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[TargetLowering] simplify code for uaddsat/usubsat expansion; NFC 

llvm-svn: 355508
This commit is contained in:
Sanjay Patel 2019-03-06 14:34:59 +00:00
parent 9052f50cb4
commit 89e534746f
1 changed files with 5 additions and 8 deletions
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13
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -5438,17 +5438,14 @@ SDValue TargetLowering::expandAddSubSat(SDNode *Node, SelectionDAG &DAG) const {
SDValue SumDiff = Result.getValue(0);
SDValue Overflow = Result.getValue(1);
SDValue Zero = DAG.getConstant(0, dl, ResultType);
SDValue AllOnes = DAG.getAllOnesConstant(dl, ResultType);
if (Opcode == ISD::UADDSAT) {
// Just need to check overflow for SatMax.
APInt MaxVal = APInt::getMaxValue(BitWidth);
SDValue SatMax = DAG.getConstant(MaxVal, dl, ResultType);
return DAG.getSelect(dl, ResultType, Overflow, SatMax, SumDiff);
// Overflow ? 0xffff.... : (LHS + RHS)
return DAG.getSelect(dl, ResultType, Overflow, AllOnes, SumDiff);
} else if (Opcode == ISD::USUBSAT) {
// Just need to check overflow for SatMin.
APInt MinVal = APInt::getMinValue(BitWidth);
SDValue SatMin = DAG.getConstant(MinVal, dl, ResultType);
return DAG.getSelect(dl, ResultType, Overflow, SatMin, SumDiff);
// Overflow ? 0 : (LHS - RHS)
return DAG.getSelect(dl, ResultType, Overflow, Zero, SumDiff);
} else {
// SatMax -> Overflow && SumDiff < 0
// SatMin -> Overflow && SumDiff >= 0