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[SelectionDAG] ComputeNumSignBits - use Valid Min/Max shift amount helpers directly. NFCI. 

We are calling getValidShiftAmountConstant first followed by getValidMinimumShiftAmountConstant/getValidMaximumShiftAmountConstant if that failed. But both are used in the same way in ComputeNumSignBits and the Min/Max variants call getValidShiftAmountConstant internally anyhow.
This commit is contained in:
Simon Pilgrim 2020-05-30 14:02:14 +01:00
parent 179f8ad08d
commit 9d0bfcec83
1 changed files with 4 additions and 10 deletions
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14
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -3657,23 +3657,17 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
case ISD::SRA:
Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
// SRA X, C -> adds C sign bits.
if (const APInt *ShAmt = getValidShiftAmountConstant(Op, DemandedElts))
Tmp = std::min<uint64_t>(Tmp + ShAmt->getZExtValue(), VTBits);
else if (const APInt *ShAmt =
getValidMinimumShiftAmountConstant(Op, DemandedElts))
if (const APInt *ShAmt =
getValidMinimumShiftAmountConstant(Op, DemandedElts))
Tmp = std::min<uint64_t>(Tmp + ShAmt->getZExtValue(), VTBits);
return Tmp;
case ISD::SHL:
if (const APInt *ShAmt = getValidShiftAmountConstant(Op, DemandedElts)) {
if (const APInt *ShAmt =
getValidMaximumShiftAmountConstant(Op, DemandedElts)) {
// shl destroys sign bits, ensure it doesn't shift out all sign bits.
Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
if (ShAmt->ult(Tmp))
return Tmp - ShAmt->getZExtValue();
} else if (const APInt *ShAmt =
getValidMaximumShiftAmountConstant(Op, DemandedElts)) {
Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
if (ShAmt->ult(Tmp))
return Tmp - ShAmt->getZExtValue();
}
break;
case ISD::AND: