From 73b1ee857bb1022fbc72d983ef33a31b100013b9 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Thu, 3 Sep 2009 17:03:47 +0000
Subject: [PATCH] Use WeakVH to hold dead mdnodes. Check use_empty() before
 deleting a node.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80928 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/LLVMContext.cpp | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/VMCore/LLVMContext.cpp b/lib/VMCore/LLVMContext.cpp
index 0ed21fb754e..887679e08d3 100644
--- a/lib/VMCore/LLVMContext.cpp
+++ b/lib/VMCore/LLVMContext.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Constants.h"
 #include "llvm/Instruction.h"
 #include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/ValueHandle.h"
 #include "LLVMContextImpl.h"
 #include <set>
 
@@ -45,24 +46,25 @@ GetElementPtrConstantExpr::GetElementPtrConstantExpr
 }
 
 bool LLVMContext::RemoveDeadMetadata() {
-  std::vector<const MDNode *> DeadMDNodes;
+  std::vector<WeakVH> DeadMDNodes;
   bool Changed = false;
   while (1) {
 
     for (FoldingSet<MDNode>::iterator 
            I = pImpl->MDNodeSet.begin(),
            E = pImpl->MDNodeSet.end(); I != E; ++I) {
-      const MDNode *N = &(*I);
+      MDNode *N = &(*I);
       if (N->use_empty()) 
-        DeadMDNodes.push_back(N);
+        DeadMDNodes.push_back(WeakVH(N));
     }
     
     if (DeadMDNodes.empty())
       return Changed;
 
     while (!DeadMDNodes.empty()) {
-      const MDNode *N = DeadMDNodes.back(); DeadMDNodes.pop_back();
-      delete N;
+      const MDNode *N = cast<MDNode>(DeadMDNodes.back()); DeadMDNodes.pop_back();
+      if (N->use_empty())
+	delete N;
     }
   }
   return Changed;
-- 
2.11.0