minimum number of arguments
+		switch optype(T).(type) {
+		case *Slice:
+			min = 2
+		case *Map, *Chan:
+			min = 1
+		case *top:
+			check.invalidArg(arg0, _InvalidMake, "cannot make %s; type parameter has no structural type", arg0)
+			return
+		default:
 			check.invalidArg(arg0, _InvalidMake, "cannot make %s; type must be slice, map, or channel", arg0)
 			return
 		}
-		if nargs < min || max < nargs {
-			if min == max {
-				check.errorf(call, _WrongArgCount, "%v expects %d arguments; found %d", call, min, nargs)
-			} else {
-				check.errorf(call, _WrongArgCount, "%v expects %d or %d arguments; found %d", call, min, max, nargs)
-			}
+		if nargs < min || min+1 < nargs {
+			check.invalidOp(call, _WrongArgCount, "%v expects %d or %d arguments; found %d", call, min, min+1, nargs)
 			return
 		}
 
@@ -612,19 +615,22 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 
 	case _Alignof:
 		// unsafe.Alignof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.invalidOp(call, _Todo, "unsafe.Alignof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Alignof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Offsetof:
 		// unsafe.Offsetof(x T) uintptr, where x must be a selector
@@ -644,7 +650,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 
 		base := derefStructPtr(x.typ)
 		sel := selx.Sel.Name
-		obj, index, indirect := check.lookupFieldOrMethod(base, false, check.pkg, sel)
+		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
 		switch obj.(type) {
 		case nil:
 			check.invalidArg(x, _MissingFieldOrMethod, "%s has no single field %s", base, sel)
@@ -662,30 +668,52 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 
-		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
+		// TODO(gri) Should we pass x.typ instead of base (and have indirect report if derefStructPtr indirected)?
 		check.recordSelection(selx, FieldVal, base, obj, index, false)
 
-		offs := check.conf.offsetof(base, index)
-		x.mode = constant_
-		x.val = constant.MakeInt64(offs)
+		// record the selector expression (was bug - issue #47895)
+		{
+			mode := value
+			if x.mode == variable || indirect {
+				mode = variable
+			}
+			check.record(&operand{mode, selx, obj.Type(), nil, 0})
+		}
+
+		// The field offset is considered a variable even if the field is declared before
+		// the part of the struct which is variable-sized. This makes both the rules
+		// simpler and also permits (or at least doesn't prevent) a compiler from re-
+		// arranging struct fields if it wanted to.
+		if hasVarSize(base) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], obj.Type()))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.offsetof(base, index))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Sizeof:
 		// unsafe.Sizeof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.invalidOp(call, _Todo, "unsafe.Sizeof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Sizeof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Slice:
 		// unsafe.Slice(ptr *T, len IntegerType) []T
@@ -757,6 +785,25 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 	return true
 }
 
+// hasVarSize reports if the size of type t is variable due to type parameters.
+func hasVarSize(t Type) bool {
+	switch t := under(t).(type) {
+	case *Array:
+		return hasVarSize(t.elem)
+	case *Struct:
+		for _, f := range t.fields {
+			if hasVarSize(f.typ) {
+				return true
+			}
+		}
+	case *TypeParam:
+		return true
+	case *Named, *Union, *top:
+		unreachable()
+	}
+	return false
+}
+
 // applyTypeFunc applies f to x. If x is a type parameter,
 // the result is a type parameter constrained by an new
 // interface bound. The type bounds for that interface
@@ -768,10 +815,10 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
 	if tp := asTypeParam(x); tp != nil {
 		// Test if t satisfies the requirements for the argument
 		// type and collect possible result types at the same time.
-		var rtypes []Type
-		if !tp.Bound().is(func(x Type) bool {
-			if r := f(x); r != nil {
-				rtypes = append(rtypes, r)
+		var terms []*Term
+		if !tp.iface().typeSet().is(func(t *term) bool {
+			if r := f(t.typ); r != nil {
+				terms = append(terms, NewTerm(t.tilde, r))
 				return true
 			}
 			return false
@@ -779,11 +826,12 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
 			return nil
 		}
 
-		// construct a suitable new type parameter
-		tpar := NewTypeName(token.NoPos, nil /* = Universe pkg */, "", nil)
-		ptyp := check.newTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
-		tsum := _NewSum(rtypes)
-		ptyp.bound = &Interface{types: tsum, allMethods: markComplete, allTypes: tsum}
+		// Construct a suitable new type parameter for the sum type. The
+		// type param is placed in the current package so export/import
+		// works as expected.
+		tpar := NewTypeName(token.NoPos, check.pkg, "", nil)
+		ptyp := check.NewTypeParam(tpar, NewInterfaceType(nil, []Type{NewUnion(terms)})) // assigns type to tpar as a side-effect
+		ptyp.index = tp.index
 
 		return ptyp
 	}
@@ -807,10 +855,9 @@ func makeSig(res Type, args ...Type) *Signature {
 	return &Signature{params: params, results: result}
 }
 
-// implicitArrayDeref returns A if typ is of the form *A and A is an array;
+// arrayPtrDeref returns A if typ is of the form *A and A is an array;
 // otherwise it returns typ.
-//
-func implicitArrayDeref(typ Type) Type {
+func arrayPtrDeref(typ Type) Type {
 	if p, ok := typ.(*Pointer); ok {
 		if a := asArray(p.base); a != nil {
 			return a
diff --git a/src/go/types/builtins_test.go b/src/go/types/builtins_test.go
index 11de9a1ac1a45d17bba26ed2f41bdb7499015858..cee3d315e592f621b3ce2dbc5d87fa90ee439515 100644
--- a/src/go/types/builtins_test.go
+++ b/src/go/types/builtins_test.go
@@ -113,12 +113,15 @@ var builtinCalls = []struct {
 
 	{"Alignof", `_ = unsafe.Alignof(0)`, `invalid type`},                 // constant
 	{"Alignof", `var x struct{}; _ = unsafe.Alignof(x)`, `invalid type`}, // constant
+	{"Alignof", `var x P; _ = unsafe.Alignof(x)`, `func(p.P₁) uintptr`},
 
 	{"Offsetof", `var x struct{f bool}; _ = unsafe.Offsetof(x.f)`, `invalid type`},           // constant
 	{"Offsetof", `var x struct{_ int; f bool}; _ = unsafe.Offsetof((&x).f)`, `invalid type`}, // constant
+	{"Offsetof", `var x struct{_ int; f P}; _ = unsafe.Offsetof((&x).f)`, `func(p.P₁) uintptr`},
 
 	{"Sizeof", `_ = unsafe.Sizeof(0)`, `invalid type`},                 // constant
 	{"Sizeof", `var x struct{}; _ = unsafe.Sizeof(x)`, `invalid type`}, // constant
+	{"Sizeof", `var x P; _ = unsafe.Sizeof(x)`, `func(p.P₁) uintptr`},
 
 	{"Slice", `var p *int; _ = unsafe.Slice(p, 1)`, `func(*int, int) []int`},
 	{"Slice", `var p *byte; var n uintptr; _ = unsafe.Slice(p, n)`, `func(*byte, uintptr) []byte`},
@@ -151,8 +154,10 @@ func TestBuiltinSignatures(t *testing.T) {
 	}
 }
 
+// parseGenericSrc in types2 is not necessary. We can just parse in testBuiltinSignature below.
+
 func testBuiltinSignature(t *testing.T, name, src0, want string) {
-	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _() { %s }`, src0)
+	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _[P any]() { %s }`, src0)
 	f, err := parser.ParseFile(fset, "", src, 0)
 	if err != nil {
 		t.Errorf("%s: %s", src0, err)
diff --git a/src/go/types/call.go b/src/go/types/call.go
index 631ea426c6bbf42e5fe613e4936942a2e253d055..87eeef444b5b75d9de2e1de5302aba6438944324 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -16,23 +16,22 @@ import (
 
 // funcInst type-checks a function instantiation inst and returns the result in x.
 // The operand x must be the evaluation of inst.X and its type must be a signature.
-func (check *Checker) funcInst(x *operand, inst *ast.IndexExpr) {
-	xlist := typeparams.UnpackExpr(inst.Index)
-	targs := check.typeList(xlist)
+func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
+	targs := check.typeList(ix.Indices)
 	if targs == nil {
 		x.mode = invalid
-		x.expr = inst
+		x.expr = ix.Orig
 		return
 	}
-	assert(len(targs) == len(xlist))
+	assert(len(targs) == len(ix.Indices))
 
 	// check number of type arguments (got) vs number of type parameters (want)
 	sig := x.typ.(*Signature)
-	got, want := len(targs), len(sig.tparams)
+	got, want := len(targs), sig.TParams().Len()
 	if got > want {
-		check.errorf(xlist[got-1], _Todo, "got %d type arguments but want %d", got, want)
+		check.errorf(ix.Indices[got-1], _Todo, "got %d type arguments but want %d", got, want)
 		x.mode = invalid
-		x.expr = inst
+		x.expr = ix.Orig
 		return
 	}
 
@@ -40,11 +39,11 @@ func (check *Checker) funcInst(x *operand, inst *ast.IndexExpr) {
 	inferred := false
 
 	if got < want {
-		targs = check.infer(inst, sig.tparams, targs, nil, nil, true)
+		targs = check.infer(ix.Orig, sig.TParams().list(), targs, nil, nil, true)
 		if targs == nil {
 			// error was already reported
 			x.mode = invalid
-			x.expr = inst
+			x.expr = ix.Orig
 			return
 		}
 		got = len(targs)
@@ -55,34 +54,36 @@ func (check *Checker) funcInst(x *operand, inst *ast.IndexExpr) {
 	// determine argument positions (for error reporting)
 	// TODO(rFindley) use a positioner here? instantiate would need to be
 	//                updated accordingly.
-	poslist := make([]token.Pos, len(xlist))
-	for i, x := range xlist {
+	poslist := make([]token.Pos, len(ix.Indices))
+	for i, x := range ix.Indices {
 		poslist[i] = x.Pos()
 	}
 
 	// instantiate function signature
 	res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
-	assert(res.tparams == nil) // signature is not generic anymore
+	assert(res.TParams().Len() == 0) // signature is not generic anymore
 	if inferred {
-		check.recordInferred(inst, targs, res)
+		check.recordInferred(ix.Orig, targs, res)
 	}
 	x.typ = res
 	x.mode = value
-	x.expr = inst
+	x.expr = ix.Orig
 }
 
 func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
-	var inst *ast.IndexExpr
-	if iexpr, _ := call.Fun.(*ast.IndexExpr); iexpr != nil {
-		if check.indexExpr(x, iexpr) {
+	ix := typeparams.UnpackIndexExpr(call.Fun)
+	if ix != nil {
+		if check.indexExpr(x, ix) {
 			// Delay function instantiation to argument checking,
 			// where we combine type and value arguments for type
 			// inference.
 			assert(x.mode == value)
-			inst = iexpr
+		} else {
+			ix = nil
 		}
-		x.expr = iexpr
+		x.expr = call.Fun
 		check.record(x)
+
 	} else {
 		check.exprOrType(x, call.Fun)
 	}
@@ -108,8 +109,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 					break
 				}
 				if t := asInterface(T); t != nil {
-					check.completeInterface(token.NoPos, t)
-					if t._IsConstraint() {
+					if t.IsConstraint() {
 						check.errorf(call, _Todo, "cannot use interface %s in conversion (contains type list or is comparable)", T)
 						break
 					}
@@ -149,21 +149,20 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 
 	// evaluate type arguments, if any
 	var targs []Type
-	if inst != nil {
-		xlist := typeparams.UnpackExpr(inst.Index)
-		targs = check.typeList(xlist)
+	if ix != nil {
+		targs = check.typeList(ix.Indices)
 		if targs == nil {
 			check.use(call.Args...)
 			x.mode = invalid
 			x.expr = call
 			return statement
 		}
-		assert(len(targs) == len(xlist))
+		assert(len(targs) == len(ix.Indices))
 
 		// check number of type arguments (got) vs number of type parameters (want)
-		got, want := len(targs), len(sig.tparams)
+		got, want := len(targs), sig.TParams().Len()
 		if got > want {
-			check.errorf(xlist[want], _Todo, "got %d type arguments but want %d", got, want)
+			check.errorf(ix.Indices[want], _Todo, "got %d type arguments but want %d", got, want)
 			check.use(call.Args...)
 			x.mode = invalid
 			x.expr = call
@@ -195,7 +194,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 
 	// if type inference failed, a parametrized result must be invalidated
 	// (operands cannot have a parametrized type)
-	if x.mode == value && len(sig.tparams) > 0 && isParameterized(sig.tparams, x.typ) {
+	if x.mode == value && sig.TParams().Len() > 0 && isParameterized(sig.TParams().list(), x.typ) {
 		x.mode = invalid
 	}
 
@@ -224,7 +223,6 @@ func (check *Checker) exprList(elist []ast.Expr, allowCommaOk bool) (xlist []*op
 		// exactly one (possibly invalid or comma-ok) value
 		xlist = []*operand{&x}
 		if allowCommaOk && (x.mode == mapindex || x.mode == commaok || x.mode == commaerr) {
-			x.mode = value
 			x2 := &operand{mode: value, expr: e, typ: Typ[UntypedBool]}
 			if x.mode == commaerr {
 				x2.typ = universeError
@@ -325,24 +323,24 @@ func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type
 	}
 
 	// infer type arguments and instantiate signature if necessary
-	if len(sig.tparams) > 0 {
+	if sig.TParams().Len() > 0 {
 		// TODO(gri) provide position information for targs so we can feed
 		//           it to the instantiate call for better error reporting
-		targs := check.infer(call, sig.tparams, targs, sigParams, args, true)
+		targs := check.infer(call, sig.TParams().list(), targs, sigParams, args, true)
 		if targs == nil {
 			return // error already reported
 		}
 
 		// compute result signature
 		rsig = check.instantiate(call.Pos(), sig, targs, nil).(*Signature)
-		assert(rsig.tparams == nil) // signature is not generic anymore
+		assert(rsig.TParams().Len() == 0) // signature is not generic anymore
 		check.recordInferred(call, targs, rsig)
 
 		// Optimization: Only if the parameter list was adjusted do we
 		// need to compute it from the adjusted list; otherwise we can
 		// simply use the result signature's parameter list.
 		if adjusted {
-			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.tparams, targs)).(*Tuple)
+			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.TParams().list(), targs), nil).(*Tuple)
 		} else {
 			sigParams = rsig.params
 		}
@@ -471,7 +469,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 
 	check.instantiatedOperand(x)
 
-	obj, index, indirect = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
+	obj, index, indirect = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
 	if obj == nil {
 		switch {
 		case index != nil:
@@ -483,11 +481,10 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 			var why string
 			if tpar := asTypeParam(x.typ); tpar != nil {
 				// Type parameter bounds don't specify fields, so don't mention "field".
-				switch obj := tpar.Bound().obj.(type) {
-				case nil:
+				if tname := tpar.iface().obj; tname != nil {
+					why = check.sprintf("interface %s has no method %s", tname.name, sel)
+				} else {
 					why = check.sprintf("type bound for %s has no method %s", x.typ, sel)
-				case *TypeName:
-					why = check.sprintf("interface %s has no method %s", obj.name, sel)
 				}
 			} else {
 				why = check.sprintf("type %s has no field or method %s", x.typ, sel)
@@ -501,7 +498,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 				} else {
 					changeCase = string(unicode.ToUpper(r)) + sel[1:]
 				}
-				if obj, _, _ = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
+				if obj, _, _ = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
 					why += ", but does have " + changeCase
 				}
 			}
@@ -519,7 +516,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 		// the signature accordingly.
 		// TODO(gri) factor this code out
 		sig := m.typ.(*Signature)
-		if len(sig.rparams) > 0 {
+		if sig.RParams().Len() > 0 {
 			// For inference to work, we must use the receiver type
 			// matching the receiver in the actual method declaration.
 			// If the method is embedded, the matching receiver is the
@@ -547,7 +544,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 			// the receiver type arguments here, the receiver must be be otherwise invalid
 			// and an error has been reported elsewhere.
 			arg := operand{mode: variable, expr: x.expr, typ: recv}
-			targs := check.infer(m, sig.rparams, nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
+			targs := check.infer(m, sig.RParams().list(), nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
 			if targs == nil {
 				// We may reach here if there were other errors (see issue #40056).
 				goto Error
@@ -556,7 +553,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 			// (If we modify m, some tests will fail; possibly because the m is in use.)
 			// TODO(gri) investigate and provide a correct explanation here
 			copy := *m
-			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.rparams, targs))
+			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.RParams().list(), targs), nil)
 			obj = ©
 		}
 		// TODO(gri) we also need to do substitution for parameterized interface methods
@@ -575,17 +572,37 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 
 		check.recordSelection(e, MethodExpr, x.typ, m, index, indirect)
 
+		sig := m.typ.(*Signature)
+		if sig.recv == nil {
+			check.error(e, _InvalidDeclCycle, "illegal cycle in method declaration")
+			goto Error
+		}
+
 		// the receiver type becomes the type of the first function
 		// argument of the method expression's function type
 		var params []*Var
-		sig := m.typ.(*Signature)
 		if sig.params != nil {
 			params = sig.params.vars
 		}
+		// Be consistent about named/unnamed parameters. This is not needed
+		// for type-checking, but the newly constructed signature may appear
+		// in an error message and then have mixed named/unnamed parameters.
+		// (An alternative would be to not print parameter names in errors,
+		// but it's useful to see them; this is cheap and method expressions
+		// are rare.)
+		name := ""
+		if len(params) > 0 && params[0].name != "" {
+			// name needed
+			name = sig.recv.name
+			if name == "" {
+				name = "_"
+			}
+		}
+		params = append([]*Var{NewVar(sig.recv.pos, sig.recv.pkg, name, x.typ)}, params...)
 		x.mode = value
 		x.typ = &Signature{
 			tparams:  sig.tparams,
-			params:   NewTuple(append([]*Var{NewVar(token.NoPos, check.pkg, "_", x.typ)}, params...)...),
+			params:   NewTuple(params...),
 			results:  sig.results,
 			variadic: sig.variadic,
 		}
diff --git a/src/go/types/chan.go b/src/go/types/chan.go
new file mode 100644
index 0000000000000000000000000000000000000000..1f7b72be309c868c450151bdbf7100e70244f884
--- /dev/null
+++ b/src/go/types/chan.go
@@ -0,0 +1,35 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Chan represents a channel type.
+type Chan struct {
+	dir  ChanDir
+	elem Type
+}
+
+// A ChanDir value indicates a channel direction.
+type ChanDir int
+
+// The direction of a channel is indicated by one of these constants.
+const (
+	SendRecv ChanDir = iota
+	SendOnly
+	RecvOnly
+)
+
+// NewChan returns a new channel type for the given direction and element type.
+func NewChan(dir ChanDir, elem Type) *Chan {
+	return &Chan{dir: dir, elem: elem}
+}
+
+// Dir returns the direction of channel c.
+func (c *Chan) Dir() ChanDir { return c.dir }
+
+// Elem returns the element type of channel c.
+func (c *Chan) Elem() Type { return c.elem }
+
+func (t *Chan) Underlying() Type { return t }
+func (t *Chan) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/check.go b/src/go/types/check.go
index a923c3c612124f21f6baa59cec4967ee5084a271..909bf8d52d07182d43d823f5bddd57ef70497a5e 100644
--- a/src/go/types/check.go
+++ b/src/go/types/check.go
@@ -73,7 +73,7 @@ type importKey struct {
 // A dotImportKey describes a dot-imported object in the given scope.
 type dotImportKey struct {
 	scope *Scope
-	obj   Object
+	name  string
 }
 
 // A Checker maintains the state of the type checker.
@@ -85,11 +85,11 @@ type Checker struct {
 	fset *token.FileSet
 	pkg  *Package
 	*Info
-	version version                    // accepted language version
-	objMap  map[Object]*declInfo       // maps package-level objects and (non-interface) methods to declaration info
-	impMap  map[importKey]*Package     // maps (import path, source directory) to (complete or fake) package
-	posMap  map[*Interface][]token.Pos // maps interface types to lists of embedded interface positions
-	typMap  map[string]*Named          // maps an instantiated named type hash to a *Named type
+	version version                // accepted language version
+	nextID  uint64                 // unique Id for type parameters (first valid Id is 1)
+	objMap  map[Object]*declInfo   // maps package-level objects and (non-interface) methods to declaration info
+	impMap  map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
+	typMap  map[string]*Named      // maps an instantiated named type hash to a *Named type
 
 	// pkgPathMap maps package names to the set of distinct import paths we've
 	// seen for that name, anywhere in the import graph. It is used for
@@ -179,9 +179,9 @@ func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Ch
 		info = new(Info)
 	}
 
-	version, err := parseGoVersion(conf.goVersion)
+	version, err := parseGoVersion(conf.GoVersion)
 	if err != nil {
-		panic(fmt.Sprintf("invalid Go version %q (%v)", conf.goVersion, err))
+		panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
 	}
 
 	return &Checker{
@@ -192,7 +192,6 @@ func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Ch
 		version: version,
 		objMap:  make(map[Object]*declInfo),
 		impMap:  make(map[importKey]*Package),
-		posMap:  make(map[*Interface][]token.Pos),
 		typMap:  make(map[string]*Named),
 	}
 }
@@ -274,10 +273,6 @@ func (check *Checker) checkFiles(files []*ast.File) (err error) {
 
 	check.recordUntyped()
 
-	if check.Info != nil {
-		sanitizeInfo(check.Info)
-	}
-
 	check.pkg.complete = true
 
 	// no longer needed - release memory
@@ -411,8 +406,8 @@ func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
 func (check *Checker) recordInferred(call ast.Expr, targs []Type, sig *Signature) {
 	assert(call != nil)
 	assert(sig != nil)
-	if m := getInferred(check.Info); m != nil {
-		m[call] = _Inferred{targs, sig}
+	if m := check.Inferred; m != nil {
+		m[call] = Inferred{&TypeList{targs}, sig}
 	}
 }
 
diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index f83abf11ce2e22623cb1ff266ec0b2c4a2f6557f..8c8452c9c683d26c478fcef3b6808560c87f978e 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -202,15 +202,13 @@ func asGoVersion(s string) string {
 	return ""
 }
 
-func checkFiles(t *testing.T, sizes Sizes, goVersion string, filenames []string, srcs [][]byte, manual bool, imp Importer) {
+func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, manual bool, imp Importer) {
 	if len(filenames) == 0 {
 		t.Fatal("no source files")
 	}
 
-	if strings.HasSuffix(filenames[0], ".go2") && !typeparams.Enabled {
-		t.Skip("type params are not enabled")
-	}
-	if strings.HasSuffix(filenames[0], ".go1") && typeparams.Enabled {
+	if strings.HasSuffix(filenames[0], ".go1") {
+		// TODO(rfindley): re-enable this test by using GoVersion.
 		t.Skip("type params are enabled")
 	}
 
@@ -228,6 +226,7 @@ func checkFiles(t *testing.T, sizes Sizes, goVersion string, filenames []string,
 	}
 
 	// if no Go version is given, consider the package name
+	goVersion := *goVersion
 	if goVersion == "" {
 		goVersion = asGoVersion(pkgName)
 	}
@@ -243,7 +242,7 @@ func checkFiles(t *testing.T, sizes Sizes, goVersion string, filenames []string,
 	// typecheck and collect typechecker errors
 	var conf Config
 	conf.Sizes = sizes
-	SetGoVersion(&conf, goVersion)
+	conf.GoVersion = goVersion
 
 	// special case for importC.src
 	if len(filenames) == 1 {
@@ -303,29 +302,48 @@ func checkFiles(t *testing.T, sizes Sizes, goVersion string, filenames []string,
 	}
 }
 
-// TestManual is for manual testing of input files, provided as a list
-// of arguments after the test arguments (and a separating "--"). For
-// instance, to check the files foo.go and bar.go, use:
+// TestManual is for manual testing of a package - either provided
+// as a list of filenames belonging to the package, or a directory
+// name containing the package files - after the test arguments
+// (and a separating "--"). For instance, to test the package made
+// of the files foo.go and bar.go, use:
 //
 // 	go test -run Manual -- foo.go bar.go
 //
-// Provide the -verify flag to verify errors against ERROR comments in
-// the input files rather than having a list of errors reported.
-// The accepted Go language version can be controlled with the -lang flag.
+// If no source arguments are provided, the file testdata/manual.go2
+// is used instead.
+// Provide the -verify flag to verify errors against ERROR comments
+// in the input files rather than having a list of errors reported.
+// The accepted Go language version can be controlled with the -lang
+// flag.
 func TestManual(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
 	filenames := flag.Args()
 	if len(filenames) == 0 {
-		return
+		filenames = []string{filepath.FromSlash("testdata/manual.go2")}
 	}
-	testenv.MustHaveGoBuild(t)
+
+	info, err := os.Stat(filenames[0])
+	if err != nil {
+		t.Fatalf("TestManual: %v", err)
+	}
+
 	DefPredeclaredTestFuncs()
-	testPkg(t, filenames, *goVersion, true)
+	if info.IsDir() {
+		if len(filenames) > 1 {
+			t.Fatal("TestManual: must have only one directory argument")
+		}
+		testDir(t, filenames[0], true)
+	} else {
+		testPkg(t, filenames, true)
+	}
 }
 
 func TestLongConstants(t *testing.T) {
 	format := "package longconst\n\nconst _ = %s\nconst _ = %s // ERROR excessively long constant"
 	src := fmt.Sprintf(format, strings.Repeat("1", 9999), strings.Repeat("1", 10001))
-	checkFiles(t, nil, "", []string{"longconst.go"}, [][]byte{[]byte(src)}, false, nil)
+	testFiles(t, nil, []string{"longconst.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
 // TestIndexRepresentability tests that constant index operands must
@@ -333,32 +351,24 @@ func TestLongConstants(t *testing.T) {
 // represent larger values.
 func TestIndexRepresentability(t *testing.T) {
 	const src = "package index\n\nvar s []byte\nvar _ = s[int64 /* ERROR \"int64\\(1\\) << 40 \\(.*\\) overflows int\" */ (1) << 40]"
-	checkFiles(t, &StdSizes{4, 4}, "", []string{"index.go"}, [][]byte{[]byte(src)}, false, nil)
-}
-
-func TestIssue46453(t *testing.T) {
-	if typeparams.Enabled {
-		t.Skip("type params are enabled")
-	}
-	const src = "package p\ntype _ comparable // ERROR \"undeclared name: comparable\""
-	checkFiles(t, nil, "", []string{"issue46453.go"}, [][]byte{[]byte(src)}, false, nil)
+	testFiles(t, &StdSizes{4, 4}, []string{"index.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
 func TestIssue47243_TypedRHS(t *testing.T) {
 	// The RHS of the shift expression below overflows uint on 32bit platforms,
 	// but this is OK as it is explicitly typed.
 	const src = "package issue47243\n\nvar a uint64; var _ = a << uint64(4294967296)" // uint64(1<<32)
-	checkFiles(t, &StdSizes{4, 4}, "", []string{"p.go"}, [][]byte{[]byte(src)}, false, nil)
+	testFiles(t, &StdSizes{4, 4}, []string{"p.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
-func TestCheck(t *testing.T)     { DefPredeclaredTestFuncs(); testDir(t, "check") }
-func TestExamples(t *testing.T)  { testDir(t, "examples") }
-func TestFixedbugs(t *testing.T) { testDir(t, "fixedbugs") }
+func TestCheck(t *testing.T)     { DefPredeclaredTestFuncs(); testDirFiles(t, "testdata/check", false) }
+func TestExamples(t *testing.T)  { testDirFiles(t, "testdata/examples", false) }
+func TestFixedbugs(t *testing.T) { testDirFiles(t, "testdata/fixedbugs", false) }
 
-func testDir(t *testing.T, dir string) {
+func testDirFiles(t *testing.T, dir string, manual bool) {
 	testenv.MustHaveGoBuild(t)
+	dir = filepath.FromSlash(dir)
 
-	dir = filepath.Join("testdata", dir)
 	fis, err := os.ReadDir(dir)
 	if err != nil {
 		t.Error(err)
@@ -368,28 +378,38 @@ func testDir(t *testing.T, dir string) {
 	for _, fi := range fis {
 		path := filepath.Join(dir, fi.Name())
 
-		// if fi is a directory, its files make up a single package
-		var filenames []string
+		// If fi is a directory, its files make up a single package.
 		if fi.IsDir() {
-			fis, err := os.ReadDir(path)
-			if err != nil {
-				t.Error(err)
-				continue
-			}
-			for _, fi := range fis {
-				filenames = append(filenames, filepath.Join(path, fi.Name()))
-			}
+			testDir(t, path, manual)
 		} else {
-			filenames = []string{path}
+			t.Run(filepath.Base(path), func(t *testing.T) {
+				testPkg(t, []string{path}, manual)
+			})
 		}
-		t.Run(filepath.Base(path), func(t *testing.T) {
-			testPkg(t, filenames, "", false)
-		})
 	}
 }
 
+func testDir(t *testing.T, dir string, manual bool) {
+	testenv.MustHaveGoBuild(t)
+
+	fis, err := os.ReadDir(dir)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	var filenames []string
+	for _, fi := range fis {
+		filenames = append(filenames, filepath.Join(dir, fi.Name()))
+	}
+
+	t.Run(filepath.Base(dir), func(t *testing.T) {
+		testPkg(t, filenames, manual)
+	})
+}
+
 // TODO(rFindley) reconcile the different test setup in go/types with types2.
-func testPkg(t *testing.T, filenames []string, goVersion string, manual bool) {
+func testPkg(t *testing.T, filenames []string, manual bool) {
 	srcs := make([][]byte, len(filenames))
 	for i, filename := range filenames {
 		src, err := os.ReadFile(filename)
@@ -398,5 +418,5 @@ func testPkg(t *testing.T, filenames []string, goVersion string, manual bool) {
 		}
 		srcs[i] = src
 	}
-	checkFiles(t, nil, goVersion, filenames, srcs, manual, nil)
+	testFiles(t, nil, filenames, srcs, manual, nil)
 }
diff --git a/src/go/types/conversions.go b/src/go/types/conversions.go
index ad6d3eef1027a839d0c0dea3e87172cde7ef8c02..a1fcdd4fd8dfd5ddb8bc22c6e08d04f2ed4c8aeb 100644
--- a/src/go/types/conversions.go
+++ b/src/go/types/conversions.go
@@ -94,7 +94,7 @@ func (x *operand) convertibleTo(check *Checker, T Type, reason *string) bool {
 	V := x.typ
 	Vu := under(V)
 	Tu := under(T)
-	if check.identicalIgnoreTags(Vu, Tu) {
+	if IdenticalIgnoreTags(Vu, Tu) {
 		return true
 	}
 
@@ -102,7 +102,7 @@ func (x *operand) convertibleTo(check *Checker, T Type, reason *string) bool {
 	// have identical underlying types if tags are ignored"
 	if V, ok := V.(*Pointer); ok {
 		if T, ok := T.(*Pointer); ok {
-			if check.identicalIgnoreTags(under(V.base), under(T.base)) {
+			if IdenticalIgnoreTags(under(V.base), under(T.base)) {
 				return true
 			}
 		}
@@ -143,7 +143,7 @@ func (x *operand) convertibleTo(check *Checker, T Type, reason *string) bool {
 	if s := asSlice(V); s != nil {
 		if p := asPointer(T); p != nil {
 			if a := asArray(p.Elem()); a != nil {
-				if check.identical(s.Elem(), a.Elem()) {
+				if Identical(s.Elem(), a.Elem()) {
 					if check == nil || check.allowVersion(check.pkg, 1, 17) {
 						return true
 					}
diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index 9211febc6da1620a43e9867af2f37c149a6f0753..8ebaf289f1e5e17950887d502c9785c9a73c9039 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -317,6 +317,7 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo {
 		}
 
 	case *Named:
+		t.expand(check.typMap)
 		// don't touch the type if it is from a different package or the Universe scope
 		// (doing so would lead to a race condition - was issue #35049)
 		if t.obj.pkg != check.pkg {
@@ -333,12 +334,12 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo {
 		switch t.info {
 		case unknown:
 			t.info = marked
-			t.info = check.validType(t.orig, append(path, t.obj)) // only types of current package added to path
+			t.info = check.validType(t.fromRHS, append(path, t.obj)) // only types of current package added to path
 		case marked:
 			// cycle detected
 			for i, tn := range path {
 				if t.obj.pkg != check.pkg {
-					panic("internal error: type cycle via package-external type")
+					panic("type cycle via package-external type")
 				}
 				if tn == t.obj {
 					check.cycleError(path[i:])
@@ -346,12 +347,9 @@ func (check *Checker) validType(typ Type, path []Object) typeInfo {
 					return t.info
 				}
 			}
-			panic("internal error: cycle start not found")
+			panic("cycle start not found")
 		}
 		return t.info
-
-	case *instance:
-		return check.validType(t.expand(), path)
 	}
 
 	return valid
@@ -569,102 +567,6 @@ func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
 	check.initVars(lhs, []ast.Expr{init}, token.NoPos)
 }
 
-// under returns the expanded underlying type of n0; possibly by following
-// forward chains of named types. If an underlying type is found, resolve
-// the chain by setting the underlying type for each defined type in the
-// chain before returning it. If no underlying type is found or a cycle
-// is detected, the result is Typ[Invalid]. If a cycle is detected and
-// n0.check != nil, the cycle is reported.
-func (n0 *Named) under() Type {
-	u := n0.underlying
-
-	if u == Typ[Invalid] {
-		return u
-	}
-
-	// If the underlying type of a defined type is not a defined
-	// (incl. instance) type, then that is the desired underlying
-	// type.
-	switch u.(type) {
-	case nil:
-		return Typ[Invalid]
-	default:
-		// common case
-		return u
-	case *Named, *instance:
-		// handled below
-	}
-
-	if n0.check == nil {
-		panic("internal error: Named.check == nil but type is incomplete")
-	}
-
-	// Invariant: after this point n0 as well as any named types in its
-	// underlying chain should be set up when this function exits.
-	check := n0.check
-
-	// If we can't expand u at this point, it is invalid.
-	n := asNamed(u)
-	if n == nil {
-		n0.underlying = Typ[Invalid]
-		return n0.underlying
-	}
-
-	// Otherwise, follow the forward chain.
-	seen := map[*Named]int{n0: 0}
-	path := []Object{n0.obj}
-	for {
-		u = n.underlying
-		if u == nil {
-			u = Typ[Invalid]
-			break
-		}
-		var n1 *Named
-		switch u1 := u.(type) {
-		case *Named:
-			n1 = u1
-		case *instance:
-			n1, _ = u1.expand().(*Named)
-			if n1 == nil {
-				u = Typ[Invalid]
-			}
-		}
-		if n1 == nil {
-			break // end of chain
-		}
-
-		seen[n] = len(seen)
-		path = append(path, n.obj)
-		n = n1
-
-		if i, ok := seen[n]; ok {
-			// cycle
-			check.cycleError(path[i:])
-			u = Typ[Invalid]
-			break
-		}
-	}
-
-	for n := range seen {
-		// We should never have to update the underlying type of an imported type;
-		// those underlying types should have been resolved during the import.
-		// Also, doing so would lead to a race condition (was issue #31749).
-		// Do this check always, not just in debug mode (it's cheap).
-		if n.obj.pkg != check.pkg {
-			panic("internal error: imported type with unresolved underlying type")
-		}
-		n.underlying = u
-	}
-
-	return u
-}
-
-func (n *Named) setUnderlying(typ Type) {
-	if n != nil {
-		n.underlying = typ
-	}
-}
-
 func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
 	assert(obj.typ == nil)
 
@@ -680,58 +582,57 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
 		alias = false
 	}
 
+	// alias declaration
 	if alias {
-		// type alias declaration
 		if !check.allowVersion(check.pkg, 1, 9) {
 			check.errorf(atPos(tdecl.Assign), _BadDecl, "type aliases requires go1.9 or later")
 		}
 
 		obj.typ = Typ[Invalid]
 		obj.typ = check.anyType(tdecl.Type)
+		return
+	}
 
-	} else {
-		// defined type declaration
-
-		named := check.newNamed(obj, nil, nil)
-		def.setUnderlying(named)
-		obj.typ = named // make sure recursive type declarations terminate
-
-		if tparams := typeparams.Get(tdecl); tparams != nil {
-			check.openScope(tdecl, "type parameters")
-			defer check.closeScope()
-			named.tparams = check.collectTypeParams(tparams)
-		}
-
-		// determine underlying type of named
-		named.orig = check.definedType(tdecl.Type, named)
+	// type definition or generic type declaration
+	named := check.newNamed(obj, nil, nil, nil, nil)
+	def.setUnderlying(named)
 
-		// The underlying type of named may be itself a named type that is
-		// incomplete:
-		//
-		//	type (
-		//		A B
-		//		B *C
-		//		C A
-		//	)
-		//
-		// The type of C is the (named) type of A which is incomplete,
-		// and which has as its underlying type the named type B.
-		// Determine the (final, unnamed) underlying type by resolving
-		// any forward chain.
-		// TODO(gri) Investigate if we can just use named.origin here
-		//           and rely on lazy computation of the underlying type.
-		named.underlying = under(named)
+	if tparams := typeparams.Get(tdecl); tparams != nil {
+		check.openScope(tdecl, "type parameters")
+		defer check.closeScope()
+		named.tparams = check.collectTypeParams(tparams)
 	}
 
-}
+	// determine underlying type of named
+	named.fromRHS = check.definedType(tdecl.Type, named)
+	assert(named.fromRHS != nil)
 
-func (check *Checker) collectTypeParams(list *ast.FieldList) (tparams []*TypeName) {
-	// Type parameter lists should not be empty. The parser will
-	// complain but we still may get an incorrect AST: ignore it.
-	if list.NumFields() == 0 {
-		return
+	// The underlying type of named may be itself a named type that is
+	// incomplete:
+	//
+	//	type (
+	//		A B
+	//		B *C
+	//		C A
+	//	)
+	//
+	// The type of C is the (named) type of A which is incomplete,
+	// and which has as its underlying type the named type B.
+	// Determine the (final, unnamed) underlying type by resolving
+	// any forward chain.
+	// TODO(gri) Investigate if we can just use named.fromRHS here
+	//           and rely on lazy computation of the underlying type.
+	named.underlying = under(named)
+
+	// If the RHS is a type parameter, it must be from this type declaration.
+	if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.TParams().list(), tpar) < 0 {
+		check.errorf(tdecl.Type, _Todo, "cannot use function type parameter %s as RHS in type declaration", tpar)
+		named.underlying = Typ[Invalid]
 	}
+}
 
+func (check *Checker) collectTypeParams(list *ast.FieldList) *TParamList {
+	var tparams []*TypeParam
 	// Declare type parameters up-front, with empty interface as type bound.
 	// The scope of type parameters starts at the beginning of the type parameter
 	// list (so we can have mutually recursive parameterized interfaces).
@@ -739,53 +640,29 @@ func (check *Checker) collectTypeParams(list *ast.FieldList) (tparams []*TypeNam
 		tparams = check.declareTypeParams(tparams, f.Names)
 	}
 
-	setBoundAt := func(at int, bound Type) {
-		assert(IsInterface(bound))
-		tparams[at].typ.(*_TypeParam).bound = bound
-	}
-
 	index := 0
 	var bound Type
 	for _, f := range list.List {
 		if f.Type == nil {
 			goto next
 		}
-
-		// The predeclared identifier "any" is visible only as a constraint
-		// in a type parameter list. Look for it before general constraint
-		// resolution.
-		if tident, _ := unparen(f.Type).(*ast.Ident); tident != nil && tident.Name == "any" && check.lookup("any") == nil {
-			bound = universeAny
-		} else {
-			bound = check.typ(f.Type)
-		}
-
-		// type bound must be an interface
-		// TODO(gri) We should delay the interface check because
-		//           we may not have a complete interface yet:
-		//           type C(type T C) interface {}
-		//           (issue #39724).
-		if _, ok := under(bound).(*Interface); ok {
-			// Otherwise, set the bound for each type parameter.
-			for i := range f.Names {
-				setBoundAt(index+i, bound)
-			}
-		} else if bound != Typ[Invalid] {
-			check.errorf(f.Type, _Todo, "%s is not an interface", bound)
+		bound = check.boundType(f.Type)
+		for i := range f.Names {
+			tparams[index+i].bound = bound
 		}
 
 	next:
 		index += len(f.Names)
 	}
 
-	return
+	return bindTParams(tparams)
 }
 
-func (check *Checker) declareTypeParams(tparams []*TypeName, names []*ast.Ident) []*TypeName {
+func (check *Checker) declareTypeParams(tparams []*TypeParam, names []*ast.Ident) []*TypeParam {
 	for _, name := range names {
-		tpar := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
-		check.newTypeParam(tpar, len(tparams), &emptyInterface) // assigns type to tpar as a side-effect
-		check.declare(check.scope, name, tpar, check.scope.pos) // TODO(gri) check scope position
+		tname := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
+		tpar := check.NewTypeParam(tname, &emptyInterface)       // assigns type to tpar as a side-effect
+		check.declare(check.scope, name, tname, check.scope.pos) // TODO(gri) check scope position
 		tparams = append(tparams, tpar)
 	}
 
@@ -796,6 +673,25 @@ func (check *Checker) declareTypeParams(tparams []*TypeName, names []*ast.Ident)
 	return tparams
 }
 
+// boundType type-checks the type expression e and returns its type, or Typ[Invalid].
+// The type must be an interface, including the predeclared type "any".
+func (check *Checker) boundType(e ast.Expr) Type {
+	// The predeclared identifier "any" is visible only as a type bound in a type parameter list.
+	// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+	if name, _ := unparen(e).(*ast.Ident); name != nil && name.Name == "any" && check.lookup("any") == universeAny {
+		return universeAny.Type()
+	}
+
+	bound := check.typ(e)
+	check.later(func() {
+		u := under(bound)
+		if _, ok := u.(*Interface); !ok && u != Typ[Invalid] {
+			check.errorf(e, _Todo, "%s is not an interface", bound)
+		}
+	})
+	return bound
+}
+
 func (check *Checker) collectMethods(obj *TypeName) {
 	// get associated methods
 	// (Checker.collectObjects only collects methods with non-blank names;
@@ -815,7 +711,8 @@ func (check *Checker) collectMethods(obj *TypeName) {
 	// and field names must be distinct."
 	base := asNamed(obj.typ) // shouldn't fail but be conservative
 	if base != nil {
-		if t, _ := base.underlying.(*Struct); t != nil {
+		u := safeUnderlying(base) // base should be expanded, but use safeUnderlying to be conservative
+		if t, _ := u.(*Struct); t != nil {
 			for _, fld := range t.fields {
 				if fld.name != "_" {
 					assert(mset.insert(fld) == nil)
@@ -851,6 +748,7 @@ func (check *Checker) collectMethods(obj *TypeName) {
 		}
 
 		if base != nil {
+			base.load() // TODO(mdempsky): Probably unnecessary.
 			base.methods = append(base.methods, m)
 		}
 	}
@@ -877,6 +775,10 @@ func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
 	check.funcType(sig, fdecl.Recv, fdecl.Type)
 	obj.color_ = saved
 
+	if fdecl.Type.TParams.NumFields() > 0 && fdecl.Body == nil {
+		check.softErrorf(fdecl.Name, _Todo, "parameterized function is missing function body")
+	}
+
 	// function body must be type-checked after global declarations
 	// (functions implemented elsewhere have no body)
 	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
diff --git a/src/go/types/errorcodes.go b/src/go/types/errorcodes.go
index 3d24da7b533cf89d5851a204dd8c373b2567d3dc..bcc850f75381f32bd6ca3f7c88b708195c5d8e04 100644
--- a/src/go/types/errorcodes.go
+++ b/src/go/types/errorcodes.go
@@ -281,16 +281,7 @@ const (
 	_IncomparableMapKey
 
 	// _InvalidIfaceEmbed occurs when a non-interface type is embedded in an
-	// interface.
-	//
-	// Example:
-	//  type T struct {}
-	//
-	//  func (T) m()
-	//
-	//  type I interface {
-	//  	T
-	//  }
+	// interface (for go 1.17 or earlier).
 	_InvalidIfaceEmbed
 
 	// _InvalidPtrEmbed occurs when an embedded field is of the pointer form *T,
@@ -884,7 +875,7 @@ const (
 	// context in which it is used.
 	//
 	// Example:
-	//  var _ = 1 + ""
+	//  var _ = 1 + nil
 	_InvalidUntypedConversion
 
 	// _BadOffsetofSyntax occurs when unsafe.Offsetof is called with an argument
diff --git a/src/go/types/errors.go b/src/go/types/errors.go
index 226310641733ae833e91e63064ec6a8db71ea469..933de93d8585b05d32c8e217e183876e6d5f0dfa 100644
--- a/src/go/types/errors.go
+++ b/src/go/types/errors.go
@@ -63,22 +63,28 @@ func (check *Checker) markImports(pkg *Package) {
 }
 
 func (check *Checker) sprintf(format string, args ...interface{}) string {
+	return sprintf(check.fset, check.qualifier, format, args...)
+}
+
+func sprintf(fset *token.FileSet, qf Qualifier, format string, args ...interface{}) string {
 	for i, arg := range args {
 		switch a := arg.(type) {
 		case nil:
 			arg = ""
 		case operand:
-			panic("internal error: should always pass *operand")
+			panic("got operand instead of *operand")
 		case *operand:
-			arg = operandString(a, check.qualifier)
+			arg = operandString(a, qf)
 		case token.Pos:
-			arg = check.fset.Position(a).String()
+			if fset != nil {
+				arg = fset.Position(a).String()
+			}
 		case ast.Expr:
 			arg = ExprString(a)
 		case Object:
-			arg = ObjectString(a, check.qualifier)
+			arg = ObjectString(a, qf)
 		case Type:
-			arg = TypeString(a, check.qualifier)
+			arg = TypeString(a, qf)
 		}
 		args[i] = arg
 	}
@@ -236,7 +242,7 @@ func (s atPos) Pos() token.Pos {
 func spanOf(at positioner) posSpan {
 	switch x := at.(type) {
 	case nil:
-		panic("internal error: nil")
+		panic("nil positioner")
 	case posSpan:
 		return x
 	case ast.Node:
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 58962e777bc9541ec549a0c0de0035187f0331ac..b0e2a27085f8237e0b351fee7a65c30228126701 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -144,6 +144,14 @@ var op2str2 = [...]string{
 	token.SHL: "shift",
 }
 
+func underIs(typ Type, f func(Type) bool) bool {
+	u := under(typ)
+	if tpar, _ := u.(*TypeParam); tpar != nil {
+		return tpar.underIs(f)
+	}
+	return f(u)
+}
+
 // The unary expression e may be nil. It's passed in for better error messages only.
 func (check *Checker) unary(x *operand, e *ast.UnaryExpr) {
 	check.expr(x, e.X)
@@ -164,19 +172,29 @@ func (check *Checker) unary(x *operand, e *ast.UnaryExpr) {
 		return
 
 	case token.ARROW:
-		typ := asChan(x.typ)
-		if typ == nil {
-			check.invalidOp(x, _InvalidReceive, "cannot receive from non-channel %s", x)
-			x.mode = invalid
-			return
-		}
-		if typ.dir == SendOnly {
-			check.invalidOp(x, _InvalidReceive, "cannot receive from send-only channel %s", x)
+		var elem Type
+		if !underIs(x.typ, func(u Type) bool {
+			ch, _ := u.(*Chan)
+			if ch == nil {
+				check.invalidOp(x, _InvalidReceive, "cannot receive from non-channel %s", x)
+				return false
+			}
+			if ch.dir == SendOnly {
+				check.invalidOp(x, _InvalidReceive, "cannot receive from send-only channel %s", x)
+				return false
+			}
+			if elem != nil && !Identical(ch.elem, elem) {
+				check.invalidOp(x, _Todo, "channels of %s must have the same element type", x)
+				return false
+			}
+			elem = ch.elem
+			return true
+		}) {
 			x.mode = invalid
 			return
 		}
 		x.mode = commaok
-		x.typ = typ.elem
+		x.typ = elem
 		check.hasCallOrRecv = true
 		return
 	}
@@ -582,7 +600,7 @@ func (check *Checker) updateExprVal(x ast.Expr, val constant.Value) {
 func (check *Checker) convertUntyped(x *operand, target Type) {
 	newType, val, code := check.implicitTypeAndValue(x, target)
 	if code != 0 {
-		check.invalidConversion(code, x, target.Underlying())
+		check.invalidConversion(code, x, safeUnderlying(target))
 		x.mode = invalid
 		return
 	}
@@ -603,7 +621,6 @@ func (check *Checker) convertUntyped(x *operand, target Type) {
 // If x is a constant operand, the returned constant.Value will be the
 // representation of x in this context.
 func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, constant.Value, errorCode) {
-	target = expand(target)
 	if x.mode == invalid || isTyped(x.typ) || target == Typ[Invalid] {
 		return x.typ, nil, 0
 	}
@@ -622,7 +639,7 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 		return x.typ, nil, 0
 	}
 
-	switch t := optype(target).(type) {
+	switch t := under(target).(type) {
 	case *Basic:
 		if x.mode == constant_ {
 			v, code := check.representation(x, t)
@@ -661,8 +678,8 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 		default:
 			return nil, nil, _InvalidUntypedConversion
 		}
-	case *_Sum:
-		ok := t.is(func(t Type) bool {
+	case *TypeParam:
+		ok := t.underIs(func(t Type) bool {
 			target, _, _ := check.implicitTypeAndValue(x, t)
 			return target != nil
 		})
@@ -682,7 +699,6 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 			return Typ[UntypedNil], nil, 0
 		}
 		// cannot assign untyped values to non-empty interfaces
-		check.completeInterface(token.NoPos, t)
 		if !t.Empty() {
 			return nil, nil, _InvalidUntypedConversion
 		}
@@ -943,14 +959,28 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
 		return
 	}
 
-	check.convertUntyped(x, y.typ)
-	if x.mode == invalid {
-		return
+	canMix := func(x, y *operand) bool {
+		if IsInterface(x.typ) || IsInterface(y.typ) {
+			return true
+		}
+		if isBoolean(x.typ) != isBoolean(y.typ) {
+			return false
+		}
+		if isString(x.typ) != isString(y.typ) {
+			return false
+		}
+		return true
 	}
-	check.convertUntyped(&y, x.typ)
-	if y.mode == invalid {
-		x.mode = invalid
-		return
+	if canMix(x, &y) {
+		check.convertUntyped(x, y.typ)
+		if x.mode == invalid {
+			return
+		}
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			x.mode = invalid
+			return
+		}
 	}
 
 	if isComparison(op) {
@@ -958,7 +988,7 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
 		return
 	}
 
-	if !check.identical(x.typ, y.typ) {
+	if !Identical(x.typ, y.typ) {
 		// only report an error if we have valid types
 		// (otherwise we had an error reported elsewhere already)
 		if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
@@ -1154,7 +1184,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 			goto Error
 		}
 
-		switch utyp := optype(base).(type) {
+		switch utyp := under(base).(type) {
 		case *Struct:
 			if len(e.Elts) == 0 {
 				break
@@ -1284,7 +1314,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 					xkey := keyVal(x.val)
 					if asInterface(utyp.key) != nil {
 						for _, vtyp := range visited[xkey] {
-							if check.identical(vtyp, x.typ) {
+							if Identical(vtyp, x.typ) {
 								duplicate = true
 								break
 							}
@@ -1333,9 +1363,10 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 	case *ast.SelectorExpr:
 		check.selector(x, e)
 
-	case *ast.IndexExpr:
-		if check.indexExpr(x, e) {
-			check.funcInst(x, e)
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(e)
+		if check.indexExpr(x, ix) {
+			check.funcInst(x, ix)
 		}
 		if x.mode == invalid {
 			goto Error
@@ -1384,13 +1415,24 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 		case typexpr:
 			x.typ = &Pointer{base: x.typ}
 		default:
-			if typ := asPointer(x.typ); typ != nil {
-				x.mode = variable
-				x.typ = typ.base
-			} else {
-				check.invalidOp(x, _InvalidIndirection, "cannot indirect %s", x)
+			var base Type
+			if !underIs(x.typ, func(u Type) bool {
+				p, _ := u.(*Pointer)
+				if p == nil {
+					check.invalidOp(x, _InvalidIndirection, "cannot indirect %s", x)
+					return false
+				}
+				if base != nil && !Identical(p.base, base) {
+					check.invalidOp(x, _Todo, "pointers of %s must have identical base types", x)
+					return false
+				}
+				base = p.base
+				return true
+			}) {
 				goto Error
 			}
+			x.mode = variable
+			x.typ = base
 		}
 
 	case *ast.UnaryExpr:
@@ -1425,12 +1467,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 		// types, which are comparatively rare.
 
 	default:
-		if typeparams.IsListExpr(e) {
-			// catch-all for unexpected expression lists
-			check.errorf(e, _Todo, "unexpected list of expressions")
-		} else {
-			panic(fmt.Sprintf("%s: unknown expression type %T", check.fset.Position(e.Pos()), e))
-		}
+		panic(fmt.Sprintf("%s: unknown expression type %T", check.fset.Position(e.Pos()), e))
 	}
 
 	// everything went well
@@ -1475,7 +1512,7 @@ func (check *Checker) typeAssertion(at positioner, x *operand, xtyp *Interface,
 	}
 	var msg string
 	if wrongType != nil {
-		if check.identical(method.typ, wrongType.typ) {
+		if Identical(method.typ, wrongType.typ) {
 			msg = fmt.Sprintf("missing method %s (%s has pointer receiver)", method.name, method.name)
 		} else {
 			msg = fmt.Sprintf("wrong type for method %s (have %s, want %s)", method.name, wrongType.typ, method.typ)
diff --git a/src/go/types/exprstring.go b/src/go/types/exprstring.go
index f05e6424d44d88a89e4fecde277b15f34344320b..aee8a5ba5f74d2826d76ddbbf41ade0992cdeebd 100644
--- a/src/go/types/exprstring.go
+++ b/src/go/types/exprstring.go
@@ -67,11 +67,11 @@ func WriteExpr(buf *bytes.Buffer, x ast.Expr) {
 		buf.WriteByte('.')
 		buf.WriteString(x.Sel.Name)
 
-	case *ast.IndexExpr:
-		WriteExpr(buf, x.X)
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(x)
+		WriteExpr(buf, ix.X)
 		buf.WriteByte('[')
-		exprs := typeparams.UnpackExpr(x.Index)
-		for i, e := range exprs {
+		for i, e := range ix.Indices {
 			if i > 0 {
 				buf.WriteString(", ")
 			}
diff --git a/src/go/types/exprstring_test.go b/src/go/types/exprstring_test.go
index 51102881c9f188f7021bda97b44697f0e8b6005f..a67f6a978a9509ce8f251041f0e2e92d82a91876 100644
--- a/src/go/types/exprstring_test.go
+++ b/src/go/types/exprstring_test.go
@@ -27,6 +27,40 @@ var testExprs = []testEntry{
 	{"func(x int) complex128 {}", "(func(x int) complex128 literal)"},
 	{"[]int{1, 2, 3}", "([]int literal)"},
 
+	// type expressions
+	dup("[1 << 10]byte"),
+	dup("[]int"),
+	dup("*int"),
+	dup("struct{x int}"),
+	dup("func()"),
+	dup("func(int, float32) string"),
+	dup("interface{m()}"),
+	dup("interface{m() string; n(x int)}"),
+	dup("interface{type int}"),
+
+	// The following exprs do not get formatted correctly: each element in the
+	// type list is printed on a separate line. This is left as a placeholder
+	// until type lists are removed.
+	// TODO(rfindley): remove this once type lists are gone.
+	// dup("interface{type int, float64, string}"),
+	// dup("interface{type int; m()}"),
+	// dup("interface{type int, float64, string; m() string; n(x int)}"),
+	dup("map[string]int"),
+	dup("chan E"),
+	dup("<-chan E"),
+	dup("chan<- E"),
+
+	// new interfaces
+	dup("interface{int}"),
+	dup("interface{~int}"),
+	dup("interface{~int}"),
+	dup("interface{int | string}"),
+	dup("interface{~int | ~string; float64; m()}"),
+
+	// See above.
+	// dup("interface{type a, b, c; ~int | ~string; float64; m()}"),
+	dup("interface{~T[int, string] | string}"),
+
 	// non-type expressions
 	dup("(x)"),
 	dup("x.f"),
diff --git a/src/go/types/index.go b/src/go/types/index.go
index 2ba3475f897107817d16c75730d28319ab3915b5..a49bc5519cf3e9a5f29fdaf45d2595af2d1342ae 100644
--- a/src/go/types/index.go
+++ b/src/go/types/index.go
@@ -15,25 +15,25 @@ import (
 // If e is a valid function instantiation, indexExpr returns true.
 // In that case x represents the uninstantiated function value and
 // it is the caller's responsibility to instantiate the function.
-func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) (isFuncInst bool) {
+func (check *Checker) indexExpr(x *operand, e *typeparams.IndexExpr) (isFuncInst bool) {
 	check.exprOrType(x, e.X)
 
 	switch x.mode {
 	case invalid:
-		check.use(typeparams.UnpackExpr(e.Index)...)
+		check.use(e.Indices...)
 		return false
 
 	case typexpr:
 		// type instantiation
 		x.mode = invalid
-		x.typ = check.varType(e)
+		x.typ = check.varType(e.Orig)
 		if x.typ != Typ[Invalid] {
 			x.mode = typexpr
 		}
 		return false
 
 	case value:
-		if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+		if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 			// function instantiation
 			return true
 		}
@@ -41,7 +41,7 @@ func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) (isFuncInst bool)
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			valid = true
@@ -80,7 +80,7 @@ func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) (isFuncInst bool)
 		index := check.singleIndex(e)
 		if index == nil {
 			x.mode = invalid
-			return
+			return false
 		}
 		var key operand
 		check.expr(&key, index)
@@ -88,88 +88,81 @@ func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) (isFuncInst bool)
 		// ok to continue even if indexing failed - map element type is known
 		x.mode = mapindex
 		x.typ = typ.elem
-		x.expr = e
-		return
+		x.expr = e.Orig
+		return false
 
-	case *_Sum:
-		// A sum type can be indexed if all of the sum's types
-		// support indexing and have the same index and element
-		// type. Special rules apply for maps in the sum type.
-		var tkey, telem Type // key is for map types only
-		nmaps := 0           // number of map types in sum type
-		if typ.is(func(t Type) bool {
-			var e Type
-			switch t := under(t).(type) {
+	case *TypeParam:
+		// TODO(gri) report detailed failure cause for better error messages
+		var tkey, telem Type // tkey != nil if we have maps
+		if typ.underIs(func(u Type) bool {
+			var key, elem Type
+			alen := int64(-1) // valid if >= 0
+			switch t := u.(type) {
 			case *Basic:
-				if isString(t) {
-					e = universeByte
+				if !isString(t) {
+					return false
 				}
+				elem = universeByte
 			case *Array:
-				e = t.elem
+				elem = t.elem
+				alen = t.len
 			case *Pointer:
-				if t := asArray(t.base); t != nil {
-					e = t.elem
+				a, _ := under(t.base).(*Array)
+				if a == nil {
+					return false
 				}
+				elem = a.elem
+				alen = a.len
 			case *Slice:
-				e = t.elem
+				elem = t.elem
 			case *Map:
-				// If there are multiple maps in the sum type,
-				// they must have identical key types.
-				// TODO(gri) We may be able to relax this rule
-				// but it becomes complicated very quickly.
-				if tkey != nil && !Identical(t.key, tkey) {
+				key = t.key
+				elem = t.elem
+			default:
+				return false
+			}
+			assert(elem != nil)
+			if telem == nil {
+				// first type
+				tkey, telem = key, elem
+				length = alen
+			} else {
+				// all map keys must be identical (incl. all nil)
+				if !Identical(key, tkey) {
 					return false
 				}
-				tkey = t.key
-				e = t.elem
-				nmaps++
-			case *_TypeParam:
-				check.errorf(x, 0, "type of %s contains a type parameter - cannot index (implementation restriction)", x)
-			case *instance:
-				panic("unimplemented")
-			}
-			if e == nil || telem != nil && !Identical(e, telem) {
-				return false
+				// all element types must be identical
+				if !Identical(elem, telem) {
+					return false
+				}
+				tkey, telem = key, elem
+				// track the minimal length for arrays
+				if alen >= 0 && alen < length {
+					length = alen
+				}
 			}
-			telem = e
 			return true
 		}) {
-			// If there are maps, the index expression must be assignable
-			// to the map key type (as for simple map index expressions).
-			if nmaps > 0 {
+			// For maps, the index expression must be assignable to the map key type.
+			if tkey != nil {
 				index := check.singleIndex(e)
 				if index == nil {
 					x.mode = invalid
-					return
+					return false
 				}
 				var key operand
 				check.expr(&key, index)
 				check.assignment(&key, tkey, "map index")
 				// ok to continue even if indexing failed - map element type is known
-
-				// If there are only maps, we are done.
-				if nmaps == len(typ.types) {
-					x.mode = mapindex
-					x.typ = telem
-					x.expr = e
-					return
-				}
-
-				// Otherwise we have mix of maps and other types. For
-				// now we require that the map key be an integer type.
-				// TODO(gri) This is probably not good enough.
-				valid = isInteger(tkey)
-				// avoid 2nd indexing error if indexing failed above
-				if !valid && key.mode == invalid {
-					x.mode = invalid
-					return
-				}
-				x.mode = value // map index expressions are not addressable
-			} else {
-				// no maps
-				valid = true
-				x.mode = variable
+				x.mode = mapindex
+				x.typ = telem
+				x.expr = e
+				return false
 			}
+
+			// no maps
+			valid = true
+			x.mode = variable
 			x.typ = telem
 		}
 	}
@@ -177,13 +170,13 @@ func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) (isFuncInst bool)
 	if !valid {
 		check.invalidOp(x, _NonIndexableOperand, "cannot index %s", x)
 		x.mode = invalid
-		return
+		return false
 	}
 
 	index := check.singleIndex(e)
 	if index == nil {
 		x.mode = invalid
-		return
+		return false
 	}
 
 	// In pathological (invalid) cases (e.g.: type T1 [][[]T1{}[0][0]]T0)
@@ -206,7 +199,7 @@ func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			if e.Slice3 {
@@ -246,8 +239,8 @@ func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
 		valid = true
 		// x.typ doesn't change
 
-	case *_Sum, *_TypeParam:
-		check.errorf(x, 0, "generic slice expressions not yet implemented")
+	case *TypeParam:
+		check.errorf(x, _Todo, "generic slice expressions not yet implemented")
 		x.mode = invalid
 		return
 	}
@@ -311,23 +304,16 @@ L:
 // singleIndex returns the (single) index from the index expression e.
 // If the index is missing, or if there are multiple indices, an error
 // is reported and the result is nil.
-func (check *Checker) singleIndex(e *ast.IndexExpr) ast.Expr {
-	index := e.Index
-	if index == nil {
-		check.invalidAST(e, "missing index for %s", e)
-		return nil
-	}
-
-	indexes := typeparams.UnpackExpr(index)
-	if len(indexes) == 0 {
-		check.invalidAST(index, "index expression %v with 0 indices", index)
+func (check *Checker) singleIndex(expr *typeparams.IndexExpr) ast.Expr {
+	if len(expr.Indices) == 0 {
+		check.invalidAST(expr.Orig, "index expression %v with 0 indices", expr)
 		return nil
 	}
-	if len(indexes) > 1 {
+	if len(expr.Indices) > 1 {
 		// TODO(rFindley) should this get a distinct error code?
-		check.invalidOp(indexes[1], _InvalidIndex, "more than one index")
+		check.invalidOp(expr.Indices[1], _InvalidIndex, "more than one index")
 	}
-	return indexes[0]
+	return expr.Indices[0]
 }
 
 // index checks an index expression for validity.
diff --git a/src/go/types/infer.go b/src/go/types/infer.go
index 5d49351e1f043475332fad124e73efc5b4e2f6a5..e6417545e9d7737b6699dead4ade6bbd93f8dad0 100644
--- a/src/go/types/infer.go
+++ b/src/go/types/infer.go
@@ -27,7 +27,7 @@ import (
 //
 // Constraint type inference is used after each step to expand the set of type arguments.
 //
-func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
+func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
 	if debug {
 		defer func() {
 			assert(result == nil || len(result) == len(tparams))
@@ -82,18 +82,18 @@ func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type,
 
 	// Substitute type arguments for their respective type parameters in params,
 	// if any. Note that nil targs entries are ignored by check.subst.
-	// TODO(gri) Can we avoid this (we're setting known type argumemts below,
+	// TODO(gri) Can we avoid this (we're setting known type arguments below,
 	//           but that doesn't impact the isParameterized check for now).
 	if params.Len() > 0 {
 		smap := makeSubstMap(tparams, targs)
-		params = check.subst(token.NoPos, params, smap).(*Tuple)
+		params = check.subst(token.NoPos, params, smap, nil).(*Tuple)
 	}
 
 	// --- 2 ---
 	// Unify parameter and argument types for generic parameters with typed arguments
 	// and collect the indices of generic parameters with untyped arguments.
 	// Terminology: generic parameter = function parameter with a type-parameterized type
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 
 	// Set the type arguments which we know already.
@@ -121,13 +121,13 @@ func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type,
 				}
 			}
 			if allFailed {
-				check.errorf(arg, _Todo, "%s %s of %s does not match %s (cannot infer %s)", kind, targ, arg.expr, tpar, typeNamesString(tparams))
+				check.errorf(arg, _Todo, "%s %s of %s does not match %s (cannot infer %s)", kind, targ, arg.expr, tpar, typeParamsString(tparams))
 				return
 			}
 		}
 		smap := makeSubstMap(tparams, targs)
 		// TODO(rFindley): pass a positioner here, rather than arg.Pos().
-		inferred := check.subst(arg.Pos(), tpar, smap)
+		inferred := check.subst(arg.Pos(), tpar, smap, nil)
 		if inferred != tpar {
 			check.errorf(arg, _Todo, "%s %s of %s does not match inferred type %s for %s", kind, targ, arg.expr, inferred, tpar)
 		} else {
@@ -189,7 +189,7 @@ func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type,
 		// only parameter type it can possibly match against is a *TypeParam.
 		// Thus, only consider untyped arguments for generic parameters that
 		// are not of composite types and which don't have a type inferred yet.
-		if tpar, _ := par.typ.(*_TypeParam); tpar != nil && targs[tpar.index] == nil {
+		if tpar, _ := par.typ.(*TypeParam); tpar != nil && targs[tpar.index] == nil {
 			arg := args[i]
 			targ := Default(arg.typ)
 			// The default type for an untyped nil is untyped nil. We must not
@@ -218,23 +218,23 @@ func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type,
 	assert(index >= 0 && targs[index] == nil)
 	tpar := tparams[index]
 	if report {
-		check.errorf(posn, _Todo, "cannot infer %s (%v) (%v)", tpar.name, tpar.pos, targs)
+		check.errorf(posn, _Todo, "cannot infer %s (%v) (%v)", tpar.obj.name, tpar.obj.pos, targs)
 	}
 	return nil
 }
 
-// typeNamesString produces a string containing all the
-// type names in list suitable for human consumption.
-func typeNamesString(list []*TypeName) string {
+// typeParamsString produces a string containing all the type parameter names
+// in list suitable for human consumption.
+func typeParamsString(list []*TypeParam) string {
 	// common cases
 	n := len(list)
 	switch n {
 	case 0:
 		return ""
 	case 1:
-		return list[0].name
+		return list[0].obj.name
 	case 2:
-		return list[0].name + " and " + list[1].name
+		return list[0].obj.name + " and " + list[1].obj.name
 	}
 
 	// general case (n > 2)
@@ -243,15 +243,15 @@ func typeNamesString(list []*TypeName) string {
 		if i > 0 {
 			b.WriteString(", ")
 		}
-		b.WriteString(tname.name)
+		b.WriteString(tname.obj.name)
 	}
 	b.WriteString(", and ")
-	b.WriteString(list[n-1].name)
+	b.WriteString(list[n-1].obj.name)
 	return b.String()
 }
 
 // IsParameterized reports whether typ contains any of the type parameters of tparams.
-func isParameterized(tparams []*TypeName, typ Type) bool {
+func isParameterized(tparams []*TypeParam, typ Type) bool {
 	w := tpWalker{
 		seen:    make(map[Type]bool),
 		tparams: tparams,
@@ -261,7 +261,7 @@ func isParameterized(tparams []*TypeName, typ Type) bool {
 
 type tpWalker struct {
 	seen    map[Type]bool
-	tparams []*TypeName
+	tparams []*TypeParam
 }
 
 func (w *tpWalker) isParameterized(typ Type) (res bool) {
@@ -275,7 +275,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 	}()
 
 	switch t := typ.(type) {
-	case nil, *Basic: // TODO(gri) should nil be handled here?
+	case nil, *top, *Basic: // TODO(gri) should nil be handled here?
 		break
 
 	case *Array:
@@ -302,9 +302,6 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 			}
 		}
 
-	case *_Sum:
-		return w.isParameterizedList(t.types)
-
 	case *Signature:
 		// t.tparams may not be nil if we are looking at a signature
 		// of a generic function type (or an interface method) that is
@@ -316,24 +313,15 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 		return w.isParameterized(t.params) || w.isParameterized(t.results)
 
 	case *Interface:
-		if t.allMethods != nil {
-			// TODO(rFindley) at some point we should enforce completeness here
-			for _, m := range t.allMethods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
+		tset := t.typeSet()
+		for _, m := range tset.methods {
+			if w.isParameterized(m.typ) {
+				return true
 			}
-			return w.isParameterizedList(unpackType(t.allTypes))
 		}
-
-		return t.iterate(func(t *Interface) bool {
-			for _, m := range t.methods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
-			}
-			return w.isParameterizedList(unpackType(t.types))
-		}, nil)
+		return tset.is(func(t *term) bool {
+			return w.isParameterized(t.typ)
+		})
 
 	case *Map:
 		return w.isParameterized(t.key) || w.isParameterized(t.elem)
@@ -342,14 +330,11 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 		return w.isParameterized(t.elem)
 
 	case *Named:
-		return w.isParameterizedList(t.targs)
+		return w.isParameterizedTypeList(t.targs.list())
 
-	case *_TypeParam:
+	case *TypeParam:
 		// t must be one of w.tparams
-		return t.index < len(w.tparams) && w.tparams[t.index].typ == t
-
-	case *instance:
-		return w.isParameterizedList(t.targs)
+		return t.index < len(w.tparams) && w.tparams[t.index] == t
 
 	default:
 		unreachable()
@@ -358,7 +343,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
 	return false
 }
 
-func (w *tpWalker) isParameterizedList(list []Type) bool {
+func (w *tpWalker) isParameterizedTypeList(list []Type) bool {
 	for _, t := range list {
 		if w.isParameterized(t) {
 			return true
@@ -375,12 +360,12 @@ func (w *tpWalker) isParameterizedList(list []Type) bool {
 // first type argument in that list that couldn't be inferred (and thus is nil). If all
 // type arguments were inferred successfully, index is < 0. The number of type arguments
 // provided may be less than the number of type parameters, but there must be at least one.
-func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (types []Type, index int) {
+func (check *Checker) inferB(tparams []*TypeParam, targs []Type, report bool) (types []Type, index int) {
 	assert(len(tparams) >= len(targs) && len(targs) > 0)
 
 	// Setup bidirectional unification between those structural bounds
 	// and the corresponding type arguments (which may be nil!).
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 	u.y = u.x // type parameters between LHS and RHS of unification are identical
 
@@ -393,12 +378,12 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 
 	// Unify type parameters with their structural constraints, if any.
 	for _, tpar := range tparams {
-		typ := tpar.typ.(*_TypeParam)
-		sbound := check.structuralType(typ.bound)
+		typ := tpar
+		sbound := typ.structuralType()
 		if sbound != nil {
 			if !u.unify(typ, sbound) {
 				if report {
-					check.errorf(tpar, _Todo, "%s does not match %s", tpar, sbound)
+					check.errorf(tpar.obj, _Todo, "%s does not match %s", tpar.obj, sbound)
 				}
 				return nil, 0
 			}
@@ -407,8 +392,8 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
 	// arguments for which there were structural constraints. The newly inferred non-
-	// nil entries may still contain references to other type parameters. For instance,
-	// for [A any, B interface{type []C}, C interface{type *A}], if A == int
+	// nil entries may still contain references to other type parameters.
+	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
 	// until nothing changes anymore.
@@ -437,7 +422,7 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 		n := 0
 		for _, index := range dirty {
 			t0 := types[index]
-			if t1 := check.subst(token.NoPos, t0, smap); t1 != t0 {
+			if t1 := check.subst(token.NoPos, t0, smap, nil); t1 != t0 {
 				types[index] = t1
 				dirty[n] = index
 				n++
@@ -467,16 +452,3 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
 
 	return
 }
-
-// structuralType returns the structural type of a constraint, if any.
-func (check *Checker) structuralType(constraint Type) Type {
-	if iface, _ := under(constraint).(*Interface); iface != nil {
-		check.completeInterface(token.NoPos, iface)
-		types := unpackType(iface.allTypes)
-		if len(types) == 1 {
-			return types[0]
-		}
-		return nil
-	}
-	return constraint
-}
diff --git a/src/go/types/instantiate.go b/src/go/types/instantiate.go
new file mode 100644
index 0000000000000000000000000000000000000000..3ee09b7e8425ea2508162bea7038ac7ffacc5f25
--- /dev/null
+++ b/src/go/types/instantiate.go
@@ -0,0 +1,288 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements instantiation of generic types
+// through substitution of type parameters by type arguments.
+
+package types
+
+import (
+	"errors"
+	"fmt"
+	"go/token"
+)
+
+// An Environment is an opaque type checking environment. It may be used to
+// share identical type instances across type checked packages or calls to
+// Instantiate.
+//
+// Currently, Environment is just a placeholder and has no effect on
+// instantiation.
+type Environment struct {
+	// Environment is currently un-implemented, because our instantiatedHash
+	// logic doesn't correctly handle Named type identity across multiple
+	// packages.
+	// TODO(rfindley): implement this.
+}
+
+// Instantiate instantiates the type typ with the given type arguments targs.
+// typ must be a *Named or a *Signature type, and its number of type parameters
+// must match the number of provided type arguments. The result is a new,
+// instantiated (not parameterized) type of the same kind (either a *Named or a
+// *Signature). Any methods attached to a *Named are simply copied; they are
+// not instantiated.
+//
+// If env is non-nil, it may be used to de-dupe the instance against previous
+// instances with the same identity. This functionality is currently
+// unimplemented.
+//
+// If verify is set and constraint satisfaction fails, the returned error may
+// be of dynamic type ArgumentError indicating which type argument did not
+// satisfy its corresponding type parameter constraint, and why.
+//
+// TODO(rfindley): change this function to also return an error if lengths of
+// tparams and targs do not match.
+func Instantiate(env *Environment, typ Type, targs []Type, validate bool) (Type, error) {
+	inst := (*Checker)(nil).instance(token.NoPos, typ, targs)
+
+	var err error
+	if validate {
+		var tparams []*TypeParam
+		switch t := typ.(type) {
+		case *Named:
+			tparams = t.TParams().list()
+		case *Signature:
+			tparams = t.TParams().list()
+		}
+		if i, err := (*Checker)(nil).verify(token.NoPos, tparams, targs); err != nil {
+			return inst, ArgumentError{i, err}
+		}
+	}
+
+	return inst, err
+}
+
+// instantiate creates an instance and defers verification of constraints to
+// later in the type checking pass. For Named types the resulting instance will
+// be unexpanded.
+func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, posList []token.Pos) (res Type) {
+	assert(check != nil)
+	if trace {
+		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
+		check.indent++
+		defer func() {
+			check.indent--
+			var under Type
+			if res != nil {
+				// Calling under() here may lead to endless instantiations.
+				// Test case: type T[P any] T[P]
+				// TODO(gri) investigate if that's a bug or to be expected.
+				under = safeUnderlying(res)
+			}
+			check.trace(pos, "=> %s (under = %s)", res, under)
+		}()
+	}
+
+	inst := check.instance(pos, typ, targs)
+
+	assert(len(posList) <= len(targs))
+	check.later(func() {
+		// Collect tparams again because lazily loaded *Named types may not have
+		// had tparams set up above.
+		var tparams []*TypeParam
+		switch t := typ.(type) {
+		case *Named:
+			tparams = t.TParams().list()
+		case *Signature:
+			tparams = t.TParams().list()
+		}
+		// Avoid duplicate errors; instantiate will have complained if tparams
+		// and targs do not have the same length.
+		if len(tparams) == len(targs) {
+			if i, err := check.verify(pos, tparams, targs); err != nil {
+				// best position for error reporting
+				pos := pos
+				if i < len(posList) {
+					pos = posList[i]
+				}
+				check.softErrorf(atPos(pos), _Todo, err.Error())
+			}
+		}
+	})
+	return inst
+}
+
+// instance creates a type or function instance using the given original type
+// typ and arguments targs. For Named types the resulting instance will be
+// unexpanded.
+func (check *Checker) instance(pos token.Pos, typ Type, targs []Type) (res Type) {
+	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
+	switch t := typ.(type) {
+	case *Named:
+		h := instantiatedHash(t, targs)
+		if check != nil {
+			// typ may already have been instantiated with identical type arguments. In
+			// that case, re-use the existing instance.
+			if named := check.typMap[h]; named != nil {
+				return named
+			}
+		}
+
+		tname := NewTypeName(pos, t.obj.pkg, t.obj.name, nil)
+		named := check.newNamed(tname, t, nil, nil, nil) // methods and tparams are set when named is loaded
+		named.targs = &TypeList{targs}
+		named.instance = &instance{pos}
+		if check != nil {
+			check.typMap[h] = named
+		}
+		res = named
+	case *Signature:
+		tparams := t.TParams()
+		if !check.validateTArgLen(pos, tparams.Len(), len(targs)) {
+			return Typ[Invalid]
+		}
+		if tparams.Len() == 0 {
+			return typ // nothing to do (minor optimization)
+		}
+		defer func() {
+			// If we had an unexpected failure somewhere don't panic below when
+			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
+			// is returned.
+			if _, ok := res.(*Signature); !ok {
+				return
+			}
+			// If the signature doesn't use its type parameters, subst
+			// will not make a copy. In that case, make a copy now (so
+			// we can set tparams to nil w/o causing side-effects).
+			if t == res {
+				copy := *t
+				res = ©
+			}
+			// After instantiating a generic signature, it is not generic
+			// anymore; we need to set tparams to nil.
+			res.(*Signature).tparams = nil
+		}()
+		res = check.subst(pos, typ, makeSubstMap(tparams.list(), targs), nil)
+	default:
+		// only types and functions can be generic
+		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
+	}
+	return res
+}
+
+// validateTArgLen verifies that the length of targs and tparams matches,
+// reporting an error if not. If validation fails and check is nil,
+// validateTArgLen panics.
+func (check *Checker) validateTArgLen(pos token.Pos, ntparams, ntargs int) bool {
+	if ntargs != ntparams {
+		// TODO(gri) provide better error message
+		if check != nil {
+			check.errorf(atPos(pos), _Todo, "got %d arguments but %d type parameters", ntargs, ntparams)
+			return false
+		}
+		panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, ntargs, ntparams))
+	}
+	return true
+}
+
+func (check *Checker) verify(pos token.Pos, tparams []*TypeParam, targs []Type) (int, error) {
+	smap := makeSubstMap(tparams, targs)
+	for i, tpar := range tparams {
+		// stop checking bounds after the first failure
+		if err := check.satisfies(pos, targs[i], tpar, smap); err != nil {
+			return i, err
+		}
+	}
+	return -1, nil
+}
+
+// satisfies reports whether the type argument targ satisfies the constraint of type parameter
+// parameter tpar (after any of its type parameters have been substituted through smap).
+// A suitable error is reported if the result is false.
+// TODO(gri) This should be a method of interfaces or type sets.
+func (check *Checker) satisfies(pos token.Pos, targ Type, tpar *TypeParam, smap substMap) error {
+	iface := tpar.iface()
+	if iface.Empty() {
+		return nil // no type bound
+	}
+
+	// TODO(rfindley): it would be great if users could pass in a qualifier here,
+	// rather than falling back to verbose qualification. Maybe this can be part
+	// of a the shared environment.
+	var qf Qualifier
+	if check != nil {
+		qf = check.qualifier
+	}
+	errorf := func(format string, args ...interface{}) error {
+		return errors.New(sprintf(nil, qf, format, args...))
+	}
+
+	// The type parameter bound is parameterized with the same type parameters
+	// as the instantiated type; before we can use it for bounds checking we
+	// need to instantiate it with the type arguments with which we instantiate
+	// the parameterized type.
+	iface = check.subst(pos, iface, smap, nil).(*Interface)
+
+	// if iface is comparable, targ must be comparable
+	// TODO(gri) the error messages needs to be better, here
+	if iface.IsComparable() && !Comparable(targ) {
+		if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsAll() {
+			return errorf("%s has no constraints", targ)
+		}
+		return errorf("%s does not satisfy comparable", targ)
+	}
+
+	// targ must implement iface (methods)
+	// - check only if we have methods
+	if iface.NumMethods() > 0 {
+		// If the type argument is a pointer to a type parameter, the type argument's
+		// method set is empty.
+		// TODO(gri) is this what we want? (spec question)
+		if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
+			return errorf("%s has no methods", targ)
+		}
+		if m, wrong := check.missingMethod(targ, iface, true); m != nil {
+			// TODO(gri) needs to print updated name to avoid major confusion in error message!
+			//           (print warning for now)
+			// Old warning:
+			// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
+			if wrong != nil {
+				// TODO(gri) This can still report uninstantiated types which makes the error message
+				//           more difficult to read then necessary.
+				// TODO(rFindley) should this use parentheses rather than ':' for qualification?
+				return errorf("%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
+					targ, tpar.bound, wrong, m,
+				)
+			}
+			return errorf("%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
+		}
+	}
+
+	// targ's underlying type must also be one of the interface types listed, if any
+	if !iface.typeSet().hasTerms() {
+		return nil // nothing to do
+	}
+
+	// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
+	// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
+	if targ := asTypeParam(targ); targ != nil {
+		targBound := targ.iface()
+		if !targBound.typeSet().hasTerms() {
+			return errorf("%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
+		}
+		if !targBound.typeSet().subsetOf(iface.typeSet()) {
+			// TODO(gri) need better error message
+			return errorf("%s does not satisfy %s", targ, tpar.bound)
+		}
+		return nil
+	}
+
+	// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
+	if !iface.typeSet().includes(targ) {
+		// TODO(gri) better error message
+		return errorf("%s does not satisfy %s", targ, tpar.bound)
+	}
+
+	return nil
+}
diff --git a/src/go/types/interface.go b/src/go/types/interface.go
new file mode 100644
index 0000000000000000000000000000000000000000..d27f8cfd4d69da42235719203fa62496fc2a706e
--- /dev/null
+++ b/src/go/types/interface.go
@@ -0,0 +1,249 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/ast"
+	"go/internal/typeparams"
+	"go/token"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// An Interface represents an interface type.
+type Interface struct {
+	obj       *TypeName    // type name object defining this interface; or nil (for better error messages)
+	methods   []*Func      // ordered list of explicitly declared methods
+	embeddeds []Type       // ordered list of explicitly embedded elements
+	embedPos  *[]token.Pos // positions of embedded elements; or nil (for error messages) - use pointer to save space
+	complete  bool         // indicates that obj, methods, and embeddeds are set and type set can be computed
+
+	tset *_TypeSet // type set described by this interface, computed lazily
+}
+
+// typeSet returns the type set for interface t.
+func (t *Interface) typeSet() *_TypeSet { return computeInterfaceTypeSet(nil, token.NoPos, t) }
+
+// emptyInterface represents the empty (completed) interface
+var emptyInterface = Interface{complete: true, tset: &topTypeSet}
+
+// NewInterface returns a new interface for the given methods and embedded types.
+// NewInterface takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+//
+// Deprecated: Use NewInterfaceType instead which allows arbitrary embedded types.
+func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
+	tnames := make([]Type, len(embeddeds))
+	for i, t := range embeddeds {
+		tnames[i] = t
+	}
+	return NewInterfaceType(methods, tnames)
+}
+
+// NewInterfaceType returns a new interface for the given methods and embedded
+// types. NewInterfaceType takes ownership of the provided methods and may
+// modify their types by setting missing receivers.
+//
+// To avoid race conditions, the interface's type set should be computed before
+// concurrent use of the interface, by explicitly calling Complete.
+func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
+	if len(methods) == 0 && len(embeddeds) == 0 {
+		return &emptyInterface
+	}
+
+	// set method receivers if necessary
+	typ := new(Interface)
+	for _, m := range methods {
+		if sig := m.typ.(*Signature); sig.recv == nil {
+			sig.recv = NewVar(m.pos, m.pkg, "", typ)
+		}
+	}
+
+	// sort for API stability
+	sortMethods(methods)
+
+	typ.methods = methods
+	typ.embeddeds = embeddeds
+	typ.complete = true
+
+	return typ
+}
+
+// NumExplicitMethods returns the number of explicitly declared methods of interface t.
+func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
+
+// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
+
+// NumEmbeddeds returns the number of embedded types in interface t.
+func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
+
+// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
+// The result is nil if the i'th embedded type is not a defined type.
+//
+// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
+func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
+
+// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
+func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
+
+// NumMethods returns the total number of methods of interface t.
+func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
+
+// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
+
+// Empty reports whether t is the empty interface.
+func (t *Interface) Empty() bool { return t.typeSet().IsAll() }
+
+// IsComparable reports whether each type in interface t's type set is comparable.
+func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
+
+// IsConstraint reports whether interface t is not just a method set.
+func (t *Interface) IsConstraint() bool { return !t.typeSet().IsMethodSet() }
+
+// Complete computes the interface's type set. It must be called by users of
+// NewInterfaceType and NewInterface after the interface's embedded types are
+// fully defined and before using the interface type in any way other than to
+// form other types. The interface must not contain duplicate methods or a
+// panic occurs. Complete returns the receiver.
+//
+// Interface types that have been completed are safe for concurrent use.
+func (t *Interface) Complete() *Interface {
+	if !t.complete {
+		t.complete = true
+	}
+	t.typeSet() // checks if t.tset is already set
+	return t
+}
+
+func (t *Interface) Underlying() Type { return t }
+func (t *Interface) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
+	var tlist []ast.Expr
+	var tname *ast.Ident // "type" name of first entry in a type list declaration
+
+	addEmbedded := func(pos token.Pos, typ Type) {
+		ityp.embeddeds = append(ityp.embeddeds, typ)
+		if ityp.embedPos == nil {
+			ityp.embedPos = new([]token.Pos)
+		}
+		*ityp.embedPos = append(*ityp.embedPos, pos)
+	}
+
+	for _, f := range iface.Methods.List {
+		if len(f.Names) == 0 {
+			// We have an embedded type; possibly a union of types.
+			addEmbedded(f.Type.Pos(), parseUnion(check, flattenUnion(nil, f.Type)))
+			continue
+		}
+
+		// We have a method with name f.Names[0], or a type
+		// of a type list (name.Name == "type").
+		// (The parser ensures that there's only one method
+		// and we don't care if a constructed AST has more.)
+		name := f.Names[0]
+		if name.Name == "_" {
+			check.errorf(name, _BlankIfaceMethod, "invalid method name _")
+			continue // ignore
+		}
+
+		// TODO(rfindley) Remove type list handling once the parser doesn't accept type lists anymore.
+		if name.Name == "type" {
+			// Report an error for the first type list per interface
+			// if we don't allow type lists, but continue.
+			if !allowTypeLists && tlist == nil {
+				check.softErrorf(name, _Todo, "use generalized embedding syntax instead of a type list")
+			}
+			// For now, collect all type list entries as if it
+			// were a single union, where each union element is
+			// of the form ~T.
+			// TODO(rfindley) remove once we disallow type lists
+			op := new(ast.UnaryExpr)
+			op.Op = token.TILDE
+			op.X = f.Type
+			tlist = append(tlist, op)
+			// Report an error if we have multiple type lists in an
+			// interface, but only if they are permitted in the first place.
+			if allowTypeLists && tname != nil && tname != name {
+				check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
+			}
+			tname = name
+			continue
+		}
+
+		typ := check.typ(f.Type)
+		sig, _ := typ.(*Signature)
+		if sig == nil {
+			if typ != Typ[Invalid] {
+				check.invalidAST(f.Type, "%s is not a method signature", typ)
+			}
+			continue // ignore
+		}
+
+		// Always type-check method type parameters but complain if they are not enabled.
+		// (This extra check is needed here because interface method signatures don't have
+		// a receiver specification.)
+		if sig.tparams != nil {
+			var at positioner = f.Type
+			if tparams := typeparams.Get(f.Type); tparams != nil {
+				at = tparams
+			}
+			check.errorf(at, _Todo, "methods cannot have type parameters")
+		}
+
+		// use named receiver type if available (for better error messages)
+		var recvTyp Type = ityp
+		if def != nil {
+			recvTyp = def
+		}
+		sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
+
+		m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
+		check.recordDef(name, m)
+		ityp.methods = append(ityp.methods, m)
+	}
+
+	// type constraints
+	if tlist != nil {
+		// TODO(rfindley): this differs from types2 due to the use of Pos() below,
+		// which should actually be on the ~. Confirm that this position is correct.
+		addEmbedded(tlist[0].Pos(), parseUnion(check, tlist))
+	}
+
+	// All methods and embedded elements for this interface are collected;
+	// i.e., this interface is may be used in a type set computation.
+	ityp.complete = true
+
+	if len(ityp.methods) == 0 && len(ityp.embeddeds) == 0 {
+		// empty interface
+		ityp.tset = &topTypeSet
+		return
+	}
+
+	// sort for API stability
+	sortMethods(ityp.methods)
+	// (don't sort embeddeds: they must correspond to *embedPos entries)
+
+	// Compute type set with a non-nil *Checker as soon as possible
+	// to report any errors. Subsequent uses of type sets will use
+	// this computed type set and won't need to pass in a *Checker.
+	check.later(func() { computeInterfaceTypeSet(check, iface.Pos(), ityp) })
+}
+
+func flattenUnion(list []ast.Expr, x ast.Expr) []ast.Expr {
+	if o, _ := x.(*ast.BinaryExpr); o != nil && o.Op == token.OR {
+		list = flattenUnion(list, o.X)
+		x = o.Y
+	}
+	return append(list, x)
+}
diff --git a/src/go/types/issues_test.go b/src/go/types/issues_test.go
index 519e19953645d8e8c4f97d0058cd29ebdb9ffdc3..51995af30afd39f7c174abaa1d61dfc9421277bb 100644
--- a/src/go/types/issues_test.go
+++ b/src/go/types/issues_test.go
@@ -634,7 +634,7 @@ var _ T = template /* ERROR cannot use.*text/template.* as T value */.Template{}
 	}
 	imp := importHelper{pkg: a, fallback: importer.Default()}
 
-	checkFiles(t, nil, "", []string{"b.go"}, [][]byte{[]byte(bsrc)}, false, imp)
-	checkFiles(t, nil, "", []string{"c.go"}, [][]byte{[]byte(csrc)}, false, imp)
-	checkFiles(t, nil, "", []string{"t.go"}, [][]byte{[]byte(tsrc)}, false, imp)
+	testFiles(t, nil, []string{"b.go"}, [][]byte{[]byte(bsrc)}, false, imp)
+	testFiles(t, nil, []string{"c.go"}, [][]byte{[]byte(csrc)}, false, imp)
+	testFiles(t, nil, []string{"t.go"}, [][]byte{[]byte(tsrc)}, false, imp)
 }
diff --git a/src/go/types/labels.go b/src/go/types/labels.go
index 8cf6e63645e9f123386bc7cd879a591c76382d13..f3b7f211f37f25d46efec69975f501942e3a9118 100644
--- a/src/go/types/labels.go
+++ b/src/go/types/labels.go
@@ -36,7 +36,8 @@ func (check *Checker) labels(body *ast.BlockStmt) {
 	}
 
 	// spec: "It is illegal to define a label that is never used."
-	for _, obj := range all.elems {
+	for name, obj := range all.elems {
+		obj = resolve(name, obj)
 		if lbl := obj.(*Label); !lbl.used {
 			check.softErrorf(lbl, _UnusedLabel, "label %s declared but not used", lbl.name)
 		}
diff --git a/src/go/types/lookup.go b/src/go/types/lookup.go
index 9c7bfd4bb97da8db276c633874c8dda8186dffda..862e59401d73d9f3b3a531c571c8972e713c9624 100644
--- a/src/go/types/lookup.go
+++ b/src/go/types/lookup.go
@@ -8,6 +8,11 @@ package types
 
 import "go/token"
 
+// Internal use of LookupFieldOrMethod: If the obj result is a method
+// associated with a concrete (non-interface) type, the method's signature
+// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
+// the method's type.
+
 // LookupFieldOrMethod looks up a field or method with given package and name
 // in T and returns the corresponding *Var or *Func, an index sequence, and a
 // bool indicating if there were any pointer indirections on the path to the
@@ -35,19 +40,6 @@ import "go/token"
 //	the method's formal receiver base type, nor was the receiver addressable.
 //
 func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
-	return (*Checker)(nil).lookupFieldOrMethod(T, addressable, pkg, name)
-}
-
-// Internal use of Checker.lookupFieldOrMethod: If the obj result is a method
-// associated with a concrete (non-interface) type, the method's signature
-// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
-// the method's type.
-// TODO(gri) Now that we provide the *Checker, we can probably remove this
-// caveat by calling Checker.objDecl from lookupFieldOrMethod. Investigate.
-
-// lookupFieldOrMethod is like the external version but completes interfaces
-// as necessary.
-func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// Methods cannot be associated to a named pointer type
 	// (spec: "The type denoted by T is called the receiver base type;
 	// it must not be a pointer or interface type and it must be declared
@@ -56,8 +48,8 @@ func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package
 	// pointer type but discard the result if it is a method since we would
 	// not have found it for T (see also issue 8590).
 	if t := asNamed(T); t != nil {
-		if p, _ := t.underlying.(*Pointer); p != nil {
-			obj, index, indirect = check.rawLookupFieldOrMethod(p, false, pkg, name)
+		if p, _ := safeUnderlying(t).(*Pointer); p != nil {
+			obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
 			if _, ok := obj.(*Func); ok {
 				return nil, nil, false
 			}
@@ -65,7 +57,7 @@ func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package
 		}
 	}
 
-	return check.rawLookupFieldOrMethod(T, addressable, pkg, name)
+	return lookupFieldOrMethod(T, addressable, pkg, name)
 }
 
 // TODO(gri) The named type consolidation and seen maps below must be
@@ -73,10 +65,9 @@ func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package
 //           types always have only one representation (even when imported
 //           indirectly via different packages.)
 
-// rawLookupFieldOrMethod should only be called by lookupFieldOrMethod and missingMethod.
-func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+// lookupFieldOrMethod should only be called by LookupFieldOrMethod and missingMethod.
+func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// WARNING: The code in this function is extremely subtle - do not modify casually!
-	//          This function and NewMethodSet should be kept in sync.
 
 	if name == "_" {
 		return // blank fields/methods are never found
@@ -84,10 +75,15 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 
 	typ, isPtr := deref(T)
 
-	// *typ where typ is an interface has no methods.
-	// Be cautious: typ may be nil (issue 39634, crash #3).
-	if typ == nil || isPtr && IsInterface(typ) {
-		return
+	// *typ where typ is an interface or type parameter has no methods.
+	if isPtr {
+		// don't look at under(typ) here - was bug (issue #47747)
+		if _, ok := typ.(*TypeParam); ok {
+			return
+		}
+		if _, ok := under(typ).(*Interface); ok {
+			return
+		}
 	}
 
 	// Start with typ as single entry at shallowest depth.
@@ -107,7 +103,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 		var next []embeddedType // embedded types found at current depth
 
 		// look for (pkg, name) in all types at current depth
-		var tpar *_TypeParam // set if obj receiver is a type parameter
+		var tpar *TypeParam // set if obj receiver is a type parameter
 		for _, e := range current {
 			typ := e.typ
 
@@ -128,6 +124,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 				seen[named] = true
 
 				// look for a matching attached method
+				named.load()
 				if i, m := lookupMethod(named.methods, pkg, name); m != nil {
 					// potential match
 					// caution: method may not have a proper signature yet
@@ -185,9 +182,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 
 			case *Interface:
 				// look for a matching method
-				// TODO(gri) t.allMethods is sorted - use binary search
-				check.completeInterface(token.NoPos, t)
-				if i, m := lookupMethod(t.allMethods, pkg, name); m != nil {
+				if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -197,10 +192,8 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 					indirect = e.indirect
 				}
 
-			case *_TypeParam:
-				// only consider explicit methods in the type parameter bound, not
-				// methods that may be common to all types in the type list.
-				if i, m := lookupMethod(t.Bound().allMethods, pkg, name); m != nil {
+			case *TypeParam:
+				if i, m := t.iface().typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -229,7 +222,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
 			return
 		}
 
-		current = check.consolidateMultiples(next)
+		current = consolidateMultiples(next)
 	}
 
 	return nil, nil, false // not found
@@ -246,7 +239,7 @@ type embeddedType struct {
 // consolidateMultiples collects multiple list entries with the same type
 // into a single entry marked as containing multiples. The result is the
 // consolidated list.
-func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
+func consolidateMultiples(list []embeddedType) []embeddedType {
 	if len(list) <= 1 {
 		return list // at most one entry - nothing to do
 	}
@@ -254,7 +247,7 @@ func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
 	n := 0                     // number of entries w/ unique type
 	prev := make(map[Type]int) // index at which type was previously seen
 	for _, e := range list {
-		if i, found := check.lookupType(prev, e.typ); found {
+		if i, found := lookupType(prev, e.typ); found {
 			list[i].multiples = true
 			// ignore this entry
 		} else {
@@ -266,14 +259,14 @@ func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
 	return list[:n]
 }
 
-func (check *Checker) lookupType(m map[Type]int, typ Type) (int, bool) {
+func lookupType(m map[Type]int, typ Type) (int, bool) {
 	// fast path: maybe the types are equal
 	if i, found := m[typ]; found {
 		return i, true
 	}
 
 	for t, i := range m {
-		if check.identical(t, typ) {
+		if Identical(t, typ) {
 			return i, true
 		}
 	}
@@ -306,40 +299,40 @@ func MissingMethod(V Type, T *Interface, static bool) (method *Func, wrongType b
 // To improve error messages, also report the wrong signature
 // when the method exists on *V instead of V.
 func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method, wrongType *Func) {
-	check.completeInterface(token.NoPos, T)
-
 	// fast path for common case
 	if T.Empty() {
 		return
 	}
 
 	if ityp := asInterface(V); ityp != nil {
-		check.completeInterface(token.NoPos, ityp)
-		// TODO(gri) allMethods is sorted - can do this more efficiently
-		for _, m := range T.allMethods {
-			_, f := lookupMethod(ityp.allMethods, m.pkg, m.name)
+		// TODO(gri) the methods are sorted - could do this more efficiently
+		for _, m := range T.typeSet().methods {
+			_, f := ityp.typeSet().LookupMethod(m.pkg, m.name)
 
 			if f == nil {
-				// if m is the magic method == we're ok (interfaces are comparable)
-				if m.name == "==" || !static {
+				if !static {
 					continue
 				}
 				return m, f
 			}
 
+			// both methods must have the same number of type parameters
 			ftyp := f.typ.(*Signature)
 			mtyp := m.typ.(*Signature)
-			if len(ftyp.tparams) != len(mtyp.tparams) {
+			if ftyp.TParams().Len() != mtyp.TParams().Len() {
 				return m, f
 			}
+			if ftyp.TParams().Len() > 0 {
+				panic("method with type parameters")
+			}
 
 			// If the methods have type parameters we don't care whether they
 			// are the same or not, as long as they match up. Use unification
 			// to see if they can be made to match.
 			// TODO(gri) is this always correct? what about type bounds?
 			// (Alternative is to rename/subst type parameters and compare.)
-			u := newUnifier(check, true)
-			u.x.init(ftyp.tparams)
+			u := newUnifier(true)
+			u.x.init(ftyp.TParams().list())
 			if !u.unify(ftyp, mtyp) {
 				return m, f
 			}
@@ -351,14 +344,14 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 	// A concrete type implements T if it implements all methods of T.
 	Vd, _ := deref(V)
 	Vn := asNamed(Vd)
-	for _, m := range T.allMethods {
+	for _, m := range T.typeSet().methods {
 		// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
-		obj, _, _ := check.rawLookupFieldOrMethod(V, false, m.pkg, m.name)
+		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
 
 		// Check if *V implements this method of T.
 		if obj == nil {
 			ptr := NewPointer(V)
-			obj, _, _ = check.rawLookupFieldOrMethod(ptr, false, m.pkg, m.name)
+			obj, _, _ = lookupFieldOrMethod(ptr, false, m.pkg, m.name)
 			if obj != nil {
 				return m, obj.(*Func)
 			}
@@ -367,10 +360,6 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// we must have a method (not a field of matching function type)
 		f, _ := obj.(*Func)
 		if f == nil {
-			// if m is the magic method == and V is comparable, we're ok
-			if m.name == "==" && Comparable(V) {
-				continue
-			}
 			return m, nil
 		}
 
@@ -382,9 +371,12 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// both methods must have the same number of type parameters
 		ftyp := f.typ.(*Signature)
 		mtyp := m.typ.(*Signature)
-		if len(ftyp.tparams) != len(mtyp.tparams) {
+		if ftyp.TParams().Len() != mtyp.TParams().Len() {
 			return m, f
 		}
+		if ftyp.TParams().Len() > 0 {
+			panic("method with type parameters")
+		}
 
 		// If V is a (instantiated) generic type, its methods are still
 		// parameterized using the original (declaration) receiver type
@@ -393,17 +385,17 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// In order to compare the signatures, substitute the receiver
 		// type parameters of ftyp with V's instantiation type arguments.
 		// This lazily instantiates the signature of method f.
-		if Vn != nil && len(Vn.tparams) > 0 {
+		if Vn != nil && Vn.TParams().Len() > 0 {
 			// Be careful: The number of type arguments may not match
 			// the number of receiver parameters. If so, an error was
 			// reported earlier but the length discrepancy is still
 			// here. Exit early in this case to prevent an assertion
 			// failure in makeSubstMap.
 			// TODO(gri) Can we avoid this check by fixing the lengths?
-			if len(ftyp.rparams) != len(Vn.targs) {
+			if len(ftyp.RParams().list()) != Vn.targs.Len() {
 				return
 			}
-			ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.rparams, Vn.targs)).(*Signature)
+			ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs.list()), nil).(*Signature)
 		}
 
 		// If the methods have type parameters we don't care whether they
@@ -411,8 +403,8 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// to see if they can be made to match.
 		// TODO(gri) is this always correct? what about type bounds?
 		// (Alternative is to rename/subst type parameters and compare.)
-		u := newUnifier(check, true)
-		u.x.init(ftyp.tparams)
+		u := newUnifier(true)
+		u.x.init(ftyp.RParams().list())
 		if !u.unify(ftyp, mtyp) {
 			return m, f
 		}
diff --git a/src/go/types/map.go b/src/go/types/map.go
new file mode 100644
index 0000000000000000000000000000000000000000..01e13b214e966412debe21f1f64e2d35d65abc66
--- /dev/null
+++ b/src/go/types/map.go
@@ -0,0 +1,24 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Map represents a map type.
+type Map struct {
+	key, elem Type
+}
+
+// NewMap returns a new map for the given key and element types.
+func NewMap(key, elem Type) *Map {
+	return &Map{key: key, elem: elem}
+}
+
+// Key returns the key type of map m.
+func (m *Map) Key() Type { return m.key }
+
+// Elem returns the element type of map m.
+func (m *Map) Elem() Type { return m.elem }
+
+func (t *Map) Underlying() Type { return t }
+func (t *Map) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/methodset.go b/src/go/types/methodset.go
index ae8011a2eeef92f8246631d13cf24d1cc5780504..1462601d5869e4a135bf8be616bd4028c49c090e 100644
--- a/src/go/types/methodset.go
+++ b/src/go/types/methodset.go
@@ -130,7 +130,7 @@ func NewMethodSet(T Type) *MethodSet {
 				// continue with underlying type, but only if it's not a type parameter
 				// TODO(rFindley): should this use named.under()? Can there be a difference?
 				typ = named.underlying
-				if _, ok := typ.(*_TypeParam); ok {
+				if _, ok := typ.(*TypeParam); ok {
 					continue
 				}
 			}
@@ -157,10 +157,10 @@ func NewMethodSet(T Type) *MethodSet {
 				}
 
 			case *Interface:
-				mset = mset.add(t.allMethods, e.index, true, e.multiples)
+				mset = mset.add(t.typeSet().methods, e.index, true, e.multiples)
 
-			case *_TypeParam:
-				mset = mset.add(t.Bound().allMethods, e.index, true, e.multiples)
+			case *TypeParam:
+				mset = mset.add(t.iface().typeSet().methods, e.index, true, e.multiples)
 			}
 		}
 
@@ -190,12 +190,7 @@ func NewMethodSet(T Type) *MethodSet {
 			}
 		}
 
-		// It's ok to call consolidateMultiples with a nil *Checker because
-		// MethodSets are not used internally (outside debug mode). When used
-		// externally, interfaces are expected to be completed and then we do
-		// not need a *Checker to complete them when (indirectly) calling
-		// Checker.identical via consolidateMultiples.
-		current = (*Checker)(nil).consolidateMultiples(next)
+		current = consolidateMultiples(next)
 	}
 
 	if len(base) == 0 {
diff --git a/src/go/types/methodset_test.go b/src/go/types/methodset_test.go
index 4a373fa2c4ff9846a46826a88a63b8c85b1522db..73a8442f21417de6c3c3f01019551b2ae825fc0d 100644
--- a/src/go/types/methodset_test.go
+++ b/src/go/types/methodset_test.go
@@ -7,7 +7,6 @@ package types_test
 import (
 	"testing"
 
-	"go/internal/typeparams"
 	. "go/types"
 )
 
@@ -47,12 +46,15 @@ func TestNewMethodSet(t *testing.T) {
 
 	genericTests := map[string][]method{
 		// By convention, look up a in the scope of "g"
-		"type C interface{ f() }; func g[T C](a T){}":                       {{"f", []int{0}, true}},
-		"type C interface{ f() }; func g[T C]() { var a T; _ = a }":         {{"f", []int{0}, true}},
-		"type C interface{ f() }; func g[T C]() { var a struct{T}; _ = a }": {{"f", []int{0, 0}, true}},
+		"type C interface{ f() }; func g[T C](a T){}":               {{"f", []int{0}, true}},
+		"type C interface{ f() }; func g[T C]() { var a T; _ = a }": {{"f", []int{0}, true}},
 
-		// Issue #45639.
-		"type C interface{ f() }; func g[T C]() { type Y T; var a Y; _ = a }": {},
+		// Issue #43621: We don't allow this anymore. Keep this code in case we
+		// decide to revisit this decision.
+		// "type C interface{ f() }; func g[T C]() { var a struct{T}; _ = a }": {{"f", []int{0, 0}, true}},
+
+		// Issue #45639: We also don't allow this anymore.
+		// "type C interface{ f() }; func g[T C]() { type Y T; var a Y; _ = a }": {},
 	}
 
 	check := func(src string, methods []method, generic bool) {
@@ -101,9 +103,7 @@ func TestNewMethodSet(t *testing.T) {
 		check(src, methods, false)
 	}
 
-	if typeparams.Enabled {
-		for src, methods := range genericTests {
-			check(src, methods, true)
-		}
+	for src, methods := range genericTests {
+		check(src, methods, true)
 	}
 }
diff --git a/src/go/types/named.go b/src/go/types/named.go
new file mode 100644
index 0000000000000000000000000000000000000000..6bc33b95389762df98334d360fd12f98c24a1b7b
--- /dev/null
+++ b/src/go/types/named.go
@@ -0,0 +1,295 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/token"
+	"sync"
+)
+
+// TODO(rfindley) Clean up Named struct below; specifically the fromRHS field (can we use underlying?).
+
+// A Named represents a named (defined) type.
+type Named struct {
+	check      *Checker
+	info       typeInfo    // for cycle detection
+	obj        *TypeName   // corresponding declared object for declared types; placeholder for instantiated types
+	orig       *Named      // original, uninstantiated type
+	fromRHS    Type        // type (on RHS of declaration) this *Named type is derived of (for cycle reporting)
+	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
+	instance   *instance   // syntactic information for lazy instantiation
+	tparams    *TParamList // type parameters, or nil
+	targs      *TypeList   // type arguments (after instantiation), or nil
+	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
+
+	resolve func(*Named) ([]*TypeParam, Type, []*Func)
+	once    sync.Once
+}
+
+// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
+// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
+// The underlying type must not be a *Named.
+func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
+	if _, ok := underlying.(*Named); ok {
+		panic("underlying type must not be *Named")
+	}
+	return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods)
+}
+
+func (t *Named) load() *Named {
+	// If t is an instantiated type, it derives its methods and tparams from its
+	// base type. Since we expect type parameters and methods to be set after a
+	// call to load, we must load the base and copy here.
+	//
+	// underlying is set when t is expanded.
+	//
+	// By convention, a type instance is loaded iff its tparams are set.
+	if t.targs.Len() > 0 && t.tparams == nil {
+		t.orig.load()
+		t.tparams = t.orig.tparams
+		t.methods = t.orig.methods
+	}
+	if t.resolve == nil {
+		return t
+	}
+
+	t.once.Do(func() {
+		// TODO(mdempsky): Since we're passing t to resolve anyway
+		// (necessary because types2 expects the receiver type for methods
+		// on defined interface types to be the Named rather than the
+		// underlying Interface), maybe it should just handle calling
+		// SetTParams, SetUnderlying, and AddMethod instead?  Those
+		// methods would need to support reentrant calls though.  It would
+		// also make the API more future-proof towards further extensions
+		// (like SetTParams).
+
+		tparams, underlying, methods := t.resolve(t)
+
+		switch underlying.(type) {
+		case nil, *Named:
+			panic("invalid underlying type")
+		}
+
+		t.tparams = bindTParams(tparams)
+		t.underlying = underlying
+		t.methods = methods
+	})
+	return t
+}
+
+// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
+func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams *TParamList, methods []*Func) *Named {
+	typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods}
+	if typ.orig == nil {
+		typ.orig = typ
+	}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	// Ensure that typ is always expanded, at which point the check field can be
+	// nilled out.
+	//
+	// Note that currently we cannot nil out check inside typ.under(), because
+	// it's possible that typ is expanded multiple times.
+	//
+	// TODO(rFindley): clean this up so that under is the only function mutating
+	//                 named types.
+	if check != nil {
+		check.later(func() {
+			switch typ.under().(type) {
+			case *Named:
+				panic("unexpanded underlying type")
+			}
+			typ.check = nil
+		})
+	}
+	return typ
+}
+
+// Obj returns the type name for the declaration defining the named type t. For
+// instantiated types, this is the type name of the base type.
+func (t *Named) Obj() *TypeName {
+	return t.orig.obj // for non-instances this is the same as t.obj
+}
+
+// _Orig returns the original generic type an instantiated type is derived from.
+// If t is not an instantiated type, the result is t.
+func (t *Named) _Orig() *Named { return t.orig }
+
+// TODO(gri) Come up with a better representation and API to distinguish
+//           between parameterized instantiated and non-instantiated types.
+
+// TParams returns the type parameters of the named type t, or nil.
+// The result is non-nil for an (originally) parameterized type even if it is instantiated.
+func (t *Named) TParams() *TParamList { return t.load().tparams }
+
+// SetTParams sets the type parameters of the named type t.
+func (t *Named) SetTParams(tparams []*TypeParam) { t.load().tparams = bindTParams(tparams) }
+
+// TArgs returns the type arguments used to instantiate the named type t.
+func (t *Named) TArgs() *TypeList { return t.targs }
+
+// NumMethods returns the number of explicit methods whose receiver is named type t.
+func (t *Named) NumMethods() int { return len(t.load().methods) }
+
+// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
+func (t *Named) Method(i int) *Func { return t.load().methods[i] }
+
+// SetUnderlying sets the underlying type and marks t as complete.
+func (t *Named) SetUnderlying(underlying Type) {
+	if underlying == nil {
+		panic("underlying type must not be nil")
+	}
+	if _, ok := underlying.(*Named); ok {
+		panic("underlying type must not be *Named")
+	}
+	t.load().underlying = underlying
+}
+
+// AddMethod adds method m unless it is already in the method list.
+func (t *Named) AddMethod(m *Func) {
+	t.load()
+	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
+		t.methods = append(t.methods, m)
+	}
+}
+
+func (t *Named) Underlying() Type { return t.load().expand(nil).underlying }
+func (t *Named) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// under returns the expanded underlying type of n0; possibly by following
+// forward chains of named types. If an underlying type is found, resolve
+// the chain by setting the underlying type for each defined type in the
+// chain before returning it. If no underlying type is found or a cycle
+// is detected, the result is Typ[Invalid]. If a cycle is detected and
+// n0.check != nil, the cycle is reported.
+func (n0 *Named) under() Type {
+	u := n0.Underlying()
+
+	// If the underlying type of a defined type is not a defined
+	// (incl. instance) type, then that is the desired underlying
+	// type.
+	var n1 *Named
+	switch u1 := u.(type) {
+	case nil:
+		return Typ[Invalid]
+	default:
+		// common case
+		return u
+	case *Named:
+		// handled below
+		n1 = u1
+	}
+
+	if n0.check == nil {
+		panic("Named.check == nil but type is incomplete")
+	}
+
+	// Invariant: after this point n0 as well as any named types in its
+	// underlying chain should be set up when this function exits.
+	check := n0.check
+	n := n0
+
+	seen := make(map[*Named]int) // types that need their underlying resolved
+	var path []Object            // objects encountered, for cycle reporting
+
+loop:
+	for {
+		seen[n] = len(seen)
+		path = append(path, n.obj)
+		n = n1
+		if i, ok := seen[n]; ok {
+			// cycle
+			check.cycleError(path[i:])
+			u = Typ[Invalid]
+			break
+		}
+		u = n.Underlying()
+		switch u1 := u.(type) {
+		case nil:
+			u = Typ[Invalid]
+			break loop
+		default:
+			break loop
+		case *Named:
+			// Continue collecting *Named types in the chain.
+			n1 = u1
+		}
+	}
+
+	for n := range seen {
+		// We should never have to update the underlying type of an imported type;
+		// those underlying types should have been resolved during the import.
+		// Also, doing so would lead to a race condition (was issue #31749).
+		// Do this check always, not just in debug mode (it's cheap).
+		if n.obj.pkg != check.pkg {
+			panic("imported type with unresolved underlying type")
+		}
+		n.underlying = u
+	}
+
+	return u
+}
+
+func (n *Named) setUnderlying(typ Type) {
+	if n != nil {
+		n.underlying = typ
+	}
+}
+
+// instance holds position information for use in lazy instantiation.
+//
+// TODO(rfindley): instance is probably unnecessary now. See if it can be
+// eliminated.
+type instance struct {
+	pos token.Pos // position of type instantiation; for error reporting only
+}
+
+// expand ensures that the underlying type of n is instantiated.
+// The underlying type will be Typ[Invalid] if there was an error.
+func (n *Named) expand(typMap map[string]*Named) *Named {
+	if n.instance != nil {
+		// n must be loaded before instantiation, in order to have accurate
+		// tparams. This is done implicitly by the call to n.TParams, but making it
+		// explicit is harmless: load is idempotent.
+		n.load()
+		var u Type
+		if n.check.validateTArgLen(n.instance.pos, n.tparams.Len(), n.targs.Len()) {
+			if typMap == nil {
+				if n.check != nil {
+					typMap = n.check.typMap
+				} else {
+					// If we're instantiating lazily, we might be outside the scope of a
+					// type-checking pass. In that case we won't have a pre-existing
+					// typMap, but don't want to create a duplicate of the current instance
+					// in the process of expansion.
+					h := instantiatedHash(n.orig, n.targs.list())
+					typMap = map[string]*Named{h: n}
+				}
+			}
+			u = n.check.subst(n.instance.pos, n.orig.underlying, makeSubstMap(n.TParams().list(), n.targs.list()), typMap)
+		} else {
+			u = Typ[Invalid]
+		}
+		n.underlying = u
+		n.fromRHS = u
+		n.instance = nil
+	}
+	return n
+}
+
+// safeUnderlying returns the underlying of typ without expanding instances, to
+// avoid infinite recursion.
+//
+// TODO(rfindley): eliminate this function or give it a better name.
+func safeUnderlying(typ Type) Type {
+	if t, _ := typ.(*Named); t != nil {
+		return t.load().underlying
+	}
+	return typ.Underlying()
+}
diff --git a/src/go/types/object.go b/src/go/types/object.go
index 50346ec6919407e41e730b09c849a324938b18de..eb5df56d1423b869e96fb725dc854c9c23bccef3 100644
--- a/src/go/types/object.go
+++ b/src/go/types/object.go
@@ -230,6 +230,14 @@ func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName {
 	return &TypeName{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}}
 }
 
+// _NewTypeNameLazy returns a new defined type like NewTypeName, but it
+// lazily calls resolve to finish constructing the Named object.
+func _NewTypeNameLazy(pos token.Pos, pkg *Package, name string, resolve func(named *Named) (tparams []*TypeParam, underlying Type, methods []*Func)) *TypeName {
+	obj := NewTypeName(pos, pkg, name, nil)
+	NewNamed(obj, nil, nil).resolve = resolve
+	return obj
+}
+
 // IsAlias reports whether obj is an alias name for a type.
 func (obj *TypeName) IsAlias() bool {
 	switch t := obj.typ.(type) {
@@ -421,6 +429,9 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 		if _, ok := typ.(*Basic); ok {
 			return
 		}
+		if named, _ := typ.(*Named); named != nil && named.TParams().Len() > 0 {
+			writeTParamList(buf, named.TParams().list(), qf, nil)
+		}
 		if tname.IsAlias() {
 			buf.WriteString(" =")
 		} else {
diff --git a/src/go/types/object_test.go b/src/go/types/object_test.go
index 2b6057bd934bca19cfa0f40062d6b8bb63fdd744..0ff8fdd6fa69bad43ca3a603d6f3d7fe6770d89a 100644
--- a/src/go/types/object_test.go
+++ b/src/go/types/object_test.go
@@ -22,7 +22,7 @@ func TestIsAlias(t *testing.T) {
 	check(Unsafe.Scope().Lookup("Pointer").(*TypeName), false)
 	for _, name := range Universe.Names() {
 		if obj, _ := Universe.Lookup(name).(*TypeName); obj != nil {
-			check(obj, name == "byte" || name == "rune")
+			check(obj, name == "any" || name == "byte" || name == "rune")
 		}
 	}
 
diff --git a/src/go/types/operand.go b/src/go/types/operand.go
index 6463728cec6a37b9308fa8853663104deaa2ed90..a54802defc53452a26504efc28c80cc1a628c895 100644
--- a/src/go/types/operand.go
+++ b/src/go/types/operand.go
@@ -159,16 +159,20 @@ func operandString(x *operand, qf Qualifier) string {
 	if hasType {
 		if x.typ != Typ[Invalid] {
 			var intro string
-			switch {
-			case isGeneric(x.typ):
-				intro = " of generic type "
-			case asTypeParam(x.typ) != nil:
-				intro = " of type parameter type "
-			default:
+			var tpar *TypeParam
+			if isGeneric(x.typ) {
+				intro = " of parameterized type "
+			} else if tpar = asTypeParam(x.typ); tpar != nil {
+				intro = " of type parameter "
+			} else {
 				intro = " of type "
 			}
 			buf.WriteString(intro)
 			WriteType(&buf, x.typ, qf)
+			if tpar != nil {
+				buf.WriteString(" constrained by ")
+				WriteType(&buf, tpar.bound, qf) // do not compute interface type sets here
+			}
 		} else {
 			buf.WriteString(" with invalid type")
 		}
@@ -233,20 +237,35 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 
 	V := x.typ
 
+	const debugAssignableTo = false
+	if debugAssignableTo && check != nil {
+		check.dump("V = %s", V)
+		check.dump("T = %s", T)
+	}
+
 	// x's type is identical to T
-	if check.identical(V, T) {
+	if Identical(V, T) {
 		return true, 0
 	}
 
 	Vu := optype(V)
 	Tu := optype(T)
 
+	if debugAssignableTo && check != nil {
+		check.dump("Vu = %s", Vu)
+		check.dump("Tu = %s", Tu)
+	}
+
 	// x is an untyped value representable by a value of type T.
 	if isUntyped(Vu) {
-		if t, ok := Tu.(*_Sum); ok {
-			return t.is(func(t Type) bool {
+		if t, _ := under(T).(*TypeParam); t != nil {
+			return t.is(func(t *term) bool {
 				// TODO(gri) this could probably be more efficient
-				ok, _ := x.assignableTo(check, t, reason)
+				if t.tilde {
+					// TODO(gri) We need to check assignability
+					//           for the underlying type of x.
+				}
+				ok, _ := x.assignableTo(check, t.typ, reason)
 				return ok
 			}), _IncompatibleAssign
 		}
@@ -257,7 +276,7 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 
 	// x's type V and T have identical underlying types
 	// and at least one of V or T is not a named type
-	if check.identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
+	if Identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
 		return true, 0
 	}
 
@@ -266,7 +285,7 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 		if m, wrongType := check.missingMethod(V, Ti, true); m != nil /* Implements(V, Ti) */ {
 			if reason != nil {
 				if wrongType != nil {
-					if check.identical(m.typ, wrongType.typ) {
+					if Identical(m.typ, wrongType.typ) {
 						*reason = fmt.Sprintf("missing method %s (%s has pointer receiver)", m.name, m.name)
 					} else {
 						*reason = fmt.Sprintf("wrong type for method %s (have %s, want %s)", m.Name(), wrongType.typ, m.typ)
@@ -285,7 +304,7 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) (bool, er
 	// type, x's type V and T have identical element types,
 	// and at least one of V or T is not a named type
 	if Vc, ok := Vu.(*Chan); ok && Vc.dir == SendRecv {
-		if Tc, ok := Tu.(*Chan); ok && check.identical(Vc.elem, Tc.elem) {
+		if Tc, ok := Tu.(*Chan); ok && Identical(Vc.elem, Tc.elem) {
 			return !isNamed(V) || !isNamed(T), _InvalidChanAssign
 		}
 	}
diff --git a/src/go/types/pointer.go b/src/go/types/pointer.go
new file mode 100644
index 0000000000000000000000000000000000000000..6352ee57e2c832ca0e3eea4aa2106a9aeba42675
--- /dev/null
+++ b/src/go/types/pointer.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Pointer represents a pointer type.
+type Pointer struct {
+	base Type // element type
+}
+
+// NewPointer returns a new pointer type for the given element (base) type.
+func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
+
+// Elem returns the element type for the given pointer p.
+func (p *Pointer) Elem() Type { return p.base }
+
+func (t *Pointer) Underlying() Type { return t }
+func (t *Pointer) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/predicates.go b/src/go/types/predicates.go
index 7bb026414f8c36366b47cf164236662dbe5e9dc9..2f4ef9dace0d743583095e162c7abc10532b3e5b 100644
--- a/src/go/types/predicates.go
+++ b/src/go/types/predicates.go
@@ -6,15 +6,11 @@
 
 package types
 
-import (
-	"go/token"
-)
-
 // isNamed reports whether typ has a name.
 // isNamed may be called with types that are not fully set up.
 func isNamed(typ Type) bool {
 	switch typ.(type) {
-	case *Basic, *Named, *_TypeParam, *instance:
+	case *Basic, *Named, *TypeParam:
 		return true
 	}
 	return false
@@ -25,15 +21,15 @@ func isNamed(typ Type) bool {
 func isGeneric(typ Type) bool {
 	// A parameterized type is only instantiated if it doesn't have an instantiation already.
 	named, _ := typ.(*Named)
-	return named != nil && named.obj != nil && named.tparams != nil && named.targs == nil
+	return named != nil && named.obj != nil && named.targs == nil && named.TParams() != nil
 }
 
 func is(typ Type, what BasicInfo) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.info&what != 0
-	case *_Sum:
-		return t.is(func(typ Type) bool { return is(typ, what) })
+	case *TypeParam:
+		return t.underIs(func(typ Type) bool { return is(typ, what) })
 	}
 	return false
 }
@@ -61,9 +57,6 @@ func isNumericOrString(typ Type) bool { return is(typ, IsNumeric|IsString) }
 func isTyped(typ Type) bool {
 	// isTyped is called with types that are not fully
 	// set up. Must not call asBasic()!
-	// A *Named or *instance type is always typed, so
-	// we only need to check if we have a true *Basic
-	// type.
 	t, _ := typ.(*Basic)
 	return t == nil || t.info&IsUntyped == 0
 }
@@ -100,19 +93,7 @@ func comparable(T Type, seen map[Type]bool) bool {
 	}
 	seen[T] = true
 
-	// If T is a type parameter not constrained by any type
-	// list (i.e., it's underlying type is the top type),
-	// T is comparable if it has the == method. Otherwise,
-	// the underlying type "wins". For instance
-	//
-	//     interface{ comparable; type []byte }
-	//
-	// is not comparable because []byte is not comparable.
-	if t := asTypeParam(T); t != nil && optype(t) == theTop {
-		return t.Bound()._IsComparable()
-	}
-
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		// assume invalid types to be comparable
 		// to avoid follow-up errors
@@ -128,42 +109,25 @@ func comparable(T Type, seen map[Type]bool) bool {
 		return true
 	case *Array:
 		return comparable(t.elem, seen)
-	case *_Sum:
-		pred := func(t Type) bool {
-			return comparable(t, seen)
-		}
-		return t.is(pred)
-	case *_TypeParam:
-		return t.Bound()._IsComparable()
+	case *TypeParam:
+		return t.iface().IsComparable()
 	}
 	return false
 }
 
 // hasNil reports whether a type includes the nil value.
 func hasNil(typ Type) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.kind == UnsafePointer
 	case *Slice, *Pointer, *Signature, *Interface, *Map, *Chan:
 		return true
-	case *_Sum:
-		return t.is(hasNil)
+	case *TypeParam:
+		return t.underIs(hasNil)
 	}
 	return false
 }
 
-// identical reports whether x and y are identical types.
-// Receivers of Signature types are ignored.
-func (check *Checker) identical(x, y Type) bool {
-	return check.identical0(x, y, true, nil)
-}
-
-// identicalIgnoreTags reports whether x and y are identical types if tags are ignored.
-// Receivers of Signature types are ignored.
-func (check *Checker) identicalIgnoreTags(x, y Type) bool {
-	return check.identical0(x, y, false, nil)
-}
-
 // An ifacePair is a node in a stack of interface type pairs compared for identity.
 type ifacePair struct {
 	x, y *Interface
@@ -175,11 +139,7 @@ func (p *ifacePair) identical(q *ifacePair) bool {
 }
 
 // For changes to this code the corresponding changes should be made to unifier.nify.
-func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
-	// types must be expanded for comparison
-	x = expandf(x)
-	y = expandf(y)
-
+func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	if x == y {
 		return true
 	}
@@ -199,13 +159,13 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 		if y, ok := y.(*Array); ok {
 			// If one or both array lengths are unknown (< 0) due to some error,
 			// assume they are the same to avoid spurious follow-on errors.
-			return (x.len < 0 || y.len < 0 || x.len == y.len) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return (x.len < 0 || y.len < 0 || x.len == y.len) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Slice:
 		// Two slice types are identical if they have identical element types.
 		if y, ok := y.(*Slice); ok {
-			return check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Struct:
@@ -220,7 +180,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 					if f.embedded != g.embedded ||
 						cmpTags && x.Tag(i) != y.Tag(i) ||
 						!f.sameId(g.pkg, g.name) ||
-						!check.identical0(f.typ, g.typ, cmpTags, p) {
+						!identical(f.typ, g.typ, cmpTags, p) {
 						return false
 					}
 				}
@@ -231,7 +191,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Pointer:
 		// Two pointer types are identical if they have identical base types.
 		if y, ok := y.(*Pointer); ok {
-			return check.identical0(x.base, y.base, cmpTags, p)
+			return identical(x.base, y.base, cmpTags, p)
 		}
 
 	case *Tuple:
@@ -242,7 +202,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 				if x != nil {
 					for i, v := range x.vars {
 						w := y.vars[i]
-						if !check.identical0(v.typ, w.typ, cmpTags, p) {
+						if !identical(v.typ, w.typ, cmpTags, p) {
 							return false
 						}
 					}
@@ -260,49 +220,27 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 		// parameter names.
 		if y, ok := y.(*Signature); ok {
 			return x.variadic == y.variadic &&
-				check.identicalTParams(x.tparams, y.tparams, cmpTags, p) &&
-				check.identical0(x.params, y.params, cmpTags, p) &&
-				check.identical0(x.results, y.results, cmpTags, p)
-		}
-
-	case *_Sum:
-		// Two sum types are identical if they contain the same types.
-		// (Sum types always consist of at least two types. Also, the
-		// the set (list) of types in a sum type consists of unique
-		// types - each type appears exactly once. Thus, two sum types
-		// must contain the same number of types to have chance of
-		// being equal.
-		if y, ok := y.(*_Sum); ok && len(x.types) == len(y.types) {
-			// Every type in x.types must be in y.types.
-			// Quadratic algorithm, but probably good enough for now.
-			// TODO(gri) we need a fast quick type ID/hash for all types.
-		L:
-			for _, x := range x.types {
-				for _, y := range y.types {
-					if Identical(x, y) {
-						continue L // x is in y.types
-					}
-				}
-				return false // x is not in y.types
-			}
-			return true
+				identicalTParams(x.TParams().list(), y.TParams().list(), cmpTags, p) &&
+				identical(x.params, y.params, cmpTags, p) &&
+				identical(x.results, y.results, cmpTags, p)
 		}
 
 	case *Interface:
+		// Two interface types are identical if they describe the same type sets.
+		// With the existing implementation restriction, this simplifies to:
+		//
 		// Two interface types are identical if they have the same set of methods with
-		// the same names and identical function types. Lower-case method names from
-		// different packages are always different. The order of the methods is irrelevant.
+		// the same names and identical function types, and if any type restrictions
+		// are the same. Lower-case method names from different packages are always
+		// different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if check != nil {
-				check.completeInterface(token.NoPos, x)
-				check.completeInterface(token.NoPos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !xset.terms.equal(yset.terms) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -339,7 +277,7 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 				}
 				for i, f := range a {
 					g := b[i]
-					if f.Id() != g.Id() || !check.identical0(f.typ, g.typ, cmpTags, q) {
+					if f.Id() != g.Id() || !identical(f.typ, g.typ, cmpTags, q) {
 						return false
 					}
 				}
@@ -350,36 +288,58 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Map:
 		// Two map types are identical if they have identical key and value types.
 		if y, ok := y.(*Map); ok {
-			return check.identical0(x.key, y.key, cmpTags, p) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.key, y.key, cmpTags, p) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Chan:
 		// Two channel types are identical if they have identical value types
 		// and the same direction.
 		if y, ok := y.(*Chan); ok {
-			return x.dir == y.dir && check.identical0(x.elem, y.elem, cmpTags, p)
+			return x.dir == y.dir && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Named:
 		// Two named types are identical if their type names originate
 		// in the same type declaration.
 		if y, ok := y.(*Named); ok {
+			x.expand(nil)
+			y.expand(nil)
+
+			xargs := x.TArgs().list()
+			yargs := y.TArgs().list()
+
+			if len(xargs) != len(yargs) {
+				return false
+			}
+
+			if nargs := len(xargs); nargs > 0 {
+				// Instances are identical if their original type and type arguments
+				// are identical.
+				if !Identical(x.orig, y.orig) {
+					return false
+				}
+				for i := 0; i < nargs; i++ {
+					xa := xargs[i]
+					ya := yargs[i]
+					if !Identical(xa, ya) {
+						return false
+					}
+				}
+				return true
+			}
+
 			// TODO(gri) Why is x == y not sufficient? And if it is,
 			//           we can just return false here because x == y
 			//           is caught in the very beginning of this function.
 			return x.obj == y.obj
 		}
 
-	case *_TypeParam:
+	case *TypeParam:
 		// nothing to do (x and y being equal is caught in the very beginning of this function)
 
-	// case *instance:
-	//	unreachable since types are expanded
-
-	case *bottom, *top:
-		// Either both types are theBottom, or both are theTop in which
-		// case the initial x == y check will have caught them. Otherwise
-		// they are not identical.
+	case *top:
+		// Either both types are theTop in which case the initial x == y check
+		// will have caught them. Otherwise they are not identical.
 
 	case nil:
 		// avoid a crash in case of nil type
@@ -391,13 +351,13 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
 	return false
 }
 
-func (check *Checker) identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
+func identicalTParams(x, y []*TypeParam, cmpTags bool, p *ifacePair) bool {
 	if len(x) != len(y) {
 		return false
 	}
 	for i, x := range x {
 		y := y[i]
-		if !check.identical0(x.typ.(*_TypeParam).bound, y.typ.(*_TypeParam).bound, cmpTags, p) {
+		if !identical(x.bound, y.bound, cmpTags, p) {
 			return false
 		}
 	}
diff --git a/src/go/types/resolver.go b/src/go/types/resolver.go
index 114647a2fffecb937bd785c3d85e3467626499a4..5e58c3dcfd568839df2d82264b992298a5622464 100644
--- a/src/go/types/resolver.go
+++ b/src/go/types/resolver.go
@@ -276,7 +276,7 @@ func (check *Checker) collectObjects() {
 				}
 
 				if name == "init" {
-					check.errorf(d.spec.Name, _InvalidInitDecl, "cannot import package as init - init must be a func")
+					check.errorf(d.spec, _InvalidInitDecl, "cannot import package as init - init must be a func")
 					return
 				}
 
@@ -309,20 +309,24 @@ func (check *Checker) collectObjects() {
 						check.dotImportMap = make(map[dotImportKey]*PkgName)
 					}
 					// merge imported scope with file scope
-					for _, obj := range imp.scope.elems {
+					for name, obj := range imp.scope.elems {
+						// Note: Avoid eager resolve(name, obj) here, so we only
+						// resolve dot-imported objects as needed.
+
 						// A package scope may contain non-exported objects,
 						// do not import them!
-						if obj.Exported() {
+						if token.IsExported(name) {
 							// declare dot-imported object
 							// (Do not use check.declare because it modifies the object
 							// via Object.setScopePos, which leads to a race condition;
 							// the object may be imported into more than one file scope
 							// concurrently. See issue #32154.)
-							if alt := fileScope.Insert(obj); alt != nil {
-								check.errorf(d.spec.Name, _DuplicateDecl, "%s redeclared in this block", obj.Name())
+							if alt := fileScope.Lookup(name); alt != nil {
+								check.errorf(d.spec.Name, _DuplicateDecl, "%s redeclared in this block", alt.Name())
 								check.reportAltDecl(alt)
 							} else {
-								check.dotImportMap[dotImportKey{fileScope, obj}] = pkgName
+								fileScope.insert(name, obj)
+								check.dotImportMap[dotImportKey{fileScope, name}] = pkgName
 							}
 						}
 					}
@@ -443,8 +447,9 @@ func (check *Checker) collectObjects() {
 
 	// verify that objects in package and file scopes have different names
 	for _, scope := range fileScopes {
-		for _, obj := range scope.elems {
-			if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
+		for name, obj := range scope.elems {
+			if alt := pkg.scope.Lookup(name); alt != nil {
+				obj = resolve(name, obj)
 				if pkg, ok := obj.(*PkgName); ok {
 					check.errorf(alt, _DuplicateDecl, "%s already declared through import of %s", alt.Name(), pkg.Imported())
 					check.reportAltDecl(pkg)
@@ -499,10 +504,12 @@ L: // unpack receiver type
 	}
 
 	// unpack type parameters, if any
-	if ptyp, _ := rtyp.(*ast.IndexExpr); ptyp != nil {
-		rtyp = ptyp.X
+	switch rtyp.(type) {
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(rtyp)
+		rtyp = ix.X
 		if unpackParams {
-			for _, arg := range typeparams.UnpackExpr(ptyp.Index) {
+			for _, arg := range ix.Indices {
 				var par *ast.Ident
 				switch arg := arg.(type) {
 				case *ast.Ident:
@@ -510,7 +517,7 @@ L: // unpack receiver type
 				case *ast.BadExpr:
 					// ignore - error already reported by parser
 				case nil:
-					check.invalidAST(ptyp, "parameterized receiver contains nil parameters")
+					check.invalidAST(ix.Orig, "parameterized receiver contains nil parameters")
 				default:
 					check.errorf(arg, _Todo, "receiver type parameter %s must be an identifier", arg)
 				}
diff --git a/src/go/types/sanitize.go b/src/go/types/sanitize.go
deleted file mode 100644
index 727ec173eac81a4077be56e5f1a1affe9372e88b..0000000000000000000000000000000000000000
--- a/src/go/types/sanitize.go
+++ /dev/null
@@ -1,206 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package types
-
-// sanitizeInfo walks the types contained in info to ensure that all instances
-// are expanded.
-//
-// This includes some objects that may be shared across concurrent
-// type-checking passes (such as those in the universe scope), so we are
-// careful here not to write types that are already sanitized. This avoids a
-// data race as any shared types should already be sanitized.
-func sanitizeInfo(info *Info) {
-	var s sanitizer = make(map[Type]Type)
-
-	// Note: Some map entries are not references.
-	// If modified, they must be assigned back.
-
-	for e, tv := range info.Types {
-		if typ := s.typ(tv.Type); typ != tv.Type {
-			tv.Type = typ
-			info.Types[e] = tv
-		}
-	}
-
-	inferred := getInferred(info)
-	for e, inf := range inferred {
-		changed := false
-		for i, targ := range inf.Targs {
-			if typ := s.typ(targ); typ != targ {
-				inf.Targs[i] = typ
-				changed = true
-			}
-		}
-		if typ := s.typ(inf.Sig); typ != inf.Sig {
-			inf.Sig = typ.(*Signature)
-			changed = true
-		}
-		if changed {
-			inferred[e] = inf
-		}
-	}
-
-	for _, obj := range info.Defs {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	for _, obj := range info.Uses {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	// TODO(gri) sanitize as needed
-	// - info.Implicits
-	// - info.Selections
-	// - info.Scopes
-	// - info.InitOrder
-}
-
-type sanitizer map[Type]Type
-
-func (s sanitizer) typ(typ Type) Type {
-	if typ == nil {
-		return nil
-	}
-
-	if t, found := s[typ]; found {
-		return t
-	}
-	s[typ] = typ
-
-	switch t := typ.(type) {
-	case *Basic, *bottom, *top:
-		// nothing to do
-
-	case *Array:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Slice:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Struct:
-		s.varList(t.fields)
-
-	case *Pointer:
-		if base := s.typ(t.base); base != t.base {
-			t.base = base
-		}
-
-	case *Tuple:
-		s.tuple(t)
-
-	case *Signature:
-		s.var_(t.recv)
-		s.tuple(t.params)
-		s.tuple(t.results)
-
-	case *_Sum:
-		s.typeList(t.types)
-
-	case *Interface:
-		s.funcList(t.methods)
-		if types := s.typ(t.types); types != t.types {
-			t.types = types
-		}
-		s.typeList(t.embeddeds)
-		s.funcList(t.allMethods)
-		if allTypes := s.typ(t.allTypes); allTypes != t.allTypes {
-			t.allTypes = allTypes
-		}
-
-	case *Map:
-		if key := s.typ(t.key); key != t.key {
-			t.key = key
-		}
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Chan:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Named:
-		if debug && t.check != nil {
-			panic("internal error: Named.check != nil")
-		}
-		if orig := s.typ(t.orig); orig != t.orig {
-			t.orig = orig
-		}
-		if under := s.typ(t.underlying); under != t.underlying {
-			t.underlying = under
-		}
-		s.typeList(t.targs)
-		s.funcList(t.methods)
-
-	case *_TypeParam:
-		if bound := s.typ(t.bound); bound != t.bound {
-			t.bound = bound
-		}
-
-	case *instance:
-		typ = t.expand()
-		s[t] = typ
-
-	default:
-		panic("unimplemented")
-	}
-
-	return typ
-}
-
-func (s sanitizer) var_(v *Var) {
-	if v != nil {
-		if typ := s.typ(v.typ); typ != v.typ {
-			v.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) varList(list []*Var) {
-	for _, v := range list {
-		s.var_(v)
-	}
-}
-
-func (s sanitizer) tuple(t *Tuple) {
-	if t != nil {
-		s.varList(t.vars)
-	}
-}
-
-func (s sanitizer) func_(f *Func) {
-	if f != nil {
-		if typ := s.typ(f.typ); typ != f.typ {
-			f.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) funcList(list []*Func) {
-	for _, f := range list {
-		s.func_(f)
-	}
-}
-
-func (s sanitizer) typeList(list []Type) {
-	for i, t := range list {
-		if typ := s.typ(t); typ != t {
-			list[i] = typ
-		}
-	}
-}
diff --git a/src/go/types/scope.go b/src/go/types/scope.go
index 26c28d1c4e3c46437d8640b893137ef3b0ccdcef..010727eb722a7bf81756e9ff17aa8e02a949f07b 100644
--- a/src/go/types/scope.go
+++ b/src/go/types/scope.go
@@ -13,6 +13,7 @@ import (
 	"io"
 	"sort"
 	"strings"
+	"sync"
 )
 
 // A Scope maintains a set of objects and links to its containing
@@ -22,6 +23,7 @@ import (
 type Scope struct {
 	parent   *Scope
 	children []*Scope
+	number   int               // parent.children[number-1] is this scope; 0 if there is no parent
 	elems    map[string]Object // lazily allocated
 	pos, end token.Pos         // scope extent; may be invalid
 	comment  string            // for debugging only
@@ -31,10 +33,11 @@ type Scope struct {
 // NewScope returns a new, empty scope contained in the given parent
 // scope, if any. The comment is for debugging only.
 func NewScope(parent *Scope, pos, end token.Pos, comment string) *Scope {
-	s := &Scope{parent, nil, nil, pos, end, comment, false}
+	s := &Scope{parent, nil, 0, nil, pos, end, comment, false}
 	// don't add children to Universe scope!
 	if parent != nil && parent != Universe {
 		parent.children = append(parent.children, s)
+		s.number = len(parent.children)
 	}
 	return s
 }
@@ -66,7 +69,7 @@ func (s *Scope) Child(i int) *Scope { return s.children[i] }
 // Lookup returns the object in scope s with the given name if such an
 // object exists; otherwise the result is nil.
 func (s *Scope) Lookup(name string) Object {
-	return s.elems[name]
+	return resolve(name, s.elems[name])
 }
 
 // LookupParent follows the parent chain of scopes starting with s until
@@ -81,7 +84,7 @@ func (s *Scope) Lookup(name string) Object {
 // whose scope is the scope of the package that exported them.
 func (s *Scope) LookupParent(name string, pos token.Pos) (*Scope, Object) {
 	for ; s != nil; s = s.parent {
-		if obj := s.elems[name]; obj != nil && (!pos.IsValid() || obj.scopePos() <= pos) {
+		if obj := s.Lookup(name); obj != nil && (!pos.IsValid() || obj.scopePos() <= pos) {
 			return s, obj
 		}
 	}
@@ -95,19 +98,38 @@ func (s *Scope) LookupParent(name string, pos token.Pos) (*Scope, Object) {
 // if not already set, and returns nil.
 func (s *Scope) Insert(obj Object) Object {
 	name := obj.Name()
-	if alt := s.elems[name]; alt != nil {
+	if alt := s.Lookup(name); alt != nil {
 		return alt
 	}
-	if s.elems == nil {
-		s.elems = make(map[string]Object)
-	}
-	s.elems[name] = obj
+	s.insert(name, obj)
 	if obj.Parent() == nil {
 		obj.setParent(s)
 	}
 	return nil
 }
 
+// _InsertLazy is like Insert, but allows deferring construction of the
+// inserted object until it's accessed with Lookup. The Object
+// returned by resolve must have the same name as given to _InsertLazy.
+// If s already contains an alternative object with the same name,
+// _InsertLazy leaves s unchanged and returns false. Otherwise it
+// records the binding and returns true. The object's parent scope
+// will be set to s after resolve is called.
+func (s *Scope) _InsertLazy(name string, resolve func() Object) bool {
+	if s.elems[name] != nil {
+		return false
+	}
+	s.insert(name, &lazyObject{parent: s, resolve: resolve})
+	return true
+}
+
+func (s *Scope) insert(name string, obj Object) {
+	if s.elems == nil {
+		s.elems = make(map[string]Object)
+	}
+	s.elems[name] = obj
+}
+
 // squash merges s with its parent scope p by adding all
 // objects of s to p, adding all children of s to the
 // children of p, and removing s from p's children.
@@ -117,7 +139,8 @@ func (s *Scope) Insert(obj Object) Object {
 func (s *Scope) squash(err func(obj, alt Object)) {
 	p := s.parent
 	assert(p != nil)
-	for _, obj := range s.elems {
+	for name, obj := range s.elems {
+		obj = resolve(name, obj)
 		obj.setParent(nil)
 		if alt := p.Insert(obj); alt != nil {
 			err(obj, alt)
@@ -196,7 +219,7 @@ func (s *Scope) WriteTo(w io.Writer, n int, recurse bool) {
 
 	indn1 := indn + ind
 	for _, name := range s.Names() {
-		fmt.Fprintf(w, "%s%s\n", indn1, s.elems[name])
+		fmt.Fprintf(w, "%s%s\n", indn1, s.Lookup(name))
 	}
 
 	if recurse {
@@ -214,3 +237,57 @@ func (s *Scope) String() string {
 	s.WriteTo(&buf, 0, false)
 	return buf.String()
 }
+
+// A lazyObject represents an imported Object that has not been fully
+// resolved yet by its importer.
+type lazyObject struct {
+	parent  *Scope
+	resolve func() Object
+	obj     Object
+	once    sync.Once
+}
+
+// resolve returns the Object represented by obj, resolving lazy
+// objects as appropriate.
+func resolve(name string, obj Object) Object {
+	if lazy, ok := obj.(*lazyObject); ok {
+		lazy.once.Do(func() {
+			obj := lazy.resolve()
+
+			if _, ok := obj.(*lazyObject); ok {
+				panic("recursive lazy object")
+			}
+			if obj.Name() != name {
+				panic("lazy object has unexpected name")
+			}
+
+			if obj.Parent() == nil {
+				obj.setParent(lazy.parent)
+			}
+			lazy.obj = obj
+		})
+
+		obj = lazy.obj
+	}
+	return obj
+}
+
+// stub implementations so *lazyObject implements Object and we can
+// store them directly into Scope.elems.
+func (*lazyObject) Parent() *Scope                        { panic("unreachable") }
+func (*lazyObject) Pos() token.Pos                        { panic("unreachable") }
+func (*lazyObject) Pkg() *Package                         { panic("unreachable") }
+func (*lazyObject) Name() string                          { panic("unreachable") }
+func (*lazyObject) Type() Type                            { panic("unreachable") }
+func (*lazyObject) Exported() bool                        { panic("unreachable") }
+func (*lazyObject) Id() string                            { panic("unreachable") }
+func (*lazyObject) String() string                        { panic("unreachable") }
+func (*lazyObject) order() uint32                         { panic("unreachable") }
+func (*lazyObject) color() color                          { panic("unreachable") }
+func (*lazyObject) setType(Type)                          { panic("unreachable") }
+func (*lazyObject) setOrder(uint32)                       { panic("unreachable") }
+func (*lazyObject) setColor(color color)                  { panic("unreachable") }
+func (*lazyObject) setParent(*Scope)                      { panic("unreachable") }
+func (*lazyObject) sameId(pkg *Package, name string) bool { panic("unreachable") }
+func (*lazyObject) scopePos() token.Pos                   { panic("unreachable") }
+func (*lazyObject) setScopePos(pos token.Pos)             { panic("unreachable") }
diff --git a/src/go/types/signature.go b/src/go/types/signature.go
new file mode 100644
index 0000000000000000000000000000000000000000..d6c12cf3d9e8cea0e1b4e59256ed07ede55c9470
--- /dev/null
+++ b/src/go/types/signature.go
@@ -0,0 +1,352 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"fmt"
+	"go/ast"
+	"go/internal/typeparams"
+	"go/token"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Signature represents a (non-builtin) function or method type.
+// The receiver is ignored when comparing signatures for identity.
+type Signature struct {
+	// We need to keep the scope in Signature (rather than passing it around
+	// and store it in the Func Object) because when type-checking a function
+	// literal we call the general type checker which returns a general Type.
+	// We then unpack the *Signature and use the scope for the literal body.
+	rparams  *TParamList // receiver type parameters from left to right, or nil
+	tparams  *TParamList // type parameters from left to right, or nil
+	scope    *Scope      // function scope, present for package-local signatures
+	recv     *Var        // nil if not a method
+	params   *Tuple      // (incoming) parameters from left to right; or nil
+	results  *Tuple      // (outgoing) results from left to right; or nil
+	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
+}
+
+// NewSignature returns a new function type for the given receiver, parameters,
+// and results, either of which may be nil. If variadic is set, the function
+// is variadic, it must have at least one parameter, and the last parameter
+// must be of unnamed slice type.
+func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
+	if variadic {
+		n := params.Len()
+		if n == 0 {
+			panic("variadic function must have at least one parameter")
+		}
+		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
+			panic("variadic parameter must be of unnamed slice type")
+		}
+	}
+	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
+}
+
+// Recv returns the receiver of signature s (if a method), or nil if a
+// function. It is ignored when comparing signatures for identity.
+//
+// For an abstract method, Recv returns the enclosing interface either
+// as a *Named or an *Interface. Due to embedding, an interface may
+// contain methods whose receiver type is a different interface.
+func (s *Signature) Recv() *Var { return s.recv }
+
+// TParams returns the type parameters of signature s, or nil.
+func (s *Signature) TParams() *TParamList { return s.tparams }
+
+// SetTParams sets the type parameters of signature s.
+func (s *Signature) SetTParams(tparams []*TypeParam) { s.tparams = bindTParams(tparams) }
+
+// RParams returns the receiver type parameters of signature s, or nil.
+func (s *Signature) RParams() *TParamList { return s.rparams }
+
+// SetRParams sets the receiver type params of signature s.
+func (s *Signature) SetRParams(rparams []*TypeParam) { s.rparams = bindTParams(rparams) }
+
+// Params returns the parameters of signature s, or nil.
+func (s *Signature) Params() *Tuple { return s.params }
+
+// Results returns the results of signature s, or nil.
+func (s *Signature) Results() *Tuple { return s.results }
+
+// Variadic reports whether the signature s is variadic.
+func (s *Signature) Variadic() bool { return s.variadic }
+
+func (t *Signature) Underlying() Type { return t }
+func (t *Signature) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// funcType type-checks a function or method type.
+func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
+	check.openScope(ftyp, "function")
+	check.scope.isFunc = true
+	check.recordScope(ftyp, check.scope)
+	sig.scope = check.scope
+	defer check.closeScope()
+
+	var recvTyp ast.Expr // rewritten receiver type; valid if != nil
+	if recvPar != nil && len(recvPar.List) > 0 {
+		// collect generic receiver type parameters, if any
+		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
+		// - the receiver specification acts as local declaration for its type parameters, which may be blank
+		_, rname, rparams := check.unpackRecv(recvPar.List[0].Type, true)
+		if len(rparams) > 0 {
+			// Blank identifiers don't get declared and regular type-checking of the instantiated
+			// parameterized receiver type expression fails in Checker.collectParams of receiver.
+			// Identify blank type parameters and substitute each with a unique new identifier named
+			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
+			// name.
+			var smap map[*ast.Ident]*ast.Ident // substitution map from "_" to "n_" identifiers
+			for i, p := range rparams {
+				if p.Name == "_" {
+					new := *p
+					new.Name = fmt.Sprintf("%d_", i)
+					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
+					if smap == nil {
+						smap = make(map[*ast.Ident]*ast.Ident)
+					}
+					smap[p] = &new
+				}
+			}
+			if smap != nil {
+				// blank identifiers were found => use rewritten receiver type
+				recvTyp = isubst(recvPar.List[0].Type, smap)
+			}
+			sig.rparams = bindTParams(check.declareTypeParams(nil, rparams))
+			// determine receiver type to get its type parameters
+			// and the respective type parameter bounds
+			var recvTParams []*TypeParam
+			if rname != nil {
+				// recv should be a Named type (otherwise an error is reported elsewhere)
+				// Also: Don't report an error via genericType since it will be reported
+				//       again when we type-check the signature.
+				// TODO(gri) maybe the receiver should be marked as invalid instead?
+				if recv := asNamed(check.genericType(rname, false)); recv != nil {
+					recvTParams = recv.TParams().list()
+				}
+			}
+			// provide type parameter bounds
+			// - only do this if we have the right number (otherwise an error is reported elsewhere)
+			if sig.RParams().Len() == len(recvTParams) {
+				// We have a list of *TypeNames but we need a list of Types.
+				list := make([]Type, sig.RParams().Len())
+				for i, t := range sig.RParams().list() {
+					list[i] = t
+				}
+				smap := makeSubstMap(recvTParams, list)
+				for i, tpar := range sig.RParams().list() {
+					bound := recvTParams[i].bound
+					// bound is (possibly) parameterized in the context of the
+					// receiver type declaration. Substitute parameters for the
+					// current context.
+					// TODO(gri) should we assume now that bounds always exist?
+					//           (no bound == empty interface)
+					if bound != nil {
+						bound = check.subst(tpar.obj.pos, bound, smap, nil)
+						tpar.bound = bound
+					}
+				}
+			}
+		}
+	}
+
+	if tparams := typeparams.Get(ftyp); tparams != nil {
+		sig.tparams = check.collectTypeParams(tparams)
+		// Always type-check method type parameters but complain that they are not allowed.
+		// (A separate check is needed when type-checking interface method signatures because
+		// they don't have a receiver specification.)
+		if recvPar != nil {
+			check.errorf(tparams, _Todo, "methods cannot have type parameters")
+		}
+	}
+
+	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
+	// declarations and then squash that scope into the parent scope (and report any redeclarations at
+	// that time).
+	scope := NewScope(check.scope, token.NoPos, token.NoPos, "function body (temp. scope)")
+	recvList, _ := check.collectParams(scope, recvPar, recvTyp, false) // use rewritten receiver type, if any
+	params, variadic := check.collectParams(scope, ftyp.Params, nil, true)
+	results, _ := check.collectParams(scope, ftyp.Results, nil, false)
+	scope.squash(func(obj, alt Object) {
+		check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
+		check.reportAltDecl(alt)
+	})
+
+	if recvPar != nil {
+		// recv parameter list present (may be empty)
+		// spec: "The receiver is specified via an extra parameter section preceding the
+		// method name. That parameter section must declare a single parameter, the receiver."
+		var recv *Var
+		switch len(recvList) {
+		case 0:
+			// error reported by resolver
+			recv = NewParam(0, nil, "", Typ[Invalid]) // ignore recv below
+		default:
+			// more than one receiver
+			check.error(recvList[len(recvList)-1], _BadRecv, "method must have exactly one receiver")
+			fallthrough // continue with first receiver
+		case 1:
+			recv = recvList[0]
+		}
+
+		// TODO(gri) We should delay rtyp expansion to when we actually need the
+		//           receiver; thus all checks here should be delayed to later.
+		rtyp, _ := deref(recv.typ)
+
+		// spec: "The receiver type must be of the form T or *T where T is a type name."
+		// (ignore invalid types - error was reported before)
+		if rtyp != Typ[Invalid] {
+			var err string
+			switch T := rtyp.(type) {
+			case *Named:
+				T.expand(nil)
+				// spec: "The type denoted by T is called the receiver base type; it must not
+				// be a pointer or interface type and it must be declared in the same package
+				// as the method."
+				if T.obj.pkg != check.pkg {
+					err = "type not defined in this package"
+				} else {
+					// The underlying type of a receiver base type can be a type parameter;
+					// e.g. for methods with a generic receiver T[P] with type T[P any] P.
+					underIs(T, func(u Type) bool {
+						switch u := u.(type) {
+						case *Basic:
+							// unsafe.Pointer is treated like a regular pointer
+							if u.kind == UnsafePointer {
+								err = "unsafe.Pointer"
+								return false
+							}
+						case *Pointer, *Interface:
+							err = "pointer or interface type"
+							return false
+						}
+						return true
+					})
+				}
+			case *Basic:
+				err = "basic or unnamed type"
+			default:
+				check.errorf(recv, _InvalidRecv, "invalid receiver type %s", recv.typ)
+			}
+			if err != "" {
+				check.errorf(recv, _InvalidRecv, "invalid receiver type %s (%s)", recv.typ, err)
+				// ok to continue
+			}
+		}
+		sig.recv = recv
+	}
+
+	sig.params = NewTuple(params...)
+	sig.results = NewTuple(results...)
+	sig.variadic = variadic
+}
+
+// collectParams declares the parameters of list in scope and returns the corresponding
+// variable list. If type0 != nil, it is used instead of the first type in list.
+func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, type0 ast.Expr, variadicOk bool) (params []*Var, variadic bool) {
+	if list == nil {
+		return
+	}
+
+	var named, anonymous bool
+	for i, field := range list.List {
+		ftype := field.Type
+		if i == 0 && type0 != nil {
+			ftype = type0
+		}
+		if t, _ := ftype.(*ast.Ellipsis); t != nil {
+			ftype = t.Elt
+			if variadicOk && i == len(list.List)-1 && len(field.Names) <= 1 {
+				variadic = true
+			} else {
+				check.softErrorf(t, _MisplacedDotDotDot, "can only use ... with final parameter in list")
+				// ignore ... and continue
+			}
+		}
+		typ := check.varType(ftype)
+		// The parser ensures that f.Tag is nil and we don't
+		// care if a constructed AST contains a non-nil tag.
+		if len(field.Names) > 0 {
+			// named parameter
+			for _, name := range field.Names {
+				if name.Name == "" {
+					check.invalidAST(name, "anonymous parameter")
+					// ok to continue
+				}
+				par := NewParam(name.Pos(), check.pkg, name.Name, typ)
+				check.declare(scope, name, par, scope.pos)
+				params = append(params, par)
+			}
+			named = true
+		} else {
+			// anonymous parameter
+			par := NewParam(ftype.Pos(), check.pkg, "", typ)
+			check.recordImplicit(field, par)
+			params = append(params, par)
+			anonymous = true
+		}
+	}
+
+	if named && anonymous {
+		check.invalidAST(list, "list contains both named and anonymous parameters")
+		// ok to continue
+	}
+
+	// For a variadic function, change the last parameter's type from T to []T.
+	// Since we type-checked T rather than ...T, we also need to retro-actively
+	// record the type for ...T.
+	if variadic {
+		last := params[len(params)-1]
+		last.typ = &Slice{elem: last.typ}
+		check.recordTypeAndValue(list.List[len(list.List)-1].Type, typexpr, last.typ, nil)
+	}
+
+	return
+}
+
+// isubst returns an x with identifiers substituted per the substitution map smap.
+// isubst only handles the case of (valid) method receiver type expressions correctly.
+func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
+	switch n := x.(type) {
+	case *ast.Ident:
+		if alt := smap[n]; alt != nil {
+			return alt
+		}
+	case *ast.StarExpr:
+		X := isubst(n.X, smap)
+		if X != n.X {
+			new := *n
+			new.X = X
+			return &new
+		}
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(x)
+		var newIndexes []ast.Expr
+		for i, index := range ix.Indices {
+			new := isubst(index, smap)
+			if new != index {
+				if newIndexes == nil {
+					newIndexes = make([]ast.Expr, len(ix.Indices))
+					copy(newIndexes, ix.Indices)
+				}
+				newIndexes[i] = new
+			}
+		}
+		if newIndexes != nil {
+			return typeparams.PackIndexExpr(ix.X, ix.Lbrack, newIndexes, ix.Rbrack)
+		}
+	case *ast.ParenExpr:
+		return isubst(n.X, smap) // no need to keep parentheses
+	default:
+		// Other receiver type expressions are invalid.
+		// It's fine to ignore those here as they will
+		// be checked elsewhere.
+	}
+	return x
+}
diff --git a/src/go/types/sizeof_test.go b/src/go/types/sizeof_test.go
index 5a9d07ca41802a9edbf292a9b0f0d738e86d268f..c2f5b3c3331e83a43642a7c1ae882830ee5af425 100644
--- a/src/go/types/sizeof_test.go
+++ b/src/go/types/sizeof_test.go
@@ -25,15 +25,14 @@ func TestSizeof(t *testing.T) {
 		{Struct{}, 24, 48},
 		{Pointer{}, 8, 16},
 		{Tuple{}, 12, 24},
-		{Signature{}, 44, 88},
-		{_Sum{}, 12, 24},
-		{Interface{}, 60, 120},
+		{Signature{}, 28, 56},
+		{Union{}, 16, 32},
+		{Interface{}, 40, 80},
 		{Map{}, 16, 32},
 		{Chan{}, 12, 24},
-		{Named{}, 64, 128},
-		{_TypeParam{}, 28, 48},
-		{instance{}, 44, 88},
-		{bottom{}, 0, 0},
+		{Named{}, 72, 136},
+		{TypeParam{}, 28, 48},
+		{term{}, 12, 24},
 		{top{}, 0, 0},
 
 		// Objects
@@ -47,8 +46,9 @@ func TestSizeof(t *testing.T) {
 		{Nil{}, 40, 72},
 
 		// Misc
-		{Scope{}, 40, 80},
+		{Scope{}, 44, 88},
 		{Package{}, 40, 80},
+		{_TypeSet{}, 28, 56},
 	}
 	for _, test := range tests {
 		got := reflect.TypeOf(test.val).Size()
diff --git a/src/go/types/sizes.go b/src/go/types/sizes.go
index 67052bb816e0935167cd0e204731a247e2a6a50b..4c85bfe057f8ddd7c37858aac7df59c29c3ba22c 100644
--- a/src/go/types/sizes.go
+++ b/src/go/types/sizes.go
@@ -48,7 +48,7 @@ type StdSizes struct {
 func (s *StdSizes) Alignof(T Type) int64 {
 	// For arrays and structs, alignment is defined in terms
 	// of alignment of the elements and fields, respectively.
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Array:
 		// spec: "For a variable x of array type: unsafe.Alignof(x)
 		// is the same as unsafe.Alignof(x[0]), but at least 1."
@@ -73,6 +73,8 @@ func (s *StdSizes) Alignof(T Type) int64 {
 		if t.Info()&IsString != 0 {
 			return s.WordSize
 		}
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	a := s.Sizeof(T) // may be 0
 	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
@@ -118,7 +120,7 @@ var basicSizes = [...]byte{
 }
 
 func (s *StdSizes) Sizeof(T Type) int64 {
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		assert(isTyped(T))
 		k := t.kind
@@ -148,10 +150,10 @@ func (s *StdSizes) Sizeof(T Type) int64 {
 		}
 		offsets := s.Offsetsof(t.fields)
 		return offsets[n-1] + s.Sizeof(t.fields[n-1].typ)
-	case *_Sum:
-		panic("Sizeof unimplemented for type sum")
 	case *Interface:
 		return s.WordSize * 2
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	return s.WordSize // catch-all
 }
diff --git a/src/go/types/slice.go b/src/go/types/slice.go
new file mode 100644
index 0000000000000000000000000000000000000000..debdd81586cce0fb39c4df553250f8b952c286bb
--- /dev/null
+++ b/src/go/types/slice.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Slice represents a slice type.
+type Slice struct {
+	elem Type
+}
+
+// NewSlice returns a new slice type for the given element type.
+func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
+
+// Elem returns the element type of slice s.
+func (s *Slice) Elem() Type { return s.elem }
+
+func (t *Slice) Underlying() Type { return t }
+func (t *Slice) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/stdlib_test.go b/src/go/types/stdlib_test.go
index d86a77a110f7a7f9f68083e2c8d1545b6c6adfd9..3eb7519a91af06d2d27f8c19fdb1b4bb358e0ea9 100644
--- a/src/go/types/stdlib_test.go
+++ b/src/go/types/stdlib_test.go
@@ -140,8 +140,7 @@ func testTestDir(t *testing.T, path string, ignore ...string) {
 		// parse and type-check file
 		file, err := parser.ParseFile(fset, filename, nil, 0)
 		if err == nil {
-			conf := Config{Importer: stdLibImporter}
-			SetGoVersion(&conf, goVersion)
+			conf := Config{GoVersion: goVersion, Importer: stdLibImporter}
 			_, err = conf.Check(filename, fset, []*ast.File{file}, nil)
 		}
 
diff --git a/src/go/types/stmt.go b/src/go/types/stmt.go
index 47f6dcfbd1ce8f6f5b25f0da36a2ef144afb1feb..fd6eba2deb26f5bbaa55a41340f196a9ff55dd89 100644
--- a/src/go/types/stmt.go
+++ b/src/go/types/stmt.go
@@ -15,7 +15,7 @@ import (
 
 func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body *ast.BlockStmt, iota constant.Value) {
 	if check.conf.IgnoreFuncBodies {
-		panic("internal error: function body not ignored")
+		panic("function body not ignored")
 	}
 
 	if trace {
@@ -65,7 +65,8 @@ func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body
 
 func (check *Checker) usage(scope *Scope) {
 	var unused []*Var
-	for _, elem := range scope.elems {
+	for name, elem := range scope.elems {
+		elem = resolve(name, elem)
 		if v, _ := elem.(*Var); v != nil && !v.used {
 			unused = append(unused, v)
 		}
@@ -264,7 +265,7 @@ L:
 			// look for duplicate types for a given value
 			// (quadratic algorithm, but these lists tend to be very short)
 			for _, vt := range seen[val] {
-				if check.identical(v.typ, vt.typ) {
+				if Identical(v.typ, vt.typ) {
 					check.errorf(&v, _DuplicateCase, "duplicate case %s in expression switch", &v)
 					check.error(atPos(vt.pos), _DuplicateCase, "\tprevious case") // secondary error, \t indented
 					continue L
@@ -288,7 +289,7 @@ L:
 		// look for duplicate types
 		// (quadratic algorithm, but type switches tend to be reasonably small)
 		for t, other := range seen {
-			if T == nil && t == nil || T != nil && t != nil && check.identical(T, t) {
+			if T == nil && t == nil || T != nil && t != nil && Identical(T, t) {
 				// talk about "case" rather than "type" because of nil case
 				Ts := "nil"
 				if T != nil {
@@ -360,25 +361,33 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		check.errorf(&x, code, "%s %s", &x, msg)
 
 	case *ast.SendStmt:
-		var ch, x operand
+		var ch, val operand
 		check.expr(&ch, s.Chan)
-		check.expr(&x, s.Value)
-		if ch.mode == invalid || x.mode == invalid {
+		check.expr(&val, s.Value)
+		if ch.mode == invalid || val.mode == invalid {
 			return
 		}
-
-		tch := asChan(ch.typ)
-		if tch == nil {
-			check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to non-chan type %s", ch.typ)
-			return
-		}
-
-		if tch.dir == RecvOnly {
-			check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to receive-only type %s", tch)
+		var elem Type
+		if !underIs(ch.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to non-channel %s", &ch)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to receive-only channel %s", &ch)
+				return false
+			}
+			if elem != nil && !Identical(uch.elem, elem) {
+				check.invalidOp(inNode(s, s.Arrow), _Todo, "channels of %s must have the same element type", &ch)
+				return false
+			}
+			elem = uch.elem
+			return true
+		}) {
 			return
 		}
-
-		check.assignment(&x, tch.elem, "send")
+		check.assignment(&val, elem, "send")
 
 	case *ast.IncDecStmt:
 		var op token.Token
@@ -774,9 +783,9 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		// determine key/value types
 		var key, val Type
 		if x.mode != invalid {
+			// Ranging over a type parameter is permitted if it has a structural type.
 			typ := optype(x.typ)
 			if _, ok := typ.(*Chan); ok && s.Value != nil {
-				// TODO(gri) this also needs to happen for channels in generic variables
 				check.softErrorf(atPos(s.Value.Pos()), _InvalidIterVar, "range over %s permits only one iteration variable", &x)
 				// ok to continue
 			}
@@ -890,7 +899,7 @@ func isVarName(x ast.Expr) bool {
 // variables are used or present; this matters if we range over a generic
 // type where not all keys or values are of the same type.
 func rangeKeyVal(typ Type, wantKey, wantVal bool) (Type, Type, string) {
-	switch typ := typ.(type) {
+	switch typ := arrayPtrDeref(typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			return Typ[Int], universeRune, "" // use 'rune' name
@@ -899,44 +908,17 @@ func rangeKeyVal(typ Type, wantKey, wantVal bool) (Type, Type, string) {
 		return Typ[Int], typ.elem, ""
 	case *Slice:
 		return Typ[Int], typ.elem, ""
-	case *Pointer:
-		if typ := asArray(typ.base); typ != nil {
-			return Typ[Int], typ.elem, ""
-		}
 	case *Map:
 		return typ.key, typ.elem, ""
 	case *Chan:
 		var msg string
 		if typ.dir == SendOnly {
-			msg = "send-only channel"
+			msg = "receive from send-only channel"
 		}
 		return typ.elem, Typ[Invalid], msg
-	case *_Sum:
-		first := true
-		var key, val Type
-		var msg string
-		typ.is(func(t Type) bool {
-			k, v, m := rangeKeyVal(under(t), wantKey, wantVal)
-			if k == nil || m != "" {
-				key, val, msg = k, v, m
-				return false
-			}
-			if first {
-				key, val, msg = k, v, m
-				first = false
-				return true
-			}
-			if wantKey && !Identical(key, k) {
-				key, val, msg = nil, nil, "all possible values must have the same key type"
-				return false
-			}
-			if wantVal && !Identical(val, v) {
-				key, val, msg = nil, nil, "all possible values must have the same element type"
-				return false
-			}
-			return true
-		})
-		return key, val, msg
+	case *top:
+		// we have a type parameter with no structural type
+		return nil, nil, "no structural type"
 	}
 	return nil, nil, ""
 }
diff --git a/src/go/types/struct.go b/src/go/types/struct.go
new file mode 100644
index 0000000000000000000000000000000000000000..48b07346dc30cc7c3ba3038ca7b1a780bd41829d
--- /dev/null
+++ b/src/go/types/struct.go
@@ -0,0 +1,202 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+	"strconv"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Struct represents a struct type.
+type Struct struct {
+	fields []*Var
+	tags   []string // field tags; nil if there are no tags
+}
+
+// NewStruct returns a new struct with the given fields and corresponding field tags.
+// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
+// only as long as required to hold the tag with the largest index i. Consequently,
+// if no field has a tag, tags may be nil.
+func NewStruct(fields []*Var, tags []string) *Struct {
+	var fset objset
+	for _, f := range fields {
+		if f.name != "_" && fset.insert(f) != nil {
+			panic("multiple fields with the same name")
+		}
+	}
+	if len(tags) > len(fields) {
+		panic("more tags than fields")
+	}
+	return &Struct{fields: fields, tags: tags}
+}
+
+// NumFields returns the number of fields in the struct (including blank and embedded fields).
+func (s *Struct) NumFields() int { return len(s.fields) }
+
+// Field returns the i'th field for 0 <= i < NumFields().
+func (s *Struct) Field(i int) *Var { return s.fields[i] }
+
+// Tag returns the i'th field tag for 0 <= i < NumFields().
+func (s *Struct) Tag(i int) string {
+	if i < len(s.tags) {
+		return s.tags[i]
+	}
+	return ""
+}
+
+func (t *Struct) Underlying() Type { return t }
+func (t *Struct) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) structType(styp *Struct, e *ast.StructType) {
+	list := e.Fields
+	if list == nil {
+		return
+	}
+
+	// struct fields and tags
+	var fields []*Var
+	var tags []string
+
+	// for double-declaration checks
+	var fset objset
+
+	// current field typ and tag
+	var typ Type
+	var tag string
+	add := func(ident *ast.Ident, embedded bool, pos token.Pos) {
+		if tag != "" && tags == nil {
+			tags = make([]string, len(fields))
+		}
+		if tags != nil {
+			tags = append(tags, tag)
+		}
+
+		name := ident.Name
+		fld := NewField(pos, check.pkg, name, typ, embedded)
+		// spec: "Within a struct, non-blank field names must be unique."
+		if name == "_" || check.declareInSet(&fset, pos, fld) {
+			fields = append(fields, fld)
+			check.recordDef(ident, fld)
+		}
+	}
+
+	// addInvalid adds an embedded field of invalid type to the struct for
+	// fields with errors; this keeps the number of struct fields in sync
+	// with the source as long as the fields are _ or have different names
+	// (issue #25627).
+	addInvalid := func(ident *ast.Ident, pos token.Pos) {
+		typ = Typ[Invalid]
+		tag = ""
+		add(ident, true, pos)
+	}
+
+	for _, f := range list.List {
+		typ = check.varType(f.Type)
+		tag = check.tag(f.Tag)
+		if len(f.Names) > 0 {
+			// named fields
+			for _, name := range f.Names {
+				add(name, false, name.Pos())
+			}
+		} else {
+			// embedded field
+			// spec: "An embedded type must be specified as a type name T or as a
+			// pointer to a non-interface type name *T, and T itself may not be a
+			// pointer type."
+			pos := f.Type.Pos()
+			name := embeddedFieldIdent(f.Type)
+			if name == nil {
+				// TODO(rFindley): using invalidAST here causes test failures (all
+				//                 errors should have codes). Clean this up.
+				check.errorf(f.Type, _Todo, "invalid AST: embedded field type %s has no name", f.Type)
+				name = ast.NewIdent("_")
+				name.NamePos = pos
+				addInvalid(name, pos)
+				continue
+			}
+			add(name, true, pos)
+
+			// Because we have a name, typ must be of the form T or *T, where T is the name
+			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
+			// We must delay this check to the end because we don't want to instantiate
+			// (via under(t)) a possibly incomplete type.
+
+			// for use in the closure below
+			embeddedTyp := typ
+			embeddedPos := f.Type
+
+			check.later(func() {
+				t, isPtr := deref(embeddedTyp)
+				switch t := under(t).(type) {
+				case *Basic:
+					if t == Typ[Invalid] {
+						// error was reported before
+						return
+					}
+					// unsafe.Pointer is treated like a regular pointer
+					if t.kind == UnsafePointer {
+						check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be unsafe.Pointer")
+					}
+				case *Pointer:
+					check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer")
+				case *TypeParam:
+					check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a (pointer to a) type parameter")
+				case *Interface:
+					if isPtr {
+						check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer to an interface")
+					}
+				}
+			})
+		}
+	}
+
+	styp.fields = fields
+	styp.tags = tags
+}
+
+func embeddedFieldIdent(e ast.Expr) *ast.Ident {
+	switch e := e.(type) {
+	case *ast.Ident:
+		return e
+	case *ast.StarExpr:
+		// *T is valid, but **T is not
+		if _, ok := e.X.(*ast.StarExpr); !ok {
+			return embeddedFieldIdent(e.X)
+		}
+	case *ast.SelectorExpr:
+		return e.Sel
+	case *ast.IndexExpr:
+		return embeddedFieldIdent(e.X)
+	}
+	return nil // invalid embedded field
+}
+
+func (check *Checker) declareInSet(oset *objset, pos token.Pos, obj Object) bool {
+	if alt := oset.insert(obj); alt != nil {
+		check.errorf(atPos(pos), _DuplicateDecl, "%s redeclared", obj.Name())
+		check.reportAltDecl(alt)
+		return false
+	}
+	return true
+}
+
+func (check *Checker) tag(t *ast.BasicLit) string {
+	if t != nil {
+		if t.Kind == token.STRING {
+			if val, err := strconv.Unquote(t.Value); err == nil {
+				return val
+			}
+		}
+		check.invalidAST(t, "incorrect tag syntax: %q", t.Value)
+	}
+	return ""
+}
diff --git a/src/go/types/subst.go b/src/go/types/subst.go
index 931375f1f2b9873304975e85b5eb78991273e002..8b8d6fb82a783dae578b78f701c1856b80442a47 100644
--- a/src/go/types/subst.go
+++ b/src/go/types/subst.go
@@ -2,218 +2,49 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements instantiation of generic types
-// through substitution of type parameters by actual
-// types.
+// This file implements type parameter substitution.
 
 package types
 
 import (
 	"bytes"
-	"fmt"
 	"go/token"
 )
 
 // TODO(rFindley) decide error codes for the errors in this file, and check
 //                if error spans can be improved
 
-type substMap struct {
-	// The targs field is currently needed for *Named type substitution.
-	// TODO(gri) rewrite that code, get rid of this field, and make this
-	//           struct just the map (proj)
-	targs []Type
-	proj  map[*_TypeParam]Type
-}
+type substMap map[*TypeParam]Type
 
 // makeSubstMap creates a new substitution map mapping tpars[i] to targs[i].
 // If targs[i] is nil, tpars[i] is not substituted.
-func makeSubstMap(tpars []*TypeName, targs []Type) *substMap {
+func makeSubstMap(tpars []*TypeParam, targs []Type) substMap {
 	assert(len(tpars) == len(targs))
-	proj := make(map[*_TypeParam]Type, len(tpars))
+	proj := make(substMap, len(tpars))
 	for i, tpar := range tpars {
-		// We must expand type arguments otherwise *instance
-		// types end up as components in composite types.
-		// TODO(gri) explain why this causes problems, if it does
-		targ := expand(targs[i]) // possibly nil
-		targs[i] = targ
-		proj[tpar.typ.(*_TypeParam)] = targ
+		proj[tpar] = targs[i]
 	}
-	return &substMap{targs, proj}
-}
-
-func (m *substMap) String() string {
-	return fmt.Sprintf("%s", m.proj)
+	return proj
 }
 
-func (m *substMap) empty() bool {
-	return len(m.proj) == 0
+func (m substMap) empty() bool {
+	return len(m) == 0
 }
 
-func (m *substMap) lookup(tpar *_TypeParam) Type {
-	if t := m.proj[tpar]; t != nil {
+func (m substMap) lookup(tpar *TypeParam) Type {
+	if t := m[tpar]; t != nil {
 		return t
 	}
 	return tpar
 }
 
-func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist []token.Pos) (res Type) {
-	if trace {
-		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
-		check.indent++
-		defer func() {
-			check.indent--
-			var under Type
-			if res != nil {
-				// Calling under() here may lead to endless instantiations.
-				// Test case: type T[P any] T[P]
-				// TODO(gri) investigate if that's a bug or to be expected.
-				under = res.Underlying()
-			}
-			check.trace(pos, "=> %s (under = %s)", res, under)
-		}()
-	}
-
-	assert(len(poslist) <= len(targs))
-
-	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
-	var tparams []*TypeName
-	switch t := typ.(type) {
-	case *Named:
-		tparams = t.tparams
-	case *Signature:
-		tparams = t.tparams
-		defer func() {
-			// If we had an unexpected failure somewhere don't panic below when
-			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
-			// is returned.
-			if _, ok := res.(*Signature); !ok {
-				return
-			}
-			// If the signature doesn't use its type parameters, subst
-			// will not make a copy. In that case, make a copy now (so
-			// we can set tparams to nil w/o causing side-effects).
-			if t == res {
-				copy := *t
-				res = ©
-			}
-			// After instantiating a generic signature, it is not generic
-			// anymore; we need to set tparams to nil.
-			res.(*Signature).tparams = nil
-		}()
-
-	default:
-		check.dump("%v: cannot instantiate %v", pos, typ)
-		unreachable() // only defined types and (defined) functions can be generic
-	}
-
-	// the number of supplied types must match the number of type parameters
-	if len(targs) != len(tparams) {
-		// TODO(gri) provide better error message
-		check.errorf(atPos(pos), _Todo, "got %d arguments but %d type parameters", len(targs), len(tparams))
-		return Typ[Invalid]
-	}
-
-	if len(tparams) == 0 {
-		return typ // nothing to do (minor optimization)
-	}
-
-	smap := makeSubstMap(tparams, targs)
-
-	// check bounds
-	for i, tname := range tparams {
-		tpar := tname.typ.(*_TypeParam)
-		iface := tpar.Bound()
-		if iface.Empty() {
-			continue // no type bound
-		}
-
-		targ := targs[i]
-
-		// best position for error reporting
-		pos := pos
-		if i < len(poslist) {
-			pos = poslist[i]
-		}
-
-		// The type parameter bound is parameterized with the same type parameters
-		// as the instantiated type; before we can use it for bounds checking we
-		// need to instantiate it with the type arguments with which we instantiate
-		// the parameterized type.
-		iface = check.subst(pos, iface, smap).(*Interface)
-
-		// targ must implement iface (methods)
-		// - check only if we have methods
-		check.completeInterface(token.NoPos, iface)
-		if len(iface.allMethods) > 0 {
-			// If the type argument is a pointer to a type parameter, the type argument's
-			// method set is empty.
-			// TODO(gri) is this what we want? (spec question)
-			if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
-				check.errorf(atPos(pos), 0, "%s has no methods", targ)
-				break
-			}
-			if m, wrong := check.missingMethod(targ, iface, true); m != nil {
-				// TODO(gri) needs to print updated name to avoid major confusion in error message!
-				//           (print warning for now)
-				// Old warning:
-				// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
-				if m.name == "==" {
-					// We don't want to report "missing method ==".
-					check.softErrorf(atPos(pos), 0, "%s does not satisfy comparable", targ)
-				} else if wrong != nil {
-					// TODO(gri) This can still report uninstantiated types which makes the error message
-					//           more difficult to read then necessary.
-					// TODO(rFindley) should this use parentheses rather than ':' for qualification?
-					check.softErrorf(atPos(pos), _Todo,
-						"%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
-						targ, tpar.bound, wrong, m,
-					)
-				} else {
-					check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
-				}
-				break
-			}
-		}
-
-		// targ's underlying type must also be one of the interface types listed, if any
-		if iface.allTypes == nil {
-			continue // nothing to do
-		}
-
-		// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
-		// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
-		if targ := asTypeParam(targ); targ != nil {
-			targBound := targ.Bound()
-			if targBound.allTypes == nil {
-				check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
-				break
-			}
-			for _, t := range unpackType(targBound.allTypes) {
-				if !iface.isSatisfiedBy(t) {
-					// TODO(gri) match this error message with the one below (or vice versa)
-					check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, t, iface.allTypes)
-					break
-				}
-			}
-			break
-		}
-
-		// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
-		if !iface.isSatisfiedBy(targ) {
-			check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s or %s not found in %s)", targ, tpar.bound, targ, under(targ), iface.allTypes)
-			break
-		}
-	}
-
-	return check.subst(pos, typ, smap)
-}
-
-// subst returns the type typ with its type parameters tpars replaced by
-// the corresponding type arguments targs, recursively.
-// subst is functional in the sense that it doesn't modify the incoming
-// type. If a substitution took place, the result type is different from
-// from the incoming type.
-func (check *Checker) subst(pos token.Pos, typ Type, smap *substMap) Type {
+// subst returns the type typ with its type parameters tpars replaced by the
+// corresponding type arguments targs, recursively. subst is pure in the sense
+// that it doesn't modify the incoming type. If a substitution took place, the
+// result type is different from from the incoming type.
+//
+// If the given typMap is non-nil, it is used in lieu of check.typMap.
+func (check *Checker) subst(pos token.Pos, typ Type, smap substMap, typMap map[string]*Named) Type {
 	if smap.empty() {
 		return typ
 	}
@@ -222,20 +53,38 @@ func (check *Checker) subst(pos token.Pos, typ Type, smap *substMap) Type {
 	switch t := typ.(type) {
 	case *Basic:
 		return typ // nothing to do
-	case *_TypeParam:
+	case *TypeParam:
 		return smap.lookup(t)
 	}
 
 	// general case
-	subst := subster{check, pos, make(map[Type]Type), smap}
+	var subst subster
+	subst.pos = pos
+	subst.smap = smap
+
+	if check != nil {
+		subst.check = check
+		if typMap == nil {
+			typMap = check.typMap
+		}
+	}
+	if typMap == nil {
+		// If we don't have a *Checker and its global type map,
+		// use a local version. Besides avoiding duplicate work,
+		// the type map prevents infinite recursive substitution
+		// for recursive types (example: type T[P any] *T[P]).
+		typMap = make(map[string]*Named)
+	}
+	subst.typMap = typMap
+
 	return subst.typ(typ)
 }
 
 type subster struct {
-	check *Checker
-	pos   token.Pos
-	cache map[Type]Type
-	smap  *substMap
+	pos    token.Pos
+	smap   substMap
+	check  *Checker // nil if called via Instantiate
+	typMap map[string]*Named
 }
 
 func (subst *subster) typ(typ Type) Type {
@@ -244,7 +93,7 @@ func (subst *subster) typ(typ Type) Type {
 		// Call typOrNil if it's possible that typ is nil.
 		panic("nil typ")
 
-	case *Basic, *bottom, *top:
+	case *Basic, *top:
 		// nothing to do
 
 	case *Array:
@@ -293,26 +142,20 @@ func (subst *subster) typ(typ Type) Type {
 			}
 		}
 
-	case *_Sum:
-		types, copied := subst.typeList(t.types)
+	case *Union:
+		terms, copied := subst.termlist(t.terms)
 		if copied {
-			// Don't do it manually, with a Sum literal: the new
-			// types list may not be unique and NewSum may remove
-			// duplicates.
-			return _NewSum(types)
+			// term list substitution may introduce duplicate terms (unlikely but possible).
+			// This is ok; lazy type set computation will determine the actual type set
+			// in normal form.
+			return &Union{terms, nil}
 		}
 
 	case *Interface:
 		methods, mcopied := subst.funcList(t.methods)
-		types := t.types
-		if t.types != nil {
-			types = subst.typ(t.types)
-		}
 		embeddeds, ecopied := subst.typeList(t.embeddeds)
-		if mcopied || types != t.types || ecopied {
-			iface := &Interface{methods: methods, types: types, embeddeds: embeddeds}
-			subst.check.posMap[iface] = subst.check.posMap[t] // satisfy completeInterface requirement
-			subst.check.completeInterface(token.NoPos, iface)
+		if mcopied || ecopied {
+			iface := &Interface{methods: methods, embeddeds: embeddeds, complete: t.complete}
 			return iface
 		}
 
@@ -330,85 +173,82 @@ func (subst *subster) typ(typ Type) Type {
 		}
 
 	case *Named:
-		subst.check.indent++
-		defer func() {
-			subst.check.indent--
-		}()
-		dump := func(format string, args ...interface{}) {
-			if trace {
+		// dump is for debugging
+		dump := func(string, ...interface{}) {}
+		if subst.check != nil && trace {
+			subst.check.indent++
+			defer func() {
+				subst.check.indent--
+			}()
+			dump = func(format string, args ...interface{}) {
 				subst.check.trace(subst.pos, format, args...)
 			}
 		}
 
-		if t.tparams == nil {
+		if t.TParams().Len() == 0 {
 			dump(">>> %s is not parameterized", t)
 			return t // type is not parameterized
 		}
 
-		var newTargs []Type
-
-		if len(t.targs) > 0 {
-			// already instantiated
-			dump(">>> %s already instantiated", t)
-			assert(len(t.targs) == len(t.tparams))
-			// For each (existing) type argument targ, determine if it needs
-			// to be substituted; i.e., if it is or contains a type parameter
-			// that has a type argument for it.
-			for i, targ := range t.targs {
-				dump(">>> %d targ = %s", i, targ)
-				newTarg := subst.typ(targ)
-				if newTarg != targ {
-					dump(">>> substituted %d targ %s => %s", i, targ, newTarg)
-					if newTargs == nil {
-						newTargs = make([]Type, len(t.tparams))
-						copy(newTargs, t.targs)
-					}
-					newTargs[i] = newTarg
+		var newTArgs []Type
+		assert(t.targs.Len() == t.TParams().Len())
+
+		// already instantiated
+		dump(">>> %s already instantiated", t)
+		// For each (existing) type argument targ, determine if it needs
+		// to be substituted; i.e., if it is or contains a type parameter
+		// that has a type argument for it.
+		for i, targ := range t.targs.list() {
+			dump(">>> %d targ = %s", i, targ)
+			new_targ := subst.typ(targ)
+			if new_targ != targ {
+				dump(">>> substituted %d targ %s => %s", i, targ, new_targ)
+				if newTArgs == nil {
+					newTArgs = make([]Type, t.TParams().Len())
+					copy(newTArgs, t.targs.list())
 				}
+				newTArgs[i] = new_targ
 			}
+		}
 
-			if newTargs == nil {
-				dump(">>> nothing to substitute in %s", t)
-				return t // nothing to substitute
-			}
-		} else {
-			// not yet instantiated
-			dump(">>> first instantiation of %s", t)
-			// TODO(rFindley) can we instead subst the tparam types here?
-			newTargs = subst.smap.targs
+		if newTArgs == nil {
+			dump(">>> nothing to substitute in %s", t)
+			return t // nothing to substitute
 		}
 
 		// before creating a new named type, check if we have this one already
-		h := instantiatedHash(t, newTargs)
+		h := instantiatedHash(t, newTArgs)
 		dump(">>> new type hash: %s", h)
-		if named, found := subst.check.typMap[h]; found {
+		if named, found := subst.typMap[h]; found {
 			dump(">>> found %s", named)
-			subst.cache[t] = named
 			return named
 		}
 
-		// create a new named type and populate caches to avoid endless recursion
+		// Create a new named type and populate typMap to avoid endless recursion.
+		// The position used here is irrelevant because validation only occurs on t
+		// (we don't call validType on named), but we use subst.pos to help with
+		// debugging.
 		tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil)
-		named := subst.check.newNamed(tname, t.underlying, t.methods) // method signatures are updated lazily
-		named.tparams = t.tparams                                     // new type is still parameterized
-		named.targs = newTargs
-		subst.check.typMap[h] = named
-		subst.cache[t] = named
+		t.load()
+		// It's ok to provide a nil *Checker because the newly created type
+		// doesn't need to be (lazily) expanded; it's expanded below.
+		named := (*Checker)(nil).newNamed(tname, t.orig, nil, t.tparams, t.methods) // t is loaded, so tparams and methods are available
+		named.targs = &TypeList{newTArgs}
+		subst.typMap[h] = named
+		t.expand(subst.typMap) // must happen after typMap update to avoid infinite recursion
 
 		// do the substitution
-		dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTargs)
+		dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTArgs)
 		named.underlying = subst.typOrNil(t.underlying)
-		named.orig = named.underlying // for cycle detection (Checker.validType)
+		dump(">>> underlying: %v", named.underlying)
+		assert(named.underlying != nil)
+		named.fromRHS = named.underlying // for consistency, though no cycle detection is necessary
 
 		return named
 
-	case *_TypeParam:
+	case *TypeParam:
 		return subst.smap.lookup(t)
 
-	case *instance:
-		// TODO(gri) can we avoid the expansion here and just substitute the type parameters?
-		return subst.typ(t.expand())
-
 	default:
 		panic("unimplemented")
 	}
@@ -416,14 +256,17 @@ func (subst *subster) typ(typ Type) Type {
 	return typ
 }
 
-// TODO(gri) Eventually, this should be more sophisticated.
-//           It won't work correctly for locally declared types.
+var instanceHashing = 0
+
 func instantiatedHash(typ *Named, targs []Type) string {
+	assert(instanceHashing == 0)
+	instanceHashing++
 	var buf bytes.Buffer
 	writeTypeName(&buf, typ.obj, nil)
 	buf.WriteByte('[')
 	writeTypeList(&buf, targs, nil, nil)
 	buf.WriteByte(']')
+	instanceHashing--
 
 	// With respect to the represented type, whether a
 	// type is fully expanded or stored as instance
@@ -541,3 +384,21 @@ func (subst *subster) typeList(in []Type) (out []Type, copied bool) {
 	}
 	return
 }
+
+func (subst *subster) termlist(in []*Term) (out []*Term, copied bool) {
+	out = in
+	for i, t := range in {
+		if u := subst.typ(t.typ); u != t.typ {
+			if !copied {
+				// first function that got substituted => allocate new out slice
+				// and copy all functions
+				new := make([]*Term, len(in))
+				copy(new, out)
+				out = new
+				copied = true
+			}
+			out[i] = NewTerm(t.tilde, u)
+		}
+	}
+	return
+}
diff --git a/src/go/types/termlist.go b/src/go/types/termlist.go
new file mode 100644
index 0000000000000000000000000000000000000000..99114cbf4cc5268f8493650dfc3bfbee3289225f
--- /dev/null
+++ b/src/go/types/termlist.go
@@ -0,0 +1,167 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import "bytes"
+
+// A termlist represents the type set represented by the union
+// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
+// A termlist is in normal form if all terms are disjoint.
+// termlist operations don't require the operands to be in
+// normal form.
+type termlist []*term
+
+// allTermlist represents the set of all types.
+// It is in normal form.
+var allTermlist = termlist{new(term)}
+
+// String prints the termlist exactly (without normalization).
+func (xl termlist) String() string {
+	if len(xl) == 0 {
+		return "∅"
+	}
+	var buf bytes.Buffer
+	for i, x := range xl {
+		if i > 0 {
+			buf.WriteString(" ∪ ")
+		}
+		buf.WriteString(x.String())
+	}
+	return buf.String()
+}
+
+// isEmpty reports whether the termlist xl represents the empty set of types.
+func (xl termlist) isEmpty() bool {
+	// If there's a non-nil term, the entire list is not empty.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// isAll reports whether the termlist xl represents the set of all types.
+func (xl termlist) isAll() bool {
+	// If there's a 𝓤 term, the entire list is 𝓤.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil && x.typ == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// norm returns the normal form of xl.
+func (xl termlist) norm() termlist {
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	used := make([]bool, len(xl))
+	var rl termlist
+	for i, xi := range xl {
+		if xi == nil || used[i] {
+			continue
+		}
+		for j := i + 1; j < len(xl); j++ {
+			xj := xl[j]
+			if xj == nil || used[j] {
+				continue
+			}
+			if u1, u2 := xi.union(xj); u2 == nil {
+				// If we encounter a 𝓤 term, the entire list is 𝓤.
+				// Exit early.
+				// (Note that this is not just an optimization;
+				// if we continue, we may end up with a 𝓤 term
+				// and other terms and the result would not be
+				// in normal form.)
+				if u1.typ == nil {
+					return allTermlist
+				}
+				xi = u1
+				used[j] = true // xj is now unioned into xi - ignore it in future iterations
+			}
+		}
+		rl = append(rl, xi)
+	}
+	return rl
+}
+
+// If the type set represented by xl is specified by a single (non-𝓤) term,
+// structuralType returns that type. Otherwise it returns nil.
+func (xl termlist) structuralType() Type {
+	if nl := xl.norm(); len(nl) == 1 {
+		return nl[0].typ // if nl.isAll() then typ is nil, which is ok
+	}
+	return nil
+}
+
+// union returns the union xl ∪ yl.
+func (xl termlist) union(yl termlist) termlist {
+	return append(xl, yl...).norm()
+}
+
+// intersect returns the intersection xl ∩ yl.
+func (xl termlist) intersect(yl termlist) termlist {
+	if xl.isEmpty() || yl.isEmpty() {
+		return nil
+	}
+
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	var rl termlist
+	for _, x := range xl {
+		for _, y := range yl {
+			if r := x.intersect(y); r != nil {
+				rl = append(rl, r)
+			}
+		}
+	}
+	return rl.norm()
+}
+
+// equal reports whether xl and yl represent the same type set.
+func (xl termlist) equal(yl termlist) bool {
+	// TODO(gri) this should be more efficient
+	return xl.subsetOf(yl) && yl.subsetOf(xl)
+}
+
+// includes reports whether t ∈ xl.
+func (xl termlist) includes(t Type) bool {
+	for _, x := range xl {
+		if x.includes(t) {
+			return true
+		}
+	}
+	return false
+}
+
+// supersetOf reports whether y ⊆ xl.
+func (xl termlist) supersetOf(y *term) bool {
+	for _, x := range xl {
+		if y.subsetOf(x) {
+			return true
+		}
+	}
+	return false
+}
+
+// subsetOf reports whether xl ⊆ yl.
+func (xl termlist) subsetOf(yl termlist) bool {
+	if yl.isEmpty() {
+		return xl.isEmpty()
+	}
+
+	// each term x of xl must be a subset of yl
+	for _, x := range xl {
+		if !yl.supersetOf(x) {
+			return false // x is not a subset yl
+		}
+	}
+	return true
+}
diff --git a/src/go/types/termlist_test.go b/src/go/types/termlist_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..d1fe28f728b30aed0419219992c65527bc21a3d8
--- /dev/null
+++ b/src/go/types/termlist_test.go
@@ -0,0 +1,313 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"strings"
+	"testing"
+)
+
+// maketl makes a term list from a string of the term list.
+func maketl(s string) termlist {
+	s = strings.ReplaceAll(s, " ", "")
+	names := strings.Split(s, "∪")
+	r := make(termlist, len(names))
+	for i, n := range names {
+		r[i] = testTerm(n)
+	}
+	return r
+}
+
+func TestTermlistAll(t *testing.T) {
+	if !allTermlist.isAll() {
+		t.Errorf("allTermlist is not the set of all types")
+	}
+}
+
+func TestTermlistString(t *testing.T) {
+	for _, want := range []string{
+		"∅",
+		"𝓤",
+		"int",
+		"~int",
+		"myInt",
+		"∅ ∪ ∅",
+		"𝓤 ∪ 𝓤",
+		"∅ ∪ 𝓤 ∪ int",
+		"∅ ∪ 𝓤 ∪ int ∪ myInt",
+	} {
+		if got := maketl(want).String(); got != want {
+			t.Errorf("(%v).String() == %v", want, got)
+		}
+	}
+}
+
+func TestTermlistIsEmpty(t *testing.T) {
+	for test, want := range map[string]bool{
+		"∅":             true,
+		"∅ ∪ ∅":         true,
+		"∅ ∪ ∅ ∪ 𝓤":     false,
+		"∅ ∪ ∅ ∪ myInt": false,
+		"𝓤":             false,
+		"𝓤 ∪ int":       false,
+		"𝓤 ∪ myInt ∪ ∅": false,
+	} {
+		xl := maketl(test)
+		got := xl.isEmpty()
+		if got != want {
+			t.Errorf("(%v).isEmpty() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistIsAll(t *testing.T) {
+	for test, want := range map[string]bool{
+		"∅":             false,
+		"∅ ∪ ∅":         false,
+		"int ∪ ~string": false,
+		"~int ∪ myInt":  false,
+		"∅ ∪ ∅ ∪ 𝓤":     true,
+		"𝓤":             true,
+		"𝓤 ∪ int":       true,
+		"myInt ∪ 𝓤":     true,
+	} {
+		xl := maketl(test)
+		got := xl.isAll()
+		if got != want {
+			t.Errorf("(%v).isAll() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistNorm(t *testing.T) {
+	for _, test := range []struct {
+		xl, want string
+	}{
+		{"∅", "∅"},
+		{"∅ ∪ ∅", "∅"},
+		{"∅ ∪ int", "int"},
+		{"∅ ∪ myInt", "myInt"},
+		{"𝓤 ∪ int", "𝓤"},
+		{"𝓤 ∪ myInt", "𝓤"},
+		{"int ∪ myInt", "int ∪ myInt"},
+		{"~int ∪ int", "~int"},
+		{"~int ∪ myInt", "~int"},
+		{"int ∪ ~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤 ∪ ~string ∪ int", "𝓤"},
+		{"~int ∪ string ∪ myInt ∪ ~string ∪ int", "~int ∪ ~string"},
+	} {
+		xl := maketl(test.xl)
+		got := maketl(test.xl).norm()
+		if got.String() != test.want {
+			t.Errorf("(%v).norm() = %v; want %v", xl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistStructuralType(t *testing.T) {
+	// helper to deal with nil types
+	tstring := func(typ Type) string {
+		if typ == nil {
+			return "nil"
+		}
+		return typ.String()
+	}
+
+	for test, want := range map[string]string{
+		"∅":                 "nil",
+		"𝓤":                 "nil",
+		"int":               "int",
+		"myInt":             "myInt",
+		"~int":              "int",
+		"~int ∪ string":     "nil",
+		"~int ∪ myInt":      "int",
+		"∅ ∪ int":           "int",
+		"∅ ∪ ~int":          "int",
+		"∅ ∪ ~int ∪ string": "nil",
+	} {
+		xl := maketl(test)
+		got := tstring(xl.structuralType())
+		if got != want {
+			t.Errorf("(%v).structuralType() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistUnion(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl, want string
+	}{
+
+		{"∅", "∅", "∅"},
+		{"∅", "𝓤", "𝓤"},
+		{"∅", "int", "int"},
+		{"𝓤", "~int", "𝓤"},
+		{"int", "~int", "~int"},
+		{"int", "string", "int ∪ string"},
+		{"int", "myInt", "int ∪ myInt"},
+		{"~int", "myInt", "~int"},
+		{"int ∪ string", "~string", "int ∪ ~string"},
+		{"~int ∪ string", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ string ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ myInt ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "𝓤"},
+		{"~int ∪ string ∪ myInt", "~string ∪ int", "~int ∪ ~string"},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.union(yl).String()
+		if got != test.want {
+			t.Errorf("(%v).union(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistIntersect(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl, want string
+	}{
+
+		{"∅", "∅", "∅"},
+		{"∅", "𝓤", "∅"},
+		{"∅", "int", "∅"},
+		{"∅", "myInt", "∅"},
+		{"𝓤", "~int", "~int"},
+		{"𝓤", "myInt", "myInt"},
+		{"int", "~int", "int"},
+		{"int", "string", "∅"},
+		{"int", "myInt", "∅"},
+		{"~int", "myInt", "myInt"},
+		{"int ∪ string", "~string", "string"},
+		{"~int ∪ string", "~string ∪ int", "int ∪ string"},
+		{"~int ∪ string ∪ ∅", "~string ∪ int", "int ∪ string"},
+		{"~int ∪ myInt ∪ ∅", "~string ∪ int", "int"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ myInt", "~string ∪ int", "int ∪ string"},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.intersect(yl).String()
+		if got != test.want {
+			t.Errorf("(%v).intersect(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistEqual(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl string
+		want   bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", false},
+		{"𝓤", "𝓤", true},
+		{"𝓤 ∪ int", "𝓤", true},
+		{"𝓤 ∪ int", "string ∪ 𝓤", true},
+		{"𝓤 ∪ myInt", "string ∪ 𝓤", true},
+		{"int ∪ ~string", "string ∪ int", false},
+		{"~int ∪ string", "string ∪ myInt", false},
+		{"int ∪ ~string ∪ ∅", "string ∪ int ∪ ~string", true},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.equal(yl)
+		if got != test.want {
+			t.Errorf("(%v).equal(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistIncludes(t *testing.T) {
+	for _, test := range []struct {
+		xl, typ string
+		want    bool
+	}{
+		{"∅", "int", false},
+		{"𝓤", "int", true},
+		{"~int", "int", true},
+		{"int", "string", false},
+		{"~int", "string", false},
+		{"~int", "myInt", true},
+		{"int ∪ string", "string", true},
+		{"~int ∪ string", "int", true},
+		{"~int ∪ string", "myInt", true},
+		{"~int ∪ myInt ∪ ∅", "myInt", true},
+		{"myInt ∪ ∅ ∪ 𝓤", "int", true},
+	} {
+		xl := maketl(test.xl)
+		yl := testTerm(test.typ).typ
+		got := xl.includes(yl)
+		if got != test.want {
+			t.Errorf("(%v).includes(%v) = %v; want %v", test.xl, yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistSupersetOf(t *testing.T) {
+	for _, test := range []struct {
+		xl, typ string
+		want    bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", false},
+		{"∅", "int", false},
+		{"𝓤", "∅", true},
+		{"𝓤", "𝓤", true},
+		{"𝓤", "int", true},
+		{"𝓤", "~int", true},
+		{"𝓤", "myInt", true},
+		{"~int", "int", true},
+		{"~int", "~int", true},
+		{"~int", "myInt", true},
+		{"int", "~int", false},
+		{"myInt", "~int", false},
+		{"int", "string", false},
+		{"~int", "string", false},
+		{"int ∪ string", "string", true},
+		{"int ∪ string", "~string", false},
+		{"~int ∪ string", "int", true},
+		{"~int ∪ string", "myInt", true},
+		{"~int ∪ string ∪ ∅", "string", true},
+		{"~string ∪ ∅ ∪ 𝓤", "myInt", true},
+	} {
+		xl := maketl(test.xl)
+		y := testTerm(test.typ)
+		got := xl.supersetOf(y)
+		if got != test.want {
+			t.Errorf("(%v).supersetOf(%v) = %v; want %v", test.xl, y, got, test.want)
+		}
+	}
+}
+
+func TestTermlistSubsetOf(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl string
+		want   bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", true},
+		{"𝓤", "∅", false},
+		{"𝓤", "𝓤", true},
+		{"int", "int ∪ string", true},
+		{"~int", "int ∪ string", false},
+		{"~int", "myInt ∪ string", false},
+		{"myInt", "~int ∪ string", true},
+		{"~int", "string ∪ string ∪ int ∪ ~int", true},
+		{"myInt", "string ∪ string ∪ ~int", true},
+		{"int ∪ string", "string", false},
+		{"int ∪ string", "string ∪ int", true},
+		{"int ∪ ~string", "string ∪ int", false},
+		{"myInt ∪ ~string", "string ∪ int ∪ 𝓤", true},
+		{"int ∪ ~string", "string ∪ int ∪ ∅ ∪ string", false},
+		{"int ∪ myInt", "string ∪ ~int ∪ ∅ ∪ string", true},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.subsetOf(yl)
+		if got != test.want {
+			t.Errorf("(%v).subsetOf(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
diff --git a/src/go/types/testdata/check/builtins.go2 b/src/go/types/testdata/check/builtins.go2
index 3918d836b5277a8a71d46380b441b1a29d409bd7..1c773cc70b17e741b1ac71882d3d80f9b977c0ef 100644
--- a/src/go/types/testdata/check/builtins.go2
+++ b/src/go/types/testdata/check/builtins.go2
@@ -6,48 +6,222 @@
 
 package builtins
 
-type Bmc interface {
-	type map[rune]string, chan int
+import "unsafe"
+
+// close
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
+}
+
+func _[T C0](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
+}
+
+func _[T C1](ch T) {
+	close(ch)
+}
+
+func _[T C2](ch T) {
+	close(ch /* ERROR cannot close receive-only channel */)
+}
+
+func _[T C3](ch T) {
+	close(ch)
+}
+
+func _[T C4](ch T) {
+	close(ch)
+}
+
+func _[T C5[X], X any](ch T) {
+	close(ch)
+}
+
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface { map[string]int | map[string]float64 }
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func _[T any](m T) {
+	delete(m /* ERROR not a map */, "foo")
 }
 
-type Bms interface {
-	type map[string]int, []int
+func _[T M0](m T) {
+	delete(m /* ERROR not a map */, "foo")
 }
 
-type Bcs interface {
-	type chan bool, []float64
+func _[T M1](m T) {
+	delete(m, "foo")
 }
 
-type Bss interface {
-	type []int, []string
+func _[T M2](m T) {
+	delete(m, "foo")
+	delete(m, 0 /* ERROR cannot use .* as string */)
 }
 
-func _[T any] () {
-	_ = make(T /* ERROR invalid argument */ )
-	_ = make(T /* ERROR invalid argument */ , 10)
-	_ = make(T /* ERROR invalid argument */ , 10, 20)
+func _[T M3](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
 }
 
-func _[T Bmc] () {
-	_ = make(T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 1 or 2 arguments */ (T, 10, 20)
+func _[T M4[rune, V], V any](m T) {
+	delete(m, 'k')
 }
 
-func _[T Bms] () {
-	_ = make /* ERROR expects 2 arguments */ (T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
+func _[T M4[K, V], K comparable, V any](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
 }
 
-func _[T Bcs] () {
-	_ = make /* ERROR expects 2 arguments */ (T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
+// make
+
+func _[
+	S1 interface{ []int },
+	S2 interface{ []int | chan int },
+
+	M1 interface{ map[string]int },
+	M2 interface{ map[string]int | chan int },
+
+	C1 interface{ chan int },
+	C2 interface{ chan int | chan string },
+]() {
+	type S0 []int
+	_ = make([]int, 10)
+	_ = make(S0, 10)
+	_ = make(S1, 10)
+	_ = make() /* ERROR not enough arguments */
+	_ = make /* ERROR expects 2 or 3 arguments */ (S1)
+	_ = make(S1, 10, 20)
+	_ = make /* ERROR expects 2 or 3 arguments */ (S1, 10, 20, 30)
+	_ = make(S2 /* ERROR cannot make .* no structural type */ , 10)
+
+	type M0 map[string]int
+	_ = make(map[string]int)
+	_ = make(M0)
+	_ = make(M1)
+	_ = make(M1, 10)
+	_ = make/* ERROR expects 1 or 2 arguments */(M1, 10, 20)
+	_ = make(M2 /* ERROR cannot make .* no structural type */ )
+
+	type C0 chan int
+	_ = make(chan int)
+	_ = make(C0)
+	_ = make(C1)
+	_ = make(C1, 10)
+	_ = make/* ERROR expects 1 or 2 arguments */(C1, 10, 20)
+	_ = make(C2 /* ERROR cannot make .* no structural type */ )
 }
 
-func _[T Bss] () {
-	_ = make /* ERROR expects 2 or 3 arguments */ (T)
-	_ = make(T, 10)
-	_ = make(T, 10, 20)
+// unsafe.Alignof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Alignof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Alignof(p)
+	assert(pp == 8)
+	const ll = unsafe.Alignof(l)
+	assert(ll == 8)
+	const ff = unsafe.Alignof(f)
+	assert(ff == 8)
+	const ii = unsafe.Alignof(i)
+	assert(ii == 8)
+	const cc = unsafe.Alignof(c)
+	assert(cc == 8)
+	const mm = unsafe.Alignof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Offsetof
+
+func _[T comparable]() {
+	var (
+		b struct{ _, f int64 }
+		a struct{ _, f [10]T }
+		s struct{ _, f struct{ f T } }
+		p struct{ _, f *T }
+		l struct{ _, f []T }
+		f struct{ _, f func(T) }
+		i struct{ _, f interface{ m() T } }
+		c struct{ _, f chan T }
+		m struct{ _, f map[T]T }
+		t struct{ _, f T }
+	)
+
+	const bb = unsafe.Offsetof(b.f)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Offsetof(p.f)
+	assert(pp == 8)
+	const ll = unsafe.Offsetof(l.f)
+	assert(ll == 24)
+	const ff = unsafe.Offsetof(f.f)
+	assert(ff == 8)
+	const ii = unsafe.Offsetof(i.f)
+	assert(ii == 16)
+	const cc = unsafe.Offsetof(c.f)
+	assert(cc == 8)
+	const mm = unsafe.Offsetof(m.f)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Sizeof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Sizeof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Sizeof(p)
+	assert(pp == 8)
+	const ll = unsafe.Sizeof(l)
+	assert(ll == 24)
+	const ff = unsafe.Sizeof(f)
+	assert(ff == 8)
+	const ii = unsafe.Sizeof(i)
+	assert(ii == 16)
+	const cc = unsafe.Sizeof(c)
+	assert(cc == 8)
+	const mm = unsafe.Sizeof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
 }
diff --git a/src/go/types/testdata/check/builtins.src b/src/go/types/testdata/check/builtins.src
index 370752891407beef0f7d828a128144617c4796c9..7fd6a4b03297ba2385f4e62ba4aecd450834c337 100644
--- a/src/go/types/testdata/check/builtins.src
+++ b/src/go/types/testdata/check/builtins.src
@@ -144,7 +144,7 @@ func close1() {
 	var r <-chan int
 	close() // ERROR not enough arguments
 	close(1, 2) // ERROR too many arguments
-	close(42 /* ERROR not a channel */)
+	close(42 /* ERROR cannot close non-channel */)
 	close(r /* ERROR receive-only channel */)
 	close(c)
 	_ = close /* ERROR used as value */ (c)
diff --git a/src/go/types/testdata/check/const0.src b/src/go/types/testdata/check/const0.src
index 5608b1549ba8d7774c2463fa9faab3702673f061..3cffdf904c87feb265ee5b1293d07be185e17372 100644
--- a/src/go/types/testdata/check/const0.src
+++ b/src/go/types/testdata/check/const0.src
@@ -27,7 +27,7 @@ const (
 	ub1 = true
 	ub2 = 2 < 1
 	ub3 = ui1 == uf1
-	ub4 = true /* ERROR "cannot convert" */ == 0
+	ub4 = true /* ERROR "mismatched types untyped bool and untyped int" */ == 0
 
 	// integer values
 	ui0 = 0
diff --git a/src/go/types/testdata/check/cycles4.src b/src/go/types/testdata/check/cycles4.src
index 445babca68bc3db73a1cc192f366480171fbc659..924aabf475f9640cdfa6da8834fa9a8db6aa0a2b 100644
--- a/src/go/types/testdata/check/cycles4.src
+++ b/src/go/types/testdata/check/cycles4.src
@@ -4,6 +4,8 @@
 
 package p
 
+import "unsafe"
+
 // Check that all methods of T are collected before
 // determining the result type of m (which embeds
 // all methods of T).
@@ -13,7 +15,7 @@ type T interface {
 	E
 }
 
-var _ = T.m(nil).m().e()
+var _ int = T.m(nil).m().e()
 
 type E interface {
 	e() int
@@ -22,7 +24,7 @@ type E interface {
 // Check that unresolved forward chains are followed
 // (see also comment in resolver.go, checker.typeDecl).
 
-var _ = C.m(nil).m().e()
+var _ int = C.m(nil).m().e()
 
 type A B
 
@@ -108,3 +110,12 @@ type Element interface {
 type Event interface {
 	Target() Element
 }
+
+// Check that accessing an interface method too early doesn't lead
+// to follow-on errors due to an incorrectly computed type set.
+
+type T8 interface {
+	m() [unsafe.Sizeof(T8.m /* ERROR undefined */ )]int
+}
+
+var _ = T8.m // no error expected here
diff --git a/src/go/types/testdata/check/decls0.src b/src/go/types/testdata/check/decls0.src
index 5ad8f53f65ab20b5e21b753119df153a67bd206b..1224e46377ab45f1bb32965ffd86f53a3431bb31 100644
--- a/src/go/types/testdata/check/decls0.src
+++ b/src/go/types/testdata/check/decls0.src
@@ -4,7 +4,7 @@
 
 // type declarations
 
-package decls0
+package go1_17 // don't permit non-interface elements in interfaces
 
 import "unsafe"
 
@@ -187,10 +187,10 @@ func f4() (x *f4 /* ERROR "not a type" */ ) { return }
 // TODO(#43215) this should be detected as a cycle error
 func f5([unsafe.Sizeof(f5)]int) {}
 
-func (S0) m1 (x S0 /* ERROR value .* is not a type */ .m1) {}
-func (S0) m2 (x *S0 /* ERROR value .* is not a type */ .m2) {}
-func (S0) m3 () (x S0 /* ERROR value .* is not a type */ .m3) { return }
-func (S0) m4 () (x *S0 /* ERROR value .* is not a type */ .m4) { return }
+func (S0) m1 (x S0 /* ERROR illegal cycle in method declaration */ .m1) {}
+func (S0) m2 (x *S0 /* ERROR illegal cycle in method declaration */ .m2) {}
+func (S0) m3 () (x S0 /* ERROR illegal cycle in method declaration */ .m3) { return }
+func (S0) m4 () (x *S0 /* ERROR illegal cycle in method declaration */ .m4) { return }
 
 // interfaces may not have any blank methods
 type BlankI interface {
diff --git a/src/go/types/testdata/check/decls1.src b/src/go/types/testdata/check/decls1.src
index f4d2eaba91150a5c82780e536716e21ab09f43ef..6fe349b0b2fda71f7c6369ed4f139b6bc4737496 100644
--- a/src/go/types/testdata/check/decls1.src
+++ b/src/go/types/testdata/check/decls1.src
@@ -83,7 +83,7 @@ var (
 
 // Constant expression initializations
 var (
-	v1 = 1 /* ERROR "cannot convert" */ + "foo"
+	v1 = 1 /* ERROR "mismatched types untyped int and untyped string" */ + "foo"
 	v2 = c + 255
 	v3 = c + 256 /* ERROR "overflows" */
 	v4 = r + 2147483647
diff --git a/src/go/types/testdata/check/expr1.src b/src/go/types/testdata/check/expr1.src
index 4ead815158f61e2dbbb91dec8e7feabef4a3923c..42b95fbb37bec2810aaff3a75b73d2e2ca79b8fc 100644
--- a/src/go/types/testdata/check/expr1.src
+++ b/src/go/types/testdata/check/expr1.src
@@ -111,10 +111,10 @@ type mystring string
 func _(x, y string, z mystring) {
 	x = x + "foo"
 	x = x /* ERROR not defined */ - "foo"
-	x = x + 1 // ERROR cannot convert
+	x = x /* ERROR mismatched types string and untyped int */ + 1
 	x = x + y
 	x = x /* ERROR not defined */ - y
-	x = x * 10 // ERROR cannot convert
+	x = x /* ERROR mismatched types string and untyped int */* 10
 }
 
 func f() (a, b int) { return }
diff --git a/src/go/types/testdata/check/expr2.src b/src/go/types/testdata/check/expr2.src
index 0c959e8011944f0ce42b89bc193e448628bc762f..f9726b5de53202c301757e36ea5bde812cd3db24 100644
--- a/src/go/types/testdata/check/expr2.src
+++ b/src/go/types/testdata/check/expr2.src
@@ -10,7 +10,7 @@ func _bool() {
 	const t = true == true
 	const f = true == false
 	_ = t /* ERROR "cannot compare" */ < f
-	_ = 0 /* ERROR "cannot convert" */ == t
+	_ = 0 /* ERROR "mismatched types untyped int and untyped bool" */ == t
 	var b bool
 	var x, y float32
 	b = x < y
diff --git a/src/go/types/testdata/check/expr3.src b/src/go/types/testdata/check/expr3.src
index 0525a5a33ae09012954ff7aa7c8b0d1e89733356..3ab367810f5172bf5354c9835b144e0ed1ff4b8b 100644
--- a/src/go/types/testdata/check/expr3.src
+++ b/src/go/types/testdata/check/expr3.src
@@ -103,7 +103,7 @@ func indexes() {
 	var ok mybool
 	_, ok = m["bar"]
 	_ = ok
-	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "cannot convert"
+	_ = m/* ERROR "mismatched types int and untyped string" */[0 /* ERROR "cannot use 0" */ ] + "foo"
 
 	var t string
 	_ = t[- /* ERROR "negative" */ 1]
diff --git a/src/go/types/testdata/check/issues.go2 b/src/go/types/testdata/check/issues.go2
index 8994164eacf5f9cd4bf2838b2b47442c2bc3ae6e..a994d73f66904cbf34aa0403382975f3f4f240e6 100644
--- a/src/go/types/testdata/check/issues.go2
+++ b/src/go/types/testdata/check/issues.go2
@@ -24,31 +24,23 @@ func _() {
 	eql[io.Reader](nil, nil)
 }
 
-// If we have a receiver of pointer type (below: *T) we must ignore
-// the pointer in the implementation of the method lookup because
-// the type bound of T is an interface and pointer to interface types
-// have no methods and then the lookup would fail.
+// If we have a receiver of pointer to type parameter type (below: *T)
+// we don't have any methods, like for interfaces.
 type C[T any] interface {
     m()
 }
 
 // using type bound C
 func _[T C[T]](x *T) {
-	x.m()
+	x.m  /* ERROR x\.m undefined */ ()
 }
 
 // using an interface literal as bound
 func _[T interface{ m() }](x *T) {
-	x.m()
+	x.m  /* ERROR x\.m undefined */ ()
 }
 
-// In a generic function body all method calls will be pointer method calls.
-// If necessary, the function body will insert temporary variables, not seen
-// by the user, in order to get an addressable variable to use to call the method.
-// Thus, assume an argument type for a generic function to be the type of addressable
-// values in the generic function when checking if the argument type satisfies the
-// generic function's type bound.
-func f2[_ interface{ m1(); m2() }]()
+func f2[_ interface{ m1(); m2() }]() {}
 
 type T struct{}
 func (T) m1()
@@ -64,15 +56,15 @@ func _() {
 // type with a type list constraint, all of the type argument's types in its
 // bound, but at least one (!), must be in the type list of the bound of the
 // corresponding parameterized type's type parameter.
-type T1[P interface{type uint}] struct{}
+type T1[P interface{~uint}] struct{}
 
 func _[P any]() {
-    _ = T1[P /* ERROR P has no type constraints */ ]{}
+    _ = T1[P /* ERROR P has no constraints */ ]{}
 }
 
 // This is the original (simplified) program causing the same issue.
 type Unsigned interface {
-	type uint
+	~uint
 }
 
 type T2[U Unsigned] struct {
@@ -83,8 +75,8 @@ func (u T2[U]) Add1() U {
     return u.s + 1
 }
 
-func NewT2[U any]() T2[U /* ERROR U has no type constraints */ ] {
-    return T2[U /* ERROR U has no type constraints */ ]{}
+func NewT2[U any]() T2[U /* ERROR U has no constraints */ ] {
+    return T2[U /* ERROR U has no constraints */ ]{}
 }
 
 func _() {
@@ -163,7 +155,7 @@ type inf2[T any] struct{ inf2 /* ERROR illegal cycle */ [T] }
 // predicate disjunction in the implementation was wrong because if a type list
 // contains both an integer and a floating-point type, the type parameter is
 // neither an integer or a floating-point number.
-func convert[T1, T2 interface{type int, uint, float32}](v T1) T2 {
+func convert[T1, T2 interface{~int | ~uint | ~float32}](v T1) T2 {
 	return T2(v)
 }
 
@@ -175,12 +167,12 @@ func _() {
 // both numeric, or both strings. The implementation had the same problem
 // with this check as the conversion issue above (issue #39623).
 
-func issue39623[T interface{type int, string}](x, y T) T {
+func issue39623[T interface{~int | ~string}](x, y T) T {
 	return x + y
 }
 
 // Simplified, from https://go2goplay.golang.org/p/efS6x6s-9NI:
-func Sum[T interface{type int, string}](s []T) (sum T) {
+func Sum[T interface{~int | ~string}](s []T) (sum T) {
 	for _, v := range s {
 		sum += v
 	}
@@ -189,19 +181,19 @@ func Sum[T interface{type int, string}](s []T) (sum T) {
 
 // Assignability of an unnamed pointer type to a type parameter that
 // has a matching underlying type.
-func _[T interface{}, PT interface{type *T}] (x T) PT {
+func _[T interface{}, PT interface{~*T}] (x T) PT {
     return &x
 }
 
 // Indexing of generic types containing type parameters in their type list:
-func at[T interface{ type []E }, E interface{}](x T, i int) E {
+func at[T interface{ ~[]E }, E interface{}](x T, i int) E {
         return x[i]
 }
 
 // A generic type inside a function acts like a named type. Its underlying
 // type is itself, its "operational type" is defined by the type list in
 // the tybe bound, if any.
-func _[T interface{type int}](x T) {
+func _[T interface{~int}](x T) {
 	type myint int
 	var _ int = int(x)
 	var _ T = 42
@@ -210,24 +202,24 @@ func _[T interface{type int}](x T) {
 
 // Indexing a generic type with an array type bound checks length.
 // (Example by mdempsky@.)
-func _[T interface { type [10]int }](x T) {
+func _[T interface { ~[10]int }](x T) {
 	_ = x[9] // ok
 	_ = x[20 /* ERROR out of bounds */ ]
 }
 
 // Pointer indirection of a generic type.
-func _[T interface{ type *int }](p T) int {
+func _[T interface{ ~*int }](p T) int {
 	return *p
 }
 
 // Channel sends and receives on generic types.
-func _[T interface{ type chan int }](ch T) int {
+func _[T interface{ ~chan int }](ch T) int {
 	ch <- 0
 	return <- ch
 }
 
 // Calling of a generic variable.
-func _[T interface{ type func() }](f T) {
+func _[T interface{ ~func() }](f T) {
 	f()
 	go f()
 }
@@ -239,9 +231,9 @@ func _[T interface{ type func() }](f T) {
 // type parameter that was substituted with a defined type.
 // Test case from an (originally) failing example.
 
-type sliceOf[E any] interface{ type []E }
+type sliceOf[E any] interface{ ~[]E }
 
-func append[T interface{}, S sliceOf[T], T2 interface{ type T }](s S, t ...T2) S
+func append[T interface{}, S sliceOf[T], T2 interface{}](s S, t ...T2) S { panic(0) }
 
 var f           func()
 var cancelSlice []context.CancelFunc
@@ -249,7 +241,7 @@ var _ = append[context.CancelFunc, []context.CancelFunc, context.CancelFunc](can
 
 // A generic function must be instantiated with a type, not a value.
 
-func g[T any](T) T
+func g[T any](T) T { panic(0) }
 
 var _ = g[int]
 var _ = g[nil /* ERROR is not a type */ ]
diff --git a/src/go/types/testdata/check/issues.src b/src/go/types/testdata/check/issues.src
index 55fe220337f47fba7342b0cb324ffc1c6301792b..ef1737331d7eeaac110fe8bfde549ac5a8181796 100644
--- a/src/go/types/testdata/check/issues.src
+++ b/src/go/types/testdata/check/issues.src
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package issues
+package go1_17 // don't permit non-interface elements in interfaces
 
 import (
 	"fmt"
diff --git a/src/go/types/testdata/check/linalg.go2 b/src/go/types/testdata/check/linalg.go2
index 0d27603a5837a2747922d9c1e52802b840ca8c4e..efc090a1d1f0b788dd8977cf551ed2d77a40a108 100644
--- a/src/go/types/testdata/check/linalg.go2
+++ b/src/go/types/testdata/check/linalg.go2
@@ -9,10 +9,10 @@ import "math"
 // Numeric is type bound that matches any numeric type.
 // It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
 }
 
 func DotProduct[T Numeric](s1, s2 []T) T {
@@ -42,14 +42,14 @@ func AbsDifference[T NumericAbs[T]](a, b T) T {
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // OrderedAbs is a helper type that defines an Abs method for
diff --git a/src/go/types/testdata/check/map2.go2 b/src/go/types/testdata/check/map2.go2
index 2833445662de813d6d3eeed95978c8342316b29f..e13bf33feda9edb1f87910f9bda04d4f7908bd9e 100644
--- a/src/go/types/testdata/check/map2.go2
+++ b/src/go/types/testdata/check/map2.go2
@@ -114,7 +114,7 @@ func (it *Iterator[K, V]) Next() (K, V, bool) {
 
 // chans
 
-func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T])
+func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T]) { panic(0) }
 
 // A sender is used to send values to a Receiver.
 type chans_Sender[T any] struct {
@@ -143,4 +143,4 @@ type chans_Receiver[T any] struct {
 func (r *chans_Receiver[T]) Next() (T, bool) {
 	v, ok := <-r.values
 	return v, ok
-}
\ No newline at end of file
+}
diff --git a/src/go/types/testdata/check/stmt0.src b/src/go/types/testdata/check/stmt0.src
index 76b6e70d63bacd703871aedfc02778196a7b5e6a..15df37703c1cb052175b2f810103a74eddf88e03 100644
--- a/src/go/types/testdata/check/stmt0.src
+++ b/src/go/types/testdata/check/stmt0.src
@@ -49,18 +49,18 @@ func assignments1() {
 	b = true
 
 	i += 1
-	i += "foo" /* ERROR "cannot convert.*int" */
+	i /* ERROR "mismatched types int and untyped string" */+= "foo"
 
 	f -= 1
 	f /= 0
 	f = float32(0)/0 /* ERROR "division by zero" */
-	f -= "foo" /* ERROR "cannot convert.*float64" */
+	f /* ERROR "mismatched types float64 and untyped string" */-= "foo"
 
 	c *= 1
 	c /= 0
 
 	s += "bar"
-	s += 1 /* ERROR "cannot convert.*string" */
+	s /* ERROR "mismatched types string and untyped int" */+= 1
 
 	var u64 uint64
 	u64 += 1< 0 {
 		x0 = x[0]
@@ -118,9 +118,9 @@ func max[T interface{ type int }](x ...T) T {
 // Thus even if a type can be inferred successfully, the function
 // call may not be valid.
 
-func fboth[T any](chan T)
-func frecv[T any](<-chan T)
-func fsend[T any](chan<- T)
+func fboth[T any](chan T) {}
+func frecv[T any](<-chan T) {}
+func fsend[T any](chan<- T) {}
 
 func _() {
 	var both chan int
@@ -140,9 +140,9 @@ func _() {
 	fsend(send)
 }
 
-func ffboth[T any](func(chan T))
-func ffrecv[T any](func(<-chan T))
-func ffsend[T any](func(chan<- T))
+func ffboth[T any](func(chan T)) {}
+func ffrecv[T any](func(<-chan T)) {}
+func ffsend[T any](func(chan<- T)) {}
 
 func _() {
 	var both func(chan int)
@@ -169,9 +169,9 @@ func _() {
 // assignment is permitted, parameter passing is permitted as well,
 // so type inference should be able to handle these cases well.
 
-func g1[T any]([]T)
-func g2[T any]([]T, T)
-func g3[T any](*T, ...T)
+func g1[T any]([]T) {}
+func g2[T any]([]T, T) {}
+func g3[T any](*T, ...T) {}
 
 func _() {
 	type intSlize []int
@@ -194,7 +194,7 @@ func _() {
 
 // Here's a realistic example.
 
-func append[T any](s []T, t ...T) []T
+func append[T any](s []T, t ...T) []T { panic(0) }
 
 func _() {
 	var f func()
@@ -207,8 +207,12 @@ func _() {
 // (that would indicate a slice type). Thus, generic functions cannot
 // have empty type parameter lists, either. This is a syntax error.
 
-func h[] /* ERROR empty type parameter list */ ()
+func h[] /* ERROR empty type parameter list */ () {}
 
 func _() {
 	h /* ERROR cannot index */ [] /* ERROR operand */ ()
 }
+
+// Parameterized functions must have a function body.
+
+func _ /* ERROR missing function body */ [P any]()
diff --git a/src/go/types/testdata/examples/inference.go2 b/src/go/types/testdata/examples/inference.go2
index b4f3369aa0c2560ca5b8821dc6a949055ba19aee..9a2dcc47f2a67d8d0cb1c695d3681100245a05eb 100644
--- a/src/go/types/testdata/examples/inference.go2
+++ b/src/go/types/testdata/examples/inference.go2
@@ -7,10 +7,10 @@
 package p
 
 type Ordered interface {
-	type int, float64, string
+	~int|~float64|~string
 }
 
-func min[T Ordered](x, y T) T
+func min[T Ordered](x, y T) T { panic(0) }
 
 func _() {
 	// min can be called with explicit instantiation.
@@ -37,7 +37,7 @@ func _() {
 	_ = min("foo", "bar")
 }
 
-func mixed[T1, T2, T3 any](T1, T2, T3)
+func mixed[T1, T2, T3 any](T1, T2, T3) {}
 
 func _() {
 	// mixed can be called with explicit instantiation.
@@ -54,7 +54,7 @@ func _() {
 	mixed[int, string](1.1 /* ERROR cannot use 1.1 */ , "", false)
 }
 
-func related1[Slice interface{type []Elem}, Elem any](s Slice, e Elem)
+func related1[Slice interface{~[]Elem}, Elem any](s Slice, e Elem) {}
 
 func _() {
 	// related1 can be called with explicit instantiation.
@@ -78,7 +78,7 @@ func _() {
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{type []Elem}](e Elem, s Slice)
+func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice) {}
 
 func _() {
 	// related2 can be called with explicit instantiation.
diff --git a/src/go/types/testdata/examples/methods.go2 b/src/go/types/testdata/examples/methods.go2
index 76c6539e1b7e7de019b7031025274eee082be8d7..4e87041e54771391056937e8b8e5424df025f5c5 100644
--- a/src/go/types/testdata/examples/methods.go2
+++ b/src/go/types/testdata/examples/methods.go2
@@ -6,6 +6,8 @@
 
 package p
 
+import "unsafe"
+
 // Parameterized types may have methods.
 type T1[A any] struct{ a A }
 
@@ -94,3 +96,18 @@ func (_ T2[_, _, _]) _() int { return 42 }
 type T0 struct{}
 func (T0) _() {}
 func (T1[A]) _() {}
+
+// A generic receiver type may constrain its type parameter such
+// that it must be a pointer type. Such receiver types are not
+// permitted.
+type T3a[P interface{ ~int | ~string | ~float64 }] P
+
+func (T3a[_]) m() {} // this is ok
+
+type T3b[P interface{ ~unsafe.Pointer }] P
+
+func (T3b /* ERROR invalid receiver */ [_]) m() {}
+
+type T3c[P interface{ *int | *string }] P
+
+func (T3c /* ERROR invalid receiver */ [_]) m() {}
diff --git a/src/go/types/testdata/examples/operations.go2 b/src/go/types/testdata/examples/operations.go2
new file mode 100644
index 0000000000000000000000000000000000000000..18e4d6080c59f0307c55e94bf389e4109eb88a7f
--- /dev/null
+++ b/src/go/types/testdata/examples/operations.go2
@@ -0,0 +1,29 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// indirection
+
+func _[P any](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ int }](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ *int }](p P) {
+        _ = *p
+}
+
+func _[P interface{ *int | *string }](p P) {
+        _ = *p // ERROR must have identical base types
+}
+
+type intPtr *int
+
+func _[P interface{ *int | intPtr } ](p P) {
+        var _ int = *p
+}
diff --git a/src/go/types/testdata/examples/types.go2 b/src/go/types/testdata/examples/types.go2
index 59c8804ad279597f3e3e0ce80bd5e05ad2d79b00..82f17a3263df8808341d898bff6a52c129375579 100644
--- a/src/go/types/testdata/examples/types.go2
+++ b/src/go/types/testdata/examples/types.go2
@@ -161,30 +161,40 @@ type _ struct {
 	* /* ERROR List redeclared */ List[int]
 }
 
+// Issue #45639: We don't allow this anymore. Keep this code
+//               in case we decide to revisit this decision.
+//
 // It's possible to declare local types whose underlying types
 // are type parameters. As with ordinary type definitions, the
 // types underlying properties are "inherited" but the methods
 // are not.
-func _[T interface{ m(); type int }]() {
-	type L T
-	var x L
-
-	// m is not defined on L (it is not "inherited" from
-	// its underlying type).
-	x.m /* ERROR x.m undefined */ ()
-
-	// But the properties of T, such that as that it supports
-	// the operations of the types given by its type bound,
-	// are also the properties of L.
-	x++
-	_ = x - x
-
-	// On the other hand, if we define a local alias for T,
-	// that alias stands for T as expected.
-	type A = T
-	var y A
-	y.m()
-	_ = y < 0
+//func _[T interface{ m(); ~int }]() {
+//	type L T
+//	var x L
+//
+//	// m is not defined on L (it is not "inherited" from
+//	// its underlying type).
+//	x.m /* ERROR x.m undefined */ ()
+//
+//	// But the properties of T, such that as that it supports
+//	// the operations of the types given by its type bound,
+//	// are also the properties of L.
+//	x++
+//	_ = x - x
+//
+//	// On the other hand, if we define a local alias for T,
+//	// that alias stands for T as expected.
+//	type A = T
+//	var y A
+//	y.m()
+//	_ = y < 0
+//}
+
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
 }
 
 // As a special case, an explicit type argument may be omitted
@@ -212,15 +222,15 @@ type B0 interface {}
 type B1[_ any] interface{}
 type B2[_, _ any] interface{}
 
-func _[T1 B0]()
-func _[T1 B1[T1]]()
-func _[T1 B2 /* ERROR cannot use generic type .* without instantiation */ ]()
+func _[T1 B0]() {}
+func _[T1 B1[T1]]() {}
+func _[T1 B2 /* ERROR cannot use generic type .* without instantiation */ ]() {}
 
-func _[T1, T2 B0]()
-func _[T1 B1[T1], T2 B1[T2]]()
-func _[T1, T2 B2 /* ERROR cannot use generic type .* without instantiation */ ]()
+func _[T1, T2 B0]() {}
+func _[T1 B1[T1], T2 B1[T2]]() {}
+func _[T1, T2 B2 /* ERROR cannot use generic type .* without instantiation */ ]() {}
 
-func _[T1 B0, T2 B1[T2]]() // here B1 applies to T2
+func _[T1 B0, T2 B1[T2]]() {} // here B1 applies to T2
 
 // When the type argument is left away, the type bound is
 // instantiated for each type parameter with that type
@@ -238,11 +248,11 @@ func _[A Adder[A], B Adder[B], C Adder[A]]() {
 // The type of variables (incl. parameters and return values) cannot
 // be an interface with type constraints or be/embed comparable.
 type I interface {
-	type int
+	~int
 }
 
 var (
-	_ interface /* ERROR contains type constraints */ {type int}
+	_ interface /* ERROR contains type constraints */ {~int}
 	_ I /* ERROR contains type constraints */
 )
 
@@ -273,7 +283,7 @@ func _() {
 // (If a type list contains just a single const type, we could
 // allow it, but such type lists don't make much sense in the
 // first place.)
-func _[T interface { type int, float64 }]() {
+func _[T interface {~int|~float64}]() {
 	// not valid
 	const _ = T /* ERROR not constant */ (0)
 	const _ T /* ERROR invalid constant type T */ = 1
diff --git a/src/go/types/testdata/fixedbugs/issue28251.src b/src/go/types/testdata/fixedbugs/issue28251.src
index cd79e0e8b5d299e905628654369e8df0db5477fe..ef5e61df47f2c5e332a5db29e82f24bccadbd5e0 100644
--- a/src/go/types/testdata/fixedbugs/issue28251.src
+++ b/src/go/types/testdata/fixedbugs/issue28251.src
@@ -60,6 +60,6 @@ type (
         T11 = T
 )
 
-func (T9 /* ERROR invalid receiver \*\*T */ ) m9() {}
+func (T9 /* ERROR invalid receiver type \*\*T */ ) m9() {}
 func _() { (T{}).m9 /* ERROR has no field or method m9 */ () }
 func _() { (&T{}).m9 /* ERROR has no field or method m9 */ () }
diff --git a/src/go/types/testdata/fixedbugs/issue39634.go2 b/src/go/types/testdata/fixedbugs/issue39634.go2
index a13ed13ce5f3dbf5df418a8296b76f4523ec71e2..f307ee9c9e9d0fa5bc14b3b28ded5a99bbe4919e 100644
--- a/src/go/types/testdata/fixedbugs/issue39634.go2
+++ b/src/go/types/testdata/fixedbugs/issue39634.go2
@@ -31,13 +31,14 @@ type x7[A any] struct{ foo7 }
 func main7() { var _ foo7 = x7[int]{} }
 
 // crash 8
-type foo8[A any] interface { type A }
-func bar8[A foo8[A]](a A) {}
-func main8() {}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// type foo8[A any] interface { ~A }
+// func bar8[A foo8[A]](a A) {}
+// func main8() {}
 
 // crash 9
-type foo9[A any] interface { type foo9 /* ERROR interface contains type constraints */ [A] }
-func _() { var _ = new(foo9 /* ERROR interface contains type constraints */ [int]) }
+type foo9[A any] interface { foo9 /* ERROR illegal cycle */ [A] }
+func _() { var _ = new(foo9 /* ERROR illegal cycle */ [int]) }
 
 // crash 12
 var u /* ERROR cycle */ , i [func /* ERROR used as value */ /* ERROR used as value */ (u, c /* ERROR undeclared */ /* ERROR undeclared */ ) {}(0, len /* ERROR must be called */ /* ERROR must be called */ )]c /* ERROR undeclared */ /* ERROR undeclared */
@@ -49,7 +50,7 @@ func (G15 /* ERROR generic type .* without instantiation */ ) p()
 
 // crash 16
 type Foo16[T any] r16 /* ERROR not a type */
-func r16[T any]() Foo16[Foo16[T]]
+func r16[T any]() Foo16[Foo16[T]] { panic(0) }
 
 // crash 17
 type Y17 interface{ c() }
@@ -57,7 +58,7 @@ type Z17 interface {
 	c() Y17
 	Y17 /* ERROR duplicate method */
 }
-func F17[T Z17](T)
+func F17[T Z17](T) {}
 
 // crash 18
 type o18[T any] []func(_ o18[[]_ /* ERROR cannot use _ */ ])
@@ -87,5 +88,5 @@ type T26 = interface{ F26[ /* ERROR methods cannot have type parameters */ Z any
 func F26[Z any]() T26 { return F26[] /* ERROR operand */ }
 
 // crash 27
-func e27[T any]() interface{ x27 /* ERROR not a type */ }
+func e27[T any]() interface{ x27 /* ERROR not a type */ } { panic(0) }
 func x27() { e27 /* ERROR cannot infer T */ () }
diff --git a/src/go/types/testdata/fixedbugs/issue39680.go2 b/src/go/types/testdata/fixedbugs/issue39680.go2
index 9bc26f35461345eb2f0d5728ba39fe793774723d..e56bc3547582d190f110b6f70a231e9e38012572 100644
--- a/src/go/types/testdata/fixedbugs/issue39680.go2
+++ b/src/go/types/testdata/fixedbugs/issue39680.go2
@@ -4,16 +4,19 @@
 
 package p
 
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+
+/*
 import "fmt"
 
 // Minimal test case.
-func _[T interface{type T}](x T) T{
+func _[T interface{~T}](x T) T{
 	return x
 }
 
 // Test case from issue.
 type constr[T any] interface {
-	type T
+	~T
 }
 
 func Print[T constr[T]](s []T) {
@@ -25,3 +28,4 @@ func Print[T constr[T]](s []T) {
 func f() {
 	Print([]string{"Hello, ", "playground\n"})
 }
+*/
diff --git a/src/go/types/testdata/fixedbugs/issue39693.go2 b/src/go/types/testdata/fixedbugs/issue39693.go2
index 316ab1982e89cf3635b1b1b16b3356f70a4d2b4f..ec7641902a12f3549eca15af28fda8a8ae808ebc 100644
--- a/src/go/types/testdata/fixedbugs/issue39693.go2
+++ b/src/go/types/testdata/fixedbugs/issue39693.go2
@@ -4,11 +4,20 @@
 
 package p
 
-type Number interface {
-	int     /* ERROR int is not an interface */
-	float64 /* ERROR float64 is not an interface */
+type Number1 interface {
+	// embedding non-interface types is permitted
+	int
+	float64
 }
 
-func Add[T Number](a, b T) T {
+func Add[T Number1](a, b T) T {
 	return a /* ERROR not defined */ + b
 }
+
+type Number2 interface {
+	int|float64
+}
+
+func Add2[T Number2](a, b T) T {
+	return a + b
+}
diff --git a/src/go/types/testdata/fixedbugs/issue39699.go2 b/src/go/types/testdata/fixedbugs/issue39699.go2
index 75491e7e26f00cd5b1d0ce771d471724ae7cdf9e..72f83997c2460a5496556cb1d294b9e260550c5d 100644
--- a/src/go/types/testdata/fixedbugs/issue39699.go2
+++ b/src/go/types/testdata/fixedbugs/issue39699.go2
@@ -8,7 +8,7 @@ type T0 interface{
 }
 
 type T1 interface{
-	type int
+	~int
 }
 
 type T2 interface{
diff --git a/src/go/types/testdata/fixedbugs/issue39711.go2 b/src/go/types/testdata/fixedbugs/issue39711.go2
index df621a4c1730db66648dd23c898a1238bdfce332..cf1f90545f6e8026fa53529db85ff47334117277 100644
--- a/src/go/types/testdata/fixedbugs/issue39711.go2
+++ b/src/go/types/testdata/fixedbugs/issue39711.go2
@@ -7,5 +7,7 @@ package p
 // Do not report a duplicate type error for this type list.
 // (Check types after interfaces have been completed.)
 type _ interface {
-	type interface{ Error() string }, interface{ String() string }
+	// TODO(rfindley) Once we have full type sets we can enable this again.
+	// Fow now we don't permit interfaces in type lists.
+	// type interface{ Error() string }, interface{ String() string }
 }
diff --git a/src/go/types/testdata/fixedbugs/issue39723.go2 b/src/go/types/testdata/fixedbugs/issue39723.go2
index 55464e6b7759f09016050e541868a72b50e1dca1..d5311ed3e7538e9350a0df3dc23b137a88503ae4 100644
--- a/src/go/types/testdata/fixedbugs/issue39723.go2
+++ b/src/go/types/testdata/fixedbugs/issue39723.go2
@@ -6,4 +6,4 @@ package p
 
 // A constraint must be an interface; it cannot
 // be a type parameter, for instance.
-func _[A interface{ type interface{} }, B A /* ERROR not an interface */ ]()
+func _[A interface{ ~int }, B A /* ERROR not an interface */ ]() {}
diff --git a/src/go/types/testdata/fixedbugs/issue39725.go2 b/src/go/types/testdata/fixedbugs/issue39725.go2
index e19b6770bfe4bd21462434f97ace29659a02c4ed..62dc45a59601eecc43e0b23fd09123cf00fbf57d 100644
--- a/src/go/types/testdata/fixedbugs/issue39725.go2
+++ b/src/go/types/testdata/fixedbugs/issue39725.go2
@@ -4,13 +4,13 @@
 
 package p
 
-func f1[T1, T2 any](T1, T2, struct{a T1; b T2})
+func f1[T1, T2 any](T1, T2, struct{a T1; b T2}) {}
 func _() {
 	f1(42, string("foo"), struct /* ERROR does not match inferred type struct\{a int; b string\} */ {a, b int}{})
 }
 
 // simplified test case from issue
-func f2[T any](_ []T, _ func(T))
+func f2[T any](_ []T, _ func(T)) {}
 func _() {
 	f2([]string{}, func /* ERROR does not match inferred type func\(string\) */ (f []byte) {})
 }
diff --git a/src/go/types/testdata/fixedbugs/issue39755.go2 b/src/go/types/testdata/fixedbugs/issue39755.go2
index b7ab68818e9587897e7f916730644a3dc1f0af8b..257b73a2fbeff15a934f4daf4798952578bad9d5 100644
--- a/src/go/types/testdata/fixedbugs/issue39755.go2
+++ b/src/go/types/testdata/fixedbugs/issue39755.go2
@@ -4,14 +4,14 @@
 
 package p
 
-func _[T interface{type map[string]int}](x T) {
+func _[T interface{~map[string]int}](x T) {
 	_ = x == nil
 }
 
 // simplified test case from issue
 
 type PathParamsConstraint interface {
-        type map[string]string, []struct{key, value string}
+        ~map[string]string | ~[]struct{key, value string}
 }
 
 type PathParams[T PathParamsConstraint] struct {
diff --git a/src/go/types/testdata/fixedbugs/issue39938.go2 b/src/go/types/testdata/fixedbugs/issue39938.go2
index 76e7e369ca12bb6718272a2de41dfc7f6617d848..0da6e103fd1139b48d6d26e6d9b9ec9cee7ac5db 100644
--- a/src/go/types/testdata/fixedbugs/issue39938.go2
+++ b/src/go/types/testdata/fixedbugs/issue39938.go2
@@ -8,8 +8,8 @@ package p
 
 type E0[P any] P
 type E1[P any] *P
-type E2[P any] struct{ P }
-type E3[P any] struct{ *P }
+type E2[P any] struct{ _ P }
+type E3[P any] struct{ _ *P }
 
 type T0 /* ERROR illegal cycle */ struct {
         _ E0[T0]
diff --git a/src/go/types/testdata/fixedbugs/issue39948.go2 b/src/go/types/testdata/fixedbugs/issue39948.go2
index c2b460902cc643b5537834e489f3213f551fe6f7..e38e57268d63d1fd00012274bd8ea23bc2a7c7df 100644
--- a/src/go/types/testdata/fixedbugs/issue39948.go2
+++ b/src/go/types/testdata/fixedbugs/issue39948.go2
@@ -5,5 +5,5 @@
 package p
 
 type T[P any] interface{
-	P // ERROR P is a type parameter, not an interface
+	P // ERROR cannot embed a type parameter
 }
diff --git a/src/go/types/testdata/fixedbugs/issue39976.go2 b/src/go/types/testdata/fixedbugs/issue39976.go2
index 3db4eae0123930db81b5ff193e58ff802678878a..d703da90a2176a3e975f5a62cad5cf5b3f665faf 100644
--- a/src/go/types/testdata/fixedbugs/issue39976.go2
+++ b/src/go/types/testdata/fixedbugs/issue39976.go2
@@ -7,7 +7,7 @@ package p
 type policy[K, V any] interface{}
 type LRU[K, V any] struct{}
 
-func NewCache[K, V any](p policy[K, V])
+func NewCache[K, V any](p policy[K, V]) {}
 
 func _() {
 	var lru LRU[int, string]
diff --git a/src/go/types/testdata/fixedbugs/issue40038.go2 b/src/go/types/testdata/fixedbugs/issue40038.go2
index 8948d61caa477fff40ac7f773946d0377df734e4..5f81fcbfaa7236bfcdd58114ac74847f9e709555 100644
--- a/src/go/types/testdata/fixedbugs/issue40038.go2
+++ b/src/go/types/testdata/fixedbugs/issue40038.go2
@@ -8,8 +8,8 @@ type A[T any] int
 
 func (A[T]) m(A[T])
 
-func f[P interface{m(P)}]()
+func f[P interface{m(P)}]() {}
 
 func _() {
 	_ = f[A[int]]
-}
\ No newline at end of file
+}
diff --git a/src/go/types/testdata/fixedbugs/issue40056.go2 b/src/go/types/testdata/fixedbugs/issue40056.go2
index f587691e3d746a58bc22a2bfd6d9382230859d3c..66130c0a558ebaef7ec875d3072a818a65b16ff3 100644
--- a/src/go/types/testdata/fixedbugs/issue40056.go2
+++ b/src/go/types/testdata/fixedbugs/issue40056.go2
@@ -10,6 +10,6 @@ func _() {
 
 type S struct {}
 
-func NewS[T any]() *S
+func NewS[T any]() *S { panic(0) }
 
 func (_ *S /* ERROR S is not a generic type */ [T]) M()
diff --git a/src/go/types/testdata/fixedbugs/issue40301.go2 b/src/go/types/testdata/fixedbugs/issue40301.go2
index 5d97855f8a172ff414ae86c5112b500059a3142b..c78f9a1fa040892e7ebec27753100db2867752b2 100644
--- a/src/go/types/testdata/fixedbugs/issue40301.go2
+++ b/src/go/types/testdata/fixedbugs/issue40301.go2
@@ -7,6 +7,6 @@ package p
 import "unsafe"
 
 func _[T any](x T) {
-	_ = unsafe /* ERROR undefined */ .Alignof(x)
-	_ = unsafe /* ERROR undefined */ .Sizeof(x)
+	_ = unsafe.Alignof(x)
+	_ = unsafe.Sizeof(x)
 }
diff --git a/src/go/types/testdata/fixedbugs/issue40684.go2 b/src/go/types/testdata/fixedbugs/issue40684.go2
index 0269c3a62ce6d0d10d92f0f2cb4e0ce8e82129cf..63a058d039d93448f745ec2ecc1d091dae93da13 100644
--- a/src/go/types/testdata/fixedbugs/issue40684.go2
+++ b/src/go/types/testdata/fixedbugs/issue40684.go2
@@ -6,10 +6,10 @@ package p
 
 type T[_ any] int
 
-func f[_ any]()
-func g[_, _ any]()
+func f[_ any]() {}
+func g[_, _ any]() {}
 
 func _() {
 	_ = f[T /* ERROR without instantiation */ ]
 	_ = g[T /* ERROR without instantiation */ , T /* ERROR without instantiation */ ]
-}
\ No newline at end of file
+}
diff --git a/src/go/types/testdata/fixedbugs/issue40789.go2 b/src/go/types/testdata/fixedbugs/issue40789.go2
new file mode 100644
index 0000000000000000000000000000000000000000..9eea4ad60a6647380606f70fd998febab618db8c
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue40789.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func main() {
+	m := map[string]int{
+		"a": 6,
+		"b": 7,
+	}
+	fmt.Println(copyMap[map[string]int, string, int](m))
+}
+
+type Map[K comparable, V any] interface {
+	map[K] V
+}
+
+func copyMap[M Map[K, V], K comparable, V any](m M) M {
+	m1 := make(M)
+	for k, v := range m {
+		m1[k] = v
+	}
+	return m1
+}
+
+// simpler test case from the same issue
+
+type A[X comparable] interface {
+	[]X
+}
+
+func f[B A[X], X comparable]() B {
+	return nil
+}
diff --git a/src/go/types/testdata/fixedbugs/issue41124.go2 b/src/go/types/testdata/fixedbugs/issue41124.go2
index 61f766bcbd7891ef16f8ca6396349e1ff43159f6..4642ab60fc8edaf7f78c709459f29b549258e33f 100644
--- a/src/go/types/testdata/fixedbugs/issue41124.go2
+++ b/src/go/types/testdata/fixedbugs/issue41124.go2
@@ -7,7 +7,7 @@ package p
 // Test case from issue.
 
 type Nat interface {
-	type Zero, Succ
+	Zero|Succ
 }
 
 type Zero struct{}
@@ -22,7 +22,7 @@ type I1 interface {
 }
 
 type I2 interface {
-	type int
+	~int
 }
 
 type I3 interface {
@@ -47,7 +47,7 @@ type _ struct{
 }
 
 type _ struct{
-	I3 // ERROR interface contains type constraints
+	I3 // ERROR interface is .* comparable
 }
 
 // General composite types.
@@ -59,19 +59,19 @@ type (
 	_ []I1 // ERROR interface is .* comparable
 	_ []I2 // ERROR interface contains type constraints
 
-	_ *I3 // ERROR interface contains type constraints
+	_ *I3 // ERROR interface is .* comparable
 	_ map[I1 /* ERROR interface is .* comparable */ ]I2 // ERROR interface contains type constraints
-	_ chan I3 // ERROR interface contains type constraints
+	_ chan I3 // ERROR interface is .* comparable
 	_ func(I1 /* ERROR interface is .* comparable */ )
 	_ func() I2 // ERROR interface contains type constraints
 )
 
 // Other cases.
 
-var _ = [...]I3 /* ERROR interface contains type constraints */ {}
+var _ = [...]I3 /* ERROR interface is .* comparable */ {}
 
 func _(x interface{}) {
-	_ = x.(I3 /* ERROR interface contains type constraints */ )
+	_ = x.(I3 /* ERROR interface is .* comparable */ )
 }
 
 type T1[_ any] struct{}
@@ -79,9 +79,9 @@ type T3[_, _, _ any] struct{}
 var _ T1[I2 /* ERROR interface contains type constraints */ ]
 var _ T3[int, I2 /* ERROR interface contains type constraints */ , float32]
 
-func f1[_ any]() int
+func f1[_ any]() int { panic(0) }
 var _ = f1[I2 /* ERROR interface contains type constraints */ ]()
-func f3[_, _, _ any]() int
+func f3[_, _, _ any]() int { panic(0) }
 var _ = f3[int, I2 /* ERROR interface contains type constraints */ , float32]()
 
 func _(x interface{}) {
diff --git a/src/go/types/testdata/fixedbugs/issue42758.go2 b/src/go/types/testdata/fixedbugs/issue42758.go2
index 698cb8a16bad26194a40f5893e7a1d493b30083c..bf0031f5d244305720afb8c8d2f2710c5b8bbaf9 100644
--- a/src/go/types/testdata/fixedbugs/issue42758.go2
+++ b/src/go/types/testdata/fixedbugs/issue42758.go2
@@ -17,7 +17,7 @@ func _[T any](x interface{}){
 }
 
 type constraint interface {
-	type int
+	~int
 }
 
 func _[T constraint](x interface{}){
diff --git a/src/go/types/testdata/fixedbugs/issue43671.go2 b/src/go/types/testdata/fixedbugs/issue43671.go2
new file mode 100644
index 0000000000000000000000000000000000000000..6cc3801cc96b8b38ed8ef4c9ea6e4a8ad6c54081
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue43671.go2
@@ -0,0 +1,58 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | <-chan T }
+
+func _[T any](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C0](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C1](ch T) {
+	<-ch
+}
+
+func _[T C2](ch T) {
+	<-ch
+}
+
+func _[T C3](ch T) {
+	<-ch // ERROR channels of ch .* must have the same element type
+}
+
+func _[T C4](ch T) {
+	<-ch // ERROR cannot receive from send-only channel
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	x = <-ch
+}
+
+// test case from issue, slightly modified
+type RecvChan[T any] interface {
+	~chan T | ~<-chan T
+}
+
+func _[T any, C RecvChan[T]](ch C) T {
+	return <-ch
+}
+
+func f[T any, C interface{ chan T }](ch C) T {
+	return <-ch
+}
+
+func _(ch chan int) {
+	var x int = f(ch) // test constraint type inference for this case
+	_ = x
+}
diff --git a/src/go/types/testdata/fixedbugs/issue45548.go2 b/src/go/types/testdata/fixedbugs/issue45548.go2
index b1e42497e8586c500d11985f0df6c70249927949..b8ba0ad4a70915b4edaca42bb24ca60f1088a2bd 100644
--- a/src/go/types/testdata/fixedbugs/issue45548.go2
+++ b/src/go/types/testdata/fixedbugs/issue45548.go2
@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{type *Q}, G interface{type *R}, Q, R any](q Q, r R) {}
+func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)
diff --git a/src/go/types/testdata/fixedbugs/issue45635.go2 b/src/go/types/testdata/fixedbugs/issue45635.go2
index 3e2cceca2d43b007e9f11bda908ab50ba588b281..fc50797b17ca76929275a00ff343e0b25484bb72 100644
--- a/src/go/types/testdata/fixedbugs/issue45635.go2
+++ b/src/go/types/testdata/fixedbugs/issue45635.go2
@@ -10,10 +10,10 @@ func main() {
 
 type N[T any] struct{}
 
-var _ N /* ERROR "0 arguments but 1 type parameters" */ []
+var _ N [] // ERROR expected type argument list
 
 type I interface {
-	type map[int]int, []int
+	~[]int
 }
 
 func _[T I](i, j int) {
@@ -27,6 +27,5 @@ func _[T I](i, j int) {
 	_ = s[i, j /* ERROR "more than one index" */ ]
 
 	var t T
-	// TODO(rFindley) Fix the duplicate error below.
-	_ = t[i, j /* ERROR "more than one index" */ /* ERROR "more than one index" */ ]
+	_ = t[i, j /* ERROR "more than one index" */ ]
 }
diff --git a/src/go/types/testdata/fixedbugs/issue45639.go2 b/src/go/types/testdata/fixedbugs/issue45639.go2
new file mode 100644
index 0000000000000000000000000000000000000000..441fb4cb346211c684e0a9e51247102b89ed7048
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue45639.go2
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package P
+
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
+}
diff --git a/src/go/types/testdata/fixedbugs/issue45985.go2 b/src/go/types/testdata/fixedbugs/issue45985.go2
index 550b9c6712768cb9950fd398a366ab1b3677a7d4..6e42dbb633969bf92e3df7e0ce084c4de103b7b3 100644
--- a/src/go/types/testdata/fixedbugs/issue45985.go2
+++ b/src/go/types/testdata/fixedbugs/issue45985.go2
@@ -5,7 +5,7 @@
 package issue45985
 
 // TODO(rFindley): this error should be on app[int] below.
-func app[S /* ERROR "type S = S does not match" */ interface{ type []T }, T any](s S, e T) S {
+func app[S /* ERROR "type S = S does not match" */ interface{ ~[]T }, T any](s S, e T) S {
     return append(s, e)
 }
 
diff --git a/src/go/types/testdata/fixedbugs/issue46090.go2 b/src/go/types/testdata/fixedbugs/issue46090.go2
new file mode 100644
index 0000000000000000000000000000000000000000..81b31974c8dc0207e0833d51c845b978ce26cef4
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue46090.go2
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The predeclared type comparable is not visible before Go 1.18.
+
+package go1_17
+
+type _ comparable // ERROR undeclared
diff --git a/src/go/types/testdata/fixedbugs/issue46275.go2 b/src/go/types/testdata/fixedbugs/issue46275.go2
new file mode 100644
index 0000000000000000000000000000000000000000..0ebde31c8e909c204eb586ea3ab4fdeb5cf15182
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue46275.go2
@@ -0,0 +1,27 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package issue46275
+
+type N[T any] struct {
+        *N[T]
+        t T
+}
+
+func (n *N[T]) Elem() T {
+        return n.t
+}
+
+type I interface {
+        Elem() string
+}
+
+func _() {
+        var n1 *N[string]
+        var _ I = n1
+        type NS N[string]
+        var n2 *NS
+        var _ I = n2
+}
+
diff --git a/src/go/types/testdata/fixedbugs/issue47031.go2 b/src/go/types/testdata/fixedbugs/issue47031.go2
new file mode 100644
index 0000000000000000000000000000000000000000..b184f9b5b7dfbf7255d9bd6587fb78acce371fb6
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47031.go2
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Mer interface { M() }
+
+func F[T Mer](p *T) {
+	p.M /* ERROR p\.M undefined */ ()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+
+func _() {
+	F(new(MyMer))
+	F[Mer](nil)
+}
diff --git a/src/go/types/testdata/fixedbugs/issue47115.go2 b/src/go/types/testdata/fixedbugs/issue47115.go2
new file mode 100644
index 0000000000000000000000000000000000000000..6694219b54934c3856d02c2faf7a0692dd752281
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47115.go2
@@ -0,0 +1,40 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	ch <- /* ERROR cannot send to non-channel */ 0
+}
+
+func _[T C0](ch T) {
+	ch <- /* ERROR cannot send to non-channel */ 0
+}
+
+func _[T C1](ch T) {
+	ch <- 0
+}
+
+func _[T C2](ch T) {
+	ch  <-/* ERROR cannot send to receive-only channel */ 0
+}
+
+func _[T C3](ch T) {
+	ch <- /* ERROR channels of ch .* must have the same element type */ 0
+}
+
+func _[T C4](ch T) {
+	ch <- 0
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	ch <- x
+}
diff --git a/src/go/types/testdata/fixedbugs/issue47127.go2 b/src/go/types/testdata/fixedbugs/issue47127.go2
new file mode 100644
index 0000000000000000000000000000000000000000..108d600a38a6c9ce9075ca792ab7abf4077f1d8e
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47127.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Embedding of stand-alone type parameters is not permitted.
+
+package p
+
+type (
+        _[P any] interface{ *P | []P | chan P | map[string]P }
+        _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+)
+
+func _[P any]() {
+        type (
+                _[P any] interface{ *P | []P | chan P | map[string]P }
+                _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+
+                _ interface{ *P | []P | chan P | map[string]P }
+                _ interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+        )
+}
+
+func _[P any, Q interface{ *P | []P | chan P | map[string]P }]() {}
+func _[P any, Q interface{ P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ ~P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ int | P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }]() {}
diff --git a/src/go/types/testdata/fixedbugs/issue47411.go2 b/src/go/types/testdata/fixedbugs/issue47411.go2
new file mode 100644
index 0000000000000000000000000000000000000000..2fc26d9e8591097dcb7c4a7e389942c5c6084ac8
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47411.go2
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f[_ comparable]() {}
+func g[_ interface{interface{comparable; ~int|~string}}]() {}
+
+func _[P comparable,
+        Q interface{ comparable; ~int|~string },
+        R any,                               // not comparable
+        S interface{ comparable; ~func() },  // not comparable
+]() {
+        _ = f[int]
+        _ = f[P]
+        _ = f[Q]
+        _ = f[func /* ERROR does not satisfy comparable */ ()]
+        _ = f[R /* ERROR R has no constraints */ ]
+
+        _ = g[int]
+        _ = g[P /* ERROR P has no type constraints */ ]
+        _ = g[Q]
+        _ = g[func /* ERROR does not satisfy comparable */()]
+        _ = g[R /* ERROR R has no constraints */ ]
+}
diff --git a/src/go/types/testdata/fixedbugs/issue47747.go2 b/src/go/types/testdata/fixedbugs/issue47747.go2
new file mode 100644
index 0000000000000000000000000000000000000000..af52056bef2ad91606a289f3168aa28a4ca13624
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47747.go2
@@ -0,0 +1,68 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type T1[P any] P
+
+func (T1[_]) m() {}
+
+func _[P any](x *T1[P]) {
+        // x.m exists because x is of type *T1 where T1 is a defined type
+        // (even though under(T1) is a type parameter)
+        x.m()
+}
+
+
+func _[P interface{ m() }](x P) {
+        x.m()
+        // (&x).m doesn't exist because &x is of type *P
+        // and pointers to type parameters don't have methods
+        (&x).m /* ERROR \*P has no field or method m */ ()
+}
+
+
+type T2 interface{ m() }
+
+func _(x *T2) {
+        // x.m doesn't exists because x is of type *T2
+        // and pointers to interfaces don't have methods
+        x.m /* ERROR \*T2 has no field or method m */()
+}
+
+// Test case 1 from issue
+
+type Fooer1[t any] interface {
+	Foo(Barer[t])
+}
+type Barer[t any] interface {
+	Bar(t)
+}
+
+type Foo1[t any] t
+type Bar[t any] t
+
+func (l Foo1[t]) Foo(v Barer[t]) { v.Bar(t(l)) }
+func (b *Bar[t]) Bar(l t)        { *b = Bar[t](l) }
+
+func _[t any](f Fooer1[t]) t {
+	var b Bar[t]
+	f.Foo(&b)
+	return t(b)
+}
+
+// Test case 2 from issue
+
+type Fooer2[t any] interface {
+	Foo()
+}
+
+type Foo2[t any] t
+
+func (f *Foo2[t]) Foo() {}
+
+func _[t any](v t) {
+	var f = Foo2[t](v)
+	_ = Fooer2[t](&f)
+}
diff --git a/src/go/types/testdata/manual.go2 b/src/go/types/testdata/manual.go2
new file mode 100644
index 0000000000000000000000000000000000000000..25e6f22f94b7336cd60ae59e226f047856476e01
--- /dev/null
+++ b/src/go/types/testdata/manual.go2
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is tested when running "go test -run Manual"
+// without source arguments. Use for one-off debugging.
+
+package p
+
diff --git a/src/go/types/tuple.go b/src/go/types/tuple.go
new file mode 100644
index 0000000000000000000000000000000000000000..16d28bc9a6fc222a4dee0a1de842b318df81cc9d
--- /dev/null
+++ b/src/go/types/tuple.go
@@ -0,0 +1,36 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
+// Tuples are used as components of signatures and to represent the type of multiple
+// assignments; they are not first class types of Go.
+type Tuple struct {
+	vars []*Var
+}
+
+// NewTuple returns a new tuple for the given variables.
+func NewTuple(x ...*Var) *Tuple {
+	if len(x) > 0 {
+		return &Tuple{vars: x}
+	}
+	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
+	//           it's too subtle and causes problems.
+	return nil
+}
+
+// Len returns the number variables of tuple t.
+func (t *Tuple) Len() int {
+	if t != nil {
+		return len(t.vars)
+	}
+	return 0
+}
+
+// At returns the i'th variable of tuple t.
+func (t *Tuple) At(i int) *Var { return t.vars[i] }
+
+func (t *Tuple) Underlying() Type { return t }
+func (t *Tuple) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/type.go b/src/go/types/type.go
index 2660ce4408c1b640f67bf517ca72d3819055907e..3be42a15846e19a954bc0cc4da3016083ed5fe5a 100644
--- a/src/go/types/type.go
+++ b/src/go/types/type.go
@@ -4,12 +4,6 @@
 
 package types
 
-import (
-	"fmt"
-	"go/token"
-	"sync/atomic"
-)
-
 // A Type represents a type of Go.
 // All types implement the Type interface.
 type Type interface {
@@ -22,892 +16,55 @@ type Type interface {
 	String() string
 }
 
-// BasicKind describes the kind of basic type.
-type BasicKind int
-
-const (
-	Invalid BasicKind = iota // type is invalid
-
-	// predeclared types
-	Bool
-	Int
-	Int8
-	Int16
-	Int32
-	Int64
-	Uint
-	Uint8
-	Uint16
-	Uint32
-	Uint64
-	Uintptr
-	Float32
-	Float64
-	Complex64
-	Complex128
-	String
-	UnsafePointer
-
-	// types for untyped values
-	UntypedBool
-	UntypedInt
-	UntypedRune
-	UntypedFloat
-	UntypedComplex
-	UntypedString
-	UntypedNil
-
-	// aliases
-	Byte = Uint8
-	Rune = Int32
-)
-
-// BasicInfo is a set of flags describing properties of a basic type.
-type BasicInfo int
-
-// Properties of basic types.
-const (
-	IsBoolean BasicInfo = 1 << iota
-	IsInteger
-	IsUnsigned
-	IsFloat
-	IsComplex
-	IsString
-	IsUntyped
-
-	IsOrdered   = IsInteger | IsFloat | IsString
-	IsNumeric   = IsInteger | IsFloat | IsComplex
-	IsConstType = IsBoolean | IsNumeric | IsString
-)
-
-// A Basic represents a basic type.
-type Basic struct {
-	kind BasicKind
-	info BasicInfo
-	name string
-}
-
-// Kind returns the kind of basic type b.
-func (b *Basic) Kind() BasicKind { return b.kind }
-
-// Info returns information about properties of basic type b.
-func (b *Basic) Info() BasicInfo { return b.info }
-
-// Name returns the name of basic type b.
-func (b *Basic) Name() string { return b.name }
-
-// An Array represents an array type.
-type Array struct {
-	len  int64
-	elem Type
-}
-
-// NewArray returns a new array type for the given element type and length.
-// A negative length indicates an unknown length.
-func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
-
-// Len returns the length of array a.
-// A negative result indicates an unknown length.
-func (a *Array) Len() int64 { return a.len }
-
-// Elem returns element type of array a.
-func (a *Array) Elem() Type { return a.elem }
-
-// A Slice represents a slice type.
-type Slice struct {
-	elem Type
-}
-
-// NewSlice returns a new slice type for the given element type.
-func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
-
-// Elem returns the element type of slice s.
-func (s *Slice) Elem() Type { return s.elem }
-
-// A Struct represents a struct type.
-type Struct struct {
-	fields []*Var
-	tags   []string // field tags; nil if there are no tags
-}
-
-// NewStruct returns a new struct with the given fields and corresponding field tags.
-// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
-// only as long as required to hold the tag with the largest index i. Consequently,
-// if no field has a tag, tags may be nil.
-func NewStruct(fields []*Var, tags []string) *Struct {
-	var fset objset
-	for _, f := range fields {
-		if f.name != "_" && fset.insert(f) != nil {
-			panic("multiple fields with the same name")
-		}
-	}
-	if len(tags) > len(fields) {
-		panic("more tags than fields")
-	}
-	return &Struct{fields: fields, tags: tags}
-}
-
-// NumFields returns the number of fields in the struct (including blank and embedded fields).
-func (s *Struct) NumFields() int { return len(s.fields) }
-
-// Field returns the i'th field for 0 <= i < NumFields().
-func (s *Struct) Field(i int) *Var { return s.fields[i] }
-
-// Tag returns the i'th field tag for 0 <= i < NumFields().
-func (s *Struct) Tag(i int) string {
-	if i < len(s.tags) {
-		return s.tags[i]
-	}
-	return ""
-}
-
-// A Pointer represents a pointer type.
-type Pointer struct {
-	base Type // element type
-}
-
-// NewPointer returns a new pointer type for the given element (base) type.
-func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
-
-// Elem returns the element type for the given pointer p.
-func (p *Pointer) Elem() Type { return p.base }
-
-// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
-// Tuples are used as components of signatures and to represent the type of multiple
-// assignments; they are not first class types of Go.
-type Tuple struct {
-	vars []*Var
-}
-
-// NewTuple returns a new tuple for the given variables.
-func NewTuple(x ...*Var) *Tuple {
-	if len(x) > 0 {
-		return &Tuple{vars: x}
-	}
-	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
-	//           it's too subtle and causes problems.
-	return nil
-}
-
-// Len returns the number variables of tuple t.
-func (t *Tuple) Len() int {
-	if t != nil {
-		return len(t.vars)
-	}
-	return 0
-}
-
-// At returns the i'th variable of tuple t.
-func (t *Tuple) At(i int) *Var { return t.vars[i] }
-
-// A Signature represents a (non-builtin) function or method type.
-// The receiver is ignored when comparing signatures for identity.
-type Signature struct {
-	// We need to keep the scope in Signature (rather than passing it around
-	// and store it in the Func Object) because when type-checking a function
-	// literal we call the general type checker which returns a general Type.
-	// We then unpack the *Signature and use the scope for the literal body.
-	rparams  []*TypeName // receiver type parameters from left to right, or nil
-	tparams  []*TypeName // type parameters from left to right, or nil
-	scope    *Scope      // function scope, present for package-local signatures
-	recv     *Var        // nil if not a method
-	params   *Tuple      // (incoming) parameters from left to right; or nil
-	results  *Tuple      // (outgoing) results from left to right; or nil
-	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
-}
-
-// NewSignature returns a new function type for the given receiver, parameters,
-// and results, either of which may be nil. If variadic is set, the function
-// is variadic, it must have at least one parameter, and the last parameter
-// must be of unnamed slice type.
-func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
-	if variadic {
-		n := params.Len()
-		if n == 0 {
-			panic("types.NewSignature: variadic function must have at least one parameter")
-		}
-		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
-			panic("types.NewSignature: variadic parameter must be of unnamed slice type")
-		}
-	}
-	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
-}
-
-// Recv returns the receiver of signature s (if a method), or nil if a
-// function. It is ignored when comparing signatures for identity.
-//
-// For an abstract method, Recv returns the enclosing interface either
-// as a *Named or an *Interface. Due to embedding, an interface may
-// contain methods whose receiver type is a different interface.
-func (s *Signature) Recv() *Var { return s.recv }
-
-// _TParams returns the type parameters of signature s, or nil.
-func (s *Signature) _TParams() []*TypeName { return s.tparams }
-
-// _SetTParams sets the type parameters of signature s.
-func (s *Signature) _SetTParams(tparams []*TypeName) { s.tparams = tparams }
-
-// Params returns the parameters of signature s, or nil.
-func (s *Signature) Params() *Tuple { return s.params }
-
-// Results returns the results of signature s, or nil.
-func (s *Signature) Results() *Tuple { return s.results }
-
-// Variadic reports whether the signature s is variadic.
-func (s *Signature) Variadic() bool { return s.variadic }
-
-// A _Sum represents a set of possible types.
-// Sums are currently used to represent type lists of interfaces
-// and thus the underlying types of type parameters; they are not
-// first class types of Go.
-type _Sum struct {
-	types []Type // types are unique
-}
-
-// _NewSum returns a new Sum type consisting of the provided
-// types if there are more than one. If there is exactly one
-// type, it returns that type. If the list of types is empty
-// the result is nil.
-func _NewSum(types []Type) Type {
-	if len(types) == 0 {
-		return nil
-	}
-
-	// What should happen if types contains a sum type?
-	// Do we flatten the types list? For now we check
-	// and panic. This should not be possible for the
-	// current use case of type lists.
-	// TODO(gri) Come up with the rules for sum types.
-	for _, t := range types {
-		if _, ok := t.(*_Sum); ok {
-			panic("sum type contains sum type - unimplemented")
-		}
-	}
-
-	if len(types) == 1 {
-		return types[0]
-	}
-	return &_Sum{types: types}
-}
-
-// is reports whether all types in t satisfy pred.
-func (s *_Sum) is(pred func(Type) bool) bool {
-	if s == nil {
-		return false
-	}
-	for _, t := range s.types {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// An Interface represents an interface type.
-type Interface struct {
-	methods   []*Func // ordered list of explicitly declared methods
-	types     Type    // (possibly a Sum) type declared with a type list (TODO(gri) need better field name)
-	embeddeds []Type  // ordered list of explicitly embedded types
-
-	allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)
-	allTypes   Type    // intersection of all embedded and locally declared types  (TODO(gri) need better field name)
-
-	obj Object // type declaration defining this interface; or nil (for better error messages)
-}
-
-// unpack unpacks a type into a list of types.
-// TODO(gri) Try to eliminate the need for this function.
-func unpackType(typ Type) []Type {
-	if typ == nil {
-		return nil
-	}
-	if sum := asSum(typ); sum != nil {
-		return sum.types
-	}
-	return []Type{typ}
-}
-
-// is reports whether interface t represents types that all satisfy pred.
-func (t *Interface) is(pred func(Type) bool) bool {
-	if t.allTypes == nil {
-		return false // we must have at least one type! (was bug)
-	}
-	for _, t := range unpackType(t.allTypes) {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// emptyInterface represents the empty (completed) interface
-var emptyInterface = Interface{allMethods: markComplete}
-
-// markComplete is used to mark an empty interface as completely
-// set up by setting the allMethods field to a non-nil empty slice.
-var markComplete = make([]*Func, 0)
-
-// NewInterface returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type.
-// NewInterface takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-//
-// Deprecated: Use NewInterfaceType instead which allows any (even non-defined) interface types
-// to be embedded. This is necessary for interfaces that embed alias type names referring to
-// non-defined (literal) interface types.
-func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
-	tnames := make([]Type, len(embeddeds))
-	for i, t := range embeddeds {
-		tnames[i] = t
-	}
-	return NewInterfaceType(methods, tnames)
-}
-
-// NewInterfaceType returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type (this property is not
-// verified for defined types, which may be in the process of being set up and which don't
-// have a valid underlying type yet).
-// NewInterfaceType takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
-	if len(methods) == 0 && len(embeddeds) == 0 {
-		return &emptyInterface
-	}
-
-	// set method receivers if necessary
-	typ := new(Interface)
-	for _, m := range methods {
-		if sig := m.typ.(*Signature); sig.recv == nil {
-			sig.recv = NewVar(m.pos, m.pkg, "", typ)
-		}
-	}
-
-	// All embedded types should be interfaces; however, defined types
-	// may not yet be fully resolved. Only verify that non-defined types
-	// are interfaces. This matches the behavior of the code before the
-	// fix for #25301 (issue #25596).
-	for _, t := range embeddeds {
-		if _, ok := t.(*Named); !ok && !IsInterface(t) {
-			panic("embedded type is not an interface")
-		}
-	}
-
-	// sort for API stability
-	sortMethods(methods)
-	sortTypes(embeddeds)
-
-	typ.methods = methods
-	typ.embeddeds = embeddeds
-	return typ
-}
-
-// NumExplicitMethods returns the number of explicitly declared methods of interface t.
-func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
-
-// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
-// The methods are ordered by their unique Id.
-func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
-
-// NumEmbeddeds returns the number of embedded types in interface t.
-func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
-
-// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
-// The result is nil if the i'th embedded type is not a defined type.
-//
-// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
-func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
-
-// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
-func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
-
-// NumMethods returns the total number of methods of interface t.
-// The interface must have been completed.
-func (t *Interface) NumMethods() int { t.assertCompleteness(); return len(t.allMethods) }
-
-func (t *Interface) assertCompleteness() {
-	if t.allMethods == nil {
-		panic("interface is incomplete")
-	}
-}
-
-// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
-// The methods are ordered by their unique Id.
-// The interface must have been completed.
-func (t *Interface) Method(i int) *Func { t.assertCompleteness(); return t.allMethods[i] }
-
-// Empty reports whether t is the empty interface.
-func (t *Interface) Empty() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		// A non-nil allTypes may still be empty and represents the bottom type.
-		return len(t.allMethods) == 0 && t.allTypes == nil
-	}
-	return !t.iterate(func(t *Interface) bool {
-		return len(t.methods) > 0 || t.types != nil
-	}, nil)
-}
-
-// _HasTypeList reports whether interface t has a type list, possibly from an embedded type.
-func (t *Interface) _HasTypeList() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		return t.allTypes != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		return t.types != nil
-	}, nil)
-}
-
-// _IsComparable reports whether interface t is or embeds the predeclared interface "comparable".
-func (t *Interface) _IsComparable() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// _IsConstraint reports t.HasTypeList() || t.IsComparable().
-func (t *Interface) _IsConstraint() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		if t.allTypes != nil {
-			return true
-		}
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		if t.types != nil {
-			return true
-		}
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// iterate calls f with t and then with any embedded interface of t, recursively, until f returns true.
-// iterate reports whether any call to f returned true.
-func (t *Interface) iterate(f func(*Interface) bool, seen map[*Interface]bool) bool {
-	if f(t) {
-		return true
-	}
-	for _, e := range t.embeddeds {
-		// e should be an interface but be careful (it may be invalid)
-		if e := asInterface(e); e != nil {
-			// Cyclic interfaces such as "type E interface { E }" are not permitted
-			// but they are still constructed and we need to detect such cycles.
-			if seen[e] {
-				continue
-			}
-			if seen == nil {
-				seen = make(map[*Interface]bool)
-			}
-			seen[e] = true
-			if e.iterate(f, seen) {
-				return true
-			}
-		}
-	}
-	return false
-}
-
-// isSatisfiedBy reports whether interface t's type list is satisfied by the type typ.
-// If the type list is empty (absent), typ trivially satisfies the interface.
-// TODO(gri) This is not a great name. Eventually, we should have a more comprehensive
-//           "implements" predicate.
-func (t *Interface) isSatisfiedBy(typ Type) bool {
-	t.Complete()
-	if t.allTypes == nil {
-		return true
-	}
-	types := unpackType(t.allTypes)
-	return includes(types, typ) || includes(types, under(typ))
-}
-
-// Complete computes the interface's method set. It must be called by users of
-// NewInterfaceType and NewInterface after the interface's embedded types are
-// fully defined and before using the interface type in any way other than to
-// form other types. The interface must not contain duplicate methods or a
-// panic occurs. Complete returns the receiver.
-func (t *Interface) Complete() *Interface {
-	// TODO(gri) consolidate this method with Checker.completeInterface
-	if t.allMethods != nil {
-		return t
-	}
-
-	t.allMethods = markComplete // avoid infinite recursion
-
-	var todo []*Func
-	var methods []*Func
-	var seen objset
-	addMethod := func(m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-		case explicit:
-			panic("duplicate method " + m.name)
-		default:
-			// check method signatures after all locally embedded interfaces are computed
-			todo = append(todo, m, other.(*Func))
-		}
-	}
-
-	for _, m := range t.methods {
-		addMethod(m, true)
-	}
-
-	allTypes := t.types
+// top represents the top of the type lattice.
+// It is the underlying type of a type parameter that
+// can be satisfied by any type (ignoring methods),
+// because its type constraint contains no restrictions
+// besides methods.
+type top struct{}
 
-	for _, typ := range t.embeddeds {
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				panic(fmt.Sprintf("%s is not an interface", typ))
-			}
-			continue
-		}
-		etyp.Complete()
-		for _, m := range etyp.allMethods {
-			addMethod(m, false)
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
+// theTop is the singleton top type.
+var theTop = &top{}
 
-	for i := 0; i < len(todo); i += 2 {
-		m := todo[i]
-		other := todo[i+1]
-		if !Identical(m.typ, other.typ) {
-			panic("duplicate method " + m.name)
-		}
-	}
+func (t *top) Underlying() Type { return t }
+func (t *top) String() string   { return TypeString(t, nil) }
 
-	if methods != nil {
-		sortMethods(methods)
-		t.allMethods = methods
+// under returns the true expanded underlying type.
+// If it doesn't exist, the result is Typ[Invalid].
+// under must only be called when a type is known
+// to be fully set up.
+func under(t Type) Type {
+	// TODO(gri) is this correct for *Union?
+	if n := asNamed(t); n != nil {
+		return n.under()
 	}
-	t.allTypes = allTypes
-
 	return t
 }
 
-// A Map represents a map type.
-type Map struct {
-	key, elem Type
-}
-
-// NewMap returns a new map for the given key and element types.
-func NewMap(key, elem Type) *Map {
-	return &Map{key: key, elem: elem}
-}
-
-// Key returns the key type of map m.
-func (m *Map) Key() Type { return m.key }
-
-// Elem returns the element type of map m.
-func (m *Map) Elem() Type { return m.elem }
-
-// A Chan represents a channel type.
-type Chan struct {
-	dir  ChanDir
-	elem Type
-}
-
-// A ChanDir value indicates a channel direction.
-type ChanDir int
-
-// The direction of a channel is indicated by one of these constants.
-const (
-	SendRecv ChanDir = iota
-	SendOnly
-	RecvOnly
-)
-
-// NewChan returns a new channel type for the given direction and element type.
-func NewChan(dir ChanDir, elem Type) *Chan {
-	return &Chan{dir: dir, elem: elem}
-}
-
-// Dir returns the direction of channel c.
-func (c *Chan) Dir() ChanDir { return c.dir }
-
-// Elem returns the element type of channel c.
-func (c *Chan) Elem() Type { return c.elem }
-
-// A Named represents a named (defined) type.
-type Named struct {
-	check      *Checker    // for Named.under implementation; nilled once under has been called
-	info       typeInfo    // for cycle detection
-	obj        *TypeName   // corresponding declared object
-	orig       Type        // type (on RHS of declaration) this *Named type is derived of (for cycle reporting)
-	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
-	tparams    []*TypeName // type parameters, or nil
-	targs      []Type      // type arguments (after instantiation), or nil
-	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
-}
-
-// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
-// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
-// The underlying type must not be a *Named.
-func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
-	if _, ok := underlying.(*Named); ok {
-		panic("types.NewNamed: underlying type must not be *Named")
-	}
-	return (*Checker)(nil).newNamed(obj, underlying, methods)
-}
-
-func (check *Checker) newNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
-	typ := &Named{check: check, obj: obj, orig: underlying, underlying: underlying, methods: methods}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	// Ensure that typ is always expanded, at which point the check field can be
-	// nilled out.
-	//
-	// Note that currently we cannot nil out check inside typ.under(), because
-	// it's possible that typ is expanded multiple times.
-	//
-	// TODO(rFindley): clean this up so that under is the only function mutating
-	//                 named types.
-	if check != nil {
-		check.later(func() {
-			switch typ.under().(type) {
-			case *Named, *instance:
-				panic("internal error: unexpanded underlying type")
-			}
-			typ.check = nil
-		})
-	}
-	return typ
-}
-
-// Obj returns the type name for the named type t.
-func (t *Named) Obj() *TypeName { return t.obj }
-
-// TODO(gri) Come up with a better representation and API to distinguish
-//           between parameterized instantiated and non-instantiated types.
-
-// _TParams returns the type parameters of the named type t, or nil.
-// The result is non-nil for an (originally) parameterized type even if it is instantiated.
-func (t *Named) _TParams() []*TypeName { return t.tparams }
-
-// _TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
-func (t *Named) _TArgs() []Type { return t.targs }
-
-// _SetTArgs sets the type arguments of Named.
-func (t *Named) _SetTArgs(args []Type) { t.targs = args }
-
-// NumMethods returns the number of explicit methods whose receiver is named type t.
-func (t *Named) NumMethods() int { return len(t.methods) }
-
-// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
-func (t *Named) Method(i int) *Func { return t.methods[i] }
-
-// SetUnderlying sets the underlying type and marks t as complete.
-func (t *Named) SetUnderlying(underlying Type) {
-	if underlying == nil {
-		panic("types.Named.SetUnderlying: underlying type must not be nil")
-	}
-	if _, ok := underlying.(*Named); ok {
-		panic("types.Named.SetUnderlying: underlying type must not be *Named")
-	}
-	t.underlying = underlying
-}
-
-// AddMethod adds method m unless it is already in the method list.
-func (t *Named) AddMethod(m *Func) {
-	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
-		t.methods = append(t.methods, m)
-	}
-}
-
-// Note: This is a uint32 rather than a uint64 because the
-// respective 64 bit atomic instructions are not available
-// on all platforms.
-var lastId uint32
-
-// nextId returns a value increasing monotonically by 1 with
-// each call, starting with 1. It may be called concurrently.
-func nextId() uint64 { return uint64(atomic.AddUint32(&lastId, 1)) }
-
-// A _TypeParam represents a type parameter type.
-type _TypeParam struct {
-	check *Checker  // for lazy type bound completion
-	id    uint64    // unique id
-	obj   *TypeName // corresponding type name
-	index int       // parameter index
-	bound Type      // *Named or *Interface; underlying type is always *Interface
-}
-
-// newTypeParam returns a new TypeParam.
-func (check *Checker) newTypeParam(obj *TypeName, index int, bound Type) *_TypeParam {
-	assert(bound != nil)
-	typ := &_TypeParam{check: check, id: nextId(), obj: obj, index: index, bound: bound}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	return typ
-}
-
-func (t *_TypeParam) Bound() *Interface {
-	iface := asInterface(t.bound)
-	// use the type bound position if we have one
-	pos := token.NoPos
-	if n, _ := t.bound.(*Named); n != nil {
-		pos = n.obj.pos
-	}
-	// TODO(rFindley) switch this to an unexported method on Checker.
-	t.check.completeInterface(pos, iface)
-	return iface
-}
-
 // optype returns a type's operational type. Except for
 // type parameters, the operational type is the same
 // as the underlying type (as returned by under). For
-// Type parameters, the operational type is determined
-// by the corresponding type bound's type list. The
-// result may be the bottom or top type, but it is never
-// the incoming type parameter.
+// Type parameters, the operational type is the structural
+// type, if any; otherwise it's the top type.
+// The result is never the incoming type parameter.
 func optype(typ Type) Type {
 	if t := asTypeParam(typ); t != nil {
+		// TODO(gri) review accuracy of this comment
 		// If the optype is typ, return the top type as we have
 		// no information. It also prevents infinite recursion
 		// via the asTypeParam converter function. This can happen
 		// for a type parameter list of the form:
 		// (type T interface { type T }).
 		// See also issue #39680.
-		if u := t.Bound().allTypes; u != nil && u != typ {
-			// u != typ and u is a type parameter => under(u) != typ, so this is ok
-			return under(u)
+		if u := t.structuralType(); u != nil {
+			assert(u != typ) // "naked" type parameters cannot be embedded
+			return u
 		}
 		return theTop
 	}
 	return under(typ)
 }
 
-// An instance represents an instantiated generic type syntactically
-// (without expanding the instantiation). Type instances appear only
-// during type-checking and are replaced by their fully instantiated
-// (expanded) types before the end of type-checking.
-type instance struct {
-	check   *Checker    // for lazy instantiation
-	pos     token.Pos   // position of type instantiation; for error reporting only
-	base    *Named      // parameterized type to be instantiated
-	targs   []Type      // type arguments
-	poslist []token.Pos // position of each targ; for error reporting only
-	value   Type        // base(targs...) after instantiation or Typ[Invalid]; nil if not yet set
-}
-
-// expand returns the instantiated (= expanded) type of t.
-// The result is either an instantiated *Named type, or
-// Typ[Invalid] if there was an error.
-func (t *instance) expand() Type {
-	v := t.value
-	if v == nil {
-		v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist)
-		if v == nil {
-			v = Typ[Invalid]
-		}
-		t.value = v
-	}
-	// After instantiation we must have an invalid or a *Named type.
-	if debug && v != Typ[Invalid] {
-		_ = v.(*Named)
-	}
-	return v
-}
-
-// expand expands a type instance into its instantiated
-// type and leaves all other types alone. expand does
-// not recurse.
-func expand(typ Type) Type {
-	if t, _ := typ.(*instance); t != nil {
-		return t.expand()
-	}
-	return typ
-}
-
-// expandf is set to expand.
-// Call expandf when calling expand causes compile-time cycle error.
-var expandf func(Type) Type
-
-func init() { expandf = expand }
-
-// bottom represents the bottom of the type lattice.
-// It is the underlying type of a type parameter that
-// cannot be satisfied by any type, usually because
-// the intersection of type constraints left nothing).
-type bottom struct{}
-
-// theBottom is the singleton bottom type.
-var theBottom = &bottom{}
-
-// top represents the top of the type lattice.
-// It is the underlying type of a type parameter that
-// can be satisfied by any type (ignoring methods),
-// usually because the type constraint has no type
-// list.
-type top struct{}
-
-// theTop is the singleton top type.
-var theTop = &top{}
-
-// Type-specific implementations of Underlying.
-func (t *Basic) Underlying() Type      { return t }
-func (t *Array) Underlying() Type      { return t }
-func (t *Slice) Underlying() Type      { return t }
-func (t *Struct) Underlying() Type     { return t }
-func (t *Pointer) Underlying() Type    { return t }
-func (t *Tuple) Underlying() Type      { return t }
-func (t *Signature) Underlying() Type  { return t }
-func (t *_Sum) Underlying() Type       { return t }
-func (t *Interface) Underlying() Type  { return t }
-func (t *Map) Underlying() Type        { return t }
-func (t *Chan) Underlying() Type       { return t }
-func (t *Named) Underlying() Type      { return t.underlying }
-func (t *_TypeParam) Underlying() Type { return t }
-func (t *instance) Underlying() Type   { return t }
-func (t *bottom) Underlying() Type     { return t }
-func (t *top) Underlying() Type        { return t }
-
-// Type-specific implementations of String.
-func (t *Basic) String() string      { return TypeString(t, nil) }
-func (t *Array) String() string      { return TypeString(t, nil) }
-func (t *Slice) String() string      { return TypeString(t, nil) }
-func (t *Struct) String() string     { return TypeString(t, nil) }
-func (t *Pointer) String() string    { return TypeString(t, nil) }
-func (t *Tuple) String() string      { return TypeString(t, nil) }
-func (t *Signature) String() string  { return TypeString(t, nil) }
-func (t *_Sum) String() string       { return TypeString(t, nil) }
-func (t *Interface) String() string  { return TypeString(t, nil) }
-func (t *Map) String() string        { return TypeString(t, nil) }
-func (t *Chan) String() string       { return TypeString(t, nil) }
-func (t *Named) String() string      { return TypeString(t, nil) }
-func (t *_TypeParam) String() string { return TypeString(t, nil) }
-func (t *instance) String() string   { return TypeString(t, nil) }
-func (t *bottom) String() string     { return TypeString(t, nil) }
-func (t *top) String() string        { return TypeString(t, nil) }
-
-// under returns the true expanded underlying type.
-// If it doesn't exist, the result is Typ[Invalid].
-// under must only be called when a type is known
-// to be fully set up.
-func under(t Type) Type {
-	// TODO(gri) is this correct for *Sum?
-	if n := asNamed(t); n != nil {
-		return n.under()
-	}
-	return t
-}
-
 // Converters
 //
 // A converter must only be called when a type is
@@ -941,46 +98,29 @@ func asPointer(t Type) *Pointer {
 	return op
 }
 
-func asTuple(t Type) *Tuple {
-	op, _ := optype(t).(*Tuple)
-	return op
-}
-
 func asSignature(t Type) *Signature {
 	op, _ := optype(t).(*Signature)
 	return op
 }
 
-func asSum(t Type) *_Sum {
-	op, _ := optype(t).(*_Sum)
-	return op
-}
+// If the argument to asInterface, asNamed, or asTypeParam is of the respective type
+// (possibly after expanding an instance type), these methods return that type.
+// Otherwise the result is nil.
 
 func asInterface(t Type) *Interface {
 	op, _ := optype(t).(*Interface)
 	return op
 }
 
-func asMap(t Type) *Map {
-	op, _ := optype(t).(*Map)
-	return op
-}
-
-func asChan(t Type) *Chan {
-	op, _ := optype(t).(*Chan)
-	return op
-}
-
-// If the argument to asNamed and asTypeParam is of the respective types
-// (possibly after expanding an instance type), these methods return that type.
-// Otherwise the result is nil.
-
 func asNamed(t Type) *Named {
-	e, _ := expand(t).(*Named)
+	e, _ := t.(*Named)
+	if e != nil {
+		e.expand(nil)
+	}
 	return e
 }
 
-func asTypeParam(t Type) *_TypeParam {
-	u, _ := under(t).(*_TypeParam)
+func asTypeParam(t Type) *TypeParam {
+	u, _ := under(t).(*TypeParam)
 	return u
 }
diff --git a/src/go/types/typelists.go b/src/go/types/typelists.go
new file mode 100644
index 0000000000000000000000000000000000000000..a8181404bf732256293a4c2458d941d17231be1a
--- /dev/null
+++ b/src/go/types/typelists.go
@@ -0,0 +1,61 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// TParamList holds a list of type parameters.
+type TParamList struct{ tparams []*TypeParam }
+
+// Len returns the number of type parameters in the list.
+// It is safe to call on a nil receiver.
+func (l *TParamList) Len() int { return len(l.list()) }
+
+// At returns the i'th type parameter in the list.
+func (l *TParamList) At(i int) *TypeParam { return l.tparams[i] }
+
+// list is for internal use where we expect a []*TypeParam.
+// TODO(rfindley): list should probably be eliminated: we can pass around a
+// TParamList instead.
+func (l *TParamList) list() []*TypeParam {
+	if l == nil {
+		return nil
+	}
+	return l.tparams
+}
+
+// TypeList holds a list of types.
+type TypeList struct{ types []Type }
+
+// Len returns the number of types in the list.
+// It is safe to call on a nil receiver.
+func (l *TypeList) Len() int { return len(l.list()) }
+
+// At returns the i'th type in the list.
+func (l *TypeList) At(i int) Type { return l.types[i] }
+
+// list is for internal use where we expect a []Type.
+// TODO(rfindley): list should probably be eliminated: we can pass around a
+// TypeList instead.
+func (l *TypeList) list() []Type {
+	if l == nil {
+		return nil
+	}
+	return l.types
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func bindTParams(list []*TypeParam) *TParamList {
+	if len(list) == 0 {
+		return nil
+	}
+	for i, typ := range list {
+		if typ.index >= 0 {
+			panic("type parameter bound more than once")
+		}
+		typ.index = i
+	}
+	return &TParamList{tparams: list}
+}
diff --git a/src/go/types/typeparam.go b/src/go/types/typeparam.go
new file mode 100644
index 0000000000000000000000000000000000000000..b6952489ca94e14ba3f03dccf25f2811bb4bb679
--- /dev/null
+++ b/src/go/types/typeparam.go
@@ -0,0 +1,113 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/token"
+	"sync/atomic"
+)
+
+// Note: This is a uint32 rather than a uint64 because the
+// respective 64 bit atomic instructions are not available
+// on all platforms.
+var lastID uint32
+
+// nextID returns a value increasing monotonically by 1 with
+// each call, starting with 1. It may be called concurrently.
+func nextID() uint64 { return uint64(atomic.AddUint32(&lastID, 1)) }
+
+// A TypeParam represents a type parameter type.
+type TypeParam struct {
+	check *Checker  // for lazy type bound completion
+	id    uint64    // unique id, for debugging only
+	obj   *TypeName // corresponding type name
+	index int       // type parameter index in source order, starting at 0
+	// TODO(rfindley): this could also be Typ[Invalid]. Verify that this is handled correctly.
+	bound Type // *Named or *Interface; underlying type is always *Interface
+}
+
+// NewTypeParam returns a new TypeParam. Type parameters may be set on a Named
+// or Signature type by calling SetTParams. Setting a type parameter on more
+// than one type will result in a panic.
+//
+// The bound argument can be nil, and set later via SetBound.
+func (check *Checker) NewTypeParam(obj *TypeName, bound Type) *TypeParam {
+	// Always increment lastID, even if it is not used.
+	id := nextID()
+	if check != nil {
+		check.nextID++
+		id = check.nextID
+	}
+	typ := &TypeParam{check: check, id: id, obj: obj, index: -1, bound: bound}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	return typ
+}
+
+// TODO(rfindley): remove or export these placeholder APIs.
+
+// Index returns the index of the type param within its param list.
+func (t *TypeParam) _Index() int {
+	return t.index
+}
+
+// SetId sets the unique id of a type param. Should only be used for type params
+// in imported generic types.
+func (t *TypeParam) _SetId(id uint64) {
+	t.id = id
+}
+
+// Obj returns the type name for t.
+func (t *TypeParam) Obj() *TypeName { return t.obj }
+
+// Constraint returns the type constraint specified for t.
+func (t *TypeParam) Constraint() Type {
+	// compute the type set if possible (we may not have an interface)
+	if iface, _ := under(t.bound).(*Interface); iface != nil {
+		// use the type bound position if we have one
+		pos := token.NoPos
+		if n, _ := t.bound.(*Named); n != nil {
+			pos = n.obj.pos
+		}
+		computeInterfaceTypeSet(t.check, pos, iface)
+	}
+	return t.bound
+}
+
+// SetConstraint sets the type constraint for t.
+func (t *TypeParam) SetConstraint(bound Type) {
+	if bound == nil {
+		panic("nil constraint")
+	}
+	t.bound = bound
+}
+
+func (t *TypeParam) Underlying() Type { return t }
+func (t *TypeParam) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// iface returns the constraint interface of t.
+func (t *TypeParam) iface() *Interface {
+	if iface, _ := under(t.Constraint()).(*Interface); iface != nil {
+		return iface
+	}
+	return &emptyInterface
+}
+
+// structuralType returns the structural type of the type parameter's constraint; or nil.
+func (t *TypeParam) structuralType() Type {
+	return t.iface().typeSet().structuralType()
+}
+
+func (t *TypeParam) is(f func(*term) bool) bool {
+	return t.iface().typeSet().is(f)
+}
+
+func (t *TypeParam) underIs(f func(Type) bool) bool {
+	return t.iface().typeSet().underIs(f)
+}
diff --git a/src/go/types/types_test.go b/src/go/types/types_test.go
index 25cd9966282861ebf71827819813f0e9b44908d0..f2358c6e1988ca5898524058d48b67ea550d8303 100644
--- a/src/go/types/types_test.go
+++ b/src/go/types/types_test.go
@@ -4,16 +4,5 @@
 
 package types
 
-import "sync/atomic"
-
-// Upon calling ResetId, nextId starts with 1 again.
-// It may be called concurrently. This is only needed
-// for tests where we may want to have a consistent
-// numbering for each individual test case.
-func ResetId() { atomic.StoreUint32(&lastId, 0) }
-
-// SetGoVersion sets the unexported goVersion field on config, so that tests
-// which assert on behavior for older Go versions can set it.
-func SetGoVersion(config *Config, goVersion string) {
-	config.goVersion = goVersion
-}
+// Debug is set if go/types is built with debug mode enabled.
+const Debug = debug
diff --git a/src/go/types/typeset.go b/src/go/types/typeset.go
new file mode 100644
index 0000000000000000000000000000000000000000..7bdc708d4cc154877e202f85db4ccd4a24ef2b84
--- /dev/null
+++ b/src/go/types/typeset.go
@@ -0,0 +1,390 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"sort"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A _TypeSet represents the type set of an interface.
+type _TypeSet struct {
+	comparable bool // if set, the interface is or embeds comparable
+	// TODO(gri) consider using a set for the methods for faster lookup
+	methods []*Func  // all methods of the interface; sorted by unique ID
+	terms   termlist // type terms of the type set
+}
+
+// IsEmpty reports whether type set s is the empty set.
+func (s *_TypeSet) IsEmpty() bool { return s.terms.isEmpty() }
+
+// IsAll reports whether type set s is the set of all types (corresponding to the empty interface).
+func (s *_TypeSet) IsAll() bool { return !s.comparable && len(s.methods) == 0 && s.terms.isAll() }
+
+// TODO(gri) IsMethodSet is not a great name for this predicate. Find a better one.
+
+// IsMethodSet reports whether the type set s is described by a single set of methods.
+func (s *_TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isAll() }
+
+// IsComparable reports whether each type in the set is comparable.
+func (s *_TypeSet) IsComparable() bool {
+	if s.terms.isAll() {
+		return s.comparable
+	}
+	return s.is(func(t *term) bool {
+		return Comparable(t.typ)
+	})
+}
+
+// TODO(gri) IsTypeSet is not a great name for this predicate. Find a better one.
+
+// IsTypeSet reports whether the type set s is represented by a finite set of underlying types.
+func (s *_TypeSet) IsTypeSet() bool {
+	return !s.comparable && len(s.methods) == 0
+}
+
+// NumMethods returns the number of methods available.
+func (s *_TypeSet) NumMethods() int { return len(s.methods) }
+
+// Method returns the i'th method of type set s for 0 <= i < s.NumMethods().
+// The methods are ordered by their unique ID.
+func (s *_TypeSet) Method(i int) *Func { return s.methods[i] }
+
+// LookupMethod returns the index of and method with matching package and name, or (-1, nil).
+func (s *_TypeSet) LookupMethod(pkg *Package, name string) (int, *Func) {
+	// TODO(gri) s.methods is sorted - consider binary search
+	return lookupMethod(s.methods, pkg, name)
+}
+
+func (s *_TypeSet) String() string {
+	switch {
+	case s.IsEmpty():
+		return "∅"
+	case s.IsAll():
+		return "𝓤"
+	}
+
+	hasMethods := len(s.methods) > 0
+	hasTerms := s.hasTerms()
+
+	var buf bytes.Buffer
+	buf.WriteByte('{')
+	if s.comparable {
+		buf.WriteString(" comparable")
+		if hasMethods || hasTerms {
+			buf.WriteByte(';')
+		}
+	}
+	for i, m := range s.methods {
+		if i > 0 {
+			buf.WriteByte(';')
+		}
+		buf.WriteByte(' ')
+		buf.WriteString(m.String())
+	}
+	if hasMethods && hasTerms {
+		buf.WriteByte(';')
+	}
+	if hasTerms {
+		buf.WriteString(s.terms.String())
+	}
+	buf.WriteString(" }") // there was at least one method or term
+
+	return buf.String()
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (s *_TypeSet) hasTerms() bool              { return !s.terms.isAll() }
+func (s *_TypeSet) structuralType() Type        { return s.terms.structuralType() }
+func (s *_TypeSet) includes(t Type) bool        { return s.terms.includes(t) }
+func (s1 *_TypeSet) subsetOf(s2 *_TypeSet) bool { return s1.terms.subsetOf(s2.terms) }
+
+// TODO(gri) TypeSet.is and TypeSet.underIs should probably also go into termlist.go
+
+var topTerm = term{false, theTop}
+
+func (s *_TypeSet) is(f func(*term) bool) bool {
+	if len(s.terms) == 0 {
+		return false
+	}
+	for _, t := range s.terms {
+		// Terms represent the top term with a nil type.
+		// The rest of the type checker uses the top type
+		// instead. Convert.
+		// TODO(gri) investigate if we can do without this
+		if t.typ == nil {
+			t = &topTerm
+		}
+		if !f(t) {
+			return false
+		}
+	}
+	return true
+}
+
+func (s *_TypeSet) underIs(f func(Type) bool) bool {
+	if len(s.terms) == 0 {
+		return false
+	}
+	for _, t := range s.terms {
+		// see corresponding comment in TypeSet.is
+		u := t.typ
+		if u == nil {
+			u = theTop
+		}
+		// t == under(t) for ~t terms
+		if !t.tilde {
+			u = under(u)
+		}
+		if debug {
+			assert(Identical(u, under(u)))
+		}
+		if !f(u) {
+			return false
+		}
+	}
+	return true
+}
+
+// topTypeSet may be used as type set for the empty interface.
+var topTypeSet = _TypeSet{terms: allTermlist}
+
+// computeInterfaceTypeSet may be called with check == nil.
+func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_TypeSet {
+	if ityp.tset != nil {
+		return ityp.tset
+	}
+
+	// If the interface is not fully set up yet, the type set will
+	// not be complete, which may lead to errors when using the the
+	// type set (e.g. missing method). Don't compute a partial type
+	// set (and don't store it!), so that we still compute the full
+	// type set eventually. Instead, return the top type set and
+	// let any follow-on errors play out.
+	//
+	// TODO(gri) Consider recording when this happens and reporting
+	// it as an error (but only if there were no other errors so to
+	// to not have unnecessary follow-on errors).
+	if !ityp.complete {
+		return &topTypeSet
+	}
+
+	if check != nil && trace {
+		// Types don't generally have position information.
+		// If we don't have a valid pos provided, try to use
+		// one close enough.
+		if !pos.IsValid() && len(ityp.methods) > 0 {
+			pos = ityp.methods[0].pos
+		}
+
+		check.trace(pos, "type set for %s", ityp)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(pos, "=> %s ", ityp.typeSet())
+		}()
+	}
+
+	// An infinitely expanding interface (due to a cycle) is detected
+	// elsewhere (Checker.validType), so here we simply assume we only
+	// have valid interfaces. Mark the interface as complete to avoid
+	// infinite recursion if the validType check occurs later for some
+	// reason.
+	ityp.tset = &_TypeSet{terms: allTermlist} // TODO(gri) is this sufficient?
+
+	// Methods of embedded interfaces are collected unchanged; i.e., the identity
+	// of a method I.m's Func Object of an interface I is the same as that of
+	// the method m in an interface that embeds interface I. On the other hand,
+	// if a method is embedded via multiple overlapping embedded interfaces, we
+	// don't provide a guarantee which "original m" got chosen for the embedding
+	// interface. See also issue #34421.
+	//
+	// If we don't care to provide this identity guarantee anymore, instead of
+	// reusing the original method in embeddings, we can clone the method's Func
+	// Object and give it the position of a corresponding embedded interface. Then
+	// we can get rid of the mpos map below and simply use the cloned method's
+	// position.
+
+	var todo []*Func
+	var seen objset
+	var methods []*Func
+	mpos := make(map[*Func]token.Pos) // method specification or method embedding position, for good error messages
+	addMethod := func(pos token.Pos, m *Func, explicit bool) {
+		switch other := seen.insert(m); {
+		case other == nil:
+			methods = append(methods, m)
+			mpos[m] = pos
+		case explicit:
+			if check == nil {
+				panic(fmt.Sprintf("%v: duplicate method %s", m.pos, m.name))
+			}
+			// check != nil
+			check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
+			check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
+		default:
+			// We have a duplicate method name in an embedded (not explicitly declared) method.
+			// Check method signatures after all types are computed (issue #33656).
+			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
+			// error here as well (even though we could do it eagerly) because it's the same
+			// error message.
+			if check == nil {
+				// check method signatures after all locally embedded interfaces are computed
+				todo = append(todo, m, other.(*Func))
+				break
+			}
+			// check != nil
+			check.later(func() {
+				if !check.allowVersion(m.pkg, 1, 14) || !Identical(m.typ, other.Type()) {
+					check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
+					check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
+				}
+			})
+		}
+	}
+
+	for _, m := range ityp.methods {
+		addMethod(m.pos, m, true)
+	}
+
+	// collect embedded elements
+	var allTerms = allTermlist
+	for i, typ := range ityp.embeddeds {
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
+		var pos token.Pos // embedding position
+		if ityp.embedPos != nil {
+			pos = (*ityp.embedPos)[i]
+		}
+		var terms termlist
+		switch u := under(typ).(type) {
+		case *Interface:
+			tset := computeInterfaceTypeSet(check, pos, u)
+			if tset.comparable {
+				ityp.tset.comparable = true
+			}
+			for _, m := range tset.methods {
+				addMethod(pos, m, false) // use embedding position pos rather than m.pos
+			}
+			terms = tset.terms
+		case *Union:
+			tset := computeUnionTypeSet(check, pos, u)
+			if tset == &invalidTypeSet {
+				continue // ignore invalid unions
+			}
+			terms = tset.terms
+		case *TypeParam:
+			// Embedding stand-alone type parameters is not permitted.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if typ == Typ[Invalid] {
+				continue
+			}
+			if check != nil && !check.allowVersion(check.pkg, 1, 18) {
+				check.errorf(atPos(pos), _InvalidIfaceEmbed, "%s is not an interface", typ)
+				continue
+			}
+			terms = termlist{{false, typ}}
+		}
+		// The type set of an interface is the intersection
+		// of the type sets of all its elements.
+		// Intersection cannot produce longer termlists and
+		// thus cannot overflow.
+		allTerms = allTerms.intersect(terms)
+	}
+	ityp.embedPos = nil // not needed anymore (errors have been reported)
+
+	// process todo's (this only happens if check == nil)
+	for i := 0; i < len(todo); i += 2 {
+		m := todo[i]
+		other := todo[i+1]
+		if !Identical(m.typ, other.typ) {
+			panic(fmt.Sprintf("%v: duplicate method %s", m.pos, m.name))
+		}
+	}
+
+	if methods != nil {
+		sort.Sort(byUniqueMethodName(methods))
+		ityp.tset.methods = methods
+	}
+	ityp.tset.terms = allTerms
+
+	return ityp.tset
+}
+
+func sortMethods(list []*Func) {
+	sort.Sort(byUniqueMethodName(list))
+}
+
+func assertSortedMethods(list []*Func) {
+	if !debug {
+		panic("assertSortedMethods called outside debug mode")
+	}
+	if !sort.IsSorted(byUniqueMethodName(list)) {
+		panic("methods not sorted")
+	}
+}
+
+// byUniqueMethodName method lists can be sorted by their unique method names.
+type byUniqueMethodName []*Func
+
+func (a byUniqueMethodName) Len() int           { return len(a) }
+func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
+func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+// invalidTypeSet is a singleton type set to signal an invalid type set
+// due to an error. It's also a valid empty type set, so consumers of
+// type sets may choose to ignore it.
+var invalidTypeSet _TypeSet
+
+// computeUnionTypeSet may be called with check == nil.
+// The result is &invalidTypeSet if the union overflows.
+func computeUnionTypeSet(check *Checker, pos token.Pos, utyp *Union) *_TypeSet {
+	if utyp.tset != nil {
+		return utyp.tset
+	}
+
+	// avoid infinite recursion (see also computeInterfaceTypeSet)
+	utyp.tset = new(_TypeSet)
+
+	var allTerms termlist
+	for _, t := range utyp.terms {
+		var terms termlist
+		switch u := under(t.typ).(type) {
+		case *Interface:
+			terms = computeInterfaceTypeSet(check, pos, u).terms
+		case *TypeParam:
+			// A stand-alone type parameters is not permitted as union term.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if t.typ == Typ[Invalid] {
+				continue
+			}
+			terms = termlist{(*term)(t)}
+		}
+		// The type set of a union expression is the union
+		// of the type sets of each term.
+		allTerms = allTerms.union(terms)
+		if len(allTerms) > maxTermCount {
+			if check != nil {
+				check.errorf(atPos(pos), _Todo, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+			}
+			utyp.tset = &invalidTypeSet
+			return utyp.tset
+		}
+	}
+	utyp.tset.terms = allTerms
+
+	return utyp.tset
+}
diff --git a/src/go/types/typeset_test.go b/src/go/types/typeset_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..4fd1aa247d75645bf154f814762d379472cd215a
--- /dev/null
+++ b/src/go/types/typeset_test.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import "testing"
+
+func TestInvalidTypeSet(t *testing.T) {
+	if !invalidTypeSet.IsEmpty() {
+		t.Error("invalidTypeSet is not empty")
+	}
+}
+
+// TODO(gri) add more tests
diff --git a/src/go/types/typestring.go b/src/go/types/typestring.go
index fe27f0f276c30e5127b2a0d61c1145b56b1105cf..cdc7ea9f512d4761b2542e22078d4c2052f3da09 100644
--- a/src/go/types/typestring.go
+++ b/src/go/types/typestring.go
@@ -40,27 +40,6 @@ func RelativeTo(pkg *Package) Qualifier {
 	}
 }
 
-// If gcCompatibilityMode is set, printing of types is modified
-// to match the representation of some types in the gc compiler:
-//
-//	- byte and rune lose their alias name and simply stand for
-//	  uint8 and int32 respectively
-//	- embedded interfaces get flattened (the embedding info is lost,
-//	  and certain recursive interface types cannot be printed anymore)
-//
-// This makes it easier to compare packages computed with the type-
-// checker vs packages imported from gc export data.
-//
-// Caution: This flag affects all uses of WriteType, globally.
-// It is only provided for testing in conjunction with
-// gc-generated data.
-//
-// This flag is exported in the x/tools/go/types package. We don't
-// need it at the moment in the std repo and so we don't export it
-// anymore. We should eventually try to remove it altogether.
-// TODO(gri) remove this
-var gcCompatibilityMode bool
-
 // TypeString returns the string representation of typ.
 // The Qualifier controls the printing of
 // package-level objects, and may be nil.
@@ -107,16 +86,6 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 				break
 			}
 		}
-
-		if gcCompatibilityMode {
-			// forget the alias names
-			switch t.kind {
-			case Byte:
-				t = Typ[Uint8]
-			case Rune:
-				t = Typ[Int32]
-			}
-		}
 		buf.WriteString(t.name)
 
 	case *Array:
@@ -158,80 +127,40 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		buf.WriteString("func")
 		writeSignature(buf, t, qf, visited)
 
-	case *_Sum:
-		for i, t := range t.types {
+	case *Union:
+		// Unions only appear as (syntactic) embedded elements
+		// in interfaces and syntactically cannot be empty.
+		if t.Len() == 0 {
+			panic("empty union")
+		}
+		for i, t := range t.terms {
 			if i > 0 {
-				buf.WriteString(", ")
+				buf.WriteByte('|')
 			}
-			writeType(buf, t, qf, visited)
+			if t.tilde {
+				buf.WriteByte('~')
+			}
+			writeType(buf, t.typ, qf, visited)
 		}
 
 	case *Interface:
-		// We write the source-level methods and embedded types rather
-		// than the actual method set since resolved method signatures
-		// may have non-printable cycles if parameters have embedded
-		// interface types that (directly or indirectly) embed the
-		// current interface. For instance, consider the result type
-		// of m:
-		//
-		//     type T interface{
-		//         m() interface{ T }
-		//     }
-		//
 		buf.WriteString("interface{")
-		empty := true
-		if gcCompatibilityMode {
-			// print flattened interface
-			// (useful to compare against gc-generated interfaces)
-			for i, m := range t.allMethods {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				buf.WriteString(m.name)
-				writeSignature(buf, m.typ.(*Signature), qf, visited)
-				empty = false
-			}
-			if !empty && t.allTypes != nil {
-				buf.WriteString("; ")
-			}
-			if t.allTypes != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.allTypes, qf, visited)
-			}
-		} else {
-			// print explicit interface methods and embedded types
-			for i, m := range t.methods {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				buf.WriteString(m.name)
-				writeSignature(buf, m.typ.(*Signature), qf, visited)
-				empty = false
-			}
-			if !empty && t.types != nil {
+		first := true
+		// print explicit interface methods and embedded types
+		for _, m := range t.methods {
+			if !first {
 				buf.WriteString("; ")
 			}
-			if t.types != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.types, qf, visited)
-				empty = false
-			}
-			if !empty && len(t.embeddeds) > 0 {
-				buf.WriteString("; ")
-			}
-			for i, typ := range t.embeddeds {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				writeType(buf, typ, qf, visited)
-				empty = false
-			}
+			first = false
+			buf.WriteString(m.name)
+			writeSignature(buf, m.typ.(*Signature), qf, visited)
 		}
-		if t.allMethods == nil || len(t.methods) > len(t.allMethods) {
-			if !empty {
-				buf.WriteByte(' ')
+		for _, typ := range t.embeddeds {
+			if !first {
+				buf.WriteString("; ")
 			}
-			buf.WriteString("/* incomplete */")
+			first = false
+			writeType(buf, typ, qf, visited)
 		}
 		buf.WriteByte('}')
 
@@ -256,7 +185,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		case RecvOnly:
 			s = "<-chan "
 		default:
-			panic("unreachable")
+			unreachable()
 		}
 		buf.WriteString(s)
 		if parens {
@@ -268,39 +197,40 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 		}
 
 	case *Named:
+		if t.instance != nil {
+			buf.WriteByte(instanceMarker)
+		}
 		writeTypeName(buf, t.obj, qf)
 		if t.targs != nil {
 			// instantiated type
 			buf.WriteByte('[')
-			writeTypeList(buf, t.targs, qf, visited)
+			writeTypeList(buf, t.targs.list(), qf, visited)
 			buf.WriteByte(']')
-		} else if t.tparams != nil {
+		} else if t.TParams().Len() != 0 {
 			// parameterized type
-			writeTParamList(buf, t.tparams, qf, visited)
+			writeTParamList(buf, t.TParams().list(), qf, visited)
 		}
 
-	case *_TypeParam:
+	case *TypeParam:
 		s := "?"
 		if t.obj != nil {
+			// Optionally write out package for typeparams (like Named).
+			// TODO(rfindley): this is required for import/export, so
+			// we maybe need a separate function that won't be changed
+			// for debugging purposes.
+			if t.obj.pkg != nil {
+				writePackage(buf, t.obj.pkg, qf)
+			}
 			s = t.obj.name
 		}
 		buf.WriteString(s + subscript(t.id))
 
-	case *instance:
-		buf.WriteByte(instanceMarker) // indicate "non-evaluated" syntactic instance
-		writeTypeName(buf, t.base.obj, qf)
-		buf.WriteByte('[')
-		writeTypeList(buf, t.targs, qf, visited)
-		buf.WriteByte(']')
-
-	case *bottom:
-		buf.WriteString("⊥")
-
 	case *top:
 		buf.WriteString("⊤")
 
 	default:
 		// For externally defined implementations of Type.
+		// Note: In this case cycles won't be caught.
 		buf.WriteString(t.String())
 	}
 }
@@ -314,30 +244,33 @@ func writeTypeList(buf *bytes.Buffer, list []Type, qf Qualifier, visited []Type)
 	}
 }
 
-func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited []Type) {
+func writeTParamList(buf *bytes.Buffer, list []*TypeParam, qf Qualifier, visited []Type) {
 	// TODO(rFindley) compare this with the corresponding implementation in types2
 	buf.WriteString("[")
 	var prev Type
-	for i, p := range list {
-		// TODO(rFindley) support 'any' sugar here.
-		var b Type = &emptyInterface
-		if t, _ := p.typ.(*_TypeParam); t != nil && t.bound != nil {
-			b = t.bound
+	for i, tpar := range list {
+		// Determine the type parameter and its constraint.
+		// list is expected to hold type parameter names,
+		// but don't crash if that's not the case.
+		var bound Type
+		if tpar != nil {
+			bound = tpar.bound // should not be nil but we want to see it if it is
 		}
+
 		if i > 0 {
-			if b != prev {
-				// type bound changed - write previous one before advancing
+			if bound != prev {
+				// bound changed - write previous one before advancing
 				buf.WriteByte(' ')
 				writeType(buf, prev, qf, visited)
 			}
 			buf.WriteString(", ")
 		}
-		prev = b
+		prev = bound
 
-		if t, _ := p.typ.(*_TypeParam); t != nil {
-			writeType(buf, t, qf, visited)
+		if tpar != nil {
+			writeType(buf, tpar, qf, visited)
 		} else {
-			buf.WriteString(p.name)
+			buf.WriteString(tpar.obj.name)
 		}
 	}
 	if prev != nil {
@@ -348,17 +281,38 @@ func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited
 }
 
 func writeTypeName(buf *bytes.Buffer, obj *TypeName, qf Qualifier) {
-	s := ""
-	if obj != nil {
-		if obj.pkg != nil {
-			writePackage(buf, obj.pkg, qf)
+	if obj == nil {
+		buf.WriteString("")
+		return
+	}
+	if obj.pkg != nil {
+		writePackage(buf, obj.pkg, qf)
+	}
+	buf.WriteString(obj.name)
+
+	if instanceHashing != 0 {
+		// For local defined types, use the (original!) TypeName's scope
+		// numbers to disambiguate.
+		typ := obj.typ.(*Named)
+		// TODO(gri) Figure out why typ.orig != typ.orig.orig sometimes
+		//           and whether the loop can iterate more than twice.
+		//           (It seems somehow connected to instance types.)
+		for typ.orig != typ {
+			typ = typ.orig
 		}
-		// TODO(gri): function-local named types should be displayed
-		// differently from named types at package level to avoid
-		// ambiguity.
-		s = obj.name
+		writeScopeNumbers(buf, typ.obj.parent)
+	}
+}
+
+// writeScopeNumbers writes the number sequence for this scope to buf
+// in the form ".i.j.k" where i, j, k, etc. stand for scope numbers.
+// If a scope is nil or has no parent (such as a package scope), nothing
+// is written.
+func writeScopeNumbers(buf *bytes.Buffer, s *Scope) {
+	if s != nil && s.number > 0 {
+		writeScopeNumbers(buf, s.parent)
+		fmt.Fprintf(buf, ".%d", s.number)
 	}
-	buf.WriteString(s)
 }
 
 func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
@@ -381,7 +335,7 @@ func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visi
 					// special case:
 					// append(s, "foo"...) leads to signature func([]byte, string...)
 					if t := asBasic(typ); t == nil || t.kind != String {
-						panic("internal error: string type expected")
+						panic("expected string type")
 					}
 					writeType(buf, typ, qf, visited)
 					buf.WriteString("...")
@@ -403,8 +357,8 @@ func WriteSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier) {
 }
 
 func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
-	if sig.tparams != nil {
-		writeTParamList(buf, sig.tparams, qf, visited)
+	if sig.TParams().Len() != 0 {
+		writeTParamList(buf, sig.TParams().list(), qf, visited)
 	}
 
 	writeTuple(buf, sig.params, sig.variadic, qf, visited)
diff --git a/src/go/types/typestring_test.go b/src/go/types/typestring_test.go
index b16529dc64155cc306d1233d30b5d3d921dbf764..ddbb2884b6c7f2ccd08b2cd16e3e6c4982d88a81 100644
--- a/src/go/types/typestring_test.go
+++ b/src/go/types/typestring_test.go
@@ -95,6 +95,8 @@ var independentTestTypes = []testEntry{
 	dup("interface{}"),
 	dup("interface{m()}"),
 	dup(`interface{String() string; m(int) float32}`),
+	dup("interface{int|float32|complex128}"),
+	dup("interface{int|~float32|~complex128}"),
 
 	// TODO(rFindley) uncomment this once this AST is accepted, and add more test
 	// cases.
@@ -142,58 +144,6 @@ func TestTypeString(t *testing.T) {
 	}
 }
 
-func TestIncompleteInterfaces(t *testing.T) {
-	sig := NewSignature(nil, nil, nil, false)
-	m := NewFunc(token.NoPos, nil, "m", sig)
-	for _, test := range []struct {
-		typ  *Interface
-		want string
-	}{
-		{new(Interface), "interface{/* incomplete */}"},
-		{new(Interface).Complete(), "interface{}"},
-
-		{NewInterface(nil, nil), "interface{}"},
-		{NewInterface(nil, nil).Complete(), "interface{}"},
-		{NewInterface([]*Func{}, nil), "interface{}"},
-		{NewInterface([]*Func{}, nil).Complete(), "interface{}"},
-		{NewInterface(nil, []*Named{}), "interface{}"},
-		{NewInterface(nil, []*Named{}).Complete(), "interface{}"},
-		{NewInterface([]*Func{m}, nil), "interface{m() /* incomplete */}"},
-		{NewInterface([]*Func{m}, nil).Complete(), "interface{m()}"},
-		{NewInterface(nil, []*Named{newDefined(new(Interface).Complete())}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(new(Interface).Complete())}).Complete(), "interface{T}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil))}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil).Complete())}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil).Complete())}).Complete(), "interface{T}"},
-
-		{NewInterfaceType(nil, nil), "interface{}"},
-		{NewInterfaceType(nil, nil).Complete(), "interface{}"},
-		{NewInterfaceType([]*Func{}, nil), "interface{}"},
-		{NewInterfaceType([]*Func{}, nil).Complete(), "interface{}"},
-		{NewInterfaceType(nil, []Type{}), "interface{}"},
-		{NewInterfaceType(nil, []Type{}).Complete(), "interface{}"},
-		{NewInterfaceType([]*Func{m}, nil), "interface{m() /* incomplete */}"},
-		{NewInterfaceType([]*Func{m}, nil).Complete(), "interface{m()}"},
-		{NewInterfaceType(nil, []Type{new(Interface).Complete()}), "interface{interface{} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{new(Interface).Complete()}).Complete(), "interface{interface{}}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil)}), "interface{interface{m() /* incomplete */} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil).Complete()}), "interface{interface{m()} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil).Complete()}).Complete(), "interface{interface{m()}}"},
-	} {
-		got := test.typ.String()
-		if got != test.want {
-			t.Errorf("got: %s, want: %s", got, test.want)
-		}
-	}
-}
-
-// newDefined creates a new defined type named T with the given underlying type.
-// Helper function for use with TestIncompleteInterfaces only.
-func newDefined(underlying Type) *Named {
-	tname := NewTypeName(token.NoPos, nil, "T", nil)
-	return NewNamed(tname, underlying, nil)
-}
-
 func TestQualifiedTypeString(t *testing.T) {
 	p, _ := pkgFor("p.go", "package p; type T int", nil)
 	q, _ := pkgFor("q.go", "package q", nil)
diff --git a/src/go/types/typeterm.go b/src/go/types/typeterm.go
new file mode 100644
index 0000000000000000000000000000000000000000..6b6782100084f66aa1ea9add9c35e2910b05d17c
--- /dev/null
+++ b/src/go/types/typeterm.go
@@ -0,0 +1,166 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A term describes elementary type sets:
+//
+//   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
+//   𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
+//   T:  &term{false, T}  == {T}                    // set of type T
+//  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
+//
+type term struct {
+	tilde bool // valid if typ != nil
+	typ   Type
+}
+
+func (x *term) String() string {
+	switch {
+	case x == nil:
+		return "∅"
+	case x.typ == nil:
+		return "𝓤"
+	case x.tilde:
+		return "~" + x.typ.String()
+	default:
+		return x.typ.String()
+	}
+}
+
+// equal reports whether x and y represent the same type set.
+func (x *term) equal(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return x == y
+	case x.typ == nil || y.typ == nil:
+		return x.typ == y.typ
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	return x.tilde == y.tilde && Identical(x.typ, y.typ)
+}
+
+// union returns the union x ∪ y: zero, one, or two non-nil terms.
+func (x *term) union(y *term) (_, _ *term) {
+	// easy cases
+	switch {
+	case x == nil && y == nil:
+		return nil, nil // ∅ ∪ ∅ == ∅
+	case x == nil:
+		return y, nil // ∅ ∪ y == y
+	case y == nil:
+		return x, nil // x ∪ ∅ == x
+	case x.typ == nil:
+		return x, nil // 𝓤 ∪ y == 𝓤
+	case y.typ == nil:
+		return y, nil // x ∪ 𝓤 == 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∪ ~t == ~t
+	// ~t ∪  T == ~t
+	//  T ∪ ~t == ~t
+	//  T ∪  T ==  T
+	if x.tilde || !y.tilde {
+		return x, nil
+	}
+	return y, nil
+}
+
+// intersect returns the intersection x ∩ y.
+func (x *term) intersect(y *term) *term {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
+	case x.typ == nil:
+		return y // 𝓤 ∩ y == y
+	case y.typ == nil:
+		return x // x ∩ 𝓤 == x
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return nil // x ∩ y == ∅ if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∩ ~t == ~t
+	// ~t ∩  T ==  T
+	//  T ∩ ~t ==  T
+	//  T ∩  T ==  T
+	if !x.tilde || y.tilde {
+		return x
+	}
+	return y
+}
+
+// includes reports whether t ∈ x.
+func (x *term) includes(t Type) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return false // t ∈ ∅ == false
+	case x.typ == nil:
+		return true // t ∈ 𝓤 == true
+	}
+	// ∅ ⊂ x ⊂ 𝓤
+
+	u := t
+	if x.tilde {
+		u = under(u)
+	}
+	return Identical(x.typ, u)
+}
+
+// subsetOf reports whether x ⊆ y.
+func (x *term) subsetOf(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return true // ∅ ⊆ y == true
+	case y == nil:
+		return false // x ⊆ ∅ == false since x != ∅
+	case y.typ == nil:
+		return true // x ⊆ 𝓤 == true
+	case x.typ == nil:
+		return false // 𝓤 ⊆ y == false since y != 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return false // x ⊆ y == false if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ⊆ ~t == true
+	// ~t ⊆ T == false
+	//  T ⊆ ~t == true
+	//  T ⊆  T == true
+	return !x.tilde || y.tilde
+}
+
+// disjoint reports whether x ∩ y == ∅.
+// x.typ and y.typ must not be nil.
+func (x *term) disjoint(y *term) bool {
+	if debug && (x.typ == nil || y.typ == nil) {
+		panic("invalid argument(s)")
+	}
+	ux := x.typ
+	if y.tilde {
+		ux = under(ux)
+	}
+	uy := y.typ
+	if x.tilde {
+		uy = under(uy)
+	}
+	return !Identical(ux, uy)
+}
diff --git a/src/go/types/typeterm_test.go b/src/go/types/typeterm_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..27f132a1d249a2df23599acbd51123680399d2fa
--- /dev/null
+++ b/src/go/types/typeterm_test.go
@@ -0,0 +1,240 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/token"
+	"strings"
+	"testing"
+)
+
+var myInt = func() Type {
+	tname := NewTypeName(token.NoPos, nil, "myInt", nil)
+	return NewNamed(tname, Typ[Int], nil)
+}()
+
+var testTerms = map[string]*term{
+	"∅":       nil,
+	"𝓤":       {},
+	"int":     {false, Typ[Int]},
+	"~int":    {true, Typ[Int]},
+	"string":  {false, Typ[String]},
+	"~string": {true, Typ[String]},
+	"myInt":   {false, myInt},
+}
+
+func TestTermString(t *testing.T) {
+	for want, x := range testTerms {
+		if got := x.String(); got != want {
+			t.Errorf("%v.String() == %v; want %v", x, got, want)
+		}
+	}
+}
+
+func split(s string, n int) []string {
+	r := strings.Split(s, " ")
+	if len(r) != n {
+		panic("invalid test case: " + s)
+	}
+	return r
+}
+
+func testTerm(name string) *term {
+	r, ok := testTerms[name]
+	if !ok {
+		panic("invalid test argument: " + name)
+	}
+	return r
+}
+
+func TestTermEqual(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"𝓤 𝓤 T",
+		"int int T",
+		"~int ~int T",
+		"myInt myInt T",
+		"∅ 𝓤 F",
+		"∅ int F",
+		"∅ ~int F",
+		"𝓤 int F",
+		"𝓤 ~int F",
+		"𝓤 myInt F",
+		"int ~int F",
+		"int myInt F",
+		"~int myInt F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+		// equal is symmetric
+		x, y = y, x
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermUnion(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅ ∅",
+		"∅ 𝓤 𝓤 ∅",
+		"∅ int int ∅",
+		"∅ ~int ~int ∅",
+		"∅ myInt myInt ∅",
+		"𝓤 𝓤 𝓤 ∅",
+		"𝓤 int 𝓤 ∅",
+		"𝓤 ~int 𝓤 ∅",
+		"𝓤 myInt 𝓤 ∅",
+		"int int int ∅",
+		"int ~int ~int ∅",
+		"int string int string",
+		"int ~string int ~string",
+		"int myInt int myInt",
+		"~int ~string ~int ~string",
+		"~int myInt ~int ∅",
+
+		// union is symmetric, but the result order isn't - repeat symmetric cases explictly
+		"𝓤 ∅ 𝓤 ∅",
+		"int ∅ int ∅",
+		"~int ∅ ~int ∅",
+		"myInt ∅ myInt ∅",
+		"int 𝓤 𝓤 ∅",
+		"~int 𝓤 𝓤 ∅",
+		"myInt 𝓤 𝓤 ∅",
+		"~int int ~int ∅",
+		"string int string int",
+		"~string int ~string int",
+		"myInt int myInt int",
+		"~string ~int ~string ~int",
+		"myInt ~int ~int ∅",
+	} {
+		args := split(test, 4)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want1 := testTerm(args[2])
+		want2 := testTerm(args[3])
+		if got1, got2 := x.union(y); !got1.equal(want1) || !got2.equal(want2) {
+			t.Errorf("%v.union(%v) = %v, %v; want %v, %v", x, y, got1, got2, want1, want2)
+		}
+	}
+}
+
+func TestTermIntersection(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅",
+		"∅ 𝓤 ∅",
+		"∅ int ∅",
+		"∅ ~int ∅",
+		"∅ myInt ∅",
+		"𝓤 𝓤 𝓤",
+		"𝓤 int int",
+		"𝓤 ~int ~int",
+		"𝓤 myInt myInt",
+		"int int int",
+		"int ~int int",
+		"int string ∅",
+		"int ~string ∅",
+		"int string ∅",
+		"~int ~string ∅",
+		"~int myInt myInt",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := testTerm(args[2])
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+		// intersect is symmetric
+		x, y = y, x
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermIncludes(t *testing.T) {
+	for _, test := range []string{
+		"∅ int F",
+		"𝓤 int T",
+		"int int T",
+		"~int int T",
+		"~int myInt T",
+		"string int F",
+		"~string int F",
+		"myInt int F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1]).typ
+		want := args[2] == "T"
+		if got := x.includes(y); got != want {
+			t.Errorf("%v.includes(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermSubsetOf(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"𝓤 𝓤 T",
+		"int int T",
+		"~int ~int T",
+		"myInt myInt T",
+		"∅ 𝓤 T",
+		"∅ int T",
+		"∅ ~int T",
+		"∅ myInt T",
+		"𝓤 int F",
+		"𝓤 ~int F",
+		"𝓤 myInt F",
+		"int ~int T",
+		"int myInt F",
+		"~int myInt F",
+		"myInt int F",
+		"myInt ~int T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.subsetOf(y); got != want {
+			t.Errorf("%v.subsetOf(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermDisjoint(t *testing.T) {
+	for _, test := range []string{
+		"int int F",
+		"~int ~int F",
+		"int ~int F",
+		"int string T",
+		"int ~string T",
+		"int myInt T",
+		"~int ~string T",
+		"~int myInt F",
+		"string myInt T",
+		"~string myInt T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+		// disjoint is symmetric
+		x, y = y, x
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go
index 1738d864a6573965f9bf5cf626b9b9a48fdb60ec..baa4e3c2d0385e2853ee81c0f66715b858b6ceb9 100644
--- a/src/go/types/typexpr.go
+++ b/src/go/types/typexpr.go
@@ -12,8 +12,6 @@ import (
 	"go/constant"
 	"go/internal/typeparams"
 	"go/token"
-	"sort"
-	"strconv"
 	"strings"
 )
 
@@ -29,13 +27,24 @@ func (check *Checker) ident(x *operand, e *ast.Ident, def *Named, wantType bool)
 	// Note that we cannot use check.lookup here because the returned scope
 	// may be different from obj.Parent(). See also Scope.LookupParent doc.
 	scope, obj := check.scope.LookupParent(e.Name, check.pos)
-	if obj == nil {
+	switch obj {
+	case nil:
 		if e.Name == "_" {
-			check.errorf(e, _InvalidBlank, "cannot use _ as value or type")
+			check.error(e, _InvalidBlank, "cannot use _ as value or type")
 		} else {
 			check.errorf(e, _UndeclaredName, "undeclared name: %s", e.Name)
 		}
 		return
+	case universeAny, universeComparable:
+		if !check.allowVersion(check.pkg, 1, 18) {
+			check.errorf(e, _UndeclaredName, "undeclared name: %s (requires version go1.18 or later)", e.Name)
+			return
+		}
+		// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+		if obj == universeAny {
+			check.error(e, _Todo, "cannot use any outside constraint position")
+			return
+		}
 	}
 	check.recordUse(e, obj)
 
@@ -58,7 +67,7 @@ func (check *Checker) ident(x *operand, e *ast.Ident, def *Named, wantType bool)
 	// If so, mark the respective package as used.
 	// (This code is only needed for dot-imports. Without them,
 	// we only have to mark variables, see *Var case below).
-	if pkgName := check.dotImportMap[dotImportKey{scope, obj}]; pkgName != nil {
+	if pkgName := check.dotImportMap[dotImportKey{scope, obj.Name()}]; pkgName != nil {
 		pkgName.used = true
 	}
 
@@ -136,19 +145,18 @@ func (check *Checker) varType(e ast.Expr) Type {
 // ordinaryType reports an error if typ is an interface type containing
 // type lists or is (or embeds) the predeclared type comparable.
 func (check *Checker) ordinaryType(pos positioner, typ Type) {
-	// We don't want to call under() (via asInterface) or complete interfaces
-	// while we are in the middle of type-checking parameter declarations that
-	// might belong to interface methods. Delay this check to the end of
-	// type-checking.
+	// We don't want to call under() (via asInterface) or complete interfaces while we
+	// are in the middle of type-checking parameter declarations that might belong to
+	// interface methods. Delay this check to the end of type-checking.
 	check.later(func() {
 		if t := asInterface(typ); t != nil {
-			check.completeInterface(pos.Pos(), t) // TODO(gri) is this the correct position?
-			if t.allTypes != nil {
-				check.softErrorf(pos, _Todo, "interface contains type constraints (%s)", t.allTypes)
-				return
-			}
-			if t._IsComparable() {
-				check.softErrorf(pos, _Todo, "interface is (or embeds) comparable")
+			tset := computeInterfaceTypeSet(check, pos.Pos(), t) // TODO(gri) is this the correct position?
+			if !tset.IsMethodSet() {
+				if tset.comparable {
+					check.softErrorf(pos, _Todo, "interface is (or embeds) comparable")
+				} else {
+					check.softErrorf(pos, _Todo, "interface contains type constraints")
+				}
 			}
 		}
 	})
@@ -194,205 +202,6 @@ func (check *Checker) genericType(e ast.Expr, reportErr bool) Type {
 	return typ
 }
 
-// isubst returns an x with identifiers substituted per the substitution map smap.
-// isubst only handles the case of (valid) method receiver type expressions correctly.
-func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
-	switch n := x.(type) {
-	case *ast.Ident:
-		if alt := smap[n]; alt != nil {
-			return alt
-		}
-	case *ast.StarExpr:
-		X := isubst(n.X, smap)
-		if X != n.X {
-			new := *n
-			new.X = X
-			return &new
-		}
-	case *ast.IndexExpr:
-		elems := typeparams.UnpackExpr(n.Index)
-		var newElems []ast.Expr
-		for i, elem := range elems {
-			new := isubst(elem, smap)
-			if new != elem {
-				if newElems == nil {
-					newElems = make([]ast.Expr, len(elems))
-					copy(newElems, elems)
-				}
-				newElems[i] = new
-			}
-		}
-		if newElems != nil {
-			index := typeparams.PackExpr(newElems)
-			new := *n
-			new.Index = index
-			return &new
-		}
-	case *ast.ParenExpr:
-		return isubst(n.X, smap) // no need to keep parentheses
-	default:
-		// Other receiver type expressions are invalid.
-		// It's fine to ignore those here as they will
-		// be checked elsewhere.
-	}
-	return x
-}
-
-// funcType type-checks a function or method type.
-func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
-	check.openScope(ftyp, "function")
-	check.scope.isFunc = true
-	check.recordScope(ftyp, check.scope)
-	sig.scope = check.scope
-	defer check.closeScope()
-
-	var recvTyp ast.Expr // rewritten receiver type; valid if != nil
-	if recvPar != nil && len(recvPar.List) > 0 {
-		// collect generic receiver type parameters, if any
-		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
-		// - the receiver specification acts as local declaration for its type parameters, which may be blank
-		_, rname, rparams := check.unpackRecv(recvPar.List[0].Type, true)
-		if len(rparams) > 0 {
-			// Blank identifiers don't get declared and regular type-checking of the instantiated
-			// parameterized receiver type expression fails in Checker.collectParams of receiver.
-			// Identify blank type parameters and substitute each with a unique new identifier named
-			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
-			// name.
-			var smap map[*ast.Ident]*ast.Ident // substitution map from "_" to "n_" identifiers
-			for i, p := range rparams {
-				if p.Name == "_" {
-					new := *p
-					new.Name = fmt.Sprintf("%d_", i)
-					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
-					if smap == nil {
-						smap = make(map[*ast.Ident]*ast.Ident)
-					}
-					smap[p] = &new
-				}
-			}
-			if smap != nil {
-				// blank identifiers were found => use rewritten receiver type
-				recvTyp = isubst(recvPar.List[0].Type, smap)
-			}
-			sig.rparams = check.declareTypeParams(nil, rparams)
-			// determine receiver type to get its type parameters
-			// and the respective type parameter bounds
-			var recvTParams []*TypeName
-			if rname != nil {
-				// recv should be a Named type (otherwise an error is reported elsewhere)
-				// Also: Don't report an error via genericType since it will be reported
-				//       again when we type-check the signature.
-				// TODO(gri) maybe the receiver should be marked as invalid instead?
-				if recv := asNamed(check.genericType(rname, false)); recv != nil {
-					recvTParams = recv.tparams
-				}
-			}
-			// provide type parameter bounds
-			// - only do this if we have the right number (otherwise an error is reported elsewhere)
-			if len(sig.rparams) == len(recvTParams) {
-				// We have a list of *TypeNames but we need a list of Types.
-				list := make([]Type, len(sig.rparams))
-				for i, t := range sig.rparams {
-					list[i] = t.typ
-				}
-				smap := makeSubstMap(recvTParams, list)
-				for i, tname := range sig.rparams {
-					bound := recvTParams[i].typ.(*_TypeParam).bound
-					// bound is (possibly) parameterized in the context of the
-					// receiver type declaration. Substitute parameters for the
-					// current context.
-					// TODO(gri) should we assume now that bounds always exist?
-					//           (no bound == empty interface)
-					if bound != nil {
-						bound = check.subst(tname.pos, bound, smap)
-						tname.typ.(*_TypeParam).bound = bound
-					}
-				}
-			}
-		}
-	}
-
-	if tparams := typeparams.Get(ftyp); tparams != nil {
-		sig.tparams = check.collectTypeParams(tparams)
-		// Always type-check method type parameters but complain that they are not allowed.
-		// (A separate check is needed when type-checking interface method signatures because
-		// they don't have a receiver specification.)
-		if recvPar != nil {
-			check.errorf(tparams, _Todo, "methods cannot have type parameters")
-		}
-	}
-
-	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
-	// declarations and then squash that scope into the parent scope (and report any redeclarations at
-	// that time).
-	scope := NewScope(check.scope, token.NoPos, token.NoPos, "function body (temp. scope)")
-	recvList, _ := check.collectParams(scope, recvPar, recvTyp, false) // use rewritten receiver type, if any
-	params, variadic := check.collectParams(scope, ftyp.Params, nil, true)
-	results, _ := check.collectParams(scope, ftyp.Results, nil, false)
-	scope.squash(func(obj, alt Object) {
-		check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
-		check.reportAltDecl(alt)
-	})
-
-	if recvPar != nil {
-		// recv parameter list present (may be empty)
-		// spec: "The receiver is specified via an extra parameter section preceding the
-		// method name. That parameter section must declare a single parameter, the receiver."
-		var recv *Var
-		switch len(recvList) {
-		case 0:
-			// error reported by resolver
-			recv = NewParam(0, nil, "", Typ[Invalid]) // ignore recv below
-		default:
-			// more than one receiver
-			check.error(recvList[len(recvList)-1], _BadRecv, "method must have exactly one receiver")
-			fallthrough // continue with first receiver
-		case 1:
-			recv = recvList[0]
-		}
-
-		// TODO(gri) We should delay rtyp expansion to when we actually need the
-		//           receiver; thus all checks here should be delayed to later.
-		rtyp, _ := deref(recv.typ)
-		rtyp = expand(rtyp)
-
-		// spec: "The receiver type must be of the form T or *T where T is a type name."
-		// (ignore invalid types - error was reported before)
-		if t := rtyp; t != Typ[Invalid] {
-			var err string
-			if T := asNamed(t); T != nil {
-				// spec: "The type denoted by T is called the receiver base type; it must not
-				// be a pointer or interface type and it must be declared in the same package
-				// as the method."
-				if T.obj.pkg != check.pkg {
-					err = "type not defined in this package"
-				} else {
-					switch u := optype(T).(type) {
-					case *Basic:
-						// unsafe.Pointer is treated like a regular pointer
-						if u.kind == UnsafePointer {
-							err = "unsafe.Pointer"
-						}
-					case *Pointer, *Interface:
-						err = "pointer or interface type"
-					}
-				}
-			} else {
-				err = "basic or unnamed type"
-			}
-			if err != "" {
-				check.errorf(recv, _InvalidRecv, "invalid receiver %s (%s)", recv.typ, err)
-				// ok to continue
-			}
-		}
-		sig.recv = recv
-	}
-
-	sig.params = NewTuple(params...)
-	sig.results = NewTuple(results...)
-	sig.variadic = variadic
-}
-
 // goTypeName returns the Go type name for typ and
 // removes any occurrences of "types." from that name.
 func goTypeName(typ Type) string {
@@ -414,7 +223,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 				// Test case: type T[P any] *T[P]
 				// TODO(gri) investigate if that's a bug or to be expected
 				// (see also analogous comment in Checker.instantiate).
-				under = T.Underlying()
+				under = safeUnderlying(T)
 			}
 			if T == under {
 				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
@@ -462,13 +271,10 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 			check.errorf(&x, _NotAType, "%s is not a type", &x)
 		}
 
-	case *ast.IndexExpr:
-		if typeparams.Enabled {
-			exprs := typeparams.UnpackExpr(e.Index)
-			return check.instantiatedType(e.X, exprs, def)
-		}
-		check.errorf(e0, _NotAType, "%s is not a type", e0)
-		check.use(e.X)
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(e)
+		// TODO(rfindley): type instantiation should require go1.18
+		return check.instantiatedType(ix.X, ix.Indices, def)
 
 	case *ast.ParenExpr:
 		// Generic types must be instantiated before they can be used in any form.
@@ -604,44 +410,36 @@ func (check *Checker) typeOrNil(e ast.Expr) Type {
 	return Typ[Invalid]
 }
 
-func (check *Checker) instantiatedType(x ast.Expr, targs []ast.Expr, def *Named) Type {
-	b := check.genericType(x, true) // TODO(gri) what about cycles?
-	if b == Typ[Invalid] {
-		return b // error already reported
+func (check *Checker) instantiatedType(x ast.Expr, targsx []ast.Expr, def *Named) Type {
+	gtyp := check.genericType(x, true)
+	if gtyp == Typ[Invalid] {
+		return gtyp // error already reported
 	}
-	base := asNamed(b)
+	base, _ := gtyp.(*Named)
 	if base == nil {
-		unreachable() // should have been caught by genericType
+		panic(fmt.Sprintf("%v: cannot instantiate %v", x.Pos(), gtyp))
 	}
 
-	// create a new type instance rather than instantiate the type
-	// TODO(gri) should do argument number check here rather than
-	//           when instantiating the type?
-	typ := new(instance)
-	def.setUnderlying(typ)
-
-	typ.check = check
-	typ.pos = x.Pos()
-	typ.base = base
-
-	// evaluate arguments (always)
-	typ.targs = check.typeList(targs)
-	if typ.targs == nil {
+	// evaluate arguments
+	targs := check.typeList(targsx)
+	if targs == nil {
 		def.setUnderlying(Typ[Invalid]) // avoid later errors due to lazy instantiation
 		return Typ[Invalid]
 	}
 
-	// determine argument positions (for error reporting)
-	typ.poslist = make([]token.Pos, len(targs))
-	for i, arg := range targs {
-		typ.poslist[i] = arg.Pos()
+	// determine argument positions
+	posList := make([]token.Pos, len(targs))
+	for i, arg := range targsx {
+		posList[i] = arg.Pos()
 	}
 
+	typ := check.instantiate(x.Pos(), base, targs, posList)
+	def.setUnderlying(typ)
+
 	// make sure we check instantiation works at least once
 	// and that the resulting type is valid
 	check.later(func() {
-		t := typ.expand()
-		check.validType(t, nil)
+		check.validType(typ, nil)
 	})
 
 	return typ
@@ -689,518 +487,3 @@ func (check *Checker) typeList(list []ast.Expr) []Type {
 	}
 	return res
 }
-
-// collectParams declares the parameters of list in scope and returns the corresponding
-// variable list. If type0 != nil, it is used instead of the first type in list.
-func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, type0 ast.Expr, variadicOk bool) (params []*Var, variadic bool) {
-	if list == nil {
-		return
-	}
-
-	var named, anonymous bool
-	for i, field := range list.List {
-		ftype := field.Type
-		if i == 0 && type0 != nil {
-			ftype = type0
-		}
-		if t, _ := ftype.(*ast.Ellipsis); t != nil {
-			ftype = t.Elt
-			if variadicOk && i == len(list.List)-1 && len(field.Names) <= 1 {
-				variadic = true
-			} else {
-				check.softErrorf(t, _MisplacedDotDotDot, "can only use ... with final parameter in list")
-				// ignore ... and continue
-			}
-		}
-		typ := check.varType(ftype)
-		// The parser ensures that f.Tag is nil and we don't
-		// care if a constructed AST contains a non-nil tag.
-		if len(field.Names) > 0 {
-			// named parameter
-			for _, name := range field.Names {
-				if name.Name == "" {
-					check.invalidAST(name, "anonymous parameter")
-					// ok to continue
-				}
-				par := NewParam(name.Pos(), check.pkg, name.Name, typ)
-				check.declare(scope, name, par, scope.pos)
-				params = append(params, par)
-			}
-			named = true
-		} else {
-			// anonymous parameter
-			par := NewParam(ftype.Pos(), check.pkg, "", typ)
-			check.recordImplicit(field, par)
-			params = append(params, par)
-			anonymous = true
-		}
-	}
-
-	if named && anonymous {
-		check.invalidAST(list, "list contains both named and anonymous parameters")
-		// ok to continue
-	}
-
-	// For a variadic function, change the last parameter's type from T to []T.
-	// Since we type-checked T rather than ...T, we also need to retro-actively
-	// record the type for ...T.
-	if variadic {
-		last := params[len(params)-1]
-		last.typ = &Slice{elem: last.typ}
-		check.recordTypeAndValue(list.List[len(list.List)-1].Type, typexpr, last.typ, nil)
-	}
-
-	return
-}
-
-func (check *Checker) declareInSet(oset *objset, pos token.Pos, obj Object) bool {
-	if alt := oset.insert(obj); alt != nil {
-		check.errorf(atPos(pos), _DuplicateDecl, "%s redeclared", obj.Name())
-		check.reportAltDecl(alt)
-		return false
-	}
-	return true
-}
-
-func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
-	var tlist *ast.Ident // "type" name of first entry in a type list declaration
-	var types []ast.Expr
-	for _, f := range iface.Methods.List {
-		if len(f.Names) > 0 {
-			// We have a method with name f.Names[0], or a type
-			// of a type list (name.Name == "type").
-			// (The parser ensures that there's only one method
-			// and we don't care if a constructed AST has more.)
-			name := f.Names[0]
-			if name.Name == "_" {
-				check.errorf(name, _BlankIfaceMethod, "invalid method name _")
-				continue // ignore
-			}
-
-			if name.Name == "type" {
-				// Always collect all type list entries, even from
-				// different type lists, under the assumption that
-				// the author intended to include all types.
-				types = append(types, f.Type)
-				if tlist != nil && tlist != name {
-					check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
-				}
-				tlist = name
-				continue
-			}
-
-			typ := check.typ(f.Type)
-			sig, _ := typ.(*Signature)
-			if sig == nil {
-				if typ != Typ[Invalid] {
-					check.invalidAST(f.Type, "%s is not a method signature", typ)
-				}
-				continue // ignore
-			}
-
-			// Always type-check method type parameters but complain if they are not enabled.
-			// (This extra check is needed here because interface method signatures don't have
-			// a receiver specification.)
-			if sig.tparams != nil {
-				var at positioner = f.Type
-				if tparams := typeparams.Get(f.Type); tparams != nil {
-					at = tparams
-				}
-				check.errorf(at, _Todo, "methods cannot have type parameters")
-			}
-
-			// use named receiver type if available (for better error messages)
-			var recvTyp Type = ityp
-			if def != nil {
-				recvTyp = def
-			}
-			sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
-
-			m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
-			check.recordDef(name, m)
-			ityp.methods = append(ityp.methods, m)
-		} else {
-			// We have an embedded type. completeInterface will
-			// eventually verify that we have an interface.
-			ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
-			check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
-		}
-	}
-
-	// type constraints
-	ityp.types = _NewSum(check.collectTypeConstraints(iface.Pos(), types))
-
-	if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
-		// empty interface
-		ityp.allMethods = markComplete
-		return
-	}
-
-	// sort for API stability
-	sortMethods(ityp.methods)
-	sortTypes(ityp.embeddeds)
-
-	check.later(func() { check.completeInterface(iface.Pos(), ityp) })
-}
-
-func (check *Checker) completeInterface(pos token.Pos, ityp *Interface) {
-	if ityp.allMethods != nil {
-		return
-	}
-
-	// completeInterface may be called via the LookupFieldOrMethod,
-	// MissingMethod, Identical, or IdenticalIgnoreTags external API
-	// in which case check will be nil. In this case, type-checking
-	// must be finished and all interfaces should have been completed.
-	if check == nil {
-		panic("internal error: incomplete interface")
-	}
-
-	if trace {
-		// Types don't generally have position information.
-		// If we don't have a valid pos provided, try to use
-		// one close enough.
-		if !pos.IsValid() && len(ityp.methods) > 0 {
-			pos = ityp.methods[0].pos
-		}
-
-		check.trace(pos, "complete %s", ityp)
-		check.indent++
-		defer func() {
-			check.indent--
-			check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
-		}()
-	}
-
-	// An infinitely expanding interface (due to a cycle) is detected
-	// elsewhere (Checker.validType), so here we simply assume we only
-	// have valid interfaces. Mark the interface as complete to avoid
-	// infinite recursion if the validType check occurs later for some
-	// reason.
-	ityp.allMethods = markComplete
-
-	// Methods of embedded interfaces are collected unchanged; i.e., the identity
-	// of a method I.m's Func Object of an interface I is the same as that of
-	// the method m in an interface that embeds interface I. On the other hand,
-	// if a method is embedded via multiple overlapping embedded interfaces, we
-	// don't provide a guarantee which "original m" got chosen for the embedding
-	// interface. See also issue #34421.
-	//
-	// If we don't care to provide this identity guarantee anymore, instead of
-	// reusing the original method in embeddings, we can clone the method's Func
-	// Object and give it the position of a corresponding embedded interface. Then
-	// we can get rid of the mpos map below and simply use the cloned method's
-	// position.
-
-	var seen objset
-	var methods []*Func
-	mpos := make(map[*Func]token.Pos) // method specification or method embedding position, for good error messages
-	addMethod := func(pos token.Pos, m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-			mpos[m] = pos
-		case explicit:
-			check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
-			check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
-		default:
-			// We have a duplicate method name in an embedded (not explicitly declared) method.
-			// Check method signatures after all types are computed (issue #33656).
-			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
-			// error here as well (even though we could do it eagerly) because it's the same
-			// error message.
-			check.later(func() {
-				if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
-					check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
-					check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
-				}
-			})
-		}
-	}
-
-	for _, m := range ityp.methods {
-		addMethod(m.pos, m, true)
-	}
-
-	// collect types
-	allTypes := ityp.types
-
-	posList := check.posMap[ityp]
-	for i, typ := range ityp.embeddeds {
-		pos := posList[i] // embedding position
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				var format string
-				if _, ok := utyp.(*_TypeParam); ok {
-					format = "%s is a type parameter, not an interface"
-				} else {
-					format = "%s is not an interface"
-				}
-				// TODO: correct error code.
-				check.errorf(atPos(pos), _InvalidIfaceEmbed, format, typ)
-			}
-			continue
-		}
-		check.completeInterface(pos, etyp)
-		for _, m := range etyp.allMethods {
-			addMethod(pos, m, false) // use embedding position pos rather than m.pos
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
-
-	if methods != nil {
-		sort.Sort(byUniqueMethodName(methods))
-		ityp.allMethods = methods
-	}
-	ityp.allTypes = allTypes
-}
-
-// intersect computes the intersection of the types x and y.
-// Note: A incomming nil type stands for the top type. A top
-// type result is returned as nil.
-func intersect(x, y Type) (r Type) {
-	defer func() {
-		if r == theTop {
-			r = nil
-		}
-	}()
-
-	switch {
-	case x == theBottom || y == theBottom:
-		return theBottom
-	case x == nil || x == theTop:
-		return y
-	case y == nil || x == theTop:
-		return x
-	}
-
-	xtypes := unpackType(x)
-	ytypes := unpackType(y)
-	// Compute the list rtypes which includes only
-	// types that are in both xtypes and ytypes.
-	// Quadratic algorithm, but good enough for now.
-	// TODO(gri) fix this
-	var rtypes []Type
-	for _, x := range xtypes {
-		if includes(ytypes, x) {
-			rtypes = append(rtypes, x)
-		}
-	}
-
-	if rtypes == nil {
-		return theBottom
-	}
-	return _NewSum(rtypes)
-}
-
-func sortTypes(list []Type) {
-	sort.Stable(byUniqueTypeName(list))
-}
-
-// byUniqueTypeName named type lists can be sorted by their unique type names.
-type byUniqueTypeName []Type
-
-func (a byUniqueTypeName) Len() int           { return len(a) }
-func (a byUniqueTypeName) Less(i, j int) bool { return sortName(a[i]) < sortName(a[j]) }
-func (a byUniqueTypeName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func sortName(t Type) string {
-	if named := asNamed(t); named != nil {
-		return named.obj.Id()
-	}
-	return ""
-}
-
-func sortMethods(list []*Func) {
-	sort.Sort(byUniqueMethodName(list))
-}
-
-func assertSortedMethods(list []*Func) {
-	if !debug {
-		panic("internal error: assertSortedMethods called outside debug mode")
-	}
-	if !sort.IsSorted(byUniqueMethodName(list)) {
-		panic("internal error: methods not sorted")
-	}
-}
-
-// byUniqueMethodName method lists can be sorted by their unique method names.
-type byUniqueMethodName []*Func
-
-func (a byUniqueMethodName) Len() int           { return len(a) }
-func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
-func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func (check *Checker) tag(t *ast.BasicLit) string {
-	if t != nil {
-		if t.Kind == token.STRING {
-			if val, err := strconv.Unquote(t.Value); err == nil {
-				return val
-			}
-		}
-		check.invalidAST(t, "incorrect tag syntax: %q", t.Value)
-	}
-	return ""
-}
-
-func (check *Checker) structType(styp *Struct, e *ast.StructType) {
-	list := e.Fields
-	if list == nil {
-		return
-	}
-
-	// struct fields and tags
-	var fields []*Var
-	var tags []string
-
-	// for double-declaration checks
-	var fset objset
-
-	// current field typ and tag
-	var typ Type
-	var tag string
-	add := func(ident *ast.Ident, embedded bool, pos token.Pos) {
-		if tag != "" && tags == nil {
-			tags = make([]string, len(fields))
-		}
-		if tags != nil {
-			tags = append(tags, tag)
-		}
-
-		name := ident.Name
-		fld := NewField(pos, check.pkg, name, typ, embedded)
-		// spec: "Within a struct, non-blank field names must be unique."
-		if name == "_" || check.declareInSet(&fset, pos, fld) {
-			fields = append(fields, fld)
-			check.recordDef(ident, fld)
-		}
-	}
-
-	// addInvalid adds an embedded field of invalid type to the struct for
-	// fields with errors; this keeps the number of struct fields in sync
-	// with the source as long as the fields are _ or have different names
-	// (issue #25627).
-	addInvalid := func(ident *ast.Ident, pos token.Pos) {
-		typ = Typ[Invalid]
-		tag = ""
-		add(ident, true, pos)
-	}
-
-	for _, f := range list.List {
-		typ = check.varType(f.Type)
-		tag = check.tag(f.Tag)
-		if len(f.Names) > 0 {
-			// named fields
-			for _, name := range f.Names {
-				add(name, false, name.Pos())
-			}
-		} else {
-			// embedded field
-			// spec: "An embedded type must be specified as a type name T or as a
-			// pointer to a non-interface type name *T, and T itself may not be a
-			// pointer type."
-			pos := f.Type.Pos()
-			name := embeddedFieldIdent(f.Type)
-			if name == nil {
-				// TODO(rFindley): using invalidAST here causes test failures (all
-				//                 errors should have codes). Clean this up.
-				check.errorf(f.Type, _Todo, "invalid AST: embedded field type %s has no name", f.Type)
-				name = ast.NewIdent("_")
-				name.NamePos = pos
-				addInvalid(name, pos)
-				continue
-			}
-			add(name, true, pos)
-
-			// Because we have a name, typ must be of the form T or *T, where T is the name
-			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
-			// We must delay this check to the end because we don't want to instantiate
-			// (via under(t)) a possibly incomplete type.
-
-			// for use in the closure below
-			embeddedTyp := typ
-			embeddedPos := f.Type
-
-			check.later(func() {
-				t, isPtr := deref(embeddedTyp)
-				switch t := optype(t).(type) {
-				case *Basic:
-					if t == Typ[Invalid] {
-						// error was reported before
-						return
-					}
-					// unsafe.Pointer is treated like a regular pointer
-					if t.kind == UnsafePointer {
-						check.errorf(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be unsafe.Pointer")
-					}
-				case *Pointer:
-					check.errorf(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer")
-				case *Interface:
-					if isPtr {
-						check.errorf(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer to an interface")
-					}
-				}
-			})
-		}
-	}
-
-	styp.fields = fields
-	styp.tags = tags
-}
-
-func embeddedFieldIdent(e ast.Expr) *ast.Ident {
-	switch e := e.(type) {
-	case *ast.Ident:
-		return e
-	case *ast.StarExpr:
-		// *T is valid, but **T is not
-		if _, ok := e.X.(*ast.StarExpr); !ok {
-			return embeddedFieldIdent(e.X)
-		}
-	case *ast.SelectorExpr:
-		return e.Sel
-	case *ast.IndexExpr:
-		return embeddedFieldIdent(e.X)
-	}
-	return nil // invalid embedded field
-}
-
-func (check *Checker) collectTypeConstraints(pos token.Pos, types []ast.Expr) []Type {
-	list := make([]Type, 0, len(types)) // assume all types are correct
-	for _, texpr := range types {
-		if texpr == nil {
-			check.invalidAST(atPos(pos), "missing type constraint")
-			continue
-		}
-		list = append(list, check.varType(texpr))
-	}
-
-	// Ensure that each type is only present once in the type list.  Types may be
-	// interfaces, which may not be complete yet. It's ok to do this check at the
-	// end because it's not a requirement for correctness of the code.
-	// Note: This is a quadratic algorithm, but type lists tend to be short.
-	check.later(func() {
-		for i, t := range list {
-			if t := asInterface(t); t != nil {
-				check.completeInterface(types[i].Pos(), t)
-			}
-			if includes(list[:i], t) {
-				check.softErrorf(types[i], _Todo, "duplicate type %s in type list", t)
-			}
-		}
-	})
-
-	return list
-}
-
-// includes reports whether typ is in list.
-func includes(list []Type, typ Type) bool {
-	for _, e := range list {
-		if Identical(typ, e) {
-			return true
-		}
-	}
-	return false
-}
diff --git a/src/go/types/unify.go b/src/go/types/unify.go
index db06e21cf724fd11330e33f0c91ffe03ce09138a..1720646db920b319bc1c91c9509b839b17da92cd 100644
--- a/src/go/types/unify.go
+++ b/src/go/types/unify.go
@@ -8,7 +8,7 @@ package types
 
 import (
 	"bytes"
-	"go/token"
+	"fmt"
 	"sort"
 )
 
@@ -38,7 +38,6 @@ import (
 // and the respective types inferred for each type parameter.
 // A unifier is created by calling newUnifier.
 type unifier struct {
-	check *Checker
 	exact bool
 	x, y  tparamsList // x and y must initialized via tparamsList.init
 	types []Type      // inferred types, shared by x and y
@@ -49,8 +48,8 @@ type unifier struct {
 // exactly. If exact is not set, a named type's underlying type
 // is considered if unification would fail otherwise, and the
 // direction of channels is ignored.
-func newUnifier(check *Checker, exact bool) *unifier {
-	u := &unifier{check: check, exact: exact}
+func newUnifier(exact bool) *unifier {
+	u := &unifier{exact: exact}
 	u.x.unifier = u
 	u.y.unifier = u
 	return u
@@ -64,7 +63,7 @@ func (u *unifier) unify(x, y Type) bool {
 // A tparamsList describes a list of type parameters and the types inferred for them.
 type tparamsList struct {
 	unifier *unifier
-	tparams []*TypeName
+	tparams []*TypeParam
 	// For each tparams element, there is a corresponding type slot index in indices.
 	// index  < 0: unifier.types[-index-1] == nil
 	// index == 0: no type slot allocated yet
@@ -79,11 +78,11 @@ type tparamsList struct {
 func (d *tparamsList) String() string {
 	var buf bytes.Buffer
 	buf.WriteByte('[')
-	for i, tname := range d.tparams {
+	for i, tpar := range d.tparams {
 		if i > 0 {
 			buf.WriteString(", ")
 		}
-		writeType(&buf, tname.typ, nil, nil)
+		writeType(&buf, tpar, nil, nil)
 		buf.WriteString(": ")
 		writeType(&buf, d.at(i), nil, nil)
 	}
@@ -94,13 +93,13 @@ func (d *tparamsList) String() string {
 // init initializes d with the given type parameters.
 // The type parameters must be in the order in which they appear in their declaration
 // (this ensures that the tparams indices match the respective type parameter index).
-func (d *tparamsList) init(tparams []*TypeName) {
+func (d *tparamsList) init(tparams []*TypeParam) {
 	if len(tparams) == 0 {
 		return
 	}
 	if debug {
 		for i, tpar := range tparams {
-			assert(i == tpar.typ.(*_TypeParam).index)
+			assert(i == tpar.index)
 		}
 	}
 	d.tparams = tparams
@@ -148,10 +147,17 @@ func (u *unifier) join(i, j int) bool {
 // If typ is a type parameter of d, index returns the type parameter index.
 // Otherwise, the result is < 0.
 func (d *tparamsList) index(typ Type) int {
-	if t, ok := typ.(*_TypeParam); ok {
-		if i := t.index; i < len(d.tparams) && d.tparams[i].typ == t {
-			return i
-		}
+	if tpar, ok := typ.(*TypeParam); ok {
+		return tparamIndex(d.tparams, tpar)
+	}
+	return -1
+}
+
+// If tpar is a type parameter in list, tparamIndex returns the type parameter index.
+// Otherwise, the result is < 0. tpar must not be nil.
+func tparamIndex(list []*TypeParam, tpar *TypeParam) int {
+	if i := tpar.index; i < len(list) && list[i] == tpar {
+		return i
 	}
 	return -1
 }
@@ -220,10 +226,6 @@ func (u *unifier) nifyEq(x, y Type, p *ifacePair) bool {
 // code the corresponding changes should be made here.
 // Must not be called directly from outside the unifier.
 func (u *unifier) nify(x, y Type, p *ifacePair) bool {
-	// types must be expanded for comparison
-	x = expand(x)
-	y = expand(y)
-
 	if !u.exact {
 		// If exact unification is known to fail because we attempt to
 		// match a type name against an unnamed type literal, consider
@@ -352,25 +354,18 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
 				u.nify(x.results, y.results, p)
 		}
 
-	case *_Sum:
-		// This should not happen with the current internal use of sum types.
-		panic("type inference across sum types not implemented")
-
 	case *Interface:
 		// Two interface types are identical if they have the same set of methods with
 		// the same names and identical function types. Lower-case method names from
 		// different packages are always different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if u.check != nil {
-				u.check.completeInterface(token.NoPos, x)
-				u.check.completeInterface(token.NoPos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !xset.terms.equal(yset.terms) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -428,19 +423,20 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
 		}
 
 	case *Named:
-		// Two named types are identical if their type names originate
-		// in the same type declaration.
-		// if y, ok := y.(*Named); ok {
-		// 	return x.obj == y.obj
-		// }
 		if y, ok := y.(*Named); ok {
+			x.expand(nil)
+			y.expand(nil)
+
+			xargs := x.targs.list()
+			yargs := y.targs.list()
+
 			// TODO(gri) This is not always correct: two types may have the same names
 			//           in the same package if one of them is nested in a function.
 			//           Extremely unlikely but we need an always correct solution.
 			if x.obj.pkg == y.obj.pkg && x.obj.name == y.obj.name {
-				assert(len(x.targs) == len(y.targs))
-				for i, x := range x.targs {
-					if !u.nify(x, y.targs[i], p) {
+				assert(len(xargs) == len(yargs))
+				for i, x := range xargs {
+					if !u.nify(x, yargs[i], p) {
 						return false
 					}
 				}
@@ -448,21 +444,17 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
 			}
 		}
 
-	case *_TypeParam:
+	case *TypeParam:
 		// Two type parameters (which are not part of the type parameters of the
 		// enclosing type as those are handled in the beginning of this function)
 		// are identical if they originate in the same declaration.
 		return x == y
 
-	// case *instance:
-	//	unreachable since types are expanded
-
 	case nil:
 		// avoid a crash in case of nil type
 
 	default:
-		u.check.dump("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams)
-		unreachable()
+		panic(fmt.Sprintf("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams))
 	}
 
 	return false
diff --git a/src/go/types/union.go b/src/go/types/union.go
new file mode 100644
index 0000000000000000000000000000000000000000..1ba99adaca2c02a65ef7711bd7e9c9af475e32c4
--- /dev/null
+++ b/src/go/types/union.go
@@ -0,0 +1,153 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Union represents a union of terms embedded in an interface.
+type Union struct {
+	terms []*Term   // list of syntactical terms (not a canonicalized termlist)
+	tset  *_TypeSet // type set described by this union, computed lazily
+}
+
+// NewUnion returns a new Union type with the given terms.
+// It is an error to create an empty union; they are syntactically not possible.
+func NewUnion(terms []*Term) *Union {
+	if len(terms) == 0 {
+		panic("empty union")
+	}
+	return &Union{terms, nil}
+}
+
+func (u *Union) Len() int         { return len(u.terms) }
+func (u *Union) Term(i int) *Term { return u.terms[i] }
+
+func (u *Union) Underlying() Type { return u }
+func (u *Union) String() string   { return TypeString(u, nil) }
+
+// A Term represents a term in a Union.
+type Term term
+
+// NewTerm returns a new union term.
+func NewTerm(tilde bool, typ Type) *Term { return &Term{tilde, typ} }
+
+func (t *Term) Tilde() bool    { return t.tilde }
+func (t *Term) Type() Type     { return t.typ }
+func (t *Term) String() string { return (*term)(t).String() }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// Avoid excessive type-checking times due to quadratic termlist operations.
+const maxTermCount = 100
+
+// parseUnion parses the given list of type expressions tlist as a union of
+// those expressions. The result is a Union type, or Typ[Invalid] for some
+// errors.
+func parseUnion(check *Checker, tlist []ast.Expr) Type {
+	var terms []*Term
+	for _, x := range tlist {
+		tilde, typ := parseTilde(check, x)
+		if len(tlist) == 1 && !tilde {
+			return typ // single type (optimization)
+		}
+		if len(terms) >= maxTermCount {
+			check.errorf(x, _Todo, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+			return Typ[Invalid]
+		}
+		terms = append(terms, NewTerm(tilde, typ))
+	}
+
+	// Check validity of terms.
+	// Do this check later because it requires types to be set up.
+	// Note: This is a quadratic algorithm, but unions tend to be short.
+	check.later(func() {
+		for i, t := range terms {
+			if t.typ == Typ[Invalid] {
+				continue
+			}
+
+			x := tlist[i]
+			pos := x.Pos()
+			// We may not know the position of x if it was a typechecker-
+			// introduced ~T term for a type list entry T. Use the position
+			// of T instead.
+			// TODO(rfindley) remove this test once we don't support type lists anymore
+			if !pos.IsValid() {
+				if op, _ := x.(*ast.UnaryExpr); op != nil {
+					pos = op.X.Pos()
+				}
+			}
+
+			u := under(t.typ)
+			f, _ := u.(*Interface)
+			if t.tilde {
+				if f != nil {
+					check.errorf(x, _Todo, "invalid use of ~ (%s is an interface)", t.typ)
+					continue // don't report another error for t
+				}
+
+				if !Identical(u, t.typ) {
+					check.errorf(x, _Todo, "invalid use of ~ (underlying type of %s is %s)", t.typ, u)
+					continue // don't report another error for t
+				}
+			}
+
+			// Stand-alone embedded interfaces are ok and are handled by the single-type case
+			// in the beginning. Embedded interfaces with tilde are excluded above. If we reach
+			// here, we must have at least two terms in the union.
+			if f != nil && !f.typeSet().IsTypeSet() {
+				check.errorf(atPos(pos), _Todo, "cannot use %s in union (interface contains methods)", t)
+				continue // don't report another error for t
+			}
+
+			// Report overlapping (non-disjoint) terms such as
+			// a|a, a|~a, ~a|~a, and ~a|A (where under(A) == a).
+			if j := overlappingTerm(terms[:i], t); j >= 0 {
+				check.softErrorf(atPos(pos), _Todo, "overlapping terms %s and %s", t, terms[j])
+			}
+		}
+	})
+
+	return &Union{terms, nil}
+}
+
+func parseTilde(check *Checker, x ast.Expr) (tilde bool, typ Type) {
+	if op, _ := x.(*ast.UnaryExpr); op != nil && op.Op == token.TILDE {
+		x = op.X
+		tilde = true
+	}
+	typ = check.anyType(x)
+	// embedding stand-alone type parameters is not permitted (issue #47127).
+	if _, ok := under(typ).(*TypeParam); ok {
+		check.error(x, _Todo, "cannot embed a type parameter")
+		typ = Typ[Invalid]
+	}
+	return
+}
+
+// overlappingTerm reports the index of the term x in terms which is
+// overlapping (not disjoint) from y. The result is < 0 if there is no
+// such term.
+func overlappingTerm(terms []*Term, y *Term) int {
+	for i, x := range terms {
+		// disjoint requires non-nil, non-top arguments
+		if debug {
+			if x == nil || x.typ == nil || y == nil || y.typ == nil {
+				panic("empty or top union term")
+			}
+		}
+		if !(*term)(x).disjoint((*term)(y)) {
+			return i
+		}
+	}
+	return -1
+}
diff --git a/src/go/types/universe.go b/src/go/types/universe.go
index d7feb2c609efa93829bc90bd9176d1d9a423bf94..a2acfb5f69dc3850d7e513fcfb47981f96066d2c 100644
--- a/src/go/types/universe.go
+++ b/src/go/types/universe.go
@@ -8,7 +8,6 @@ package types
 
 import (
 	"go/constant"
-	"go/internal/typeparams"
 	"go/token"
 	"strings"
 )
@@ -22,11 +21,12 @@ var Universe *Scope
 var Unsafe *Package
 
 var (
-	universeIota  *Const
-	universeByte  *Basic // uint8 alias, but has name "byte"
-	universeRune  *Basic // int32 alias, but has name "rune"
-	universeAny   *Interface
-	universeError *Named
+	universeIota       Object
+	universeByte       Type // uint8 alias, but has name "byte"
+	universeRune       Type // int32 alias, but has name "rune"
+	universeAny        Object
+	universeError      Type
+	universeComparable Object
 )
 
 // Typ contains the predeclared *Basic types indexed by their
@@ -79,20 +79,30 @@ func defPredeclaredTypes() {
 		def(NewTypeName(token.NoPos, nil, t.name, t))
 	}
 
-	// any
-	// (Predeclared and entered into universe scope so we do all the
-	// usual checks; but removed again from scope later since it's
-	// only visible as constraint in a type parameter list.)
+	// type any = interface{}
 	def(NewTypeName(token.NoPos, nil, "any", &emptyInterface))
 
-	// Error has a nil package in its qualified name since it is in no package
+	// type error interface{ Error() string }
 	{
+		obj := NewTypeName(token.NoPos, nil, "error", nil)
+		obj.setColor(black)
 		res := NewVar(token.NoPos, nil, "", Typ[String])
-		sig := &Signature{results: NewTuple(res)}
+		sig := NewSignature(nil, nil, NewTuple(res), false)
 		err := NewFunc(token.NoPos, nil, "Error", sig)
-		typ := &Named{underlying: NewInterfaceType([]*Func{err}, nil).Complete()}
+		ityp := &Interface{obj, []*Func{err}, nil, nil, true, nil}
+		computeInterfaceTypeSet(nil, token.NoPos, ityp) // prevent races due to lazy computation of tset
+		typ := NewNamed(obj, ityp, nil)
 		sig.recv = NewVar(token.NoPos, nil, "", typ)
-		def(NewTypeName(token.NoPos, nil, "error", typ))
+		def(obj)
+	}
+
+	// type comparable interface{ /* type set marked comparable */ }
+	{
+		obj := NewTypeName(token.NoPos, nil, "comparable", nil)
+		obj.setColor(black)
+		ityp := &Interface{obj, nil, nil, nil, true, &_TypeSet{true, nil, allTermlist}}
+		NewNamed(obj, ityp, nil)
+		def(obj)
 	}
 }
 
@@ -202,33 +212,6 @@ func DefPredeclaredTestFuncs() {
 	def(newBuiltin(_Trace))
 }
 
-func defPredeclaredComparable() {
-	// The "comparable" interface can be imagined as defined like
-	//
-	// type comparable interface {
-	//         == () untyped bool
-	//         != () untyped bool
-	// }
-	//
-	// == and != cannot be user-declared but we can declare
-	// a magic method == and check for its presence when needed.
-
-	// Define interface { == () }. We don't care about the signature
-	// for == so leave it empty except for the receiver, which is
-	// set up later to match the usual interface method assumptions.
-	sig := new(Signature)
-	eql := NewFunc(token.NoPos, nil, "==", sig)
-	iface := NewInterfaceType([]*Func{eql}, nil).Complete()
-
-	// set up the defined type for the interface
-	obj := NewTypeName(token.NoPos, nil, "comparable", nil)
-	named := NewNamed(obj, iface, nil)
-	obj.color_ = black
-	sig.recv = NewVar(token.NoPos, nil, "", named) // complete == signature
-
-	def(obj)
-}
-
 func init() {
 	Universe = NewScope(nil, token.NoPos, token.NoPos, "universe")
 	Unsafe = NewPackage("unsafe", "unsafe")
@@ -238,18 +221,13 @@ func init() {
 	defPredeclaredConsts()
 	defPredeclaredNil()
 	defPredeclaredFuncs()
-	if typeparams.Enabled {
-		defPredeclaredComparable()
-	}
-
-	universeIota = Universe.Lookup("iota").(*Const)
-	universeByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
-	universeRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
-	universeAny = Universe.Lookup("any").(*TypeName).typ.(*Interface)
-	universeError = Universe.Lookup("error").(*TypeName).typ.(*Named)
 
-	// "any" is only visible as constraint in a type parameter list
-	delete(Universe.elems, "any")
+	universeIota = Universe.Lookup("iota")
+	universeByte = Universe.Lookup("byte").Type()
+	universeRune = Universe.Lookup("rune").Type()
+	universeAny = Universe.Lookup("any")
+	universeError = Universe.Lookup("error").Type()
+	universeComparable = Universe.Lookup("comparable")
 }
 
 // Objects with names containing blanks are internal and not entered into
@@ -281,6 +259,6 @@ func def(obj Object) {
 		}
 	}
 	if scope.Insert(obj) != nil {
-		panic("internal error: double declaration")
+		panic("double declaration of predeclared identifier")
 	}
 }
diff --git a/src/internal/abi/abi.go b/src/internal/abi/abi.go
index aaff9cece35720aef56455742b2f4556ba1f98d8..eadff248d99ff3a81f95b6b1643bcd8123625474 100644
--- a/src/internal/abi/abi.go
+++ b/src/internal/abi/abi.go
@@ -4,7 +4,10 @@
 
 package abi
 
-import "unsafe"
+import (
+	"internal/goarch"
+	"unsafe"
+)
 
 // RegArgs is a struct that has space for each argument
 // and return value register on the current architecture.
@@ -33,6 +36,46 @@ type RegArgs struct {
 	ReturnIsPtr IntArgRegBitmap
 }
 
+// IntRegArgAddr returns a pointer inside of r.Ints[reg] that is appropriately
+// offset for an argument of size argSize.
+//
+// argSize must be non-zero, fit in a register, and a power-of-two.
+//
+// This method is a helper for dealing with the endianness of different CPU
+// architectures, since sub-word-sized arguments in big endian architectures
+// need to be "aligned" to the upper edge of the register to be interpreted
+// by the CPU correctly.
+func (r *RegArgs) IntRegArgAddr(reg int, argSize uintptr) unsafe.Pointer {
+	if argSize > goarch.PtrSize || argSize == 0 || argSize&(argSize-1) != 0 {
+		panic("invalid argSize")
+	}
+	offset := uintptr(0)
+	if goarch.BigEndian {
+		offset = goarch.PtrSize - argSize
+	}
+	return unsafe.Pointer(uintptr(unsafe.Pointer(&r.Ints[reg])) + offset)
+}
+
+// FloatRegArgAddr returns a pointer inside of r.Floats[reg] that is appropriately
+// offset for an argument of size argSize.
+//
+// argSize must be non-zero, fit in a register, and a power-of-two.
+//
+// This method is a helper for dealing with the endianness of different CPU
+// architectures, since sub-word-sized arguments in big endian architectures
+// need to be "aligned" to the upper edge of the register to be interpreted
+// by the CPU correctly.
+func (r *RegArgs) FloatRegArgAddr(reg int, argSize uintptr) unsafe.Pointer {
+	if argSize > EffectiveFloatRegSize || argSize == 0 || argSize&(argSize-1) != 0 {
+		panic("invalid argSize")
+	}
+	offset := uintptr(0)
+	if goarch.BigEndian {
+		offset = EffectiveFloatRegSize - argSize
+	}
+	return unsafe.Pointer(uintptr(unsafe.Pointer(&r.Floats[reg])) + offset)
+}
+
 // IntArgRegBitmap is a bitmap large enough to hold one bit per
 // integer argument/return register.
 type IntArgRegBitmap [(IntArgRegs + 7) / 8]uint8
diff --git a/src/internal/abi/abi_amd64.go b/src/internal/abi/abi_amd64.go
index aff71f6a58a9553a7bc7175dfb287cf13e907d8b..d3c567822311b162b2ff2be048361bb5ac1819eb 100644
--- a/src/internal/abi/abi_amd64.go
+++ b/src/internal/abi/abi_amd64.go
@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build goexperiment.regabireflect
-// +build goexperiment.regabireflect
-
 package abi
 
 const (
diff --git a/src/internal/abi/abi_arm64.go b/src/internal/abi/abi_arm64.go
new file mode 100644
index 0000000000000000000000000000000000000000..7544d7506edb03d93be1ba4bbd626960d9c49528
--- /dev/null
+++ b/src/internal/abi/abi_arm64.go
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build goexperiment.regabireflect
+// +build goexperiment.regabireflect
+
+package abi
+
+const (
+	// See abi_generic.go.
+
+	// R0 - R15.
+	IntArgRegs = 16
+
+	// F0 - F15.
+	FloatArgRegs = 16
+
+	EffectiveFloatRegSize = 8
+)
diff --git a/src/internal/abi/abi_generic.go b/src/internal/abi/abi_generic.go
index 69400f930fb12b50b1df1a24a89aaa0e577d17b5..e8f94f805f57e8198c295acf97a6272b3884f3af 100644
--- a/src/internal/abi/abi_generic.go
+++ b/src/internal/abi/abi_generic.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !goexperiment.regabireflect
-// +build !goexperiment.regabireflect
+//go:build !goexperiment.regabireflect && !amd64
+// +build !goexperiment.regabireflect,!amd64
 
 package abi
 
diff --git a/src/internal/buildcfg/exp.go b/src/internal/buildcfg/exp.go
index 9a60253aab9b1830815bf4b69ffd3fee32474974..3844e4f021193cdff6cf9f373c863e5ff6bd11c5 100644
--- a/src/internal/buildcfg/exp.go
+++ b/src/internal/buildcfg/exp.go
@@ -46,13 +46,11 @@ var FramePointerEnabled = GOARCH == "amd64" || GOARCH == "arm64"
 //
 // TODO(mdempsky): Move to internal/goexperiment.
 func ParseGOEXPERIMENT(goos, goarch, goexp string) (flags, baseline goexperiment.Flags, err error) {
-	regabiSupported := goarch == "amd64" && (goos == "android" || goos == "linux" || goos == "darwin" || goos == "windows")
+	regabiSupported := goarch == "amd64" || goarch == "arm64"
 
 	baseline = goexperiment.Flags{
 		RegabiWrappers: regabiSupported,
-		RegabiG:        regabiSupported,
 		RegabiReflect:  regabiSupported,
-		RegabiDefer:    regabiSupported,
 		RegabiArgs:     regabiSupported,
 	}
 
@@ -78,9 +76,7 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (flags, baseline goexperiment
 		// do the right thing.
 		names["regabi"] = func(v bool) {
 			flags.RegabiWrappers = v
-			flags.RegabiG = v
 			flags.RegabiReflect = v
-			flags.RegabiDefer = v
 			flags.RegabiArgs = v
 		}
 
@@ -109,20 +105,20 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (flags, baseline goexperiment
 		}
 	}
 
-	// regabi is only supported on amd64.
-	if goarch != "amd64" {
-		flags.RegabiWrappers = false
-		flags.RegabiG = false
+	// regabi is always enabled on amd64.
+	if goarch == "amd64" {
+		flags.RegabiWrappers = true
+		flags.RegabiReflect = true
+		flags.RegabiArgs = true
+	}
+	// regabi is only supported on amd64 and arm64.
+	if goarch != "amd64" && goarch != "arm64" {
 		flags.RegabiReflect = false
-		flags.RegabiDefer = false
 		flags.RegabiArgs = false
 	}
 	// Check regabi dependencies.
-	if flags.RegabiG && !flags.RegabiWrappers {
-		err = fmt.Errorf("GOEXPERIMENT regabig requires regabiwrappers")
-	}
-	if flags.RegabiArgs && !(flags.RegabiWrappers && flags.RegabiG && flags.RegabiReflect && flags.RegabiDefer) {
-		err = fmt.Errorf("GOEXPERIMENT regabiargs requires regabiwrappers,regabig,regabireflect,regabidefer")
+	if flags.RegabiArgs && !(flags.RegabiWrappers && flags.RegabiReflect) {
+		err = fmt.Errorf("GOEXPERIMENT regabiargs requires regabiwrappers,regabireflect")
 	}
 	return
 }
@@ -162,7 +158,11 @@ func expList(exp, base *goexperiment.Flags, all bool) []string {
 // GOEXPERIMENT is exactly what a user would set on the command line
 // to get the set of enabled experiments.
 func GOEXPERIMENT() string {
-	return strings.Join(expList(&Experiment, &experimentBaseline, false), ",")
+	goexp := strings.Join(expList(&Experiment, &experimentBaseline, false), ",")
+	if goexp == "" && DefaultGOEXPERIMENT != "" {
+		goexp = "," // non-empty to override DefaultGOEXPERIMENT
+	}
+	return goexp
 }
 
 // EnabledExperiments returns a list of enabled experiments, as
diff --git a/src/internal/bytealg/bytealg.go b/src/internal/bytealg/bytealg.go
index 6b2b540acc8846ce1707641930e3d185690ab295..ebebce75fe484a0317be60a053c473726b944f72 100644
--- a/src/internal/bytealg/bytealg.go
+++ b/src/internal/bytealg/bytealg.go
@@ -11,7 +11,6 @@ import (
 
 // Offsets into internal/cpu records for use in assembly.
 const (
-	offsetX86HasSSE2   = unsafe.Offsetof(cpu.X86.HasSSE2)
 	offsetX86HasSSE42  = unsafe.Offsetof(cpu.X86.HasSSE42)
 	offsetX86HasAVX2   = unsafe.Offsetof(cpu.X86.HasAVX2)
 	offsetX86HasPOPCNT = unsafe.Offsetof(cpu.X86.HasPOPCNT)
diff --git a/src/internal/bytealg/compare_386.s b/src/internal/bytealg/compare_386.s
index 0981983d20f313bd5fd2f750afe89b6aab61f8fc..27b660ccf7c526ac70be5f016695cb19238aa19c 100644
--- a/src/internal/bytealg/compare_386.s
+++ b/src/internal/bytealg/compare_386.s
@@ -36,8 +36,9 @@ TEXT cmpbody<>(SB),NOSPLIT,$0-0
 	JEQ	allsame
 	CMPL	BP, $4
 	JB	small
-	CMPB	internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE	mediumloop
+#ifdef GO386_softfloat
+	JMP	mediumloop
+#endif
 largeloop:
 	CMPL	BP, $16
 	JB	mediumloop
diff --git a/src/internal/bytealg/compare_amd64.s b/src/internal/bytealg/compare_amd64.s
index 8295acb03a184d17d28bae5f141d06a7de437a05..4ccaca5e87b23b397078d20ed8b413773469d2d5 100644
--- a/src/internal/bytealg/compare_amd64.s
+++ b/src/internal/bytealg/compare_amd64.s
@@ -6,7 +6,6 @@
 #include "textflag.h"
 
 TEXT ·Compare(SB),NOSPLIT,$0-56
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a_base (want in SI)
 	// BX = a_len  (want in BX)
 	// CX = a_cap  (unused)
@@ -15,17 +14,9 @@ TEXT ·Compare(SB),NOSPLIT,$0-56
 	// R8 = b_cap  (unused)
 	MOVQ	SI, DX
 	MOVQ	AX, SI
-#else
-	MOVQ	a_base+0(FP), SI
-	MOVQ	a_len+8(FP), BX
-	MOVQ	b_base+24(FP), DI
-	MOVQ	b_len+32(FP), DX
-	LEAQ	ret+48(FP), R9
-#endif
 	JMP	cmpbody<>(SB)
 
 TEXT runtime·cmpstring(SB),NOSPLIT,$0-40
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a_base (want in SI)
 	// BX = a_len  (want in BX)
 	// CX = b_base (want in DI)
@@ -33,13 +24,6 @@ TEXT runtime·cmpstring(SB),NOSPLIT,$0-40
 	MOVQ	AX, SI
 	MOVQ	DI, DX
 	MOVQ	CX, DI
-#else
-	MOVQ	a_base+0(FP), SI
-	MOVQ	a_len+8(FP), BX
-	MOVQ	b_base+16(FP), DI
-	MOVQ	b_len+24(FP), DX
-	LEAQ	ret+32(FP), R9
-#endif
 	JMP	cmpbody<>(SB)
 
 // input:
@@ -47,12 +31,8 @@ TEXT runtime·cmpstring(SB),NOSPLIT,$0-40
 //   DI = b
 //   BX = alen
 //   DX = blen
-#ifndef GOEXPERIMENT_regabiargs
-//   R9 = address of output word (stores -1/0/1 here)
-#else
 // output:
 //   AX = output (-1/0/1)
-#endif
 TEXT cmpbody<>(SB),NOSPLIT,$0-0
 	CMPQ	SI, DI
 	JEQ	allsame
@@ -100,9 +80,6 @@ diff16:
 	CMPB	CX, (DI)(BX*1)
 	SETHI	AX
 	LEAQ	-1(AX*2), AX	// convert 1/0 to +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// 0 through 16 bytes left, alen>=8, blen>=8
@@ -128,9 +105,6 @@ diff8:
 	SHRQ	CX, AX	// move a's bit to bottom
 	ANDQ	$1, AX	// mask bit
 	LEAQ	-1(AX*2), AX // 1/0 => +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// 0-7 bytes in common
@@ -169,9 +143,6 @@ di_finish:
 	SHRQ	CX, SI	// move a's bit to bottom
 	ANDQ	$1, SI	// mask bit
 	LEAQ	-1(SI*2), AX // 1/0 => +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 allsame:
@@ -181,9 +152,6 @@ allsame:
 	SETGT	AX	// 1 if alen > blen
 	SETEQ	CX	// 1 if alen == blen
 	LEAQ	-1(CX)(AX*2), AX	// 1,0,-1 result
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// this works for >= 64 bytes of data.
diff --git a/src/internal/bytealg/compare_arm64.s b/src/internal/bytealg/compare_arm64.s
index 56d56f241eb8696d2a22c6133148ce7f8625c933..5a80207258313dbb984be319d5818aa74498fcea 100644
--- a/src/internal/bytealg/compare_arm64.s
+++ b/src/internal/bytealg/compare_arm64.s
@@ -5,65 +5,88 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-TEXT ·Compare(SB),NOSPLIT|NOFRAME,$0-56
-	MOVD	a_base+0(FP), R2
-	MOVD	a_len+8(FP), R0
-	MOVD	b_base+24(FP), R3
-	MOVD	b_len+32(FP), R1
+TEXT ·Compare(SB),NOSPLIT|NOFRAME,$0-56
+#ifdef GOEXPERIMENT_regabiargs
+	// R0 = a_base (want in R0)
+	// R1 = a_len  (want in R1)
+	// R2 = a_cap  (unused)
+	// R3 = b_base (want in R2)
+	// R4 = b_len  (want in R3)
+	// R5 = b_cap  (unused)
+	MOVD	R3, R2
+	MOVD	R4, R3
+#else
+	MOVD	a_base+0(FP), R0
+	MOVD	a_len+8(FP), R1
+	MOVD	b_base+24(FP), R2
+	MOVD	b_len+32(FP), R3
 	MOVD	$ret+48(FP), R7
+#endif
 	B	cmpbody<>(SB)
 
-TEXT runtime·cmpstring(SB),NOSPLIT|NOFRAME,$0-40
-	MOVD	a_base+0(FP), R2
-	MOVD	a_len+8(FP), R0
-	MOVD	b_base+16(FP), R3
-	MOVD	b_len+24(FP), R1
+TEXT runtime·cmpstring(SB),NOSPLIT|NOFRAME,$0-40
+#ifdef GOEXPERIMENT_regabiargs
+	// R0 = a_base
+	// R1 = a_len
+	// R2 = b_base
+	// R3 = b_len
+#else
+	MOVD	a_base+0(FP), R0
+	MOVD	a_len+8(FP), R1
+	MOVD	b_base+16(FP), R2
+	MOVD	b_len+24(FP), R3
 	MOVD	$ret+32(FP), R7
+#endif
 	B	cmpbody<>(SB)
 
 // On entry:
-// R0 is the length of a
-// R1 is the length of b
-// R2 points to the start of a
-// R3 points to the start of b
+// R0 points to the start of a
+// R1 is the length of a
+// R2 points to the start of b
+// R3 is the length of b
+#ifndef GOEXPERIMENT_regabiargs
 // R7 points to return value (-1/0/1 will be written here)
+#endif
 //
 // On exit:
+#ifdef GOEXPERIMENT_regabiargs
+// R0 is the result
+#endif
 // R4, R5, R6, R8, R9 and R10 are clobbered
 TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0-0
-	CMP	R2, R3
+	CMP	R0, R2
 	BEQ	samebytes         // same starting pointers; compare lengths
-	CMP	R0, R1
-	CSEL	LT, R1, R0, R6    // R6 is min(R0, R1)
+	CMP	R1, R3
+	CSEL	LT, R3, R1, R6    // R6 is min(R1, R3)
 
 	CBZ	R6, samebytes
 	BIC	$0xf, R6, R10
 	CBZ	R10, small        // length < 16
-	ADD	R2, R10           // end of chunk16
+	ADD	R0, R10           // end of chunk16
 	// length >= 16
 chunk16_loop:
-	LDP.P	16(R2), (R4, R8)
-	LDP.P	16(R3), (R5, R9)
+	LDP.P	16(R0), (R4, R8)
+	LDP.P	16(R2), (R5, R9)
 	CMP	R4, R5
 	BNE	cmp
 	CMP	R8, R9
 	BNE	cmpnext
-	CMP	R10, R2
+	CMP	R10, R0
 	BNE	chunk16_loop
 	AND	$0xf, R6, R6
 	CBZ	R6, samebytes
 	SUBS	$8, R6
 	BLT	tail
 	// the length of tail > 8 bytes
-	MOVD.P	8(R2), R4
-	MOVD.P	8(R3), R5
+	MOVD.P	8(R0), R4
+	MOVD.P	8(R2), R5
 	CMP	R4, R5
 	BNE	cmp
 	SUB	$8, R6
 	// compare last 8 bytes
 tail:
-	MOVD	(R2)(R6), R4
-	MOVD	(R3)(R6), R5
+	MOVD	(R0)(R6), R4
+	MOVD	(R2)(R6), R5
 	CMP	R4, R5
 	BEQ	samebytes
 cmp:
@@ -71,52 +94,56 @@ cmp:
 	REV	R5, R5
 	CMP	R4, R5
 ret:
-	MOVD	$1, R4
-	CNEG	HI, R4, R4
-	MOVD	R4, (R7)
+	MOVD	$1, R0
+	CNEG	HI, R0, R0
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	R0, (R7)
+#endif
 	RET
 small:
 	TBZ	$3, R6, lt_8
-	MOVD	(R2), R4
-	MOVD	(R3), R5
+	MOVD	(R0), R4
+	MOVD	(R2), R5
 	CMP	R4, R5
 	BNE	cmp
 	SUBS	$8, R6
 	BEQ	samebytes
+	ADD	$8, R0
 	ADD	$8, R2
-	ADD	$8, R3
 	SUB	$8, R6
 	B	tail
 lt_8:
 	TBZ	$2, R6, lt_4
-	MOVWU	(R2), R4
-	MOVWU	(R3), R5
+	MOVWU	(R0), R4
+	MOVWU	(R2), R5
 	CMPW	R4, R5
 	BNE	cmp
 	SUBS	$4, R6
 	BEQ	samebytes
+	ADD	$4, R0
 	ADD	$4, R2
-	ADD	$4, R3
 lt_4:
 	TBZ	$1, R6, lt_2
-	MOVHU	(R2), R4
-	MOVHU	(R3), R5
+	MOVHU	(R0), R4
+	MOVHU	(R2), R5
 	CMPW	R4, R5
 	BNE	cmp
+	ADD	$2, R0
 	ADD	$2, R2
-	ADD	$2, R3
 lt_2:
 	TBZ	$0, R6, samebytes
 one:
-	MOVBU	(R2), R4
-	MOVBU	(R3), R5
+	MOVBU	(R0), R4
+	MOVBU	(R2), R5
 	CMPW	R4, R5
 	BNE	ret
 samebytes:
-	CMP	R1, R0
-	CSET	NE, R4
-	CNEG	LO, R4, R4
-	MOVD	R4, (R7)
+	CMP	R3, R1
+	CSET	NE, R0
+	CNEG	LO, R0, R0
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	R0, (R7)
+#endif
 	RET
 cmpnext:
 	REV	R8, R4
diff --git a/src/internal/bytealg/equal_386.s b/src/internal/bytealg/equal_386.s
index 87233635a927d35cd6018fa692f3081317575eca..58b3cbe3d07194b5eddd4a3ef2f0b5425d8cb485 100644
--- a/src/internal/bytealg/equal_386.s
+++ b/src/internal/bytealg/equal_386.s
@@ -43,8 +43,9 @@ TEXT memeqbody<>(SB),NOSPLIT,$0-0
 hugeloop:
 	CMPL	BX, $64
 	JB	bigloop
-	CMPB	internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE	bigloop
+#ifdef GO386_softfloat
+	JMP	bigloop
+#endif
 	MOVOU	(SI), X0
 	MOVOU	(DI), X1
 	MOVOU	16(SI), X2
diff --git a/src/internal/bytealg/equal_amd64.s b/src/internal/bytealg/equal_amd64.s
index 6f12d2a1690380d5e92326a96f775e799165b6e5..dd46e2e0fdfb0ea32485f4660ecfa66197b764db 100644
--- a/src/internal/bytealg/equal_amd64.s
+++ b/src/internal/bytealg/equal_amd64.s
@@ -7,7 +7,6 @@
 
 // memequal(a, b unsafe.Pointer, size uintptr) bool
 TEXT runtime·memequal(SB),NOSPLIT,$0-25
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a    (want in SI)
 	// BX = b    (want in DI)
 	// CX = size (want in BX)
@@ -20,22 +19,9 @@ neq:
 	MOVQ	BX, DI
 	MOVQ	CX, BX
 	JMP	memeqbody<>(SB)
-#else
-	MOVQ	a+0(FP), SI
-	MOVQ	b+8(FP), DI
-	CMPQ	SI, DI
-	JEQ	eq
-	MOVQ	size+16(FP), BX
-	LEAQ	ret+24(FP), AX
-	JMP	memeqbody<>(SB)
-eq:
-	MOVB	$1, ret+24(FP)
-	RET
-#endif
 
 // memequal_varlen(a, b unsafe.Pointer) bool
 TEXT runtime·memequal_varlen(SB),NOSPLIT,$0-17
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a       (want in SI)
 	// BX = b       (want in DI)
 	// 8(DX) = size (want in BX)
@@ -48,29 +34,13 @@ neq:
 	MOVQ	BX, DI
 	MOVQ	8(DX), BX    // compiler stores size at offset 8 in the closure
 	JMP	memeqbody<>(SB)
-#else
-	MOVQ	a+0(FP), SI
-	MOVQ	b+8(FP), DI
-	CMPQ	SI, DI
-	JEQ	eq
-	MOVQ	8(DX), BX    // compiler stores size at offset 8 in the closure
-	LEAQ	ret+16(FP), AX
-	JMP	memeqbody<>(SB)
-eq:
-	MOVB	$1, ret+16(FP)
-	RET
-#endif
 
 // Input:
 //   a in SI
 //   b in DI
 //   count in BX
-#ifndef GOEXPERIMENT_regabiargs
-//   address of result byte in AX
-#else
 // Output:
 //   result in AX
-#endif
 TEXT memeqbody<>(SB),NOSPLIT,$0-0
 	CMPQ	BX, $8
 	JB	small
@@ -104,11 +74,7 @@ hugeloop:
 	SUBQ	$64, BX
 	CMPL	DX, $0xffff
 	JEQ	hugeloop
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 	// 64 bytes at a time using ymm registers
@@ -129,11 +95,7 @@ hugeloop_avx2:
 	CMPL	DX, $0xffffffff
 	JEQ	hugeloop_avx2
 	VZEROUPPER
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 bigloop_avx2:
@@ -150,11 +112,7 @@ bigloop:
 	SUBQ	$8, BX
 	CMPQ	CX, DX
 	JEQ	bigloop
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 	// remaining 0-8 bytes
@@ -162,11 +120,7 @@ leftover:
 	MOVQ	-8(SI)(BX*1), CX
 	MOVQ	-8(DI)(BX*1), DX
 	CMPQ	CX, DX
-#ifdef GOEXPERIMENT_regabiargs
 	SETEQ	AX
-#else
-	SETEQ	(AX)
-#endif
 	RET
 
 small:
@@ -201,10 +155,5 @@ di_finish:
 	SUBQ	SI, DI
 	SHLQ	CX, DI
 equal:
-#ifdef GOEXPERIMENT_regabiargs
 	SETEQ	AX
-#else
-	SETEQ	(AX)
-#endif
 	RET
-
diff --git a/src/internal/bytealg/equal_arm64.s b/src/internal/bytealg/equal_arm64.s
index 01aa7b7b7aa8adbc0f1945a072e6c2a576c082fc..cf5cf54e5971a33223f909696503c1bace31baea 100644
--- a/src/internal/bytealg/equal_arm64.s
+++ b/src/internal/bytealg/equal_arm64.s
@@ -6,58 +6,70 @@
 #include "textflag.h"
 
 // memequal(a, b unsafe.Pointer, size uintptr) bool
-TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-25
-	MOVD	size+16(FP), R1
+TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-25
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	size+16(FP), R2
+#endif
 	// short path to handle 0-byte case
-	CBZ	R1, equal
+	CBZ	R2, equal
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	a+0(FP), R0
-	MOVD	b+8(FP), R2
+	MOVD	b+8(FP), R1
 	MOVD	$ret+24(FP), R8
+#endif
 	B	memeqbody<>(SB)
 equal:
 	MOVD	$1, R0
+#ifndef GOEXPERIMENT_regabiargs
 	MOVB	R0, ret+24(FP)
+#endif
 	RET
 
 // memequal_varlen(a, b unsafe.Pointer) bool
-TEXT runtime·memequal_varlen(SB),NOSPLIT,$40-17
-	MOVD	a+0(FP), R3
-	MOVD	b+8(FP), R4
-	CMP	R3, R4
+TEXT runtime·memequal_varlen(SB),NOSPLIT,$0-17
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	a+0(FP), R0
+	MOVD	b+8(FP), R1
+#endif
+	CMP	R0, R1
 	BEQ	eq
-	MOVD	8(R26), R5    // compiler stores size at offset 8 in the closure
-	CBZ	R5, eq
-	MOVD	R3, 8(RSP)
-	MOVD	R4, 16(RSP)
-	MOVD	R5, 24(RSP)
-	BL	runtime·memequal(SB)
-	MOVBU	32(RSP), R3
-	MOVB	R3, ret+16(FP)
-	RET
+	MOVD	8(R26), R2    // compiler stores size at offset 8 in the closure
+	CBZ	R2, eq
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	$ret+16(FP), R8
+#endif
+	B	memeqbody<>(SB)
 eq:
-	MOVD	$1, R3
-	MOVB	R3, ret+16(FP)
+	MOVD	$1, R0
+#ifndef GOEXPERIMENT_regabiargs
+	MOVB	R0, ret+16(FP)
+#endif
 	RET
 
 // input:
 // R0: pointer a
-// R1: data len
-// R2: pointer b
+// R1: pointer b
+// R2: data len
+#ifdef GOEXPERIMENT_regabiargs
+// at return: result in R0
+#else
 // R8: address to put result
+#endif
+
 TEXT memeqbody<>(SB),NOSPLIT,$0
-	CMP	$1, R1
+	CMP	$1, R2
 	// handle 1-byte special case for better performance
 	BEQ	one
-	CMP	$16, R1
+	CMP	$16, R2
 	// handle specially if length < 16
 	BLO	tail
-	BIC	$0x3f, R1, R3
+	BIC	$0x3f, R2, R3
 	CBZ	R3, chunk16
 	// work with 64-byte chunks
 	ADD	R3, R0, R6	// end of chunks
 chunk64_loop:
 	VLD1.P	(R0), [V0.D2, V1.D2, V2.D2, V3.D2]
-	VLD1.P	(R2), [V4.D2, V5.D2, V6.D2, V7.D2]
+	VLD1.P	(R1), [V4.D2, V5.D2, V6.D2, V7.D2]
 	VCMEQ	V0.D2, V4.D2, V8.D2
 	VCMEQ	V1.D2, V5.D2, V9.D2
 	VCMEQ	V2.D2, V6.D2, V10.D2
@@ -71,66 +83,72 @@ chunk64_loop:
 	CBZ	R4, not_equal
 	CBZ	R5, not_equal
 	BNE	chunk64_loop
-	AND	$0x3f, R1, R1
-	CBZ	R1, equal
+	AND	$0x3f, R2, R2
+	CBZ	R2, equal
 chunk16:
 	// work with 16-byte chunks
-	BIC	$0xf, R1, R3
+	BIC	$0xf, R2, R3
 	CBZ	R3, tail
 	ADD	R3, R0, R6	// end of chunks
 chunk16_loop:
 	LDP.P	16(R0), (R4, R5)
-	LDP.P	16(R2), (R7, R9)
+	LDP.P	16(R1), (R7, R9)
 	EOR	R4, R7
 	CBNZ	R7, not_equal
 	EOR	R5, R9
 	CBNZ	R9, not_equal
 	CMP	R0, R6
 	BNE	chunk16_loop
-	AND	$0xf, R1, R1
-	CBZ	R1, equal
+	AND	$0xf, R2, R2
+	CBZ	R2, equal
 tail:
 	// special compare of tail with length < 16
-	TBZ	$3, R1, lt_8
+	TBZ	$3, R2, lt_8
 	MOVD	(R0), R4
-	MOVD	(R2), R5
+	MOVD	(R1), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
-	SUB	$8, R1, R6	// offset of the last 8 bytes
+	SUB	$8, R2, R6	// offset of the last 8 bytes
 	MOVD	(R0)(R6), R4
-	MOVD	(R2)(R6), R5
+	MOVD	(R1)(R6), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
 	B	equal
 lt_8:
-	TBZ	$2, R1, lt_4
+	TBZ	$2, R2, lt_4
 	MOVWU	(R0), R4
-	MOVWU	(R2), R5
+	MOVWU	(R1), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
-	SUB	$4, R1, R6	// offset of the last 4 bytes
+	SUB	$4, R2, R6	// offset of the last 4 bytes
 	MOVWU	(R0)(R6), R4
-	MOVWU	(R2)(R6), R5
+	MOVWU	(R1)(R6), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
 	B	equal
 lt_4:
-	TBZ	$1, R1, lt_2
+	TBZ	$1, R2, lt_2
 	MOVHU.P	2(R0), R4
-	MOVHU.P	2(R2), R5
+	MOVHU.P	2(R1), R5
 	CMP	R4, R5
 	BNE	not_equal
 lt_2:
-	TBZ	$0, R1, equal
+	TBZ	$0, R2, equal
 one:
 	MOVBU	(R0), R4
-	MOVBU	(R2), R5
+	MOVBU	(R1), R5
 	CMP	R4, R5
 	BNE	not_equal
 equal:
 	MOVD	$1, R0
+#ifndef GOEXPERIMENT_regabiargs
 	MOVB	R0, (R8)
+#endif
 	RET
 not_equal:
+#ifdef GOEXPERIMENT_regabiargs
+	MOVB	ZR, R0
+#else
 	MOVB	ZR, (R8)
+#endif
 	RET
diff --git a/src/internal/cpu/cpu.go b/src/internal/cpu/cpu.go
index dab5d068ef36e4ef5bf1d028bced35fc7cd5fa94..4f0c5d2896bfa9d13489ddfc3308bc976c6ea132 100644
--- a/src/internal/cpu/cpu.go
+++ b/src/internal/cpu/cpu.go
@@ -36,7 +36,7 @@ var X86 struct {
 	HasOSXSAVE   bool
 	HasPCLMULQDQ bool
 	HasPOPCNT    bool
-	HasSSE2      bool
+	HasRDTSCP    bool
 	HasSSE3      bool
 	HasSSSE3     bool
 	HasSSE41     bool
diff --git a/src/internal/cpu/cpu_x86.go b/src/internal/cpu/cpu_x86.go
index fd1217a05d7cab12bf2b7c0acd38553cafd47c03..1582e832a45a548362b11f9b8ecfc792e29508fd 100644
--- a/src/internal/cpu/cpu_x86.go
+++ b/src/internal/cpu/cpu_x86.go
@@ -37,6 +37,9 @@ const (
 	cpuid_BMI2 = 1 << 8
 	cpuid_ERMS = 1 << 9
 	cpuid_ADX  = 1 << 19
+
+	// edx bits for CPUID 0x80000001
+	cpuid_RDTSCP = 1 << 27
 )
 
 var maxExtendedFunctionInformation uint32
@@ -53,13 +56,11 @@ func doinit() {
 		{Name: "fma", Feature: &X86.HasFMA},
 		{Name: "pclmulqdq", Feature: &X86.HasPCLMULQDQ},
 		{Name: "popcnt", Feature: &X86.HasPOPCNT},
+		{Name: "rdtscp", Feature: &X86.HasRDTSCP},
 		{Name: "sse3", Feature: &X86.HasSSE3},
 		{Name: "sse41", Feature: &X86.HasSSE41},
 		{Name: "sse42", Feature: &X86.HasSSE42},
 		{Name: "ssse3", Feature: &X86.HasSSSE3},
-
-		// These capabilities should always be enabled on amd64:
-		{Name: "sse2", Feature: &X86.HasSSE2, Required: GOARCH == "amd64"},
 	}
 
 	maxID, _, _, _ := cpuid(0, 0)
@@ -70,8 +71,7 @@ func doinit() {
 
 	maxExtendedFunctionInformation, _, _, _ = cpuid(0x80000000, 0)
 
-	_, _, ecx1, edx1 := cpuid(1, 0)
-	X86.HasSSE2 = isSet(edx1, cpuid_SSE2)
+	_, _, ecx1, _ := cpuid(1, 0)
 
 	X86.HasSSE3 = isSet(ecx1, cpuid_SSE3)
 	X86.HasPCLMULQDQ = isSet(ecx1, cpuid_PCLMULQDQ)
@@ -112,6 +112,16 @@ func doinit() {
 	X86.HasBMI2 = isSet(ebx7, cpuid_BMI2)
 	X86.HasERMS = isSet(ebx7, cpuid_ERMS)
 	X86.HasADX = isSet(ebx7, cpuid_ADX)
+
+	var maxExtendedInformation uint32
+	maxExtendedInformation, _, _, _ = cpuid(0x80000000, 0)
+
+	if maxExtendedInformation < 0x80000001 {
+		return
+	}
+
+	_, _, _, edxExt1 := cpuid(0x80000001, 0)
+	X86.HasRDTSCP = isSet(edxExt1, cpuid_RDTSCP)
 }
 
 func isSet(hwc uint32, value uint32) bool {
diff --git a/src/internal/cpu/cpu_x86_test.go b/src/internal/cpu/cpu_x86_test.go
index e3e16cc1612e05955295a965204ca0dc66e497aa..de1c5fb3b06099ac52dd168ea868a840991342ba 100644
--- a/src/internal/cpu/cpu_x86_test.go
+++ b/src/internal/cpu/cpu_x86_test.go
@@ -10,7 +10,6 @@ package cpu_test
 import (
 	. "internal/cpu"
 	"os"
-	"runtime"
 	"testing"
 )
 
@@ -20,23 +19,6 @@ func TestX86ifAVX2hasAVX(t *testing.T) {
 	}
 }
 
-func TestDisableSSE2(t *testing.T) {
-	runDebugOptionsTest(t, "TestSSE2DebugOption", "cpu.sse2=off")
-}
-
-func TestSSE2DebugOption(t *testing.T) {
-	MustHaveDebugOptionsSupport(t)
-
-	if os.Getenv("GODEBUG") != "cpu.sse2=off" {
-		t.Skipf("skipping test: GODEBUG=cpu.sse2=off not set")
-	}
-
-	want := runtime.GOARCH != "386" // SSE2 can only be disabled on 386.
-	if got := X86.HasSSE2; got != want {
-		t.Errorf("X86.HasSSE2 on %s expected %v, got %v", runtime.GOARCH, want, got)
-	}
-}
-
 func TestDisableSSE3(t *testing.T) {
 	runDebugOptionsTest(t, "TestSSE3DebugOption", "cpu.sse3=off")
 }
diff --git a/src/internal/goarch/gengoarch.go b/src/internal/goarch/gengoarch.go
new file mode 100644
index 0000000000000000000000000000000000000000..af15518ad8bdc474d000e6ce93cf0124a60e9607
--- /dev/null
+++ b/src/internal/goarch/gengoarch.go
@@ -0,0 +1,59 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+var goarches []string
+
+func main() {
+	data, err := os.ReadFile("../../go/build/syslist.go")
+	if err != nil {
+		log.Fatal(err)
+	}
+	const goarchPrefix = `const goarchList = `
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, goarchPrefix) {
+			text, err := strconv.Unquote(strings.TrimPrefix(line, goarchPrefix))
+			if err != nil {
+				log.Fatalf("parsing goarchList: %v", err)
+			}
+			goarches = strings.Fields(text)
+		}
+	}
+
+	for _, target := range goarches {
+		if target == "amd64p32" {
+			continue
+		}
+		var buf bytes.Buffer
+		fmt.Fprintf(&buf, "// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.\n\n")
+		fmt.Fprintf(&buf, "//go:build %s\n", target)
+		fmt.Fprintf(&buf, "// +build %s\n\n", target) // must explicitly include target for bootstrapping purposes
+		fmt.Fprintf(&buf, "package goarch\n\n")
+		fmt.Fprintf(&buf, "const GOARCH = `%s`\n\n", target)
+		for _, goarch := range goarches {
+			value := 0
+			if goarch == target {
+				value = 1
+			}
+			fmt.Fprintf(&buf, "const Is%s = %d\n", strings.Title(goarch), value)
+		}
+		err := os.WriteFile("zgoarch_"+target+".go", buf.Bytes(), 0666)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}
diff --git a/src/runtime/internal/sys/arch.go b/src/internal/goarch/goarch.go
similarity index 74%
rename from src/runtime/internal/sys/arch.go
rename to src/internal/goarch/goarch.go
index 3c99a2f7da0831048e2aa5ae24cb8914e5d83785..921f5a208fc6330adc2c71bca38ab6789b612d5a 100644
--- a/src/runtime/internal/sys/arch.go
+++ b/src/internal/goarch/goarch.go
@@ -1,8 +1,15 @@
-// Copyright 2014 The Go Authors. All rights reserved.
+// Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+// package goarch contains GOARCH-specific constants.
+package goarch
+
+// The next line makes 'go generate' write the zgoarch*.go files with
+// per-arch information, including constants named $GOARCH for every
+// GOARCH. The constant is 1 on the current system, 0 otherwise; multiplying
+// by them is useful for defining GOARCH-specific constants.
+//go:generate go run gengoarch.go
 
 type ArchFamilyType int
 
@@ -23,14 +30,11 @@ const (
 // It is also the size of the machine's native word size (that is, 4 on 32-bit systems, 8 on 64-bit).
 const PtrSize = 4 << (^uintptr(0) >> 63)
 
-// AIX requires a larger stack for syscalls.
-const StackGuardMultiplier = StackGuardMultiplierDefault*(1-GoosAix) + 2*GoosAix
-
 // ArchFamily is the architecture family (AMD64, ARM, ...)
 const ArchFamily ArchFamilyType = _ArchFamily
 
 // BigEndian reports whether the architecture is big-endian.
-const BigEndian = GoarchArmbe|GoarchArm64be|GoarchMips|GoarchMips64|GoarchPpc|GoarchPpc64|GoarchS390|GoarchS390x|GoarchSparc|GoarchSparc64 == 1
+const BigEndian = IsArmbe|IsArm64be|IsMips|IsMips64|IsPpc|IsPpc64|IsS390|IsS390x|IsSparc|IsSparc64 == 1
 
 // DefaultPhysPageSize is the default physical page size.
 const DefaultPhysPageSize = _DefaultPhysPageSize
diff --git a/src/runtime/internal/sys/arch_386.go b/src/internal/goarch/goarch_386.go
similarity index 95%
rename from src/runtime/internal/sys/arch_386.go
rename to src/internal/goarch/goarch_386.go
index 1ebce3435e4be374308d59601ab52d4d572d5eb1..c6214217fcf339a5eb279c0bf80e15441acfd9b1 100644
--- a/src/runtime/internal/sys/arch_386.go
+++ b/src/internal/goarch/goarch_386.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = I386
diff --git a/src/runtime/internal/sys/arch_amd64.go b/src/internal/goarch/goarch_amd64.go
similarity index 95%
rename from src/runtime/internal/sys/arch_amd64.go
rename to src/internal/goarch/goarch_amd64.go
index 7f003d0f1d503431452dca3003f47c6c1d080621..911e3e72421720f95412579c50917d54e781bc7b 100644
--- a/src/runtime/internal/sys/arch_amd64.go
+++ b/src/internal/goarch/goarch_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = AMD64
diff --git a/src/runtime/internal/sys/arch_arm.go b/src/internal/goarch/goarch_arm.go
similarity index 95%
rename from src/runtime/internal/sys/arch_arm.go
rename to src/internal/goarch/goarch_arm.go
index ef2048bb71a5dd837c2c6e03ccb312ade0baf48f..a6591713c8204006a3d9cff45f56f345092b3b01 100644
--- a/src/runtime/internal/sys/arch_arm.go
+++ b/src/internal/goarch/goarch_arm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = ARM
diff --git a/src/runtime/internal/sys/arch_arm64.go b/src/internal/goarch/goarch_arm64.go
similarity index 95%
rename from src/runtime/internal/sys/arch_arm64.go
rename to src/internal/goarch/goarch_arm64.go
index b9f2f7b1fe226abd96e5907e34b04be368fa6ea3..85d0b4763913212bb2be2e81d0c6880bfa0b88d4 100644
--- a/src/runtime/internal/sys/arch_arm64.go
+++ b/src/internal/goarch/goarch_arm64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = ARM64
diff --git a/src/runtime/internal/sys/arch_mips.go b/src/internal/goarch/goarch_mips.go
similarity index 95%
rename from src/runtime/internal/sys/arch_mips.go
rename to src/internal/goarch/goarch_mips.go
index 4cb0eebea7bb5c0fbaafe59ff2b9bfe8a7448e2a..59f3995e2a54fda0d1df6bfdbc883840fbfef0d6 100644
--- a/src/runtime/internal/sys/arch_mips.go
+++ b/src/internal/goarch/goarch_mips.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS
diff --git a/src/runtime/internal/sys/arch_mips64.go b/src/internal/goarch/goarch_mips64.go
similarity index 95%
rename from src/runtime/internal/sys/arch_mips64.go
rename to src/internal/goarch/goarch_mips64.go
index 57636ac4a4e0ebe933066ca9a6fb1722e12436a5..9e4f82797d410ae88a5bd6a7c8e6260c170b8da5 100644
--- a/src/runtime/internal/sys/arch_mips64.go
+++ b/src/internal/goarch/goarch_mips64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS64
diff --git a/src/runtime/internal/sys/arch_mips64le.go b/src/internal/goarch/goarch_mips64le.go
similarity index 95%
rename from src/runtime/internal/sys/arch_mips64le.go
rename to src/internal/goarch/goarch_mips64le.go
index 57636ac4a4e0ebe933066ca9a6fb1722e12436a5..9e4f82797d410ae88a5bd6a7c8e6260c170b8da5 100644
--- a/src/runtime/internal/sys/arch_mips64le.go
+++ b/src/internal/goarch/goarch_mips64le.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS64
diff --git a/src/runtime/internal/sys/arch_mipsle.go b/src/internal/goarch/goarch_mipsle.go
similarity index 95%
rename from src/runtime/internal/sys/arch_mipsle.go
rename to src/internal/goarch/goarch_mipsle.go
index 4240f5ce47bb7f8abfaffc75f2f3c5ffed838aa1..3e6642bb86399ba7b01378d53111460a4a30ef21 100644
--- a/src/runtime/internal/sys/arch_mipsle.go
+++ b/src/internal/goarch/goarch_mipsle.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS
diff --git a/src/runtime/internal/sys/arch_ppc64.go b/src/internal/goarch/goarch_ppc64.go
similarity index 95%
rename from src/runtime/internal/sys/arch_ppc64.go
rename to src/internal/goarch/goarch_ppc64.go
index 1869213ce241ee5f6da403b2714652756dc956dc..60cc846e6a380aae4cf1574739661e8a06efb392 100644
--- a/src/runtime/internal/sys/arch_ppc64.go
+++ b/src/internal/goarch/goarch_ppc64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = PPC64
diff --git a/src/runtime/internal/sys/arch_ppc64le.go b/src/internal/goarch/goarch_ppc64le.go
similarity index 95%
rename from src/runtime/internal/sys/arch_ppc64le.go
rename to src/internal/goarch/goarch_ppc64le.go
index 1869213ce241ee5f6da403b2714652756dc956dc..60cc846e6a380aae4cf1574739661e8a06efb392 100644
--- a/src/runtime/internal/sys/arch_ppc64le.go
+++ b/src/internal/goarch/goarch_ppc64le.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = PPC64
diff --git a/src/runtime/internal/sys/arch_riscv64.go b/src/internal/goarch/goarch_riscv64.go
similarity index 95%
rename from src/runtime/internal/sys/arch_riscv64.go
rename to src/internal/goarch/goarch_riscv64.go
index 360d236e32072ac431f19ed75095b406cb6b4beb..3b6da1e02fe9b8c04dc10d7a16e4f0afd472b859 100644
--- a/src/runtime/internal/sys/arch_riscv64.go
+++ b/src/internal/goarch/goarch_riscv64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = RISCV64
diff --git a/src/runtime/internal/sys/arch_s390x.go b/src/internal/goarch/goarch_s390x.go
similarity index 95%
rename from src/runtime/internal/sys/arch_s390x.go
rename to src/internal/goarch/goarch_s390x.go
index e33e0b7f2b890b416ac5e70c2cbdcff6a5ad2eb5..20c5705581e79ce5c897c3b6c6e442a3c92c8a02 100644
--- a/src/runtime/internal/sys/arch_s390x.go
+++ b/src/internal/goarch/goarch_s390x.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = S390X
diff --git a/src/runtime/internal/sys/arch_wasm.go b/src/internal/goarch/goarch_wasm.go
similarity index 95%
rename from src/runtime/internal/sys/arch_wasm.go
rename to src/internal/goarch/goarch_wasm.go
index ee919ff9e634996eeb54bd40e7a9c73e0509a5ec..98618d6980edd7e0ae4329c7f0575e62d64023e8 100644
--- a/src/runtime/internal/sys/arch_wasm.go
+++ b/src/internal/goarch/goarch_wasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = WASM
diff --git a/src/internal/goarch/zgoarch_386.go b/src/internal/goarch/zgoarch_386.go
new file mode 100644
index 0000000000000000000000000000000000000000..2395b8095149f49444fbeae7eb1551dcbc3ee7c8
--- /dev/null
+++ b/src/internal/goarch/zgoarch_386.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build 386
+// +build 386
+
+package goarch
+
+const GOARCH = `386`
+
+const Is386 = 1
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_amd64.go b/src/internal/goarch/zgoarch_amd64.go
new file mode 100644
index 0000000000000000000000000000000000000000..c301d279c17fa64a978f1fc5071d56cb50b9377f
--- /dev/null
+++ b/src/internal/goarch/zgoarch_amd64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build amd64
+// +build amd64
+
+package goarch
+
+const GOARCH = `amd64`
+
+const Is386 = 0
+const IsAmd64 = 1
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_arm.go b/src/internal/goarch/zgoarch_arm.go
new file mode 100644
index 0000000000000000000000000000000000000000..4a5ff379995d096952bf99d752f97257d30c2498
--- /dev/null
+++ b/src/internal/goarch/zgoarch_arm.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build arm
+// +build arm
+
+package goarch
+
+const GOARCH = `arm`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 1
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_arm64.go b/src/internal/goarch/zgoarch_arm64.go
new file mode 100644
index 0000000000000000000000000000000000000000..840e280f94bd93c717773725a64a772a9a497924
--- /dev/null
+++ b/src/internal/goarch/zgoarch_arm64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build arm64
+// +build arm64
+
+package goarch
+
+const GOARCH = `arm64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 1
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_arm64be.go b/src/internal/goarch/zgoarch_arm64be.go
new file mode 100644
index 0000000000000000000000000000000000000000..bdbe5faacf1535e6fe0c683fe39563fbfa881626
--- /dev/null
+++ b/src/internal/goarch/zgoarch_arm64be.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build arm64be
+// +build arm64be
+
+package goarch
+
+const GOARCH = `arm64be`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 1
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_armbe.go b/src/internal/goarch/zgoarch_armbe.go
new file mode 100644
index 0000000000000000000000000000000000000000..36be514a0b486df9f3a56bd26afc38bf5d097f4e
--- /dev/null
+++ b/src/internal/goarch/zgoarch_armbe.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build armbe
+// +build armbe
+
+package goarch
+
+const GOARCH = `armbe`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 1
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_loong64.go b/src/internal/goarch/zgoarch_loong64.go
new file mode 100644
index 0000000000000000000000000000000000000000..9465cf5bf5de126e9fff0cc4a3a1e8b1c63cd499
--- /dev/null
+++ b/src/internal/goarch/zgoarch_loong64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build loong64
+// +build loong64
+
+package goarch
+
+const GOARCH = `loong64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 1
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips.go b/src/internal/goarch/zgoarch_mips.go
new file mode 100644
index 0000000000000000000000000000000000000000..e1458c0485e3218aefd7d17a32f6e4a352c3e3a9
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips
+// +build mips
+
+package goarch
+
+const GOARCH = `mips`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 1
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64.go b/src/internal/goarch/zgoarch_mips64.go
new file mode 100644
index 0000000000000000000000000000000000000000..7de345e32198aee8e1e507c8ec1dd95a6108c042
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64
+// +build mips64
+
+package goarch
+
+const GOARCH = `mips64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 1
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64le.go b/src/internal/goarch/zgoarch_mips64le.go
new file mode 100644
index 0000000000000000000000000000000000000000..96b1c3c021c4737d586b507ae2facb8bc72df183
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64le.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64le
+// +build mips64le
+
+package goarch
+
+const GOARCH = `mips64le`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 1
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64p32.go b/src/internal/goarch/zgoarch_mips64p32.go
new file mode 100644
index 0000000000000000000000000000000000000000..91d1f3c4df88a0103eec56b4c276738d98ea6434
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64p32.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64p32
+// +build mips64p32
+
+package goarch
+
+const GOARCH = `mips64p32`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 1
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64p32le.go b/src/internal/goarch/zgoarch_mips64p32le.go
new file mode 100644
index 0000000000000000000000000000000000000000..18f2ef2347be5cc9cb1e6c55daabed4e93fd2da3
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64p32le.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64p32le
+// +build mips64p32le
+
+package goarch
+
+const GOARCH = `mips64p32le`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 1
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mipsle.go b/src/internal/goarch/zgoarch_mipsle.go
new file mode 100644
index 0000000000000000000000000000000000000000..4551de1a3259e1ebce7d809650bff4d4ccad86d8
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mipsle.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mipsle
+// +build mipsle
+
+package goarch
+
+const GOARCH = `mipsle`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 1
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_ppc.go b/src/internal/goarch/zgoarch_ppc.go
new file mode 100644
index 0000000000000000000000000000000000000000..ffed58c2e514a4d5226e41c314a0dbec1509eed0
--- /dev/null
+++ b/src/internal/goarch/zgoarch_ppc.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build ppc
+// +build ppc
+
+package goarch
+
+const GOARCH = `ppc`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 1
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_ppc64.go b/src/internal/goarch/zgoarch_ppc64.go
new file mode 100644
index 0000000000000000000000000000000000000000..c369c741664faceef14ea207016b3151bb45188d
--- /dev/null
+++ b/src/internal/goarch/zgoarch_ppc64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build ppc64
+// +build ppc64
+
+package goarch
+
+const GOARCH = `ppc64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 1
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_ppc64le.go b/src/internal/goarch/zgoarch_ppc64le.go
new file mode 100644
index 0000000000000000000000000000000000000000..de5bae2a810cea079eab7fd27228d41c79987a76
--- /dev/null
+++ b/src/internal/goarch/zgoarch_ppc64le.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build ppc64le
+// +build ppc64le
+
+package goarch
+
+const GOARCH = `ppc64le`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 1
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_riscv.go b/src/internal/goarch/zgoarch_riscv.go
new file mode 100644
index 0000000000000000000000000000000000000000..07c9d81b397baa4e7072c84a0b2ba752a2eca9d8
--- /dev/null
+++ b/src/internal/goarch/zgoarch_riscv.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build riscv
+// +build riscv
+
+package goarch
+
+const GOARCH = `riscv`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 1
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_riscv64.go b/src/internal/goarch/zgoarch_riscv64.go
new file mode 100644
index 0000000000000000000000000000000000000000..24e6ef3fdf439161ff0ab628a5bcf90e0a2eecae
--- /dev/null
+++ b/src/internal/goarch/zgoarch_riscv64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build riscv64
+// +build riscv64
+
+package goarch
+
+const GOARCH = `riscv64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 1
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_s390.go b/src/internal/goarch/zgoarch_s390.go
new file mode 100644
index 0000000000000000000000000000000000000000..429206d653a6202eeb9c59a154efc5e21def8daa
--- /dev/null
+++ b/src/internal/goarch/zgoarch_s390.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build s390
+// +build s390
+
+package goarch
+
+const GOARCH = `s390`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 1
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_s390x.go b/src/internal/goarch/zgoarch_s390x.go
new file mode 100644
index 0000000000000000000000000000000000000000..0c5900521640de380c97a9e3511f87da1b42aed2
--- /dev/null
+++ b/src/internal/goarch/zgoarch_s390x.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build s390x
+// +build s390x
+
+package goarch
+
+const GOARCH = `s390x`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 1
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_sparc.go b/src/internal/goarch/zgoarch_sparc.go
new file mode 100644
index 0000000000000000000000000000000000000000..83a356e4c7a03bd6074cd8b7a28ffb4100143a63
--- /dev/null
+++ b/src/internal/goarch/zgoarch_sparc.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build sparc
+// +build sparc
+
+package goarch
+
+const GOARCH = `sparc`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 1
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_sparc64.go b/src/internal/goarch/zgoarch_sparc64.go
new file mode 100644
index 0000000000000000000000000000000000000000..7c9d40986ecb13a522a4ca2cc1b74f2fa89db585
--- /dev/null
+++ b/src/internal/goarch/zgoarch_sparc64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build sparc64
+// +build sparc64
+
+package goarch
+
+const GOARCH = `sparc64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 1
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_wasm.go b/src/internal/goarch/zgoarch_wasm.go
new file mode 100644
index 0000000000000000000000000000000000000000..5aac1dfc47975aacbeb3f9164b3213a89aeb6aad
--- /dev/null
+++ b/src/internal/goarch/zgoarch_wasm.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build wasm
+// +build wasm
+
+package goarch
+
+const GOARCH = `wasm`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 1
diff --git a/src/internal/goexperiment/exp_regabi_off.go b/src/internal/goexperiment/exp_regabi_off.go
deleted file mode 100644
index 5d8823843d94844085e7aae6a5c2ba548637bee0..0000000000000000000000000000000000000000
--- a/src/internal/goexperiment/exp_regabi_off.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build !goexperiment.regabi
-// +build !goexperiment.regabi
-
-package goexperiment
-
-const Regabi = false
-const RegabiInt = 0
diff --git a/src/internal/goexperiment/exp_regabi_on.go b/src/internal/goexperiment/exp_regabi_on.go
deleted file mode 100644
index c08d58e9b2aa25099caa3021573818ab0bcd9cb4..0000000000000000000000000000000000000000
--- a/src/internal/goexperiment/exp_regabi_on.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build goexperiment.regabi
-// +build goexperiment.regabi
-
-package goexperiment
-
-const Regabi = true
-const RegabiInt = 1
diff --git a/src/internal/goexperiment/exp_regabidefer_off.go b/src/internal/goexperiment/exp_regabidefer_off.go
deleted file mode 100644
index b47c0c2cf55129fa74af650b7586f2c355a9db6a..0000000000000000000000000000000000000000
--- a/src/internal/goexperiment/exp_regabidefer_off.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build !goexperiment.regabidefer
-// +build !goexperiment.regabidefer
-
-package goexperiment
-
-const RegabiDefer = false
-const RegabiDeferInt = 0
diff --git a/src/internal/goexperiment/exp_regabidefer_on.go b/src/internal/goexperiment/exp_regabidefer_on.go
deleted file mode 100644
index bbf2f6c69be4d6be7341a96ad5d69031b2236c3f..0000000000000000000000000000000000000000
--- a/src/internal/goexperiment/exp_regabidefer_on.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build goexperiment.regabidefer
-// +build goexperiment.regabidefer
-
-package goexperiment
-
-const RegabiDefer = true
-const RegabiDeferInt = 1
diff --git a/src/internal/goexperiment/exp_regabig_off.go b/src/internal/goexperiment/exp_regabig_off.go
deleted file mode 100644
index 1b37d4518680210b2bea6cea756cd76f185787c9..0000000000000000000000000000000000000000
--- a/src/internal/goexperiment/exp_regabig_off.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build !goexperiment.regabig
-// +build !goexperiment.regabig
-
-package goexperiment
-
-const RegabiG = false
-const RegabiGInt = 0
diff --git a/src/internal/goexperiment/exp_regabig_on.go b/src/internal/goexperiment/exp_regabig_on.go
deleted file mode 100644
index 7e5b162e0b2ae2aa8e0f3ddd230bcea3db67ddc9..0000000000000000000000000000000000000000
--- a/src/internal/goexperiment/exp_regabig_on.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build goexperiment.regabig
-// +build goexperiment.regabig
-
-package goexperiment
-
-const RegabiG = true
-const RegabiGInt = 1
diff --git a/src/internal/goexperiment/exp_unified_off.go b/src/internal/goexperiment/exp_unified_off.go
new file mode 100644
index 0000000000000000000000000000000000000000..4c16fd85624c60f7fac164071839f98c158b6af1
--- /dev/null
+++ b/src/internal/goexperiment/exp_unified_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.unified
+// +build !goexperiment.unified
+
+package goexperiment
+
+const Unified = false
+const UnifiedInt = 0
diff --git a/src/internal/goexperiment/exp_unified_on.go b/src/internal/goexperiment/exp_unified_on.go
new file mode 100644
index 0000000000000000000000000000000000000000..2b17ba3e79b4bbd3422bcb18653bfae83c7b3602
--- /dev/null
+++ b/src/internal/goexperiment/exp_unified_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.unified
+// +build goexperiment.unified
+
+package goexperiment
+
+const Unified = true
+const UnifiedInt = 1
diff --git a/src/internal/goexperiment/flags.go b/src/internal/goexperiment/flags.go
index cd4c178818495f165b20ec2caebdecf8cbe6cc13..0a61a0e5fc12adc1556cc38138bf14e2583b3cf9 100644
--- a/src/internal/goexperiment/flags.go
+++ b/src/internal/goexperiment/flags.go
@@ -59,6 +59,10 @@ type Flags struct {
 	PreemptibleLoops  bool
 	StaticLockRanking bool
 
+	// Unified enables the compiler's unified IR construction
+	// experiment.
+	Unified bool
+
 	// Regabi is split into several sub-experiments that can be
 	// enabled individually. Not all combinations work.
 	// The "regabi" GOEXPERIMENT is an alias for all "working"
@@ -68,26 +72,15 @@ type Flags struct {
 	// ABI0 and ABIInternal functions. Without this, the ABIs are
 	// assumed to be identical so cross-ABI calls are direct.
 	RegabiWrappers bool
-	// RegabiG enables dedicated G and zero registers in
-	// ABIInternal.
-	//
-	// Requires wrappers because it makes the ABIs incompatible.
-	RegabiG bool
 	// RegabiReflect enables the register-passing paths in
 	// reflection calls. This is also gated by intArgRegs in
 	// reflect and runtime (which are disabled by default) so it
 	// can be used in targeted tests.
 	RegabiReflect bool
-	// RegabiDefer enables desugaring defer and go calls
-	// into argument-less closures.
-	RegabiDefer bool
 	// RegabiArgs enables register arguments/results in all
 	// compiled Go functions.
 	//
-	// Requires wrappers (to do ABI translation), g (because
-	// runtime assembly that's been ported to ABIInternal uses the
-	// G register), reflect (so reflection calls use registers),
-	// and defer (because the runtime doesn't support passing
-	// register arguments to defer/go).
+	// Requires wrappers (to do ABI translation), and reflect (so
+	// reflection calls use registers).
 	RegabiArgs bool
 }
diff --git a/src/runtime/internal/sys/gengoos.go b/src/internal/goos/gengoos.go
similarity index 56%
rename from src/runtime/internal/sys/gengoos.go
rename to src/internal/goos/gengoos.go
index ffe962f71df61c89cba3261d7e017c5de4e432b2..1860cd700dfb278dd88c87dafd0385d1e2e922e7 100644
--- a/src/runtime/internal/sys/gengoos.go
+++ b/src/internal/goos/gengoos.go
@@ -16,17 +16,14 @@ import (
 	"strings"
 )
 
-var gooses, goarches []string
+var gooses []string
 
 func main() {
-	data, err := os.ReadFile("../../../go/build/syslist.go")
+	data, err := os.ReadFile("../../go/build/syslist.go")
 	if err != nil {
 		log.Fatal(err)
 	}
-	const (
-		goosPrefix   = `const goosList = `
-		goarchPrefix = `const goarchList = `
-	)
+	const goosPrefix = `const goosList = `
 	for _, line := range strings.Split(string(data), "\n") {
 		if strings.HasPrefix(line, goosPrefix) {
 			text, err := strconv.Unquote(strings.TrimPrefix(line, goosPrefix))
@@ -35,13 +32,6 @@ func main() {
 			}
 			gooses = strings.Fields(text)
 		}
-		if strings.HasPrefix(line, goarchPrefix) {
-			text, err := strconv.Unquote(strings.TrimPrefix(line, goarchPrefix))
-			if err != nil {
-				log.Fatalf("parsing goarchList: %v", err)
-			}
-			goarches = strings.Fields(text)
-		}
 	}
 
 	for _, target := range gooses {
@@ -63,41 +53,18 @@ func main() {
 		fmt.Fprintf(&buf, "// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.\n\n")
 		fmt.Fprintf(&buf, "//go:build %s\n", strings.Join(tags, " && "))
 		fmt.Fprintf(&buf, "// +build %s\n\n", strings.Join(tags, ","))
-		fmt.Fprintf(&buf, "package sys\n\n")
+		fmt.Fprintf(&buf, "package goos\n\n")
 		fmt.Fprintf(&buf, "const GOOS = `%s`\n\n", target)
 		for _, goos := range gooses {
 			value := 0
 			if goos == target {
 				value = 1
 			}
-			fmt.Fprintf(&buf, "const Goos%s = %d\n", strings.Title(goos), value)
+			fmt.Fprintf(&buf, "const Is%s = %d\n", strings.Title(goos), value)
 		}
 		err := os.WriteFile("zgoos_"+target+".go", buf.Bytes(), 0666)
 		if err != nil {
 			log.Fatal(err)
 		}
 	}
-
-	for _, target := range goarches {
-		if target == "amd64p32" {
-			continue
-		}
-		var buf bytes.Buffer
-		fmt.Fprintf(&buf, "// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.\n\n")
-		fmt.Fprintf(&buf, "//go:build %s\n", target)
-		fmt.Fprintf(&buf, "// +build %s\n\n", target) // must explicitly include target for bootstrapping purposes
-		fmt.Fprintf(&buf, "package sys\n\n")
-		fmt.Fprintf(&buf, "const GOARCH = `%s`\n\n", target)
-		for _, goarch := range goarches {
-			value := 0
-			if goarch == target {
-				value = 1
-			}
-			fmt.Fprintf(&buf, "const Goarch%s = %d\n", strings.Title(goarch), value)
-		}
-		err := os.WriteFile("zgoarch_"+target+".go", buf.Bytes(), 0666)
-		if err != nil {
-			log.Fatal(err)
-		}
-	}
 }
diff --git a/src/internal/goos/goos.go b/src/internal/goos/goos.go
new file mode 100644
index 0000000000000000000000000000000000000000..ebb521fec6876c6c7d01af5bcde8dae37d7fe195
--- /dev/null
+++ b/src/internal/goos/goos.go
@@ -0,0 +1,12 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// package goos contains GOOS-specific constants.
+package goos
+
+// The next line makes 'go generate' write the zgoos*.go files with
+// per-OS information, including constants named Is$GOOS for every
+// known GOOS. The constant is 1 on the current system, 0 otherwise;
+// multiplying by them is useful for defining GOOS-specific constants.
+//go:generate go run gengoos.go
diff --git a/src/internal/goos/zgoos_aix.go b/src/internal/goos/zgoos_aix.go
new file mode 100644
index 0000000000000000000000000000000000000000..063e698b82c6db2229c5180fceeb3572be285f32
--- /dev/null
+++ b/src/internal/goos/zgoos_aix.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build aix
+// +build aix
+
+package goos
+
+const GOOS = `aix`
+
+const IsAix = 1
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_android.go b/src/internal/goos/zgoos_android.go
new file mode 100644
index 0000000000000000000000000000000000000000..e9e4864978226755dba341e4c9df890b939ac885
--- /dev/null
+++ b/src/internal/goos/zgoos_android.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build android
+// +build android
+
+package goos
+
+const GOOS = `android`
+
+const IsAix = 0
+const IsAndroid = 1
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_darwin.go b/src/internal/goos/zgoos_darwin.go
new file mode 100644
index 0000000000000000000000000000000000000000..309d6a271729c18c7f7a117c545a2686279df6bc
--- /dev/null
+++ b/src/internal/goos/zgoos_darwin.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build !ios && darwin
+// +build !ios,darwin
+
+package goos
+
+const GOOS = `darwin`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 1
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_dragonfly.go b/src/internal/goos/zgoos_dragonfly.go
new file mode 100644
index 0000000000000000000000000000000000000000..4e8711b94c573dd87c54235d27d109cff164de27
--- /dev/null
+++ b/src/internal/goos/zgoos_dragonfly.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build dragonfly
+// +build dragonfly
+
+package goos
+
+const GOOS = `dragonfly`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 1
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_freebsd.go b/src/internal/goos/zgoos_freebsd.go
new file mode 100644
index 0000000000000000000000000000000000000000..f312bd16081acbf7abc2053e42206e1f155deb37
--- /dev/null
+++ b/src/internal/goos/zgoos_freebsd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build freebsd
+// +build freebsd
+
+package goos
+
+const GOOS = `freebsd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 1
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_hurd.go b/src/internal/goos/zgoos_hurd.go
new file mode 100644
index 0000000000000000000000000000000000000000..0f0dd28b81b80b24863741d9c5dcaf86c7c1e39c
--- /dev/null
+++ b/src/internal/goos/zgoos_hurd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build hurd
+// +build hurd
+
+package goos
+
+const GOOS = `hurd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 1
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_illumos.go b/src/internal/goos/zgoos_illumos.go
new file mode 100644
index 0000000000000000000000000000000000000000..17e7c53a40334b29d7877a6f07b5e91c3a90831c
--- /dev/null
+++ b/src/internal/goos/zgoos_illumos.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build illumos
+// +build illumos
+
+package goos
+
+const GOOS = `illumos`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 1
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_ios.go b/src/internal/goos/zgoos_ios.go
new file mode 100644
index 0000000000000000000000000000000000000000..e4745ca41341753d8831079dbcd76795c40d9e73
--- /dev/null
+++ b/src/internal/goos/zgoos_ios.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build ios
+// +build ios
+
+package goos
+
+const GOOS = `ios`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 1
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_js.go b/src/internal/goos/zgoos_js.go
new file mode 100644
index 0000000000000000000000000000000000000000..bd2417e9cea97f8d0a1c4f1f91b48d22955e2c39
--- /dev/null
+++ b/src/internal/goos/zgoos_js.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build js
+// +build js
+
+package goos
+
+const GOOS = `js`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 1
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_linux.go b/src/internal/goos/zgoos_linux.go
new file mode 100644
index 0000000000000000000000000000000000000000..476702f442adfdac096874983650c58a8ee7532e
--- /dev/null
+++ b/src/internal/goos/zgoos_linux.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build !android && linux
+// +build !android,linux
+
+package goos
+
+const GOOS = `linux`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 1
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_netbsd.go b/src/internal/goos/zgoos_netbsd.go
new file mode 100644
index 0000000000000000000000000000000000000000..97b7564babd29d66ab84aa15c80e40357a518c15
--- /dev/null
+++ b/src/internal/goos/zgoos_netbsd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build netbsd
+// +build netbsd
+
+package goos
+
+const GOOS = `netbsd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 1
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_openbsd.go b/src/internal/goos/zgoos_openbsd.go
new file mode 100644
index 0000000000000000000000000000000000000000..384a96480d69a8e10cb2def17ccfde1e2d18ed83
--- /dev/null
+++ b/src/internal/goos/zgoos_openbsd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build openbsd
+// +build openbsd
+
+package goos
+
+const GOOS = `openbsd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 1
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_plan9.go b/src/internal/goos/zgoos_plan9.go
new file mode 100644
index 0000000000000000000000000000000000000000..fcc279a79ec52978150787f978baf38a8273a411
--- /dev/null
+++ b/src/internal/goos/zgoos_plan9.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build plan9
+// +build plan9
+
+package goos
+
+const GOOS = `plan9`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 1
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_solaris.go b/src/internal/goos/zgoos_solaris.go
new file mode 100644
index 0000000000000000000000000000000000000000..3f366cf71018683fbfa8b3924d4558c24dbffeac
--- /dev/null
+++ b/src/internal/goos/zgoos_solaris.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build !illumos && solaris
+// +build !illumos,solaris
+
+package goos
+
+const GOOS = `solaris`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 1
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_windows.go b/src/internal/goos/zgoos_windows.go
new file mode 100644
index 0000000000000000000000000000000000000000..dfa55339d34cfe5db7ce68d8e83affa5055af7d2
--- /dev/null
+++ b/src/internal/goos/zgoos_windows.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build windows
+// +build windows
+
+package goos
+
+const GOOS = `windows`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 1
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_zos.go b/src/internal/goos/zgoos_zos.go
new file mode 100644
index 0000000000000000000000000000000000000000..714f24963a253f830d6f7b2df35ada18eafc92ad
--- /dev/null
+++ b/src/internal/goos/zgoos_zos.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build zos
+// +build zos
+
+package goos
+
+const GOOS = `zos`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 1
diff --git a/src/internal/goversion/goversion.go b/src/internal/goversion/goversion.go
index 4cc15688c0b70505e47ddd4ffce5c20a85852442..8fcea100dc696ab6044e871730be6f4a4054237a 100644
--- a/src/internal/goversion/goversion.go
+++ b/src/internal/goversion/goversion.go
@@ -9,4 +9,4 @@ package goversion
 //
 // It should be updated at the start of each development cycle to be
 // the version of the next Go 1.x release. See golang.org/issue/40705.
-const Version = 17
+const Version = 18
diff --git a/src/internal/poll/fd_unix.go b/src/internal/poll/fd_unix.go
index 3b17cd22b03b8f85d0f9b6eb250d3379d59b9cfa..60b59df2e36a3f73f39665fc264a0d52329b772e 100644
--- a/src/internal/poll/fd_unix.go
+++ b/src/internal/poll/fd_unix.go
@@ -230,6 +230,60 @@ func (fd *FD) ReadFrom(p []byte) (int, syscall.Sockaddr, error) {
 	}
 }
 
+// ReadFrom wraps the recvfrom network call for IPv4.
+func (fd *FD) ReadFromInet4(p []byte, from *syscall.SockaddrInet4) (int, error) {
+	if err := fd.readLock(); err != nil {
+		return 0, err
+	}
+	defer fd.readUnlock()
+	if err := fd.pd.prepareRead(fd.isFile); err != nil {
+		return 0, err
+	}
+	for {
+		n, err := syscall.RecvfromInet4(fd.Sysfd, p, 0, from)
+		if err != nil {
+			if err == syscall.EINTR {
+				continue
+			}
+			n = 0
+			if err == syscall.EAGAIN && fd.pd.pollable() {
+				if err = fd.pd.waitRead(fd.isFile); err == nil {
+					continue
+				}
+			}
+		}
+		err = fd.eofError(n, err)
+		return n, err
+	}
+}
+
+// ReadFrom wraps the recvfrom network call for IPv6.
+func (fd *FD) ReadFromInet6(p []byte, from *syscall.SockaddrInet6) (int, error) {
+	if err := fd.readLock(); err != nil {
+		return 0, err
+	}
+	defer fd.readUnlock()
+	if err := fd.pd.prepareRead(fd.isFile); err != nil {
+		return 0, err
+	}
+	for {
+		n, err := syscall.RecvfromInet6(fd.Sysfd, p, 0, from)
+		if err != nil {
+			if err == syscall.EINTR {
+				continue
+			}
+			n = 0
+			if err == syscall.EAGAIN && fd.pd.pollable() {
+				if err = fd.pd.waitRead(fd.isFile); err == nil {
+					continue
+				}
+			}
+		}
+		err = fd.eofError(n, err)
+		return n, err
+	}
+}
+
 // ReadMsg wraps the recvmsg network call.
 func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.Sockaddr, error) {
 	if err := fd.readLock(); err != nil {
@@ -327,6 +381,58 @@ func (fd *FD) Pwrite(p []byte, off int64) (int, error) {
 	}
 }
 
+// WriteToInet4 wraps the sendto network call for IPv4 addresses.
+func (fd *FD) WriteToInet4(p []byte, sa syscall.SockaddrInet4) (int, error) {
+	if err := fd.writeLock(); err != nil {
+		return 0, err
+	}
+	defer fd.writeUnlock()
+	if err := fd.pd.prepareWrite(fd.isFile); err != nil {
+		return 0, err
+	}
+	for {
+		err := syscall.SendtoInet4(fd.Sysfd, p, 0, sa)
+		if err == syscall.EINTR {
+			continue
+		}
+		if err == syscall.EAGAIN && fd.pd.pollable() {
+			if err = fd.pd.waitWrite(fd.isFile); err == nil {
+				continue
+			}
+		}
+		if err != nil {
+			return 0, err
+		}
+		return len(p), nil
+	}
+}
+
+// WriteToInet6 wraps the sendto network call for IPv6 addresses.
+func (fd *FD) WriteToInet6(p []byte, sa syscall.SockaddrInet6) (int, error) {
+	if err := fd.writeLock(); err != nil {
+		return 0, err
+	}
+	defer fd.writeUnlock()
+	if err := fd.pd.prepareWrite(fd.isFile); err != nil {
+		return 0, err
+	}
+	for {
+		err := syscall.SendtoInet6(fd.Sysfd, p, 0, sa)
+		if err == syscall.EINTR {
+			continue
+		}
+		if err == syscall.EAGAIN && fd.pd.pollable() {
+			if err = fd.pd.waitWrite(fd.isFile); err == nil {
+				continue
+			}
+		}
+		if err != nil {
+			return 0, err
+		}
+		return len(p), nil
+	}
+}
+
 // WriteTo wraps the sendto network call.
 func (fd *FD) WriteTo(p []byte, sa syscall.Sockaddr) (int, error) {
 	if err := fd.writeLock(); err != nil {
diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go
index 4a5169527c42b0592d13e6c75df3fc9773647347..48fcdf306cfe7591adbf0b5a78fc328c678ed76d 100644
--- a/src/internal/poll/fd_windows.go
+++ b/src/internal/poll/fd_windows.go
@@ -79,6 +79,8 @@ type operation struct {
 	buf    syscall.WSABuf
 	msg    windows.WSAMsg
 	sa     syscall.Sockaddr
+	sa4    syscall.SockaddrInet4
+	sa6    syscall.SockaddrInet6
 	rsa    *syscall.RawSockaddrAny
 	rsan   int32
 	handle syscall.Handle
@@ -593,6 +595,70 @@ func (fd *FD) ReadFrom(buf []byte) (int, syscall.Sockaddr, error) {
 	return n, sa, nil
 }
 
+// ReadFrom wraps the recvfrom network call for IPv4.
+func (fd *FD) ReadFromInet4(buf []byte, sa4 *syscall.SockaddrInet4) (int, error) {
+	if len(buf) == 0 {
+		return 0, nil
+	}
+	if len(buf) > maxRW {
+		buf = buf[:maxRW]
+	}
+	if err := fd.readLock(); err != nil {
+		return 0, err
+	}
+	defer fd.readUnlock()
+	o := &fd.rop
+	o.InitBuf(buf)
+	n, err := execIO(o, func(o *operation) error {
+		if o.rsa == nil {
+			o.rsa = new(syscall.RawSockaddrAny)
+		}
+		o.rsan = int32(unsafe.Sizeof(*o.rsa))
+		return syscall.WSARecvFrom(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, o.rsa, &o.rsan, &o.o, nil)
+	})
+	err = fd.eofError(n, err)
+	if err != nil {
+		return n, err
+	}
+	sa, _ := o.rsa.Sockaddr()
+	if sa != nil {
+		*sa4 = *(sa.(*syscall.SockaddrInet4))
+	}
+	return n, err
+}
+
+// ReadFrom wraps the recvfrom network call for IPv6.
+func (fd *FD) ReadFromInet6(buf []byte, sa6 *syscall.SockaddrInet6) (int, error) {
+	if len(buf) == 0 {
+		return 0, nil
+	}
+	if len(buf) > maxRW {
+		buf = buf[:maxRW]
+	}
+	if err := fd.readLock(); err != nil {
+		return 0, err
+	}
+	defer fd.readUnlock()
+	o := &fd.rop
+	o.InitBuf(buf)
+	n, err := execIO(o, func(o *operation) error {
+		if o.rsa == nil {
+			o.rsa = new(syscall.RawSockaddrAny)
+		}
+		o.rsan = int32(unsafe.Sizeof(*o.rsa))
+		return syscall.WSARecvFrom(o.fd.Sysfd, &o.buf, 1, &o.qty, &o.flags, o.rsa, &o.rsan, &o.o, nil)
+	})
+	err = fd.eofError(n, err)
+	if err != nil {
+		return n, err
+	}
+	sa, _ := o.rsa.Sockaddr()
+	if sa != nil {
+		*sa6 = *(sa.(*syscall.SockaddrInet6))
+	}
+	return n, err
+}
+
 // Write implements io.Writer.
 func (fd *FD) Write(buf []byte) (int, error) {
 	if err := fd.writeLock(); err != nil {
@@ -791,6 +857,50 @@ func (fd *FD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
 	return ntotal, nil
 }
 
+// WriteTo wraps the sendto network call for IPv4.
+func (fd *FD) WriteToInet4(buf []byte, sa4 syscall.SockaddrInet4) (int, error) {
+	if err := fd.writeLock(); err != nil {
+		return 0, err
+	}
+	defer fd.writeUnlock()
+
+	if len(buf) == 0 {
+		// handle zero-byte payload
+		o := &fd.wop
+		o.InitBuf(buf)
+		o.sa4 = sa4
+		n, err := execIO(o, func(o *operation) error {
+			return syscall.WSASendtoInet4(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa4, &o.o, nil)
+		})
+		return n, err
+	}
+
+	ntotal := 0
+	for len(buf) > 0 {
+		b := buf
+		if len(b) > maxRW {
+			b = b[:maxRW]
+		}
+		o := &fd.wop
+		o.InitBuf(b)
+		o.sa4 = sa4
+		n, err := execIO(o, func(o *operation) error {
+			return syscall.WSASendtoInet4(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa4, &o.o, nil)
+		})
+		ntotal += int(n)
+		if err != nil {
+			return ntotal, err
+		}
+		buf = buf[n:]
+	}
+	return ntotal, nil
+}
+
+// WriteTo wraps the sendto network call for IPv6.
+func (fd *FD) WriteToInet6(buf []byte, sa syscall.SockaddrInet6) (int, error) {
+	return fd.WriteTo(buf, &sa)
+}
+
 // Call ConnectEx. This doesn't need any locking, since it is only
 // called when the descriptor is first created. This is here rather
 // than in the net package so that it can use fd.wop.
diff --git a/src/internal/reflectlite/swapper.go b/src/internal/reflectlite/swapper.go
index 6330ab2d34668dd8f85719120befb61cd75c1984..ac081d49bbbe9caada596c3c6bfa536b2c769a72 100644
--- a/src/internal/reflectlite/swapper.go
+++ b/src/internal/reflectlite/swapper.go
@@ -5,6 +5,7 @@
 package reflectlite
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"unsafe"
 )
@@ -36,7 +37,7 @@ func Swapper(slice interface{}) func(i, j int) {
 
 	// Some common & small cases, without using memmove:
 	if hasPtr {
-		if size == ptrSize {
+		if size == goarch.PtrSize {
 			ps := *(*[]unsafe.Pointer)(v.ptr)
 			return func(i, j int) { ps[i], ps[j] = ps[j], ps[i] }
 		}
diff --git a/src/internal/reflectlite/value.go b/src/internal/reflectlite/value.go
index 0365eeeabf634f0ad2c1a88709b49bbc66ae70bb..136273842ceecb27c787bf479a3e85b78348ed53 100644
--- a/src/internal/reflectlite/value.go
+++ b/src/internal/reflectlite/value.go
@@ -5,13 +5,12 @@
 package reflectlite
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"runtime"
 	"unsafe"
 )
 
-const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
-
 // Value is the reflection interface to a Go value.
 //
 // Not all methods apply to all kinds of values. Restrictions,
@@ -90,7 +89,7 @@ func (f flag) ro() flag {
 // pointer returns the underlying pointer represented by v.
 // v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
 func (v Value) pointer() unsafe.Pointer {
-	if v.typ.size != ptrSize || !v.typ.pointers() {
+	if v.typ.size != goarch.PtrSize || !v.typ.pointers() {
 		panic("can't call pointer on a non-pointer Value")
 	}
 	if v.flag&flagIndir != 0 {
diff --git a/src/internal/syscall/unix/getentropy_darwin.go b/src/internal/syscall/unix/getentropy_darwin.go
index e1a410a454144627108c7e449430b671b2689930..c75006bf8b686742463b1d601d2ec51eff20cf46 100644
--- a/src/internal/syscall/unix/getentropy_darwin.go
+++ b/src/internal/syscall/unix/getentropy_darwin.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin && !ios
+// +build darwin,!ios
+
 package unix
 
 import (
diff --git a/src/internal/syscall/unix/ioctl_aix.go b/src/internal/syscall/unix/ioctl_aix.go
index 19d56c36a13156563115d5bbdf248a08ccbf1627..d361533b5c4a43bdf3789f7711077d74278560bd 100644
--- a/src/internal/syscall/unix/ioctl_aix.go
+++ b/src/internal/syscall/unix/ioctl_aix.go
@@ -16,7 +16,7 @@ var libc_ioctl uintptr
 // Implemented in syscall/syscall_aix.go.
 func syscall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
 
-func Ioctl(fd int, cmd int, args uintptr) (err error) {
+func Ioctl(fd int, cmd int, args unsafe.Pointer) (err error) {
 	_, _, e1 := syscall6(uintptr(unsafe.Pointer(&libc_ioctl)), 3, uintptr(fd), uintptr(cmd), uintptr(args), 0, 0, 0)
 	if e1 != 0 {
 		err = e1
diff --git a/src/internal/syscall/windows/exec_windows_test.go b/src/internal/syscall/windows/exec_windows_test.go
index 283d7cea94bfa0fdd622a301eacb56e2de232316..0db626636e95d1308cd6defb0937cb4a60b1da05 100644
--- a/src/internal/syscall/windows/exec_windows_test.go
+++ b/src/internal/syscall/windows/exec_windows_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package windows_test
diff --git a/src/internal/syscall/windows/mksyscall.go b/src/internal/syscall/windows/mksyscall.go
index 599f07601bd4d5af2dedd8530b306776c7af850e..39f745db7a3d40bb38e386ae30d1b201ae9f06e3 100644
--- a/src/internal/syscall/windows/mksyscall.go
+++ b/src/internal/syscall/windows/mksyscall.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build generate
 // +build generate
 
 package windows
diff --git a/src/internal/syscall/windows/registry/export_test.go b/src/internal/syscall/windows/registry/export_test.go
index 8badf6fdcf1f9a2612546c741e7119aea58abe24..d02d93f287522f62ae766b7f7a11fbcdb34bf2bd 100644
--- a/src/internal/syscall/windows/registry/export_test.go
+++ b/src/internal/syscall/windows/registry/export_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package registry
diff --git a/src/internal/syscall/windows/registry/key.go b/src/internal/syscall/windows/registry/key.go
index 612c48f084060fa7c98339e91c076df070123532..ebe73a2e02468336a514ce1f5d95a89b6ae456ba 100644
--- a/src/internal/syscall/windows/registry/key.go
+++ b/src/internal/syscall/windows/registry/key.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 // Package registry provides access to the Windows registry.
diff --git a/src/internal/syscall/windows/registry/mksyscall.go b/src/internal/syscall/windows/registry/mksyscall.go
index 320abf7fc69ecaad80a1487c3ac76f5da018458f..0a007df7ccd08322d0650c1e0612a41b6e3d7b38 100644
--- a/src/internal/syscall/windows/registry/mksyscall.go
+++ b/src/internal/syscall/windows/registry/mksyscall.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build generate
 // +build generate
 
 package registry
diff --git a/src/internal/syscall/windows/registry/registry_test.go b/src/internal/syscall/windows/registry/registry_test.go
index 57971629006a7a842ba748eeca38cf84c58078af..69b84e1c4c5f995f7804ac086f71c27708efb3ac 100644
--- a/src/internal/syscall/windows/registry/registry_test.go
+++ b/src/internal/syscall/windows/registry/registry_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package registry_test
diff --git a/src/internal/syscall/windows/registry/syscall.go b/src/internal/syscall/windows/registry/syscall.go
index a6525dac5d91aca8337b323f7098dbee230ec164..bb612793613f571a1250a417a2773c1f782fff73 100644
--- a/src/internal/syscall/windows/registry/syscall.go
+++ b/src/internal/syscall/windows/registry/syscall.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package registry
diff --git a/src/internal/syscall/windows/registry/value.go b/src/internal/syscall/windows/registry/value.go
index dc3930a6bc2edaa753b23a14f49ff2ecc1af6f13..e1fc99c40d4cdd8cd57bf15ef667939720a277b2 100644
--- a/src/internal/syscall/windows/registry/value.go
+++ b/src/internal/syscall/windows/registry/value.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package registry
diff --git a/src/internal/syscall/windows/sysdll/sysdll.go b/src/internal/syscall/windows/sysdll/sysdll.go
index c587c19c77d45a31af9d77e18a30e35e627e1a81..61b998e4cfc3d164b8f224d7264ee68686396efb 100644
--- a/src/internal/syscall/windows/sysdll/sysdll.go
+++ b/src/internal/syscall/windows/sysdll/sysdll.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 // Package sysdll is an internal leaf package that records and reports
diff --git a/src/io/fs/fs.go b/src/io/fs/fs.go
index e1be32478e02986b59ba7f57945df7cfdd784391..e603afadb0b1b166e646ed0be6a11c98333fb798 100644
--- a/src/io/fs/fs.go
+++ b/src/io/fs/fs.go
@@ -86,7 +86,7 @@ type File interface {
 type DirEntry interface {
 	// Name returns the name of the file (or subdirectory) described by the entry.
 	// This name is only the final element of the path (the base name), not the entire path.
-	// For example, Name would return "hello.go" not "/home/gopher/hello.go".
+	// For example, Name would return "hello.go" not "home/gopher/hello.go".
 	Name() string
 
 	// IsDir reports whether the entry describes a directory.
diff --git a/src/io/pipe.go b/src/io/pipe.go
index b5343bb6b73b50d4a75d86d7c1ece87abd38d4ed..2724e3f7abe4fddba4800b2ac7185ec66e031e0c 100644
--- a/src/io/pipe.go
+++ b/src/io/pipe.go
@@ -47,7 +47,7 @@ type pipe struct {
 	werr onceError
 }
 
-func (p *pipe) Read(b []byte) (n int, err error) {
+func (p *pipe) read(b []byte) (n int, err error) {
 	select {
 	case <-p.done:
 		return 0, p.readCloseError()
@@ -64,15 +64,7 @@ func (p *pipe) Read(b []byte) (n int, err error) {
 	}
 }
 
-func (p *pipe) readCloseError() error {
-	rerr := p.rerr.Load()
-	if werr := p.werr.Load(); rerr == nil && werr != nil {
-		return werr
-	}
-	return ErrClosedPipe
-}
-
-func (p *pipe) CloseRead(err error) error {
+func (p *pipe) closeRead(err error) error {
 	if err == nil {
 		err = ErrClosedPipe
 	}
@@ -81,7 +73,7 @@ func (p *pipe) CloseRead(err error) error {
 	return nil
 }
 
-func (p *pipe) Write(b []byte) (n int, err error) {
+func (p *pipe) write(b []byte) (n int, err error) {
 	select {
 	case <-p.done:
 		return 0, p.writeCloseError()
@@ -103,15 +95,7 @@ func (p *pipe) Write(b []byte) (n int, err error) {
 	return n, nil
 }
 
-func (p *pipe) writeCloseError() error {
-	werr := p.werr.Load()
-	if rerr := p.rerr.Load(); werr == nil && rerr != nil {
-		return rerr
-	}
-	return ErrClosedPipe
-}
-
-func (p *pipe) CloseWrite(err error) error {
+func (p *pipe) closeWrite(err error) error {
 	if err == nil {
 		err = EOF
 	}
@@ -120,6 +104,24 @@ func (p *pipe) CloseWrite(err error) error {
 	return nil
 }
 
+// readCloseError is considered internal to the pipe type.
+func (p *pipe) readCloseError() error {
+	rerr := p.rerr.Load()
+	if werr := p.werr.Load(); rerr == nil && werr != nil {
+		return werr
+	}
+	return ErrClosedPipe
+}
+
+// writeCloseError is considered internal to the pipe type.
+func (p *pipe) writeCloseError() error {
+	werr := p.werr.Load()
+	if rerr := p.rerr.Load(); werr == nil && rerr != nil {
+		return rerr
+	}
+	return ErrClosedPipe
+}
+
 // A PipeReader is the read half of a pipe.
 type PipeReader struct {
 	p *pipe
@@ -131,7 +133,7 @@ type PipeReader struct {
 // If the write end is closed with an error, that error is
 // returned as err; otherwise err is EOF.
 func (r *PipeReader) Read(data []byte) (n int, err error) {
-	return r.p.Read(data)
+	return r.p.read(data)
 }
 
 // Close closes the reader; subsequent writes to the
@@ -146,7 +148,7 @@ func (r *PipeReader) Close() error {
 // CloseWithError never overwrites the previous error if it exists
 // and always returns nil.
 func (r *PipeReader) CloseWithError(err error) error {
-	return r.p.CloseRead(err)
+	return r.p.closeRead(err)
 }
 
 // A PipeWriter is the write half of a pipe.
@@ -160,7 +162,7 @@ type PipeWriter struct {
 // If the read end is closed with an error, that err is
 // returned as err; otherwise err is ErrClosedPipe.
 func (w *PipeWriter) Write(data []byte) (n int, err error) {
-	return w.p.Write(data)
+	return w.p.write(data)
 }
 
 // Close closes the writer; subsequent reads from the
@@ -176,7 +178,7 @@ func (w *PipeWriter) Close() error {
 // CloseWithError never overwrites the previous error if it exists
 // and always returns nil.
 func (w *PipeWriter) CloseWithError(err error) error {
-	return w.p.CloseWrite(err)
+	return w.p.closeWrite(err)
 }
 
 // Pipe creates a synchronous in-memory pipe.
diff --git a/src/make.bash b/src/make.bash
index 4fb13f62758d7910d837225ab195ff49897ce96c..7986125a06ffc652016aef3252a24f6337379ea9 100755
--- a/src/make.bash
+++ b/src/make.bash
@@ -130,8 +130,8 @@ if [ "$(uname -s)" = "GNU/kFreeBSD" ]; then
 	export CGO_ENABLED=0
 fi
 
-# Test which linker/loader our system is using
-if type readelf >/dev/null 2>&1; then
+# Test which linker/loader our system is using, if GO_LDSO is not set.
+if [ -z "$GO_LDSO" ] && type readelf >/dev/null 2>&1; then
 	if echo "int main() { return 0; }" | ${CC:-cc} -o ./test-musl-ldso -x c - >/dev/null 2>&1; then
 		LDSO=$(readelf -l ./test-musl-ldso | grep 'interpreter:' | sed -e 's/^.*interpreter: \(.*\)[]]/\1/') >/dev/null 2>&1
 		[ -z "$LDSO" ] || export GO_LDSO="$LDSO"
@@ -203,16 +203,10 @@ if [ "$1" = "--dist-tool" ]; then
 	exit 0
 fi
 
-buildall="-a"
-if [ "$1" = "--no-clean" ]; then
-	buildall=""
-	shift
-fi
-
 # Run dist bootstrap to complete make.bash.
 # Bootstrap installs a proper cmd/dist, built with the new toolchain.
 # Throw ours, built with Go 1.4, away after bootstrap.
-./cmd/dist/dist bootstrap $buildall $vflag $GO_DISTFLAGS "$@"
+./cmd/dist/dist bootstrap -a $vflag $GO_DISTFLAGS "$@"
 rm -f ./cmd/dist/dist
 
 # DO NOT ADD ANY NEW CODE HERE.
diff --git a/src/make.bat b/src/make.bat
index b4a8e7084905e5487559779842596f35d89335e0..8f2825b09a935fe36cc6cb67baa230eeed9e5977 100644
--- a/src/make.bat
+++ b/src/make.bat
@@ -112,20 +112,20 @@ if x%2==x--dist-tool goto copydist
 if x%3==x--dist-tool goto copydist
 if x%4==x--dist-tool goto copydist
 
-set buildall=-a
-if x%1==x--no-clean set buildall=
-if x%2==x--no-clean set buildall=
-if x%3==x--no-clean set buildall=
-if x%4==x--no-clean set buildall=
-if x%1==x--no-banner set buildall=%buildall% --no-banner
-if x%2==x--no-banner set buildall=%buildall% --no-banner
-if x%3==x--no-banner set buildall=%buildall% --no-banner
-if x%4==x--no-banner set buildall=%buildall% --no-banner
+set bootstrapflags=
+if x%1==x--no-clean set bootstrapflags=--no-clean
+if x%2==x--no-clean set bootstrapflags=--no-clean
+if x%3==x--no-clean set bootstrapflags=--no-clean
+if x%4==x--no-clean set bootstrapflags=--no-clean
+if x%1==x--no-banner set bootstrapflags=%bootstrapflags% --no-banner
+if x%2==x--no-banner set bootstrapflags=%bootstrapflags% --no-banner
+if x%3==x--no-banner set bootstrapflags=%bootstrapflags% --no-banner
+if x%4==x--no-banner set bootstrapflags=%bootstrapflags% --no-banner
 
 :: Run dist bootstrap to complete make.bash.
 :: Bootstrap installs a proper cmd/dist, built with the new toolchain.
 :: Throw ours, built with Go 1.4, away after bootstrap.
-.\cmd\dist\dist.exe bootstrap %vflag% %buildall%
+.\cmd\dist\dist.exe bootstrap -a %vflag% %bootstrapflags%
 if errorlevel 1 goto fail
 del .\cmd\dist\dist.exe
 goto end
diff --git a/src/make.rc b/src/make.rc
index f5e57e975561839c3e3c1ac7bd24e5d03b2219b6..7bdc7dea1c1eefde25478f71b970b2466512b41c 100755
--- a/src/make.rc
+++ b/src/make.rc
@@ -92,15 +92,10 @@ if(~ $1 --dist-tool){
 	exit
 }
 
-buildall = -a
-if(~ $1 --no-clean) {
-	buildall = ()
-	shift
-}
 # Run dist bootstrap to complete make.bash.
 # Bootstrap installs a proper cmd/dist, built with the new toolchain.
 # Throw ours, built with Go 1.4, away after bootstrap.
-./cmd/dist/dist bootstrap $vflag $buildall $*
+./cmd/dist/dist bootstrap -a $vflag $*
 rm -f ./cmd/dist/dist
 
 # DO NOT ADD ANY NEW CODE HERE.
diff --git a/src/math/big/float.go b/src/math/big/float.go
index 42050e2c39d76e2c703730ac8883b0dd2f31f715..a8c91a6e547c268371b1093ae0d57c5af2fa47a3 100644
--- a/src/math/big/float.go
+++ b/src/math/big/float.go
@@ -304,7 +304,9 @@ func (z *Float) setExpAndRound(exp int64, sbit uint) {
 // SetMantExp sets z to mant × 2**exp and returns z.
 // The result z has the same precision and rounding mode
 // as mant. SetMantExp is an inverse of MantExp but does
-// not require 0.5 <= |mant| < 1.0. Specifically:
+// not require 0.5 <= |mant| < 1.0. Specifically, for a
+// given x of type *Float, SetMantExp relates to MantExp
+// as follows:
 //
 //	mant := new(Float)
 //	new(Float).SetMantExp(mant, x.MantExp(mant)).Cmp(x) == 0
diff --git a/src/math/sinh_s390x.s b/src/math/sinh_s390x.s
index 73701f24f12fd813d590714df09e705a4a3283aa..d684968a3a87e684c80d166369fc3dc229a1186c 100644
--- a/src/math/sinh_s390x.s
+++ b/src/math/sinh_s390x.s
@@ -56,11 +56,11 @@ GLOBL sinhe9<>+0(SB), RODATA, $8
 
 TEXT ·sinhAsm(SB),NOSPLIT,$0-16
 	FMOVD   x+0(FP), F0
-	//specail case Sinh(±0) = ±0
+	//special case Sinh(±0) = ±0
 	FMOVD   $(0.0), F1
 	FCMPU   F0, F1
 	BEQ     sinhIsZero
-	//specail case Sinh(±Inf = ±Inf
+	//special case Sinh(±Inf) = ±Inf
 	FMOVD   $1.797693134862315708145274237317043567981e+308, F1
 	FCMPU   F1, F0
 	BLEU    sinhIsInf
diff --git a/src/math/tan_s390x.s b/src/math/tan_s390x.s
index b6e2295874e6ee83f1a70b38502492ad7d591135..82267608b97ea6c17b1f7f89a218c1c87c0d15b5 100644
--- a/src/math/tan_s390x.s
+++ b/src/math/tan_s390x.s
@@ -38,7 +38,7 @@ GLOBL ·tanxadd<> + 0(SB), RODATA, $8
 
 TEXT	·tanAsm(SB), NOSPLIT, $0-16
 	FMOVD	x+0(FP), F0
-	//specail case Tan(±0) = ±0
+	//special case Tan(±0) = ±0
 	FMOVD   $(0.0), F1
 	FCMPU   F0, F1
 	BEQ     atanIsZero
diff --git a/src/net/cgo_unix.go b/src/net/cgo_unix.go
index 2ea86e074fb9436fa55f9a6884a828b4cd16ad24..5bf6fd84bc2aca1c4fd49e12417367d44f0ce0f7 100644
--- a/src/net/cgo_unix.go
+++ b/src/net/cgo_unix.go
@@ -323,7 +323,7 @@ func cgoLookupAddrPTR(addr string, sa *C.struct_sockaddr, salen C.socklen_t) (na
 			break
 		}
 	}
-	return []string{absDomainName(b)}, nil
+	return []string{absDomainName(string(b))}, nil
 }
 
 func cgoReverseLookup(result chan<- reverseLookupResult, addr string, sa *C.struct_sockaddr, salen C.socklen_t) {
diff --git a/src/net/dnsclient.go b/src/net/dnsclient.go
index 1bbe39650bbac2f7ec755d8de90c2ccae3845632..3c1a12995a8033e044f74a19c1bb29da30f375a2 100644
--- a/src/net/dnsclient.go
+++ b/src/net/dnsclient.go
@@ -5,6 +5,7 @@
 package net
 
 import (
+	"internal/bytealg"
 	"internal/itoa"
 	"sort"
 
@@ -136,18 +137,11 @@ func isDomainName(s string) bool {
 // It's hard to tell so we settle on the heuristic that names without dots
 // (like "localhost" or "myhost") do not get trailing dots, but any other
 // names do.
-func absDomainName(b []byte) string {
-	hasDots := false
-	for _, x := range b {
-		if x == '.' {
-			hasDots = true
-			break
-		}
-	}
-	if hasDots && b[len(b)-1] != '.' {
-		b = append(b, '.')
+func absDomainName(s string) string {
+	if bytealg.IndexByteString(s, '.') != -1 && s[len(s)-1] != '.' {
+		s += "."
 	}
-	return string(b)
+	return s
 }
 
 // An SRV represents a single DNS SRV record.
diff --git a/src/net/fd_posix.go b/src/net/fd_posix.go
index 4703ff33a10c71ef22df5317f8b413cfe186e0d6..38e5a8d61d10533a5c7b1f8b044cacf01dd24237 100644
--- a/src/net/fd_posix.go
+++ b/src/net/fd_posix.go
@@ -63,6 +63,17 @@ func (fd *netFD) readFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
 	runtime.KeepAlive(fd)
 	return n, sa, wrapSyscallError(readFromSyscallName, err)
 }
+func (fd *netFD) readFromInet4(p []byte, from *syscall.SockaddrInet4) (n int, err error) {
+	n, err = fd.pfd.ReadFromInet4(p, from)
+	runtime.KeepAlive(fd)
+	return n, wrapSyscallError(readFromSyscallName, err)
+}
+
+func (fd *netFD) readFromInet6(p []byte, from *syscall.SockaddrInet6) (n int, err error) {
+	n, err = fd.pfd.ReadFromInet6(p, from)
+	runtime.KeepAlive(fd)
+	return n, wrapSyscallError(readFromSyscallName, err)
+}
 
 func (fd *netFD) readMsg(p []byte, oob []byte, flags int) (n, oobn, retflags int, sa syscall.Sockaddr, err error) {
 	n, oobn, retflags, sa, err = fd.pfd.ReadMsg(p, oob, flags)
@@ -82,6 +93,18 @@ func (fd *netFD) writeTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
 	return n, wrapSyscallError(writeToSyscallName, err)
 }
 
+func (fd *netFD) writeToInet4(p []byte, sa syscall.SockaddrInet4) (n int, err error) {
+	n, err = fd.pfd.WriteToInet4(p, sa)
+	runtime.KeepAlive(fd)
+	return n, wrapSyscallError(writeToSyscallName, err)
+}
+
+func (fd *netFD) writeToInet6(p []byte, sa syscall.SockaddrInet6) (n int, err error) {
+	n, err = fd.pfd.WriteToInet6(p, sa)
+	runtime.KeepAlive(fd)
+	return n, wrapSyscallError(writeToSyscallName, err)
+}
+
 func (fd *netFD) writeMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
 	n, oobn, err = fd.pfd.WriteMsg(p, oob, sa)
 	runtime.KeepAlive(fd)
diff --git a/src/net/hosts.go b/src/net/hosts.go
index 5c560f3756ed1a2ec58ef9b08345f8a96530c3ba..e604031920b1fe55a495679f64b740683161fdfd 100644
--- a/src/net/hosts.go
+++ b/src/net/hosts.go
@@ -82,10 +82,10 @@ func readHosts() {
 			continue
 		}
 		for i := 1; i < len(f); i++ {
-			name := absDomainName([]byte(f[i]))
+			name := absDomainName(f[i])
 			h := []byte(f[i])
 			lowerASCIIBytes(h)
-			key := absDomainName(h)
+			key := absDomainName(string(h))
 			hs[key] = append(hs[key], addr)
 			is[addr] = append(is[addr], name)
 		}
@@ -106,11 +106,12 @@ func lookupStaticHost(host string) []string {
 	defer hosts.Unlock()
 	readHosts()
 	if len(hosts.byName) != 0 {
-		// TODO(jbd,bradfitz): avoid this alloc if host is already all lowercase?
-		// or linear scan the byName map if it's small enough?
-		lowerHost := []byte(host)
-		lowerASCIIBytes(lowerHost)
-		if ips, ok := hosts.byName[absDomainName(lowerHost)]; ok {
+		if hasUpperCase(host) {
+			lowerHost := []byte(host)
+			lowerASCIIBytes(lowerHost)
+			host = string(lowerHost)
+		}
+		if ips, ok := hosts.byName[absDomainName(host)]; ok {
 			ipsCp := make([]string, len(ips))
 			copy(ipsCp, ips)
 			return ipsCp
diff --git a/src/net/hosts_test.go b/src/net/hosts_test.go
index 19c43999f9291ca77a13053c92b7efedc1c8e95e..72919140e9c79f032b493e2642b863c3b026755b 100644
--- a/src/net/hosts_test.go
+++ b/src/net/hosts_test.go
@@ -70,7 +70,7 @@ func TestLookupStaticHost(t *testing.T) {
 }
 
 func testStaticHost(t *testing.T, hostsPath string, ent staticHostEntry) {
-	ins := []string{ent.in, absDomainName([]byte(ent.in)), strings.ToLower(ent.in), strings.ToUpper(ent.in)}
+	ins := []string{ent.in, absDomainName(ent.in), strings.ToLower(ent.in), strings.ToUpper(ent.in)}
 	for _, in := range ins {
 		addrs := lookupStaticHost(in)
 		if !reflect.DeepEqual(addrs, ent.out) {
@@ -141,7 +141,7 @@ func TestLookupStaticAddr(t *testing.T) {
 func testStaticAddr(t *testing.T, hostsPath string, ent staticHostEntry) {
 	hosts := lookupStaticAddr(ent.in)
 	for i := range ent.out {
-		ent.out[i] = absDomainName([]byte(ent.out[i]))
+		ent.out[i] = absDomainName(ent.out[i])
 	}
 	if !reflect.DeepEqual(hosts, ent.out) {
 		t.Errorf("%s, lookupStaticAddr(%s) = %v; want %v", hostsPath, ent.in, hosts, ent.out)
diff --git a/src/net/http/header.go b/src/net/http/header.go
index 4c72dcb2c88d254f3e8b81a483bb6b40079f4b37..5c77cbb8826661dfcaab9f9283c2d7e9f04acf09 100644
--- a/src/net/http/header.go
+++ b/src/net/http/header.go
@@ -13,6 +13,8 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"golang.org/x/net/http/httpguts"
 )
 
 // A Header represents the key-value pairs in an HTTP header.
@@ -192,6 +194,13 @@ func (h Header) writeSubset(w io.Writer, exclude map[string]bool, trace *httptra
 	kvs, sorter := h.sortedKeyValues(exclude)
 	var formattedVals []string
 	for _, kv := range kvs {
+		if !httpguts.ValidHeaderFieldName(kv.key) {
+			// This could be an error. In the common case of
+			// writing response headers, however, we have no good
+			// way to provide the error back to the server
+			// handler, so just drop invalid headers instead.
+			continue
+		}
 		for _, v := range kv.values {
 			v = headerNewlineToSpace.Replace(v)
 			v = textproto.TrimString(v)
diff --git a/src/net/http/header_test.go b/src/net/http/header_test.go
index 47893629194b6a6dedde343b06c73ac0db976f34..57d16f51a5d62e662847b47fbf33203048c8b8bb 100644
--- a/src/net/http/header_test.go
+++ b/src/net/http/header_test.go
@@ -89,6 +89,19 @@ var headerWriteTests = []struct {
 			"k4: 4a\r\nk4: 4b\r\nk6: 6a\r\nk6: 6b\r\n" +
 			"k7: 7a\r\nk7: 7b\r\nk8: 8a\r\nk8: 8b\r\nk9: 9a\r\nk9: 9b\r\n",
 	},
+	// Tests invalid characters in headers.
+	{
+		Header{
+			"Content-Type":             {"text/html; charset=UTF-8"},
+			"NewlineInValue":           {"1\r\nBar: 2"},
+			"NewlineInKey\r\n":         {"1"},
+			"Colon:InKey":              {"1"},
+			"Evil: 1\r\nSmuggledValue": {"1"},
+		},
+		nil,
+		"Content-Type: text/html; charset=UTF-8\r\n" +
+			"NewlineInValue: 1  Bar: 2\r\n",
+	},
 }
 
 func TestHeaderWrite(t *testing.T) {
diff --git a/src/net/http/httputil/reverseproxy.go b/src/net/http/httputil/reverseproxy.go
index 5d39955d62d15fa962f8ead218e93a620af49a13..8b63368386f43ba81a574e571ada7bcfffd195e0 100644
--- a/src/net/http/httputil/reverseproxy.go
+++ b/src/net/http/httputil/reverseproxy.go
@@ -235,6 +235,15 @@ func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	if req.ContentLength == 0 {
 		outreq.Body = nil // Issue 16036: nil Body for http.Transport retries
 	}
+	if outreq.Body != nil {
+		// Reading from the request body after returning from a handler is not
+		// allowed, and the RoundTrip goroutine that reads the Body can outlive
+		// this handler. This can lead to a crash if the handler panics (see
+		// Issue 46866). Although calling Close doesn't guarantee there isn't
+		// any Read in flight after the handle returns, in practice it's safe to
+		// read after closing it.
+		defer outreq.Body.Close()
+	}
 	if outreq.Header == nil {
 		outreq.Header = make(http.Header) // Issue 33142: historical behavior was to always allocate
 	}
diff --git a/src/net/http/httputil/reverseproxy_test.go b/src/net/http/httputil/reverseproxy_test.go
index 1898ed8b8afdef4a1e0da64daa1c0cd480070483..4b6ad77a29466fe0fbb9f1e79fa1bd804b2264ea 100644
--- a/src/net/http/httputil/reverseproxy_test.go
+++ b/src/net/http/httputil/reverseproxy_test.go
@@ -1122,6 +1122,45 @@ func TestReverseProxy_PanicBodyError(t *testing.T) {
 	rproxy.ServeHTTP(httptest.NewRecorder(), req)
 }
 
+// Issue #46866: panic without closing incoming request body causes a panic
+func TestReverseProxy_PanicClosesIncomingBody(t *testing.T) {
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		out := "this call was relayed by the reverse proxy"
+		// Coerce a wrong content length to induce io.ErrUnexpectedEOF
+		w.Header().Set("Content-Length", fmt.Sprintf("%d", len(out)*2))
+		fmt.Fprintln(w, out)
+	}))
+	defer backend.Close()
+	backendURL, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	proxyHandler := NewSingleHostReverseProxy(backendURL)
+	proxyHandler.ErrorLog = log.New(io.Discard, "", 0) // quiet for tests
+	frontend := httptest.NewServer(proxyHandler)
+	defer frontend.Close()
+	frontendClient := frontend.Client()
+
+	var wg sync.WaitGroup
+	for i := 0; i < 2; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 10; j++ {
+				const reqLen = 6 * 1024 * 1024
+				req, _ := http.NewRequest("POST", frontend.URL, &io.LimitedReader{R: neverEnding('x'), N: reqLen})
+				req.ContentLength = reqLen
+				resp, _ := frontendClient.Transport.RoundTrip(req)
+				if resp != nil {
+					io.Copy(io.Discard, resp.Body)
+					resp.Body.Close()
+				}
+			}
+		}()
+	}
+	wg.Wait()
+}
+
 func TestSelectFlushInterval(t *testing.T) {
 	tests := []struct {
 		name string
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index 690e0c299d2b353489dc63c4eaeff58b3f817dbe..eeaa49264450de6785415669622801410d8abca9 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -6441,10 +6441,11 @@ func TestErrorWriteLoopRace(t *testing.T) {
 // Test that a new request which uses the connection of an active request
 // cannot cause it to be canceled as well.
 func TestCancelRequestWhenSharingConnection(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping in short mode")
-	}
+	reqc := make(chan chan struct{}, 2)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, req *Request) {
+		ch := make(chan struct{}, 1)
+		reqc <- ch
+		<-ch
 		w.Header().Add("Content-Length", "0")
 	}))
 	defer ts.Close()
@@ -6456,34 +6457,58 @@ func TestCancelRequestWhenSharingConnection(t *testing.T) {
 
 	var wg sync.WaitGroup
 
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	wg.Add(1)
+	putidlec := make(chan chan struct{})
+	go func() {
+		defer wg.Done()
+		ctx := httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
+			PutIdleConn: func(error) {
+				// Signal that the idle conn has been returned to the pool,
+				// and wait for the order to proceed.
+				ch := make(chan struct{})
+				putidlec <- ch
+				<-ch
+			},
+		})
+		req, _ := NewRequestWithContext(ctx, "GET", ts.URL, nil)
+		res, err := client.Do(req)
+		if err == nil {
+			res.Body.Close()
+		}
+		if err != nil {
+			t.Errorf("request 1: got err %v, want nil", err)
+		}
+	}()
 
-	for i := 0; i < 10; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
-			for ctx.Err() == nil {
-				reqctx, reqcancel := context.WithCancel(ctx)
-				go reqcancel()
-				req, _ := NewRequestWithContext(reqctx, "GET", ts.URL, nil)
-				res, err := client.Do(req)
-				if err == nil {
-					res.Body.Close()
-				}
-			}
-		}()
-	}
+	// Wait for the first request to receive a response and return the
+	// connection to the idle pool.
+	r1c := <-reqc
+	close(r1c)
+	idlec := <-putidlec
 
-	for ctx.Err() == nil {
-		req, _ := NewRequest("GET", ts.URL, nil)
-		if res, err := client.Do(req); err != nil {
-			t.Errorf("unexpected: %p %v", req, err)
-			break
-		} else {
+	wg.Add(1)
+	cancelctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		defer wg.Done()
+		req, _ := NewRequestWithContext(cancelctx, "GET", ts.URL, nil)
+		res, err := client.Do(req)
+		if err == nil {
 			res.Body.Close()
 		}
-	}
+		if !errors.Is(err, context.Canceled) {
+			t.Errorf("request 2: got err %v, want Canceled", err)
+		}
+	}()
 
+	// Wait for the second request to arrive at the server, and then cancel
+	// the request context.
+	r2c := <-reqc
 	cancel()
+
+	// Give the cancelation a moment to take effect, and then unblock the first request.
+	time.Sleep(1 * time.Millisecond)
+	close(idlec)
+
+	close(r2c)
 	wg.Wait()
 }
diff --git a/src/net/interface_aix.go b/src/net/interface_aix.go
index 49f78c2abbcbfa78eba1c57e3f8755842dc4a095..7ad45d11756a0646096121fdcf200a0e61ecd5e9 100644
--- a/src/net/interface_aix.go
+++ b/src/net/interface_aix.go
@@ -78,7 +78,7 @@ func interfaceTable(ifindex int) ([]Interface, error) {
 				// Retrieve MTU
 				ifr := &ifreq{}
 				copy(ifr.Name[:], ifi.Name)
-				err = unix.Ioctl(sock, syscall.SIOCGIFMTU, uintptr(unsafe.Pointer(ifr)))
+				err = unix.Ioctl(sock, syscall.SIOCGIFMTU, unsafe.Pointer(ifr))
 				if err != nil {
 					return nil, err
 				}
diff --git a/src/net/ip.go b/src/net/ip.go
index 38e1aa2247f5c329d9c247de420b2a58ecc8a25b..b016bef144a5d7e3b4e7c0369b617fd88161f93d 100644
--- a/src/net/ip.go
+++ b/src/net/ip.go
@@ -308,7 +308,7 @@ func ubtoa(dst []byte, start int, v byte) int {
 // It returns one of 4 forms:
 //   - "", if ip has length 0
 //   - dotted decimal ("192.0.2.1"), if ip is an IPv4 or IP4-mapped IPv6 address
-//   - IPv6 ("2001:db8::1"), if ip is a valid IPv6 address
+//   - IPv6 conforming to RFC 5952 ("2001:db8::1"), if ip is a valid IPv6 address
 //   - the hexadecimal form of ip, without punctuation, if no other cases apply
 func (ip IP) String() string {
 	p := ip
diff --git a/src/net/ipsock_posix.go b/src/net/ipsock_posix.go
index c51c2274015dcf8382e079bcb8ef3759d1a87f88..50003ac4464bc013ae5d10cb65cbc953b24ad8a6 100644
--- a/src/net/ipsock_posix.go
+++ b/src/net/ipsock_posix.go
@@ -142,42 +142,58 @@ func internetSocket(ctx context.Context, net string, laddr, raddr sockaddr, soty
 	return socket(ctx, net, family, sotype, proto, ipv6only, laddr, raddr, ctrlFn)
 }
 
+func ipToSockaddrInet4(ip IP, port int) (syscall.SockaddrInet4, error) {
+	if len(ip) == 0 {
+		ip = IPv4zero
+	}
+	ip4 := ip.To4()
+	if ip4 == nil {
+		return syscall.SockaddrInet4{}, &AddrError{Err: "non-IPv4 address", Addr: ip.String()}
+	}
+	sa := syscall.SockaddrInet4{Port: port}
+	copy(sa.Addr[:], ip4)
+	return sa, nil
+}
+
+func ipToSockaddrInet6(ip IP, port int, zone string) (syscall.SockaddrInet6, error) {
+	// In general, an IP wildcard address, which is either
+	// "0.0.0.0" or "::", means the entire IP addressing
+	// space. For some historical reason, it is used to
+	// specify "any available address" on some operations
+	// of IP node.
+	//
+	// When the IP node supports IPv4-mapped IPv6 address,
+	// we allow a listener to listen to the wildcard
+	// address of both IP addressing spaces by specifying
+	// IPv6 wildcard address.
+	if len(ip) == 0 || ip.Equal(IPv4zero) {
+		ip = IPv6zero
+	}
+	// We accept any IPv6 address including IPv4-mapped
+	// IPv6 address.
+	ip6 := ip.To16()
+	if ip6 == nil {
+		return syscall.SockaddrInet6{}, &AddrError{Err: "non-IPv6 address", Addr: ip.String()}
+	}
+	sa := syscall.SockaddrInet6{Port: port, ZoneId: uint32(zoneCache.index(zone))}
+	copy(sa.Addr[:], ip6)
+	return sa, nil
+}
+
 func ipToSockaddr(family int, ip IP, port int, zone string) (syscall.Sockaddr, error) {
 	switch family {
 	case syscall.AF_INET:
-		if len(ip) == 0 {
-			ip = IPv4zero
-		}
-		ip4 := ip.To4()
-		if ip4 == nil {
-			return nil, &AddrError{Err: "non-IPv4 address", Addr: ip.String()}
+		sa, err := ipToSockaddrInet4(ip, port)
+		if err != nil {
+			return nil, err
 		}
-		sa := &syscall.SockaddrInet4{Port: port}
-		copy(sa.Addr[:], ip4)
-		return sa, nil
+		return &sa, nil
 	case syscall.AF_INET6:
-		// In general, an IP wildcard address, which is either
-		// "0.0.0.0" or "::", means the entire IP addressing
-		// space. For some historical reason, it is used to
-		// specify "any available address" on some operations
-		// of IP node.
-		//
-		// When the IP node supports IPv4-mapped IPv6 address,
-		// we allow a listener to listen to the wildcard
-		// address of both IP addressing spaces by specifying
-		// IPv6 wildcard address.
-		if len(ip) == 0 || ip.Equal(IPv4zero) {
-			ip = IPv6zero
-		}
-		// We accept any IPv6 address including IPv4-mapped
-		// IPv6 address.
-		ip6 := ip.To16()
-		if ip6 == nil {
-			return nil, &AddrError{Err: "non-IPv6 address", Addr: ip.String()}
+		sa, err := ipToSockaddrInet6(ip, port, zone)
+		if err != nil {
+			return nil, err
 		}
-		sa := &syscall.SockaddrInet6{Port: port, ZoneId: uint32(zoneCache.index(zone))}
-		copy(sa.Addr[:], ip6)
-		return sa, nil
+		return &sa, nil
 	}
 	return nil, &AddrError{Err: "invalid address family", Addr: ip.String()}
 }
diff --git a/src/net/lookup.go b/src/net/lookup.go
index d350ef7fc03b0b6259a562e5f28b04a40157fdf0..02beaca7e16dc1e7de74ceae459ac47a1e975275 100644
--- a/src/net/lookup.go
+++ b/src/net/lookup.go
@@ -620,6 +620,6 @@ func (r *Resolver) LookupAddr(ctx context.Context, addr string) ([]string, error
 }
 
 // errMalformedDNSRecordsDetail is the DNSError detail which is returned when a Resolver.Lookup...
-// method recieves DNS records which contain invalid DNS names. This may be returned alongside
+// method receives DNS records which contain invalid DNS names. This may be returned alongside
 // results which have had the malformed records filtered out.
 var errMalformedDNSRecordsDetail = "DNS response contained records which contain invalid names"
diff --git a/src/net/lookup_plan9.go b/src/net/lookup_plan9.go
index 75c18b33ac06f0eca362200a8909b45bf3ab23c3..d43a03b778d477a3327dfd00f96667a6f56b9507 100644
--- a/src/net/lookup_plan9.go
+++ b/src/net/lookup_plan9.go
@@ -262,8 +262,8 @@ func (*Resolver) lookupSRV(ctx context.Context, service, proto, name string) (cn
 		if !(portOk && priorityOk && weightOk) {
 			continue
 		}
-		addrs = append(addrs, &SRV{absDomainName([]byte(f[5])), uint16(port), uint16(priority), uint16(weight)})
-		cname = absDomainName([]byte(f[0]))
+		addrs = append(addrs, &SRV{absDomainName(f[5]), uint16(port), uint16(priority), uint16(weight)})
+		cname = absDomainName(f[0])
 	}
 	byPriorityWeight(addrs).sort()
 	return
@@ -280,7 +280,7 @@ func (*Resolver) lookupMX(ctx context.Context, name string) (mx []*MX, err error
 			continue
 		}
 		if pref, _, ok := dtoi(f[2]); ok {
-			mx = append(mx, &MX{absDomainName([]byte(f[3])), uint16(pref)})
+			mx = append(mx, &MX{absDomainName(f[3]), uint16(pref)})
 		}
 	}
 	byPref(mx).sort()
@@ -297,7 +297,7 @@ func (*Resolver) lookupNS(ctx context.Context, name string) (ns []*NS, err error
 		if len(f) < 3 {
 			continue
 		}
-		ns = append(ns, &NS{absDomainName([]byte(f[2]))})
+		ns = append(ns, &NS{absDomainName(f[2])})
 	}
 	return
 }
@@ -329,7 +329,7 @@ func (*Resolver) lookupAddr(ctx context.Context, addr string) (name []string, er
 		if len(f) < 3 {
 			continue
 		}
-		name = append(name, absDomainName([]byte(f[2])))
+		name = append(name, absDomainName(f[2]))
 	}
 	return
 }
diff --git a/src/net/lookup_windows.go b/src/net/lookup_windows.go
index bb34a081336930dee36c8a6d17e67ded263f9058..27e5f86910e0fcff75b14b80731b4bebb46d21d4 100644
--- a/src/net/lookup_windows.go
+++ b/src/net/lookup_windows.go
@@ -226,7 +226,7 @@ func (*Resolver) lookupCNAME(ctx context.Context, name string) (string, error) {
 	// windows returns DNS_INFO_NO_RECORDS if there are no CNAME-s
 	if errno, ok := e.(syscall.Errno); ok && errno == syscall.DNS_INFO_NO_RECORDS {
 		// if there are no aliases, the canonical name is the input name
-		return absDomainName([]byte(name)), nil
+		return absDomainName(name), nil
 	}
 	if e != nil {
 		return "", &DNSError{Err: winError("dnsquery", e).Error(), Name: name}
@@ -235,7 +235,7 @@ func (*Resolver) lookupCNAME(ctx context.Context, name string) (string, error) {
 
 	resolved := resolveCNAME(syscall.StringToUTF16Ptr(name), r)
 	cname := windows.UTF16PtrToString(resolved)
-	return absDomainName([]byte(cname)), nil
+	return absDomainName(cname), nil
 }
 
 func (*Resolver) lookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
@@ -258,10 +258,10 @@ func (*Resolver) lookupSRV(ctx context.Context, service, proto, name string) (st
 	srvs := make([]*SRV, 0, 10)
 	for _, p := range validRecs(r, syscall.DNS_TYPE_SRV, target) {
 		v := (*syscall.DNSSRVData)(unsafe.Pointer(&p.Data[0]))
-		srvs = append(srvs, &SRV{absDomainName([]byte(syscall.UTF16ToString((*[256]uint16)(unsafe.Pointer(v.Target))[:]))), v.Port, v.Priority, v.Weight})
+		srvs = append(srvs, &SRV{absDomainName(syscall.UTF16ToString((*[256]uint16)(unsafe.Pointer(v.Target))[:])), v.Port, v.Priority, v.Weight})
 	}
 	byPriorityWeight(srvs).sort()
-	return absDomainName([]byte(target)), srvs, nil
+	return absDomainName(target), srvs, nil
 }
 
 func (*Resolver) lookupMX(ctx context.Context, name string) ([]*MX, error) {
@@ -278,7 +278,7 @@ func (*Resolver) lookupMX(ctx context.Context, name string) ([]*MX, error) {
 	mxs := make([]*MX, 0, 10)
 	for _, p := range validRecs(r, syscall.DNS_TYPE_MX, name) {
 		v := (*syscall.DNSMXData)(unsafe.Pointer(&p.Data[0]))
-		mxs = append(mxs, &MX{absDomainName([]byte(windows.UTF16PtrToString(v.NameExchange))), v.Preference})
+		mxs = append(mxs, &MX{absDomainName(windows.UTF16PtrToString(v.NameExchange)), v.Preference})
 	}
 	byPref(mxs).sort()
 	return mxs, nil
@@ -298,7 +298,7 @@ func (*Resolver) lookupNS(ctx context.Context, name string) ([]*NS, error) {
 	nss := make([]*NS, 0, 10)
 	for _, p := range validRecs(r, syscall.DNS_TYPE_NS, name) {
 		v := (*syscall.DNSPTRData)(unsafe.Pointer(&p.Data[0]))
-		nss = append(nss, &NS{absDomainName([]byte(syscall.UTF16ToString((*[256]uint16)(unsafe.Pointer(v.Host))[:])))})
+		nss = append(nss, &NS{absDomainName(syscall.UTF16ToString((*[256]uint16)(unsafe.Pointer(v.Host))[:]))})
 	}
 	return nss, nil
 }
@@ -344,7 +344,7 @@ func (*Resolver) lookupAddr(ctx context.Context, addr string) ([]string, error)
 	ptrs := make([]string, 0, 10)
 	for _, p := range validRecs(r, syscall.DNS_TYPE_PTR, arpa) {
 		v := (*syscall.DNSPTRData)(unsafe.Pointer(&p.Data[0]))
-		ptrs = append(ptrs, absDomainName([]byte(windows.UTF16PtrToString(v.Host))))
+		ptrs = append(ptrs, absDomainName(windows.UTF16PtrToString(v.Host)))
 	}
 	return ptrs, nil
 }
diff --git a/src/net/lookup_windows_test.go b/src/net/lookup_windows_test.go
index aa95501d023930d114970e828296e9d10b531d9e..f726ef0f3475b064d59be85972f5cde95a7a9010 100644
--- a/src/net/lookup_windows_test.go
+++ b/src/net/lookup_windows_test.go
@@ -220,14 +220,14 @@ func nslookupMX(name string) (mx []*MX, err error) {
 	rx := regexp.MustCompile(`(?m)^([a-z0-9.\-]+)\s+mail exchanger\s*=\s*([0-9]+)\s*([a-z0-9.\-]+)$`)
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
 		pref, _, _ := dtoi(ans[2])
-		mx = append(mx, &MX{absDomainName([]byte(ans[3])), uint16(pref)})
+		mx = append(mx, &MX{absDomainName(ans[3]), uint16(pref)})
 	}
 	// windows nslookup syntax
 	// gmail.com       MX preference = 30, mail exchanger = alt3.gmail-smtp-in.l.google.com
 	rx = regexp.MustCompile(`(?m)^([a-z0-9.\-]+)\s+MX preference\s*=\s*([0-9]+)\s*,\s*mail exchanger\s*=\s*([a-z0-9.\-]+)$`)
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
 		pref, _, _ := dtoi(ans[2])
-		mx = append(mx, &MX{absDomainName([]byte(ans[3])), uint16(pref)})
+		mx = append(mx, &MX{absDomainName(ans[3]), uint16(pref)})
 	}
 	return
 }
@@ -241,7 +241,7 @@ func nslookupNS(name string) (ns []*NS, err error) {
 	// golang.org      nameserver = ns1.google.com.
 	rx := regexp.MustCompile(`(?m)^([a-z0-9.\-]+)\s+nameserver\s*=\s*([a-z0-9.\-]+)$`)
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
-		ns = append(ns, &NS{absDomainName([]byte(ans[2]))})
+		ns = append(ns, &NS{absDomainName(ans[2])})
 	}
 	return
 }
@@ -258,7 +258,7 @@ func nslookupCNAME(name string) (cname string, err error) {
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
 		last = ans[2]
 	}
-	return absDomainName([]byte(last)), nil
+	return absDomainName(last), nil
 }
 
 func nslookupTXT(name string) (txt []string, err error) {
@@ -299,7 +299,7 @@ func lookupPTR(name string) (ptr []string, err error) {
 	ptr = make([]string, 0, 10)
 	rx := regexp.MustCompile(`(?m)^Pinging\s+([a-zA-Z0-9.\-]+)\s+\[.*$`)
 	for _, ans := range rx.FindAllStringSubmatch(r, -1) {
-		ptr = append(ptr, absDomainName([]byte(ans[1])))
+		ptr = append(ptr, absDomainName(ans[1]))
 	}
 	return
 }
diff --git a/src/net/net_fake.go b/src/net/net_fake.go
index 74fc1da6fd80af665696880153bfc49a508900d6..48419be6703ac7caeaaadc46157be59d068922cb 100644
--- a/src/net/net_fake.go
+++ b/src/net/net_fake.go
@@ -266,6 +266,14 @@ func sysSocket(family, sotype, proto int) (int, error) {
 
 func (fd *netFD) readFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
 	return 0, nil, syscall.ENOSYS
+
+}
+func (fd *netFD) readFromInet4(p []byte, sa *syscall.SockaddrInet4) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func (fd *netFD) readFromInet6(p []byte, sa *syscall.SockaddrInet6) (n int, err error) {
+	return 0, syscall.ENOSYS
 }
 
 func (fd *netFD) readMsg(p []byte, oob []byte, flags int) (n, oobn, retflags int, sa syscall.Sockaddr, err error) {
@@ -276,6 +284,14 @@ func (fd *netFD) writeTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
 	return 0, syscall.ENOSYS
 }
 
+func (fd *netFD) writeToInet4(p []byte, sa syscall.SockaddrInet4) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func (fd *netFD) writeToInet6(p []byte, sa syscall.SockaddrInet6) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
 func (fd *netFD) writeMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
 	return 0, 0, syscall.ENOSYS
 }
diff --git a/src/net/parse.go b/src/net/parse.go
index 6c230ab63fa0c7906a5c80b95f0e2443be5d139f..0d7cce12e624a22020af04544dc85a01e135936d 100644
--- a/src/net/parse.go
+++ b/src/net/parse.go
@@ -208,6 +208,16 @@ func last(s string, b byte) int {
 	return i
 }
 
+// hasUpperCase tells whether the given string contains at least one upper-case.
+func hasUpperCase(s string) bool {
+	for i := range s {
+		if 'A' <= s[i] && s[i] <= 'Z' {
+			return true
+		}
+	}
+	return false
+}
+
 // lowerASCIIBytes makes x ASCII lowercase in-place.
 func lowerASCIIBytes(x []byte) {
 	for i, b := range x {
diff --git a/src/net/udpsock_posix.go b/src/net/udpsock_posix.go
index 96fb373ce770ca91a8a8dc0eec2f1712ca381ed1..3a333ca2438250c9f6848302aea6f3ff0291725e 100644
--- a/src/net/udpsock_posix.go
+++ b/src/net/udpsock_posix.go
@@ -44,13 +44,25 @@ func (a *UDPAddr) toLocal(net string) sockaddr {
 }
 
 func (c *UDPConn) readFrom(b []byte, addr *UDPAddr) (int, *UDPAddr, error) {
-	n, sa, err := c.fd.readFrom(b)
-	switch sa := sa.(type) {
-	case *syscall.SockaddrInet4:
-		*addr = UDPAddr{IP: sa.Addr[0:], Port: sa.Port}
-	case *syscall.SockaddrInet6:
-		*addr = UDPAddr{IP: sa.Addr[0:], Port: sa.Port, Zone: zoneCache.name(int(sa.ZoneId))}
-	default:
+	var n int
+	var err error
+	switch c.fd.family {
+	case syscall.AF_INET:
+		var from syscall.SockaddrInet4
+		n, err = c.fd.readFromInet4(b, &from)
+		if err == nil {
+			ip := from.Addr // copy from.Addr; ip escapes, so this line allocates 4 bytes
+			*addr = UDPAddr{IP: ip[:], Port: from.Port}
+		}
+	case syscall.AF_INET6:
+		var from syscall.SockaddrInet6
+		n, err = c.fd.readFromInet6(b, &from)
+		if err == nil {
+			ip := from.Addr // copy from.Addr; ip escapes, so this line allocates 16 bytes
+			*addr = UDPAddr{IP: ip[:], Port: from.Port, Zone: zoneCache.name(int(from.ZoneId))}
+		}
+	}
+	if err != nil {
 		// No sockaddr, so don't return UDPAddr.
 		addr = nil
 	}
@@ -76,11 +88,23 @@ func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
 	if addr == nil {
 		return 0, errMissingAddress
 	}
-	sa, err := addr.sockaddr(c.fd.family)
-	if err != nil {
-		return 0, err
+
+	switch c.fd.family {
+	case syscall.AF_INET:
+		sa, err := ipToSockaddrInet4(addr.IP, addr.Port)
+		if err != nil {
+			return 0, err
+		}
+		return c.fd.writeToInet4(b, sa)
+	case syscall.AF_INET6:
+		sa, err := ipToSockaddrInet6(addr.IP, addr.Port, addr.Zone)
+		if err != nil {
+			return 0, err
+		}
+		return c.fd.writeToInet6(b, sa)
+	default:
+		return 0, &AddrError{Err: "invalid address family", Addr: addr.IP.String()}
 	}
-	return c.fd.writeTo(b, sa)
 }
 
 func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
diff --git a/src/os/exec/lp_windows_test.go b/src/os/exec/lp_windows_test.go
index f834ffede03609eb6fdb6de000cea871cf8ec201..bbf6a9b7f13b5ef5ac412c7eabac6dca3b56f11e 100644
--- a/src/os/exec/lp_windows_test.go
+++ b/src/os/exec/lp_windows_test.go
@@ -312,9 +312,6 @@ func TestLookPath(t *testing.T) {
 	// Run all tests.
 	for i, test := range lookPathTests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {
-			if i == 16 {
-				t.Skip("golang.org/issue/44379")
-			}
 			dir := filepath.Join(tmp, "d"+strconv.Itoa(i))
 			err := os.Mkdir(dir, 0700)
 			if err != nil {
diff --git a/src/os/user/lookup_plan9.go b/src/os/user/lookup_plan9.go
index 33ae3a6adf416c5d74523e5fba68b51c002e64c2..51caf55935e37eb6880521487f6ddf95695c5db3 100644
--- a/src/os/user/lookup_plan9.go
+++ b/src/os/user/lookup_plan9.go
@@ -18,6 +18,7 @@ const (
 )
 
 func init() {
+	userImplemented = false
 	groupImplemented = false
 }
 
diff --git a/src/os/user/user_test.go b/src/os/user/user_test.go
index 49920317bed93b9c7c32baea3d4f809c2127f538..1112c78c004f92816c13645f6637fa9e2e96d1a3 100644
--- a/src/os/user/user_test.go
+++ b/src/os/user/user_test.go
@@ -56,10 +56,6 @@ func compare(t *testing.T, want, got *User) {
 func TestLookup(t *testing.T) {
 	checkUser(t)
 
-	if runtime.GOOS == "plan9" {
-		t.Skipf("Lookup not implemented on %q", runtime.GOOS)
-	}
-
 	want, err := Current()
 	if err != nil {
 		t.Fatalf("Current: %v", err)
@@ -77,10 +73,6 @@ func TestLookup(t *testing.T) {
 func TestLookupId(t *testing.T) {
 	checkUser(t)
 
-	if runtime.GOOS == "plan9" {
-		t.Skipf("LookupId not implemented on %q", runtime.GOOS)
-	}
-
 	want, err := Current()
 	if err != nil {
 		t.Fatalf("Current: %v", err)
diff --git a/src/path/filepath/path_test.go b/src/path/filepath/path_test.go
index bc5509b49cf1ab7e4820405a10a869d9b56edd61..55b27f1af88928df36c993dd28d500105676a35c 100644
--- a/src/path/filepath/path_test.go
+++ b/src/path/filepath/path_test.go
@@ -791,6 +791,8 @@ var winisabstests = []IsAbsTest{
 	{`c:a\b`, false},
 	{`c:\a\b`, true},
 	{`c:/a/b`, true},
+	{`\\host\share`, true},
+	{`\\host\share\`, true},
 	{`\\host\share\foo`, true},
 	{`//host/share/foo/bar`, true},
 }
diff --git a/src/path/filepath/path_windows.go b/src/path/filepath/path_windows.go
index 445c868e41460456469d1459d868352fdaa3e5c2..b4d8ac33010e753bf158f3c7f550995e52c7e5e1 100644
--- a/src/path/filepath/path_windows.go
+++ b/src/path/filepath/path_windows.go
@@ -45,6 +45,10 @@ func IsAbs(path string) (b bool) {
 	if l == 0 {
 		return false
 	}
+	// If the volume name starts with a double slash, this is a UNC path.
+	if isSlash(path[0]) && isSlash(path[1]) {
+		return true
+	}
 	path = path[l:]
 	if path == "" {
 		return false
diff --git a/src/race.bash b/src/race.bash
index 81fb4be60646b70cc0b7541beb82695d673a25e8..f795ec9b7b75f27976eea9ecec92144f627d8311 100755
--- a/src/race.bash
+++ b/src/race.bash
@@ -13,35 +13,16 @@ function usage {
 	exit 1
 }
 
-case $(uname) in
-"Darwin")
-	if [ $(uname -m) != "x86_64" ] && [ $(uname -m) != "arm64" ]; then
-		usage
-	fi
-	;;
-"Linux")
-	if [ $(uname -m) != "x86_64" ] && [ $(uname -m) != "ppc64le" ] && [ $(uname -m) != "aarch64" ]; then
-		usage
-	fi
-	;;
-"FreeBSD")
-	if [ $(uname -m) != "amd64" ]; then
-		usage
-	fi
-	;;
-"NetBSD")
-	if [ $(uname -m) != "amd64" ]; then
-		usage
-	fi
-	;;
-"OpenBSD")
-	if [ $(uname -m) != "amd64" ]; then
-		usage
-	fi
-	;;
-*)
-	usage
-	;;
+case $(uname -s -m) in
+  "Darwin x86_64") ;;
+  "Darwin arm64")  ;;
+  "Linux x86_64")  ;;
+  "Linux ppc64le") ;;
+  "Linux aarch64") ;;
+  "FreeBSD amd64") ;;
+  "NetBSD amd64")  ;;
+  "OpenBSD amd64") ;;
+  *) usage         ;;
 esac
 
 if [ ! -f make.bash ]; then
diff --git a/src/reflect/abi.go b/src/reflect/abi.go
index 17b79a8394fad5b5f12afd581356a6c354cfa0b4..9ddde3ae57cfca4b49413efccb6c126d6902f40d 100644
--- a/src/reflect/abi.go
+++ b/src/reflect/abi.go
@@ -6,6 +6,7 @@ package reflect
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"internal/goexperiment"
 	"unsafe"
 )
@@ -167,7 +168,7 @@ func (a *abiSeq) addRcvr(rcvr *rtype) (*abiStep, bool) {
 	a.valueStart = append(a.valueStart, len(a.steps))
 	var ok, ptr bool
 	if ifaceIndir(rcvr) || rcvr.pointers() {
-		ok = a.assignIntN(0, ptrSize, 1, 0b1)
+		ok = a.assignIntN(0, goarch.PtrSize, 1, 0b1)
 		ptr = true
 	} else {
 		// TODO(mknyszek): Is this case even possible?
@@ -176,11 +177,11 @@ func (a *abiSeq) addRcvr(rcvr *rtype) (*abiStep, bool) {
 		// in the reflect package which only conditionally added
 		// a pointer bit to the reflect.(Value).Call stack frame's
 		// GC bitmap.
-		ok = a.assignIntN(0, ptrSize, 1, 0b0)
+		ok = a.assignIntN(0, goarch.PtrSize, 1, 0b0)
 		ptr = false
 	}
 	if !ok {
-		a.stackAssign(ptrSize, ptrSize)
+		a.stackAssign(goarch.PtrSize, goarch.PtrSize)
 		return &a.steps[len(a.steps)-1], ptr
 	}
 	return nil, ptr
@@ -202,7 +203,7 @@ func (a *abiSeq) regAssign(t *rtype, offset uintptr) bool {
 	case Bool, Int, Uint, Int8, Uint8, Int16, Uint16, Int32, Uint32, Uintptr:
 		return a.assignIntN(offset, t.size, 1, 0b0)
 	case Int64, Uint64:
-		switch ptrSize {
+		switch goarch.PtrSize {
 		case 4:
 			return a.assignIntN(offset, 4, 2, 0b0)
 		case 8:
@@ -215,11 +216,11 @@ func (a *abiSeq) regAssign(t *rtype, offset uintptr) bool {
 	case Complex128:
 		return a.assignFloatN(offset, 8, 2)
 	case String:
-		return a.assignIntN(offset, ptrSize, 2, 0b01)
+		return a.assignIntN(offset, goarch.PtrSize, 2, 0b01)
 	case Interface:
-		return a.assignIntN(offset, ptrSize, 2, 0b10)
+		return a.assignIntN(offset, goarch.PtrSize, 2, 0b10)
 	case Slice:
-		return a.assignIntN(offset, ptrSize, 3, 0b001)
+		return a.assignIntN(offset, goarch.PtrSize, 3, 0b001)
 	case Array:
 		tt := (*arrayType)(unsafe.Pointer(t))
 		switch tt.len {
@@ -262,7 +263,7 @@ func (a *abiSeq) assignIntN(offset, size uintptr, n int, ptrMap uint8) bool {
 	if n > 8 || n < 0 {
 		panic("invalid n")
 	}
-	if ptrMap != 0 && size != ptrSize {
+	if ptrMap != 0 && size != goarch.PtrSize {
 		panic("non-empty pointer map passed for non-pointer-size values")
 	}
 	if a.iregs+n > intArgRegs {
@@ -413,7 +414,7 @@ func newAbiDesc(t *funcType, rcvr *rtype) abiDesc {
 				stackPtrs.append(0)
 			}
 		} else {
-			spill += ptrSize
+			spill += goarch.PtrSize
 		}
 	}
 	for i, arg := range t.in() {
@@ -430,12 +431,12 @@ func newAbiDesc(t *funcType, rcvr *rtype) abiDesc {
 			}
 		}
 	}
-	spill = align(spill, ptrSize)
+	spill = align(spill, goarch.PtrSize)
 
 	// From the input parameters alone, we now know
 	// the stackCallArgsSize and retOffset.
 	stackCallArgsSize := in.stackBytes
-	retOffset := align(in.stackBytes, ptrSize)
+	retOffset := align(in.stackBytes, goarch.PtrSize)
 
 	// Compute the stack frame pointer bitmap and register
 	// pointer bitmap for return values.
diff --git a/src/reflect/abi_test.go b/src/reflect/abi_test.go
index 5a0130f7b452b988bae5cb1eea552c635236633d..2b247d1d7986ff4a72156882b23c51b1f3d5e0bb 100644
--- a/src/reflect/abi_test.go
+++ b/src/reflect/abi_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build goexperiment.regabireflect
-// +build goexperiment.regabireflect
+//go:build goexperiment.regabireflect && goexperiment.regabiargs
+// +build goexperiment.regabireflect,goexperiment.regabiargs
 
 package reflect_test
 
diff --git a/src/reflect/all_test.go b/src/reflect/all_test.go
index eac27e886f21d6c8d8325d50ad5e9c615457d929..df79f058075f4b58e19549ae24d9c039b39771f4 100644
--- a/src/reflect/all_test.go
+++ b/src/reflect/all_test.go
@@ -10,6 +10,7 @@ import (
 	"flag"
 	"fmt"
 	"go/token"
+	"internal/goarch"
 	"io"
 	"math"
 	"math/rand"
@@ -6466,10 +6467,10 @@ func clobber() {
 
 func TestFuncLayout(t *testing.T) {
 	align := func(x uintptr) uintptr {
-		return (x + PtrSize - 1) &^ (PtrSize - 1)
+		return (x + goarch.PtrSize - 1) &^ (goarch.PtrSize - 1)
 	}
 	var r []byte
-	if PtrSize == 4 {
+	if goarch.PtrSize == 4 {
 		r = []byte{0, 0, 0, 1}
 	} else {
 		r = []byte{0, 0, 1}
@@ -6490,56 +6491,56 @@ func TestFuncLayout(t *testing.T) {
 	tests := []test{
 		{
 			typ:       ValueOf(func(a, b string) string { return "" }).Type(),
-			size:      6 * PtrSize,
-			argsize:   4 * PtrSize,
-			retOffset: 4 * PtrSize,
+			size:      6 * goarch.PtrSize,
+			argsize:   4 * goarch.PtrSize,
+			retOffset: 4 * goarch.PtrSize,
 			stack:     []byte{1, 0, 1, 0, 1},
 			gc:        []byte{1, 0, 1, 0, 1},
 		},
 		{
 			typ:       ValueOf(func(a, b, c uint32, p *byte, d uint16) {}).Type(),
-			size:      align(align(3*4) + PtrSize + 2),
-			argsize:   align(3*4) + PtrSize + 2,
-			retOffset: align(align(3*4) + PtrSize + 2),
+			size:      align(align(3*4) + goarch.PtrSize + 2),
+			argsize:   align(3*4) + goarch.PtrSize + 2,
+			retOffset: align(align(3*4) + goarch.PtrSize + 2),
 			stack:     r,
 			gc:        r,
 		},
 		{
 			typ:       ValueOf(func(a map[int]int, b uintptr, c interface{}) {}).Type(),
-			size:      4 * PtrSize,
-			argsize:   4 * PtrSize,
-			retOffset: 4 * PtrSize,
+			size:      4 * goarch.PtrSize,
+			argsize:   4 * goarch.PtrSize,
+			retOffset: 4 * goarch.PtrSize,
 			stack:     []byte{1, 0, 1, 1},
 			gc:        []byte{1, 0, 1, 1},
 		},
 		{
 			typ:       ValueOf(func(a S) {}).Type(),
-			size:      4 * PtrSize,
-			argsize:   4 * PtrSize,
-			retOffset: 4 * PtrSize,
+			size:      4 * goarch.PtrSize,
+			argsize:   4 * goarch.PtrSize,
+			retOffset: 4 * goarch.PtrSize,
 			stack:     []byte{0, 0, 1, 1},
 			gc:        []byte{0, 0, 1, 1},
 		},
 		{
 			rcvr:      ValueOf((*byte)(nil)).Type(),
 			typ:       ValueOf(func(a uintptr, b *int) {}).Type(),
-			size:      3 * PtrSize,
-			argsize:   3 * PtrSize,
-			retOffset: 3 * PtrSize,
+			size:      3 * goarch.PtrSize,
+			argsize:   3 * goarch.PtrSize,
+			retOffset: 3 * goarch.PtrSize,
 			stack:     []byte{1, 0, 1},
 			gc:        []byte{1, 0, 1},
 		},
 		{
 			typ:       ValueOf(func(a uintptr) {}).Type(),
-			size:      PtrSize,
-			argsize:   PtrSize,
-			retOffset: PtrSize,
+			size:      goarch.PtrSize,
+			argsize:   goarch.PtrSize,
+			retOffset: goarch.PtrSize,
 			stack:     []byte{},
 			gc:        []byte{},
 		},
 		{
 			typ:       ValueOf(func() uintptr { return 0 }).Type(),
-			size:      PtrSize,
+			size:      goarch.PtrSize,
 			argsize:   0,
 			retOffset: 0,
 			stack:     []byte{},
@@ -6548,9 +6549,9 @@ func TestFuncLayout(t *testing.T) {
 		{
 			rcvr:      ValueOf(uintptr(0)).Type(),
 			typ:       ValueOf(func(a uintptr) {}).Type(),
-			size:      2 * PtrSize,
-			argsize:   2 * PtrSize,
-			retOffset: 2 * PtrSize,
+			size:      2 * goarch.PtrSize,
+			argsize:   2 * goarch.PtrSize,
+			retOffset: 2 * goarch.PtrSize,
 			stack:     []byte{1},
 			gc:        []byte{1},
 			// Note: this one is tricky, as the receiver is not a pointer. But we
@@ -6756,7 +6757,7 @@ func TestGCBits(t *testing.T) {
 	verifyGCBits(t, TypeOf(([][10000]Xscalar)(nil)), lit(1))
 	verifyGCBits(t, SliceOf(ArrayOf(10000, Tscalar)), lit(1))
 
-	hdr := make([]byte, 8/PtrSize)
+	hdr := make([]byte, 8/goarch.PtrSize)
 
 	verifyMapBucket := func(t *testing.T, k, e Type, m interface{}, want []byte) {
 		verifyGCBits(t, MapBucketOf(k, e), want)
@@ -6772,7 +6773,7 @@ func TestGCBits(t *testing.T) {
 		join(hdr, rep(8, lit(0, 1)), rep(8, lit(1)), lit(1)))
 	verifyMapBucket(t, Tint64, Tptr,
 		map[int64]Xptr(nil),
-		join(hdr, rep(8, rep(8/PtrSize, lit(0))), rep(8, lit(1)), lit(1)))
+		join(hdr, rep(8, rep(8/goarch.PtrSize, lit(0))), rep(8, lit(1)), lit(1)))
 	verifyMapBucket(t,
 		Tscalar, Tscalar,
 		map[Xscalar]Xscalar(nil),
@@ -6782,20 +6783,20 @@ func TestGCBits(t *testing.T) {
 		map[[2]Xscalarptr][3]Xptrscalar(nil),
 		join(hdr, rep(8*2, lit(0, 1)), rep(8*3, lit(1, 0)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize, Tscalarptr), ArrayOf(64/PtrSize, Tptrscalar),
-		map[[64 / PtrSize]Xscalarptr][64 / PtrSize]Xptrscalar(nil),
-		join(hdr, rep(8*64/PtrSize, lit(0, 1)), rep(8*64/PtrSize, lit(1, 0)), lit(1)))
+		ArrayOf(64/goarch.PtrSize, Tscalarptr), ArrayOf(64/goarch.PtrSize, Tptrscalar),
+		map[[64 / goarch.PtrSize]Xscalarptr][64 / goarch.PtrSize]Xptrscalar(nil),
+		join(hdr, rep(8*64/goarch.PtrSize, lit(0, 1)), rep(8*64/goarch.PtrSize, lit(1, 0)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize+1, Tscalarptr), ArrayOf(64/PtrSize, Tptrscalar),
-		map[[64/PtrSize + 1]Xscalarptr][64 / PtrSize]Xptrscalar(nil),
-		join(hdr, rep(8, lit(1)), rep(8*64/PtrSize, lit(1, 0)), lit(1)))
+		ArrayOf(64/goarch.PtrSize+1, Tscalarptr), ArrayOf(64/goarch.PtrSize, Tptrscalar),
+		map[[64/goarch.PtrSize + 1]Xscalarptr][64 / goarch.PtrSize]Xptrscalar(nil),
+		join(hdr, rep(8, lit(1)), rep(8*64/goarch.PtrSize, lit(1, 0)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize, Tscalarptr), ArrayOf(64/PtrSize+1, Tptrscalar),
-		map[[64 / PtrSize]Xscalarptr][64/PtrSize + 1]Xptrscalar(nil),
-		join(hdr, rep(8*64/PtrSize, lit(0, 1)), rep(8, lit(1)), lit(1)))
+		ArrayOf(64/goarch.PtrSize, Tscalarptr), ArrayOf(64/goarch.PtrSize+1, Tptrscalar),
+		map[[64 / goarch.PtrSize]Xscalarptr][64/goarch.PtrSize + 1]Xptrscalar(nil),
+		join(hdr, rep(8*64/goarch.PtrSize, lit(0, 1)), rep(8, lit(1)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize+1, Tscalarptr), ArrayOf(64/PtrSize+1, Tptrscalar),
-		map[[64/PtrSize + 1]Xscalarptr][64/PtrSize + 1]Xptrscalar(nil),
+		ArrayOf(64/goarch.PtrSize+1, Tscalarptr), ArrayOf(64/goarch.PtrSize+1, Tptrscalar),
+		map[[64/goarch.PtrSize + 1]Xscalarptr][64/goarch.PtrSize + 1]Xptrscalar(nil),
 		join(hdr, rep(8, lit(1)), rep(8, lit(1)), lit(1)))
 }
 
@@ -7295,4 +7296,11 @@ func TestConvertibleTo(t *testing.T) {
 	if t1.ConvertibleTo(t2) {
 		t.Fatalf("(%s).ConvertibleTo(%s) = true, want false", t1, t2)
 	}
+
+	t3 := ValueOf([]example1.MyStruct{}).Type()
+	t4 := ValueOf([]example2.MyStruct{}).Type()
+
+	if t3.ConvertibleTo(t4) {
+		t.Fatalf("(%s).ConvertibleTo(%s) = true, want false", t3, t4)
+	}
 }
diff --git a/src/reflect/asm_amd64.s b/src/reflect/asm_amd64.s
index facf07516d8c2441058c7c032db482bd5a4d2c6b..d21d498063b55e382a1e473fcb5e6a501be88d36 100644
--- a/src/reflect/asm_amd64.s
+++ b/src/reflect/asm_amd64.s
@@ -24,15 +24,13 @@
 // See the comment on the declaration of makeFuncStub in makefunc.go
 // for more details.
 // No arg size here; runtime pulls arg map out of the func value.
-// makeFuncStub must be ABIInternal because it is placed directly
-// in function values.
 // This frame contains two locals. See the comment above LOCAL_RETVALID.
-TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$312
+TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$312
 	NO_LOCAL_POINTERS
 	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
 	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·spillArgs(SB)
+	CALL	runtime·spillArgs(SB)
 	MOVQ	DX, 24(SP) // outside of moveMakeFuncArgPtrs's arg area
 	MOVQ	DX, 0(SP)
 	MOVQ	R12, 8(SP)
@@ -48,22 +46,20 @@ TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$312
 	MOVQ	AX, 24(SP)
 	CALL	·callReflect(SB)
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·unspillArgs(SB)
+	CALL	runtime·unspillArgs(SB)
 	RET
 
 // methodValueCall is the code half of the function returned by makeMethodValue.
 // See the comment on the declaration of methodValueCall in makefunc.go
 // for more details.
 // No arg size here; runtime pulls arg map out of the func value.
-// methodValueCall must be ABIInternal because it is placed directly
-// in function values.
 // This frame contains two locals. See the comment above LOCAL_RETVALID.
-TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$312
+TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$312
 	NO_LOCAL_POINTERS
 	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
 	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·spillArgs(SB)
+	CALL	runtime·spillArgs(SB)
 	MOVQ	DX, 24(SP) // outside of moveMakeFuncArgPtrs's arg area
 	MOVQ	DX, 0(SP)
 	MOVQ	R12, 8(SP)
@@ -79,5 +75,5 @@ TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$312
 	MOVQ	AX, 24(SP)
 	CALL	·callMethod(SB)
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·unspillArgs(SB)
+	CALL	runtime·unspillArgs(SB)
 	RET
diff --git a/src/reflect/asm_arm64.s b/src/reflect/asm_arm64.s
index 5fe88e27e400d24bb97d2c57c5f58c7d95248c46..5b9b3573fa2a7e721e482cfe61b91dbf25552e62 100644
--- a/src/reflect/asm_arm64.s
+++ b/src/reflect/asm_arm64.s
@@ -5,34 +5,75 @@
 #include "textflag.h"
 #include "funcdata.h"
 
+// The frames of each of the two functions below contain two locals, at offsets
+// that are known to the runtime.
+//
+// The first local is a bool called retValid with a whole pointer-word reserved
+// for it on the stack. The purpose of this word is so that the runtime knows
+// whether the stack-allocated return space contains valid values for stack
+// scanning.
+//
+// The second local is an abi.RegArgs value whose offset is also known to the
+// runtime, so that a stack map for it can be constructed, since it contains
+// pointers visible to the GC.
+#define LOCAL_RETVALID 40
+#define LOCAL_REGARGS 48
+
+// The frame size of the functions below is
+// 32 (args of callReflect) + 8 (bool + padding) + 392 (abi.RegArgs) = 432.
+
 // makeFuncStub is the code half of the function returned by MakeFunc.
 // See the comment on the declaration of makeFuncStub in makefunc.go
 // for more details.
 // No arg size here, runtime pulls arg map out of the func value.
-TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$40
+TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$432
 	NO_LOCAL_POINTERS
+	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
+	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·spillArgs(SB)
+	MOVD	R26, 32(RSP) // outside of moveMakeFuncArgPtrs's arg area
+	MOVD	R26, 8(RSP)
+	MOVD	R20, 16(RSP)
+	CALL	·moveMakeFuncArgPtrs(SB)
+	MOVD	32(RSP), R26
 	MOVD	R26, 8(RSP)
 	MOVD	$argframe+0(FP), R3
 	MOVD	R3, 16(RSP)
-	MOVB	$0, 40(RSP)
-	ADD	$40, RSP, R3
+	MOVB	$0, LOCAL_RETVALID(RSP)
+	ADD	$LOCAL_RETVALID, RSP, R3
 	MOVD	R3, 24(RSP)
-	MOVD	$0, 32(RSP)
-	BL	·callReflect(SB)
+	ADD	$LOCAL_REGARGS, RSP, R3
+	MOVD	R3, 32(RSP)
+	CALL	·callReflect(SB)
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·unspillArgs(SB)
 	RET
 
 // methodValueCall is the code half of the function returned by makeMethodValue.
 // See the comment on the declaration of methodValueCall in makefunc.go
 // for more details.
 // No arg size here; runtime pulls arg map out of the func value.
-TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$40
+TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$432
 	NO_LOCAL_POINTERS
+	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
+	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·spillArgs(SB)
+	MOVD	R26, 32(RSP) // outside of moveMakeFuncArgPtrs's arg area
+	MOVD	R26, 8(RSP)
+	MOVD	R20, 16(RSP)
+	CALL	·moveMakeFuncArgPtrs(SB)
+	MOVD	32(RSP), R26
 	MOVD	R26, 8(RSP)
 	MOVD	$argframe+0(FP), R3
 	MOVD	R3, 16(RSP)
-	MOVB	$0, 40(RSP)
-	ADD	$40, RSP, R3
+	MOVB	$0, LOCAL_RETVALID(RSP)
+	ADD	$LOCAL_RETVALID, RSP, R3
 	MOVD	R3, 24(RSP)
-	MOVD	$0, 32(RSP)
-	BL	·callMethod(SB)
+	ADD	$LOCAL_REGARGS, RSP, R3
+	MOVD	R3, 32(RSP)
+	CALL	·callMethod(SB)
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·unspillArgs(SB)
 	RET
diff --git a/src/reflect/example_test.go b/src/reflect/example_test.go
index 23c08e4950049ed44f818d1d118ef1892adb1ad9..684bafd64869bb16fb4ad6a5be6dbfdd7c83ebe6 100644
--- a/src/reflect/example_test.go
+++ b/src/reflect/example_test.go
@@ -166,3 +166,31 @@ func ExampleStructOf() {
 	// json:  {"height":0.4,"age":2}
 	// value: &{Height:1.5 Age:10}
 }
+
+func ExampleValue_FieldByIndex() {
+	// This example shows a case in which the name of a promoted field
+	// is hidden by another field: FieldByName will not work, so
+	// FieldByIndex must be used instead.
+	type user struct {
+		firstName string
+		lastName  string
+	}
+
+	type data struct {
+		user
+		firstName string
+		lastName  string
+	}
+
+	u := data{
+		user:      user{"Embedded John", "Embedded Doe"},
+		firstName: "John",
+		lastName:  "Doe",
+	}
+
+	s := reflect.ValueOf(u).FieldByIndex([]int{0, 1})
+	fmt.Println("embedded last name:", s)
+
+	// Output:
+	// embedded last name: Embedded Doe
+}
diff --git a/src/reflect/export_test.go b/src/reflect/export_test.go
index b6830a98020f54bc18f30e995c56f50f3412aef7..01749e30d85229a43ad976f738e60f324b9a7057 100644
--- a/src/reflect/export_test.go
+++ b/src/reflect/export_test.go
@@ -5,6 +5,7 @@
 package reflect
 
 import (
+	"internal/goarch"
 	"sync"
 	"unsafe"
 )
@@ -22,8 +23,6 @@ func IsRO(v Value) bool {
 
 var CallGC = &callGC
 
-const PtrSize = ptrSize
-
 // FuncLayout calls funcLayout and returns a subset of the results for testing.
 //
 // Bitmaps like stack, gc, inReg, and outReg are expanded such that each bit
@@ -65,7 +64,7 @@ func FuncLayout(t Type, rcvr Type) (frametype Type, argSize, retOffset uintptr,
 	// Expand frame type's GC bitmap into byte-map.
 	ptrs = ft.ptrdata != 0
 	if ptrs {
-		nptrs := ft.ptrdata / ptrSize
+		nptrs := ft.ptrdata / goarch.PtrSize
 		gcdata := ft.gcSlice(0, (nptrs+7)/8)
 		for i := uintptr(0); i < nptrs; i++ {
 			gc = append(gc, gcdata[i/8]>>(i%8)&1)
diff --git a/src/reflect/makefunc.go b/src/reflect/makefunc.go
index d53e68a3594a66de2fddde11860279931d1106f5..588be8bcc155602cdad79e7f4b7003444fbe7772 100644
--- a/src/reflect/makefunc.go
+++ b/src/reflect/makefunc.go
@@ -52,11 +52,7 @@ func MakeFunc(typ Type, fn func(args []Value) (results []Value)) Value {
 	t := typ.common()
 	ftyp := (*funcType)(unsafe.Pointer(t))
 
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. https://golang.org/s/go11func.)
-	dummy := makeFuncStub
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
+	code := abi.FuncPCABI0(makeFuncStub)
 
 	// makeFuncImpl contains a stack map for use by the runtime
 	_, _, abi := funcLayout(ftyp, nil)
@@ -111,11 +107,7 @@ func makeMethodValue(op string, v Value) Value {
 	// v.Type returns the actual type of the method value.
 	ftyp := (*funcType)(unsafe.Pointer(v.Type().(*rtype)))
 
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. https://golang.org/s/go11func.)
-	dummy := methodValueCall
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
+	code := abi.FuncPCABI0(methodValueCall)
 
 	// methodValue contains a stack map for use by the runtime
 	_, _, abi := funcLayout(ftyp, nil)
diff --git a/src/reflect/swapper.go b/src/reflect/swapper.go
index 0cf40666b1e8e5c35a0920440b75f579e72c0a2e..67b7fbe59be83689fb3dcc7d9b1d9fefd592586f 100644
--- a/src/reflect/swapper.go
+++ b/src/reflect/swapper.go
@@ -5,6 +5,7 @@
 package reflect
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"unsafe"
 )
@@ -36,7 +37,7 @@ func Swapper(slice interface{}) func(i, j int) {
 
 	// Some common & small cases, without using memmove:
 	if hasPtr {
-		if size == ptrSize {
+		if size == goarch.PtrSize {
 			ps := *(*[]unsafe.Pointer)(v.ptr)
 			return func(i, j int) { ps[i], ps[j] = ps[j], ps[i] }
 		}
diff --git a/src/reflect/type.go b/src/reflect/type.go
index f672a7a5d5fc996e93a38c4c99fddd4fee76a687..278426da09e3a6431cc518d7488839f906266f88 100644
--- a/src/reflect/type.go
+++ b/src/reflect/type.go
@@ -16,6 +16,7 @@
 package reflect
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"strconv"
 	"sync"
@@ -1924,13 +1925,13 @@ func MapOf(key, elem Type) Type {
 	}
 	mt.flags = 0
 	if ktyp.size > maxKeySize {
-		mt.keysize = uint8(ptrSize)
+		mt.keysize = uint8(goarch.PtrSize)
 		mt.flags |= 1 // indirect key
 	} else {
 		mt.keysize = uint8(ktyp.size)
 	}
 	if etyp.size > maxValSize {
-		mt.valuesize = uint8(ptrSize)
+		mt.valuesize = uint8(goarch.PtrSize)
 		mt.flags |= 2 // indirect value
 	} else {
 		mt.valuesize = uint8(etyp.size)
@@ -2231,31 +2232,31 @@ func bucketOf(ktyp, etyp *rtype) *rtype {
 	var ptrdata uintptr
 	var overflowPad uintptr
 
-	size := bucketSize*(1+ktyp.size+etyp.size) + overflowPad + ptrSize
+	size := bucketSize*(1+ktyp.size+etyp.size) + overflowPad + goarch.PtrSize
 	if size&uintptr(ktyp.align-1) != 0 || size&uintptr(etyp.align-1) != 0 {
 		panic("reflect: bad size computation in MapOf")
 	}
 
 	if ktyp.ptrdata != 0 || etyp.ptrdata != 0 {
-		nptr := (bucketSize*(1+ktyp.size+etyp.size) + ptrSize) / ptrSize
+		nptr := (bucketSize*(1+ktyp.size+etyp.size) + goarch.PtrSize) / goarch.PtrSize
 		mask := make([]byte, (nptr+7)/8)
-		base := bucketSize / ptrSize
+		base := bucketSize / goarch.PtrSize
 
 		if ktyp.ptrdata != 0 {
 			emitGCMask(mask, base, ktyp, bucketSize)
 		}
-		base += bucketSize * ktyp.size / ptrSize
+		base += bucketSize * ktyp.size / goarch.PtrSize
 
 		if etyp.ptrdata != 0 {
 			emitGCMask(mask, base, etyp, bucketSize)
 		}
-		base += bucketSize * etyp.size / ptrSize
-		base += overflowPad / ptrSize
+		base += bucketSize * etyp.size / goarch.PtrSize
+		base += overflowPad / goarch.PtrSize
 
 		word := base
 		mask[word/8] |= 1 << (word % 8)
 		gcdata = &mask[0]
-		ptrdata = (word + 1) * ptrSize
+		ptrdata = (word + 1) * goarch.PtrSize
 
 		// overflow word must be last
 		if ptrdata != size {
@@ -2264,7 +2265,7 @@ func bucketOf(ktyp, etyp *rtype) *rtype {
 	}
 
 	b := &rtype{
-		align:   ptrSize,
+		align:   goarch.PtrSize,
 		size:    size,
 		kind:    uint8(Struct),
 		ptrdata: ptrdata,
@@ -2288,8 +2289,8 @@ func emitGCMask(out []byte, base uintptr, typ *rtype, n uintptr) {
 	if typ.kind&kindGCProg != 0 {
 		panic("reflect: unexpected GC program")
 	}
-	ptrs := typ.ptrdata / ptrSize
-	words := typ.size / ptrSize
+	ptrs := typ.ptrdata / goarch.PtrSize
+	words := typ.size / goarch.PtrSize
 	mask := typ.gcSlice(0, (ptrs+7)/8)
 	for j := uintptr(0); j < ptrs; j++ {
 		if (mask[j/8]>>(j%8))&1 != 0 {
@@ -2312,7 +2313,7 @@ func appendGCProg(dst []byte, typ *rtype) []byte {
 	}
 
 	// Element is small with pointer mask; use as literal bits.
-	ptrs := typ.ptrdata / ptrSize
+	ptrs := typ.ptrdata / goarch.PtrSize
 	mask := typ.gcSlice(0, (ptrs+7)/8)
 
 	// Emit 120-bit chunks of full bytes (max is 127 but we avoid using partial bytes).
@@ -2759,7 +2760,7 @@ func StructOf(fields []StructField) Type {
 			}
 			// Pad to start of this field with zeros.
 			if ft.offset() > off {
-				n := (ft.offset() - off) / ptrSize
+				n := (ft.offset() - off) / goarch.PtrSize
 				prog = append(prog, 0x01, 0x00) // emit a 0 bit
 				if n > 1 {
 					prog = append(prog, 0x81)      // repeat previous bit
@@ -2936,11 +2937,11 @@ func ArrayOf(length int, elem Type) Type {
 		array.gcdata = typ.gcdata
 		array.ptrdata = typ.ptrdata
 
-	case typ.kind&kindGCProg == 0 && array.size <= maxPtrmaskBytes*8*ptrSize:
+	case typ.kind&kindGCProg == 0 && array.size <= maxPtrmaskBytes*8*goarch.PtrSize:
 		// Element is small with pointer mask; array is still small.
 		// Create direct pointer mask by turning each 1 bit in elem
 		// into length 1 bits in larger mask.
-		mask := make([]byte, (array.ptrdata/ptrSize+7)/8)
+		mask := make([]byte, (array.ptrdata/goarch.PtrSize+7)/8)
 		emitGCMask(mask, 0, typ, array.len)
 		array.gcdata = &mask[0]
 
@@ -2950,8 +2951,8 @@ func ArrayOf(length int, elem Type) Type {
 		prog := []byte{0, 0, 0, 0} // will be length of prog
 		prog = appendGCProg(prog, typ)
 		// Pad from ptrdata to size.
-		elemPtrs := typ.ptrdata / ptrSize
-		elemWords := typ.size / ptrSize
+		elemPtrs := typ.ptrdata / goarch.PtrSize
+		elemWords := typ.size / goarch.PtrSize
 		if elemPtrs < elemWords {
 			// Emit literal 0 bit, then repeat as needed.
 			prog = append(prog, 0x01, 0x00)
@@ -3063,13 +3064,13 @@ func funcLayout(t *funcType, rcvr *rtype) (frametype *rtype, framePool *sync.Poo
 
 	// build dummy rtype holding gc program
 	x := &rtype{
-		align: ptrSize,
+		align: goarch.PtrSize,
 		// Don't add spill space here; it's only necessary in
 		// reflectcall's frame, not in the allocated frame.
 		// TODO(mknyszek): Remove this comment when register
 		// spill space in the frame is no longer required.
-		size:    align(abi.retOffset+abi.ret.stackBytes, ptrSize),
-		ptrdata: uintptr(abi.stackPtrs.n) * ptrSize,
+		size:    align(abi.retOffset+abi.ret.stackBytes, goarch.PtrSize),
+		ptrdata: uintptr(abi.stackPtrs.n) * goarch.PtrSize,
 	}
 	if abi.stackPtrs.n > 0 {
 		x.gcdata = &abi.stackPtrs.data[0]
@@ -3124,14 +3125,14 @@ func addTypeBits(bv *bitVector, offset uintptr, t *rtype) {
 	switch Kind(t.kind & kindMask) {
 	case Chan, Func, Map, Ptr, Slice, String, UnsafePointer:
 		// 1 pointer at start of representation
-		for bv.n < uint32(offset/uintptr(ptrSize)) {
+		for bv.n < uint32(offset/uintptr(goarch.PtrSize)) {
 			bv.append(0)
 		}
 		bv.append(1)
 
 	case Interface:
 		// 2 pointers
-		for bv.n < uint32(offset/uintptr(ptrSize)) {
+		for bv.n < uint32(offset/uintptr(goarch.PtrSize)) {
 			bv.append(0)
 		}
 		bv.append(1)
diff --git a/src/reflect/value.go b/src/reflect/value.go
index 6f878eba5b0411af35e44d27ea6a64a2205248e7..de01f13825fca1d5d9b624eef0c241f62bd065d2 100644
--- a/src/reflect/value.go
+++ b/src/reflect/value.go
@@ -6,6 +6,7 @@ package reflect
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"internal/itoa"
 	"internal/unsafeheader"
 	"math"
@@ -13,8 +14,6 @@ import (
 	"unsafe"
 )
 
-const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
-
 // Value is the reflection interface to a Go value.
 //
 // Not all methods apply to all kinds of values. Restrictions,
@@ -94,7 +93,7 @@ func (f flag) ro() flag {
 // v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
 // if v.Kind() == Ptr, the base type must not be go:notinheap.
 func (v Value) pointer() unsafe.Pointer {
-	if v.typ.size != ptrSize || !v.typ.pointers() {
+	if v.typ.size != goarch.PtrSize || !v.typ.pointers() {
 		panic("can't call pointer on a non-pointer Value")
 	}
 	if v.flag&flagIndir != 0 {
@@ -509,7 +508,7 @@ func (v Value) call(op string, in []Value) []Value {
 				// Copy values to "integer registers."
 				if v.flag&flagIndir != 0 {
 					offset := add(v.ptr, st.offset, "precomputed value offset")
-					memmove(unsafe.Pointer(®Args.Ints[st.ireg]), offset, st.size)
+					memmove(regArgs.IntRegArgAddr(st.ireg, st.size), offset, st.size)
 				} else {
 					if st.kind == abiStepPointer {
 						// Duplicate this pointer in the pointer area of the
@@ -525,7 +524,7 @@ func (v Value) call(op string, in []Value) []Value {
 					panic("attempted to copy pointer to FP register")
 				}
 				offset := add(v.ptr, st.offset, "precomputed value offset")
-				memmove(unsafe.Pointer(®Args.Floats[st.freg]), offset, st.size)
+				memmove(regArgs.FloatRegArgAddr(st.freg, st.size), offset, st.size)
 			default:
 				panic("unknown ABI part kind")
 			}
@@ -533,7 +532,7 @@ func (v Value) call(op string, in []Value) []Value {
 	}
 	// TODO(mknyszek): Remove this when we no longer have
 	// caller reserved spill space.
-	frameSize = align(frameSize, ptrSize)
+	frameSize = align(frameSize, goarch.PtrSize)
 	frameSize += abi.spill
 
 	// Mark pointers in registers for the return path.
@@ -611,13 +610,13 @@ func (v Value) call(op string, in []Value) []Value {
 				switch st.kind {
 				case abiStepIntReg:
 					offset := add(s, st.offset, "precomputed value offset")
-					memmove(offset, unsafe.Pointer(®Args.Ints[st.ireg]), st.size)
+					memmove(offset, regArgs.IntRegArgAddr(st.ireg, st.size), st.size)
 				case abiStepPointer:
 					s := add(s, st.offset, "precomputed value offset")
 					*((*unsafe.Pointer)(s)) = regArgs.Ptrs[st.ireg]
 				case abiStepFloatReg:
 					offset := add(s, st.offset, "precomputed value offset")
-					memmove(offset, unsafe.Pointer(®Args.Floats[st.freg]), st.size)
+					memmove(offset, regArgs.FloatRegArgAddr(st.freg, st.size), st.size)
 				case abiStepStack:
 					panic("register-based return value has stack component")
 				default:
@@ -699,13 +698,13 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer, retValid *bool, regs
 					switch st.kind {
 					case abiStepIntReg:
 						offset := add(v.ptr, st.offset, "precomputed value offset")
-						memmove(offset, unsafe.Pointer(®s.Ints[st.ireg]), st.size)
+						memmove(offset, regs.IntRegArgAddr(st.ireg, st.size), st.size)
 					case abiStepPointer:
 						s := add(v.ptr, st.offset, "precomputed value offset")
 						*((*unsafe.Pointer)(s)) = regs.Ptrs[st.ireg]
 					case abiStepFloatReg:
 						offset := add(v.ptr, st.offset, "precomputed value offset")
-						memmove(offset, unsafe.Pointer(®s.Floats[st.freg]), st.size)
+						memmove(offset, regs.FloatRegArgAddr(st.freg, st.size), st.size)
 					case abiStepStack:
 						panic("register-based return value has stack component")
 					default:
@@ -785,7 +784,7 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer, retValid *bool, regs
 					// Copy values to "integer registers."
 					if v.flag&flagIndir != 0 {
 						offset := add(v.ptr, st.offset, "precomputed value offset")
-						memmove(unsafe.Pointer(®s.Ints[st.ireg]), offset, st.size)
+						memmove(regs.IntRegArgAddr(st.ireg, st.size), offset, st.size)
 					} else {
 						// Only populate the Ints space on the return path.
 						// This is safe because out is kept alive until the
@@ -800,7 +799,7 @@ func callReflect(ctxt *makeFuncImpl, frame unsafe.Pointer, retValid *bool, regs
 						panic("attempted to copy pointer to FP register")
 					}
 					offset := add(v.ptr, st.offset, "precomputed value offset")
-					memmove(unsafe.Pointer(®s.Floats[st.freg]), offset, st.size)
+					memmove(regs.FloatRegArgAddr(st.freg, st.size), offset, st.size)
 				default:
 					panic("unknown ABI part kind")
 				}
@@ -931,7 +930,7 @@ func callMethod(ctxt *methodValue, frame unsafe.Pointer, retValid *bool, regs *a
 
 	// Deal with the receiver. It's guaranteed to only be one word in size.
 	if st := methodABI.call.steps[0]; st.kind == abiStepStack {
-		// Only copy the reciever to the stack if the ABI says so.
+		// Only copy the receiver to the stack if the ABI says so.
 		// Otherwise, it'll be in a register already.
 		storeRcvr(rcvr, methodFrame)
 	} else {
@@ -958,9 +957,6 @@ func callMethod(ctxt *methodValue, frame unsafe.Pointer, retValid *bool, regs *a
 		// 2. Stack -> registers translation.
 		// 3. Registers -> stack translation.
 		// 4. Registers -> registers translation.
-		// TODO(mknyszek): Cases 2 and 3 below only work on little endian
-		// architectures. This is OK for now, but this needs to be fixed
-		// before supporting the register ABI on big endian architectures.
 
 		// If the value ABI passes the value on the stack,
 		// then the method ABI does too, because it has strictly
@@ -986,9 +982,9 @@ func callMethod(ctxt *methodValue, frame unsafe.Pointer, retValid *bool, regs *a
 					methodRegs.Ptrs[mStep.ireg] = *(*unsafe.Pointer)(from)
 					fallthrough // We need to make sure this ends up in Ints, too.
 				case abiStepIntReg:
-					memmove(unsafe.Pointer(&methodRegs.Ints[mStep.ireg]), from, mStep.size)
+					memmove(methodRegs.IntRegArgAddr(mStep.ireg, mStep.size), from, mStep.size)
 				case abiStepFloatReg:
-					memmove(unsafe.Pointer(&methodRegs.Floats[mStep.freg]), from, mStep.size)
+					memmove(methodRegs.FloatRegArgAddr(mStep.freg, mStep.size), from, mStep.size)
 				default:
 					panic("unexpected method step")
 				}
@@ -1004,9 +1000,9 @@ func callMethod(ctxt *methodValue, frame unsafe.Pointer, retValid *bool, regs *a
 					// Do the pointer copy directly so we get a write barrier.
 					*(*unsafe.Pointer)(to) = valueRegs.Ptrs[vStep.ireg]
 				case abiStepIntReg:
-					memmove(to, unsafe.Pointer(&valueRegs.Ints[vStep.ireg]), vStep.size)
+					memmove(to, valueRegs.IntRegArgAddr(vStep.ireg, vStep.size), vStep.size)
 				case abiStepFloatReg:
-					memmove(to, unsafe.Pointer(&valueRegs.Floats[vStep.freg]), vStep.size)
+					memmove(to, valueRegs.FloatRegArgAddr(vStep.freg, vStep.size), vStep.size)
 				default:
 					panic("unexpected value step")
 				}
@@ -1043,7 +1039,7 @@ func callMethod(ctxt *methodValue, frame unsafe.Pointer, retValid *bool, regs *a
 	methodFrameSize := methodFrameType.size
 	// TODO(mknyszek): Remove this when we no longer have
 	// caller reserved spill space.
-	methodFrameSize = align(methodFrameSize, ptrSize)
+	methodFrameSize = align(methodFrameSize, goarch.PtrSize)
 	methodFrameSize += methodABI.spill
 
 	// Mark pointers in registers for the return path.
diff --git a/src/runtime/alg.go b/src/runtime/alg.go
index 39c742684216362c48013b8ecfb1446a7ae45d1f..978a3b85dcb3ad3e44f956934a02f78273da075f 100644
--- a/src/runtime/alg.go
+++ b/src/runtime/alg.go
@@ -6,13 +6,13 @@ package runtime
 
 import (
 	"internal/cpu"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
 const (
-	c0 = uintptr((8-sys.PtrSize)/4*2860486313 + (sys.PtrSize-4)/4*33054211828000289)
-	c1 = uintptr((8-sys.PtrSize)/4*3267000013 + (sys.PtrSize-4)/4*23344194077549503)
+	c0 = uintptr((8-goarch.PtrSize)/4*2860486313 + (goarch.PtrSize-4)/4*33054211828000289)
+	c1 = uintptr((8-goarch.PtrSize)/4*3267000013 + (goarch.PtrSize-4)/4*23344194077549503)
 )
 
 func memhash0(p unsafe.Pointer, h uintptr) uintptr {
@@ -300,7 +300,7 @@ func ifaceHash(i interface {
 	return interhash(noescape(unsafe.Pointer(&i)), seed)
 }
 
-const hashRandomBytes = sys.PtrSize / 4 * 64
+const hashRandomBytes = goarch.PtrSize / 4 * 64
 
 // used in asm_{386,amd64,arm64}.s to seed the hash function
 var aeskeysched [hashRandomBytes]byte
@@ -321,7 +321,7 @@ func alginit() {
 		initAlgAES()
 		return
 	}
-	getRandomData((*[len(hashkey) * sys.PtrSize]byte)(unsafe.Pointer(&hashkey))[:])
+	getRandomData((*[len(hashkey) * goarch.PtrSize]byte)(unsafe.Pointer(&hashkey))[:])
 	hashkey[0] |= 1 // make sure these numbers are odd
 	hashkey[1] |= 1
 	hashkey[2] |= 1
@@ -337,7 +337,7 @@ func initAlgAES() {
 // Note: These routines perform the read with a native endianness.
 func readUnaligned32(p unsafe.Pointer) uint32 {
 	q := (*[4]byte)(p)
-	if sys.BigEndian {
+	if goarch.BigEndian {
 		return uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24
 	}
 	return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24
@@ -345,7 +345,7 @@ func readUnaligned32(p unsafe.Pointer) uint32 {
 
 func readUnaligned64(p unsafe.Pointer) uint64 {
 	q := (*[8]byte)(p)
-	if sys.BigEndian {
+	if goarch.BigEndian {
 		return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 |
 			uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56
 	}
diff --git a/src/runtime/asm.s b/src/runtime/asm.s
index 72c744925d89aec9d1cc33a6eacf55f826866fcf..0e14fcd3e6a3569f17357b31e3cefa4a142c0ae8 100644
--- a/src/runtime/asm.s
+++ b/src/runtime/asm.s
@@ -13,6 +13,6 @@ DATA runtime·no_pointers_stackmap+0x04(SB)/4, $0
 GLOBL runtime·no_pointers_stackmap(SB),RODATA, $8
 
 #ifndef GOARCH_amd64
-TEXT ·sigpanic0(SB),NOSPLIT,$0-0
+TEXT ·sigpanic0(SB),NOSPLIT,$0-0
 	JMP	·sigpanic(SB)
 #endif
diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s
index ec5ea58028bf0e5ad38b24792bd6d2fdaf1e9a4b..594cd5ed0d9592fad2a2fa38f71accd0b2ef6471 100644
--- a/src/runtime/asm_386.s
+++ b/src/runtime/asm_386.s
@@ -137,9 +137,6 @@ has_cpuid:
 	CMPL	AX, $0
 	JE	nocpuinfo
 
-	// Figure out how to serialize RDTSC.
-	// On Intel processors LFENCE is enough. AMD requires MFENCE.
-	// Don't know about the rest, so let's do MFENCE.
 	CMPL	BX, $0x756E6547  // "Genu"
 	JNE	notintel
 	CMPL	DX, $0x49656E69  // "ineI"
@@ -147,7 +144,6 @@ has_cpuid:
 	CMPL	CX, $0x6C65746E  // "ntel"
 	JNE	notintel
 	MOVB	$1, runtime·isIntel(SB)
-	MOVB	$1, runtime·lfenceBeforeRdtsc(SB)
 notintel:
 
 	// Load EAX=1 cpuid flags
@@ -244,10 +240,8 @@ ok:
 
 	// create a new goroutine to start program
 	PUSHL	$runtime·mainPC(SB)	// entry
-	PUSHL	$0	// arg size
 	CALL	runtime·newproc(SB)
 	POPL	AX
-	POPL	AX
 
 	// start this M
 	CALL	runtime·mstart(SB)
@@ -584,26 +578,6 @@ TEXT ·publicationBarrier(SB),NOSPLIT,$0-0
 	// compile barrier.
 	RET
 
-// void jmpdefer(fn, sp);
-// called from deferreturn.
-// 1. pop the caller
-// 2. sub 5 bytes (the length of CALL & a 32 bit displacement) from the callers
-//    return (when building for shared libraries, subtract 16 bytes -- 5 bytes
-//    for CALL & displacement to call __x86.get_pc_thunk.cx, 6 bytes for the
-//    LEAL to load the offset into BX, and finally 5 for the call & displacement)
-// 3. jmp to the argument
-TEXT runtime·jmpdefer(SB), NOSPLIT, $0-8
-	MOVL	fv+0(FP), DX	// fn
-	MOVL	argp+4(FP), BX	// caller sp
-	LEAL	-4(BX), SP	// caller sp after CALL
-#ifdef GOBUILDMODE_shared
-	SUBL	$16, (SP)	// return to CALL again
-#else
-	SUBL	$5, (SP)	// return to CALL again
-#endif
-	MOVL	0(DX), BX
-	JMP	BX	// but first run the deferred function
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -655,18 +629,18 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-12
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	get_tls(CX)
-	MOVL	g(CX), BP
-	CMPL	BP, $0
-	JEQ	nosave	// Don't even have a G yet.
-	MOVL	g_m(BP), BP
-	MOVL	m_g0(BP), SI
 	MOVL	g(CX), DI
-	CMPL	SI, DI
-	JEQ	noswitch
+	CMPL	DI, $0
+	JEQ	nosave	// Don't even have a G yet.
+	MOVL	g_m(DI), BP
 	CMPL	DI, m_gsignal(BP)
 	JEQ	noswitch
+	MOVL	m_g0(BP), SI
+	CMPL	DI, SI
+	JEQ	noswitch
 	CALL	gosave_systemstack_switch<>(SB)
 	get_tls(CX)
 	MOVL	SI, g(CX)
@@ -860,19 +834,37 @@ TEXT runtime·stackcheck(SB), NOSPLIT, $0-0
 
 // func cputicks() int64
 TEXT runtime·cputicks(SB),NOSPLIT,$0-8
-	CMPB	internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE	done
-	CMPB	runtime·lfenceBeforeRdtsc(SB), $1
-	JNE	mfence
-	LFENCE
-	JMP	done
-mfence:
-	MFENCE
+	// LFENCE/MFENCE instruction support is dependent on SSE2.
+	// When no SSE2 support is present do not enforce any serialization
+	// since using CPUID to serialize the instruction stream is
+	// very costly.
+#ifdef GO386_softfloat
+	JMP	rdtsc  // no fence instructions available
+#endif
+	CMPB	internal∕cpu·X86+const_offsetX86HasRDTSCP(SB), $1
+	JNE	fences
+	// Instruction stream serializing RDTSCP is supported.
+	// RDTSCP is supported by Intel Nehalem (2008) and
+	// AMD K8 Rev. F (2006) and newer.
+	RDTSCP
 done:
-	RDTSC
 	MOVL	AX, ret_lo+0(FP)
 	MOVL	DX, ret_hi+4(FP)
 	RET
+fences:
+	// MFENCE is instruction stream serializing and flushes the
+	// store buffers on AMD. The serialization semantics of LFENCE on AMD
+	// are dependent on MSR C001_1029 and CPU generation.
+	// LFENCE on Intel does wait for all previous instructions to have executed.
+	// Intel recommends MFENCE;LFENCE in its manuals before RDTSC to have all
+	// previous instructions executed and all previous loads and stores to globally visible.
+	// Using MFENCE;LFENCE here aligns the serializing properties without
+	// runtime detection of CPU manufacturer.
+	MFENCE
+	LFENCE
+rdtsc:
+	RDTSC
+	JMP done
 
 TEXT ldt0setup<>(SB),NOSPLIT,$16-0
 	// set up ldt 7 to point at m0.tls
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 14f29e19647aa2d991cf623592411129ac3da14b..3ab6060ec0c60819f528c186f97cb95d257e83a2 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -103,9 +103,6 @@ TEXT runtime·rt0_go(SB),NOSPLIT|TOPFRAME,$0
 	CMPL	AX, $0
 	JE	nocpuinfo
 
-	// Figure out how to serialize RDTSC.
-	// On Intel processors LFENCE is enough. AMD requires MFENCE.
-	// Don't know about the rest, so let's do MFENCE.
 	CMPL	BX, $0x756E6547  // "Genu"
 	JNE	notintel
 	CMPL	DX, $0x49656E69  // "ineI"
@@ -113,7 +110,6 @@ TEXT runtime·rt0_go(SB),NOSPLIT|TOPFRAME,$0
 	CMPL	CX, $0x6C65746E  // "ntel"
 	JNE	notintel
 	MOVB	$1, runtime·isIntel(SB)
-	MOVB	$1, runtime·lfenceBeforeRdtsc(SB)
 notintel:
 
 	// Load EAX=1 cpuid flags
@@ -214,10 +210,8 @@ ok:
 	// create a new goroutine to start program
 	MOVQ	$runtime·mainPC(SB), AX		// entry
 	PUSHQ	AX
-	PUSHQ	$0			// arg size
 	CALL	runtime·newproc(SB)
 	POPQ	AX
-	POPQ	AX
 
 	// start this M
 	CALL	runtime·mstart(SB)
@@ -279,7 +273,6 @@ TEXT gogo<>(SB), NOSPLIT, $0
 // Switch to m->g0's stack, call fn(g).
 // Fn must never return. It should gogo(&g->sched)
 // to keep running g.
-#ifdef GOEXPERIMENT_regabiargs
 TEXT runtime·mcall(SB), NOSPLIT, $0-8
 	MOVQ	AX, DX	// DX = fn
 
@@ -308,38 +301,6 @@ goodm:
 	POPQ	AX
 	JMP	runtime·badmcall2(SB)
 	RET
-#else
-TEXT runtime·mcall(SB), NOSPLIT, $0-8
-	MOVQ	fn+0(FP), DI
-
-	get_tls(CX)
-	MOVQ	g(CX), AX	// save state in g->sched
-	MOVQ	0(SP), BX	// caller's PC
-	MOVQ	BX, (g_sched+gobuf_pc)(AX)
-	LEAQ	fn+0(FP), BX	// caller's SP
-	MOVQ	BX, (g_sched+gobuf_sp)(AX)
-	MOVQ	BP, (g_sched+gobuf_bp)(AX)
-
-	// switch to m->g0 & its stack, call fn
-	MOVQ	g(CX), BX
-	MOVQ	g_m(BX), BX
-	MOVQ	m_g0(BX), SI
-	CMPQ	SI, AX	// if g == m->g0 call badmcall
-	JNE	3(PC)
-	MOVQ	$runtime·badmcall(SB), AX
-	JMP	AX
-	MOVQ	SI, g(CX)	// g = m->g0
-	MOVQ	SI, R14	// set the g register
-	MOVQ	(g_sched+gobuf_sp)(SI), SP	// sp = m->g0->sched.sp
-	PUSHQ	AX
-	MOVQ	DI, DX
-	MOVQ	0(DI), DI
-	CALL	DI
-	POPQ	AX
-	MOVQ	$runtime·badmcall2(SB), AX
-	JMP	AX
-	RET
-#endif
 
 // systemstack_switch is a dummy routine that systemstack leaves at the bottom
 // of the G stack. We need to distinguish the routine that
@@ -467,9 +428,8 @@ TEXT runtime·morestack_noctxt(SB),NOSPLIT,$0
 	MOVL	$0, DX
 	JMP	runtime·morestack(SB)
 
-#ifdef GOEXPERIMENT_regabireflect
 // spillArgs stores return values from registers to a *internal/abi.RegArgs in R12.
-TEXT ·spillArgs(SB),NOSPLIT,$0-0
+TEXT ·spillArgs(SB),NOSPLIT,$0-0
 	MOVQ AX, 0(R12)
 	MOVQ BX, 8(R12)
 	MOVQ CX, 16(R12)
@@ -497,7 +457,7 @@ TEXT ·spillArgs(SB),NOSPLIT,$0-0
 	RET
 
 // unspillArgs loads args into registers from a *internal/abi.RegArgs in R12.
-TEXT ·unspillArgs(SB),NOSPLIT,$0-0
+TEXT ·unspillArgs(SB),NOSPLIT,$0-0
 	MOVQ 0(R12), AX
 	MOVQ 8(R12), BX
 	MOVQ 16(R12), CX
@@ -523,15 +483,6 @@ TEXT ·unspillArgs(SB),NOSPLIT,$0-0
 	MOVQ 176(R12), X13
 	MOVQ 184(R12), X14
 	RET
-#else
-// spillArgs stores return values from registers to a pointer in R12.
-TEXT ·spillArgs(SB),NOSPLIT,$0-0
-	RET
-
-// unspillArgs loads args into registers from a pointer in R12.
-TEXT ·unspillArgs(SB),NOSPLIT,$0-0
-	RET
-#endif
 
 // reflectcall: call a function with the given argument list
 // func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
@@ -588,7 +539,7 @@ TEXT NAME(SB), WRAPPER, $MAXSIZE-48;		\
 	REP;MOVSB;				\
 	/* set up argument registers */		\
 	MOVQ    regArgs+40(FP), R12;		\
-	CALL    ·unspillArgs(SB);		\
+	CALL    ·unspillArgs(SB);		\
 	/* call function */			\
 	MOVQ	f+8(FP), DX;			\
 	PCDATA  $PCDATA_StackMapIndex, $0;	\
@@ -596,7 +547,7 @@ TEXT NAME(SB), WRAPPER, $MAXSIZE-48;		\
 	CALL	R12;				\
 	/* copy register return values back */		\
 	MOVQ    regArgs+40(FP), R12;		\
-	CALL    ·spillArgs(SB);		\
+	CALL    ·spillArgs(SB);		\
 	MOVLQZX	stackArgsSize+24(FP), CX;		\
 	MOVLQZX	stackRetOffset+28(FP), BX;		\
 	MOVQ	stackArgs+16(FP), DI;		\
@@ -664,31 +615,12 @@ TEXT ·publicationBarrier(SB),NOSPLIT,$0-0
 	// compile barrier.
 	RET
 
-// func jmpdefer(fv *funcval, argp uintptr)
-// argp is a caller SP.
-// called from deferreturn.
-// 1. pop the caller
-// 2. sub 5 bytes from the callers return
-// 3. jmp to the argument
-TEXT runtime·jmpdefer(SB), NOSPLIT, $0-16
-	MOVQ	fv+0(FP), DX	// fn
-	MOVQ	argp+8(FP), BX	// caller sp
-	LEAQ	-8(BX), SP	// caller sp after CALL
-	MOVQ	-8(SP), BP	// restore BP as if deferreturn returned (harmless if framepointers not in use)
-	SUBQ	$5, (SP)	// return to CALL again
-	MOVQ	0(DX), BX
-	JMP	BX	// but first run the deferred function
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
 // or else unwinding from systemstack_switch is incorrect.
 // Smashes R9.
 TEXT gosave_systemstack_switch<>(SB),NOSPLIT,$0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R14)
-	MOVQ	g(R14), R14
-#endif
 	MOVQ	$runtime·systemstack_switch(SB), R9
 	MOVQ	R9, (g_sched+gobuf_pc)(R14)
 	LEAQ	8(SP), R9
@@ -731,22 +663,21 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-20
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	get_tls(CX)
-	MOVQ	g(CX), R8
-	CMPQ	R8, $0
-	JEQ	nosave
-	MOVQ	g_m(R8), R8
-	MOVQ	m_g0(R8), SI
 	MOVQ	g(CX), DI
-	CMPQ	SI, DI
+	CMPQ	DI, $0
 	JEQ	nosave
+	MOVQ	g_m(DI), R8
 	MOVQ	m_gsignal(R8), SI
-	CMPQ	SI, DI
+	CMPQ	DI, SI
+	JEQ	nosave
+	MOVQ	m_g0(R8), SI
+	CMPQ	DI, SI
 	JEQ	nosave
 
 	// Switch to system stack.
-	MOVQ	m_g0(R8), SI
 	CALL	gosave_systemstack_switch<>(SB)
 	MOVQ	SI, g(CX)
 	MOVQ	(g_sched+gobuf_sp)(SI), SP
@@ -993,77 +924,62 @@ TEXT runtime·stackcheck(SB), NOSPLIT, $0-0
 
 // func cputicks() int64
 TEXT runtime·cputicks(SB),NOSPLIT,$0-0
-	CMPB	runtime·lfenceBeforeRdtsc(SB), $1
-	JNE	mfence
-	LFENCE
-	JMP	done
-mfence:
-	MFENCE
+	CMPB	internal∕cpu·X86+const_offsetX86HasRDTSCP(SB), $1
+	JNE	fences
+	// Instruction stream serializing RDTSCP is supported.
+	// RDTSCP is supported by Intel Nehalem (2008) and
+	// AMD K8 Rev. F (2006) and newer.
+	RDTSCP
 done:
-	RDTSC
 	SHLQ	$32, DX
 	ADDQ	DX, AX
 	MOVQ	AX, ret+0(FP)
 	RET
+fences:
+	// MFENCE is instruction stream serializing and flushes the
+	// store buffers on AMD. The serialization semantics of LFENCE on AMD
+	// are dependent on MSR C001_1029 and CPU generation.
+	// LFENCE on Intel does wait for all previous instructions to have executed.
+	// Intel recommends MFENCE;LFENCE in its manuals before RDTSC to have all
+	// previous instructions executed and all previous loads and stores to globally visible.
+	// Using MFENCE;LFENCE here aligns the serializing properties without
+	// runtime detection of CPU manufacturer.
+	MFENCE
+	LFENCE
+	RDTSC
+	JMP done
 
 // func memhash(p unsafe.Pointer, h, s uintptr) uintptr
 // hash function using AES hardware instructions
 TEXT runtime·memhash(SB),NOSPLIT,$0-32
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
 	// CX = size
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	s+16(FP), CX	// size
-	LEAQ	ret+24(FP), DX
-#endif
 	JMP	aeshashbody<>(SB)
 noaes:
 	JMP	runtime·memhashFallback(SB)
 
 // func strhash(p unsafe.Pointer, h uintptr) uintptr
 TEXT runtime·strhash(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to string struct
 	// BX = seed
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	p+0(FP), AX	// ptr to string struct
-#endif
 	MOVQ	8(AX), CX	// length of string
 	MOVQ	(AX), AX	// string data
-#ifndef GOEXPERIMENT_regabiargs
-	LEAQ	ret+16(FP), DX
-#endif
 	JMP	aeshashbody<>(SB)
 noaes:
 	JMP	runtime·strhashFallback(SB)
 
 // AX: data
-#ifdef GOEXPERIMENT_regabiargs
 // BX: hash seed
-#else
-// h+8(FP): hash seed
-#endif
 // CX: length
-#ifdef GOEXPERIMENT_regabiargs
 // At return: AX = return value
-#else
-// DX: address to put return value
-#endif
 TEXT aeshashbody<>(SB),NOSPLIT,$0-0
 	// Fill an SSE register with our seeds.
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0				// 64 bits of per-table hash seed
-#else
-	MOVQ	h+8(FP), X0			// 64 bits of per-table hash seed
-#endif
 	PINSRW	$4, CX, X0			// 16 bits of length
 	PSHUFHW $0, X0, X0			// repeat length 4 times total
 	MOVO	X0, X1				// save unscrambled seed
@@ -1100,11 +1016,7 @@ final1:
 	AESENC	X1, X1	// scramble combo 3 times
 	AESENC	X1, X1
 	AESENC	X1, X1
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X1, AX	// return X1
-#else
-	MOVQ	X1, (DX)
-#endif
 	RET
 
 endofpage:
@@ -1120,11 +1032,7 @@ endofpage:
 aes0:
 	// Return scrambled input seed
 	AESENC	X0, X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, (DX)
-#endif
 	RET
 
 aes16:
@@ -1154,11 +1062,7 @@ aes17to32:
 
 	// combine results
 	PXOR	X3, X2
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X2, AX	// return X2
-#else
-	MOVQ	X2, (DX)
-#endif
 	RET
 
 aes33to64:
@@ -1200,11 +1104,7 @@ aes33to64:
 	PXOR	X6, X4
 	PXOR	X7, X5
 	PXOR	X5, X4
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X4, AX	// return X4
-#else
-	MOVQ	X4, (DX)
-#endif
 	RET
 
 aes65to128:
@@ -1286,15 +1186,9 @@ aes65to128:
 	PXOR	X10, X8
 	PXOR	X11, X9
 	PXOR	X9, X8
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
-#else
-	MOVQ	X8, (DX)
-#endif
 	RET
 
 aes129plus:
@@ -1410,41 +1304,24 @@ aesloop:
 	PXOR	X10, X8
 	PXOR	X11, X9
 	PXOR	X9, X8
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
-#else
-	MOVQ	X8, (DX)
-#endif
 	RET
 
 // func memhash32(p unsafe.Pointer, h uintptr) uintptr
 // ABIInternal for performance.
 TEXT runtime·memhash32(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0	// X0 = seed
-#else
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	h+8(FP), X0	// seed
-#endif
 	PINSRD	$2, (AX), X0	// data
 	AESENC	runtime·aeskeysched+0(SB), X0
 	AESENC	runtime·aeskeysched+16(SB), X0
 	AESENC	runtime·aeskeysched+32(SB), X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, ret+16(FP)
-#endif
 	RET
 noaes:
 	JMP	runtime·memhash32Fallback(SB)
@@ -1452,28 +1329,16 @@ noaes:
 // func memhash64(p unsafe.Pointer, h uintptr) uintptr
 // ABIInternal for performance.
 TEXT runtime·memhash64(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
-#else
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0	// X0 = seed
-#else
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	h+8(FP), X0	// seed
-#endif
 	PINSRQ	$1, (AX), X0	// data
 	AESENC	runtime·aeskeysched+0(SB), X0
 	AESENC	runtime·aeskeysched+16(SB), X0
 	AESENC	runtime·aeskeysched+32(SB), X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, ret+16(FP)
-#endif
 	RET
 noaes:
 	JMP	runtime·memhash64Fallback(SB)
@@ -1596,10 +1461,10 @@ TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0
 // This function is injected from the signal handler for panicking
 // signals. It is quite painful to set X15 in the signal context,
 // so we do it here.
-TEXT ·sigpanic0(SB),NOSPLIT,$0-0
-#ifdef GOEXPERIMENT_regabig
+TEXT ·sigpanic0(SB),NOSPLIT,$0-0
 	get_tls(R14)
 	MOVQ	g(R14), R14
+#ifndef GOOS_plan9
 	XORPS	X15, X15
 #endif
 	JMP	·sigpanic(SB)
@@ -1619,13 +1484,7 @@ TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$112
 	MOVQ	R13, 104(SP)
 	// TODO: Consider passing g.m.p in as an argument so they can be shared
 	// across a sequence of write barriers.
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), R13
-#else
-	get_tls(R13)
-	MOVQ	g(R13), R13
-	MOVQ	g_m(R13), R13
-#endif
 	MOVQ	m_p(R13), R13
 	MOVQ	(p_wbBuf+wbBuf_next)(R13), R12
 	// Increment wbBuf.next position.
@@ -1956,146 +1815,61 @@ TEXT runtime·debugCallPanicked(SB),NOSPLIT,$16-16
 // The tail call makes these stubs disappear in backtraces.
 // Defined as ABIInternal since they do not use the stack-based Go ABI.
 TEXT runtime·panicIndex(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndex(SB)
 TEXT runtime·panicIndexU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndexU(SB)
 TEXT runtime·panicSliceAlen(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlen(SB)
 TEXT runtime·panicSliceAlenU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlenU(SB)
 TEXT runtime·panicSliceAcap(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcap(SB)
 TEXT runtime·panicSliceAcapU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcapU(SB)
 TEXT runtime·panicSliceB(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceB(SB)
 TEXT runtime·panicSliceBU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceBU(SB)
 TEXT runtime·panicSlice3Alen(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Alen(SB)
 TEXT runtime·panicSlice3AlenU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AlenU(SB)
 TEXT runtime·panicSlice3Acap(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Acap(SB)
 TEXT runtime·panicSlice3AcapU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AcapU(SB)
 TEXT runtime·panicSlice3B(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3B(SB)
 TEXT runtime·panicSlice3BU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3BU(SB)
 TEXT runtime·panicSlice3C(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3C(SB)
 TEXT runtime·panicSlice3CU(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3CU(SB)
 TEXT runtime·panicSliceConvert(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceConvert(SB)
 
 #ifdef GOOS_android
diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s
index 6d3573d68fb0ef3b90462220cc36bd502090ef58..b47184e36bc9801e1c2c2080b9a9ef629122304a 100644
--- a/src/runtime/asm_arm.s
+++ b/src/runtime/asm_arm.s
@@ -168,14 +168,13 @@ TEXT runtime·rt0_go(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
 	BL	runtime·schedinit(SB)
 
 	// create a new goroutine to start program
+	SUB	$8, R13
 	MOVW	$runtime·mainPC(SB), R0
-	MOVW.W	R0, -4(R13)
-	MOVW	$8, R0
-	MOVW.W	R0, -4(R13)
+	MOVW	R0, 4(R13)	// arg 1: fn
 	MOVW	$0, R0
-	MOVW.W	R0, -4(R13)	// push $0 as guard
+	MOVW	R0, 0(R13)	// dummy LR
 	BL	runtime·newproc(SB)
-	MOVW	$12(R13), R13	// pop args and LR
+	ADD	$8, R13	// pop args and LR
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -507,20 +506,6 @@ CALLFN(·call268435456, 268435456)
 CALLFN(·call536870912, 536870912)
 CALLFN(·call1073741824, 1073741824)
 
-// void jmpdefer(fn, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 4 bytes to get back to BL deferreturn
-// 3. B to fn
-TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
-	MOVW	0(R13), LR
-	MOVW	$-4(LR), LR	// BL deferreturn
-	MOVW	fv+0(FP), R7
-	MOVW	argp+4(FP), R13
-	MOVW	$-4(R13), R13	// SP is 4 below argp, due to saved LR
-	MOVW	0(R7), R1
-	B	(R1)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -571,7 +556,8 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-12
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOVW	g_m(g), R8
 	MOVW	m_gsignal(R8), R3
 	CMP	R3, g
diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s
index 2d495397a8d0aea274a68290fe24584141f202b7..8cbd17fa7506df985bfc59cf25c411a9bfc6ee6e 100644
--- a/src/runtime/asm_arm64.s
+++ b/src/runtime/asm_arm64.s
@@ -87,14 +87,11 @@ nocgo:
 
 	// create a new goroutine to start program
 	MOVD	$runtime·mainPC(SB), R0		// entry
-	MOVD	RSP, R7
-	MOVD.W	$0, -8(R7)
-	MOVD.W	R0, -8(R7)
-	MOVD.W	$0, -8(R7)
-	MOVD.W	$0, -8(R7)
-	MOVD	R7, RSP
+	SUB	$16, RSP
+	MOVD	R0, 8(RSP) // arg
+	MOVD	$0, 0(RSP) // dummy LR
 	BL	runtime·newproc(SB)
-	ADD	$32, RSP
+	ADD	$16, RSP
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -103,7 +100,7 @@ nocgo:
 	MOVD	R0, (R0)	// boom
 	UNDEF
 
-DATA	runtime·mainPC+0(SB)/8,$runtime·main(SB)
+DATA	runtime·mainPC+0(SB)/8,$runtime·main(SB)
 GLOBL	runtime·mainPC(SB),RODATA,$8
 
 TEXT runtime·breakpoint(SB),NOSPLIT|NOFRAME,$0-0
@@ -152,7 +149,13 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 // Switch to m->g0's stack, call fn(g).
 // Fn must never return. It should gogo(&g->sched)
 // to keep running g.
-TEXT runtime·mcall(SB), NOSPLIT|NOFRAME, $0-8
+TEXT runtime·mcall(SB), NOSPLIT|NOFRAME, $0-8
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R0, R26				// context
+#else
+	MOVD	fn+0(FP), R26			// context
+#endif
+
 	// Save caller state in g->sched
 	MOVD	RSP, R0
 	MOVD	R0, (g_sched+gobuf_sp)(g)
@@ -168,14 +171,18 @@ TEXT runtime·mcall(SB), NOSPLIT|NOFRAME, $0-8
 	CMP	g, R3
 	BNE	2(PC)
 	B	runtime·badmcall(SB)
-	MOVD	fn+0(FP), R26			// context
-	MOVD	0(R26), R4			// code pointer
+
 	MOVD	(g_sched+gobuf_sp)(g), R0
 	MOVD	R0, RSP	// sp = m->g0->sched.sp
 	MOVD	(g_sched+gobuf_bp)(g), R29
-	MOVD	R3, -8(RSP)
-	MOVD	$0, -16(RSP)
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R3, R0				// arg = g
+#else
+	MOVD	R3, -8(RSP)			// arg = g
+#endif
+	MOVD	$0, -16(RSP)			// dummy LR
 	SUB	$16, RSP
+	MOVD	0(R26), R4			// code pointer
 	BL	(R4)
 	B	runtime·badmcall2(SB)
 
@@ -310,6 +317,86 @@ TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVW	$0, R26
 	B runtime·morestack(SB)
 
+#ifdef GOEXPERIMENT_regabireflect
+// spillArgs stores return values from registers to a *internal/abi.RegArgs in R20.
+TEXT ·spillArgs(SB),NOSPLIT,$0-0
+	MOVD	R0, (0*8)(R20)
+	MOVD	R1, (1*8)(R20)
+	MOVD	R2, (2*8)(R20)
+	MOVD	R3, (3*8)(R20)
+	MOVD	R4, (4*8)(R20)
+	MOVD	R5, (5*8)(R20)
+	MOVD	R6, (6*8)(R20)
+	MOVD	R7, (7*8)(R20)
+	MOVD	R8, (8*8)(R20)
+	MOVD	R9, (9*8)(R20)
+	MOVD	R10, (10*8)(R20)
+	MOVD	R11, (11*8)(R20)
+	MOVD	R12, (12*8)(R20)
+	MOVD	R13, (13*8)(R20)
+	MOVD	R14, (14*8)(R20)
+	MOVD	R15, (15*8)(R20)
+	FMOVD	F0, (16*8)(R20)
+	FMOVD	F1, (17*8)(R20)
+	FMOVD	F2, (18*8)(R20)
+	FMOVD	F3, (19*8)(R20)
+	FMOVD	F4, (20*8)(R20)
+	FMOVD	F5, (21*8)(R20)
+	FMOVD	F6, (22*8)(R20)
+	FMOVD	F7, (23*8)(R20)
+	FMOVD	F8, (24*8)(R20)
+	FMOVD	F9, (25*8)(R20)
+	FMOVD	F10, (26*8)(R20)
+	FMOVD	F11, (27*8)(R20)
+	FMOVD	F12, (28*8)(R20)
+	FMOVD	F13, (29*8)(R20)
+	FMOVD	F14, (30*8)(R20)
+	FMOVD	F15, (31*8)(R20)
+	RET
+
+// unspillArgs loads args into registers from a *internal/abi.RegArgs in R20.
+TEXT ·unspillArgs(SB),NOSPLIT,$0-0
+	MOVD	(0*8)(R20), R0
+	MOVD	(1*8)(R20), R1
+	MOVD	(2*8)(R20), R2
+	MOVD	(3*8)(R20), R3
+	MOVD	(4*8)(R20), R4
+	MOVD	(5*8)(R20), R5
+	MOVD	(6*8)(R20), R6
+	MOVD	(7*8)(R20), R7
+	MOVD	(8*8)(R20), R8
+	MOVD	(9*8)(R20), R9
+	MOVD	(10*8)(R20), R10
+	MOVD	(11*8)(R20), R11
+	MOVD	(12*8)(R20), R12
+	MOVD	(13*8)(R20), R13
+	MOVD	(14*8)(R20), R14
+	MOVD	(15*8)(R20), R15
+	FMOVD	(16*8)(R20), F0
+	FMOVD	(17*8)(R20), F1
+	FMOVD	(18*8)(R20), F2
+	FMOVD	(19*8)(R20), F3
+	FMOVD	(20*8)(R20), F4
+	FMOVD	(21*8)(R20), F5
+	FMOVD	(22*8)(R20), F6
+	FMOVD	(23*8)(R20), F7
+	FMOVD	(24*8)(R20), F8
+	FMOVD	(25*8)(R20), F9
+	FMOVD	(26*8)(R20), F10
+	FMOVD	(27*8)(R20), F11
+	FMOVD	(28*8)(R20), F12
+	FMOVD	(29*8)(R20), F13
+	FMOVD	(30*8)(R20), F14
+	FMOVD	(31*8)(R20), F15
+	RET
+#else
+TEXT ·spillArgs(SB),NOSPLIT,$0-0
+	RET
+
+TEXT ·unspillArgs(SB),NOSPLIT,$0-0
+	RET
+#endif
+
 // reflectcall: call a function with the given argument list
 // func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
 // we don't have variable-sized frames, so we use a small number
@@ -381,12 +468,17 @@ TEXT NAME(SB), WRAPPER, $MAXSIZE-48;		\
 	MOVBU.P	R7, 1(R5);			\
 	CMP	R5, R6;				\
 	BNE	-3(PC);				\
+	/* set up argument registers */		\
+	MOVD	regArgs+40(FP), R20;		\
+	CALL	·unspillArgs(SB);		\
 	/* call function */			\
 	MOVD	f+8(FP), R26;			\
-	MOVD	(R26), R0;			\
-	PCDATA  $PCDATA_StackMapIndex, $0;	\
-	BL	(R0);				\
+	MOVD	(R26), R20;			\
+	PCDATA	$PCDATA_StackMapIndex, $0;	\
+	BL	(R20);				\
 	/* copy return values back */		\
+	MOVD	regArgs+40(FP), R20;		\
+	CALL	·spillArgs(SB);		\
 	MOVD	stackArgsType+0(FP), R7;		\
 	MOVD	stackArgs+16(FP), R3;			\
 	MOVWU	stackArgsSize+24(FP), R4;			\
@@ -403,11 +495,12 @@ TEXT NAME(SB), WRAPPER, $MAXSIZE-48;		\
 // to reflectcallmove. It does not follow the Go ABI; it expects its
 // arguments in registers.
 TEXT callRet<>(SB), NOSPLIT, $48-0
+	NO_LOCAL_POINTERS
 	MOVD	R7, 8(RSP)
 	MOVD	R3, 16(RSP)
 	MOVD	R5, 24(RSP)
 	MOVD	R4, 32(RSP)
-	MOVD	$0, 40(RSP)
+	MOVD	R20, 40(RSP)
 	BL	runtime·reflectcallmove(SB)
 	RET
 
@@ -440,12 +533,14 @@ CALLFN(·call536870912, 536870912)
 CALLFN(·call1073741824, 1073741824)
 
 // func memhash32(p unsafe.Pointer, h uintptr) uintptr
-TEXT runtime·memhash32(SB),NOSPLIT|NOFRAME,$0-24
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
+TEXT runtime·memhash32(SB),NOSPLIT|NOFRAME,$0-24
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	p+0(FP), R0
 	MOVD	h+8(FP), R1
 	MOVD	$ret+16(FP), R2
+#endif
 	MOVD	$runtime·aeskeysched+0(SB), R3
 
 	VEOR	V0.B16, V0.B16, V0.B16
@@ -459,18 +554,24 @@ TEXT runtime·memhash32(SB),NOSPLIT|NOFRAME,$0-24
 	AESMC	V0.B16, V0.B16
 	AESE	V2.B16, V0.B16
 
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
 	VST1	[V0.D1], (R2)
+#endif
 	RET
 noaes:
-	B	runtime·memhash32Fallback(SB)
+	B	runtime·memhash32Fallback(SB)
 
 // func memhash64(p unsafe.Pointer, h uintptr) uintptr
-TEXT runtime·memhash64(SB),NOSPLIT|NOFRAME,$0-24
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
+TEXT runtime·memhash64(SB),NOSPLIT|NOFRAME,$0-24
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	p+0(FP), R0
 	MOVD	h+8(FP), R1
 	MOVD	$ret+16(FP), R2
+#endif
 	MOVD	$runtime·aeskeysched+0(SB), R3
 
 	VEOR	V0.B16, V0.B16, V0.B16
@@ -484,75 +585,89 @@ TEXT runtime·memhash64(SB),NOSPLIT|NOFRAME,$0-24
 	AESMC	V0.B16, V0.B16
 	AESE	V2.B16, V0.B16
 
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
 	VST1	[V0.D1], (R2)
+#endif
 	RET
 noaes:
-	B	runtime·memhash64Fallback(SB)
+	B	runtime·memhash64Fallback(SB)
 
 // func memhash(p unsafe.Pointer, h, size uintptr) uintptr
-TEXT runtime·memhash(SB),NOSPLIT|NOFRAME,$0-32
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
+TEXT runtime·memhash(SB),NOSPLIT|NOFRAME,$0-32
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	p+0(FP), R0
-	MOVD	s+16(FP), R1
-	MOVD	h+8(FP), R3
-	MOVD	$ret+24(FP), R2
+	MOVD	h+8(FP), R1
+	MOVD	s+16(FP), R2
+	MOVD	$ret+24(FP), R8
+#endif
 	B	aeshashbody<>(SB)
 noaes:
-	B	runtime·memhashFallback(SB)
+	B	runtime·memhashFallback(SB)
 
 // func strhash(p unsafe.Pointer, h uintptr) uintptr
-TEXT runtime·strhash(SB),NOSPLIT|NOFRAME,$0-24
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
-	MOVD	p+0(FP), R10 // string pointer
-	LDP	(R10), (R0, R1) //string data/ length
-	MOVD	h+8(FP), R3
-	MOVD	$ret+16(FP), R2 // return adddress
+TEXT runtime·strhash(SB),NOSPLIT|NOFRAME,$0-24
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifdef GOEXPERIMENT_regabiargs
+	LDP	(R0), (R0, R2)	// string data / length
+#else
+	MOVD	p+0(FP), R10	// string pointer
+	LDP	(R10), (R0, R2)	// string data / length
+	MOVD	h+8(FP), R1
+	MOVD	$ret+16(FP), R8	// return adddress
+#endif
 	B	aeshashbody<>(SB)
 noaes:
-	B	runtime·strhashFallback(SB)
+	B	runtime·strhashFallback(SB)
 
 // R0: data
-// R1: length
-// R2: address to put return value
-// R3: seed data
+// R1: seed data
+// R2: length
+#ifdef GOEXPERIMENT_regabiargs
+// At return, R0 = return value
+#else
+// R8: address to put return value
+#endif
 TEXT aeshashbody<>(SB),NOSPLIT|NOFRAME,$0
 	VEOR	V30.B16, V30.B16, V30.B16
-	VMOV	R3, V30.D[0]
-	VMOV	R1, V30.D[1] // load length into seed
+	VMOV	R1, V30.D[0]
+	VMOV	R2, V30.D[1] // load length into seed
 
 	MOVD	$runtime·aeskeysched+0(SB), R4
 	VLD1.P	16(R4), [V0.B16]
 	AESE	V30.B16, V0.B16
 	AESMC	V0.B16, V0.B16
-	CMP	$16, R1
+	CMP	$16, R2
 	BLO	aes0to15
 	BEQ	aes16
-	CMP	$32, R1
+	CMP	$32, R2
 	BLS	aes17to32
-	CMP	$64, R1
+	CMP	$64, R2
 	BLS	aes33to64
-	CMP	$128, R1
+	CMP	$128, R2
 	BLS	aes65to128
 	B	aes129plus
 
 aes0to15:
-	CBZ	R1, aes0
+	CBZ	R2, aes0
 	VEOR	V2.B16, V2.B16, V2.B16
-	TBZ	$3, R1, less_than_8
+	TBZ	$3, R2, less_than_8
 	VLD1.P	8(R0), V2.D[0]
 
 less_than_8:
-	TBZ	$2, R1, less_than_4
+	TBZ	$2, R2, less_than_4
 	VLD1.P	4(R0), V2.S[2]
 
 less_than_4:
-	TBZ	$1, R1, less_than_2
+	TBZ	$1, R2, less_than_2
 	VLD1.P	2(R0), V2.H[6]
 
 less_than_2:
-	TBZ	$0, R1, done
+	TBZ	$0, R2, done
 	VLD1	(R0), V2.B[14]
 done:
 	AESE	V0.B16, V2.B16
@@ -561,11 +676,21 @@ done:
 	AESMC	V2.B16, V2.B16
 	AESE	V0.B16, V2.B16
 
-	VST1	[V2.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V2.D[0], R0
+#else
+	VST1	[V2.D1], (R8)
+#endif
 	RET
+
 aes0:
-	VST1	[V0.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
+	VST1	[V0.D1], (R8)
+#endif
 	RET
+
 aes16:
 	VLD1	(R0), [V2.B16]
 	B	done
@@ -575,7 +700,7 @@ aes17to32:
 	VLD1	(R4), [V1.B16]
 	AESE	V30.B16, V1.B16
 	AESMC	V1.B16, V1.B16
-	SUB	$16, R1, R10
+	SUB	$16, R2, R10
 	VLD1.P	(R0)(R10), [V2.B16]
 	VLD1	(R0), [V3.B16]
 
@@ -593,7 +718,11 @@ aes17to32:
 	AESE	V1.B16, V3.B16
 
 	VEOR	V3.B16, V2.B16, V2.B16
-	VST1	[V2.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V2.D[0], R0
+#else
+	VST1	[V2.D1], (R8)
+#endif
 	RET
 
 aes33to64:
@@ -604,7 +733,7 @@ aes33to64:
 	AESMC	V2.B16, V2.B16
 	AESE	V30.B16, V3.B16
 	AESMC	V3.B16, V3.B16
-	SUB	$32, R1, R10
+	SUB	$32, R2, R10
 
 	VLD1.P	(R0)(R10), [V4.B16, V5.B16]
 	VLD1	(R0), [V6.B16, V7.B16]
@@ -636,7 +765,11 @@ aes33to64:
 	VEOR	V7.B16, V5.B16, V5.B16
 	VEOR	V5.B16, V4.B16, V4.B16
 
-	VST1	[V4.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V4.D[0], R0
+#else
+	VST1	[V4.D1], (R8)
+#endif
 	RET
 
 aes65to128:
@@ -657,7 +790,7 @@ aes65to128:
 	AESE	V30.B16, V7.B16
 	AESMC	V7.B16, V7.B16
 
-	SUB	$64, R1, R10
+	SUB	$64, R2, R10
 	VLD1.P	(R0)(R10), [V8.B16, V9.B16, V10.B16, V11.B16]
 	VLD1	(R0), [V12.B16, V13.B16, V14.B16, V15.B16]
 	AESE	V0.B16,	 V8.B16
@@ -711,7 +844,11 @@ aes65to128:
 	VEOR	V11.B16, V9.B16, V9.B16
 	VEOR	V9.B16, V8.B16, V8.B16
 
-	VST1	[V8.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V8.D[0], R0
+#else
+	VST1	[V8.D1], (R8)
+#endif
 	RET
 
 aes129plus:
@@ -732,12 +869,12 @@ aes129plus:
 	AESMC	V6.B16, V6.B16
 	AESE	V30.B16, V7.B16
 	AESMC	V7.B16, V7.B16
-	ADD	R0, R1, R10
+	ADD	R0, R2, R10
 	SUB	$128, R10, R10
 	VLD1.P	64(R10), [V8.B16, V9.B16, V10.B16, V11.B16]
 	VLD1	(R10), [V12.B16, V13.B16, V14.B16, V15.B16]
-	SUB	$1, R1, R1
-	LSR	$7, R1, R1
+	SUB	$1, R2, R2
+	LSR	$7, R2, R2
 
 aesloop:
 	AESE	V8.B16,	 V0.B16
@@ -776,8 +913,8 @@ aesloop:
 	AESMC	V6.B16,  V6.B16
 	AESE	V15.B16, V7.B16
 	AESMC	V7.B16,  V7.B16
-	SUB	$1, R1, R1
-	CBNZ	R1, aesloop
+	SUB	$1, R2, R2
+	CBNZ	R2, aesloop
 
 	AESE	V8.B16,	 V0.B16
 	AESMC	V0.B16,  V0.B16
@@ -830,7 +967,11 @@ aesloop:
 	VEOR	V4.B16, V6.B16, V4.B16
 	VEOR	V4.B16, V0.B16, V0.B16
 
-	VST1	[V0.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
+	VST1	[V0.D1], (R8)
+#endif
 	RET
 
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
@@ -841,23 +982,6 @@ again:
 	CBNZ	R0, again
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 4 bytes to get back to BL deferreturn
-// 3. BR to fn
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOVD	0(RSP), R0
-	SUB	$4, R0
-	MOVD	R0, LR
-
-	MOVD	fv+0(FP), R26
-	MOVD	argp+8(FP), R0
-	MOVD	R0, RSP
-	SUB	$8, RSP
-	MOVD	0(R26), R3
-	B	(R3)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -903,7 +1027,8 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-20
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOVD	g_m(g), R8
 	MOVD	m_gsignal(R8), R3
 	CMP	R3, g
@@ -1052,7 +1177,8 @@ havem:
 	MOVD	R1, 8(RSP)
 	MOVD	R2, 16(RSP)
 	MOVD	R3, 24(RSP)
-	BL	runtime·cgocallbackg(SB)
+	MOVD	$runtime·cgocallbackg(SB), R0
+	CALL	(R0) // indirect call to bypass nosplit check. We're on a different stack now.
 
 	// Restore g->sched (== m->curg->sched) from saved values.
 	MOVD	0(RSP), R5
@@ -1158,7 +1284,10 @@ TEXT ·checkASM(SB),NOSPLIT,$0-1
 // It does not clobber any general-purpose registers,
 // but may clobber others (e.g., floating point registers)
 // The act of CALLing gcWriteBarrier will clobber R30 (LR).
-TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$200
+//
+// Defined as ABIInternal since the compiler generates ABIInternal
+// calls to it directly and it does not use the stack-based Go ABI.
+TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$200
 	// Save the registers clobbered by the fast path.
 	MOVD	R0, 184(RSP)
 	MOVD	R1, 192(RSP)
@@ -1250,71 +1379,129 @@ flush:
 // in the caller's stack frame. These stubs write the args into that stack space and
 // then tail call to the corresponding runtime handler.
 // The tail call makes these stubs disappear in backtraces.
-TEXT runtime·panicIndex(SB),NOSPLIT,$0-16
+//
+// Defined as ABIInternal since the compiler generates ABIInternal
+// calls to it directly and it does not use the stack-based Go ABI.
+TEXT runtime·panicIndex(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicIndex(SB)
-TEXT runtime·panicIndexU(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicIndex(SB)
+TEXT runtime·panicIndexU(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicIndexU(SB)
-TEXT runtime·panicSliceAlen(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicIndexU(SB)
+TEXT runtime·panicSliceAlen(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAlen(SB)
-TEXT runtime·panicSliceAlenU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAlen(SB)
+TEXT runtime·panicSliceAlenU(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAlenU(SB)
-TEXT runtime·panicSliceAcap(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAlenU(SB)
+TEXT runtime·panicSliceAcap(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAcap(SB)
-TEXT runtime·panicSliceAcapU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAcap(SB)
+TEXT runtime·panicSliceAcapU(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAcapU(SB)
-TEXT runtime·panicSliceB(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAcapU(SB)
+TEXT runtime·panicSliceB(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSliceB(SB)
-TEXT runtime·panicSliceBU(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSliceB(SB)
+TEXT runtime·panicSliceBU(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSliceBU(SB)
-TEXT runtime·panicSlice3Alen(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSliceBU(SB)
+TEXT runtime·panicSlice3Alen(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3Alen(SB)
-TEXT runtime·panicSlice3AlenU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3Alen(SB)
+TEXT runtime·panicSlice3AlenU(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3AlenU(SB)
-TEXT runtime·panicSlice3Acap(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3AlenU(SB)
+TEXT runtime·panicSlice3Acap(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3Acap(SB)
-TEXT runtime·panicSlice3AcapU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3Acap(SB)
+TEXT runtime·panicSlice3AcapU(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3AcapU(SB)
-TEXT runtime·panicSlice3B(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3AcapU(SB)
+TEXT runtime·panicSlice3B(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSlice3B(SB)
-TEXT runtime·panicSlice3BU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3B(SB)
+TEXT runtime·panicSlice3BU(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSlice3BU(SB)
-TEXT runtime·panicSlice3C(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3BU(SB)
+TEXT runtime·panicSlice3C(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSlice3C(SB)
-TEXT runtime·panicSlice3CU(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSlice3C(SB)
+TEXT runtime·panicSlice3CU(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSlice3CU(SB)
-TEXT runtime·panicSliceConvert(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSlice3CU(SB)
+TEXT runtime·panicSliceConvert(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSliceConvert(SB)
+#endif
+	JMP	runtime·goPanicSliceConvert(SB)
diff --git a/src/runtime/asm_mips64x.s b/src/runtime/asm_mips64x.s
index d4d22801055157c1a4079ccce2142b6cfc928ba4..e0e5cbb7048c918de43d2696f7d692d707a60329 100644
--- a/src/runtime/asm_mips64x.s
+++ b/src/runtime/asm_mips64x.s
@@ -63,12 +63,11 @@ nocgo:
 
 	// create a new goroutine to start program
 	MOVV	$runtime·mainPC(SB), R1		// entry
-	ADDV	$-24, R29
-	MOVV	R1, 16(R29)
-	MOVV	R0, 8(R29)
+	ADDV	$-16, R29
+	MOVV	R1, 8(R29)
 	MOVV	R0, 0(R29)
 	JAL	runtime·newproc(SB)
-	ADDV	$24, R29
+	ADDV	$16, R29
 
 	// start this M
 	JAL	runtime·mstart(SB)
@@ -385,22 +384,6 @@ CALLFN(·call1073741824, 1073741824)
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 8 bytes to get back to JAL deferreturn
-// 3. JMP to fn
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOVV	0(R29), R31
-	ADDV	$-8, R31
-
-	MOVV	fv+0(FP), REGCTXT
-	MOVV	argp+8(FP), R29
-	ADDV	$-8, R29
-	NOR	R0, R0	// prevent scheduling
-	MOVV	0(REGCTXT), R4
-	JMP	(R4)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -441,8 +424,11 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-20
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOVV	g_m(g), R5
+	MOVV	m_gsignal(R5), R6
+	BEQ	R6, g, g0
 	MOVV	m_g0(R5), R6
 	BEQ	R6, g, g0
 
diff --git a/src/runtime/asm_mipsx.s b/src/runtime/asm_mipsx.s
index ea7edf20cf9f84fc21b38f81e66afe001d3a2030..1b550719d17eb4b5e3ef5ff320a814783315a960 100644
--- a/src/runtime/asm_mipsx.s
+++ b/src/runtime/asm_mipsx.s
@@ -64,12 +64,11 @@ nocgo:
 
 	// create a new goroutine to start program
 	MOVW	$runtime·mainPC(SB), R1	// entry
-	ADDU	$-12, R29
-	MOVW	R1, 8(R29)
-	MOVW	R0, 4(R29)
+	ADDU	$-8, R29
+	MOVW	R1, 4(R29)
 	MOVW	R0, 0(R29)
 	JAL	runtime·newproc(SB)
-	ADDU	$12, R29
+	ADDU	$8, R29
 
 	// start this M
 	JAL	runtime·mstart(SB)
@@ -383,22 +382,6 @@ CALLFN(·call1073741824, 1073741824)
 TEXT runtime·procyield(SB),NOSPLIT,$0-4
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 8 bytes to get back to JAL deferreturn
-// 3. JMP to fn
-TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
-	MOVW	0(R29), R31
-	ADDU	$-8, R31
-
-	MOVW	fv+0(FP), REGCTXT
-	MOVW	argp+4(FP), R29
-	ADDU	$-4, R29
-	NOR	R0, R0	// prevent scheduling
-	MOVW	0(REGCTXT), R4
-	JMP	(R4)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -430,8 +413,11 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-12
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOVW	g_m(g), R5
+	MOVW	m_gsignal(R5), R6
+	BEQ	R6, g, g0
 	MOVW	m_g0(R5), R6
 	BEQ	R6, g, g0
 
diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index 942cc14f17d044d8705ca4343a042139c2176204..7270abbdee211adcb863537677ef80188e34358c 100644
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -94,9 +94,8 @@ nocgo:
 	MOVDU	R0, -8(R1)
 	MOVDU	R0, -8(R1)
 	MOVDU	R0, -8(R1)
-	MOVDU	R0, -8(R1)
 	BL	runtime·newproc(SB)
-	ADD	$(16+FIXED_FRAME), R1
+	ADD	$(8+FIXED_FRAME), R1
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -504,34 +503,6 @@ again:
 	OR	R6, R6, R6	// Set PPR priority back to medium-low
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 8 bytes to get back to either nop or toc reload before deferreturn
-// 3. BR to fn
-// When dynamically linking Go, it is not sufficient to rewind to the BL
-// deferreturn -- we might be jumping between modules and so we need to reset
-// the TOC pointer in r2. To do this, codegen inserts MOVD 24(R1), R2 *before*
-// the BL deferreturn and jmpdefer rewinds to that.
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOVD	0(R1), R31
-	SUB     $8, R31
-	MOVD	R31, LR
-
-	MOVD	fv+0(FP), R11
-	MOVD	argp+8(FP), R1
-	SUB	$FIXED_FRAME, R1
-#ifdef GOOS_aix
-	// AIX won't trigger a SIGSEGV if R11 = nil
-	// So it manually triggers it
-	CMP	R0, R11
-	BNE	2(PC)
-	MOVD	R0, 0(R0)
-#endif
-	MOVD	0(R11), R12
-	MOVD	R12, CTR
-	BR	(CTR)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -570,9 +541,8 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-20
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
-	// Moreover, if it's called inside the signal handler, it must not switch
-	// to g0 as it can be in use by another syscall.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOVD	g_m(g), R8
 	MOVD	m_gsignal(R8), R6
 	CMP	R6, g
diff --git a/src/runtime/asm_riscv64.s b/src/runtime/asm_riscv64.s
index ef7af4e10d8826861804362f3604310ca570a584..531b46927c98f03a9469f2ddadc47f20745f7c09 100644
--- a/src/runtime/asm_riscv64.s
+++ b/src/runtime/asm_riscv64.s
@@ -57,12 +57,11 @@ nocgo:
 
 	// create a new goroutine to start program
 	MOV	$runtime·mainPC(SB), T0		// entry
-	ADD	$-24, X2
-	MOV	T0, 16(X2)
-	MOV	ZERO, 8(X2)
+	ADD	$-16, X2
+	MOV	T0, 8(X2)
 	MOV	ZERO, 0(X2)
 	CALL	runtime·newproc(SB)
-	ADD	$24, X2
+	ADD	$16, X2
 
 	// start this M
 	CALL	runtime·mstart(SB)
@@ -82,7 +81,7 @@ TEXT setg_gcc<>(SB),NOSPLIT,$0-0
 
 // func cputicks() int64
 TEXT runtime·cputicks(SB),NOSPLIT,$0-8
-	RDTIME	A0
+	RDCYCLE	A0
 	MOV	A0, ret+0(FP)
 	RET
 
@@ -249,21 +248,6 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 	MOV	gobuf_pc(T0), T0
 	JALR	ZERO, T0
 
-// func jmpdefer(fv *funcval, argp uintptr)
-// called from deferreturn
-// 1. grab stored return address from the caller's frame
-// 2. sub 8 bytes to get back to JAL deferreturn
-// 3. JMP to fn
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOV	0(X2), RA
-	ADD	$-8, RA
-
-	MOV	fv+0(FP), CTXT
-	MOV	argp+8(FP), X2
-	ADD	$-8, X2
-	MOV	0(CTXT), T0
-	JALR	ZERO, T0
-
 // func procyield(cycles uint32)
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
 	RET
@@ -326,8 +310,11 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-20
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOV	g_m(g), X6
+	MOV	m_gsignal(X6), X7
+	BEQ	X7, g, g0
 	MOV	m_g0(X6), X7
 	BEQ	X7, g, g0
 
diff --git a/src/runtime/asm_s390x.s b/src/runtime/asm_s390x.s
index fb382716303b42a6647b729be116512d1355bedd..5894fe5783113e6717233aaf1a09afcfebdce4d1 100644
--- a/src/runtime/asm_s390x.s
+++ b/src/runtime/asm_s390x.s
@@ -147,12 +147,11 @@ nocgo:
 
 	// create a new goroutine to start program
 	MOVD	$runtime·mainPC(SB), R2		// entry
-	SUB     $24, R15
-	MOVD 	R2, 16(R15)
-	MOVD 	$0, 8(R15)
+	SUB     $16, R15
+	MOVD 	R2, 8(R15)
 	MOVD 	$0, 0(R15)
 	BL	runtime·newproc(SB)
-	ADD	$24, R15
+	ADD	$16, R15
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -481,21 +480,6 @@ TEXT callfnMVC<>(SB),NOSPLIT|NOFRAME,$0-0
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 6 bytes to get back to BL deferreturn (size of BRASL instruction)
-// 3. BR to fn
-TEXT runtime·jmpdefer(SB),NOSPLIT|NOFRAME,$0-16
-	MOVD	0(R15), R1
-	SUB	$6, R1, LR
-
-	MOVD	fv+0(FP), R12
-	MOVD	argp+8(FP), R15
-	SUB	$8, R15
-	MOVD	0(R12), R3
-	BR	(R3)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -529,12 +513,15 @@ TEXT ·asmcgocall(SB),NOSPLIT,$0-20
 
 	// Figure out if we need to switch to m->g0 stack.
 	// We get called to create new OS threads too, and those
-	// come in on the m->g0 stack already.
+	// come in on the m->g0 stack already. Or we might already
+	// be on the m->gsignal stack.
 	MOVD	g_m(g), R6
-	MOVD	m_g0(R6), R6
-	CMPBEQ	R6, g, g0
+	MOVD	m_gsignal(R6), R7
+	CMPBEQ	R7, g, g0
+	MOVD	m_g0(R6), R7
+	CMPBEQ	R7, g, g0
 	BL	gosave_systemstack_switch<>(SB)
-	MOVD	R6, g
+	MOVD	R7, g
 	BL	runtime·save_g(SB)
 	MOVD	(g_sched+gobuf_sp)(g), R15
 
diff --git a/src/runtime/asm_wasm.s b/src/runtime/asm_wasm.s
index 33c335ba5af91bfde9c613cd164b095e03ea090f..d885da6e70f4398d36e04b7a4ac25613d749048d 100644
--- a/src/runtime/asm_wasm.s
+++ b/src/runtime/asm_wasm.s
@@ -18,8 +18,7 @@ TEXT runtime·rt0_go(SB), NOSPLIT|NOFRAME|TOPFRAME, $0
 	CALLNORESUME runtime·args(SB)
 	CALLNORESUME runtime·osinit(SB)
 	CALLNORESUME runtime·schedinit(SB)
-	MOVD $0, 0(SP)
-	MOVD $runtime·mainPC(SB), 8(SP)
+	MOVD $runtime·mainPC(SB), 0(SP)
 	CALLNORESUME runtime·newproc(SB)
 	CALL runtime·mstart(SB) // WebAssembly stack will unwind when switching to another goroutine
 	UNDEF
@@ -194,35 +193,6 @@ TEXT runtime·return0(SB), NOSPLIT, $0-0
 	MOVD $0, RET0
 	RET
 
-TEXT runtime·jmpdefer(SB), NOSPLIT, $0-16
-	MOVD fv+0(FP), CTXT
-
-	Get CTXT
-	I64Eqz
-	If
-		CALLNORESUME runtime·sigpanic(SB)
-	End
-
-	// caller sp after CALL
-	I64Load argp+8(FP)
-	I64Const $8
-	I64Sub
-	I32WrapI64
-	Set SP
-
-	// decrease PC_B by 1 to CALL again
-	Get SP
-	I32Load16U (SP)
-	I32Const $1
-	I32Sub
-	I32Store16 $0
-
-	// but first run the deferred function
-	Get CTXT
-	I32WrapI64
-	I64Load $0
-	JMP
-
 TEXT runtime·asminit(SB), NOSPLIT, $0-0
 	// No per-thread init.
 	RET
diff --git a/src/runtime/cgo/gcc_traceback.c b/src/runtime/cgo/gcc_traceback.c
index d86331c583a674cc6d2fa89bbb582ba439999c0c..6e9470c43c24ada65f16ac115f4a51c41c97de94 100644
--- a/src/runtime/cgo/gcc_traceback.c
+++ b/src/runtime/cgo/gcc_traceback.c
@@ -7,6 +7,14 @@
 #include 
 #include "libcgo.h"
 
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#if __has_feature(memory_sanitizer)
+#include 
+#endif
+
 // Call the user's traceback function and then call sigtramp.
 // The runtime signal handler will jump to this code.
 // We do it this way so that the user's traceback function will be called
@@ -19,6 +27,18 @@ x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(str
 	arg.SigContext = (uintptr_t)(context);
 	arg.Buf = cgoCallers;
 	arg.Max = 32; // must match len(runtime.cgoCallers)
+
+#if __has_feature(memory_sanitizer)
+        // This function is called directly from the signal handler.
+        // The arguments are passed in registers, so whether msan
+        // considers cgoCallers to be initialized depends on whether
+        // it considers the appropriate register to be initialized.
+        // That can cause false reports in rare cases.
+        // Explicitly unpoison the memory to avoid that.
+        // See issue #47543 for more details.
+        __msan_unpoison(&arg, sizeof arg);
+#endif
+
 	(*cgoTraceback)(&arg);
 	sigtramp(sig, info, context);
 }
diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go
index 8ffb48a888e7e4c155354e1fd48ac7dbefc2188c..2f3c609907649b2e385e98ab03183a02efc56a0a 100644
--- a/src/runtime/cgocall.go
+++ b/src/runtime/cgocall.go
@@ -85,6 +85,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -212,6 +213,8 @@ func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) {
 	// a different M. The call to unlockOSThread is in unwindm.
 	lockOSThread()
 
+	checkm := gp.m
+
 	// Save current syscall parameters, so m.syscall can be
 	// used again if callback decide to make syscall.
 	syscall := gp.m.syscall
@@ -227,15 +230,20 @@ func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) {
 
 	osPreemptExtExit(gp.m)
 
-	cgocallbackg1(fn, frame, ctxt)
+	cgocallbackg1(fn, frame, ctxt) // will call unlockOSThread
 
 	// At this point unlockOSThread has been called.
 	// The following code must not change to a different m.
 	// This is enforced by checking incgo in the schedule function.
 
+	gp.m.incgo = true
+
+	if gp.m != checkm {
+		throw("m changed unexpectedly in cgocallbackg")
+	}
+
 	osPreemptExtEnter(gp.m)
 
-	gp.m.incgo = true
 	// going back to cgo call
 	reentersyscall(savedpc, uintptr(savedsp))
 
@@ -244,6 +252,11 @@ func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) {
 
 func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) {
 	gp := getg()
+
+	// When we return, undo the call to lockOSThread in cgocallbackg.
+	// We must still stay on the same m.
+	defer unlockOSThread()
+
 	if gp.m.needextram || atomic.Load(&extraMWaiters) > 0 {
 		gp.m.needextram = false
 		systemstack(newextram)
@@ -323,10 +336,6 @@ func unwindm(restore *bool) {
 
 		releasem(mp)
 	}
-
-	// Undo the call to lockOSThread in cgocallbackg.
-	// We must still stay on the same m.
-	unlockOSThread()
 }
 
 // called from assembly
@@ -472,7 +481,7 @@ func cgoCheckArg(t *_type, p unsafe.Pointer, indir, top bool, msg string) {
 		if inheap(uintptr(unsafe.Pointer(it))) {
 			panic(errorString(msg))
 		}
-		p = *(*unsafe.Pointer)(add(p, sys.PtrSize))
+		p = *(*unsafe.Pointer)(add(p, goarch.PtrSize))
 		if !cgoIsGoPointer(p) {
 			return
 		}
@@ -552,7 +561,7 @@ func cgoCheckUnknownPointer(p unsafe.Pointer, msg string) (base, i uintptr) {
 		}
 		hbits := heapBitsForAddr(base)
 		n := span.elemsize
-		for i = uintptr(0); i < n; i += sys.PtrSize {
+		for i = uintptr(0); i < n; i += goarch.PtrSize {
 			if !hbits.morePointers() {
 				// No more possible pointers.
 				break
diff --git a/src/runtime/cgocheck.go b/src/runtime/cgocheck.go
index 516045c16331dcb6ae20a13fd1e5fe4433a3f775..3acbadf803d0443b76e94388ae13f0a19e7eaf74 100644
--- a/src/runtime/cgocheck.go
+++ b/src/runtime/cgocheck.go
@@ -8,7 +8,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -151,7 +151,7 @@ func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
 	// src must be in the regular heap.
 
 	hbits := heapBitsForAddr(uintptr(src))
-	for i := uintptr(0); i < off+size; i += sys.PtrSize {
+	for i := uintptr(0); i < off+size; i += goarch.PtrSize {
 		bits := hbits.bits()
 		if i >= off && bits&bitPointer != 0 {
 			v := *(*unsafe.Pointer)(add(src, i))
@@ -169,22 +169,22 @@ func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
 //go:nosplit
 //go:nowritebarrier
 func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
-	skipMask := off / sys.PtrSize / 8
-	skipBytes := skipMask * sys.PtrSize * 8
+	skipMask := off / goarch.PtrSize / 8
+	skipBytes := skipMask * goarch.PtrSize * 8
 	ptrmask := addb(gcbits, skipMask)
 	src = add(src, skipBytes)
 	off -= skipBytes
 	size += off
 	var bits uint32
-	for i := uintptr(0); i < size; i += sys.PtrSize {
-		if i&(sys.PtrSize*8-1) == 0 {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
+		if i&(goarch.PtrSize*8-1) == 0 {
 			bits = uint32(*ptrmask)
 			ptrmask = addb(ptrmask, 1)
 		} else {
 			bits >>= 1
 		}
 		if off > 0 {
-			off -= sys.PtrSize
+			off -= goarch.PtrSize
 		} else {
 			if bits&1 != 0 {
 				v := *(*unsafe.Pointer)(add(src, i))
diff --git a/src/runtime/chan.go b/src/runtime/chan.go
index f2a75b30f44596490a95c191139d0a1346394ec8..3cdb5dce117e3325fab2712bca53df1c704c0f7c 100644
--- a/src/runtime/chan.go
+++ b/src/runtime/chan.go
@@ -18,6 +18,7 @@ package runtime
 //  c.qcount < c.dataqsiz implies that c.sendq is empty.
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/math"
 	"unsafe"
@@ -169,7 +170,7 @@ func chansend(c *hchan, ep unsafe.Pointer, block bool, callerpc uintptr) bool {
 	}
 
 	if raceenabled {
-		racereadpc(c.raceaddr(), callerpc, funcPC(chansend))
+		racereadpc(c.raceaddr(), callerpc, abi.FuncPCABIInternal(chansend))
 	}
 
 	// Fast path: check for failed non-blocking operation without acquiring the lock.
@@ -365,7 +366,7 @@ func closechan(c *hchan) {
 
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(c.raceaddr(), callerpc, funcPC(closechan))
+		racewritepc(c.raceaddr(), callerpc, abi.FuncPCABIInternal(closechan))
 		racerelease(c.raceaddr())
 	}
 
diff --git a/src/runtime/cpuflags.go b/src/runtime/cpuflags.go
index 5104650c5d73e824ee1bc79b9a0db171d23b1002..bbe93c5bea2d7e46d752b25ebfca2e7b1640bdd6 100644
--- a/src/runtime/cpuflags.go
+++ b/src/runtime/cpuflags.go
@@ -11,10 +11,10 @@ import (
 
 // Offsets into internal/cpu records for use in assembly.
 const (
-	offsetX86HasAVX  = unsafe.Offsetof(cpu.X86.HasAVX)
-	offsetX86HasAVX2 = unsafe.Offsetof(cpu.X86.HasAVX2)
-	offsetX86HasERMS = unsafe.Offsetof(cpu.X86.HasERMS)
-	offsetX86HasSSE2 = unsafe.Offsetof(cpu.X86.HasSSE2)
+	offsetX86HasAVX    = unsafe.Offsetof(cpu.X86.HasAVX)
+	offsetX86HasAVX2   = unsafe.Offsetof(cpu.X86.HasAVX2)
+	offsetX86HasERMS   = unsafe.Offsetof(cpu.X86.HasERMS)
+	offsetX86HasRDTSCP = unsafe.Offsetof(cpu.X86.HasRDTSCP)
 
 	offsetARMHasIDIVA = unsafe.Offsetof(cpu.ARM.HasIDIVA)
 
diff --git a/src/runtime/cpuprof.go b/src/runtime/cpuprof.go
index e5d0193b9cbd4f5c10fc9ca0cac49464658ddec3..c81ab710c2021391708aa7a4e30c0395e9e6ff70 100644
--- a/src/runtime/cpuprof.go
+++ b/src/runtime/cpuprof.go
@@ -13,6 +13,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -166,8 +167,8 @@ func (p *cpuProfile) addExtra() {
 	if p.lostExtra > 0 {
 		hdr := [1]uint64{p.lostExtra}
 		lostStk := [2]uintptr{
-			funcPC(_LostExternalCode) + sys.PCQuantum,
-			funcPC(_ExternalCode) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_LostExternalCode) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum,
 		}
 		p.log.write(nil, 0, hdr[:], lostStk[:])
 		p.lostExtra = 0
@@ -176,8 +177,8 @@ func (p *cpuProfile) addExtra() {
 	if p.lostAtomic > 0 {
 		hdr := [1]uint64{p.lostAtomic}
 		lostStk := [2]uintptr{
-			funcPC(_LostSIGPROFDuringAtomic64) + sys.PCQuantum,
-			funcPC(_System) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_LostSIGPROFDuringAtomic64) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_System) + sys.PCQuantum,
 		}
 		p.log.write(nil, 0, hdr[:], lostStk[:])
 		p.lostAtomic = 0
diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index 7d25c51aa2a7c2a5823abe1be63be64b8752712a..5729942cee3bfb36b0e0152059aa607155c23aef 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -282,6 +282,15 @@ func TestCgoTracebackContext(t *testing.T) {
 	}
 }
 
+func TestCgoTracebackContextPreemption(t *testing.T) {
+	t.Parallel()
+	got := runTestProg(t, "testprogcgo", "TracebackContextPreemption")
+	want := "OK\n"
+	if got != want {
+		t.Errorf("expected %q got %v", want, got)
+	}
+}
+
 func testCgoPprof(t *testing.T, buildArg, runArg, top, bottom string) {
 	t.Parallel()
 	if runtime.GOOS != "linux" || (runtime.GOARCH != "amd64" && runtime.GOARCH != "ppc64le") {
diff --git a/src/runtime/debugcall.go b/src/runtime/debugcall.go
index faddf59eed6b405b11709b69012d1148af9845c6..ad66a18c26ce74bd9a1580d6090ae16a3ac72947 100644
--- a/src/runtime/debugcall.go
+++ b/src/runtime/debugcall.go
@@ -112,7 +112,7 @@ func debugCallWrap(dispatch uintptr) {
 		// closure and start the goroutine with that closure, but the compiler disallows
 		// implicit closure allocation in the runtime.
 		fn := debugCallWrap1
-		newg := newproc1(*(**funcval)(unsafe.Pointer(&fn)), nil, 0, gp, callerpc)
+		newg := newproc1(*(**funcval)(unsafe.Pointer(&fn)), gp, callerpc)
 		args := &debugCallWrapArgs{
 			dispatch: dispatch,
 			callingG: gp,
diff --git a/src/runtime/defs_openbsd.go b/src/runtime/defs_openbsd.go
index 8d323449d1c5d4330f0ce732b10be0e036f5bec6..f818dc445396f1d2c397a46b78a471b4ba31a206 100644
--- a/src/runtime/defs_openbsd.go
+++ b/src/runtime/defs_openbsd.go
@@ -26,6 +26,7 @@ package runtime
 #include 
 #include 
 #include 
+#include 
 #include 
 */
 import "C"
diff --git a/src/runtime/defs_plan9_386.go b/src/runtime/defs_plan9_386.go
index 49129b3c3fcb1c675f26c89426b27ebb8a0d0624..428044df6871d71823a5f18edd745e1fb749eda9 100644
--- a/src/runtime/defs_plan9_386.go
+++ b/src/runtime/defs_plan9_386.go
@@ -61,4 +61,4 @@ func dumpregs(u *ureg) {
 	print("gs    ", hex(u.gs), "\n")
 }
 
-func sigpanictramp() {}
+func sigpanictramp()
diff --git a/src/runtime/defs_plan9_amd64.go b/src/runtime/defs_plan9_amd64.go
index 00995630341a81c09cd28eaab16a31942532fd48..15a27fc7db9e5110991e4dcf282ed590b2171d9a 100644
--- a/src/runtime/defs_plan9_amd64.go
+++ b/src/runtime/defs_plan9_amd64.go
@@ -78,4 +78,4 @@ func dumpregs(u *ureg) {
 	print("gs    ", hex(u.gs), "\n")
 }
 
-func sigpanictramp() {}
+func sigpanictramp()
diff --git a/src/runtime/duff_arm64.s b/src/runtime/duff_arm64.s
index 128b076af9db658b41847080c5fa72e35d7eecc6..33c4905078d242502ac00743a8b705f3ce16e23b 100644
--- a/src/runtime/duff_arm64.s
+++ b/src/runtime/duff_arm64.s
@@ -4,7 +4,7 @@
 
 #include "textflag.h"
 
-TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0
+TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0
 	STP.P	(ZR, ZR), 16(R20)
 	STP.P	(ZR, ZR), 16(R20)
 	STP.P	(ZR, ZR), 16(R20)
@@ -71,7 +71,7 @@ TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0
 	STP	(ZR, ZR), (R20)
 	RET
 
-TEXT runtime·duffcopy(SB), NOSPLIT|NOFRAME, $0-0
+TEXT runtime·duffcopy(SB), NOSPLIT|NOFRAME, $0-0
 	LDP.P	16(R20), (R26, R27)
 	STP.P	(R26, R27), 16(R21)
 
diff --git a/src/runtime/export_debug_test.go b/src/runtime/export_debug_test.go
index fe4c9045c107ebc01c0b25548d2e0c397397136a..a2cef02cf863becfca3d63d81323c89e057d1705 100644
--- a/src/runtime/export_debug_test.go
+++ b/src/runtime/export_debug_test.go
@@ -9,7 +9,7 @@ package runtime
 
 import (
 	"internal/abi"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -115,7 +115,7 @@ func (h *debugCallHandler) inject(info *siginfo, ctxt *sigctxt, gp2 *g) bool {
 			return false
 		}
 		// Push current PC on the stack.
-		rsp := ctxt.rsp() - sys.PtrSize
+		rsp := ctxt.rsp() - goarch.PtrSize
 		*(*uint64)(unsafe.Pointer(uintptr(rsp))) = ctxt.rip()
 		ctxt.set_rsp(rsp)
 		// Write the argument frame size.
@@ -125,7 +125,7 @@ func (h *debugCallHandler) inject(info *siginfo, ctxt *sigctxt, gp2 *g) bool {
 		h.savedFP = *h.savedRegs.fpstate
 		h.savedRegs.fpstate = nil
 		// Set PC to debugCallV2.
-		ctxt.set_rip(uint64(funcPC(debugCallV2)))
+		ctxt.set_rip(uint64(abi.FuncPCABIInternal(debugCallV2)))
 		// Call injected. Switch to the debugCall protocol.
 		testSigtrap = h.handleF
 	case _Grunnable:
@@ -166,7 +166,7 @@ func (h *debugCallHandler) handle(info *siginfo, ctxt *sigctxt, gp2 *g) bool {
 			storeRegArgs(ctxt.regs(), h.regArgs)
 		}
 		// Push return PC.
-		sp -= sys.PtrSize
+		sp -= goarch.PtrSize
 		ctxt.set_rsp(sp)
 		*(*uint64)(unsafe.Pointer(uintptr(sp))) = ctxt.rip()
 		// Set PC to call and context register.
@@ -182,7 +182,7 @@ func (h *debugCallHandler) handle(info *siginfo, ctxt *sigctxt, gp2 *g) bool {
 	case 2:
 		// Function panicked. Copy panic out.
 		sp := ctxt.rsp()
-		memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(sp)), 2*sys.PtrSize)
+		memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(sp)), 2*goarch.PtrSize)
 	case 8:
 		// Call isn't safe. Get the reason.
 		sp := ctxt.rsp()
diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go
index c8d01fbb1574de6b78faff16ed63b8d8c7362d52..e7279564e3fcaee92453d3e76dca1d5122e4695e 100644
--- a/src/runtime/export_test.go
+++ b/src/runtime/export_test.go
@@ -7,6 +7,8 @@
 package runtime
 
 import (
+	"internal/goarch"
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -27,8 +29,6 @@ var Exitsyscall = exitsyscall
 var LockedOSThread = lockedOSThread
 var Xadduintptr = atomic.Xadduintptr
 
-var FuncPC = funcPC
-
 var Fastlog2 = fastlog2
 
 var Atoi = atoi
@@ -147,40 +147,28 @@ func RunSchedLocalQueueStealTest() {
 	}
 }
 
-// Temporary to enable register ABI bringup.
-// TODO(register args): convert back to local variables in RunSchedLocalQueueEmptyTest that
-// get passed to the "go" stmts there.
-var RunSchedLocalQueueEmptyState struct {
-	done  chan bool
-	ready *uint32
-	p     *p
-}
-
 func RunSchedLocalQueueEmptyTest(iters int) {
 	// Test that runq is not spuriously reported as empty.
 	// Runq emptiness affects scheduling decisions and spurious emptiness
 	// can lead to underutilization (both runnable Gs and idle Ps coexist
 	// for arbitrary long time).
 	done := make(chan bool, 1)
-	RunSchedLocalQueueEmptyState.done = done
 	p := new(p)
-	RunSchedLocalQueueEmptyState.p = p
 	gs := make([]g, 2)
 	ready := new(uint32)
-	RunSchedLocalQueueEmptyState.ready = ready
 	for i := 0; i < iters; i++ {
 		*ready = 0
 		next0 := (i & 1) == 0
 		next1 := (i & 2) == 0
 		runqput(p, &gs[0], next0)
 		go func() {
-			for atomic.Xadd(RunSchedLocalQueueEmptyState.ready, 1); atomic.Load(RunSchedLocalQueueEmptyState.ready) != 2; {
+			for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
 			}
-			if runqempty(RunSchedLocalQueueEmptyState.p) {
-				//println("next:", next0, next1)
+			if runqempty(p) {
+				println("next:", next0, next1)
 				throw("queue is empty")
 			}
-			RunSchedLocalQueueEmptyState.done <- true
+			done <- true
 		}()
 		for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
 		}
@@ -228,8 +216,6 @@ var Write = write
 func Envs() []string     { return envs }
 func SetEnvs(e []string) { envs = e }
 
-var BigEndian = sys.BigEndian
-
 // For benchmarking.
 
 func BenchSetType(n int, x interface{}) {
@@ -259,7 +245,7 @@ func BenchSetType(n int, x interface{}) {
 	})
 }
 
-const PtrSize = sys.PtrSize
+const PtrSize = goarch.PtrSize
 
 var ForceGCPeriod = &forcegcperiod
 
@@ -1066,7 +1052,7 @@ func FreePageAlloc(pp *PageAlloc) {
 //
 // This should not be higher than 0x100*pallocChunkBytes to support
 // mips and mipsle, which only have 31-bit address spaces.
-var BaseChunkIdx = ChunkIdx(chunkIndex(((0xc000*pageAlloc64Bit + 0x100*pageAlloc32Bit) * pallocChunkBytes) + arenaBaseOffset*sys.GoosAix))
+var BaseChunkIdx = ChunkIdx(chunkIndex(((0xc000*pageAlloc64Bit + 0x100*pageAlloc32Bit) * pallocChunkBytes) + arenaBaseOffset*goos.IsAix))
 
 // PageBase returns an address given a chunk index and a page index
 // relative to that chunk.
diff --git a/src/runtime/export_windows_test.go b/src/runtime/export_windows_test.go
index 536b398fd7a077802aa5a65a328237c049171afa..d9cf753463940c2f6c2bfc0c8dd3a9de56179411 100644
--- a/src/runtime/export_windows_test.go
+++ b/src/runtime/export_windows_test.go
@@ -8,6 +8,8 @@ package runtime
 
 import "unsafe"
 
+const MaxArgs = maxArgs
+
 var (
 	TestingWER              = &testingWER
 	OsYield                 = osyield
diff --git a/src/runtime/extern.go b/src/runtime/extern.go
index 48e1e6603b7aeb179bdf627c801f91665e3106b0..eca4062e68c17bb663e3cc0541664858c4627dbe 100644
--- a/src/runtime/extern.go
+++ b/src/runtime/extern.go
@@ -186,7 +186,10 @@ of the run-time system.
 */
 package runtime
 
-import "runtime/internal/sys"
+import (
+	"internal/goarch"
+	"internal/goos"
+)
 
 // Caller reports file and line number information about function invocations on
 // the calling goroutine's stack. The argument skip is the number of stack frames
@@ -260,8 +263,8 @@ func Version() string {
 // GOOS is the running program's operating system target:
 // one of darwin, freebsd, linux, and so on.
 // To view possible combinations of GOOS and GOARCH, run "go tool dist list".
-const GOOS string = sys.GOOS
+const GOOS string = goos.GOOS
 
 // GOARCH is the running program's architecture target:
 // one of 386, amd64, arm, s390x, and so on.
-const GOARCH string = sys.GOARCH
+const GOARCH string = goarch.GOARCH
diff --git a/src/runtime/gc_test.go b/src/runtime/gc_test.go
index 5e7c6c574fe1937777f3af9a3c508917088d9452..0ec533153484ca953ed385453bf36829e69c1416 100644
--- a/src/runtime/gc_test.go
+++ b/src/runtime/gc_test.go
@@ -21,6 +21,7 @@ import (
 )
 
 func TestGcSys(t *testing.T) {
+	t.Skip("skipping known-flaky test; golang.org/issue/37331")
 	if os.Getenv("GOGC") == "off" {
 		t.Skip("skipping test; GOGC=off in environment")
 	}
diff --git a/src/runtime/heapdump.go b/src/runtime/heapdump.go
index 934e55f49523061a8787551c0aff15d3e92a0ffa..8fb30d95b9b1be80d880e8fec575632dfc6367da 100644
--- a/src/runtime/heapdump.go
+++ b/src/runtime/heapdump.go
@@ -12,7 +12,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -247,7 +247,7 @@ func dumpbv(cbv *bitvector, offset uintptr) {
 	for i := uintptr(0); i < uintptr(cbv.n); i++ {
 		if cbv.ptrbit(i) == 1 {
 			dumpint(fieldKindPtr)
-			dumpint(uint64(offset + i*sys.PtrSize))
+			dumpint(uint64(offset + i*goarch.PtrSize))
 		}
 	}
 }
@@ -298,7 +298,7 @@ func dumpframe(s *stkframe, arg unsafe.Pointer) bool {
 		dumpbv(&child.args, child.argoff)
 	} else {
 		// conservative - everything might be a pointer
-		for off := child.argoff; off < child.argoff+child.arglen; off += sys.PtrSize {
+		for off := child.argoff; off < child.argoff+child.arglen; off += goarch.PtrSize {
 			dumpint(fieldKindPtr)
 			dumpint(uint64(off))
 		}
@@ -307,21 +307,21 @@ func dumpframe(s *stkframe, arg unsafe.Pointer) bool {
 	// Dump fields in the local vars section
 	if stkmap == nil {
 		// No locals information, dump everything.
-		for off := child.arglen; off < s.varp-s.sp; off += sys.PtrSize {
+		for off := child.arglen; off < s.varp-s.sp; off += goarch.PtrSize {
 			dumpint(fieldKindPtr)
 			dumpint(uint64(off))
 		}
 	} else if stkmap.n < 0 {
 		// Locals size information, dump just the locals.
 		size := uintptr(-stkmap.n)
-		for off := s.varp - size - s.sp; off < s.varp-s.sp; off += sys.PtrSize {
+		for off := s.varp - size - s.sp; off < s.varp-s.sp; off += goarch.PtrSize {
 			dumpint(fieldKindPtr)
 			dumpint(uint64(off))
 		}
 	} else if stkmap.n > 0 {
 		// Locals bitmap information, scan just the pointers in
 		// locals.
-		dumpbv(&bv, s.varp-uintptr(bv.n)*sys.PtrSize-s.sp)
+		dumpbv(&bv, s.varp-uintptr(bv.n)*goarch.PtrSize-s.sp)
 	}
 	dumpint(fieldKindEol)
 
@@ -381,12 +381,13 @@ func dumpgoroutine(gp *g) {
 		dumpint(uint64(uintptr(unsafe.Pointer(gp))))
 		dumpint(uint64(d.sp))
 		dumpint(uint64(d.pc))
-		dumpint(uint64(uintptr(unsafe.Pointer(d.fn))))
+		fn := *(**funcval)(unsafe.Pointer(&d.fn))
+		dumpint(uint64(uintptr(unsafe.Pointer(fn))))
 		if d.fn == nil {
 			// d.fn can be nil for open-coded defers
 			dumpint(uint64(0))
 		} else {
-			dumpint(uint64(uintptr(unsafe.Pointer(d.fn.fn))))
+			dumpint(uint64(uintptr(unsafe.Pointer(fn.fn))))
 		}
 		dumpint(uint64(uintptr(unsafe.Pointer(d.link))))
 	}
@@ -510,7 +511,7 @@ func dumpparams() {
 	} else {
 		dumpbool(true) // big-endian ptrs
 	}
-	dumpint(sys.PtrSize)
+	dumpint(goarch.PtrSize)
 	var arenaStart, arenaEnd uintptr
 	for i1 := range mheap_.arenas {
 		if mheap_.arenas[i1] == nil {
@@ -531,7 +532,7 @@ func dumpparams() {
 	}
 	dumpint(uint64(arenaStart))
 	dumpint(uint64(arenaEnd))
-	dumpstr(sys.GOARCH)
+	dumpstr(goarch.GOARCH)
 	dumpstr(buildVersion)
 	dumpint(uint64(ncpu))
 }
@@ -725,7 +726,7 @@ func dumpfields(bv bitvector) {
 
 func makeheapobjbv(p uintptr, size uintptr) bitvector {
 	// Extend the temp buffer if necessary.
-	nptr := size / sys.PtrSize
+	nptr := size / goarch.PtrSize
 	if uintptr(len(tmpbuf)) < nptr/8+1 {
 		if tmpbuf != nil {
 			sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
diff --git a/src/runtime/iface.go b/src/runtime/iface.go
index cd5fead9990cbfe2c98cfd291620c16b14f59589..3d1d9d6ba18cf0183f3edb87fcc03ca5f2548275 100644
--- a/src/runtime/iface.go
+++ b/src/runtime/iface.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -63,7 +64,7 @@ func getitab(inter *interfacetype, typ *_type, canfail bool) *itab {
 	}
 
 	// Entry doesn't exist yet. Make a new entry & add it.
-	m = (*itab)(persistentalloc(unsafe.Sizeof(itab{})+uintptr(len(inter.mhdr)-1)*sys.PtrSize, 0, &memstats.other_sys))
+	m = (*itab)(persistentalloc(unsafe.Sizeof(itab{})+uintptr(len(inter.mhdr)-1)*goarch.PtrSize, 0, &memstats.other_sys))
 	m.inter = inter
 	m._type = typ
 	// The hash is used in type switches. However, compiler statically generates itab's
@@ -100,7 +101,7 @@ func (t *itabTableType) find(inter *interfacetype, typ *_type) *itab {
 	mask := t.size - 1
 	h := itabHashFunc(inter, typ) & mask
 	for i := uintptr(1); ; i++ {
-		p := (**itab)(add(unsafe.Pointer(&t.entries), h*sys.PtrSize))
+		p := (**itab)(add(unsafe.Pointer(&t.entries), h*goarch.PtrSize))
 		// Use atomic read here so if we see m != nil, we also see
 		// the initializations of the fields of m.
 		// m := *p
@@ -133,7 +134,7 @@ func itabAdd(m *itab) {
 		// t2 = new(itabTableType) + some additional entries
 		// We lie and tell malloc we want pointer-free memory because
 		// all the pointed-to values are not in the heap.
-		t2 := (*itabTableType)(mallocgc((2+2*t.size)*sys.PtrSize, nil, true))
+		t2 := (*itabTableType)(mallocgc((2+2*t.size)*goarch.PtrSize, nil, true))
 		t2.size = t.size * 2
 
 		// Copy over entries.
@@ -161,7 +162,7 @@ func (t *itabTableType) add(m *itab) {
 	mask := t.size - 1
 	h := itabHashFunc(m.inter, m._type) & mask
 	for i := uintptr(1); ; i++ {
-		p := (**itab)(add(unsafe.Pointer(&t.entries), h*sys.PtrSize))
+		p := (**itab)(add(unsafe.Pointer(&t.entries), h*goarch.PtrSize))
 		m2 := *p
 		if m2 == m {
 			// A given itab may be used in more than one module
@@ -315,26 +316,36 @@ var (
 // The convXXX functions succeed on a nil input, whereas the assertXXX
 // functions fail on a nil input.
 
-func convT2E(t *_type, elem unsafe.Pointer) (e eface) {
+// convT converts a value of type t, which is pointed to by v, to a pointer that can
+// be used as the second word of an interface value.
+func convT(t *_type, v unsafe.Pointer) unsafe.Pointer {
 	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2E))
+		raceReadObjectPC(t, v, getcallerpc(), abi.FuncPCABIInternal(convT))
 	}
 	if msanenabled {
-		msanread(elem, t.size)
+		msanread(v, t.size)
 	}
 	x := mallocgc(t.size, t, true)
-	// TODO: We allocate a zeroed object only to overwrite it with actual data.
-	// Figure out how to avoid zeroing. Also below in convT2Eslice, convT2I, convT2Islice.
-	typedmemmove(t, x, elem)
-	e._type = t
-	e.data = x
-	return
+	typedmemmove(t, x, v)
+	return x
+}
+func convTnoptr(t *_type, v unsafe.Pointer) unsafe.Pointer {
+	// TODO: maybe take size instead of type?
+	if raceenabled {
+		raceReadObjectPC(t, v, getcallerpc(), abi.FuncPCABIInternal(convTnoptr))
+	}
+	if msanenabled {
+		msanread(v, t.size)
+	}
+	x := mallocgc(t.size, t, false)
+	memmove(x, v, t.size)
+	return x
 }
 
 func convT16(val uint16) (x unsafe.Pointer) {
 	if val < uint16(len(staticuint64s)) {
 		x = unsafe.Pointer(&staticuint64s[val])
-		if sys.BigEndian {
+		if goarch.BigEndian {
 			x = add(x, 6)
 		}
 	} else {
@@ -347,7 +358,7 @@ func convT16(val uint16) (x unsafe.Pointer) {
 func convT32(val uint32) (x unsafe.Pointer) {
 	if val < uint32(len(staticuint64s)) {
 		x = unsafe.Pointer(&staticuint64s[val])
-		if sys.BigEndian {
+		if goarch.BigEndian {
 			x = add(x, 4)
 		}
 	} else {
@@ -388,63 +399,16 @@ func convTslice(val []byte) (x unsafe.Pointer) {
 	return
 }
 
-func convT2Enoptr(t *_type, elem unsafe.Pointer) (e eface) {
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Enoptr))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
-	x := mallocgc(t.size, t, false)
-	memmove(x, elem, t.size)
-	e._type = t
-	e.data = x
-	return
-}
-
-func convT2I(tab *itab, elem unsafe.Pointer) (i iface) {
-	t := tab._type
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2I))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
-	x := mallocgc(t.size, t, true)
-	typedmemmove(t, x, elem)
-	i.tab = tab
-	i.data = x
-	return
-}
-
-func convT2Inoptr(tab *itab, elem unsafe.Pointer) (i iface) {
-	t := tab._type
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Inoptr))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
-	x := mallocgc(t.size, t, false)
-	memmove(x, elem, t.size)
-	i.tab = tab
-	i.data = x
-	return
-}
-
-func convI2I(inter *interfacetype, i iface) (r iface) {
-	tab := i.tab
-	if tab == nil {
-		return
+// convI2I returns the new itab to be used for the destination value
+// when converting a value with itab src to the dst interface.
+func convI2I(dst *interfacetype, src *itab) *itab {
+	if src == nil {
+		return nil
 	}
-	if tab.inter == inter {
-		r.tab = tab
-		r.data = i.data
-		return
+	if src.inter == dst {
+		return src
 	}
-	r.tab = getitab(inter, tab._type, false)
-	r.data = i.data
-	return
+	return getitab(dst, src._type, false)
 }
 
 func assertI2I(inter *interfacetype, tab *itab) *itab {
@@ -511,7 +475,7 @@ func iterate_itabs(fn func(*itab)) {
 	// so no other locks/atomics needed.
 	t := itabTable
 	for i := uintptr(0); i < t.size; i++ {
-		m := *(**itab)(add(unsafe.Pointer(&t.entries), i*sys.PtrSize))
+		m := *(**itab)(add(unsafe.Pointer(&t.entries), i*goarch.PtrSize))
 		if m != nil {
 			fn(m)
 		}
diff --git a/src/runtime/internal/atomic/atomic_test.go b/src/runtime/internal/atomic/atomic_test.go
index c9c2eba248cf4221b3c5cad1d4d3b577117a60f9..2ae60b8507ef5831e2d5345514224696c0b85623 100644
--- a/src/runtime/internal/atomic/atomic_test.go
+++ b/src/runtime/internal/atomic/atomic_test.go
@@ -5,9 +5,9 @@
 package atomic_test
 
 import (
+	"internal/goarch"
 	"runtime"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"testing"
 	"unsafe"
 )
@@ -56,7 +56,7 @@ func TestXadduintptr(t *testing.T) {
 // Tests that xadduintptr correctly updates 64-bit values. The place where
 // we actually do so is mstats.go, functions mSysStat{Inc,Dec}.
 func TestXadduintptrOnUint64(t *testing.T) {
-	if sys.BigEndian {
+	if goarch.BigEndian {
 		// On big endian architectures, we never use xadduintptr to update
 		// 64-bit values and hence we skip the test.  (Note that functions
 		// mSysStat{Inc,Dec} in mstats.go have explicit checks for
diff --git a/src/runtime/internal/math/math.go b/src/runtime/internal/math/math.go
index b6bd12d3e8b66d5908b5c2d0da0bfe0d051ff263..c3fac366be0210979ce9beee890eb5394df909f5 100644
--- a/src/runtime/internal/math/math.go
+++ b/src/runtime/internal/math/math.go
@@ -4,14 +4,14 @@
 
 package math
 
-import "runtime/internal/sys"
+import "internal/goarch"
 
 const MaxUintptr = ^uintptr(0)
 
 // MulUintptr returns a * b and whether the multiplication overflowed.
 // On supported platforms this is an intrinsic lowered by the compiler.
 func MulUintptr(a, b uintptr) (uintptr, bool) {
-	if a|b < 1<<(4*sys.PtrSize) || a == 0 {
+	if a|b < 1<<(4*goarch.PtrSize) || a == 0 {
 		return a * b, false
 	}
 	overflow := b > MaxUintptr/a
diff --git a/src/runtime/internal/sys/consts.go b/src/runtime/internal/sys/consts.go
new file mode 100644
index 0000000000000000000000000000000000000000..fffcf81d1f3b398d657ef9a7a1ff9fc1d764a23c
--- /dev/null
+++ b/src/runtime/internal/sys/consts.go
@@ -0,0 +1,34 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sys
+
+import (
+	"internal/goarch"
+	"internal/goos"
+)
+
+// AIX requires a larger stack for syscalls.
+const StackGuardMultiplier = StackGuardMultiplierDefault*(1-goos.IsAix) + 2*goos.IsAix
+
+// DefaultPhysPageSize is the default physical page size.
+const DefaultPhysPageSize = goarch.DefaultPhysPageSize
+
+// PCQuantum is the minimal unit for a program counter (1 on x86, 4 on most other systems).
+// The various PC tables record PC deltas pre-divided by PCQuantum.
+const PCQuantum = goarch.PCQuantum
+
+// Int64Align is the required alignment for a 64-bit integer (4 on 32-bit systems, 8 on 64-bit).
+const Int64Align = goarch.PtrSize
+
+// MinFrameSize is the size of the system-reserved words at the bottom
+// of a frame (just above the architectural stack pointer).
+// It is zero on x86 and PtrSize on most non-x86 (LR-based) systems.
+// On PowerPC it is larger, to cover three more reserved words:
+// the compiler word, the link editor word, and the TOC save word.
+const MinFrameSize = goarch.MinFrameSize
+
+// StackAlign is the required alignment of the SP register.
+// The stack must be at least word aligned, but some architectures require more.
+const StackAlign = goarch.StackAlign
diff --git a/src/runtime/internal/sys/sys.go b/src/runtime/internal/sys/sys.go
index 9d9ac4507f66447037acc3599f70640583a97cf4..694101d36fda4133c60640b714437198e35dce60 100644
--- a/src/runtime/internal/sys/sys.go
+++ b/src/runtime/internal/sys/sys.go
@@ -5,11 +5,3 @@
 // package sys contains system- and configuration- and architecture-specific
 // constants used by the runtime.
 package sys
-
-// The next line makes 'go generate' write the zgo*.go files with
-// per-OS and per-arch information, including constants
-// named Goos$GOOS and Goarch$GOARCH for every
-// known GOOS and GOARCH. The constant is 1 on the
-// current system, 0 otherwise; multiplying by them is
-// useful for defining GOOS- or GOARCH-specific constants.
-//go:generate go run gengoos.go
diff --git a/src/runtime/internal/sys/zgoarch_386.go b/src/runtime/internal/sys/zgoarch_386.go
deleted file mode 100644
index 5b189e7e738f469258c7595343f0cf89cb09b73d..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_386.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build 386
-// +build 386
-
-package sys
-
-const GOARCH = `386`
-
-const Goarch386 = 1
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_amd64.go b/src/runtime/internal/sys/zgoarch_amd64.go
deleted file mode 100644
index 312977d07923f85ea9e6b575162abdf7b0305509..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_amd64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build amd64
-// +build amd64
-
-package sys
-
-const GOARCH = `amd64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 1
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_arm.go b/src/runtime/internal/sys/zgoarch_arm.go
deleted file mode 100644
index 5781870324e0b900a42f890b6c3a4366330ae13f..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_arm.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build arm
-// +build arm
-
-package sys
-
-const GOARCH = `arm`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 1
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_arm64.go b/src/runtime/internal/sys/zgoarch_arm64.go
deleted file mode 100644
index f72a1f2161c1df8713b0c84e1eea36c2bd8b7960..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_arm64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build arm64
-// +build arm64
-
-package sys
-
-const GOARCH = `arm64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 1
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_arm64be.go b/src/runtime/internal/sys/zgoarch_arm64be.go
deleted file mode 100644
index e8056460587ca1d55b176f97689e9e7f327a80e2..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_arm64be.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build arm64be
-// +build arm64be
-
-package sys
-
-const GOARCH = `arm64be`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 1
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_armbe.go b/src/runtime/internal/sys/zgoarch_armbe.go
deleted file mode 100644
index d8d4e56d9a4e35cfdc7231b094f38b7538a2301b..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_armbe.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build armbe
-// +build armbe
-
-package sys
-
-const GOARCH = `armbe`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 1
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_loong64.go b/src/runtime/internal/sys/zgoarch_loong64.go
deleted file mode 100644
index 6f35eb44a3b8a6717266534b97fbc0fc7d1f7e13..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_loong64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build loong64
-// +build loong64
-
-package sys
-
-const GOARCH = `loong64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 1
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips.go b/src/runtime/internal/sys/zgoarch_mips.go
deleted file mode 100644
index bd58a92a0e4e93f513f829e6827dbfee804f7f9c..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_mips.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips
-// +build mips
-
-package sys
-
-const GOARCH = `mips`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 1
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64.go b/src/runtime/internal/sys/zgoarch_mips64.go
deleted file mode 100644
index 8e4a3dcd526d854958bda84dc279c28530e0a87a..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_mips64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64
-// +build mips64
-
-package sys
-
-const GOARCH = `mips64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 1
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64le.go b/src/runtime/internal/sys/zgoarch_mips64le.go
deleted file mode 100644
index d8e00339ea81aa6f485d7e9f7424c6a9f9f6e5dc..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_mips64le.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64le
-// +build mips64le
-
-package sys
-
-const GOARCH = `mips64le`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 1
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64p32.go b/src/runtime/internal/sys/zgoarch_mips64p32.go
deleted file mode 100644
index 8549cc0ba3443fa808cb9982b84047974767a53d..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_mips64p32.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64p32
-// +build mips64p32
-
-package sys
-
-const GOARCH = `mips64p32`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 1
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64p32le.go b/src/runtime/internal/sys/zgoarch_mips64p32le.go
deleted file mode 100644
index 667b6fe514b0bd4c0c324edd77a76aa266f11105..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_mips64p32le.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64p32le
-// +build mips64p32le
-
-package sys
-
-const GOARCH = `mips64p32le`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 1
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mipsle.go b/src/runtime/internal/sys/zgoarch_mipsle.go
deleted file mode 100644
index 8bedb2bb9019699e4b8e992f83c9f7b4ad178f18..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_mipsle.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mipsle
-// +build mipsle
-
-package sys
-
-const GOARCH = `mipsle`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 1
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_ppc.go b/src/runtime/internal/sys/zgoarch_ppc.go
deleted file mode 100644
index fe2196a32789e51b4b90dde92ab6c45dea0edcc9..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_ppc.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ppc
-// +build ppc
-
-package sys
-
-const GOARCH = `ppc`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 1
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_ppc64.go b/src/runtime/internal/sys/zgoarch_ppc64.go
deleted file mode 100644
index bd7cc43de3974d2041c98e87d3041dd62cbfa608..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_ppc64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ppc64
-// +build ppc64
-
-package sys
-
-const GOARCH = `ppc64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 1
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_ppc64le.go b/src/runtime/internal/sys/zgoarch_ppc64le.go
deleted file mode 100644
index e101892401650d3cfd342b47b2db890fc911c246..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_ppc64le.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ppc64le
-// +build ppc64le
-
-package sys
-
-const GOARCH = `ppc64le`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 1
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_riscv.go b/src/runtime/internal/sys/zgoarch_riscv.go
deleted file mode 100644
index 559f86071a7ea83258d0b28b50615f4648e8c12b..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_riscv.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build riscv
-// +build riscv
-
-package sys
-
-const GOARCH = `riscv`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 1
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_riscv64.go b/src/runtime/internal/sys/zgoarch_riscv64.go
deleted file mode 100644
index 8485a94b3dd910dd00e79aee3a4cd73c9b2e8ae2..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_riscv64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build riscv64
-// +build riscv64
-
-package sys
-
-const GOARCH = `riscv64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 1
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_s390.go b/src/runtime/internal/sys/zgoarch_s390.go
deleted file mode 100644
index 4c4569e3762159cc8b313628a7a71eacc798f019..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_s390.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build s390
-// +build s390
-
-package sys
-
-const GOARCH = `s390`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 1
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_s390x.go b/src/runtime/internal/sys/zgoarch_s390x.go
deleted file mode 100644
index e50d2edbb5515c84f34c3eac907658c112abe16f..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_s390x.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build s390x
-// +build s390x
-
-package sys
-
-const GOARCH = `s390x`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 1
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_sparc.go b/src/runtime/internal/sys/zgoarch_sparc.go
deleted file mode 100644
index 0d08752c7bc5906e971eceae6ea834fb6f9e41ff..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_sparc.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build sparc
-// +build sparc
-
-package sys
-
-const GOARCH = `sparc`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 1
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_sparc64.go b/src/runtime/internal/sys/zgoarch_sparc64.go
deleted file mode 100644
index ba405bbf3557aa808e4435718d645c29481c00da..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_sparc64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build sparc64
-// +build sparc64
-
-package sys
-
-const GOARCH = `sparc64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 1
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_wasm.go b/src/runtime/internal/sys/zgoarch_wasm.go
deleted file mode 100644
index 7c3e5afd1ee2415c55065f21aec888dd0ec778ec..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoarch_wasm.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build wasm
-// +build wasm
-
-package sys
-
-const GOARCH = `wasm`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 1
diff --git a/src/runtime/internal/sys/zgoos_aix.go b/src/runtime/internal/sys/zgoos_aix.go
deleted file mode 100644
index f3b907471f6e4ad68a933dbed7e25a45806e9052..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_aix.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build aix
-// +build aix
-
-package sys
-
-const GOOS = `aix`
-
-const GoosAix = 1
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_android.go b/src/runtime/internal/sys/zgoos_android.go
deleted file mode 100644
index e28baf7c48103e037941ebb03f55f485c7a3e3a4..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_android.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build android
-// +build android
-
-package sys
-
-const GOOS = `android`
-
-const GoosAix = 0
-const GoosAndroid = 1
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_darwin.go b/src/runtime/internal/sys/zgoos_darwin.go
deleted file mode 100644
index 3c7f7b543eecdd2d3559c832f920d8c0a3fbd865..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_darwin.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build !ios && darwin
-// +build !ios,darwin
-
-package sys
-
-const GOOS = `darwin`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 1
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_dragonfly.go b/src/runtime/internal/sys/zgoos_dragonfly.go
deleted file mode 100644
index f844d29e2a1e552c11a1b9f57d44e9c01df97c47..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_dragonfly.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build dragonfly
-// +build dragonfly
-
-package sys
-
-const GOOS = `dragonfly`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 1
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_freebsd.go b/src/runtime/internal/sys/zgoos_freebsd.go
deleted file mode 100644
index 8999a2797af0cbce96b97239bd4b3219dbf38e96..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_freebsd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build freebsd
-// +build freebsd
-
-package sys
-
-const GOOS = `freebsd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 1
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_hurd.go b/src/runtime/internal/sys/zgoos_hurd.go
deleted file mode 100644
index a546488bf8999df89df1e98ae3195e25d5c4b913..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_hurd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build hurd
-// +build hurd
-
-package sys
-
-const GOOS = `hurd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 1
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_illumos.go b/src/runtime/internal/sys/zgoos_illumos.go
deleted file mode 100644
index 02a4ca06e82b1b54d064c1a15776f6868d332590..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_illumos.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build illumos
-// +build illumos
-
-package sys
-
-const GOOS = `illumos`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 1
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_ios.go b/src/runtime/internal/sys/zgoos_ios.go
deleted file mode 100644
index 033eec623df05375589396351cf87311315ad58e..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_ios.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ios
-// +build ios
-
-package sys
-
-const GOOS = `ios`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 1
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_js.go b/src/runtime/internal/sys/zgoos_js.go
deleted file mode 100644
index 28226ad60ad2dc94058da37c1a895f8e326d2f1f..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_js.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build js
-// +build js
-
-package sys
-
-const GOOS = `js`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 1
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_linux.go b/src/runtime/internal/sys/zgoos_linux.go
deleted file mode 100644
index 01546e4b9f26165b15cdf5f08091e083660ef545..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_linux.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build !android && linux
-// +build !android,linux
-
-package sys
-
-const GOOS = `linux`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 1
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_netbsd.go b/src/runtime/internal/sys/zgoos_netbsd.go
deleted file mode 100644
index 9d658b20ee200d9b3759c8fc5da24ad29ef1e578..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_netbsd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build netbsd
-// +build netbsd
-
-package sys
-
-const GOOS = `netbsd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 1
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_openbsd.go b/src/runtime/internal/sys/zgoos_openbsd.go
deleted file mode 100644
index 0f55454a953fec156a7cb6c5f6bf6e982ba4fab1..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_openbsd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build openbsd
-// +build openbsd
-
-package sys
-
-const GOOS = `openbsd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 1
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_plan9.go b/src/runtime/internal/sys/zgoos_plan9.go
deleted file mode 100644
index d0347464d6d25dcf55cc1069a0128b600917b32e..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_plan9.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build plan9
-// +build plan9
-
-package sys
-
-const GOOS = `plan9`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 1
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_solaris.go b/src/runtime/internal/sys/zgoos_solaris.go
deleted file mode 100644
index 05c3007e2c226077531804715ff5c386a10651eb..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_solaris.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build !illumos && solaris
-// +build !illumos,solaris
-
-package sys
-
-const GOOS = `solaris`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 1
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_windows.go b/src/runtime/internal/sys/zgoos_windows.go
deleted file mode 100644
index 7d07fa3a451150875f9710dc020da8b74a37be92..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_windows.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build windows
-// +build windows
-
-package sys
-
-const GOOS = `windows`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 1
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_zos.go b/src/runtime/internal/sys/zgoos_zos.go
deleted file mode 100644
index d6e5b9b0cb2b98b2e9edd9a678e39645723c7bb1..0000000000000000000000000000000000000000
--- a/src/runtime/internal/sys/zgoos_zos.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build zos
-// +build zos
-
-package sys
-
-const GOOS = `zos`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 1
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index cc22b0f276597e94b5e6138a4fcddb8d5e20bb5b..f8d5d48a28d7c8f7c1e35ebc013f93a166bbb42b 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -101,6 +101,8 @@
 package runtime
 
 import (
+	"internal/goarch"
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/math"
 	"runtime/internal/sys"
@@ -150,7 +152,7 @@ const (
 	//   windows/32       | 4KB        | 3
 	//   windows/64       | 8KB        | 2
 	//   plan9            | 4KB        | 3
-	_NumStackOrders = 4 - sys.PtrSize/4*sys.GoosWindows - 1*sys.GoosPlan9
+	_NumStackOrders = 4 - goarch.PtrSize/4*goos.IsWindows - 1*goos.IsPlan9
 
 	// heapAddrBits is the number of bits in a heap address. On
 	// amd64, addresses are sign-extended beyond heapAddrBits. On
@@ -207,7 +209,7 @@ const (
 	// arenaBaseOffset to offset into the top 4 GiB.
 	//
 	// WebAssembly currently has a limit of 4GB linear memory.
-	heapAddrBits = (_64bit*(1-sys.GoarchWasm)*(1-sys.GoosIos*sys.GoarchArm64))*48 + (1-_64bit+sys.GoarchWasm)*(32-(sys.GoarchMips+sys.GoarchMipsle)) + 33*sys.GoosIos*sys.GoarchArm64
+	heapAddrBits = (_64bit*(1-goarch.IsWasm)*(1-goos.IsIos*goarch.IsArm64))*48 + (1-_64bit+goarch.IsWasm)*(32-(goarch.IsMips+goarch.IsMipsle)) + 33*goos.IsIos*goarch.IsArm64
 
 	// maxAlloc is the maximum size of an allocation. On 64-bit,
 	// it's theoretically possible to allocate 1< typ.size {
 			// Array allocation. If there are any
@@ -1419,7 +1410,7 @@ func persistentalloc1(size, align uintptr, sysStat *sysMemStat) *notInHeap {
 				break
 			}
 		}
-		persistent.off = alignUp(sys.PtrSize, align)
+		persistent.off = alignUp(goarch.PtrSize, align)
 	}
 	p := persistent.base.add(persistent.off)
 	persistent.off += size
diff --git a/src/runtime/map.go b/src/runtime/map.go
index 111db56b01a2fe874767a6375b6c80d6588b3d4b..0cad1a354de3dec000c6b7fde8d3462be216e841 100644
--- a/src/runtime/map.go
+++ b/src/runtime/map.go
@@ -54,9 +54,10 @@ package runtime
 // before the table grows. Typical tables will be somewhat less loaded.
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/math"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -103,7 +104,7 @@ const (
 	sameSizeGrow = 8 // the current map growth is to a new map of the same size
 
 	// sentinel bucket ID for iterator checks
-	noCheck = 1<<(8*sys.PtrSize) - 1
+	noCheck = 1<<(8*goarch.PtrSize) - 1
 )
 
 // isEmpty reports whether the given tophash array entry represents an empty bucket entry.
@@ -182,7 +183,7 @@ type hiter struct {
 // bucketShift returns 1<> (sys.PtrSize*8 - 8))
+	top := uint8(hash >> (goarch.PtrSize*8 - 8))
 	if top < minTopHash {
 		top += minTopHash
 	}
@@ -205,11 +206,11 @@ func evacuated(b *bmap) bool {
 }
 
 func (b *bmap) overflow(t *maptype) *bmap {
-	return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-sys.PtrSize))
+	return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-goarch.PtrSize))
 }
 
 func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
-	*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-sys.PtrSize)) = ovf
+	*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-goarch.PtrSize)) = ovf
 }
 
 func (b *bmap) keys() unsafe.Pointer {
@@ -394,7 +395,7 @@ func makeBucketArray(t *maptype, b uint8, dirtyalloc unsafe.Pointer) (buckets un
 func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapaccess1)
+		pc := abi.FuncPCABIInternal(mapaccess1)
 		racereadpc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -452,7 +453,7 @@ bucketloop:
 func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapaccess2)
+		pc := abi.FuncPCABIInternal(mapaccess2)
 		racereadpc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -574,7 +575,7 @@ func mapassign(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(mapassign)
+		pc := abi.FuncPCABIInternal(mapassign)
 		racewritepc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -685,7 +686,7 @@ done:
 func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapdelete)
+		pc := abi.FuncPCABIInternal(mapdelete)
 		racewritepc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -802,14 +803,14 @@ search:
 func mapiterinit(t *maptype, h *hmap, it *hiter) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapiterinit))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiterinit))
 	}
 
 	if h == nil || h.count == 0 {
 		return
 	}
 
-	if unsafe.Sizeof(hiter{})/sys.PtrSize != 12 {
+	if unsafe.Sizeof(hiter{})/goarch.PtrSize != 12 {
 		throw("hash_iter size incorrect") // see cmd/compile/internal/reflectdata/reflect.go
 	}
 	it.t = t
@@ -852,7 +853,7 @@ func mapiternext(it *hiter) {
 	h := it.h
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapiternext))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiternext))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map iteration and map write")
@@ -978,7 +979,7 @@ next:
 func mapclear(t *maptype, h *hmap) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapclear)
+		pc := abi.FuncPCABIInternal(mapclear)
 		racewritepc(unsafe.Pointer(h), callerpc, pc)
 	}
 
@@ -1280,11 +1281,11 @@ func reflect_makemap(t *maptype, cap int) *hmap {
 	if t.key.equal == nil {
 		throw("runtime.reflect_makemap: unsupported map key type")
 	}
-	if t.key.size > maxKeySize && (!t.indirectkey() || t.keysize != uint8(sys.PtrSize)) ||
+	if t.key.size > maxKeySize && (!t.indirectkey() || t.keysize != uint8(goarch.PtrSize)) ||
 		t.key.size <= maxKeySize && (t.indirectkey() || t.keysize != uint8(t.key.size)) {
 		throw("key size wrong")
 	}
-	if t.elem.size > maxElemSize && (!t.indirectelem() || t.elemsize != uint8(sys.PtrSize)) ||
+	if t.elem.size > maxElemSize && (!t.indirectelem() || t.elemsize != uint8(goarch.PtrSize)) ||
 		t.elem.size <= maxElemSize && (t.indirectelem() || t.elemsize != uint8(t.elem.size)) {
 		throw("elem size wrong")
 	}
@@ -1363,7 +1364,7 @@ func reflect_maplen(h *hmap) int {
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(reflect_maplen))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
 	}
 	return h.count
 }
@@ -1375,7 +1376,7 @@ func reflectlite_maplen(h *hmap) int {
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(reflect_maplen))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
 	}
 	return h.count
 }
diff --git a/src/runtime/map_fast32.go b/src/runtime/map_fast32.go
index 8d52dad217afb0fabce82c73c1a27ef52345eddd..e80caeef552702c853c9f1b17c2162d619161fa5 100644
--- a/src/runtime/map_fast32.go
+++ b/src/runtime/map_fast32.go
@@ -5,14 +5,15 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
 func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_fast32))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast32))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0])
@@ -52,7 +53,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
 func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_fast32))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast32))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -95,7 +96,7 @@ func mapassign_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast32))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast32))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -185,7 +186,7 @@ func mapassign_fast32ptr(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast32))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast32))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -272,7 +273,7 @@ done:
 func mapdelete_fast32(t *maptype, h *hmap, key uint32) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_fast32))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapdelete_fast32))
 	}
 	if h == nil || h.count == 0 {
 		return
@@ -301,7 +302,7 @@ search:
 			// Only clear key if there are pointers in it.
 			// This can only happen if pointers are 32 bit
 			// wide as 64 bit pointers do not fit into a 32 bit key.
-			if sys.PtrSize == 4 && t.key.ptrdata != 0 {
+			if goarch.PtrSize == 4 && t.key.ptrdata != 0 {
 				// The key must be a pointer as we checked pointers are
 				// 32 bits wide and the key is 32 bits wide also.
 				*(*unsafe.Pointer)(k) = nil
@@ -427,7 +428,7 @@ func evacuate_fast32(t *maptype, h *hmap, oldbucket uintptr) {
 				dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
 
 				// Copy key.
-				if sys.PtrSize == 4 && t.key.ptrdata != 0 && writeBarrier.enabled {
+				if goarch.PtrSize == 4 && t.key.ptrdata != 0 && writeBarrier.enabled {
 					// Write with a write barrier.
 					*(*unsafe.Pointer)(dst.k) = *(*unsafe.Pointer)(k)
 				} else {
diff --git a/src/runtime/map_fast64.go b/src/runtime/map_fast64.go
index f1368dc774ec4de8cc6ec4071fe507ee2020d6c0..69d8872885a48ca9dcb1289314b4ed65533bffed 100644
--- a/src/runtime/map_fast64.go
+++ b/src/runtime/map_fast64.go
@@ -5,14 +5,15 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
 func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_fast64))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast64))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0])
@@ -52,7 +53,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
 func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_fast64))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast64))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -95,7 +96,7 @@ func mapassign_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast64))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast64))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -185,7 +186,7 @@ func mapassign_fast64ptr(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast64))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast64))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -272,7 +273,7 @@ done:
 func mapdelete_fast64(t *maptype, h *hmap, key uint64) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_fast64))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapdelete_fast64))
 	}
 	if h == nil || h.count == 0 {
 		return
@@ -300,7 +301,7 @@ search:
 			}
 			// Only clear key if there are pointers in it.
 			if t.key.ptrdata != 0 {
-				if sys.PtrSize == 8 {
+				if goarch.PtrSize == 8 {
 					*(*unsafe.Pointer)(k) = nil
 				} else {
 					// There are three ways to squeeze at one ore more 32 bit pointers into 64 bits.
@@ -430,7 +431,7 @@ func evacuate_fast64(t *maptype, h *hmap, oldbucket uintptr) {
 
 				// Copy key.
 				if t.key.ptrdata != 0 && writeBarrier.enabled {
-					if sys.PtrSize == 8 {
+					if goarch.PtrSize == 8 {
 						// Write with a write barrier.
 						*(*unsafe.Pointer)(dst.k) = *(*unsafe.Pointer)(k)
 					} else {
diff --git a/src/runtime/map_faststr.go b/src/runtime/map_faststr.go
index 0673dd39c8ff6a87084668400febbf64520c0fa3..4dca882c6368779f5e22a9b2a1572a3cfbe90936 100644
--- a/src/runtime/map_faststr.go
+++ b/src/runtime/map_faststr.go
@@ -5,14 +5,15 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
 func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_faststr))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_faststr))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0])
@@ -26,7 +27,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 		b := (*bmap)(h.buckets)
 		if key.len < 32 {
 			// short key, doing lots of comparisons is ok
-			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 				k := (*stringStruct)(kptr)
 				if k.len != key.len || isEmpty(b.tophash[i]) {
 					if b.tophash[i] == emptyRest {
@@ -35,14 +36,14 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 					continue
 				}
 				if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 				}
 			}
 			return unsafe.Pointer(&zeroVal[0])
 		}
 		// long key, try not to do more comparisons than necessary
 		keymaybe := uintptr(bucketCnt)
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || isEmpty(b.tophash[i]) {
 				if b.tophash[i] == emptyRest {
@@ -51,7 +52,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 				continue
 			}
 			if k.str == key.str {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 			}
 			// check first 4 bytes
 			if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) {
@@ -68,9 +69,9 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 			keymaybe = i
 		}
 		if keymaybe != bucketCnt {
-			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize))
+			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*goarch.PtrSize))
 			if memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize))
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+keymaybe*uintptr(t.elemsize))
 			}
 		}
 		return unsafe.Pointer(&zeroVal[0])
@@ -91,13 +92,13 @@ dohash:
 	}
 	top := tophash(hash)
 	for ; b != nil; b = b.overflow(t) {
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || b.tophash[i] != top {
 				continue
 			}
 			if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 			}
 		}
 	}
@@ -107,7 +108,7 @@ dohash:
 func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_faststr))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_faststr))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -121,7 +122,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 		b := (*bmap)(h.buckets)
 		if key.len < 32 {
 			// short key, doing lots of comparisons is ok
-			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 				k := (*stringStruct)(kptr)
 				if k.len != key.len || isEmpty(b.tophash[i]) {
 					if b.tophash[i] == emptyRest {
@@ -130,14 +131,14 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 					continue
 				}
 				if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
+					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize)), true
 				}
 			}
 			return unsafe.Pointer(&zeroVal[0]), false
 		}
 		// long key, try not to do more comparisons than necessary
 		keymaybe := uintptr(bucketCnt)
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || isEmpty(b.tophash[i]) {
 				if b.tophash[i] == emptyRest {
@@ -146,7 +147,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 				continue
 			}
 			if k.str == key.str {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize)), true
 			}
 			// check first 4 bytes
 			if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) {
@@ -163,9 +164,9 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 			keymaybe = i
 		}
 		if keymaybe != bucketCnt {
-			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize))
+			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*goarch.PtrSize))
 			if memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize)), true
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+keymaybe*uintptr(t.elemsize)), true
 			}
 		}
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -186,13 +187,13 @@ dohash:
 	}
 	top := tophash(hash)
 	for ; b != nil; b = b.overflow(t) {
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || b.tophash[i] != top {
 				continue
 			}
 			if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize)), true
 			}
 		}
 	}
@@ -205,7 +206,7 @@ func mapassign_faststr(t *maptype, h *hmap, s string) unsafe.Pointer {
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_faststr))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_faststr))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -245,7 +246,7 @@ bucketloop:
 				}
 				continue
 			}
-			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+i*2*sys.PtrSize))
+			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+i*2*goarch.PtrSize))
 			if k.len != key.len {
 				continue
 			}
@@ -283,13 +284,13 @@ bucketloop:
 	}
 	insertb.tophash[inserti&(bucketCnt-1)] = top // mask inserti to avoid bounds checks
 
-	insertk = add(unsafe.Pointer(insertb), dataOffset+inserti*2*sys.PtrSize)
+	insertk = add(unsafe.Pointer(insertb), dataOffset+inserti*2*goarch.PtrSize)
 	// store new key at insert position
 	*((*stringStruct)(insertk)) = *key
 	h.count++
 
 done:
-	elem := add(unsafe.Pointer(insertb), dataOffset+bucketCnt*2*sys.PtrSize+inserti*uintptr(t.elemsize))
+	elem := add(unsafe.Pointer(insertb), dataOffset+bucketCnt*2*goarch.PtrSize+inserti*uintptr(t.elemsize))
 	if h.flags&hashWriting == 0 {
 		throw("concurrent map writes")
 	}
@@ -300,7 +301,7 @@ done:
 func mapdelete_faststr(t *maptype, h *hmap, ky string) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_faststr))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapdelete_faststr))
 	}
 	if h == nil || h.count == 0 {
 		return
@@ -324,7 +325,7 @@ func mapdelete_faststr(t *maptype, h *hmap, ky string) {
 	top := tophash(hash)
 search:
 	for ; b != nil; b = b.overflow(t) {
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || b.tophash[i] != top {
 				continue
@@ -334,7 +335,7 @@ search:
 			}
 			// Clear key's pointer.
 			k.str = nil
-			e := add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+			e := add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 			if t.elem.ptrdata != 0 {
 				memclrHasPointers(e, t.elem.size)
 			} else {
@@ -410,7 +411,7 @@ func evacuate_faststr(t *maptype, h *hmap, oldbucket uintptr) {
 		x := &xy[0]
 		x.b = (*bmap)(add(h.buckets, oldbucket*uintptr(t.bucketsize)))
 		x.k = add(unsafe.Pointer(x.b), dataOffset)
-		x.e = add(x.k, bucketCnt*2*sys.PtrSize)
+		x.e = add(x.k, bucketCnt*2*goarch.PtrSize)
 
 		if !h.sameSizeGrow() {
 			// Only calculate y pointers if we're growing bigger.
@@ -418,13 +419,13 @@ func evacuate_faststr(t *maptype, h *hmap, oldbucket uintptr) {
 			y := &xy[1]
 			y.b = (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.bucketsize)))
 			y.k = add(unsafe.Pointer(y.b), dataOffset)
-			y.e = add(y.k, bucketCnt*2*sys.PtrSize)
+			y.e = add(y.k, bucketCnt*2*goarch.PtrSize)
 		}
 
 		for ; b != nil; b = b.overflow(t) {
 			k := add(unsafe.Pointer(b), dataOffset)
-			e := add(k, bucketCnt*2*sys.PtrSize)
-			for i := 0; i < bucketCnt; i, k, e = i+1, add(k, 2*sys.PtrSize), add(e, uintptr(t.elemsize)) {
+			e := add(k, bucketCnt*2*goarch.PtrSize)
+			for i := 0; i < bucketCnt; i, k, e = i+1, add(k, 2*goarch.PtrSize), add(e, uintptr(t.elemsize)) {
 				top := b.tophash[i]
 				if isEmpty(top) {
 					b.tophash[i] = evacuatedEmpty
@@ -450,7 +451,7 @@ func evacuate_faststr(t *maptype, h *hmap, oldbucket uintptr) {
 					dst.b = h.newoverflow(t, dst.b)
 					dst.i = 0
 					dst.k = add(unsafe.Pointer(dst.b), dataOffset)
-					dst.e = add(dst.k, bucketCnt*2*sys.PtrSize)
+					dst.e = add(dst.k, bucketCnt*2*goarch.PtrSize)
 				}
 				dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
 
@@ -463,7 +464,7 @@ func evacuate_faststr(t *maptype, h *hmap, oldbucket uintptr) {
 				// key or elem arrays.  That's ok, as we have the overflow pointer
 				// at the end of the bucket to protect against pointing past the
 				// end of the bucket.
-				dst.k = add(dst.k, 2*sys.PtrSize)
+				dst.k = add(dst.k, 2*goarch.PtrSize)
 				dst.e = add(dst.e, uintptr(t.elemsize))
 			}
 		}
diff --git a/src/runtime/map_test.go b/src/runtime/map_test.go
index 302b3c23c12b4280d5839584cc0566bdfc1d01bb..24556b4093c32e44e8c2ab8e79e4a20422194bd0 100644
--- a/src/runtime/map_test.go
+++ b/src/runtime/map_test.go
@@ -6,10 +6,10 @@ package runtime_test
 
 import (
 	"fmt"
+	"internal/goarch"
 	"math"
 	"reflect"
 	"runtime"
-	"runtime/internal/sys"
 	"sort"
 	"strconv"
 	"strings"
@@ -21,7 +21,7 @@ func TestHmapSize(t *testing.T) {
 	// The structure of hmap is defined in runtime/map.go
 	// and in cmd/compile/internal/gc/reflect.go and must be in sync.
 	// The size of hmap should be 48 bytes on 64 bit and 28 bytes on 32 bit platforms.
-	var hmapSize = uintptr(8 + 5*sys.PtrSize)
+	var hmapSize = uintptr(8 + 5*goarch.PtrSize)
 	if runtime.RuntimeHmapSize != hmapSize {
 		t.Errorf("sizeof(runtime.hmap{})==%d, want %d", runtime.RuntimeHmapSize, hmapSize)
 	}
diff --git a/src/runtime/mbarrier.go b/src/runtime/mbarrier.go
index 4994347bdeb35610d1f45efb714b233004835105..3fd1cca42cc2f2c0e4b808b56ee6ca4617fee92b 100644
--- a/src/runtime/mbarrier.go
+++ b/src/runtime/mbarrier.go
@@ -15,7 +15,7 @@ package runtime
 
 import (
 	"internal/abi"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -177,8 +177,8 @@ func typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 //go:linkname reflect_typedmemmove reflect.typedmemmove
 func reflect_typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 	if raceenabled {
-		raceWriteObjectPC(typ, dst, getcallerpc(), funcPC(reflect_typedmemmove))
-		raceReadObjectPC(typ, src, getcallerpc(), funcPC(reflect_typedmemmove))
+		raceWriteObjectPC(typ, dst, getcallerpc(), abi.FuncPCABIInternal(reflect_typedmemmove))
+		raceReadObjectPC(typ, src, getcallerpc(), abi.FuncPCABIInternal(reflect_typedmemmove))
 	}
 	if msanenabled {
 		msanwrite(dst, typ.size)
@@ -197,11 +197,11 @@ func reflectlite_typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 // off must be a multiple of sys.PtrSize.
 //go:linkname reflect_typedmemmovepartial reflect.typedmemmovepartial
 func reflect_typedmemmovepartial(typ *_type, dst, src unsafe.Pointer, off, size uintptr) {
-	if writeBarrier.needed && typ.ptrdata > off && size >= sys.PtrSize {
-		if off&(sys.PtrSize-1) != 0 {
+	if writeBarrier.needed && typ.ptrdata > off && size >= goarch.PtrSize {
+		if off&(goarch.PtrSize-1) != 0 {
 			panic("reflect: internal error: misaligned offset")
 		}
-		pwsize := alignDown(size, sys.PtrSize)
+		pwsize := alignDown(size, goarch.PtrSize)
 		if poff := typ.ptrdata - off; pwsize > poff {
 			pwsize = poff
 		}
@@ -225,7 +225,7 @@ func reflect_typedmemmovepartial(typ *_type, dst, src unsafe.Pointer, off, size
 //
 //go:nosplit
 func reflectcallmove(typ *_type, dst, src unsafe.Pointer, size uintptr, regs *abi.RegArgs) {
-	if writeBarrier.needed && typ != nil && typ.ptrdata != 0 && size >= sys.PtrSize {
+	if writeBarrier.needed && typ != nil && typ.ptrdata != 0 && size >= goarch.PtrSize {
 		bulkBarrierPreWrite(uintptr(dst), uintptr(src), size)
 	}
 	memmove(dst, src, size)
@@ -254,7 +254,7 @@ func typedslicecopy(typ *_type, dstPtr unsafe.Pointer, dstLen int, srcPtr unsafe
 	// code and needs its own instrumentation.
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(slicecopy)
+		pc := abi.FuncPCABIInternal(slicecopy)
 		racewriterangepc(dstPtr, uintptr(n)*typ.size, callerpc, pc)
 		racereadrangepc(srcPtr, uintptr(n)*typ.size, callerpc, pc)
 	}
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index 32b8db7a50282c70785615902af017232280bc35..9363409e361c11dfce0b03061fc4f11bcd5de8c3 100644
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -46,6 +46,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -326,8 +327,8 @@ func heapBitsForAddr(addr uintptr) (h heapBits) {
 		// we expect to crash in the caller.
 		return
 	}
-	h.bitp = &ha.bitmap[(addr/(sys.PtrSize*4))%heapArenaBitmapBytes]
-	h.shift = uint32((addr / sys.PtrSize) & 3)
+	h.bitp = &ha.bitmap[(addr/(goarch.PtrSize*4))%heapArenaBitmapBytes]
+	h.shift = uint32((addr / goarch.PtrSize) & 3)
 	h.arena = uint32(arena)
 	h.last = &ha.bitmap[len(ha.bitmap)-1]
 	return
@@ -386,10 +387,10 @@ func findObject(p, refBase, refOff uintptr) (base uintptr, s *mspan, objIndex ui
 	// If s is nil, the virtual address has never been part of the heap.
 	// This pointer may be to some mmap'd region, so we allow it.
 	if s == nil {
-		if GOARCH == "amd64" && p == clobberdeadPtr && debug.invalidptr != 0 {
-			// Crash if clobberdeadPtr is seen. Only on AMD64 for now, as
-			// it is the only platform where compiler's clobberdead mode is
-			// implemented. On AMD64 clobberdeadPtr cannot be a valid address.
+		if (GOARCH == "amd64" || GOARCH == "arm64") && p == clobberdeadPtr && debug.invalidptr != 0 {
+			// Crash if clobberdeadPtr is seen. Only on AMD64 and ARM64 for now,
+			// as they are the only platform where compiler's clobberdead mode is
+			// implemented. On these platforms clobberdeadPtr cannot be a valid address.
 			badPointer(s, p, refBase, refOff)
 		}
 		return
@@ -557,7 +558,7 @@ func (h heapBits) isPointer() bool {
 //
 //go:nosplit
 func bulkBarrierPreWrite(dst, src, size uintptr) {
-	if (dst|src|size)&(sys.PtrSize-1) != 0 {
+	if (dst|src|size)&(goarch.PtrSize-1) != 0 {
 		throw("bulkBarrierPreWrite: unaligned arguments")
 	}
 	if !writeBarrier.needed {
@@ -592,7 +593,7 @@ func bulkBarrierPreWrite(dst, src, size uintptr) {
 	buf := &getg().m.p.ptr().wbBuf
 	h := heapBitsForAddr(dst)
 	if src == 0 {
-		for i := uintptr(0); i < size; i += sys.PtrSize {
+		for i := uintptr(0); i < size; i += goarch.PtrSize {
 			if h.isPointer() {
 				dstx := (*uintptr)(unsafe.Pointer(dst + i))
 				if !buf.putFast(*dstx, 0) {
@@ -602,7 +603,7 @@ func bulkBarrierPreWrite(dst, src, size uintptr) {
 			h = h.next()
 		}
 	} else {
-		for i := uintptr(0); i < size; i += sys.PtrSize {
+		for i := uintptr(0); i < size; i += goarch.PtrSize {
 			if h.isPointer() {
 				dstx := (*uintptr)(unsafe.Pointer(dst + i))
 				srcx := (*uintptr)(unsafe.Pointer(src + i))
@@ -625,7 +626,7 @@ func bulkBarrierPreWrite(dst, src, size uintptr) {
 // created and zeroed with malloc.
 //go:nosplit
 func bulkBarrierPreWriteSrcOnly(dst, src, size uintptr) {
-	if (dst|src|size)&(sys.PtrSize-1) != 0 {
+	if (dst|src|size)&(goarch.PtrSize-1) != 0 {
 		throw("bulkBarrierPreWrite: unaligned arguments")
 	}
 	if !writeBarrier.needed {
@@ -633,7 +634,7 @@ func bulkBarrierPreWriteSrcOnly(dst, src, size uintptr) {
 	}
 	buf := &getg().m.p.ptr().wbBuf
 	h := heapBitsForAddr(dst)
-	for i := uintptr(0); i < size; i += sys.PtrSize {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
 		if h.isPointer() {
 			srcx := (*uintptr)(unsafe.Pointer(src + i))
 			if !buf.putFast(0, *srcx) {
@@ -653,17 +654,17 @@ func bulkBarrierPreWriteSrcOnly(dst, src, size uintptr) {
 //
 //go:nosplit
 func bulkBarrierBitmap(dst, src, size, maskOffset uintptr, bits *uint8) {
-	word := maskOffset / sys.PtrSize
+	word := maskOffset / goarch.PtrSize
 	bits = addb(bits, word/8)
 	mask := uint8(1) << (word % 8)
 
 	buf := &getg().m.p.ptr().wbBuf
-	for i := uintptr(0); i < size; i += sys.PtrSize {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
 		if mask == 0 {
 			bits = addb(bits, 1)
 			if *bits == 0 {
 				// Skip 8 words.
-				i += 7 * sys.PtrSize
+				i += 7 * goarch.PtrSize
 				continue
 			}
 			mask = 1
@@ -720,8 +721,8 @@ func typeBitsBulkBarrier(typ *_type, dst, src, size uintptr) {
 	ptrmask := typ.gcdata
 	buf := &getg().m.p.ptr().wbBuf
 	var bits uint32
-	for i := uintptr(0); i < typ.ptrdata; i += sys.PtrSize {
-		if i&(sys.PtrSize*8-1) == 0 {
+	for i := uintptr(0); i < typ.ptrdata; i += goarch.PtrSize {
+		if i&(goarch.PtrSize*8-1) == 0 {
 			bits = uint32(*ptrmask)
 			ptrmask = addb(ptrmask, 1)
 		} else {
@@ -751,14 +752,14 @@ func typeBitsBulkBarrier(typ *_type, dst, src, size uintptr) {
 // Otherwise, it initializes all words to scalar/dead.
 func (h heapBits) initSpan(s *mspan) {
 	// Clear bits corresponding to objects.
-	nw := (s.npages << _PageShift) / sys.PtrSize
+	nw := (s.npages << _PageShift) / goarch.PtrSize
 	if nw%wordsPerBitmapByte != 0 {
 		throw("initSpan: unaligned length")
 	}
 	if h.shift != 0 {
 		throw("initSpan: unaligned base")
 	}
-	isPtrs := sys.PtrSize == 8 && s.elemsize == sys.PtrSize
+	isPtrs := goarch.PtrSize == 8 && s.elemsize == goarch.PtrSize
 	for nw > 0 {
 		hNext, anw := h.forwardOrBoundary(nw)
 		nbyte := anw / wordsPerBitmapByte
@@ -836,7 +837,7 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) {
 	// The checks for size == sys.PtrSize and size == 2*sys.PtrSize can therefore
 	// assume that dataSize == size without checking it explicitly.
 
-	if sys.PtrSize == 8 && size == sys.PtrSize {
+	if goarch.PtrSize == 8 && size == goarch.PtrSize {
 		// It's one word and it has pointers, it must be a pointer.
 		// Since all allocated one-word objects are pointers
 		// (non-pointers are aggregated into tinySize allocations),
@@ -862,8 +863,8 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) {
 	// objects are at least 4 words long and that their bitmaps start either at the beginning
 	// of a bitmap byte, or half-way in (h.shift of 0 and 2 respectively).
 
-	if size == 2*sys.PtrSize {
-		if typ.size == sys.PtrSize {
+	if size == 2*goarch.PtrSize {
+		if typ.size == goarch.PtrSize {
 			// We're allocating a block big enough to hold two pointers.
 			// On 64-bit, that means the actual object must be two pointers,
 			// or else we'd have used the one-pointer-sized block.
@@ -872,7 +873,7 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) {
 			// just the smallest block available. Distinguish by checking dataSize.
 			// (In general the number of instances of typ being allocated is
 			// dataSize/typ.size.)
-			if sys.PtrSize == 4 && dataSize == sys.PtrSize {
+			if goarch.PtrSize == 4 && dataSize == goarch.PtrSize {
 				// 1 pointer object. On 32-bit machines clear the bit for the
 				// unused second word.
 				*h.bitp &^= (bitPointer | bitScan | (bitPointer|bitScan)<> h.shift) & (bitPointer | bitScan)
@@ -1446,7 +1447,7 @@ Phase4:
 				print("initial bits h0.bitp=", h0.bitp, " h0.shift=", h0.shift, "\n")
 				print("current bits h.bitp=", h.bitp, " h.shift=", h.shift, " *h.bitp=", hex(*h.bitp), "\n")
 				print("ptrmask=", ptrmask, " p=", p, " endp=", endp, " endnb=", endnb, " pbits=", hex(pbits), " b=", hex(b), " nb=", nb, "\n")
-				println("at word", i, "offset", i*sys.PtrSize, "have", hex(have), "want", hex(want))
+				println("at word", i, "offset", i*goarch.PtrSize, "have", hex(have), "want", hex(want))
 				if typ.kind&kindGCProg != 0 {
 					println("GC program:")
 					dumpGCProg(addb(typ.gcdata, 4))
@@ -1477,14 +1478,14 @@ var debugPtrmask struct {
 // so that the relevant bitmap bytes are not shared with surrounding
 // objects.
 func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize uintptr, prog *byte) {
-	if sys.PtrSize == 8 && allocSize%(4*sys.PtrSize) != 0 {
+	if goarch.PtrSize == 8 && allocSize%(4*goarch.PtrSize) != 0 {
 		// Alignment will be wrong.
 		throw("heapBitsSetTypeGCProg: small allocation")
 	}
 	var totalBits uintptr
 	if elemSize == dataSize {
 		totalBits = runGCProg(prog, nil, h.bitp, 2)
-		if totalBits*sys.PtrSize != progSize {
+		if totalBits*goarch.PtrSize != progSize {
 			println("runtime: heapBitsSetTypeGCProg: total bits", totalBits, "but progSize", progSize)
 			throw("heapBitsSetTypeGCProg: unexpected bit count")
 		}
@@ -1499,7 +1500,7 @@ func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize u
 		// repeats that first element to fill the array.
 		var trailer [40]byte // 3 varints (max 10 each) + some bytes
 		i := 0
-		if n := elemSize/sys.PtrSize - progSize/sys.PtrSize; n > 0 {
+		if n := elemSize/goarch.PtrSize - progSize/goarch.PtrSize; n > 0 {
 			// literal(0)
 			trailer[i] = 0x01
 			i++
@@ -1521,7 +1522,7 @@ func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize u
 		// repeat(elemSize/ptrSize, count-1)
 		trailer[i] = 0x80
 		i++
-		n := elemSize / sys.PtrSize
+		n := elemSize / goarch.PtrSize
 		for ; n >= 0x80; n >>= 7 {
 			trailer[i] = byte(n | 0x80)
 			i++
@@ -1545,10 +1546,10 @@ func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize u
 		// last element. This will cause the code below to
 		// memclr the dead section of the final array element,
 		// so that scanobject can stop early in the final element.
-		totalBits = (elemSize*(count-1) + progSize) / sys.PtrSize
+		totalBits = (elemSize*(count-1) + progSize) / goarch.PtrSize
 	}
 	endProg := unsafe.Pointer(addb(h.bitp, (totalBits+3)/4))
-	endAlloc := unsafe.Pointer(addb(h.bitp, allocSize/sys.PtrSize/wordsPerBitmapByte))
+	endAlloc := unsafe.Pointer(addb(h.bitp, allocSize/goarch.PtrSize/wordsPerBitmapByte))
 	memclrNoHeapPointers(endProg, uintptr(endAlloc)-uintptr(endProg))
 }
 
@@ -1556,7 +1557,7 @@ func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize u
 // size the size of the region described by prog, in bytes.
 // The resulting bitvector will have no more than size/sys.PtrSize bits.
 func progToPointerMask(prog *byte, size uintptr) bitvector {
-	n := (size/sys.PtrSize + 7) / 8
+	n := (size/goarch.PtrSize + 7) / 8
 	x := (*[1 << 30]byte)(persistentalloc(n+1, 1, &memstats.buckhash_sys))[:n+1]
 	x[len(x)-1] = 0xa1 // overflow check sentinel
 	n = runGCProg(prog, nil, &x[0], 1)
@@ -1691,7 +1692,7 @@ Run:
 		// the pattern to a bit buffer holding at most 7 bits (a partial byte)
 		// it will not overflow.
 		src := dst
-		const maxBits = sys.PtrSize*8 - 7
+		const maxBits = goarch.PtrSize*8 - 7
 		if n <= maxBits {
 			// Start with bits in output buffer.
 			pattern := bits
@@ -1744,7 +1745,7 @@ Run:
 				nb := npattern
 				if nb+nb <= maxBits {
 					// Double pattern until the whole uintptr is filled.
-					for nb <= sys.PtrSize*8 {
+					for nb <= goarch.PtrSize*8 {
 						b |= b << nb
 						nb += nb
 					}
@@ -1872,7 +1873,7 @@ Run:
 // The result must be deallocated with dematerializeGCProg.
 func materializeGCProg(ptrdata uintptr, prog *byte) *mspan {
 	// Each word of ptrdata needs one bit in the bitmap.
-	bitmapBytes := divRoundUp(ptrdata, 8*sys.PtrSize)
+	bitmapBytes := divRoundUp(ptrdata, 8*goarch.PtrSize)
 	// Compute the number of pages needed for bitmapBytes.
 	pages := divRoundUp(bitmapBytes, pageSize)
 	s := mheap_.allocManual(pages, spanAllocPtrScalarBits)
@@ -1945,7 +1946,7 @@ func getgcmaskcb(frame *stkframe, ctxt unsafe.Pointer) bool {
 func reflect_gcbits(x interface{}) []byte {
 	ret := getgcmask(x)
 	typ := (*ptrtype)(unsafe.Pointer(efaceOf(&x)._type)).elem
-	nptr := typ.ptrdata / sys.PtrSize
+	nptr := typ.ptrdata / goarch.PtrSize
 	for uintptr(len(ret)) > nptr && ret[len(ret)-1] == 0 {
 		ret = ret[:len(ret)-1]
 	}
@@ -1965,10 +1966,10 @@ func getgcmask(ep interface{}) (mask []byte) {
 		if datap.data <= uintptr(p) && uintptr(p) < datap.edata {
 			bitmap := datap.gcdatamask.bytedata
 			n := (*ptrtype)(unsafe.Pointer(t)).elem.size
-			mask = make([]byte, n/sys.PtrSize)
-			for i := uintptr(0); i < n; i += sys.PtrSize {
-				off := (uintptr(p) + i - datap.data) / sys.PtrSize
-				mask[i/sys.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
+			mask = make([]byte, n/goarch.PtrSize)
+			for i := uintptr(0); i < n; i += goarch.PtrSize {
+				off := (uintptr(p) + i - datap.data) / goarch.PtrSize
+				mask[i/goarch.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
 			}
 			return
 		}
@@ -1977,10 +1978,10 @@ func getgcmask(ep interface{}) (mask []byte) {
 		if datap.bss <= uintptr(p) && uintptr(p) < datap.ebss {
 			bitmap := datap.gcbssmask.bytedata
 			n := (*ptrtype)(unsafe.Pointer(t)).elem.size
-			mask = make([]byte, n/sys.PtrSize)
-			for i := uintptr(0); i < n; i += sys.PtrSize {
-				off := (uintptr(p) + i - datap.bss) / sys.PtrSize
-				mask[i/sys.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
+			mask = make([]byte, n/goarch.PtrSize)
+			for i := uintptr(0); i < n; i += goarch.PtrSize {
+				off := (uintptr(p) + i - datap.bss) / goarch.PtrSize
+				mask[i/goarch.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
 			}
 			return
 		}
@@ -1990,13 +1991,13 @@ func getgcmask(ep interface{}) (mask []byte) {
 	if base, s, _ := findObject(uintptr(p), 0, 0); base != 0 {
 		hbits := heapBitsForAddr(base)
 		n := s.elemsize
-		mask = make([]byte, n/sys.PtrSize)
-		for i := uintptr(0); i < n; i += sys.PtrSize {
+		mask = make([]byte, n/goarch.PtrSize)
+		for i := uintptr(0); i < n; i += goarch.PtrSize {
 			if hbits.isPointer() {
-				mask[i/sys.PtrSize] = 1
+				mask[i/goarch.PtrSize] = 1
 			}
 			if !hbits.morePointers() {
-				mask = mask[:i/sys.PtrSize]
+				mask = mask[:i/goarch.PtrSize]
 				break
 			}
 			hbits = hbits.next()
@@ -2015,12 +2016,12 @@ func getgcmask(ep interface{}) (mask []byte) {
 			if locals.n == 0 {
 				return
 			}
-			size := uintptr(locals.n) * sys.PtrSize
+			size := uintptr(locals.n) * goarch.PtrSize
 			n := (*ptrtype)(unsafe.Pointer(t)).elem.size
-			mask = make([]byte, n/sys.PtrSize)
-			for i := uintptr(0); i < n; i += sys.PtrSize {
-				off := (uintptr(p) + i - frame.varp + size) / sys.PtrSize
-				mask[i/sys.PtrSize] = locals.ptrbit(off)
+			mask = make([]byte, n/goarch.PtrSize)
+			for i := uintptr(0); i < n; i += goarch.PtrSize {
+				off := (uintptr(p) + i - frame.varp + size) / goarch.PtrSize
+				mask[i/goarch.PtrSize] = locals.ptrbit(off)
 			}
 		}
 		return
diff --git a/src/runtime/mcheckmark.go b/src/runtime/mcheckmark.go
index ba80ac1bdf4d6070037a0a02ec46e2380797034b..1dd28585f1c03970f7e7030feb9cf7ed69b30b2e 100644
--- a/src/runtime/mcheckmark.go
+++ b/src/runtime/mcheckmark.go
@@ -13,8 +13,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -24,7 +24,7 @@ import (
 // allocation.
 //
 //go:notinheap
-type checkmarksMap [heapArenaBytes / sys.PtrSize / 8]uint8
+type checkmarksMap [heapArenaBytes / goarch.PtrSize / 8]uint8
 
 // If useCheckmark is true, marking of an object uses the checkmark
 // bits instead of the standard mark bits.
diff --git a/src/runtime/memclr_386.s b/src/runtime/memclr_386.s
index 046c3441198bf5e4c44b29fe524e8e50d9ca17ca..2627792ced076a308a9410204dbbe51a8f0f8c6d 100644
--- a/src/runtime/memclr_386.s
+++ b/src/runtime/memclr_386.s
@@ -30,8 +30,9 @@ tail:
 	JBE	_5through8
 	CMPL	BX, $16
 	JBE	_9through16
-	CMPB	internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE	nosse2
+#ifdef GO386_softfloat
+	JMP	nosse2
+#endif
 	PXOR	X0, X0
 	CMPL	BX, $32
 	JBE	_17through32
diff --git a/src/runtime/memclr_amd64.s b/src/runtime/memclr_amd64.s
index a10f57bd8cbe3bf16d4ad7496b5f5bd478c8fb2a..918a4b9e0e416cedd7808ea541a71a36c0b7dcba 100644
--- a/src/runtime/memclr_amd64.s
+++ b/src/runtime/memclr_amd64.s
@@ -13,14 +13,9 @@
 // func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
 // ABIInternal for performance.
 TEXT runtime·memclrNoHeapPointers(SB), NOSPLIT, $0-16
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr
 	// BX = n
 	MOVQ	AX, DI	// DI = ptr
-#else
-	MOVQ	ptr+0(FP), DI
-	MOVQ	n+8(FP), BX
-#endif
 	XORQ	AX, AX
 
 	// MOVOU seems always faster than REP STOSQ.
@@ -37,9 +32,6 @@ tail:
 	JE	_8
 	CMPQ	BX, $16
 	JBE	_9through16
-#ifndef GOEXPERIMENT_regabig
-	PXOR	X15, X15
-#endif
 	CMPQ	BX, $32
 	JBE	_17through32
 	CMPQ	BX, $64
diff --git a/src/runtime/memclr_arm64.s b/src/runtime/memclr_arm64.s
index c1a0dcef584fa1c03eba2f71fa99b1066b91dd69..b80cca6a1cd0bb8469a94173fc2fb74111b32282 100644
--- a/src/runtime/memclr_arm64.s
+++ b/src/runtime/memclr_arm64.s
@@ -8,9 +8,11 @@
 
 // func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
 // Also called from assembly in sys_windows_arm64.s without g (but using Go stack convention).
-TEXT runtime·memclrNoHeapPointers(SB),NOSPLIT,$0-16
+TEXT runtime·memclrNoHeapPointers(SB),NOSPLIT,$0-16
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	ptr+0(FP), R0
 	MOVD	n+8(FP), R1
+#endif
 
 	CMP	$16, R1
 	// If n is equal to 16 bytes, use zero_exact_16 to zero
diff --git a/src/runtime/memmove_386.s b/src/runtime/memmove_386.s
index 1a43a1f724d7330f001c7fc5636356216ae8812c..389ef8847712e0d8adf982b9e20171118233ec73 100644
--- a/src/runtime/memmove_386.s
+++ b/src/runtime/memmove_386.s
@@ -55,8 +55,9 @@ tail:
 	JBE	move_5through8
 	CMPL	BX, $16
 	JBE	move_9through16
-	CMPB	internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE	nosse2
+#ifdef GO386_softfloat
+	JMP	nosse2
+#endif
 	CMPL	BX, $32
 	JBE	move_17through32
 	CMPL	BX, $64
diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s
index 24c6529f58405471af326f95f9b2b311f1868df7..fa0c0e414f48c7e947159d4e68032da8b55fed80 100644
--- a/src/runtime/memmove_amd64.s
+++ b/src/runtime/memmove_amd64.s
@@ -34,18 +34,12 @@
 // func memmove(to, from unsafe.Pointer, n uintptr)
 // ABIInternal for performance.
 TEXT runtime·memmove(SB), NOSPLIT, $0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = to
 	// BX = from
 	// CX = n
 	MOVQ	AX, DI
 	MOVQ	BX, SI
 	MOVQ	CX, BX
-#else
-	MOVQ	to+0(FP), DI
-	MOVQ	from+8(FP), SI
-	MOVQ	n+16(FP), BX
-#endif
 
 	// REP instructions have a high startup cost, so we handle small sizes
 	// with some straightline code. The REP MOVSQ instruction is really fast
@@ -254,10 +248,8 @@ move_129through256:
 	MOVOU	X13, -48(DI)(BX*1)
 	MOVOU	X14, -32(DI)(BX*1)
 	MOVOU	X15, -16(DI)(BX*1)
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 	RET
 move_256through2048:
 	SUBQ	$256, BX
@@ -297,10 +289,8 @@ move_256through2048:
 	LEAQ	256(SI), SI
 	LEAQ	256(DI), DI
 	JGE	move_256through2048
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 	JMP	tail
 
 avxUnaligned:
diff --git a/src/runtime/memmove_arm64.s b/src/runtime/memmove_arm64.s
index 43d27629e5bd13435107324502f43d0d70a7d792..bee3b00c47d81c2cefeb9a2e9df14c458d574014 100644
--- a/src/runtime/memmove_arm64.s
+++ b/src/runtime/memmove_arm64.s
@@ -26,10 +26,12 @@
 // The loop tail is handled by always copying 64 bytes from the end.
 
 // func memmove(to, from unsafe.Pointer, n uintptr)
-TEXT runtime·memmove(SB), NOSPLIT|NOFRAME, $0-24
+TEXT runtime·memmove(SB), NOSPLIT|NOFRAME, $0-24
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	to+0(FP), R0
 	MOVD	from+8(FP), R1
 	MOVD	n+16(FP), R2
+#endif
 	CBZ	R2, copy0
 
 	// Small copies: 1..16 bytes
diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go
index fd318d49a8d20475713b0b0482fb811a79b2fea3..3cdb81e2fb96542761deef366db86b4112dbaaed 100644
--- a/src/runtime/mfinal.go
+++ b/src/runtime/mfinal.go
@@ -8,8 +8,8 @@ package runtime
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -26,14 +26,14 @@ type finblock struct {
 	next    *finblock
 	cnt     uint32
 	_       int32
-	fin     [(_FinBlockSize - 2*sys.PtrSize - 2*4) / unsafe.Sizeof(finalizer{})]finalizer
+	fin     [(_FinBlockSize - 2*goarch.PtrSize - 2*4) / unsafe.Sizeof(finalizer{})]finalizer
 }
 
 var finlock mutex  // protects the following variables
 var fing *g        // goroutine that runs finalizers
 var finq *finblock // list of finalizers that are to be executed
 var finc *finblock // cache of free blocks
-var finptrmask [_FinBlockSize / sys.PtrSize / 8]byte
+var finptrmask [_FinBlockSize / goarch.PtrSize / 8]byte
 var fingwait bool
 var fingwake bool
 var allfin *finblock // list of all blocks
@@ -95,12 +95,12 @@ func queuefinalizer(p unsafe.Pointer, fn *funcval, nret uintptr, fint *_type, ot
 			if finptrmask[0] == 0 {
 				// Build pointer mask for Finalizer array in block.
 				// Check assumptions made in finalizer1 array above.
-				if (unsafe.Sizeof(finalizer{}) != 5*sys.PtrSize ||
+				if (unsafe.Sizeof(finalizer{}) != 5*goarch.PtrSize ||
 					unsafe.Offsetof(finalizer{}.fn) != 0 ||
-					unsafe.Offsetof(finalizer{}.arg) != sys.PtrSize ||
-					unsafe.Offsetof(finalizer{}.nret) != 2*sys.PtrSize ||
-					unsafe.Offsetof(finalizer{}.fint) != 3*sys.PtrSize ||
-					unsafe.Offsetof(finalizer{}.ot) != 4*sys.PtrSize) {
+					unsafe.Offsetof(finalizer{}.arg) != goarch.PtrSize ||
+					unsafe.Offsetof(finalizer{}.nret) != 2*goarch.PtrSize ||
+					unsafe.Offsetof(finalizer{}.fint) != 3*goarch.PtrSize ||
+					unsafe.Offsetof(finalizer{}.ot) != 4*goarch.PtrSize) {
 					throw("finalizer out of sync")
 				}
 				for i := range finptrmask {
@@ -432,7 +432,7 @@ okarg:
 	for _, t := range ft.out() {
 		nret = alignUp(nret, uintptr(t.align)) + uintptr(t.size)
 	}
-	nret = alignUp(nret, sys.PtrSize)
+	nret = alignUp(nret, goarch.PtrSize)
 
 	// make sure we have a finalizer goroutine
 	createfing()
@@ -466,6 +466,10 @@ okarg:
 // Without the KeepAlive call, the finalizer could run at the start of
 // syscall.Read, closing the file descriptor before syscall.Read makes
 // the actual system call.
+//
+// Note: KeepAlive should only be used to prevent finalizers from
+// running prematurely. In particular, when used with unsafe.Pointer,
+// the rules for valid uses of unsafe.Pointer still apply.
 func KeepAlive(x interface{}) {
 	// Introduce a use of x that the compiler can't eliminate.
 	// This makes sure x is alive on entry. We need x to be alive
diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 458566353536f5f0af5286aeb35ef971430fc6ff..34b5b482a355b634d2f2b9b85d120ca4981afd9e 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -167,22 +167,17 @@ func gcinit() {
 	lockInit(&work.wbufSpans.lock, lockRankWbufSpans)
 }
 
-// Temporary in order to enable register ABI work.
-// TODO(register args): convert back to local chan in gcenabled, passed to "go" stmts.
-var gcenable_setup chan int
-
 // gcenable is called after the bulk of the runtime initialization,
 // just before we're about to start letting user code run.
 // It kicks off the background sweeper goroutine, the background
 // scavenger goroutine, and enables GC.
 func gcenable() {
 	// Kick off sweeping and scavenging.
-	gcenable_setup = make(chan int, 2)
-	go bgsweep()
-	go bgscavenge()
-	<-gcenable_setup
-	<-gcenable_setup
-	gcenable_setup = nil
+	c := make(chan int, 2)
+	go bgsweep(c)
+	go bgscavenge(c)
+	<-c
+	<-c
 	memstats.enablegc = true // now that runtime is initialized, GC is okay
 }
 
@@ -1563,19 +1558,17 @@ func clearpools() {
 	sched.sudogcache = nil
 	unlock(&sched.sudoglock)
 
-	// Clear central defer pools.
+	// Clear central defer pool.
 	// Leave per-P pools alone, they have strictly bounded size.
 	lock(&sched.deferlock)
-	for i := range sched.deferpool {
-		// disconnect cached list before dropping it on the floor,
-		// so that a dangling ref to one entry does not pin all of them.
-		var d, dlink *_defer
-		for d = sched.deferpool[i]; d != nil; d = dlink {
-			dlink = d.link
-			d.link = nil
-		}
-		sched.deferpool[i] = nil
+	// disconnect cached list before dropping it on the floor,
+	// so that a dangling ref to one entry does not pin all of them.
+	var d, dlink *_defer
+	for d = sched.deferpool; d != nil; d = dlink {
+		dlink = d.link
+		d.link = nil
 	}
+	sched.deferpool = nil
 	unlock(&sched.deferlock)
 }
 
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 1fd0732d62dcc6b8a0831701d535bf322d08d9dc..874d9107209c0448368a1b90e5f2a0d9249b1b87 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -7,8 +7,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -245,7 +245,7 @@ func markroot(gcw *gcWork, i uint32) {
 //
 //go:nowritebarrier
 func markrootBlock(b0, n0 uintptr, ptrmask0 *uint8, gcw *gcWork, shard int) {
-	if rootBlockBytes%(8*sys.PtrSize) != 0 {
+	if rootBlockBytes%(8*goarch.PtrSize) != 0 {
 		// This is necessary to pick byte offsets in ptrmask0.
 		throw("rootBlockBytes must be a multiple of 8*ptrSize")
 	}
@@ -258,7 +258,7 @@ func markrootBlock(b0, n0 uintptr, ptrmask0 *uint8, gcw *gcWork, shard int) {
 		return
 	}
 	b := b0 + off
-	ptrmask := (*uint8)(add(unsafe.Pointer(ptrmask0), uintptr(shard)*(rootBlockBytes/(8*sys.PtrSize))))
+	ptrmask := (*uint8)(add(unsafe.Pointer(ptrmask0), uintptr(shard)*(rootBlockBytes/(8*goarch.PtrSize))))
 	n := uintptr(rootBlockBytes)
 	if off+n > n0 {
 		n = n0 - off
@@ -372,7 +372,7 @@ func markrootSpans(gcw *gcWork, shard int) {
 				scanobject(p, gcw)
 
 				// The special itself is a root.
-				scanblock(uintptr(unsafe.Pointer(&spf.fn)), sys.PtrSize, &oneptrmask[0], gcw, nil)
+				scanblock(uintptr(unsafe.Pointer(&spf.fn)), goarch.PtrSize, &oneptrmask[0], gcw, nil)
 			}
 			unlock(&s.speciallock)
 		}
@@ -737,7 +737,7 @@ func scanstack(gp *g, gcw *gcWork) {
 	// register that gets moved back and forth between the
 	// register and sched.ctxt without a write barrier.
 	if gp.sched.ctxt != nil {
-		scanblock(uintptr(unsafe.Pointer(&gp.sched.ctxt)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+		scanblock(uintptr(unsafe.Pointer(&gp.sched.ctxt)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 	}
 
 	// Scan the stack. Accumulate a list of stack objects.
@@ -750,26 +750,23 @@ func scanstack(gp *g, gcw *gcWork) {
 	// Find additional pointers that point into the stack from the heap.
 	// Currently this includes defers and panics. See also function copystack.
 
-	// Find and trace all defer arguments.
-	tracebackdefers(gp, scanframe, nil)
-
 	// Find and trace other pointers in defer records.
 	for d := gp._defer; d != nil; d = d.link {
 		if d.fn != nil {
-			// tracebackdefers above does not scan the func value, which could
-			// be a stack allocated closure. See issue 30453.
-			scanblock(uintptr(unsafe.Pointer(&d.fn)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+			// Scan the func value, which could be a stack allocated closure.
+			// See issue 30453.
+			scanblock(uintptr(unsafe.Pointer(&d.fn)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 		}
 		if d.link != nil {
 			// The link field of a stack-allocated defer record might point
 			// to a heap-allocated defer record. Keep that heap record live.
-			scanblock(uintptr(unsafe.Pointer(&d.link)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+			scanblock(uintptr(unsafe.Pointer(&d.link)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 		}
 		// Retain defers records themselves.
 		// Defer records might not be reachable from the G through regular heap
 		// tracing because the defer linked list might weave between the stack and the heap.
 		if d.heap {
-			scanblock(uintptr(unsafe.Pointer(&d)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+			scanblock(uintptr(unsafe.Pointer(&d)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 		}
 	}
 	if gp._panic != nil {
@@ -913,13 +910,13 @@ func scanframeworker(frame *stkframe, state *stackScanState, gcw *gcWork) {
 
 	// Scan local variables if stack frame has been allocated.
 	if locals.n > 0 {
-		size := uintptr(locals.n) * sys.PtrSize
+		size := uintptr(locals.n) * goarch.PtrSize
 		scanblock(frame.varp-size, size, locals.bytedata, gcw, state)
 	}
 
 	// Scan arguments.
 	if args.n > 0 {
-		scanblock(frame.argp, uintptr(args.n)*sys.PtrSize, args.bytedata, gcw, state)
+		scanblock(frame.argp, uintptr(args.n)*goarch.PtrSize, args.bytedata, gcw, state)
 	}
 
 	// Add all stack objects to the stack object list.
@@ -1172,9 +1169,9 @@ func scanblock(b0, n0 uintptr, ptrmask *uint8, gcw *gcWork, stk *stackScanState)
 
 	for i := uintptr(0); i < n; {
 		// Find bits for the next word.
-		bits := uint32(*addb(ptrmask, i/(sys.PtrSize*8)))
+		bits := uint32(*addb(ptrmask, i/(goarch.PtrSize*8)))
 		if bits == 0 {
-			i += sys.PtrSize * 8
+			i += goarch.PtrSize * 8
 			continue
 		}
 		for j := 0; j < 8 && i < n; j++ {
@@ -1190,7 +1187,7 @@ func scanblock(b0, n0 uintptr, ptrmask *uint8, gcw *gcWork, stk *stackScanState)
 				}
 			}
 			bits >>= 1
-			i += sys.PtrSize
+			i += goarch.PtrSize
 		}
 	}
 }
@@ -1251,7 +1248,7 @@ func scanobject(b uintptr, gcw *gcWork) {
 	}
 
 	var i uintptr
-	for i = 0; i < n; i, hbits = i+sys.PtrSize, hbits.next() {
+	for i = 0; i < n; i, hbits = i+goarch.PtrSize, hbits.next() {
 		// Load bits once. See CL 22712 and issue 16973 for discussion.
 		bits := hbits.bits()
 		if bits&bitScan == 0 {
@@ -1300,7 +1297,7 @@ func scanConservative(b, n uintptr, ptrmask *uint8, gcw *gcWork, state *stackSca
 		print("conservatively scanning [", hex(b), ",", hex(b+n), ")\n")
 		hexdumpWords(b, b+n, func(p uintptr) byte {
 			if ptrmask != nil {
-				word := (p - b) / sys.PtrSize
+				word := (p - b) / goarch.PtrSize
 				bits := *addb(ptrmask, word/8)
 				if (bits>>(word%8))&1 == 0 {
 					return '$'
@@ -1325,9 +1322,9 @@ func scanConservative(b, n uintptr, ptrmask *uint8, gcw *gcWork, state *stackSca
 		printunlock()
 	}
 
-	for i := uintptr(0); i < n; i += sys.PtrSize {
+	for i := uintptr(0); i < n; i += goarch.PtrSize {
 		if ptrmask != nil {
-			word := i / sys.PtrSize
+			word := i / goarch.PtrSize
 			bits := *addb(ptrmask, word/8)
 			if bits == 0 {
 				// Skip 8 words (the loop increment will do the 8th)
@@ -1336,10 +1333,10 @@ func scanConservative(b, n uintptr, ptrmask *uint8, gcw *gcWork, state *stackSca
 				// seen this word of ptrmask, so i
 				// must be 8-word-aligned, but check
 				// our reasoning just in case.
-				if i%(sys.PtrSize*8) != 0 {
+				if i%(goarch.PtrSize*8) != 0 {
 					throw("misaligned mask")
 				}
-				i += sys.PtrSize*8 - sys.PtrSize
+				i += goarch.PtrSize*8 - goarch.PtrSize
 				continue
 			}
 			if (bits>>(word%8))&1 == 0 {
@@ -1401,7 +1398,7 @@ func shade(b uintptr) {
 //go:nowritebarrierrec
 func greyobject(obj, base, off uintptr, span *mspan, gcw *gcWork, objIndex uintptr) {
 	// obj should be start of allocation, and so must be at least pointer-aligned.
-	if obj&(sys.PtrSize-1) != 0 {
+	if obj&(goarch.PtrSize-1) != 0 {
 		throw("greyobject: obj not pointer-aligned")
 	}
 	mbits := span.markBitsForIndex(objIndex)
@@ -1473,13 +1470,13 @@ func gcDumpObject(label string, obj, off uintptr) {
 		// We're printing something from a stack frame. We
 		// don't know how big it is, so just show up to an
 		// including off.
-		size = off + sys.PtrSize
+		size = off + goarch.PtrSize
 	}
-	for i := uintptr(0); i < size; i += sys.PtrSize {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
 		// For big objects, just print the beginning (because
 		// that usually hints at the object's type) and the
 		// fields around off.
-		if !(i < 128*sys.PtrSize || off-16*sys.PtrSize < i && i < off+16*sys.PtrSize) {
+		if !(i < 128*goarch.PtrSize || off-16*goarch.PtrSize < i && i < off+16*goarch.PtrSize) {
 			skipped = true
 			continue
 		}
diff --git a/src/runtime/mgcscavenge.go b/src/runtime/mgcscavenge.go
index 7578129f9d13965eca8cff1456f12caf2a8a147d..2bb19985db0353aa181f9c40a0e08c6c831fcdeb 100644
--- a/src/runtime/mgcscavenge.go
+++ b/src/runtime/mgcscavenge.go
@@ -56,6 +56,7 @@
 package runtime
 
 import (
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -90,7 +91,7 @@ const (
 	//
 	// This ratio is used as part of multiplicative factor to help the scavenger account
 	// for the additional costs of using scavenged memory in its pacing.
-	scavengeCostRatio = 0.7 * (sys.GoosDarwin + sys.GoosIos)
+	scavengeCostRatio = 0.7 * (goos.IsDarwin + goos.IsIos)
 
 	// scavengeReservationShards determines the amount of memory the scavenger
 	// should reserve for scavenging at a time. Specifically, the amount of
@@ -249,7 +250,7 @@ func scavengeSleep(ns int64) int64 {
 // The background scavenger maintains the RSS of the application below
 // the line described by the proportional scavenging statistics in
 // the mheap struct.
-func bgscavenge() {
+func bgscavenge(c chan int) {
 	scavenge.g = getg()
 
 	lockInit(&scavenge.lock, lockRankScavenge)
@@ -261,7 +262,7 @@ func bgscavenge() {
 		wakeScavenger()
 	}
 
-	gcenable_setup <- 1
+	c <- 1
 	goparkunlock(&scavenge.lock, waitReasonGCScavengeWait, traceEvGoBlock, 1)
 
 	// Exponentially-weighted moving average of the fraction of time this
diff --git a/src/runtime/mgcstack.go b/src/runtime/mgcstack.go
index 92d58485f6f7a250d50a106fd77a378ef39a6e2e..49dc54e16524ce873609222ba1ea697640b1fddf 100644
--- a/src/runtime/mgcstack.go
+++ b/src/runtime/mgcstack.go
@@ -95,7 +95,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -107,7 +107,7 @@ const stackTraceDebug = false
 //go:notinheap
 type stackWorkBuf struct {
 	stackWorkBufHdr
-	obj [(_WorkbufSize - unsafe.Sizeof(stackWorkBufHdr{})) / sys.PtrSize]uintptr
+	obj [(_WorkbufSize - unsafe.Sizeof(stackWorkBufHdr{})) / goarch.PtrSize]uintptr
 }
 
 // Header declaration must come after the buf declaration above, because of issue #14620.
diff --git a/src/runtime/mgcsweep.go b/src/runtime/mgcsweep.go
index 8fe3a6534077946f4d4c5222206340f9ba828728..1812644623b2f2eb2ffb09217491c969a117deaf 100644
--- a/src/runtime/mgcsweep.go
+++ b/src/runtime/mgcsweep.go
@@ -153,13 +153,13 @@ func finishsweep_m() {
 	nextMarkBitArenaEpoch()
 }
 
-func bgsweep() {
+func bgsweep(c chan int) {
 	sweep.g = getg()
 
 	lockInit(&sweep.lock, lockRankSweep)
 	lock(&sweep.lock)
 	sweep.parked = true
-	gcenable_setup <- 1
+	c <- 1
 	goparkunlock(&sweep.lock, waitReasonGCSweepWait, traceEvGoBlock, 1)
 
 	for {
diff --git a/src/runtime/mgcwork.go b/src/runtime/mgcwork.go
index 667c7afa97197ddd3d190fafaf928385595447dd..8787d93d873508b36ebd597b417b1e08dec91b67 100644
--- a/src/runtime/mgcwork.go
+++ b/src/runtime/mgcwork.go
@@ -5,8 +5,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -322,7 +322,7 @@ type workbufhdr struct {
 type workbuf struct {
 	workbufhdr
 	// account for the above fields
-	obj [(_WorkbufSize - unsafe.Sizeof(workbufhdr{})) / sys.PtrSize]uintptr
+	obj [(_WorkbufSize - unsafe.Sizeof(workbufhdr{})) / goarch.PtrSize]uintptr
 }
 
 // workbuf factory routines. These funcs are used to manage the
diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 84c00ce8f85cd1e13047f4fae9536b67bdae08d3..b78f752ded6b618cd25417446d07e3f1bf16e69b 100644
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -10,8 +10,8 @@ package runtime
 
 import (
 	"internal/cpu"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -497,13 +497,13 @@ func recordspan(vh unsafe.Pointer, p unsafe.Pointer) {
 	assertLockHeld(&h.lock)
 
 	if len(h.allspans) >= cap(h.allspans) {
-		n := 64 * 1024 / sys.PtrSize
+		n := 64 * 1024 / goarch.PtrSize
 		if n < cap(h.allspans)*3/2 {
 			n = cap(h.allspans) * 3 / 2
 		}
 		var new []*mspan
 		sp := (*slice)(unsafe.Pointer(&new))
-		sp.array = sysAlloc(uintptr(n)*sys.PtrSize, &memstats.other_sys)
+		sp.array = sysAlloc(uintptr(n)*goarch.PtrSize, &memstats.other_sys)
 		if sp.array == nil {
 			throw("runtime: cannot allocate memory")
 		}
@@ -1822,7 +1822,7 @@ func addfinalizer(p unsafe.Pointer, f *funcval, nret uintptr, fint *_type, ot *p
 			scanobject(base, gcw)
 			// Mark the finalizer itself, since the
 			// special isn't part of the GC'd heap.
-			scanblock(uintptr(unsafe.Pointer(&s.fn)), sys.PtrSize, &oneptrmask[0], gcw, nil)
+			scanblock(uintptr(unsafe.Pointer(&s.fn)), goarch.PtrSize, &oneptrmask[0], gcw, nil)
 			releasem(mp)
 		}
 		return true
diff --git a/src/runtime/mkduff.go b/src/runtime/mkduff.go
index da191cc594c0de6daadd0dddca70070f38395341..f03674509238b0505ef4f7ee9ad93e7085821597 100644
--- a/src/runtime/mkduff.go
+++ b/src/runtime/mkduff.go
@@ -154,7 +154,7 @@ func zeroARM64(w io.Writer) {
 	// ZR: always zero
 	// R20: ptr to memory to be zeroed
 	// On return, R20 points to the last zeroed dword.
-	fmt.Fprintln(w, "TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0")
+	fmt.Fprintln(w, "TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0")
 	for i := 0; i < 63; i++ {
 		fmt.Fprintln(w, "\tSTP.P\t(ZR, ZR), 16(R20)")
 	}
@@ -167,7 +167,7 @@ func copyARM64(w io.Writer) {
 	// R21: ptr to destination memory
 	// R26, R27 (aka REGTMP): scratch space
 	// R20 and R21 are updated as a side effect
-	fmt.Fprintln(w, "TEXT runtime·duffcopy(SB), NOSPLIT|NOFRAME, $0-0")
+	fmt.Fprintln(w, "TEXT runtime·duffcopy(SB), NOSPLIT|NOFRAME, $0-0")
 
 	for i := 0; i < 64; i++ {
 		fmt.Fprintln(w, "\tLDP.P\t16(R20), (R26, R27)")
diff --git a/src/runtime/mkpreempt.go b/src/runtime/mkpreempt.go
index 6c980540f5776019e82ccd5939775723edfd86e1..d87446d03618420b828d8733e24e3733acbbcdc8 100644
--- a/src/runtime/mkpreempt.go
+++ b/src/runtime/mkpreempt.go
@@ -128,8 +128,7 @@ func header(arch string) {
 	}
 	fmt.Fprintf(out, "#include \"go_asm.h\"\n")
 	fmt.Fprintf(out, "#include \"textflag.h\"\n\n")
-	fmt.Fprintf(out, "// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.\n")
-	fmt.Fprintf(out, "TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0\n")
+	fmt.Fprintf(out, "TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0\n")
 }
 
 func p(f string, args ...interface{}) {
@@ -201,6 +200,8 @@ func gen386() {
 		l.add("MOVL", reg, 4)
 	}
 
+	softfloat := "GO386_softfloat"
+
 	// Save SSE state only if supported.
 	lSSE := layout{stack: l.stack, sp: "SP"}
 	for i := 0; i < 8; i++ {
@@ -210,13 +211,13 @@ func gen386() {
 	p("ADJSP $%d", lSSE.stack)
 	p("NOP SP")
 	l.save()
-	p("CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1\nJNE nosse")
+	p("#ifndef %s", softfloat)
 	lSSE.save()
-	label("nosse:")
+	p("#endif")
 	p("CALL ·asyncPreempt2(SB)")
-	p("CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1\nJNE nosse2")
+	p("#ifndef %s", softfloat)
 	lSSE.restore()
-	label("nosse2:")
+	p("#endif")
 	l.restore()
 	p("ADJSP $%d", -lSSE.stack)
 
diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go
index 5235b898e4f56cdcf4613ee91803e8377c39192d..0e6043cf2a37492c834597f5a3363695bb4c8bc2 100644
--- a/src/runtime/mprof.go
+++ b/src/runtime/mprof.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -141,7 +142,7 @@ var (
 	mbuckets  *bucket // memory profile buckets
 	bbuckets  *bucket // blocking profile buckets
 	xbuckets  *bucket // mutex profile buckets
-	buckhash  *[179999]*bucket
+	buckhash  *[buckHashSize]*bucket
 	bucketmem uintptr
 
 	mProf struct {
@@ -621,7 +622,7 @@ func record(r *MemProfileRecord, b *bucket) {
 	r.AllocObjects = int64(mp.active.allocs)
 	r.FreeObjects = int64(mp.active.frees)
 	if raceenabled {
-		racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), funcPC(MemProfile))
+		racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), abi.FuncPCABIInternal(MemProfile))
 	}
 	if msanenabled {
 		msanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0))
@@ -674,7 +675,7 @@ func BlockProfile(p []BlockProfileRecord) (n int, ok bool) {
 			}
 			r.Cycles = bp.cycles
 			if raceenabled {
-				racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), funcPC(BlockProfile))
+				racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), abi.FuncPCABIInternal(BlockProfile))
 			}
 			if msanenabled {
 				msanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0))
diff --git a/src/runtime/mranges.go b/src/runtime/mranges.go
index 84a2c06dbb2e66fcb1810e91640403e8281196e9..e0be1e134ed71b9585d7df38a87887c95901563f 100644
--- a/src/runtime/mranges.go
+++ b/src/runtime/mranges.go
@@ -10,7 +10,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -167,7 +167,7 @@ func (a *addrRanges) init(sysStat *sysMemStat) {
 	ranges := (*notInHeapSlice)(unsafe.Pointer(&a.ranges))
 	ranges.len = 0
 	ranges.cap = 16
-	ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), sys.PtrSize, sysStat))
+	ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), goarch.PtrSize, sysStat))
 	a.sysStat = sysStat
 	a.totalBytes = 0
 }
@@ -294,7 +294,7 @@ func (a *addrRanges) add(r addrRange) {
 			ranges := (*notInHeapSlice)(unsafe.Pointer(&a.ranges))
 			ranges.len = len(oldRanges) + 1
 			ranges.cap = cap(oldRanges) * 2
-			ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), sys.PtrSize, a.sysStat))
+			ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), goarch.PtrSize, a.sysStat))
 
 			// Copy in the old array, but make space for the new range.
 			copy(a.ranges[:i], oldRanges[:i])
@@ -364,7 +364,7 @@ func (a *addrRanges) cloneInto(b *addrRanges) {
 		ranges := (*notInHeapSlice)(unsafe.Pointer(&b.ranges))
 		ranges.len = 0
 		ranges.cap = cap(a.ranges)
-		ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), sys.PtrSize, b.sysStat))
+		ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), goarch.PtrSize, b.sysStat))
 	}
 	b.ranges = b.ranges[:len(a.ranges)]
 	b.totalBytes = a.totalBytes
diff --git a/src/runtime/msan/msan.go b/src/runtime/msan/msan.go
index c81577dddac08ca2992ccafb349df182a86561d7..9908a8ec22170fdf7782407e25247b909a25c56c 100644
--- a/src/runtime/msan/msan.go
+++ b/src/runtime/msan/msan.go
@@ -2,7 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build msan,linux
+//go:build msan && linux && (amd64 || arm64)
+// +build msan
+// +build linux
 // +build amd64 arm64
 
 package msan
diff --git a/src/runtime/mspanset.go b/src/runtime/mspanset.go
index 10d2596c38ccb350a1416cd72398a0ecec687df8..29f14910ccdbb6211321bd3a5cbf925f9648226d 100644
--- a/src/runtime/mspanset.go
+++ b/src/runtime/mspanset.go
@@ -6,8 +6,8 @@ package runtime
 
 import (
 	"internal/cpu"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -82,7 +82,7 @@ func (b *spanSet) push(s *mspan) {
 retry:
 	if top < spineLen {
 		spine := atomic.Loadp(unsafe.Pointer(&b.spine))
-		blockp := add(spine, sys.PtrSize*top)
+		blockp := add(spine, goarch.PtrSize*top)
 		block = (*spanSetBlock)(atomic.Loadp(blockp))
 	} else {
 		// Add a new block to the spine, potentially growing
@@ -102,11 +102,11 @@ retry:
 			if newCap == 0 {
 				newCap = spanSetInitSpineCap
 			}
-			newSpine := persistentalloc(newCap*sys.PtrSize, cpu.CacheLineSize, &memstats.gcMiscSys)
+			newSpine := persistentalloc(newCap*goarch.PtrSize, cpu.CacheLineSize, &memstats.gcMiscSys)
 			if b.spineCap != 0 {
 				// Blocks are allocated off-heap, so
 				// no write barriers.
-				memmove(newSpine, b.spine, b.spineCap*sys.PtrSize)
+				memmove(newSpine, b.spine, b.spineCap*goarch.PtrSize)
 			}
 			// Spine is allocated off-heap, so no write barrier.
 			atomic.StorepNoWB(unsafe.Pointer(&b.spine), newSpine)
@@ -124,7 +124,7 @@ retry:
 		block = spanSetBlockPool.alloc()
 
 		// Add it to the spine.
-		blockp := add(b.spine, sys.PtrSize*top)
+		blockp := add(b.spine, goarch.PtrSize*top)
 		// Blocks are allocated off-heap, so no write barrier.
 		atomic.StorepNoWB(blockp, unsafe.Pointer(block))
 		atomic.Storeuintptr(&b.spineLen, spineLen+1)
@@ -181,7 +181,7 @@ claimLoop:
 	// grows monotonically and we've already verified it, we'll definitely
 	// be reading from a valid block.
 	spine := atomic.Loadp(unsafe.Pointer(&b.spine))
-	blockp := add(spine, sys.PtrSize*uintptr(top))
+	blockp := add(spine, goarch.PtrSize*uintptr(top))
 
 	// Given that the spine length is correct, we know we will never
 	// see a nil block here, since the length is always updated after
@@ -241,7 +241,7 @@ func (b *spanSet) reset() {
 		// since it may be pushed into again. In order to avoid leaking
 		// memory since we're going to reset the head and tail, clean
 		// up such a block now, if it exists.
-		blockp := (**spanSetBlock)(add(b.spine, sys.PtrSize*uintptr(top)))
+		blockp := (**spanSetBlock)(add(b.spine, goarch.PtrSize*uintptr(top)))
 		block := *blockp
 		if block != nil {
 			// Sanity check the popped value.
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go
index eeb2a7b4bc73be09eca70a7fbd0cbb7083a25f32..341ba9a9365c2eef81ad998d5ab173785f3d2f0d 100644
--- a/src/runtime/mstats.go
+++ b/src/runtime/mstats.go
@@ -7,8 +7,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -713,7 +713,7 @@ type heapStatsDelta struct {
 
 	// Add a uint32 to ensure this struct is a multiple of 8 bytes in size.
 	// Only necessary on 32-bit platforms.
-	_ [(sys.PtrSize / 4) % 2]uint32
+	_ [(goarch.PtrSize / 4) % 2]uint32
 }
 
 // merge adds in the deltas from b into a.
diff --git a/src/runtime/mwbbuf.go b/src/runtime/mwbbuf.go
index 6efc00007d5f0eb8dafb72f6265e9400ddb09dd0..78d9382620bedc7436c0175e182e0e9466ac4042 100644
--- a/src/runtime/mwbbuf.go
+++ b/src/runtime/mwbbuf.go
@@ -23,8 +23,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -145,7 +145,7 @@ func (b *wbBuf) putFast(old, new uintptr) bool {
 	p := (*[2]uintptr)(unsafe.Pointer(b.next))
 	p[0] = old
 	p[1] = new
-	b.next += 2 * sys.PtrSize
+	b.next += 2 * goarch.PtrSize
 	return b.next != b.end
 }
 
diff --git a/src/runtime/norace_linux_test.go b/src/runtime/norace_linux_test.go
index 94b7c7a46777d81adf4a0059b81e20887531c324..b199aa633c12708c1361bc9c9af5e3c110e7b622 100644
--- a/src/runtime/norace_linux_test.go
+++ b/src/runtime/norace_linux_test.go
@@ -9,6 +9,7 @@
 package runtime_test
 
 import (
+	"internal/abi"
 	"runtime"
 	"testing"
 	"time"
@@ -25,7 +26,7 @@ func newOSProcCreated() {
 // Can't be run with -race because it inserts calls into newOSProcCreated()
 // that require a valid G/M.
 func TestNewOSProc0(t *testing.T) {
-	runtime.NewOSProc0(0x800000, unsafe.Pointer(runtime.FuncPC(newOSProcCreated)))
+	runtime.NewOSProc0(0x800000, unsafe.Pointer(abi.FuncPCABIInternal(newOSProcCreated)))
 	check := time.NewTicker(100 * time.Millisecond)
 	defer check.Stop()
 	end := time.After(5 * time.Second)
diff --git a/src/runtime/os3_plan9.go b/src/runtime/os3_plan9.go
index c5dc23de8b60898ee02c8c796c7517222648a635..a06d74e279fd6fc9f5e5b2eb78778cae3de826d8 100644
--- a/src/runtime/os3_plan9.go
+++ b/src/runtime/os3_plan9.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -92,15 +93,15 @@ func sighandler(_ureg *ureg, note *byte, gp *g) int {
 			if usesLR {
 				c.setlr(pc)
 			} else {
-				sp -= sys.PtrSize
+				sp -= goarch.PtrSize
 				*(*uintptr)(unsafe.Pointer(sp)) = pc
 				c.setsp(sp)
 			}
 		}
 		if usesLR {
-			c.setpc(funcPC(sigpanictramp))
+			c.setpc(abi.FuncPCABI0(sigpanictramp))
 		} else {
-			c.setpc(funcPC(sigpanic0))
+			c.setpc(abi.FuncPCABI0(sigpanic0))
 		}
 		return _NCONT
 	}
diff --git a/src/runtime/os3_solaris.go b/src/runtime/os3_solaris.go
index 39ef831acfef8723bd1fd3ab4826ca166a46984b..84194a3050d6c99d32ce41246e43280b6b785f20 100644
--- a/src/runtime/os3_solaris.go
+++ b/src/runtime/os3_solaris.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -172,7 +173,7 @@ func newosproc(mp *m) {
 	// Disable signals during create, so that the new thread starts
 	// with signals disabled. It will enable them in minit.
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	ret = pthread_create(&tid, &attr, funcPC(tstart_sysvicall), unsafe.Pointer(mp))
+	ret = pthread_create(&tid, &attr, abi.FuncPCABI0(tstart_sysvicall), unsafe.Pointer(mp))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 	if ret != 0 {
 		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", ret, ")\n")
@@ -215,7 +216,7 @@ func miniterrno()
 // Called to initialize a new m (including the bootstrap m).
 // Called on the new thread, cannot allocate memory.
 func minit() {
-	asmcgocall(unsafe.Pointer(funcPC(miniterrno)), unsafe.Pointer(&libc____errno))
+	asmcgocall(unsafe.Pointer(abi.FuncPCABI0(miniterrno)), unsafe.Pointer(&libc____errno))
 
 	minitSignals()
 
@@ -241,8 +242,8 @@ func setsig(i uint32, fn uintptr) {
 
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	*((*uintptr)(unsafe.Pointer(&sa._funcptr))) = fn
 	sigaction(i, &sa, nil)
@@ -390,6 +391,7 @@ func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) (un
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func doMmap(addr, n, prot, flags, fd, off uintptr) (uintptr, uintptr) {
 	var libcall libcall
 	libcall.fn = uintptr(unsafe.Pointer(&libc_mmap))
@@ -598,7 +600,7 @@ func sysargs(argc int32, argv **byte) {
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_aix.go b/src/runtime/os_aix.go
index 4fb1c8e845c87c5793a77c0f0bab6cca8b2e55fb..478dde2fc3ff4c1d8527c83a50fd86f19d8cbbb0 100644
--- a/src/runtime/os_aix.go
+++ b/src/runtime/os_aix.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"unsafe"
 )
 
@@ -267,7 +268,7 @@ func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		fn = uintptr(unsafe.Pointer(&sigtramp))
 	}
 	sa.sa_handler = fn
diff --git a/src/runtime/os_darwin.go b/src/runtime/os_darwin.go
index 079be107d719a24891fdcef303b41bb115808ada..ca61f20e8ac43c0d57c282c6f2f0c9cab98f8776 100644
--- a/src/runtime/os_darwin.go
+++ b/src/runtime/os_darwin.go
@@ -369,7 +369,7 @@ func setsig(i uint32, fn uintptr) {
 	var sa usigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = ^uint32(0)
-	if fn == funcPC(sighandler) { // funcPC(sighandler) matches the callers in signal_unix.go
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		if iscgo {
 			fn = abi.FuncPCABI0(cgoSigtramp)
 		} else {
diff --git a/src/runtime/os_dragonfly.go b/src/runtime/os_dragonfly.go
index 5c688a31096a6b6aa51175a7d5b8fa702a210a62..191a560667c9cf9a2329543830d2c8855d8fee8c 100644
--- a/src/runtime/os_dragonfly.go
+++ b/src/runtime/os_dragonfly.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -147,14 +148,14 @@ func lwp_start(uintptr)
 func newosproc(mp *m) {
 	stk := unsafe.Pointer(mp.g0.stack.hi)
 	if false {
-		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " lwp_start=", funcPC(lwp_start), " id=", mp.id, " ostk=", &mp, "\n")
+		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " lwp_start=", abi.FuncPCABI0(lwp_start), " id=", mp.id, " ostk=", &mp, "\n")
 	}
 
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
 
 	params := lwpparams{
-		start_func: funcPC(lwp_start),
+		start_func: abi.FuncPCABI0(lwp_start),
 		arg:        unsafe.Pointer(mp),
 		stack:      uintptr(stk),
 		tid1:       nil, // minit will record tid
@@ -226,8 +227,8 @@ func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_sigaction = fn
 	sigaction(i, &sa, nil)
@@ -278,7 +279,7 @@ func sysargs(argc int32, argv **byte) {
 	// skip NULL separator
 	n++
 
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_freebsd.go b/src/runtime/os_freebsd.go
index 09dd50ce59477583ff418da334e3769f191890a4..5a8121a420f208fea16c4aa345380fc63afabc63 100644
--- a/src/runtime/os_freebsd.go
+++ b/src/runtime/os_freebsd.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -116,8 +117,8 @@ func getncpu() int32 {
 	}
 
 	maskSize := int(maxcpus+7) / 8
-	if maskSize < sys.PtrSize {
-		maskSize = sys.PtrSize
+	if maskSize < goarch.PtrSize {
+		maskSize = goarch.PtrSize
 	}
 	if maskSize > len(mask) {
 		maskSize = len(mask)
@@ -197,11 +198,11 @@ func thr_start()
 func newosproc(mp *m) {
 	stk := unsafe.Pointer(mp.g0.stack.hi)
 	if false {
-		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " thr_start=", funcPC(thr_start), " id=", mp.id, " ostk=", &mp, "\n")
+		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " thr_start=", abi.FuncPCABI0(thr_start), " id=", mp.id, " ostk=", &mp, "\n")
 	}
 
 	param := thrparam{
-		start_func: funcPC(thr_start),
+		start_func: abi.FuncPCABI0(thr_start),
 		arg:        unsafe.Pointer(mp),
 		stack_base: mp.g0.stack.lo,
 		stack_size: uintptr(stk) - mp.g0.stack.lo,
@@ -236,7 +237,7 @@ func newosproc0(stacksize uintptr, fn unsafe.Pointer) {
 	// However, newosproc0 is currently unreachable because builds
 	// utilizing c-shared/c-archive force external linking.
 	param := thrparam{
-		start_func: funcPC(fn),
+		start_func: uintptr(fn),
 		arg:        nil,
 		stack_base: uintptr(stack), //+stacksize?
 		stack_size: stacksize,
@@ -391,7 +392,7 @@ func sysargs(argc int32, argv **byte) {
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_freebsd2.go b/src/runtime/os_freebsd2.go
index fde6fbf1b144eb609559d4662d9bf054636405aa..7e266dc27e2c62a34b74b35a5be352fdaf5e89c1 100644
--- a/src/runtime/os_freebsd2.go
+++ b/src/runtime/os_freebsd2.go
@@ -7,14 +7,16 @@
 
 package runtime
 
+import "internal/abi"
+
 //go:nosplit
 //go:nowritebarrierrec
 func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_handler = fn
 	sigaction(i, &sa, nil)
diff --git a/src/runtime/os_freebsd_amd64.go b/src/runtime/os_freebsd_amd64.go
index dc0bb9ff96fd33ca40cb21ee59ee1a2ea6631010..b179383eacc769316ab7a2c45b719e2a2a9c89b3 100644
--- a/src/runtime/os_freebsd_amd64.go
+++ b/src/runtime/os_freebsd_amd64.go
@@ -4,6 +4,8 @@
 
 package runtime
 
+import "internal/abi"
+
 func cgoSigtramp()
 
 //go:nosplit
@@ -12,11 +14,11 @@ func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		if iscgo {
-			fn = funcPC(cgoSigtramp)
+			fn = abi.FuncPCABI0(cgoSigtramp)
 		} else {
-			fn = funcPC(sigtramp)
+			fn = abi.FuncPCABI0(sigtramp)
 		}
 	}
 	sa.sa_handler = fn
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index c8b29e396c7128cdab84057c2782694bcd793e5f..88c16f7163959007231c680e8d6e3d334af116af 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -142,14 +143,14 @@ func newosproc(mp *m) {
 	 * note: strace gets confused if we use CLONE_PTRACE here.
 	 */
 	if false {
-		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " clone=", funcPC(clone), " id=", mp.id, " ostk=", &mp, "\n")
+		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " clone=", abi.FuncPCABI0(clone), " id=", mp.id, " ostk=", &mp, "\n")
 	}
 
 	// Disable signals during clone, so that the new thread starts
 	// with signals disabled. It will enable them in minit.
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	ret := clone(cloneFlags, stk, unsafe.Pointer(mp), unsafe.Pointer(mp.g0), unsafe.Pointer(funcPC(mstart)))
+	ret := clone(cloneFlags, stk, unsafe.Pointer(mp), unsafe.Pointer(mp.g0), unsafe.Pointer(abi.FuncPCABI0(mstart)))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 
 	if ret < 0 {
@@ -205,7 +206,7 @@ func sysargs(argc int32, argv **byte) {
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	if sysauxv(auxv[:]) != 0 {
 		return
 	}
@@ -429,13 +430,13 @@ func setsig(i uint32, fn uintptr) {
 	// should not be used". x86_64 kernel requires it. Only use it on
 	// x86.
 	if GOARCH == "386" || GOARCH == "amd64" {
-		sa.sa_restorer = funcPC(sigreturn)
+		sa.sa_restorer = abi.FuncPCABI0(sigreturn)
 	}
-	if fn == funcPC(sighandler) {
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		if iscgo {
-			fn = funcPC(cgoSigtramp)
+			fn = abi.FuncPCABI0(cgoSigtramp)
 		} else {
-			fn = funcPC(sigtramp)
+			fn = abi.FuncPCABI0(sigtramp)
 		}
 	}
 	sa.sa_handler = fn
diff --git a/src/runtime/os_netbsd.go b/src/runtime/os_netbsd.go
index 6fbb3aa6947bad99357103f6adb00364ed5b9a02..0b95fa7a6e75c77fe49c3a535fee7d14a4472eaf 100644
--- a/src/runtime/os_netbsd.go
+++ b/src/runtime/os_netbsd.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -100,6 +101,9 @@ var sigset_all = sigset{[4]uint32{^uint32(0), ^uint32(0), ^uint32(0), ^uint32(0)
 
 // From NetBSD's 
 const (
+	_CTL_KERN   = 1
+	_KERN_OSREV = 3
+
 	_CTL_HW        = 6
 	_HW_NCPU       = 3
 	_HW_PAGESIZE   = 7
@@ -137,6 +141,13 @@ func getPageSize() uintptr {
 	return 0
 }
 
+func getOSRev() int {
+	if osrev, ok := sysctlInt([]uint32{_CTL_KERN, _KERN_OSREV}); ok {
+		return int(osrev)
+	}
+	return 0
+}
+
 //go:nosplit
 func semacreate(mp *m) {
 }
@@ -215,7 +226,7 @@ func newosproc(mp *m) {
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
 
-	lwp_mcontext_init(&uc.uc_mcontext, stk, mp, mp.g0, funcPC(netbsdMstart))
+	lwp_mcontext_init(&uc.uc_mcontext, stk, mp, mp.g0, abi.FuncPCABI0(netbsdMstart))
 
 	ret := lwp_create(unsafe.Pointer(&uc), _LWP_DETACHED, unsafe.Pointer(&mp.procid))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
@@ -251,6 +262,7 @@ func osinit() {
 	if physPageSize == 0 {
 		physPageSize = getPageSize()
 	}
+	needSysmonWorkaround = getOSRev() < 902000000 // NetBSD 9.2
 }
 
 var urandom_dev = []byte("/dev/urandom\x00")
@@ -318,8 +330,8 @@ func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_sigaction = fn
 	sigaction(i, &sa, nil)
@@ -371,7 +383,7 @@ func sysargs(argc int32, argv **byte) {
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_netbsd_386.go b/src/runtime/os_netbsd_386.go
index 037f7e36dc6ae730321f68e2b9f2c777cd49a06b..ac89b9852c7f64a268615180b3d885f56b88d488 100644
--- a/src/runtime/os_netbsd_386.go
+++ b/src/runtime/os_netbsd_386.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_EIP] = uint32(funcPC(lwp_tramp))
+	mc.__gregs[_REG_EIP] = uint32(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_UESP] = uint32(uintptr(stk))
 	mc.__gregs[_REG_EBX] = uint32(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_EDX] = uint32(uintptr(unsafe.Pointer(gp)))
diff --git a/src/runtime/os_netbsd_amd64.go b/src/runtime/os_netbsd_amd64.go
index 5118b0c4ffda78c82406ef194c5575f7d445cbbe..74eea0ceabc4d9562af9f3e6ae120e08418ac34f 100644
--- a/src/runtime/os_netbsd_amd64.go
+++ b/src/runtime/os_netbsd_amd64.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_RIP] = uint64(funcPC(lwp_tramp))
+	mc.__gregs[_REG_RIP] = uint64(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_RSP] = uint64(uintptr(stk))
 	mc.__gregs[_REG_R8] = uint64(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_R9] = uint64(uintptr(unsafe.Pointer(gp)))
diff --git a/src/runtime/os_netbsd_arm.go b/src/runtime/os_netbsd_arm.go
index b5ec23e45b0a8833154279d37920e42ad6673802..5fb4e08d66a9158755227d0d9f53cc13132e9a0e 100644
--- a/src/runtime/os_netbsd_arm.go
+++ b/src/runtime/os_netbsd_arm.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_R15] = uint32(funcPC(lwp_tramp))
+	mc.__gregs[_REG_R15] = uint32(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_R13] = uint32(uintptr(stk))
 	mc.__gregs[_REG_R0] = uint32(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_R1] = uint32(uintptr(unsafe.Pointer(gp)))
diff --git a/src/runtime/os_netbsd_arm64.go b/src/runtime/os_netbsd_arm64.go
index 8d21b0a430f9abeecc833cf6dcb4f1e459f698b0..2dda9c9274d73bdcd44b145bf67d9379995932b1 100644
--- a/src/runtime/os_netbsd_arm64.go
+++ b/src/runtime/os_netbsd_arm64.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_ELR] = uint64(funcPC(lwp_tramp))
+	mc.__gregs[_REG_ELR] = uint64(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_X31] = uint64(uintptr(stk))
 	mc.__gregs[_REG_X0] = uint64(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_X1] = uint64(uintptr(unsafe.Pointer(mp.g0)))
diff --git a/src/runtime/os_openbsd.go b/src/runtime/os_openbsd.go
index 6259b96c22b84e05eb2d5ac203496c3381f8cf36..54f36c6ebff7a4aebfd3c2a4a2b164043e00a58c 100644
--- a/src/runtime/os_openbsd.go
+++ b/src/runtime/os_openbsd.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -191,8 +192,8 @@ func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = uint32(sigset_all)
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_sigaction = fn
 	sigaction(i, &sa, nil)
diff --git a/src/runtime/os_openbsd_libc.go b/src/runtime/os_openbsd_libc.go
index 0a342e553398a6f4d34df1030371204ad81a73a5..981e49827fbd99a09181a86e02e5c1b5c7f28365 100644
--- a/src/runtime/os_openbsd_libc.go
+++ b/src/runtime/os_openbsd_libc.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"unsafe"
 )
 
@@ -48,7 +49,7 @@ func newosproc(mp *m) {
 	// setup and then calls mstart.
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	err := pthread_create(&attr, funcPC(mstart_stub), unsafe.Pointer(mp))
+	err := pthread_create(&attr, abi.FuncPCABI0(mstart_stub), unsafe.Pointer(mp))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 	if err != 0 {
 		write(2, unsafe.Pointer(&failThreadCreate[0]), int32(len(failThreadCreate)))
diff --git a/src/runtime/os_openbsd_syscall.go b/src/runtime/os_openbsd_syscall.go
index 3cdcb6c707bfe2dfb08986e19ade174ca717d742..1ddee1864e415150ef9eca6b48699c5c564b30a9 100644
--- a/src/runtime/os_openbsd_syscall.go
+++ b/src/runtime/os_openbsd_syscall.go
@@ -8,7 +8,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -28,12 +29,12 @@ func newosproc(mp *m) {
 	param := tforkt{
 		tf_tcb:   unsafe.Pointer(&mp.tls[0]),
 		tf_tid:   nil, // minit will record tid
-		tf_stack: uintptr(stk) - sys.PtrSize,
+		tf_stack: uintptr(stk) - goarch.PtrSize,
 	}
 
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	ret := tfork(¶m, unsafe.Sizeof(param), mp, mp.g0, funcPC(mstart))
+	ret := tfork(¶m, unsafe.Sizeof(param), mp, mp.g0, abi.FuncPCABI0(mstart))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 
 	if ret < 0 {
diff --git a/src/runtime/os_plan9.go b/src/runtime/os_plan9.go
index 4d428346f0e37de08ef4763700abdc06b939c499..975d460a7da924ede62917c0b6800d826cfdf4c5 100644
--- a/src/runtime/os_plan9.go
+++ b/src/runtime/os_plan9.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -346,7 +347,7 @@ func getRandomData(r []byte) {
 
 func initsig(preinit bool) {
 	if !preinit {
-		notify(unsafe.Pointer(funcPC(sigtramp)))
+		notify(unsafe.Pointer(abi.FuncPCABI0(sigtramp)))
 	}
 }
 
diff --git a/src/runtime/os_solaris.go b/src/runtime/os_solaris.go
index 89129e5f1acfa164f55efae7ebc6e3a4bcda98f0..8ac1b08f690a8ab59851fb5f0bc3c1406e9b2ae9 100644
--- a/src/runtime/os_solaris.go
+++ b/src/runtime/os_solaris.go
@@ -179,6 +179,7 @@ func sysvicall3Err(fn *libcFunc, a1, a2, a3 uintptr) (r1, err uintptr) {
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func sysvicall4(fn *libcFunc, a1, a2, a3, a4 uintptr) uintptr {
 	// Leave caller's PC/SP around for traceback.
 	gp := getg()
@@ -208,6 +209,7 @@ func sysvicall4(fn *libcFunc, a1, a2, a3, a4 uintptr) uintptr {
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func sysvicall5(fn *libcFunc, a1, a2, a3, a4, a5 uintptr) uintptr {
 	// Leave caller's PC/SP around for traceback.
 	gp := getg()
@@ -237,6 +239,7 @@ func sysvicall5(fn *libcFunc, a1, a2, a3, a4, a5 uintptr) uintptr {
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func sysvicall6(fn *libcFunc, a1, a2, a3, a4, a5, a6 uintptr) uintptr {
 	// Leave caller's PC/SP around for traceback.
 	gp := getg()
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index f0935264ac6604b852960f2fea4164fc23e90173..648239fb366a15b6f96d53af2cb76e3867ebc871 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -543,7 +544,7 @@ func initLongPathSupport() {
 }
 
 func osinit() {
-	asmstdcallAddr = unsafe.Pointer(funcPC(asmstdcall))
+	asmstdcallAddr = unsafe.Pointer(abi.FuncPCABI0(asmstdcall))
 
 	setBadSignalMsg()
 
@@ -906,7 +907,7 @@ func semacreate(mp *m) {
 func newosproc(mp *m) {
 	// We pass 0 for the stack size to use the default for this binary.
 	thandle := stdcall6(_CreateThread, 0, 0,
-		funcPC(tstart_stdcall), uintptr(unsafe.Pointer(mp)),
+		abi.FuncPCABI0(tstart_stdcall), uintptr(unsafe.Pointer(mp)),
 		0, 0)
 
 	if thandle == 0 {
@@ -1385,14 +1386,14 @@ func preemptM(mp *m) {
 	if gp != nil && wantAsyncPreempt(gp) {
 		if ok, newpc := isAsyncSafePoint(gp, c.ip(), c.sp(), c.lr()); ok {
 			// Inject call to asyncPreempt
-			targetPC := funcPC(asyncPreempt)
+			targetPC := abi.FuncPCABI0(asyncPreempt)
 			switch GOARCH {
 			default:
 				throw("unsupported architecture")
 			case "386", "amd64":
 				// Make it look like the thread called targetPC.
 				sp := c.sp()
-				sp -= sys.PtrSize
+				sp -= goarch.PtrSize
 				*(*uintptr)(unsafe.Pointer(sp)) = newpc
 				c.set_sp(sp)
 				c.set_ip(targetPC)
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index f6c38aafcc825d30f55a92832ff10bf64de8c993..e4bdceb32f1a68d4730846980e441eab6e886dfb 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -5,8 +5,7 @@
 package runtime
 
 import (
-	"internal/abi"
-	"internal/goexperiment"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -31,7 +30,7 @@ import (
 // pc should be the program counter of the compiler-generated code that
 // triggered this panic.
 func panicCheck1(pc uintptr, msg string) {
-	if sys.GoarchWasm == 0 && hasPrefix(funcname(findfunc(pc)), "runtime.") {
+	if goarch.IsWasm == 0 && hasPrefix(funcname(findfunc(pc)), "runtime.") {
 		// Note: wasm can't tail call, so we can't get the original caller's pc.
 		throw(msg)
 	}
@@ -226,47 +225,27 @@ func panicmemAddr(addr uintptr) {
 	panic(errorAddressString{msg: "invalid memory address or nil pointer dereference", addr: addr})
 }
 
-// Create a new deferred function fn with siz bytes of arguments.
+// Create a new deferred function fn, which has no arguments and results.
 // The compiler turns a defer statement into a call to this.
-//go:nosplit
-func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
+func deferproc(fn func()) {
 	gp := getg()
 	if gp.m.curg != gp {
 		// go code on the system stack can't defer
 		throw("defer on system stack")
 	}
 
-	if goexperiment.RegabiDefer && siz != 0 {
-		// TODO: Make deferproc just take a func().
-		throw("defer with non-empty frame")
-	}
-
-	// the arguments of fn are in a perilous state. The stack map
-	// for deferproc does not describe them. So we can't let garbage
-	// collection or stack copying trigger until we've copied them out
-	// to somewhere safe. The memmove below does that.
-	// Until the copy completes, we can only call nosplit routines.
-	sp := getcallersp()
-	argp := uintptr(unsafe.Pointer(&fn)) + unsafe.Sizeof(fn)
-	callerpc := getcallerpc()
-
-	d := newdefer(siz)
+	d := newdefer()
 	if d._panic != nil {
 		throw("deferproc: d.panic != nil after newdefer")
 	}
 	d.link = gp._defer
 	gp._defer = d
 	d.fn = fn
-	d.pc = callerpc
-	d.sp = sp
-	switch siz {
-	case 0:
-		// Do nothing.
-	case sys.PtrSize:
-		*(*uintptr)(deferArgs(d)) = *(*uintptr)(unsafe.Pointer(argp))
-	default:
-		memmove(deferArgs(d), unsafe.Pointer(argp), uintptr(siz))
-	}
+	d.pc = getcallerpc()
+	// We must not be preempted between calling getcallersp and
+	// storing it to d.sp because getcallersp's result is a
+	// uintptr stack pointer.
+	d.sp = getcallersp()
 
 	// deferproc returns 0 normally.
 	// a deferred func that stops a panic
@@ -280,12 +259,10 @@ func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
 }
 
 // deferprocStack queues a new deferred function with a defer record on the stack.
-// The defer record must have its siz and fn fields initialized.
+// The defer record must have its fn field initialized.
 // All other fields can contain junk.
-// The defer record must be immediately followed in memory by
-// the arguments of the defer.
-// Nosplit because the arguments on the stack won't be scanned
-// until the defer record is spliced into the gp._defer list.
+// Nosplit because of the uninitialized pointer fields on the stack.
+//
 //go:nosplit
 func deferprocStack(d *_defer) {
 	gp := getg()
@@ -293,10 +270,7 @@ func deferprocStack(d *_defer) {
 		// go code on the system stack can't defer
 		throw("defer on system stack")
 	}
-	if goexperiment.RegabiDefer && d.siz != 0 {
-		throw("defer with non-empty frame")
-	}
-	// siz and fn are already set.
+	// fn is already set.
 	// The other fields are junk on entry to deferprocStack and
 	// are initialized here.
 	d.started = false
@@ -327,132 +301,37 @@ func deferprocStack(d *_defer) {
 	// been set and must not be clobbered.
 }
 
-// Small malloc size classes >= 16 are the multiples of 16: 16, 32, 48, 64, 80, 96, 112, 128, 144, ...
-// Each P holds a pool for defers with small arg sizes.
-// Assign defer allocations to pools by rounding to 16, to match malloc size classes.
-
-const (
-	deferHeaderSize = unsafe.Sizeof(_defer{})
-	minDeferAlloc   = (deferHeaderSize + 15) &^ 15
-	minDeferArgs    = minDeferAlloc - deferHeaderSize
-)
-
-// defer size class for arg size sz
-//go:nosplit
-func deferclass(siz uintptr) uintptr {
-	if siz <= minDeferArgs {
-		return 0
-	}
-	return (siz - minDeferArgs + 15) / 16
-}
-
-// total size of memory block for defer with arg size sz
-func totaldefersize(siz uintptr) uintptr {
-	if siz <= minDeferArgs {
-		return minDeferAlloc
-	}
-	return deferHeaderSize + siz
-}
-
-// Ensure that defer arg sizes that map to the same defer size class
-// also map to the same malloc size class.
-func testdefersizes() {
-	var m [len(p{}.deferpool)]int32
-
-	for i := range m {
-		m[i] = -1
-	}
-	for i := uintptr(0); ; i++ {
-		defersc := deferclass(i)
-		if defersc >= uintptr(len(m)) {
-			break
-		}
-		siz := roundupsize(totaldefersize(i))
-		if m[defersc] < 0 {
-			m[defersc] = int32(siz)
-			continue
-		}
-		if m[defersc] != int32(siz) {
-			print("bad defer size class: i=", i, " siz=", siz, " defersc=", defersc, "\n")
-			throw("bad defer size class")
-		}
-	}
-}
-
-// The arguments associated with a deferred call are stored
-// immediately after the _defer header in memory.
-//go:nosplit
-func deferArgs(d *_defer) unsafe.Pointer {
-	if d.siz == 0 {
-		// Avoid pointer past the defer allocation.
-		return nil
-	}
-	return add(unsafe.Pointer(d), unsafe.Sizeof(*d))
-}
-
-// deferFunc returns d's deferred function. This is temporary while we
-// support both modes of GOEXPERIMENT=regabidefer. Once we commit to
-// that experiment, we should change the type of d.fn.
-//go:nosplit
-func deferFunc(d *_defer) func() {
-	if !goexperiment.RegabiDefer {
-		throw("requires GOEXPERIMENT=regabidefer")
-	}
-	var fn func()
-	*(**funcval)(unsafe.Pointer(&fn)) = d.fn
-	return fn
-}
-
-var deferType *_type // type of _defer struct
-
-func init() {
-	var x interface{}
-	x = (*_defer)(nil)
-	deferType = (*(**ptrtype)(unsafe.Pointer(&x))).elem
-}
+// Each P holds a pool for defers.
 
 // Allocate a Defer, usually using per-P pool.
 // Each defer must be released with freedefer.  The defer is not
 // added to any defer chain yet.
-//
-// This must not grow the stack because there may be a frame without
-// stack map information when this is called.
-//
-//go:nosplit
-func newdefer(siz int32) *_defer {
+func newdefer() *_defer {
 	var d *_defer
-	sc := deferclass(uintptr(siz))
-	gp := getg()
-	if sc < uintptr(len(p{}.deferpool)) {
-		pp := gp.m.p.ptr()
-		if len(pp.deferpool[sc]) == 0 && sched.deferpool[sc] != nil {
-			// Take the slow path on the system stack so
-			// we don't grow newdefer's stack.
-			systemstack(func() {
-				lock(&sched.deferlock)
-				for len(pp.deferpool[sc]) < cap(pp.deferpool[sc])/2 && sched.deferpool[sc] != nil {
-					d := sched.deferpool[sc]
-					sched.deferpool[sc] = d.link
-					d.link = nil
-					pp.deferpool[sc] = append(pp.deferpool[sc], d)
-				}
-				unlock(&sched.deferlock)
-			})
-		}
-		if n := len(pp.deferpool[sc]); n > 0 {
-			d = pp.deferpool[sc][n-1]
-			pp.deferpool[sc][n-1] = nil
-			pp.deferpool[sc] = pp.deferpool[sc][:n-1]
+	mp := acquirem()
+	pp := mp.p.ptr()
+	if len(pp.deferpool) == 0 && sched.deferpool != nil {
+		lock(&sched.deferlock)
+		for len(pp.deferpool) < cap(pp.deferpool)/2 && sched.deferpool != nil {
+			d := sched.deferpool
+			sched.deferpool = d.link
+			d.link = nil
+			pp.deferpool = append(pp.deferpool, d)
 		}
+		unlock(&sched.deferlock)
+	}
+	if n := len(pp.deferpool); n > 0 {
+		d = pp.deferpool[n-1]
+		pp.deferpool[n-1] = nil
+		pp.deferpool = pp.deferpool[:n-1]
 	}
+	releasem(mp)
+	mp, pp = nil, nil
+
 	if d == nil {
-		// Allocate new defer+args.
-		systemstack(func() {
-			total := roundupsize(totaldefersize(uintptr(siz)))
-			d = (*_defer)(mallocgc(total, deferType, true))
-		})
+		// Allocate new defer.
+		d = new(_defer)
 	}
-	d.siz = siz
 	d.heap = true
 	return d
 }
@@ -460,11 +339,16 @@ func newdefer(siz int32) *_defer {
 // Free the given defer.
 // The defer cannot be used after this call.
 //
-// This must not grow the stack because there may be a frame without a
-// stack map when this is called.
+// This is nosplit because the incoming defer is in a perilous state.
+// It's not on any defer list, so stack copying won't adjust stack
+// pointers in it (namely, d.link). Hence, if we were to copy the
+// stack, d could then contain a stale pointer.
 //
 //go:nosplit
 func freedefer(d *_defer) {
+	d.link = nil
+	// After this point we can copy the stack.
+
 	if d._panic != nil {
 		freedeferpanic()
 	}
@@ -474,53 +358,36 @@ func freedefer(d *_defer) {
 	if !d.heap {
 		return
 	}
-	sc := deferclass(uintptr(d.siz))
-	if sc >= uintptr(len(p{}.deferpool)) {
-		return
-	}
-	pp := getg().m.p.ptr()
-	if len(pp.deferpool[sc]) == cap(pp.deferpool[sc]) {
+
+	mp := acquirem()
+	pp := mp.p.ptr()
+	if len(pp.deferpool) == cap(pp.deferpool) {
 		// Transfer half of local cache to the central cache.
-		//
-		// Take this slow path on the system stack so
-		// we don't grow freedefer's stack.
-		systemstack(func() {
-			var first, last *_defer
-			for len(pp.deferpool[sc]) > cap(pp.deferpool[sc])/2 {
-				n := len(pp.deferpool[sc])
-				d := pp.deferpool[sc][n-1]
-				pp.deferpool[sc][n-1] = nil
-				pp.deferpool[sc] = pp.deferpool[sc][:n-1]
-				if first == nil {
-					first = d
-				} else {
-					last.link = d
-				}
-				last = d
+		var first, last *_defer
+		for len(pp.deferpool) > cap(pp.deferpool)/2 {
+			n := len(pp.deferpool)
+			d := pp.deferpool[n-1]
+			pp.deferpool[n-1] = nil
+			pp.deferpool = pp.deferpool[:n-1]
+			if first == nil {
+				first = d
+			} else {
+				last.link = d
 			}
-			lock(&sched.deferlock)
-			last.link = sched.deferpool[sc]
-			sched.deferpool[sc] = first
-			unlock(&sched.deferlock)
-		})
+			last = d
+		}
+		lock(&sched.deferlock)
+		last.link = sched.deferpool
+		sched.deferpool = first
+		unlock(&sched.deferlock)
 	}
 
-	// These lines used to be simply `*d = _defer{}` but that
-	// started causing a nosplit stack overflow via typedmemmove.
-	d.siz = 0
-	d.started = false
-	d.openDefer = false
-	d.sp = 0
-	d.pc = 0
-	d.framepc = 0
-	d.varp = 0
-	d.fd = nil
-	// d._panic and d.fn must be nil already.
-	// If not, we would have called freedeferpanic or freedeferfn above,
-	// both of which throw.
-	d.link = nil
+	*d = _defer{}
 
-	pp.deferpool[sc] = append(pp.deferpool[sc], d)
+	pp.deferpool = append(pp.deferpool, d)
+
+	releasem(mp)
+	mp, pp = nil, nil
 }
 
 // Separate function so that it can split stack.
@@ -535,66 +402,39 @@ func freedeferfn() {
 	throw("freedefer with d.fn != nil")
 }
 
-// Run a deferred function if there is one.
+// deferreturn runs deferred functions for the caller's frame.
 // The compiler inserts a call to this at the end of any
 // function which calls defer.
-// If there is a deferred function, this will call runtime·jmpdefer,
-// which will jump to the deferred function such that it appears
-// to have been called by the caller of deferreturn at the point
-// just before deferreturn was called. The effect is that deferreturn
-// is called again and again until there are no more deferred functions.
-//
-// Declared as nosplit, because the function should not be preempted once we start
-// modifying the caller's frame in order to reuse the frame to call the deferred
-// function.
-//
-//go:nosplit
 func deferreturn() {
 	gp := getg()
-	d := gp._defer
-	if d == nil {
-		return
-	}
-	sp := getcallersp()
-	if d.sp != sp {
-		return
-	}
-	if d.openDefer {
-		done := runOpenDeferFrame(gp, d)
-		if !done {
-			throw("unfinished open-coded defers in deferreturn")
+	for {
+		d := gp._defer
+		if d == nil {
+			return
 		}
+		sp := getcallersp()
+		if d.sp != sp {
+			return
+		}
+		if d.openDefer {
+			done := runOpenDeferFrame(gp, d)
+			if !done {
+				throw("unfinished open-coded defers in deferreturn")
+			}
+			gp._defer = d.link
+			freedefer(d)
+			// If this frame uses open defers, then this
+			// must be the only defer record for the
+			// frame, so we can just return.
+			return
+		}
+
+		fn := d.fn
+		d.fn = nil
 		gp._defer = d.link
 		freedefer(d)
-		return
+		fn()
 	}
-
-	// Moving arguments around.
-	//
-	// Everything called after this point must be recursively
-	// nosplit because the garbage collector won't know the form
-	// of the arguments until the jmpdefer can flip the PC over to
-	// fn.
-	argp := getcallersp() + sys.MinFrameSize
-	switch d.siz {
-	case 0:
-		// Do nothing.
-	case sys.PtrSize:
-		*(*uintptr)(unsafe.Pointer(argp)) = *(*uintptr)(deferArgs(d))
-	default:
-		memmove(unsafe.Pointer(argp), deferArgs(d), uintptr(d.siz))
-	}
-	fn := d.fn
-	d.fn = nil
-	gp._defer = d.link
-	freedefer(d)
-	// If the defer function pointer is nil, force the seg fault to happen
-	// here rather than in jmpdefer. gentraceback() throws an error if it is
-	// called with a callback on an LR architecture and jmpdefer is on the
-	// stack, because the stack trace can be incorrect in that case - see
-	// issue #8153).
-	_ = fn.fn
-	jmpdefer(fn, argp)
 }
 
 // Goexit terminates the goroutine that calls it. No other goroutine is affected.
@@ -655,15 +495,9 @@ func Goexit() {
 				addOneOpenDeferFrame(gp, 0, nil)
 			}
 		} else {
-			if goexperiment.RegabiDefer {
-				// Save the pc/sp in deferCallSave(), so we can "recover" back to this
-				// loop if necessary.
-				deferCallSave(&p, deferFunc(d))
-			} else {
-				// Save the pc/sp in reflectcallSave(), so we can "recover" back to this
-				// loop if necessary.
-				reflectcallSave(&p, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz))
-			}
+			// Save the pc/sp in deferCallSave(), so we can "recover" back to this
+			// loop if necessary.
+			deferCallSave(&p, d.fn)
 		}
 		if p.aborted {
 			// We had a recursive panic in the defer d we started, and
@@ -783,8 +617,7 @@ func addOneOpenDeferFrame(gp *g, pc uintptr, sp unsafe.Pointer) {
 					throw("missing deferreturn")
 				}
 
-				maxargsize, _ := readvarintUnsafe(fd)
-				d1 := newdefer(int32(maxargsize))
+				d1 := newdefer()
 				d1.openDefer = true
 				d1._panic = nil
 				// These are the pc/sp to set after we've
@@ -845,57 +678,29 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
 	done := true
 	fd := d.fd
 
-	// Skip the maxargsize
-	_, fd = readvarintUnsafe(fd)
 	deferBitsOffset, fd := readvarintUnsafe(fd)
 	nDefers, fd := readvarintUnsafe(fd)
 	deferBits := *(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset)))
 
 	for i := int(nDefers) - 1; i >= 0; i-- {
 		// read the funcdata info for this defer
-		var argWidth, closureOffset, nArgs uint32
-		argWidth, fd = readvarintUnsafe(fd)
+		var closureOffset uint32
 		closureOffset, fd = readvarintUnsafe(fd)
-		nArgs, fd = readvarintUnsafe(fd)
-		if goexperiment.RegabiDefer && argWidth != 0 {
-			throw("defer with non-empty frame")
-		}
 		if deferBits&(1< _StackLimit {
 		// We need more than the nosplit limit. This isn't
 		// unsafe, but it may limit asynchronous preemption.
@@ -398,7 +399,7 @@ func isAsyncSafePoint(gp *g, pc, sp, lr uintptr) (bool, uintptr) {
 		return false, 0
 	}
 	up, startpc := pcdatavalue2(f, _PCDATA_UnsafePoint, pc)
-	if up != _PCDATA_UnsafePointSafe {
+	if up == _PCDATA_UnsafePointUnsafe {
 		// Unsafe-point marked by compiler. This includes
 		// atomic sequences (e.g., write barrier) and nosplit
 		// functions (except at calls).
diff --git a/src/runtime/preempt_386.s b/src/runtime/preempt_386.s
index a803b24dc6f0b06bec126b4dc3f1904d94a28f07..d57bc3d37c061e17d6f5fed474d3005057ad8851 100644
--- a/src/runtime/preempt_386.s
+++ b/src/runtime/preempt_386.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	PUSHFL
 	ADJSP $156
 	NOP SP
@@ -15,8 +14,7 @@ TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVL BP, 16(SP)
 	MOVL SI, 20(SP)
 	MOVL DI, 24(SP)
-	CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE nosse
+	#ifndef GO386_softfloat
 	MOVUPS X0, 28(SP)
 	MOVUPS X1, 44(SP)
 	MOVUPS X2, 60(SP)
@@ -25,10 +23,9 @@ TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVUPS X5, 108(SP)
 	MOVUPS X6, 124(SP)
 	MOVUPS X7, 140(SP)
-nosse:
+	#endif
 	CALL ·asyncPreempt2(SB)
-	CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
-	JNE nosse2
+	#ifndef GO386_softfloat
 	MOVUPS 140(SP), X7
 	MOVUPS 124(SP), X6
 	MOVUPS 108(SP), X5
@@ -37,7 +34,7 @@ nosse:
 	MOVUPS 60(SP), X2
 	MOVUPS 44(SP), X1
 	MOVUPS 28(SP), X0
-nosse2:
+	#endif
 	MOVL 24(SP), DI
 	MOVL 20(SP), SI
 	MOVL 16(SP), BP
diff --git a/src/runtime/preempt_amd64.s b/src/runtime/preempt_amd64.s
index dc7af806d32f3e390dab0173db9e3442265b47c1..31f7c8b66f502b6cbeccc90b7c695214614eb6b2 100644
--- a/src/runtime/preempt_amd64.s
+++ b/src/runtime/preempt_amd64.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	PUSHQ BP
 	MOVQ SP, BP
 	// Save flags before clobbering them
diff --git a/src/runtime/preempt_arm.s b/src/runtime/preempt_arm.s
index bbc9fbb1eae1d6e19640f049c2e0e87dc17ffebd..8f243c0dcd608191507494e86bac08e921241c3b 100644
--- a/src/runtime/preempt_arm.s
+++ b/src/runtime/preempt_arm.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVW.W R14, -188(R13)
 	MOVW R0, 4(R13)
 	MOVW R1, 8(R13)
diff --git a/src/runtime/preempt_arm64.s b/src/runtime/preempt_arm64.s
index 2b70a28479dd3572314bbf59fc48f0d8c125e7ef..36ee13282c777630eaa6e19310b236e7ada65634 100644
--- a/src/runtime/preempt_arm64.s
+++ b/src/runtime/preempt_arm64.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVD R30, -496(RSP)
 	SUB $496, RSP
 	#ifdef GOOS_linux
diff --git a/src/runtime/preempt_mips64x.s b/src/runtime/preempt_mips64x.s
index b755425bc5d3275e6c7700d63f41e35e4120c20a..c1249e382e206d1d002e5b64be5e2cca6a712054 100644
--- a/src/runtime/preempt_mips64x.s
+++ b/src/runtime/preempt_mips64x.s
@@ -6,8 +6,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVV R31, -488(R29)
 	SUBV $488, R29
 	MOVV R1, 8(R29)
diff --git a/src/runtime/preempt_mipsx.s b/src/runtime/preempt_mipsx.s
index c1bff60859610ce4e333d4d8b097fb026011393a..70b79e05b99a23cc5229b2946ca5a58138606526 100644
--- a/src/runtime/preempt_mipsx.s
+++ b/src/runtime/preempt_mipsx.s
@@ -6,8 +6,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVW R31, -244(R29)
 	SUB $244, R29
 	MOVW R1, 4(R29)
diff --git a/src/runtime/preempt_ppc64x.s b/src/runtime/preempt_ppc64x.s
index 70bd91982bfa89eff10177aeef5c66eed7f516eb..7ed4021dde74f7ea46d4a042c0dac03673725f46 100644
--- a/src/runtime/preempt_ppc64x.s
+++ b/src/runtime/preempt_ppc64x.s
@@ -6,8 +6,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVD R31, -488(R1)
 	MOVD LR, R31
 	MOVDU R31, -520(R1)
diff --git a/src/runtime/preempt_riscv64.s b/src/runtime/preempt_riscv64.s
index d4f9cc277f4b62b27a8c33002fb587c53795bd43..eb68dcba2b96d137171d58c0a9b36b7f433fa387 100644
--- a/src/runtime/preempt_riscv64.s
+++ b/src/runtime/preempt_riscv64.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOV X1, -472(X2)
 	ADD $-472, X2
 	MOV X3, 8(X2)
diff --git a/src/runtime/preempt_s390x.s b/src/runtime/preempt_s390x.s
index c6f11571df77885bf1d1d9f9f0dd44a9f00262c7..ca9e47cde1791340c6df2b7ef2740ccb6fb6c225 100644
--- a/src/runtime/preempt_s390x.s
+++ b/src/runtime/preempt_s390x.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	IPM R10
 	MOVD R14, -248(R15)
 	ADD $-248, R15
diff --git a/src/runtime/preempt_wasm.s b/src/runtime/preempt_wasm.s
index da90e8aa6dd311c7049b2da5134399249f4b9147..0cf57d3d2265bbf9b5cc14623216097c15fa3cf6 100644
--- a/src/runtime/preempt_wasm.s
+++ b/src/runtime/preempt_wasm.s
@@ -3,7 +3,6 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	// No async preemption on wasm
 	UNDEF
diff --git a/src/runtime/print.go b/src/runtime/print.go
index f15296cf024587f1b655ae7e75eb1103d1cb91d8..59a91203b9ff9cad9e665833d5a8e362bda68f5b 100644
--- a/src/runtime/print.go
+++ b/src/runtime/print.go
@@ -5,8 +5,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -271,7 +271,7 @@ func hexdumpWords(p, end uintptr, mark func(uintptr) byte) {
 	var markbuf [1]byte
 	markbuf[0] = ' '
 	minhexdigits = int(unsafe.Sizeof(uintptr(0)) * 2)
-	for i := uintptr(0); p+i < end; i += sys.PtrSize {
+	for i := uintptr(0); p+i < end; i += goarch.PtrSize {
 		if i%16 == 0 {
 			if i != 0 {
 				println()
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 7bc2a92590755ee3b1c40255d00c760fa30e927b..55023e3f9f0bb6acb74b353350bf3f6792b5cf8b 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -7,7 +7,7 @@ package runtime
 import (
 	"internal/abi"
 	"internal/cpu"
-	"internal/goexperiment"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -152,7 +152,7 @@ func main() {
 	// Max stack size is 1 GB on 64-bit, 250 MB on 32-bit.
 	// Using decimal instead of binary GB and MB because
 	// they look nicer in the stack overflow failure message.
-	if sys.PtrSize == 8 {
+	if goarch.PtrSize == 8 {
 		maxstacksize = 1000000000
 	} else {
 		maxstacksize = 250000000
@@ -466,18 +466,6 @@ func releaseSudog(s *sudog) {
 	releasem(mp)
 }
 
-// funcPC returns the entry PC of the function f.
-// It assumes that f is a func value. Otherwise the behavior is undefined.
-// CAREFUL: In programs with plugins, funcPC can return different values
-// for the same function (because there are actually multiple copies of
-// the same function in the address space). To be safe, don't use the
-// results of this function in any == expression. It is only safe to
-// use the result as an address at which to start executing code.
-//go:nosplit
-func funcPC(f interface{}) uintptr {
-	return *(*uintptr)(efaceOf(&f).data)
-}
-
 // called from assembly
 func badmcall(fn func(*g)) {
 	throw("runtime: mcall called on m->g0 stack")
@@ -568,7 +556,7 @@ func atomicAllG() (**g, uintptr) {
 
 // atomicAllGIndex returns ptr[i] with the allgptr returned from atomicAllG.
 func atomicAllGIndex(ptr **g, i uintptr) *g {
-	return *(**g)(add(unsafe.Pointer(ptr), i*sys.PtrSize))
+	return *(**g)(add(unsafe.Pointer(ptr), i*goarch.PtrSize))
 }
 
 // forEachG calls fn on every G from allgs.
@@ -634,13 +622,18 @@ func cpuinit() {
 
 	// Support cpu feature variables are used in code generated by the compiler
 	// to guard execution of instructions that can not be assumed to be always supported.
-	x86HasPOPCNT = cpu.X86.HasPOPCNT
-	x86HasSSE41 = cpu.X86.HasSSE41
-	x86HasFMA = cpu.X86.HasFMA
+	switch GOARCH {
+	case "386", "AMD64":
+		x86HasPOPCNT = cpu.X86.HasPOPCNT
+		x86HasSSE41 = cpu.X86.HasSSE41
+		x86HasFMA = cpu.X86.HasFMA
 
-	armHasVFPv4 = cpu.ARM.HasVFPv4
+	case "arm":
+		armHasVFPv4 = cpu.ARM.HasVFPv4
 
-	arm64HasATOMICS = cpu.ARM64.HasATOMICS
+	case "arm64":
+		arm64HasATOMICS = cpu.ARM64.HasATOMICS
+	}
 }
 
 // The bootstrap sequence is:
@@ -2027,7 +2020,7 @@ func oneNewExtraM() {
 	gp := malg(4096)
 	gp.sched.pc = abi.FuncPCABI0(goexit) + sys.PCQuantum
 	gp.sched.sp = gp.stack.hi
-	gp.sched.sp -= 4 * sys.PtrSize // extra space in case of reads slightly beyond frame
+	gp.sched.sp -= 4 * goarch.PtrSize // extra space in case of reads slightly beyond frame
 	gp.sched.lr = 0
 	gp.sched.g = guintptr(unsafe.Pointer(gp))
 	gp.syscallpc = gp.sched.pc
@@ -2045,7 +2038,7 @@ func oneNewExtraM() {
 	gp.lockedm.set(mp)
 	gp.goid = int64(atomic.Xadd64(&sched.goidgen, 1))
 	if raceenabled {
-		gp.racectx = racegostart(funcPC(newextram) + sys.PCQuantum)
+		gp.racectx = racegostart(abi.FuncPCABIInternal(newextram) + sys.PCQuantum)
 	}
 	// put on allg for garbage collector
 	allgadd(gp)
@@ -2238,7 +2231,7 @@ func newm1(mp *m) {
 		}
 		ts.g.set(mp.g0)
 		ts.tls = (*uint64)(unsafe.Pointer(&mp.tls[0]))
-		ts.fn = unsafe.Pointer(funcPC(mstart))
+		ts.fn = unsafe.Pointer(abi.FuncPCABI0(mstart))
 		if msanenabled {
 			msanwrite(unsafe.Pointer(&ts), unsafe.Sizeof(ts))
 		}
@@ -4116,7 +4109,10 @@ func exitsyscall0(gp *g) {
 	schedule() // Never returns.
 }
 
-func beforefork() {
+// Called from syscall package before fork.
+//go:linkname syscall_runtime_BeforeFork syscall.runtime_BeforeFork
+//go:nosplit
+func syscall_runtime_BeforeFork() {
 	gp := getg().m.curg
 
 	// Block signals during a fork, so that the child does not run
@@ -4133,14 +4129,10 @@ func beforefork() {
 	gp.stackguard0 = stackFork
 }
 
-// Called from syscall package before fork.
-//go:linkname syscall_runtime_BeforeFork syscall.runtime_BeforeFork
+// Called from syscall package after fork in parent.
+//go:linkname syscall_runtime_AfterFork syscall.runtime_AfterFork
 //go:nosplit
-func syscall_runtime_BeforeFork() {
-	systemstack(beforefork)
-}
-
-func afterfork() {
+func syscall_runtime_AfterFork() {
 	gp := getg().m.curg
 
 	// See the comments in beforefork.
@@ -4151,13 +4143,6 @@ func afterfork() {
 	gp.m.locks--
 }
 
-// Called from syscall package after fork in parent.
-//go:linkname syscall_runtime_AfterFork syscall.runtime_AfterFork
-//go:nosplit
-func syscall_runtime_AfterFork() {
-	systemstack(afterfork)
-}
-
 // inForkedChild is true while manipulating signals in the child process.
 // This is used to avoid calling libc functions in case we are using vfork.
 var inForkedChild bool
@@ -4232,27 +4217,14 @@ func malg(stacksize int32) *g {
 	return newg
 }
 
-// Create a new g running fn with siz bytes of arguments.
+// Create a new g running fn.
 // Put it on the queue of g's waiting to run.
 // The compiler turns a go statement into a call to this.
-//
-// The stack layout of this call is unusual: it assumes that the
-// arguments to pass to fn are on the stack sequentially immediately
-// after &fn. Hence, they are logically part of newproc's argument
-// frame, even though they don't appear in its signature (and can't
-// because their types differ between call sites).
-//
-// This must be nosplit because this stack layout means there are
-// untyped arguments in newproc's argument frame. Stack copies won't
-// be able to adjust them and stack splits won't be able to copy them.
-//
-//go:nosplit
-func newproc(siz int32, fn *funcval) {
-	argp := add(unsafe.Pointer(&fn), sys.PtrSize)
+func newproc(fn *funcval) {
 	gp := getg()
 	pc := getcallerpc()
 	systemstack(func() {
-		newg := newproc1(fn, argp, siz, gp, pc)
+		newg := newproc1(fn, gp, pc)
 
 		_p_ := getg().m.p.ptr()
 		runqput(_p_, newg, true)
@@ -4263,24 +4235,10 @@ func newproc(siz int32, fn *funcval) {
 	})
 }
 
-// Create a new g in state _Grunnable, starting at fn, with narg bytes
-// of arguments starting at argp. callerpc is the address of the go
-// statement that created this. The caller is responsible for adding
-// the new g to the scheduler.
-//
-// This must run on the system stack because it's the continuation of
-// newproc, which cannot split the stack.
-//
-//go:systemstack
-func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerpc uintptr) *g {
-	if goexperiment.RegabiDefer && narg != 0 {
-		// TODO: When we commit to GOEXPERIMENT=regabidefer,
-		// rewrite the comments for newproc and newproc1.
-		// newproc will no longer have a funny stack layout or
-		// need to be nosplit.
-		throw("go with non-empty frame")
-	}
-
+// Create a new g in state _Grunnable, starting at fn. callerpc is the
+// address of the go statement that created this. The caller is responsible
+// for adding the new g to the scheduler.
+func newproc1(fn *funcval, callergp *g, callerpc uintptr) *g {
 	_g_ := getg()
 
 	if fn == nil {
@@ -4288,16 +4246,6 @@ func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerp
 		throw("go of nil func value")
 	}
 	acquirem() // disable preemption because it can be holding p in a local var
-	siz := narg
-	siz = (siz + 7) &^ 7
-
-	// We could allocate a larger initial stack if necessary.
-	// Not worth it: this is almost always an error.
-	// 4*PtrSize: extra space added below
-	// PtrSize: caller's LR (arm) or return address (x86, in gostartcall).
-	if siz >= _StackMin-4*sys.PtrSize-sys.PtrSize {
-		throw("newproc: function arguments too large for new goroutine")
-	}
 
 	_p_ := _g_.m.p.ptr()
 	newg := gfget(_p_)
@@ -4314,8 +4262,8 @@ func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerp
 		throw("newproc1: new g is not Gdead")
 	}
 
-	totalSize := 4*sys.PtrSize + uintptr(siz) + sys.MinFrameSize // extra space in case of reads slightly beyond frame
-	totalSize += -totalSize & (sys.StackAlign - 1)               // align to StackAlign
+	totalSize := uintptr(4*goarch.PtrSize + sys.MinFrameSize) // extra space in case of reads slightly beyond frame
+	totalSize = alignUp(totalSize, sys.StackAlign)
 	sp := newg.stack.hi - totalSize
 	spArg := sp
 	if usesLR {
@@ -4324,24 +4272,6 @@ func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerp
 		prepGoExitFrame(sp)
 		spArg += sys.MinFrameSize
 	}
-	if narg > 0 {
-		memmove(unsafe.Pointer(spArg), argp, uintptr(narg))
-		// This is a stack-to-stack copy. If write barriers
-		// are enabled and the source stack is grey (the
-		// destination is always black), then perform a
-		// barrier copy. We do this *after* the memmove
-		// because the destination stack may have garbage on
-		// it.
-		if writeBarrier.needed && !_g_.m.curg.gcscandone {
-			f := findfunc(fn.fn)
-			stkmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
-			if stkmap.nbit > 0 {
-				// We're in the prologue, so it's always stack map index 0.
-				bv := stackmapdata(stkmap, 0)
-				bulkBarrierBitmap(spArg, spArg, uintptr(bv.n)*sys.PtrSize, 0, bv.bytedata)
-			}
-		}
-	}
 
 	memclrNoHeapPointers(unsafe.Pointer(&newg.sched), unsafe.Sizeof(newg.sched))
 	newg.sched.sp = sp
@@ -4686,7 +4616,7 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
 		return
 	}
 
-	// On mips{,le}, 64bit atomics are emulated with spinlocks, in
+	// On mips{,le}/arm, 64bit atomics are emulated with spinlocks, in
 	// runtime/internal/atomic. If SIGPROF arrives while the program is inside
 	// the critical section, it creates a deadlock (when writing the sample).
 	// As a workaround, create a counter of SIGPROFs while in critical section
@@ -4699,6 +4629,13 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
 				return
 			}
 		}
+		if GOARCH == "arm" && goarm < 7 && GOOS == "linux" && pc&0xffff0000 == 0xffff0000 {
+			// runtime/internal/atomic functions call into kernel
+			// helpers on arm < 7. See
+			// runtime/internal/atomic/sys_linux_arm.s.
+			cpuprof.lostAtomic++
+			return
+		}
 	}
 
 	// Profiling runs concurrently with GC, so it must not allocate.
@@ -4751,16 +4688,16 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
 			// If all of the above has failed, account it against abstract "System" or "GC".
 			n = 2
 			if inVDSOPage(pc) {
-				pc = funcPC(_VDSO) + sys.PCQuantum
+				pc = abi.FuncPCABIInternal(_VDSO) + sys.PCQuantum
 			} else if pc > firstmoduledata.etext {
 				// "ExternalCode" is better than "etext".
-				pc = funcPC(_ExternalCode) + sys.PCQuantum
+				pc = abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum
 			}
 			stk[0] = pc
 			if mp.preemptoff != "" {
-				stk[1] = funcPC(_GC) + sys.PCQuantum
+				stk[1] = abi.FuncPCABIInternal(_GC) + sys.PCQuantum
 			} else {
-				stk[1] = funcPC(_System) + sys.PCQuantum
+				stk[1] = abi.FuncPCABIInternal(_System) + sys.PCQuantum
 			}
 		}
 	}
@@ -4804,7 +4741,7 @@ func sigprofNonGoPC(pc uintptr) {
 	if prof.hz != 0 {
 		stk := []uintptr{
 			pc,
-			funcPC(_ExternalCode) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum,
 		}
 		cpuprof.addNonGo(stk)
 	}
@@ -4854,9 +4791,7 @@ func (pp *p) init(id int32) {
 	pp.id = id
 	pp.status = _Pgcstop
 	pp.sudogcache = pp.sudogbuf[:0]
-	for i := range pp.deferpool {
-		pp.deferpool[i] = pp.deferpoolbuf[i][:0]
-	}
+	pp.deferpool = pp.deferpoolbuf[:0]
 	pp.wbBuf.reset()
 	if pp.mcache == nil {
 		if id == 0 {
@@ -4933,12 +4868,10 @@ func (pp *p) destroy() {
 		pp.sudogbuf[i] = nil
 	}
 	pp.sudogcache = pp.sudogbuf[:0]
-	for i := range pp.deferpool {
-		for j := range pp.deferpoolbuf[i] {
-			pp.deferpoolbuf[i][j] = nil
-		}
-		pp.deferpool[i] = pp.deferpoolbuf[i][:0]
+	for j := range pp.deferpoolbuf {
+		pp.deferpoolbuf[j] = nil
 	}
+	pp.deferpool = pp.deferpoolbuf[:0]
 	systemstack(func() {
 		for i := 0; i < pp.mspancache.len; i++ {
 			// Safe to call since the world is stopped.
@@ -5301,6 +5234,10 @@ func checkdead() {
 // This is a variable for testing purposes. It normally doesn't change.
 var forcegcperiod int64 = 2 * 60 * 1e9
 
+// needSysmonWorkaround is true if the workaround for
+// golang.org/issue/42515 is needed on NetBSD.
+var needSysmonWorkaround bool = false
+
 // Always runs without a P, so write barriers are not allowed.
 //
 //go:nowritebarrierrec
@@ -5409,7 +5346,7 @@ func sysmon() {
 			}
 		}
 		mDoFixup()
-		if GOOS == "netbsd" {
+		if GOOS == "netbsd" && needSysmonWorkaround {
 			// netpoll is responsible for waiting for timer
 			// expiration, so we typically don't have to worry
 			// about starting an M to service timers. (Note that
@@ -6463,7 +6400,7 @@ func doInit(t *initTask) {
 		t.state = 1 // initialization in progress
 
 		for i := uintptr(0); i < t.ndeps; i++ {
-			p := add(unsafe.Pointer(t), (3+i)*sys.PtrSize)
+			p := add(unsafe.Pointer(t), (3+i)*goarch.PtrSize)
 			t2 := *(**initTask)(p)
 			doInit(t2)
 		}
@@ -6484,9 +6421,9 @@ func doInit(t *initTask) {
 			before = inittrace
 		}
 
-		firstFunc := add(unsafe.Pointer(t), (3+t.ndeps)*sys.PtrSize)
+		firstFunc := add(unsafe.Pointer(t), (3+t.ndeps)*goarch.PtrSize)
 		for i := uintptr(0); i < t.nfns; i++ {
-			p := add(firstFunc, i*sys.PtrSize)
+			p := add(firstFunc, i*goarch.PtrSize)
 			f := *(*func())(unsafe.Pointer(&p))
 			f()
 		}
@@ -6496,7 +6433,8 @@ func doInit(t *initTask) {
 			// Load stats non-atomically since tracinit is updated only by this init goroutine.
 			after := inittrace
 
-			pkg := funcpkgpath(findfunc(funcPC(firstFunc)))
+			f := *(*func())(unsafe.Pointer(&firstFunc))
+			pkg := funcpkgpath(findfunc(abi.FuncPCABIInternal(f)))
 
 			var sbuf [24]byte
 			print("init ", pkg, " @")
diff --git a/src/runtime/race.go b/src/runtime/race.go
index ce6b5b54681533bee45a198fccd9ad884b9aa642..7eaa9d2b721dbdb08093ae7f2631bff4b7c71e4d 100644
--- a/src/runtime/race.go
+++ b/src/runtime/race.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"unsafe"
 )
 
@@ -361,7 +362,7 @@ func raceinit() (gctx, pctx uintptr) {
 		throw("raceinit: race build must use cgo")
 	}
 
-	racecall(&__tsan_init, uintptr(unsafe.Pointer(&gctx)), uintptr(unsafe.Pointer(&pctx)), funcPC(racecallbackthunk), 0)
+	racecall(&__tsan_init, uintptr(unsafe.Pointer(&gctx)), uintptr(unsafe.Pointer(&pctx)), abi.FuncPCABI0(racecallbackthunk), 0)
 
 	// Round data segment to page boundaries, because it's used in mmap().
 	start := ^uintptr(0)
diff --git a/src/runtime/race/output_test.go b/src/runtime/race/output_test.go
index 99052071d0089d6a716e065c704fbbfa16b93e1f..63fcd847dc7e6c3100e62270f5d6b54cc424b669 100644
--- a/src/runtime/race/output_test.go
+++ b/src/runtime/race/output_test.go
@@ -148,7 +148,7 @@ exit status 66
 package main
 func main() {
 	done := make(chan bool)
-	x := 0
+	x := 0; _ = x
 	go func() {
 		x = 42
 		done <- true
@@ -162,7 +162,7 @@ func main() {
 package main
 func main() {
 	done := make(chan bool)
-	x := 0
+	x := 0; _ = x
 	go func() {
 		x = 42
 		done <- true
@@ -178,7 +178,7 @@ func main() {
 package main
 func main() {
 	done := make(chan bool)
-	x := 0
+	x := 0; _ = x
 	go func() {
 		x = 42
 		done <- true
diff --git a/src/runtime/race_amd64.s b/src/runtime/race_amd64.s
index 8d4813eadddd5e68a9303a2658d7c7920c22d056..d42e415dca59b26c6bfdc9fecba1c2070f8fe25d 100644
--- a/src/runtime/race_amd64.s
+++ b/src/runtime/race_amd64.s
@@ -46,11 +46,7 @@
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·raceread(SB), NOSPLIT, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
-#else
-	MOVQ	addr+0(FP), RARG1
-#endif
 	MOVQ	(SP), RARG2
 	// void __tsan_read(ThreadState *thr, void *addr, void *pc);
 	MOVQ	$__tsan_read(SB), AX
@@ -76,11 +72,7 @@ TEXT	runtime·racereadpc(SB), NOSPLIT, $0-24
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·racewrite(SB), NOSPLIT, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
-#else
-	MOVQ	addr+0(FP), RARG1
-#endif
 	MOVQ	(SP), RARG2
 	// void __tsan_write(ThreadState *thr, void *addr, void *pc);
 	MOVQ	$__tsan_write(SB), AX
@@ -131,13 +123,8 @@ TEXT	runtime·racereadrangepc1(SB), NOSPLIT, $0-24
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·racewriterange(SB), NOSPLIT, $0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
 	MOVQ	BX, RARG2
-#else
-	MOVQ	addr+0(FP), RARG1
-	MOVQ	size+8(FP), RARG2
-#endif
 	MOVQ	(SP), RARG3
 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVQ	$__tsan_write_range(SB), AX
@@ -161,10 +148,6 @@ TEXT	runtime·racewriterangepc1(SB), NOSPLIT, $0-24
 // If addr (RARG1) is out of range, do nothing.
 // Otherwise, setup goroutine context and invoke racecall. Other arguments already set.
 TEXT	racecalladdr<>(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	// Check that addr is within [arenastart, arenaend) or within [racedatastart, racedataend).
 	CMPQ	RARG1, runtime·racearenastart(SB)
@@ -192,10 +175,6 @@ TEXT	runtime·racefuncenter(SB), NOSPLIT, $0-8
 // R11 = caller's return address
 TEXT	racefuncenter<>(SB), NOSPLIT, $0-0
 	MOVQ	DX, BX		// save function entry context (for closures)
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	MOVQ	R11, RARG1
 	// void __tsan_func_enter(ThreadState *thr, void *pc);
@@ -208,10 +187,6 @@ TEXT	racefuncenter<>(SB), NOSPLIT, $0-0
 // func runtime·racefuncexit()
 // Called from instrumented code.
 TEXT	runtime·racefuncexit(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	// void __tsan_func_exit(ThreadState *thr);
 	MOVQ	$__tsan_func_exit(SB), AX
@@ -370,10 +345,6 @@ racecallatomic_data:
 	JAE	racecallatomic_ignore
 racecallatomic_ok:
 	// Addr is within the good range, call the atomic function.
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	MOVQ	8(SP), RARG1	// caller pc
 	MOVQ	(SP), RARG2	// pc
@@ -385,10 +356,6 @@ racecallatomic_ignore:
 	// An attempt to synchronize on the address would cause crash.
 	MOVQ	AX, BX	// remember the original function
 	MOVQ	$__tsan_go_ignore_sync_begin(SB), AX
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	CALL	racecall<>(SB)
 	MOVQ	BX, AX	// restore the original function
@@ -416,10 +383,6 @@ TEXT	runtime·racecall(SB), NOSPLIT, $0-0
 
 // Switches SP to g0 stack and calls (AX). Arguments already set.
 TEXT	racecall<>(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_m(R14), R13
 	// Switch to g0 stack.
 	MOVQ	SP, R12		// callee-saved, preserved across the CALL
@@ -441,9 +404,7 @@ call:
 // The overall effect of Go->C->Go call chain is similar to that of mcall.
 // RARG0 contains command code. RARG1 contains command-specific context.
 // See racecallback for command codes.
-// Defined as ABIInternal so as to avoid introducing a wrapper,
-// because its address is passed to C via funcPC.
-TEXT	runtime·racecallbackthunk(SB), NOSPLIT, $0-0
+TEXT	runtime·racecallbackthunk(SB), NOSPLIT, $0-0
 	// Handle command raceGetProcCmd (0) here.
 	// First, code below assumes that we are on curg, while raceGetProcCmd
 	// can be executed on g0. Second, it is called frequently, so will
diff --git a/src/runtime/race_arm64.s b/src/runtime/race_arm64.s
index c6d5b91edc0f3ee8a7bd29f081b9f78d639d46ad..2b2413b6b771ff8785dd81bdd7a62df0b767e2dc 100644
--- a/src/runtime/race_arm64.s
+++ b/src/runtime/race_arm64.s
@@ -43,8 +43,14 @@
 
 // func runtime·raceread(addr uintptr)
 // Called from instrumented code.
-TEXT	runtime·raceread(SB), NOSPLIT, $0-8
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·raceread(SB), NOSPLIT, $0-8
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
+#endif
 	MOVD	LR, R2
 	// void __tsan_read(ThreadState *thr, void *addr, void *pc);
 	MOVD	$__tsan_read(SB), R9
@@ -66,8 +72,14 @@ TEXT	runtime·racereadpc(SB), NOSPLIT, $0-24
 
 // func runtime·racewrite(addr uintptr)
 // Called from instrumented code.
-TEXT	runtime·racewrite(SB), NOSPLIT, $0-8
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·racewrite(SB), NOSPLIT, $0-8
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
+#endif
 	MOVD	LR, R2
 	// void __tsan_write(ThreadState *thr, void *addr, void *pc);
 	MOVD	$__tsan_write(SB), R9
@@ -89,9 +101,16 @@ TEXT	runtime·racewritepc(SB), NOSPLIT, $0-24
 
 // func runtime·racereadrange(addr, size uintptr)
 // Called from instrumented code.
-TEXT	runtime·racereadrange(SB), NOSPLIT, $0-16
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·racereadrange(SB), NOSPLIT, $0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R2	// size
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
 	MOVD	size+8(FP), R2
+#endif
 	MOVD	LR, R3
 	// void __tsan_read_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVD	$__tsan_read_range(SB), R9
@@ -114,9 +133,16 @@ TEXT	runtime·racereadrangepc1(SB), NOSPLIT, $0-24
 
 // func runtime·racewriterange(addr, size uintptr)
 // Called from instrumented code.
-TEXT	runtime·racewriterange(SB), NOSPLIT, $0-16
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·racewriterange(SB), NOSPLIT, $0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R2	// size
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
 	MOVD	size+8(FP), R2
+#endif
 	MOVD	LR, R3
 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVD	$__tsan_write_range(SB), R9
diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index b238da8f514e42b7973a0c148621a0ebb1e6e249..b6c3cbfff4806d2600730a6ebe77153598ed3f58 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -6,8 +6,8 @@ package runtime
 
 import (
 	"internal/bytealg"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -55,7 +55,7 @@ var (
 // nosplit for use in linux startup sysargs
 //go:nosplit
 func argv_index(argv **byte, i int32) *byte {
-	return *(**byte)(add(unsafe.Pointer(argv), uintptr(i)*sys.PtrSize))
+	return *(**byte)(add(unsafe.Pointer(argv), uintptr(i)*goarch.PtrSize))
 }
 
 func args(c int32, v **byte) {
@@ -190,10 +190,10 @@ func check() {
 	if unsafe.Sizeof(j) != 8 {
 		throw("bad j")
 	}
-	if unsafe.Sizeof(k) != sys.PtrSize {
+	if unsafe.Sizeof(k) != goarch.PtrSize {
 		throw("bad k")
 	}
-	if unsafe.Sizeof(l) != sys.PtrSize {
+	if unsafe.Sizeof(l) != goarch.PtrSize {
 		throw("bad l")
 	}
 	if unsafe.Sizeof(x1) != 1 {
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 5051ec4d3e95eed3f46fde743261d9f19628d385..271d57e5d0b9a6755aeaaa97c822d4b43ab2c7ae 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -5,8 +5,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -505,7 +505,7 @@ const (
 	// tlsSlots is the number of pointer-sized slots reserved for TLS on some platforms,
 	// like Windows.
 	tlsSlots = 6
-	tlsSize  = tlsSlots * sys.PtrSize
+	tlsSize  = tlsSlots * goarch.PtrSize
 )
 
 type m struct {
@@ -613,8 +613,8 @@ type p struct {
 	pcache      pageCache
 	raceprocctx uintptr
 
-	deferpool    [5][]*_defer // pool of available defer structs of different sizes (see panic.go)
-	deferpoolbuf [5][32]*_defer
+	deferpool    []*_defer // pool of available defer structs (see panic.go)
+	deferpoolbuf [32]*_defer
 
 	// Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen.
 	goidcache    uint64
@@ -795,9 +795,9 @@ type schedt struct {
 	sudoglock  mutex
 	sudogcache *sudog
 
-	// Central pool of available defer structs of different sizes.
+	// Central pool of available defer structs.
 	deferlock mutex
-	deferpool [5]*_defer
+	deferpool *_defer
 
 	// freem is the list of m's waiting to be freed when their
 	// m.exited is set. Linked through m.freelink.
@@ -924,7 +924,7 @@ func extendRandom(r []byte, n int) {
 			w = 16
 		}
 		h := memhash(unsafe.Pointer(&r[n-w]), uintptr(nanotime()), uintptr(w))
-		for i := 0; i < sys.PtrSize && n < len(r); i++ {
+		for i := 0; i < goarch.PtrSize && n < len(r); i++ {
 			r[n] = byte(h)
 			n++
 			h >>= 8
@@ -934,25 +934,24 @@ func extendRandom(r []byte, n int) {
 
 // A _defer holds an entry on the list of deferred calls.
 // If you add a field here, add code to clear it in freedefer and deferProcStack
-// This struct must match the code in cmd/compile/internal/reflectdata/reflect.go:deferstruct
-// and cmd/compile/internal/gc/ssa.go:(*state).call.
+// This struct must match the code in cmd/compile/internal/ssagen/ssa.go:deferstruct
+// and cmd/compile/internal/ssagen/ssa.go:(*state).call.
 // Some defers will be allocated on the stack and some on the heap.
 // All defers are logically part of the stack, so write barriers to
 // initialize them are not required. All defers must be manually scanned,
 // and for heap defers, marked.
 type _defer struct {
-	siz     int32 // includes both arguments and results
 	started bool
 	heap    bool
 	// openDefer indicates that this _defer is for a frame with open-coded
 	// defers. We have only one defer record for the entire frame (which may
 	// currently have 0, 1, or more defers active).
 	openDefer bool
-	sp        uintptr  // sp at time of defer
-	pc        uintptr  // pc at time of defer
-	fn        *funcval // can be nil for open-coded defers
-	_panic    *_panic  // panic that is running defer
-	link      *_defer
+	sp        uintptr // sp at time of defer
+	pc        uintptr // pc at time of defer
+	fn        func()  // can be nil for open-coded defers
+	_panic    *_panic // panic that is running defer
+	link      *_defer // next defer on G; can point to either heap or stack!
 
 	// If openDefer is true, the fields below record values about the stack
 	// frame and associated function that has the open-coded defer(s). sp
@@ -1129,7 +1128,6 @@ var (
 	// Set on startup in asm_{386,amd64}.s
 	processorVersionInfo uint32
 	isIntel              bool
-	lfenceBeforeRdtsc    bool
 
 	goarm uint8 // set by cmd/link on arm systems
 )
diff --git a/src/runtime/select.go b/src/runtime/select.go
index 06edb69f429ba0c1ac01279de0204d10e71bda8a..ee1f95ffa9ed304fa82aaf562356ea6b10110eea 100644
--- a/src/runtime/select.go
+++ b/src/runtime/select.go
@@ -7,6 +7,7 @@ package runtime
 // This file contains the implementation of Go select statements.
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -22,8 +23,8 @@ type scase struct {
 }
 
 var (
-	chansendpc = funcPC(chansend)
-	chanrecvpc = funcPC(chanrecv)
+	chansendpc = abi.FuncPCABIInternal(chansend)
+	chanrecvpc = abi.FuncPCABIInternal(chanrecv)
 )
 
 func selectsetpc(pc *uintptr) {
diff --git a/src/runtime/signal_386.go b/src/runtime/signal_386.go
index 5824eaddb5630d5b2dc49bc68532c974cde09d81..69a59e6dcff2a9e60ce336a1513b9b4afac5d7b2 100644
--- a/src/runtime/signal_386.go
+++ b/src/runtime/signal_386.go
@@ -8,7 +8,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -42,17 +43,17 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	sp := uintptr(c.esp())
 
 	if shouldPushSigpanic(gp, pc, *(*uintptr)(unsafe.Pointer(sp))) {
-		c.pushCall(funcPC(sigpanic), pc)
+		c.pushCall(abi.FuncPCABIInternal(sigpanic), pc)
 	} else {
 		// Not safe to push the call. Just clobber the frame.
-		c.set_eip(uint32(funcPC(sigpanic)))
+		c.set_eip(uint32(abi.FuncPCABIInternal(sigpanic)))
 	}
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
 	// Make it look like we called target at resumePC.
 	sp := uintptr(c.esp())
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = resumePC
 	c.set_esp(uint32(sp))
 	c.set_eip(uint32(targetPC))
diff --git a/src/runtime/signal_aix_ppc64.go b/src/runtime/signal_aix_ppc64.go
index a0becd431ebdf6728d93449ada1eca644606cbf9..5999d9dc3d01d407d4999eaa191a2fff0ffbf79c 100644
--- a/src/runtime/signal_aix_ppc64.go
+++ b/src/runtime/signal_aix_ppc64.go
@@ -8,7 +8,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -82,5 +82,5 @@ func (c *sigctxt) set_link(x uint64) { c.regs().lr = x }
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_amd64.go b/src/runtime/signal_amd64.go
index e45fbb4a87a39f8c95973d209c1d93c07b00fd59..20490cffbf5174f08503296fef6d36ac0606bbfd 100644
--- a/src/runtime/signal_amd64.go
+++ b/src/runtime/signal_amd64.go
@@ -9,7 +9,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -70,17 +71,17 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	// Go special registers. We inject sigpanic0 (instead of sigpanic),
 	// which takes care of that.
 	if shouldPushSigpanic(gp, pc, *(*uintptr)(unsafe.Pointer(sp))) {
-		c.pushCall(funcPC(sigpanic0), pc)
+		c.pushCall(abi.FuncPCABI0(sigpanic0), pc)
 	} else {
 		// Not safe to push the call. Just clobber the frame.
-		c.set_rip(uint64(funcPC(sigpanic0)))
+		c.set_rip(uint64(abi.FuncPCABI0(sigpanic0)))
 	}
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
 	// Make it look like we called target at resumePC.
 	sp := uintptr(c.rsp())
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = resumePC
 	c.set_rsp(uint64(sp))
 	c.set_rip(uint64(targetPC))
diff --git a/src/runtime/signal_arm.go b/src/runtime/signal_arm.go
index 4d9c6224a29d1e6a64174b38fadcf22f8995b3c1..a0780788f809fc7a04fa7ca5d173cdea1325f89f 100644
--- a/src/runtime/signal_arm.go
+++ b/src/runtime/signal_arm.go
@@ -7,7 +7,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func dumpregs(c *sigctxt) {
 	print("trap    ", hex(c.trap()), "\n")
@@ -61,7 +64,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 
 	// In case we are panicking from external C code
 	c.set_r10(uint32(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint32(funcPC(sigpanic)))
+	c.set_pc(uint32(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_arm64.go b/src/runtime/signal_arm64.go
index f04750084f4b011e5028ed08375548530a4d0318..9d4a8b8a99d54e6516418b84e44d8d7908b0d9d5 100644
--- a/src/runtime/signal_arm64.go
+++ b/src/runtime/signal_arm64.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -77,7 +78,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 
 	// In case we are panicking from external C code
 	c.set_r28(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_linux_386.go b/src/runtime/signal_linux_386.go
index 13d9df407102e5fc366fc598d7988fc6127c1547..321518c18e3f50a681280270b8e50910e6716735 100644
--- a/src/runtime/signal_linux_386.go
+++ b/src/runtime/signal_linux_386.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -42,5 +42,5 @@ func (c *sigctxt) set_eip(x uint32)     { c.regs().eip = x }
 func (c *sigctxt) set_esp(x uint32)     { c.regs().esp = x }
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint32) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_amd64.go b/src/runtime/signal_linux_amd64.go
index 210e8967e5da299c473920af3cee344e77eaf084..573b11839740de5c436482202fc89a07141ad3fe 100644
--- a/src/runtime/signal_linux_amd64.go
+++ b/src/runtime/signal_linux_amd64.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -52,5 +52,5 @@ func (c *sigctxt) set_rip(x uint64)     { c.regs().rip = x }
 func (c *sigctxt) set_rsp(x uint64)     { c.regs().rsp = x }
 func (c *sigctxt) set_sigcode(x uint64) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_arm.go b/src/runtime/signal_linux_arm.go
index 876b505917394fc9875fdc81ce637d7d2a0f6365..eb107d68d1b181937ead1fa64089b647d5b0b931 100644
--- a/src/runtime/signal_linux_arm.go
+++ b/src/runtime/signal_linux_arm.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -54,5 +54,5 @@ func (c *sigctxt) set_r10(x uint32) { c.regs().r10 = x }
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint32) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_arm64.go b/src/runtime/signal_linux_arm64.go
index 2075f253d7d0f848e897bee7ba74015a3762dde7..4ccc03079235465e3301365c7e6cf7f156549c21 100644
--- a/src/runtime/signal_linux_arm64.go
+++ b/src/runtime/signal_linux_arm64.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -67,5 +67,5 @@ func (c *sigctxt) set_lr(x uint64)  { c.regs().regs[30] = x }
 func (c *sigctxt) set_r28(x uint64) { c.regs().regs[28] = x }
 
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_mips64x.go b/src/runtime/signal_linux_mips64x.go
index f0a75ac3ea571598ab610b547b0c2d1109c234e0..e62d6a93fd2fe9a0a1079ba9623560a138f251d8 100644
--- a/src/runtime/signal_linux_mips64x.go
+++ b/src/runtime/signal_linux_mips64x.go
@@ -9,7 +9,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -75,5 +75,5 @@ func (c *sigctxt) set_link(x uint64) { c.regs().sc_regs[31] = x }
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_ppc64x.go b/src/runtime/signal_linux_ppc64x.go
index d9d3e55ec2000976a2935b4962018fbc61f2ad44..d2eeb39eadd39c66a1b75576097e0c485f896fd7 100644
--- a/src/runtime/signal_linux_ppc64x.go
+++ b/src/runtime/signal_linux_ppc64x.go
@@ -9,7 +9,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -79,5 +79,5 @@ func (c *sigctxt) set_link(x uint64) { c.regs().link = x }
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_riscv64.go b/src/runtime/signal_linux_riscv64.go
index 9f68e5c548fb45b44300fc26efad510d6e6c5f97..b26450dbfac5cdbc2cfc4d1a236e41f4ab2bc0e7 100644
--- a/src/runtime/signal_linux_riscv64.go
+++ b/src/runtime/signal_linux_riscv64.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -64,5 +64,5 @@ func (c *sigctxt) set_gp(x uint64) { c.regs().sc_regs.gp = x }
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_s390x.go b/src/runtime/signal_linux_s390x.go
index 12d5c315931c89c5764e6813edbf55485b9c58be..18c3b115efc87f05b249d2ba51173d4388fdba2e 100644
--- a/src/runtime/signal_linux_s390x.go
+++ b/src/runtime/signal_linux_s390x.go
@@ -5,6 +5,8 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -53,7 +55,7 @@ func (c *sigctxt) set_sp(x uint64)      { c.regs().gregs[15] = x }
 func (c *sigctxt) set_pc(x uint64)      { c.regs().psw_addr = x }
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
 
 func dumpregs(c *sigctxt) {
@@ -107,7 +109,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	// In case we are panicking from external C code
 	c.set_r0(0)
 	c.set_r13(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_mips64x.go b/src/runtime/signal_mips64x.go
index 1616b570278a0ce8f91e0f702007b4f5677aba81..87dfa724c4758e7c75b0b60fe21411288ecf4ea5 100644
--- a/src/runtime/signal_mips64x.go
+++ b/src/runtime/signal_mips64x.go
@@ -9,7 +9,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -68,7 +69,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	// functions are correctly handled. This smashes
 	// the stack frame but we're not going back there
 	// anyway.
-	sp := c.sp() - sys.PtrSize
+	sp := c.sp() - goarch.PtrSize
 	c.set_sp(sp)
 	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
 
@@ -80,7 +81,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	}
 
 	// In case we are panicking from external C code
-	sigpanicPC := uint64(funcPC(sigpanic))
+	sigpanicPC := uint64(abi.FuncPCABIInternal(sigpanic))
 	c.set_r28(sigpanicPC >> 32 << 32) // RSB register
 	c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
 	c.set_pc(sigpanicPC)
diff --git a/src/runtime/signal_mipsx.go b/src/runtime/signal_mipsx.go
index dcc7f1e9dd5e035e4caae63fbef5d181be917d2d..5067799bd6bd75368eac70205db44a38b906849d 100644
--- a/src/runtime/signal_mipsx.go
+++ b/src/runtime/signal_mipsx.go
@@ -9,6 +9,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -78,7 +79,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 
 	// In case we are panicking from external C code
 	c.set_r30(uint32(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint32(funcPC(sigpanic)))
+	c.set_pc(uint32(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_ppc64x.go b/src/runtime/signal_ppc64x.go
index f2225da9a1771d53decc142e532630605f8a5da4..8a39d59957695ce14af2624fb51cf3b2ef8f2d19 100644
--- a/src/runtime/signal_ppc64x.go
+++ b/src/runtime/signal_ppc64x.go
@@ -9,6 +9,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -83,8 +84,8 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	// In case we are panicking from external C code
 	c.set_r0(0)
 	c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_r12(uint64(funcPC(sigpanic)))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_r12(uint64(abi.FuncPCABIInternal(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_riscv64.go b/src/runtime/signal_riscv64.go
index e6b1b14130e53b3960f57152d5b8926da2781759..8a24e4e36a9977f2c91ac982f0c6dc6a2ed693d3 100644
--- a/src/runtime/signal_riscv64.go
+++ b/src/runtime/signal_riscv64.go
@@ -8,7 +8,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -63,7 +64,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 	// functions are correctly handled. This smashes
 	// the stack frame but we're not going back there
 	// anyway.
-	sp := c.sp() - sys.PtrSize
+	sp := c.sp() - goarch.PtrSize
 	c.set_sp(sp)
 	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.ra()
 
@@ -76,7 +77,7 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
 
 	// In case we are panicking from external C code
 	c.set_gp(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
@@ -84,7 +85,7 @@ func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
 	// push the call. The function being pushed is responsible
 	// for restoring the LR and setting the SP back.
 	// This extra slot is known to gentraceback.
-	sp := c.sp() - sys.PtrSize
+	sp := c.sp() - goarch.PtrSize
 	c.set_sp(sp)
 	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.ra()
 	// Set up PC and LR to pretend the function being signaled
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 6096760b50c2420cf8bd39ec4ea62e92ec668917..8117582855db02d55e1b874a4f71630427f8ed30 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -143,7 +144,7 @@ func initsig(preinit bool) {
 		}
 
 		handlingSig[i] = 1
-		setsig(i, funcPC(sighandler))
+		setsig(i, abi.FuncPCABIInternal(sighandler))
 	}
 }
 
@@ -194,7 +195,7 @@ func sigenable(sig uint32) {
 		<-maskUpdatedChan
 		if atomic.Cas(&handlingSig[sig], 0, 1) {
 			atomic.Storeuintptr(&fwdSig[sig], getsig(sig))
-			setsig(sig, funcPC(sighandler))
+			setsig(sig, abi.FuncPCABIInternal(sighandler))
 		}
 	}
 }
@@ -271,7 +272,7 @@ func setProcessCPUProfiler(hz int32) {
 		// Enable the Go signal handler if not enabled.
 		if atomic.Cas(&handlingSig[_SIGPROF], 0, 1) {
 			atomic.Storeuintptr(&fwdSig[_SIGPROF], getsig(_SIGPROF))
-			setsig(_SIGPROF, funcPC(sighandler))
+			setsig(_SIGPROF, abi.FuncPCABIInternal(sighandler))
 		}
 
 		var it itimerval
@@ -329,7 +330,7 @@ func doSigPreempt(gp *g, ctxt *sigctxt) {
 	if wantAsyncPreempt(gp) {
 		if ok, newpc := isAsyncSafePoint(gp, ctxt.sigpc(), ctxt.sigsp(), ctxt.siglr()); ok {
 			// Adjust the PC and inject a call to asyncPreempt.
-			ctxt.pushCall(funcPC(asyncPreempt), newpc)
+			ctxt.pushCall(abi.FuncPCABI0(asyncPreempt), newpc)
 		}
 	}
 
@@ -843,7 +844,7 @@ func raisebadsignal(sig uint32, c *sigctxt) {
 	// We may receive another instance of the signal before we
 	// restore the Go handler, but that is not so bad: we know
 	// that the Go program has been ignoring the signal.
-	setsig(sig, funcPC(sighandler))
+	setsig(sig, abi.FuncPCABIInternal(sighandler))
 }
 
 //go:nosplit
diff --git a/src/runtime/signal_windows.go b/src/runtime/signal_windows.go
index f2ce24d735cf1c20ebc29ff797edeca05d866ca0..3fe352ef575bb780a2705292c905c5798390e1e1 100644
--- a/src/runtime/signal_windows.go
+++ b/src/runtime/signal_windows.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -27,15 +28,15 @@ func firstcontinuetramp()
 func lastcontinuetramp()
 
 func initExceptionHandler() {
-	stdcall2(_AddVectoredExceptionHandler, 1, funcPC(exceptiontramp))
+	stdcall2(_AddVectoredExceptionHandler, 1, abi.FuncPCABI0(exceptiontramp))
 	if _AddVectoredContinueHandler == nil || GOARCH == "386" {
 		// use SetUnhandledExceptionFilter for windows-386 or
 		// if VectoredContinueHandler is unavailable.
 		// note: SetUnhandledExceptionFilter handler won't be called, if debugging.
-		stdcall1(_SetUnhandledExceptionFilter, funcPC(lastcontinuetramp))
+		stdcall1(_SetUnhandledExceptionFilter, abi.FuncPCABI0(lastcontinuetramp))
 	} else {
-		stdcall2(_AddVectoredContinueHandler, 1, funcPC(firstcontinuetramp))
-		stdcall2(_AddVectoredContinueHandler, 0, funcPC(lastcontinuetramp))
+		stdcall2(_AddVectoredContinueHandler, 1, abi.FuncPCABI0(firstcontinuetramp))
+		stdcall2(_AddVectoredContinueHandler, 0, abi.FuncPCABI0(lastcontinuetramp))
 	}
 }
 
@@ -133,7 +134,7 @@ func exceptionhandler(info *exceptionrecord, r *context, gp *g) int32 {
 	// The exception is not from asyncPreempt, so not to push a
 	// sigpanic call to make it look like that. Instead, just
 	// overwrite the PC. (See issue #35773)
-	if r.ip() != 0 && r.ip() != funcPC(asyncPreempt) {
+	if r.ip() != 0 && r.ip() != abi.FuncPCABI0(asyncPreempt) {
 		sp := unsafe.Pointer(r.sp())
 		delta := uintptr(sys.StackAlign)
 		sp = add(sp, -delta)
@@ -145,7 +146,7 @@ func exceptionhandler(info *exceptionrecord, r *context, gp *g) int32 {
 			*((*uintptr)(sp)) = r.ip()
 		}
 	}
-	r.set_ip(funcPC(sigpanic0))
+	r.set_ip(abi.FuncPCABI0(sigpanic0))
 	return _EXCEPTION_CONTINUE_EXECUTION
 }
 
@@ -183,6 +184,17 @@ func lastcontinuehandler(info *exceptionrecord, r *context, gp *g) int32 {
 		return _EXCEPTION_CONTINUE_SEARCH
 	}
 
+	// VEH is called before SEH, but arm64 MSVC DLLs use SEH to trap
+	// illegal instructions during runtime initialization to determine
+	// CPU features, so if we make it to the last handler and we're
+	// arm64 and it's an illegal instruction and this is coming from
+	// non-Go code, then assume it's this runtime probing happen, and
+	// pass that onward to SEH.
+	if GOARCH == "arm64" && info.exceptioncode == _EXCEPTION_ILLEGAL_INSTRUCTION &&
+		(r.ip() < firstmoduledata.text || firstmoduledata.etext < r.ip()) {
+		return _EXCEPTION_CONTINUE_SEARCH
+	}
+
 	winthrow(info, r, gp)
 	return 0 // not reached
 }
diff --git a/src/runtime/slice.go b/src/runtime/slice.go
index 01cdcaeee3b0b1e0b7d0395ed339f970be4f2036..e8267be885df1670ed24265c8e5a890709f72a3b 100644
--- a/src/runtime/slice.go
+++ b/src/runtime/slice.go
@@ -5,6 +5,8 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/math"
 	"runtime/internal/sys"
 	"unsafe"
@@ -68,7 +70,7 @@ func makeslicecopy(et *_type, tolen int, fromlen int, from unsafe.Pointer) unsaf
 
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(makeslicecopy)
+		pc := abi.FuncPCABIInternal(makeslicecopy)
 		racereadrangepc(from, copymem, callerpc, pc)
 	}
 	if msanenabled {
@@ -162,7 +164,7 @@ func panicunsafeslicelen() {
 func growslice(et *_type, old slice, cap int) slice {
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadrangepc(old.array, uintptr(old.len*int(et.size)), callerpc, funcPC(growslice))
+		racereadrangepc(old.array, uintptr(old.len*int(et.size)), callerpc, abi.FuncPCABIInternal(growslice))
 	}
 	if msanenabled {
 		msanread(old.array, uintptr(old.len*int(et.size)))
@@ -212,15 +214,15 @@ func growslice(et *_type, old slice, cap int) slice {
 		capmem = roundupsize(uintptr(newcap))
 		overflow = uintptr(newcap) > maxAlloc
 		newcap = int(capmem)
-	case et.size == sys.PtrSize:
-		lenmem = uintptr(old.len) * sys.PtrSize
-		newlenmem = uintptr(cap) * sys.PtrSize
-		capmem = roundupsize(uintptr(newcap) * sys.PtrSize)
-		overflow = uintptr(newcap) > maxAlloc/sys.PtrSize
-		newcap = int(capmem / sys.PtrSize)
+	case et.size == goarch.PtrSize:
+		lenmem = uintptr(old.len) * goarch.PtrSize
+		newlenmem = uintptr(cap) * goarch.PtrSize
+		capmem = roundupsize(uintptr(newcap) * goarch.PtrSize)
+		overflow = uintptr(newcap) > maxAlloc/goarch.PtrSize
+		newcap = int(capmem / goarch.PtrSize)
 	case isPowerOfTwo(et.size):
 		var shift uintptr
-		if sys.PtrSize == 8 {
+		if goarch.PtrSize == 8 {
 			// Mask shift for better code generation.
 			shift = uintptr(sys.Ctz64(uint64(et.size))) & 63
 		} else {
@@ -298,7 +300,7 @@ func slicecopy(toPtr unsafe.Pointer, toLen int, fromPtr unsafe.Pointer, fromLen
 	size := uintptr(n) * width
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(slicecopy)
+		pc := abi.FuncPCABIInternal(slicecopy)
 		racereadrangepc(fromPtr, size, callerpc, pc)
 		racewriterangepc(toPtr, size, callerpc, pc)
 	}
diff --git a/src/runtime/softfloat64.go b/src/runtime/softfloat64.go
index 13bee6c1d7a06499d838ef6cf2356f1dd3db9774..084aa132d9c6bd2636b6a58a452798264544e37b 100644
--- a/src/runtime/softfloat64.go
+++ b/src/runtime/softfloat64.go
@@ -562,36 +562,38 @@ func f64toint64(x uint64) int64 {
 	return val
 }
 
-func f64touint64(x float64) uint64 {
-	if x < float64(1<<63) {
-		return uint64(int64(x))
+func f64touint64(x uint64) uint64 {
+	var m uint64 = 0x43e0000000000000 // float64 1<<63
+	if fgt64(m, x) {
+		return uint64(f64toint64(x))
 	}
-	y := x - float64(1<<63)
-	z := uint64(int64(y))
+	y := fadd64(x, -m)
+	z := uint64(f64toint64(y))
 	return z | (1 << 63)
 }
 
-func f32touint64(x float32) uint64 {
-	if x < float32(1<<63) {
-		return uint64(int64(x))
+func f32touint64(x uint32) uint64 {
+	var m uint32 = 0x5f000000 // float32 1<<63
+	if fgt32(m, x) {
+		return uint64(f32toint64(x))
 	}
-	y := x - float32(1<<63)
-	z := uint64(int64(y))
+	y := fadd32(x, -m)
+	z := uint64(f32toint64(y))
 	return z | (1 << 63)
 }
 
-func fuint64to64(x uint64) float64 {
+func fuint64to64(x uint64) uint64 {
 	if int64(x) >= 0 {
-		return float64(int64(x))
+		return fint64to64(int64(x))
 	}
-	// See ../cmd/compile/internal/gc/ssa.go:uint64Tofloat
+	// See ../cmd/compile/internal/ssagen/ssa.go:uint64Tofloat
 	y := x & 1
 	z := x >> 1
 	z = z | y
-	r := float64(int64(z))
-	return r + r
+	r := fint64to64(int64(z))
+	return fadd64(r, r)
 }
 
-func fuint64to32(x uint64) float32 {
-	return float32(fuint64to64(x))
+func fuint64to32(x uint64) uint32 {
+	return f64to32(fuint64to64(x))
 }
diff --git a/src/runtime/stack.go b/src/runtime/stack.go
index 6e0d157630b47ad540d8f0e7967748ba4b628da0..54ad66dca2d202697926af9ea5d75729336868bf 100644
--- a/src/runtime/stack.go
+++ b/src/runtime/stack.go
@@ -7,6 +7,8 @@ package runtime
 import (
 	"internal/abi"
 	"internal/cpu"
+	"internal/goarch"
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -67,7 +69,7 @@ const (
 	// to each stack below the usual guard area for OS-specific
 	// purposes like signal handling. Used on Windows, Plan 9,
 	// and iOS because they do not use a separate stack.
-	_StackSystem = sys.GoosWindows*512*sys.PtrSize + sys.GoosPlan9*512 + sys.GoosIos*sys.GoarchArm64*1024
+	_StackSystem = goos.IsWindows*512*goarch.PtrSize + goos.IsPlan9*512 + goos.IsIos*goarch.IsArm64*1024
 
 	// The minimum size of stack used by Go code
 	_StackMin = 2048
@@ -125,7 +127,7 @@ const (
 )
 
 const (
-	uintptrMask = 1<<(8*sys.PtrSize) - 1
+	uintptrMask = 1<<(8*goarch.PtrSize) - 1
 
 	// The values below can be stored to g.stackguard0 to force
 	// the next stack check to fail.
@@ -599,14 +601,14 @@ func adjustpointers(scanp unsafe.Pointer, bv *bitvector, adjinfo *adjustinfo, f
 	for i := uintptr(0); i < num; i += 8 {
 		if stackDebug >= 4 {
 			for j := uintptr(0); j < 8; j++ {
-				print("        ", add(scanp, (i+j)*sys.PtrSize), ":", ptrnames[bv.ptrbit(i+j)], ":", hex(*(*uintptr)(add(scanp, (i+j)*sys.PtrSize))), " # ", i, " ", *addb(bv.bytedata, i/8), "\n")
+				print("        ", add(scanp, (i+j)*goarch.PtrSize), ":", ptrnames[bv.ptrbit(i+j)], ":", hex(*(*uintptr)(add(scanp, (i+j)*goarch.PtrSize))), " # ", i, " ", *addb(bv.bytedata, i/8), "\n")
 			}
 		}
 		b := *(addb(bv.bytedata, i/8))
 		for b != 0 {
 			j := uintptr(sys.Ctz8(b))
 			b &= b - 1
-			pp := (*uintptr)(add(scanp, (i+j)*sys.PtrSize))
+			pp := (*uintptr)(add(scanp, (i+j)*goarch.PtrSize))
 		retry:
 			p := *pp
 			if f.valid() && 0 < p && p < minLegalPointer && debug.invalidptr != 0 {
@@ -655,13 +657,13 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 
 	// Adjust local variables if stack frame has been allocated.
 	if locals.n > 0 {
-		size := uintptr(locals.n) * sys.PtrSize
+		size := uintptr(locals.n) * goarch.PtrSize
 		adjustpointers(unsafe.Pointer(frame.varp-size), &locals, adjinfo, f)
 	}
 
 	// Adjust saved base pointer if there is one.
 	// TODO what about arm64 frame pointer adjustment?
-	if sys.ArchFamily == sys.AMD64 && frame.argp-frame.varp == 2*sys.PtrSize {
+	if goarch.ArchFamily == goarch.AMD64 && frame.argp-frame.varp == 2*goarch.PtrSize {
 		if stackDebug >= 3 {
 			print("      saved bp\n")
 		}
@@ -710,8 +712,8 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 				s = materializeGCProg(ptrdata, gcdata)
 				gcdata = (*byte)(unsafe.Pointer(s.startAddr))
 			}
-			for i := uintptr(0); i < ptrdata; i += sys.PtrSize {
-				if *addb(gcdata, i/(8*sys.PtrSize))>>(i/sys.PtrSize&7)&1 != 0 {
+			for i := uintptr(0); i < ptrdata; i += goarch.PtrSize {
+				if *addb(gcdata, i/(8*goarch.PtrSize))>>(i/goarch.PtrSize&7)&1 != 0 {
 					adjustpointer(adjinfo, unsafe.Pointer(p+i))
 				}
 			}
@@ -753,11 +755,6 @@ func adjustdefers(gp *g, adjinfo *adjustinfo) {
 		adjustpointer(adjinfo, unsafe.Pointer(&d.varp))
 		adjustpointer(adjinfo, unsafe.Pointer(&d.fd))
 	}
-
-	// Adjust defer argument blocks the same way we adjust active stack frames.
-	// Note: this code is after the loop above, so that if a defer record is
-	// stack allocated, we work on the copy in the new stack.
-	tracebackdefers(gp, adjustframe, noescape(unsafe.Pointer(adjinfo)))
 }
 
 func adjustpanics(gp *g, adjinfo *adjustinfo) {
@@ -1017,9 +1014,9 @@ func newstack() {
 		throw("missing stack in newstack")
 	}
 	sp := gp.sched.sp
-	if sys.ArchFamily == sys.AMD64 || sys.ArchFamily == sys.I386 || sys.ArchFamily == sys.WASM {
+	if goarch.ArchFamily == goarch.AMD64 || goarch.ArchFamily == goarch.I386 || goarch.ArchFamily == goarch.WASM {
 		// The call to morestack cost a word.
-		sp -= sys.PtrSize
+		sp -= goarch.PtrSize
 	}
 	if stackDebug >= 1 || sp < gp.stack.lo {
 		print("runtime: newstack sp=", hex(sp), " stack=[", hex(gp.stack.lo), ", ", hex(gp.stack.hi), "]\n",
@@ -1114,7 +1111,7 @@ func gostartcallfn(gobuf *gobuf, fv *funcval) {
 	if fv != nil {
 		fn = unsafe.Pointer(fv.fn)
 	} else {
-		fn = unsafe.Pointer(funcPC(nilfunc))
+		fn = unsafe.Pointer(abi.FuncPCABIInternal(nilfunc))
 	}
 	gostartcall(gobuf, fn, unsafe.Pointer(fv))
 }
@@ -1262,8 +1259,8 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args
 	// Local variables.
 	size := frame.varp - frame.sp
 	var minsize uintptr
-	switch sys.ArchFamily {
-	case sys.ARM64:
+	switch goarch.ArchFamily {
+	case goarch.ARM64:
 		minsize = sys.StackAlign
 	default:
 		minsize = sys.MinFrameSize
@@ -1298,7 +1295,7 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args
 			// In this case, arglen specifies how much of the args section is actually live.
 			// (It could be either all the args + results, or just the args.)
 			args = *frame.argmap
-			n := int32(frame.arglen / sys.PtrSize)
+			n := int32(frame.arglen / goarch.PtrSize)
 			if n < args.n {
 				args.n = n // Don't use more of the arguments than arglen.
 			}
@@ -1320,17 +1317,17 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args
 	}
 
 	// stack objects.
-	if GOARCH == "amd64" && unsafe.Sizeof(abi.RegArgs{}) > 0 && frame.argmap != nil {
+	if (GOARCH == "amd64" || GOARCH == "arm64") && unsafe.Sizeof(abi.RegArgs{}) > 0 && frame.argmap != nil {
 		// argmap is set when the function is reflect.makeFuncStub or reflect.methodValueCall.
 		// We don't actually use argmap in this case, but we need to fake the stack object
-		// record for these frames which contain an internal/abi.RegArgs at a hard-coded offset
-		// on amd64.
+		// record for these frames which contain an internal/abi.RegArgs at a hard-coded offset.
+		// This offset matches the assembly code on amd64 and arm64.
 		objs = methodValueCallFrameObjs
 	} else {
 		p := funcdata(f, _FUNCDATA_StackObjects)
 		if p != nil {
 			n := *(*uintptr)(p)
-			p = add(p, sys.PtrSize)
+			p = add(p, goarch.PtrSize)
 			*(*slice)(unsafe.Pointer(&objs)) = slice{array: noescape(p), len: int(n), cap: int(n)}
 			// Note: the noescape above is needed to keep
 			// getStackMap from "leaking param content:
diff --git a/src/runtime/string.go b/src/runtime/string.go
index d6030a1dca433b0d168d62665d930ba34b06965e..d6990dab9aa66e46dbf889bafb95449b7b5574b5 100644
--- a/src/runtime/string.go
+++ b/src/runtime/string.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
 	"internal/bytealg"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -88,14 +89,14 @@ func slicebytetostring(buf *tmpBuf, ptr *byte, n int) (str string) {
 		racereadrangepc(unsafe.Pointer(ptr),
 			uintptr(n),
 			getcallerpc(),
-			funcPC(slicebytetostring))
+			abi.FuncPCABIInternal(slicebytetostring))
 	}
 	if msanenabled {
 		msanread(unsafe.Pointer(ptr), uintptr(n))
 	}
 	if n == 1 {
 		p := unsafe.Pointer(&staticuint64s[*ptr])
-		if sys.BigEndian {
+		if goarch.BigEndian {
 			p = add(p, 7)
 		}
 		stringStructOf(&str).str = p
@@ -152,7 +153,7 @@ func slicebytetostringtmp(ptr *byte, n int) (str string) {
 		racereadrangepc(unsafe.Pointer(ptr),
 			uintptr(n),
 			getcallerpc(),
-			funcPC(slicebytetostringtmp))
+			abi.FuncPCABIInternal(slicebytetostringtmp))
 	}
 	if msanenabled && n > 0 {
 		msanread(unsafe.Pointer(ptr), uintptr(n))
@@ -203,7 +204,7 @@ func slicerunetostring(buf *tmpBuf, a []rune) string {
 		racereadrangepc(unsafe.Pointer(&a[0]),
 			uintptr(len(a))*unsafe.Sizeof(a[0]),
 			getcallerpc(),
-			funcPC(slicerunetostring))
+			abi.FuncPCABIInternal(slicerunetostring))
 	}
 	if msanenabled && len(a) > 0 {
 		msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 16d758320294509575295ad3388b747d5e159d85..8a520d7839e31e4fc7180f5e38b88be015c778e7 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -6,6 +6,7 @@ package runtime
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"internal/goexperiment"
 	"unsafe"
 )
@@ -176,8 +177,6 @@ func cgocallback(fn, frame, ctxt uintptr)
 
 func gogo(buf *gobuf)
 
-//go:noescape
-func jmpdefer(fv *funcval, argp uintptr)
 func asminit()
 func setg(gg *g)
 func breakpoint()
@@ -421,12 +420,5 @@ func sigpanic0()
 // structure that is at least large enough to hold the
 // registers the system supports.
 //
-// Currently it's set to zero because using the actual
-// constant will break every part of the toolchain that
-// uses finalizers or Windows callbacks to call functions
-// The value that is currently commented out there should be
-// the actual value once we're ready to use the register ABI
-// everywhere.
-//
 // Protected by finlock.
-var intArgRegs = abi.IntArgRegs * goexperiment.RegabiArgsInt
+var intArgRegs = abi.IntArgRegs * (goexperiment.RegabiArgsInt | goarch.IsAmd64)
diff --git a/src/runtime/stubs_arm64.go b/src/runtime/stubs_arm64.go
index f5e3bb4854083c5ef80f7b8d251c8a10865ba195..bd0533d158125a88eae804607274b40200eeba62 100644
--- a/src/runtime/stubs_arm64.go
+++ b/src/runtime/stubs_arm64.go
@@ -14,3 +14,10 @@ func save_g()
 func asmcgocall_no_g(fn, arg unsafe.Pointer)
 
 func emptyfunc()
+
+// Used by reflectcall and the reflect package.
+//
+// Spills/loads arguments in registers to/from an internal/abi.RegArgs
+// respectively. Does not follow the Go ABI.
+func spillArgs()
+func unspillArgs()
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 999300a58ec3404baf8ec991b522ffe942b096fe..d08aa0b320470506aa2ef42ba2f3ceecd58783d4 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -330,7 +331,6 @@ const (
 	funcID_gogo
 	funcID_gopanic
 	funcID_handleAsyncEvent
-	funcID_jmpdefer
 	funcID_mcall
 	funcID_morestack
 	funcID_mstart
@@ -568,7 +568,7 @@ const debugPcln = false
 func moduledataverify1(datap *moduledata) {
 	// Check that the pclntab's format is valid.
 	hdr := datap.pcHeader
-	if hdr.magic != 0xfffffffa || hdr.pad1 != 0 || hdr.pad2 != 0 || hdr.minLC != sys.PCQuantum || hdr.ptrSize != sys.PtrSize {
+	if hdr.magic != 0xfffffffa || hdr.pad1 != 0 || hdr.pad2 != 0 || hdr.minLC != sys.PCQuantum || hdr.ptrSize != goarch.PtrSize {
 		print("runtime: function symbol table header:", hex(hdr.magic), hex(hdr.pad1), hex(hdr.pad2), hex(hdr.minLC), hex(hdr.ptrSize))
 		if datap.pluginpath != "" {
 			print(", plugin:", datap.pluginpath)
@@ -786,7 +786,7 @@ type pcvalueCacheEnt struct {
 // For now, align to sys.PtrSize and reduce mod the number of entries.
 // In practice, this appears to be fairly randomly and evenly distributed.
 func pcvalueCacheKey(targetpc uintptr) uintptr {
-	return (targetpc / sys.PtrSize) % uintptr(len(pcvalueCache{}.entries))
+	return (targetpc / goarch.PtrSize) % uintptr(len(pcvalueCache{}.entries))
 }
 
 // Returns the PCData value, and the PC where this value starts.
@@ -955,7 +955,7 @@ func funcline(f funcInfo, targetpc uintptr) (file string, line int32) {
 
 func funcspdelta(f funcInfo, targetpc uintptr, cache *pcvalueCache) int32 {
 	x, _ := pcvalue(f, f.pcsp, targetpc, cache, true)
-	if x&(sys.PtrSize-1) != 0 {
+	if x&(goarch.PtrSize-1) != 0 {
 		print("invalid spdelta ", funcname(f), " ", hex(f.entry), " ", hex(targetpc), " ", hex(f.pcsp), " ", x, "\n")
 	}
 	return x
@@ -1014,13 +1014,13 @@ func funcdata(f funcInfo, i uint8) unsafe.Pointer {
 		return nil
 	}
 	p := add(unsafe.Pointer(&f.nfuncdata), unsafe.Sizeof(f.nfuncdata)+uintptr(f.npcdata)*4)
-	if sys.PtrSize == 8 && uintptr(p)&4 != 0 {
+	if goarch.PtrSize == 8 && uintptr(p)&4 != 0 {
 		if uintptr(unsafe.Pointer(f._func))&4 != 0 {
 			println("runtime: misaligned func", f._func)
 		}
 		p = add(p, 4)
 	}
-	return *(*unsafe.Pointer)(add(p, uintptr(i)*sys.PtrSize))
+	return *(*unsafe.Pointer)(add(p, uintptr(i)*goarch.PtrSize))
 }
 
 // step advances to the next pc, value pair in the encoded table.
diff --git a/src/runtime/sys_darwin_arm64.go b/src/runtime/sys_darwin_arm64.go
index 9c14f33a1ce2389778dd17c144c59dcd20b95fa3..e6d4c1be484716e9e3e5441a7c4cb6a70776c79c 100644
--- a/src/runtime/sys_darwin_arm64.go
+++ b/src/runtime/sys_darwin_arm64.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -14,14 +15,14 @@ import (
 //go:nosplit
 //go:cgo_unsafe_args
 func g0_pthread_key_create(k *pthreadkey, destructor uintptr) int32 {
-	return asmcgocall(unsafe.Pointer(funcPC(pthread_key_create_trampoline)), unsafe.Pointer(&k))
+	return asmcgocall(unsafe.Pointer(abi.FuncPCABI0(pthread_key_create_trampoline)), unsafe.Pointer(&k))
 }
 func pthread_key_create_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func g0_pthread_setspecific(k pthreadkey, value uintptr) int32 {
-	return asmcgocall(unsafe.Pointer(funcPC(pthread_setspecific_trampoline)), unsafe.Pointer(&k))
+	return asmcgocall(unsafe.Pointer(abi.FuncPCABI0(pthread_setspecific_trampoline)), unsafe.Pointer(&k))
 }
 func pthread_setspecific_trampoline()
 
@@ -53,7 +54,7 @@ func tlsinit(tlsg *uintptr, tlsbase *[_PTHREAD_KEYS_MAX]uintptr) {
 
 	for i, x := range tlsbase {
 		if x == magic {
-			*tlsg = uintptr(i * sys.PtrSize)
+			*tlsg = uintptr(i * goarch.PtrSize)
 			g0_pthread_setspecific(k, 0)
 			return
 		}
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index 33cc670b641590e6ff7a26dde2505a1cb5f2583e..64ddc2354e6959f0ecb5b5adc502548026c1ee80 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -215,13 +215,7 @@ TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
 
 	MOVQ	SP, R12	// Save old SP; R12 unchanged by C code.
 
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), BX // BX unchanged by C code.
-#else
-	get_tls(CX)
-	MOVQ	g(CX), AX
-	MOVQ	g_m(AX), BX // BX unchanged by C code.
-#endif
 
 	// Set vdsoPC and vdsoSP for SIGPROF traceback.
 	// Save the old values on stack and restore them on exit,
@@ -236,11 +230,7 @@ TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
 	MOVQ	CX, m_vdsoPC(BX)
 	MOVQ	DX, m_vdsoSP(BX)
 
-#ifdef GOEXPERIMENT_regabig
 	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
-#else
-	CMPQ	AX, m_curg(BX)	// Only switch if on curg.
-#endif
 	JNE	noswitch
 
 	MOVQ	m_g0(BX), DX
@@ -328,9 +318,8 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
 	POPQ	BP
 	RET
 
-// Defined as ABIInternal since it does not use the stack-based Go ABI.
 // Called using C ABI.
-TEXT runtime·sigtramp(SB),NOSPLIT,$0
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	// Transition from C ABI to Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
@@ -348,8 +337,7 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$0
 
 // Used instead of sigtramp in programs that use cgo.
 // Arguments from kernel are in DI, SI, DX.
-// Defined as ABIInternal since it does not use the stack-based Go ABI.
-TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
+TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
 	// If no traceback function, do usual sigtramp.
 	MOVQ	runtime·cgoTraceback(SB), AX
 	TESTQ	AX, AX
@@ -392,12 +380,12 @@ TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
 	// The first three arguments, and the fifth, are already in registers.
 	// Set the two remaining arguments now.
 	MOVQ	runtime·cgoTraceback(SB), CX
-	MOVQ	$runtime·sigtramp(SB), R9
+	MOVQ	$runtime·sigtramp(SB), R9
 	MOVQ	_cgo_callers(SB), AX
 	JMP	AX
 
 sigtramp:
-	JMP	runtime·sigtramp(SB)
+	JMP	runtime·sigtramp(SB)
 
 sigtrampnog:
 	// Signal arrived on a non-Go thread. If this is SIGPROF, get a
@@ -428,8 +416,7 @@ sigtrampnog:
 // https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c
 // The code that cares about the precise instructions used is:
 // https://gcc.gnu.org/viewcvs/gcc/trunk/libgcc/config/i386/linux-unwind.h?revision=219188&view=markup
-// Defined as ABIInternal since it does not use the stack-based Go ABI.
-TEXT runtime·sigreturn(SB),NOSPLIT,$0
+TEXT runtime·sigreturn(SB),NOSPLIT,$0
 	MOVQ	$SYS_rt_sigreturn, AX
 	SYSCALL
 	INT $3	// not reached
diff --git a/src/runtime/sys_linux_riscv64.s b/src/runtime/sys_linux_riscv64.s
index 2389f1cc182489971fb050fcc9209fbbd470e474..54b7a3f61c56d8823878998e0a40c03bbf583ddf 100644
--- a/src/runtime/sys_linux_riscv64.s
+++ b/src/runtime/sys_linux_riscv64.s
@@ -25,7 +25,6 @@
 #define SYS_fcntl		25
 #define SYS_futex		98
 #define SYS_getpid		172
-#define SYS_getrlimit		163
 #define SYS_gettid		178
 #define SYS_gettimeofday	169
 #define SYS_kill		129
@@ -132,15 +131,6 @@ TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20
 	MOVW	A0, errno+16(FP)
 	RET
 
-// func getrlimit(kind int32, limit unsafe.Pointer) int32
-TEXT runtime·getrlimit(SB),NOSPLIT|NOFRAME,$0-20
-	MOVW	kind+0(FP), A0
-	MOV	limit+8(FP), A1
-	MOV	$SYS_getrlimit, A7
-	ECALL
-	MOVW	A0, ret+16(FP)
-	RET
-
 // func usleep(usec uint32)
 TEXT runtime·usleep(SB),NOSPLIT,$24-4
 	MOVWU	usec+0(FP), A0
diff --git a/src/runtime/sys_openbsd.go b/src/runtime/sys_openbsd.go
index ab3149558b3087156446c32d9f01a958019d2ad8..15888619b1790b6aaf8d40717416778850e9d5cc 100644
--- a/src/runtime/sys_openbsd.go
+++ b/src/runtime/sys_openbsd.go
@@ -7,7 +7,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // The *_trampoline functions convert from the Go calling convention to the C calling convention
 // and then call the underlying libc function. These are defined in sys_openbsd_$ARCH.s.
@@ -15,35 +18,35 @@ import "unsafe"
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_init(attr *pthreadattr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_init_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_init_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_init_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_destroy(attr *pthreadattr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_destroy_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_destroy_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_destroy_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_getstacksize(attr *pthreadattr, size *uintptr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_getstacksize_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_getstacksize_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_getstacksize_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_setdetachstate(attr *pthreadattr, state int) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_setdetachstate_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_setdetachstate_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_setdetachstate_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_create(attr *pthreadattr, start uintptr, arg unsafe.Pointer) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_create_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_create_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_create_trampoline()
 
diff --git a/src/runtime/sys_openbsd1.go b/src/runtime/sys_openbsd1.go
index cb5d35879cdef6a7049271e13575c630c9eaed0c..b4e9f54538e02ee14e16ea242307980c275c796c 100644
--- a/src/runtime/sys_openbsd1.go
+++ b/src/runtime/sys_openbsd1.go
@@ -7,31 +7,34 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 //go:nosplit
 //go:cgo_unsafe_args
 func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(thrsleep_trampoline)), unsafe.Pointer(&ident))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(thrsleep_trampoline)), unsafe.Pointer(&ident))
 }
 func thrsleep_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func thrwakeup(ident uintptr, n int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(thrwakeup_trampoline)), unsafe.Pointer(&ident))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(thrwakeup_trampoline)), unsafe.Pointer(&ident))
 }
 func thrwakeup_trampoline()
 
 //go:nosplit
 func osyield() {
-	libcCall(unsafe.Pointer(funcPC(sched_yield_trampoline)), unsafe.Pointer(nil))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sched_yield_trampoline)), unsafe.Pointer(nil))
 }
 func sched_yield_trampoline()
 
 //go:nosplit
 func osyield_no_g() {
-	asmcgocall_no_g(unsafe.Pointer(funcPC(sched_yield_trampoline)), unsafe.Pointer(nil))
+	asmcgocall_no_g(unsafe.Pointer(abi.FuncPCABI0(sched_yield_trampoline)), unsafe.Pointer(nil))
 }
 
 //go:cgo_import_dynamic libc_thrsleep __thrsleep "libc.so"
diff --git a/src/runtime/sys_openbsd2.go b/src/runtime/sys_openbsd2.go
index cd1a4e879fb2df8bc946548b4cb7e917cfed0652..23e0b195fd1c1150073ed7a8d438b9318e408b5f 100644
--- a/src/runtime/sys_openbsd2.go
+++ b/src/runtime/sys_openbsd2.go
@@ -7,21 +7,24 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // This is exported via linkname to assembly in runtime/cgo.
 //go:linkname exit
 //go:nosplit
 //go:cgo_unsafe_args
 func exit(code int32) {
-	libcCall(unsafe.Pointer(funcPC(exit_trampoline)), unsafe.Pointer(&code))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(exit_trampoline)), unsafe.Pointer(&code))
 }
 func exit_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func getthrid() (tid int32) {
-	libcCall(unsafe.Pointer(funcPC(getthrid_trampoline)), unsafe.Pointer(&tid))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(getthrid_trampoline)), unsafe.Pointer(&tid))
 	return
 }
 func getthrid_trampoline()
@@ -29,14 +32,14 @@ func getthrid_trampoline()
 //go:nosplit
 //go:cgo_unsafe_args
 func raiseproc(sig uint32) {
-	libcCall(unsafe.Pointer(funcPC(raiseproc_trampoline)), unsafe.Pointer(&sig))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(raiseproc_trampoline)), unsafe.Pointer(&sig))
 }
 func raiseproc_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func thrkill(tid int32, sig int) {
-	libcCall(unsafe.Pointer(funcPC(thrkill_trampoline)), unsafe.Pointer(&tid))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(thrkill_trampoline)), unsafe.Pointer(&tid))
 }
 func thrkill_trampoline()
 
@@ -53,7 +56,7 @@ func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) (un
 		ret1            unsafe.Pointer
 		ret2            int
 	}{addr, n, prot, flags, fd, off, nil, 0}
-	libcCall(unsafe.Pointer(funcPC(mmap_trampoline)), unsafe.Pointer(&args))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(mmap_trampoline)), unsafe.Pointer(&args))
 	return args.ret1, args.ret2
 }
 func mmap_trampoline()
@@ -61,42 +64,42 @@ func mmap_trampoline()
 //go:nosplit
 //go:cgo_unsafe_args
 func munmap(addr unsafe.Pointer, n uintptr) {
-	libcCall(unsafe.Pointer(funcPC(munmap_trampoline)), unsafe.Pointer(&addr))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(munmap_trampoline)), unsafe.Pointer(&addr))
 }
 func munmap_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func madvise(addr unsafe.Pointer, n uintptr, flags int32) {
-	libcCall(unsafe.Pointer(funcPC(madvise_trampoline)), unsafe.Pointer(&addr))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(madvise_trampoline)), unsafe.Pointer(&addr))
 }
 func madvise_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func open(name *byte, mode, perm int32) (ret int32) {
-	return libcCall(unsafe.Pointer(funcPC(open_trampoline)), unsafe.Pointer(&name))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(open_trampoline)), unsafe.Pointer(&name))
 }
 func open_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func closefd(fd int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(close_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(close_trampoline)), unsafe.Pointer(&fd))
 }
 func close_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func read(fd int32, p unsafe.Pointer, n int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(read_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(read_trampoline)), unsafe.Pointer(&fd))
 }
 func read_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func write1(fd uintptr, p unsafe.Pointer, n int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(write_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(write_trampoline)), unsafe.Pointer(&fd))
 }
 func write_trampoline()
 
@@ -110,7 +113,7 @@ func pipe2(flags int32) (r, w int32, errno int32) {
 		p     unsafe.Pointer
 		flags int32
 	}{noescape(unsafe.Pointer(&p)), flags}
-	errno = libcCall(unsafe.Pointer(funcPC(pipe2_trampoline)), unsafe.Pointer(&args))
+	errno = libcCall(unsafe.Pointer(abi.FuncPCABI0(pipe2_trampoline)), unsafe.Pointer(&args))
 	return p[0], p[1], errno
 }
 func pipe2_trampoline()
@@ -118,34 +121,34 @@ func pipe2_trampoline()
 //go:nosplit
 //go:cgo_unsafe_args
 func setitimer(mode int32, new, old *itimerval) {
-	libcCall(unsafe.Pointer(funcPC(setitimer_trampoline)), unsafe.Pointer(&mode))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(setitimer_trampoline)), unsafe.Pointer(&mode))
 }
 func setitimer_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func usleep(usec uint32) {
-	libcCall(unsafe.Pointer(funcPC(usleep_trampoline)), unsafe.Pointer(&usec))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(usleep_trampoline)), unsafe.Pointer(&usec))
 }
 func usleep_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func usleep_no_g(usec uint32) {
-	asmcgocall_no_g(unsafe.Pointer(funcPC(usleep_trampoline)), unsafe.Pointer(&usec))
+	asmcgocall_no_g(unsafe.Pointer(abi.FuncPCABI0(usleep_trampoline)), unsafe.Pointer(&usec))
 }
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, ndst uintptr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(sysctl_trampoline)), unsafe.Pointer(&mib))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(sysctl_trampoline)), unsafe.Pointer(&mib))
 }
 func sysctl_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func fcntl(fd, cmd, arg int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(fcntl_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(fcntl_trampoline)), unsafe.Pointer(&fd))
 }
 func fcntl_trampoline()
 
@@ -156,7 +159,7 @@ func nanotime1() int64 {
 		clock_id int32
 		tp       unsafe.Pointer
 	}{_CLOCK_MONOTONIC, unsafe.Pointer(&ts)}
-	libcCall(unsafe.Pointer(funcPC(clock_gettime_trampoline)), unsafe.Pointer(&args))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args))
 	return ts.tv_sec*1e9 + int64(ts.tv_nsec)
 }
 func clock_gettime_trampoline()
@@ -168,42 +171,44 @@ func walltime() (int64, int32) {
 		clock_id int32
 		tp       unsafe.Pointer
 	}{_CLOCK_REALTIME, unsafe.Pointer(&ts)}
-	libcCall(unsafe.Pointer(funcPC(clock_gettime_trampoline)), unsafe.Pointer(&args))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args))
 	return ts.tv_sec, int32(ts.tv_nsec)
 }
 
 //go:nosplit
 //go:cgo_unsafe_args
 func kqueue() int32 {
-	return libcCall(unsafe.Pointer(funcPC(kqueue_trampoline)), nil)
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(kqueue_trampoline)), nil)
 }
 func kqueue_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func kevent(kq int32, ch *keventt, nch int32, ev *keventt, nev int32, ts *timespec) int32 {
-	return libcCall(unsafe.Pointer(funcPC(kevent_trampoline)), unsafe.Pointer(&kq))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(kevent_trampoline)), unsafe.Pointer(&kq))
 }
 func kevent_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sigaction(sig uint32, new *sigactiont, old *sigactiont) {
-	libcCall(unsafe.Pointer(funcPC(sigaction_trampoline)), unsafe.Pointer(&sig))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sigaction_trampoline)), unsafe.Pointer(&sig))
 }
 func sigaction_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sigprocmask(how uint32, new *sigset, old *sigset) {
-	libcCall(unsafe.Pointer(funcPC(sigprocmask_trampoline)), unsafe.Pointer(&how))
+	// sigprocmask is called from sigsave, which is called from needm.
+	// As such, we have to be able to run with no g here.
+	asmcgocall_no_g(unsafe.Pointer(abi.FuncPCABI0(sigprocmask_trampoline)), unsafe.Pointer(&how))
 }
 func sigprocmask_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sigaltstack(new *stackt, old *stackt) {
-	libcCall(unsafe.Pointer(funcPC(sigaltstack_trampoline)), unsafe.Pointer(&new))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sigaltstack_trampoline)), unsafe.Pointer(&new))
 }
 func sigaltstack_trampoline()
 
diff --git a/src/runtime/sys_openbsd3.go b/src/runtime/sys_openbsd3.go
index 8d77a4b216e93136d8bcecc550aaf6fd1ef69f99..a917ebde6108a99be3df2374bcbf8a9248a0111c 100644
--- a/src/runtime/sys_openbsd3.go
+++ b/src/runtime/sys_openbsd3.go
@@ -7,7 +7,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // The X versions of syscall expect the libc call to return a 64-bit result.
 // Otherwise (the non-X version) expects a 32-bit result.
@@ -20,7 +23,7 @@ import "unsafe"
 //go:cgo_unsafe_args
 func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -31,7 +34,7 @@ func syscall()
 //go:cgo_unsafe_args
 func syscall_syscallX(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscallX)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscallX)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -42,7 +45,7 @@ func syscallX()
 //go:cgo_unsafe_args
 func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall6)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -53,7 +56,7 @@ func syscall6()
 //go:cgo_unsafe_args
 func syscall_syscall6X(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall6X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6X)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -64,7 +67,7 @@ func syscall6X()
 //go:cgo_unsafe_args
 func syscall_syscall10(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall10)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall10)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -75,7 +78,7 @@ func syscall10()
 //go:cgo_unsafe_args
 func syscall_syscall10X(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall10X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall10X)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -85,7 +88,7 @@ func syscall10X()
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall)), unsafe.Pointer(&fn))
 	return
 }
 
@@ -93,7 +96,7 @@ func syscall_rawSyscall(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall6)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6)), unsafe.Pointer(&fn))
 	return
 }
 
@@ -101,7 +104,7 @@ func syscall_rawSyscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintpt
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall6X(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall6X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6X)), unsafe.Pointer(&fn))
 	return
 }
 
@@ -109,6 +112,6 @@ func syscall_rawSyscall6X(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintp
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall10X(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall10X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall10X)), unsafe.Pointer(&fn))
 	return
 }
diff --git a/src/runtime/sys_openbsd_amd64.s b/src/runtime/sys_openbsd_amd64.s
index 522e98cf4f5ab024294dc01fc4825e7f2de25574..fc89ee6cbbda990a4e01272c217732ce738c3b52 100644
--- a/src/runtime/sys_openbsd_amd64.s
+++ b/src/runtime/sys_openbsd_amd64.s
@@ -58,7 +58,7 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
 	RET
 
 // Called using C ABI.
-TEXT runtime·sigtramp(SB),NOSPLIT,$0
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	// Transition from C ABI to Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
diff --git a/src/runtime/sys_plan9_386.s b/src/runtime/sys_plan9_386.s
index b3d2f1376d624c8b97e9e37ab95e53ee74fcf84e..bdcb98e19e0bbf083dd1a8511e3507f4fa0bad69 100644
--- a/src/runtime/sys_plan9_386.s
+++ b/src/runtime/sys_plan9_386.s
@@ -250,3 +250,7 @@ TEXT runtime·errstr(SB),NOSPLIT,$8-8
 	MOVL	0(SP), AX
 	MOVL	AX, ret_base+0(FP)
 	RET
+
+// never called on this platform
+TEXT ·sigpanictramp(SB),NOSPLIT,$0-0
+	UNDEF
diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
index 731306ab448463217fd5a8dd1a5ab273d081e386..39fc4c68e4ce969632c34ec14a650ec3b97ca9d7 100644
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -251,3 +251,7 @@ TEXT runtime·errstr(SB),NOSPLIT,$16-16
 	MOVQ	0(SP), AX
 	MOVQ	AX, ret_base+0(FP)
 	RET
+
+// never called on this platform
+TEXT ·sigpanictramp(SB),NOSPLIT,$0-0
+	UNDEF
diff --git a/src/runtime/sys_wasm.go b/src/runtime/sys_wasm.go
index 057ed4ccd90a7513ff8211f00a7685d450bfeef5..e6e7f471eea9f80c082977e1e5bb165728ac310b 100644
--- a/src/runtime/sys_wasm.go
+++ b/src/runtime/sys_wasm.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -30,7 +31,7 @@ func wasmExit(code int32)
 // and then stopped before the first instruction in fn.
 func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
 	sp := buf.sp
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = buf.pc
 	buf.sp = sp
 	buf.pc = uintptr(fn)
diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s
index 0b3933502ab3f4f42b8d6e8b2844724bf7a7ab96..cf3a439523c74196e54d44b498e2568d82f08f2e 100644
--- a/src/runtime/sys_windows_386.s
+++ b/src/runtime/sys_windows_386.s
@@ -8,7 +8,7 @@
 #include "time_windows.h"
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall(SB),NOSPLIT,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT,$0
 	MOVL	fn+0(FP), BX
 
 	// SetLastError(0).
@@ -147,21 +147,21 @@ done:
 	BYTE $0xC2; WORD $4
 	RET // unreached; make assembler happy
 
-TEXT runtime·exceptiontramp(SB),NOSPLIT,$0
+TEXT runtime·exceptiontramp(SB),NOSPLIT,$0
 	MOVL	$runtime·exceptionhandler(SB), AX
 	JMP	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp(SB),NOSPLIT,$0-0
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT,$0-0
 	// is never called
 	INT	$3
 
-TEXT runtime·lastcontinuetramp(SB),NOSPLIT,$0-0
+TEXT runtime·lastcontinuetramp(SB),NOSPLIT,$0-0
 	MOVL	$runtime·lastcontinuehandler(SB), AX
 	JMP	sigtramp<>(SB)
 
 GLOBL runtime·cbctxts(SB), NOPTR, $4
 
-TEXT runtime·callbackasm1(SB),NOSPLIT,$0
+TEXT runtime·callbackasm1(SB),NOSPLIT,$0
   	MOVL	0(SP), AX	// will use to find our callback context
 
 	// remove return address from stack, we are not returning to callbackasm, but to its caller.
@@ -180,7 +180,7 @@ TEXT runtime·callbackasm1(SB),NOSPLIT,$0
 	CLD
 
 	// determine index into runtime·cbs table
-	SUBL	$runtime·callbackasm(SB), AX
+	SUBL	$runtime·callbackasm(SB), AX
 	MOVL	$0, DX
 	MOVL	$5, BX	// divide by 5 because each call instruction in runtime·callbacks is 5 bytes long
 	DIVL	BX
@@ -250,7 +250,7 @@ TEXT tstart<>(SB),NOSPLIT,$0
 	RET
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
 	MOVL	newm+0(FP), BX
 
 	PUSHL	BX
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index e7782846b25c7c3b6f97391bd75c90eeb56adcc8..1e4c1d2b6117b28ad61934013ff7007e40c5eedd 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -8,12 +8,8 @@
 #include "time_windows.h"
 #include "cgo/abi_amd64.h"
 
-// maxargs should be divisible by 2, as Windows stack
-// must be kept 16-byte aligned on syscall entry.
-#define maxargs 18
-
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	// asmcgocall will put first argument into CX.
 	PUSHQ	CX			// save for later
 	MOVQ	libcall_fn(CX), AX
@@ -24,14 +20,14 @@ TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	MOVQ	0x30(GS), DI
 	MOVL	$0, 0x68(DI)
 
-	SUBQ	$(maxargs*8), SP	// room for args
+	SUBQ	$(const_maxArgs*8), SP	// room for args
 
 	// Fast version, do not store args on the stack.
 	CMPL	CX, $4
 	JLE	loadregs
 
 	// Check we have enough room for args.
-	CMPL	CX, $maxargs
+	CMPL	CX, $const_maxArgs
 	JLE	2(PC)
 	INT	$3			// not enough room -> crash
 
@@ -59,7 +55,7 @@ loadregs:
 	// Call stdcall function.
 	CALL	AX
 
-	ADDQ	$(maxargs*8), SP
+	ADDQ	$(const_maxArgs*8), SP
 
 	// Return result.
 	POPQ	CX
@@ -179,15 +175,15 @@ done:
 
 	RET
 
-TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
 	MOVQ	$runtime·exceptionhandler(SB), AX
 	JMP	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
 	MOVQ	$runtime·firstcontinuehandler(SB), AX
 	JMP	sigtramp<>(SB)
 
-TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
+TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
 	MOVQ	$runtime·lastcontinuehandler(SB), AX
 	JMP	sigtramp<>(SB)
 
@@ -212,7 +208,7 @@ TEXT runtime·callbackasm1(SB),NOSPLIT,$0
 	ADDQ	$8, SP
 
 	// determine index into runtime·cbs table
-	MOVQ	$runtime·callbackasm(SB), DX
+	MOVQ	$runtime·callbackasm(SB), DX
 	SUBQ	DX, AX
 	MOVQ	$0, DX
 	MOVQ	$5, CX	// divide by 5 because each call instruction in runtime·callbacks is 5 bytes long
@@ -245,7 +241,7 @@ TEXT runtime·callbackasm1(SB),NOSPLIT,$0
 	RET
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
 	// Switch from the host ABI to the Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
diff --git a/src/runtime/sys_windows_arm.s b/src/runtime/sys_windows_arm.s
index 48f8c7dedffd5ec8afa7fc22e7156aafc8de5de8..c9e96cb6522a1536f76977cc1a9b3facfa77543a 100644
--- a/src/runtime/sys_windows_arm.s
+++ b/src/runtime/sys_windows_arm.s
@@ -10,7 +10,7 @@
 // Note: For system ABI, R0-R3 are args, R4-R11 are callee-save.
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	MOVM.DB.W [R4, R5, R14], (R13)	// push {r4, r5, lr}
 	MOVW	R0, R4			// put libcall * in r4
 	MOVW	R13, R5			// save stack pointer in r5
@@ -222,21 +222,21 @@ TEXT sigresume<>(SB),NOSPLIT|NOFRAME,$0
 	MOVW	R0, R13
 	B	(R1)
 
-TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$runtime·exceptionhandler(SB), R1
 	B	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$runtime·firstcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
-TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$runtime·lastcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
 GLOBL runtime·cbctxts(SB), NOPTR, $4
 
-TEXT runtime·callbackasm1(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm1(SB),NOSPLIT|NOFRAME,$0
 	// On entry, the trampoline in zcallback_windows_arm.s left
 	// the callback index in R12 (which is volatile in the C ABI).
 
@@ -275,7 +275,7 @@ TEXT runtime·callbackasm1(SB),NOSPLIT|NOFRAME,$0
 	B	(R12)	// return
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT|NOFRAME,$0
 	MOVM.DB.W [R4-R11, R14], (R13)		// push {r4-r11, lr}
 
 	MOVW	m_g0(R0), g
diff --git a/src/runtime/sys_windows_arm64.s b/src/runtime/sys_windows_arm64.s
index 7a2e11f5ae29832d6536a1fd11a03a2bdff553b2..44145c53fb7ee8e0822fef94b64af6b7fcd55253 100644
--- a/src/runtime/sys_windows_arm64.s
+++ b/src/runtime/sys_windows_arm64.s
@@ -18,7 +18,7 @@
 // load_g and save_g (in tls_arm64.s) clobber R27 (REGTMP) and R0.
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	STP.W	(R29, R30), -32(RSP)	// allocate C ABI stack frame
 	STP	(R19, R20), 16(RSP) // save old R19, R20
 	MOVD	R0, R19	// save libcall pointer
@@ -290,21 +290,21 @@ TEXT sigresume<>(SB),NOSPLIT|NOFRAME,$0
 	MOVD	R0, RSP
 	B	(R1)
 
-TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
-	MOVD	$runtime·exceptionhandler(SB), R1
+TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
+	MOVD	$runtime·exceptionhandler(SB), R1
 	B	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
-	MOVD	$runtime·firstcontinuehandler(SB), R1
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
+	MOVD	$runtime·firstcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
 TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
-	MOVD	$runtime·lastcontinuehandler(SB), R1
+	MOVD	$runtime·lastcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
 GLOBL runtime·cbctxts(SB), NOPTR, $4
 
-TEXT runtime·callbackasm1(SB),NOSPLIT,$208-0
+TEXT runtime·callbackasm1(SB),NOSPLIT,$208-0
 	NO_LOCAL_POINTERS
 
 	// On entry, the trampoline in zcallback_windows_arm64.s left
@@ -339,7 +339,7 @@ TEXT runtime·callbackasm1(SB),NOSPLIT,$208-0
 	MOVD	R0, callbackArgs_result(R13)	// result
 
 	// Call cgocallback, which will call callbackWrap(frame).
-	MOVD	$·callbackWrap(SB), R0	// PC of function to call
+	MOVD	$·callbackWrap(SB), R0	// PC of function to call, cgocallback takes an ABIInternal entry-point
 	MOVD	R13, R1	// frame (&callbackArgs{...})
 	MOVD	$0, R2	// context
 	MOVD	R0, (1*8)(RSP)
@@ -356,7 +356,7 @@ TEXT runtime·callbackasm1(SB),NOSPLIT,$208-0
 	RET
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall(SB),NOSPLIT,$96-0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT,$96-0
 	SAVE_R19_TO_R28(-10*8)
 
 	MOVD	m_g0(R0), g
diff --git a/src/runtime/sys_x86.go b/src/runtime/sys_x86.go
index 0866e3140e09d092245c323cc1c554fd4a44d726..856c73a2f6c84625a3b62dfbbfe35009cb380ccf 100644
--- a/src/runtime/sys_x86.go
+++ b/src/runtime/sys_x86.go
@@ -8,7 +8,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -16,7 +16,7 @@ import (
 // and then stopped before the first instruction in fn.
 func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
 	sp := buf.sp
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = buf.pc
 	buf.sp = sp
 	buf.pc = uintptr(fn)
diff --git a/src/runtime/syscall_solaris.go b/src/runtime/syscall_solaris.go
index 094516927f3f495ad9b4817772fa510db3e35bf9..15be8e1c61a3411008e256d99d9510069fa266a3 100644
--- a/src/runtime/syscall_solaris.go
+++ b/src/runtime/syscall_solaris.go
@@ -35,6 +35,7 @@ func pipe1() // declared for vet; do NOT call
 
 //go:nosplit
 //go:linkname syscall_sysvicall6
+//go:cgo_unsafe_args
 func syscall_sysvicall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	call := libcall{
 		fn:   fn,
@@ -49,6 +50,7 @@ func syscall_sysvicall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err
 
 //go:nosplit
 //go:linkname syscall_rawsysvicall6
+//go:cgo_unsafe_args
 func syscall_rawsysvicall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	call := libcall{
 		fn:   fn,
@@ -104,6 +106,7 @@ func syscall_dup2(oldfd, newfd uintptr) (val, err uintptr) {
 
 //go:nosplit
 //go:linkname syscall_execve
+//go:cgo_unsafe_args
 func syscall_execve(path, argv, envp uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_execve)),
@@ -123,6 +126,7 @@ func syscall_exit(code uintptr) {
 
 //go:nosplit
 //go:linkname syscall_fcntl
+//go:cgo_unsafe_args
 func syscall_fcntl(fd, cmd, arg uintptr) (val, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_fcntl)),
@@ -181,6 +185,7 @@ func syscall_getpid() (pid, err uintptr) {
 
 //go:nosplit
 //go:linkname syscall_ioctl
+//go:cgo_unsafe_args
 func syscall_ioctl(fd, req, arg uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_ioctl)),
@@ -234,6 +239,7 @@ func syscall_setgid(gid uintptr) (err uintptr) {
 
 //go:nosplit
 //go:linkname syscall_setgroups
+//go:cgo_unsafe_args
 func syscall_setgroups(ngid, gid uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_setgroups)),
@@ -270,6 +276,7 @@ func syscall_setuid(uid uintptr) (err uintptr) {
 
 //go:nosplit
 //go:linkname syscall_setpgid
+//go:cgo_unsafe_args
 func syscall_setpgid(pid, pgid uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_setpgid)),
@@ -281,6 +288,7 @@ func syscall_setpgid(pid, pgid uintptr) (err uintptr) {
 }
 
 //go:linkname syscall_syscall
+//go:cgo_unsafe_args
 func syscall_syscall(trap, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_syscall)),
@@ -294,6 +302,7 @@ func syscall_syscall(trap, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 }
 
 //go:linkname syscall_wait4
+//go:cgo_unsafe_args
 func syscall_wait4(pid uintptr, wstatus *uint32, options uintptr, rusage unsafe.Pointer) (wpid int, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_wait4)),
@@ -308,6 +317,7 @@ func syscall_wait4(pid uintptr, wstatus *uint32, options uintptr, rusage unsafe.
 
 //go:nosplit
 //go:linkname syscall_write
+//go:cgo_unsafe_args
 func syscall_write(fd, buf, nbyte uintptr) (n, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_write)),
diff --git a/src/runtime/syscall_windows.go b/src/runtime/syscall_windows.go
index 4763a440e7ef1c47ba322727dfd7bee3bcbb482f..da181f2a8d416ad9aeacc0de4974da17f23881ff 100644
--- a/src/runtime/syscall_windows.go
+++ b/src/runtime/syscall_windows.go
@@ -6,7 +6,7 @@ package runtime
 
 import (
 	"internal/abi"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -73,7 +73,7 @@ type abiDesc struct {
 }
 
 func (p *abiDesc) assignArg(t *_type) {
-	if t.size > sys.PtrSize {
+	if t.size > goarch.PtrSize {
 		// We don't support this right now. In
 		// stdcall/cdecl, 64-bit ints and doubles are
 		// passed as two words (little endian); and
@@ -146,7 +146,7 @@ func (p *abiDesc) assignArg(t *_type) {
 
 	// cdecl, stdcall, fastcall, and arm pad arguments to word size.
 	// TODO(rsc): On arm and arm64 do we need to skip the caller's saved LR?
-	p.srcStackSize += sys.PtrSize
+	p.srcStackSize += goarch.PtrSize
 }
 
 // tryRegAssignArg tries to register-assign a value of type t.
@@ -162,7 +162,7 @@ func (p *abiDesc) tryRegAssignArg(t *_type, offset uintptr) bool {
 		return p.assignReg(t.size, offset)
 	case kindInt64, kindUint64:
 		// Only register-assign if the registers are big enough.
-		if sys.PtrSize == 8 {
+		if goarch.PtrSize == 8 {
 			return p.assignReg(t.size, offset)
 		}
 	case kindArray:
@@ -232,10 +232,10 @@ func callbackasmAddr(i int) uintptr {
 		// followed by a branch instruction
 		entrySize = 8
 	}
-	return funcPC(callbackasm) + uintptr(i*entrySize)
+	return abi.FuncPCABI0(callbackasm) + uintptr(i*entrySize)
 }
 
-const callbackMaxFrame = 64 * sys.PtrSize
+const callbackMaxFrame = 64 * goarch.PtrSize
 
 // compileCallback converts a Go function fn into a C function pointer
 // that can be passed to Windows APIs.
@@ -263,13 +263,13 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
 	}
 	// The Go ABI aligns the result to the word size. src is
 	// already aligned.
-	abiMap.dstStackSize = alignUp(abiMap.dstStackSize, sys.PtrSize)
+	abiMap.dstStackSize = alignUp(abiMap.dstStackSize, goarch.PtrSize)
 	abiMap.retOffset = abiMap.dstStackSize
 
 	if len(ft.out()) != 1 {
 		panic("compileCallback: expected function with one uintptr-sized result")
 	}
-	if ft.out()[0].size != sys.PtrSize {
+	if ft.out()[0].size != goarch.PtrSize {
 		panic("compileCallback: expected function with one uintptr-sized result")
 	}
 	if k := ft.out()[0].kind & kindMask; k == kindFloat32 || k == kindFloat64 {
@@ -282,12 +282,12 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
 		// Make room for the uintptr-sized result.
 		// If there are argument registers, the return value will
 		// be passed in the first register.
-		abiMap.dstStackSize += sys.PtrSize
+		abiMap.dstStackSize += goarch.PtrSize
 	}
 
 	// TODO(mknyszek): Remove dstSpill from this calculation when we no longer have
 	// caller reserved spill space.
-	frameSize := alignUp(abiMap.dstStackSize, sys.PtrSize)
+	frameSize := alignUp(abiMap.dstStackSize, goarch.PtrSize)
 	frameSize += abiMap.dstSpill
 	if frameSize > callbackMaxFrame {
 		panic("compileCallback: function argument frame too large")
@@ -370,7 +370,7 @@ func callbackWrap(a *callbackArgs) {
 
 	// TODO(mknyszek): Remove this when we no longer have
 	// caller reserved spill space.
-	frameSize := alignUp(c.abiMap.dstStackSize, sys.PtrSize)
+	frameSize := alignUp(c.abiMap.dstStackSize, goarch.PtrSize)
 	frameSize += c.abiMap.dstSpill
 
 	// Even though this is copying back results, we can pass a nil
@@ -468,84 +468,69 @@ func syscall_getprocaddress(handle uintptr, procname *byte) (outhandle, err uint
 
 //go:linkname syscall_Syscall syscall.Syscall
 //go:nosplit
-//go:cgo_unsafe_args
 func syscall_Syscall(fn, nargs, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
-	lockOSThread()
-	defer unlockOSThread()
-	c := &getg().m.syscall
-	c.fn = fn
-	c.n = nargs
-	c.args = uintptr(noescape(unsafe.Pointer(&a1)))
-	cgocall(asmstdcallAddr, unsafe.Pointer(c))
-	return c.r1, c.r2, c.err
+	return syscall_SyscallN(fn, a1, a2, a3)
 }
 
 //go:linkname syscall_Syscall6 syscall.Syscall6
 //go:nosplit
-//go:cgo_unsafe_args
 func syscall_Syscall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
-	lockOSThread()
-	defer unlockOSThread()
-	c := &getg().m.syscall
-	c.fn = fn
-	c.n = nargs
-	c.args = uintptr(noescape(unsafe.Pointer(&a1)))
-	cgocall(asmstdcallAddr, unsafe.Pointer(c))
-	return c.r1, c.r2, c.err
+	return syscall_SyscallN(fn, a1, a2, a3, a4, a5, a6)
 }
 
 //go:linkname syscall_Syscall9 syscall.Syscall9
 //go:nosplit
-//go:cgo_unsafe_args
 func syscall_Syscall9(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2, err uintptr) {
-	lockOSThread()
-	c := &getg().m.syscall
-	c.fn = fn
-	c.n = nargs
-	c.args = uintptr(noescape(unsafe.Pointer(&a1)))
-	cgocall(asmstdcallAddr, unsafe.Pointer(c))
-	unlockOSThread()
-	return c.r1, c.r2, c.err
+	return syscall_SyscallN(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9)
 }
 
 //go:linkname syscall_Syscall12 syscall.Syscall12
 //go:nosplit
-//go:cgo_unsafe_args
 func syscall_Syscall12(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12 uintptr) (r1, r2, err uintptr) {
-	lockOSThread()
-	c := &getg().m.syscall
-	c.fn = fn
-	c.n = nargs
-	c.args = uintptr(noescape(unsafe.Pointer(&a1)))
-	cgocall(asmstdcallAddr, unsafe.Pointer(c))
-	unlockOSThread()
-	return c.r1, c.r2, c.err
+	return syscall_SyscallN(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12)
 }
 
 //go:linkname syscall_Syscall15 syscall.Syscall15
 //go:nosplit
-//go:cgo_unsafe_args
 func syscall_Syscall15(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr) (r1, r2, err uintptr) {
-	lockOSThread()
-	c := &getg().m.syscall
-	c.fn = fn
-	c.n = nargs
-	c.args = uintptr(noescape(unsafe.Pointer(&a1)))
-	cgocall(asmstdcallAddr, unsafe.Pointer(c))
-	unlockOSThread()
-	return c.r1, c.r2, c.err
+	return syscall_SyscallN(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15)
 }
 
 //go:linkname syscall_Syscall18 syscall.Syscall18
 //go:nosplit
-//go:cgo_unsafe_args
 func syscall_Syscall18(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, a17, a18 uintptr) (r1, r2, err uintptr) {
+	return syscall_SyscallN(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, a17, a18)
+}
+
+// maxArgs should be divisible by 2, as Windows stack
+// must be kept 16-byte aligned on syscall entry.
+//
+// Although it only permits maximum 42 parameters, it
+// is arguably large enough.
+const maxArgs = 42
+
+//go:linkname syscall_SyscallN syscall.SyscallN
+//go:nosplit
+func syscall_SyscallN(trap uintptr, args ...uintptr) (r1, r2, err uintptr) {
+	nargs := len(args)
+
+	// asmstdcall expects it can access the first 4 arguments
+	// to load them into registers.
+	var tmp [4]uintptr
+	switch {
+	case nargs < 4:
+		copy(tmp[:], args)
+		args = tmp[:]
+	case nargs > maxArgs:
+		panic("runtime: SyscallN has too many arguments")
+	}
+
 	lockOSThread()
+	defer unlockOSThread()
 	c := &getg().m.syscall
-	c.fn = fn
-	c.n = nargs
-	c.args = uintptr(noescape(unsafe.Pointer(&a1)))
+	c.fn = trap
+	c.n = uintptr(nargs)
+	c.args = uintptr(noescape(unsafe.Pointer(&args[0])))
 	cgocall(asmstdcallAddr, unsafe.Pointer(c))
-	unlockOSThread()
 	return c.r1, c.r2, c.err
 }
diff --git a/src/runtime/syscall_windows_test.go b/src/runtime/syscall_windows_test.go
index e3f772ac4bb9457a5ed94ff944cfc466b67afca2..235c79f68ffe9c0affe3085154d2ab5472298021 100644
--- a/src/runtime/syscall_windows_test.go
+++ b/src/runtime/syscall_windows_test.go
@@ -759,7 +759,7 @@ uintptr_t cfunc(callback f, uintptr_t n) {
 	}
 }
 
-func TestSyscall18(t *testing.T) {
+func TestSyscallN(t *testing.T) {
 	if _, err := exec.LookPath("gcc"); err != nil {
 		t.Skip("skipping test: gcc is missing")
 	}
@@ -767,40 +767,52 @@ func TestSyscall18(t *testing.T) {
 		t.Skipf("skipping test: GOARCH=%s", runtime.GOARCH)
 	}
 
-	const src = `
-#include 
-#include 
+	for arglen := 0; arglen <= runtime.MaxArgs; arglen++ {
+		arglen := arglen
+		t.Run(fmt.Sprintf("arg-%d", arglen), func(t *testing.T) {
+			t.Parallel()
+			args := make([]string, arglen)
+			rets := make([]string, arglen+1)
+			params := make([]uintptr, arglen)
+			for i := range args {
+				args[i] = fmt.Sprintf("int a%d", i)
+				rets[i] = fmt.Sprintf("(a%d == %d)", i, i)
+				params[i] = uintptr(i)
+			}
+			rets[arglen] = "1" // for arglen == 0
 
-int cfunc(	int a1, int a2, int a3, int a4, int a5, int a6, int a7, int a8, int a9,
-			int a10, int a11, int a12, int a13, int a14, int a15, int a16, int a17, int a18) {
-	return 1;
-}
-`
-	tmpdir := t.TempDir()
+			src := fmt.Sprintf(`
+		#include 
+		#include 
+		int cfunc(%s) { return %s; }`, strings.Join(args, ", "), strings.Join(rets, " && "))
 
-	srcname := "mydll.c"
-	err := os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
-	if err != nil {
-		t.Fatal(err)
-	}
-	outname := "mydll.dll"
-	cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
-	cmd.Dir = tmpdir
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		t.Fatalf("failed to build dll: %v - %v", err, string(out))
-	}
-	dllpath := filepath.Join(tmpdir, outname)
+			tmpdir := t.TempDir()
 
-	dll := syscall.MustLoadDLL(dllpath)
-	defer dll.Release()
+			srcname := "mydll.c"
+			err := os.WriteFile(filepath.Join(tmpdir, srcname), []byte(src), 0)
+			if err != nil {
+				t.Fatal(err)
+			}
+			outname := "mydll.dll"
+			cmd := exec.Command("gcc", "-shared", "-s", "-Werror", "-o", outname, srcname)
+			cmd.Dir = tmpdir
+			out, err := cmd.CombinedOutput()
+			if err != nil {
+				t.Fatalf("failed to build dll: %v\n%s", err, out)
+			}
+			dllpath := filepath.Join(tmpdir, outname)
 
-	proc := dll.MustFindProc("cfunc")
+			dll := syscall.MustLoadDLL(dllpath)
+			defer dll.Release()
 
-	// proc.Call() will call Syscall18() internally.
-	r, _, err := proc.Call(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-	if r != 1 {
-		t.Errorf("got %d want 1 (err=%v)", r, err)
+			proc := dll.MustFindProc("cfunc")
+
+			// proc.Call() will call SyscallN() internally.
+			r, _, err := proc.Call(params...)
+			if r != 1 {
+				t.Errorf("got %d want 1 (err=%v)", r, err)
+			}
+		})
 	}
 }
 
diff --git a/src/runtime/testdata/testprogcgo/tracebackctxt.go b/src/runtime/testdata/testprogcgo/tracebackctxt.go
index 51fa4ad25c320f357a7b466009787e584664089c..62ff8eccd671a27cd13c0027839a9f77a1985df1 100644
--- a/src/runtime/testdata/testprogcgo/tracebackctxt.go
+++ b/src/runtime/testdata/testprogcgo/tracebackctxt.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// The __attribute__((weak)) used below doesn't seem to work on Windows.
-
 package main
 
 // Test the context argument to SetCgoTraceback.
@@ -14,20 +12,24 @@ package main
 extern void C1(void);
 extern void C2(void);
 extern void tcContext(void*);
+extern void tcContextSimple(void*);
 extern void tcTraceback(void*);
 extern void tcSymbolizer(void*);
 extern int getContextCount(void);
+extern void TracebackContextPreemptionCallGo(int);
 */
 import "C"
 
 import (
 	"fmt"
 	"runtime"
+	"sync"
 	"unsafe"
 )
 
 func init() {
 	register("TracebackContext", TracebackContext)
+	register("TracebackContextPreemption", TracebackContextPreemption)
 }
 
 var tracebackOK bool
@@ -105,3 +107,30 @@ wantLoop:
 		tracebackOK = false
 	}
 }
+
+// Issue 47441.
+func TracebackContextPreemption() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.tcTraceback), unsafe.Pointer(C.tcContextSimple), unsafe.Pointer(C.tcSymbolizer))
+
+	const funcs = 10
+	const calls = 1e5
+	var wg sync.WaitGroup
+	for i := 0; i < funcs; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := 0; j < calls; j++ {
+				C.TracebackContextPreemptionCallGo(C.int(i*calls + j))
+			}
+		}(i)
+	}
+	wg.Wait()
+
+	fmt.Println("OK")
+}
+
+//export TracebackContextPreemptionGoFunction
+func TracebackContextPreemptionGoFunction(i C.int) {
+	// Do some busy work.
+	fmt.Sprintf("%d\n", i)
+}
diff --git a/src/runtime/testdata/testprogcgo/tracebackctxt_c.c b/src/runtime/testdata/testprogcgo/tracebackctxt_c.c
index 900cada0d3d7fc1f1c541f43f90f970b4cb5d0b4..910cb7b8997a67acbffc3bcec59baee9b6d37033 100644
--- a/src/runtime/testdata/testprogcgo/tracebackctxt_c.c
+++ b/src/runtime/testdata/testprogcgo/tracebackctxt_c.c
@@ -11,6 +11,7 @@
 // Functions exported from Go.
 extern void G1(void);
 extern void G2(void);
+extern void TracebackContextPreemptionGoFunction(int);
 
 void C1() {
 	G1();
@@ -62,10 +63,17 @@ void tcContext(void* parg) {
 	}
 }
 
+void tcContextSimple(void* parg) {
+	struct cgoContextArg* arg = (struct cgoContextArg*)(parg);
+	if (arg->context == 0) {
+		arg->context = 1;
+	}
+}
+
 void tcTraceback(void* parg) {
 	int base, i;
 	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
-	if (arg->context == 0) {
+	if (arg->context == 0 && arg->sigContext == 0) {
 		// This shouldn't happen in this program.
 		abort();
 	}
@@ -89,3 +97,7 @@ void tcSymbolizer(void *parg) {
 	arg->func = "cFunction";
 	arg->lineno = arg->pc + (arg->more << 16);
 }
+
+void TracebackContextPreemptionCallGo(int i) {
+	TracebackContextPreemptionGoFunction(i);
+}
diff --git a/src/runtime/textflag.h b/src/runtime/textflag.h
index e727208cd03a0b5f693edaedb4861da5b85add2c..214075e360ceb623daa53cdd8313cdd5473435af 100644
--- a/src/runtime/textflag.h
+++ b/src/runtime/textflag.h
@@ -32,8 +32,8 @@
 #define NOFRAME 512
 // Function can call reflect.Type.Method or reflect.Type.MethodByName.
 #define REFLECTMETHOD 1024
-// Function is the top of the call stack. Call stack unwinders should stop
-// at this function.
+// Function is the outermost frame of the call stack. Call stack unwinders
+// should stop at this function.
 #define TOPFRAME 2048
 // Function is an ABI wrapper.
 #define ABIWRAPPER 4096
diff --git a/src/runtime/time.go b/src/runtime/time.go
index 666b2423164162fd96d1beed5ba6544fe0f6fe71..ad267c336564f68c78e65d4236421710eb568f8a 100644
--- a/src/runtime/time.go
+++ b/src/runtime/time.go
@@ -7,6 +7,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -819,7 +820,7 @@ func runOneTimer(pp *p, t *timer, now int64) {
 	if raceenabled {
 		ppcur := getg().m.p.ptr()
 		if ppcur.timerRaceCtx == 0 {
-			ppcur.timerRaceCtx = racegostart(funcPC(runtimer) + sys.PCQuantum)
+			ppcur.timerRaceCtx = racegostart(abi.FuncPCABIInternal(runtimer) + sys.PCQuantum)
 		}
 		raceacquirectx(ppcur.timerRaceCtx, unsafe.Pointer(t))
 	}
diff --git a/src/runtime/time_linux_amd64.s b/src/runtime/time_linux_amd64.s
index 0dd791989685cd1235d7445b3c20895cdbe9d1c8..c88e92bd0cab904074c0890a4f9f662509310cb0 100644
--- a/src/runtime/time_linux_amd64.s
+++ b/src/runtime/time_linux_amd64.s
@@ -15,13 +15,7 @@
 TEXT time·now(SB),NOSPLIT,$16-24
 	MOVQ	SP, R12 // Save old SP; R12 unchanged by C code.
 
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), BX // BX unchanged by C code.
-#else
-	get_tls(CX)
-	MOVQ	g(CX), AX
-	MOVQ	g_m(AX), BX // BX unchanged by C code.
-#endif
 
 	// Store CLOCK_REALTIME results directly to return space.
 	LEAQ	sec+0(FP), SI
@@ -38,11 +32,7 @@ TEXT time·now(SB),NOSPLIT,$16-24
 	MOVQ	CX, m_vdsoPC(BX)
 	MOVQ	SI, m_vdsoSP(BX)
 
-#ifdef GOEXPERIMENT_regabig
 	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
-#else
-	CMPQ	AX, m_curg(BX)	// Only switch if on curg.
-#endif
 	JNE	noswitch
 
 	MOVQ	m_g0(BX), DX
diff --git a/src/runtime/trace.go b/src/runtime/trace.go
index 1530178c853d01765def102386e1827abd97a65b..00544e4283c620310c1ee3b53664750d34787713 100644
--- a/src/runtime/trace.go
+++ b/src/runtime/trace.go
@@ -13,6 +13,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -85,7 +86,7 @@ const (
 	// and ppc64le.
 	// Tracing won't work reliably for architectures where cputicks is emulated
 	// by nanotime, so the value doesn't matter for those architectures.
-	traceTickDiv = 16 + 48*(sys.Goarch386|sys.GoarchAmd64)
+	traceTickDiv = 16 + 48*(goarch.Is386|goarch.IsAmd64)
 	// Maximum number of PCs in a single stack trace.
 	// Since events contain only stack id rather than whole stack trace,
 	// we can allow quite large values here.
@@ -829,7 +830,7 @@ Search:
 
 // newStack allocates a new stack of size n.
 func (tab *traceStackTable) newStack(n int) *traceStack {
-	return (*traceStack)(tab.mem.alloc(unsafe.Sizeof(traceStack{}) + uintptr(n)*sys.PtrSize))
+	return (*traceStack)(tab.mem.alloc(unsafe.Sizeof(traceStack{}) + uintptr(n)*goarch.PtrSize))
 }
 
 // allFrames returns all of the Frames corresponding to pcs.
@@ -929,7 +930,7 @@ type traceAlloc struct {
 //go:notinheap
 type traceAllocBlock struct {
 	next traceAllocBlockPtr
-	data [64<<10 - sys.PtrSize]byte
+	data [64<<10 - goarch.PtrSize]byte
 }
 
 // TODO: Since traceAllocBlock is now go:notinheap, this isn't necessary.
@@ -940,7 +941,7 @@ func (p *traceAllocBlockPtr) set(x *traceAllocBlock) { *p = traceAllocBlockPtr(u
 
 // alloc allocates n-byte block.
 func (a *traceAlloc) alloc(n uintptr) unsafe.Pointer {
-	n = alignUp(n, sys.PtrSize)
+	n = alignUp(n, goarch.PtrSize)
 	if a.head == 0 || a.off+n > uintptr(len(a.head.ptr().data)) {
 		if n > uintptr(len(a.head.ptr().data)) {
 			throw("trace: alloc too large")
diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 814c3236345404e63f7d37c11e0076b67d824d52..8c0979eec23b5bf5cdce42d9376f324cbf37e36b 100644
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -6,6 +6,7 @@ package runtime
 
 import (
 	"internal/bytealg"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -21,41 +22,6 @@ import (
 
 const usesLR = sys.MinFrameSize > 0
 
-// Traceback over the deferred function calls.
-// Report them like calls that have been invoked but not started executing yet.
-func tracebackdefers(gp *g, callback func(*stkframe, unsafe.Pointer) bool, v unsafe.Pointer) {
-	var frame stkframe
-	for d := gp._defer; d != nil; d = d.link {
-		fn := d.fn
-		if fn == nil {
-			// Defer of nil function. Args don't matter.
-			frame.pc = 0
-			frame.fn = funcInfo{}
-			frame.argp = 0
-			frame.arglen = 0
-			frame.argmap = nil
-		} else {
-			frame.pc = fn.fn
-			f := findfunc(frame.pc)
-			if !f.valid() {
-				print("runtime: unknown pc in defer ", hex(frame.pc), "\n")
-				throw("unknown pc")
-			}
-			frame.fn = f
-			frame.argp = uintptr(deferArgs(d))
-			var ok bool
-			frame.arglen, frame.argmap, ok = getArgInfoFast(f, true)
-			if !ok {
-				frame.arglen, frame.argmap = getArgInfo(&frame, f, true, fn)
-			}
-		}
-		frame.continpc = frame.pc
-		if !callback((*stkframe)(noescape(unsafe.Pointer(&frame))), v) {
-			return
-		}
-	}
-}
-
 // Generic traceback. Handles runtime stack prints (pcbuf == nil),
 // the runtime.Callers function (pcbuf != nil), as well as the garbage
 // collector (callback != nil).  A little clunky to merge these, but avoids
@@ -126,7 +92,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
 			frame.lr = 0
 		} else {
 			frame.pc = uintptr(*(*uintptr)(unsafe.Pointer(frame.sp)))
-			frame.sp += sys.PtrSize
+			frame.sp += goarch.PtrSize
 		}
 	}
 
@@ -207,7 +173,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
 			frame.fp = frame.sp + uintptr(funcspdelta(f, frame.pc, &cache))
 			if !usesLR {
 				// On x86, call instruction pushes return PC before entering new function.
-				frame.fp += sys.PtrSize
+				frame.fp += goarch.PtrSize
 			}
 		}
 		var flr funcInfo
@@ -248,7 +214,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
 				}
 			} else {
 				if frame.lr == 0 {
-					lrPtr = frame.fp - sys.PtrSize
+					lrPtr = frame.fp - goarch.PtrSize
 					frame.lr = uintptr(*(*uintptr)(unsafe.Pointer(lrPtr)))
 				}
 			}
@@ -279,7 +245,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
 		frame.varp = frame.fp
 		if !usesLR {
 			// On x86, call instruction pushes return PC before entering new function.
-			frame.varp -= sys.PtrSize
+			frame.varp -= goarch.PtrSize
 		}
 
 		// For architectures with frame pointers, if there's
@@ -300,7 +266,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
 		// And it happens to end up mimicking the x86 layout.
 		// Other architectures may make different decisions.
 		if frame.varp > frame.sp && framepointer_enabled {
-			frame.varp -= sys.PtrSize
+			frame.varp -= goarch.PtrSize
 		}
 
 		// Derive size of arguments.
@@ -600,10 +566,10 @@ func printArgs(f funcInfo, argp unsafe.Pointer) {
 
 	print1 := func(off, sz uint8) {
 		x := readUnaligned64(add(argp, uintptr(off)))
-		// mask out irrelavant bits
+		// mask out irrelevant bits
 		if sz < 8 {
 			shift := 64 - sz*8
-			if sys.BigEndian {
+			if goarch.BigEndian {
 				x = x >> shift
 			} else {
 				x = x << shift >> shift
@@ -700,16 +666,16 @@ func getArgInfo(frame *stkframe, f funcInfo, needArgMap bool, ctxt *funcval) (ar
 				// Figure out whether the return values are valid.
 				// Reflect will update this value after it copies
 				// in the return values.
-				retValid = *(*bool)(unsafe.Pointer(arg0 + 4*sys.PtrSize))
+				retValid = *(*bool)(unsafe.Pointer(arg0 + 4*goarch.PtrSize))
 			}
 			if mv.fn != f.entry {
 				print("runtime: confused by ", funcname(f), "\n")
 				throw("reflect mismatch")
 			}
 			bv := mv.stack
-			arglen = uintptr(bv.n * sys.PtrSize)
+			arglen = uintptr(bv.n * goarch.PtrSize)
 			if !retValid {
-				arglen = uintptr(mv.argLen) &^ (sys.PtrSize - 1)
+				arglen = uintptr(mv.argLen) &^ (goarch.PtrSize - 1)
 			}
 			argmap = bv
 		}
@@ -1045,8 +1011,8 @@ func tracebackothers(me *g) {
 // for debugging purposes. If the address bad is included in the
 // hexdumped range, it will mark it as well.
 func tracebackHexdump(stk stack, frame *stkframe, bad uintptr) {
-	const expand = 32 * sys.PtrSize
-	const maxExpand = 256 * sys.PtrSize
+	const expand = 32 * goarch.PtrSize
+	const maxExpand = 256 * goarch.PtrSize
 	// Start around frame.sp.
 	lo, hi := frame.sp, frame.sp
 	// Expand to include frame.fp.
diff --git a/src/runtime/type.go b/src/runtime/type.go
index 4039273695b106746a0582386c8834c72d6b4f15..ad01d5095e5088ad8d99d007452316b810cb2c98 100644
--- a/src/runtime/type.go
+++ b/src/runtime/type.go
@@ -6,7 +6,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // tflag is documented in reflect/type.go.
 //
@@ -262,7 +265,7 @@ func (t *_type) textOff(off textOff) unsafe.Pointer {
 	if off == -1 {
 		// -1 is the sentinel value for unreachable code.
 		// See cmd/link/internal/ld/data.go:relocsym.
-		return unsafe.Pointer(funcPC(unreachableMethod))
+		return unsafe.Pointer(abi.FuncPCABIInternal(unreachableMethod))
 	}
 	base := uintptr(unsafe.Pointer(t))
 	var md *moduledata
diff --git a/src/runtime/wincallback.go b/src/runtime/wincallback.go
index a7a787d8f6d694579f7e7827f7838f74b67ce6df..73f1e567cecf948558a87ab15bff97a83ee36955 100644
--- a/src/runtime/wincallback.go
+++ b/src/runtime/wincallback.go
@@ -33,7 +33,7 @@ func genasm386Amd64() {
 // CALL instruction in runtime·callbackasm. This determines
 // which Go callback function is executed later on.
 
-TEXT runtime·callbackasm(SB),7,$0
+TEXT runtime·callbackasm(SB),7,$0
 `)
 	for i := 0; i < maxCallback; i++ {
 		buf.WriteString("\tCALL\truntime·callbackasm1(SB)\n")
@@ -61,7 +61,7 @@ func genasmArm() {
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 `)
 	for i := 0; i < maxCallback; i++ {
 		buf.WriteString(fmt.Sprintf("\tMOVW\t$%d, R12\n", i))
@@ -89,7 +89,7 @@ func genasmArm64() {
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 `)
 	for i := 0; i < maxCallback; i++ {
 		buf.WriteString(fmt.Sprintf("\tMOVD\t$%d, R12\n", i))
diff --git a/src/runtime/zcallback_windows.s b/src/runtime/zcallback_windows.s
index e451c2b9d0508bb5d46deaf3ff4c17a78a936ef5..561527c90d1c4d3e0e886e190e2a5f4632dd47c6 100644
--- a/src/runtime/zcallback_windows.s
+++ b/src/runtime/zcallback_windows.s
@@ -11,7 +11,7 @@
 // CALL instruction in runtime·callbackasm. This determines
 // which Go callback function is executed later on.
 
-TEXT runtime·callbackasm(SB),7,$0
+TEXT runtime·callbackasm(SB),7,$0
 	CALL	runtime·callbackasm1(SB)
 	CALL	runtime·callbackasm1(SB)
 	CALL	runtime·callbackasm1(SB)
diff --git a/src/runtime/zcallback_windows_arm.s b/src/runtime/zcallback_windows_arm.s
index a73a813acb3c5d9095699165125f139a7fde9554..f943d84cbfe5fddfd47ae7090658db059d70f6c8 100644
--- a/src/runtime/zcallback_windows_arm.s
+++ b/src/runtime/zcallback_windows_arm.s
@@ -9,7 +9,7 @@
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$0, R12
 	B	runtime·callbackasm1(SB)
 	MOVW	$1, R12
diff --git a/src/runtime/zcallback_windows_arm64.s b/src/runtime/zcallback_windows_arm64.s
index 2a6bda0990c108d3c180929ddcfe31ff34dba166..69fb05788cdab23883725e7b41cbf6a7f325692e 100644
--- a/src/runtime/zcallback_windows_arm64.s
+++ b/src/runtime/zcallback_windows_arm64.s
@@ -9,7 +9,7 @@
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 	MOVD	$0, R12
 	B	runtime·callbackasm1(SB)
 	MOVD	$1, R12
diff --git a/src/strconv/ftoaryu.go b/src/strconv/ftoaryu.go
index 1c61288b9ffa8ebaa7b7d294bc9d238700e7da3a..f2e74bed1779400c87820a9dbc9c127fdd0a9a4f 100644
--- a/src/strconv/ftoaryu.go
+++ b/src/strconv/ftoaryu.go
@@ -291,7 +291,7 @@ func ryuFtoaShortest(d *decimalSlice, mant uint64, exp int, flt *floatInfo) {
 	// Is it allowed to use 'du' as a result?
 	// It is always allowed when it is truncated, but also
 	// if it is exact and the original binary mantissa is even
-	// When disallowed, we can substract 1.
+	// When disallowed, we can subtract 1.
 	uok := !du0 || fracu > 0
 	if du0 && fracu == 0 {
 		uok = mant&1 == 0
diff --git a/src/strconv/quote.go b/src/strconv/quote.go
index b3bbb1612b9f634e930fc169bc329e87d1c8858d..d2814b92da795b77ceb1a4757748cf7d25ca6ea2 100644
--- a/src/strconv/quote.go
+++ b/src/strconv/quote.go
@@ -103,7 +103,7 @@ func appendEscapedRune(buf []byte, r rune, quote byte, ASCIIonly, graphicOnly bo
 			buf = append(buf, `\x`...)
 			buf = append(buf, lowerhex[byte(r)>>4])
 			buf = append(buf, lowerhex[byte(r)&0xF])
-		case r > utf8.MaxRune:
+		case !utf8.ValidRune(r):
 			r = 0xFFFD
 			fallthrough
 		case r < 0x10000:
@@ -322,7 +322,7 @@ func UnquoteChar(s string, quote byte) (value rune, multibyte bool, tail string,
 			value = v
 			break
 		}
-		if v > utf8.MaxRune {
+		if !utf8.ValidRune(v) {
 			err = ErrSyntax
 			return
 		}
diff --git a/src/strconv/quote_test.go b/src/strconv/quote_test.go
index 4750be27408a65dfd4c2f51864abda3862d60250..81fc8f79e147499f14798d1831bb8d61d6b55ce2 100644
--- a/src/strconv/quote_test.go
+++ b/src/strconv/quote_test.go
@@ -131,6 +131,7 @@ var quoterunetests = []quoteRuneTest{
 	{'\\', `'\\'`, `'\\'`, `'\\'`},
 	{0xFF, `'ÿ'`, `'\u00ff'`, `'ÿ'`},
 	{0x263a, `'☺'`, `'\u263a'`, `'☺'`},
+	{0xdead, `'�'`, `'\ufffd'`, `'�'`},
 	{0xfffd, `'�'`, `'\ufffd'`, `'�'`},
 	{0x0010ffff, `'\U0010ffff'`, `'\U0010ffff'`, `'\U0010ffff'`},
 	{0x0010ffff + 1, `'�'`, `'\ufffd'`, `'�'`},
@@ -305,6 +306,8 @@ var misquoted = []string{
 	"\"\n\"",
 	"\"\\n\n\"",
 	"'\n'",
+	`"\udead"`,
+	`"\ud83d\ude4f"`,
 }
 
 func TestUnquote(t *testing.T) {
diff --git a/src/strings/replace.go b/src/strings/replace.go
index e28d42887930b9d852bdd2129c28f4ebf3bd8c8b..ee728bb22b655259247ad7b871ae9983b28fac72 100644
--- a/src/strings/replace.go
+++ b/src/strings/replace.go
@@ -387,7 +387,7 @@ func makeSingleStringReplacer(pattern string, value string) *singleStringReplace
 }
 
 func (r *singleStringReplacer) Replace(s string) string {
-	var buf []byte
+	var buf Builder
 	i, matched := 0, false
 	for {
 		match := r.finder.next(s[i:])
@@ -395,15 +395,16 @@ func (r *singleStringReplacer) Replace(s string) string {
 			break
 		}
 		matched = true
-		buf = append(buf, s[i:i+match]...)
-		buf = append(buf, r.value...)
+		buf.Grow(match + len(r.value))
+		buf.WriteString(s[i : i+match])
+		buf.WriteString(r.value)
 		i += match + len(r.finder.pattern)
 	}
 	if !matched {
 		return s
 	}
-	buf = append(buf, s[i:]...)
-	return string(buf)
+	buf.WriteString(s[i:])
+	return buf.String()
 }
 
 func (r *singleStringReplacer) WriteString(w io.Writer, s string) (n int, err error) {
diff --git a/src/sync/atomic/value.go b/src/sync/atomic/value.go
index 61f81d8fd377b06e49e49b70bf88918589766998..3500cd22f4e74e7991d4f9cfca1ea6856695b722 100644
--- a/src/sync/atomic/value.go
+++ b/src/sync/atomic/value.go
@@ -126,7 +126,7 @@ func (v *Value) Swap(new interface{}) (old interface{}) {
 	}
 }
 
-// CompareAndSwapPointer executes the compare-and-swap operation for the Value.
+// CompareAndSwap executes the compare-and-swap operation for the Value.
 //
 // All calls to CompareAndSwap for a given Value must use values of the same
 // concrete type. CompareAndSwap of an inconsistent type panics, as does
diff --git a/src/syscall/dll_windows.go b/src/syscall/dll_windows.go
index 16210ca5b58a53d1cd26bec6374b3b17818feb7f..34b481d6e63543c1cf08cf1ea0d2ec664b66781a 100644
--- a/src/syscall/dll_windows.go
+++ b/src/syscall/dll_windows.go
@@ -5,7 +5,6 @@
 package syscall
 
 import (
-	"internal/itoa"
 	"internal/syscall/windows/sysdll"
 	"sync"
 	"sync/atomic"
@@ -25,12 +24,25 @@ func (e *DLLError) Unwrap() error { return e.Err }
 
 // Implemented in ../runtime/syscall_windows.go.
 
+// Deprecated: Use SyscallN instead.
 func Syscall(trap, nargs, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
+
+// Deprecated: Use SyscallN instead.
 func Syscall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
+
+// Deprecated: Use SyscallN instead.
 func Syscall9(trap, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err Errno)
+
+// Deprecated: Use SyscallN instead.
 func Syscall12(trap, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12 uintptr) (r1, r2 uintptr, err Errno)
+
+// Deprecated: Use SyscallN instead.
 func Syscall15(trap, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr) (r1, r2 uintptr, err Errno)
+
+// Deprecated: Use SyscallN instead.
 func Syscall18(trap, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, a17, a18 uintptr) (r1, r2 uintptr, err Errno)
+
+func SyscallN(trap uintptr, args ...uintptr) (r1, r2 uintptr, err Errno)
 func loadlibrary(filename *uint16) (handle uintptr, err Errno)
 func loadsystemlibrary(filename *uint16, absoluteFilepath *uint16) (handle uintptr, err Errno)
 func getprocaddress(handle uintptr, procname *uint8) (proc uintptr, err Errno)
@@ -160,8 +172,7 @@ func (p *Proc) Addr() uintptr {
 
 //go:uintptrescapes
 
-// Call executes procedure p with arguments a. It will panic if more than 18 arguments
-// are supplied.
+// Call executes procedure p with arguments a.
 //
 // The returned error is always non-nil, constructed from the result of GetLastError.
 // Callers must inspect the primary return value to decide whether an error occurred
@@ -175,49 +186,8 @@ func (p *Proc) Addr() uintptr {
 // values are returned in r2. The return value for C type "float" is
 // math.Float32frombits(uint32(r2)). For C type "double", it is
 // math.Float64frombits(uint64(r2)).
-func (p *Proc) Call(a ...uintptr) (r1, r2 uintptr, lastErr error) {
-	switch len(a) {
-	case 0:
-		return Syscall(p.Addr(), uintptr(len(a)), 0, 0, 0)
-	case 1:
-		return Syscall(p.Addr(), uintptr(len(a)), a[0], 0, 0)
-	case 2:
-		return Syscall(p.Addr(), uintptr(len(a)), a[0], a[1], 0)
-	case 3:
-		return Syscall(p.Addr(), uintptr(len(a)), a[0], a[1], a[2])
-	case 4:
-		return Syscall6(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], 0, 0)
-	case 5:
-		return Syscall6(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], 0)
-	case 6:
-		return Syscall6(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5])
-	case 7:
-		return Syscall9(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], 0, 0)
-	case 8:
-		return Syscall9(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], 0)
-	case 9:
-		return Syscall9(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8])
-	case 10:
-		return Syscall12(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], 0, 0)
-	case 11:
-		return Syscall12(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], 0)
-	case 12:
-		return Syscall12(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11])
-	case 13:
-		return Syscall15(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], 0, 0)
-	case 14:
-		return Syscall15(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], 0)
-	case 15:
-		return Syscall15(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14])
-	case 16:
-		return Syscall18(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15], 0, 0)
-	case 17:
-		return Syscall18(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15], a[16], 0)
-	case 18:
-		return Syscall18(p.Addr(), uintptr(len(a)), a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15], a[16], a[17])
-	default:
-		panic("Call " + p.Name + " with too many arguments " + itoa.Itoa(len(a)) + ".")
-	}
+func (p *Proc) Call(a ...uintptr) (uintptr, uintptr, error) {
+	return SyscallN(p.Addr(), a...)
 }
 
 // A LazyDLL implements access to a single DLL.
diff --git a/src/syscall/exec_libc2.go b/src/syscall/exec_libc2.go
index b999754c2e81bf33c15accea3ab169841af96284..bd98109d071c82963591be1d457b4cbf564ca0b9 100644
--- a/src/syscall/exec_libc2.go
+++ b/src/syscall/exec_libc2.go
@@ -117,14 +117,15 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	}
 
 	if sys.Foreground {
-		pgrp := sys.Pgid
+		// This should really be pid_t, however _C_int (aka int32) is
+		// generally equivalent.
+		pgrp := _C_int(sys.Pgid)
 		if pgrp == 0 {
 			r1, _, err1 = rawSyscall(abi.FuncPCABI0(libc_getpid_trampoline), 0, 0, 0)
 			if err1 != 0 {
 				goto childerror
 			}
-
-			pgrp = int(r1)
+			pgrp = _C_int(r1)
 		}
 
 		// Place process group in foreground.
diff --git a/src/syscall/js/export_test.go b/src/syscall/js/export_test.go
index 1b5ed3ce8491c2838e5b430ad4a57bfc5fc48ce7..4bd9c5d595eb72a8a186de52d2beaf80e9aa7b9d 100644
--- a/src/syscall/js/export_test.go
+++ b/src/syscall/js/export_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 package js
diff --git a/src/syscall/js/func.go b/src/syscall/js/func.go
index da4cf68774ddcd6ebd25aaaf1c93f548595883cb..ab23e5fbfc0cce35a8821c6de43ef36bbaf90157 100644
--- a/src/syscall/js/func.go
+++ b/src/syscall/js/func.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 package js
diff --git a/src/syscall/js/js.go b/src/syscall/js/js.go
index a48bbd4dd794b707bbb50a49fee6691b8eed7340..d805d6916644d7d0c0dde33d1706bf87e72d064a 100644
--- a/src/syscall/js/js.go
+++ b/src/syscall/js/js.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 // Package js gives access to the WebAssembly host environment when using the js/wasm architecture.
diff --git a/src/syscall/js/js_test.go b/src/syscall/js/js_test.go
index 5fc9107d40250ce9da212e5db934a7c1c49da446..8088a897f60716ffb2f439f177fc7fa4372b99ce 100644
--- a/src/syscall/js/js_test.go
+++ b/src/syscall/js/js_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 // To run these tests:
diff --git a/src/syscall/net_js.go b/src/syscall/net_js.go
index ed462025bbc88c1d3f5e4972e51320ba1c726b25..2998c2159c8ef77d35ceb10846d08bfb17604851 100644
--- a/src/syscall/net_js.go
+++ b/src/syscall/net_js.go
@@ -92,10 +92,26 @@ func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
 	return 0, nil, ENOSYS
 }
 
+func RecvfromInet4(fd int, p []byte, flags int, from *SockaddrInet4) (n int, err error) {
+	return 0, ENOSYS
+}
+
+func RecvfromInet6(fd int, p []byte, flags int, from *SockaddrInet6) (n int, err error) {
+	return 0, ENOSYS
+}
+
 func Sendto(fd int, p []byte, flags int, to Sockaddr) error {
 	return ENOSYS
 }
 
+func SendtoInet4(fd int, p []byte, flags int, to SockaddrInet4) error {
+	return ENOSYS
+}
+
+func SendtoInet6(fd int, p []byte, flags int, to SockaddrInet6) error {
+	return ENOSYS
+}
+
 func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn, recvflags int, from Sockaddr, err error) {
 	return 0, 0, 0, nil, ENOSYS
 }
diff --git a/src/syscall/netlink_linux.go b/src/syscall/netlink_linux.go
index 0937ff797ad4dcd3ae3323a8a71e1d75c6775d7a..2d810705bf1bcd38f162bf5a639244619af6a163 100644
--- a/src/syscall/netlink_linux.go
+++ b/src/syscall/netlink_linux.go
@@ -55,14 +55,22 @@ func NetlinkRIB(proto, family int) ([]byte, error) {
 		return nil, err
 	}
 	defer Close(s)
-	lsa := &SockaddrNetlink{Family: AF_NETLINK}
-	if err := Bind(s, lsa); err != nil {
+	sa := &SockaddrNetlink{Family: AF_NETLINK}
+	if err := Bind(s, sa); err != nil {
 		return nil, err
 	}
 	wb := newNetlinkRouteRequest(proto, 1, family)
-	if err := Sendto(s, wb, 0, lsa); err != nil {
+	if err := Sendto(s, wb, 0, sa); err != nil {
 		return nil, err
 	}
+	lsa, err := Getsockname(s)
+	if err != nil {
+		return nil, err
+	}
+	lsanl, ok := lsa.(*SockaddrNetlink)
+	if !ok {
+		return nil, EINVAL
+	}
 	var tab []byte
 	rbNew := make([]byte, Getpagesize())
 done:
@@ -82,16 +90,7 @@ done:
 			return nil, err
 		}
 		for _, m := range msgs {
-			lsa, err := Getsockname(s)
-			if err != nil {
-				return nil, err
-			}
-			switch v := lsa.(type) {
-			case *SockaddrNetlink:
-				if m.Header.Seq != 1 || m.Header.Pid != v.Pid {
-					return nil, EINVAL
-				}
-			default:
+			if m.Header.Seq != 1 || m.Header.Pid != lsanl.Pid {
 				return nil, EINVAL
 			}
 			if m.Header.Type == NLMSG_DONE {
diff --git a/src/syscall/syscall_unix.go b/src/syscall/syscall_unix.go
index 5b405b99b4f23744bb35f308ab1b8b015d3994ee..101e39c7d0885395ac8d84438a2ff6092cd6aa2a 100644
--- a/src/syscall/syscall_unix.go
+++ b/src/syscall/syscall_unix.go
@@ -292,6 +292,49 @@ func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
 	return
 }
 
+func RecvfromInet4(fd int, p []byte, flags int, from *SockaddrInet4) (n int, err error) {
+	var rsa RawSockaddrAny
+	var socklen _Socklen = SizeofSockaddrAny
+	if n, err = recvfrom(fd, p, flags, &rsa, &socklen); err != nil {
+		return
+	}
+	pp := (*RawSockaddrInet4)(unsafe.Pointer(&rsa))
+	port := (*[2]byte)(unsafe.Pointer(&pp.Port))
+	from.Port = int(port[0])<<8 + int(port[1])
+	from.Addr = pp.Addr
+	return
+}
+
+func RecvfromInet6(fd int, p []byte, flags int, from *SockaddrInet6) (n int, err error) {
+	var rsa RawSockaddrAny
+	var socklen _Socklen = SizeofSockaddrAny
+	if n, err = recvfrom(fd, p, flags, &rsa, &socklen); err != nil {
+		return
+	}
+	pp := (*RawSockaddrInet6)(unsafe.Pointer(&rsa))
+	port := (*[2]byte)(unsafe.Pointer(&pp.Port))
+	from.Port = int(port[0])<<8 + int(port[1])
+	from.ZoneId = pp.Scope_id
+	from.Addr = pp.Addr
+	return
+}
+
+func SendtoInet4(fd int, p []byte, flags int, to SockaddrInet4) (err error) {
+	ptr, n, err := to.sockaddr()
+	if err != nil {
+		return err
+	}
+	return sendto(fd, p, flags, ptr, n)
+}
+
+func SendtoInet6(fd int, p []byte, flags int, to SockaddrInet6) (err error) {
+	ptr, n, err := to.sockaddr()
+	if err != nil {
+		return err
+	}
+	return sendto(fd, p, flags, ptr, n)
+}
+
 func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
 	ptr, n, err := to.sockaddr()
 	if err != nil {
diff --git a/src/syscall/syscall_windows.go b/src/syscall/syscall_windows.go
index 660179ae9e8cf32ddccb2e09b3ac45dbf136f860..d4e51e541d1f09bb75c1497ad175f5f37c73e78c 100644
--- a/src/syscall/syscall_windows.go
+++ b/src/syscall/syscall_windows.go
@@ -924,6 +924,38 @@ func WSASendto(s Handle, bufs *WSABuf, bufcnt uint32, sent *uint32, flags uint32
 	return err
 }
 
+func WSASendtoInet4(s Handle, bufs *WSABuf, bufcnt uint32, sent *uint32, flags uint32, to SockaddrInet4, overlapped *Overlapped, croutine *byte) (err error) {
+	rsa, len, err := to.sockaddr()
+	if err != nil {
+		return err
+	}
+	r1, _, e1 := Syscall9(procWSASendTo.Addr(), 9, uintptr(s), uintptr(unsafe.Pointer(bufs)), uintptr(bufcnt), uintptr(unsafe.Pointer(sent)), uintptr(flags), uintptr(unsafe.Pointer(rsa)), uintptr(len), uintptr(unsafe.Pointer(overlapped)), uintptr(unsafe.Pointer(croutine)))
+	if r1 == socket_error {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = EINVAL
+		}
+	}
+	return err
+}
+
+func WSASendtoInet6(s Handle, bufs *WSABuf, bufcnt uint32, sent *uint32, flags uint32, to SockaddrInet6, overlapped *Overlapped, croutine *byte) (err error) {
+	rsa, len, err := to.sockaddr()
+	if err != nil {
+		return err
+	}
+	r1, _, e1 := Syscall9(procWSASendTo.Addr(), 9, uintptr(s), uintptr(unsafe.Pointer(bufs)), uintptr(bufcnt), uintptr(unsafe.Pointer(sent)), uintptr(flags), uintptr(unsafe.Pointer(rsa)), uintptr(len), uintptr(unsafe.Pointer(overlapped)), uintptr(unsafe.Pointer(croutine)))
+	if r1 == socket_error {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = EINVAL
+		}
+	}
+	return err
+}
+
 func LoadGetAddrInfo() error {
 	return procGetAddrInfoW.Find()
 }
diff --git a/src/testing/fstest/mapfs.go b/src/testing/fstest/mapfs.go
index 9fef2f4696ec7944acc891eb3c69e86a3f376139..056ef133fac928e173c26ce8d34d7ab5f18b064e 100644
--- a/src/testing/fstest/mapfs.go
+++ b/src/testing/fstest/mapfs.go
@@ -66,7 +66,9 @@ func (fsys MapFS) Open(name string) (fs.File, error) {
 		for fname, f := range fsys {
 			i := strings.Index(fname, "/")
 			if i < 0 {
-				list = append(list, mapFileInfo{fname, f})
+				if fname != "." {
+					list = append(list, mapFileInfo{fname, f})
+				}
 			} else {
 				need[fname[:i]] = true
 			}
diff --git a/src/testing/fstest/mapfs_test.go b/src/testing/fstest/mapfs_test.go
index 2abedd67351fc4d4b258225c7ec79d5d02764fad..c8d29283b28989c942ac9b00d51c1311717876fa 100644
--- a/src/testing/fstest/mapfs_test.go
+++ b/src/testing/fstest/mapfs_test.go
@@ -5,6 +5,9 @@
 package fstest
 
 import (
+	"fmt"
+	"io/fs"
+	"strings"
 	"testing"
 )
 
@@ -17,3 +20,28 @@ func TestMapFS(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestMapFSChmodDot(t *testing.T) {
+	m := MapFS{
+		"a/b.txt": &MapFile{Mode: 0666},
+		".":       &MapFile{Mode: 0777 | fs.ModeDir},
+	}
+	buf := new(strings.Builder)
+	fs.WalkDir(m, ".", func(path string, d fs.DirEntry, err error) error {
+		fi, err := d.Info()
+		if err != nil {
+			return err
+		}
+		fmt.Fprintf(buf, "%s: %v\n", path, fi.Mode())
+		return nil
+	})
+	want := `
+.: drwxrwxrwx
+a: d---------
+a/b.txt: -rw-rw-rw-
+`[1:]
+	got := buf.String()
+	if want != got {
+		t.Errorf("MapFS modes want:\n%s\ngot:\n%s\n", want, got)
+	}
+}
diff --git a/src/time/format.go b/src/time/format.go
index bb173a21c2d4584f7b9015eb1c832ba7d63d86dc..f4b4f48142f69387b72babac32ac888ff036145d 100644
--- a/src/time/format.go
+++ b/src/time/format.go
@@ -77,9 +77,9 @@ import "errors"
 // The formats  and 002 are space-padded and zero-padded
 // three-character day of year; there is no unpadded day of year format.
 //
-// A decimal point followed by one or more zeros represents a fractional
-// second, printed to the given number of decimal places.
-// Either a comma or decimal point followed by one or more nines represents
+// A comma or decimal point followed by one or more zeros represents
+// a fractional second, printed to the given number of decimal places.
+// A comma or decimal point followed by one or more nines represents
 // a fractional second, printed to the given number of decimal places, with
 // trailing zeros removed.
 // For example "15:04:05,000" or "15:04:05.000" formats or parses with
diff --git a/src/time/sleep.go b/src/time/sleep.go
index 4f4579941469cd978ef39c0b01e0f281e3ed39f3..b467d1d589d1e70fa32914f1f3cce1f8859ae877 100644
--- a/src/time/sleep.go
+++ b/src/time/sleep.go
@@ -139,12 +139,8 @@ func (t *Timer) Reset(d Duration) bool {
 	return resetTimer(&t.r, w)
 }
 
+// sendTime does a non-blocking send of the current time on c.
 func sendTime(c interface{}, seq uintptr) {
-	// Non-blocking send of time on c.
-	// Used in NewTimer, it cannot block anyway (buffer).
-	// Used in NewTicker, dropping sends on the floor is
-	// the desired behavior when the reader gets behind,
-	// because the sends are periodic.
 	select {
 	case c.(chan Time) <- Now():
 	default:
diff --git a/src/time/tick.go b/src/time/tick.go
index 81d2a43f2838800bf0b1d8cc456882600fc35de3..f9522b0b754ad6c2566b0e04cb45fd856a7857b5 100644
--- a/src/time/tick.go
+++ b/src/time/tick.go
@@ -14,9 +14,9 @@ type Ticker struct {
 }
 
 // NewTicker returns a new Ticker containing a channel that will send
-// the time on the channel after each tick. The period of the ticks is
-// specified by the duration argument. The ticker will adjust the time
-// interval or drop ticks to make up for slow receivers.
+// the current time on the channel after each tick. The period of the
+// ticks is specified by the duration argument. The ticker will adjust
+// the time interval or drop ticks to make up for slow receivers.
 // The duration d must be greater than zero; if not, NewTicker will
 // panic. Stop the ticker to release associated resources.
 func NewTicker(d Duration) *Ticker {
diff --git a/src/time/tzdata/generate_zipdata.go b/src/time/tzdata/generate_zipdata.go
index 64b5b1b22c234fcba7056e93ce9c72145a5e5c52..0869c8458c60ae18edf1f1398534022b28f56ce7 100644
--- a/src/time/tzdata/generate_zipdata.go
+++ b/src/time/tzdata/generate_zipdata.go
@@ -31,8 +31,8 @@ const header = `// Copyright 2020 The Go Authors. All rights reserved.
 
 // For more information, see
 // https://www.iana.org/time-zones
-// ftp://ftp.iana.org/tz/code/tz-link.htm
-// http://tools.ietf.org/html/rfc6557
+// ftp://ftp.iana.org/tz/code/tz-link.html
+// https://datatracker.ietf.org/doc/html/rfc6557
 
 package tzdata
 
diff --git a/src/time/tzdata/zipdata.go b/src/time/tzdata/zipdata.go
index 03b59720e27eb9b3add26ed883138bf3e200cb8b..60c078400824c99621daad4b29af5ee42becb942 100644
--- a/src/time/tzdata/zipdata.go
+++ b/src/time/tzdata/zipdata.go
@@ -11,8 +11,8 @@
 
 // For more information, see
 // https://www.iana.org/time-zones
-// ftp://ftp.iana.org/tz/code/tz-link.htm
-// http://tools.ietf.org/html/rfc6557
+// ftp://ftp.iana.org/tz/code/tz-link.html
+// https://datatracker.ietf.org/doc/html/rfc6557
 
 package tzdata
 
diff --git a/test/chan/perm.go b/test/chan/perm.go
index 4c94ab7ffaeefb2e96cd260768e2a4ceb2486983..04046723a4f6fefda18911b4bb9351086177ae0f 100644
--- a/test/chan/perm.go
+++ b/test/chan/perm.go
@@ -66,5 +66,5 @@ func main() {
 	close(c)
 	close(cs)
 	close(cr) // ERROR "receive"
-	close(n)  // ERROR "invalid operation.*non-chan type|must be channel|not a channel"
+	close(n)  // ERROR "invalid operation.*non-chan type|must be channel|non-channel"
 }
diff --git a/test/codegen/arithmetic.go b/test/codegen/arithmetic.go
index a27a17f6e112df3752870135b62b5e4440f39f97..eb0f338036c3c8e7907b670265cc361f0007186d 100644
--- a/test/codegen/arithmetic.go
+++ b/test/codegen/arithmetic.go
@@ -202,7 +202,7 @@ func ConstDivs(n1 uint, n2 int) (uint, int) {
 
 	// amd64:"MOVQ\t[$]-1085102592571150095","IMULQ",-"IDIVQ"
 	// 386:"MOVL\t[$]-252645135","IMULL",-"IDIVL"
-	// arm64:`MOVD`,`SMULH`,-`DIV`
+	// arm64:`SMULH`,-`DIV`
 	// arm:`MOVW`,`MUL`,-`.*udiv`
 	b := n2 / 17 // signed
 
@@ -266,7 +266,7 @@ func ConstMods(n1 uint, n2 int) (uint, int) {
 
 	// amd64:"MOVQ\t[$]-1085102592571150095","IMULQ",-"IDIVQ"
 	// 386:"MOVL\t[$]-252645135","IMULL",-"IDIVL"
-	// arm64:`MOVD`,`SMULH`,-`DIV`
+	// arm64:`SMULH`,-`DIV`
 	// arm:`MOVW`,`MUL`,-`.*udiv`
 	b := n2 % 17 // signed
 
diff --git a/test/codegen/clobberdead.go b/test/codegen/clobberdead.go
index f8d964cba689a80b1924e62a5a9f7c7e9080fd7d..c490790bb63ded8997211ff95a6ffc5a5fedb442 100644
--- a/test/codegen/clobberdead.go
+++ b/test/codegen/clobberdead.go
@@ -1,6 +1,6 @@
 // asmcheck -gcflags=-clobberdead
 
-// +build amd64
+// +build amd64 arm64
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -13,15 +13,18 @@ type T [2]*int // contain pointer, not SSA-able (so locals are not registerized)
 var p1, p2, p3 T
 
 func F() {
-	// 3735936685 is 0xdeaddead
+	// 3735936685 is 0xdeaddead. On ARM64 R27 is REGTMP.
 	// clobber x, y at entry. not clobber z (stack object).
 	// amd64:`MOVL\t\$3735936685, ""\.x`, `MOVL\t\$3735936685, ""\.y`, -`MOVL\t\$3735936685, ""\.z`
+	// arm64:`MOVW\tR27, ""\.x`, `MOVW\tR27, ""\.y`, -`MOVW\tR27, ""\.z`
 	x, y, z := p1, p2, p3
 	addrTaken(&z)
 	// x is dead at the call (the value of x is loaded before the CALL), y is not
 	// amd64:`MOVL\t\$3735936685, ""\.x`, -`MOVL\t\$3735936685, ""\.y`
+	// arm64:`MOVW\tR27, ""\.x`, -`MOVW\tR27, ""\.y`
 	use(x)
 	// amd64:`MOVL\t\$3735936685, ""\.x`, `MOVL\t\$3735936685, ""\.y`
+	// arm64:`MOVW\tR27, ""\.x`, `MOVW\tR27, ""\.y`
 	use(y)
 }
 
diff --git a/test/codegen/mathbits.go b/test/codegen/mathbits.go
index 03012eff5d8444a2e71e5f0a49ccc8e850ae004c..aecd84a78bb1c215d0fd4d22c5ed6a52984fb952 100644
--- a/test/codegen/mathbits.go
+++ b/test/codegen/mathbits.go
@@ -710,6 +710,7 @@ func Mul64(x, y uint64) (hi, lo uint64) {
 	// ppc64le:"MULHDU","MULLD"
 	// s390x:"MLGR"
 	// mips64: "MULVU"
+	// riscv64:"MULHU","MUL"
 	return bits.Mul64(x, y)
 }
 
diff --git a/test/complit1.go b/test/complit1.go
index 7c2a4e2996d5160a8500a1a3a139f8de156a21c3..8cbcd63ee0d176d93e88b951e758215f776f60d1 100644
--- a/test/complit1.go
+++ b/test/complit1.go
@@ -46,20 +46,20 @@ var (
 	_ = &T{0, 0, "", nil}               // ok
 	_ = &T{i: 0, f: 0, s: "", next: {}} // ERROR "missing type in composite literal|omit types within composite literal"
 	_ = &T{0, 0, "", {}}                // ERROR "missing type in composite literal|omit types within composite literal"
-	_ = TP{i: 0, f: 0, s: "", next: {}} // ERROR "invalid composite literal type TP|omit types within composite literal"
+	_ = TP{i: 0, f: 0, s: ""}           // ERROR "invalid composite literal type TP"
 	_ = &Ti{}                           // ERROR "invalid composite literal type Ti|expected.*type for composite literal"
 )
 
 type M map[T]T
 
 var (
-	_ = M{{i:1}: {i:2}}
-	_ = M{T{i:1}: {i:2}}
-	_ = M{{i:1}: T{i:2}}
-	_ = M{T{i:1}: T{i:2}}
+	_ = M{{i: 1}: {i: 2}}
+	_ = M{T{i: 1}: {i: 2}}
+	_ = M{{i: 1}: T{i: 2}}
+	_ = M{T{i: 1}: T{i: 2}}
 )
 
-type S struct { s [1]*M1 }
+type S struct{ s [1]*M1 }
 type M1 map[S]int
-var _ = M1{{s:[1]*M1{&M1{{}:1}}}:2}
 
+var _ = M1{{s: [1]*M1{&M1{{}: 1}}}: 2}
diff --git a/test/ddd1.go b/test/ddd1.go
index ad49b347f49dd66439b17fb86e9d2ad3569fc2e3..f7381b7c946212b7b2686b419b6a706a50b842df 100644
--- a/test/ddd1.go
+++ b/test/ddd1.go
@@ -17,8 +17,8 @@ var (
 	_ = sum(1, 2, 3)
 	_ = sum()
 	_ = sum(1.0, 2.0)
-	_ = sum(1.5)      // ERROR "integer"
-	_ = sum("hello")  // ERROR ".hello. .type untyped string. as type int|incompatible"
+	_ = sum(1.5)      // ERROR "1\.5 .untyped float constant. as int|integer"
+	_ = sum("hello")  // ERROR ".hello. (.untyped string constant. as int|.type untyped string. as type int)|incompatible"
 	_ = sum([]int{1}) // ERROR "\[\]int{...}.*as type int|incompatible"
 )
 
@@ -27,9 +27,9 @@ func tuple() (int, int, int) { return 1, 2, 3 }
 
 var (
 	_ = sum(tuple())
-	_ = sum(tuple()...) // ERROR "multiple-value"
+	_ = sum(tuple()...) // ERROR "\.{3} with 3-valued|multiple-value"
 	_ = sum3(tuple())
-	_ = sum3(tuple()...) // ERROR "multiple-value" ERROR "invalid use of .*[.][.][.]"
+	_ = sum3(tuple()...) // ERROR "\.{3} in call to non-variadic|multiple-value|invalid use of .*[.][.][.]"
 )
 
 type T []T
@@ -60,5 +60,5 @@ func bad(args ...int) {
 	_ = [...]byte("foo") // ERROR "[.][.][.]"
 	_ = [...][...]int{{1,2,3},{4,5,6}}	// ERROR "[.][.][.]"
 
-	Foo(x...) // ERROR "invalid use of .*[.][.][.]"
+	Foo(x...) // ERROR "\.{3} in call to non-variadic|invalid use of .*[.][.][.]"
 }
diff --git a/test/devirt.go b/test/devirt.go
index e0149d8229247fccb35a1c40db8070f7b46c733e..d5c815222e448cb01b9620256db9e55f9cc09d0d 100644
--- a/test/devirt.go
+++ b/test/devirt.go
@@ -31,9 +31,8 @@ func main() {
 		panic("not 3")
 	}
 
-	// Can't do types that aren't "direct" interfaces (yet).
 	r = indirectiface{3, 4, 5}
-	if r.Value() != 12 {
+	if r.Value() != 12 { // ERROR "de-virtualizing call$"
 		panic("not 12")
 	}
 }
diff --git a/test/escape2.go b/test/escape2.go
index b9b723d8666862195d9bc090eda8608ba0bf607e..e3e5904cde525bc9b4c2412a1c52b5764e23f837 100644
--- a/test/escape2.go
+++ b/test/escape2.go
@@ -59,7 +59,7 @@ func foo8(xx, yy *int) int { // ERROR "xx does not escape$" "yy does not escape$
 	return *xx
 }
 
-func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r2 level=0$" "leaking param: yy to result ~r2 level=0$"
+func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r0 level=0$" "leaking param: yy to result ~r0 level=0$"
 	xx = yy
 	return xx
 }
@@ -343,11 +343,11 @@ func indaddr1(x int) *int { // ERROR "moved to heap: x$"
 	return &x
 }
 
-func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *&x
 }
 
-func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *(**int)(unsafe.Pointer(&x))
 }
 
@@ -374,11 +374,11 @@ func float64bitsptr(f float64) *uint64 { // ERROR "moved to heap: f$"
 	return (*uint64)(unsafe.Pointer(&f))
 }
 
-func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r1 level=0$"
+func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r0 level=0$"
 	return (*uint64)(unsafe.Pointer(f))
 }
 
-func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch val := i.(type) {
 	case *int:
 		return val
@@ -389,7 +389,7 @@ func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level
 	return nil
 }
 
-func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch j := i; *j + 110 {
 	case 12:
 		return j
@@ -401,7 +401,7 @@ func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
 }
 
 // assigning to an array element is like assigning to the array
-func foo60(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo60(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	var a [12]*int
 	a[0] = i
 	return a[1]
@@ -414,7 +414,7 @@ func foo60a(i *int) *int { // ERROR "i does not escape$"
 }
 
 // assigning to a struct field  is like assigning to the struct
-func foo61(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo61(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	type S struct {
 		a, b *int
 	}
@@ -611,11 +611,11 @@ func foo74c() {
 	}
 }
 
-func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r2 level=0$" "x does not escape$"
+func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r0 level=0$" "x does not escape$"
 	return y
 }
 
-func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r2 level=0$" "y does not escape$"
+func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r0 level=0$" "y does not escape$"
 	return &x[0]
 }
 
@@ -667,13 +667,13 @@ func foo76e() {
 func foo76f() {
 	for {
 		// TODO: This one really only escapes its scope, but we don't distinguish yet.
-		defer myprint(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
 func foo76g() {
 	for {
-		defer myprint1(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint1(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
@@ -770,7 +770,7 @@ func foo91(x *int) map[*int]*int { // ERROR "leaking param: x$"
 	return map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int{...} escapes to heap$"
 }
 
-func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return [2]*int{x, nil}
 }
 
@@ -783,7 +783,7 @@ func foo93(c chan *int) *int { // ERROR "c does not escape$"
 }
 
 // does not leak m
-func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r2 level=1"
+func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for k, v := range m {
 		if b {
 			return k
@@ -799,12 +799,12 @@ func foo95(m map[*int]*int, x *int) { // ERROR "m does not escape$" "leaking par
 }
 
 // does not leak m but does leak content
-func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	return m[0]
 }
 
 // does leak m
-func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[0]
 }
 
@@ -814,12 +814,12 @@ func foo98(m map[int]*int) *int { // ERROR "m does not escape$"
 }
 
 // does leak m
-func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[:]
 }
 
 // does not leak m
-func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for _, v := range m {
 		return v
 	}
@@ -827,7 +827,7 @@ func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
 }
 
 // does leak m
-func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	for _, v := range m {
 		return v
 	}
@@ -890,27 +890,27 @@ func foo110(x *int) *int { // ERROR "leaking param: x$"
 	return m[nil]
 }
 
-func foo111(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0"
+func foo111(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0"
 	m := []*int{x} // ERROR "\[\]\*int{...} does not escape$"
 	return m[0]
 }
 
-func foo112(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo112(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := [1]*int{x}
 	return m[0]
 }
 
-func foo113(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo113(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := Bar{ii: x}
 	return m.ii
 }
 
-func foo114(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo114(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := &Bar{ii: x} // ERROR "&Bar{...} does not escape$"
 	return m.ii
 }
 
-func foo115(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo115(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return (*int)(unsafe.Pointer(uintptr(unsafe.Pointer(x)) + 1))
 }
 
@@ -1148,16 +1148,16 @@ L100:
 
 func foo121() {
 	for i := 0; i < 10; i++ {
-		defer myprint(nil, i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go myprint(nil, i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer myprint(nil, i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go myprint(nil, i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
 // same as foo121 but check across import
 func foo121b() {
 	for i := 0; i < 10; i++ {
-		defer fmt.Printf("%d", i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go fmt.Printf("%d", i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer fmt.Printf("%d", i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go fmt.Printf("%d", i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
diff --git a/test/escape2n.go b/test/escape2n.go
index 7c8208aa73ca11afb097cd1a0fb9e68922dc8d89..57cc1a01639eb410656caaba1e6bc092c4b59d0e 100644
--- a/test/escape2n.go
+++ b/test/escape2n.go
@@ -59,7 +59,7 @@ func foo8(xx, yy *int) int { // ERROR "xx does not escape$" "yy does not escape$
 	return *xx
 }
 
-func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r2 level=0$" "leaking param: yy to result ~r2 level=0$"
+func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r0 level=0$" "leaking param: yy to result ~r0 level=0$"
 	xx = yy
 	return xx
 }
@@ -343,11 +343,11 @@ func indaddr1(x int) *int { // ERROR "moved to heap: x$"
 	return &x
 }
 
-func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *&x
 }
 
-func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *(**int)(unsafe.Pointer(&x))
 }
 
@@ -374,11 +374,11 @@ func float64bitsptr(f float64) *uint64 { // ERROR "moved to heap: f$"
 	return (*uint64)(unsafe.Pointer(&f))
 }
 
-func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r1 level=0$"
+func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r0 level=0$"
 	return (*uint64)(unsafe.Pointer(f))
 }
 
-func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch val := i.(type) {
 	case *int:
 		return val
@@ -389,7 +389,7 @@ func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level
 	return nil
 }
 
-func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch j := i; *j + 110 {
 	case 12:
 		return j
@@ -401,7 +401,7 @@ func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
 }
 
 // assigning to an array element is like assigning to the array
-func foo60(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo60(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	var a [12]*int
 	a[0] = i
 	return a[1]
@@ -414,7 +414,7 @@ func foo60a(i *int) *int { // ERROR "i does not escape$"
 }
 
 // assigning to a struct field  is like assigning to the struct
-func foo61(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo61(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	type S struct {
 		a, b *int
 	}
@@ -611,11 +611,11 @@ func foo74c() {
 	}
 }
 
-func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r2 level=0$" "x does not escape$"
+func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r0 level=0$" "x does not escape$"
 	return y
 }
 
-func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r2 level=0$" "y does not escape$"
+func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r0 level=0$" "y does not escape$"
 	return &x[0]
 }
 
@@ -667,13 +667,13 @@ func foo76e() {
 func foo76f() {
 	for {
 		// TODO: This one really only escapes its scope, but we don't distinguish yet.
-		defer myprint(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
 func foo76g() {
 	for {
-		defer myprint1(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint1(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
@@ -770,7 +770,7 @@ func foo91(x *int) map[*int]*int { // ERROR "leaking param: x$"
 	return map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int{...} escapes to heap$"
 }
 
-func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return [2]*int{x, nil}
 }
 
@@ -783,7 +783,7 @@ func foo93(c chan *int) *int { // ERROR "c does not escape$"
 }
 
 // does not leak m
-func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r2 level=1"
+func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for k, v := range m {
 		if b {
 			return k
@@ -799,12 +799,12 @@ func foo95(m map[*int]*int, x *int) { // ERROR "m does not escape$" "leaking par
 }
 
 // does not leak m but does leak content
-func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	return m[0]
 }
 
 // does leak m
-func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[0]
 }
 
@@ -814,12 +814,12 @@ func foo98(m map[int]*int) *int { // ERROR "m does not escape$"
 }
 
 // does leak m
-func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[:]
 }
 
 // does not leak m
-func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for _, v := range m {
 		return v
 	}
@@ -827,7 +827,7 @@ func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
 }
 
 // does leak m
-func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	for _, v := range m {
 		return v
 	}
@@ -890,27 +890,27 @@ func foo110(x *int) *int { // ERROR "leaking param: x$"
 	return m[nil]
 }
 
-func foo111(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0"
+func foo111(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0"
 	m := []*int{x} // ERROR "\[\]\*int{...} does not escape$"
 	return m[0]
 }
 
-func foo112(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo112(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := [1]*int{x}
 	return m[0]
 }
 
-func foo113(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo113(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := Bar{ii: x}
 	return m.ii
 }
 
-func foo114(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo114(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := &Bar{ii: x} // ERROR "&Bar{...} does not escape$"
 	return m.ii
 }
 
-func foo115(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo115(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return (*int)(unsafe.Pointer(uintptr(unsafe.Pointer(x)) + 1))
 }
 
@@ -1148,16 +1148,16 @@ L100:
 
 func foo121() {
 	for i := 0; i < 10; i++ {
-		defer myprint(nil, i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go myprint(nil, i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer myprint(nil, i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go myprint(nil, i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
 // same as foo121 but check across import
 func foo121b() {
 	for i := 0; i < 10; i++ {
-		defer fmt.Printf("%d", i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go fmt.Printf("%d", i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer fmt.Printf("%d", i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go fmt.Printf("%d", i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
diff --git a/test/escape5.go b/test/escape5.go
index 82be2c38e790e64f8ffc62f86a84d8572e563142..089130dad5c73e2163b7fbd3fa0c509ada81c319 100644
--- a/test/escape5.go
+++ b/test/escape5.go
@@ -22,19 +22,19 @@ func leaktoret(p *int) *int { // ERROR "leaking param: p to result"
 	return p
 }
 
-func leaktoret2(p *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: p to result ~r2"
+func leaktoret2(p *int) (*int, *int) { // ERROR "leaking param: p to result ~r0" "leaking param: p to result ~r1"
 	return p, p
 }
 
-func leaktoret22(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r2" "leaking param: q to result ~r3"
+func leaktoret22(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r0" "leaking param: q to result ~r1"
 	return p, q
 }
 
-func leaktoret22b(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r3" "leaking param: q to result ~r2"
+func leaktoret22b(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: q to result ~r0"
 	return leaktoret22(q, p)
 }
 
-func leaktoret22c(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r3" "leaking param: q to result ~r2"
+func leaktoret22c(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: q to result ~r0"
 	r, s := leaktoret22(q, p)
 	return r, s
 }
@@ -173,15 +173,14 @@ type U int
 func (*U) M()   {}
 func (_ *U) N() {}
 
-func _() {
+func fbad24305a() {
 	var u U
 	u.M()
 	u.N()
 }
 
-func fbad24305() {
-	// BAD u should not be heap allocated
-	var u U // ERROR "moved to heap: u"
+func fbad24305b() {
+	var u U
 	(*U).M(&u)
 	(*U).N(&u)
 }
diff --git a/test/escape_array.go b/test/escape_array.go
index 0d07fd861ffb331dc019b55887a08e4484aa3f30..83062c9436e71d2a1ed9462633b2e8d829a63197 100644
--- a/test/escape_array.go
+++ b/test/escape_array.go
@@ -12,15 +12,15 @@ var Ssink *string
 
 type U [2]*string
 
-func bar(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+func bar(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
 	return U{a, b}
 }
 
-func foo(x U) U { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
 	return U{x[1], x[0]}
 }
 
-func bff(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+func bff(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
 	return foo(foo(bar(a, b)))
 }
 
@@ -41,27 +41,27 @@ func tbff2() *string {
 	return u[1]
 }
 
-func car(x U) *string { // ERROR "leaking param: x to result ~r1 level=0$"
+func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
 	return x[0]
 }
 
 // BAD: need fine-grained analysis to track x[0] and x[1] differently.
-func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=0$" "leaking param: y to result ~r2 level=0$"
+func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
 	x[0] = y
 	return x[1]
 }
 
-func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param: y$"
+func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
 	x[0] = y // leaking y to heap is intended
 	return x[1]
 }
 
-func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
 	x[0] = *y
 	return x[1]
 }
 
-func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
 	x[0] = y[0]
 	return x[1]
 }
diff --git a/test/escape_calls.go b/test/escape_calls.go
index 9e1db5426ed5d69b3ed20bb907cdc59ae8975b53..aa7c7f516cf96ef38dc7ab1b8617e7cbf5b246e7 100644
--- a/test/escape_calls.go
+++ b/test/escape_calls.go
@@ -11,7 +11,7 @@
 
 package foo
 
-func f(buf []byte) []byte { // ERROR "leaking param: buf to result ~r1 level=0$"
+func f(buf []byte) []byte { // ERROR "leaking param: buf to result ~r0 level=0$"
 	return buf
 }
 
diff --git a/test/escape_closure.go b/test/escape_closure.go
index 9152319fe045ba025ea32298fe8dff9c6c604dad..bd6c025476ee8a8ddaff4933b715aa9bf999f2c8 100644
--- a/test/escape_closure.go
+++ b/test/escape_closure.go
@@ -44,7 +44,7 @@ func ClosureCallArgs3() {
 
 func ClosureCallArgs4() {
 	x := 0
-	_ = func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape"
+	_ = func(p *int) *int { // ERROR "leaking param: p to result ~r0" "func literal does not escape"
 		return p
 	}(&x)
 }
@@ -111,7 +111,7 @@ func ClosureCallArgs11() {
 
 func ClosureCallArgs12() {
 	x := 0
-	defer func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape"
+	defer func(p *int) *int { // ERROR "leaking param: p to result ~r0" "func literal does not escape"
 		return p
 	}(&x)
 }
@@ -126,7 +126,7 @@ func ClosureCallArgs13() {
 func ClosureCallArgs14() {
 	x := 0
 	p := &x
-	_ = func(p **int) *int { // ERROR "leaking param: p to result ~r1 level=1" "func literal does not escape"
+	_ = func(p **int) *int { // ERROR "leaking param: p to result ~r0 level=1" "func literal does not escape"
 		return *p
 	}(&p)
 }
@@ -145,7 +145,7 @@ func ClosureLeak1(s string) string { // ERROR "s does not escape"
 }
 
 // See #14409 -- returning part of captured var leaks it.
-func ClosureLeak1a(a ...string) string { // ERROR "leaking param: a to result ~r1 level=1$"
+func ClosureLeak1a(a ...string) string { // ERROR "leaking param: a to result ~r0 level=1$"
 	return func() string { // ERROR "func literal does not escape"
 		return a[0]
 	}()
diff --git a/test/escape_goto.go b/test/escape_goto.go
index f024a9afe378b256bf51cb0c018b81c23cca19c9..90da5a2151297082b9163b998bae1830c0e36db5 100644
--- a/test/escape_goto.go
+++ b/test/escape_goto.go
@@ -10,7 +10,7 @@ package escape
 
 var x bool
 
-func _() {
+func f1() {
 	var p *int
 loop:
 	if x {
@@ -22,7 +22,7 @@ loop:
 	_ = p
 }
 
-func _() {
+func f2() {
 	var p *int
 	if x {
 	loop:
@@ -33,7 +33,7 @@ func _() {
 	_ = p
 }
 
-func _() {
+func f3() {
 	var p *int
 	if x {
 	loop:
diff --git a/test/escape_param.go b/test/escape_param.go
index dc93f689cf9fbd8e17a52097fbe95f244c525ddb..b630bae88fcd9b357c442609d07d3495aee0aec8 100644
--- a/test/escape_param.go
+++ b/test/escape_param.go
@@ -16,7 +16,7 @@ func zero() int { return 0 }
 var sink interface{}
 
 // in -> out
-func param0(p *int) *int { // ERROR "leaking param: p to result ~r1"
+func param0(p *int) *int { // ERROR "leaking param: p to result ~r0"
 	return p
 }
 
@@ -31,7 +31,7 @@ func caller0b() {
 }
 
 // in, in -> out, out
-func param1(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r2" "leaking param: p2 to result ~r3"
+func param1(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r0" "leaking param: p2 to result ~r1"
 	return p1, p2
 }
 
@@ -222,7 +222,7 @@ func caller8() {
 }
 
 // *in -> out
-func param9(p ***int) **int { // ERROR "leaking param: p to result ~r1 level=1"
+func param9(p ***int) **int { // ERROR "leaking param: p to result ~r0 level=1"
 	return *p
 }
 
@@ -241,7 +241,7 @@ func caller9b() {
 }
 
 // **in -> out
-func param10(p ***int) *int { // ERROR "leaking param: p to result ~r1 level=2"
+func param10(p ***int) *int { // ERROR "leaking param: p to result ~r0 level=2"
 	return **p
 }
 
@@ -436,6 +436,6 @@ func param14a(x [4]*int) interface{} { // ERROR "leaking param: x$"
 
 // Convert to a direct interface, does not need an allocation.
 // So x only leaks to result.
-func param14b(x *int) interface{} { // ERROR "leaking param: x to result ~r1 level=0"
+func param14b(x *int) interface{} { // ERROR "leaking param: x to result ~r0 level=0"
 	return x
 }
diff --git a/test/escape_runtime_atomic.go b/test/escape_runtime_atomic.go
index 62e8fede278b7f6022892c1cc39b89650c805f9b..30d1d0c0c1d89dc572873f037b20a90dd32003c0 100644
--- a/test/escape_runtime_atomic.go
+++ b/test/escape_runtime_atomic.go
@@ -13,8 +13,8 @@ import (
 	"unsafe"
 )
 
-// BAD: should always be "leaking param: addr to result ~r1 level=1$".
-func Loadp(addr unsafe.Pointer) unsafe.Pointer { // ERROR "leaking param: addr( to result ~r1 level=1)?$"
+// BAD: should always be "leaking param: addr to result ~r0 level=1$".
+func Loadp(addr unsafe.Pointer) unsafe.Pointer { // ERROR "leaking param: addr( to result ~r0 level=1)?$"
 	return atomic.Loadp(addr)
 }
 
diff --git a/test/escape_slice.go b/test/escape_slice.go
index d60414736c38d28c2527db8d21a1dba7be40983b..055b60be4173cfe5a2ef6ba55b147133e9e2a8eb 100644
--- a/test/escape_slice.go
+++ b/test/escape_slice.go
@@ -101,7 +101,7 @@ func slice11() {
 	_ = s
 }
 
-func slice12(x []int) *[1]int { // ERROR "leaking param: x to result ~r1 level=0$"
+func slice12(x []int) *[1]int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return (*[1]int)(x)
 }
 
@@ -110,7 +110,7 @@ func envForDir(dir string) []string { // ERROR "dir does not escape"
 	return mergeEnvLists([]string{"PWD=" + dir}, env) // ERROR ".PWD=. \+ dir escapes to heap" "\[\]string{...} does not escape"
 }
 
-func mergeEnvLists(in, out []string) []string { // ERROR "leaking param content: in" "leaking param content: out" "leaking param: out to result ~r2 level=0"
+func mergeEnvLists(in, out []string) []string { // ERROR "leaking param content: in" "leaking param content: out" "leaking param: out to result ~r0 level=0"
 NextVar:
 	for _, inkv := range in {
 		k := strings.SplitAfterN(inkv, "=", 2)[0]
diff --git a/test/escape_struct_return.go b/test/escape_struct_return.go
index 222ef8bc22a064cc8c2e507034028cd82e26a174..a42ae1e8c9b5270e610865554af7477ac95ab6be 100644
--- a/test/escape_struct_return.go
+++ b/test/escape_struct_return.go
@@ -15,11 +15,11 @@ type U struct {
 	_spp **string
 }
 
-func A(sp *string, spp **string) U { // ERROR "leaking param: sp to result ~r2 level=0$" "leaking param: spp to result ~r2 level=0$"
+func A(sp *string, spp **string) U { // ERROR "leaking param: sp to result ~r0 level=0$" "leaking param: spp to result ~r0 level=0$"
 	return U{sp, spp}
 }
 
-func B(spp **string) U { // ERROR "leaking param: spp to result ~r1 level=0$"
+func B(spp **string) U { // ERROR "leaking param: spp to result ~r0 level=0$"
 	return U{*spp, spp}
 }
 
diff --git a/test/escape_unsafe.go b/test/escape_unsafe.go
index b34beacccb5992f208b9b2789dd8c8b32c7a6086..cec6674a142374c7c9f6d9c867048f475d866ff2 100644
--- a/test/escape_unsafe.go
+++ b/test/escape_unsafe.go
@@ -15,7 +15,7 @@ import (
 
 // (1) Conversion of a *T1 to Pointer to *T2.
 
-func convert(p *float64) *uint64 { // ERROR "leaking param: p to result ~r1 level=0$"
+func convert(p *float64) *uint64 { // ERROR "leaking param: p to result ~r0 level=0$"
 	return (*uint64)(unsafe.Pointer(p))
 }
 
@@ -39,12 +39,12 @@ func arithMask() unsafe.Pointer {
 // (5) Conversion of the result of reflect.Value.Pointer or
 // reflect.Value.UnsafeAddr from uintptr to Pointer.
 
-// BAD: should be "leaking param: p to result ~r1 level=0$"
+// BAD: should be "leaking param: p to result ~r0 level=0$"
 func valuePointer(p *int) unsafe.Pointer { // ERROR "leaking param: p$"
 	return unsafe.Pointer(reflect.ValueOf(p).Pointer())
 }
 
-// BAD: should be "leaking param: p to result ~r1 level=0$"
+// BAD: should be "leaking param: p to result ~r0 level=0$"
 func valueUnsafeAddr(p *int) unsafe.Pointer { // ERROR "leaking param: p$"
 	return unsafe.Pointer(reflect.ValueOf(p).Elem().UnsafeAddr())
 }
@@ -52,11 +52,11 @@ func valueUnsafeAddr(p *int) unsafe.Pointer { // ERROR "leaking param: p$"
 // (6) Conversion of a reflect.SliceHeader or reflect.StringHeader
 // Data field to or from Pointer.
 
-func fromSliceData(s []int) unsafe.Pointer { // ERROR "leaking param: s to result ~r1 level=0$"
+func fromSliceData(s []int) unsafe.Pointer { // ERROR "leaking param: s to result ~r0 level=0$"
 	return unsafe.Pointer((*reflect.SliceHeader)(unsafe.Pointer(&s)).Data)
 }
 
-func fromStringData(s string) unsafe.Pointer { // ERROR "leaking param: s to result ~r1 level=0$"
+func fromStringData(s string) unsafe.Pointer { // ERROR "leaking param: s to result ~r0 level=0$"
 	return unsafe.Pointer((*reflect.StringHeader)(unsafe.Pointer(&s)).Data)
 }
 
diff --git a/test/fixedbugs/bug195.go b/test/fixedbugs/bug195.go
index 94f61fff7f1cb0a2b030b6ba7273b12e7f7b47b4..6d8578d6cb06049eaf2bdc115f0fae0832110394 100644
--- a/test/fixedbugs/bug195.go
+++ b/test/fixedbugs/bug195.go
@@ -1,4 +1,4 @@
-// errorcheck
+// errorcheck -lang=go1.17
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/bug248.dir/bug2.go b/test/fixedbugs/bug248.dir/bug2.go
index c0fdecfdb7b1e2a05abfccb67bea8e85ada95b2e..92a7974679eae10349fe8f4f7817cbf39fbf28dd 100644
--- a/test/fixedbugs/bug248.dir/bug2.go
+++ b/test/fixedbugs/bug248.dir/bug2.go
@@ -50,8 +50,8 @@ var p0i2 p1.I = t0(0) // ERROR "does not implement|incompatible"
 func foobar() {
 	// check that cannot assign one to the other,
 	// but can convert.
-	v0 = v1 // ERROR "assign"
-	v1 = v0 // ERROR "assign"
+	v0 = v1 // ERROR "assign|cannot use"
+	v1 = v0 // ERROR "assign|cannot use"
 
 	v0 = p0.T(v1)
 	v1 = p1.T(v0)
diff --git a/test/fixedbugs/bug267.go b/test/fixedbugs/bug267.go
index cf8bf841f8b1da65e102fab82c413a54b868bb1b..b61216a9d5a93fe746d09f93d43b142c8d91e87f 100644
--- a/test/fixedbugs/bug267.go
+++ b/test/fixedbugs/bug267.go
@@ -10,7 +10,7 @@ type T []int
 
 var a []bool
 
-func _() {
+func f1() {
 	if a[T{42}[0]] {
 	}
 	// if (a[T{42}[0]]) {}  // this compiles
diff --git a/test/fixedbugs/bug345.dir/main.go b/test/fixedbugs/bug345.dir/main.go
index b77a2fad5fba076e5c0e7ad8f3d87fcaccc057f3..a53d3e8586ed553a73d847d6b8493a95bcb9a513 100644
--- a/test/fixedbugs/bug345.dir/main.go
+++ b/test/fixedbugs/bug345.dir/main.go
@@ -23,7 +23,7 @@ func main() {
 	// main.go:27: cannot use &x (type *"io".SectionReader) as type *"/Users/rsc/g/go/test/fixedbugs/bug345.dir/io".SectionReader in function argument
 
 	var w io.Writer
-	bufio.NewWriter(w) // ERROR "[\w.]+[^.]/io|has incompatible type"
+	bufio.NewWriter(w) // ERROR "[\w.]+[^.]/io|has incompatible type|cannot use"
 	var x goio.SectionReader
-	io.SR(&x) // ERROR "[\w.]+[^.]/io|has incompatible type"
+	io.SR(&x) // ERROR "[\w.]+[^.]/io|has incompatible type|cannot use"
 }
diff --git a/test/fixedbugs/bug460.dir/b.go b/test/fixedbugs/bug460.dir/b.go
index ef646946cf187ab02ef5a993f93e4d8e268a8da5..5d388fc413f783de1aa93fe6c0aacab463b87e63 100644
--- a/test/fixedbugs/bug460.dir/b.go
+++ b/test/fixedbugs/bug460.dir/b.go
@@ -9,9 +9,9 @@ import "./a"
 var x a.Foo
 
 func main() {
-	x.int = 20    // ERROR "unexported field"
-	x.int8 = 20   // ERROR "unexported field"
-	x.error = nil // ERROR "unexported field"
-	x.rune = 'a'  // ERROR "unexported field"
-	x.byte = 20   // ERROR "unexported field"
+	x.int = 20    // ERROR "unexported field|undefined"
+	x.int8 = 20   // ERROR "unexported field|undefined"
+	x.error = nil // ERROR "unexported field|undefined"
+	x.rune = 'a'  // ERROR "unexported field|undefined"
+	x.byte = 20   // ERROR "unexported field|undefined"
 }
diff --git a/test/fixedbugs/bug514.go b/test/fixedbugs/bug514.go
new file mode 100644
index 0000000000000000000000000000000000000000..3fb7f32a3009cf662cae8c4c3b08bea83b978e67
--- /dev/null
+++ b/test/fixedbugs/bug514.go
@@ -0,0 +1,55 @@
+// run
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type iface interface {
+	Get() int
+}
+
+//go:notinheap
+type notInHeap struct {
+	i int
+}
+
+type myInt struct {
+	f *notInHeap
+}
+
+func (mi myInt) Get() int {
+	return int(mi.f.i)
+}
+
+type embed struct {
+	*myInt
+}
+
+var val = 1234
+
+var valNotInHeap = notInHeap{val}
+
+func main() {
+	i := val
+	check(i)
+	mi := myInt{f: &valNotInHeap}
+	check(mi.Get())
+	ifv := iface(mi)
+	check(ifv.Get())
+	ifv = iface(&mi)
+	check(ifv.Get())
+	em := embed{&mi}
+	check(em.Get())
+	ifv = em
+	check(ifv.Get())
+	ifv = &em
+	check(ifv.Get())
+}
+
+func check(v int) {
+	if v != val {
+		panic(v)
+	}
+}
diff --git a/test/fixedbugs/issue10441.go b/test/fixedbugs/issue10441.go
index 9bc4948b15b2881f703389d68e1288f396814608..7cd26d841b66d1573e3e7b2bb097d22f80a8d0be 100644
--- a/test/fixedbugs/issue10441.go
+++ b/test/fixedbugs/issue10441.go
@@ -1,4 +1,4 @@
-// build
+// compile
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue10975.go b/test/fixedbugs/issue10975.go
index 89ef23c1a86e555cb175daedb55c550b3c874015..876ea58ef97634a9d26154ecd1dd28cb87cc185e 100644
--- a/test/fixedbugs/issue10975.go
+++ b/test/fixedbugs/issue10975.go
@@ -1,4 +1,4 @@
-// errorcheck
+// errorcheck -lang=go1.17
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue11614.go b/test/fixedbugs/issue11614.go
index de15f9827ffb28d1c18166c762349d0834de0422..6ea463b7fe92ffbbe0ebfc5d7fe8500caacec2a7 100644
--- a/test/fixedbugs/issue11614.go
+++ b/test/fixedbugs/issue11614.go
@@ -1,4 +1,4 @@
-// errorcheck
+// errorcheck -lang=go1.17
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue12006.go b/test/fixedbugs/issue12006.go
index 0a2ef8dad04dbc76b3e09ec265ef8540f8dd2605..e878bc48e241e11befd77c30a2790c07a9d2058a 100644
--- a/test/fixedbugs/issue12006.go
+++ b/test/fixedbugs/issue12006.go
@@ -87,7 +87,7 @@ func TFooI() {
 	FooI(a, b, c) // ERROR "a escapes to heap" "b escapes to heap" "... argument does not escape"
 }
 
-func FooJ(args ...interface{}) *int32 { // ERROR "leaking param: args to result ~r1 level=1"
+func FooJ(args ...interface{}) *int32 { // ERROR "leaking param: args to result ~r0 level=1"
 	for i := 0; i < len(args); i++ {
 		switch x := args[i].(type) {
 		case nil:
@@ -123,7 +123,7 @@ type fakeSlice struct {
 	a *[4]interface{}
 }
 
-func FooK(args fakeSlice) *int32 { // ERROR "leaking param: args to result ~r1 level=1"
+func FooK(args fakeSlice) *int32 { // ERROR "leaking param: args to result ~r0 level=1"
 	for i := 0; i < args.l; i++ {
 		switch x := (*args.a)[i].(type) {
 		case nil:
@@ -148,7 +148,7 @@ func TFooK2() {
 	isink = FooK(fs)
 }
 
-func FooL(args []interface{}) *int32 { // ERROR "leaking param: args to result ~r1 level=1"
+func FooL(args []interface{}) *int32 { // ERROR "leaking param: args to result ~r0 level=1"
 	for i := 0; i < len(args); i++ {
 		switch x := args[i].(type) {
 		case nil:
diff --git a/test/fixedbugs/issue12588.go b/test/fixedbugs/issue12588.go
index 950ef36e206c76e9c83e6d6503462f19ed1f73ae..dc8111198c49d24e87ebe8b1bcd8e473bcea3b3a 100644
--- a/test/fixedbugs/issue12588.go
+++ b/test/fixedbugs/issue12588.go
@@ -35,7 +35,7 @@ func g(a *A) int { // ERROR "a does not escape"
 	return 0
 }
 
-func h(a *B) *uint64 { // ERROR "leaking param: a to result ~r1 level=1"
+func h(a *B) *uint64 { // ERROR "leaking param: a to result ~r0 level=1"
 	for i, x := range &a.b {
 		if i == 0 {
 			return x
@@ -44,7 +44,7 @@ func h(a *B) *uint64 { // ERROR "leaking param: a to result ~r1 level=1"
 	return nil
 }
 
-func h2(a *B) *uint64 { // ERROR "leaking param: a to result ~r1 level=1"
+func h2(a *B) *uint64 { // ERROR "leaking param: a to result ~r0 level=1"
 	p := &a.b
 	for i, x := range p {
 		if i == 0 {
@@ -55,7 +55,7 @@ func h2(a *B) *uint64 { // ERROR "leaking param: a to result ~r1 level=1"
 }
 
 // Seems like below should be level=1, not 0.
-func k(a B) *uint64 { // ERROR "leaking param: a to result ~r1 level=0"
+func k(a B) *uint64 { // ERROR "leaking param: a to result ~r0 level=0"
 	for i, x := range &a.b {
 		if i == 0 {
 			return x
diff --git a/test/fixedbugs/issue14652.go b/test/fixedbugs/issue14652.go
index d53b412668314822423427c98711bb0731041b83..14a223977b4a1ddd1952d063f97e6bcd27517bc8 100644
--- a/test/fixedbugs/issue14652.go
+++ b/test/fixedbugs/issue14652.go
@@ -6,4 +6,4 @@
 
 package p
 
-var x any // ERROR "undefined: any|undefined type .*any.*"
+var x any // ERROR "undefined: any|undefined type .*any.*|cannot use any outside constraint position"
diff --git a/test/fixedbugs/issue14999.go b/test/fixedbugs/issue14999.go
index b648441fc29779b1f202a20b9056da176f32e59f..a25a50e519a5ea75d90fd263ac11328b3aef09eb 100644
--- a/test/fixedbugs/issue14999.go
+++ b/test/fixedbugs/issue14999.go
@@ -7,11 +7,11 @@
 package p
 
 func f(x int) func(int) int {
-	return func(y int) int { return x + y } // ERROR "heap-allocated closure, not allowed in runtime"
+	return func(y int) int { return x + y } // ERROR "heap-allocated closure f\.func1, not allowed in runtime"
 }
 
 func g(x int) func(int) int { // ERROR "x escapes to heap, not allowed in runtime"
-	return func(y int) int { // ERROR "heap-allocated closure, not allowed in runtime"
+	return func(y int) int { // ERROR "heap-allocated closure g\.func1, not allowed in runtime"
 		x += y
 		return x + y
 	}
diff --git a/test/fixedbugs/issue20250.go b/test/fixedbugs/issue20250.go
index 1a513bea56df1f916dfe77d99b0f8f72733a6d28..aed7b25d1bff4b30cb591c70afe96eda623afd0e 100644
--- a/test/fixedbugs/issue20250.go
+++ b/test/fixedbugs/issue20250.go
@@ -17,7 +17,7 @@ type T struct {
 func f(a T) { // ERROR "live at entry to f: a"
 	var e interface{} // ERROR "stack object e interface \{\}$"
 	func() {          // ERROR "live at entry to f.func1: a &e"
-		e = a.s // ERROR "live at call to convT2E: &e" "stack object a T$"
+		e = a.s // ERROR "live at call to convT: &e" "stack object a T$"
 	}()
 	// Before the fix, both a and e were live at the previous line.
 	_ = e
diff --git a/test/fixedbugs/issue22076.go b/test/fixedbugs/issue22076.go
index 5d628b96bd3a08b574c1a156e72565c5f1115745..b383a674e2f66b02d2bd53ca6306f23f92db45b1 100644
--- a/test/fixedbugs/issue22076.go
+++ b/test/fixedbugs/issue22076.go
@@ -13,12 +13,12 @@ import . "bytes"
 
 var _ Reader // use "bytes" import
 
-func _() {
+func f1() {
 	Buffer := 0
 	_ = Buffer
 }
 
-func _() {
+func f2() {
 	for Buffer := range []int{} {
 		_ = Buffer
 	}
diff --git a/test/fixedbugs/issue24651a.go b/test/fixedbugs/issue24651a.go
index 6c7bf3090877fcae177cebe06c2462265be27ab5..1bfe8ac1ce8243b77f1b4374d4c92b2776fc980f 100644
--- a/test/fixedbugs/issue24651a.go
+++ b/test/fixedbugs/issue24651a.go
@@ -21,5 +21,5 @@ var x = 5
 //go:noinline Provide a clean, constant reason for not inlining main
 func main() { // ERROR "cannot inline main: marked go:noinline$"
 	println("Foo(", x, ")=", Foo(x))
-	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
+	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar"
 }
diff --git a/test/fixedbugs/issue24651b.go b/test/fixedbugs/issue24651b.go
index aa88a6787b96bfd7db8f8231dc7f4dccdce4ce50..2af54fc4b53e52bf92480997bb94ee0e17e5cb48 100644
--- a/test/fixedbugs/issue24651b.go
+++ b/test/fixedbugs/issue24651b.go
@@ -19,6 +19,6 @@ var x = 5
 
 //go:noinline Provide a clean, constant reason for not inlining main
 func main() { // ERROR "cannot inline main: marked go:noinline$"
-	println("Foo(", x, ")=", Foo(x)) // ERROR "inlining call to Foo func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
-	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
+	println("Foo(", x, ")=", Foo(x)) // ERROR "inlining call to Foo"
+	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar"
 }
diff --git a/test/fixedbugs/issue26163.go b/test/fixedbugs/issue26163.go
index d141a2797d60f15e5047d756d063fb3102305e75..3f3d77859def812a43f934347592b7013c87836e 100644
--- a/test/fixedbugs/issue26163.go
+++ b/test/fixedbugs/issue26163.go
@@ -1,4 +1,4 @@
-// compile -N -d=softfloat -goexperiment noregabiargs
+// compile -N -d=softfloat
 
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue27557.go b/test/fixedbugs/issue27557.go
index e35ab5a1690fb03dc01faff01b56a1302ad1f5e6..f609b27faa5e12ddc4e03218c36e5916d4c43271 100644
--- a/test/fixedbugs/issue27557.go
+++ b/test/fixedbugs/issue27557.go
@@ -8,19 +8,19 @@ package p
 
 var sink interface{}
 
-func _() {
+func f1() {
 	var t T
 	f := t.noescape // ERROR "t.noescape does not escape"
 	f()
 }
 
-func _() {
+func f2() {
 	var t T       // ERROR "moved to heap"
 	f := t.escape // ERROR "t.escape does not escape"
 	f()
 }
 
-func _() {
+func f3() {
 	var t T        // ERROR "moved to heap"
 	f := t.returns // ERROR "t.returns does not escape"
 	sink = f()
diff --git a/test/fixedbugs/issue28688.go b/test/fixedbugs/issue28688.go
index 8ef0802812c6824a6b0e74f070115a843921738a..0d2000e149872f2d0d5496e64123bbcd0f491d8f 100644
--- a/test/fixedbugs/issue28688.go
+++ b/test/fixedbugs/issue28688.go
@@ -1,4 +1,4 @@
-// run -gcflags=-d=softfloat -goexperiment noregabiargs
+// run -gcflags=-d=softfloat
 
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue30862.dir/a.go b/test/fixedbugs/issue30862.dir/a/a.go
similarity index 100%
rename from test/fixedbugs/issue30862.dir/a.go
rename to test/fixedbugs/issue30862.dir/a/a.go
diff --git a/test/fixedbugs/issue30862.dir/b.go b/test/fixedbugs/issue30862.dir/b/b.go
similarity index 95%
rename from test/fixedbugs/issue30862.dir/b.go
rename to test/fixedbugs/issue30862.dir/b/b.go
index 3e501bb8dcbdc7c853f614fba5b360d50d87c044..230221d5036248af1c1c80415a675cc55f8ee16e 100644
--- a/test/fixedbugs/issue30862.dir/b.go
+++ b/test/fixedbugs/issue30862.dir/b/b.go
@@ -4,7 +4,7 @@
 
 package b
 
-import "./a"
+import "issue30862.dir/a"
 
 type EmbedImported struct {
 	a.NoitfStruct
diff --git a/test/fixedbugs/issue30862.dir/main.go b/test/fixedbugs/issue30862.dir/main.go
index 80db0e13a84753fda986ebfc40c0bd3bdcda44d4..1489c5a34255fbb01b93700bd1150d90de93920a 100644
--- a/test/fixedbugs/issue30862.dir/main.go
+++ b/test/fixedbugs/issue30862.dir/main.go
@@ -8,7 +8,7 @@ import (
 	"fmt"
 	"os"
 
-	"./b"
+	"issue30862.dir/b"
 )
 
 // Test case for issue 30862.
diff --git a/test/fixedbugs/issue30862.go b/test/fixedbugs/issue30862.go
index ba122cc3c8b805b931660d3c39c36db48ddb2e9c..acac71e2ccabd4d85c16b9e38265f93f03af0652 100644
--- a/test/fixedbugs/issue30862.go
+++ b/test/fixedbugs/issue30862.go
@@ -1,4 +1,4 @@
-// rundir
+// runindir -goexperiment fieldtrack
 
 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -9,6 +9,4 @@
 // is set when building it, whereas gccgo has field tracking
 // enabled by default (hence the build tag below).
 
-// +build gccgo
-
 package ignored
diff --git a/test/fixedbugs/issue30898.go b/test/fixedbugs/issue30898.go
index b6376d3f9e7a7fe0ae223db0c869bd9a0dc6c9fa..c7f6f2d3712b3cf507cbc8d1338a4604d99e5c47 100644
--- a/test/fixedbugs/issue30898.go
+++ b/test/fixedbugs/issue30898.go
@@ -15,5 +15,5 @@ func debugf(format string, args ...interface{}) { // ERROR "can inline debugf" "
 
 func bar() { // ERROR "can inline bar"
 	value := 10
-	debugf("value is %d", value) // ERROR "inlining call to debugf" "value does not escape" "\[\]interface {}{...} does not escape"
+	debugf("value is %d", value) // ERROR "inlining call to debugf" "value does not escape" "\.\.\. argument does not escape"
 }
diff --git a/test/fixedbugs/issue31573.go b/test/fixedbugs/issue31573.go
index 005910e00d16b8b6b8727e42163457cbadefcf9b..eaab5634316916a239b1c71d9ea35dafe42533e6 100644
--- a/test/fixedbugs/issue31573.go
+++ b/test/fixedbugs/issue31573.go
@@ -19,31 +19,31 @@ func g() {
 	defer f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) does not escape$"
 
 	go f()
-	go f(new(int))           // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
-	go f(new(int), new(int)) // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
+	go f(new(int))           // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
+	go f(new(int), new(int)) // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
 
 	go f(nil...)
-	go f([]*int{}...)                   // ERROR "\[\]\*int{} escapes to heap$"
-	go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
-	go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
+	go f([]*int{}...)                   // ERROR "\[\]\*int{} does not escape$"
+	go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
+	go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
 
 	for {
 		defer f()
-		defer f(new(int))           // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
-		defer f(new(int), new(int)) // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
+		defer f(new(int))           // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
+		defer f(new(int), new(int)) // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
 
 		defer f(nil...)
-		defer f([]*int{}...)                   // ERROR "\[\]\*int{} escapes to heap$"
-		defer f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
-		defer f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
+		defer f([]*int{}...)                   // ERROR "\[\]\*int{} does not escape$"
+		defer f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
+		defer f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
 
 		go f()
-		go f(new(int))           // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
-		go f(new(int), new(int)) // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
+		go f(new(int))           // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
+		go f(new(int), new(int)) // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
 
 		go f(nil...)
-		go f([]*int{}...)                   // ERROR "\[\]\*int{} escapes to heap$"
-		go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
-		go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
+		go f([]*int{}...)                   // ERROR "\[\]\*int{} does not escape$"
+		go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
+		go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
 	}
 }
diff --git a/test/fixedbugs/issue41500.go b/test/fixedbugs/issue41500.go
index 3ec23a0dfe08ba973230b633a1e59058127d6e35..b0ae7cfd59f575326239970c1e48978078134f3a 100644
--- a/test/fixedbugs/issue41500.go
+++ b/test/fixedbugs/issue41500.go
@@ -13,8 +13,8 @@ type s struct {
 func f() {
 	var x *s
 
-	_ = x == nil || len(x.slice) // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|cannot convert"
-	_ = len(x.slice) || x == nil // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|cannot convert"
-	_ = x == nil && len(x.slice) // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|cannot convert"
-	_ = len(x.slice) && x == nil // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|cannot convert"
+	_ = x == nil || len(x.slice) // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|mismatched types untyped bool and int"
+	_ = len(x.slice) || x == nil // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|mismatched types int and untyped bool"
+	_ = x == nil && len(x.slice) // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|mismatched types untyped bool and int"
+	_ = len(x.slice) && x == nil // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|mismatched types int and untyped bool"
 }
diff --git a/test/fixedbugs/issue42284.dir/a.go b/test/fixedbugs/issue42284.dir/a.go
index ffe9310be35b645165ab7b329f168703b9d9867e..f7fd80bd2070bb5a8e7f4e0074970d2bf16399f3 100644
--- a/test/fixedbugs/issue42284.dir/a.go
+++ b/test/fixedbugs/issue42284.dir/a.go
@@ -13,7 +13,7 @@ func E() I { // ERROR "can inline E"
 	return T(0) // ERROR "T\(0\) escapes to heap"
 }
 
-func F(i I) I { // ERROR "can inline F" "leaking param: i to result ~r1 level=0"
+func F(i I) I { // ERROR "can inline F" "leaking param: i to result ~r0 level=0"
 	i = nil
 	return i
 }
diff --git a/test/fixedbugs/issue43762.go b/test/fixedbugs/issue43762.go
index 9f7682ad6ac50b013a0e513b25bf55e9395a9c9b..bf950c8f524d58266ccdaaefdb1cf4bf21bea7e0 100644
--- a/test/fixedbugs/issue43762.go
+++ b/test/fixedbugs/issue43762.go
@@ -6,6 +6,6 @@
 
 package p
 
-var _ = true == '\\' // ERROR "invalid operation: true == '\\\\'|cannot convert true"
-var _ = true == '\'' // ERROR "invalid operation: true == '\\''|cannot convert true"
-var _ = true == '\n' // ERROR "invalid operation: true == '\\n'|cannot convert true"
+var _ = true == '\\' // ERROR "invalid operation: (cannot compare true)|(true) == '\\\\' \(mismatched types untyped bool and untyped rune\)"
+var _ = true == '\'' // ERROR "invalid operation: (cannot compare true)|(true) == '\\'' \(mismatched types untyped bool and untyped rune\)"
+var _ = true == '\n' // ERROR "invalid operation: (cannot compare true)|(true) == '\\n' \(mismatched types untyped bool and untyped rune\)"
diff --git a/test/fixedbugs/issue44432.go b/test/fixedbugs/issue44432.go
index c5fb67e0d782b6a5acceca35291c8add42705ad5..eec53f30008e3d889aeac58fcd57730b7b1e30eb 100644
--- a/test/fixedbugs/issue44432.go
+++ b/test/fixedbugs/issue44432.go
@@ -8,6 +8,6 @@ package p
 
 var m = map[string]int{
 	"a": 1,
-	1:   1, // ERROR "cannot use 1.*as type string in map key"
-	2:   2, // ERROR "cannot use 2.*as type string in map key"
+	1:   1, // ERROR "cannot use 1.*as.*string.*in map"
+	2:   2, // ERROR "cannot use 2.*as.*string.*in map"
 }
diff --git a/test/fixedbugs/issue45258.go b/test/fixedbugs/issue45258.go
index f4d6fccf17d85d6a6aa8dccae6272dbc782fdfe9..b026c0c8f539c4a62ee7b74f9f7431bf5ff08047 100644
--- a/test/fixedbugs/issue45258.go
+++ b/test/fixedbugs/issue45258.go
@@ -22,7 +22,7 @@ func (r *impl) Foo() Barer {
 
 func (r *impl) Bar() {}
 
-func _() {
+func f1() {
 	var r Fooer = &impl{}
 	r.Foo().Bar()
 }
diff --git a/test/fixedbugs/issue46556.go b/test/fixedbugs/issue46556.go
new file mode 100644
index 0000000000000000000000000000000000000000..b159f61b0c5034309d27288ab9a425834bb6ea1d
--- /dev/null
+++ b/test/fixedbugs/issue46556.go
@@ -0,0 +1,16 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type A = interface{}
+type B interface{}
+
+// Test that embedding both anonymous and defined types is supported.
+type C interface {
+	A
+	B
+}
diff --git a/test/fixedbugs/issue46749.go b/test/fixedbugs/issue46749.go
index 63ed19795e5fc7ccde39515d9a34ac1fed0a63de..faf1f884a6b40cde9d83a606b77a25314091315f 100644
--- a/test/fixedbugs/issue46749.go
+++ b/test/fixedbugs/issue46749.go
@@ -14,13 +14,13 @@ var iface interface{}
 var (
 	_ = "" + b   // ERROR "invalid operation.*mismatched types.*untyped string and bool"
 	_ = "" + i   // ERROR "invalid operation.*mismatched types.*untyped string and int"
-	_ = "" + nil // ERROR "invalid operation.*mismatched types.*untyped string and nil"
+	_ = "" + nil // ERROR "invalid operation.*mismatched types.*untyped string and nil|(untyped nil)"
 )
 
 var (
 	_ = s + false // ERROR "invalid operation.*mismatched types.*string and untyped bool"
 	_ = s + 1     // ERROR "invalid operation.*mismatched types.*string and untyped int"
-	_ = s + nil   // ERROR "invalid operation.*mismatched types.*string and nil"
+	_ = s + nil   // ERROR "invalid operation.*mismatched types.*string and nil|(untyped nil)"
 )
 
 var (
@@ -31,7 +31,7 @@ var (
 var (
 	_ = b + 1         // ERROR "invalid operation.*mismatched types.*bool and untyped int"
 	_ = i + false     // ERROR "invalid operation.*mismatched types.*int and untyped bool"
-	_ = iface + 1     // ERROR "invalid operation.*mismatched types.*interface {} and int"
-	_ = iface + 1.0   // ERROR "invalid operation.*mismatched types.*interface {} and float64"
-	_ = iface + false // ERROR "invalid operation.*mismatched types.*interface {} and bool"
+	_ = iface + 1     // ERROR "invalid operation.*mismatched types.*interface *{} and int"
+	_ = iface + 1.0   // ERROR "invalid operation.*mismatched types.*interface *{} and float64"
+	_ = iface + false // ERROR "invalid operation.*mismatched types.*interface *{} and bool"
 )
diff --git a/test/fixedbugs/issue46903.go b/test/fixedbugs/issue46903.go
new file mode 100644
index 0000000000000000000000000000000000000000..3237a583d547361117b1b82aa6df2ca0a66a5508
--- /dev/null
+++ b/test/fixedbugs/issue46903.go
@@ -0,0 +1,32 @@
+// run
+//go:build goexperiment.unified
+// +build goexperiment.unified
+
+// TODO(mdempsky): Enable test unconditionally. This test should pass
+// for non-unified mode too.
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+//go:notinheap
+type A struct{ B }
+type B struct{ x byte }
+type I interface{ M() *B }
+
+func (p *B) M() *B { return p }
+
+var (
+	a A
+	i I = &a
+)
+
+func main() {
+	got, want := i.M(), &a.B
+	if got != want {
+		println(got, "!=", want)
+		panic("FAIL")
+	}
+}
diff --git a/test/fixedbugs/issue47068.dir/a.go b/test/fixedbugs/issue47068.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..f7b780d459d274140e13bffda0ec26a8a3a057b1
--- /dev/null
+++ b/test/fixedbugs/issue47068.dir/a.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func A() {
+	var m map[int]int = map[int]int{
+		0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0,
+		10: 0, 11: 0, 12: 0, 13: 0, 14: 0, 15: 0, 16: 0, 17: 0, 18: 0, 19: 0,
+		20: 0, 21: 0, 22: 0, 23: 0, 24: 0, 25: 0, 26: 0, 27: 0, 28: 0, 29: 0}
+	if len(m) != 30 {
+		panic("unepexted map length")
+	}
+}
diff --git a/test/fixedbugs/issue47068.dir/b.go b/test/fixedbugs/issue47068.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..d341a4a395005cb9b5411ece09004ee9c2571118
--- /dev/null
+++ b/test/fixedbugs/issue47068.dir/b.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "reflect"
+
+func B() {
+	t1 := reflect.TypeOf([30]int{})
+	t2 := reflect.TypeOf(new([30]int)).Elem()
+	if t1 != t2 {
+		panic("[30]int types do not match")
+	}
+}
diff --git a/test/fixedbugs/issue47068.dir/main.go b/test/fixedbugs/issue47068.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..16ef5b780b9f8d4648e04aaf09958d908f3f2946
--- /dev/null
+++ b/test/fixedbugs/issue47068.dir/main.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"b"
+)
+
+func main() {
+	a.A()
+	b.B()
+}
diff --git a/src/internal/cpu/cpu_386.go b/test/fixedbugs/issue47068.go
similarity index 54%
rename from src/internal/cpu/cpu_386.go
rename to test/fixedbugs/issue47068.go
index 561c81f8083518a397202083d53cf4f797ce8b9c..af6f1341729458e04aba9a8a7110ec999540bc2a 100644
--- a/src/internal/cpu/cpu_386.go
+++ b/test/fixedbugs/issue47068.go
@@ -1,7 +1,7 @@
-// Copyright 2018 The Go Authors. All rights reserved.
+// rundir
+
+// Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package cpu
-
-const GOARCH = "386"
+package ignored
diff --git a/test/fixedbugs/issue47131.dir/a.go b/test/fixedbugs/issue47131.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..6e798d1d0c8e2dd7370416750e2fc5764346a9e9
--- /dev/null
+++ b/test/fixedbugs/issue47131.dir/a.go
@@ -0,0 +1,13 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type MyInt int
+
+type MyIntAlias = MyInt
+
+func (mia *MyIntAlias) Get() int {
+	return int(*mia)
+}
diff --git a/test/fixedbugs/issue47131.dir/b.go b/test/fixedbugs/issue47131.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..c658127ca9d53c2495f12690437e095401f9a4c2
--- /dev/null
+++ b/test/fixedbugs/issue47131.dir/b.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "./a"
+
+func F2() int {
+	var mia a.MyIntAlias
+	return mia.Get()
+}
diff --git a/src/internal/cpu/cpu_amd64.go b/test/fixedbugs/issue47131.go
similarity index 54%
rename from src/internal/cpu/cpu_amd64.go
rename to test/fixedbugs/issue47131.go
index 9b0015362d53fba083efefb8a8f0c3b7e42a4a9c..b83fbd7af16a576c16e0fc73b84f1ca0f618b756 100644
--- a/src/internal/cpu/cpu_amd64.go
+++ b/test/fixedbugs/issue47131.go
@@ -1,7 +1,7 @@
-// Copyright 2018 The Go Authors. All rights reserved.
+// compiledir
+
+// Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package cpu
-
-const GOARCH = "amd64"
+package ignored
diff --git a/test/fixedbugs/issue47227.go b/test/fixedbugs/issue47227.go
new file mode 100644
index 0000000000000000000000000000000000000000..a14efc9a689410ccfe66ac2c94ee120524640215
--- /dev/null
+++ b/test/fixedbugs/issue47227.go
@@ -0,0 +1,23 @@
+// run fake-arg-to-force-use-of-go-run
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build cgo
+// +build cgo
+
+package main
+
+// void f(int *p) { *p = 0x12345678; }
+import "C"
+
+func main() {
+	var x C.int
+	func() {
+		defer C.f(&x)
+	}()
+	if x != 0x12345678 {
+		panic("FAIL")
+	}
+}
diff --git a/test/fixedbugs/issue47712.go b/test/fixedbugs/issue47712.go
new file mode 100644
index 0000000000000000000000000000000000000000..81a2681592e92cc1dfee1ef94018624b9040e5e0
--- /dev/null
+++ b/test/fixedbugs/issue47712.go
@@ -0,0 +1,23 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f() {
+	if false {
+		defer func() {
+			_ = recover()
+		}()
+	}
+}
+
+func g() {
+	for false {
+		defer func() {
+			_ = recover()
+		}()
+	}
+}
diff --git a/test/fixedbugs/issue47928.go b/test/fixedbugs/issue47928.go
new file mode 100644
index 0000000000000000000000000000000000000000..3bc291dd3f1b4ea8746b7e52155467b18eb5a562
--- /dev/null
+++ b/test/fixedbugs/issue47928.go
@@ -0,0 +1,21 @@
+// run -goexperiment fieldtrack
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func main() {
+	var i interface{} = new(T)
+	if _, ok := i.(interface{ Bad() }); ok {
+		panic("FAIL")
+	}
+}
+
+type T struct{ U }
+
+type U struct{}
+
+//go:nointerface
+func (*U) Bad() {}
diff --git a/test/fixedbugs/issue4909b.go b/test/fixedbugs/issue4909b.go
index 0f594e3db67be58142ad8ca6a89ba04f972b3f09..7d7922701a20ce8a1c51dc0bf89023e9901770b4 100644
--- a/test/fixedbugs/issue4909b.go
+++ b/test/fixedbugs/issue4909b.go
@@ -73,7 +73,7 @@ func writeDot(ns ...int) {
 		}
 		fmt.Print(")")
 		if isIndirect {
-			fmt.Print(` // ERROR "indirection"`)
+			fmt.Print(` // ERROR "indirection|embedded via a pointer"`)
 		}
 		fmt.Print("\n")
 	}
diff --git a/test/fixedbugs/issue8042.go b/test/fixedbugs/issue8042.go
index 5639f97bb89b946717857925e5ff1624782c2980..be15ef06cd2fd03554cf19292277d2af5f9559eb 100644
--- a/test/fixedbugs/issue8042.go
+++ b/test/fixedbugs/issue8042.go
@@ -9,7 +9,7 @@
 
 package p
 
-func _() {
+func f1() {
 	goto L1
 	const x = 0
 L1:
@@ -18,7 +18,7 @@ L1:
 L2:
 }
 
-func _() {
+func f2() {
 	{
 		goto L1
 	}
@@ -31,7 +31,7 @@ L1:
 L2:
 }
 
-func _(d int) {
+func f3(d int) {
 	if d > 0 {
 		goto L1
 	} else {
diff --git a/test/fixedbugs/issue8761.go b/test/fixedbugs/issue8761.go
index 7f458f7f03378d7343dc1216f14a43d3a00dca3a..e5130e1ff5ca92edad3f7d950093be9ced6d00b0 100644
--- a/test/fixedbugs/issue8761.go
+++ b/test/fixedbugs/issue8761.go
@@ -10,17 +10,17 @@
 
 package p
 
-func _() {
+func f1() {
 	type C chan int
 	_ = [1][]C{[]C{make(chan int)}}
 }
 
-func _() {
+func f2() {
 	type C interface{}
 	_ = [1][]C{[]C{recover()}}
 }
 
-func _() {
+func f3() {
 	type C *int
 	_ = [1][]C{[]C{new(int)}}
 }
diff --git a/test/inline.go b/test/inline.go
index 472a941dca3a66a47b0b2a6679bb921bc1cbc8b3..a73c0ba7b1da0f185268f35d76801252744a6d25 100644
--- a/test/inline.go
+++ b/test/inline.go
@@ -1,4 +1,4 @@
-// errorcheck -0 -m -d=inlfuncswithclosures=1
+// errorcheckwithauto -0 -m -d=inlfuncswithclosures=1
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -49,7 +49,7 @@ func j(x int) int { // ERROR "can inline j"
 	}
 }
 
-func _() int { // ERROR "can inline _"
+func f2() int { // ERROR "can inline f2"
 	tmp1 := h
 	tmp2 := tmp1
 	return tmp2(0) // ERROR "inlining call to h"
@@ -167,8 +167,9 @@ func (T) meth(int, int) {} // ERROR "can inline T.meth"
 
 func k() (T, int, int) { return T{}, 0, 0 } // ERROR "can inline k"
 
-func _() { // ERROR "can inline _"
+func f3() { // ERROR "can inline f3"
 	T.meth(k()) // ERROR "inlining call to k" "inlining call to T.meth"
+	// ERRORAUTO "inlining call to T.meth"
 }
 
 func small1() { // ERROR "can inline small1"
@@ -232,12 +233,13 @@ Loop:
 // Issue #18493 - make sure we can do inlining of functions with a method value
 type T1 struct{}
 
-func (a T1) meth(val int) int { // ERROR "can inline T1.meth" "inlining call to T1.meth"
+func (a T1) meth(val int) int { // ERROR "can inline T1.meth"
 	return val + 5
 }
 
 func getMeth(t1 T1) func(int) int { // ERROR "can inline getMeth"
 	return t1.meth // ERROR "t1.meth escapes to heap"
+	// ERRORAUTO "inlining call to T1.meth"
 }
 
 func ii() { // ERROR "can inline ii"
diff --git a/test/inline_big.go b/test/inline_big.go
index 68e1101d3b0de921e9128f4d2b519e58748ce2ba..83672753f78a171bd224fa71705eb3e7dc4c2118 100644
--- a/test/inline_big.go
+++ b/test/inline_big.go
@@ -1023,7 +1023,7 @@ func f(a []int) int { // ERROR "cannot inline f:.*" "a does not escape"
 	a[997] = 0
 	a[998] = 0
 	a[999] = 0
-	x := small(a)  // ERROR "inlining call to small .*"
+	x := small(a)  // ERROR "inlining call to small"
 	y := medium(a) // The crux of this test: medium is not inlined.
 	return x + y
 }
diff --git a/test/inline_variadic.go b/test/inline_variadic.go
index 687048a1922d55ca42ac1c334bd1380978e4d499..49483d77f79934b9f4011da0705daba3faeb2a7b 100644
--- a/test/inline_variadic.go
+++ b/test/inline_variadic.go
@@ -14,6 +14,6 @@ func head(xs ...string) string { // ERROR "can inline head" "leaking param: xs t
 }
 
 func f() string { // ERROR "can inline f"
-	x := head("hello", "world") // ERROR "inlining call to head" "\[\]string{...} does not escape"
+	x := head("hello", "world") // ERROR "inlining call to head" "\.\.\. argument does not escape"
 	return x
 }
diff --git a/test/live.go b/test/live.go
index bc7b3849cf3b571994f120f9ae27cc6b1fc084fa..6130f7f06944d79535d3468bb01d0069e5b84fb0 100644
--- a/test/live.go
+++ b/test/live.go
@@ -1,5 +1,5 @@
 // errorcheckwithauto -0 -l -live -wb=0 -d=ssa/insert_resched_checks/off
-// +build !ppc64,!ppc64le,!goexperiment.regabi,!goexperiment.regabidefer
+// +build !ppc64,!ppc64le,!goexperiment.regabiargs
 
 // ppc64 needs a better tighten pass to make f18 pass
 // rescheduling checks need to be turned off because there are some live variables across the inserted check call
@@ -144,8 +144,8 @@ var i9 interface{}
 func f9() bool {
 	g8()
 	x := i9
-	y := interface{}(g18()) // ERROR "live at call to convT2E: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
-	i9 = y                  // make y escape so the line above has to call convT2E
+	y := interface{}(g18()) // ERROR "live at call to convT: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
+	i9 = y                  // make y escape so the line above has to call convT
 	return x != y
 }
 
@@ -424,7 +424,7 @@ func f27defer(b bool) {
 	}
 	defer call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
 	printnl()                    // ERROR "live at call to printnl: .autotmp_[0-9]+ .autotmp_[0-9]+"
-	return                       // ERROR "live at call to call27: .autotmp_[0-9]+"
+	return                       // ERROR "live at indirect call: .autotmp_[0-9]+"
 }
 
 // and newproc (go) escapes to the heap
@@ -432,9 +432,9 @@ func f27defer(b bool) {
 func f27go(b bool) {
 	x := 0
 	if b {
-		go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newproc: &x$"
+		go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newobject: &x .autotmp_[0-9]+$" "live at call to newproc: &x$" // allocate two closures, the func literal, and the wrapper for go
 	}
-	go call27(func() { x++ }) // ERROR "live at call to newobject: &x$"
+	go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newobject: .autotmp_[0-9]+$" // allocate two closures, the func literal, and the wrapper for go
 	printnl()
 }
 
@@ -503,7 +503,7 @@ func f31(b1, b2, b3 bool) {
 		g31(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	if b2 {
-		h31(g18()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
+		h31(g18()) // ERROR "live at call to convT: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
 	}
 	if b3 {
 		panic(g18())
@@ -688,7 +688,7 @@ type T struct{}
 
 func (*T) Foo(ptr *int) {}
 
-type R struct{ *T } // ERRORAUTO "live at entry to \(\*R\)\.Foo: \.this ptr" "live at entry to R\.Foo: \.this ptr"
+type R struct{ *T }
 
 // issue 18860: output arguments must be live all the time if there is a defer.
 // In particular, at printint r must be live.
diff --git a/test/live_regabi.go b/test/live_regabi.go
index 2b0278ecb83c903531e7076d865e1d6d6fec63b2..aac9a7766c02fe61189fa6ae8ad8240dc4e88330 100644
--- a/test/live_regabi.go
+++ b/test/live_regabi.go
@@ -1,5 +1,5 @@
 // errorcheckwithauto -0 -l -live -wb=0 -d=ssa/insert_resched_checks/off
-// +build amd64,goexperiment.regabidefer,goexperiment.regabiargs
+// +build amd64,goexperiment.regabiargs arm64,goexperiment.regabiargs
 
 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -139,8 +139,8 @@ var i9 interface{}
 func f9() bool {
 	g8()
 	x := i9
-	y := interface{}(g18()) // ERROR "live at call to convT2E: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
-	i9 = y                  // make y escape so the line above has to call convT2E
+	y := interface{}(g18()) // ERROR "live at call to convT: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
+	i9 = y                  // make y escape so the line above has to call convT
 	return x != y
 }
 
@@ -498,7 +498,7 @@ func f31(b1, b2, b3 bool) {
 		g31(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	if b2 {
-		h31(g18()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
+		h31(g18()) // ERROR "live at call to convT: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
 	}
 	if b3 {
 		panic(g18())
@@ -683,7 +683,7 @@ type T struct{}
 
 func (*T) Foo(ptr *int) {}
 
-type R struct{ *T } // ERRORAUTO "live at entry to \(\*R\)\.Foo: \.this ptr" "live at entry to R\.Foo: \.this ptr"
+type R struct{ *T }
 
 // issue 18860: output arguments must be live all the time if there is a defer.
 // In particular, at printint r must be live.
diff --git a/test/reflectmethod8.go b/test/reflectmethod8.go
new file mode 100644
index 0000000000000000000000000000000000000000..482163bae6f4419811b374ec7eaea0442eef8980
--- /dev/null
+++ b/test/reflectmethod8.go
@@ -0,0 +1,26 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Make sure that the compiler can analyze non-reflect
+// Type.{Method,MethodByName} calls.
+
+package p
+
+type I interface {
+	MethodByName(string)
+	Method(int)
+}
+
+type M struct{}
+
+func (M) MethodByName(string) {}
+func (M) Method(int)          {}
+
+func f() {
+	var m M
+	I.MethodByName(m, "")
+	I.Method(m, 42)
+}
diff --git a/test/run.go b/test/run.go
index d7f5d02391b67dbf2641af524889520c705761b3..3759059c95cf9c9f541c1b5a5e5f4609b21dd3ad 100644
--- a/test/run.go
+++ b/test/run.go
@@ -9,6 +9,7 @@ package main
 
 import (
 	"bytes"
+	"encoding/json"
 	"errors"
 	"flag"
 	"fmt"
@@ -31,6 +32,10 @@ import (
 	"unicode"
 )
 
+// CompilerDefaultGLevel is the -G level used by default when not overridden by a
+// command-line flag
+const CompilerDefaultGLevel = 3
+
 var (
 	verbose        = flag.Bool("v", false, "verbose. if set, parallelism is set to 1.")
 	keep           = flag.Bool("k", false, "keep. keep temporary directory.")
@@ -42,11 +47,55 @@ var (
 	linkshared     = flag.Bool("linkshared", false, "")
 	updateErrors   = flag.Bool("update_errors", false, "update error messages in test file based on compiler output")
 	runoutputLimit = flag.Int("l", defaultRunOutputLimit(), "number of parallel runoutput tests to run")
+	force          = flag.Bool("f", false, "ignore expected-failure test lists")
+	generics       = flag.String("G", defaultGLevels, "a comma-separated list of -G compiler flags to test with")
 
 	shard  = flag.Int("shard", 0, "shard index to run. Only applicable if -shards is non-zero.")
 	shards = flag.Int("shards", 0, "number of shards. If 0, all tests are run. This is used by the continuous build.")
 )
 
+type envVars struct {
+	GOOS         string
+	GOARCH       string
+	GOEXPERIMENT string
+	CGO_ENABLED  string
+}
+
+var env = func() (res envVars) {
+	cmd := exec.Command("go", "env", "-json")
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		log.Fatal("StdoutPipe:", err)
+	}
+	if err := cmd.Start(); err != nil {
+		log.Fatal("Start:", err)
+	}
+	if err := json.NewDecoder(stdout).Decode(&res); err != nil {
+		log.Fatal("Decode:", err)
+	}
+	if err := cmd.Wait(); err != nil {
+		log.Fatal("Wait:", err)
+	}
+	return
+}()
+
+var unifiedEnabled, defaultGLevels = func() (bool, string) {
+	// TODO(mdempsky): This will give false negatives if the unified
+	// experiment is enabled by default, but presumably at that point we
+	// won't need to disable tests for it anymore anyway.
+	enabled := strings.Contains(","+env.GOEXPERIMENT+",", ",unified,")
+
+	// Normal test runs should test with both -G=0 and -G=3 for types2
+	// coverage. But the unified experiment always uses types2, so
+	// testing with -G=3 is redundant.
+	glevels := "0,3"
+	if enabled {
+		glevels = "0"
+	}
+
+	return enabled, glevels
+}()
+
 // defaultAllCodeGen returns the default value of the -all_codegen
 // flag. By default, we prefer to be fast (returning false), except on
 // the linux-amd64 builder that's already very fast, so we get more
@@ -56,12 +105,13 @@ func defaultAllCodeGen() bool {
 }
 
 var (
-	goos, goarch string
-	cgoEnabled   bool
+	goos          = env.GOOS
+	goarch        = env.GOARCH
+	cgoEnabled, _ = strconv.ParseBool(env.CGO_ENABLED)
 
 	// dirs are the directories to look for *.go files in.
 	// TODO(bradfitz): just use all directories?
-	dirs = []string{".", "ken", "chan", "interface", "syntax", "dwarf", "fixedbugs", "codegen", "runtime", "abi", "typeparam"}
+	dirs = []string{".", "ken", "chan", "interface", "syntax", "dwarf", "fixedbugs", "codegen", "runtime", "abi", "typeparam", "typeparam/mdempsky"}
 
 	// ratec controls the max number of tests running at a time.
 	ratec chan bool
@@ -82,11 +132,13 @@ const maxTests = 5000
 func main() {
 	flag.Parse()
 
-	goos = getenv("GOOS", runtime.GOOS)
-	goarch = getenv("GOARCH", runtime.GOARCH)
-	cgoEnv, err := exec.Command(goTool(), "env", "CGO_ENABLED").Output()
-	if err == nil {
-		cgoEnabled, _ = strconv.ParseBool(strings.TrimSpace(string(cgoEnv)))
+	var glevels []int
+	for _, s := range strings.Split(*generics, ",") {
+		glevel, err := strconv.Atoi(s)
+		if err != nil {
+			log.Fatalf("invalid -G flag: %v", err)
+		}
+		glevels = append(glevels, glevel)
 	}
 
 	findExecCmd()
@@ -113,11 +165,11 @@ func main() {
 			}
 			if fi, err := os.Stat(arg); err == nil && fi.IsDir() {
 				for _, baseGoFile := range goFiles(arg) {
-					tests = append(tests, startTest(arg, baseGoFile))
+					tests = append(tests, startTests(arg, baseGoFile, glevels)...)
 				}
 			} else if strings.HasSuffix(arg, ".go") {
 				dir, file := filepath.Split(arg)
-				tests = append(tests, startTest(dir, file))
+				tests = append(tests, startTests(dir, file, glevels)...)
 			} else {
 				log.Fatalf("can't yet deal with non-directory and non-go file %q", arg)
 			}
@@ -125,7 +177,7 @@ func main() {
 	} else {
 		for _, dir := range dirs {
 			for _, baseGoFile := range goFiles(dir) {
-				tests = append(tests, startTest(dir, baseGoFile))
+				tests = append(tests, startTests(dir, baseGoFile, glevels)...)
 			}
 		}
 	}
@@ -142,8 +194,15 @@ func main() {
 			status = "FAIL"
 		}
 		if test.err != nil {
-			status = "FAIL"
 			errStr = test.err.Error()
+			if test.expectFail {
+				errStr += " (expected)"
+			} else {
+				status = "FAIL"
+			}
+		} else if test.expectFail {
+			status = "FAIL"
+			errStr = "unexpected success"
 		}
 		if status == "FAIL" {
 			failed = true
@@ -151,7 +210,8 @@ func main() {
 		resCount[status]++
 		dt := fmt.Sprintf("%.3fs", test.dt.Seconds())
 		if status == "FAIL" {
-			fmt.Printf("# go run run.go -- %s\n%s\nFAIL\t%s\t%s\n",
+			fmt.Printf("# go run run.go -G=%v %s\n%s\nFAIL\t%s\t%s\n",
+				test.glevel,
 				path.Join(test.dir, test.gofile),
 				errStr, test.goFileName(), dt)
 			continue
@@ -270,30 +330,78 @@ type test struct {
 	dir, gofile string
 	donec       chan bool // closed when done
 	dt          time.Duration
+	glevel      int // what -G level this test should use
 
 	src string
 
 	tempDir string
 	err     error
+
+	// expectFail indicates whether the (overall) test recipe is
+	// expected to fail under the current test configuration (e.g., -G=3
+	// or GOEXPERIMENT=unified).
+	expectFail bool
 }
 
-// startTest
-func startTest(dir, gofile string) *test {
-	t := &test{
-		dir:    dir,
-		gofile: gofile,
-		donec:  make(chan bool, 1),
+// initExpectFail initializes t.expectFail based on the build+test
+// configuration.
+func (t *test) initExpectFail(hasGFlag bool) {
+	if *force {
+		return
 	}
-	if toRun == nil {
-		toRun = make(chan *test, maxTests)
-		go runTests()
+
+	if t.glevel == 0 && !hasGFlag && !unifiedEnabled {
+		// tests should always pass when run w/o types2 (i.e., using the
+		// legacy typechecker, option -G=0).
+		return
 	}
-	select {
-	case toRun <- t:
-	default:
-		panic("toRun buffer size (maxTests) is too small")
+
+	failureSets := []map[string]bool{types2Failures}
+
+	// Note: gccgo supports more 32-bit architectures than this, but
+	// hopefully the 32-bit failures are fixed before this matters.
+	switch goarch {
+	case "386", "arm", "mips", "mipsle":
+		failureSets = append(failureSets, types2Failures32Bit)
 	}
-	return t
+
+	if unifiedEnabled {
+		failureSets = append(failureSets, unifiedFailures)
+	} else {
+		failureSets = append(failureSets, g3Failures)
+	}
+
+	filename := strings.Replace(t.goFileName(), "\\", "/", -1) // goFileName() uses \ on Windows
+
+	for _, set := range failureSets {
+		if set[filename] {
+			t.expectFail = true
+			return
+		}
+	}
+}
+
+func startTests(dir, gofile string, glevels []int) []*test {
+	tests := make([]*test, len(glevels))
+	for i, glevel := range glevels {
+		t := &test{
+			dir:    dir,
+			gofile: gofile,
+			glevel: glevel,
+			donec:  make(chan bool, 1),
+		}
+		if toRun == nil {
+			toRun = make(chan *test, maxTests)
+			go runTests()
+		}
+		select {
+		case toRun <- t:
+		default:
+			panic("toRun buffer size (maxTests) is too small")
+		}
+		tests[i] = t
+	}
+	return tests
 }
 
 // runTests runs tests in parallel, but respecting the order they
@@ -480,12 +588,16 @@ func init() { checkShouldTest() }
 // This must match the flags used for building the standard library,
 // or else the commands will rebuild any needed packages (like runtime)
 // over and over.
-func goGcflags() string {
-	return "-gcflags=all=" + os.Getenv("GO_GCFLAGS")
+func (t *test) goGcflags() string {
+	flags := os.Getenv("GO_GCFLAGS")
+	if t.glevel != CompilerDefaultGLevel {
+		flags = fmt.Sprintf("%s -G=%v", flags, t.glevel)
+	}
+	return "-gcflags=all=" + flags
 }
 
-func goGcflagsIsEmpty() bool {
-	return "" == os.Getenv("GO_GCFLAGS")
+func (t *test) goGcflagsIsEmpty() bool {
+	return "" == os.Getenv("GO_GCFLAGS") && t.glevel == CompilerDefaultGLevel
 }
 
 var errTimeout = errors.New("command exceeded time limit")
@@ -541,7 +653,11 @@ func (t *test) run() {
 	singlefilepkgs := false
 	setpkgpaths := false
 	localImports := true
-	f := strings.Fields(action)
+	f, err := splitQuoted(action)
+	if err != nil {
+		t.err = fmt.Errorf("invalid test recipe: %v", err)
+		return
+	}
 	if len(f) > 0 {
 		action = f[0]
 		args = f[1:]
@@ -569,6 +685,8 @@ func (t *test) run() {
 		return
 	}
 
+	goexp := env.GOEXPERIMENT
+
 	// collect flags
 	for len(args) > 0 && strings.HasPrefix(args[0], "-") {
 		switch args[0] {
@@ -595,7 +713,11 @@ func (t *test) run() {
 			}
 		case "-goexperiment": // set GOEXPERIMENT environment
 			args = args[1:]
-			runenv = append(runenv, "GOEXPERIMENT="+args[0])
+			if goexp != "" {
+				goexp += ","
+			}
+			goexp += args[0]
+			runenv = append(runenv, "GOEXPERIMENT="+goexp)
 
 		default:
 			flags = append(flags, args[0])
@@ -616,6 +738,57 @@ func (t *test) run() {
 		}
 	}
 
+	type Tool int
+
+	const (
+		_ Tool = iota
+		AsmCheck
+		Build
+		Run
+		Compile
+	)
+
+	// validForGLevel reports whether the current test is valid to run
+	// at the specified -G level. If so, it may update flags as
+	// necessary to test with -G.
+	validForGLevel := func(tool Tool) bool {
+		hasGFlag := false
+		for _, flag := range flags {
+			if strings.Contains(flag, "-G") {
+				hasGFlag = true
+			}
+		}
+
+		if hasGFlag && t.glevel != CompilerDefaultGLevel {
+			// test provides explicit -G flag already; don't run again
+			if *verbose {
+				fmt.Printf("excl\t%s\n", t.goFileName())
+			}
+			return false
+		}
+
+		t.initExpectFail(hasGFlag)
+
+		switch tool {
+		case Build, Run:
+			// ok; handled in goGcflags
+
+		case Compile:
+			if !hasGFlag {
+				flags = append(flags, fmt.Sprintf("-G=%v", t.glevel))
+			}
+
+		default:
+			// we don't know how to add -G for this test yet
+			if *verbose {
+				fmt.Printf("excl\t%s\n", t.goFileName())
+			}
+			return false
+		}
+
+		return true
+	}
+
 	t.makeTempDir()
 	if !*keep {
 		defer os.RemoveAll(t.tempDir)
@@ -692,6 +865,10 @@ func (t *test) run() {
 		t.err = fmt.Errorf("unimplemented action %q", action)
 
 	case "asmcheck":
+		if !validForGLevel(AsmCheck) {
+			return
+		}
+
 		// Compile Go file and match the generated assembly
 		// against a set of regexps in comments.
 		ops := t.wantedAsmOpcodes(long)
@@ -746,6 +923,10 @@ func (t *test) run() {
 		return
 
 	case "errorcheck":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Compile Go file.
 		// Fail if wantError is true and compilation was successful and vice versa.
 		// Match errors produced by gc against errors in comments.
@@ -774,72 +955,20 @@ func (t *test) run() {
 			t.updateErrors(string(out), long)
 		}
 		t.err = t.errorCheck(string(out), wantAuto, long, t.gofile)
-		if t.err != nil {
-			return // don't hide error if run below succeeds
-		}
-
-		// The following is temporary scaffolding to get types2 typechecker
-		// up and running against the existing test cases. The explicitly
-		// listed files don't pass yet, usually because the error messages
-		// are slightly different (this list is not complete). Any errorcheck
-		// tests that require output from analysis phases past initial type-
-		// checking are also excluded since these phases are not running yet.
-		// We can get rid of this code once types2 is fully plugged in.
-
-		// For now we're done when we can't handle the file or some of the flags.
-		// The first goal is to eliminate the excluded list; the second goal is to
-		// eliminate the flag list.
-
-		// Excluded files.
-		filename := strings.Replace(t.goFileName(), "\\", "/", -1) // goFileName() uses \ on Windows
-		if excluded[filename] {
-			if *verbose {
-				fmt.Printf("excl\t%s\n", filename)
-			}
-			return // cannot handle file yet
-		}
-
-		// Excluded flags.
-		for _, flag := range flags {
-			for _, pattern := range []string{
-				"-m",
-			} {
-				if strings.Contains(flag, pattern) {
-					if *verbose {
-						fmt.Printf("excl\t%s\t%s\n", filename, flags)
-					}
-					return // cannot handle flag
-				}
-			}
-		}
 
-		// Run errorcheck again with -G option (new typechecker).
-		cmdline = []string{goTool(), "tool", "compile", "-G=3", "-C", "-e", "-o", "a.o"}
-		// No need to add -dynlink even if linkshared if we're just checking for errors...
-		cmdline = append(cmdline, flags...)
-		cmdline = append(cmdline, long)
-		out, err = runcmd(cmdline...)
-		if wantError {
-			if err == nil {
-				t.err = fmt.Errorf("compilation succeeded unexpectedly\n%s", out)
-				return
-			}
-		} else {
-			if err != nil {
-				t.err = err
-				return
-			}
-		}
-		if *updateErrors {
-			t.updateErrors(string(out), long)
+	case "compile":
+		if !validForGLevel(Compile) {
+			return
 		}
-		t.err = t.errorCheck(string(out), wantAuto, long, t.gofile)
 
-	case "compile":
 		// Compile Go file.
 		_, t.err = compileFile(runcmd, long, flags)
 
 	case "compiledir":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Compile all files in the directory as packages in lexicographic order.
 		longdir := filepath.Join(cwd, t.goDirName())
 		pkgs, err := goDirPackages(longdir, singlefilepkgs)
@@ -855,6 +984,10 @@ func (t *test) run() {
 		}
 
 	case "errorcheckdir", "errorcheckandrundir":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		flags = append(flags, "-d=panic")
 		// Compile and errorCheck all files in the directory as packages in lexicographic order.
 		// If errorcheckdir and wantError, compilation of the last package must fail.
@@ -900,6 +1033,10 @@ func (t *test) run() {
 		fallthrough
 
 	case "rundir":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Compile all files in the directory as packages in lexicographic order.
 		// In case of errorcheckandrundir, ignore failed compilation of the package before the last.
 		// Link as if the last file is the main package, run it.
@@ -958,6 +1095,10 @@ func (t *test) run() {
 		}
 
 	case "runindir":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Make a shallow copy of t.goDirName() in its own module and GOPATH, and
 		// run "go run ." in it. The module path (and hence import path prefix) of
 		// the copy is equal to the basename of the source directory.
@@ -983,7 +1124,7 @@ func (t *test) run() {
 			return
 		}
 
-		cmd := []string{goTool(), "run", goGcflags()}
+		cmd := []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -997,13 +1138,21 @@ func (t *test) run() {
 		t.checkExpectedOutput(out)
 
 	case "build":
+		if !validForGLevel(Build) {
+			return
+		}
+
 		// Build Go file.
-		_, err := runcmd(goTool(), "build", goGcflags(), "-o", "a.exe", long)
+		_, err := runcmd(goTool(), "build", t.goGcflags(), "-o", "a.exe", long)
 		if err != nil {
 			t.err = err
 		}
 
 	case "builddir", "buildrundir":
+		if !validForGLevel(Build) {
+			return
+		}
+
 		// Build an executable from all the .go and .s files in a subdirectory.
 		// Run it and verify its output in the buildrundir case.
 		longdir := filepath.Join(cwd, t.goDirName())
@@ -1083,10 +1232,14 @@ func (t *test) run() {
 		}
 
 	case "buildrun":
+		if !validForGLevel(Build) {
+			return
+		}
+
 		// Build an executable from Go file, then run it, verify its output.
 		// Useful for timeout tests where failure mode is infinite loop.
 		// TODO: not supported on NaCl
-		cmd := []string{goTool(), "build", goGcflags(), "-o", "a.exe"}
+		cmd := []string{goTool(), "build", t.goGcflags(), "-o", "a.exe"}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1108,13 +1261,17 @@ func (t *test) run() {
 		t.checkExpectedOutput(out)
 
 	case "run":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Run Go file if no special go command flags are provided;
 		// otherwise build an executable and run it.
 		// Verify the output.
 		runInDir = ""
 		var out []byte
 		var err error
-		if len(flags)+len(args) == 0 && goGcflagsIsEmpty() && !*linkshared && goarch == runtime.GOARCH && goos == runtime.GOOS {
+		if len(flags)+len(args) == 0 && t.goGcflagsIsEmpty() && !*linkshared && goarch == runtime.GOARCH && goos == runtime.GOOS && goexp == env.GOEXPERIMENT {
 			// If we're not using special go command flags,
 			// skip all the go command machinery.
 			// This avoids any time the go command would
@@ -1136,7 +1293,7 @@ func (t *test) run() {
 			}
 			out, err = runcmd(append([]string{exe}, args...)...)
 		} else {
-			cmd := []string{goTool(), "run", goGcflags()}
+			cmd := []string{goTool(), "run", t.goGcflags()}
 			if *linkshared {
 				cmd = append(cmd, "-linkshared")
 			}
@@ -1151,6 +1308,10 @@ func (t *test) run() {
 		t.checkExpectedOutput(out)
 
 	case "runoutput":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Run Go file and write its output into temporary Go file.
 		// Run generated Go file and verify its output.
 		rungatec <- true
@@ -1158,7 +1319,7 @@ func (t *test) run() {
 			<-rungatec
 		}()
 		runInDir = ""
-		cmd := []string{goTool(), "run", goGcflags()}
+		cmd := []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1173,7 +1334,7 @@ func (t *test) run() {
 			t.err = fmt.Errorf("write tempfile:%s", err)
 			return
 		}
-		cmd = []string{goTool(), "run", goGcflags()}
+		cmd = []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1186,10 +1347,14 @@ func (t *test) run() {
 		t.checkExpectedOutput(out)
 
 	case "errorcheckoutput":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Run Go file and write its output into temporary Go file.
 		// Compile and errorCheck generated Go file.
 		runInDir = ""
-		cmd := []string{goTool(), "run", goGcflags()}
+		cmd := []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1594,6 +1759,7 @@ var (
 		"ppc64le": {"GOPPC64", "power8", "power9"},
 		"s390x":   {},
 		"wasm":    {},
+		"riscv64": {},
 	}
 )
 
@@ -1941,66 +2107,162 @@ func overlayDir(dstRoot, srcRoot string) error {
 	})
 }
 
+// The following is temporary scaffolding to get types2 typechecker
+// up and running against the existing test cases. The explicitly
+// listed files don't pass yet, usually because the error messages
+// are slightly different (this list is not complete). Any errorcheck
+// tests that require output from analysis phases past initial type-
+// checking are also excluded since these phases are not running yet.
+// We can get rid of this code once types2 is fully plugged in.
+
 // List of files that the compiler cannot errorcheck with the new typechecker (compiler -G option).
 // Temporary scaffolding until we pass all the tests at which point this map can be removed.
-var excluded = map[string]bool{
-	"complit1.go":     true, // types2 reports extra errors
-	"const2.go":       true, // types2 not run after syntax errors
-	"ddd1.go":         true, // issue #42987
-	"directive.go":    true, // misplaced compiler directive checks
-	"float_lit3.go":   true, // types2 reports extra errors
-	"import1.go":      true, // types2 reports extra errors
-	"import5.go":      true, // issue #42988
-	"import6.go":      true, // issue #43109
-	"initializerr.go": true, // types2 reports extra errors
-	"linkname2.go":    true, // error reported by noder (not running for types2 errorcheck test)
-	"notinheap.go":    true, // types2 doesn't report errors about conversions that are invalid due to //go:notinheap
-	"shift1.go":       true, // issue #42989
-	"typecheck.go":    true, // invalid function is not causing errors when called
-	"writebarrier.go": true, // correct diagnostics, but different lines (probably irgen's fault)
-
-	"fixedbugs/bug176.go":    true, // types2 reports all errors (pref: types2)
-	"fixedbugs/bug195.go":    true, // types2 reports slightly different (but correct) bugs
-	"fixedbugs/bug228.go":    true, // types2 not run after syntax errors
-	"fixedbugs/bug231.go":    true, // types2 bug? (same error reported twice)
-	"fixedbugs/bug255.go":    true, // types2 reports extra errors
-	"fixedbugs/bug351.go":    true, // types2 reports extra errors
-	"fixedbugs/bug374.go":    true, // types2 reports extra errors
-	"fixedbugs/bug385_32.go": true, // types2 doesn't produce missing error "type .* too large" (32-bit specific)
-	"fixedbugs/bug388.go":    true, // types2 not run due to syntax errors
-	"fixedbugs/bug412.go":    true, // types2 produces a follow-on error
-
-	"fixedbugs/issue11590.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue11610.go":  true, // types2 not run after syntax errors
-	"fixedbugs/issue11614.go":  true, // types2 reports an extra error
-	"fixedbugs/issue13415.go":  true, // declared but not used conflict
-	"fixedbugs/issue14520.go":  true, // missing import path error by types2
-	"fixedbugs/issue16428.go":  true, // types2 reports two instead of one error
-	"fixedbugs/issue17038.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue17645.go":  true, // multiple errors on same line
-	"fixedbugs/issue18331.go":  true, // missing error about misuse of //go:noescape (irgen needs code from noder)
-	"fixedbugs/issue18393.go":  true, // types2 not run after syntax errors
-	"fixedbugs/issue19012.go":  true, // multiple errors on same line
-	"fixedbugs/issue20233.go":  true, // types2 reports two instead of one error (pref: compiler)
-	"fixedbugs/issue20245.go":  true, // types2 reports two instead of one error (pref: compiler)
-	"fixedbugs/issue20250.go":  true, // correct diagnostics, but different lines (probably irgen's fault)
-	"fixedbugs/issue21979.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue23732.go":  true, // types2 reports different (but ok) line numbers
-	"fixedbugs/issue25958.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue28079b.go": true, // types2 reports follow-on errors
-	"fixedbugs/issue28268.go":  true, // types2 reports follow-on errors
-	"fixedbugs/issue33460.go":  true, // types2 reports alternative positions in separate error
-	"fixedbugs/issue41575.go":  true, // types2 reports alternative positions in separate error
-	"fixedbugs/issue42058a.go": true, // types2 doesn't report "channel element type too large"
-	"fixedbugs/issue42058b.go": true, // types2 doesn't report "channel element type too large"
-	"fixedbugs/issue4232.go":   true, // types2 reports (correct) extra errors
-	"fixedbugs/issue4452.go":   true, // types2 reports (correct) extra errors
-	"fixedbugs/issue5609.go":   true, // types2 needs a better error message
-	"fixedbugs/issue6889.go":   true, // types2 can handle this without constant overflow
-	"fixedbugs/issue7525.go":   true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525b.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525c.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525d.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525e.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue46749.go":  true, // types2 reports can not convert error instead of type mismatched
+var types2Failures = setOf(
+	"directive.go",    // misplaced compiler directive checks
+	"float_lit3.go",   // types2 reports extra errors
+	"import1.go",      // types2 reports extra errors
+	"import6.go",      // issue #43109
+	"initializerr.go", // types2 reports extra errors
+	"linkname2.go",    // error reported by noder (not running for types2 errorcheck test)
+	"notinheap.go",    // types2 doesn't report errors about conversions that are invalid due to //go:notinheap
+	"shift1.go",       // issue #42989
+	"typecheck.go",    // invalid function is not causing errors when called
+
+	"interface/private.go", // types2 phrases errors differently (doesn't use non-spec "private" term)
+
+	"fixedbugs/bug176.go", // types2 reports all errors (pref: types2)
+	"fixedbugs/bug195.go", // types2 reports slightly different (but correct) bugs
+	"fixedbugs/bug228.go", // types2 doesn't run when there are syntax errors
+	"fixedbugs/bug231.go", // types2 bug? (same error reported twice)
+	"fixedbugs/bug255.go", // types2 reports extra errors
+	"fixedbugs/bug374.go", // types2 reports extra errors
+	"fixedbugs/bug388.go", // types2 not run due to syntax errors
+	"fixedbugs/bug412.go", // types2 produces a follow-on error
+
+	"fixedbugs/issue10700.go",  // types2 reports ok hint, but does not match regexp
+	"fixedbugs/issue11590.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue11610.go",  // types2 not run after syntax errors
+	"fixedbugs/issue11614.go",  // types2 reports an extra error
+	"fixedbugs/issue14520.go",  // missing import path error by types2
+	"fixedbugs/issue16428.go",  // types2 reports two instead of one error
+	"fixedbugs/issue17038.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue17645.go",  // multiple errors on same line
+	"fixedbugs/issue18331.go",  // missing error about misuse of //go:noescape (irgen needs code from noder)
+	"fixedbugs/issue18419.go",  // types2 reports
+	"fixedbugs/issue19012.go",  // multiple errors on same line
+	"fixedbugs/issue20233.go",  // types2 reports two instead of one error (pref: compiler)
+	"fixedbugs/issue20245.go",  // types2 reports two instead of one error (pref: compiler)
+	"fixedbugs/issue21979.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue23732.go",  // types2 reports different (but ok) line numbers
+	"fixedbugs/issue25958.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue28079b.go", // types2 reports follow-on errors
+	"fixedbugs/issue28268.go",  // types2 reports follow-on errors
+	"fixedbugs/issue31053.go",  // types2 reports "unknown field" instead of "cannot refer to unexported field"
+	"fixedbugs/issue33460.go",  // types2 reports alternative positions in separate error
+	"fixedbugs/issue42058a.go", // types2 doesn't report "channel element type too large"
+	"fixedbugs/issue42058b.go", // types2 doesn't report "channel element type too large"
+	"fixedbugs/issue4232.go",   // types2 reports (correct) extra errors
+	"fixedbugs/issue4452.go",   // types2 reports (correct) extra errors
+	"fixedbugs/issue4510.go",   // types2 reports different (but ok) line numbers
+	"fixedbugs/issue47201.go",  // types2 spells the error message differently
+	"fixedbugs/issue5609.go",   // types2 needs a better error message
+	"fixedbugs/issue7525b.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525c.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525d.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525e.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525.go",   // types2 reports init cycle error on different line - ok otherwise
+)
+
+var types2Failures32Bit = setOf(
+	"printbig.go",             // large untyped int passed to print (32-bit)
+	"fixedbugs/bug114.go",     // large untyped int passed to println (32-bit)
+	"fixedbugs/issue23305.go", // large untyped int passed to println (32-bit)
+	"fixedbugs/bug385_32.go",  // types2 doesn't produce missing error "type .* too large" (32-bit specific)
+)
+
+var g3Failures = setOf(
+	"writebarrier.go", // correct diagnostics, but different lines (probably irgen's fault)
+
+	"typeparam/nested.go", // -G=3 doesn't support function-local types with generics
+
+	"typeparam/mdempsky/4.go", // -G=3 can't export functions with labeled breaks in loops
+)
+
+var unifiedFailures = setOf(
+	"closure3.go", // unified IR numbers closures differently than -d=inlfuncswithclosures
+	"escape4.go",  // unified IR can inline f5 and f6; test doesn't expect this
+	"inline.go",   // unified IR reports function literal diagnostics on different lines than -d=inlfuncswithclosures
+
+	"fixedbugs/issue42284.go", // prints "T(0) does not escape", but test expects "a.I(a.T(0)) does not escape"
+	"fixedbugs/issue7921.go",  // prints "… escapes to heap", but test expects "string(…) escapes to heap"
+)
+
+func setOf(keys ...string) map[string]bool {
+	m := make(map[string]bool, len(keys))
+	for _, key := range keys {
+		m[key] = true
+	}
+	return m
+}
+
+// splitQuoted splits the string s around each instance of one or more consecutive
+// white space characters while taking into account quotes and escaping, and
+// returns an array of substrings of s or an empty list if s contains only white space.
+// Single quotes and double quotes are recognized to prevent splitting within the
+// quoted region, and are removed from the resulting substrings. If a quote in s
+// isn't closed err will be set and r will have the unclosed argument as the
+// last element. The backslash is used for escaping.
+//
+// For example, the following string:
+//
+//     a b:"c d" 'e''f'  "g\""
+//
+// Would be parsed as:
+//
+//     []string{"a", "b:c d", "ef", `g"`}
+//
+// [copied from src/go/build/build.go]
+func splitQuoted(s string) (r []string, err error) {
+	var args []string
+	arg := make([]rune, len(s))
+	escaped := false
+	quoted := false
+	quote := '\x00'
+	i := 0
+	for _, rune := range s {
+		switch {
+		case escaped:
+			escaped = false
+		case rune == '\\':
+			escaped = true
+			continue
+		case quote != '\x00':
+			if rune == quote {
+				quote = '\x00'
+				continue
+			}
+		case rune == '"' || rune == '\'':
+			quoted = true
+			quote = rune
+			continue
+		case unicode.IsSpace(rune):
+			if quoted || i > 0 {
+				quoted = false
+				args = append(args, string(arg[:i]))
+				i = 0
+			}
+			continue
+		}
+		arg[i] = rune
+		i++
+	}
+	if quoted || i > 0 {
+		args = append(args, string(arg[:i]))
+	}
+	if quote != 0 {
+		err = errors.New("unclosed quote")
+	} else if escaped {
+		err = errors.New("unfinished escaping")
+	}
+	return args, err
 }
diff --git a/test/typeparam/absdiff.go b/test/typeparam/absdiff.go
index 1381d7c92c90b54ed910aff292dd061709bc26e7..cad6e84c4e496b5c5c76e42f86833605d9bc3e6f 100644
--- a/test/typeparam/absdiff.go
+++ b/test/typeparam/absdiff.go
@@ -12,10 +12,10 @@ import (
 )
 
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
 }
 
 // numericAbs matches numeric types with an Abs method.
@@ -33,14 +33,14 @@ func absDifference[T numericAbs[T]](a, b T) T {
 
 // orderedNumeric matches numeric types that support the < operator.
 type orderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // Complex matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // orderedAbs is a helper type that defines an Abs method for
@@ -48,8 +48,7 @@ type Complex interface {
 type orderedAbs[T orderedNumeric] T
 
 func (a orderedAbs[T]) Abs() orderedAbs[T] {
-	// TODO(danscales): orderedAbs[T] conversion shouldn't be needed
-	if a < orderedAbs[T](0) {
+	if a < 0 {
 		return -a
 	}
 	return a
@@ -62,7 +61,7 @@ type complexAbs[T Complex] T
 func (a complexAbs[T]) Abs() complexAbs[T] {
 	r := float64(real(a))
 	i := float64(imag(a))
-	d := math.Sqrt(r * r + i * i)
+	d := math.Sqrt(r*r + i*i)
 	return complexAbs[T](complex(d, 0))
 }
 
@@ -89,10 +88,10 @@ func main() {
 		panic(fmt.Sprintf("got = %v, want = %v", got, want))
 	}
 
-	if got, want := complexAbsDifference(5.0 + 2.0i, 2.0 - 2.0i), 5+0i; got != want {
+	if got, want := complexAbsDifference(5.0+2.0i, 2.0-2.0i), 5+0i; got != want {
 		panic(fmt.Sprintf("got = %v, want = %v", got, want))
 	}
-	if got, want := complexAbsDifference(2.0 - 2.0i, 5.0 + 2.0i), 5+0i; got != want {
+	if got, want := complexAbsDifference(2.0-2.0i, 5.0+2.0i), 5+0i; got != want {
 		panic(fmt.Sprintf("got = %v, want = %v", got, want))
 	}
 }
diff --git a/test/typeparam/absdiffimp.dir/a.go b/test/typeparam/absdiffimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..7b5bfbe2aced91f92fdc096aafde63f1bc24fb6c
--- /dev/null
+++ b/test/typeparam/absdiffimp.dir/a.go
@@ -0,0 +1,75 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"math"
+)
+
+type Numeric interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
+}
+
+// numericAbs matches numeric types with an Abs method.
+type numericAbs[T any] interface {
+	Numeric
+	Abs() T
+}
+
+// AbsDifference computes the absolute value of the difference of
+// a and b, where the absolute value is determined by the Abs method.
+func absDifference[T numericAbs[T]](a, b T) T {
+	d := a - b
+	return d.Abs()
+}
+
+// orderedNumeric matches numeric types that support the < operator.
+type orderedNumeric interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
+}
+
+// Complex matches the two complex types, which do not have a < operator.
+type Complex interface {
+	~complex64 | ~complex128
+}
+
+// orderedAbs is a helper type that defines an Abs method for
+// ordered numeric types.
+type orderedAbs[T orderedNumeric] T
+
+func (a orderedAbs[T]) Abs() orderedAbs[T] {
+	if a < 0 {
+		return -a
+	}
+	return a
+}
+
+// complexAbs is a helper type that defines an Abs method for
+// complex types.
+type complexAbs[T Complex] T
+
+func (a complexAbs[T]) Abs() complexAbs[T] {
+	r := float64(real(a))
+	i := float64(imag(a))
+	d := math.Sqrt(r*r + i*i)
+	return complexAbs[T](complex(d, 0))
+}
+
+// OrderedAbsDifference returns the absolute value of the difference
+// between a and b, where a and b are of an ordered type.
+func OrderedAbsDifference[T orderedNumeric](a, b T) T {
+	return T(absDifference(orderedAbs[T](a), orderedAbs[T](b)))
+}
+
+// ComplexAbsDifference returns the absolute value of the difference
+// between a and b, where a and b are of a complex type.
+func ComplexAbsDifference[T Complex](a, b T) T {
+	return T(absDifference(complexAbs[T](a), complexAbs[T](b)))
+}
diff --git a/test/typeparam/absdiffimp.dir/main.go b/test/typeparam/absdiffimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..8eefdbdf384939cc8dba4ca7307fc183c4f04491
--- /dev/null
+++ b/test/typeparam/absdiffimp.dir/main.go
@@ -0,0 +1,29 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	if got, want := a.OrderedAbsDifference(1.0, -2.0), 3.0; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+	if got, want := a.OrderedAbsDifference(-1.0, 2.0), 3.0; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+	if got, want := a.OrderedAbsDifference(-20, 15), 35; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+
+	if got, want := a.ComplexAbsDifference(5.0+2.0i, 2.0-2.0i), 5+0i; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+	if got, want := a.ComplexAbsDifference(2.0-2.0i, 5.0+2.0i), 5+0i; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+}
diff --git a/test/typeparam/absdiffimp.go b/test/typeparam/absdiffimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/absdiffimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/adder.go b/test/typeparam/adder.go
index 0c25ad4ef2d1c3c049a6b4759f19ba12c36ffb45..79319bd236986233c25793d8dfe73034322b61b7 100644
--- a/test/typeparam/adder.go
+++ b/test/typeparam/adder.go
@@ -11,19 +11,19 @@ import (
 )
 
 type AddType interface {
-	type int, int64, string
+	int | int64 | string
 }
 
-// _Add can add numbers or strings
-func _Add[T AddType](a, b T) T {
+// Add can add numbers or strings
+func Add[T AddType](a, b T) T {
 	return a + b
 }
 
 func main() {
-	if got, want := _Add(5, 3), 8; got != want {
+	if got, want := Add(5, 3), 8; got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	if got, want := _Add("ab", "cd"), "abcd"; got != want {
+	if got, want := Add("ab", "cd"), "abcd"; got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 }
diff --git a/test/typeparam/aliasimp.dir/a.go b/test/typeparam/aliasimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..c64e87c10fa2fd4e31bb7d801094f5691fb329dc
--- /dev/null
+++ b/test/typeparam/aliasimp.dir/a.go
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Rimp[T any] struct {
+	F T
+}
diff --git a/test/typeparam/aliasimp.dir/main.go b/test/typeparam/aliasimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..221a6c758dcf4a1dfe8c48eb1b0c41aaa497db1b
--- /dev/null
+++ b/test/typeparam/aliasimp.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "a"
+
+type R[T any] struct {
+	F T
+}
+
+type S = R
+
+type Sint = R[int]
+
+type Simp = a.Rimp
+
+type SimpString Simp[string]
+
+func main() {
+	var s S[int]
+	if s.F != 0 {
+		panic(s.F)
+	}
+	var s2 Sint
+	if s2.F != 0 {
+		panic(s2.F)
+	}
+	var s3 Simp[string]
+	if s3.F != "" {
+		panic(s3.F)
+	}
+	var s4 SimpString
+	if s4.F != "" {
+		panic(s4.F)
+	}
+}
diff --git a/test/typeparam/aliasimp.go b/test/typeparam/aliasimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/aliasimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/boundmethod.go b/test/typeparam/boundmethod.go
new file mode 100644
index 0000000000000000000000000000000000000000..22f416422da426ea6552a6a801b1eb0d53c12fdb
--- /dev/null
+++ b/test/typeparam/boundmethod.go
@@ -0,0 +1,106 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This test illustrates how a type bound method (String below) can be implemented
+// either by a concrete type (myint below) or a instantiated generic type
+// (StringInt[myint] below).
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+type myint int
+
+//go:noinline
+func (m myint) String() string {
+	return strconv.Itoa(int(m))
+}
+
+type Stringer interface {
+	String() string
+}
+
+func stringify[T Stringer](s []T) (ret []string) {
+	for _, v := range s {
+		// Test normal bounds method call on type param
+		x1 := v.String()
+
+		// Test converting type param to its bound interface first
+		v1 := Stringer(v)
+		x2 := v1.String()
+
+		// Test method expression with type param type
+		f1 := T.String
+		x3 := f1(v)
+
+		// Test creating and calling closure equivalent to the method expression
+		f2 := func(v1 T) string {
+			return Stringer(v1).String()
+		}
+		x4 := f2(v)
+
+		if x1 != x2 || x2 != x3 || x3 != x4 {
+			panic(fmt.Sprintf("Mismatched values %v, %v, %v, %v\n", x1, x2, x3, x4))
+		}
+
+		ret = append(ret, v.String())
+	}
+	return ret
+}
+
+type Ints interface {
+	~int32 | ~int
+}
+
+type StringInt[T Ints] T
+
+//go:noinline
+func (m StringInt[T]) String() string {
+	return strconv.Itoa(int(m))
+}
+
+type StringStruct[T Ints] struct {
+	f T
+}
+
+func (m StringStruct[T]) String() string {
+	return strconv.Itoa(int(m.f))
+}
+
+func main() {
+	x := []myint{myint(1), myint(2), myint(3)}
+
+	// stringify on a normal type, whose bound method is associated with the base type.
+	got := stringify(x)
+	want := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got, want) {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+
+	x2 := []StringInt[myint]{StringInt[myint](5), StringInt[myint](7), StringInt[myint](6)}
+
+	// stringify on an instantiated type, whose bound method is associated with
+	// the generic type StringInt[T], which maps directly to T.
+	got2 := stringify(x2)
+	want2 := []string{ "5", "7", "6" }
+	if !reflect.DeepEqual(got2, want2) {
+		panic(fmt.Sprintf("got %s, want %s", got2, want2))
+	}
+
+	// stringify on an instantiated type, whose bound method is associated with
+	// the generic type StringStruct[T], which maps to a struct containing T.
+	x3 := []StringStruct[myint]{StringStruct[myint]{f: 11}, StringStruct[myint]{f: 10}, StringStruct[myint]{f: 9}}
+
+	got3 := stringify(x3)
+	want3 := []string{ "11", "10", "9" }
+	if !reflect.DeepEqual(got3, want3) {
+		panic(fmt.Sprintf("got %s, want %s", got3, want3))
+	}
+}
diff --git a/test/typeparam/builtins.go b/test/typeparam/builtins.go
new file mode 100644
index 0000000000000000000000000000000000000000..844cdae8ab3c7c590e035f907916cfb3529cdae4
--- /dev/null
+++ b/test/typeparam/builtins.go
@@ -0,0 +1,111 @@
+// compile -G=3
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file tests built-in calls on generic types.
+
+// derived and expanded from cmd/compile/internal/types2/testdata/check/builtins.go2
+
+package builtins
+
+// close
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func f1[T C1](ch T) {
+	close(ch)
+}
+
+func f2[T C3](ch T) {
+	close(ch)
+}
+
+func f3[T C4](ch T) {
+	close(ch)
+}
+
+func f4[T C5[X], X any](ch T) {
+	close(ch)
+}
+
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface {
+	map[string]int | map[string]float64
+}
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func g1[T M1](m T) {
+	delete(m, "foo")
+}
+
+func g2[T M2](m T) {
+	delete(m, "foo")
+}
+
+func g3[T M4[rune, V], V any](m T) {
+	delete(m, 'k')
+}
+
+// make
+
+func m1[
+	S1 interface{ []int },
+	S2 interface{ []int | chan int },
+
+	M1 interface{ map[string]int },
+	M2 interface{ map[string]int | chan int },
+
+	C1 interface{ chan int },
+	C2 interface{ chan int | chan string },
+]() {
+	type S0 []int
+	_ = make([]int, 10)
+	_ = make(S0, 10)
+	_ = make(S1, 10)
+	_ = make(S1, 10, 20)
+
+	type M0 map[string]int
+	_ = make(map[string]int)
+	_ = make(M0)
+	_ = make(M1)
+	_ = make(M1, 10)
+
+	type C0 chan int
+	_ = make(chan int)
+	_ = make(C0)
+	_ = make(C1)
+	_ = make(C1, 10)
+}
+
+// len/cap
+
+type Slice[T any] interface {
+	[]T
+}
+
+func c1[T any, S Slice[T]]() {
+	x := make(S, 5, 10)
+	_ = len(x)
+	_ = cap(x)
+}
+
+// append
+
+func a1[T any, S Slice[T]]() {
+	x := make(S, 5)
+	y := make(S, 2)
+	var z T
+	_ = append(x, y...)
+	_ = append(x, z)
+}
diff --git a/test/typeparam/chans.go b/test/typeparam/chans.go
index 2fcd4af75e544da9cd4fa55bf67b1c13afe33763..c30c21c37bfd062290fe12562b10ee3defa7a28f 100644
--- a/test/typeparam/chans.go
+++ b/test/typeparam/chans.go
@@ -183,7 +183,7 @@ func _Ranger[Elem any]() (*_Sender[Elem], *_Receiver[Elem]) {
 		values: c,
 		done:   d,
 	}
-	r := &_Receiver[Elem] {
+	r := &_Receiver[Elem]{
 		values: c,
 		done:   d,
 	}
diff --git a/test/typeparam/chansimp.dir/a.go b/test/typeparam/chansimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..73219927041c02f4da261511095fde998753862f
--- /dev/null
+++ b/test/typeparam/chansimp.dir/a.go
@@ -0,0 +1,232 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"context"
+	"runtime"
+)
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// ReadAll reads from c until the channel is closed or the context is
+// canceled, returning all the values read.
+func ReadAll[Elem any](ctx context.Context, c <-chan Elem) []Elem {
+	var r []Elem
+	for {
+		select {
+		case <-ctx.Done():
+			return r
+		case v, ok := <-c:
+			if !ok {
+				return r
+			}
+			r = append(r, v)
+		}
+	}
+}
+
+// Merge merges two channels into a single channel.
+// This will leave a goroutine running until either both channels are closed
+// or the context is canceled, at which point the returned channel is closed.
+func Merge[Elem any](ctx context.Context, c1, c2 <-chan Elem) <-chan Elem {
+	r := make(chan Elem)
+	go func(ctx context.Context, c1, c2 <-chan Elem, r chan<- Elem) {
+		defer close(r)
+		for c1 != nil || c2 != nil {
+			select {
+			case <-ctx.Done():
+				return
+			case v1, ok := <-c1:
+				if ok {
+					r <- v1
+				} else {
+					c1 = nil
+				}
+			case v2, ok := <-c2:
+				if ok {
+					r <- v2
+				} else {
+					c2 = nil
+				}
+			}
+		}
+	}(ctx, c1, c2, r)
+	return r
+}
+
+// Filter calls f on each value read from c. If f returns true the value
+// is sent on the returned channel. This will leave a goroutine running
+// until c is closed or the context is canceled, at which point the
+// returned channel is closed.
+func Filter[Elem any](ctx context.Context, c <-chan Elem, f func(Elem) bool) <-chan Elem {
+	r := make(chan Elem)
+	go func(ctx context.Context, c <-chan Elem, f func(Elem) bool, r chan<- Elem) {
+		defer close(r)
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case v, ok := <-c:
+				if !ok {
+					return
+				}
+				if f(v) {
+					r <- v
+				}
+			}
+		}
+	}(ctx, c, f, r)
+	return r
+}
+
+// Sink returns a channel that discards all values sent to it.
+// This will leave a goroutine running until the context is canceled
+// or the returned channel is closed.
+func Sink[Elem any](ctx context.Context) chan<- Elem {
+	r := make(chan Elem)
+	go func(ctx context.Context, r <-chan Elem) {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case _, ok := <-r:
+				if !ok {
+					return
+				}
+			}
+		}
+	}(ctx, r)
+	return r
+}
+
+// An Exclusive is a value that may only be used by a single goroutine
+// at a time. This is implemented using channels rather than a mutex.
+type Exclusive[Val any] struct {
+	c chan Val
+}
+
+// MakeExclusive makes an initialized exclusive value.
+func MakeExclusive[Val any](initial Val) *Exclusive[Val] {
+	r := &Exclusive[Val]{
+		c: make(chan Val, 1),
+	}
+	r.c <- initial
+	return r
+}
+
+// Acquire acquires the exclusive value for private use.
+// It must be released using the Release method.
+func (e *Exclusive[Val]) Acquire() Val {
+	return <-e.c
+}
+
+// TryAcquire attempts to acquire the value. The ok result reports whether
+// the value was acquired. If the value is acquired, it must be released
+// using the Release method.
+func (e *Exclusive[Val]) TryAcquire() (v Val, ok bool) {
+	select {
+	case r := <-e.c:
+		return r, true
+	default:
+		return v, false
+	}
+}
+
+// Release updates and releases the value.
+// This method panics if the value has not been acquired.
+func (e *Exclusive[Val]) Release(v Val) {
+	select {
+	case e.c <- v:
+	default:
+		panic("Exclusive Release without Acquire")
+	}
+}
+
+// Ranger returns a Sender and a Receiver. The Receiver provides a
+// Next method to retrieve values. The Sender provides a Send method
+// to send values and a Close method to stop sending values. The Next
+// method indicates when the Sender has been closed, and the Send
+// method indicates when the Receiver has been freed.
+//
+// This is a convenient way to exit a goroutine sending values when
+// the receiver stops reading them.
+func Ranger[Elem any]() (*Sender[Elem], *Receiver[Elem]) {
+	c := make(chan Elem)
+	d := make(chan struct{})
+	s := &Sender[Elem]{
+		values: c,
+		done:   d,
+	}
+	r := &Receiver[Elem]{
+		values: c,
+		done:   d,
+	}
+	runtime.SetFinalizer(r, (*Receiver[Elem]).finalize)
+	return s, r
+}
+
+// A Sender is used to send values to a Receiver.
+type Sender[Elem any] struct {
+	values chan<- Elem
+	done   <-chan struct{}
+}
+
+// Send sends a value to the receiver. It reports whether the value was sent.
+// The value will not be sent if the context is closed or the receiver
+// is freed.
+func (s *Sender[Elem]) Send(ctx context.Context, v Elem) bool {
+	select {
+	case <-ctx.Done():
+		return false
+	case s.values <- v:
+		return true
+	case <-s.done:
+		return false
+	}
+}
+
+// Close tells the receiver that no more values will arrive.
+// After Close is called, the Sender may no longer be used.
+func (s *Sender[Elem]) Close() {
+	close(s.values)
+}
+
+// A Receiver receives values from a Sender.
+type Receiver[Elem any] struct {
+	values <-chan Elem
+	done   chan<- struct{}
+}
+
+// Next returns the next value from the channel. The bool result indicates
+// whether the value is valid.
+func (r *Receiver[Elem]) Next(ctx context.Context) (v Elem, ok bool) {
+	select {
+	case <-ctx.Done():
+	case v, ok = <-r.values:
+	}
+	return v, ok
+}
+
+// finalize is a finalizer for the receiver.
+func (r *Receiver[Elem]) finalize() {
+	close(r.done)
+}
diff --git a/test/typeparam/chansimp.dir/main.go b/test/typeparam/chansimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..ca2716759824988ecaccaff3b37af90390257bc0
--- /dev/null
+++ b/test/typeparam/chansimp.dir/main.go
@@ -0,0 +1,189 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"context"
+	"fmt"
+	"runtime"
+	"sort"
+	"sync"
+	"time"
+)
+
+func TestReadAll() {
+	c := make(chan int)
+	go func() {
+		c <- 4
+		c <- 2
+		c <- 5
+		close(c)
+	}()
+	got := a.ReadAll(context.Background(), c)
+	want := []int{4, 2, 5}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("ReadAll returned %v, want %v", got, want))
+	}
+}
+
+func TestMerge() {
+	c1 := make(chan int)
+	c2 := make(chan int)
+	go func() {
+		c1 <- 1
+		c1 <- 3
+		c1 <- 5
+		close(c1)
+	}()
+	go func() {
+		c2 <- 2
+		c2 <- 4
+		c2 <- 6
+		close(c2)
+	}()
+	ctx := context.Background()
+	got := a.ReadAll(ctx, a.Merge(ctx, c1, c2))
+	sort.Ints(got)
+	want := []int{1, 2, 3, 4, 5, 6}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("Merge returned %v, want %v", got, want))
+	}
+}
+
+func TestFilter() {
+	c := make(chan int)
+	go func() {
+		c <- 1
+		c <- 2
+		c <- 3
+		close(c)
+	}()
+	even := func(i int) bool { return i%2 == 0 }
+	ctx := context.Background()
+	got := a.ReadAll(ctx, a.Filter(ctx, c, even))
+	want := []int{2}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("Filter returned %v, want %v", got, want))
+	}
+}
+
+func TestSink() {
+	c := a.Sink[int](context.Background())
+	after := time.NewTimer(time.Minute)
+	defer after.Stop()
+	send := func(v int) {
+		select {
+		case c <- v:
+		case <-after.C:
+			panic("timed out sending to Sink")
+		}
+	}
+	send(1)
+	send(2)
+	send(3)
+	close(c)
+}
+
+func TestExclusive() {
+	val := 0
+	ex := a.MakeExclusive(&val)
+
+	var wg sync.WaitGroup
+	f := func() {
+		defer wg.Done()
+		for i := 0; i < 10; i++ {
+			p := ex.Acquire()
+			(*p)++
+			ex.Release(p)
+		}
+	}
+
+	wg.Add(2)
+	go f()
+	go f()
+
+	wg.Wait()
+	if val != 20 {
+		panic(fmt.Sprintf("after Acquire/Release loop got %d, want 20", val))
+	}
+}
+
+func TestExclusiveTry() {
+	s := ""
+	ex := a.MakeExclusive(&s)
+	p, ok := ex.TryAcquire()
+	if !ok {
+		panic("TryAcquire failed")
+	}
+	*p = "a"
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, ok := ex.TryAcquire()
+		if ok {
+			panic(fmt.Sprintf("TryAcquire succeeded unexpectedly"))
+		}
+	}()
+	wg.Wait()
+
+	ex.Release(p)
+
+	p, ok = ex.TryAcquire()
+	if !ok {
+		panic(fmt.Sprintf("TryAcquire failed"))
+	}
+}
+
+func TestRanger() {
+	s, r := a.Ranger[int]()
+
+	ctx := context.Background()
+	go func() {
+		// Receive one value then exit.
+		v, ok := r.Next(ctx)
+		if !ok {
+			panic(fmt.Sprintf("did not receive any values"))
+		} else if v != 1 {
+			panic(fmt.Sprintf("received %d, want 1", v))
+		}
+	}()
+
+	c1 := make(chan bool)
+	c2 := make(chan bool)
+	go func() {
+		defer close(c2)
+		if !s.Send(ctx, 1) {
+			panic(fmt.Sprintf("Send failed unexpectedly"))
+		}
+		close(c1)
+		if s.Send(ctx, 2) {
+			panic(fmt.Sprintf("Send succeeded unexpectedly"))
+		}
+	}()
+
+	<-c1
+
+	// Force a garbage collection to try to get the finalizers to run.
+	runtime.GC()
+
+	select {
+	case <-c2:
+	case <-time.After(time.Minute):
+		panic("Ranger Send should have failed, but timed out")
+	}
+}
+
+func main() {
+	TestReadAll()
+	TestMerge()
+	TestFilter()
+	TestSink()
+	TestExclusive()
+	TestExclusiveTry()
+	TestRanger()
+}
diff --git a/test/typeparam/chansimp.go b/test/typeparam/chansimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/chansimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/combine.go b/test/typeparam/combine.go
index d4a2988a7b0e46421e96949ebf8c3ada48081d04..5dfdb78442529f986f172df76516509fc0079f2b 100644
--- a/test/typeparam/combine.go
+++ b/test/typeparam/combine.go
@@ -10,56 +10,56 @@ import (
 	"fmt"
 )
 
-type _Gen[A any] func() (A, bool)
+type Gen[A any] func() (A, bool)
 
-func combine[T1, T2, T any](g1 _Gen[T1], g2 _Gen[T2], join func(T1, T2) T) _Gen[T] {
-    return func() (T, bool) {
-        var t T
-        t1, ok := g1()
-        if !ok {
-            return t, false
-        }
-        t2, ok := g2()
-        if !ok {
-            return t, false
-        }
-        return join(t1, t2), true
-    }
+func Combine[T1, T2, T any](g1 Gen[T1], g2 Gen[T2], join func(T1, T2) T) Gen[T] {
+	return func() (T, bool) {
+		var t T
+		t1, ok := g1()
+		if !ok {
+			return t, false
+		}
+		t2, ok := g2()
+		if !ok {
+			return t, false
+		}
+		return join(t1, t2), true
+	}
 }
 
-type _Pair[A, B any] struct {
+type Pair[A, B any] struct {
 	A A
 	B B
 }
 
-func _NewPair[A, B any](a A, b B) _Pair[A, B] {
-	return _Pair[A, B]{a, b}
+func _NewPair[A, B any](a A, b B) Pair[A, B] {
+	return Pair[A, B]{a, b}
 }
 
-func _Combine2[A, B any](ga _Gen[A], gb _Gen[B]) _Gen[_Pair[A, B]] {
-    return combine(ga, gb, _NewPair[A, B])
+func Combine2[A, B any](ga Gen[A], gb Gen[B]) Gen[Pair[A, B]] {
+	return Combine(ga, gb, _NewPair[A, B])
 }
 
 func main() {
-	var g1 _Gen[int] = func() (int, bool) { return 3, true }
-	var g2 _Gen[string] = func() (string, bool) { return "x", false }
-	var g3 _Gen[string] = func() (string, bool) { return "y", true }
+	var g1 Gen[int] = func() (int, bool) { return 3, true }
+	var g2 Gen[string] = func() (string, bool) { return "x", false }
+	var g3 Gen[string] = func() (string, bool) { return "y", true }
 
-	gc := combine(g1, g2, _NewPair[int, string])
+	gc := Combine(g1, g2, _NewPair[int, string])
 	if got, ok := gc(); ok {
 		panic(fmt.Sprintf("got %v, %v, wanted -/false", got, ok))
 	}
-	gc2 := _Combine2(g1, g2)
+	gc2 := Combine2(g1, g2)
 	if got, ok := gc2(); ok {
 		panic(fmt.Sprintf("got %v, %v, wanted -/false", got, ok))
 	}
 
-	gc3 := combine(g1, g3, _NewPair[int, string])
+	gc3 := Combine(g1, g3, _NewPair[int, string])
 	if got, ok := gc3(); !ok || got.A != 3 || got.B != "y" {
 		panic(fmt.Sprintf("got %v, %v, wanted {3, y}, true", got, ok))
 	}
-	gc4 := _Combine2(g1, g3)
+	gc4 := Combine2(g1, g3)
 	if got, ok := gc4(); !ok || got.A != 3 || got.B != "y" {
-		panic (fmt.Sprintf("got %v, %v, wanted {3, y}, true", got, ok))
+		panic(fmt.Sprintf("got %v, %v, wanted {3, y}, true", got, ok))
 	}
 }
diff --git a/test/typeparam/cons.go b/test/typeparam/cons.go
index 8d255ebdb83ea83e563426aefc228484b3a26728..4750392a9557a42002530365377b2112902dec9a 100644
--- a/test/typeparam/cons.go
+++ b/test/typeparam/cons.go
@@ -12,7 +12,7 @@ import "fmt"
 // argument
 type any interface{}
 
-type _Function[a, b any] interface {
+type Function[a, b any] interface {
 	Apply(x a) b
 }
 
@@ -29,8 +29,8 @@ func (this pos) Apply(x int) bool {
 }
 
 type compose[a, b, c any] struct {
-	f _Function[a, b]
-	g _Function[b, c]
+	f Function[a, b]
+	g Function[b, c]
 }
 
 func (this compose[a, b, c]) Apply(x a) c {
@@ -47,52 +47,52 @@ func (this Int) Equal(that int) bool {
 	return int(this) == that
 }
 
-type _List[a any] interface {
-	Match(casenil _Function[_Nil[a], any], casecons _Function[_Cons[a], any]) any
+type List[a any] interface {
+	Match(casenil Function[Nil[a], any], casecons Function[Cons[a], any]) any
 }
 
-type _Nil[a any] struct{
+type Nil[a any] struct {
 }
 
-func (xs _Nil[a]) Match(casenil _Function[_Nil[a], any], casecons _Function[_Cons[a], any]) any {
+func (xs Nil[a]) Match(casenil Function[Nil[a], any], casecons Function[Cons[a], any]) any {
 	return casenil.Apply(xs)
 }
 
-type _Cons[a any] struct {
+type Cons[a any] struct {
 	Head a
-	Tail _List[a]
+	Tail List[a]
 }
 
-func (xs _Cons[a]) Match(casenil _Function[_Nil[a], any], casecons _Function[_Cons[a], any]) any {
+func (xs Cons[a]) Match(casenil Function[Nil[a], any], casecons Function[Cons[a], any]) any {
 	return casecons.Apply(xs)
 }
 
-type mapNil[a, b any] struct{
+type mapNil[a, b any] struct {
 }
 
-func (m mapNil[a, b]) Apply(_ _Nil[a]) any {
-	return _Nil[b]{}
+func (m mapNil[a, b]) Apply(_ Nil[a]) any {
+	return Nil[b]{}
 }
 
 type mapCons[a, b any] struct {
-	f _Function[a, b]
+	f Function[a, b]
 }
 
-func (m mapCons[a, b]) Apply(xs _Cons[a]) any {
-	return _Cons[b]{m.f.Apply(xs.Head), _Map[a, b](m.f, xs.Tail)}
+func (m mapCons[a, b]) Apply(xs Cons[a]) any {
+	return Cons[b]{m.f.Apply(xs.Head), Map[a, b](m.f, xs.Tail)}
 }
 
-func _Map[a, b any](f _Function[a, b], xs _List[a]) _List[b] {
-	return xs.Match(mapNil[a, b]{}, mapCons[a, b]{f}).(_List[b])
+func Map[a, b any](f Function[a, b], xs List[a]) List[b] {
+	return xs.Match(mapNil[a, b]{}, mapCons[a, b]{f}).(List[b])
 }
 
 func main() {
-	var xs _List[int] = _Cons[int]{3, _Cons[int]{6, _Nil[int]{}}}
-	var ys _List[int] = _Map[int, int](incr{-5}, xs)
-	var xz _List[bool] = _Map[int, bool](pos{}, ys)
-	cs1 := xz.(_Cons[bool])
-	cs2 := cs1.Tail.(_Cons[bool])
-	_, ok := cs2.Tail.(_Nil[bool])
+	var xs List[int] = Cons[int]{3, Cons[int]{6, Nil[int]{}}}
+	var ys List[int] = Map[int, int](incr{-5}, xs)
+	var xz List[bool] = Map[int, bool](pos{}, ys)
+	cs1 := xz.(Cons[bool])
+	cs2 := cs1.Tail.(Cons[bool])
+	_, ok := cs2.Tail.(Nil[bool])
 	if cs1.Head != false || cs2.Head != true || !ok {
 		panic(fmt.Sprintf("got %v, %v, %v, expected false, true, true",
 			cs1.Head, cs2.Head, ok))
diff --git a/test/typeparam/dedup.dir/a.go b/test/typeparam/dedup.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..f5cb6dc7623c86dd82ecc69805965890287b43df
--- /dev/null
+++ b/test/typeparam/dedup.dir/a.go
@@ -0,0 +1,10 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+//go:noinline
+func F[T comparable](a, b T) bool {
+	return a == b
+}
diff --git a/test/typeparam/dedup.dir/b.go b/test/typeparam/dedup.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..ce037e2d8a3ebd0a9d9b1d862f20fe47a111aead
--- /dev/null
+++ b/test/typeparam/dedup.dir/b.go
@@ -0,0 +1,14 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "a"
+
+func B() {
+	var x int64
+	println(a.F(&x, &x))
+	var y int32
+	println(a.F(&y, &y))
+}
diff --git a/test/typeparam/dedup.dir/c.go b/test/typeparam/dedup.dir/c.go
new file mode 100644
index 0000000000000000000000000000000000000000..11a5d97642be7ab5c4d4f9675b0faa50db9c2ccc
--- /dev/null
+++ b/test/typeparam/dedup.dir/c.go
@@ -0,0 +1,14 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package c
+
+import "a"
+
+func C() {
+	var x int64
+	println(a.F(&x, &x))
+	var y int32
+	println(a.F(&y, &y))
+}
diff --git a/test/typeparam/dedup.dir/main.go b/test/typeparam/dedup.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..dc3ff6f75ffaeba8471026ea90af8387806b0945
--- /dev/null
+++ b/test/typeparam/dedup.dir/main.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"b"
+	"c"
+)
+
+func main() {
+	b.B()
+	c.C()
+}
diff --git a/test/typeparam/dedup.go b/test/typeparam/dedup.go
new file mode 100644
index 0000000000000000000000000000000000000000..dca4cf3a84fdaa29523b60be40a57efb3ac32e44
--- /dev/null
+++ b/test/typeparam/dedup.go
@@ -0,0 +1,12 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Note: this doesn't really test the deduplication of
+// instantiations. It just provides an easy mechanism to build a
+// binary that you can then check with objdump manually to make sure
+// deduplication is happening. TODO: automate this somehow?
+
+package ignored
diff --git a/test/typeparam/dedup.out b/test/typeparam/dedup.out
new file mode 100644
index 0000000000000000000000000000000000000000..1140ff52e2ba1f46b1315269500c551a9bd48768
--- /dev/null
+++ b/test/typeparam/dedup.out
@@ -0,0 +1,4 @@
+true
+true
+true
+true
diff --git a/test/typeparam/dictionaryCapture-noinline.go b/test/typeparam/dictionaryCapture-noinline.go
new file mode 100644
index 0000000000000000000000000000000000000000..ad5bfa008e9004aa6360d05cf7cc7c1991991d0b
--- /dev/null
+++ b/test/typeparam/dictionaryCapture-noinline.go
@@ -0,0 +1,126 @@
+// run -gcflags="-G=3 -l"
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test situations where functions/methods are not
+// immediately called and we need to capture the dictionary
+// required for later invocation.
+
+package main
+
+func main() {
+	functions()
+	methodExpressions()
+	methodValues()
+	interfaceMethods()
+	globals()
+}
+
+func g0[T any](x T) {
+}
+func g1[T any](x T) T {
+	return x
+}
+func g2[T any](x T) (T, T) {
+	return x, x
+}
+
+func functions() {
+	f0 := g0[int]
+	f0(7)
+	f1 := g1[int]
+	is7(f1(7))
+	f2 := g2[int]
+	is77(f2(7))
+}
+
+func is7(x int) {
+	if x != 7 {
+		println(x)
+		panic("assertion failed")
+	}
+}
+func is77(x, y int) {
+	if x != 7 || y != 7 {
+		println(x, y)
+		panic("assertion failed")
+	}
+}
+
+type s[T any] struct {
+	a T
+}
+
+func (x s[T]) g0() {
+}
+func (x s[T]) g1() T {
+	return x.a
+}
+func (x s[T]) g2() (T, T) {
+	return x.a, x.a
+}
+
+func methodExpressions() {
+	x := s[int]{a: 7}
+	f0 := s[int].g0
+	f0(x)
+	f1 := s[int].g1
+	is7(f1(x))
+	f2 := s[int].g2
+	is77(f2(x))
+}
+
+func methodValues() {
+	x := s[int]{a: 7}
+	f0 := x.g0
+	f0()
+	f1 := x.g1
+	is7(f1())
+	f2 := x.g2
+	is77(f2())
+}
+
+var x interface {
+	g0()
+	g1() int
+	g2() (int, int)
+} = s[int]{a: 7}
+var y interface{} = s[int]{a: 7}
+
+func interfaceMethods() {
+	x.g0()
+	is7(x.g1())
+	is77(x.g2())
+	y.(interface{ g0() }).g0()
+	is7(y.(interface{ g1() int }).g1())
+	is77(y.(interface{ g2() (int, int) }).g2())
+}
+
+// Also check for instantiations outside functions.
+var gg0 = g0[int]
+var gg1 = g1[int]
+var gg2 = g2[int]
+
+var hh0 = s[int].g0
+var hh1 = s[int].g1
+var hh2 = s[int].g2
+
+var xtop = s[int]{a: 7}
+var ii0 = x.g0
+var ii1 = x.g1
+var ii2 = x.g2
+
+func globals() {
+	gg0(7)
+	is7(gg1(7))
+	is77(gg2(7))
+	x := s[int]{a: 7}
+	hh0(x)
+	is7(hh1(x))
+	is77(hh2(x))
+	ii0()
+	is7(ii1())
+	is77(ii2())
+}
diff --git a/test/typeparam/dictionaryCapture.go b/test/typeparam/dictionaryCapture.go
new file mode 100644
index 0000000000000000000000000000000000000000..7c7948145a8f3afed97d9767ad2a618db5fab48f
--- /dev/null
+++ b/test/typeparam/dictionaryCapture.go
@@ -0,0 +1,203 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test situations where functions/methods are not
+// immediately called and we need to capture the dictionary
+// required for later invocation.
+
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	functions()
+	methodExpressions()
+	genMethodExpressions[int](7)
+	methodValues()
+	genMethodValues[int](7)
+	interfaceMethods()
+	globals()
+	recursive()
+}
+
+func g0[T any](x T) {
+}
+func g1[T any](x T) T {
+	return x
+}
+func g2[T any](x T) (T, T) {
+	return x, x
+}
+
+func functions() {
+	f0 := g0[int]
+	f0(7)
+	f1 := g1[int]
+	is7(f1(7))
+	f2 := g2[int]
+	is77(f2(7))
+}
+
+func is7(x int) {
+	if x != 7 {
+		println(x)
+		panic("assertion failed")
+	}
+}
+func is77(x, y int) {
+	if x != 7 || y != 7 {
+		println(x, y)
+		panic("assertion failed")
+	}
+}
+
+type s[T any] struct {
+	a T
+}
+
+func (x s[T]) g0() {
+}
+func (x s[T]) g1() T {
+	return x.a
+}
+func (x s[T]) g2() (T, T) {
+	return x.a, x.a
+}
+
+func methodExpressions() {
+	x := s[int]{a: 7}
+	f0 := s[int].g0
+	f0(x)
+	f0p := (*s[int]).g0
+	f0p(&x)
+	f1 := s[int].g1
+	is7(f1(x))
+	f1p := (*s[int]).g1
+	is7(f1p(&x))
+	f2 := s[int].g2
+	is77(f2(x))
+	f2p := (*s[int]).g2
+	is77(f2p(&x))
+}
+
+func genMethodExpressions[T comparable](want T) {
+	x := s[T]{a: want}
+	f0 := s[T].g0
+	f0(x)
+	f0p := (*s[T]).g0
+	f0p(&x)
+	f1 := s[T].g1
+	if got := f1(x); got != want {
+		panic(fmt.Sprintf("f1(x) == %d, want %d", got, want))
+	}
+	f1p := (*s[T]).g1
+	if got := f1p(&x); got != want {
+		panic(fmt.Sprintf("f1p(&x) == %d, want %d", got, want))
+	}
+	f2 := s[T].g2
+	if got1, got2 := f2(x); got1 != want || got2 != want {
+		panic(fmt.Sprintf("f2(x) == %d, %d, want %d, %d", got1, got2, want, want))
+	}
+}
+
+func methodValues() {
+	x := s[int]{a: 7}
+	f0 := x.g0
+	f0()
+	f1 := x.g1
+	is7(f1())
+	f2 := x.g2
+	is77(f2())
+}
+
+func genMethodValues[T comparable](want T) {
+	x := s[T]{a: want}
+	f0 := x.g0
+	f0()
+	f1 := x.g1
+	if got := f1(); got != want {
+		panic(fmt.Sprintf("f1() == %d, want %d", got, want))
+	}
+	f2 := x.g2
+	if got1, got2 := f2(); got1 != want || got2 != want {
+		panic(fmt.Sprintf("f2() == %d, %d, want %d, %d", got1, got2, want, want))
+	}
+}
+
+var x interface {
+	g0()
+	g1() int
+	g2() (int, int)
+} = s[int]{a: 7}
+var y interface{} = s[int]{a: 7}
+
+func interfaceMethods() {
+	x.g0()
+	is7(x.g1())
+	is77(x.g2())
+	y.(interface{ g0() }).g0()
+	is7(y.(interface{ g1() int }).g1())
+	is77(y.(interface{ g2() (int, int) }).g2())
+}
+
+// Also check for instantiations outside functions.
+var gg0 = g0[int]
+var gg1 = g1[int]
+var gg2 = g2[int]
+
+var hh0 = s[int].g0
+var hh1 = s[int].g1
+var hh2 = s[int].g2
+
+var xtop = s[int]{a: 7}
+var ii0 = x.g0
+var ii1 = x.g1
+var ii2 = x.g2
+
+func globals() {
+	gg0(7)
+	is7(gg1(7))
+	is77(gg2(7))
+	x := s[int]{a: 7}
+	hh0(x)
+	is7(hh1(x))
+	is77(hh2(x))
+	ii0()
+	is7(ii1())
+	is77(ii2())
+}
+
+func recursive() {
+	if got, want := recur1[int](5), 110; got != want {
+		panic(fmt.Sprintf("recur1[int](5) = %d, want = %d", got, want))
+	}
+}
+
+type Integer interface {
+	int | int32 | int64
+}
+
+func recur1[T Integer](n T) T {
+	if n == 0 || n == 1 {
+		return T(1)
+	} else {
+		return n * recur2(n-1)
+	}
+}
+
+func recur2[T Integer](n T) T {
+	list := make([]T, n)
+	for i, _ := range list {
+		list[i] = T(i + 1)
+	}
+	var sum T
+	for _, elt := range list {
+		sum += elt
+	}
+	return sum + recur1(n-1)
+}
diff --git a/test/typeparam/dottype.go b/test/typeparam/dottype.go
new file mode 100644
index 0000000000000000000000000000000000000000..c9c900c0962ecc74ab94d0e6d2b39b05d6f44c74
--- /dev/null
+++ b/test/typeparam/dottype.go
@@ -0,0 +1,86 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](x interface{}) T {
+	return x.(T)
+}
+func f2[T any](x interface{}) (T, bool) {
+	t, ok := x.(T)
+	return t, ok
+}
+
+type I interface {
+	foo()
+}
+
+type myint int
+
+func (myint) foo() {
+}
+
+type myfloat float64
+
+func (myfloat) foo() {
+}
+
+func g[T I](x I) T {
+	return x.(T)
+}
+func g2[T I](x I) (T, bool) {
+	t, ok := x.(T)
+	return t, ok
+}
+
+func h[T any](x interface{}) struct{ a, b T } {
+	return x.(struct{ a, b T })
+}
+
+func k[T any](x interface{}) interface{ bar() T } {
+	return x.(interface{ bar() T })
+}
+
+type mybar int
+
+func (x mybar) bar() int {
+	return int(x)
+}
+
+func main() {
+	var i interface{} = int(3)
+	var j I = myint(3)
+	var x interface{} = float64(3)
+	var y I = myfloat(3)
+
+	println(f[int](i))
+	shouldpanic(func() { f[int](x) })
+	println(f2[int](i))
+	println(f2[int](x))
+
+	println(g[myint](j))
+	shouldpanic(func() { g[myint](y) })
+	println(g2[myint](j))
+	println(g2[myint](y))
+
+	println(h[int](struct{ a, b int }{3, 5}).a)
+
+	println(k[int](mybar(3)).bar())
+
+	type large struct {a,b,c,d,e,f int}
+	println(f[large](large{}).a)
+	l2, ok := f2[large](large{})
+	println(l2.a, ok)
+}
+func shouldpanic(x func()) {
+	defer func() {
+		e := recover()
+		if e == nil {
+			panic("didn't panic")
+		}
+	}()
+	x()
+}
diff --git a/test/typeparam/dottype.out b/test/typeparam/dottype.out
new file mode 100644
index 0000000000000000000000000000000000000000..8e6a3c25526093a1175bc60dad33b267fa5ad0ee
--- /dev/null
+++ b/test/typeparam/dottype.out
@@ -0,0 +1,10 @@
+3
+3 true
+0 false
+3
+3 true
+0 false
+3
+3
+0
+0 true
diff --git a/test/typeparam/double.go b/test/typeparam/double.go
index ce78ec9748319ca580451630955a3428b30e09cd..6ddb6b2d08b11238827d2ce2f71e8c19b886fcbf 100644
--- a/test/typeparam/double.go
+++ b/test/typeparam/double.go
@@ -12,7 +12,7 @@ import (
 )
 
 type Number interface {
-	type int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | ~float32 | ~float64
 }
 
 type MySlice []int
@@ -44,29 +44,29 @@ func main() {
 	want := MySlice{2, 4, 6}
 	got := _DoubleElems[MySlice, int](arg)
 	if !reflect.DeepEqual(got, want) {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	// constraint type inference
 	got = _DoubleElems[MySlice](arg)
 	if !reflect.DeepEqual(got, want) {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	got = _DoubleElems(arg)
 	if !reflect.DeepEqual(got, want) {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	farg := MyFloatSlice{1.2, 2.0, 3.5}
 	fwant := MyFloatSlice{2.4, 4.0, 7.0}
 	fgot := _DoubleElems(farg)
 	if !reflect.DeepEqual(fgot, fwant) {
-                panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
+		panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
 	}
 
 	fgot = _DoubleElems2(farg)
 	if !reflect.DeepEqual(fgot, fwant) {
-                panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
+		panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
 	}
 }
diff --git a/test/typeparam/equal.go b/test/typeparam/equal.go
new file mode 100644
index 0000000000000000000000000000000000000000..a1d3e8ae02348f8495933cf337d8910a8aad256c
--- /dev/null
+++ b/test/typeparam/equal.go
@@ -0,0 +1,69 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// comparisons of type parameters to interfaces
+
+package main
+
+func f[T comparable](t, u T) bool {
+	// Comparing two type parameters directly.
+	// (Not really testing comparisons to interfaces, but just 'cause we're here.)
+	return t == u
+}
+
+func g[T comparable](t T, i interface{}) bool {
+	// Compare type parameter value to empty interface.
+	return t == i
+}
+
+type I interface {
+	foo()
+}
+
+type C interface {
+	comparable
+	I
+}
+
+func h[T C](t T, i I) bool {
+	// Compare type parameter value to nonempty interface.
+	return t == i
+}
+
+type myint int
+
+func (x myint) foo() {
+}
+
+func k[T comparable](t T, i interface{}) bool {
+	// Compare derived type value to interface.
+	return struct{ a, b T }{t, t} == i
+}
+
+func main() {
+	assert(f(3, 3))
+	assert(!f(3, 5))
+	assert(g(3, 3))
+	assert(!g(3, 5))
+	assert(h(myint(3), myint(3)))
+	assert(!h(myint(3), myint(5)))
+
+	type S struct{ a, b float64 }
+
+	assert(f(S{3, 5}, S{3, 5}))
+	assert(!f(S{3, 5}, S{4, 6}))
+	assert(g(S{3, 5}, S{3, 5}))
+	assert(!g(S{3, 5}, S{4, 6}))
+
+	assert(k(3, struct{ a, b int }{3, 3}))
+	assert(!k(3, struct{ a, b int }{3, 4}))
+}
+
+func assert(b bool) {
+	if !b {
+		panic("assertion failed")
+	}
+}
diff --git a/test/typeparam/fact.go b/test/typeparam/fact.go
index 16b2adf6fb71557566a4c23312d30885ad457c1d..e19cfe69565848da0f723186c99836bd0028f968 100644
--- a/test/typeparam/fact.go
+++ b/test/typeparam/fact.go
@@ -8,11 +8,11 @@ package main
 
 import "fmt"
 
-func fact[T interface { type int, int64, float64 }](n T) T {
-	if n == T(1) {
-		return T(1)
+func fact[T interface{ ~int | ~int64 | ~float64 }](n T) T {
+	if n == 1 {
+		return 1
 	}
-	return n * fact(n - T(1))
+	return n * fact(n-1)
 }
 
 func main() {
diff --git a/test/typeparam/factimp.dir/a.go b/test/typeparam/factimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..0bd73a88e7daef699992f7ce8756334f69f5e42a
--- /dev/null
+++ b/test/typeparam/factimp.dir/a.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func Fact[T interface{ int | int64 | float64 }](n T) T {
+	if n == 1 {
+		return 1
+	}
+	return n * Fact(n-1)
+}
diff --git a/test/typeparam/factimp.dir/main.go b/test/typeparam/factimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..c2238002aebf8e02b9e60e2a36ac0925706ffc5e
--- /dev/null
+++ b/test/typeparam/factimp.dir/main.go
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	const want = 120
+
+	if got := a.Fact(5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Fact[int64](5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Fact(5.0); got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+}
diff --git a/test/typeparam/factimp.go b/test/typeparam/factimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/factimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/graph.go b/test/typeparam/graph.go
index f2a2630ad09d60b94f780753dce0c68b78c626bc..cecf349a9ad7da758487ef03eccfc28f22d9751d 100644
--- a/test/typeparam/graph.go
+++ b/test/typeparam/graph.go
@@ -225,7 +225,6 @@ func TestShortestPath() {
 	}
 }
 
-
 func main() {
 	TestShortestPath()
 }
diff --git a/test/typeparam/ifaceconv.go b/test/typeparam/ifaceconv.go
new file mode 100644
index 0000000000000000000000000000000000000000..ee3a9e0dc3a83d7c2a3333cc7abce8b9c6f549c3
--- /dev/null
+++ b/test/typeparam/ifaceconv.go
@@ -0,0 +1,83 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that we can convert type parameters to both empty
+// and nonempty interfaces, and named and nonnamed versions
+// thereof.
+
+package main
+
+import "fmt"
+
+type E interface{}
+
+func f[T any](x T) interface{} {
+	var i interface{} = x
+	return i
+}
+
+func fs[T any](x T) interface{} {
+	y := []T{x}
+	var i interface{} = y
+	return i
+}
+
+func g[T any](x T) E {
+	var i E = x
+	return i
+}
+
+type C interface {
+	foo() int
+}
+
+type myInt int
+
+func (x myInt) foo() int {
+	return int(x + 1)
+}
+
+func h[T C](x T) interface{ foo() int } {
+	var i interface{ foo() int } = x
+	return i
+}
+func i[T C](x T) C {
+	var i C = x // conversion in assignment
+	return i
+}
+
+func j[T C](t T) C {
+	return C(t) // explicit conversion
+}
+
+func js[T any](x T) interface{} {
+	y := []T{x}
+	return interface{}(y)
+}
+
+func main() {
+	if got, want := f[int](7), 7; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := fs[int](7), []int{7}; got.([]int)[0] != want[0] {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := g[int](7), 7; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := h[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := i[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := j[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := js[int](7), []int{7}; got.([]int)[0] != want[0] {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+}
diff --git a/test/typeparam/index.go b/test/typeparam/index.go
index 83e65acdd006e20d0a6fc86be5d3b0a8841e4fe5..906f76d325c8d2cc511cfe2b74b0ba3198f35b58 100644
--- a/test/typeparam/index.go
+++ b/test/typeparam/index.go
@@ -11,7 +11,7 @@ import (
 )
 
 // Index returns the index of x in s, or -1 if not found.
-func index[T comparable](s []T, x T) int {
+func Index[T comparable](s []T, x T) int {
 	for i, v := range s {
 		// v and x are type T, which has the comparable
 		// constraint, so we can use == here.
@@ -26,21 +26,56 @@ type obj struct {
 	x int
 }
 
+type obj2 struct {
+	x int8
+	y float64
+}
+
+type obj3 struct {
+	x int64
+	y int8
+}
+
+type inner struct {
+	y int64
+	z int32
+}
+
+type obj4 struct {
+	x int32
+	s inner
+}
+
 func main() {
 	want := 2
 
 	vec1 := []string{"ab", "cd", "ef"}
-	if got := index(vec1, "ef"); got != want {
+	if got := Index(vec1, "ef"); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	vec2 := []byte{'c', '6', '@'}
-	if got := index(vec2, '@'); got != want {
+	if got := Index(vec2, '@'); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	vec3 := []*obj{&obj{2}, &obj{42}, &obj{1}}
-	if got := index(vec3, vec3[2]); got != want {
+	if got := Index(vec3, vec3[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec4 := []obj2{obj2{2, 3.0}, obj2{3, 4.0}, obj2{4, 5.0}}
+	if got := Index(vec4, vec4[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec5 := []obj3{obj3{2, 3}, obj3{3, 4}, obj3{4, 5}}
+	if got := Index(vec5, vec5[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec6 := []obj4{obj4{2, inner{3, 4}}, obj4{3, inner{4, 5}}, obj4{4, inner{5, 6}}}
+	if got := Index(vec6, vec6[2]); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 }
diff --git a/test/typeparam/interfacearg.go b/test/typeparam/interfacearg.go
index e2d85e3647b3742dca2f7acaa22ba11ef8cf990b..28ea3e3afbb7763f88c6e438832f678820babb72 100644
--- a/test/typeparam/interfacearg.go
+++ b/test/typeparam/interfacearg.go
@@ -9,23 +9,25 @@ package main
 type I interface{}
 
 type _S[T any] struct {
-	*T
+	x *T
 }
 
 // F is a non-generic function, but has a type _S[I] which is instantiated from a
 // generic type. Test that _S[I] is successfully exported.
 func F() {
 	v := _S[I]{}
-	if v.T != nil {
+	if v.x != nil {
 		panic(v)
 	}
 }
 
 // Testing the various combinations of method expressions.
 type S1 struct{}
+
 func (*S1) M() {}
 
 type S2 struct{}
+
 func (S2) M() {}
 
 func _F1[T interface{ M() }](t T) {
@@ -33,9 +35,9 @@ func _F1[T interface{ M() }](t T) {
 }
 
 func F2() {
-        _F1(&S1{})
-        _F1(S2{})
-        _F1(&S2{})
+	_F1(&S1{})
+	_F1(S2{})
+	_F1(&S2{})
 }
 
 func main() {
diff --git a/test/typeparam/issue39755.go b/test/typeparam/issue39755.go
new file mode 100644
index 0000000000000000000000000000000000000000..c4b6902eeade0580f494f698c6fb0892ddcc4ec5
--- /dev/null
+++ b/test/typeparam/issue39755.go
@@ -0,0 +1,27 @@
+// compile -G=3
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// copied from cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go
+
+package p
+
+func _[T interface{ ~map[string]int }](x T) {
+	_ = x == nil
+}
+
+// simplified test case from issue
+
+type PathParamsConstraint interface {
+	~map[string]string | ~[]struct{ key, value string }
+}
+
+type PathParams[T PathParamsConstraint] struct {
+	t T
+}
+
+func (pp *PathParams[T]) IsNil() bool {
+	return pp.t == nil // this must succeed
+}
diff --git a/test/typeparam/issue44688.go b/test/typeparam/issue44688.go
new file mode 100644
index 0000000000000000000000000000000000000000..5ebce72628ff6157e09ea9a4cbc75f7e6291643c
--- /dev/null
+++ b/test/typeparam/issue44688.go
@@ -0,0 +1,148 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// derived & expanded from cmd/compile/internal/types2/testdata/fixedbugs/issue44688.go2
+
+package main
+
+type A1[T any] struct {
+	val T
+}
+
+func (p *A1[T]) m1(val T) {
+	p.val = val
+}
+
+type A2[T any] interface {
+	m2(T)
+}
+
+type B1[T any] struct {
+	filler int
+	*A1[T]
+	A2[T]
+}
+
+type B2[T any] interface {
+	A2[T]
+}
+
+type ImpA2[T any] struct {
+	f T
+}
+
+func (a2 *ImpA2[T]) m2(s T) {
+	a2.f = s
+}
+
+type C[T any] struct {
+	filler1 int
+	filler2 int
+	B1[T]
+}
+
+type D[T any] struct {
+	filler1 int
+	filler2 int
+	filler3 int
+	C[T]
+}
+
+func test1[T any](arg T) {
+	// calling embedded methods
+	var b1 B1[T]
+	b1.A1 = &A1[T]{}
+	b1.A2 = &ImpA2[T]{}
+
+	b1.A1.m1(arg)
+	b1.m1(arg)
+
+	b1.A2.m2(arg)
+	b1.m2(arg)
+
+	var b2 B2[T]
+	b2 = &ImpA2[T]{}
+	b2.m2(arg)
+
+	// a deeper nesting
+	var d D[T]
+	d.C.B1.A1 = &A1[T]{}
+	d.C.B1.A2 = &ImpA2[T]{}
+	d.m1(arg)
+	d.m2(arg)
+
+	// calling method expressions
+	m1x := B1[T].m1
+	m1x(b1, arg)
+	m2x := B2[T].m2
+	m2x(b2, arg)
+
+	// calling method values
+	m1v := b1.m1
+	m1v(arg)
+	m2v := b1.m2
+	m2v(arg)
+	b2v := b2.m2
+	b2v(arg)
+}
+
+func test2() {
+	// calling embedded methods
+	var b1 B1[string]
+	b1.A1 = &A1[string]{}
+	b1.A2 = &ImpA2[string]{}
+
+	b1.A1.m1("")
+	b1.m1("")
+
+	b1.A2.m2("")
+	b1.m2("")
+
+	var b2 B2[string]
+	b2 = &ImpA2[string]{}
+	b2.m2("")
+
+	// a deeper nesting
+	var d D[string]
+	d.C.B1.A1 = &A1[string]{}
+	d.C.B1.A2 = &ImpA2[string]{}
+	d.m1("")
+	d.m2("")
+
+	// calling method expressions
+	m1x := B1[string].m1
+	m1x(b1, "")
+	m2x := B2[string].m2
+	m2x(b2, "")
+
+	// calling method values
+	m1v := b1.m1
+	m1v("")
+	m2v := b1.m2
+	m2v("")
+	b2v := b2.m2
+	b2v("")
+}
+
+// actual test case from issue
+
+type A[T any] struct{}
+
+func (*A[T]) f(T) {}
+
+type B[T any] struct{ A[T] }
+
+func test3() {
+	var b B[string]
+	b.A.f("")
+	b.f("")
+}
+
+func main() {
+	test1[string]("")
+	test2()
+	test3()
+}
diff --git a/test/typeparam/issue45547.go b/test/typeparam/issue45547.go
index 0a08d66b70e1f305edad82503bee5885353c52cd..b354d4d7f64b5fb81f47f7bbdf36e0121c2d418a 100644
--- a/test/typeparam/issue45547.go
+++ b/test/typeparam/issue45547.go
@@ -11,7 +11,7 @@ func f[T any]() (f, g T) { return f, g }
 // Tests for generic function instantiation on the right hande side of multi-value
 // assignments.
 
-func _() {
+func g() {
 	// Multi-value assignment within a function
 	var _, _ = f[int]()
 }
diff --git a/test/typeparam/issue45817.go b/test/typeparam/issue45817.go
new file mode 100644
index 0000000000000000000000000000000000000000..1efee3b0af2ecb9ed18790f94a0751bf99401259
--- /dev/null
+++ b/test/typeparam/issue45817.go
@@ -0,0 +1,26 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+)
+
+type s[T any] struct {
+	a T
+}
+
+func (x s[T]) f() T {
+	return x.a
+}
+func main() {
+	x := s[int]{a: 7}
+	f := x.f
+	if got, want := f(), 7; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/issue46472.go b/test/typeparam/issue46472.go
new file mode 100644
index 0000000000000000000000000000000000000000..cd4d923ef55e955d4f8b34925e4981527d1def78
--- /dev/null
+++ b/test/typeparam/issue46472.go
@@ -0,0 +1,20 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func foo[T any](d T) {
+	switch v := interface{}(d).(type) {
+	case string:
+		if v != "x" {
+			panic("unexpected v: " + v)
+		}
+	}
+
+}
+func main() {
+	foo("x")
+}
diff --git a/test/typeparam/issue46591.go b/test/typeparam/issue46591.go
new file mode 100644
index 0000000000000000000000000000000000000000..e7b9fa2b48956eccff31bf63248abf90cdd846cd
--- /dev/null
+++ b/test/typeparam/issue46591.go
@@ -0,0 +1,22 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type T[_ any] struct{}
+
+var m = map[interface{}]int{
+	T[struct{ int }]{}: 0,
+	T[struct {
+		int "x"
+	}]{}: 0,
+}
+
+func main() {
+	if len(m) != 2 {
+		panic(len(m))
+	}
+}
diff --git a/test/typeparam/issue47258.go b/test/typeparam/issue47258.go
new file mode 100644
index 0000000000000000000000000000000000000000..717329471e12252e4739dcf1d636edb134ba5a70
--- /dev/null
+++ b/test/typeparam/issue47258.go
@@ -0,0 +1,32 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+)
+
+type Numeric interface {
+	int32 | int64 | float64 | complex64
+}
+
+//go:noline
+func inc[T Numeric](x T) T {
+	x++
+	return x
+}
+func main() {
+	if got, want := inc(int32(5)), int32(6); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := inc(float64(5)), float64(6.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := inc(complex64(5)), complex64(6.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/issue47272.go b/test/typeparam/issue47272.go
new file mode 100644
index 0000000000000000000000000000000000000000..6771cb9901b29a2450340972961e0ce1edb94a67
--- /dev/null
+++ b/test/typeparam/issue47272.go
@@ -0,0 +1,55 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"errors"
+	"fmt"
+)
+
+type Option[T any] struct {
+	ok  bool
+	val T
+}
+
+func (o Option[T]) String() string {
+	if o.ok {
+		return fmt.Sprintf("Some(%v)", o.val)
+	}
+	return "None"
+}
+
+func Some[T any](val T) Option[T] { return Option[T]{ok: true, val: val} }
+func None[T any]() Option[T]      { return Option[T]{ok: false} }
+
+type Result[T, E any] struct {
+	ok  bool
+	val T
+	err E
+}
+
+func (r Result[T, E]) String() string {
+	if r.ok {
+		return fmt.Sprintf("Ok(%v)", r.val)
+	}
+	return fmt.Sprintf("Err(%v)", r.err)
+}
+
+func Ok[T, E any](val T) Result[T, E]  { return Result[T, E]{ok: true, val: val} }
+func Err[T, E any](err E) Result[T, E] { return Result[T, E]{ok: false, err: err} }
+
+func main() {
+	a := Some[int](1)
+	b := None[int]()
+	fmt.Println(a, b)
+
+	x := Ok[int, error](1)
+	y := Err[int, error](errors.New("test"))
+	fmt.Println(x, y)
+	// fmt.Println(x)
+	_, _, _, _ = a, b, x, y
+}
diff --git a/test/typeparam/issue47272.out b/test/typeparam/issue47272.out
new file mode 100644
index 0000000000000000000000000000000000000000..9c433faa9701c4ea915826ba37788b958265d849
--- /dev/null
+++ b/test/typeparam/issue47272.out
@@ -0,0 +1,2 @@
+Some(1) None
+Ok(1) Err(test)
diff --git a/test/typeparam/issue47514.go b/test/typeparam/issue47514.go
new file mode 100644
index 0000000000000000000000000000000000000000..947f254003ddae35b30f27c088baf0e65f148d90
--- /dev/null
+++ b/test/typeparam/issue47514.go
@@ -0,0 +1,20 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that closures inside a generic function are not exported,
+// even though not themselves generic.
+
+package main
+
+func Do[T any]() {
+	_ = func() string {
+		return ""
+	}
+}
+
+func main() {
+	Do[int]()
+}
diff --git a/test/typeparam/issue47514b.go b/test/typeparam/issue47514b.go
new file mode 100644
index 0000000000000000000000000000000000000000..5428a0edc5f306194b8e07a884489bde9b5ab552
--- /dev/null
+++ b/test/typeparam/issue47514b.go
@@ -0,0 +1,19 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func Do[T any](do func() (T, string)) {
+	_ = func() (T, string) {
+		return do()
+	}
+}
+
+func main() {
+	Do[int](func() (int, string) {
+		return 3, "3"
+	})
+}
diff --git a/test/typeparam/issue47684.go b/test/typeparam/issue47684.go
new file mode 100644
index 0000000000000000000000000000000000000000..2798b78ca8f57c411581e29a88eb47642b3efeaa
--- /dev/null
+++ b/test/typeparam/issue47684.go
@@ -0,0 +1,19 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[G any]() int {
+	return func() int {
+		return func() int {
+			return 0
+		}()
+	}()
+}
+
+func main() {
+	f[int]()
+}
diff --git a/test/typeparam/issue47684b.go b/test/typeparam/issue47684b.go
new file mode 100644
index 0000000000000000000000000000000000000000..c43ef8d16988c038dd0106ee344487b9c7ff1dd5
--- /dev/null
+++ b/test/typeparam/issue47684b.go
@@ -0,0 +1,23 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[G any]() interface{} {
+	return func() interface{} {
+		return func() interface{} {
+			var x G
+			return x
+		}()
+	}()
+}
+
+func main() {
+	x := f[int]()
+	if v, ok := x.(int); !ok || v != 0 {
+		panic("bad")
+	}
+}
diff --git a/test/typeparam/issue47684c.go b/test/typeparam/issue47684c.go
new file mode 100644
index 0000000000000000000000000000000000000000..32f1b66087e92f4869ab52763ee71b64d548ca43
--- /dev/null
+++ b/test/typeparam/issue47684c.go
@@ -0,0 +1,19 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[G any]() func()func()int {
+	return func() func()int {
+		return func() int {
+			return 0
+		}
+	}
+}
+
+func main() {
+	f[int]()()()
+}
diff --git a/test/typeparam/issue47713.go b/test/typeparam/issue47713.go
new file mode 100644
index 0000000000000000000000000000000000000000..a38eea19eb6274fd7a557c1bb8ef484c21b78fb0
--- /dev/null
+++ b/test/typeparam/issue47713.go
@@ -0,0 +1,52 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"encoding"
+	"fmt"
+)
+
+type Seralizable interface {
+	encoding.BinaryMarshaler
+	encoding.BinaryUnmarshaler
+}
+
+type SerDeString string
+
+func (s *SerDeString) UnmarshalBinary(in []byte) error {
+	*s = SerDeString(in)
+	return nil
+}
+
+func (s SerDeString) MarshalBinary() ([]byte, error) {
+	return []byte(s), nil
+}
+
+
+type GenericSerializable[T Seralizable] struct {
+	Key string
+	Value T
+}
+
+func (g GenericSerializable[T]) Send() {
+	out, err := g.Value.MarshalBinary()
+	if err != nil {
+		panic("bad")
+	}
+	var newval SerDeString
+	newval.UnmarshalBinary(out)
+	fmt.Printf("Sent %s\n", newval)
+}
+
+func main() {
+	val := SerDeString("asdf")
+	x := GenericSerializable[*SerDeString]{
+		Value: &val,
+	}
+	x.Send()
+}
diff --git a/test/typeparam/issue47713.out b/test/typeparam/issue47713.out
new file mode 100644
index 0000000000000000000000000000000000000000..a6e77197d81c62f4fae6cdb17dcc962ebbca3aca
--- /dev/null
+++ b/test/typeparam/issue47713.out
@@ -0,0 +1 @@
+Sent asdf
diff --git a/test/typeparam/issue47716.go b/test/typeparam/issue47716.go
new file mode 100644
index 0000000000000000000000000000000000000000..7f34fcb21f363841e09599a1db20ddc4ea93972a
--- /dev/null
+++ b/test/typeparam/issue47716.go
@@ -0,0 +1,68 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+// size returns the size of type T
+func size[T any](x T) uintptr {
+	return unsafe.Sizeof(x)
+}
+
+// size returns the alignment of type T
+func align[T any](x T) uintptr {
+	return unsafe.Alignof(x)
+}
+
+type Tstruct[T any] struct {
+	f1 T
+	f2 int
+}
+
+// offset returns the offset of field f2 in the generic type Tstruct
+func (r *Tstruct[T]) offset() uintptr {
+	return unsafe.Offsetof(r.f2)
+}
+
+func main() {
+	v1 := int(5)
+	if got, want := size(v1), unsafe.Sizeof(v1); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := align(v1), unsafe.Alignof(v1); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	v2 := "abc"
+	if got, want := size(v2), unsafe.Sizeof(v2); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := align(v2), unsafe.Alignof(v2); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	var v3 Tstruct[int]
+	if got, want := unsafe.Offsetof(v3.f2), unsafe.Sizeof(v1); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	var v4 Tstruct[interface{}]
+	var v5 interface{}
+	if got, want := unsafe.Offsetof(v4.f2), unsafe.Sizeof(v5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got, want := v3.offset(), unsafe.Offsetof(v3.f2); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := v4.offset(), unsafe.Offsetof(v4.f2); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/issue47723.go b/test/typeparam/issue47723.go
new file mode 100644
index 0000000000000000000000000000000000000000..9ef60402b236fef681f118a553fd1a306e1dbe7a
--- /dev/null
+++ b/test/typeparam/issue47723.go
@@ -0,0 +1,23 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[_ any]() int {
+	var a [1]int
+	_ = func() int {
+		return func() int {
+			return 0
+		}()
+	}()
+	return a[func() int {
+		return 0
+	}()]
+}
+
+func main() {
+	f[int]()
+}
diff --git a/test/typeparam/issue47740.go b/test/typeparam/issue47740.go
new file mode 100644
index 0000000000000000000000000000000000000000..a8c6839de329576059543fc32276647a91184822
--- /dev/null
+++ b/test/typeparam/issue47740.go
@@ -0,0 +1,37 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+type Exp[Ty any] interface {
+	Eval() Ty
+}
+
+type Lit[Ty any] Ty
+
+func (lit Lit[Ty]) Eval() Ty       { return Ty(lit) }
+func (lit Lit[Ty]) String() string { return fmt.Sprintf("(lit %v)", Ty(lit)) }
+
+type Eq[Ty any] struct {
+	a Exp[Ty]
+	b Exp[Ty]
+}
+
+func (e Eq[Ty]) String() string {
+	return fmt.Sprintf("(eq %v %v)", e.a, e.b)
+}
+
+var (
+	e0 = Eq[int]{Lit[int](128), Lit[int](64)}
+	e1 = Eq[bool]{Lit[bool](true), Lit[bool](true)}
+)
+
+func main() {
+	fmt.Printf("%v\n", e0)
+	fmt.Printf("%v\n", e1)
+}
diff --git a/test/typeparam/issue47740.out b/test/typeparam/issue47740.out
new file mode 100644
index 0000000000000000000000000000000000000000..f23c310f66511d77da053b07fa97edb655845e09
--- /dev/null
+++ b/test/typeparam/issue47740.out
@@ -0,0 +1,2 @@
+(eq (lit 128) (lit 64))
+(eq (lit true) (lit true))
diff --git a/test/typeparam/issue47740b.go b/test/typeparam/issue47740b.go
new file mode 100644
index 0000000000000000000000000000000000000000..2a91d35eb42f214c9eff31dfc98fe9349395688e
--- /dev/null
+++ b/test/typeparam/issue47740b.go
@@ -0,0 +1,23 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "reflect"
+
+type S[T any] struct {
+	a interface{}
+}
+
+func (e S[T]) M() {
+	v := reflect.ValueOf(e.a)
+	_, _ = v.Interface().(int)
+}
+
+func main() {
+	e := S[int]{0}
+	e.M()
+}
diff --git a/test/typeparam/issue47775.dir/b.go b/test/typeparam/issue47775.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..b6d7ba97c59c11efb413b23107569e540db3f952
--- /dev/null
+++ b/test/typeparam/issue47775.dir/b.go
@@ -0,0 +1,19 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+type C[T any] struct {
+}
+
+func (c *C[T]) reset() {
+}
+
+func New[T any]() {
+	c := &C[T]{}
+	z(c.reset)
+}
+
+func z(interface{}) {
+}
diff --git a/test/typeparam/issue47775.dir/main.go b/test/typeparam/issue47775.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..ed284ddfc6d0807f944375dac5111c897d6bc8a6
--- /dev/null
+++ b/test/typeparam/issue47775.dir/main.go
@@ -0,0 +1,11 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "b"
+
+func main() {
+	b.New[int]()
+}
diff --git a/test/typeparam/issue47775.go b/test/typeparam/issue47775.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/issue47775.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/issue47775b.go b/test/typeparam/issue47775b.go
new file mode 100644
index 0000000000000000000000000000000000000000..6d3fc8df97b5700c000eb58ef72e1b20a6c1c9b4
--- /dev/null
+++ b/test/typeparam/issue47775b.go
@@ -0,0 +1,28 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type C[T any] struct {
+}
+
+func (c *C[T]) reset() {
+}
+
+func New[T any]() {
+	c := &C[T]{}
+	i = c.reset
+	z(c.reset)
+}
+
+var i interface{}
+
+func z(interface{}) {
+}
+
+func main() {
+	New[int]()
+}
diff --git a/test/typeparam/issue47877.go b/test/typeparam/issue47877.go
new file mode 100644
index 0000000000000000000000000000000000000000..0a834590dded3b04cd42e9f1b63453cc851dd6fa
--- /dev/null
+++ b/test/typeparam/issue47877.go
@@ -0,0 +1,23 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type Map[K comparable, V any] struct {
+        m map[K]V
+}
+
+func NewMap[K comparable, V any]() Map[K, V] {
+        return Map[K, V]{m: map[K]V{}}
+}
+
+func (m Map[K, V]) Get(key K) V {
+        return m.m[key]
+}
+
+func main() {
+        _ = NewMap[int, struct{}]()
+}
diff --git a/test/typeparam/issue47896.go b/test/typeparam/issue47896.go
new file mode 100644
index 0000000000000000000000000000000000000000..1b2f265cc112123a5c3f210bc3ec24350d9b6b87
--- /dev/null
+++ b/test/typeparam/issue47896.go
@@ -0,0 +1,74 @@
+//  compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"database/sql"
+)
+
+// Collection generic interface which things can be added to.
+type Collection[T any] interface {
+	Add(T)
+}
+
+// Slice generic slice implementation of a Collection
+type Slice[T any] []*T
+
+func (s *Slice[T]) Add(t *T) {
+	*s = append(*s, t)
+}
+
+type Scanner interface {
+	Scan(...interface{}) error
+}
+
+type Mapper[T any] func(s Scanner, t T) error
+
+type Repository[T any] struct {
+	db *sql.DB
+}
+
+func (r *Repository[T]) scan(rows *sql.Rows, m Mapper[*T], c Collection[*T]) error {
+	for rows.Next() {
+		t := new(T)
+		if err := m(rows, t); err != nil {
+			return err
+		}
+		c.Add(t)
+	}
+	return rows.Err()
+}
+
+func (r *Repository[T]) query(query string, m Mapper[*T], c Collection[*T]) error {
+	rows, err := r.db.Query(query)
+	if err != nil {
+		return err
+	}
+	if err := r.scan(rows, m, c); err != nil {
+		rows.Close()
+		return err
+	}
+	return rows.Close()
+}
+
+type Actor struct {
+	ActorID   uint16
+	FirstName string
+	LastName  string
+}
+
+type ActorRepository struct {
+	r Repository[Actor]
+}
+
+func (ActorRepository) scan(s Scanner, a *Actor) error {
+	return s.Scan(&a.ActorID, &a.FirstName, &a.LastName)
+}
+
+func (r *ActorRepository) SelectAll(c Collection[*Actor]) error {
+	return r.r.query("SELECT `actor_id`, `first_name`, `last_name` FROM `actor` LIMIT 10", r.scan, c)
+}
diff --git a/test/typeparam/issue47924.go b/test/typeparam/issue47924.go
new file mode 100644
index 0000000000000000000000000000000000000000..1d1bab3bf918f9bdaacc3f2948396fbab6aa706a
--- /dev/null
+++ b/test/typeparam/issue47924.go
@@ -0,0 +1,15 @@
+// compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Cache[K any] struct{}
+
+func (c Cache[K]) foo(x interface{}, f func(K) bool) {
+	f(x.(K))
+}
+
+var _ Cache[int]
diff --git a/test/typeparam/list.go b/test/typeparam/list.go
index 579078f02f7b1397cd5de521def0c82f086d6dae..adfe72f1de1ea2cd899766e316f6be3ab7456a1c 100644
--- a/test/typeparam/list.go
+++ b/test/typeparam/list.go
@@ -11,10 +11,10 @@ import (
 )
 
 type Ordered interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64,
-                string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 // _List is a linked list of ordered values of type T.
@@ -34,9 +34,9 @@ func (l *_List[T]) Largest() T {
 }
 
 type OrderedNum interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // _ListNum is a linked _List of ordered numeric values of type T.
@@ -64,40 +64,40 @@ func main() {
 	i2 := &_List[int]{i3, 3}
 	i1 := &_List[int]{i2, 2}
 	if got, want := i1.Largest(), 3; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	b3 := &_List[byte]{nil, byte(1)}
 	b2 := &_List[byte]{b3, byte(3)}
 	b1 := &_List[byte]{b2, byte(2)}
 	if got, want := b1.Largest(), byte(3); got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	f3 := &_List[float64]{nil, 13.5}
 	f2 := &_List[float64]{f3, 1.2}
 	f1 := &_List[float64]{f2, 4.5}
 	if got, want := f1.Largest(), 13.5; got != want {
-                panic(fmt.Sprintf("got %f, want %f", got, want))
+		panic(fmt.Sprintf("got %f, want %f", got, want))
 	}
 
 	s3 := &_List[string]{nil, "dd"}
 	s2 := &_List[string]{s3, "aa"}
 	s1 := &_List[string]{s2, "bb"}
 	if got, want := s1.Largest(), "dd"; got != want {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	j3 := &_ListNum[int]{nil, 1}
 	j2 := &_ListNum[int]{j3, 32}
 	j1 := &_ListNum[int]{j2, 2}
 	if got, want := j1.ClippedLargest(), 2; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 	g3 := &_ListNum[float64]{nil, 13.5}
 	g2 := &_ListNum[float64]{g3, 1.2}
 	g1 := &_ListNum[float64]{g2, 4.5}
 	if got, want := g1.ClippedLargest(), 4.5; got != want {
-                panic(fmt.Sprintf("got %f, want %f", got, want))
+		panic(fmt.Sprintf("got %f, want %f", got, want))
 	}
 }
diff --git a/test/typeparam/list2.go b/test/typeparam/list2.go
index 385193d87657c7ab1172e2bd5170ed3461f377ba..e7f346c78e13c7addd209c42fb50904931f5925b 100644
--- a/test/typeparam/list2.go
+++ b/test/typeparam/list2.go
@@ -50,7 +50,7 @@ func (e *_Element[T]) Prev() *_Element[T] {
 // The zero value for _List is an empty list ready to use.
 type _List[T any] struct {
 	root _Element[T] // sentinel list element, only &root, root.prev, and root.next are used
-	len  int     // current list length excluding (this) sentinel element
+	len  int         // current list length excluding (this) sentinel element
 }
 
 // Init initializes or clears list l.
@@ -594,8 +594,15 @@ func TestTransform() {
 	checkList(l2, []interface{}{"1", "2"})
 }
 
-
 func main() {
 	TestList()
+	TestExtending()
+	TestRemove()
+	TestIssue4103()
+	TestIssue6349()
+	TestMove()
+	TestZeroList()
+	TestInsertBeforeUnknownMark()
+	TestInsertAfterUnknownMark()
+	TestTransform()
 }
-
diff --git a/test/typeparam/listimp.dir/a.go b/test/typeparam/listimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..bf1641af9c384d8a0baeb4ff41fe87501aa4bf95
--- /dev/null
+++ b/test/typeparam/listimp.dir/a.go
@@ -0,0 +1,53 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
+}
+
+// List is a linked list of ordered values of type T.
+type List[T Ordered] struct {
+	Next *List[T]
+	Val  T
+}
+
+func (l *List[T]) Largest() T {
+	var max T
+	for p := l; p != nil; p = p.Next {
+		if p.Val > max {
+			max = p.Val
+		}
+	}
+	return max
+}
+
+type OrderedNum interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
+}
+
+// ListNum is a linked _List of ordered numeric values of type T.
+type ListNum[T OrderedNum] struct {
+	Next *ListNum[T]
+	Val  T
+}
+
+const Clip = 5
+
+// clippedLargest returns the largest in the list of OrderNums, but a max of 5.
+func (l *ListNum[T]) ClippedLargest() T {
+	var max T
+	for p := l; p != nil; p = p.Next {
+		if p.Val > max && p.Val < Clip {
+			max = p.Val
+		}
+	}
+	return max
+}
diff --git a/test/typeparam/listimp.dir/main.go b/test/typeparam/listimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..985ff59a18994bbb9c5c383a763d9982888be160
--- /dev/null
+++ b/test/typeparam/listimp.dir/main.go
@@ -0,0 +1,52 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	i3 := &a.List[int]{nil, 1}
+	i2 := &a.List[int]{i3, 3}
+	i1 := &a.List[int]{i2, 2}
+	if got, want := i1.Largest(), 3; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	b3 := &a.List[byte]{nil, byte(1)}
+	b2 := &a.List[byte]{b3, byte(3)}
+	b1 := &a.List[byte]{b2, byte(2)}
+	if got, want := b1.Largest(), byte(3); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	f3 := &a.List[float64]{nil, 13.5}
+	f2 := &a.List[float64]{f3, 1.2}
+	f1 := &a.List[float64]{f2, 4.5}
+	if got, want := f1.Largest(), 13.5; got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+
+	s3 := &a.List[string]{nil, "dd"}
+	s2 := &a.List[string]{s3, "aa"}
+	s1 := &a.List[string]{s2, "bb"}
+	if got, want := s1.Largest(), "dd"; got != want {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+	j3 := &a.ListNum[int]{nil, 1}
+	j2 := &a.ListNum[int]{j3, 32}
+	j1 := &a.ListNum[int]{j2, 2}
+	if got, want := j1.ClippedLargest(), 2; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	g3 := &a.ListNum[float64]{nil, 13.5}
+	g2 := &a.ListNum[float64]{g3, 1.2}
+	g1 := &a.ListNum[float64]{g2, 4.5}
+	if got, want := g1.ClippedLargest(), 4.5; got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+}
diff --git a/test/typeparam/listimp.go b/test/typeparam/listimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/listimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/listimp2.dir/a.go b/test/typeparam/listimp2.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..3a7dfc3999a0db856c877a5cc2c4f21c899e801c
--- /dev/null
+++ b/test/typeparam/listimp2.dir/a.go
@@ -0,0 +1,298 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"fmt"
+)
+
+// Element is an element of a linked list.
+type Element[T any] struct {
+	// Next and previous pointers in the doubly-linked list of elements.
+	// To simplify the implementation, internally a list l is implemented
+	// as a ring, such that &l.root is both the next element of the last
+	// list element (l.Back()) and the previous element of the first list
+	// element (l.Front()).
+	next, prev *Element[T]
+
+	// The list to which this element belongs.
+	list *List[T]
+
+	// The value stored with this element.
+	Value T
+}
+
+// Next returns the next list element or nil.
+func (e *Element[T]) Next() *Element[T] {
+	if p := e.next; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// Prev returns the previous list element or nil.
+func (e *Element[T]) Prev() *Element[T] {
+	if p := e.prev; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// List represents a doubly linked list.
+// The zero value for List is an empty list ready to use.
+type List[T any] struct {
+	root Element[T] // sentinel list element, only &root, root.prev, and root.next are used
+	len  int        // current list length excluding (this) sentinel element
+}
+
+// Init initializes or clears list l.
+func (l *List[T]) Init() *List[T] {
+	l.root.next = &l.root
+	l.root.prev = &l.root
+	l.len = 0
+	return l
+}
+
+// New returns an initialized list.
+func New[T any]() *List[T] { return new(List[T]).Init() }
+
+// Len returns the number of elements of list l.
+// The complexity is O(1).
+func (l *List[_]) Len() int { return l.len }
+
+// Front returns the first element of list l or nil if the list is empty.
+func (l *List[T]) Front() *Element[T] {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.next
+}
+
+// Back returns the last element of list l or nil if the list is empty.
+func (l *List[T]) Back() *Element[T] {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.prev
+}
+
+// lazyInit lazily initializes a zero List value.
+func (l *List[_]) lazyInit() {
+	if l.root.next == nil {
+		l.Init()
+	}
+}
+
+// insert inserts e after at, increments l.len, and returns e.
+func (l *List[T]) insert(e, at *Element[T]) *Element[T] {
+	e.prev = at
+	e.next = at.next
+	e.prev.next = e
+	e.next.prev = e
+	e.list = l
+	l.len++
+	return e
+}
+
+// insertValue is a convenience wrapper for insert(&Element[T]{Value: v}, at).
+func (l *List[T]) insertValue(v T, at *Element[T]) *Element[T] {
+	return l.insert(&Element[T]{Value: v}, at)
+}
+
+// remove removes e from its list, decrements l.len, and returns e.
+func (l *List[T]) remove(e *Element[T]) *Element[T] {
+	e.prev.next = e.next
+	e.next.prev = e.prev
+	e.next = nil // avoid memory leaks
+	e.prev = nil // avoid memory leaks
+	e.list = nil
+	l.len--
+	return e
+}
+
+// move moves e to next to at and returns e.
+func (l *List[T]) move(e, at *Element[T]) *Element[T] {
+	if e == at {
+		return e
+	}
+	e.prev.next = e.next
+	e.next.prev = e.prev
+
+	e.prev = at
+	e.next = at.next
+	e.prev.next = e
+	e.next.prev = e
+
+	return e
+}
+
+// Remove removes e from l if e is an element of list l.
+// It returns the element value e.Value.
+// The element must not be nil.
+func (l *List[T]) Remove(e *Element[T]) T {
+	if e.list == l {
+		// if e.list == l, l must have been initialized when e was inserted
+		// in l or l == nil (e is a zero Element) and l.remove will crash
+		l.remove(e)
+	}
+	return e.Value
+}
+
+// PushFront inserts a new element e with value v at the front of list l and returns e.
+func (l *List[T]) PushFront(v T) *Element[T] {
+	l.lazyInit()
+	return l.insertValue(v, &l.root)
+}
+
+// PushBack inserts a new element e with value v at the back of list l and returns e.
+func (l *List[T]) PushBack(v T) *Element[T] {
+	l.lazyInit()
+	return l.insertValue(v, l.root.prev)
+}
+
+// InsertBefore inserts a new element e with value v immediately before mark and returns e.
+// If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
+func (l *List[T]) InsertBefore(v T, mark *Element[T]) *Element[T] {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in List.Remove about initialization of l
+	return l.insertValue(v, mark.prev)
+}
+
+// InsertAfter inserts a new element e with value v immediately after mark and returns e.
+// If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
+func (l *List[T]) InsertAfter(v T, mark *Element[T]) *Element[T] {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in List.Remove about initialization of l
+	return l.insertValue(v, mark)
+}
+
+// MoveToFront moves element e to the front of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *List[T]) MoveToFront(e *Element[T]) {
+	if e.list != l || l.root.next == e {
+		return
+	}
+	// see comment in List.Remove about initialization of l
+	l.move(e, &l.root)
+}
+
+// MoveToBack moves element e to the back of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *List[T]) MoveToBack(e *Element[T]) {
+	if e.list != l || l.root.prev == e {
+		return
+	}
+	// see comment in List.Remove about initialization of l
+	l.move(e, l.root.prev)
+}
+
+// MoveBefore moves element e to its new position before mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *List[T]) MoveBefore(e, mark *Element[T]) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.move(e, mark.prev)
+}
+
+// MoveAfter moves element e to its new position after mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *List[T]) MoveAfter(e, mark *Element[T]) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.move(e, mark)
+}
+
+// PushBackList inserts a copy of an other list at the back of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *List[T]) PushBackList(other *List[T]) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
+		l.insertValue(e.Value, l.root.prev)
+	}
+}
+
+// PushFrontList inserts a copy of an other list at the front of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *List[T]) PushFrontList(other *List[T]) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
+		l.insertValue(e.Value, &l.root)
+	}
+}
+
+// Transform runs a transform function on a list returning a new list.
+func Transform[TElem1, TElem2 any](lst *List[TElem1], f func(TElem1) TElem2) *List[TElem2] {
+	ret := New[TElem2]()
+	for p := lst.Front(); p != nil; p = p.Next() {
+		ret.PushBack(f(p.Value))
+	}
+	return ret
+}
+
+func CheckListLen[T any](l *List[T], len int) bool {
+	if n := l.Len(); n != len {
+		panic(fmt.Sprintf("l.Len() = %d, want %d", n, len))
+		return false
+	}
+	return true
+}
+
+func CheckListPointers[T any](l *List[T], es []*Element[T]) {
+	root := &l.root
+
+	if !CheckListLen(l, len(es)) {
+		return
+	}
+
+	// zero length lists must be the zero value or properly initialized (sentinel circle)
+	if len(es) == 0 {
+		if l.root.next != nil && l.root.next != root || l.root.prev != nil && l.root.prev != root {
+			panic(fmt.Sprintf("l.root.next = %p, l.root.prev = %p; both should both be nil or %p", l.root.next, l.root.prev, root))
+		}
+		return
+	}
+	// len(es) > 0
+
+	// check internal and external prev/next connections
+	for i, e := range es {
+		prev := root
+		Prev := (*Element[T])(nil)
+		if i > 0 {
+			prev = es[i-1]
+			Prev = prev
+		}
+		if p := e.prev; p != prev {
+			panic(fmt.Sprintf("elt[%d](%p).prev = %p, want %p", i, e, p, prev))
+		}
+		if p := e.Prev(); p != Prev {
+			panic(fmt.Sprintf("elt[%d](%p).Prev() = %p, want %p", i, e, p, Prev))
+		}
+
+		next := root
+		Next := (*Element[T])(nil)
+		if i < len(es)-1 {
+			next = es[i+1]
+			Next = next
+		}
+		if n := e.next; n != next {
+			panic(fmt.Sprintf("elt[%d](%p).next = %p, want %p", i, e, n, next))
+		}
+		if n := e.Next(); n != Next {
+			panic(fmt.Sprintf("elt[%d](%p).Next() = %p, want %p", i, e, n, Next))
+		}
+	}
+}
diff --git a/test/typeparam/listimp2.dir/main.go b/test/typeparam/listimp2.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..226e1a9a571bde4b654e44bd9e52ce86bdc019c5
--- /dev/null
+++ b/test/typeparam/listimp2.dir/main.go
@@ -0,0 +1,315 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"strconv"
+)
+
+func TestList() {
+	l := a.New[string]()
+	a.CheckListPointers(l, []*(a.Element[string]){})
+
+	// Single element list
+	e := l.PushFront("a")
+	a.CheckListPointers(l, []*(a.Element[string]){e})
+	l.MoveToFront(e)
+	a.CheckListPointers(l, []*(a.Element[string]){e})
+	l.MoveToBack(e)
+	a.CheckListPointers(l, []*(a.Element[string]){e})
+	l.Remove(e)
+	a.CheckListPointers(l, []*(a.Element[string]){})
+
+	// Bigger list
+	l2 := a.New[int]()
+	e2 := l2.PushFront(2)
+	e1 := l2.PushFront(1)
+	e3 := l2.PushBack(3)
+	e4 := l2.PushBack(600)
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e2, e3, e4})
+
+	l2.Remove(e2)
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e3, e4})
+
+	l2.MoveToFront(e3) // move from middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e3, e1, e4})
+
+	l2.MoveToFront(e1)
+	l2.MoveToBack(e3) // move from middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3})
+
+	l2.MoveToFront(e3) // move from back
+	a.CheckListPointers(l2, []*(a.Element[int]){e3, e1, e4})
+	l2.MoveToFront(e3) // should be no-op
+	a.CheckListPointers(l2, []*(a.Element[int]){e3, e1, e4})
+
+	l2.MoveToBack(e3) // move from front
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3})
+	l2.MoveToBack(e3) // should be no-op
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3})
+
+	e2 = l2.InsertBefore(2, e1) // insert before front
+	a.CheckListPointers(l2, []*(a.Element[int]){e2, e1, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertBefore(2, e4) // insert before middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e2, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertBefore(2, e3) // insert before back
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e2, e3})
+	l2.Remove(e2)
+
+	e2 = l2.InsertAfter(2, e1) // insert after front
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e2, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertAfter(2, e4) // insert after middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e2, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertAfter(2, e3) // insert after back
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3, e2})
+	l2.Remove(e2)
+
+	// Check standard iteration.
+	sum := 0
+	for e := l2.Front(); e != nil; e = e.Next() {
+		sum += e.Value
+	}
+	if sum != 604 {
+		panic(fmt.Sprintf("sum over l = %d, want 604", sum))
+	}
+
+	// Clear all elements by iterating
+	var next *a.Element[int]
+	for e := l2.Front(); e != nil; e = next {
+		next = e.Next()
+		l2.Remove(e)
+	}
+	a.CheckListPointers(l2, []*(a.Element[int]){})
+}
+
+func checkList[T comparable](l *a.List[T], es []interface{}) {
+	if !a.CheckListLen(l, len(es)) {
+		return
+	}
+
+	i := 0
+	for e := l.Front(); e != nil; e = e.Next() {
+		le := e.Value
+		// Comparison between a generically-typed variable le and an interface.
+		if le != es[i] {
+			panic(fmt.Sprintf("elt[%d].Value = %v, want %v", i, le, es[i]))
+		}
+		i++
+	}
+}
+
+func TestExtending() {
+	l1 := a.New[int]()
+	l2 := a.New[int]()
+
+	l1.PushBack(1)
+	l1.PushBack(2)
+	l1.PushBack(3)
+
+	l2.PushBack(4)
+	l2.PushBack(5)
+
+	l3 := a.New[int]()
+	l3.PushBackList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushBackList(l2)
+	checkList(l3, []interface{}{1, 2, 3, 4, 5})
+
+	l3 = a.New[int]()
+	l3.PushFrontList(l2)
+	checkList(l3, []interface{}{4, 5})
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1, 2, 3, 4, 5})
+
+	checkList(l1, []interface{}{1, 2, 3})
+	checkList(l2, []interface{}{4, 5})
+
+	l3 = a.New[int]()
+	l3.PushBackList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushBackList(l3)
+	checkList(l3, []interface{}{1, 2, 3, 1, 2, 3})
+
+	l3 = a.New[int]()
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushFrontList(l3)
+	checkList(l3, []interface{}{1, 2, 3, 1, 2, 3})
+
+	l3 = a.New[int]()
+	l1.PushBackList(l3)
+	checkList(l1, []interface{}{1, 2, 3})
+	l1.PushFrontList(l3)
+	checkList(l1, []interface{}{1, 2, 3})
+}
+
+func TestRemove() {
+	l := a.New[int]()
+	e1 := l.PushBack(1)
+	e2 := l.PushBack(2)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2})
+	e := l.Front()
+	l.Remove(e)
+	a.CheckListPointers(l, []*(a.Element[int]){e2})
+	l.Remove(e)
+	a.CheckListPointers(l, []*(a.Element[int]){e2})
+}
+
+func TestIssue4103() {
+	l1 := a.New[int]()
+	l1.PushBack(1)
+	l1.PushBack(2)
+
+	l2 := a.New[int]()
+	l2.PushBack(3)
+	l2.PushBack(4)
+
+	e := l1.Front()
+	l2.Remove(e) // l2 should not change because e is not an element of l2
+	if n := l2.Len(); n != 2 {
+		panic(fmt.Sprintf("l2.Len() = %d, want 2", n))
+	}
+
+	l1.InsertBefore(8, e)
+	if n := l1.Len(); n != 3 {
+		panic(fmt.Sprintf("l1.Len() = %d, want 3", n))
+	}
+}
+
+func TestIssue6349() {
+	l := a.New[int]()
+	l.PushBack(1)
+	l.PushBack(2)
+
+	e := l.Front()
+	l.Remove(e)
+	if e.Value != 1 {
+		panic(fmt.Sprintf("e.value = %d, want 1", e.Value))
+	}
+	if e.Next() != nil {
+		panic(fmt.Sprintf("e.Next() != nil"))
+	}
+	if e.Prev() != nil {
+		panic(fmt.Sprintf("e.Prev() != nil"))
+	}
+}
+
+func TestMove() {
+	l := a.New[int]()
+	e1 := l.PushBack(1)
+	e2 := l.PushBack(2)
+	e3 := l.PushBack(3)
+	e4 := l.PushBack(4)
+
+	l.MoveAfter(e3, e3)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+	l.MoveBefore(e2, e2)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+
+	l.MoveAfter(e3, e2)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+	l.MoveBefore(e2, e3)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+
+	l.MoveBefore(e2, e4)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e3, e2, e4})
+	e2, e3 = e3, e2
+
+	l.MoveBefore(e4, e1)
+	a.CheckListPointers(l, []*(a.Element[int]){e4, e1, e2, e3})
+	e1, e2, e3, e4 = e4, e1, e2, e3
+
+	l.MoveAfter(e4, e1)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e4, e2, e3})
+	e2, e3, e4 = e4, e2, e3
+
+	l.MoveAfter(e2, e3)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e3, e2, e4})
+	e2, e3 = e3, e2
+}
+
+// Test PushFront, PushBack, PushFrontList, PushBackList with uninitialized a.List
+func TestZeroList() {
+	var l1 = new(a.List[int])
+	l1.PushFront(1)
+	checkList(l1, []interface{}{1})
+
+	var l2 = new(a.List[int])
+	l2.PushBack(1)
+	checkList(l2, []interface{}{1})
+
+	var l3 = new(a.List[int])
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1})
+
+	var l4 = new(a.List[int])
+	l4.PushBackList(l2)
+	checkList(l4, []interface{}{1})
+}
+
+// Test that a list l is not modified when calling InsertBefore with a mark that is not an element of l.
+func TestInsertBeforeUnknownMark() {
+	var l a.List[int]
+	l.PushBack(1)
+	l.PushBack(2)
+	l.PushBack(3)
+	l.InsertBefore(1, new(a.Element[int]))
+	checkList(&l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling InsertAfter with a mark that is not an element of l.
+func TestInsertAfterUnknownMark() {
+	var l a.List[int]
+	l.PushBack(1)
+	l.PushBack(2)
+	l.PushBack(3)
+	l.InsertAfter(1, new(a.Element[int]))
+	checkList(&l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling MoveAfter or MoveBefore with a mark that is not an element of l.
+func TestMoveUnknownMark() {
+	var l1 a.List[int]
+	e1 := l1.PushBack(1)
+
+	var l2 a.List[int]
+	e2 := l2.PushBack(2)
+
+	l1.MoveAfter(e1, e2)
+	checkList(&l1, []interface{}{1})
+	checkList(&l2, []interface{}{2})
+
+	l1.MoveBefore(e1, e2)
+	checkList(&l1, []interface{}{1})
+	checkList(&l2, []interface{}{2})
+}
+
+// Test the Transform function.
+func TestTransform() {
+	l1 := a.New[int]()
+	l1.PushBack(1)
+	l1.PushBack(2)
+	l2 := a.Transform(l1, strconv.Itoa)
+	checkList(l2, []interface{}{"1", "2"})
+}
+
+func main() {
+	TestList()
+	TestExtending()
+	TestRemove()
+	TestIssue4103()
+	TestIssue6349()
+	TestMove()
+	TestZeroList()
+	TestInsertBeforeUnknownMark()
+	TestInsertAfterUnknownMark()
+	TestTransform()
+}
diff --git a/test/typeparam/listimp2.go b/test/typeparam/listimp2.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/listimp2.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/lockable.go b/test/typeparam/lockable.go
index d53817521f30c8529fe9c3e4876eb7a5bddad553..9b20d87bb77e53cbf345876ca23471e970271f6b 100644
--- a/test/typeparam/lockable.go
+++ b/test/typeparam/lockable.go
@@ -8,29 +8,29 @@ package main
 
 import "sync"
 
-// A _Lockable is a value that may be safely simultaneously accessed
+// A Lockable is a value that may be safely simultaneously accessed
 // from multiple goroutines via the Get and Set methods.
-type _Lockable[T any] struct {
-	T
+type Lockable[T any] struct {
+	x  T
 	mu sync.Mutex
 }
 
-// Get returns the value stored in a _Lockable.
-func (l *_Lockable[T]) get() T {
+// Get returns the value stored in a Lockable.
+func (l *Lockable[T]) get() T {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	return l.T
+	return l.x
 }
 
-// set sets the value in a _Lockable.
-func (l *_Lockable[T]) set(v T) {
+// set sets the value in a Lockable.
+func (l *Lockable[T]) set(v T) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	l.T = v
+	l.x = v
 }
 
 func main() {
-	sl := _Lockable[string]{T: "a"}
+	sl := Lockable[string]{x: "a"}
 	if got := sl.get(); got != "a" {
 		panic(got)
 	}
@@ -39,7 +39,7 @@ func main() {
 		panic(got)
 	}
 
-	il := _Lockable[int]{T: 1}
+	il := Lockable[int]{x: 1}
 	if got := il.get(); got != 1 {
 		panic(got)
 	}
diff --git a/test/typeparam/mapimp.dir/a.go b/test/typeparam/mapimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..cbfa80ac6b1d338bf40a4d6c76da0f3f419c60b2
--- /dev/null
+++ b/test/typeparam/mapimp.dir/a.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+// Map calls the function f on every element of the slice s,
+// returning a new slice of the results.
+func Mapper[F, T any](s []F, f func(F) T) []T {
+	r := make([]T, len(s))
+	for i, v := range s {
+		r[i] = f(v)
+	}
+	return r
+}
diff --git a/test/typeparam/mapimp.dir/main.go b/test/typeparam/mapimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..4d4a4d9eb0b384687ae81fe3dc89c372a537dba3
--- /dev/null
+++ b/test/typeparam/mapimp.dir/main.go
@@ -0,0 +1,28 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+func main() {
+	got := a.Mapper([]int{1, 2, 3}, strconv.Itoa)
+	want := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got, want) {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+
+	fgot := a.Mapper([]float64{2.5, 2.3, 3.5}, func(f float64) string {
+		return strconv.FormatFloat(f, 'f', -1, 64)
+	})
+	fwant := []string{"2.5", "2.3", "3.5"}
+	if !reflect.DeepEqual(fgot, fwant) {
+		panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
+	}
+}
diff --git a/test/typeparam/mapimp.go b/test/typeparam/mapimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/mapimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mapsimp.dir/a.go b/test/typeparam/mapsimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..696e2a568014a9b0edb23cb9438557d2e2914526
--- /dev/null
+++ b/test/typeparam/mapsimp.dir/a.go
@@ -0,0 +1,108 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+// SliceEqual reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Keys returns the keys of the map m.
+// The keys will be an indeterminate order.
+func Keys[K comparable, V any](m map[K]V) []K {
+	r := make([]K, 0, len(m))
+	for k := range m {
+		r = append(r, k)
+	}
+	return r
+}
+
+// Values returns the values of the map m.
+// The values will be in an indeterminate order.
+func Values[K comparable, V any](m map[K]V) []V {
+	r := make([]V, 0, len(m))
+	for _, v := range m {
+		r = append(r, v)
+	}
+	return r
+}
+
+// Equal reports whether two maps contain the same key/value pairs.
+// Values are compared using ==.
+func Equal[K, V comparable](m1, m2 map[K]V) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[k]; !ok || v1 != v2 {
+			return false
+		}
+	}
+	return true
+}
+
+// Copy returns a copy of m.
+func Copy[K comparable, V any](m map[K]V) map[K]V {
+	r := make(map[K]V, len(m))
+	for k, v := range m {
+		r[k] = v
+	}
+	return r
+}
+
+// Add adds all key/value pairs in m2 to m1. Keys in m2 that are already
+// present in m1 will be overwritten with the value in m2.
+func Add[K comparable, V any](m1, m2 map[K]V) {
+	for k, v := range m2 {
+		m1[k] = v
+	}
+}
+
+// Sub removes all keys in m2 from m1. Keys in m2 that are not present
+// in m1 are ignored. The values in m2 are ignored.
+func Sub[K comparable, V any](m1, m2 map[K]V) {
+	for k := range m2 {
+		delete(m1, k)
+	}
+}
+
+// Intersect removes all keys from m1 that are not present in m2.
+// Keys in m2 that are not in m1 are ignored. The values in m2 are ignored.
+func Intersect[K comparable, V any](m1, m2 map[K]V) {
+	for k := range m1 {
+		if _, ok := m2[k]; !ok {
+			delete(m1, k)
+		}
+	}
+}
+
+// Filter deletes any key/value pairs from m for which f returns false.
+func Filter[K comparable, V any](m map[K]V, f func(K, V) bool) {
+	for k, v := range m {
+		if !f(k, v) {
+			delete(m, k)
+		}
+	}
+}
+
+// TransformValues applies f to each value in m. The keys remain unchanged.
+func TransformValues[K comparable, V any](m map[K]V, f func(V) V) {
+	for k, v := range m {
+		m[k] = f(v)
+	}
+}
diff --git a/test/typeparam/mapsimp.dir/main.go b/test/typeparam/mapsimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..873660e4cd5038f6f316c1d1d5dd7c3883bc1a0c
--- /dev/null
+++ b/test/typeparam/mapsimp.dir/main.go
@@ -0,0 +1,156 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"math"
+	"sort"
+)
+
+var m1 = map[int]int{1: 2, 2: 4, 4: 8, 8: 16}
+var m2 = map[int]string{1: "2", 2: "4", 4: "8", 8: "16"}
+
+func TestKeys() {
+	want := []int{1, 2, 4, 8}
+
+	got1 := a.Keys(m1)
+	sort.Ints(got1)
+	if !a.SliceEqual(got1, want) {
+		panic(fmt.Sprintf("a.Keys(%v) = %v, want %v", m1, got1, want))
+	}
+
+	got2 := a.Keys(m2)
+	sort.Ints(got2)
+	if !a.SliceEqual(got2, want) {
+		panic(fmt.Sprintf("a.Keys(%v) = %v, want %v", m2, got2, want))
+	}
+}
+
+func TestValues() {
+	got1 := a.Values(m1)
+	want1 := []int{2, 4, 8, 16}
+	sort.Ints(got1)
+	if !a.SliceEqual(got1, want1) {
+		panic(fmt.Sprintf("a.Values(%v) = %v, want %v", m1, got1, want1))
+	}
+
+	got2 := a.Values(m2)
+	want2 := []string{"16", "2", "4", "8"}
+	sort.Strings(got2)
+	if !a.SliceEqual(got2, want2) {
+		panic(fmt.Sprintf("a.Values(%v) = %v, want %v", m2, got2, want2))
+	}
+}
+
+func TestEqual() {
+	if !a.Equal(m1, m1) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", m1, m1))
+	}
+	if a.Equal(m1, nil) {
+		panic(fmt.Sprintf("a.Equal(%v, nil) = true, want false", m1))
+	}
+	if a.Equal(nil, m1) {
+		panic(fmt.Sprintf("a.Equal(nil, %v) = true, want false", m1))
+	}
+	if !a.Equal[int, int](nil, nil) {
+		panic("a.Equal(nil, nil) = false, want true")
+	}
+	if ms := map[int]int{1: 2}; a.Equal(m1, ms) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", m1, ms))
+	}
+
+	// Comparing NaN for equality is expected to fail.
+	mf := map[int]float64{1: 0, 2: math.NaN()}
+	if a.Equal(mf, mf) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", mf, mf))
+	}
+}
+
+func TestCopy() {
+	m2 := a.Copy(m1)
+	if !a.Equal(m1, m2) {
+		panic(fmt.Sprintf("a.Copy(%v) = %v, want %v", m1, m2, m1))
+	}
+	m2[16] = 32
+	if a.Equal(m1, m2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", m1, m2))
+	}
+}
+
+func TestAdd() {
+	mc := a.Copy(m1)
+	a.Add(mc, mc)
+	if !a.Equal(mc, m1) {
+		panic(fmt.Sprintf("a.Add(%v, %v) = %v, want %v", m1, m1, mc, m1))
+	}
+	a.Add(mc, map[int]int{16: 32})
+	want := map[int]int{1: 2, 2: 4, 4: 8, 8: 16, 16: 32}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Add result = %v, want %v", mc, want))
+	}
+}
+
+func TestSub() {
+	mc := a.Copy(m1)
+	a.Sub(mc, mc)
+	if len(mc) > 0 {
+		panic(fmt.Sprintf("a.Sub(%v, %v) = %v, want empty map", m1, m1, mc))
+	}
+	mc = a.Copy(m1)
+	a.Sub(mc, map[int]int{1: 0})
+	want := map[int]int{2: 4, 4: 8, 8: 16}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Sub result = %v, want %v", mc, want))
+	}
+}
+
+func TestIntersect() {
+	mc := a.Copy(m1)
+	a.Intersect(mc, mc)
+	if !a.Equal(mc, m1) {
+		panic(fmt.Sprintf("a.Intersect(%v, %v) = %v, want %v", m1, m1, mc, m1))
+	}
+	a.Intersect(mc, map[int]int{1: 0, 2: 0})
+	want := map[int]int{1: 2, 2: 4}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Intersect result = %v, want %v", mc, want))
+	}
+}
+
+func TestFilter() {
+	mc := a.Copy(m1)
+	a.Filter(mc, func(int, int) bool { return true })
+	if !a.Equal(mc, m1) {
+		panic(fmt.Sprintf("a.Filter(%v, true) = %v, want %v", m1, mc, m1))
+	}
+	a.Filter(mc, func(k, v int) bool { return k < 3 })
+	want := map[int]int{1: 2, 2: 4}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Filter result = %v, want %v", mc, want))
+	}
+}
+
+func TestTransformValues() {
+	mc := a.Copy(m1)
+	a.TransformValues(mc, func(i int) int { return i / 2 })
+	want := map[int]int{1: 1, 2: 2, 4: 4, 8: 8}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.TransformValues result = %v, want %v", mc, want))
+	}
+}
+
+func main() {
+	TestKeys()
+	TestValues()
+	TestEqual()
+	TestCopy()
+	TestAdd()
+	TestSub()
+	TestIntersect()
+	TestFilter()
+	TestTransformValues()
+}
diff --git a/test/typeparam/mapsimp.go b/test/typeparam/mapsimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/mapsimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/1.dir/a.go b/test/typeparam/mdempsky/1.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..a668eb52dc9dc13d0457e3a8ed3a8049cefac904
--- /dev/null
+++ b/test/typeparam/mdempsky/1.dir/a.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type T[_ any] int
+
+func F() { _ = new(T[int]) }
diff --git a/test/typeparam/mdempsky/1.dir/b.go b/test/typeparam/mdempsky/1.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..af6fef3f6d8bad40de56f7c1803ef5990191abc7
--- /dev/null
+++ b/test/typeparam/mdempsky/1.dir/b.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "./a"
+
+func main() { a.F() }
diff --git a/test/typeparam/mdempsky/1.go b/test/typeparam/mdempsky/1.go
new file mode 100644
index 0000000000000000000000000000000000000000..87b4ff46c1ea4e6750058822d454a40cccb2cf1c
--- /dev/null
+++ b/test/typeparam/mdempsky/1.go
@@ -0,0 +1,7 @@
+// compiledir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/10.dir/a.go b/test/typeparam/mdempsky/10.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..95e111d3470a1a7259d398b3d68ec26f70b6ed65
--- /dev/null
+++ b/test/typeparam/mdempsky/10.dir/a.go
@@ -0,0 +1,7 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type I[T any] interface{ M() T }
diff --git a/test/typeparam/mdempsky/10.dir/b.go b/test/typeparam/mdempsky/10.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..0ef28fd02de3282e61ce2ebb2b0278db1ee4d9f3
--- /dev/null
+++ b/test/typeparam/mdempsky/10.dir/b.go
@@ -0,0 +1,17 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "./a"
+
+var m = a.I[int].M
+
+var never bool
+
+func main() {
+	if never {
+		m(nil)
+	}
+}
diff --git a/test/typeparam/mdempsky/10.go b/test/typeparam/mdempsky/10.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/mdempsky/10.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/11.go b/test/typeparam/mdempsky/11.go
new file mode 100644
index 0000000000000000000000000000000000000000..e86c038a10468bce44f091844369b07cf412473a
--- /dev/null
+++ b/test/typeparam/mdempsky/11.go
@@ -0,0 +1,16 @@
+// errorcheck
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Reported by Cuong Manh Le.
+
+package p
+
+type a struct{}
+
+//go:notinheap
+type b a
+
+var _ = (*b)(new(a)) // ERROR "cannot convert"
diff --git a/test/typeparam/mdempsky/12.dir/a.go b/test/typeparam/mdempsky/12.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..ee8be939a8fadd5985e56a491ae2d3e19928ef11
--- /dev/null
+++ b/test/typeparam/mdempsky/12.dir/a.go
@@ -0,0 +1,11 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type S[T any] struct {
+	F T
+}
+
+var X = S[int]{}
diff --git a/test/typeparam/mdempsky/12.dir/main.go b/test/typeparam/mdempsky/12.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..2891322e298867275828c331830fa8bbd3fda114
--- /dev/null
+++ b/test/typeparam/mdempsky/12.dir/main.go
@@ -0,0 +1,13 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"./a"
+)
+
+func main() {
+	_ = a.X
+}
diff --git a/test/typeparam/mdempsky/12.go b/test/typeparam/mdempsky/12.go
new file mode 100644
index 0000000000000000000000000000000000000000..a2dc4daacccee5e623f57cc1d45ecf266bfe2a7d
--- /dev/null
+++ b/test/typeparam/mdempsky/12.go
@@ -0,0 +1,9 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Reported by Cuong Manh Le.
+
+package ignored
diff --git a/test/typeparam/mdempsky/13.go b/test/typeparam/mdempsky/13.go
new file mode 100644
index 0000000000000000000000000000000000000000..b492774d3d849a285e74202d9f03a128733eadc5
--- /dev/null
+++ b/test/typeparam/mdempsky/13.go
@@ -0,0 +1,84 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Interface which will be used as a regular interface type and as a type bound.
+type Mer interface{
+	M()
+}
+
+// Interface that is a superset of Mer.
+type Mer2 interface {
+	M()
+	String() string
+}
+
+func F[T Mer](t T) {
+	T.M(t)
+	t.M()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+func (MyMer) String() string {
+	return "aa"
+}
+
+// Parameterized interface
+type Abs[T any] interface {
+	Abs() T
+}
+
+func G[T Abs[U], U any](t T) {
+	T.Abs(t)
+	t.Abs()
+}
+
+type MyInt int
+func (m MyInt) Abs() MyInt {
+	if m < 0 {
+		return -m
+	}
+	return m
+}
+
+type Abs2 interface {
+	Abs() MyInt
+}
+
+
+func main() {
+	mm := MyMer(3)
+	ms := struct{ Mer }{Mer: mm }
+
+	// Testing F with an interface type arg: Mer and Mer2
+	F[Mer](mm)
+	F[Mer2](mm)
+	F[struct{ Mer }](ms)
+	F[*struct{ Mer }](&ms)
+
+	ms2 := struct { MyMer }{MyMer: mm}
+	ms3 := struct { *MyMer }{MyMer: &mm}
+
+	// Testing F with a concrete type arg
+	F[MyMer](mm)
+	F[*MyMer](&mm)
+	F[struct{ MyMer }](ms2)
+	F[struct{ *MyMer }](ms3)
+	F[*struct{ MyMer }](&ms2)
+	F[*struct{ *MyMer }](&ms3)
+
+	// Testing G with a concrete type args
+	mi := MyInt(-3)
+	G[MyInt,MyInt](mi)
+
+	// Interface Abs[MyInt] holding an mi.
+	intMi := Abs[MyInt](mi)
+	// First type arg here is Abs[MyInt], an interface type.
+	G[Abs[MyInt],MyInt](intMi)
+}
diff --git a/test/typeparam/mdempsky/14.go b/test/typeparam/mdempsky/14.go
new file mode 100644
index 0000000000000000000000000000000000000000..ba685bc35c8d3fd08ae56a6f49f68fe328b3ded3
--- /dev/null
+++ b/test/typeparam/mdempsky/14.go
@@ -0,0 +1,40 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Zero returns the zero value of T
+func Zero[T any]() (_ T) {
+	return
+}
+
+type AnyInt[X any] int
+
+func (AnyInt[X]) M() {
+	var have interface{} = Zero[X]()
+	var want interface{} = Zero[MyInt]()
+
+	if have != want {
+		println("FAIL")
+	}
+}
+
+type I interface{ M() }
+
+type MyInt int
+type U = AnyInt[MyInt]
+
+var x = U(0)
+var i I = x
+
+func main() {
+	x.M()
+	U.M(x)
+	(*U).M(&x)
+
+	i.M()
+	I.M(x)
+}
diff --git a/test/typeparam/mdempsky/15.go b/test/typeparam/mdempsky/15.go
new file mode 100644
index 0000000000000000000000000000000000000000..4899fc75eecdbb44a31439c1d88fe5cdb803eb59
--- /dev/null
+++ b/test/typeparam/mdempsky/15.go
@@ -0,0 +1,69 @@
+// run -goexperiment fieldtrack -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that generics, promoted methods, and //go:nointerface
+// interoperate as expected.
+
+package main
+
+import (
+	"reflect"
+)
+
+func TypeString[T any]() string {
+	return reflect.TypeOf(new(T)).Elem().String()
+}
+
+func Test[T, Bad, Good any]() {
+	switch interface{}(new(T)).(type) {
+	case Bad:
+		println("FAIL:", TypeString[T](), "matched", TypeString[Bad]())
+	case Good:
+		// ok
+	default:
+		println("FAIL:", TypeString[T](), "did not match", TypeString[Good]())
+	}
+}
+
+func TestE[T any]() { Test[T, interface{ EBad() }, interface{ EGood() }]() }
+func TestX[T any]() { Test[T, interface{ XBad() }, interface{ XGood() }]() }
+
+type E struct{}
+
+//go:nointerface
+func (E) EBad()  {}
+func (E) EGood() {}
+
+type X[T any] struct{ E }
+
+//go:nointerface
+func (X[T]) XBad()  {}
+func (X[T]) XGood() {}
+
+type W struct{ X[int] }
+
+func main() {
+	_ = E.EGood
+	_ = E.EBad
+
+	TestE[E]()
+
+	_ = X[int].EGood
+	_ = X[int].EBad
+	_ = X[int].XGood
+	_ = X[int].XBad
+
+	TestE[X[int]]()
+	TestX[X[int]]()
+
+	_ = W.EGood
+	_ = W.EBad
+	_ = W.XGood
+	_ = W.XBad
+
+	TestE[W]()
+	TestX[W]()
+}
diff --git a/test/typeparam/mdempsky/2.go b/test/typeparam/mdempsky/2.go
new file mode 100644
index 0000000000000000000000000000000000000000..f09730f94910f65f3420d23e8b9fa705f6867415
--- /dev/null
+++ b/test/typeparam/mdempsky/2.go
@@ -0,0 +1,20 @@
+// compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type T[A, B, C any] int
+
+func (T[A, B, C]) m(x int) {
+	if x <= 0 {
+		return
+	}
+	T[B, C, A](0).m(x - 1)
+}
+
+func main() {
+	T[int8, int16, int32](0).m(3)
+}
diff --git a/test/typeparam/mdempsky/3.dir/a.go b/test/typeparam/mdempsky/3.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..cf456e8d48f17422ebb16183066d6556f371f04e
--- /dev/null
+++ b/test/typeparam/mdempsky/3.dir/a.go
@@ -0,0 +1,7 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func F[T interface{ chan int }](c T) {}
diff --git a/test/typeparam/mdempsky/3.dir/b.go b/test/typeparam/mdempsky/3.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..0cfd142f4c454e8222253d97e5a48cab273580d5
--- /dev/null
+++ b/test/typeparam/mdempsky/3.dir/b.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "./a"
+
+func g() { a.F(make(chan int)) }
diff --git a/test/typeparam/mdempsky/3.go b/test/typeparam/mdempsky/3.go
new file mode 100644
index 0000000000000000000000000000000000000000..87b4ff46c1ea4e6750058822d454a40cccb2cf1c
--- /dev/null
+++ b/test/typeparam/mdempsky/3.go
@@ -0,0 +1,7 @@
+// compiledir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/4.dir/a.go b/test/typeparam/mdempsky/4.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..cb672949eaedcd8faaeb72beb135078c6de41a7e
--- /dev/null
+++ b/test/typeparam/mdempsky/4.dir/a.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func F[T any](T) {
+Loop:
+	for {
+		break Loop
+	}
+}
diff --git a/test/typeparam/mdempsky/4.dir/b.go b/test/typeparam/mdempsky/4.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..e1fb0e7c5eaabc3af41c320fe9adfda6a22e7eab
--- /dev/null
+++ b/test/typeparam/mdempsky/4.dir/b.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "./a"
+
+func f() { a.F(0) }
diff --git a/test/typeparam/mdempsky/4.go b/test/typeparam/mdempsky/4.go
new file mode 100644
index 0000000000000000000000000000000000000000..87b4ff46c1ea4e6750058822d454a40cccb2cf1c
--- /dev/null
+++ b/test/typeparam/mdempsky/4.go
@@ -0,0 +1,7 @@
+// compiledir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/5.go b/test/typeparam/mdempsky/5.go
new file mode 100644
index 0000000000000000000000000000000000000000..0d1ad3994624ae1b01cd0bf73f256fd3c36111e5
--- /dev/null
+++ b/test/typeparam/mdempsky/5.go
@@ -0,0 +1,15 @@
+// compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type X[T any] int
+
+func (X[T]) F(T) {}
+
+func x() {
+	X[interface{}](0).F(0)
+}
diff --git a/test/typeparam/mdempsky/6.go b/test/typeparam/mdempsky/6.go
new file mode 100644
index 0000000000000000000000000000000000000000..a26ff62f6d44e9275325ee62ce68f97881c4050d
--- /dev/null
+++ b/test/typeparam/mdempsky/6.go
@@ -0,0 +1,11 @@
+// compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type I[T any] interface{ M() T }
+
+var _ = I[int].M
diff --git a/test/typeparam/mdempsky/7.dir/a.go b/test/typeparam/mdempsky/7.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..59c5995611834a9cbec9ca3b2aa9f9588011ea36
--- /dev/null
+++ b/test/typeparam/mdempsky/7.dir/a.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type I[T any] interface{ M() T }
+
+var X I[int]
diff --git a/test/typeparam/mdempsky/7.dir/b.go b/test/typeparam/mdempsky/7.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..9f70530811482ea8213ec47efd5f76593a432814
--- /dev/null
+++ b/test/typeparam/mdempsky/7.dir/b.go
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "./a"
+
+var _ = a.X
diff --git a/test/typeparam/mdempsky/7.go b/test/typeparam/mdempsky/7.go
new file mode 100644
index 0000000000000000000000000000000000000000..87b4ff46c1ea4e6750058822d454a40cccb2cf1c
--- /dev/null
+++ b/test/typeparam/mdempsky/7.go
@@ -0,0 +1,7 @@
+// compiledir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/8.dir/a.go b/test/typeparam/mdempsky/8.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..607fe5e0af2e098b1083bbe81c12c3f7dfa58506
--- /dev/null
+++ b/test/typeparam/mdempsky/8.dir/a.go
@@ -0,0 +1,7 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func F[T interface{ comparable }]() {}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/8.dir/b.go
similarity index 68%
rename from src/cmd/gofmt/gofmt_typeparams_test.go
rename to test/typeparam/mdempsky/8.dir/b.go
index 10641a77cb2f8762dfd10c2dfbb25313adab225a..ef2637b894fb69c563689081f44dc3f431a9ee5d 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/8.dir/b.go
@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "./a"
 
 func init() {
-	typeParamsEnabled = true
+	a.F[func()]() // ERROR "does not satisfy comparable"
 }
diff --git a/test/typeparam/mdempsky/8.go b/test/typeparam/mdempsky/8.go
new file mode 100644
index 0000000000000000000000000000000000000000..32cf4b830d256cbd600e05557df95d693a98b2bf
--- /dev/null
+++ b/test/typeparam/mdempsky/8.go
@@ -0,0 +1,7 @@
+// errorcheckdir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mdempsky/9.go b/test/typeparam/mdempsky/9.go
new file mode 100644
index 0000000000000000000000000000000000000000..b72516c4eabccf4175b99bfb9027acd58bcc2ff6
--- /dev/null
+++ b/test/typeparam/mdempsky/9.go
@@ -0,0 +1,11 @@
+// compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func f[V any]() []V { return []V{0: *new(V)} }
+
+func g() { f[int]() }
diff --git a/test/typeparam/min.go b/test/typeparam/min.go
index a3e4464a3039c85a9481d05225605f3d92b5c2af..d6c65d68b79db93e9f9aead771071d3e61b67f37 100644
--- a/test/typeparam/min.go
+++ b/test/typeparam/min.go
@@ -11,7 +11,7 @@ import (
 )
 
 type Ordered interface {
-	type int, int64, float64
+	~int | ~int64 | ~float64 | ~string
 }
 
 func min[T Ordered](x, y T) T {
@@ -38,4 +38,13 @@ func main() {
 	if got := min(3.5, 2.0); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
+
+	const want2 = "ay"
+	if got := min[string]("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+
+	if got := min("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
 }
diff --git a/test/typeparam/mincheck.dir/a.go b/test/typeparam/mincheck.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..fa0f249e61510c3a136fc0c66b3cff4d3f876df0
--- /dev/null
+++ b/test/typeparam/mincheck.dir/a.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	int | int64 | float64
+}
+
+func Min[T Ordered](x, y T) T {
+	if x < y {
+		return x
+	}
+	return y
+}
diff --git a/test/typeparam/mincheck.dir/main.go b/test/typeparam/mincheck.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..9cf2c6bafd669d85e6dbc80de21395aa2aac211f
--- /dev/null
+++ b/test/typeparam/mincheck.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	const want = 2
+	if got := a.Min[int](2, 3); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(2, 3); got != want {
+		panic(fmt.Sprintf("want %d, got %d", want, got))
+	}
+
+	if got := a.Min[float64](3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	const want2 = "ay"
+	if got := a.Min[string]("bb", "ay"); got != want2 { // ERROR "string does not satisfy"
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+
+	if got := a.Min("bb", "ay"); got != want2 { // ERROR "string does not satisfy"
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+}
diff --git a/test/typeparam/mincheck.go b/test/typeparam/mincheck.go
new file mode 100644
index 0000000000000000000000000000000000000000..32cf4b830d256cbd600e05557df95d693a98b2bf
--- /dev/null
+++ b/test/typeparam/mincheck.go
@@ -0,0 +1,7 @@
+// errorcheckdir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/minimp.dir/a.go b/test/typeparam/minimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..fabde62c5d7218c987cbd64793586c941456451c
--- /dev/null
+++ b/test/typeparam/minimp.dir/a.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	~int | ~int64 | ~float64 | ~string
+}
+
+func Min[T Ordered](x, y T) T {
+	if x < y {
+		return x
+	}
+	return y
+}
diff --git a/test/typeparam/minimp.dir/main.go b/test/typeparam/minimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..509f5aaed2b4cb8b1f0e7a46bc2e93d3c7555ddb
--- /dev/null
+++ b/test/typeparam/minimp.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	const want = 2
+	if got := a.Min[int](2, 3); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(2, 3); got != want {
+		panic(fmt.Sprintf("want %d, got %d", want, got))
+	}
+
+	if got := a.Min[float64](3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	const want2 = "ay"
+	if got := a.Min[string]("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+
+	if got := a.Min("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+}
diff --git a/test/typeparam/minimp.go b/test/typeparam/minimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/minimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/mutualimp.dir/a.go b/test/typeparam/mutualimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..5b924d3ce5dfec687d84c11e0bcf7b145493abcb
--- /dev/null
+++ b/test/typeparam/mutualimp.dir/a.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type X int
+
+func (x X) M() X { return x }
+
+func F[T interface{ M() U }, U interface{ M() T }]() {}
+func G()                                             { F[X, X]() }
diff --git a/test/typeparam/mutualimp.dir/b.go b/test/typeparam/mutualimp.dir/b.go
new file mode 100644
index 0000000000000000000000000000000000000000..83cc3af2835c55b7c1b5db2ba604d9a5b2da05e8
--- /dev/null
+++ b/test/typeparam/mutualimp.dir/b.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "./a"
+
+func H() {
+	a.F[a.X, a.X]()
+	a.G()
+}
diff --git a/test/typeparam/mutualimp.go b/test/typeparam/mutualimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..87b4ff46c1ea4e6750058822d454a40cccb2cf1c
--- /dev/null
+++ b/test/typeparam/mutualimp.go
@@ -0,0 +1,7 @@
+// compiledir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/nested.go b/test/typeparam/nested.go
new file mode 100644
index 0000000000000000000000000000000000000000..c0037a3e6e46edbe34cbeec1d61b08abd2a57776
--- /dev/null
+++ b/test/typeparam/nested.go
@@ -0,0 +1,134 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This test case stress tests a number of subtle cases involving
+// nested type-parameterized declarations. At a high-level, it
+// declares a generic function that contains a generic type
+// declaration:
+//
+//	func F[A intish]() {
+//		type T[B intish] struct{}
+//
+//		// store reflect.Type tuple (A, B, F[A].T[B]) in tests
+//	}
+//
+// It then instantiates this function with a variety of type arguments
+// for A and B. Particularly tricky things like shadowed types.
+//
+// From this data it tests two things:
+//
+// 1. Given tuples (A, B, F[A].T[B]) and (A', B', F[A'].T[B']),
+//    F[A].T[B] should be identical to F[A'].T[B'] iff (A, B) is
+//    identical to (A', B').
+//
+// 2. A few of the instantiations are constructed to be identical, and
+//    it tests that exactly these pairs are duplicated (by golden
+//    output comparison to nested.out).
+//
+// In both cases, we're effectively using the compiler's existing
+// runtime.Type handling (which is well tested) of type identity of A
+// and B as a way to help bootstrap testing and validate its new
+// runtime.Type handling of F[A].T[B].
+//
+// This isn't perfect, but it smoked out a handful of issues in
+// gotypes2 and unified IR.
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type test struct {
+	TArgs    [2]reflect.Type
+	Instance reflect.Type
+}
+
+var tests []test
+
+type intish interface{ ~int }
+
+type Int int
+type GlobalInt = Int // allow access to global Int, even when shadowed
+
+func F[A intish]() {
+	add := func(B, T interface{}) {
+		tests = append(tests, test{
+			TArgs: [2]reflect.Type{
+				reflect.TypeOf(A(0)),
+				reflect.TypeOf(B),
+			},
+			Instance: reflect.TypeOf(T),
+		})
+	}
+
+	type Int int
+
+	type T[B intish] struct{}
+
+	add(int(0), T[int]{})
+	add(Int(0), T[Int]{})
+	add(GlobalInt(0), T[GlobalInt]{})
+	add(A(0), T[A]{}) // NOTE: intentionally dups with int and GlobalInt
+
+	type U[_ any] int
+	type V U[int]
+	type W V
+
+	add(U[int](0), T[U[int]]{})
+	add(U[Int](0), T[U[Int]]{})
+	add(U[GlobalInt](0), T[U[GlobalInt]]{})
+	add(U[A](0), T[U[A]]{}) // NOTE: intentionally dups with U[int] and U[GlobalInt]
+	add(V(0), T[V]{})
+	add(W(0), T[W]{})
+}
+
+func main() {
+	type Int int
+
+	F[int]()
+	F[Int]()
+	F[GlobalInt]()
+
+	type U[_ any] int
+	type V U[int]
+	type W V
+
+	F[U[int]]()
+	F[U[Int]]()
+	F[U[GlobalInt]]()
+	F[V]()
+	F[W]()
+
+	type X[A any] U[X[A]]
+
+	F[X[int]]()
+	F[X[Int]]()
+	F[X[GlobalInt]]()
+
+	for j, tj := range tests {
+		for i, ti := range tests[:j+1] {
+			if (ti.TArgs == tj.TArgs) != (ti.Instance == tj.Instance) {
+				fmt.Printf("FAIL: %d,%d: %s, but %s\n", i, j, eq(ti.TArgs, tj.TArgs), eq(ti.Instance, tj.Instance))
+			}
+
+			// The test is constructed so we should see a few identical types.
+			// See "NOTE" comments above.
+			if i != j && ti.Instance == tj.Instance {
+				fmt.Printf("%d,%d: %v\n", i, j, ti.Instance)
+			}
+		}
+	}
+}
+
+func eq(a, b interface{}) string {
+	op := "=="
+	if a != b {
+		op = "!="
+	}
+	return fmt.Sprintf("%v %s %v", a, op, b)
+}
diff --git a/test/typeparam/nested.out b/test/typeparam/nested.out
new file mode 100644
index 0000000000000000000000000000000000000000..911051824828dfc9322813779b0f7570d9d6eaef
--- /dev/null
+++ b/test/typeparam/nested.out
@@ -0,0 +1,4 @@
+0,3: main.T·2[int;int]
+4,7: main.T·2[int;"".U·3[int;int]]
+22,23: main.T·2["".Int;"".Int]
+26,27: main.T·2["".Int;"".U·3["".Int;"".Int]]
diff --git a/test/typeparam/ordered.go b/test/typeparam/ordered.go
index 448db68bb55bf5eb64a68bd28a89b3f5ab592d86..0f539d659c39785752cd29083cfad45161bd29ec 100644
--- a/test/typeparam/ordered.go
+++ b/test/typeparam/ordered.go
@@ -13,15 +13,15 @@ import (
 )
 
 type Ordered interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 type orderedSlice[Elem Ordered] []Elem
 
-func (s orderedSlice[Elem]) Len() int           { return len(s) }
+func (s orderedSlice[Elem]) Len() int { return len(s) }
 func (s orderedSlice[Elem]) Less(i, j int) bool {
 	if s[i] < s[j] {
 		return true
@@ -32,7 +32,7 @@ func (s orderedSlice[Elem]) Less(i, j int) bool {
 	}
 	return false
 }
-func (s orderedSlice[Elem]) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s orderedSlice[Elem]) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
 
 func _OrderedSlice[Elem Ordered](s []Elem) {
 	sort.Sort(orderedSlice[Elem](s))
@@ -68,7 +68,7 @@ func testOrdered[Elem Ordered](name string, s []Elem, sorter func([]Elem)) bool
 	}
 	for i := len(s1) - 1; i > 0; i-- {
 		if s1[i] < s1[i-1] {
-			fmt.Printf("%s: element %d (%v) < element %d (%v)", name, i, s1[i], i - 1, s1[i - 1])
+			fmt.Printf("%s: element %d (%v) < element %d (%v)", name, i, s1[i], i-1, s1[i-1])
 			ok = false
 		}
 	}
diff --git a/test/typeparam/orderedmap.go b/test/typeparam/orderedmap.go
index db1b3742674080552fd771b41fe6882c08b317be..1f077333b8fcc49c46d10260d58d4d6f1022df37 100644
--- a/test/typeparam/orderedmap.go
+++ b/test/typeparam/orderedmap.go
@@ -15,10 +15,10 @@ import (
 )
 
 type Ordered interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64,
-                string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 // _Map is an ordered map.
@@ -230,7 +230,7 @@ func _Ranger[Elem any]() (*_Sender[Elem], *_Receiver[Elem]) {
 		values: c,
 		done:   d,
 	}
-	r := &_Receiver[Elem] {
+	r := &_Receiver[Elem]{
 		values: c,
 		done:   d,
 	}
diff --git a/test/typeparam/orderedmapsimp.dir/a.go b/test/typeparam/orderedmapsimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..d6a2de5d7b3e4a7eead46e360ac9a9c04b1293a1
--- /dev/null
+++ b/test/typeparam/orderedmapsimp.dir/a.go
@@ -0,0 +1,226 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"context"
+	"runtime"
+)
+
+type Ordered interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
+}
+
+// Map is an ordered map.
+type Map[K, V any] struct {
+	root    *node[K, V]
+	compare func(K, K) int
+}
+
+// node is the type of a node in the binary tree.
+type node[K, V any] struct {
+	key         K
+	val         V
+	left, right *node[K, V]
+}
+
+// New returns a new map. It takes a comparison function that compares two
+// keys and returns < 0 if the first is less, == 0 if they are equal,
+// > 0 if the first is greater.
+func New[K, V any](compare func(K, K) int) *Map[K, V] {
+	return &Map[K, V]{compare: compare}
+}
+
+// NewOrdered returns a new map whose key is an ordered type.
+// This is like New, but does not require providing a compare function.
+// The map compare function uses the obvious key ordering.
+func NewOrdered[K Ordered, V any]() *Map[K, V] {
+	return New[K, V](func(k1, k2 K) int {
+		switch {
+		case k1 < k2:
+			return -1
+		case k1 > k2:
+			return 1
+		default:
+			return 0
+		}
+	})
+}
+
+// find looks up key in the map, returning either a pointer to the slot of the
+// node holding key, or a pointer to the slot where a node would go.
+func (m *Map[K, V]) find(key K) **node[K, V] {
+	pn := &m.root
+	for *pn != nil {
+		switch cmp := m.compare(key, (*pn).key); {
+		case cmp < 0:
+			pn = &(*pn).left
+		case cmp > 0:
+			pn = &(*pn).right
+		default:
+			return pn
+		}
+	}
+	return pn
+}
+
+// Insert inserts a new key/value into the map.
+// If the key is already present, the value is replaced.
+// Reports whether this is a new key.
+func (m *Map[K, V]) Insert(key K, val V) bool {
+	pn := m.find(key)
+	if *pn != nil {
+		(*pn).val = val
+		return false
+	}
+	*pn = &node[K, V]{key: key, val: val}
+	return true
+}
+
+// Find returns the value associated with a key, or the zero value
+// if not present. The second result reports whether the key was found.
+func (m *Map[K, V]) Find(key K) (V, bool) {
+	pn := m.find(key)
+	if *pn == nil {
+		var zero V
+		return zero, false
+	}
+	return (*pn).val, true
+}
+
+// keyValue is a pair of key and value used while iterating.
+type keyValue[K, V any] struct {
+	key K
+	val V
+}
+
+// iterate returns an iterator that traverses the map.
+func (m *Map[K, V]) Iterate() *Iterator[K, V] {
+	sender, receiver := Ranger[keyValue[K, V]]()
+	var f func(*node[K, V]) bool
+	f = func(n *node[K, V]) bool {
+		if n == nil {
+			return true
+		}
+		// Stop the traversal if Send fails, which means that
+		// nothing is listening to the receiver.
+		return f(n.left) &&
+			sender.Send(context.Background(), keyValue[K, V]{n.key, n.val}) &&
+			f(n.right)
+	}
+	go func() {
+		f(m.root)
+		sender.Close()
+	}()
+	return &Iterator[K, V]{receiver}
+}
+
+// Iterator is used to iterate over the map.
+type Iterator[K, V any] struct {
+	r *Receiver[keyValue[K, V]]
+}
+
+// Next returns the next key and value pair, and a boolean that reports
+// whether they are valid. If not valid, we have reached the end of the map.
+func (it *Iterator[K, V]) Next() (K, V, bool) {
+	keyval, ok := it.r.Next(context.Background())
+	if !ok {
+		var zerok K
+		var zerov V
+		return zerok, zerov, false
+	}
+	return keyval.key, keyval.val, true
+}
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Ranger returns a Sender and a Receiver. The Receiver provides a
+// Next method to retrieve values. The Sender provides a Send method
+// to send values and a Close method to stop sending values. The Next
+// method indicates when the Sender has been closed, and the Send
+// method indicates when the Receiver has been freed.
+//
+// This is a convenient way to exit a goroutine sending values when
+// the receiver stops reading them.
+func Ranger[Elem any]() (*Sender[Elem], *Receiver[Elem]) {
+	c := make(chan Elem)
+	d := make(chan struct{})
+	s := &Sender[Elem]{
+		values: c,
+		done:   d,
+	}
+	r := &Receiver[Elem]{
+		values: c,
+		done:   d,
+	}
+	runtime.SetFinalizer(r, (*Receiver[Elem]).finalize)
+	return s, r
+}
+
+// A Sender is used to send values to a Receiver.
+type Sender[Elem any] struct {
+	values chan<- Elem
+	done   <-chan struct{}
+}
+
+// Send sends a value to the receiver. It reports whether the value was sent.
+// The value will not be sent if the context is closed or the receiver
+// is freed.
+func (s *Sender[Elem]) Send(ctx context.Context, v Elem) bool {
+	select {
+	case <-ctx.Done():
+		return false
+	case s.values <- v:
+		return true
+	case <-s.done:
+		return false
+	}
+}
+
+// Close tells the receiver that no more values will arrive.
+// After Close is called, the Sender may no longer be used.
+func (s *Sender[Elem]) Close() {
+	close(s.values)
+}
+
+// A Receiver receives values from a Sender.
+type Receiver[Elem any] struct {
+	values <-chan Elem
+	done   chan<- struct{}
+}
+
+// Next returns the next value from the channel. The bool result indicates
+// whether the value is valid.
+func (r *Receiver[Elem]) Next(ctx context.Context) (v Elem, ok bool) {
+	select {
+	case <-ctx.Done():
+	case v, ok = <-r.values:
+	}
+	return v, ok
+}
+
+// finalize is a finalizer for the receiver.
+func (r *Receiver[Elem]) finalize() {
+	close(r.done)
+}
diff --git a/test/typeparam/orderedmapsimp.dir/main.go b/test/typeparam/orderedmapsimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..978f1e763c09f4d2ae5badbcc33a46dad0771af0
--- /dev/null
+++ b/test/typeparam/orderedmapsimp.dir/main.go
@@ -0,0 +1,64 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"bytes"
+	"fmt"
+)
+
+func TestMap() {
+	m := a.New[[]byte, int](bytes.Compare)
+
+	if _, found := m.Find([]byte("a")); found {
+		panic(fmt.Sprintf("unexpectedly found %q in empty map", []byte("a")))
+	}
+
+	for _, c := range []int{'a', 'c', 'b'} {
+		if !m.Insert([]byte(string(c)), c) {
+			panic(fmt.Sprintf("key %q unexpectedly already present", []byte(string(c))))
+		}
+	}
+	if m.Insert([]byte("c"), 'x') {
+		panic(fmt.Sprintf("key %q unexpectedly not present", []byte("c")))
+	}
+
+	if v, found := m.Find([]byte("a")); !found {
+		panic(fmt.Sprintf("did not find %q", []byte("a")))
+	} else if v != 'a' {
+		panic(fmt.Sprintf("key %q returned wrong value %c, expected %c", []byte("a"), v, 'a'))
+	}
+	if v, found := m.Find([]byte("c")); !found {
+		panic(fmt.Sprintf("did not find %q", []byte("c")))
+	} else if v != 'x' {
+		panic(fmt.Sprintf("key %q returned wrong value %c, expected %c", []byte("c"), v, 'x'))
+	}
+
+	if _, found := m.Find([]byte("d")); found {
+		panic(fmt.Sprintf("unexpectedly found %q", []byte("d")))
+	}
+
+	gather := func(it *a.Iterator[[]byte, int]) []int {
+		var r []int
+		for {
+			_, v, ok := it.Next()
+			if !ok {
+				return r
+			}
+			r = append(r, v)
+		}
+	}
+	got := gather(m.Iterate())
+	want := []int{'a', 'b', 'x'}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("Iterate returned %v, want %v", got, want))
+	}
+
+}
+
+func main() {
+	TestMap()
+}
diff --git a/test/typeparam/orderedmapsimp.go b/test/typeparam/orderedmapsimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/orderedmapsimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/pair.go b/test/typeparam/pair.go
index 7faf083c89d117aa8283ca994b9ecb74abacd4cb..c1427b9c52c2d48896401fec162ff12d7a0ec029 100644
--- a/test/typeparam/pair.go
+++ b/test/typeparam/pair.go
@@ -24,7 +24,11 @@ func main() {
 	if got, want := unsafe.Sizeof(p.f2), uintptr(8); got != want {
 		panic(fmt.Sprintf("unexpected f2 size == %d, want %d", got, want))
 	}
-	type mypair struct { f1 int32; f2 int64 }
+
+	type mypair struct {
+		f1 int32
+		f2 int64
+	}
 	mp := mypair(p)
 	if mp.f1 != 1 || mp.f2 != 2 {
 		panic(fmt.Sprintf("mp == %#v, want %#v", mp, mypair{1, 2}))
diff --git a/test/typeparam/pairimp.dir/a.go b/test/typeparam/pairimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..a984fba37b6e6655d8ba2031166d7b575737927c
--- /dev/null
+++ b/test/typeparam/pairimp.dir/a.go
@@ -0,0 +1,10 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Pair[F1, F2 any] struct {
+	Field1 F1
+	Field2 F2
+}
diff --git a/test/typeparam/pairimp.dir/main.go b/test/typeparam/pairimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..027fdd9ce766605db05c73fe435af0384923e274
--- /dev/null
+++ b/test/typeparam/pairimp.dir/main.go
@@ -0,0 +1,30 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"unsafe"
+)
+
+func main() {
+	p := a.Pair[int32, int64]{1, 2}
+	if got, want := unsafe.Sizeof(p.Field1), uintptr(4); got != want {
+		panic(fmt.Sprintf("unexpected f1 size == %d, want %d", got, want))
+	}
+	if got, want := unsafe.Sizeof(p.Field2), uintptr(8); got != want {
+		panic(fmt.Sprintf("unexpected f2 size == %d, want %d", got, want))
+	}
+
+	type mypair struct {
+		Field1 int32
+		Field2 int64
+	}
+	mp := mypair(p)
+	if mp.Field1 != 1 || mp.Field2 != 2 {
+		panic(fmt.Sprintf("mp == %#v, want %#v", mp, mypair{1, 2}))
+	}
+}
diff --git a/test/typeparam/pairimp.go b/test/typeparam/pairimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/pairimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/sets.go b/test/typeparam/sets.go
index 258514489e1708ef552242a081c34f313bfc2c51..4f07b590e36fae404b99cb4d120d7efae02b9c5f 100644
--- a/test/typeparam/sets.go
+++ b/test/typeparam/sets.go
@@ -160,7 +160,7 @@ func TestSet() {
 	vals := s1.Values()
 	sort.Ints(vals)
 	w1 := []int{1, 2, 3, 4}
-	if !_SliceEqual(vals,  w1) {
+	if !_SliceEqual(vals, w1) {
 		panic(fmt.Sprintf("(%v).Values() == %v, want %v", s1, vals, w1))
 	}
 }
diff --git a/test/typeparam/setsimp.dir/a.go b/test/typeparam/setsimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..92449ce95620caf19ee17019ddecf36c8130ea89
--- /dev/null
+++ b/test/typeparam/setsimp.dir/a.go
@@ -0,0 +1,128 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+// SliceEqual reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// A Set is a set of elements of some type.
+type Set[Elem comparable] struct {
+	m map[Elem]struct{}
+}
+
+// Make makes a new set.
+func Make[Elem comparable]() Set[Elem] {
+	return Set[Elem]{m: make(map[Elem]struct{})}
+}
+
+// Add adds an element to a set.
+func (s Set[Elem]) Add(v Elem) {
+	s.m[v] = struct{}{}
+}
+
+// Delete removes an element from a set. If the element is not present
+// in the set, this does nothing.
+func (s Set[Elem]) Delete(v Elem) {
+	delete(s.m, v)
+}
+
+// Contains reports whether v is in the set.
+func (s Set[Elem]) Contains(v Elem) bool {
+	_, ok := s.m[v]
+	return ok
+}
+
+// Len returns the number of elements in the set.
+func (s Set[Elem]) Len() int {
+	return len(s.m)
+}
+
+// Values returns the values in the set.
+// The values will be in an indeterminate order.
+func (s Set[Elem]) Values() []Elem {
+	r := make([]Elem, 0, len(s.m))
+	for v := range s.m {
+		r = append(r, v)
+	}
+	return r
+}
+
+// Equal reports whether two sets contain the same elements.
+func Equal[Elem comparable](s1, s2 Set[Elem]) bool {
+	if len(s1.m) != len(s2.m) {
+		return false
+	}
+	for v1 := range s1.m {
+		if !s2.Contains(v1) {
+			return false
+		}
+	}
+	return true
+}
+
+// Copy returns a copy of s.
+func (s Set[Elem]) Copy() Set[Elem] {
+	r := Set[Elem]{m: make(map[Elem]struct{}, len(s.m))}
+	for v := range s.m {
+		r.m[v] = struct{}{}
+	}
+	return r
+}
+
+// AddSet adds all the elements of s2 to s.
+func (s Set[Elem]) AddSet(s2 Set[Elem]) {
+	for v := range s2.m {
+		s.m[v] = struct{}{}
+	}
+}
+
+// SubSet removes all elements in s2 from s.
+// Values in s2 that are not in s are ignored.
+func (s Set[Elem]) SubSet(s2 Set[Elem]) {
+	for v := range s2.m {
+		delete(s.m, v)
+	}
+}
+
+// Intersect removes all elements from s that are not present in s2.
+// Values in s2 that are not in s are ignored.
+func (s Set[Elem]) Intersect(s2 Set[Elem]) {
+	for v := range s.m {
+		if !s2.Contains(v) {
+			delete(s.m, v)
+		}
+	}
+}
+
+// Iterate calls f on every element in the set.
+func (s Set[Elem]) Iterate(f func(Elem)) {
+	for v := range s.m {
+		f(v)
+	}
+}
+
+// Filter deletes any elements from s for which f returns false.
+func (s Set[Elem]) Filter(f func(Elem) bool) {
+	for v := range s.m {
+		if !f(v) {
+			delete(s.m, v)
+		}
+	}
+}
diff --git a/test/typeparam/setsimp.dir/main.go b/test/typeparam/setsimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..8fd165714395b1d790a37f980cdfc4bbfcbf191c
--- /dev/null
+++ b/test/typeparam/setsimp.dir/main.go
@@ -0,0 +1,156 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"sort"
+)
+
+func TestSet() {
+	s1 := a.Make[int]()
+	if got := s1.Len(); got != 0 {
+		panic(fmt.Sprintf("Len of empty set = %d, want 0", got))
+	}
+	s1.Add(1)
+	s1.Add(1)
+	s1.Add(1)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	s1.Add(2)
+	s1.Add(3)
+	s1.Add(4)
+	if got := s1.Len(); got != 4 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 4", s1, got))
+	}
+	if !s1.Contains(1) {
+		panic(fmt.Sprintf("(%v).Contains(1) == false, want true", s1))
+	}
+	if s1.Contains(5) {
+		panic(fmt.Sprintf("(%v).Contains(5) == true, want false", s1))
+	}
+	vals := s1.Values()
+	sort.Ints(vals)
+	w1 := []int{1, 2, 3, 4}
+	if !a.SliceEqual(vals, w1) {
+		panic(fmt.Sprintf("(%v).Values() == %v, want %v", s1, vals, w1))
+	}
+}
+
+func TestEqual() {
+	s1 := a.Make[string]()
+	s2 := a.Make[string]()
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s1.Add("hello")
+	s1.Add("world")
+	if got := s1.Len(); got != 2 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 2", s1, got))
+	}
+	if a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", s1, s2))
+	}
+}
+
+func TestCopy() {
+	s1 := a.Make[float64]()
+	s1.Add(0)
+	s2 := s1.Copy()
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s1.Add(1)
+	if a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", s1, s2))
+	}
+}
+
+func TestAddSet() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := a.Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.AddSet(s2)
+	if got := s1.Len(); got != 3 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 3", s1, got))
+	}
+	s2.Add(1)
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+}
+
+func TestSubSet() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := a.Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.SubSet(s2)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	if vals, want := s1.Values(), []int{1}; !a.SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after SubSet got %v, want %v", vals, want))
+	}
+}
+
+func TestIntersect() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := a.Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.Intersect(s2)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	if vals, want := s1.Values(), []int{2}; !a.SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after Intersect got %v, want %v", vals, want))
+	}
+}
+
+func TestIterate() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s1.Add(3)
+	s1.Add(4)
+	tot := 0
+	s1.Iterate(func(i int) { tot += i })
+	if tot != 10 {
+		panic(fmt.Sprintf("total of %v == %d, want 10", s1, tot))
+	}
+}
+
+func TestFilter() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s1.Add(3)
+	s1.Filter(func(v int) bool { return v%2 == 0 })
+	if vals, want := s1.Values(), []int{2}; !a.SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after Filter got %v, want %v", vals, want))
+	}
+
+}
+
+func main() {
+	TestSet()
+	TestEqual()
+	TestCopy()
+	TestAddSet()
+	TestSubSet()
+	TestIntersect()
+	TestIterate()
+	TestFilter()
+}
diff --git a/test/typeparam/setsimp.go b/test/typeparam/setsimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/setsimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/settable.go b/test/typeparam/settable.go
index 588166da8584fad5b19ce4ec32026202fcb420aa..99455e93fa1c908a7543829d63c6510f2a89e59a 100644
--- a/test/typeparam/settable.go
+++ b/test/typeparam/settable.go
@@ -13,13 +13,13 @@ import (
 
 // Various implementations of fromStrings().
 
-type _Setter[B any] interface {
+type Setter[B any] interface {
 	Set(string)
 	type *B
 }
 
 // Takes two type parameters where PT = *T
-func fromStrings1[T any, PT _Setter[T]](s []string) []T {
+func fromStrings1[T any, PT Setter[T]](s []string) []T {
 	result := make([]T, len(s))
 	for i, v := range s {
 		// The type of &result[i] is *T which is in the type list
@@ -31,7 +31,7 @@ func fromStrings1[T any, PT _Setter[T]](s []string) []T {
 	return result
 }
 
-func fromStrings1a[T any, PT _Setter[T]](s []string) []PT {
+func fromStrings1a[T any, PT Setter[T]](s []string) []PT {
 	result := make([]PT, len(s))
 	for i, v := range s {
 		// The type new(T) is *T which is in the type list
@@ -44,7 +44,6 @@ func fromStrings1a[T any, PT _Setter[T]](s []string) []PT {
 	return result
 }
 
-
 // Takes one type parameter and a set function
 func fromStrings2[T any](s []string, set func(*T, string)) []T {
 	results := make([]T, len(s))
@@ -54,12 +53,12 @@ func fromStrings2[T any](s []string, set func(*T, string)) []T {
 	return results
 }
 
-type _Setter2 interface {
+type Setter2 interface {
 	Set(string)
 }
 
 // Takes only one type parameter, but causes a panic (see below)
-func fromStrings3[T _Setter2](s []string) []T {
+func fromStrings3[T Setter2](s []string) []T {
 	results := make([]T, len(s))
 	for i, v := range s {
 		// Panics if T is a pointer type because receiver is T(nil).
diff --git a/test/typeparam/shape1.go b/test/typeparam/shape1.go
new file mode 100644
index 0000000000000000000000000000000000000000..de1ea65ed227faa5da63301aad4c5a4573f43dcb
--- /dev/null
+++ b/test/typeparam/shape1.go
@@ -0,0 +1,50 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type I interface {
+	foo() int
+}
+
+// There should be one instantiation of f for both squarer and doubler.
+// Similarly, there should be one instantiation of f for both *incrementer and *decrementer.
+func f[T I](x T) int {
+	return x.foo()
+}
+
+type squarer int
+
+func (x squarer) foo() int {
+	return int(x*x)
+}
+
+type doubler int
+
+func (x doubler) foo() int {
+	return int(2*x)
+}
+
+type incrementer int16
+
+func (x *incrementer) foo() int {
+	return int(*x+1)
+}
+
+type decrementer int32
+
+func (x *decrementer) foo() int{
+	return int(*x-1)
+}
+
+func main() {
+	println(f(squarer(5)))
+	println(f(doubler(5)))
+	var i incrementer = 5
+	println(f(&i))
+	var d decrementer = 5
+	println(f(&d))
+}
diff --git a/test/typeparam/shape1.out b/test/typeparam/shape1.out
new file mode 100644
index 0000000000000000000000000000000000000000..da9a12ded55a5e58b371ee3a4e6c00be8eb0cdc7
--- /dev/null
+++ b/test/typeparam/shape1.out
@@ -0,0 +1,4 @@
+25
+10
+6
+4
diff --git a/test/typeparam/sliceimp.dir/a.go b/test/typeparam/sliceimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..da12e9f9fc9ededbb4a4f477cf8a979de9096e21
--- /dev/null
+++ b/test/typeparam/sliceimp.dir/a.go
@@ -0,0 +1,141 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
+}
+
+// Max returns the maximum of two values of some ordered type.
+func Max[T Ordered](a, b T) T {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+// Min returns the minimum of two values of some ordered type.
+func Min[T Ordered](a, b T) T {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func Equal[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// EqualFn reports whether two slices are equal using a comparision
+// function on each element.
+func EqualFn[Elem any](s1, s2 []Elem, eq func(Elem, Elem) bool) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if !eq(v1, v2) {
+			return false
+		}
+	}
+	return true
+}
+
+// Map turns a []Elem1 to a []Elem2 using a mapping function.
+func Map[Elem1, Elem2 any](s []Elem1, f func(Elem1) Elem2) []Elem2 {
+	r := make([]Elem2, len(s))
+	for i, v := range s {
+		r[i] = f(v)
+	}
+	return r
+}
+
+// Reduce reduces a []Elem1 to a single value of type Elem2 using
+// a reduction function.
+func Reduce[Elem1, Elem2 any](s []Elem1, initializer Elem2, f func(Elem2, Elem1) Elem2) Elem2 {
+	r := initializer
+	for _, v := range s {
+		r = f(r, v)
+	}
+	return r
+}
+
+// Filter filters values from a slice using a filter function.
+func Filter[Elem any](s []Elem, f func(Elem) bool) []Elem {
+	var r []Elem
+	for _, v := range s {
+		if f(v) {
+			r = append(r, v)
+		}
+	}
+	return r
+}
+
+// Max returns the maximum element in a slice of some ordered type.
+// If the slice is empty it returns the zero value of the element type.
+func SliceMax[Elem Ordered](s []Elem) Elem {
+	if len(s) == 0 {
+		var zero Elem
+		return zero
+	}
+	return Reduce(s[1:], s[0], Max[Elem])
+}
+
+// Min returns the minimum element in a slice of some ordered type.
+// If the slice is empty it returns the zero value of the element type.
+func SliceMin[Elem Ordered](s []Elem) Elem {
+	if len(s) == 0 {
+		var zero Elem
+		return zero
+	}
+	return Reduce(s[1:], s[0], Min[Elem])
+}
+
+// Append adds values to the end of a slice, returning a new slice.
+// This is like the predeclared append function; it's an example
+// of how to write it using generics. We used to write code like
+// this before append was added to the language, but we had to write
+// a separate copy for each type.
+func Append[T any](s []T, t ...T) []T {
+	lens := len(s)
+	tot := lens + len(t)
+	if tot <= cap(s) {
+		s = s[:tot]
+	} else {
+		news := make([]T, tot, tot+tot/2)
+		Copy(news, s)
+		s = news
+	}
+	Copy(s[lens:tot], t)
+	return s
+}
+
+// Copy copies values from t to s, stopping when either slice is full,
+// returning the number of values copied. This is like the predeclared
+// copy function; it's an example of how to write it using generics.
+func Copy[T any](s, t []T) int {
+	i := 0
+	for ; i < len(s) && i < len(t); i++ {
+		s[i] = t[i]
+	}
+	return i
+}
diff --git a/test/typeparam/sliceimp.dir/main.go b/test/typeparam/sliceimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..0f79e10018b17f7e9062316c0db711ba1a91871d
--- /dev/null
+++ b/test/typeparam/sliceimp.dir/main.go
@@ -0,0 +1,179 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"math"
+	"strings"
+)
+
+type Integer interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
+}
+
+func TestEqual() {
+	s1 := []int{1, 2, 3}
+	if !a.Equal(s1, s1) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s1))
+	}
+	s2 := []int{1, 2, 3}
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s2 = append(s2, 4)
+	if a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", s1, s2))
+	}
+
+	s3 := []float64{1, 2, math.NaN()}
+	if !a.Equal(s3, s3) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s3, s3))
+	}
+
+	if a.Equal(s1, nil) {
+		panic(fmt.Sprintf("a.Equal(%v, nil) = true, want false", s1))
+	}
+	if a.Equal(nil, s1) {
+		panic(fmt.Sprintf("a.Equal(nil, %v) = true, want false", s1))
+	}
+	if !a.Equal(s1[:0], nil) {
+		panic(fmt.Sprintf("a.Equal(%v, nil = false, want true", s1[:0]))
+	}
+}
+
+func offByOne[Elem Integer](a, b Elem) bool {
+	return a == b+1 || a == b-1
+}
+
+func TestEqualFn() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{2, 3, 4}
+	if a.EqualFn(s1, s1, offByOne[int]) {
+		panic(fmt.Sprintf("a.EqualFn(%v, %v, offByOne) = true, want false", s1, s1))
+	}
+	if !a.EqualFn(s1, s2, offByOne[int]) {
+		panic(fmt.Sprintf("a.EqualFn(%v, %v, offByOne) = false, want true", s1, s2))
+	}
+
+	if !a.EqualFn(s1[:0], nil, offByOne[int]) {
+		panic(fmt.Sprintf("a.EqualFn(%v, nil, offByOne) = false, want true", s1[:0]))
+	}
+
+	s3 := []string{"a", "b", "c"}
+	s4 := []string{"A", "B", "C"}
+	if !a.EqualFn(s3, s4, strings.EqualFold) {
+		panic(fmt.Sprintf("a.EqualFn(%v, %v, strings.EqualFold) = false, want true", s3, s4))
+	}
+}
+
+func TestMap() {
+	s1 := []int{1, 2, 3}
+	s2 := a.Map(s1, func(i int) float64 { return float64(i) * 2.5 })
+	if want := []float64{2.5, 5, 7.5}; !a.Equal(s2, want) {
+		panic(fmt.Sprintf("a.Map(%v, ...) = %v, want %v", s1, s2, want))
+	}
+
+	s3 := []string{"Hello", "World"}
+	s4 := a.Map(s3, strings.ToLower)
+	if want := []string{"hello", "world"}; !a.Equal(s4, want) {
+		panic(fmt.Sprintf("a.Map(%v, strings.ToLower) = %v, want %v", s3, s4, want))
+	}
+
+	s5 := a.Map(nil, func(i int) int { return i })
+	if len(s5) != 0 {
+		panic(fmt.Sprintf("a.Map(nil, identity) = %v, want empty slice", s5))
+	}
+}
+
+func TestReduce() {
+	s1 := []int{1, 2, 3}
+	r := a.Reduce(s1, 0, func(f float64, i int) float64 { return float64(i)*2.5 + f })
+	if want := 15.0; r != want {
+		panic(fmt.Sprintf("a.Reduce(%v, 0, ...) = %v, want %v", s1, r, want))
+	}
+
+	if got := a.Reduce(nil, 0, func(i, j int) int { return i + j }); got != 0 {
+		panic(fmt.Sprintf("a.Reduce(nil, 0, add) = %v, want 0", got))
+	}
+}
+
+func TestFilter() {
+	s1 := []int{1, 2, 3}
+	s2 := a.Filter(s1, func(i int) bool { return i%2 == 0 })
+	if want := []int{2}; !a.Equal(s2, want) {
+		panic(fmt.Sprintf("a.Filter(%v, even) = %v, want %v", s1, s2, want))
+	}
+
+	if s3 := a.Filter(s1[:0], func(i int) bool { return true }); len(s3) > 0 {
+		panic(fmt.Sprintf("a.Filter(%v, identity) = %v, want empty slice", s1[:0], s3))
+	}
+}
+
+func TestMax() {
+	s1 := []int{1, 2, 3, -5}
+	if got, want := a.SliceMax(s1), 3; got != want {
+		panic(fmt.Sprintf("a.Max(%v) = %d, want %d", s1, got, want))
+	}
+
+	s2 := []string{"aaa", "a", "aa", "aaaa"}
+	if got, want := a.SliceMax(s2), "aaaa"; got != want {
+		panic(fmt.Sprintf("a.Max(%v) = %q, want %q", s2, got, want))
+	}
+
+	if got, want := a.SliceMax(s2[:0]), ""; got != want {
+		panic(fmt.Sprintf("a.Max(%v) = %q, want %q", s2[:0], got, want))
+	}
+}
+
+func TestMin() {
+	s1 := []int{1, 2, 3, -5}
+	if got, want := a.SliceMin(s1), -5; got != want {
+		panic(fmt.Sprintf("a.Min(%v) = %d, want %d", s1, got, want))
+	}
+
+	s2 := []string{"aaa", "a", "aa", "aaaa"}
+	if got, want := a.SliceMin(s2), "a"; got != want {
+		panic(fmt.Sprintf("a.Min(%v) = %q, want %q", s2, got, want))
+	}
+
+	if got, want := a.SliceMin(s2[:0]), ""; got != want {
+		panic(fmt.Sprintf("a.Min(%v) = %q, want %q", s2[:0], got, want))
+	}
+}
+
+func TestAppend() {
+	s := []int{1, 2, 3}
+	s = a.Append(s, 4, 5, 6)
+	want := []int{1, 2, 3, 4, 5, 6}
+	if !a.Equal(s, want) {
+		panic(fmt.Sprintf("after a.Append got %v, want %v", s, want))
+	}
+}
+
+func TestCopy() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{4, 5}
+	if got := a.Copy(s1, s2); got != 2 {
+		panic(fmt.Sprintf("a.Copy returned %d, want 2", got))
+	}
+	want := []int{4, 5, 3}
+	if !a.Equal(s1, want) {
+		panic(fmt.Sprintf("after a.Copy got %v, want %v", s1, want))
+	}
+}
+func main() {
+	TestEqual()
+	TestEqualFn()
+	TestMap()
+	TestReduce()
+	TestFilter()
+	TestMax()
+	TestMin()
+	TestAppend()
+	TestCopy()
+}
diff --git a/test/typeparam/sliceimp.go b/test/typeparam/sliceimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/sliceimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/slices.go b/test/typeparam/slices.go
index 149199eb64909db8844208f2fdcb4de78baa235e..4bdf10748e50c33c5b82b4a04fbc8db95fed12db 100644
--- a/test/typeparam/slices.go
+++ b/test/typeparam/slices.go
@@ -15,31 +15,31 @@ import (
 )
 
 type Ordered interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64,
-                string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 type Integer interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
 }
 
 // Max returns the maximum of two values of some ordered type.
 func _Max[T Ordered](a, b T) T {
-        if a > b {
-                return a
-        }
-        return b
+	if a > b {
+		return a
+	}
+	return b
 }
 
 // Min returns the minimum of two values of some ordered type.
 func _Min[T Ordered](a, b T) T {
-        if a < b {
-                return a
-        }
-        return b
+	if a < b {
+		return a
+	}
+	return b
 }
 
 // _Equal reports whether two slices are equal: the same length and all
@@ -60,7 +60,7 @@ func _Equal[Elem comparable](s1, s2 []Elem) bool {
 	return true
 }
 
-// _EqualFn reports whether two slices are equal using a comparision
+// _EqualFn reports whether two slices are equal using a comparison
 // function on each element.
 func _EqualFn[Elem any](s1, s2 []Elem, eq func(Elem, Elem) bool) bool {
 	if len(s1) != len(s2) {
@@ -136,7 +136,7 @@ func _Append[T any](s []T, t ...T) []T {
 	if tot <= cap(s) {
 		s = s[:tot]
 	} else {
-		news := make([]T, tot, tot + tot/2)
+		news := make([]T, tot, tot+tot/2)
 		_Copy(news, s)
 		s = news
 	}
@@ -156,37 +156,37 @@ func _Copy[T any](s, t []T) int {
 }
 
 func TestEqual() {
-        s1 := []int{1, 2, 3}
-        if !_Equal(s1, s1) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s1))
-        }
-        s2 := []int{1, 2, 3}
-        if !_Equal(s1, s2) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
-        }
-        s2 = append(s2, 4)
-        if _Equal(s1, s2) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
-        }
-
-        s3 := []float64{1, 2, math.NaN()}
-        if !_Equal(s3, s3) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s3, s3))
-        }
-
-        if _Equal(s1, nil) {
-                panic(fmt.Sprintf("_Equal(%v, nil) = true, want false", s1))
-        }
-        if _Equal(nil, s1) {
-                panic(fmt.Sprintf("_Equal(nil, %v) = true, want false", s1))
-        }
-        if !_Equal(s1[:0], nil) {
-                panic(fmt.Sprintf("_Equal(%v, nil = false, want true", s1[:0]))
-        }
+	s1 := []int{1, 2, 3}
+	if !_Equal(s1, s1) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s1))
+	}
+	s2 := []int{1, 2, 3}
+	if !_Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s2 = append(s2, 4)
+	if _Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
+	}
+
+	s3 := []float64{1, 2, math.NaN()}
+	if !_Equal(s3, s3) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s3, s3))
+	}
+
+	if _Equal(s1, nil) {
+		panic(fmt.Sprintf("_Equal(%v, nil) = true, want false", s1))
+	}
+	if _Equal(nil, s1) {
+		panic(fmt.Sprintf("_Equal(nil, %v) = true, want false", s1))
+	}
+	if !_Equal(s1[:0], nil) {
+		panic(fmt.Sprintf("_Equal(%v, nil = false, want true", s1[:0]))
+	}
 }
 
 func offByOne[Elem Integer](a, b Elem) bool {
-	return a == b + 1 || a == b - 1
+	return a == b+1 || a == b-1
 }
 
 func TestEqualFn() {
@@ -231,12 +231,12 @@ func TestMap() {
 
 func TestReduce() {
 	s1 := []int{1, 2, 3}
-	r := _Reduce(s1, 0, func(f float64, i int) float64 { return float64(i) * 2.5 + f })
+	r := _Reduce(s1, 0, func(f float64, i int) float64 { return float64(i)*2.5 + f })
 	if want := 15.0; r != want {
 		panic(fmt.Sprintf("_Reduce(%v, 0, ...) = %v, want %v", s1, r, want))
 	}
 
-	if got := _Reduce(nil, 0, func(i, j int) int { return i + j}); got != 0 {
+	if got := _Reduce(nil, 0, func(i, j int) int { return i + j }); got != 0 {
 		panic(fmt.Sprintf("_Reduce(nil, 0, add) = %v, want 0", got))
 	}
 }
diff --git a/test/typeparam/smallest.go b/test/typeparam/smallest.go
index 63dd9ddb700fe3ee49eeeadc4dd4b4778c5f441d..af1d72d89928fd9638c3aaed1cee404e1f5f6869 100644
--- a/test/typeparam/smallest.go
+++ b/test/typeparam/smallest.go
@@ -11,13 +11,13 @@ import (
 )
 
 type Ordered interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
-func smallest[T Ordered](s []T) T {
+func Smallest[T Ordered](s []T) T {
 	r := s[0] // panics if slice is empty
 	for _, v := range s[1:] {
 		if v < r {
@@ -32,11 +32,11 @@ func main() {
 	vec2 := []string{"abc", "def", "aaa"}
 
 	want1 := 1.2
-	if got := smallest(vec1); got != want1 {
+	if got := Smallest(vec1); got != want1 {
 		panic(fmt.Sprintf("got %d, want %d", got, want1))
 	}
 	want2 := "aaa"
-	if got := smallest(vec2); got != want2 {
+	if got := Smallest(vec2); got != want2 {
 		panic(fmt.Sprintf("got %d, want %d", got, want2))
 	}
 }
diff --git a/test/typeparam/smoketest.go b/test/typeparam/smoketest.go
index b7d6201b2c12494eeee64f2a9eb0b0bbc38c356c..f32b40062d6bc8ca75ae25ef5dbe64054ff5ea35 100644
--- a/test/typeparam/smoketest.go
+++ b/test/typeparam/smoketest.go
@@ -1,4 +1,4 @@
-// compile -G
+// compile -G=1
 
 // Copyright 2020 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -9,9 +9,9 @@
 package smoketest
 
 // type parameters for functions
-func f1[P any]()
-func f2[P1, P2 any, P3 any]()
-func f3[P interface{}](x P, y T1[int])
+func f1[P any]() {}
+func f2[P1, P2 any, P3 any]() {}
+func f3[P interface{}](x P, y T1[int]) {}
 
 // function instantiations
 var _ = f1[int]
@@ -29,15 +29,15 @@ type _ T2[int, string, struct{}]
 type _ T3[bool]
 
 // methods
-func (T1[P]) m1() {}
-func (T1[_]) m2() {}
+func (T1[P]) m1()           {}
+func (T1[_]) m2()           {}
 func (x T2[P1, P2, P3]) m() {}
 
 // type lists
 type _ interface {
 	m1()
 	m2()
-	type int, float32, string
+	int | float32 | string
 	m3()
 }
 
diff --git a/test/typeparam/stringable.go b/test/typeparam/stringable.go
index 9340a3b10a9d188dd3eca552189a840f884146cb..855a1edb3bf6884a9917d362d94d987ad00faec2 100644
--- a/test/typeparam/stringable.go
+++ b/test/typeparam/stringable.go
@@ -16,11 +16,11 @@ type Stringer interface {
 	String() string
 }
 
-// stringableList is a slice of some type, where the type
+// StringableList is a slice of some type, where the type
 // must have a String method.
-type stringableList[T Stringer] []T
+type StringableList[T Stringer] []T
 
-func (s stringableList[T]) String() string {
+func (s StringableList[T]) String() string {
 	var sb strings.Builder
 	for i, v := range s {
 		if i > 0 {
@@ -38,9 +38,9 @@ func (a myint) String() string {
 }
 
 func main() {
-	v := stringableList[myint]{ myint(1), myint(2) }
+	v := StringableList[myint]{myint(1), myint(2)}
 
 	if got, want := v.String(), "1, 2"; got != want {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 }
diff --git a/test/typeparam/stringerimp.dir/a.go b/test/typeparam/stringerimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..3f70937ff55e862ed1fbf8dc206d830f56a97f59
--- /dev/null
+++ b/test/typeparam/stringerimp.dir/a.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Stringer interface {
+	String() string
+}
+
+func Stringify[T Stringer](s []T) (ret []string) {
+	for _, v := range s {
+		ret = append(ret, v.String())
+	}
+	return ret
+}
diff --git a/test/typeparam/stringerimp.dir/main.go b/test/typeparam/stringerimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..e30bdf1abeb671c426b0d69193a6cf648c25f78d
--- /dev/null
+++ b/test/typeparam/stringerimp.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+type myint int
+
+func (i myint) String() string {
+	return strconv.Itoa(int(i))
+}
+
+func main() {
+	x := []myint{myint(1), myint(2), myint(3)}
+
+	got := a.Stringify(x)
+	want := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got, want) {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+
+	m1 := myint(1)
+	m2 := myint(2)
+	m3 := myint(3)
+	y := []*myint{&m1, &m2, &m3}
+	got2 := a.Stringify(y)
+	want2 := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got2, want2) {
+		panic(fmt.Sprintf("got %s, want %s", got2, want2))
+	}
+}
diff --git a/test/typeparam/stringerimp.go b/test/typeparam/stringerimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/stringerimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/struct.go b/test/typeparam/struct.go
index 98f0fcd888839dbea21f59f2bc5218e96dbe1b05..ad1b41ddac40dc5d1ef0966c8413ff569b752734 100644
--- a/test/typeparam/struct.go
+++ b/test/typeparam/struct.go
@@ -10,40 +10,40 @@ import (
 	"fmt"
 )
 
-type _E[T any] struct {
+type E[T any] struct {
 	v T
 }
 
-type _S1 struct {
-	_E[int]
+type S1 struct {
+	E[int]
 	v string
 }
 
-type _Eint = _E[int]
-type _Ebool = _E[bool]
+type Eint = E[int]
+type Ebool = E[bool]
 
-type _S2 struct {
-	_Eint
-	_Ebool
+type S2 struct {
+	Eint
+	Ebool
 	v string
 }
 
-type _S3 struct {
-	*_E[int]
+type S3 struct {
+	*E[int]
 }
 
 func main() {
-	s1 := _S1{_Eint{2}, "foo"}
-	if got, want := s1._E.v, 2; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+	s1 := S1{Eint{2}, "foo"}
+	if got, want := s1.E.v, 2; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	s2 := _S2{_Eint{3}, _Ebool{true}, "foo"}
-	if got, want := s2._Eint.v, 3; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+	s2 := S2{Eint{3}, Ebool{true}, "foo"}
+	if got, want := s2.Eint.v, 3; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	var s3 _S3
-	s3._E = &_Eint{4}
-	if got, want := s3._E.v, 4; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+	var s3 S3
+	s3.E = &Eint{4}
+	if got, want := s3.E.v, 4; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 }
diff --git a/test/typeparam/subdict.go b/test/typeparam/subdict.go
new file mode 100644
index 0000000000000000000000000000000000000000..b4e84baf8a7fb3e4a6b57b6fce273bad22ef8eb4
--- /dev/null
+++ b/test/typeparam/subdict.go
@@ -0,0 +1,41 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test cases where a main dictionary is needed inside a generic function/method, because
+// we are calling a method on a fully-instantiated type or a fully-instantiated function.
+// (probably not common situations, of course)
+
+package main
+
+import (
+	"fmt"
+)
+
+type value[T comparable] struct {
+	val T
+}
+
+func (v *value[T]) test(def T) bool {
+	return (v.val == def)
+}
+
+func (v *value[T]) get(def T) T {
+	var c value[int]
+	if c.test(32) {
+		return def
+	} else if v.test(def) {
+		return def
+	} else {
+		return v.val
+	}
+}
+
+func main() {
+	var s value[string]
+	if got, want := s.get("ab"), ""; got != want {
+		panic(fmt.Sprintf("get() == %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/sum.go b/test/typeparam/sum.go
index f0f5e6aa07537b4627acf7d049341c835e4aaa00..d444e007a3a492605e0010adb5b3f6e62916793e 100644
--- a/test/typeparam/sum.go
+++ b/test/typeparam/sum.go
@@ -10,7 +10,7 @@ import (
 	"fmt"
 )
 
-func sum[T interface{ type int, float64 }](vec []T) T {
+func Sum[T interface{ int | float64 }](vec []T) T {
 	var sum T
 	for _, elt := range vec {
 		sum = sum + elt
@@ -18,7 +18,7 @@ func sum[T interface{ type int, float64 }](vec []T) T {
 	return sum
 }
 
-func abs(f float64) float64 {
+func Abs(f float64) float64 {
 	if f < 0.0 {
 		return -f
 	}
@@ -28,23 +28,23 @@ func abs(f float64) float64 {
 func main() {
 	vec1 := []int{3, 4}
 	vec2 := []float64{5.8, 9.6}
-	got := sum[int](vec1)
+	got := Sum[int](vec1)
 	want := vec1[0] + vec1[1]
 	if got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	got = sum(vec1)
+	got = Sum(vec1)
 	if want != got {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	fwant := vec2[0] + vec2[1]
-	fgot := sum[float64](vec2)
-	if abs(fgot - fwant) > 1e-10 {
+	fgot := Sum[float64](vec2)
+	if Abs(fgot-fwant) > 1e-10 {
 		panic(fmt.Sprintf("got %f, want %f", fgot, fwant))
 	}
-	fgot = sum(vec2)
-	if abs(fgot - fwant) > 1e-10 {
+	fgot = Sum(vec2)
+	if Abs(fgot-fwant) > 1e-10 {
 		panic(fmt.Sprintf("got %f, want %f", fgot, fwant))
 	}
 }
diff --git a/test/typeparam/tparam1.go b/test/typeparam/tparam1.go
index 70439333269a704bc5f911bf7d68ac41be17ca92..698877a6f00d65d13bc0c76edb2a6d3928644c00 100644
--- a/test/typeparam/tparam1.go
+++ b/test/typeparam/tparam1.go
@@ -10,33 +10,33 @@ package tparam1
 
 // The predeclared identifier "any" is only visible as a constraint
 // in a type parameter list.
-var _ any // ERROR "undefined"
-func _(_ any) // ERROR "undefined"
-type _[_ any /* ok here */ ] struct{}
+var _ any     // ERROR "cannot use any outside constraint position"
+func _(_ any) // ERROR "cannot use any outside constraint position"
+type _[_ any /* ok here */] struct{}
 
 const N = 10
 
 type (
-        _[] struct{} // slice
-        _[N] struct{} // array
-        _[T any] struct{}
-        _[T, T any] struct{} // ERROR "T redeclared"
-        _[T1, T2 any, T3 any] struct{}
+	_                     []struct{}  // slice
+	_                     [N]struct{} // array
+	_[T any]              struct{}
+	_[T, T any]           struct{} // ERROR "T redeclared"
+	_[T1, T2 any, T3 any] struct{}
 )
 
-func _[T any]()
-func _[T, T any]() // ERROR "T redeclared"
-func _[T1, T2 any](x T1) T2
+func _[T any]() {}
+func _[T, T any]() {} // ERROR "T redeclared"
+func _[T1, T2 any](x T1) T2 { panic(0) }
 
 // Type parameters are visible from opening [ to end of function.
 type C interface{}
 
-func _[T interface{}]()
-func _[T C]()
-func _[T struct{}]() // ERROR "not an interface"
-func _[T interface{ m() T }]()
+func _[T interface{}]() {}
+func _[T C]() {}
+func _[T struct{}]() {}// ERROR "not an interface"
+func _[T interface{ m() T }]() {}
 func _[T1 interface{ m() T2 }, T2 interface{ m() T1 }]() {
-        var _ T1
+	var _ T1
 }
 
 // TODO(gri) expand this
diff --git a/test/typeparam/typelist.go b/test/typeparam/typelist.go
index bd90d86fcf2a36f1edf58d781b20e93a4d6308e1..5ba14261ab0823efee35dc1e626906316daabfe2 100644
--- a/test/typeparam/typelist.go
+++ b/test/typeparam/typelist.go
@@ -10,19 +10,19 @@ package p
 
 // Assignability of an unnamed pointer type to a type parameter that
 // has a matching underlying type.
-func _[T interface{}, PT interface{type *T}] (x T) PT {
-    return &x
+func _[T interface{}, PT interface{ type *T }](x T) PT {
+	return &x
 }
 
 // Indexing of generic types containing type parameters in their type list:
 func at[T interface{ type []E }, E any](x T, i int) E {
-        return x[i]
+	return x[i]
 }
 
 // A generic type inside a function acts like a named type. Its underlying
 // type is itself, its "operational type" is defined by the type list in
 // the tybe bound, if any.
-func _[T interface{type int}](x T) {
+func _[T interface{ type int }](x T) {
 	type myint int
 	var _ int = int(x)
 	var _ T = 42
@@ -30,7 +30,7 @@ func _[T interface{type int}](x T) {
 }
 
 // Indexing a generic type which has a structural contraints to be an array.
-func _[T interface { type [10]int }](x T) {
+func _[T interface{ type [10]int }](x T) {
 	_ = x[9] // ok
 }
 
@@ -44,7 +44,7 @@ func _[T interface{ type *int }](p T) int {
 func _[T interface{ type chan int }](ch T) int {
 	// This would deadlock if executed (but ok for a compile test)
 	ch <- 0
-	return <- ch
+	return <-ch
 }
 
 // Calling of a generic type which has a structural constraint to be a function.
@@ -59,32 +59,34 @@ func _[T interface{ type func(string) int }](f T) int {
 }
 
 // Map access of a generic type which has a structural constraint to be a map.
-func _[V any, T interface { type map[string]V }](p T) V {
+func _[V any, T interface{ type map[string]V }](p T) V {
 	return p["test"]
 }
 
-
 // Testing partial and full type inference, including the case where the types can
 // be inferred without needing the types of the function arguments.
 
+// Cannot embed stand-alone type parameters. Disabled for now.
+/*
 func f0[A any, B interface{type C}, C interface{type D}, D interface{type A}](A, B, C, D)
-func _() {
+func f0x() {
         f := f0[string]
         f("a", "b", "c", "d")
         f0("a", "b", "c", "d")
 }
 
 func f1[A any, B interface{type A}](A, B)
-func _() {
+func f1x() {
         f := f1[int]
         f(int(0), int(0))
         f1(int(0), int(0))
         f(0, 0)
         f1(0, 0)
 }
+*/
 
-func f2[A any, B interface{type []A}](_ A, _ B)
-func _() {
+func f2[A any, B interface{ type []A }](_ A, _ B) {}
+func f2x() {
 	f := f2[byte]
 	f(byte(0), []byte{})
 	f2(byte(0), []byte{})
@@ -92,31 +94,39 @@ func _() {
 	// f2(0, []byte{}) - this one doesn't work
 }
 
+// Cannot embed stand-alone type parameters. Disabled for now.
+/*
 func f3[A any, B interface{type C}, C interface{type *A}](a A, _ B, c C)
-func _() {
+func f3x() {
 	f := f3[int]
 	var x int
 	f(x, &x, &x)
 	f3(x, &x, &x)
 }
+*/
 
-func f4[A any, B interface{type []C}, C interface{type *A}](_ A, _ B, c C)
-func _() {
+func f4[A any, B interface{ type []C }, C interface{ type *A }](_ A, _ B, c C) {}
+func f4x() {
 	f := f4[int]
 	var x int
 	f(x, []*int{}, &x)
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{type struct{b B; c C}}, B any, C interface{type *B}](x B) A
-func _() {
+func f5[A interface {
+	type struct {
+		b B
+		c C
+	}
+}, B any, C interface{ type *B }](x B) A { panic(0) }
+func f5x() {
 	x := f5(1.2)
 	var _ float64 = x.b
 	var _ float64 = *x.c
 }
 
-func f6[A any, B interface{type struct{f []A}}](B) A
-func _() {
-	x := f6(struct{f []string}{})
+func f6[A any, B interface{ type struct{ f []A } }](B) A { panic(0) }
+func f6x() {
+	x := f6(struct{ f []string }{})
 	var _ string = x
 }
diff --git a/test/typeparam/typeswitch1.go b/test/typeparam/typeswitch1.go
new file mode 100644
index 0000000000000000000000000000000000000000..27161b3db8045a560698c89fae1155282c078c18
--- /dev/null
+++ b/test/typeparam/typeswitch1.go
@@ -0,0 +1,29 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](i interface{}) {
+	switch i.(type) {
+	case T:
+		println("T")
+	case int:
+		println("int")
+	case int32, int16:
+		println("int32/int16")
+	case struct { a, b T }:
+		println("struct{T,T}")
+	default:
+		println("other")
+	}
+}
+func main() {
+	f[float64](float64(6))
+	f[float64](int(7))
+	f[float64](int32(8))
+	f[float64](struct{a, b float64}{a:1, b:2})
+	f[float64](int8(9))
+}
diff --git a/test/typeparam/typeswitch1.out b/test/typeparam/typeswitch1.out
new file mode 100644
index 0000000000000000000000000000000000000000..4bdbccfddb357ae52f65dfe4223be799a1b1eebe
--- /dev/null
+++ b/test/typeparam/typeswitch1.out
@@ -0,0 +1,5 @@
+T
+int
+int32/int16
+struct{T,T}
+other
diff --git a/test/typeparam/typeswitch2.go b/test/typeparam/typeswitch2.go
new file mode 100644
index 0000000000000000000000000000000000000000..913c56321cc7a6f790483d608b55b37e14593727
--- /dev/null
+++ b/test/typeparam/typeswitch2.go
@@ -0,0 +1,31 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "reflect"
+
+func f[T any](i interface{}) {
+	switch x := i.(type) {
+	case T:
+		println("T", x)
+	case int:
+		println("int", x)
+	case int32, int16:
+		println("int32/int16", reflect.ValueOf(x).Int())
+	case struct { a, b T }:
+		println("struct{T,T}", x.a, x.b)
+	default:
+		println("other", reflect.ValueOf(x).Int())
+	}
+}
+func main() {
+	f[float64](float64(6))
+	f[float64](int(7))
+	f[float64](int32(8))
+	f[float64](struct{a, b float64}{a:1, b:2})
+	f[float64](int8(9))
+}
diff --git a/test/typeparam/typeswitch2.out b/test/typeparam/typeswitch2.out
new file mode 100644
index 0000000000000000000000000000000000000000..944cc04cc6e60946437637b7ab552439de18b506
--- /dev/null
+++ b/test/typeparam/typeswitch2.out
@@ -0,0 +1,5 @@
+T +6.000000e+000
+int 7
+int32/int16 8
+struct{T,T} +1.000000e+000 +2.000000e+000
+other 9
diff --git a/test/typeparam/typeswitch3.go b/test/typeparam/typeswitch3.go
new file mode 100644
index 0000000000000000000000000000000000000000..6ab030114095d6022a35d9f61a0801af597331c8
--- /dev/null
+++ b/test/typeparam/typeswitch3.go
@@ -0,0 +1,35 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type I interface { foo() int }
+
+type myint int
+
+func (x myint) foo() int { return int(x) }
+
+type myfloat float64
+func (x myfloat) foo() int { return int(x) }
+
+type myint32 int32
+func (x myint32) foo() int { return int(x) }
+
+func f[T I](i I) {
+	switch x := i.(type) {
+	case T:
+		println("T", x.foo())
+	case myint:
+		println("myint", x.foo())
+	default:
+		println("other", x.foo())
+	}
+}
+func main() {
+	f[myfloat](myint(6))
+	f[myfloat](myfloat(7))
+	f[myfloat](myint32(8))
+}
diff --git a/test/typeparam/typeswitch3.out b/test/typeparam/typeswitch3.out
new file mode 100644
index 0000000000000000000000000000000000000000..2c69c72c300f6e7163d3bd12367eb001ca61d337
--- /dev/null
+++ b/test/typeparam/typeswitch3.out
@@ -0,0 +1,3 @@
+myint 6
+T 7
+other 8
diff --git a/test/typeparam/typeswitch4.go b/test/typeparam/typeswitch4.go
new file mode 100644
index 0000000000000000000000000000000000000000..6113026b65823bfd541eae70f1f9e31a0d9c5cd2
--- /dev/null
+++ b/test/typeparam/typeswitch4.go
@@ -0,0 +1,33 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type I interface { foo() int }
+
+type myint int
+
+func (x myint) foo() int {return int(x)}
+
+type myfloat float64
+func (x myfloat) foo() int {return int(x)}
+
+type myint32 int32
+func (x myint32) foo() int { return int(x) }
+
+func f[T I](i I) {
+	switch x := i.(type) {
+	case T, myint32:
+		println("T/myint32", x.foo())
+	default:
+		println("other", x.foo())
+	}
+}
+func main() {
+	f[myfloat](myint(6))
+	f[myfloat](myfloat(7))
+	f[myfloat](myint32(8))
+}
diff --git a/test/typeparam/typeswitch4.out b/test/typeparam/typeswitch4.out
new file mode 100644
index 0000000000000000000000000000000000000000..b0d54077c926104cac85a5c1bc0bec496f0cba9d
--- /dev/null
+++ b/test/typeparam/typeswitch4.out
@@ -0,0 +1,3 @@
+other 6
+T/myint32 7
+T/myint32 8
diff --git a/test/typeparam/typeswitch5.go b/test/typeparam/typeswitch5.go
new file mode 100644
index 0000000000000000000000000000000000000000..1fc6e0a14ee533680f7c704b23d60551ab7d3f16
--- /dev/null
+++ b/test/typeparam/typeswitch5.go
@@ -0,0 +1,28 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type myint int
+func (x myint) foo() int {return int(x)}
+
+type myfloat float64
+func (x myfloat) foo() float64 {return float64(x) }
+
+func f[T any](i interface{}) {
+	switch x := i.(type) {
+	case interface { foo() T }:
+		println("fooer", x.foo())
+	default:
+		println("other")
+	}
+}
+func main() {
+	f[int](myint(6))
+	f[int](myfloat(7))
+	f[float64](myint(8))
+	f[float64](myfloat(9))
+}
diff --git a/test/typeparam/typeswitch5.out b/test/typeparam/typeswitch5.out
new file mode 100644
index 0000000000000000000000000000000000000000..6b4cb4416f4536f81658050e0a3e9548728cfc09
--- /dev/null
+++ b/test/typeparam/typeswitch5.out
@@ -0,0 +1,4 @@
+fooer 6
+other
+other
+fooer +9.000000e+000
diff --git a/test/typeparam/typeswitch6.go b/test/typeparam/typeswitch6.go
new file mode 100644
index 0000000000000000000000000000000000000000..574f4aa819eecf6cf519f5ae36824e5f9d16c5d5
--- /dev/null
+++ b/test/typeparam/typeswitch6.go
@@ -0,0 +1,30 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](i interface{}) {
+	switch i.(type) {
+	case T:
+		println("T")
+	case int:
+		println("int")
+	default:
+		println("other")
+	}
+}
+
+type myint int
+func (myint) foo() {
+}
+
+func main() {
+	f[interface{}](nil)
+	f[interface{}](6)
+	f[interface{foo()}](nil)
+	f[interface{foo()}](7)
+	f[interface{foo()}](myint(8))
+}
diff --git a/test/typeparam/typeswitch6.out b/test/typeparam/typeswitch6.out
new file mode 100644
index 0000000000000000000000000000000000000000..441add5ec5bed8e4e8919df3602fc16ba9a3f87a
--- /dev/null
+++ b/test/typeparam/typeswitch6.out
@@ -0,0 +1,5 @@
+other
+T
+other
+int
+T
diff --git a/test/typeparam/typeswitch7.go b/test/typeparam/typeswitch7.go
new file mode 100644
index 0000000000000000000000000000000000000000..f2e1279fb41c5c622b84c6da7a0ca20f5ee11ad9
--- /dev/null
+++ b/test/typeparam/typeswitch7.go
@@ -0,0 +1,37 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](i interface{foo()}) {
+	switch i.(type) {
+	case interface{bar() T}:
+		println("barT")
+	case myint:
+		println("myint")
+	case myfloat:
+		println("myfloat")
+	default:
+		println("other")
+	}
+}
+
+type myint int
+func (myint) foo() {
+}
+func (x myint) bar() int {
+	return int(x)
+}
+
+type myfloat float64
+func (myfloat) foo() {
+}
+
+func main() {
+	f[int](nil)
+	f[int](myint(6))
+	f[int](myfloat(7))
+}
diff --git a/test/typeparam/typeswitch7.out b/test/typeparam/typeswitch7.out
new file mode 100644
index 0000000000000000000000000000000000000000..d7fcad4fee14f8788902cc35bdaa2aa3af80ff6e
--- /dev/null
+++ b/test/typeparam/typeswitch7.out
@@ -0,0 +1,3 @@
+other
+barT
+myfloat
diff --git a/test/typeparam/valimp.dir/a.go b/test/typeparam/valimp.dir/a.go
new file mode 100644
index 0000000000000000000000000000000000000000..2ed0063cfd6473855a71a27e3327130ae6c553a2
--- /dev/null
+++ b/test/typeparam/valimp.dir/a.go
@@ -0,0 +1,32 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Value[T any] struct {
+	val T
+}
+
+// The noinline directive should survive across import, and prevent instantiations
+// of these functions from being inlined.
+
+//go:noinline
+func Get[T any](v *Value[T]) T {
+	return v.val
+}
+
+//go:noinline
+func Set[T any](v *Value[T], val T) {
+	v.val = val
+}
+
+//go:noinline
+func (v *Value[T]) Set(val T) {
+	v.val = val
+}
+
+//go:noinline
+func (v *Value[T]) Get() T {
+	return v.val
+}
diff --git a/test/typeparam/valimp.dir/main.go b/test/typeparam/valimp.dir/main.go
new file mode 100644
index 0000000000000000000000000000000000000000..606ff2273af8333521a5947fe262497110181dc1
--- /dev/null
+++ b/test/typeparam/valimp.dir/main.go
@@ -0,0 +1,55 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	var v1 a.Value[int]
+
+	a.Set(&v1, 1)
+	if got, want := a.Get(&v1), 1; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+	v1.Set(2)
+	if got, want := v1.Get(), 2; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+	v1p := new(a.Value[int])
+	a.Set(v1p, 3)
+	if got, want := a.Get(v1p), 3; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+
+	v1p.Set(4)
+	if got, want := v1p.Get(), 4; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+
+	var v2 a.Value[string]
+	a.Set(&v2, "a")
+	if got, want := a.Get(&v2), "a"; got != want {
+		panic(fmt.Sprintf("Get() == %q, want %q", got, want))
+	}
+
+	v2.Set("b")
+	if got, want := a.Get(&v2), "b"; got != want {
+		panic(fmt.Sprintf("Get() == %q, want %q", got, want))
+	}
+
+	v2p := new(a.Value[string])
+	a.Set(v2p, "c")
+	if got, want := a.Get(v2p), "c"; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+
+	v2p.Set("d")
+	if got, want := v2p.Get(), "d"; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/valimp.go b/test/typeparam/valimp.go
new file mode 100644
index 0000000000000000000000000000000000000000..76930e5e4f694938e8456a8875300e2529e2ee08
--- /dev/null
+++ b/test/typeparam/valimp.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored
diff --git a/test/typeparam/value.go b/test/typeparam/value.go
index 5dd7449d9c76f9ee563d277255bc16fbfbb1cfd5..6c6dabcf7ca8725c5171730a7afe8919289c0ed8 100644
--- a/test/typeparam/value.go
+++ b/test/typeparam/value.go
@@ -12,7 +12,7 @@ type value[T any] struct {
 	val T
 }
 
-func get[T2 any](v *value[T2]) T2 {
+func get[T any](v *value[T]) T {
 	return v.val
 }
 
@@ -20,11 +20,11 @@ func set[T any](v *value[T], val T) {
 	v.val = val
 }
 
-func (v *value[T2]) set(val T2) {
+func (v *value[T]) set(val T) {
 	v.val = val
 }
 
-func (v *value[T2]) get() T2 {
+func (v *value[T]) get() T {
 	return v.val
 }
 
diff --git a/test/uintptrescapes2.go b/test/uintptrescapes2.go
index 3ff1d940425863caae41c03e59a1a57d379e97e0..656286c0ff2bd72e7580bd7592a533d4a346d1df 100644
--- a/test/uintptrescapes2.go
+++ b/test/uintptrescapes2.go
@@ -30,7 +30,7 @@ type T struct{}
 func (T) M1(a uintptr) {} // ERROR "escaping uintptr"
 
 //go:uintptrescapes
-func (T) M2(a ...uintptr) {} // ERROR "escaping ...uintptr" "leaking param: a"
+func (T) M2(a ...uintptr) {} // ERROR "escaping ...uintptr"
 
 func TestF1() {
 	var t int                        // ERROR "moved to heap"
diff --git a/test/writebarrier.go b/test/writebarrier.go
index dbf0b6dde28662d0d6670037744c6611866e31a1..1b30fa509e5503275904c53fb7d559296ab85259 100644
--- a/test/writebarrier.go
+++ b/test/writebarrier.go
@@ -289,3 +289,17 @@ func f27(p *int) []interface{} {
 		p,           // ERROR "write barrier"
 	}
 }
+
+var g28 [256]uint64
+
+func f28() []interface{} {
+	return []interface{}{
+		false,      // no write barrier
+		true,       // no write barrier
+		0,          // no write barrier
+		1,          // no write barrier
+		uint8(127), // no write barrier
+		int8(-4),   // no write barrier
+		&g28[5],    // no write barrier
+	}
+}