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Teach SelectionDAG how to simplify a few more setcc-equivalent select_cc

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nodes so that backends don't have to.

llvm-svn: 22999
This commit is contained in:
Nate Begeman 2005-08-24 04:57:57 +00:00
parent f034da3bd4
commit 2fc750ca45
1 changed files with 21 additions and 6 deletions
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27
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -853,21 +853,36 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2,
}
}
// Check to see if this is the equivalent of seteq X, 0.
// select_cc eq X, 0, 1, 0 -> setcc X, 0, eq -> srl (ctlz X), log2(size(X))
if (N2C && N2C->isNullValue() && N4C && N4C->isNullValue() &&
N3C && (N3C->getValue() == 1ULL) && CC == ISD::SETEQ) {
// Check to see if this is the equivalent of setcc X, 0
if (N4C && N4C->isNullValue() && N3C && (N3C->getValue() == 1ULL)) {
MVT::ValueType XType = N1.getValueType();
if (TLI.getOperationAction(ISD::SETCC, TLI.getSetCCResultTy()) ==
TargetLowering::Legal) {
return getSetCC(TLI.getSetCCResultTy(), N1, N2, ISD::SETEQ);
return getSetCC(TLI.getSetCCResultTy(), N1, N2, CC);
}
if (TLI.getOperationAction(ISD::CTLZ, XType) == TargetLowering::Legal) {
// seteq X, 0 -> srl (ctlz X, log2(size(X)))
if (N2C && N2C->isNullValue() && CC == ISD::SETEQ &&
TLI.getOperationAction(ISD::CTLZ, XType) == TargetLowering::Legal) {
SDOperand Ctlz = getNode(ISD::CTLZ, XType, N1);
return getNode(ISD::SRL, XType, Ctlz,
getConstant(Log2_32(MVT::getSizeInBits(XType)),
TLI.getShiftAmountTy()));
}
// setgt X, 0 -> srl (and (-X, ~X), size(X)-1)
if (N2C && N2C->isNullValue() && CC == ISD::SETGT) {
SDOperand NegN1 = getNode(ISD::SUB, XType, getConstant(0, XType), N1);
SDOperand NotN1 = getNode(ISD::XOR, XType, N1, getConstant(~0ULL, XType));
return getNode(ISD::SRL, XType, getNode(ISD::AND, XType, NegN1, NotN1),
getConstant(MVT::getSizeInBits(XType)-1,
TLI.getShiftAmountTy()));
}
// setgt X, -1 -> xor (srl (X, size(X)-1), 1)
if (N2C && N2C->isAllOnesValue() && CC == ISD::SETGT) {
SDOperand Sign = getNode(ISD::SRL, XType, N1,
getConstant(MVT::getSizeInBits(XType)-1,
TLI.getShiftAmountTy()));
return getNode(ISD::XOR, XType, Sign, getConstant(1, XType));
}
}
// Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X ->