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_AST_CONTEXT_SLOT_CACHE_H_
       6             : #define V8_AST_CONTEXT_SLOT_CACHE_H_
       7             : 
       8             : #include "src/allocation.h"
       9             : #include "src/ast/modules.h"
      10             : 
      11             : namespace v8 {
      12             : namespace internal {
      13             : 
      14             : // Cache for mapping (data, property name) into context slot index.
      15             : // The cache contains both positive and negative results.
      16             : // Slot index equals -1 means the property is absent.
      17             : // Cleared at startup and prior to mark sweep collection.
      18             : class ContextSlotCache {
      19             :  public:
      20             :   // Lookup context slot index for (data, name).
      21             :   // If absent, kNotFound is returned.
      22             :   int Lookup(Object* data, String* name, VariableMode* mode,
      23             :              InitializationFlag* init_flag,
      24             :              MaybeAssignedFlag* maybe_assigned_flag);
      25             : 
      26             :   // Update an element in the cache.
      27             :   void Update(Handle<Object> data, Handle<String> name, VariableMode mode,
      28             :               InitializationFlag init_flag,
      29             :               MaybeAssignedFlag maybe_assigned_flag, int slot_index);
      30             : 
      31             :   // Clear the cache.
      32             :   void Clear();
      33             : 
      34             :   static const int kNotFound = -2;
      35             : 
      36             :  private:
      37             :   ContextSlotCache() {
      38    15560192 :     for (int i = 0; i < kLength; ++i) {
      39    15560192 :       keys_[i].data = NULL;
      40    15560192 :       keys_[i].name = NULL;
      41    15560192 :       values_[i] = static_cast<uint32_t>(kNotFound);
      42             :     }
      43             :   }
      44             : 
      45             :   inline static int Hash(Object* data, String* name);
      46             : 
      47             : #ifdef DEBUG
      48             :   void ValidateEntry(Handle<Object> data, Handle<String> name,
      49             :                      VariableMode mode, InitializationFlag init_flag,
      50             :                      MaybeAssignedFlag maybe_assigned_flag, int slot_index);
      51             : #endif
      52             : 
      53             :   static const int kLength = 256;
      54             :   struct Key {
      55             :     Object* data;
      56             :     String* name;
      57             :   };
      58             : 
      59             :   struct Value {
      60             :     Value(VariableMode mode, InitializationFlag init_flag,
      61             :           MaybeAssignedFlag maybe_assigned_flag, int index) {
      62             :       DCHECK(ModeField::is_valid(mode));
      63             :       DCHECK(InitField::is_valid(init_flag));
      64             :       DCHECK(MaybeAssignedField::is_valid(maybe_assigned_flag));
      65             :       DCHECK(IndexField::is_valid(index));
      66     8525638 :       value_ = ModeField::encode(mode) | IndexField::encode(index) |
      67     4262819 :                InitField::encode(init_flag) |
      68             :                MaybeAssignedField::encode(maybe_assigned_flag);
      69             :       DCHECK(mode == this->mode());
      70             :       DCHECK(init_flag == this->initialization_flag());
      71             :       DCHECK(maybe_assigned_flag == this->maybe_assigned_flag());
      72             :       DCHECK(index == this->index());
      73             :     }
      74             : 
      75             :     explicit inline Value(uint32_t value) : value_(value) {}
      76             : 
      77             :     uint32_t raw() { return value_; }
      78             : 
      79             :     VariableMode mode() { return ModeField::decode(value_); }
      80             : 
      81             :     InitializationFlag initialization_flag() {
      82             :       return InitField::decode(value_);
      83             :     }
      84             : 
      85             :     MaybeAssignedFlag maybe_assigned_flag() {
      86             :       return MaybeAssignedField::decode(value_);
      87             :     }
      88             : 
      89             :     int index() { return IndexField::decode(value_); }
      90             : 
      91             :     // Bit fields in value_ (type, shift, size). Must be public so the
      92             :     // constants can be embedded in generated code.
      93             :     class ModeField : public BitField<VariableMode, 0, 4> {};
      94             :     class InitField : public BitField<InitializationFlag, 4, 1> {};
      95             :     class MaybeAssignedField : public BitField<MaybeAssignedFlag, 5, 1> {};
      96             :     class IndexField : public BitField<int, 6, 32 - 6> {};
      97             : 
      98             :    private:
      99             :     uint32_t value_;
     100             :   };
     101             : 
     102             :   Key keys_[kLength];
     103             :   uint32_t values_[kLength];
     104             : 
     105             :   friend class Isolate;
     106             :   DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
     107             : };
     108             : 
     109             : }  // namespace internal
     110             : }  // namespace v8
     111             : 
     112             : #endif  // V8_AST_CONTEXT_SLOT_CACHE_H_