// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_CONTEXTS_H_
#define V8_CONTEXTS_H_
#include "heap.h"
#include "objects.h"
namespace v8 {
namespace internal {
enum ContextLookupFlags {
FOLLOW_CONTEXT_CHAIN = 1,
FOLLOW_PROTOTYPE_CHAIN = 2,
DONT_FOLLOW_CHAINS = 0,
FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN
};
// ES5 10.2 defines lexical environments with mutable and immutable bindings.
// Immutable bindings have two states, initialized and uninitialized, and
// their state is changed by the InitializeImmutableBinding method. The
// BindingFlags enum represents information if a binding has definitely been
// initialized. A mutable binding does not need to be checked and thus has
// the BindingFlag MUTABLE_IS_INITIALIZED.
//
// There are two possibilities for immutable bindings
// * 'const' declared variables. They are initialized when evaluating the
// corresponding declaration statement. They need to be checked for being
// initialized and thus get the flag IMMUTABLE_CHECK_INITIALIZED.
// * The function name of a named function literal. The binding is immediately
// initialized when entering the function and thus does not need to be
// checked. it gets the BindingFlag IMMUTABLE_IS_INITIALIZED.
// Accessing an uninitialized binding produces the undefined value.
//
// The harmony proposal for block scoped bindings also introduces the
// uninitialized state for mutable bindings.
// * A 'let' declared variable. They are initialized when evaluating the
// corresponding declaration statement. They need to be checked for being
// initialized and thus get the flag MUTABLE_CHECK_INITIALIZED.
// * A 'var' declared variable. It is initialized immediately upon creation
// and thus doesn't need to be checked. It gets the flag
// MUTABLE_IS_INITIALIZED.
// * Catch bound variables, function parameters and variables introduced by
// function declarations are initialized immediately and do not need to be
// checked. Thus they get the flag MUTABLE_IS_INITIALIZED.
// Immutable bindings in harmony mode get the _HARMONY flag variants. Accessing
// an uninitialized binding produces a reference error.
//
// In V8 uninitialized bindings are set to the hole value upon creation and set
// to a different value upon initialization.
enum BindingFlags {
MUTABLE_IS_INITIALIZED,
MUTABLE_CHECK_INITIALIZED,
IMMUTABLE_IS_INITIALIZED,
IMMUTABLE_CHECK_INITIALIZED,
IMMUTABLE_IS_INITIALIZED_HARMONY,
IMMUTABLE_CHECK_INITIALIZED_HARMONY,
MISSING_BINDING
};
// Heap-allocated activation contexts.
//
// Contexts are implemented as FixedArray objects; the Context
// class is a convenience interface casted on a FixedArray object.
//
// Note: Context must have no virtual functions and Context objects
// must always be allocated via Heap::AllocateContext() or
// Factory::NewContext.
#define GLOBAL_CONTEXT_FIELDS(V) \
V(GLOBAL_PROXY_INDEX, JSObject, global_proxy_object) \
V(SECURITY_TOKEN_INDEX, Object, security_token) \
V(BOOLEAN_FUNCTION_INDEX, JSFunction, boolean_function) \
V(NUMBER_FUNCTION_INDEX, JSFunction, number_function) \
V(STRING_FUNCTION_INDEX, JSFunction, string_function) \
V(STRING_FUNCTION_PROTOTYPE_MAP_INDEX, Map, string_function_prototype_map) \
V(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \
V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function) \
V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \
V(SMI_JS_ARRAY_MAP_INDEX, Object, smi_js_array_map) \
V(DOUBLE_JS_ARRAY_MAP_INDEX, Object, double_js_array_map) \
V(OBJECT_JS_ARRAY_MAP_INDEX, Object, object_js_array_map) \
V(DATE_FUNCTION_INDEX, JSFunction, date_function) \
V(JSON_OBJECT_INDEX, JSObject, json_object) \
V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function) \
V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype) \
V(CREATE_DATE_FUN_INDEX, JSFunction, create_date_fun) \
V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun) \
V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun) \
V(TO_DETAIL_STRING_FUN_INDEX, JSFunction, to_detail_string_fun) \
V(TO_OBJECT_FUN_INDEX, JSFunction, to_object_fun) \
V(TO_INTEGER_FUN_INDEX, JSFunction, to_integer_fun) \
V(TO_UINT32_FUN_INDEX, JSFunction, to_uint32_fun) \
V(TO_INT32_FUN_INDEX, JSFunction, to_int32_fun) \
V(GLOBAL_EVAL_FUN_INDEX, JSFunction, global_eval_fun) \
V(INSTANTIATE_FUN_INDEX, JSFunction, instantiate_fun) \
V(CONFIGURE_INSTANCE_FUN_INDEX, JSFunction, configure_instance_fun) \
V(FUNCTION_MAP_INDEX, Map, function_map) \
V(STRICT_MODE_FUNCTION_MAP_INDEX, Map, strict_mode_function_map) \
V(FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, function_without_prototype_map) \
V(STRICT_MODE_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \
strict_mode_function_without_prototype_map) \
V(FUNCTION_INSTANCE_MAP_INDEX, Map, function_instance_map) \
V(STRICT_MODE_FUNCTION_INSTANCE_MAP_INDEX, Map, \
strict_mode_function_instance_map) \
V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map)\
V(ARGUMENTS_BOILERPLATE_INDEX, JSObject, arguments_boilerplate) \
V(ALIASED_ARGUMENTS_BOILERPLATE_INDEX, JSObject, \
aliased_arguments_boilerplate) \
V(STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX, JSObject, \
strict_mode_arguments_boilerplate) \
V(MESSAGE_LISTENERS_INDEX, JSObject, message_listeners) \
V(MAKE_MESSAGE_FUN_INDEX, JSFunction, make_message_fun) \
V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun) \
V(CONFIGURE_GLOBAL_INDEX, JSFunction, configure_global_fun) \
V(FUNCTION_CACHE_INDEX, JSObject, function_cache) \
V(JSFUNCTION_RESULT_CACHES_INDEX, FixedArray, jsfunction_result_caches) \
V(NORMALIZED_MAP_CACHE_INDEX, NormalizedMapCache, normalized_map_cache) \
V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \
V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \
V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction, \
call_as_constructor_delegate) \
V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \
V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \
V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \
V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \
V(MAP_CACHE_INDEX, Object, map_cache) \
V(CONTEXT_DATA_INDEX, Object, data) \
V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \
V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \
to_complete_property_descriptor) \
V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \
V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \
V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) \
V(PROXY_ENUMERATE, JSFunction, proxy_enumerate) \
V(RANDOM_SEED_INDEX, ByteArray, random_seed)
// JSFunctions are pairs (context, function code), sometimes also called
// closures. A Context object is used to represent function contexts and
// dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak).
//
// At runtime, the contexts build a stack in parallel to the execution
// stack, with the top-most context being the current context. All contexts
// have the following slots:
//
// [ closure ] This is the current function. It is the same for all
// contexts inside a function. It provides access to the
// incoming context (i.e., the outer context, which may
// or may not become the current function's context), and
// it provides access to the functions code and thus it's
// scope information, which in turn contains the names of
// statically allocated context slots. The names are needed
// for dynamic lookups in the presence of 'with' or 'eval'.
//
// [ previous ] A pointer to the previous context. It is NULL for
// function contexts, and non-NULL for 'with' contexts.
// Used to implement the 'with' statement.
//
// [ extension ] A pointer to an extension JSObject, or NULL. Used to
// implement 'with' statements and dynamic declarations
// (through 'eval'). The object in a 'with' statement is
// stored in the extension slot of a 'with' context.
// Dynamically declared variables/functions are also added
// to lazily allocated extension object. Context::Lookup
// searches the extension object for properties.
//
// [ global ] A pointer to the global object. Provided for quick
// access to the global object from inside the code (since
// we always have a context pointer).
//
// In addition, function contexts may have statically allocated context slots
// to store local variables/functions that are accessed from inner functions
// (via static context addresses) or through 'eval' (dynamic context lookups).
// Finally, the global context contains additional slots for fast access to
// global properties.
class Context: public FixedArray {
public:
// Conversions.
static Context* cast(Object* context) {
ASSERT(context->IsContext());
return reinterpret_cast<Context*>(context);
}
// The default context slot layout; indices are FixedArray slot indices.
enum {
// These slots are in all contexts.
CLOSURE_INDEX,
PREVIOUS_INDEX,
// The extension slot is used for either the global object (in global
// contexts), eval extension object (function contexts), subject of with
// (with contexts), or the variable name (catch contexts), the serialized
// scope info (block contexts).
EXTENSION_INDEX,
GLOBAL_INDEX,
MIN_CONTEXT_SLOTS,
// This slot holds the thrown value in catch contexts.
THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,
// These slots are only in global contexts.
GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS,
SECURITY_TOKEN_INDEX,
ARGUMENTS_BOILERPLATE_INDEX,
ALIASED_ARGUMENTS_BOILERPLATE_INDEX,
STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX,
REGEXP_RESULT_MAP_INDEX,
FUNCTION_MAP_INDEX,
STRICT_MODE_FUNCTION_MAP_INDEX,
FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX,
STRICT_MODE_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX,
FUNCTION_INSTANCE_MAP_INDEX,
STRICT_MODE_FUNCTION_INSTANCE_MAP_INDEX,
INITIAL_OBJECT_PROTOTYPE_INDEX,
BOOLEAN_FUNCTION_INDEX,
NUMBER_FUNCTION_INDEX,
STRING_FUNCTION_INDEX,
STRING_FUNCTION_PROTOTYPE_MAP_INDEX,
OBJECT_FUNCTION_INDEX,
INTERNAL_ARRAY_FUNCTION_INDEX,
ARRAY_FUNCTION_INDEX,
SMI_JS_ARRAY_MAP_INDEX,
DOUBLE_JS_ARRAY_MAP_INDEX,
OBJECT_JS_ARRAY_MAP_INDEX,
DATE_FUNCTION_INDEX,
JSON_OBJECT_INDEX,
REGEXP_FUNCTION_INDEX,
CREATE_DATE_FUN_INDEX,
TO_NUMBER_FUN_INDEX,
TO_STRING_FUN_INDEX,
TO_DETAIL_STRING_FUN_INDEX,
TO_OBJECT_FUN_INDEX,
TO_INTEGER_FUN_INDEX,
TO_UINT32_FUN_INDEX,
TO_INT32_FUN_INDEX,
TO_BOOLEAN_FUN_INDEX,
GLOBAL_EVAL_FUN_INDEX,
INSTANTIATE_FUN_INDEX,
CONFIGURE_INSTANCE_FUN_INDEX,
MESSAGE_LISTENERS_INDEX,
MAKE_MESSAGE_FUN_INDEX,
GET_STACK_TRACE_LINE_INDEX,
CONFIGURE_GLOBAL_INDEX,
FUNCTION_CACHE_INDEX,
JSFUNCTION_RESULT_CACHES_INDEX,
NORMALIZED_MAP_CACHE_INDEX,
RUNTIME_CONTEXT_INDEX,
CALL_AS_FUNCTION_DELEGATE_INDEX,
CALL_AS_CONSTRUCTOR_DELEGATE_INDEX,
SCRIPT_FUNCTION_INDEX,
OPAQUE_REFERENCE_FUNCTION_INDEX,
CONTEXT_EXTENSION_FUNCTION_INDEX,
OUT_OF_MEMORY_INDEX,
CONTEXT_DATA_INDEX,
ALLOW_CODE_GEN_FROM_STRINGS_INDEX,
TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX,
DERIVED_HAS_TRAP_INDEX,
DERIVED_GET_TRAP_INDEX,
DERIVED_SET_TRAP_INDEX,
PROXY_ENUMERATE,
RANDOM_SEED_INDEX,
// Properties from here are treated as weak references by the full GC.
// Scavenge treats them as strong references.
OPTIMIZED_FUNCTIONS_LIST, // Weak.
MAP_CACHE_INDEX, // Weak.
NEXT_CONTEXT_LINK, // Weak.
// Total number of slots.
GLOBAL_CONTEXT_SLOTS,
FIRST_WEAK_SLOT = OPTIMIZED_FUNCTIONS_LIST
};
// Direct slot access.
JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); }
void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); }
Context* previous() {
Object* result = unchecked_previous();
ASSERT(IsBootstrappingOrContext(result));
return reinterpret_cast<Context*>(result);
}
void set_previous(Context* context) { set(PREVIOUS_INDEX, context); }
bool has_extension() { return extension() != NULL; }
Object* extension() { return get(EXTENSION_INDEX); }
void set_extension(Object* object) { set(EXTENSION_INDEX, object); }
// Get the context where var declarations will be hoisted to, which
// may be the context itself.
Context* declaration_context();
GlobalObject* global() {
Object* result = get(GLOBAL_INDEX);
ASSERT(IsBootstrappingOrGlobalObject(result));
return reinterpret_cast<GlobalObject*>(result);
}
void set_global(GlobalObject* global) { set(GLOBAL_INDEX, global); }
// Returns a JSGlobalProxy object or null.
JSObject* global_proxy();
void set_global_proxy(JSObject* global);
// The builtins object.
JSBuiltinsObject* builtins();
// Compute the global context by traversing the context chain.
Context* global_context();
// Predicates for context types. IsGlobalContext is defined on Object
// because we frequently have to know if arbitrary objects are global
// contexts.
bool IsFunctionContext() {
Map* map = this->map();
return map == map->GetHeap()->function_context_map();
}
bool IsCatchContext() {
Map* map = this->map();
return map == map->GetHeap()->catch_context_map();
}
bool IsWithContext() {
Map* map = this->map();
return map == map->GetHeap()->with_context_map();
}
bool IsBlockContext() {
Map* map = this->map();
return map == map->GetHeap()->block_context_map();
}
bool IsModuleContext() {
Map* map = this->map();
return map == map->GetHeap()->module_context_map();
}
// Tells whether the global context is marked with out of memory.
inline bool has_out_of_memory();
// Mark the global context with out of memory.
inline void mark_out_of_memory();
// A global context hold a list of all functions which have been optimized.
void AddOptimizedFunction(JSFunction* function);
void RemoveOptimizedFunction(JSFunction* function);
Object* OptimizedFunctionsListHead();
void ClearOptimizedFunctions();
static int GetContextMapIndexFromElementsKind(
ElementsKind elements_kind) {
if (elements_kind == FAST_DOUBLE_ELEMENTS) {
return Context::DOUBLE_JS_ARRAY_MAP_INDEX;
} else if (elements_kind == FAST_ELEMENTS) {
return Context::OBJECT_JS_ARRAY_MAP_INDEX;
} else {
ASSERT(elements_kind == FAST_SMI_ONLY_ELEMENTS);
return Context::SMI_JS_ARRAY_MAP_INDEX;
}
}
#define GLOBAL_CONTEXT_FIELD_ACCESSORS(index, type, name) \
void set_##name(type* value) { \
ASSERT(IsGlobalContext()); \
set(index, value); \
} \
type* name() { \
ASSERT(IsGlobalContext()); \
return type::cast(get(index)); \
}
GLOBAL_CONTEXT_FIELDS(GLOBAL_CONTEXT_FIELD_ACCESSORS)
#undef GLOBAL_CONTEXT_FIELD_ACCESSORS
// Lookup the the slot called name, starting with the current context.
// There are three possibilities:
//
// 1) result->IsContext():
// The binding was found in a context. *index is always the
// non-negative slot index. *attributes is NONE for var and let
// declarations, READ_ONLY for const declarations (never ABSENT).
//
// 2) result->IsJSObject():
// The binding was found as a named property in a context extension
// object (i.e., was introduced via eval), as a property on the subject
// of with, or as a property of the global object. *index is -1 and
// *attributes is not ABSENT.
//
// 3) result.is_null():
// There was no binding found, *index is always -1 and *attributes is
// always ABSENT.
Handle<Object> Lookup(Handle<String> name,
ContextLookupFlags flags,
int* index,
PropertyAttributes* attributes,
BindingFlags* binding_flags);
// Code generation support.
static int SlotOffset(int index) {
return kHeaderSize + index * kPointerSize - kHeapObjectTag;
}
static const int kSize = kHeaderSize + GLOBAL_CONTEXT_SLOTS * kPointerSize;
// GC support.
typedef FixedBodyDescriptor<
kHeaderSize, kSize, kSize> ScavengeBodyDescriptor;
typedef FixedBodyDescriptor<
kHeaderSize,
kHeaderSize + FIRST_WEAK_SLOT * kPointerSize,
kSize> MarkCompactBodyDescriptor;
private:
// Unchecked access to the slots.
Object* unchecked_previous() { return get(PREVIOUS_INDEX); }
#ifdef DEBUG
// Bootstrapping-aware type checks.
static bool IsBootstrappingOrContext(Object* object);
static bool IsBootstrappingOrGlobalObject(Object* object);
#endif
};
} } // namespace v8::internal
#endif // V8_CONTEXTS_H_