[heap] Add basic infrastructure for incremental wrapper tracing.

src/heap/mark-compact.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 2205 matching lines @@
       js_object->GetInternalField(0) &&
       js_object->GetInternalField(0) != heap_->undefined_value() &&
       js_object->GetInternalField(1) != heap_->undefined_value()) {
     DCHECK(reinterpret_cast<intptr_t>(js_object->GetInternalField(0)) % 2 == 0);
     wrappers_to_trace_.push_back(std::pair<void*, void*>(
         reinterpret_cast<void*>(js_object->GetInternalField(0)),
         reinterpret_cast<void*>(js_object->GetInternalField(1))));
   }
 }
 
-void MarkCompactCollector::RegisterExternallyReferencedObject(Object** object) {
-  DCHECK(in_use());
-  HeapObject* heap_object = HeapObject::cast(*object);
-  DCHECK(heap_->Contains(heap_object));
-  MarkBit mark_bit = ObjectMarking::MarkBitFrom(heap_object);
-  MarkObject(heap_object, mark_bit);
-}
-
 class MarkCompactCollector::ObjectStatsVisitor
     : public MarkCompactCollector::HeapObjectVisitor {
  public:
   ObjectStatsVisitor(Heap* heap, ObjectStats* live_stats,
                      ObjectStats* dead_stats)
       : live_collector_(heap, live_stats), dead_collector_(heap, dead_stats) {
     DCHECK_NOT_NULL(live_stats);
     DCHECK_NOT_NULL(dead_stats);
     // Global objects are roots and thus recorded as live.
     live_collector_.CollectGlobalStatistics();
@@ skipping 1793 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8