diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp index 19a16197272fe..3b250d7d9ad1f 100644 --- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp +++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp @@ -20822,7 +20822,8 @@ SDValue RISCVTargetLowering::PerformDAGCombine(SDNode *N, // Undo this and sink the fneg so we match more fmsub/fnmadd patterns. if (sd_match(N, m_FMul(m_Value(X), m_OneUse(m_FNeg(m_Value(Y)))))) return DAG.getNode(ISD::FNEG, DL, VT, - DAG.getNode(ISD::FMUL, DL, VT, X, Y)); + DAG.getNode(ISD::FMUL, DL, VT, X, Y, N->getFlags()), + N->getFlags()); // fmul X, (copysign 1.0, Y) -> fsgnjx X, Y SDValue N0 = N->getOperand(0); diff --git a/llvm/test/CodeGen/RISCV/fma-combine.ll b/llvm/test/CodeGen/RISCV/fma-combine.ll new file mode 100644 index 0000000000000..9291ce42d765c --- /dev/null +++ b/llvm/test/CodeGen/RISCV/fma-combine.ll @@ -0,0 +1,56 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6 +; RUN: llc -mtriple=riscv64 -mattr=+d,+m < %s | FileCheck %s + +; What the original PR (#169460) tried to solve can only be revealed when a specific +; set of FMA DAG combiner patterns were skipped due to hitting some recursion limits. +; And this test is written in a way to hit that limit. + +define double @fnmadd_non_trivial(ptr %p0, ptr %p1, ptr %dst, double %mul425) { +; CHECK-LABEL: fnmadd_non_trivial: +; CHECK: # %bb.0: +; CHECK-NEXT: li a3, -2047 +; CHECK-NEXT: slli a3, a3, 51 +; CHECK-NEXT: fmv.d.x fa5, a3 +; CHECK-NEXT: lui a3, 2049 +; CHECK-NEXT: slli a3, a3, 39 +; CHECK-NEXT: fmv.d.x fa4, a3 +; CHECK-NEXT: lui a3, 8201 +; CHECK-NEXT: slli a3, a3, 37 +; CHECK-NEXT: fmv.d.x fa3, a3 +; CHECK-NEXT: li a3, 1023 +; CHECK-NEXT: fmv.d.x fa2, zero +; CHECK-NEXT: slli a3, a3, 52 +; CHECK-NEXT: fsub.d fa1, fa2, fa0 +; CHECK-NEXT: fmadd.d fa1, fa1, fa3, fa4 +; CHECK-NEXT: fmadd.d fa4, fa0, fa3, fa4 +; CHECK-NEXT: fmv.d.x fa3, a3 +; CHECK-NEXT: lui a3, %hi(.LCPI0_0) +; CHECK-NEXT: ld a3, %lo(.LCPI0_0)(a3) +; CHECK-NEXT: fmul.d fa5, fa0, fa5 +; CHECK-NEXT: fnmadd.d fa4, fa4, fa2, fa3 +; CHECK-NEXT: fnmadd.d fa3, fa1, fa2, fa3 +; CHECK-NEXT: sd a3, 0(a2) +; CHECK-NEXT: fsd fa5, 0(a0) +; CHECK-NEXT: fnmadd.d fa5, fa4, fa2, fa0 +; CHECK-NEXT: fnmadd.d fa0, fa0, fa2, fa3 +; CHECK-NEXT: fsd fa5, 0(a1) +; CHECK-NEXT: ret + store double 0x3FEE666666666666, ptr %dst, align 8 + %mul413 = fmul double %mul425, -3.000000e+00 + store double %mul413, ptr %p0, align 8 + %mul428 = fmul contract double %mul425, 4.500000e+00 + %add429 = fadd nsz contract double %mul428, 3.000000e+00 + %mul430 = fmul contract double %add429, 0.000000e+00 + %sub432 = fadd nsz contract double %mul430, 1.000000e+00 + %mul433 = fmul contract double %sub432, 0.000000e+00 + %1 = fsub nsz contract double %mul433, %mul425 + store double %1, ptr %p1, align 8 + %mul441 = fmul contract double %mul425, 0.000000e+00 + %add443 = fsub double 0.000000e+00, %mul425 + %mul446 = fmul contract double %add443, 4.500000e+00 + %add447 = fadd nsz contract double %mul446, 3.000000e+00 + %mul448 = fmul contract double %add447, 0.000000e+00 + %sub450 = fadd nsz contract double %mul448, 1.000000e+00 + %2 = fsub nsz contract double %sub450, %mul441 + ret double %2 +}