2 Commits

Author	SHA1	Message	Date
Bjorn Pettersson	6456252dbf	[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 llvm-svn: 375208	2019-10-18 07:42:02 +00:00
Bjorn Pettersson	459134064d	[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. llvm-svn: 375207	2019-10-18 07:41:53 +00:00