1 files changed, 13 insertions, 2 deletions
diff --git a/lib/VMCore/Module.cpp b/lib/VMCore/Module.cpp
index fe9b828b2b..275d4cfbf3 100644
--- a/lib/VMCore/Module.cpp
+++ b/lib/VMCore/Module.cpp
@@ -250,6 +250,7 @@ void Module::destroyConstantPointerRef(ConstantPointerRef *CPR) {
 }
 
 void Module::mutateConstantPointerRef(GlobalValue *OldGV, GlobalValue *NewGV) {
+  assert(OldGV != NewGV && "Cannot mutate to the same global!");
   GlobalValueRefMap::iterator I = GVRefMap->Map.find(OldGV);
   assert(I != GVRefMap->Map.end() && 
 	 "mutateConstantPointerRef; OldGV not in table!");
@@ -258,6 +259,16 @@ void Module::mutateConstantPointerRef(GlobalValue *OldGV, GlobalValue *NewGV) {
   // Remove the old entry...
   GVRefMap->Map.erase(I);
 
-  // Insert the new entry...
-  GVRefMap->Map.insert(std::make_pair(NewGV, Ref));
+  // Check to see if a CPR already exists for NewGV
+  I = GVRefMap->Map.lower_bound(NewGV);
+
+  if (I == GVRefMap->Map.end() || I->first != NewGV) {
+    // Insert the new entry...
+    GVRefMap->Map.insert(I, std::make_pair(NewGV, Ref));
+  } else {
+    // Otherwise, an entry already exists for the current global value.
+    // Completely replace the old CPR with the existing one...
+    Ref->replaceAllUsesWith(I->second);
+    delete Ref;
+  }
 }