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Avoid promoting a i16 node if it would eliminate a (store (op (load))) opportunity.

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llvm-svn: 102237
This commit is contained in:
Evan Cheng 2010-04-24 04:44:57 +00:00
parent 3eedf18f4c
commit ec4cc9ce14
1 changed files with 12 additions and 5 deletions
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17
lib/Target/X86/X86ISelLowering.cpp
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@ -10015,6 +10015,14 @@ bool X86TargetLowering::isTypeDesirableForOp(unsigned Opc, EVT VT) const {
}
}
static bool MayFoldLoad(SDValue Op) {
return Op.hasOneUse() && ISD::isNormalLoad(Op.getNode());
}
static bool MayFoldIntoStore(SDValue Op) {
return Op.hasOneUse() && ISD::isNormalStore(*Op.getNode()->use_begin());
}
/// IsDesirableToPromoteOp - This method query the target whether it is
/// beneficial for dag combiner to promote the specified node. If true, it
/// should return the desired promotion type by reference.
@ -10051,8 +10059,7 @@ bool X86TargetLowering::IsDesirableToPromoteOp(SDValue Op, EVT &PVT) const {
case ISD::SRL: {
SDValue N0 = Op.getOperand(0);
// Look out for (store (shl (load), x)).
if (isa<LoadSDNode>(N0) && N0.hasOneUse() &&
Op.hasOneUse() && Op.getNode()->use_begin()->getOpcode() == ISD::STORE)
if (MayFoldLoad(N0) && MayFoldIntoStore(Op))
return false;
Promote = true;
break;
@ -10067,12 +10074,12 @@ bool X86TargetLowering::IsDesirableToPromoteOp(SDValue Op, EVT &PVT) const {
case ISD::SUB: {
SDValue N0 = Op.getOperand(0);
SDValue N1 = Op.getOperand(1);
if (!Commute && isa<LoadSDNode>(N1))
if (!Commute && MayFoldLoad(N1))
return false;
// Avoid disabling potential load folding opportunities.
if ((isa<LoadSDNode>(N0) && N0.hasOneUse()) && !isa<ConstantSDNode>(N1))
if (MayFoldLoad(N0) && (!isa<ConstantSDNode>(N1) || MayFoldIntoStore(Op)))
return false;
if ((isa<LoadSDNode>(N1) && N1.hasOneUse()) && !isa<ConstantSDNode>(N0))
if (MayFoldLoad(N1) && (!isa<ConstantSDNode>(N0) || MayFoldIntoStore(Op)))
return false;
Promote = true;
}