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Hacker's Delight says, "Signed integer overflow of addition occurs if and only 

if the operands have the same sign and the sum has sign opposite to that of the
operands."

llvm-svn: 60014
This commit is contained in:
Bill Wendling 2008-11-25 08:12:19 +00:00
parent f3e95505c5
commit 4498b47677
1 changed files with 48 additions and 4 deletions
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52
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -4170,7 +4170,53 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
break;
}
case ISD::SADDO:
case ISD::SADDO: {
MVT VT = Node->getValueType(0);
switch (TLI.getOperationAction(Node->getOpcode(), VT)) {
default: assert(0 && "This action not supported for this op yet!");
case TargetLowering::Custom:
Result = TLI.LowerOperation(Op, DAG);
if (Result.getNode()) break;
// FALLTHROUGH
case TargetLowering::Legal: {
SDValue LHS = LegalizeOp(Node->getOperand(0));
SDValue RHS = LegalizeOp(Node->getOperand(1));
SDValue Sum = DAG.getNode(ISD::ADD, LHS.getValueType(), LHS, RHS);
MVT SType = Node->getValueType(0);
MVT OType = Node->getValueType(1);
SDValue Zero = DAG.getConstant(0, OType);
SDValue LHSPos = DAG.getSetCC(OType, LHS, Zero, ISD::SETGE);
SDValue RHSPos = DAG.getSetCC(OType, RHS, Zero, ISD::SETGE);
SDValue And1 = DAG.getNode(ISD::AND, OType, LHSPos, RHSPos);
And1 = DAG.getNode(ISD::AND, OType, And1,
DAG.getSetCC(OType, Sum, Zero, ISD::SETLT));
SDValue LHSNeg = DAG.getSetCC(OType, LHS, Zero, ISD::SETLT);
SDValue RHSNeg = DAG.getSetCC(OType, RHS, Zero, ISD::SETLT);
SDValue And2 = DAG.getNode(ISD::AND, OType, LHSNeg, RHSNeg);
And2 = DAG.getNode(ISD::AND, OType, And2,
DAG.getSetCC(OType, Sum, Zero, ISD::SETGE));
SDValue Cmp = DAG.getNode(ISD::OR, OType, And1, And2);
MVT ValueVTs[] = { LHS.getValueType(), OType };
SDValue Ops[] = { Sum, Cmp };
Result = DAG.getMergeValues(DAG.getVTList(&ValueVTs[0], 2), &Ops[0], 2);
SDNode *RNode = Result.getNode();
DAG.ReplaceAllUsesOfValueWith(SDValue(Node, 0), SDValue(RNode, 0));
DAG.ReplaceAllUsesOfValueWith(SDValue(Node, 1), SDValue(RNode, 1));
break;
}
}
break;
}
case ISD::UADDO: {
MVT VT = Node->getValueType(0);
switch (TLI.getOperationAction(Node->getOpcode(), VT)) {
@ -4185,9 +4231,7 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
SDValue Sum = DAG.getNode(ISD::ADD, LHS.getValueType(), LHS, RHS);
MVT OType = Node->getValueType(1);
SDValue Cmp = DAG.getSetCC(OType, Sum, LHS,
(Node->getOpcode() == ISD::SADDO) ?
ISD::SETLT : ISD::SETULT);
SDValue Cmp = DAG.getSetCC(OType, Sum, LHS, ISD::SETULT);
MVT ValueVTs[] = { LHS.getValueType(), OType };
SDValue Ops[] = { Sum, Cmp };