diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp index abc2297f346..6889cd9189c 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp @@ -1498,6 +1498,11 @@ static Instruction *foldIdentityExtractShuffle(ShuffleVectorInst &Shuf) { if (!match(Op0, m_ShuffleVector(m_Value(X), m_Value(Y), m_Constant(Mask)))) return nullptr; + // Be conservative with shuffle transforms. If we can't kill the 1st shuffle, + // then combining may result in worse codegen. + if (!Op0->hasOneUse()) + return nullptr; + // We are extracting a subvector from a shuffle. Remove excess elements from // the 1st shuffle mask to eliminate the extract. // |
