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Merge the duplicated iabs optimization in DAGCombiner and let it detected a few more idioms. 

llvm-svn: 107868
This commit is contained in:
Benjamin Kramer 2010-07-08 12:09:56 +00:00
parent e17a0a7072
commit 0ae3f08c0d
1 changed files with 26 additions and 30 deletions
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38
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -6892,28 +6892,25 @@ SDValue DAGCombiner::SimplifySelectCC(DebugLoc DL, SDValue N0, SDValue N1,
}
}
// Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X ->
// Check to see if this is an integer abs.
// select_cc setg[te] X, 0, X, -X ->
// select_cc setgt X, -1, X, -X ->
// select_cc setl[te] X, 0, -X, X ->
// select_cc setlt X, 1, -X, X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) &&
N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1) &&
N2.getOperand(0) == N1 && N0.getValueType().isInteger()) {
if (N1C) {
ConstantSDNode *SubC = NULL;
if (((N1C->isNullValue() && (CC == ISD::SETGT || CC == ISD::SETGE)) ||
(N1C->isAllOnesValue() && CC == ISD::SETGT)) &&
N0 == N2 && N3.getOpcode() == ISD::SUB && N0 == N3.getOperand(1))
SubC = dyn_cast<ConstantSDNode>(N3.getOperand(0));
else if (((N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE)) ||
(N1C->isOne() && CC == ISD::SETLT)) &&
N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1))
SubC = dyn_cast<ConstantSDNode>(N2.getOperand(0));
EVT XType = N0.getValueType();
SDValue Shift = DAG.getNode(ISD::SRA, N0.getDebugLoc(), XType, N0,
DAG.getConstant(XType.getSizeInBits()-1,
getShiftAmountTy()));
SDValue Add = DAG.getNode(ISD::ADD, N0.getDebugLoc(), XType,
N0, Shift);
AddToWorkList(Shift.getNode());
AddToWorkList(Add.getNode());
return DAG.getNode(ISD::XOR, DL, XType, Add, Shift);
}
// Check to see if this is an integer abs. select_cc setgt X, -1, X, -X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isAllOnesValue() && CC == ISD::SETGT &&
N0 == N2 && N3.getOpcode() == ISD::SUB && N0 == N3.getOperand(1)) {
if (ConstantSDNode *SubC = dyn_cast<ConstantSDNode>(N3.getOperand(0))) {
EVT XType = N0.getValueType();
if (SubC->isNullValue() && XType.isInteger()) {
if (SubC && SubC->isNullValue() && XType.isInteger()) {
SDValue Shift = DAG.getNode(ISD::SRA, N0.getDebugLoc(), XType,
N0,
DAG.getConstant(XType.getSizeInBits()-1,
@ -6925,7 +6922,6 @@ SDValue DAGCombiner::SimplifySelectCC(DebugLoc DL, SDValue N0, SDValue N1,
return DAG.getNode(ISD::XOR, DL, XType, Add, Shift);
}
}
}
return SDValue();
}