tree 22c8ee8dc6cc777bdb7a991485b7a1d1fa1ef2d0
parent 3a2363c7974ab12c29a200686fcf57ca29936c07
author Bjorn Pettersson <bjorn.a.pettersson@ericsson.com> 1571384513 +0000
committer Bjorn Pettersson <bjorn.a.pettersson@ericsson.com> 1571384513 +0000

[InstCombine] Pre-commit of test case showing miscompile bug in canEvaluateShuffled

Adding the reproducer from  https://bugs.llvm.org/show_bug.cgi?id=43689,
showing that instcombine is doing a bad transform. It transforms

  %0 = insertelement <2 x i16> undef, i16 %a, i32 0
  %1 = srem <2 x i16> %0, <i16 2, i16 1>
  %2 = shufflevector <2 x i16> %1, <2 x i16> undef, <2 x i32> <i32 undef, i32 0>

into

   %1 = insertelement <2 x i16> undef, i16 %a, i32 1
   %2 = srem <2 x i16> %1, <i16 undef, i16 2>

The undef denominator makes the whole srem undefined.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375207 91177308-0d34-0410-b5e6-96231b3b80d8