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Implement a common missing fold, (add (add x, c1), c2) -> (add x, c1+c2).

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This restores all of stanford to being identical with and without the dag
combiner with the add folding turned off in sd.cpp.

llvm-svn: 23258
This commit is contained in:
Nate Begeman 2005-09-07 16:09:19 +00:00
parent 617b26ddd7
commit e8db0c961a
1 changed files with 14 additions and 8 deletions
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22
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -342,32 +342,38 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT::ValueType VT = N0.getValueType();
// fold (add c1, c2) -> c1+c2
if (N0C && N1C)
return DAG.getConstant(N0C->getValue() + N1C->getValue(),
N->getValueType(0));
return DAG.getConstant(N0C->getValue() + N1C->getValue(), VT);
// fold (add x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// fold (add (add x, c1), c2) -> (add x, c1+c2)
if (N1C && N0.getOpcode() == ISD::ADD &&
N0.getOperand(1).getOpcode() == ISD::Constant)
return DAG.getNode(ISD::ADD, VT, N0.getOperand(0),
DAG.getConstant(N1C->getValue() +
cast<ConstantSDNode>(N0.getOperand(1))->getValue(),
VT));
// fold floating point (add c1, c2) -> c1+c2
if (N0CFP && N1CFP)
return DAG.getConstantFP(N0CFP->getValue() + N1CFP->getValue(),
N->getValueType(0));
return DAG.getConstantFP(N0CFP->getValue() + N1CFP->getValue(), VT);
// fold (A + (-B)) -> A-B
if (N1.getOpcode() == ISD::FNEG)
return DAG.getNode(ISD::SUB, N->getValueType(0), N0, N1.getOperand(0));
return DAG.getNode(ISD::SUB, VT, N0, N1.getOperand(0));
// fold ((-A) + B) -> B-A
if (N0.getOpcode() == ISD::FNEG)
return DAG.getNode(ISD::SUB, N->getValueType(0), N1, N0.getOperand(0));
return DAG.getNode(ISD::SUB, VT, N1, N0.getOperand(0));
// fold ((0-A) + B) -> B-A
if (N0.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N0.getOperand(0)) &&
cast<ConstantSDNode>(N0.getOperand(0))->isNullValue())
return DAG.getNode(ISD::SUB, N->getValueType(0), N1, N0.getOperand(1));
return DAG.getNode(ISD::SUB, VT, N1, N0.getOperand(1));
// fold (A + (0-B)) -> A-B
if (N1.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N1.getOperand(0)) &&
cast<ConstantSDNode>(N1.getOperand(0))->isNullValue())
return DAG.getNode(ISD::SUB, N->getValueType(0), N0, N1.getOperand(1));
return DAG.getNode(ISD::SUB, VT, N0, N1.getOperand(1));
// fold (A+(B-A)) -> B for non-fp types
if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(1) &&
!MVT::isFloatingPoint(N1.getValueType()))