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teach dag combiner how to eliminate MERGE_VALUES nodes. 

llvm-svn: 47052
This commit is contained in:
Chris Lattner 2008-02-13 07:25:05 +00:00
parent eea32990a9
commit ee322b44a4
1 changed files with 14 additions and 0 deletions
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14
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -137,6 +137,7 @@ namespace {
// otherwise - N should be replaced by the returned Operand.
//
SDOperand visitTokenFactor(SDNode *N);
SDOperand visitMERGE_VALUES(SDNode *N);
SDOperand visitADD(SDNode *N);
SDOperand visitSUB(SDNode *N);
SDOperand visitADDC(SDNode *N);
@ -662,6 +663,7 @@ SDOperand DAGCombiner::visit(SDNode *N) {
switch(N->getOpcode()) {
default: break;
case ISD::TokenFactor: return visitTokenFactor(N);
case ISD::MERGE_VALUES: return visitMERGE_VALUES(N);
case ISD::ADD: return visitADD(N);
case ISD::SUB: return visitSUB(N);
case ISD::ADDC: return visitADDC(N);
@ -837,6 +839,18 @@ SDOperand DAGCombiner::visitTokenFactor(SDNode *N) {
return Result;
}
/// MERGE_VALUES can always be eliminated.
SDOperand DAGCombiner::visitMERGE_VALUES(SDNode *N) {
WorkListRemover DeadNodes(*this);
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, i), N->getOperand(i),
&DeadNodes);
removeFromWorkList(N);
DAG.DeleteNode(N);
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
static
SDOperand combineShlAddConstant(SDOperand N0, SDOperand N1, SelectionDAG &DAG) {
MVT::ValueType VT = N0.getValueType();