Index: lib/Target/X86/X86ISelLowering.cpp =================================================================== --- lib/Target/X86/X86ISelLowering.cpp +++ lib/Target/X86/X86ISelLowering.cpp @@ -31735,6 +31735,33 @@ return V; } +static SDValue combineFAndFNotToFAndn(SDNode *N, SelectionDAG &DAG, + const X86Subtarget &Subtarget) { + SDValue N0 = N->getOperand(0); + SDValue N1 = N->getOperand(1); + EVT VT = N->getValueType(0); + SDLoc DL(N); + + if (!((VT == MVT::f32 && Subtarget.hasSSE1()) || + (VT == MVT::f64 && Subtarget.hasSSE2()))) + return SDValue(); + + auto isAllOnesConstantFP = [](SDValue V) { + auto *C = dyn_cast(V); + return C && C->getConstantFPValue()->isAllOnesValue(); + }; + + // fand (fxor X, -1), Y --> fandn X, Y + if (N0.getOpcode() == X86ISD::FXOR && isAllOnesConstantFP(N0.getOperand(1))) + return DAG.getNode(X86ISD::FANDN, DL, VT, N0.getOperand(0), N1); + + // fand X, (fxor Y, -1) --> fandn Y, X + if (N1.getOpcode() == X86ISD::FXOR && isAllOnesConstantFP(N1.getOperand(1))) + return DAG.getNode(X86ISD::FANDN, DL, VT, N1.getOperand(0), N0); + + return SDValue(); +} + /// Do target-specific dag combines on X86ISD::FAND nodes. static SDValue combineFAnd(SDNode *N, SelectionDAG &DAG, const X86Subtarget &Subtarget) { @@ -31746,6 +31773,9 @@ if (SDValue V = getNullFPConstForNullVal(N->getOperand(1), DAG, Subtarget)) return V; + if (SDValue V = combineFAndFNotToFAndn(N, DAG, Subtarget)) + return V; + return lowerX86FPLogicOp(N, DAG, Subtarget); } Index: test/CodeGen/X86/fp-logic-replace.ll =================================================================== --- test/CodeGen/X86/fp-logic-replace.ll +++ test/CodeGen/X86/fp-logic-replace.ll @@ -29,16 +29,13 @@ define double @FsANDNPSrr(double %x, double %y) { ; SSE-LABEL: FsANDNPSrr: ; SSE: # BB#0: -; SSE-NEXT: movsd {{.*#+}} xmm2 = mem[0],zero -; SSE-NEXT: xorpd %xmm1, %xmm2 -; SSE-NEXT: andpd %xmm2, %xmm0 +; SSE-NEXT: andnps %xmm0, %xmm1 +; SSE-NEXT: movaps %xmm1, %xmm0 ; SSE-NEXT: retq ; ; AVX-LABEL: FsANDNPSrr: ; AVX: # BB#0: -; AVX-NEXT: vmovsd {{.*#+}} xmm2 = mem[0],zero -; AVX-NEXT: vxorpd %xmm2, %xmm1, %xmm1 -; AVX-NEXT: vandpd %xmm1, %xmm0, %xmm0 +; AVX-NEXT: vandnps %xmm0, %xmm1, %xmm0 ; AVX-NEXT: retq ; %bc1 = bitcast double %x to i64