Index: lib/Transforms/InstCombine/InstCombineCalls.cpp =================================================================== --- lib/Transforms/InstCombine/InstCombineCalls.cpp +++ lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -2044,8 +2044,21 @@ return replaceInstUsesWith(*II, V); break; } - case Intrinsic::fma: case Intrinsic::fmuladd: { + // Canonicalize fast fmuladd to the separate fmul + fadd. + if (II->hasUnsafeAlgebra()) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->setFastMathFlags(II->getFastMathFlags()); + Value *Mul = Builder->CreateFMul(II->getArgOperand(0), + II->getArgOperand(1)); + Value *Add = Builder->CreateFAdd(Mul, II->getArgOperand(2)); + Add->takeName(II); + return replaceInstUsesWith(*II, Add); + } + + LLVM_FALLTHROUGH; + } + case Intrinsic::fma: { Value *Src0 = II->getArgOperand(0); Value *Src1 = II->getArgOperand(1); Index: test/Transforms/InstCombine/fma.ll =================================================================== --- test/Transforms/InstCombine/fma.ll +++ test/Transforms/InstCombine/fma.ll @@ -78,7 +78,8 @@ } ; CHECK-LABEL: @fmuladd_fneg_x_fneg_y_fast( -; CHECK: %fmuladd = call fast float @llvm.fmuladd.f32(float %x, float %y, float %z) +; CHECK-NEXT: %1 = fmul fast float %x, %y +; CHECK-NEXT: %fmuladd = fadd fast float %1, %z define float @fmuladd_fneg_x_fneg_y_fast(float %x, float %y, float %z) { %x.fneg = fsub float -0.0, %x %y.fneg = fsub float -0.0, %y @@ -122,7 +123,8 @@ } ; CHECK-LABEL: @fmuladd_fabs_x_fabs_x_fast( -; CHECK: %fmuladd = call fast float @llvm.fmuladd.f32(float %x, float %x, float %z) +; CHECK-NEXT: %1 = fmul fast float %x, %x +; CHECK-NEXT: %fmuladd = fadd fast float %1, %z define float @fmuladd_fabs_x_fabs_x_fast(float %x, float %z) { %x.fabs = call float @llvm.fabs.f32(float %x) %fmuladd = call fast float @llvm.fmuladd.f32(float %x.fabs, float %x.fabs, float %z) @@ -144,7 +146,8 @@ } ; CHECK-LABEL: @fmuladd_k_y_z_fast( -; CHECK: %fmuladd = call fast float @llvm.fmuladd.f32(float %y, float 4.000000e+00, float %z) +; CHECK: %1 = fmul fast float %y, 4.000000e+00 +; CHECK-NEXT: %fmuladd = fadd fast float %1, %z define float @fmuladd_k_y_z_fast(float %y, float %z) { %fmuladd = call fast float @llvm.fmuladd.f32(float 4.0, float %y, float %z) ret float %fmuladd