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.
8 #include "src/heap/heap.h"
9 #include "src/objects.h"
15 enum ContextLookupFlags {
16 FOLLOW_CONTEXT_CHAIN = 1,
17 FOLLOW_PROTOTYPE_CHAIN = 2,
19 DONT_FOLLOW_CHAINS = 0,
20 FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN
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.
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.
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.
54 // In V8 uninitialized bindings are set to the hole value upon creation and set
55 // to a different value upon initialization.
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,
67 // Heap-allocated activation contexts.
69 // Contexts are implemented as FixedArray objects; the Context
70 // class is a convenience interface casted on a FixedArray object.
72 // Note: Context must have no virtual functions and Context objects
73 // must always be allocated via Heap::AllocateContext() or
74 // Factory::NewContext.
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_NUMBER_FUN_INDEX, JSFunction, to_number_fun) \
89 V(TO_PRIMITIVE_INDEX, JSFunction, to_primitive) \
90 V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun)
93 #define NATIVE_CONTEXT_JS_BUILTINS(V) \
94 V(ADD_BUILTIN_INDEX, JSFunction, add_builtin) \
95 V(ADD_STRONG_BUILTIN_INDEX, JSFunction, add_strong_builtin) \
96 V(APPLY_PREPARE_BUILTIN_INDEX, JSFunction, apply_prepare_builtin) \
97 V(BIT_AND_BUILTIN_INDEX, JSFunction, bit_and_builtin) \
98 V(BIT_AND_STRONG_BUILTIN_INDEX, JSFunction, bit_and_strong_builtin) \
99 V(BIT_OR_BUILTIN_INDEX, JSFunction, bit_or_builtin) \
100 V(BIT_OR_STRONG_BUILTIN_INDEX, JSFunction, bit_or_strong_builtin) \
101 V(BIT_XOR_BUILTIN_INDEX, JSFunction, bit_xor_builtin) \
102 V(BIT_XOR_STRONG_BUILTIN_INDEX, JSFunction, bit_xor_strong_builtin) \
103 V(CALL_FUNCTION_PROXY_AS_CONSTRUCTOR_BUILTIN_INDEX, JSFunction, \
104 call_function_proxy_as_constructor_builtin) \
105 V(CALL_NON_FUNCTION_AS_CONSTRUCTOR_BUILTIN_INDEX, JSFunction, \
106 call_non_function_as_constructor_builtin) \
107 V(COMPARE_BUILTIN_INDEX, JSFunction, compare_builtin) \
108 V(COMPARE_STRONG_BUILTIN_INDEX, JSFunction, compare_strong_builtin) \
109 V(CONCAT_ITERABLE_TO_ARRAY_BUILTIN_INDEX, JSFunction, \
110 concat_iterable_to_array_builtin) \
111 V(DIV_BUILTIN_INDEX, JSFunction, div_builtin) \
112 V(DIV_STRONG_BUILTIN_INDEX, JSFunction, div_strong_builtin) \
113 V(EQUALS_BUILTIN_INDEX, JSFunction, equals_builtin) \
114 V(MOD_BUILTIN_INDEX, JSFunction, mod_builtin) \
115 V(MOD_STRONG_BUILTIN_INDEX, JSFunction, mod_strong_builtin) \
116 V(MUL_BUILTIN_INDEX, JSFunction, mul_builtin) \
117 V(MUL_STRONG_BUILTIN_INDEX, JSFunction, mul_strong_builtin) \
118 V(REFLECT_APPLY_PREPARE_BUILTIN_INDEX, JSFunction, \
119 reflect_apply_prepare_builtin) \
120 V(REFLECT_CONSTRUCT_PREPARE_BUILTIN_INDEX, JSFunction, \
121 reflect_construct_prepare_builtin) \
122 V(SAR_BUILTIN_INDEX, JSFunction, sar_builtin) \
123 V(SAR_STRONG_BUILTIN_INDEX, JSFunction, sar_strong_builtin) \
124 V(SHL_BUILTIN_INDEX, JSFunction, shl_builtin) \
125 V(SHL_STRONG_BUILTIN_INDEX, JSFunction, shl_strong_builtin) \
126 V(SHR_BUILTIN_INDEX, JSFunction, shr_builtin) \
127 V(SHR_STRONG_BUILTIN_INDEX, JSFunction, shr_strong_builtin) \
128 V(STACK_OVERFLOW_BUILTIN_INDEX, JSFunction, stack_overflow_builtin) \
129 V(STRING_ADD_LEFT_BUILTIN_INDEX, JSFunction, string_add_left_builtin) \
130 V(STRING_ADD_RIGHT_BUILTIN_INDEX, JSFunction, string_add_right_builtin) \
131 V(SUB_BUILTIN_INDEX, JSFunction, sub_builtin) \
132 V(SUB_STRONG_BUILTIN_INDEX, JSFunction, sub_strong_builtin)
135 #define NATIVE_CONTEXT_IMPORTED_FIELDS(V) \
136 V(ARRAY_CONCAT_INDEX, JSFunction, array_concat) \
137 V(ARRAY_POP_INDEX, JSFunction, array_pop) \
138 V(ARRAY_PUSH_INDEX, JSFunction, array_push) \
139 V(ARRAY_SHIFT_INDEX, JSFunction, array_shift) \
140 V(ARRAY_SPLICE_INDEX, JSFunction, array_splice) \
141 V(ARRAY_SLICE_INDEX, JSFunction, array_slice) \
142 V(ARRAY_UNSHIFT_INDEX, JSFunction, array_unshift) \
143 V(ARRAY_VALUES_ITERATOR_INDEX, JSFunction, array_values_iterator) \
144 V(CREATE_DATE_FUN_INDEX, JSFunction, create_date_fun) \
145 V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \
146 V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \
147 V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) \
148 V(ERROR_FUNCTION_INDEX, JSFunction, error_function) \
149 V(EVAL_ERROR_FUNCTION_INDEX, JSFunction, eval_error_function) \
150 V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun) \
151 V(GLOBAL_EVAL_FUN_INDEX, JSFunction, global_eval_fun) \
152 V(JSON_SERIALIZE_ADAPTER_INDEX, JSFunction, json_serialize_adapter) \
153 V(MAKE_ERROR_FUNCTION_INDEX, JSFunction, make_error_function) \
154 V(MAP_DELETE_METHOD_INDEX, JSFunction, map_delete) \
155 V(MAP_FROM_ARRAY_INDEX, JSFunction, map_from_array) \
156 V(MAP_GET_METHOD_INDEX, JSFunction, map_get) \
157 V(MAP_HAS_METHOD_INDEX, JSFunction, map_has) \
158 V(MAP_SET_METHOD_INDEX, JSFunction, map_set) \
159 V(MESSAGE_GET_COLUMN_NUMBER_INDEX, JSFunction, message_get_column_number) \
160 V(MESSAGE_GET_LINE_NUMBER_INDEX, JSFunction, message_get_line_number) \
161 V(MESSAGE_GET_SOURCE_LINE_INDEX, JSFunction, message_get_source_line) \
162 V(NATIVE_OBJECT_GET_NOTIFIER_INDEX, JSFunction, native_object_get_notifier) \
163 V(NATIVE_OBJECT_NOTIFIER_PERFORM_CHANGE, JSFunction, \
164 native_object_notifier_perform_change) \
165 V(NATIVE_OBJECT_OBSERVE_INDEX, JSFunction, native_object_observe) \
166 V(NO_SIDE_EFFECT_TO_STRING_FUN_INDEX, JSFunction, \
167 no_side_effect_to_string_fun) \
168 V(OBJECT_DEFINE_OWN_PROPERTY_INDEX, JSFunction, object_define_own_property) \
169 V(OBJECT_GET_OWN_PROPERTY_DESCROPTOR_INDEX, JSFunction, \
170 object_get_own_property_descriptor) \
171 V(OBSERVERS_BEGIN_SPLICE_INDEX, JSFunction, observers_begin_perform_splice) \
172 V(OBSERVERS_END_SPLICE_INDEX, JSFunction, observers_end_perform_splice) \
173 V(OBSERVERS_ENQUEUE_SPLICE_INDEX, JSFunction, observers_enqueue_splice) \
174 V(OBSERVERS_NOTIFY_CHANGE_INDEX, JSFunction, observers_notify_change) \
175 V(PROMISE_CATCH_INDEX, JSFunction, promise_catch) \
176 V(PROMISE_CHAIN_INDEX, JSFunction, promise_chain) \
177 V(PROMISE_CREATE_INDEX, JSFunction, promise_create) \
178 V(PROMISE_HAS_USER_DEFINED_REJECT_HANDLER_INDEX, JSFunction, \
179 promise_has_user_defined_reject_handler) \
180 V(PROMISE_REJECT_INDEX, JSFunction, promise_reject) \
181 V(PROMISE_RESOLVE_INDEX, JSFunction, promise_resolve) \
182 V(PROMISE_THEN_INDEX, JSFunction, promise_then) \
183 V(PROXY_ENUMERATE_INDEX, JSFunction, proxy_enumerate) \
184 V(RANGE_ERROR_FUNCTION_INDEX, JSFunction, range_error_function) \
185 V(REFERENCE_ERROR_FUNCTION_INDEX, JSFunction, reference_error_function) \
186 V(SET_ADD_METHOD_INDEX, JSFunction, set_add) \
187 V(SET_DELETE_METHOD_INDEX, JSFunction, set_delete) \
188 V(SET_FROM_ARRAY_INDEX, JSFunction, set_from_array) \
189 V(SET_HAS_METHOD_INDEX, JSFunction, set_has) \
190 V(STACK_OVERFLOW_BOILERPLATE_INDEX, JSObject, stack_overflow_boilerplate) \
191 V(SYNTAX_ERROR_FUNCTION_INDEX, JSFunction, syntax_error_function) \
192 V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \
193 to_complete_property_descriptor) \
194 V(TO_DETAIL_STRING_FUN_INDEX, JSFunction, to_detail_string_fun) \
195 V(TO_INTEGER_FUN_INDEX, JSFunction, to_integer_fun) \
196 V(TYPE_ERROR_FUNCTION_INDEX, JSFunction, type_error_function) \
197 V(URI_ERROR_FUNCTION_INDEX, JSFunction, uri_error_function) \
198 NATIVE_CONTEXT_JS_BUILTINS(V)
200 #define NATIVE_CONTEXT_FIELDS(V) \
201 V(GLOBAL_PROXY_INDEX, JSObject, global_proxy_object) \
202 V(EMBEDDER_DATA_INDEX, FixedArray, embedder_data) \
203 /* Below is alpha-sorted */ \
204 V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \
205 V(ARRAY_BUFFER_FUN_INDEX, JSFunction, array_buffer_fun) \
206 V(ARRAY_BUFFER_MAP_INDEX, Map, array_buffer_map) \
207 V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \
208 V(BOOL16X8_FUNCTION_INDEX, JSFunction, bool16x8_function) \
209 V(BOOL32X4_FUNCTION_INDEX, JSFunction, bool32x4_function) \
210 V(BOOL8X16_FUNCTION_INDEX, JSFunction, bool8x16_function) \
211 V(BOOLEAN_FUNCTION_INDEX, JSFunction, boolean_function) \
212 V(BOUND_FUNCTION_MAP_INDEX, Map, bound_function_map) \
213 V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction, \
214 call_as_constructor_delegate) \
215 V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \
216 V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \
217 V(DATA_VIEW_FUN_INDEX, JSFunction, data_view_fun) \
218 V(ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX, Object, \
219 error_message_for_code_gen_from_strings) \
220 V(EXTRAS_EXPORTS_OBJECT_INDEX, JSObject, extras_binding_object) \
221 V(FAST_ALIASED_ARGUMENTS_MAP_INDEX, Map, fast_aliased_arguments_map) \
222 V(FLOAT32_ARRAY_FUN_INDEX, JSFunction, float32_array_fun) \
223 V(FLOAT32X4_FUNCTION_INDEX, JSFunction, float32x4_function) \
224 V(FLOAT64_ARRAY_FUN_INDEX, JSFunction, float64_array_fun) \
225 V(FUNCTION_CACHE_INDEX, ObjectHashTable, function_cache) \
226 V(GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX, Map, generator_object_prototype_map) \
227 V(INITIAL_ARRAY_PROTOTYPE_INDEX, JSObject, initial_array_prototype) \
228 V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype) \
229 V(INT16_ARRAY_FUN_INDEX, JSFunction, int16_array_fun) \
230 V(INT16X8_FUNCTION_INDEX, JSFunction, int16x8_function) \
231 V(INT32_ARRAY_FUN_INDEX, JSFunction, int32_array_fun) \
232 V(INT32X4_FUNCTION_INDEX, JSFunction, int32x4_function) \
233 V(INT8_ARRAY_FUN_INDEX, JSFunction, int8_array_fun) \
234 V(INT8X16_FUNCTION_INDEX, JSFunction, int8x16_function) \
235 V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function) \
236 V(ITERATOR_RESULT_MAP_INDEX, Map, iterator_result_map) \
237 V(JS_ARRAY_MAPS_INDEX, Object, js_array_maps) \
238 V(JS_ARRAY_STRONG_MAPS_INDEX, Object, js_array_strong_maps) \
239 V(JS_MAP_FUN_INDEX, JSFunction, js_map_fun) \
240 V(JS_MAP_MAP_INDEX, Map, js_map_map) \
241 V(JS_OBJECT_STRONG_MAP_INDEX, Map, js_object_strong_map) \
242 V(JS_SET_FUN_INDEX, JSFunction, js_set_fun) \
243 V(JS_SET_MAP_INDEX, Map, js_set_map) \
244 V(MAP_CACHE_INDEX, Object, map_cache) \
245 V(MAP_ITERATOR_MAP_INDEX, Map, map_iterator_map) \
246 V(STRING_ITERATOR_MAP_INDEX, Map, string_iterator_map) \
247 V(MESSAGE_LISTENERS_INDEX, JSObject, message_listeners) \
248 V(NATIVES_UTILS_OBJECT_INDEX, Object, natives_utils_object) \
249 V(NORMALIZED_MAP_CACHE_INDEX, Object, normalized_map_cache) \
250 V(NUMBER_FUNCTION_INDEX, JSFunction, number_function) \
251 V(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \
252 V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \
253 V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function) \
254 V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map) \
255 V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \
256 V(SCRIPT_CONTEXT_TABLE_INDEX, ScriptContextTable, script_context_table) \
257 V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \
258 V(SECURITY_TOKEN_INDEX, Object, security_token) \
259 V(SET_ITERATOR_MAP_INDEX, Map, set_iterator_map) \
260 V(SHARED_ARRAY_BUFFER_FUN_INDEX, JSFunction, shared_array_buffer_fun) \
261 V(SLOPPY_ARGUMENTS_MAP_INDEX, Map, sloppy_arguments_map) \
262 V(SLOPPY_FUNCTION_MAP_INDEX, Map, sloppy_function_map) \
263 V(SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \
264 sloppy_function_without_prototype_map) \
265 V(SLOPPY_FUNCTION_WITH_READONLY_PROTOTYPE_MAP_INDEX, Map, \
266 sloppy_function_with_readonly_prototype_map) \
267 V(SLOPPY_GENERATOR_FUNCTION_MAP_INDEX, Map, sloppy_generator_function_map) \
268 V(SLOW_ALIASED_ARGUMENTS_MAP_INDEX, Map, slow_aliased_arguments_map) \
269 V(STRICT_ARGUMENTS_MAP_INDEX, Map, strict_arguments_map) \
270 V(STRICT_FUNCTION_MAP_INDEX, Map, strict_function_map) \
271 V(STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \
272 strict_function_without_prototype_map) \
273 V(STRICT_GENERATOR_FUNCTION_MAP_INDEX, Map, strict_generator_function_map) \
274 V(STRING_FUNCTION_INDEX, JSFunction, string_function) \
275 V(STRING_FUNCTION_PROTOTYPE_MAP_INDEX, Map, string_function_prototype_map) \
276 V(STRONG_CONSTRUCTOR_MAP_INDEX, Map, strong_constructor_map) \
277 V(STRONG_FUNCTION_MAP_INDEX, Map, strong_function_map) \
278 V(STRONG_GENERATOR_FUNCTION_MAP_INDEX, Map, strong_generator_function_map) \
279 V(STRONG_MAP_CACHE_INDEX, Object, strong_map_cache) \
280 V(SYMBOL_FUNCTION_INDEX, JSFunction, symbol_function) \
281 V(UINT16_ARRAY_FUN_INDEX, JSFunction, uint16_array_fun) \
282 V(UINT16X8_FUNCTION_INDEX, JSFunction, uint16x8_function) \
283 V(UINT32_ARRAY_FUN_INDEX, JSFunction, uint32_array_fun) \
284 V(UINT32X4_FUNCTION_INDEX, JSFunction, uint32x4_function) \
285 V(UINT8_ARRAY_FUN_INDEX, JSFunction, uint8_array_fun) \
286 V(UINT8_CLAMPED_ARRAY_FUN_INDEX, JSFunction, uint8_clamped_array_fun) \
287 V(UINT8X16_FUNCTION_INDEX, JSFunction, uint8x16_function) \
288 NATIVE_CONTEXT_INTRINSIC_FUNCTIONS(V) \
289 NATIVE_CONTEXT_IMPORTED_FIELDS(V)
291 // A table of all script contexts. Every loaded top-level script with top-level
292 // lexical declarations contributes its ScriptContext into this table.
294 // The table is a fixed array, its first slot is the current used count and
295 // the subsequent slots 1..used contain ScriptContexts.
296 class ScriptContextTable : public FixedArray {
299 static inline ScriptContextTable* cast(Object* context);
301 struct LookupResult {
305 VariableLocation location;
306 InitializationFlag init_flag;
307 MaybeAssignedFlag maybe_assigned_flag;
310 inline int used() const;
311 inline void set_used(int used);
313 static inline Handle<Context> GetContext(Handle<ScriptContextTable> table,
316 // Lookup a variable `name` in a ScriptContextTable.
317 // If it returns true, the variable is found and `result` contains
318 // valid information about its location.
319 // If it returns false, `result` is untouched.
321 static bool Lookup(Handle<ScriptContextTable> table, Handle<String> name,
322 LookupResult* result);
325 static Handle<ScriptContextTable> Extend(Handle<ScriptContextTable> table,
326 Handle<Context> script_context);
328 static int GetContextOffset(int context_index) {
329 return kFirstContextOffset + context_index * kPointerSize;
333 static const int kUsedSlot = 0;
334 static const int kFirstContextSlot = kUsedSlot + 1;
335 static const int kFirstContextOffset =
336 FixedArray::kHeaderSize + kFirstContextSlot * kPointerSize;
338 DISALLOW_IMPLICIT_CONSTRUCTORS(ScriptContextTable);
341 // JSFunctions are pairs (context, function code), sometimes also called
342 // closures. A Context object is used to represent function contexts and
343 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak).
345 // At runtime, the contexts build a stack in parallel to the execution
346 // stack, with the top-most context being the current context. All contexts
347 // have the following slots:
349 // [ closure ] This is the current function. It is the same for all
350 // contexts inside a function. It provides access to the
351 // incoming context (i.e., the outer context, which may
352 // or may not become the current function's context), and
353 // it provides access to the functions code and thus it's
354 // scope information, which in turn contains the names of
355 // statically allocated context slots. The names are needed
356 // for dynamic lookups in the presence of 'with' or 'eval'.
358 // [ previous ] A pointer to the previous context. It is NULL for
359 // function contexts, and non-NULL for 'with' contexts.
360 // Used to implement the 'with' statement.
362 // [ extension ] A pointer to an extension JSObject, or NULL. Used to
363 // implement 'with' statements and dynamic declarations
364 // (through 'eval'). The object in a 'with' statement is
365 // stored in the extension slot of a 'with' context.
366 // Dynamically declared variables/functions are also added
367 // to lazily allocated extension object. Context::Lookup
368 // searches the extension object for properties.
369 // For script and block contexts, contains the respective
370 // ScopeInfo. For block contexts representing sloppy declaration
371 // block scopes, it may also be a struct being a
372 // SloppyBlockWithEvalContextExtension, pairing the ScopeInfo
373 // with an extension object.
374 // For module contexts, points back to the respective JSModule.
376 // [ global_object ] A pointer to the global object. Provided for quick
377 // access to the global object from inside the code (since
378 // we always have a context pointer).
380 // In addition, function contexts may have statically allocated context slots
381 // to store local variables/functions that are accessed from inner functions
382 // (via static context addresses) or through 'eval' (dynamic context lookups).
383 // The native context contains additional slots for fast access to native
386 // Finally, with Harmony scoping, the JSFunction representing a top level
387 // script will have the ScriptContext rather than a FunctionContext.
388 // Script contexts from all top-level scripts are gathered in
389 // ScriptContextTable.
391 class Context: public FixedArray {
394 static inline Context* cast(Object* context);
396 // The default context slot layout; indices are FixedArray slot indices.
398 // These slots are in all contexts.
401 // The extension slot is used for either the global object (in global
402 // contexts), eval extension object (function contexts), subject of with
403 // (with contexts), or the variable name (catch contexts), the serialized
404 // scope info (block contexts), or the module instance (module contexts).
408 // These slots are only in native contexts.
409 #define NATIVE_CONTEXT_SLOT(index, type, name) index,
410 NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_SLOT)
411 #undef NATIVE_CONTEXT_SLOT
413 // Properties from here are treated as weak references by the full GC.
414 // Scavenge treats them as strong references.
415 OPTIMIZED_FUNCTIONS_LIST, // Weak.
416 OPTIMIZED_CODE_LIST, // Weak.
417 DEOPTIMIZED_CODE_LIST, // Weak.
418 NEXT_CONTEXT_LINK, // Weak.
420 // Total number of slots.
421 NATIVE_CONTEXT_SLOTS,
422 FIRST_WEAK_SLOT = OPTIMIZED_FUNCTIONS_LIST,
424 MIN_CONTEXT_SLOTS = GLOBAL_PROXY_INDEX,
425 // This slot holds the thrown value in catch contexts.
426 THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,
429 // Direct slot access.
430 inline JSFunction* closure();
431 inline void set_closure(JSFunction* closure);
433 inline Context* previous();
434 inline void set_previous(Context* context);
436 inline bool has_extension();
437 inline Object* extension();
438 inline void set_extension(Object* object);
439 JSObject* extension_object();
440 JSReceiver* extension_receiver();
441 ScopeInfo* scope_info();
442 String* catch_name();
444 inline JSModule* module();
445 inline void set_module(JSModule* module);
447 // Get the context where var declarations will be hoisted to, which
448 // may be the context itself.
449 Context* declaration_context();
450 bool is_declaration_context();
452 inline GlobalObject* global_object();
453 inline void set_global_object(GlobalObject* object);
455 // Returns a JSGlobalProxy object or null.
456 JSObject* global_proxy();
457 void set_global_proxy(JSObject* global);
459 // The builtins object.
460 JSBuiltinsObject* builtins();
462 // Get the script context by traversing the context chain.
463 Context* script_context();
465 // Compute the native context by traversing the context chain.
466 Context* native_context();
468 // Predicates for context types. IsNativeContext is also defined on Object
469 // because we frequently have to know if arbitrary objects are natives
471 inline bool IsNativeContext();
472 inline bool IsFunctionContext();
473 inline bool IsCatchContext();
474 inline bool IsWithContext();
475 inline bool IsBlockContext();
476 inline bool IsModuleContext();
477 inline bool IsScriptContext();
479 inline bool HasSameSecurityTokenAs(Context* that);
481 // Initializes global variable bindings in given script context.
482 void InitializeGlobalSlots();
484 // A native context holds a list of all functions with optimized code.
485 void AddOptimizedFunction(JSFunction* function);
486 void RemoveOptimizedFunction(JSFunction* function);
487 void SetOptimizedFunctionsListHead(Object* head);
488 Object* OptimizedFunctionsListHead();
490 // The native context also stores a list of all optimized code and a
491 // list of all deoptimized code, which are needed by the deoptimizer.
492 void AddOptimizedCode(Code* code);
493 void SetOptimizedCodeListHead(Object* head);
494 Object* OptimizedCodeListHead();
495 void SetDeoptimizedCodeListHead(Object* head);
496 Object* DeoptimizedCodeListHead();
498 Handle<Object> ErrorMessageForCodeGenerationFromStrings();
500 static int ImportedFieldIndexForName(Handle<String> name);
501 static int IntrinsicIndexForName(Handle<String> name);
503 static bool IsJSBuiltin(Handle<Context> native_context,
504 Handle<JSFunction> function);
506 #define NATIVE_CONTEXT_FIELD_ACCESSORS(index, type, name) \
507 inline void set_##name(type* value); \
508 inline bool is_##name(type* value); \
510 NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_FIELD_ACCESSORS)
511 #undef NATIVE_CONTEXT_FIELD_ACCESSORS
513 // Lookup the slot called name, starting with the current context.
514 // There are three possibilities:
516 // 1) result->IsContext():
517 // The binding was found in a context. *index is always the
518 // non-negative slot index. *attributes is NONE for var and let
519 // declarations, READ_ONLY for const declarations (never ABSENT).
521 // 2) result->IsJSObject():
522 // The binding was found as a named property in a context extension
523 // object (i.e., was introduced via eval), as a property on the subject
524 // of with, or as a property of the global object. *index is -1 and
525 // *attributes is not ABSENT.
527 // 3) result.is_null():
528 // There was no binding found, *index is always -1 and *attributes is
530 Handle<Object> Lookup(Handle<String> name,
531 ContextLookupFlags flags,
533 PropertyAttributes* attributes,
534 BindingFlags* binding_flags);
536 // Code generation support.
537 static int SlotOffset(int index) {
538 return kHeaderSize + index * kPointerSize - kHeapObjectTag;
541 static int FunctionMapIndex(LanguageMode language_mode, FunctionKind kind) {
542 if (IsGeneratorFunction(kind)) {
543 return is_strong(language_mode) ? STRONG_GENERATOR_FUNCTION_MAP_INDEX :
544 is_strict(language_mode) ? STRICT_GENERATOR_FUNCTION_MAP_INDEX
545 : SLOPPY_GENERATOR_FUNCTION_MAP_INDEX;
548 if (IsConstructor(kind)) {
549 // Use strict function map (no own "caller" / "arguments")
550 return is_strong(language_mode) ? STRONG_CONSTRUCTOR_MAP_INDEX
551 : STRICT_FUNCTION_MAP_INDEX;
554 if (IsArrowFunction(kind) || IsConciseMethod(kind) ||
555 IsAccessorFunction(kind)) {
556 return is_strong(language_mode)
557 ? STRONG_FUNCTION_MAP_INDEX
558 : STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX;
561 return is_strong(language_mode) ? STRONG_FUNCTION_MAP_INDEX :
562 is_strict(language_mode) ? STRICT_FUNCTION_MAP_INDEX
563 : SLOPPY_FUNCTION_MAP_INDEX;
566 static const int kSize = kHeaderSize + NATIVE_CONTEXT_SLOTS * kPointerSize;
567 static const int kNotFound = -1;
570 typedef FixedBodyDescriptor<
571 kHeaderSize, kSize, kSize> ScavengeBodyDescriptor;
573 typedef FixedBodyDescriptor<
575 kHeaderSize + FIRST_WEAK_SLOT * kPointerSize,
576 kSize> MarkCompactBodyDescriptor;
580 // Bootstrapping-aware type checks.
581 static bool IsBootstrappingOrValidParentContext(Object* object, Context* kid);
582 static bool IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object);
585 STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
586 STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
589 } } // namespace v8::internal
591 #endif // V8_CONTEXTS_H_