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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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56
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -6892,38 +6892,34 @@ 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) // Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) && if (N1C) {
N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1) && ConstantSDNode *SubC = NULL;
N2.getOperand(0) == N1 && N0.getValueType().isInteger()) { 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(); EVT XType = N0.getValueType();
SDValue Shift = DAG.getNode(ISD::SRA, N0.getDebugLoc(), XType, N0, if (SubC && SubC->isNullValue() && XType.isInteger()) {
DAG.getConstant(XType.getSizeInBits()-1, SDValue Shift = DAG.getNode(ISD::SRA, N0.getDebugLoc(), XType,
getShiftAmountTy())); N0,
SDValue Add = DAG.getNode(ISD::ADD, N0.getDebugLoc(), XType, DAG.getConstant(XType.getSizeInBits()-1,
N0, Shift); getShiftAmountTy()));
AddToWorkList(Shift.getNode()); SDValue Add = DAG.getNode(ISD::ADD, N0.getDebugLoc(),
AddToWorkList(Add.getNode()); XType, N0, Shift);
return DAG.getNode(ISD::XOR, DL, XType, Add, Shift); AddToWorkList(Shift.getNode());
} AddToWorkList(Add.getNode());
// Check to see if this is an integer abs. select_cc setgt X, -1, X, -X -> return DAG.getNode(ISD::XOR, DL, XType, Add, Shift);
// 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()) {
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);
}
} }
} }