1 files changed, 19 insertions, 3 deletions
diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index 3daa45cec3..40d33d15af 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -19,8 +19,9 @@
 #include "llvm/Constant.h"
 #include "llvm/Type.h"
 #include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/DominanceFrontier.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/MemoryDependenceAnalysis.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Scalar.h"
@@ -63,12 +64,27 @@ void llvm::DeleteDeadBlock(BasicBlock *BB) {
 /// any single-entry PHI nodes in it, fold them away.  This handles the case
 /// when all entries to the PHI nodes in a block are guaranteed equal, such as
 /// when the block has exactly one predecessor.
-void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) {
+void llvm::FoldSingleEntryPHINodes(BasicBlock *BB, Pass *P) {
+  if (!isa<PHINode>(BB->begin())) return;
+  
+  AliasAnalysis *AA = 0;
+  MemoryDependenceAnalysis *MemDep = 0;
+  if (P) {
+    AA = P->getAnalysisIfAvailable<AliasAnalysis>();
+    MemDep = P->getAnalysisIfAvailable<MemoryDependenceAnalysis>();
+  }
+  
   while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
     if (PN->getIncomingValue(0) != PN)
       PN->replaceAllUsesWith(PN->getIncomingValue(0));
     else
       PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+    
+    if (MemDep)
+      MemDep->removeInstruction(PN);  // Memdep updates AA itself.
+    else if (AA && isa<PointerType>(PN->getType()))
+      AA->deleteValue(PN);
+    
     PN->eraseFromParent();
   }
 }
@@ -132,7 +148,7 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) {
 
   // Begin by getting rid of unneeded PHIs.
   if (isa<PHINode>(BB->front()))
-    FoldSingleEntryPHINodes(BB);
+    FoldSingleEntryPHINodes(BB, P);
   
   // Delete the unconditional branch from the predecessor...
   PredBB->getInstList().pop_back();