Print out how many AllocationMementos were found on a scavenge of new space

src/heap-inl.h

 // 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 507 matching lines @@
 
   // If the first word is a forwarding address, the object has already been
   // copied.
   if (first_word.IsForwardingAddress()) {
     HeapObject* dest = first_word.ToForwardingAddress();
     ASSERT(object->GetIsolate()->heap()->InFromSpace(*p));
     *p = dest;
     return;
   }
 
+  if (FLAG_trace_track_allocation_sites &&
+      AllocationSite::CanTrack(object->map()->instance_type()) &&
+      object->IsJSObject()) {
+    if (AllocationMemento::FindForJSObject(JSObject::cast(object)) != NULL) {
+      object->GetIsolate()->heap()->allocation_mementos_found_on_scavenge_++;
+    }
+  }
+
   // AllocationMementos are unrooted and shouldn't survive a scavenge
   ASSERT(object->map() != object->GetHeap()->allocation_memento_map());
   // Call the slow part of scavenge object.
   return ScavengeObjectSlow(p, object);
 }
 
 
 bool Heap::CollectGarbage(AllocationSpace space, const char* gc_reason) {
   const char* collector_reason = NULL;
   GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);
@@ skipping 343 matching lines @@
 #ifdef DEBUG
   Isolate* isolate = Isolate::Current();
   isolate->heap()->disallow_allocation_failure_ = old_state_;
 #endif
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_