v8/src/contexts.cc

419 lines
14 KiB
C++

// Copyright 2011 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/v8.h"
#include "src/bootstrapper.h"
#include "src/debug.h"
#include "src/scopeinfo.h"
namespace v8 {
namespace internal {
Context* Context::declaration_context() {
Context* current = this;
while (!current->IsFunctionContext() && !current->IsNativeContext()) {
current = current->previous();
DCHECK(current->closure() == closure());
}
return current;
}
JSBuiltinsObject* Context::builtins() {
GlobalObject* object = global_object();
if (object->IsJSGlobalObject()) {
return JSGlobalObject::cast(object)->builtins();
} else {
DCHECK(object->IsJSBuiltinsObject());
return JSBuiltinsObject::cast(object);
}
}
Context* Context::global_context() {
Context* current = this;
while (!current->IsGlobalContext()) {
current = current->previous();
}
return current;
}
Context* Context::native_context() {
// Fast case: the global object for this context has been set. In
// that case, the global object has a direct pointer to the global
// context.
if (global_object()->IsGlobalObject()) {
return global_object()->native_context();
}
// During bootstrapping, the global object might not be set and we
// have to search the context chain to find the native context.
DCHECK(this->GetIsolate()->bootstrapper()->IsActive());
Context* current = this;
while (!current->IsNativeContext()) {
JSFunction* closure = JSFunction::cast(current->closure());
current = Context::cast(closure->context());
}
return current;
}
JSObject* Context::global_proxy() {
return native_context()->global_proxy_object();
}
void Context::set_global_proxy(JSObject* object) {
native_context()->set_global_proxy_object(object);
}
/**
* Lookups a property in an object environment, taking the unscopables into
* account. This is used For HasBinding spec algorithms for ObjectEnvironment.
*/
static Maybe<PropertyAttributes> UnscopableLookup(LookupIterator* it) {
Isolate* isolate = it->isolate();
Maybe<PropertyAttributes> attrs = JSReceiver::GetPropertyAttributes(it);
DCHECK(attrs.has_value || isolate->has_pending_exception());
if (!attrs.has_value || attrs.value == ABSENT) return attrs;
Handle<Symbol> unscopables_symbol(
isolate->native_context()->unscopables_symbol(), isolate);
Handle<Object> receiver = it->GetReceiver();
Handle<Object> unscopables;
MaybeHandle<Object> maybe_unscopables =
Object::GetProperty(receiver, unscopables_symbol);
if (!maybe_unscopables.ToHandle(&unscopables)) {
return Maybe<PropertyAttributes>();
}
if (!unscopables->IsSpecObject()) return attrs;
Maybe<bool> blacklist = JSReceiver::HasProperty(
Handle<JSReceiver>::cast(unscopables), it->name());
if (!blacklist.has_value) {
DCHECK(isolate->has_pending_exception());
return Maybe<PropertyAttributes>();
}
if (blacklist.value) return maybe(ABSENT);
return attrs;
}
Handle<Object> Context::Lookup(Handle<String> name,
ContextLookupFlags flags,
int* index,
PropertyAttributes* attributes,
BindingFlags* binding_flags) {
Isolate* isolate = GetIsolate();
Handle<Context> context(this, isolate);
bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0;
*index = -1;
*attributes = ABSENT;
*binding_flags = MISSING_BINDING;
if (FLAG_trace_contexts) {
PrintF("Context::Lookup(");
name->ShortPrint();
PrintF(")\n");
}
do {
if (FLAG_trace_contexts) {
PrintF(" - looking in context %p", reinterpret_cast<void*>(*context));
if (context->IsNativeContext()) PrintF(" (native context)");
PrintF("\n");
}
// 1. Check global objects, subjects of with, and extension objects.
if (context->IsNativeContext() ||
context->IsWithContext() ||
(context->IsFunctionContext() && context->has_extension())) {
Handle<JSReceiver> object(
JSReceiver::cast(context->extension()), isolate);
// Context extension objects needs to behave as if they have no
// prototype. So even if we want to follow prototype chains, we need
// to only do a local lookup for context extension objects.
Maybe<PropertyAttributes> maybe;
if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 ||
object->IsJSContextExtensionObject()) {
maybe = JSReceiver::GetOwnPropertyAttributes(object, name);
} else if (context->IsWithContext()) {
LookupIterator it(object, name);
maybe = UnscopableLookup(&it);
} else {
maybe = JSReceiver::GetPropertyAttributes(object, name);
}
if (!maybe.has_value) return Handle<Object>();
DCHECK(!isolate->has_pending_exception());
*attributes = maybe.value;
if (maybe.value != ABSENT) {
if (FLAG_trace_contexts) {
PrintF("=> found property in context object %p\n",
reinterpret_cast<void*>(*object));
}
return object;
}
}
// 2. Check the context proper if it has slots.
if (context->IsFunctionContext() || context->IsBlockContext()) {
// Use serialized scope information of functions and blocks to search
// for the context index.
Handle<ScopeInfo> scope_info;
if (context->IsFunctionContext()) {
scope_info = Handle<ScopeInfo>(
context->closure()->shared()->scope_info(), isolate);
} else {
scope_info = Handle<ScopeInfo>(
ScopeInfo::cast(context->extension()), isolate);
}
VariableMode mode;
InitializationFlag init_flag;
// TODO(sigurds) Figure out whether maybe_assigned_flag should
// be used to compute binding_flags.
MaybeAssignedFlag maybe_assigned_flag;
int slot_index = ScopeInfo::ContextSlotIndex(
scope_info, name, &mode, &init_flag, &maybe_assigned_flag);
DCHECK(slot_index < 0 || slot_index >= MIN_CONTEXT_SLOTS);
if (slot_index >= 0) {
if (FLAG_trace_contexts) {
PrintF("=> found local in context slot %d (mode = %d)\n",
slot_index, mode);
}
*index = slot_index;
// Note: Fixed context slots are statically allocated by the compiler.
// Statically allocated variables always have a statically known mode,
// which is the mode with which they were declared when added to the
// scope. Thus, the DYNAMIC mode (which corresponds to dynamically
// declared variables that were introduced through declaration nodes)
// must not appear here.
switch (mode) {
case INTERNAL: // Fall through.
case VAR:
*attributes = NONE;
*binding_flags = MUTABLE_IS_INITIALIZED;
break;
case LET:
*attributes = NONE;
*binding_flags = (init_flag == kNeedsInitialization)
? MUTABLE_CHECK_INITIALIZED : MUTABLE_IS_INITIALIZED;
break;
case CONST_LEGACY:
*attributes = READ_ONLY;
*binding_flags = (init_flag == kNeedsInitialization)
? IMMUTABLE_CHECK_INITIALIZED : IMMUTABLE_IS_INITIALIZED;
break;
case CONST:
*attributes = READ_ONLY;
*binding_flags = (init_flag == kNeedsInitialization)
? IMMUTABLE_CHECK_INITIALIZED_HARMONY :
IMMUTABLE_IS_INITIALIZED_HARMONY;
break;
case MODULE:
*attributes = READ_ONLY;
*binding_flags = IMMUTABLE_IS_INITIALIZED_HARMONY;
break;
case DYNAMIC:
case DYNAMIC_GLOBAL:
case DYNAMIC_LOCAL:
case TEMPORARY:
UNREACHABLE();
break;
}
return context;
}
// Check the slot corresponding to the intermediate context holding
// only the function name variable.
if (follow_context_chain && context->IsFunctionContext()) {
VariableMode mode;
int function_index = scope_info->FunctionContextSlotIndex(*name, &mode);
if (function_index >= 0) {
if (FLAG_trace_contexts) {
PrintF("=> found intermediate function in context slot %d\n",
function_index);
}
*index = function_index;
*attributes = READ_ONLY;
DCHECK(mode == CONST_LEGACY || mode == CONST);
*binding_flags = (mode == CONST_LEGACY)
? IMMUTABLE_IS_INITIALIZED : IMMUTABLE_IS_INITIALIZED_HARMONY;
return context;
}
}
} else if (context->IsCatchContext()) {
// Catch contexts have the variable name in the extension slot.
if (String::Equals(name, handle(String::cast(context->extension())))) {
if (FLAG_trace_contexts) {
PrintF("=> found in catch context\n");
}
*index = Context::THROWN_OBJECT_INDEX;
*attributes = NONE;
*binding_flags = MUTABLE_IS_INITIALIZED;
return context;
}
}
// 3. Prepare to continue with the previous (next outermost) context.
if (context->IsNativeContext()) {
follow_context_chain = false;
} else {
context = Handle<Context>(context->previous(), isolate);
}
} while (follow_context_chain);
if (FLAG_trace_contexts) {
PrintF("=> no property/slot found\n");
}
return Handle<Object>::null();
}
void Context::AddOptimizedFunction(JSFunction* function) {
DCHECK(IsNativeContext());
#ifdef ENABLE_SLOW_DCHECKS
if (FLAG_enable_slow_asserts) {
Object* element = get(OPTIMIZED_FUNCTIONS_LIST);
while (!element->IsUndefined()) {
CHECK(element != function);
element = JSFunction::cast(element)->next_function_link();
}
}
// Check that the context belongs to the weak native contexts list.
bool found = false;
Object* context = GetHeap()->native_contexts_list();
while (!context->IsUndefined()) {
if (context == this) {
found = true;
break;
}
context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
}
CHECK(found);
#endif
// If the function link field is already used then the function was
// enqueued as a code flushing candidate and we remove it now.
if (!function->next_function_link()->IsUndefined()) {
CodeFlusher* flusher = GetHeap()->mark_compact_collector()->code_flusher();
flusher->EvictCandidate(function);
}
DCHECK(function->next_function_link()->IsUndefined());
function->set_next_function_link(get(OPTIMIZED_FUNCTIONS_LIST));
set(OPTIMIZED_FUNCTIONS_LIST, function);
}
void Context::RemoveOptimizedFunction(JSFunction* function) {
DCHECK(IsNativeContext());
Object* element = get(OPTIMIZED_FUNCTIONS_LIST);
JSFunction* prev = NULL;
while (!element->IsUndefined()) {
JSFunction* element_function = JSFunction::cast(element);
DCHECK(element_function->next_function_link()->IsUndefined() ||
element_function->next_function_link()->IsJSFunction());
if (element_function == function) {
if (prev == NULL) {
set(OPTIMIZED_FUNCTIONS_LIST, element_function->next_function_link());
} else {
prev->set_next_function_link(element_function->next_function_link());
}
element_function->set_next_function_link(GetHeap()->undefined_value());
return;
}
prev = element_function;
element = element_function->next_function_link();
}
UNREACHABLE();
}
void Context::SetOptimizedFunctionsListHead(Object* head) {
DCHECK(IsNativeContext());
set(OPTIMIZED_FUNCTIONS_LIST, head);
}
Object* Context::OptimizedFunctionsListHead() {
DCHECK(IsNativeContext());
return get(OPTIMIZED_FUNCTIONS_LIST);
}
void Context::AddOptimizedCode(Code* code) {
DCHECK(IsNativeContext());
DCHECK(code->kind() == Code::OPTIMIZED_FUNCTION);
DCHECK(code->next_code_link()->IsUndefined());
code->set_next_code_link(get(OPTIMIZED_CODE_LIST));
set(OPTIMIZED_CODE_LIST, code);
}
void Context::SetOptimizedCodeListHead(Object* head) {
DCHECK(IsNativeContext());
set(OPTIMIZED_CODE_LIST, head);
}
Object* Context::OptimizedCodeListHead() {
DCHECK(IsNativeContext());
return get(OPTIMIZED_CODE_LIST);
}
void Context::SetDeoptimizedCodeListHead(Object* head) {
DCHECK(IsNativeContext());
set(DEOPTIMIZED_CODE_LIST, head);
}
Object* Context::DeoptimizedCodeListHead() {
DCHECK(IsNativeContext());
return get(DEOPTIMIZED_CODE_LIST);
}
Handle<Object> Context::ErrorMessageForCodeGenerationFromStrings() {
Isolate* isolate = GetIsolate();
Handle<Object> result(error_message_for_code_gen_from_strings(), isolate);
if (!result->IsUndefined()) return result;
return isolate->factory()->NewStringFromStaticChars(
"Code generation from strings disallowed for this context");
}
#ifdef DEBUG
bool Context::IsBootstrappingOrValidParentContext(
Object* object, Context* child) {
// During bootstrapping we allow all objects to pass as
// contexts. This is necessary to fix circular dependencies.
if (child->GetIsolate()->bootstrapper()->IsActive()) return true;
if (!object->IsContext()) return false;
Context* context = Context::cast(object);
return context->IsNativeContext() || context->IsGlobalContext() ||
context->IsModuleContext() || !child->IsModuleContext();
}
bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
// During bootstrapping we allow all objects to pass as global
// objects. This is necessary to fix circular dependencies.
return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
isolate->bootstrapper()->IsActive() ||
object->IsGlobalObject();
}
#endif
} } // namespace v8::internal