KeyedLookupCache and DescriptorLookupCache -> lookup-cache{-inl.h,.cc,.h}

src/lookup-cache.h

+// 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_LOOKUP_CACHE_H_
+#define V8_LOOKUP_CACHE_H_
+
+#include "src/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 = NULL;
+      keys_[i].name = NULL;
+      results_[i] = kAbsent;
+    }
+  }
+
+  static inline int Hash(Object* 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);
+};
+
+// Cache for mapping (map, property name) into field offset.
+// Cleared at startup and prior to mark sweep collection.
+class KeyedLookupCache {
+ public:
+  // Lookup field offset for (map, name). If absent, -1 is returned.
+  int Lookup(Handle<Map> map, Handle<Name> name);
+
+  // Update an element in the cache.
+  void Update(Handle<Map> map, Handle<Name> name, int field_offset);
+
+  // Clear the cache.
+  void Clear();
+
+  static const int kLength = 256;
+  static const int kCapacityMask = kLength - 1;
+  static const int kMapHashShift = 5;
+  static const int kHashMask = -4;  // Zero the last two bits.
+  static const int kEntriesPerBucket = 4;
+  static const int kEntryLength = 2;
+  static const int kMapIndex = 0;
+  static const int kKeyIndex = 1;
+  static const int kNotFound = -1;
+
+  // kEntriesPerBucket should be a power of 2.
+  STATIC_ASSERT((kEntriesPerBucket & (kEntriesPerBucket - 1)) == 0);
+  STATIC_ASSERT(kEntriesPerBucket == -kHashMask);
+
+ private:
+  KeyedLookupCache() {
+    for (int i = 0; i < kLength; ++i) {
+      keys_[i].map = NULL;
+      keys_[i].name = NULL;
+      field_offsets_[i] = kNotFound;
+    }
+  }
+
+  static inline int Hash(Handle<Map> map, Handle<Name> name);
+
+  // Get the address of the keys and field_offsets arrays.  Used in
+  // generated code to perform cache lookups.
+  Address keys_address() { return reinterpret_cast<Address>(&keys_); }
+
+  Address field_offsets_address() {
+    return reinterpret_cast<Address>(&field_offsets_);
+  }
+
+  struct Key {
+    Map* map;
+    Name* name;
+  };
+
+  Key keys_[kLength];
+  int field_offsets_[kLength];
+
+  friend class ExternalReference;
+  friend class Isolate;
+  DISALLOW_COPY_AND_ASSIGN(KeyedLookupCache);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_LOOKUP_CACHE_H_