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(add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
(sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c))

llvm-svn: 37685
This commit is contained in:
Evan Cheng 2007-06-21 07:39:16 +00:00
parent a783224b25
commit f26fc091ac
1 changed files with 64 additions and 0 deletions
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64
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -801,6 +801,55 @@ SDOperand combineShlAddConstant(SDOperand N0, SDOperand N1, SelectionDAG &DAG) {
return SDOperand();
}
static
SDOperand combineSelectAndUse(SDNode *N, SDOperand Slct, SDOperand OtherOp,
SelectionDAG &DAG) {
MVT::ValueType VT = N->getValueType(0);
unsigned Opc = N->getOpcode();
bool isSlctCC = Slct.getOpcode() == ISD::SELECT_CC;
SDOperand LHS = isSlctCC ? Slct.getOperand(2) : Slct.getOperand(1);
SDOperand RHS = isSlctCC ? Slct.getOperand(3) : Slct.getOperand(2);
ISD::CondCode CC = ISD::SETCC_INVALID;
if (isSlctCC)
CC = cast<CondCodeSDNode>(Slct.getOperand(4))->get();
else {
SDOperand CCOp = Slct.getOperand(0);
if (CCOp.getOpcode() == ISD::SETCC)
CC = cast<CondCodeSDNode>(CCOp.getOperand(2))->get();
}
bool DoXform = false;
bool InvCC = false;
assert ((Opc == ISD::ADD || (Opc == ISD::SUB && Slct == N->getOperand(1))) &&
"Bad input!");
if (LHS.getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(LHS)->isNullValue())
DoXform = true;
else if (CC != ISD::SETCC_INVALID &&
RHS.getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(RHS)->isNullValue()) {
std::swap(LHS, RHS);
bool isInt = MVT::isInteger(isSlctCC ? Slct.getOperand(0).getValueType()
: Slct.getOperand(0).getOperand(0).getValueType());
CC = ISD::getSetCCInverse(CC, isInt);
DoXform = true;
InvCC = true;
}
if (DoXform) {
SDOperand Result = DAG.getNode(Opc, VT, OtherOp, RHS);
if (isSlctCC)
return DAG.getSelectCC(OtherOp, Result,
Slct.getOperand(0), Slct.getOperand(1), CC);
SDOperand CCOp = Slct.getOperand(0);
if (InvCC)
CCOp = DAG.getSetCC(CCOp.getValueType(), CCOp.getOperand(0),
CCOp.getOperand(1), CC);
return DAG.getNode(ISD::SELECT, VT, CCOp, OtherOp, Result);
}
return SDOperand();
}
SDOperand DAGCombiner::visitADD(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
@ -869,6 +918,16 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
if (Result.Val) return Result;
}
// fold (add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
if (N0.getOpcode() == ISD::SELECT && N0.Val->hasOneUse()) {
SDOperand Result = combineSelectAndUse(N, N0, N1, DAG);
if (Result.Val) return Result;
}
if (N1.getOpcode() == ISD::SELECT && N1.Val->hasOneUse()) {
SDOperand Result = combineSelectAndUse(N, N1, N0, DAG);
if (Result.Val) return Result;
}
return SDOperand();
}
@ -960,6 +1019,11 @@ SDOperand DAGCombiner::visitSUB(SDNode *N) {
// fold (A+B)-B -> A
if (N0.getOpcode() == ISD::ADD && N0.getOperand(1) == N1)
return N0.getOperand(0);
// fold (sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c))
if (N1.getOpcode() == ISD::SELECT && N1.Val->hasOneUse()) {
SDOperand Result = combineSelectAndUse(N, N1, N0, DAG);
if (Result.Val) return Result;
}
return SDOperand();
}