More accurate usages of Heap::AdjustLiveBytes().

src/objects.cc

 // Copyright 2013 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/v8.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/api.h"
 #include "src/arguments.h"
@@ skipping 4566 matching lines @@
   // Copy the next enumeration index from instance descriptor.
   dictionary->SetNextEnumerationIndex(real_size + 1);
 
   // From here on we cannot fail and we shouldn't GC anymore.
   DisallowHeapAllocation no_allocation;
 
   // Resize the object in the heap if necessary.
   int new_instance_size = new_map->instance_size();
   int instance_size_delta = map->instance_size() - new_instance_size;
   ASSERT(instance_size_delta >= 0);
-  Heap* heap = isolate->heap();
-  heap->CreateFillerObjectAt(object->address() + new_instance_size,
-                             instance_size_delta);
-  heap->AdjustLiveBytes(object->address(),
-                        -instance_size_delta,
-                        Heap::FROM_MUTATOR);
+
+  if (instance_size_delta > 0) {
+    Heap* heap = isolate->heap();
+    heap->CreateFillerObjectAt(object->address() + new_instance_size,
+                               instance_size_delta);
+    heap->AdjustLiveBytes(object->address(), -instance_size_delta,
+                          Heap::FROM_MUTATOR);
+  }
 
   // We are storing the new map using release store after creating a filler for
   // the left-over space to avoid races with the sweeper thread.
   object->synchronized_set_map(*new_map);
 
   object->set_properties(*dictionary);
 
   isolate->counters()->props_to_dictionary()->Increment();
 
 #ifdef DEBUG
@@ skipping 12361 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal