diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp | 8 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/insert-extract-shuffle.ll | 27 |
2 files changed, 35 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp index 6c3aa3ad6c9..732a786ceb7 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp @@ -413,6 +413,14 @@ static void replaceExtractElements(InsertElementInst *InsElt, if (InsertionBlock != InsElt->getParent()) return; + // TODO: This restriction matches the check in visitInsertElementInst() and + // prevents an infinite loop caused by not turning the extract/insert pair + // into a shuffle. We really should not need either check, but we're lacking + // folds for shufflevectors because we're afraid to generate shuffle masks + // that the backend can't handle. + if (InsElt->hasOneUse() && isa<InsertElementInst>(InsElt->user_back())) + return; + auto *WideVec = new ShuffleVectorInst(ExtVecOp, UndefValue::get(ExtVecType), ConstantVector::get(ExtendMask)); diff --git a/llvm/test/Transforms/InstCombine/insert-extract-shuffle.ll b/llvm/test/Transforms/InstCombine/insert-extract-shuffle.ll index 163c3368699..4507deb7f02 100644 --- a/llvm/test/Transforms/InstCombine/insert-extract-shuffle.ll +++ b/llvm/test/Transforms/InstCombine/insert-extract-shuffle.ll @@ -237,3 +237,30 @@ end: ret double %mu } +; https://llvm.org/bugs/show_bug.cgi?id=30923 +; Delete the widening shuffle if we're not going to reduce the extract/insert to a shuffle. + +define <4 x float> @PR30923(<2 x float> %x) { +; CHECK-LABEL: @PR30923( +; CHECK-NEXT: bb1: +; CHECK-NEXT: [[EXT1:%.*]] = extractelement <2 x float> %x, i32 1 +; CHECK-NEXT: store float [[EXT1]], float* undef, align 4 +; CHECK-NEXT: br label %bb2 +; CHECK: bb2: +; CHECK-NEXT: [[EXT2:%.*]] = extractelement <2 x float> %x, i32 0 +; CHECK-NEXT: [[INS1:%.*]] = insertelement <4 x float> <float 0.000000e+00, float 0.000000e+00, float undef, float undef>, float [[EXT2]], i32 2 +; CHECK-NEXT: [[INS2:%.*]] = insertelement <4 x float> [[INS1]], float [[EXT1]], i32 3 +; CHECK-NEXT: ret <4 x float> [[INS2]] +; +bb1: + %ext1 = extractelement <2 x float> %x, i32 1 + store float %ext1, float* undef, align 4 + br label %bb2 + +bb2: + %widen = shufflevector <2 x float> %x, <2 x float> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef> + %ext2 = extractelement <4 x float> %widen, i32 0 + %ins1 = insertelement <4 x float> <float 0.0, float 0.0, float undef, float undef>, float %ext2, i32 2 + %ins2 = insertelement <4 x float> %ins1, float %ext1, i32 3 + ret <4 x float> %ins2 +} |
