Weak Cells

src/heap/objects-visiting-inl.h

Index: src/heap/objects-visiting-inl.h
diff --git a/src/heap/objects-visiting-inl.h b/src/heap/objects-visiting-inl.h
index d220118368e77d07b973ec92c701061ddf06b6a5..dcf8a9b02607508d75169d4740ab2321d27a309a 100644
--- a/src/heap/objects-visiting-inl.h
+++ b/src/heap/objects-visiting-inl.h
@@ -191,6 +191,8 @@ void StaticMarkingVisitor<StaticVisitor>::Initialize() {
 
   table_.Register(kVisitPropertyCell, &VisitPropertyCell);
 
+  table_.Register(kVisitWeakCell, &VisitWeakCell);
+
   table_.template RegisterSpecializations<DataObjectVisitor, kVisitDataObject,
                                           kVisitDataObjectGeneric>();
 
@@ -350,6 +352,22 @@ void StaticMarkingVisitor<StaticVisitor>::VisitPropertyCell(
 
 
 template <typename StaticVisitor>
+void StaticMarkingVisitor<StaticVisitor>::VisitWeakCell(Map* map,
+                                                        HeapObject* object) {
+  Heap* heap = map->GetHeap();
+  WeakCell* weak_cell = reinterpret_cast<WeakCell*>(object);
+  Object* undefined = heap->undefined_value();
+  // Enqueue weak cell in linked list of encountered weak collections.
+  // We can ignore weak cells with cleared values because they will always point
+  // to the undefined_value.
+  if (weak_cell->next() == undefined && weak_cell->value() != undefined) {
+    weak_cell->set_next(heap->encountered_weak_cells());
+    heap->set_encountered_weak_cells(weak_cell);
+  }
+}
+
+
+template <typename StaticVisitor>
 void StaticMarkingVisitor<StaticVisitor>::VisitAllocationSite(
     Map* map, HeapObject* object) {
   Heap* heap = map->GetHeap();