Use slot instead of value in the write barrier to record write from code.

src/incremental-marking.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 60 matching lines @@
     if (Marking::IsBlack(obj_bit)) {
       // Object is not going to be rescanned we need to record the slot.
       heap_->mark_compact_collector()->RecordSlot(
           HeapObject::RawField(obj, 0), slot, value);
     }
   }
 }
 
 
 void IncrementalMarking::RecordWriteFromCode(HeapObject* obj,
-                                             Object* value,
+                                             Object** slot,
                                              Isolate* isolate) {
   ASSERT(obj->IsHeapObject());
   IncrementalMarking* marking = isolate->heap()->incremental_marking();
   ASSERT(!marking->is_compacting_);
 
   MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
   int counter = chunk->write_barrier_counter();
   if (counter < (MemoryChunk::kWriteBarrierCounterGranularity / 2)) {
     marking->write_barriers_invoked_since_last_step_ +=
         MemoryChunk::kWriteBarrierCounterGranularity -
             chunk->write_barrier_counter();
     chunk->set_write_barrier_counter(
         MemoryChunk::kWriteBarrierCounterGranularity);
   }
 
-  marking->RecordWrite(obj, NULL, value);
+  marking->RecordWrite(obj, slot, *slot);
 }
 
 
 void IncrementalMarking::RecordWriteForEvacuationFromCode(HeapObject* obj,
                                                           Object** slot,
                                                           Isolate* isolate) {
   ASSERT(obj->IsHeapObject());
   IncrementalMarking* marking = isolate->heap()->incremental_marking();
   ASSERT(marking->is_compacting_);
 
@@ skipping 888 matching lines @@
   bytes_scanned_ = 0;
   write_barriers_invoked_since_last_step_ = 0;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
 }
 
 } }  // namespace v8::internal