Index: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp =================================================================== --- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -2379,6 +2379,14 @@ return FAdd; } + // fma x, y, 0 -> fmul x, y + if (II->getFastMathFlags().noSignedZeros() && + match(II->getArgOperand(2), m_Zero())) { + auto *FMul = BinaryOperator::CreateFMul(Src0, Src1); + FMul->copyFastMathFlags(II); + return FMul; + } + break; } case Intrinsic::copysign: { Index: llvm/test/Transforms/InstCombine/fma.ll =================================================================== --- llvm/test/Transforms/InstCombine/fma.ll +++ llvm/test/Transforms/InstCombine/fma.ll @@ -372,7 +372,7 @@ define float @fma_x_y_0_nsz(float %x, float %y) { ; CHECK-LABEL: @fma_x_y_0_nsz( -; CHECK-NEXT: [[FMA:%.*]] = call nsz float @llvm.fma.f32(float [[X:%.*]], float [[Y:%.*]], float 0.000000e+00) +; CHECK-NEXT: [[FMA:%.*]] = fmul nsz float [[X:%.*]], [[Y:%.*]] ; CHECK-NEXT: ret float [[FMA]] ; %fma = call nsz float @llvm.fma.f32(float %x, float %y, float 0.0) @@ -390,7 +390,7 @@ define <8 x half> @fma_x_y_0_nsz_v(<8 x half> %x, <8 x half> %y) { ; CHECK-LABEL: @fma_x_y_0_nsz_v( -; CHECK-NEXT: [[FMA:%.*]] = call nsz <8 x half> @llvm.fma.v8f16(<8 x half> [[X:%.*]], <8 x half> [[Y:%.*]], <8 x half> zeroinitializer) +; CHECK-NEXT: [[FMA:%.*]] = fmul nsz <8 x half> [[X:%.*]], [[Y:%.*]] ; CHECK-NEXT: ret <8 x half> [[FMA]] ; %fma = call nsz <8 x half> @llvm.fma.v8f16(<8 x half> %x, <8 x half> %y, <8 x half> zeroinitializer)