scopeinfo.h 5.57 KB
Newer Older
1
// Copyright 2011 the V8 project authors. All rights reserved.
2 3
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
4 5 6 7

#ifndef V8_SCOPEINFO_H_
#define V8_SCOPEINFO_H_

8
#include "src/allocation.h"
9
#include "src/modules.h"
10
#include "src/variables.h"
11

12 13
namespace v8 {
namespace internal {
14

15
// Cache for mapping (data, property name) into context slot index.
16 17 18 19 20
// The cache contains both positive and negative results.
// Slot index equals -1 means the property is absent.
// Cleared at startup and prior to mark sweep collection.
class ContextSlotCache {
 public:
21
  // Lookup context slot index for (data, name).
22
  // If absent, kNotFound is returned.
23 24 25
  int Lookup(Object* data, String* name, VariableMode* mode,
             InitializationFlag* init_flag,
             MaybeAssignedFlag* maybe_assigned_flag);
26 27

  // Update an element in the cache.
28
  void Update(Handle<Object> data, Handle<String> name, VariableMode mode,
29
              InitializationFlag init_flag,
30
              MaybeAssignedFlag maybe_assigned_flag, int slot_index);
31 32

  // Clear the cache.
33
  void Clear();
34 35

  static const int kNotFound = -2;
36

37
 private:
38 39 40 41 42 43 44 45
  ContextSlotCache() {
    for (int i = 0; i < kLength; ++i) {
      keys_[i].data = NULL;
      keys_[i].name = NULL;
      values_[i] = kNotFound;
    }
  }

46
  inline static int Hash(Object* data, String* name);
47 48

#ifdef DEBUG
49 50 51
  void ValidateEntry(Handle<Object> data, Handle<String> name,
                     VariableMode mode, InitializationFlag init_flag,
                     MaybeAssignedFlag maybe_assigned_flag, int slot_index);
52 53 54 55
#endif

  static const int kLength = 256;
  struct Key {
56
    Object* data;
57 58 59 60
    String* name;
  };

  struct Value {
61 62
    Value(VariableMode mode, InitializationFlag init_flag,
          MaybeAssignedFlag maybe_assigned_flag, int index) {
63 64 65 66
      DCHECK(ModeField::is_valid(mode));
      DCHECK(InitField::is_valid(init_flag));
      DCHECK(MaybeAssignedField::is_valid(maybe_assigned_flag));
      DCHECK(IndexField::is_valid(index));
67 68 69
      value_ = ModeField::encode(mode) | IndexField::encode(index) |
               InitField::encode(init_flag) |
               MaybeAssignedField::encode(maybe_assigned_flag);
70 71 72 73
      DCHECK(mode == this->mode());
      DCHECK(init_flag == this->initialization_flag());
      DCHECK(maybe_assigned_flag == this->maybe_assigned_flag());
      DCHECK(index == this->index());
74 75
    }

76
    explicit inline Value(uint32_t value) : value_(value) {}
77 78 79

    uint32_t raw() { return value_; }

80
    VariableMode mode() { return ModeField::decode(value_); }
81

82 83 84 85
    InitializationFlag initialization_flag() {
      return InitField::decode(value_);
    }

86 87 88 89
    MaybeAssignedFlag maybe_assigned_flag() {
      return MaybeAssignedField::decode(value_);
    }

90 91 92 93
    int index() { return IndexField::decode(value_); }

    // Bit fields in value_ (type, shift, size). Must be public so the
    // constants can be embedded in generated code.
94 95 96 97
    class ModeField : public BitField<VariableMode, 0, 4> {};
    class InitField : public BitField<InitializationFlag, 4, 1> {};
    class MaybeAssignedField : public BitField<MaybeAssignedFlag, 5, 1> {};
    class IndexField : public BitField<int, 6, 32 - 6> {};
98

99 100 101 102
   private:
    uint32_t value_;
  };

103 104 105 106 107
  Key keys_[kLength];
  uint32_t values_[kLength];

  friend class Isolate;
  DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
108 109 110
};


111 112 113 114 115 116 117 118 119 120 121 122


//---------------------------------------------------------------------------
// Auxiliary class used for the description of module instances.
// Used by Runtime_DeclareModules.

class ModuleInfo: public FixedArray {
 public:
  static ModuleInfo* cast(Object* description) {
    return static_cast<ModuleInfo*>(FixedArray::cast(description));
  }

123 124
  static Handle<ModuleInfo> Create(Isolate* isolate,
                                   ModuleDescriptor* descriptor, Scope* scope);
125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171

  // Index of module's context in host context.
  int host_index() { return Smi::cast(get(HOST_OFFSET))->value(); }

  // Name, mode, and index of the i-th export, respectively.
  // For value exports, the index is the slot of the value in the module
  // context, for exported modules it is the slot index of the
  // referred module's context in the host context.
  // TODO(rossberg): This format cannot yet handle exports of modules declared
  // in earlier scripts.
  String* name(int i) { return String::cast(get(name_offset(i))); }
  VariableMode mode(int i) {
    return static_cast<VariableMode>(Smi::cast(get(mode_offset(i)))->value());
  }
  int index(int i) { return Smi::cast(get(index_offset(i)))->value(); }

  int length() { return (FixedArray::length() - HEADER_SIZE) / ITEM_SIZE; }

 private:
  // The internal format is: Index, (Name, VariableMode, Index)*
  enum {
    HOST_OFFSET,
    NAME_OFFSET,
    MODE_OFFSET,
    INDEX_OFFSET,
    HEADER_SIZE = NAME_OFFSET,
    ITEM_SIZE = INDEX_OFFSET - NAME_OFFSET + 1
  };
  inline int name_offset(int i) { return NAME_OFFSET + i * ITEM_SIZE; }
  inline int mode_offset(int i) { return MODE_OFFSET + i * ITEM_SIZE; }
  inline int index_offset(int i) { return INDEX_OFFSET + i * ITEM_SIZE; }

  static Handle<ModuleInfo> Allocate(Isolate* isolate, int length) {
    return Handle<ModuleInfo>::cast(
        isolate->factory()->NewFixedArray(HEADER_SIZE + ITEM_SIZE * length));
  }
  void set_host_index(int index) { set(HOST_OFFSET, Smi::FromInt(index)); }
  void set_name(int i, String* name) { set(name_offset(i), name); }
  void set_mode(int i, VariableMode mode) {
    set(mode_offset(i), Smi::FromInt(mode));
  }
  void set_index(int i, int index) {
    set(index_offset(i), Smi::FromInt(index));
  }
};


172 173 174
} }  // namespace v8::internal

#endif  // V8_SCOPEINFO_H_