Simplify the write barrier.

src/incremental-marking.cc

 // Copyright 2011 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 205 matching lines @@
         MarkObject(obj);
       }
     }
   }
 
  private:
   // Mark object pointed to by p.
   INLINE(void MarkObject(Object* obj)) {
     HeapObject* heap_object = HeapObject::cast(obj);
     MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
-    if (mark_bit.data_only()) {
-      if (incremental_marking_->MarkBlackOrKeepGrey(mark_bit)) {
-        MemoryChunk::IncrementLiveBytes(heap_object->address(),
-                                        heap_object->Size());
-      }
-    } else if (Marking::IsWhite(mark_bit)) {
+    if (Marking::IsWhite(mark_bit)) {
       incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
     }
   }
 
   Heap* heap_;
   IncrementalMarking* incremental_marking_;
 };
 
 
 class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
@@ skipping 12 matching lines @@
     for (Object** p = start; p < end; p++) MarkObjectByPointer(p);
   }
 
  private:
   void MarkObjectByPointer(Object** p) {
     Object* obj = *p;
     if (!obj->IsHeapObject()) return;
 
     HeapObject* heap_object = HeapObject::cast(obj);
     MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
-    if (mark_bit.data_only()) {
-      if (incremental_marking_->MarkBlackOrKeepGrey(mark_bit)) {
-          MemoryChunk::IncrementLiveBytes(heap_object->address(),
-                                          heap_object->Size());
-      }
-    } else {
-      if (Marking::IsWhite(mark_bit)) {
-        incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
-      }
+    if (Marking::IsWhite(mark_bit)) {
+      incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
     }
   }
 
   Heap* heap_;
   IncrementalMarking* incremental_marking_;
 };
 
 
 void IncrementalMarking::SetOldSpacePageFlags(MemoryChunk* chunk,
                                               bool is_marking,
@@ skipping 628 matching lines @@
   allocation_marking_factor_ = kInitialAllocationMarkingFactor;
   bytes_scanned_ = 0;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSize();
 }
 
 } }  // namespace v8::internal