Implement a 2-pass heap verification algorithm.

runtime/vm/scavenger.h

 // 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.
 
 #ifndef VM_SCAVENGER_H_
 #define VM_SCAVENGER_H_
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
@@ skipping 56 matching lines @@
   uword* EndAddress() { return &end_; }
   static intptr_t top_offset() { return OFFSET_OF(Scavenger, top_); }
   static intptr_t end_offset() { return OFFSET_OF(Scavenger, end_); }
 
   intptr_t in_use() const { return (top_ - FirstObjectStart()); }
   intptr_t capacity() const { return space_->size(); }
 
   void VisitObjects(ObjectVisitor* visitor) const;
   void VisitObjectPointers(ObjectPointerVisitor* visitor) const;
 
+  void StartEndAddress(uword* start, uword* end) const {
+    *start = to_->start();
+    *end = to_->end();
+  }
+
   // Returns true if the last scavenge had a promotion failure.
   bool HadPromotionFailure() {
     return had_promotion_failure_;
   }
 
  private:
   uword FirstObjectStart() const { return to_->start() | object_alignment_; }
   void Prologue(Isolate* isolate, bool invoke_api_callbacks);
   void IterateRoots(Isolate* isolate,
                     ObjectPointerVisitor* visitor,
@@ skipping 56 matching lines @@
 
   friend class ScavengerVisitor;
   friend class ScavengerWeakVisitor;
 
   DISALLOW_COPY_AND_ASSIGN(Scavenger);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCAVENGER_H_