diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Target/X86/X86ISelLowering.cpp | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index ba357ed76c..5290453f05 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -969,6 +969,8 @@ X86TargetLowering::X86TargetLowering(X86TargetMachine &TM) setTargetDAGCombine(ISD::SRL); setTargetDAGCombine(ISD::OR); setTargetDAGCombine(ISD::AND); + setTargetDAGCombine(ISD::ADD); + setTargetDAGCombine(ISD::SUB); setTargetDAGCombine(ISD::STORE); setTargetDAGCombine(ISD::ZERO_EXTEND); if (Subtarget->is64Bit()) @@ -11513,6 +11515,44 @@ static SDValue PerformADCCombine(SDNode *N, SelectionDAG &DAG, return SDValue(); } +// fold (add Y, (sete X, 0)) -> adc 0, Y +// (add Y, (setne X, 0)) -> sbb -1, Y +// (sub (sete X, 0), Y) -> sbb 0, Y +// (sub (setne X, 0), Y) -> adc -1, Y +static SDValue OptimizeConditonalInDecrement(SDNode *N, SelectionDAG &DAG) { + DebugLoc DL = N->getDebugLoc(); + + // Look through ZExts. + SDValue Ext = N->getOperand(N->getOpcode() == ISD::SUB ? 1 : 0); + if (Ext.getOpcode() != ISD::ZERO_EXTEND || !Ext.hasOneUse()) + return SDValue(); + + SDValue SetCC = Ext.getOperand(0); + if (SetCC.getOpcode() != X86ISD::SETCC || !SetCC.hasOneUse()) + return SDValue(); + + X86::CondCode CC = (X86::CondCode)SetCC.getConstantOperandVal(0); + if (CC != X86::COND_E && CC != X86::COND_NE) + return SDValue(); + + SDValue Cmp = SetCC.getOperand(1); + if (Cmp.getOpcode() != X86ISD::CMP || !Cmp.hasOneUse() || + !X86::isZeroNode(Cmp.getOperand(1))) + return SDValue(); + + SDValue CmpOp0 = Cmp.getOperand(0); + SDValue NewCmp = DAG.getNode(X86ISD::CMP, DL, MVT::i32, CmpOp0, + DAG.getConstant(1, CmpOp0.getValueType())); + + SDValue OtherVal = N->getOperand(N->getOpcode() == ISD::SUB ? 0 : 1); + if (CC == X86::COND_NE) + return DAG.getNode(N->getOpcode() == ISD::SUB ? X86ISD::ADC : X86ISD::SBB, + DL, OtherVal.getValueType(), OtherVal, + DAG.getConstant(-1ULL, OtherVal.getValueType()), NewCmp); + return DAG.getNode(N->getOpcode() == ISD::SUB ? X86ISD::SBB : X86ISD::ADC, + DL, OtherVal.getValueType(), OtherVal, + DAG.getConstant(0, OtherVal.getValueType()), NewCmp); +} SDValue X86TargetLowering::PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const { @@ -11523,6 +11563,8 @@ SDValue X86TargetLowering::PerformDAGCombine(SDNode *N, return PerformEXTRACT_VECTOR_ELTCombine(N, DAG, *this); case ISD::SELECT: return PerformSELECTCombine(N, DAG, Subtarget); case X86ISD::CMOV: return PerformCMOVCombine(N, DAG, DCI); + case ISD::ADD: + case ISD::SUB: return OptimizeConditonalInDecrement(N, DAG); case X86ISD::ADC: return PerformADCCombine(N, DAG, DCI); case ISD::MUL: return PerformMulCombine(N, DAG, DCI); case ISD::SHL: |