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New fold for SELECT_CC

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23058 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2005-08-25 20:04:38 +00:00
parent c8e27db5c5
commit 1999b4b974
1 changed files with 19 additions and 1 deletions
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20
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -843,6 +843,7 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2,
SDOperand N3, SDOperand N4,
ISD::CondCode CC) {
MVT::ValueType VT = N3.getValueType();
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.Val);
ConstantSDNode *N3C = dyn_cast<ConstantSDNode>(N3.Val);
ConstantSDNode *N4C = dyn_cast<ConstantSDNode>(N4.Val);
@ -865,6 +866,23 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2,
}
}
// check to see if we're select_cc'ing a select_cc.
// this allows us to turn:
// select_cc set[eq,ne] (select_cc cc, lhs, rhs, 1, 0), 0, true, false ->
// select_cc cc, lhs, rhs, true, false
if ((N1C && N1C->isNullValue() && N2.getOpcode() == ISD::SELECT_CC) ||
(N2C && N2C->isNullValue() && N1.getOpcode() == ISD::SELECT_CC) &&
(CC == ISD::SETEQ || CC == ISD::SETNE)) {
SDOperand SCC = N1C ? N2 : N1;
ConstantSDNode *SCCT = dyn_cast<ConstantSDNode>(SCC.getOperand(2));
ConstantSDNode *SCCF = dyn_cast<ConstantSDNode>(SCC.getOperand(3));
if (SCCT && SCCF && SCCF->isNullValue() && SCCT->getValue() == 1ULL) {
if (CC == ISD::SETEQ) std::swap(N3, N4);
return getNode(ISD::SELECT_CC, N3.getValueType(), SCC.getOperand(0),
SCC.getOperand(1), N3, N4, SCC.getOperand(4));
}
}
// Check to see if we can perform the "gzip trick", transforming
// select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A
if (N2C && N2C->isNullValue() && N4C && N4C->isNullValue() &&
@ -894,7 +912,7 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2,
}
}
// Check to see if this is the equivalent of setcc X, 0
// Check to see if this is the equivalent of setcc
if (N4C && N4C->isNullValue() && N3C && (N3C->getValue() == 1ULL)) {
MVT::ValueType XType = N1.getValueType();
if (TLI.isOperationLegal(ISD::SETCC, TLI.getSetCCResultTy()))