- Remember objects (not addresses) in the old generation containing new pointers.

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 <map>
 
 #include "platform/assert.h"
@@ skipping 87 matching lines @@
  private:
   // Ids for time and data records in Heap::GCStats.
   enum {
     // Time
     kVisitIsolateRoots = 0,
     kIterateStoreBuffers = 1,
     kProcessToSpace = 2,
     kIterateWeaks = 3,
     // Data
     kStoreBufferEntries = 0,
-    kStoreBufferDuplicates = 1,
-    kStoreBufferBlockEntries = 2,
-    kStoreBufferBlockDuplicates = 3
+    kStoreBufferBlockEntries = 1
   };
 
   uword FirstObjectStart() const { return to_->start() | object_alignment_; }
   void Prologue(Isolate* isolate, bool invoke_api_callbacks);
   void IterateStoreBuffers(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateRoots(Isolate* isolate,
                     ScavengerVisitor* visitor,
                     bool visit_prologue_weak_persistent_handles);
   void IterateWeakProperties(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateWeakReferences(Isolate* isolate, ScavengerVisitor* visitor);
@@ skipping 59 matching lines @@
 
   friend class ScavengerVisitor;
   friend class ScavengerWeakVisitor;
 
   DISALLOW_COPY_AND_ASSIGN(Scavenger);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCAVENGER_H_