Bookkeeping for allocation site pretenuring

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 5697 matching lines @@
 
   // The returned handle will be used for the object in all
   // subsequent usages. This allows VisitObject to make a copy
   // of the object if desired.
   virtual Handle<JSObject> VisitObject(Handle<JSObject> object) V8_OVERRIDE {
     // Only create a memento if
     // 1) we have a JSArray, and
     // 2) the elements kind is palatable
     // 3) allow_mementos is true
     Handle<JSObject> copy;
-    if (site_context()->activated() &&
-        AllocationSite::CanTrack(object->map()->instance_type()) &&
-        AllocationSite::GetMode(object->GetElementsKind()) ==
-        TRACK_ALLOCATION_SITE) {
+    if (site_context()->ShouldCreateMemento(object)) {
       copy = JSObject::Copy(object, site_context()->current());
     } else {
       copy = JSObject::Copy(object);
     }
 
     return copy;
   }
 
   virtual Handle<JSObject> VisitElementOrProperty(
       Handle<JSObject> object,
@@ skipping 3474 matching lines @@
   }
 
 
   if (new_length == 0) return heap->isolate()->factory()->empty_string();
   return string;
 }
 
 
 AllocationMemento* AllocationMemento::FindForJSObject(JSObject* object,
                                                       bool in_GC) {
   // Currently, AllocationMemento objects are only allocated immediately

[Hannes Payer (out of office), 2013/11/27 10:51:37]

Please update this comment.

[mvstanton, 2013/11/27 13:27:58]

Done.

   // after JSArrays in NewSpace, and detecting whether a JSArray has one
   // involves carefully checking the object immediately after the JSArray
   // (if there is one) to see if it's an AllocationMemento.
   if (FLAG_track_allocation_sites && object->GetHeap()->InNewSpace(object)) {
     Address ptr_end = (reinterpret_cast<Address>(object) - kHeapObjectTag) +
         object->Size();
     Address top;
     if (in_GC) {
       top = object->GetHeap()->new_space()->FromSpacePageHigh();
     } else {
       top = object->GetHeap()->NewSpaceTop();
     }
     if ((ptr_end + AllocationMemento::kSize) <= top) {
       // There is room in newspace for allocation info. Do we have some?
       Map** possible_allocation_memento_map =
           reinterpret_cast<Map**>(ptr_end);
       if (*possible_allocation_memento_map ==
           object->GetHeap()->allocation_memento_map()) {
         AllocationMemento* memento = AllocationMemento::cast(
             reinterpret_cast<Object*>(ptr_end + kHeapObjectTag));
-        return memento;
+        if (memento->IsValid()) {
+          return memento;
+        }
       }
     }
   }
   return NULL;
 }
 
 
 uint32_t StringHasher::MakeArrayIndexHash(uint32_t value, int length) {
   // For array indexes mix the length into the hash as an array index could
   // be zero.
@@ skipping 3555 matching lines @@
 }
 
 
 void JSObject::TransitionElementsKind(Handle<JSObject> object,
                                       ElementsKind to_kind) {
   CALL_HEAP_FUNCTION_VOID(object->GetIsolate(),
                           object->TransitionElementsKind(to_kind));
 }
 
 
+const double AllocationSite::kPretenureRatio = 0.60;
+
+
 bool AllocationSite::IsNestedSite() {
   ASSERT(FLAG_trace_track_allocation_sites);
   Object* current = GetHeap()->allocation_sites_list();
   while (current != NULL && current->IsAllocationSite()) {
     AllocationSite* current_site = AllocationSite::cast(current);
     if (current_site->nested_site() == this) {
       return true;
     }
     current = current_site->weak_next();
   }
@@ skipping 3850 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