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| author | Nikita Popov <npopov@redhat.com> | 2024-05-21 14:57:19 +0200 |
|---|---|---|
| committer | Nikita Popov <npopov@redhat.com> | 2024-05-21 15:00:01 +0200 |
| commit | 263224e4481b0850539a93a272184aac4abe86d4 (patch) | |
| tree | a281ac7b21e1a24f6a3bf32b5c52b3dfcc3c727b | |
| parent | f78b1a40864470f7eb30dfda44a6ea8e845346a5 (diff) | |
| download | llvm-263224e4481b0850539a93a272184aac4abe86d4.zip llvm-263224e4481b0850539a93a272184aac4abe86d4.tar.gz llvm-263224e4481b0850539a93a272184aac4abe86d4.tar.bz2 | |
[InstCombine] Require poison operand in canEvaluateShuffled transform
This transform works on single-source shuffles, which require that
the second operand is poison, not undef. Otherwise we may convert
undef to poison.
Fixes https://github.com/llvm/llvm-project/issues/92887.
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp | 2 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/vec_shuffle.ll | 3 |
2 files changed, 2 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp index 99f1f8e..745ccbf 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp @@ -2901,7 +2901,7 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) { if (Instruction *I = foldIdentityPaddedShuffles(SVI)) return I; - if (match(RHS, m_Undef()) && canEvaluateShuffled(LHS, Mask)) { + if (match(RHS, m_Poison()) && canEvaluateShuffled(LHS, Mask)) { Value *V = evaluateInDifferentElementOrder(LHS, Mask, Builder); return replaceInstUsesWith(SVI, V); } diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle.ll b/llvm/test/Transforms/InstCombine/vec_shuffle.ll index 839279d..d36ada7 100644 --- a/llvm/test/Transforms/InstCombine/vec_shuffle.ll +++ b/llvm/test/Transforms/InstCombine/vec_shuffle.ll @@ -2331,10 +2331,9 @@ define <4 x i16> @blend_elements_from_load(ptr align 8 %_0) { ret <4 x i16> %rv } -; FIXME: This is a miscompile. define i16 @pr92887(<2 x i16> %v) { ; CHECK-LABEL: @pr92887( -; CHECK-NEXT: ret i16 poison +; CHECK-NEXT: ret i16 undef ; %v0 = extractelement <2 x i16> %v, i64 0 %v0lo = and i16 %v0, 1 |