Author: Qiu Chaofan Date: 2020-09-17T13:37:11+02:00 New Revision: b78e5de029c26c309f541ab883fa5d6d953b073d
URL: https://github.com/llvm/llvm-project/commit/b78e5de029c26c309f541ab883fa5d6d953b073d DIFF: https://github.com/llvm/llvm-project/commit/b78e5de029c26c309f541ab883fa5d6d953b073d.diff LOG: [SelectionDAG] Check any use of negation result before removal 2508ef01 fixed a bug about constant removal in negation. But after sanitizing check I found there's still some issue about it so it's reverted. Temporary nodes will be removed if useless in negation. Before the removal, they'd be checked if any other nodes used it. So the removal was moved after getNode. However in rare cases the node to be removed is the same as result of getNode. We missed that and will be fixed by this patch. Reviewed By: steven.zhang Differential Revision: https://reviews.llvm.org/D87614 (cherry picked from commit a2fb5446be960ad164060b3c05fc268f7f72d67a) Added: llvm/test/CodeGen/X86/pr47517.ll Modified: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp Removed: ################################################################################ diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp index 819e608c6896..64af293caf9e 100644 --- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -5751,8 +5751,10 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, // If we already have the use of the negated floating constant, it is free // to negate it even it has multiple uses. - if (!Op.hasOneUse() && CFP.use_empty()) + if (!Op.hasOneUse() && CFP.use_empty()) { + RemoveDeadNode(CFP); break; + } Cost = NegatibleCost::Neutral; return CFP; } @@ -5810,7 +5812,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, if (NegX && (CostX <= CostY)) { Cost = CostX; SDValue N = DAG.getNode(ISD::FSUB, DL, VT, NegX, Y, Flags); - RemoveDeadNode(NegY); + if (NegY != N) + RemoveDeadNode(NegY); return N; } @@ -5818,7 +5821,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, if (NegY) { Cost = CostY; SDValue N = DAG.getNode(ISD::FSUB, DL, VT, NegY, X, Flags); - RemoveDeadNode(NegX); + if (NegX != N) + RemoveDeadNode(NegX); return N; } break; @@ -5857,7 +5861,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, if (NegX && (CostX <= CostY)) { Cost = CostX; SDValue N = DAG.getNode(Opcode, DL, VT, NegX, Y, Flags); - RemoveDeadNode(NegY); + if (NegY != N) + RemoveDeadNode(NegY); return N; } @@ -5870,7 +5875,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, if (NegY) { Cost = CostY; SDValue N = DAG.getNode(Opcode, DL, VT, X, NegY, Flags); - RemoveDeadNode(NegX); + if (NegX != N) + RemoveDeadNode(NegX); return N; } break; @@ -5901,7 +5907,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, if (NegX && (CostX <= CostY)) { Cost = std::min(CostX, CostZ); SDValue N = DAG.getNode(Opcode, DL, VT, NegX, Y, NegZ, Flags); - RemoveDeadNode(NegY); + if (NegY != N) + RemoveDeadNode(NegY); return N; } @@ -5909,7 +5916,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG, if (NegY) { Cost = std::min(CostY, CostZ); SDValue N = DAG.getNode(Opcode, DL, VT, X, NegY, NegZ, Flags); - RemoveDeadNode(NegX); + if (NegX != N) + RemoveDeadNode(NegX); return N; } break; diff --git a/llvm/test/CodeGen/X86/pr47517.ll b/llvm/test/CodeGen/X86/pr47517.ll new file mode 100644 index 000000000000..5672fbc69a41 --- /dev/null +++ b/llvm/test/CodeGen/X86/pr47517.ll @@ -0,0 +1,28 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py +; RUN: llc -mtriple x86_64 < %s | FileCheck %s + +; To ensure unused floating point constant is correctly removed +define float @test(float %src, float* %p) { +; CHECK-LABEL: test: +; CHECK: # %bb.0: # %entry +; CHECK-NEXT: movq $0, (%rdi) +; CHECK-NEXT: xorps %xmm0, %xmm0 +; CHECK-NEXT: retq +entry: + %a0 = getelementptr inbounds float, float* %p, i32 0 + %a1 = getelementptr inbounds float, float* %p, i32 1 + store float 0.000000e+00, float* %a0 + store float 0.000000e+00, float* %a1 + %zero = load float, float* %a0 + %fmul1 = fmul fast float %zero, %src + %fadd1 = fadd fast float %fmul1, %zero + %fmul2 = fmul fast float %fadd1, 2.000000e+00 + %fmul3 = fmul fast float %fmul2, %fmul2 + %fmul4 = fmul fast float %fmul2, 2.000000e+00 + %fadd2 = fadd fast float %fmul4, -3.000000e+00 + %fmul5 = fmul fast float %fadd2, %fmul2 + %fadd3 = fadd fast float %fmul2, %src + %fadd4 = fadd fast float %fadd3, %fmul5 + %fmul6 = fmul fast float %fmul3, %fadd4 + ret float %fmul6 +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
