Merging r197449:

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r197449 | arnolds | 2013-12-16 17:11:01 -0800 (Mon, 16 Dec 2013) | 7 lines

LoopVectorizer: Don't if-convert constant expressions that can trap

A phi node operand or an instruction operand could be a constant expression that
can trap (division). Check that we don't vectorize such cases.

PR16729
radar://15653590
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@197453 91177308-0d34-0410-b5e6-96231b3b80d8