Make object groups and implicit references a bit more lightweight.

test/cctest/test-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 290 matching lines @@
 TEST(ObjectGroups) {
   GlobalHandles* global_handles = Isolate::Current()->global_handles();
   InitializeVM();
 
   NumberOfWeakCalls = 0;
   v8::HandleScope handle_scope;
 
   Handle<Object> g1s1 =
       global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   Handle<Object> g1s2 =
-    global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
+      global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   Handle<Object> g1c1 =
-    global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
+      global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   global_handles->MakeWeak(g1s1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g1s2.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g1c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
 
@@ skipping 18 matching lines @@
   // Connect group 1 and 2, make a cycle.
   Handle<FixedArray>::cast(g1s2)->set(0, *g2s2);
   Handle<FixedArray>::cast(g2s1)->set(0, *g1s1);
 
   {
     Object** g1_objects[] = { g1s1.location(), g1s2.location() };
     Object** g1_children[] = { g1c1.location() };
     Object** g2_objects[] = { g2s1.location(), g2s2.location() };
     Object** g2_children[] = { g2c1.location() };
     global_handles->AddObjectGroup(g1_objects, 2, NULL);
-    global_handles->AddImplicitReferences(HeapObject::cast(*g1s1),
-                                          g1_children, 1);
+    global_handles->AddImplicitReferences(
+        Handle<HeapObject>::cast(g1s1).location(), g1_children, 1);
     global_handles->AddObjectGroup(g2_objects, 2, NULL);
-    global_handles->AddImplicitReferences(HeapObject::cast(*g2s2),
-                                          g2_children, 1);
+    global_handles->AddImplicitReferences(
+        Handle<HeapObject>::cast(g2s2).location(), g2_children, 1);
   }
   // Do a full GC
   HEAP->CollectGarbage(OLD_POINTER_SPACE);
 
   // All object should be alive.
   CHECK_EQ(0, NumberOfWeakCalls);
 
   // Weaken the root.
   global_handles->MakeWeak(root.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   // But make children strong roots---all the objects (except for children)
   // should be collectable now.
   global_handles->ClearWeakness(g1c1.location());
   global_handles->ClearWeakness(g2c1.location());
 
   // Groups are deleted, rebuild groups.
   {
     Object** g1_objects[] = { g1s1.location(), g1s2.location() };
     Object** g1_children[] = { g1c1.location() };
     Object** g2_objects[] = { g2s1.location(), g2s2.location() };
     Object** g2_children[] = { g2c1.location() };
     global_handles->AddObjectGroup(g1_objects, 2, NULL);
-    global_handles->AddImplicitReferences(HeapObject::cast(*g1s1),
-                                         g1_children, 1);
+    global_handles->AddImplicitReferences(
+        Handle<HeapObject>::cast(g1s1).location(), g1_children, 1);
     global_handles->AddObjectGroup(g2_objects, 2, NULL);
-    global_handles->AddImplicitReferences(HeapObject::cast(*g2s2),
-                                         g2_children, 1);
+    global_handles->AddImplicitReferences(
+        Handle<HeapObject>::cast(g2s2).location(), g2_children, 1);
   }
 
   HEAP->CollectGarbage(OLD_POINTER_SPACE);
 
   // All objects should be gone. 5 global handles in total.
   CHECK_EQ(5, NumberOfWeakCalls);
 
   // And now make children weak again and collect them.
   global_handles->MakeWeak(g1c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g2c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
 
   HEAP->CollectGarbage(OLD_POINTER_SPACE);
   CHECK_EQ(7, NumberOfWeakCalls);
 }