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[X86] Move BEXTR DemandedBits handling inside SimplifyDemandedBitsForTargetNode

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Some prep work for PR39153.
This commit is contained in:
Simon Pilgrim 2020-02-03 14:01:12 +00:00
parent 80bf477ac5
commit 1f9f866ff9
1 changed files with 28 additions and 16 deletions
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44
lib/Target/X86/X86ISelLowering.cpp
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@ -36247,6 +36247,30 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
Known.Zero.setLowBits(NumElts);
return false;
}
case X86ISD::BEXTR: {
SDValue Op0 = Op.getOperand(0);
SDValue Op1 = Op.getOperand(1);
// Only bottom 16-bits of the control bits are required.
if (auto *Cst1 = dyn_cast<ConstantSDNode>(Op1)) {
// NOTE: SimplifyDemandedBits won't do this for constants.
const APInt &Val1 = Cst1->getAPIntValue();
APInt MaskedVal1 = Val1 & 0xFFFF;
if (MaskedVal1 != Val1) {
SDLoc DL(Op);
return TLO.CombineTo(
Op, TLO.DAG.getNode(X86ISD::BEXTR, DL, VT, Op0,
TLO.DAG.getConstant(MaskedVal1, DL, VT)));
}
}
KnownBits Known1;
APInt DemandedMask(APInt::getLowBitsSet(BitWidth, 16));
if (SimplifyDemandedBits(Op1, DemandedMask, Known1, TLO, Depth + 1))
return true;
break;
}
}
return TargetLowering::SimplifyDemandedBitsForTargetNode(
@ -43019,27 +43043,15 @@ static SDValue combineXor(SDNode *N, SelectionDAG &DAG,
static SDValue combineBEXTR(SDNode *N, SelectionDAG &DAG,
TargetLowering::DAGCombinerInfo &DCI,
const X86Subtarget &Subtarget) {
SDValue Op0 = N->getOperand(0);
SDValue Op1 = N->getOperand(1);
EVT VT = N->getValueType(0);
unsigned NumBits = VT.getSizeInBits();
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
// TODO - Constant Folding.
if (auto *Cst1 = dyn_cast<ConstantSDNode>(Op1)) {
// Reduce Cst1 to the bottom 16-bits.
// NOTE: SimplifyDemandedBits won't do this for constants.
const APInt &Val1 = Cst1->getAPIntValue();
APInt MaskedVal1 = Val1 & 0xFFFF;
if (MaskedVal1 != Val1)
return DAG.getNode(X86ISD::BEXTR, SDLoc(N), VT, Op0,
DAG.getConstant(MaskedVal1, SDLoc(N), VT));
}
// Only bottom 16-bits of the control bits are required.
APInt DemandedMask(APInt::getLowBitsSet(NumBits, 16));
if (TLI.SimplifyDemandedBits(Op1, DemandedMask, DCI))
// Simplify the inputs.
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
APInt DemandedMask(APInt::getAllOnesValue(NumBits));
if (TLI.SimplifyDemandedBits(SDValue(N, 0), DemandedMask, DCI))
return SDValue(N, 0);
return SDValue();