Access old space marking bits from runtime only when incremental marking is in MARKING state.

src/runtime.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 4107 matching lines @@
 
   // Shorten string and fill
   int string_size = ResultSeqString::SizeFor(position);
   int allocated_string_size = ResultSeqString::SizeFor(new_length);
   int delta = allocated_string_size - string_size;
 
   answer->set_length(position);
   if (delta == 0) return *answer;
 
   Address end_of_string = answer->address() + string_size;
-  isolate->heap()->CreateFillerObjectAt(end_of_string, delta);
-  if (Marking::IsBlack(Marking::MarkBitFrom(*answer))) {
-    MemoryChunk::IncrementLiveBytesFromMutator(answer->address(), -delta);
-  }
-
+  Heap* heap = isolate->heap();
+  heap->CreateFillerObjectAt(end_of_string, delta);
+  heap->AdjustLiveBytes(answer->address(), -delta, Heap::FROM_MUTATOR);
   return *answer;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_StringReplaceGlobalRegExpWithString) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 4);
 
   CONVERT_ARG_HANDLE_CHECKED(String, subject, 0);
   CONVERT_ARG_HANDLE_CHECKED(String, replacement, 2);
@@ skipping 10876 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal