Fix a bug in the DAGCombiner's handling of multiple linked

[oota-llvm.git] / lib / CodeGen / SelectionDAG / DAGCombiner.cpp

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 42d163f79b1136d405c10e8585a74e0c969d9621..d4d13884cb0c3c6da90e4172b5af151dd9326331 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -924,9 +924,14 @@ SDValue DAGCombiner::visitTokenFactor(SDNode *N) {
 /// MERGE_VALUES can always be eliminated.
 SDValue DAGCombiner::visitMERGE_VALUES(SDNode *N) {
   WorkListRemover DeadNodes(*this);
-  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
-    DAG.ReplaceAllUsesOfValueWith(SDValue(N, i), N->getOperand(i),
-                                  &DeadNodes);
+  // Replacing results may cause a different MERGE_VALUES to suddenly
+  // be CSE'd with N, and carry its uses with it. Iterate until no
+  // uses remain, to ensure that the node can be safely deleted.
+  do {
+    for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+      DAG.ReplaceAllUsesOfValueWith(SDValue(N, i), N->getOperand(i),
+                                    &DeadNodes);
+  } while (!N->use_empty());
   removeFromWorkList(N);
   DAG.DeleteNode(N);
   return SDValue(N, 0);   // Return N so it doesn't get rechecked!