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// Copyright 2016 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_LOOKUP_CACHE_H_
#define V8_OBJECTS_LOOKUP_CACHE_H_
#include "src/objects/map.h"
#include "src/objects/name.h"
#include "src/objects/objects.h"
namespace v8 {
namespace internal {
// Cache for mapping (map, property name) into descriptor index.
// The cache contains both positive and negative results.
// Descriptor index equals kNotFound means the property is absent.
// Cleared at startup and prior to any gc.
class DescriptorLookupCache {
public:
// Lookup descriptor index for (map, name).
// If absent, kAbsent is returned.
inline int Lookup(Map source, Name name);
// Update an element in the cache.
inline void Update(Map source, Name name, int result);
// Clear the cache.
void Clear();
static const int kAbsent = -2;
private:
DescriptorLookupCache() {
for (int i = 0; i < kLength; ++i) {
keys_[i].source = Map();
keys_[i].name = Name();
results_[i] = kAbsent;
}
}
static inline int Hash(Map source, Name name);
static const int kLength = 64;
struct Key {
Map source;
Name name;
};
Key keys_[kLength];
int results_[kLength];
friend class Isolate;
DISALLOW_COPY_AND_ASSIGN(DescriptorLookupCache);
};
} // namespace internal
} // namespace v8
#endif // V8_OBJECTS_LOOKUP_CACHE_H_