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Fix SelectionDAG::ReplaceAllUsesWith to behave correctly when

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uses are added to the From node while it is processing From's
use list, because of automatic local CSE. The fix is to avoid
visiting any new uses.

Fix a few places in the DAGCombiner that assumed that after
a RAUW call, the From node has no users and may be deleted.

This fixes PR3018.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62533 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-01-19 21:44:21 +00:00
parent 2c7ed11d93
commit dbe664adcd
3 changed files with 47 additions and 16 deletions
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30
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@@ -522,12 +522,17 @@ SDValue DAGCombiner::CombineTo(SDNode *N, const SDValue *To, unsigned NumTo,
}
}
// Nodes can be reintroduced into the worklist. Make sure we do not
// process a node that has been replaced.
removeFromWorkList(N);
// Finally, if the node is now dead, remove it from the graph. The node
// may not be dead if the replacement process recursively simplified to
// something else needing this node.
if (N->use_empty()) {
// Nodes can be reintroduced into the worklist. Make sure we do not
// process a node that has been replaced.
removeFromWorkList(N);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
}
return SDValue(N, 0);
}
@@ -658,12 +663,17 @@ void DAGCombiner::Run(CombineLevel AtLevel) {
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
AddToWorkList(N->getOperand(i).getNode());
// Nodes can be reintroduced into the worklist. Make sure we do not
// process a node that has been replaced.
removeFromWorkList(N);
// Finally, if the node is now dead, remove it from the graph. The node
// may not be dead if the replacement process recursively simplified to
// something else needing this node.
if (N->use_empty()) {
// Nodes can be reintroduced into the worklist. Make sure we do not
// process a node that has been replaced.
removeFromWorkList(N);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
}
}
// If the root changed (e.g. it was a dead load, update the root).