diff options
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 9 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/fold-buildvector-bug.ll | 40 |
2 files changed, 46 insertions, 3 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 439ddb292e4..e9cba08d333 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1587,6 +1587,11 @@ static bool isNullConstant(SDValue V) { return Const != nullptr && Const->isNullValue(); } +static bool isNullFPConstant(SDValue V) { + ConstantFPSDNode *Const = dyn_cast<ConstantFPSDNode>(V); + return Const != nullptr && Const->isZero() && !Const->isNegative(); +} + static bool isAllOnesConstant(SDValue V) { ConstantSDNode *Const = dyn_cast<ConstantSDNode>(V); return Const != nullptr && Const->isAllOnesValue(); @@ -11912,9 +11917,7 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) { if (Op.getOpcode() == ISD::UNDEF) continue; // See if we can combine this build_vector into a blend with a zero vector. - if (!VecIn2.getNode() && (isNullConstant(Op) || - (Op.getOpcode() == ISD::ConstantFP && - cast<ConstantFPSDNode>(Op.getNode())->getValueAPF().isZero()))) { + if (!VecIn2.getNode() && (isNullConstant(Op) || isNullFPConstant(Op))) { UsesZeroVector = true; continue; } diff --git a/llvm/test/CodeGen/X86/fold-buildvector-bug.ll b/llvm/test/CodeGen/X86/fold-buildvector-bug.ll new file mode 100644 index 00000000000..76deab7edae --- /dev/null +++ b/llvm/test/CodeGen/X86/fold-buildvector-bug.ll @@ -0,0 +1,40 @@ +; RUN: llc -mtriple=x86_64-unknown-unknown -mattr=+sse4.1 < %s | FileCheck %s + +; Verify that the DAGCombiner doesn't wrongly fold a build_vector into a +; blend with a zero vector if the build_vector contains negative zero. +; +; TODO: the codegen for function 'test_negative_zero_1' is sub-optimal. +; Ideally, we should generate a single shuffle blend operation. + +define <4 x float> @test_negative_zero_1(<4 x float> %A) { +; CHECK-LABEL: test_negative_zero_1: +; CHECK: # BB#0: # %entry +; CHECK-NEXT: movapd %xmm0, %xmm1 +; CHECK-NEXT: shufpd {{.*#+}} xmm1 = xmm1[1,0] +; CHECK-NEXT: xorps %xmm2, %xmm2 +; CHECK-NEXT: blendps {{.*#+}} xmm2 = xmm1[0],xmm2[1,2,3] +; CHECK-NEXT: movss {{.*#+}} xmm1 = mem[0],zero,zero,zero +; CHECK-NEXT: unpcklps {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1] +; CHECK-NEXT: unpcklpd {{.*#+}} xmm0 = xmm0[0],xmm2[0] +; CHECK-NEXT: retq +entry: + %0 = extractelement <4 x float> %A, i32 0 + %1 = insertelement <4 x float> undef, float %0, i32 0 + %2 = insertelement <4 x float> %1, float -0.0, i32 1 + %3 = extractelement <4 x float> %A, i32 2 + %4 = insertelement <4 x float> %2, float %3, i32 2 + %5 = insertelement <4 x float> %4, float 0.0, i32 3 + ret <4 x float> %5 +} + +define <2 x double> @test_negative_zero_2(<2 x double> %A) { +; CHECK-LABEL: test_negative_zero_2: +; CHECK: # BB#0: # %entry +; CHECK-NEXT: movhpd {{.*}}(%rip), %xmm0 +; CHECK-NEXT: retq +entry: + %0 = extractelement <2 x double> %A, i32 0 + %1 = insertelement <2 x double> undef, double %0, i32 0 + %2 = insertelement <2 x double> %1, double -0.0, i32 1 + ret <2 x double> %2 +} |
