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Avoid creating a token factor node in trivially redundant cases. This

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eliminates almost one node per block in common cases.

llvm-svn: 24254
This commit is contained in:
Chris Lattner 2005-11-09 05:03:03 +00:00
parent 43535a19b1
commit b7cad90e55
1 changed files with 12 additions and 1 deletions
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13
llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -1234,7 +1234,18 @@ void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
// Turn all of the unordered chains into one factored node.
if (!UnorderedChains.empty()) {
UnorderedChains.push_back(SDL.getRoot());
SDOperand Root = SDL.getRoot();
if (Root.getOpcode() != ISD::EntryToken) {
unsigned i = 0, e = UnorderedChains.size();
for (; i != e; ++i) {
assert(UnorderedChains[i].Val->getNumOperands() > 1);
if (UnorderedChains[i].Val->getOperand(0) == Root)
break; // Don't add the root if we already indirectly depend on it.
}
if (i == e)
UnorderedChains.push_back(Root);
}
DAG.setRoot(DAG.getNode(ISD::TokenFactor, MVT::Other, UnorderedChains));
}