1 files changed, 16 insertions, 6 deletions
diff --git a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
index 8fb9124a5f..02eeb3cc0a 100644
--- a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -532,17 +532,26 @@ void PromoteMem2Reg::run() {
 void PromoteMem2Reg::RewriteSingleStoreAlloca(AllocaInst *AI,
                                               AllocaInfo &Info) {
   StoreInst *OnlyStore = Info.OnlyStore;
+  bool StoringGlobalVal = !isa<Instruction>(OnlyStore->getOperand(0));
   
   // Be aware of loads before the store.
   SmallPtrSet<BasicBlock*, 32> ProcessedBlocks;
   for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i) {
-    // If the store dominates the block and if we haven't processed it yet,
-    // do so now.
-    if (!dominates(OnlyStore->getParent(), Info.UsingBlocks[i]))
+    BasicBlock *UseBlock = Info.UsingBlocks[i];
+    
+    // If we already processed this block, don't reprocess it.
+    if (!ProcessedBlocks.insert(UseBlock)) {
+      Info.UsingBlocks[i] = Info.UsingBlocks.back();
+      Info.UsingBlocks.pop_back();
+      --i; --e;
       continue;
+    }
     
-    BasicBlock *UseBlock = Info.UsingBlocks[i];
-    if (!ProcessedBlocks.insert(UseBlock))
+    // If the store dominates the block and if we haven't processed it yet,
+    // do so now.  We can't handle the case where the store doesn't dominate a
+    // block because there may be a path between the store and the use, but we
+    // may need to insert phi nodes to handle dominance properly.
+    if (StoringGlobalVal || !dominates(OnlyStore->getParent(), UseBlock))
       continue;
     
     // If the use and store are in the same block, do a quick scan to
@@ -553,7 +562,8 @@ void PromoteMem2Reg::RewriteSingleStoreAlloca(AllocaInst *AI,
         if (isa<LoadInst>(I) && I->getOperand(0) == AI)
           break;
       }
-      if (&*I != OnlyStore) break;  // Do not handle this case.
+      if (&*I != OnlyStore)
+        break;  // Do not handle this alloca.
     }
     
     // Otherwise, if this is a different block or if all uses happen