diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -37552,37 +37552,55 @@ if (VT.is512BitVector()) return SDValue(); - // TODO: Add other opcodes eventually lowered into BLEND. - for (SDNode::use_iterator UI = Cond->use_begin(), UE = Cond->use_end(); - UI != UE; ++UI) - if ((UI->getOpcode() != ISD::VSELECT && - UI->getOpcode() != X86ISD::BLENDV) || - UI.getOperandNo() != 0) + auto OnlyUsedAsSelectCond = [](SDValue Cond) { + for (SDNode::use_iterator UI = Cond->use_begin(), UE = Cond->use_end(); + UI != UE; ++UI) + if ((UI->getOpcode() != ISD::VSELECT && + UI->getOpcode() != X86ISD::BLENDV) || + UI.getOperandNo() != 0) + return false; + + return true; + }; + + if (OnlyUsedAsSelectCond(Cond)) { + APInt DemandedMask(APInt::getSignMask(BitWidth)); + KnownBits Known; + TargetLowering::TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(), + !DCI.isBeforeLegalizeOps()); + if (!TLI.SimplifyDemandedBits(Cond, DemandedMask, Known, TLO, 0, true)) return SDValue(); + // If we changed the computation somewhere in the DAG, this change will + // affect all users of Cond. Update all the nodes so that we do not use + // the generic VSELECT anymore. Otherwise, we may perform wrong + // optimizations as we messed with the actual expectation for the vector + // boolean values. + for (SDNode *U : Cond->uses()) { + if (U->getOpcode() == X86ISD::BLENDV) + continue; + + SDValue SB = DAG.getNode(X86ISD::BLENDV, SDLoc(U), U->getValueType(0), + Cond, U->getOperand(1), U->getOperand(2)); + DAG.ReplaceAllUsesOfValueWith(SDValue(U, 0), SB); + DCI.AddToWorklist(U); + } + DCI.CommitTargetLoweringOpt(TLO); + return SDValue(N, 0); + } + + // Otherwise we can still at least try to simplify multiple use bits. APInt DemandedMask(APInt::getSignMask(BitWidth)); + APInt DemandedElts(APInt::getAllOnesValue(VT.getVectorNumElements())); KnownBits Known; TargetLowering::TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(), !DCI.isBeforeLegalizeOps()); - if (!TLI.SimplifyDemandedBits(Cond, DemandedMask, Known, TLO, 0, true)) - return SDValue(); + if (SDValue V = TLI.SimplifyMultipleUseDemandedBits(Cond, DemandedMask, + DemandedElts, DAG, 0)) + return DAG.getNode(X86ISD::BLENDV, SDLoc(N), N->getValueType(0), + V, N->getOperand(1), N->getOperand(2)); - // If we changed the computation somewhere in the DAG, this change will - // affect all users of Cond. Update all the nodes so that we do not use - // the generic VSELECT anymore. Otherwise, we may perform wrong - // optimizations as we messed with the actual expectation for the vector - // boolean values. - for (SDNode *U : Cond->uses()) { - if (U->getOpcode() == X86ISD::BLENDV) - continue; - - SDValue SB = DAG.getNode(X86ISD::BLENDV, SDLoc(U), U->getValueType(0), - Cond, U->getOperand(1), U->getOperand(2)); - DAG.ReplaceAllUsesOfValueWith(SDValue(U, 0), SB); - DCI.AddToWorklist(U); - } - DCI.CommitTargetLoweringOpt(TLO); - return SDValue(N, 0); + return SDValue(); } /// Do target-specific dag combines on SELECT and VSELECT nodes. diff --git a/llvm/test/CodeGen/X86/vselect.ll b/llvm/test/CodeGen/X86/vselect.ll --- a/llvm/test/CodeGen/X86/vselect.ll +++ b/llvm/test/CodeGen/X86/vselect.ll @@ -536,8 +536,8 @@ ; SSE41: # %bb.0: ; SSE41-NEXT: psllq $63, %xmm0 ; SSE41-NEXT: psrad $31, %xmm0 -; SSE41-NEXT: pshufd {{.*#+}} xmm0 = xmm0[1,1,3,3] ; SSE41-NEXT: blendvpd %xmm0, %xmm1, %xmm2 +; SSE41-NEXT: pshufd {{.*#+}} xmm0 = xmm0[1,1,3,3] ; SSE41-NEXT: paddq %xmm2, %xmm0 ; SSE41-NEXT: retq ;