Made iteration of global handles more efficient on scavenges.

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 575 matching lines @@
   // (unless reachable from another symbol).
   SymbolMarkingVisitor symbol_marker;
   symbol_table->IterateElements(&symbol_marker);
   ProcessMarkingStack(&marker);
 }
 
 
 void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) {
   // Mark the heap roots including global variables, stack variables,
   // etc., and all objects reachable from them.
-  Heap::IterateStrongRoots(visitor);
+  Heap::IterateStrongRoots(visitor, VISIT_ONLY_STRONG);
 
   // Handle the symbol table specially.
   MarkSymbolTable();
 
   // There may be overflowed objects in the heap.  Visit them now.
   while (marking_stack.overflowed()) {
     RefillMarkingStack();
     EmptyMarkingStack(visitor->stack_visitor());
   }
 }
@@ skipping 841 matching lines @@
   }
 };
 
 
 void MarkCompactCollector::UpdatePointers() {
 #ifdef DEBUG
   ASSERT(state_ == ENCODE_FORWARDING_ADDRESSES);
   state_ = UPDATE_POINTERS;
 #endif
   UpdatingVisitor updating_visitor;
-  Heap::IterateRoots(&updating_visitor);
+  Heap::IterateRoots(&updating_visitor, VISIT_ONLY_STRONG);
   GlobalHandles::IterateWeakRoots(&updating_visitor);
 
   int live_maps = IterateLiveObjects(Heap::map_space(),
                                      &UpdatePointersInOldObject);
   int live_pointer_olds = IterateLiveObjects(Heap::old_pointer_space(),
                                              &UpdatePointersInOldObject);
   int live_data_olds = IterateLiveObjects(Heap::old_data_space(),
                                           &UpdatePointersInOldObject);
   int live_codes = IterateLiveObjects(Heap::code_space(),
                                       &UpdatePointersInOldObject);
@@ skipping 338 matching lines @@
 
 void MarkCompactCollector::RebuildRSets() {
 #ifdef DEBUG
   ASSERT(state_ == RELOCATE_OBJECTS);
   state_ = REBUILD_RSETS;
 #endif
   Heap::RebuildRSets();
 }
 
 } }  // namespace v8::internal