[keys] keep track of first and last non-empty prototype

src/keys.h

 // Copyright 2012 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.
 
 #ifndef V8_KEYS_H_
 #define V8_KEYS_H_
 
 #include "src/isolate.h"
 #include "src/objects.h"
 
@@ skipping 21 matching lines @@
 class KeyAccumulator final BASE_EMBEDDED {
  public:
   KeyAccumulator(Isolate* isolate, KeyCollectionMode mode,
                  PropertyFilter filter)
       : isolate_(isolate), mode_(mode), filter_(filter) {}
   ~KeyAccumulator();
 
   static MaybeHandle<FixedArray> GetKeys(
       Handle<JSReceiver> object, KeyCollectionMode mode, PropertyFilter filter,
       GetKeysConversion keys_conversion = GetKeysConversion::kKeepNumbers,
-      bool filter_proxy_keys = true, bool is_for_in = false);
+      bool filter_proxy_keys = true, bool is_for_in = false,
+      JSReceiver* first_non_empty_prototype = nullptr,
+      JSReceiver* last_non_empty_prototype = nullptr);
   Handle<FixedArray> GetKeys(
       GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
   Maybe<bool> CollectKeys(Handle<JSReceiver> receiver,
                           Handle<JSReceiver> object);
   Maybe<bool> CollectOwnElementIndices(Handle<JSReceiver> receiver,
                                        Handle<JSObject> object);
   Maybe<bool> CollectOwnPropertyNames(Handle<JSReceiver> receiver,
                                       Handle<JSObject> object);
 
   static Handle<FixedArray> GetEnumPropertyKeys(Isolate* isolate,
                                                 Handle<JSObject> object);
 
   void AddKey(Object* key, AddKeyConversion convert = DO_NOT_CONVERT);
   void AddKey(Handle<Object> key, AddKeyConversion convert = DO_NOT_CONVERT);
   void AddKeys(Handle<FixedArray> array, AddKeyConversion convert);
   void AddKeys(Handle<JSObject> array_like, AddKeyConversion convert);
 
   // Jump to the next level, pushing the current |levelLength_| to
   // |levelLengths_| and adding a new list to |elements_|.
   Isolate* isolate() { return isolate_; }
   PropertyFilter filter() { return filter_; }
   void set_filter_proxy_keys(bool filter) { filter_proxy_keys_ = filter; }
   void set_is_for_in(bool value) { is_for_in_ = value; }
   void set_skip_indices(bool value) { skip_indices_ = value; }
+  void set_first_non_empty_prototype(JSReceiver* object) {
+    first_non_empty_prototype_ = handle(object, isolate_);
+  }
+  void set_last_non_empty_prototype(JSReceiver* object) {
+    last_non_empty_prototype_ = handle(object, isolate_);
+  }
 
  private:
   Maybe<bool> CollectOwnKeys(Handle<JSReceiver> receiver,
                              Handle<JSObject> object);
   Maybe<bool> CollectOwnJSProxyKeys(Handle<JSReceiver> receiver,
                                     Handle<JSProxy> proxy);
   Maybe<bool> CollectOwnJSProxyTargetKeys(Handle<JSProxy> proxy,
                                           Handle<JSReceiver> target);
 
   Maybe<bool> AddKeysFromJSProxy(Handle<JSProxy> proxy,
                                  Handle<FixedArray> keys);
 
   Handle<OrderedHashSet> keys() { return Handle<OrderedHashSet>::cast(keys_); }
 
   Isolate* isolate_;
   // keys_ is either an Handle<OrderedHashSet> or in the case of own JSProxy
   // keys a Handle<FixedArray>.
   Handle<FixedArray> keys_;
+  Handle<JSReceiver> first_non_empty_prototype_;
+  Handle<JSReceiver> last_non_empty_prototype_;
   KeyCollectionMode mode_;
   PropertyFilter filter_;
   bool filter_proxy_keys_ = true;
   bool is_for_in_ = false;
   bool skip_indices_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
 };
 
 // The FastKeyAccumulator handles the cases where there are no elements on the
@@ skipping 15 matching lines @@
   MaybeHandle<FixedArray> GetKeys(
       GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
 
  private:
   void Prepare();
   MaybeHandle<FixedArray> GetKeysFast(GetKeysConversion convert);
   MaybeHandle<FixedArray> GetKeysSlow(GetKeysConversion convert);
 
   Isolate* isolate_;
   Handle<JSReceiver> receiver_;
+  Handle<JSReceiver> first_non_empty_prototype_;
+  Handle<JSReceiver> last_non_empty_prototype_;
   KeyCollectionMode mode_;
   PropertyFilter filter_;
   bool filter_proxy_keys_ = true;
   bool is_for_in_ = false;
   bool is_receiver_simple_enum_ = false;
   bool has_empty_prototype_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_KEYS_H_