Remove dead metadata.

llvm-svn: 78651

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/VMCore/LLVMContext.cpp b/llvm/lib/VMCore/LLVMContext.cpp
index 22882711a06..3ca1b0afca4 100644
--- a/llvm/lib/VMCore/LLVMContext.cpp
+++ b/llvm/lib/VMCore/LLVMContext.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Support/ManagedStatic.h"
 #include "LLVMContextImpl.h"
 #include <cstdarg>
+#include <set>
 
 using namespace llvm;
 
@@ -44,3 +45,27 @@ GetElementPtrConstantExpr::GetElementPtrConstantExpr
   for (unsigned i = 0, E = IdxList.size(); i != E; ++i)
     OperandList[i+1] = IdxList[i];
 }
+
+bool LLVMContext::RemoveDeadMetadata() {
+  std::vector<const MDNode *> DeadMDNodes;
+  bool Changed = false;
+  while (1) {
+
+    for (LLVMContextImpl::MDNodeMapTy::MapTy::iterator
+           I = pImpl->MDNodes.map_begin(),
+           E = pImpl->MDNodes.map_end(); I != E; ++I) {
+      const MDNode *N = cast<MDNode>(I->second);
+      if (N->use_empty()) 
+        DeadMDNodes.push_back(N);
+    }
+    
+    if (DeadMDNodes.empty())
+      return Changed;
+
+    while (!DeadMDNodes.empty()) {
+      const MDNode *N = DeadMDNodes.back(); DeadMDNodes.pop_back();
+      delete N;
+    }
+  }
+  return Changed;
+}