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Add a simple xform that is useful for bitfield operations. 

llvm-svn: 24029
This commit is contained in:
Chris Lattner 2005-10-27 05:06:38 +00:00
parent 97cbaf5c89
commit d8c5c066a1
1 changed files with 9 additions and 0 deletions
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9
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1103,7 +1103,16 @@ SDOperand DAGCombiner::visitOR(SDNode *N) {
if (N01C)
return DAG.getNode(ISD::OR, VT, N0.getOperand(0),
DAG.getConstant(N1C->getValue()|N01C->getValue(), VT));
} else if (N1C && N0.getOpcode() == ISD::AND && N0.Val->hasOneUse() &&
isa<ConstantSDNode>(N0.getOperand(1))) {
// Canonicalize (or (and X, c1), c2) -> (and (or X, c2), c1|c2)
ConstantSDNode *C1 = cast<ConstantSDNode>(N0.getOperand(1));
return DAG.getNode(ISD::AND, VT, DAG.getNode(ISD::OR, VT, N0.getOperand(0),
N1),
DAG.getConstant(N1C->getValue() | C1->getValue(), VT));
}
// fold (or (setcc x), (setcc y)) -> (setcc (or x, y))
if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){
ISD::CondCode Op0 = cast<CondCodeSDNode>(CC0)->get();