ES6: Implement WeakSet

src/mark-compact.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 55 matching lines @@
       abort_incremental_marking_(false),
       marking_parity_(ODD_MARKING_PARITY),
       compacting_(false),
       was_marked_incrementally_(false),
       sweeping_pending_(false),
       sequential_sweeping_(false),
       tracer_(NULL),
       migration_slots_buffer_(NULL),
       heap_(NULL),
       code_flusher_(NULL),
-      encountered_weak_maps_(NULL) { }
+      encountered_weak_collections_(NULL) { }
 
 
 #ifdef VERIFY_HEAP
 class VerifyMarkingVisitor: public ObjectVisitor {
  public:
   void VisitPointers(Object** start, Object** end) {
     for (Object** current = start; current < end; current++) {
       if ((*current)->IsHeapObject()) {
         HeapObject* object = HeapObject::cast(*current);
         CHECK(HEAP->mark_compact_collector()->IsMarked(object));
@@ skipping 302 matching lines @@
   }
 
   return compacting_;
 }
 
 
 void MarkCompactCollector::CollectGarbage() {
   // Make sure that Prepare() has been called. The individual steps below will
   // update the state as they proceed.
   ASSERT(state_ == PREPARE_GC);
-  ASSERT(encountered_weak_maps_ == Smi::FromInt(0));
+  ASSERT(encountered_weak_collections_ == Smi::FromInt(0));
 
   MarkLiveObjects();
   ASSERT(heap_->incremental_marking()->IsStopped());
 
   if (FLAG_collect_maps) ClearNonLiveReferences();
 
-  ClearWeakMaps();
+  ClearWeakCollections();
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyMarking(heap_);
   }
 #endif
 
   SweepSpaces();
 
   if (!FLAG_collect_maps) ReattachInitialMaps();
@@ skipping 1025 matching lines @@
       VisitUnmarkedObject(collector, obj);
     }
     return true;
   }
 
   INLINE(static void BeforeVisitingSharedFunctionInfo(HeapObject* object)) {
     SharedFunctionInfo* shared = SharedFunctionInfo::cast(object);
     shared->BeforeVisitingPointers();
   }
 
-  static void VisitJSWeakMap(Map* map, HeapObject* object) {
+  static void VisitWeakCollection(Map* map, HeapObject* object) {
     MarkCompactCollector* collector = map->GetHeap()->mark_compact_collector();
-    JSWeakMap* weak_map = reinterpret_cast<JSWeakMap*>(object);
+    WeakCollection* weak_collection = reinterpret_cast<WeakCollection*>(object);
 
     // Enqueue weak map in linked list of encountered weak maps.
-    if (weak_map->next() == Smi::FromInt(0)) {
-      weak_map->set_next(collector->encountered_weak_maps());
-      collector->set_encountered_weak_maps(weak_map);
+    if (weak_collection->next() == Smi::FromInt(0)) {
+      weak_collection->set_next(collector->encountered_weak_collections());
+      collector->set_encountered_weak_collections(weak_collection);
     }
 
     // Skip visiting the backing hash table containing the mappings.
-    int object_size = JSWeakMap::BodyDescriptor::SizeOf(map, object);
+    int object_size = WeakCollection::BodyDescriptor::SizeOf(map, object);
     BodyVisitorBase<MarkCompactMarkingVisitor>::IteratePointers(
         map->GetHeap(),
         object,
-        JSWeakMap::BodyDescriptor::kStartOffset,
-        JSWeakMap::kTableOffset);
+        WeakCollection::BodyDescriptor::kStartOffset,
+        WeakCollection::kTableOffset);
     BodyVisitorBase<MarkCompactMarkingVisitor>::IteratePointers(
         map->GetHeap(),
         object,
-        JSWeakMap::kTableOffset + kPointerSize,
+        WeakCollection::kTableOffset + kPointerSize,
         object_size);
 
     // Mark the backing hash table without pushing it on the marking stack.
-    Object* table_object = weak_map->table();
+    Object* table_object = weak_collection->table();
     if (!table_object->IsHashTable()) return;
     ObjectHashTable* table = ObjectHashTable::cast(table_object);
     Object** table_slot =
-        HeapObject::RawField(weak_map, JSWeakMap::kTableOffset);
+        HeapObject::RawField(weak_collection, WeakCollection::kTableOffset);
     MarkBit table_mark = Marking::MarkBitFrom(table);
     collector->RecordSlot(table_slot, table_slot, table);
     if (!table_mark.Get()) collector->SetMark(table, table_mark);
     // Recording the map slot can be skipped, because maps are not compacted.
     collector->MarkObject(table->map(), Marking::MarkBitFrom(table->map()));
     ASSERT(MarkCompactCollector::IsMarked(table->map()));
   }
 
  private:
   template<int id>
@@ skipping 747 matching lines @@
 
 // Mark all objects reachable (transitively) from objects on the marking
 // stack including references only considered in the atomic marking pause.
 void MarkCompactCollector::ProcessEphemeralMarking(ObjectVisitor* visitor) {
   bool work_to_do = true;
   ASSERT(marking_deque_.IsEmpty());
   while (work_to_do) {
     isolate()->global_handles()->IterateObjectGroups(
         visitor, &IsUnmarkedHeapObjectWithHeap);
     MarkImplicitRefGroups();
-    ProcessWeakMaps();
+    ProcessWeakCollections();
     work_to_do = !marking_deque_.IsEmpty();
     ProcessMarkingDeque();
   }
 }
 
 
 void MarkCompactCollector::ProcessTopOptimizedFrame(ObjectVisitor* visitor) {
   for (StackFrameIterator it(isolate(), isolate()->thread_local_top());
        !it.done(); it.Advance()) {
     if (it.frame()->type() == StackFrame::JAVA_SCRIPT) {
@@ skipping 388 matching lines @@
         static_cast<DependentCode::DependencyGroup>(g),
         group_number_of_entries);
     new_number_of_entries += group_number_of_entries;
   }
   for (int i = new_number_of_entries; i < number_of_entries; i++) {
     entries->clear_at(i);
   }
 }
 
 
-void MarkCompactCollector::ProcessWeakMaps() {
-  GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_WEAKMAP_PROCESS);
-  Object* weak_map_obj = encountered_weak_maps();
-  while (weak_map_obj != Smi::FromInt(0)) {
-    ASSERT(MarkCompactCollector::IsMarked(HeapObject::cast(weak_map_obj)));
-    JSWeakMap* weak_map = reinterpret_cast<JSWeakMap*>(weak_map_obj);
-    ObjectHashTable* table = ObjectHashTable::cast(weak_map->table());
+void MarkCompactCollector::ProcessWeakCollections() {
+  GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_WEAKCOLLECTION_PROCESS);
+  Object* weak_collection_obj = encountered_weak_collections();
+  while (weak_collection_obj != Smi::FromInt(0)) {
+    ASSERT(MarkCompactCollector::IsMarked(
+        HeapObject::cast(weak_collection_obj)));
+    WeakCollection* weak_collection =
+        reinterpret_cast<WeakCollection*>(weak_collection_obj);
+    ObjectHashTable* table = ObjectHashTable::cast(weak_collection->table());
     Object** anchor = reinterpret_cast<Object**>(table->address());
     for (int i = 0; i < table->Capacity(); i++) {
       if (MarkCompactCollector::IsMarked(HeapObject::cast(table->KeyAt(i)))) {
         Object** key_slot =
             HeapObject::RawField(table, FixedArray::OffsetOfElementAt(
                 ObjectHashTable::EntryToIndex(i)));
         RecordSlot(anchor, key_slot, *key_slot);
         Object** value_slot =
             HeapObject::RawField(table, FixedArray::OffsetOfElementAt(
                 ObjectHashTable::EntryToValueIndex(i)));
         MarkCompactMarkingVisitor::MarkObjectByPointer(
             this, anchor, value_slot);
       }
     }
-    weak_map_obj = weak_map->next();
+    weak_collection_obj = weak_collection->next();
   }
 }
 
 
-void MarkCompactCollector::ClearWeakMaps() {
-  GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_WEAKMAP_CLEAR);
-  Object* weak_map_obj = encountered_weak_maps();
-  while (weak_map_obj != Smi::FromInt(0)) {
-    ASSERT(MarkCompactCollector::IsMarked(HeapObject::cast(weak_map_obj)));
-    JSWeakMap* weak_map = reinterpret_cast<JSWeakMap*>(weak_map_obj);
-    ObjectHashTable* table = ObjectHashTable::cast(weak_map->table());
+void MarkCompactCollector::ClearWeakCollections() {
+  GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_WEAKCOLLECTION_CLEAR);
+  Object* weak_collection_obj = encountered_weak_collections();
+  while (weak_collection_obj != Smi::FromInt(0)) {
+    ASSERT(MarkCompactCollector::IsMarked(
+        HeapObject::cast(weak_collection_obj)));
+    WeakCollection* weak_collection =
+        reinterpret_cast<WeakCollection*>(weak_collection_obj);
+    ObjectHashTable* table = ObjectHashTable::cast(weak_collection->table());
     for (int i = 0; i < table->Capacity(); i++) {
       if (!MarkCompactCollector::IsMarked(HeapObject::cast(table->KeyAt(i)))) {
         table->RemoveEntry(i);
       }
     }
-    weak_map_obj = weak_map->next();
-    weak_map->set_next(Smi::FromInt(0));
+    weak_collection_obj = weak_collection->next();
+    weak_collection->set_next(Smi::FromInt(0));
   }
-  set_encountered_weak_maps(Smi::FromInt(0));
+  set_encountered_weak_collections(Smi::FromInt(0));
 }
 
 
 // We scavange new space simultaneously with sweeping. This is done in two
 // passes.
 //
 // The first pass migrates all alive objects from one semispace to another or
 // promotes them to old space.  Forwarding address is written directly into
 // first word of object without any encoding.  If object is dead we write
 // NULL as a forwarding address.
@@ skipping 1601 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal