Improve crash recovery cleanup to recovery CompilerInstances during crash recovery. This was a huge resource "root" during crashes.

This change requires making a bunch of fundamental Clang structures (optionally) reference counted to allow correct
ownership semantics of these objects (e.g., ASTContext) to play out between an active ASTUnit and CompilerInstance
object.

llvm-svn: 128011

clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp

@@ -149,11 +149,8 @@ bool clang::ExecuteCompilerInvocation(CompilerInstance *Clang) {
   if (!Clang->getDiagnostics().hasErrorOccurred()) {
     // Create and execute the frontend action.
     llvm::OwningPtr<FrontendAction> Act(CreateFrontendAction(*Clang));
-    if (Act) {
+    if (Act)
       Success = Clang->ExecuteAction(*Act);
-      if (Clang->getFrontendOpts().DisableFree)
-        Act.take();
-    }
   }
 
   return Success;