1 // Copyright 2012 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_CONTEXTS_H_ 29 #define V8_CONTEXTS_H_ 30 31 #include "heap.h" 32 #include "objects.h" 33 34 namespace v8 { 35 namespace internal { 36 37 38 enum ContextLookupFlags { 39 FOLLOW_CONTEXT_CHAIN = 1, 40 FOLLOW_PROTOTYPE_CHAIN = 2, 41 42 DONT_FOLLOW_CHAINS = 0, 43 FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN 44 }; 45 46 47 // ES5 10.2 defines lexical environments with mutable and immutable bindings. 48 // Immutable bindings have two states, initialized and uninitialized, and 49 // their state is changed by the InitializeImmutableBinding method. The 50 // BindingFlags enum represents information if a binding has definitely been 51 // initialized. A mutable binding does not need to be checked and thus has 52 // the BindingFlag MUTABLE_IS_INITIALIZED. 53 // 54 // There are two possibilities for immutable bindings 55 // * 'const' declared variables. They are initialized when evaluating the 56 // corresponding declaration statement. They need to be checked for being 57 // initialized and thus get the flag IMMUTABLE_CHECK_INITIALIZED. 58 // * The function name of a named function literal. The binding is immediately 59 // initialized when entering the function and thus does not need to be 60 // checked. it gets the BindingFlag IMMUTABLE_IS_INITIALIZED. 61 // Accessing an uninitialized binding produces the undefined value. 62 // 63 // The harmony proposal for block scoped bindings also introduces the 64 // uninitialized state for mutable bindings. 65 // * A 'let' declared variable. They are initialized when evaluating the 66 // corresponding declaration statement. They need to be checked for being 67 // initialized and thus get the flag MUTABLE_CHECK_INITIALIZED. 68 // * A 'var' declared variable. It is initialized immediately upon creation 69 // and thus doesn't need to be checked. It gets the flag 70 // MUTABLE_IS_INITIALIZED. 71 // * Catch bound variables, function parameters and variables introduced by 72 // function declarations are initialized immediately and do not need to be 73 // checked. Thus they get the flag MUTABLE_IS_INITIALIZED. 74 // Immutable bindings in harmony mode get the _HARMONY flag variants. Accessing 75 // an uninitialized binding produces a reference error. 76 // 77 // In V8 uninitialized bindings are set to the hole value upon creation and set 78 // to a different value upon initialization. 79 enum BindingFlags { 80 MUTABLE_IS_INITIALIZED, 81 MUTABLE_CHECK_INITIALIZED, 82 IMMUTABLE_IS_INITIALIZED, 83 IMMUTABLE_CHECK_INITIALIZED, 84 IMMUTABLE_IS_INITIALIZED_HARMONY, 85 IMMUTABLE_CHECK_INITIALIZED_HARMONY, 86 MISSING_BINDING 87 }; 88 89 90 // Heap-allocated activation contexts. 91 // 92 // Contexts are implemented as FixedArray objects; the Context 93 // class is a convenience interface casted on a FixedArray object. 94 // 95 // Note: Context must have no virtual functions and Context objects 96 // must always be allocated via Heap::AllocateContext() or 97 // Factory::NewContext. 98 99 #define GLOBAL_CONTEXT_FIELDS(V) \ 100 V(GLOBAL_PROXY_INDEX, JSObject, global_proxy_object) \ 101 V(SECURITY_TOKEN_INDEX, Object, security_token) \ 102 V(BOOLEAN_FUNCTION_INDEX, JSFunction, boolean_function) \ 103 V(NUMBER_FUNCTION_INDEX, JSFunction, number_function) \ 104 V(STRING_FUNCTION_INDEX, JSFunction, string_function) \ 105 V(STRING_FUNCTION_PROTOTYPE_MAP_INDEX, Map, string_function_prototype_map) \ 106 V(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \ 107 V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function) \ 108 V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \ 109 V(SMI_JS_ARRAY_MAP_INDEX, Object, smi_js_array_map) \ 110 V(DOUBLE_JS_ARRAY_MAP_INDEX, Object, double_js_array_map) \ 111 V(OBJECT_JS_ARRAY_MAP_INDEX, Object, object_js_array_map) \ 112 V(DATE_FUNCTION_INDEX, JSFunction, date_function) \ 113 V(JSON_OBJECT_INDEX, JSObject, json_object) \ 114 V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function) \ 115 V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype) \ 116 V(CREATE_DATE_FUN_INDEX, JSFunction, create_date_fun) \ 117 V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun) \ 118 V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun) \ 119 V(TO_DETAIL_STRING_FUN_INDEX, JSFunction, to_detail_string_fun) \ 120 V(TO_OBJECT_FUN_INDEX, JSFunction, to_object_fun) \ 121 V(TO_INTEGER_FUN_INDEX, JSFunction, to_integer_fun) \ 122 V(TO_UINT32_FUN_INDEX, JSFunction, to_uint32_fun) \ 123 V(TO_INT32_FUN_INDEX, JSFunction, to_int32_fun) \ 124 V(GLOBAL_EVAL_FUN_INDEX, JSFunction, global_eval_fun) \ 125 V(INSTANTIATE_FUN_INDEX, JSFunction, instantiate_fun) \ 126 V(CONFIGURE_INSTANCE_FUN_INDEX, JSFunction, configure_instance_fun) \ 127 V(FUNCTION_MAP_INDEX, Map, function_map) \ 128 V(STRICT_MODE_FUNCTION_MAP_INDEX, Map, strict_mode_function_map) \ 129 V(FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, function_without_prototype_map) \ 130 V(STRICT_MODE_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \ 131 strict_mode_function_without_prototype_map) \ 132 V(FUNCTION_INSTANCE_MAP_INDEX, Map, function_instance_map) \ 133 V(STRICT_MODE_FUNCTION_INSTANCE_MAP_INDEX, Map, \ 134 strict_mode_function_instance_map) \ 135 V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map)\ 136 V(ARGUMENTS_BOILERPLATE_INDEX, JSObject, arguments_boilerplate) \ 137 V(ALIASED_ARGUMENTS_BOILERPLATE_INDEX, JSObject, \ 138 aliased_arguments_boilerplate) \ 139 V(STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX, JSObject, \ 140 strict_mode_arguments_boilerplate) \ 141 V(MESSAGE_LISTENERS_INDEX, JSObject, message_listeners) \ 142 V(MAKE_MESSAGE_FUN_INDEX, JSFunction, make_message_fun) \ 143 V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun) \ 144 V(CONFIGURE_GLOBAL_INDEX, JSFunction, configure_global_fun) \ 145 V(FUNCTION_CACHE_INDEX, JSObject, function_cache) \ 146 V(JSFUNCTION_RESULT_CACHES_INDEX, FixedArray, jsfunction_result_caches) \ 147 V(NORMALIZED_MAP_CACHE_INDEX, NormalizedMapCache, normalized_map_cache) \ 148 V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \ 149 V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \ 150 V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction, \ 151 call_as_constructor_delegate) \ 152 V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \ 153 V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \ 154 V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \ 155 V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \ 156 V(MAP_CACHE_INDEX, Object, map_cache) \ 157 V(CONTEXT_DATA_INDEX, Object, data) \ 158 V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \ 159 V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \ 160 to_complete_property_descriptor) \ 161 V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \ 162 V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \ 163 V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) \ 164 V(PROXY_ENUMERATE, JSFunction, proxy_enumerate) \ 165 V(RANDOM_SEED_INDEX, ByteArray, random_seed) 166 167 // JSFunctions are pairs (context, function code), sometimes also called 168 // closures. A Context object is used to represent function contexts and 169 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak). 170 // 171 // At runtime, the contexts build a stack in parallel to the execution 172 // stack, with the top-most context being the current context. All contexts 173 // have the following slots: 174 // 175 // [ closure ] This is the current function. It is the same for all 176 // contexts inside a function. It provides access to the 177 // incoming context (i.e., the outer context, which may 178 // or may not become the current function's context), and 179 // it provides access to the functions code and thus it's 180 // scope information, which in turn contains the names of 181 // statically allocated context slots. The names are needed 182 // for dynamic lookups in the presence of 'with' or 'eval'. 183 // 184 // [ previous ] A pointer to the previous context. It is NULL for 185 // function contexts, and non-NULL for 'with' contexts. 186 // Used to implement the 'with' statement. 187 // 188 // [ extension ] A pointer to an extension JSObject, or NULL. Used to 189 // implement 'with' statements and dynamic declarations 190 // (through 'eval'). The object in a 'with' statement is 191 // stored in the extension slot of a 'with' context. 192 // Dynamically declared variables/functions are also added 193 // to lazily allocated extension object. Context::Lookup 194 // searches the extension object for properties. 195 // 196 // [ global ] A pointer to the global object. Provided for quick 197 // access to the global object from inside the code (since 198 // we always have a context pointer). 199 // 200 // In addition, function contexts may have statically allocated context slots 201 // to store local variables/functions that are accessed from inner functions 202 // (via static context addresses) or through 'eval' (dynamic context lookups). 203 // Finally, the global context contains additional slots for fast access to 204 // global properties. 205 206 class Context: public FixedArray { 207 public: 208 // Conversions. 209 static Context* cast(Object* context) { 210 ASSERT(context->IsContext()); 211 return reinterpret_cast<Context*>(context); 212 } 213 214 // The default context slot layout; indices are FixedArray slot indices. 215 enum { 216 // These slots are in all contexts. 217 CLOSURE_INDEX, 218 PREVIOUS_INDEX, 219 // The extension slot is used for either the global object (in global 220 // contexts), eval extension object (function contexts), subject of with 221 // (with contexts), or the variable name (catch contexts), the serialized 222 // scope info (block contexts). 223 EXTENSION_INDEX, 224 GLOBAL_INDEX, 225 MIN_CONTEXT_SLOTS, 226 227 // This slot holds the thrown value in catch contexts. 228 THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS, 229 230 // These slots are only in global contexts. 231 GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS, 232 SECURITY_TOKEN_INDEX, 233 ARGUMENTS_BOILERPLATE_INDEX, 234 ALIASED_ARGUMENTS_BOILERPLATE_INDEX, 235 STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX, 236 REGEXP_RESULT_MAP_INDEX, 237 FUNCTION_MAP_INDEX, 238 STRICT_MODE_FUNCTION_MAP_INDEX, 239 FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, 240 STRICT_MODE_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, 241 FUNCTION_INSTANCE_MAP_INDEX, 242 STRICT_MODE_FUNCTION_INSTANCE_MAP_INDEX, 243 INITIAL_OBJECT_PROTOTYPE_INDEX, 244 BOOLEAN_FUNCTION_INDEX, 245 NUMBER_FUNCTION_INDEX, 246 STRING_FUNCTION_INDEX, 247 STRING_FUNCTION_PROTOTYPE_MAP_INDEX, 248 OBJECT_FUNCTION_INDEX, 249 INTERNAL_ARRAY_FUNCTION_INDEX, 250 ARRAY_FUNCTION_INDEX, 251 SMI_JS_ARRAY_MAP_INDEX, 252 DOUBLE_JS_ARRAY_MAP_INDEX, 253 OBJECT_JS_ARRAY_MAP_INDEX, 254 DATE_FUNCTION_INDEX, 255 JSON_OBJECT_INDEX, 256 REGEXP_FUNCTION_INDEX, 257 CREATE_DATE_FUN_INDEX, 258 TO_NUMBER_FUN_INDEX, 259 TO_STRING_FUN_INDEX, 260 TO_DETAIL_STRING_FUN_INDEX, 261 TO_OBJECT_FUN_INDEX, 262 TO_INTEGER_FUN_INDEX, 263 TO_UINT32_FUN_INDEX, 264 TO_INT32_FUN_INDEX, 265 TO_BOOLEAN_FUN_INDEX, 266 GLOBAL_EVAL_FUN_INDEX, 267 INSTANTIATE_FUN_INDEX, 268 CONFIGURE_INSTANCE_FUN_INDEX, 269 MESSAGE_LISTENERS_INDEX, 270 MAKE_MESSAGE_FUN_INDEX, 271 GET_STACK_TRACE_LINE_INDEX, 272 CONFIGURE_GLOBAL_INDEX, 273 FUNCTION_CACHE_INDEX, 274 JSFUNCTION_RESULT_CACHES_INDEX, 275 NORMALIZED_MAP_CACHE_INDEX, 276 RUNTIME_CONTEXT_INDEX, 277 CALL_AS_FUNCTION_DELEGATE_INDEX, 278 CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, 279 SCRIPT_FUNCTION_INDEX, 280 OPAQUE_REFERENCE_FUNCTION_INDEX, 281 CONTEXT_EXTENSION_FUNCTION_INDEX, 282 OUT_OF_MEMORY_INDEX, 283 CONTEXT_DATA_INDEX, 284 ALLOW_CODE_GEN_FROM_STRINGS_INDEX, 285 TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, 286 DERIVED_HAS_TRAP_INDEX, 287 DERIVED_GET_TRAP_INDEX, 288 DERIVED_SET_TRAP_INDEX, 289 PROXY_ENUMERATE, 290 RANDOM_SEED_INDEX, 291 292 // Properties from here are treated as weak references by the full GC. 293 // Scavenge treats them as strong references. 294 OPTIMIZED_FUNCTIONS_LIST, // Weak. 295 MAP_CACHE_INDEX, // Weak. 296 NEXT_CONTEXT_LINK, // Weak. 297 298 // Total number of slots. 299 GLOBAL_CONTEXT_SLOTS, 300 301 FIRST_WEAK_SLOT = OPTIMIZED_FUNCTIONS_LIST 302 }; 303 304 // Direct slot access. 305 JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); } 306 void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); } 307 308 Context* previous() { 309 Object* result = unchecked_previous(); 310 ASSERT(IsBootstrappingOrContext(result)); 311 return reinterpret_cast<Context*>(result); 312 } 313 void set_previous(Context* context) { set(PREVIOUS_INDEX, context); } 314 315 bool has_extension() { return extension() != NULL; } 316 Object* extension() { return get(EXTENSION_INDEX); } 317 void set_extension(Object* object) { set(EXTENSION_INDEX, object); } 318 319 // Get the context where var declarations will be hoisted to, which 320 // may be the context itself. 321 Context* declaration_context(); 322 323 GlobalObject* global() { 324 Object* result = get(GLOBAL_INDEX); 325 ASSERT(IsBootstrappingOrGlobalObject(result)); 326 return reinterpret_cast<GlobalObject*>(result); 327 } 328 void set_global(GlobalObject* global) { set(GLOBAL_INDEX, global); } 329 330 // Returns a JSGlobalProxy object or null. 331 JSObject* global_proxy(); 332 void set_global_proxy(JSObject* global); 333 334 // The builtins object. 335 JSBuiltinsObject* builtins(); 336 337 // Compute the global context by traversing the context chain. 338 Context* global_context(); 339 340 // Predicates for context types. IsGlobalContext is defined on Object 341 // because we frequently have to know if arbitrary objects are global 342 // contexts. 343 bool IsFunctionContext() { 344 Map* map = this->map(); 345 return map == map->GetHeap()->function_context_map(); 346 } 347 bool IsCatchContext() { 348 Map* map = this->map(); 349 return map == map->GetHeap()->catch_context_map(); 350 } 351 bool IsWithContext() { 352 Map* map = this->map(); 353 return map == map->GetHeap()->with_context_map(); 354 } 355 bool IsBlockContext() { 356 Map* map = this->map(); 357 return map == map->GetHeap()->block_context_map(); 358 } 359 bool IsModuleContext() { 360 Map* map = this->map(); 361 return map == map->GetHeap()->module_context_map(); 362 } 363 364 // Tells whether the global context is marked with out of memory. 365 inline bool has_out_of_memory(); 366 367 // Mark the global context with out of memory. 368 inline void mark_out_of_memory(); 369 370 // A global context hold a list of all functions which have been optimized. 371 void AddOptimizedFunction(JSFunction* function); 372 void RemoveOptimizedFunction(JSFunction* function); 373 Object* OptimizedFunctionsListHead(); 374 void ClearOptimizedFunctions(); 375 376 static int GetContextMapIndexFromElementsKind( 377 ElementsKind elements_kind) { 378 if (elements_kind == FAST_DOUBLE_ELEMENTS) { 379 return Context::DOUBLE_JS_ARRAY_MAP_INDEX; 380 } else if (elements_kind == FAST_ELEMENTS) { 381 return Context::OBJECT_JS_ARRAY_MAP_INDEX; 382 } else { 383 ASSERT(elements_kind == FAST_SMI_ONLY_ELEMENTS); 384 return Context::SMI_JS_ARRAY_MAP_INDEX; 385 } 386 } 387 388 #define GLOBAL_CONTEXT_FIELD_ACCESSORS(index, type, name) \ 389 void set_##name(type* value) { \ 390 ASSERT(IsGlobalContext()); \ 391 set(index, value); \ 392 } \ 393 type* name() { \ 394 ASSERT(IsGlobalContext()); \ 395 return type::cast(get(index)); \ 396 } 397 GLOBAL_CONTEXT_FIELDS(GLOBAL_CONTEXT_FIELD_ACCESSORS) 398 #undef GLOBAL_CONTEXT_FIELD_ACCESSORS 399 400 // Lookup the the slot called name, starting with the current context. 401 // There are three possibilities: 402 // 403 // 1) result->IsContext(): 404 // The binding was found in a context. *index is always the 405 // non-negative slot index. *attributes is NONE for var and let 406 // declarations, READ_ONLY for const declarations (never ABSENT). 407 // 408 // 2) result->IsJSObject(): 409 // The binding was found as a named property in a context extension 410 // object (i.e., was introduced via eval), as a property on the subject 411 // of with, or as a property of the global object. *index is -1 and 412 // *attributes is not ABSENT. 413 // 414 // 3) result.is_null(): 415 // There was no binding found, *index is always -1 and *attributes is 416 // always ABSENT. 417 Handle<Object> Lookup(Handle<String> name, 418 ContextLookupFlags flags, 419 int* index, 420 PropertyAttributes* attributes, 421 BindingFlags* binding_flags); 422 423 // Code generation support. 424 static int SlotOffset(int index) { 425 return kHeaderSize + index * kPointerSize - kHeapObjectTag; 426 } 427 428 static const int kSize = kHeaderSize + GLOBAL_CONTEXT_SLOTS * kPointerSize; 429 430 // GC support. 431 typedef FixedBodyDescriptor< 432 kHeaderSize, kSize, kSize> ScavengeBodyDescriptor; 433 434 typedef FixedBodyDescriptor< 435 kHeaderSize, 436 kHeaderSize + FIRST_WEAK_SLOT * kPointerSize, 437 kSize> MarkCompactBodyDescriptor; 438 439 private: 440 // Unchecked access to the slots. 441 Object* unchecked_previous() { return get(PREVIOUS_INDEX); } 442 443 #ifdef DEBUG 444 // Bootstrapping-aware type checks. 445 static bool IsBootstrappingOrContext(Object* object); 446 static bool IsBootstrappingOrGlobalObject(Object* object); 447 #endif 448 }; 449 450 } } // namespace v8::internal 451 452 #endif // V8_CONTEXTS_H_ 453
