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Side by Side Diff: src/contexts.h

Issue 8404030: Version 3.7.1 (Closed) Base URL: http://v8.googlecode.com/svn/trunk/
Patch Set: Created 9 years, 1 month ago
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1 // Copyright 2011 the V8 project authors. All rights reserved. 1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without 2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are 3 // modification, are permitted provided that the following conditions are
4 // met: 4 // met:
5 // 5 //
6 // * Redistributions of source code must retain the above copyright 6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer. 7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above 8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following 9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided 10 // disclaimer in the documentation and/or other materials provided
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39 FOLLOW_CONTEXT_CHAIN = 1, 39 FOLLOW_CONTEXT_CHAIN = 1,
40 FOLLOW_PROTOTYPE_CHAIN = 2, 40 FOLLOW_PROTOTYPE_CHAIN = 2,
41 41
42 DONT_FOLLOW_CHAINS = 0, 42 DONT_FOLLOW_CHAINS = 0,
43 FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN 43 FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN
44 }; 44 };
45 45
46 46
47 // ES5 10.2 defines lexical environments with mutable and immutable bindings. 47 // ES5 10.2 defines lexical environments with mutable and immutable bindings.
48 // Immutable bindings have two states, initialized and uninitialized, and 48 // Immutable bindings have two states, initialized and uninitialized, and
49 // their state is changed by the InitializeImmutableBinding method. 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.
50 // 62 //
51 // The harmony proposal for block scoped bindings also introduces the 63 // The harmony proposal for block scoped bindings also introduces the
52 // uninitialized state for mutable bindings. A 'let' declared variable 64 // uninitialized state for mutable bindings.
53 // is a mutable binding that is created uninitalized upon activation of its 65 // * A 'let' declared variable. They are initialized when evaluating the
54 // lexical environment and it is initialized when evaluating its declaration 66 // corresponding declaration statement. They need to be checked for being
55 // statement. Var declared variables are mutable bindings that are 67 // initialized and thus get the flag MUTABLE_CHECK_INITIALIZED.
56 // immediately initialized upon creation. The BindingFlags enum represents 68 // * A 'var' declared variable. It is initialized immediately upon creation
57 // information if a binding has definitely been initialized. 'const' declared 69 // and thus doesn't need to be checked. It gets the flag
58 // variables are created as uninitialized immutable bindings. 70 // MUTABLE_IS_INITIALIZED.
59 71 // * Catch bound variables, function parameters and variables introduced by
60 // In harmony mode accessing an uninitialized binding produces a reference 72 // function declarations are initialized immediately and do not need to be
61 // error. 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.
62 enum BindingFlags { 79 enum BindingFlags {
63 MUTABLE_IS_INITIALIZED, 80 MUTABLE_IS_INITIALIZED,
64 MUTABLE_CHECK_INITIALIZED, 81 MUTABLE_CHECK_INITIALIZED,
65 IMMUTABLE_IS_INITIALIZED, 82 IMMUTABLE_IS_INITIALIZED,
66 IMMUTABLE_CHECK_INITIALIZED, 83 IMMUTABLE_CHECK_INITIALIZED,
84 IMMUTABLE_IS_INITIALIZED_HARMONY,
85 IMMUTABLE_CHECK_INITIALIZED_HARMONY,
67 MISSING_BINDING 86 MISSING_BINDING
68 }; 87 };
69 88
70 89
71 // Heap-allocated activation contexts. 90 // Heap-allocated activation contexts.
72 // 91 //
73 // Contexts are implemented as FixedArray objects; the Context 92 // Contexts are implemented as FixedArray objects; the Context
74 // class is a convenience interface casted on a FixedArray object. 93 // class is a convenience interface casted on a FixedArray object.
75 // 94 //
76 // Note: Context must have no virtual functions and Context objects 95 // Note: Context must have no virtual functions and Context objects
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131 V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \ 150 V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \
132 V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \ 151 V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \
133 V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \ 152 V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \
134 V(MAP_CACHE_INDEX, Object, map_cache) \ 153 V(MAP_CACHE_INDEX, Object, map_cache) \
135 V(CONTEXT_DATA_INDEX, Object, data) \ 154 V(CONTEXT_DATA_INDEX, Object, data) \
136 V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \ 155 V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \
137 V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \ 156 V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \
138 to_complete_property_descriptor) \ 157 to_complete_property_descriptor) \
139 V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \ 158 V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \
140 V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \ 159 V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \
141 V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) 160 V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) \
161 V(PROXY_ENUMERATE, JSFunction, proxy_enumerate) \
162 V(RANDOM_SEED_INDEX, ByteArray, random_seed)
142 163
143 // JSFunctions are pairs (context, function code), sometimes also called 164 // JSFunctions are pairs (context, function code), sometimes also called
144 // closures. A Context object is used to represent function contexts and 165 // closures. A Context object is used to represent function contexts and
145 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak). 166 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak).
146 // 167 //
147 // At runtime, the contexts build a stack in parallel to the execution 168 // At runtime, the contexts build a stack in parallel to the execution
148 // stack, with the top-most context being the current context. All contexts 169 // stack, with the top-most context being the current context. All contexts
149 // have the following slots: 170 // have the following slots:
150 // 171 //
151 // [ closure ] This is the current function. It is the same for all 172 // [ closure ] This is the current function. It is the same for all
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187 return reinterpret_cast<Context*>(context); 208 return reinterpret_cast<Context*>(context);
188 } 209 }
189 210
190 // The default context slot layout; indices are FixedArray slot indices. 211 // The default context slot layout; indices are FixedArray slot indices.
191 enum { 212 enum {
192 // These slots are in all contexts. 213 // These slots are in all contexts.
193 CLOSURE_INDEX, 214 CLOSURE_INDEX,
194 PREVIOUS_INDEX, 215 PREVIOUS_INDEX,
195 // The extension slot is used for either the global object (in global 216 // The extension slot is used for either the global object (in global
196 // contexts), eval extension object (function contexts), subject of with 217 // contexts), eval extension object (function contexts), subject of with
197 // (with contexts), or the variable name (catch contexts). 218 // (with contexts), or the variable name (catch contexts), the serialized
219 // scope info (block contexts).
198 EXTENSION_INDEX, 220 EXTENSION_INDEX,
199 GLOBAL_INDEX, 221 GLOBAL_INDEX,
200 MIN_CONTEXT_SLOTS, 222 MIN_CONTEXT_SLOTS,
201 223
202 // This slot holds the thrown value in catch contexts. 224 // This slot holds the thrown value in catch contexts.
203 THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS, 225 THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,
204 226
205 // These slots are only in global contexts. 227 // These slots are only in global contexts.
206 GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS, 228 GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS,
207 SECURITY_TOKEN_INDEX, 229 SECURITY_TOKEN_INDEX,
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251 SCRIPT_FUNCTION_INDEX, 273 SCRIPT_FUNCTION_INDEX,
252 OPAQUE_REFERENCE_FUNCTION_INDEX, 274 OPAQUE_REFERENCE_FUNCTION_INDEX,
253 CONTEXT_EXTENSION_FUNCTION_INDEX, 275 CONTEXT_EXTENSION_FUNCTION_INDEX,
254 OUT_OF_MEMORY_INDEX, 276 OUT_OF_MEMORY_INDEX,
255 CONTEXT_DATA_INDEX, 277 CONTEXT_DATA_INDEX,
256 ALLOW_CODE_GEN_FROM_STRINGS_INDEX, 278 ALLOW_CODE_GEN_FROM_STRINGS_INDEX,
257 TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, 279 TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX,
258 DERIVED_HAS_TRAP_INDEX, 280 DERIVED_HAS_TRAP_INDEX,
259 DERIVED_GET_TRAP_INDEX, 281 DERIVED_GET_TRAP_INDEX,
260 DERIVED_SET_TRAP_INDEX, 282 DERIVED_SET_TRAP_INDEX,
283 PROXY_ENUMERATE,
284 RANDOM_SEED_INDEX,
261 285
262 // Properties from here are treated as weak references by the full GC. 286 // Properties from here are treated as weak references by the full GC.
263 // Scavenge treats them as strong references. 287 // Scavenge treats them as strong references.
264 OPTIMIZED_FUNCTIONS_LIST, // Weak. 288 OPTIMIZED_FUNCTIONS_LIST, // Weak.
265 MAP_CACHE_INDEX, // Weak. 289 MAP_CACHE_INDEX, // Weak.
266 NEXT_CONTEXT_LINK, // Weak. 290 NEXT_CONTEXT_LINK, // Weak.
267 291
268 // Total number of slots. 292 // Total number of slots.
269 GLOBAL_CONTEXT_SLOTS, 293 GLOBAL_CONTEXT_SLOTS,
270 294
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378 // context. Do not consider context extension objects. This is 402 // context. Do not consider context extension objects. This is
379 // used for compiling code using eval. If the context surrounding 403 // used for compiling code using eval. If the context surrounding
380 // the eval call does not have a local variable with this name and 404 // the eval call does not have a local variable with this name and
381 // does not contain a with statement the property is global unless 405 // does not contain a with statement the property is global unless
382 // it is shadowed by a property in an extension object introduced by 406 // it is shadowed by a property in an extension object introduced by
383 // eval. 407 // eval.
384 bool GlobalIfNotShadowedByEval(Handle<String> name); 408 bool GlobalIfNotShadowedByEval(Handle<String> name);
385 409
386 // Determine if any function scope in the context call eval and if 410 // Determine if any function scope in the context call eval and if
387 // any of those calls are in non-strict mode. 411 // any of those calls are in non-strict mode.
388 void ComputeEvalScopeInfo(bool* outer_scope_calls_eval, 412 void ComputeEvalScopeInfo(bool* outer_scope_calls_non_strict_eval);
389 bool* outer_scope_calls_non_strict_eval);
390 413
391 // Code generation support. 414 // Code generation support.
392 static int SlotOffset(int index) { 415 static int SlotOffset(int index) {
393 return kHeaderSize + index * kPointerSize - kHeapObjectTag; 416 return kHeaderSize + index * kPointerSize - kHeapObjectTag;
394 } 417 }
395 418
396 static const int kSize = kHeaderSize + GLOBAL_CONTEXT_SLOTS * kPointerSize; 419 static const int kSize = kHeaderSize + GLOBAL_CONTEXT_SLOTS * kPointerSize;
397 420
398 // GC support. 421 // GC support.
399 typedef FixedBodyDescriptor< 422 typedef FixedBodyDescriptor<
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411 #ifdef DEBUG 434 #ifdef DEBUG
412 // Bootstrapping-aware type checks. 435 // Bootstrapping-aware type checks.
413 static bool IsBootstrappingOrContext(Object* object); 436 static bool IsBootstrappingOrContext(Object* object);
414 static bool IsBootstrappingOrGlobalObject(Object* object); 437 static bool IsBootstrappingOrGlobalObject(Object* object);
415 #endif 438 #endif
416 }; 439 };
417 440
418 } } // namespace v8::internal 441 } } // namespace v8::internal
419 442
420 #endif // V8_CONTEXTS_H_ 443 #endif // V8_CONTEXTS_H_
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