Implement a 2-pass heap verification algorithm.

runtime/vm/dart.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/dart.h"
 
 #include "vm/dart_api_state.h"
 #include "vm/flags.h"
 #include "vm/freelist.h"
 #include "vm/handles.h"
@@ skipping 15 matching lines @@
 
 Isolate* Dart::vm_isolate_ = NULL;
 ThreadPool* Dart::thread_pool_ = NULL;
 DebugInfo* Dart::pprof_symbol_generator_ = NULL;
 FileWriterFunction Dart::flow_graph_writer_ = NULL;
 
 // An object visitor which will mark all visited objects. This is used to
 // premark all objects in the vm_isolate_ heap.
 class PremarkingVisitor : public ObjectVisitor {
  public:
+  explicit PremarkingVisitor(Isolate* isolate) : ObjectVisitor(isolate) {}
+
   void VisitObject(RawObject* obj) {
     // RawInstruction objects are premarked on allocation.
     if (!obj->IsMarked()) {
       obj->SetMarkBit();
     }
   }
 };
 
 
 // TODO(turnidge): We should add a corresponding Dart::Cleanup.
@@ skipping 16 matching lines @@
     ASSERT(vm_isolate_ == NULL);
     ASSERT(Flags::Initialized());
     vm_isolate_ = Isolate::Init("vm-isolate");
     Zone zone(vm_isolate_);
     HandleScope handle_scope(vm_isolate_);
     Heap::Init(vm_isolate_);
     ObjectStore::Init(vm_isolate_);
     Object::InitOnce();
     StubCode::InitOnce();
     Scanner::InitOnce();
-    PremarkingVisitor premarker;
+    PremarkingVisitor premarker(vm_isolate_);
     vm_isolate_->heap()->IterateOldObjects(&premarker);
   }
   Isolate::SetCurrent(NULL);  // Unregister the VM isolate from this thread.
   Isolate::SetCreateCallback(create);
   Isolate::SetInterruptCallback(interrupt);
   return true;
 }
 
 
 Isolate* Dart::CreateIsolate(const char* name_prefix) {
@@ skipping 44 matching lines @@
 }
 
 
 void Dart::ShutdownIsolate() {
   Isolate* isolate = Isolate::Current();
   isolate->Shutdown();
   delete isolate;
 }
 
 }  // namespace dart