Optimize Map/Set.prototype.forEach

src/objects.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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include "src/allocation.h"
 #include "src/assert-scope.h"
 #include "src/builtins.h"
@@ skipping 4429 matching lines @@
     OrderedHashMap, JSMapIterator, 2> {
  public:
   DECLARE_CAST(OrderedHashMap)
 
   Object* Lookup(Handle<Object> key);
   static Handle<OrderedHashMap> Put(
       Handle<OrderedHashMap> table,
       Handle<Object> key,
       Handle<Object> value);
 
- private:
   Object* ValueAt(int entry) {
     return get(EntryToIndex(entry) + kValueOffset);
   }
 
+ private:
   static const int kValueOffset = 1;
 };
 
 
 template <int entrysize>
 class WeakHashTableShape : public BaseShape<Handle<Object> > {
  public:
   static inline bool IsMatch(Handle<Object> key, Object* other);
   static inline uint32_t Hash(Handle<Object> key);
   static inline uint32_t HashForObject(Handle<Object> key, Object* object);
@@ skipping 5620 matching lines @@
   static const int kIndexOffset = kTableOffset + kPointerSize;
   static const int kKindOffset = kIndexOffset + kPointerSize;
   static const int kSize = kKindOffset + kPointerSize;
 
   enum Kind {
     kKindKeys = 1,
     kKindValues = 2,
     kKindEntries = 3
   };
 
-  // Returns an iterator result object: {value: any, done: boolean} and moves
-  // the index to the next valid entry. Closes the iterator if moving past the
-  // end.
-  static Handle<JSObject> Next(Handle<Derived> iterator);
+  // Whether the iterator has more elements. This needs to be called before
+  // calling |CurrentKey| and/or |CurrentValue|.
+  bool HasMore();
+
+  // Move the index forward one.
+  void MoveNext() {
+    set_index(Smi::FromInt(Smi::cast(index())->value() + 1));
+  }
+
+  // Populates the array with the next key and value and then moves the iterator
+  // forward.
+  // This returns the |kind| or 0 if the iterator is already at the end.
+  Smi* Next(JSArray* value_array);
+
+  // Returns the current key of the iterator. This should only be called when
+  // |HasMore| returns true.
+  inline Object* CurrentKey();
 
  private:
-  // Transitions the iterator to the non obsolote backing store. This is a NOP
+  // Transitions the iterator to the non obsolete backing store. This is a NOP
   // if the [table] is not obsolete.
   void Transition();
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(OrderedHashTableIterator);
 };
 
 
 class JSSetIterator: public OrderedHashTableIterator<JSSetIterator,
                                                      OrderedHashSet> {
  public:
   // Dispatched behavior.
   DECLARE_PRINTER(JSSetIterator)
   DECLARE_VERIFIER(JSSetIterator)
 
   DECLARE_CAST(JSSetIterator)
 
-  static Handle<Object> ValueForKind(
-      Handle<JSSetIterator> iterator,
-      int entry_index);
+  // Called by |Next| to populate the array. This allows the subclasses to
+  // populate the array differently.
+  inline void PopulateValueArray(FixedArray* array);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSSetIterator);
 };
 
 
 class JSMapIterator: public OrderedHashTableIterator<JSMapIterator,
                                                      OrderedHashMap> {
  public:
   // Dispatched behavior.
   DECLARE_PRINTER(JSMapIterator)
   DECLARE_VERIFIER(JSMapIterator)
 
   DECLARE_CAST(JSMapIterator)
 
-  static Handle<Object> ValueForKind(
-      Handle<JSMapIterator> iterator,
-      int entry_index);
+  // Called by |Next| to populate the array. This allows the subclasses to
+  // populate the array differently.
+  inline void PopulateValueArray(FixedArray* array);
 
  private:
+  // Returns the current value of the iterator. This should only be called when
+  // |HasMore| returns true.
+  inline Object* CurrentValue();
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSMapIterator);
 };
 
 
 // Base class for both JSWeakMap and JSWeakSet
 class JSWeakCollection: public JSObject {
  public:
   // [table]: the backing hash table mapping keys to values.
   DECL_ACCESSORS(table, Object)
 
@@ skipping 996 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_