Use body descriptor to update pointers from cells.

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 3400 matching lines @@
   }
 
   GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_UPDATE_MISC_POINTERS);
 
   // Update pointers from cells.
   HeapObjectIterator cell_iterator(heap_->cell_space());
   for (HeapObject* cell = cell_iterator.Next();
        cell != NULL;
        cell = cell_iterator.Next()) {
     if (cell->IsCell()) {
-      Address value_address = reinterpret_cast<Address>(cell) +
-          (Cell::kValueOffset - kHeapObjectTag);
-      updating_visitor.VisitPointer(reinterpret_cast<Object**>(value_address));
+      Cell::BodyDescriptor::IterateBody(cell, &updating_visitor);
     }
   }
 
-  HeapObjectIterator js_global_property_cell_iterator(
-      heap_->property_cell_space());
-  for (HeapObject* cell = js_global_property_cell_iterator.Next();
+  HeapObjectIterator property_cell_iterator(heap_->property_cell_space());
+  for (HeapObject* cell = property_cell_iterator.Next();
        cell != NULL;
-       cell = js_global_property_cell_iterator.Next()) {
+       cell = property_cell_iterator.Next()) {
     if (cell->IsPropertyCell()) {
-      Address value_address =
-          reinterpret_cast<Address>(cell) +
-          (PropertyCell::kValueOffset - kHeapObjectTag);
-      updating_visitor.VisitPointer(reinterpret_cast<Object**>(value_address));
-      Address type_address =
-          reinterpret_cast<Address>(cell) +
-          (PropertyCell::kTypeOffset - kHeapObjectTag);
-      updating_visitor.VisitPointer(reinterpret_cast<Object**>(type_address));
+      PropertyCell::BodyDescriptor::IterateBody(cell, &updating_visitor);
     }
   }
 
   // Update pointer from the native contexts list.
   updating_visitor.VisitPointer(heap_->native_contexts_list_address());
 
   heap_->string_table()->Iterate(&updating_visitor);
 
   // Update pointers from external string table.
   heap_->UpdateReferencesInExternalStringTable(
@@ skipping 864 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal