Do not store DIDescriptor directly into a container. Store MDNode directly, through TrackingVH.

llvm-svn: 88677
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index ffb1af4..af86e2b 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -56,7 +56,7 @@
   bool BlockLiteralGenericSet;
   llvm::DIType BlockLiteralGeneric;
 
-  std::vector<llvm::DIDescriptor> RegionStack;
+  std::vector<llvm::TrackingVH<llvm::MDNode> > RegionStack;
 
   /// Helper functions for getOrCreateType.
   llvm::DIType CreateType(const BuiltinType *Ty, llvm::DICompileUnit U);