diff options
| author | Nikita Popov <npopov@redhat.com> | 2024-05-21 15:18:17 +0200 |
|---|---|---|
| committer | Nikita Popov <npopov@redhat.com> | 2024-05-21 15:21:31 +0200 |
| commit | ecd269e8305330c185bbedbd5a59e887122333ba (patch) | |
| tree | b25017ca2a1ebd5573abc387c61bedf1cecdda7b | |
| parent | 557a0be3af798cf55b1ef54fc98a84fa5a4ade42 (diff) | |
[InstCombine] Check for poison instead of undef in splat shuffle fold
We can't canonicalize these to a splat shuffle, as doing so would
convert undef -> poison.
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp | 10 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/vec_shuffle.ll | 8 |
2 files changed, 7 insertions, 11 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp index 745ccbfe9dc7..ac062fe55ce4 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp @@ -2214,19 +2214,19 @@ static Instruction *canonicalizeInsertSplat(ShuffleVectorInst &Shuf, uint64_t IndexC; // Match a shuffle that is a splat to a non-zero element. - if (!match(Op0, m_OneUse(m_InsertElt(m_Undef(), m_Value(X), + if (!match(Op0, m_OneUse(m_InsertElt(m_Poison(), m_Value(X), m_ConstantInt(IndexC)))) || - !match(Op1, m_Undef()) || match(Mask, m_ZeroMask()) || IndexC == 0) + !match(Op1, m_Poison()) || match(Mask, m_ZeroMask()) || IndexC == 0) return nullptr; // Insert into element 0 of a poison vector. PoisonValue *PoisonVec = PoisonValue::get(Shuf.getType()); Value *NewIns = Builder.CreateInsertElement(PoisonVec, X, (uint64_t)0); - // Splat from element 0. Any mask element that is undefined remains undefined. + // Splat from element 0. Any mask element that is poison remains poison. // For example: - // shuf (inselt undef, X, 2), _, <2,2,undef> - // --> shuf (inselt undef, X, 0), poison, <0,0,undef> + // shuf (inselt poison, X, 2), _, <2,2,undef> + // --> shuf (inselt poison, X, 0), poison, <0,0,undef> unsigned NumMaskElts = cast<FixedVectorType>(Shuf.getType())->getNumElements(); SmallVector<int, 16> NewMask(NumMaskElts, 0); diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle.ll b/llvm/test/Transforms/InstCombine/vec_shuffle.ll index 7428f7a93d64..7217e1ac4aa9 100644 --- a/llvm/test/Transforms/InstCombine/vec_shuffle.ll +++ b/llvm/test/Transforms/InstCombine/vec_shuffle.ll @@ -2346,11 +2346,9 @@ define i16 @pr92887(<2 x i16> %v) { ret i16 %extract } -; FIXME: This is a miscompile. define <2 x i32> @not_splat_shuffle1(i32 %x) { ; CHECK-LABEL: @not_splat_shuffle1( -; CHECK-NEXT: [[TMP1:%.*]] = insertelement <2 x i32> poison, i32 [[X:%.*]], i64 0 -; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <2 x i32> [[TMP1]], <2 x i32> poison, <2 x i32> zeroinitializer +; CHECK-NEXT: [[SHUF:%.*]] = insertelement <2 x i32> <i32 poison, i32 undef>, i32 [[X:%.*]], i64 0 ; CHECK-NEXT: ret <2 x i32> [[SHUF]] ; %vec = insertelement <2 x i32> undef, i32 %x, i32 1 @@ -2358,11 +2356,9 @@ define <2 x i32> @not_splat_shuffle1(i32 %x) { ret <2 x i32> %shuf } -; FIXME: This is a miscompile. define <2 x i32> @not_splat_shuffle2(i32 %x) { ; CHECK-LABEL: @not_splat_shuffle2( -; CHECK-NEXT: [[TMP1:%.*]] = insertelement <2 x i32> poison, i32 [[X:%.*]], i64 0 -; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <2 x i32> [[TMP1]], <2 x i32> poison, <2 x i32> zeroinitializer +; CHECK-NEXT: [[SHUF:%.*]] = insertelement <2 x i32> <i32 poison, i32 undef>, i32 [[X:%.*]], i64 0 ; CHECK-NEXT: ret <2 x i32> [[SHUF]] ; %vec = insertelement <2 x i32> poison, i32 %x, i32 1 |