[heap] Provide ObjectMarking with marking transitions

src/heap/scavenger.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/scavenger.h"
 
 #include "src/contexts.h"
 #include "src/heap/heap.h"
 #include "src/heap/objects-visiting-inl.h"
 #include "src/heap/scavenger-inl.h"
@@ skipping 175 matching lines @@
       MigrateObject(heap, object, target, object_size);
 
       // Update slot to new target using CAS. A concurrent sweeper thread my
       // filter the slot concurrently.
       HeapObject* old = *slot;
       base::Release_CompareAndSwap(reinterpret_cast<base::AtomicWord*>(slot),
                                    reinterpret_cast<base::AtomicWord>(old),
                                    reinterpret_cast<base::AtomicWord>(target));
 
       if (object_contents == POINTER_OBJECT) {
-        heap->promotion_queue()->insert(
-            target, object_size,
-            Marking::IsBlack(ObjectMarking::MarkBitFrom(object)));
+        heap->promotion_queue()->insert(target, object_size,
+                                        ObjectMarking::IsBlack(object));
       }
       heap->IncrementPromotedObjectsSize(object_size);
       return true;
     }
     return false;
   }
 
   template <ObjectContents object_contents, AllocationAlignment alignment>
   static inline void EvacuateObject(Map* map, HeapObject** slot,
                                     HeapObject* object, int object_size) {
@@ skipping 23 matching lines @@
   static inline void EvacuateJSFunction(Map* map, HeapObject** slot,
                                         HeapObject* object) {
     ObjectEvacuationStrategy<POINTER_OBJECT>::Visit(map, slot, object);
 
     if (marks_handling == IGNORE_MARKS) return;
 
     MapWord map_word = object->map_word();
     DCHECK(map_word.IsForwardingAddress());
     HeapObject* target = map_word.ToForwardingAddress();
 
-    MarkBit mark_bit = ObjectMarking::MarkBitFrom(target);
-    if (Marking::IsBlack(mark_bit)) {
+    if (ObjectMarking::IsBlack(target)) {
       // This object is black and it might not be rescanned by marker.
       // We should explicitly record code entry slot for compaction because
       // promotion queue processing (IteratePromotedObjectPointers) will
       // miss it as it is not HeapObject-tagged.
       Address code_entry_slot =
           target->address() + JSFunction::kCodeEntryOffset;
       Code* code = Code::cast(Code::GetObjectFromEntryAddress(code_entry_slot));
       map->GetHeap()->mark_compact_collector()->RecordCodeEntrySlot(
           target, code_entry_slot, code);
     }
@@ skipping 189 matching lines @@
 void ScavengeVisitor::ScavengePointer(Object** p) {
   Object* object = *p;
   if (!heap_->InNewSpace(object)) return;
 
   Scavenger::ScavengeObject(reinterpret_cast<HeapObject**>(p),
                             reinterpret_cast<HeapObject*>(object));
 }
 
 }  // namespace internal
 }  // namespace v8