Put empty pages discovered during sweeping to the end of the list of pages...

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 19 matching lines @@
 
 namespace v8 {
 namespace internal {
 
 // Callback function, returns whether an object is alive. The heap size
 // of the object is returned in size. It optionally updates the offset
 // to the first live object in the page (only used for old and map objects).
 typedef bool (*IsAliveFunction)(HeapObject* obj, int* size, int* offset);
 
 // Callback function for non-live blocks in the old generation.
-typedef void (*DeallocateFunction)(Address start, int size_in_bytes);
+// If add_to_freelist is false then just accounting stats are updated and
+// no attempt to add area to free list is made.
+typedef void (*DeallocateFunction)(Address start,
+                                   int size_in_bytes,
+                                   bool add_to_freelist);
 
 
 // Forward declarations.
 class RootMarkingVisitor;
 class MarkingVisitor;
 
 
 // -------------------------------------------------------------------------
 // Mark-Compact collector
 //
@@ skipping 255 matching lines @@
   static int IterateLiveObjects(NewSpace* space, HeapObjectCallback size_f);
   static int IterateLiveObjects(PagedSpace* space, HeapObjectCallback size_f);
 
   // Iterates the live objects between a range of addresses, returning the
   // number of live objects.
   static int IterateLiveObjectsInRange(Address start, Address end,
                                        HeapObjectCallback size_func);
 
   // Callback functions for deallocating non-live blocks in the old
   // generation.
-  static void DeallocateOldPointerBlock(Address start, int size_in_bytes);
-  static void DeallocateOldDataBlock(Address start, int size_in_bytes);
-  static void DeallocateCodeBlock(Address start, int size_in_bytes);
-  static void DeallocateMapBlock(Address start, int size_in_bytes);
-  static void DeallocateCellBlock(Address start, int size_in_bytes);
+  static void DeallocateOldPointerBlock(Address start,
+                                        int size_in_bytes,
+                                        bool add_to_freelist);
+
+  static void DeallocateOldDataBlock(Address start,
+                                     int size_in_bytes,
+                                     bool add_to_freelist);
+
+  static void DeallocateCodeBlock(Address start,
+                                  int size_in_bytes,
+                                  bool add_to_freelist);
+
+  static void DeallocateMapBlock(Address start,
+                                 int size_in_bytes,
+                                 bool add_to_freelist);
+
+  static void DeallocateCellBlock(Address start,
+                                  int size_in_bytes,
+                                  bool add_to_freelist);
 
   // If we are not compacting the heap, we simply sweep the spaces except
   // for the large object space, clearing mark bits and adding unmarked
   // regions to each space's free list.
   static void SweepSpaces();
 
   // -----------------------------------------------------------------------
   // Phase 3: Updating pointers in live objects.
   //
   //  Before: Same as after phase 2 (compacting collection).
@@ skipping 105 matching lines @@
 
   friend class UnmarkObjectVisitor;
   static void UnmarkObject(HeapObject* obj);
 #endif
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_