Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/objects.cc

 // Copyright 2013 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 2211 matching lines @@
   elms->set_length(len - to_trim);
 
   // Maintain marking consistency for IncrementalMarking.
   if (Marking::IsBlack(Marking::MarkBitFrom(elms))) {
     if (trim_mode == FROM_GC) {
       MemoryChunk::IncrementLiveBytesFromGC(elms->address(), -size_delta);
     } else {
       MemoryChunk::IncrementLiveBytesFromMutator(elms->address(), -size_delta);
     }
   }
+
+  // The array may not be moved during GC,
+  // and size has to be adjusted nevertheless.
+  HeapProfiler* profiler = heap->isolate()->heap_profiler();
+  if (profiler->is_tracking_allocations()) {
+    profiler->UpdateObjectSizeEvent(elms->address(), elms->Size());
+  }
 }
 
 
 bool Map::InstancesNeedRewriting(Map* target,
                                  int target_number_of_fields,
                                  int target_inobject,
                                  int target_unused) {
   // If fields were added (or removed), rewrite the instance.
   int number_of_fields = NumberOfFields();
   ASSERT(target_number_of_fields >= number_of_fields);
@@ skipping 13836 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