- Pass the knowledge whether the old GC is compacting to the GC prologue and ...

src/mark-compact.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 56 matching lines @@
   // next live object in the same page.  For spaces using a different
   // encoding (ie, contiguous spaces), the offset parameter is ignored.
   typedef void (*EncodingFunction)(HeapObject* old_object,
                                    int object_size,
                                    Object* new_object,
                                    int* offset);
 
   // Type of functions to process non-live objects.
   typedef void (*ProcessNonLiveFunction)(HeapObject* object);
 
+  // Prepares for GC by resetting relocation info in old and map spaces and
+  // choosing spaces to compact.
+  static void Prepare(GCTracer* tracer);
+
   // Performs a global garbage collection.
-  static void CollectGarbage(GCTracer* tracer);
+  static void CollectGarbage();
 
   // True if the last full GC performed heap compaction.
   static bool HasCompacted() { return compacting_collection_; }
 
   // True after the Prepare phase if the compaction is taking place.
   static bool IsCompacting() { return compacting_collection_; }
 
   // The count of the number of objects left marked at the end of the last
   // completed full GC (expected to be zero).
   static int previous_marked_count() { return previous_marked_count_; }
@@ skipping 27 matching lines @@
   static bool compacting_collection_;
 
   // The number of objects left marked at the end of the last completed full
   // GC (expected to be zero).
   static int previous_marked_count_;
 
   // A pointer to the current stack-allocated GC tracer object during a full
   // collection (NULL before and after).
   static GCTracer* tracer_;
 
-  // Prepares for GC by resetting relocation info in old and map spaces and
-  // choosing spaces to compact.
-  static void Prepare();
-
   // Finishes GC, performs heap verification if enabled.
   static void Finish();
 
   // -----------------------------------------------------------------------
   // Phase 1: Marking live objects.
   //
   //  Before: The heap has been prepared for garbage collection by
   //          MarkCompactCollector::Prepare() and is otherwise in its
   //          normal state.
   //
@@ skipping 258 matching lines @@
 
   friend class UnmarkObjectVisitor;
   static void UnmarkObject(HeapObject* obj);
 #endif
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_