Force mark sweep if size of map space is to big to allow forward pointers enc...

src/mark-compact.cc

 // 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 98 matching lines @@
   ASSERT(state_ == IDLE);
   state_ = PREPARE_GC;
 #endif
   ASSERT(!FLAG_always_compact || !FLAG_never_compact);
 
   compacting_collection_ =
       FLAG_always_compact || force_compaction_ || compact_on_next_gc_;
   compact_on_next_gc_ = false;
 
   if (FLAG_never_compact) compacting_collection_ = false;
+  if (!Heap::map_space()->MapPointersEncodable())
+      compacting_collection_ = false;
   if (FLAG_collect_maps) CreateBackPointers();
 
 #ifdef DEBUG
   if (compacting_collection_) {
     // We will write bookkeeping information to the remembered set area
     // starting now.
     Page::set_rset_state(Page::NOT_IN_USE);
   }
 #endif
 
@@ skipping 1625 matching lines @@
 
 void MarkCompactCollector::RebuildRSets() {
 #ifdef DEBUG
   ASSERT(state_ == RELOCATE_OBJECTS);
   state_ = REBUILD_RSETS;
 #endif
   Heap::RebuildRSets();
 }
 
 } }  // namespace v8::internal