Make objects embedded in optimized code weak.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 0455a84b8b6cd795e6e09b167e451a4048c0cc92..4bd11a8a93f5b6601610e489d6699eccad0e1601 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -6965,6 +6965,7 @@ bool Heap::CreateHeapObjects() {
   native_contexts_list_ = undefined_value();
   array_buffers_list_ = undefined_value();
   allocation_sites_list_ = undefined_value();
+  weak_object_to_code_ = undefined_value();
   return true;
 }
 
@@ -7108,6 +7109,27 @@ void Heap::RemoveGCEpilogueCallback(GCEpilogueCallback callback) {
 }
 
 
+MaybeObject* Heap::AddWeakObjectToCodeDependency(Object* obj,
+                                                 DependentCode* dep) {
+  ASSERT(!InNewSpace(obj));
+  ASSERT(!InNewSpace(dep));
+  MaybeObject* maybe_obj =
+      WeakHashTable::cast(weak_object_to_code_)->Put(obj, dep);
+  WeakHashTable* table;
+  if (!maybe_obj->To(&table)) return maybe_obj;
+  set_weak_object_to_code(table);
+  ASSERT_EQ(dep, WeakHashTable::cast(weak_object_to_code_)->Lookup(obj));
+  return weak_object_to_code_;
+}
+
+
+DependentCode* Heap::LookupWeakObjectToCodeDependency(Object* obj) {
+  Object* dep = WeakHashTable::cast(weak_object_to_code_)->Lookup(obj);
+  if (dep->IsDependentCode()) return DependentCode::cast(dep);
+  return DependentCode::cast(empty_fixed_array());
+}
+
+
 #ifdef DEBUG
 
 class PrintHandleVisitor: public ObjectVisitor {