commit c395575313286953895f32bddfe2ef35cd2fb51a
author Bjorn Pettersson <bjorn.a.pettersson@ericsson.com> Fri Oct 18 07:42:02 2019 +0000
committer Bjorn Pettersson <bjorn.a.pettersson@ericsson.com> Fri Oct 18 07:42:02 2019 +0000
tree 1106badf0f11a9602a95bb6bd2422f974dd30995
parent acb3705a54fe21a48077774f026640280715b25c

[InstCombine] Fix miscompile bug in canEvaluateShuffled

Summary:
Add restrictions in canEvaluateShuffled to prevent that we for example
transform

  %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>

as having an undef denominator makes the srem undefined (for all
vector elements).

Fixes: https://bugs.llvm.org/show_bug.cgi?id=43689

Reviewers: spatel, lebedev.ri

Reviewed By: spatel, lebedev.ri

Subscribers: lebedev.ri, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69038

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375208 91177308-0d34-0410-b5e6-96231b3b80d8