HeapProfiler: for the test purposes we would like to trace object movements.

src/builtins.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 255 matching lines @@
   former_start[new_start_index + 1] = Smi::FromInt(len - to_trim);
 
   // Maintain marking consistency for HeapObjectIterator and
   // IncrementalMarking.
   int size_delta = to_trim * entry_size;
   if (heap->marking()->TransferMark(elms->address(),
                                     elms->address() + size_delta)) {
     MemoryChunk::IncrementLiveBytesFromMutator(elms->address(), -size_delta);
   }
 
+  FixedArrayBase* new_elms = FixedArrayBase::cast(HeapObject::FromAddress(
+      elms->address() + size_delta));
   HeapProfiler* profiler = heap->isolate()->heap_profiler();
   if (profiler->is_profiling()) {
     profiler->ObjectMoveEvent(elms->address(),
-                              elms->address() + size_delta,
-                              elms->Size());
+                              new_elms->address(),
+                              new_elms->Size());
   }
-  return FixedArrayBase::cast(HeapObject::FromAddress(
-      elms->address() + to_trim * entry_size));
+  return new_elms;
 }
 
 
 static bool ArrayPrototypeHasNoElements(Heap* heap,
                                         Context* native_context,
                                         JSObject* array_proto) {
   // This method depends on non writability of Object and Array prototype
   // fields.
   if (array_proto->elements() != heap->empty_fixed_array()) return false;
   // Object.prototype
@@ skipping 1521 matching lines @@
 }
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 } }  // namespace v8::internal