Clear Map::constructor to object_function from the same context for prototype maps. This avoids kee…

src/objects.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
@@ skipping 9958 matching lines @@
   if (!object->HasFastProperties()) {
     JSObject::MigrateSlowToFast(object, 0, "OptimizeAsPrototype");
     has_just_copied_map = true;
   }
   if (mode == FAST_PROTOTYPE && object->HasFastProperties() &&
       !object->map()->is_prototype_map()) {
     if (!has_just_copied_map) {
       Handle<Map> new_map = Map::Copy(handle(object->map()), "CopyAsPrototype");
       JSObject::MigrateToMap(object, new_map);
     }
+    if (object->map()->constructor()->IsJSFunction()) {
+      JSFunction* constructor = JSFunction::cast(object->map()->constructor());
+      // Replace the pointer to the exact constructor with the Object function
+      // from the same context if undetectable from JS. This is to avoid keeping
+      // memory alive unnecessarily.
+      if (!constructor->shared()->IsApiFunction() &&
+          object->class_name() ==
+              object->GetIsolate()->heap()->Object_string()) {
+        Context* context = constructor->context()->native_context();
+        JSFunction* object_function = context->object_function();
+        object->map()->set_constructor(object_function);
+      }
+    }
     object->map()->set_is_prototype_map(true);
   }
 }
 
 
 void JSObject::ReoptimizeIfPrototype(Handle<JSObject> object) {
   if (!object->map()->is_prototype_map()) return;
   OptimizeAsPrototype(object, FAST_PROTOTYPE);
 }
 
@@ skipping 7211 matching lines @@
                                                CompilationInfo* info) {
   Handle<DependentCode> codes = DependentCode::InsertCompilationInfo(
       handle(cell->dependent_code(), info->isolate()),
       DependentCode::kPropertyCellChangedGroup, info->object_wrapper());
   if (*codes != cell->dependent_code()) cell->set_dependent_code(*codes);
   info->dependencies(DependentCode::kPropertyCellChangedGroup)->Add(
       cell, info->zone());
 }
 
 } }  // namespace v8::internal