Line data    Source code

       1             : // Copyright 2016 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #ifndef V8_LOOKUP_CACHE_H_
       6             : #define V8_LOOKUP_CACHE_H_
       7             : 
       8             : #include "src/objects.h"
       9             : #include "src/objects/map.h"
      10             : #include "src/objects/name.h"
      11             : 
      12             : namespace v8 {
      13             : namespace internal {
      14             : 
      15             : // Cache for mapping (map, property name) into descriptor index.
      16             : // The cache contains both positive and negative results.
      17             : // Descriptor index equals kNotFound means the property is absent.
      18             : // Cleared at startup and prior to any gc.
      19             : class DescriptorLookupCache {
      20             :  public:
      21             :   // Lookup descriptor index for (map, name).
      22             :   // If absent, kAbsent is returned.
      23             :   inline int Lookup(Map source, Name name);
      24             : 
      25             :   // Update an element in the cache.
      26             :   inline void Update(Map source, Name name, int result);
      27             : 
      28             :   // Clear the cache.
      29             :   void Clear();
      30             : 
      31             :   static const int kAbsent = -2;
      32             : 
      33             :  private:
      34       62424 :   DescriptorLookupCache() {
      35     8052696 :     for (int i = 0; i < kLength; ++i) {
      36     3995136 :       keys_[i].source = Map();
      37     3995136 :       keys_[i].name = Name();
      38     3995136 :       results_[i] = kAbsent;
      39             :     }
      40             :   }
      41             : 
      42             :   static inline int Hash(Map source, Name name);
      43             : 
      44             :   static const int kLength = 64;
      45             :   struct Key {
      46             :     Map source;
      47             :     Name name;
      48             :   };
      49             : 
      50             :   Key keys_[kLength];
      51             :   int results_[kLength];
      52             : 
      53             :   friend class Isolate;
      54             :   DISALLOW_COPY_AND_ASSIGN(DescriptorLookupCache);
      55             : };
      56             : 
      57             : }  // namespace internal
      58             : }  // namespace v8
      59             : 
      60             : #endif  // V8_LOOKUP_CACHE_H_