[PATCH] D70093: [InstCombine] Avoid moving ops that do restrict undef across shuffles.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


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Comment at: llvm/test/Transforms/InstCombine/vec_shuffle.ll:1010-1016
-; CHECK-NEXT:    [[AND:%.*]] = shufflevector <4 x i16> [[ADD:%.*]], <4 x i16> undef, <4 x i32> <i32 undef, i32 undef, i32 1, i32 1>
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <4 x i16> [[ADD:%.*]], <4 x i16> undef, <4 x i32> <i32 undef, i32 undef, i32 1, i32 1>
+; CHECK-NEXT:    [[AND:%.*]] = and <4 x i16> [[SHUFFLE]], <i16 0, i16 0, i16 -1, i16 -1>
 ; CHECK-NEXT:    ret <4 x i16> [[AND]]
 ;
 entry:
   %shuffle = shufflevector <4 x i16> %add, <4 x i16> undef, <4 x i32> <i32 undef, i32 undef, i32 1, i32 1>
   %and = and <4 x i16> %shuffle, <i16 0, i16 0, i16 -1, i16 -1>
   ret <4 x i16> %and
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Hmm yes, i'd agree this is a miscompile..


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  https://reviews.llvm.org/D70093/new/

https://reviews.llvm.org/D70093