src/contexts.h

   1 // Copyright 2012 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_CONTEXTS_H_
   6 #define V8_CONTEXTS_H_
   7
   8 #include "src/heap/heap.h"
   9 #include "src/objects.h"
  10
  11 namespace v8 {
  12 namespace internal {
  13
  14
  15 enum ContextLookupFlags {
  16   FOLLOW_CONTEXT_CHAIN = 1,
  17   FOLLOW_PROTOTYPE_CHAIN = 2,
  18
  19   DONT_FOLLOW_CHAINS = 0,
  20   FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN
  21 };
  22
  23
  24 // ES5 10.2 defines lexical environments with mutable and immutable bindings.
  25 // Immutable bindings have two states, initialized and uninitialized, and
  26 // their state is changed by the InitializeImmutableBinding method. The
  27 // BindingFlags enum represents information if a binding has definitely been
  28 // initialized. A mutable binding does not need to be checked and thus has
  29 // the BindingFlag MUTABLE_IS_INITIALIZED.
  30 //
  31 // There are two possibilities for immutable bindings
  32 //  * 'const' declared variables. They are initialized when evaluating the
  33 //    corresponding declaration statement. They need to be checked for being
  34 //    initialized and thus get the flag IMMUTABLE_CHECK_INITIALIZED.
  35 //  * The function name of a named function literal. The binding is immediately
  36 //    initialized when entering the function and thus does not need to be
  37 //    checked. it gets the BindingFlag IMMUTABLE_IS_INITIALIZED.
  38 // Accessing an uninitialized binding produces the undefined value.
  39 //
  40 // The harmony proposal for block scoped bindings also introduces the
  41 // uninitialized state for mutable bindings.
  42 //  * A 'let' declared variable. They are initialized when evaluating the
  43 //    corresponding declaration statement. They need to be checked for being
  44 //    initialized and thus get the flag MUTABLE_CHECK_INITIALIZED.
  45 //  * A 'var' declared variable. It is initialized immediately upon creation
  46 //    and thus doesn't need to be checked. It gets the flag
  47 //    MUTABLE_IS_INITIALIZED.
  48 //  * Catch bound variables, function parameters and variables introduced by
  49 //    function declarations are initialized immediately and do not need to be
  50 //    checked. Thus they get the flag MUTABLE_IS_INITIALIZED.
  51 // Immutable bindings in harmony mode get the _HARMONY flag variants. Accessing
  52 // an uninitialized binding produces a reference error.
  53 //
  54 // In V8 uninitialized bindings are set to the hole value upon creation and set
  55 // to a different value upon initialization.
  56 enum BindingFlags {
  57   MUTABLE_IS_INITIALIZED,
  58   MUTABLE_CHECK_INITIALIZED,
  59   IMMUTABLE_IS_INITIALIZED,
  60   IMMUTABLE_CHECK_INITIALIZED,
  61   IMMUTABLE_IS_INITIALIZED_HARMONY,
  62   IMMUTABLE_CHECK_INITIALIZED_HARMONY,
  63   MISSING_BINDING
  64 };
  65
  66
  67 // Heap-allocated activation contexts.
  68 //
  69 // Contexts are implemented as FixedArray objects; the Context
  70 // class is a convenience interface casted on a FixedArray object.
  71 //
  72 // Note: Context must have no virtual functions and Context objects
  73 // must always be allocated via Heap::AllocateContext() or
  74 // Factory::NewContext.
  75
  76 #define NATIVE_CONTEXT_INTRINSIC_FUNCTIONS(V)                             \
  77   V(CONCAT_ITERABLE_TO_ARRAY_INDEX, JSFunction, concat_iterable_to_array) \
  78   V(GET_TEMPLATE_CALL_SITE_INDEX, JSFunction, get_template_call_site)     \
  79   V(MAKE_RANGE_ERROR_INDEX, JSFunction, make_range_error)                 \
  80   V(MAKE_TYPE_ERROR_INDEX, JSFunction, make_type_error)                   \
  81   V(NON_NUMBER_TO_NUMBER_INDEX, JSFunction, non_number_to_number)         \
  82   V(NON_STRING_TO_STRING_INDEX, JSFunction, non_string_to_string)         \
  83   V(REFLECT_APPLY_INDEX, JSFunction, reflect_apply)                       \
  84   V(REFLECT_CONSTRUCT_INDEX, JSFunction, reflect_construct)               \
  85   V(SPREAD_ARGUMENTS_INDEX, JSFunction, spread_arguments)                 \
  86   V(SPREAD_ITERABLE_INDEX, JSFunction, spread_iterable)                   \
  87   V(TO_LENGTH_FUN_INDEX, JSFunction, to_length_fun)                       \
  88   V(TO_NAME_INDEX, JSFunction, to_name)                                   \
  89   V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun)                       \
  90   V(TO_PRIMITIVE_INDEX, JSFunction, to_primitive)                         \
  91   V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun)
  92
  93
  94 #define NATIVE_CONTEXT_JS_BUILTINS(V)                                       \
  95   V(ADD_BUILTIN_INDEX, JSFunction, add_builtin)                             \
  96   V(ADD_STRONG_BUILTIN_INDEX, JSFunction, add_strong_builtin)               \
  97   V(APPLY_PREPARE_BUILTIN_INDEX, JSFunction, apply_prepare_builtin)         \
  98   V(BIT_AND_BUILTIN_INDEX, JSFunction, bit_and_builtin)                     \
  99   V(BIT_AND_STRONG_BUILTIN_INDEX, JSFunction, bit_and_strong_builtin)       \
 100   V(BIT_OR_BUILTIN_INDEX, JSFunction, bit_or_builtin)                       \
 101   V(BIT_OR_STRONG_BUILTIN_INDEX, JSFunction, bit_or_strong_builtin)         \
 102   V(BIT_XOR_BUILTIN_INDEX, JSFunction, bit_xor_builtin)                     \
 103   V(BIT_XOR_STRONG_BUILTIN_INDEX, JSFunction, bit_xor_strong_builtin)       \
 104   V(CALL_FUNCTION_PROXY_AS_CONSTRUCTOR_BUILTIN_INDEX, JSFunction,           \
 105     call_function_proxy_as_constructor_builtin)                             \
 106   V(CALL_FUNCTION_PROXY_BUILTIN_INDEX, JSFunction,                          \
 107     call_function_proxy_builtin)                                            \
 108   V(CALL_NON_FUNCTION_AS_CONSTRUCTOR_BUILTIN_INDEX, JSFunction,             \
 109     call_non_function_as_constructor_builtin)                               \
 110   V(CALL_NON_FUNCTION_BUILTIN_INDEX, JSFunction, call_non_function_builtin) \
 111   V(COMPARE_BUILTIN_INDEX, JSFunction, compare_builtin)                     \
 112   V(COMPARE_STRONG_BUILTIN_INDEX, JSFunction, compare_strong_builtin)       \
 113   V(CONCAT_ITERABLE_TO_ARRAY_BUILTIN_INDEX, JSFunction,                     \
 114     concat_iterable_to_array_builtin)                                       \
 115   V(DIV_BUILTIN_INDEX, JSFunction, div_builtin)                             \
 116   V(DIV_STRONG_BUILTIN_INDEX, JSFunction, div_strong_builtin)               \
 117   V(EQUALS_BUILTIN_INDEX, JSFunction, equals_builtin)                       \
 118   V(IN_BUILTIN_INDEX, JSFunction, in_builtin)                               \
 119   V(MOD_BUILTIN_INDEX, JSFunction, mod_builtin)                             \
 120   V(MOD_STRONG_BUILTIN_INDEX, JSFunction, mod_strong_builtin)               \
 121   V(MUL_BUILTIN_INDEX, JSFunction, mul_builtin)                             \
 122   V(MUL_STRONG_BUILTIN_INDEX, JSFunction, mul_strong_builtin)               \
 123   V(REFLECT_APPLY_PREPARE_BUILTIN_INDEX, JSFunction,                        \
 124     reflect_apply_prepare_builtin)                                          \
 125   V(REFLECT_CONSTRUCT_PREPARE_BUILTIN_INDEX, JSFunction,                    \
 126     reflect_construct_prepare_builtin)                                      \
 127   V(SAR_BUILTIN_INDEX, JSFunction, sar_builtin)                             \
 128   V(SAR_STRONG_BUILTIN_INDEX, JSFunction, sar_strong_builtin)               \
 129   V(SHL_BUILTIN_INDEX, JSFunction, shl_builtin)                             \
 130   V(SHL_STRONG_BUILTIN_INDEX, JSFunction, shl_strong_builtin)               \
 131   V(SHR_BUILTIN_INDEX, JSFunction, shr_builtin)                             \
 132   V(SHR_STRONG_BUILTIN_INDEX, JSFunction, shr_strong_builtin)               \
 133   V(STACK_OVERFLOW_BUILTIN_INDEX, JSFunction, stack_overflow_builtin)       \
 134   V(STRING_ADD_LEFT_BUILTIN_INDEX, JSFunction, string_add_left_builtin)     \
 135   V(STRING_ADD_RIGHT_BUILTIN_INDEX, JSFunction, string_add_right_builtin)   \
 136   V(SUB_BUILTIN_INDEX, JSFunction, sub_builtin)                             \
 137   V(SUB_STRONG_BUILTIN_INDEX, JSFunction, sub_strong_builtin)               \
 138   V(TO_NAME_BUILTIN_INDEX, JSFunction, to_name_builtin)                     \
 139   V(TO_NUMBER_BUILTIN_INDEX, JSFunction, to_number_builtin)                 \
 140   V(TO_STRING_BUILTIN_INDEX, JSFunction, to_string_builtin)
 141
 142
 143 #define NATIVE_CONTEXT_IMPORTED_FIELDS(V)                                     \
 144   V(ARRAY_CONCAT_INDEX, JSFunction, array_concat)                             \
 145   V(ARRAY_POP_INDEX, JSFunction, array_pop)                                   \
 146   V(ARRAY_PUSH_INDEX, JSFunction, array_push)                                 \
 147   V(ARRAY_SHIFT_INDEX, JSFunction, array_shift)                               \
 148   V(ARRAY_SPLICE_INDEX, JSFunction, array_splice)                             \
 149   V(ARRAY_SLICE_INDEX, JSFunction, array_slice)                               \
 150   V(ARRAY_UNSHIFT_INDEX, JSFunction, array_unshift)                           \
 151   V(ARRAY_VALUES_ITERATOR_INDEX, JSFunction, array_values_iterator)           \
 152   V(CREATE_DATE_FUN_INDEX, JSFunction, create_date_fun)                       \
 153   V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap)                     \
 154   V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap)                     \
 155   V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap)                     \
 156   V(ERROR_FUNCTION_INDEX, JSFunction, error_function)                         \
 157   V(EVAL_ERROR_FUNCTION_INDEX, JSFunction, eval_error_function)               \
 158   V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun)         \
 159   V(GLOBAL_EVAL_FUN_INDEX, JSFunction, global_eval_fun)                       \
 160   V(JSON_SERIALIZE_ADAPTER_INDEX, JSFunction, json_serialize_adapter)         \
 161   V(MAKE_ERROR_FUNCTION_INDEX, JSFunction, make_error_function)               \
 162   V(MAP_DELETE_METHOD_INDEX, JSFunction, map_delete)                          \
 163   V(MAP_FROM_ARRAY_INDEX, JSFunction, map_from_array)                         \
 164   V(MAP_GET_METHOD_INDEX, JSFunction, map_get)                                \
 165   V(MAP_HAS_METHOD_INDEX, JSFunction, map_has)                                \
 166   V(MAP_SET_METHOD_INDEX, JSFunction, map_set)                                \
 167   V(MESSAGE_GET_COLUMN_NUMBER_INDEX, JSFunction, message_get_column_number)   \
 168   V(MESSAGE_GET_LINE_NUMBER_INDEX, JSFunction, message_get_line_number)       \
 169   V(MESSAGE_GET_SOURCE_LINE_INDEX, JSFunction, message_get_source_line)       \
 170   V(NATIVE_OBJECT_GET_NOTIFIER_INDEX, JSFunction, native_object_get_notifier) \
 171   V(NATIVE_OBJECT_NOTIFIER_PERFORM_CHANGE, JSFunction,                        \
 172     native_object_notifier_perform_change)                                    \
 173   V(NATIVE_OBJECT_OBSERVE_INDEX, JSFunction, native_object_observe)           \
 174   V(NO_SIDE_EFFECT_TO_STRING_FUN_INDEX, JSFunction,                           \
 175     no_side_effect_to_string_fun)                                             \
 176   V(OBJECT_DEFINE_OWN_PROPERTY_INDEX, JSFunction, object_define_own_property) \
 177   V(OBJECT_GET_OWN_PROPERTY_DESCROPTOR_INDEX, JSFunction,                     \
 178     object_get_own_property_descriptor)                                       \
 179   V(OBSERVERS_BEGIN_SPLICE_INDEX, JSFunction, observers_begin_perform_splice) \
 180   V(OBSERVERS_END_SPLICE_INDEX, JSFunction, observers_end_perform_splice)     \
 181   V(OBSERVERS_ENQUEUE_SPLICE_INDEX, JSFunction, observers_enqueue_splice)     \
 182   V(OBSERVERS_NOTIFY_CHANGE_INDEX, JSFunction, observers_notify_change)       \
 183   V(PROMISE_CATCH_INDEX, JSFunction, promise_catch)                           \
 184   V(PROMISE_CHAIN_INDEX, JSFunction, promise_chain)                           \
 185   V(PROMISE_CREATE_INDEX, JSFunction, promise_create)                         \
 186   V(PROMISE_HAS_USER_DEFINED_REJECT_HANDLER_INDEX, JSFunction,                \
 187     promise_has_user_defined_reject_handler)                                  \
 188   V(PROMISE_REJECT_INDEX, JSFunction, promise_reject)                         \
 189   V(PROMISE_RESOLVE_INDEX, JSFunction, promise_resolve)                       \
 190   V(PROMISE_THEN_INDEX, JSFunction, promise_then)                             \
 191   V(PROXY_ENUMERATE_INDEX, JSFunction, proxy_enumerate)                       \
 192   V(RANGE_ERROR_FUNCTION_INDEX, JSFunction, range_error_function)             \
 193   V(REFERENCE_ERROR_FUNCTION_INDEX, JSFunction, reference_error_function)     \
 194   V(SET_ADD_METHOD_INDEX, JSFunction, set_add)                                \
 195   V(SET_DELETE_METHOD_INDEX, JSFunction, set_delete)                          \
 196   V(SET_FROM_ARRAY_INDEX, JSFunction, set_from_array)                         \
 197   V(SET_HAS_METHOD_INDEX, JSFunction, set_has)                                \
 198   V(STACK_OVERFLOW_BOILERPLATE_INDEX, JSObject, stack_overflow_boilerplate)   \
 199   V(SYNTAX_ERROR_FUNCTION_INDEX, JSFunction, syntax_error_function)           \
 200   V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction,                        \
 201     to_complete_property_descriptor)                                          \
 202   V(TO_DETAIL_STRING_FUN_INDEX, JSFunction, to_detail_string_fun)             \
 203   V(TO_INTEGER_FUN_INDEX, JSFunction, to_integer_fun)                         \
 204   V(TYPE_ERROR_FUNCTION_INDEX, JSFunction, type_error_function)               \
 205   V(URI_ERROR_FUNCTION_INDEX, JSFunction, uri_error_function)                 \
 206   NATIVE_CONTEXT_JS_BUILTINS(V)
 207
 208 #define NATIVE_CONTEXT_FIELDS(V)                                               \
 209   V(GLOBAL_PROXY_INDEX, JSObject, global_proxy_object)                         \
 210   V(EMBEDDER_DATA_INDEX, FixedArray, embedder_data)                            \
 211   /* Below is alpha-sorted */                                                  \
 212   V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings)    \
 213   V(ARRAY_BUFFER_FUN_INDEX, JSFunction, array_buffer_fun)                      \
 214   V(ARRAY_BUFFER_MAP_INDEX, Map, array_buffer_map)                             \
 215   V(ARRAY_FUNCTION_INDEX, JSFunction, array_function)                          \
 216   V(BOOL16X8_FUNCTION_INDEX, JSFunction, bool16x8_function)                    \
 217   V(BOOL32X4_FUNCTION_INDEX, JSFunction, bool32x4_function)                    \
 218   V(BOOL8X16_FUNCTION_INDEX, JSFunction, bool8x16_function)                    \
 219   V(BOOLEAN_FUNCTION_INDEX, JSFunction, boolean_function)                      \
 220   V(BOUND_FUNCTION_MAP_INDEX, Map, bound_function_map)                         \
 221   V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction,                            \
 222     call_as_constructor_delegate)                                              \
 223   V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate)    \
 224   V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function)  \
 225   V(DATA_VIEW_FUN_INDEX, JSFunction, data_view_fun)                            \
 226   V(ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX, Object,                     \
 227     error_message_for_code_gen_from_strings)                                   \
 228   V(EXTRAS_EXPORTS_OBJECT_INDEX, JSObject, extras_binding_object)              \
 229   V(FAST_ALIASED_ARGUMENTS_MAP_INDEX, Map, fast_aliased_arguments_map)         \
 230   V(FLOAT32_ARRAY_FUN_INDEX, JSFunction, float32_array_fun)                    \
 231   V(FLOAT32X4_FUNCTION_INDEX, JSFunction, float32x4_function)                  \
 232   V(FLOAT64_ARRAY_FUN_INDEX, JSFunction, float64_array_fun)                    \
 233   V(FUNCTION_CACHE_INDEX, ObjectHashTable, function_cache)                     \
 234   V(GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX, Map, generator_object_prototype_map) \
 235   V(INITIAL_ARRAY_PROTOTYPE_INDEX, JSObject, initial_array_prototype)          \
 236   V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype)        \
 237   V(INT16_ARRAY_FUN_INDEX, JSFunction, int16_array_fun)                        \
 238   V(INT16X8_FUNCTION_INDEX, JSFunction, int16x8_function)                      \
 239   V(INT32_ARRAY_FUN_INDEX, JSFunction, int32_array_fun)                        \
 240   V(INT32X4_FUNCTION_INDEX, JSFunction, int32x4_function)                      \
 241   V(INT8_ARRAY_FUN_INDEX, JSFunction, int8_array_fun)                          \
 242   V(INT8X16_FUNCTION_INDEX, JSFunction, int8x16_function)                      \
 243   V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function)        \
 244   V(ITERATOR_RESULT_MAP_INDEX, Map, iterator_result_map)                       \
 245   V(JS_ARRAY_MAPS_INDEX, Object, js_array_maps)                                \
 246   V(JS_ARRAY_STRONG_MAPS_INDEX, Object, js_array_strong_maps)                  \
 247   V(JS_MAP_FUN_INDEX, JSFunction, js_map_fun)                                  \
 248   V(JS_MAP_MAP_INDEX, Map, js_map_map)                                         \
 249   V(JS_OBJECT_STRONG_MAP_INDEX, Map, js_object_strong_map)                     \
 250   V(JS_SET_FUN_INDEX, JSFunction, js_set_fun)                                  \
 251   V(JS_SET_MAP_INDEX, Map, js_set_map)                                         \
 252   V(MAP_CACHE_INDEX, Object, map_cache)                                        \
 253   V(MAP_ITERATOR_MAP_INDEX, Map, map_iterator_map)                             \
 254   V(MESSAGE_LISTENERS_INDEX, JSObject, message_listeners)                      \
 255   V(NATIVES_UTILS_OBJECT_INDEX, Object, natives_utils_object)                  \
 256   V(NORMALIZED_MAP_CACHE_INDEX, Object, normalized_map_cache)                  \
 257   V(NUMBER_FUNCTION_INDEX, JSFunction, number_function)                        \
 258   V(OBJECT_FUNCTION_INDEX, JSFunction, object_function)                        \
 259   V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function)    \
 260   V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function)                        \
 261   V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map)                           \
 262   V(RUNTIME_CONTEXT_INDEX, Context, runtime_context)                           \
 263   V(SCRIPT_CONTEXT_TABLE_INDEX, ScriptContextTable, script_context_table)      \
 264   V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function)                        \
 265   V(SECURITY_TOKEN_INDEX, Object, security_token)                              \
 266   V(SET_ITERATOR_MAP_INDEX, Map, set_iterator_map)                             \
 267   V(SHARED_ARRAY_BUFFER_FUN_INDEX, JSFunction, shared_array_buffer_fun)        \
 268   V(SLOPPY_ARGUMENTS_MAP_INDEX, Map, sloppy_arguments_map)                     \
 269   V(SLOPPY_FUNCTION_MAP_INDEX, Map, sloppy_function_map)                       \
 270   V(SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map,                          \
 271     sloppy_function_without_prototype_map)                                     \
 272   V(SLOPPY_FUNCTION_WITH_READONLY_PROTOTYPE_MAP_INDEX, Map,                    \
 273     sloppy_function_with_readonly_prototype_map)                               \
 274   V(SLOPPY_GENERATOR_FUNCTION_MAP_INDEX, Map, sloppy_generator_function_map)   \
 275   V(SLOW_ALIASED_ARGUMENTS_MAP_INDEX, Map, slow_aliased_arguments_map)         \
 276   V(STRICT_ARGUMENTS_MAP_INDEX, Map, strict_arguments_map)                     \
 277   V(STRICT_FUNCTION_MAP_INDEX, Map, strict_function_map)                       \
 278   V(STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map,                          \
 279     strict_function_without_prototype_map)                                     \
 280   V(STRICT_GENERATOR_FUNCTION_MAP_INDEX, Map, strict_generator_function_map)   \
 281   V(STRING_FUNCTION_INDEX, JSFunction, string_function)                        \
 282   V(STRING_FUNCTION_PROTOTYPE_MAP_INDEX, Map, string_function_prototype_map)   \
 283   V(STRONG_CONSTRUCTOR_MAP_INDEX, Map, strong_constructor_map)                 \
 284   V(STRONG_FUNCTION_MAP_INDEX, Map, strong_function_map)                       \
 285   V(STRONG_GENERATOR_FUNCTION_MAP_INDEX, Map, strong_generator_function_map)   \
 286   V(STRONG_MAP_CACHE_INDEX, Object, strong_map_cache)                          \
 287   V(SYMBOL_FUNCTION_INDEX, JSFunction, symbol_function)                        \
 288   V(UINT16_ARRAY_FUN_INDEX, JSFunction, uint16_array_fun)                      \
 289   V(UINT16X8_FUNCTION_INDEX, JSFunction, uint16x8_function)                    \
 290   V(UINT32_ARRAY_FUN_INDEX, JSFunction, uint32_array_fun)                      \
 291   V(UINT32X4_FUNCTION_INDEX, JSFunction, uint32x4_function)                    \
 292   V(UINT8_ARRAY_FUN_INDEX, JSFunction, uint8_array_fun)                        \
 293   V(UINT8_CLAMPED_ARRAY_FUN_INDEX, JSFunction, uint8_clamped_array_fun)        \
 294   V(UINT8X16_FUNCTION_INDEX, JSFunction, uint8x16_function)                    \
 295   NATIVE_CONTEXT_INTRINSIC_FUNCTIONS(V)                                        \
 296   NATIVE_CONTEXT_IMPORTED_FIELDS(V)
 297
 298 // A table of all script contexts. Every loaded top-level script with top-level
 299 // lexical declarations contributes its ScriptContext into this table.
 300 //
 301 // The table is a fixed array, its first slot is the current used count and
 302 // the subsequent slots 1..used contain ScriptContexts.
 303 class ScriptContextTable : public FixedArray {
 304  public:
 305   // Conversions.
 306   static ScriptContextTable* cast(Object* context) {
 307     DCHECK(context->IsScriptContextTable());
 308     return reinterpret_cast<ScriptContextTable*>(context);
 309   }
 310
 311   struct LookupResult {
 312     int context_index;
 313     int slot_index;
 314     VariableMode mode;
 315     VariableLocation location;
 316     InitializationFlag init_flag;
 317     MaybeAssignedFlag maybe_assigned_flag;
 318   };
 319
 320   int used() const { return Smi::cast(get(kUsedSlot))->value(); }
 321
 322   void set_used(int used) { set(kUsedSlot, Smi::FromInt(used)); }
 323
 324   static Handle<Context> GetContext(Handle<ScriptContextTable> table, int i) {
 325     DCHECK(i < table->used());
 326     return Handle<Context>::cast(FixedArray::get(table, i + 1));
 327   }
 328
 329   // Lookup a variable `name` in a ScriptContextTable.
 330   // If it returns true, the variable is found and `result` contains
 331   // valid information about its location.
 332   // If it returns false, `result` is untouched.
 333   MUST_USE_RESULT
 334   static bool Lookup(Handle<ScriptContextTable> table, Handle<String> name,
 335                      LookupResult* result);
 336
 337   MUST_USE_RESULT
 338   static Handle<ScriptContextTable> Extend(Handle<ScriptContextTable> table,
 339                                            Handle<Context> script_context);
 340
 341   static int GetContextOffset(int context_index) {
 342     return kFirstContextOffset + context_index * kPointerSize;
 343   }
 344
 345  private:
 346   static const int kUsedSlot = 0;
 347   static const int kFirstContextOffset =
 348       FixedArray::kHeaderSize + (kUsedSlot + 1) * kPointerSize;
 349
 350   DISALLOW_IMPLICIT_CONSTRUCTORS(ScriptContextTable);
 351 };
 352
 353 // JSFunctions are pairs (context, function code), sometimes also called
 354 // closures. A Context object is used to represent function contexts and
 355 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak).
 356 //
 357 // At runtime, the contexts build a stack in parallel to the execution
 358 // stack, with the top-most context being the current context. All contexts
 359 // have the following slots:
 360 //
 361 // [ closure   ]  This is the current function. It is the same for all
 362 //                contexts inside a function. It provides access to the
 363 //                incoming context (i.e., the outer context, which may
 364 //                or may not become the current function's context), and
 365 //                it provides access to the functions code and thus it's
 366 //                scope information, which in turn contains the names of
 367 //                statically allocated context slots. The names are needed
 368 //                for dynamic lookups in the presence of 'with' or 'eval'.
 369 //
 370 // [ previous  ]  A pointer to the previous context. It is NULL for
 371 //                function contexts, and non-NULL for 'with' contexts.
 372 //                Used to implement the 'with' statement.
 373 //
 374 // [ extension ]  A pointer to an extension JSObject, or NULL. Used to
 375 //                implement 'with' statements and dynamic declarations
 376 //                (through 'eval'). The object in a 'with' statement is
 377 //                stored in the extension slot of a 'with' context.
 378 //                Dynamically declared variables/functions are also added
 379 //                to lazily allocated extension object. Context::Lookup
 380 //                searches the extension object for properties.
 381 //                For script and block contexts, contains the respective
 382 //                ScopeInfo. For block contexts representing sloppy declaration
 383 //                block scopes, it may also be a struct being a
 384 //                SloppyBlockWithEvalContextExtension, pairing the ScopeInfo
 385 //                with an extension object.
 386 //                For module contexts, points back to the respective JSModule.
 387 //
 388 // [ global_object ]  A pointer to the global object. Provided for quick
 389 //                access to the global object from inside the code (since
 390 //                we always have a context pointer).
 391 //
 392 // In addition, function contexts may have statically allocated context slots
 393 // to store local variables/functions that are accessed from inner functions
 394 // (via static context addresses) or through 'eval' (dynamic context lookups).
 395 // The native context contains additional slots for fast access to native
 396 // properties.
 397 //
 398 // Finally, with Harmony scoping, the JSFunction representing a top level
 399 // script will have the ScriptContext rather than a FunctionContext.
 400 // Script contexts from all top-level scripts are gathered in
 401 // ScriptContextTable.
 402
 403 class Context: public FixedArray {
 404  public:
 405   // Conversions.
 406   static Context* cast(Object* context) {
 407     DCHECK(context->IsContext());
 408     return reinterpret_cast<Context*>(context);
 409   }
 410
 411   // The default context slot layout; indices are FixedArray slot indices.
 412   enum {
 413     // These slots are in all contexts.
 414     CLOSURE_INDEX,
 415     PREVIOUS_INDEX,
 416     // The extension slot is used for either the global object (in global
 417     // contexts), eval extension object (function contexts), subject of with
 418     // (with contexts), or the variable name (catch contexts), the serialized
 419     // scope info (block contexts), or the module instance (module contexts).
 420     EXTENSION_INDEX,
 421     GLOBAL_OBJECT_INDEX,
 422
 423     // These slots are only in native contexts.
 424 #define NATIVE_CONTEXT_SLOT(index, type, name) index,
 425     NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_SLOT)
 426 #undef NATIVE_CONTEXT_SLOT
 427
 428     // Properties from here are treated as weak references by the full GC.
 429     // Scavenge treats them as strong references.
 430     OPTIMIZED_FUNCTIONS_LIST,  // Weak.
 431     OPTIMIZED_CODE_LIST,       // Weak.
 432     DEOPTIMIZED_CODE_LIST,     // Weak.
 433     NEXT_CONTEXT_LINK,         // Weak.
 434
 435     // Total number of slots.
 436     NATIVE_CONTEXT_SLOTS,
 437     FIRST_WEAK_SLOT = OPTIMIZED_FUNCTIONS_LIST,
 438
 439     MIN_CONTEXT_SLOTS = GLOBAL_PROXY_INDEX,
 440     // This slot holds the thrown value in catch contexts.
 441     THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,
 442   };
 443
 444   // Direct slot access.
 445   JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); }
 446   void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); }
 447
 448   Context* previous() {
 449     Object* result = unchecked_previous();
 450     DCHECK(IsBootstrappingOrValidParentContext(result, this));
 451     return reinterpret_cast<Context*>(result);
 452   }
 453   void set_previous(Context* context) { set(PREVIOUS_INDEX, context); }
 454
 455   bool has_extension() { return extension() != nullptr; }
 456   Object* extension() { return get(EXTENSION_INDEX); }
 457   void set_extension(Object* object) { set(EXTENSION_INDEX, object); }
 458   JSObject* extension_object();
 459   JSReceiver* extension_receiver();
 460   ScopeInfo* scope_info();
 461   String* catch_name();
 462
 463   JSModule* module() { return JSModule::cast(get(EXTENSION_INDEX)); }
 464   void set_module(JSModule* module) { set(EXTENSION_INDEX, module); }
 465
 466   // Get the context where var declarations will be hoisted to, which
 467   // may be the context itself.
 468   Context* declaration_context();
 469   bool is_declaration_context();
 470
 471   GlobalObject* global_object() {
 472     Object* result = get(GLOBAL_OBJECT_INDEX);
 473     DCHECK(IsBootstrappingOrGlobalObject(this->GetIsolate(), result));
 474     return reinterpret_cast<GlobalObject*>(result);
 475   }
 476   void set_global_object(GlobalObject* object) {
 477     set(GLOBAL_OBJECT_INDEX, object);
 478   }
 479
 480   // Returns a JSGlobalProxy object or null.
 481   JSObject* global_proxy();
 482   void set_global_proxy(JSObject* global);
 483
 484   // The builtins object.
 485   JSBuiltinsObject* builtins();
 486
 487   // Get the script context by traversing the context chain.
 488   Context* script_context();
 489
 490   // Compute the native context by traversing the context chain.
 491   Context* native_context();
 492
 493   // Predicates for context types.  IsNativeContext is also defined on Object
 494   // because we frequently have to know if arbitrary objects are natives
 495   // contexts.
 496   bool IsNativeContext() {
 497     Map* map = this->map();
 498     return map == map->GetHeap()->native_context_map();
 499   }
 500   bool IsFunctionContext() {
 501     Map* map = this->map();
 502     return map == map->GetHeap()->function_context_map();
 503   }
 504   bool IsCatchContext() {
 505     Map* map = this->map();
 506     return map == map->GetHeap()->catch_context_map();
 507   }
 508   bool IsWithContext() {
 509     Map* map = this->map();
 510     return map == map->GetHeap()->with_context_map();
 511   }
 512   bool IsBlockContext() {
 513     Map* map = this->map();
 514     return map == map->GetHeap()->block_context_map();
 515   }
 516   bool IsModuleContext() {
 517     Map* map = this->map();
 518     return map == map->GetHeap()->module_context_map();
 519   }
 520   bool IsScriptContext() {
 521     Map* map = this->map();
 522     return map == map->GetHeap()->script_context_map();
 523   }
 524
 525   bool HasSameSecurityTokenAs(Context* that) {
 526     return this->global_object()->native_context()->security_token() ==
 527         that->global_object()->native_context()->security_token();
 528   }
 529
 530   // Initializes global variable bindings in given script context.
 531   void InitializeGlobalSlots();
 532
 533   // A native context holds a list of all functions with optimized code.
 534   void AddOptimizedFunction(JSFunction* function);
 535   void RemoveOptimizedFunction(JSFunction* function);
 536   void SetOptimizedFunctionsListHead(Object* head);
 537   Object* OptimizedFunctionsListHead();
 538
 539   // The native context also stores a list of all optimized code and a
 540   // list of all deoptimized code, which are needed by the deoptimizer.
 541   void AddOptimizedCode(Code* code);
 542   void SetOptimizedCodeListHead(Object* head);
 543   Object* OptimizedCodeListHead();
 544   void SetDeoptimizedCodeListHead(Object* head);
 545   Object* DeoptimizedCodeListHead();
 546
 547   Handle<Object> ErrorMessageForCodeGenerationFromStrings();
 548
 549   static int ImportedFieldIndexForName(Handle<String> name);
 550   static int IntrinsicIndexForName(Handle<String> name);
 551
 552   static bool IsJSBuiltin(Handle<Context> native_context,
 553                           Handle<JSFunction> function);
 554
 555 #define NATIVE_CONTEXT_FIELD_ACCESSORS(index, type, name) \
 556   void  set_##name(type* value) {                         \
 557     DCHECK(IsNativeContext());                            \
 558     set(index, value);                                    \
 559   }                                                       \
 560   bool is_##name(type* value) {                           \
 561     DCHECK(IsNativeContext());                            \
 562     return type::cast(get(index)) == value;               \
 563   }                                                       \
 564   type* name() {                                          \
 565     DCHECK(IsNativeContext());                            \
 566     return type::cast(get(index));                        \
 567   }
 568   NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_FIELD_ACCESSORS)
 569 #undef NATIVE_CONTEXT_FIELD_ACCESSORS
 570
 571   // Lookup the slot called name, starting with the current context.
 572   // There are three possibilities:
 573   //
 574   // 1) result->IsContext():
 575   //    The binding was found in a context.  *index is always the
 576   //    non-negative slot index.  *attributes is NONE for var and let
 577   //    declarations, READ_ONLY for const declarations (never ABSENT).
 578   //
 579   // 2) result->IsJSObject():
 580   //    The binding was found as a named property in a context extension
 581   //    object (i.e., was introduced via eval), as a property on the subject
 582   //    of with, or as a property of the global object.  *index is -1 and
 583   //    *attributes is not ABSENT.
 584   //
 585   // 3) result.is_null():
 586   //    There was no binding found, *index is always -1 and *attributes is
 587   //    always ABSENT.
 588   Handle<Object> Lookup(Handle<String> name,
 589                         ContextLookupFlags flags,
 590                         int* index,
 591                         PropertyAttributes* attributes,
 592                         BindingFlags* binding_flags);
 593
 594   // Code generation support.
 595   static int SlotOffset(int index) {
 596     return kHeaderSize + index * kPointerSize - kHeapObjectTag;
 597   }
 598
 599   static int FunctionMapIndex(LanguageMode language_mode, FunctionKind kind) {
 600     if (IsGeneratorFunction(kind)) {
 601       return is_strong(language_mode) ? STRONG_GENERATOR_FUNCTION_MAP_INDEX :
 602              is_strict(language_mode) ? STRICT_GENERATOR_FUNCTION_MAP_INDEX
 603                                       : SLOPPY_GENERATOR_FUNCTION_MAP_INDEX;
 604     }
 605
 606     if (IsConstructor(kind)) {
 607       // Use strict function map (no own "caller" / "arguments")
 608       return is_strong(language_mode) ? STRONG_CONSTRUCTOR_MAP_INDEX
 609                                       : STRICT_FUNCTION_MAP_INDEX;
 610     }
 611
 612     if (IsArrowFunction(kind) || IsConciseMethod(kind) ||
 613         IsAccessorFunction(kind)) {
 614       return is_strong(language_mode)
 615                  ? STRONG_FUNCTION_MAP_INDEX
 616                  : STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX;
 617     }
 618
 619     return is_strong(language_mode) ? STRONG_FUNCTION_MAP_INDEX :
 620            is_strict(language_mode) ? STRICT_FUNCTION_MAP_INDEX
 621                                     : SLOPPY_FUNCTION_MAP_INDEX;
 622   }
 623
 624   static const int kSize = kHeaderSize + NATIVE_CONTEXT_SLOTS * kPointerSize;
 625   static const int kNotFound = -1;
 626
 627   // GC support.
 628   typedef FixedBodyDescriptor<
 629       kHeaderSize, kSize, kSize> ScavengeBodyDescriptor;
 630
 631   typedef FixedBodyDescriptor<
 632       kHeaderSize,
 633       kHeaderSize + FIRST_WEAK_SLOT * kPointerSize,
 634       kSize> MarkCompactBodyDescriptor;
 635
 636  private:
 637   // Unchecked access to the slots.
 638   Object* unchecked_previous() { return get(PREVIOUS_INDEX); }
 639
 640 #ifdef DEBUG
 641   // Bootstrapping-aware type checks.
 642   static bool IsBootstrappingOrValidParentContext(Object* object, Context* kid);
 643   static bool IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object);
 644 #endif
 645
 646   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
 647   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 648 };
 649
 650 } }  // namespace v8::internal
 651
 652 #endif  // V8_CONTEXTS_H_