Handle DAG CSE adding new uses during ReplaceAllUsesWith. Fixes PR14333.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167912 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 5416a5c..37d7731 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7728,7 +7728,18 @@
if (StoreNodes[i].MemNode == EarliestOp)
continue;
StoreSDNode *St = cast<StoreSDNode>(StoreNodes[i].MemNode);
- DAG.ReplaceAllUsesOfValueWith(SDValue(St, 0), St->getChain());
+ // ReplaceAllUsesWith will replace all uses that existed when it was
+ // called, but graph optimizations may cause new ones to appear. For
+ // example, the case in pr14333 looks like
+ //
+ // St's chain -> St -> another store -> X
+ //
+ // And the only difference from St to the other store is the chain.
+ // When we change it's chain to be St's chain they become identical,
+ // get CSEed and the net result is that X is now a use of St.
+ // Since we know that St is redundant, just iterate.
+ while (!St->use_empty())
+ DAG.ReplaceAllUsesWith(SDValue(St, 0), St->getChain());
removeFromWorkList(St);
DAG.DeleteNode(St);
}