- Implement a simple old-generation marker.

vm/gc_marker.h

Index: vm/gc_marker.h
===================================================================
--- vm/gc_marker.h	(revision 0)
+++ vm/gc_marker.h	(revision 0)
@@ -0,0 +1,39 @@
+// Copyright (c) 2011, 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.
+
+#ifndef VM_GC_MARKER_H_
+#define VM_GC_MARKER_H_
+
+#include "vm/allocation.h"
+
+namespace dart {
+
+// Forward declarations.
+class Heap;
+class Isolate;
+class MarkingVisitor;
+class PageSpace;
+
+// The class GCMarker is used to mark reachable old generation objects as part
+// of the mark-sweep collection. The marking bit used is defined in RawObject.
+class GCMarker : public ValueObject {
+ public:
+  explicit GCMarker(Heap* heap) : heap_(heap) { }
+  ~GCMarker() { }
+
+  void MarkObjects(Isolate* isolate, PageSpace* page_space);
+
+ private:
+  void Prologue(Isolate* isolate);
+  void IterateRoots(Isolate* isolate, MarkingVisitor* visitor);
+  void DrainMarkingStack(Isolate* isolate, MarkingVisitor* visitor);
+
+  Heap* heap_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(GCMarker);
+};
+
+}  // namespace dart
+
+#endif  // VM_GC_MARKER_H_