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Remove this xform: 

(shl (add x, c1), c2) -> (add (shl x, c2), c1<<c2)
Replace it with:
(add (shl (add x, c1), c2), ) -> (add (add (shl x, c2), c1<<c2), )

This fixes test/CodeGen/ARM/smul.ll

llvm-svn: 33361
This commit is contained in:
Evan Cheng 2007-01-19 17:51:44 +00:00
parent e5f3de3896
commit 9201100b29
1 changed files with 26 additions and 7 deletions
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33
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -653,6 +653,22 @@ SDOperand DAGCombiner::visitTokenFactor(SDNode *N) {
return Result;
}
static
SDOperand combineShlAddConstant(SDOperand N0, SDOperand N1, SelectionDAG &DAG) {
MVT::ValueType VT = N0.getValueType();
SDOperand N00 = N0.getOperand(0);
SDOperand N01 = N0.getOperand(1);
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N01);
if (N01C && N00.getOpcode() == ISD::ADD && N00.Val->hasOneUse() &&
isa<ConstantSDNode>(N00.getOperand(1))) {
N0 = DAG.getNode(ISD::ADD, VT,
DAG.getNode(ISD::SHL, VT, N00.getOperand(0), N01),
DAG.getNode(ISD::SHL, VT, N00.getOperand(1), N01));
return DAG.getNode(ISD::ADD, VT, N0, N1);
}
return SDOperand();
}
SDOperand DAGCombiner::visitADD(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
@ -711,6 +727,16 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
}
}
// fold (add (shl (add x, c1), c2), ) -> (add (add (shl x, c2), c1<<c2), )
if (N0.getOpcode() == ISD::SHL && N0.Val->hasOneUse()) {
SDOperand Result = combineShlAddConstant(N0, N1, DAG);
if (Result.Val) return Result;
}
if (N1.getOpcode() == ISD::SHL && N1.Val->hasOneUse()) {
SDOperand Result = combineShlAddConstant(N1, N0, DAG);
if (Result.Val) return Result;
}
return SDOperand();
}
@ -1615,13 +1641,6 @@ SDOperand DAGCombiner::visitSHL(SDNode *N) {
if (N1C && N0.getOpcode() == ISD::SRA && N1 == N0.getOperand(1))
return DAG.getNode(ISD::AND, VT, N0.getOperand(0),
DAG.getConstant(~0ULL << N1C->getValue(), VT));
// fold (shl (add x, c1), c2) -> (add (shl x, c2), c1<<c2)
if (N1C && N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse() &&
isa<ConstantSDNode>(N0.getOperand(1))) {
return DAG.getNode(ISD::ADD, VT,
DAG.getNode(ISD::SHL, VT, N0.getOperand(0), N1),
DAG.getNode(ISD::SHL, VT, N0.getOperand(1), N1));
}
return SDOperand();
}