By popular demand: Slightly more honest typing in ClearNonLiveMapTransitions

src/mark-compact.cc

 // Copyright 2012 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 2350 matching lines @@
        i < number_of_transitions * step;
        i++) {
     prototype_transitions->set_undefined(heap_, header + i);
   }
 }
 
 
 void MarkCompactCollector::ClearNonLiveMapTransitions(Map* map,
                                                       MarkBit map_mark) {
   // Follow the chain of back pointers to find the prototype.
-  Map* real_prototype = map;
+  Object* real_prototype = map;
   while (real_prototype->IsMap()) {
-    real_prototype = reinterpret_cast<Map*>(real_prototype->prototype());
+    real_prototype = Map::cast(real_prototype)->prototype();
     ASSERT(real_prototype->IsHeapObject());
   }
 
   // Follow back pointers, setting them to prototype, clearing map transitions
   // when necessary.
   Map* current = map;
   bool current_is_alive = map_mark.Get();
   bool on_dead_path = !current_is_alive;
   while (current->IsMap()) {
     Object* next = current->prototype();
@@ skipping 1554 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal