Fix a problem Nate and Duraid reported where simplifying nodes can cause
them to get ressurected, in which case, deleting the undead nodes is
unfriendly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26291 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index bdb32ed..ad09869 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -120,18 +120,22 @@
std::vector<SDNode*> NowDead;
DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New, NowDead);
- // Push the new node and any (now) users onto the worklist.
+ // Push the new node and any (possibly new) users onto the worklist.
WorkList.push_back(TLO.New.Val);
AddUsersToWorkList(TLO.New.Val);
// Nodes can end up on the worklist more than once. Make sure we do
// not process a node that has been replaced.
- removeFromWorkList(TLO.Old.Val);
for (unsigned i = 0, e = NowDead.size(); i != e; ++i)
removeFromWorkList(NowDead[i]);
- // Finally, since the node is now dead, remove it from the graph.
- DAG.DeleteNode(TLO.Old.Val);
+ // 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 (TLO.Old.Val->use_empty()) {
+ removeFromWorkList(TLO.Old.Val);
+ DAG.DeleteNode(TLO.Old.Val);
+ }
return true;
}