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// Copyright 2011 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.
#include "v8.h"
#include "bootstrapper.h"
#include "debug.h"
#include "scopeinfo.h"
namespace v8 {
namespace internal {
Context* Context::declaration_context() {
Context* current = this;
while (!current->IsFunctionContext() && !current->IsGlobalContext()) {
current = current->previous();
ASSERT(current->closure() == closure());
}
return current;
}
JSBuiltinsObject* Context::builtins() {
GlobalObject* object = global();
if (object->IsJSGlobalObject()) {
return JSGlobalObject::cast(object)->builtins();
} else {
ASSERT(object->IsJSBuiltinsObject());
return JSBuiltinsObject::cast(object);
}
}
Context* Context::global_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()->IsGlobalObject()) {
return global()->global_context();
}
// During bootstrapping, the global object might not be set and we
// have to search the context chain to find the global context.
ASSERT(Isolate::Current()->bootstrapper()->IsActive());
Context* current = this;
while (!current->IsGlobalContext()) {
JSFunction* closure = JSFunction::cast(current->closure());
current = Context::cast(closure->context());
}
return current;
}
JSObject* Context::global_proxy() {
return global_context()->global_proxy_object();
}
void Context::set_global_proxy(JSObject* object) {
global_context()->set_global_proxy_object(object);
}
Handle<Object> Context::Lookup(Handle<String> name,
ContextLookupFlags flags,
int* index_,
PropertyAttributes* attributes) {
Isolate* isolate = GetIsolate();
Handle<Context> context(this, isolate);
bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0;
*index_ = -1;
*attributes = ABSENT;
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->IsGlobalContext()) PrintF(" (global context)");
PrintF("\n");
}
// Check extension/with/global object.
if (!context->IsBlockContext() && context->has_extension()) {
if (context->IsCatchContext()) {
// Catch contexts have the variable name in the extension slot.
if (name->Equals(String::cast(context->extension()))) {
if (FLAG_trace_contexts) {
PrintF("=> found in catch context\n");
}
*index_ = Context::THROWN_OBJECT_INDEX;
*attributes = NONE;
return context;
}
} else {
ASSERT(context->IsGlobalContext() ||
context->IsFunctionContext() ||
context->IsWithContext());
// Global, function, and with contexts may have an object in the
// extension slot.
Handle<JSObject> extension(JSObject::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.
if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 ||
extension->IsJSContextExtensionObject()) {
*attributes = extension->GetLocalPropertyAttribute(*name);
} else {
*attributes = extension->GetPropertyAttribute(*name);
}
if (*attributes != ABSENT) {
// property found
if (FLAG_trace_contexts) {
PrintF("=> found property in context object %p\n",
reinterpret_cast<void*>(*extension));
}
return extension;
}
}
}
// Check serialized scope information of functions and blocks. Only
// functions can have parameters, and a function name.
if (context->IsFunctionContext() || context->IsBlockContext()) {
// We may have context-local slots. Check locals in the context.
Handle<SerializedScopeInfo> scope_info;
if (context->IsFunctionContext()) {
scope_info = Handle<SerializedScopeInfo>(
context->closure()->shared()->scope_info(), isolate);
} else {
ASSERT(context->IsBlockContext());
scope_info = Handle<SerializedScopeInfo>(
SerializedScopeInfo::cast(context->extension()), isolate);
}
Variable::Mode mode;
int index = scope_info->ContextSlotIndex(*name, &mode);
ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS);
if (index >= 0) {
if (FLAG_trace_contexts) {
PrintF("=> found local in context slot %d (mode = %d)\n",
index, mode);
}
*index_ = 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 Variable::INTERNAL: // Fall through.
case Variable::VAR:
case Variable::LET:
*attributes = NONE;
break;
case Variable::CONST:
*attributes = READ_ONLY;
break;
case Variable::DYNAMIC:
case Variable::DYNAMIC_GLOBAL:
case Variable::DYNAMIC_LOCAL:
case Variable::TEMPORARY:
UNREACHABLE();
break;
}
return context;
}
// Check the slot corresponding to the intermediate context holding
// only the function name variable.
if (follow_context_chain) {
int index = scope_info->FunctionContextSlotIndex(*name);
if (index >= 0) {
if (FLAG_trace_contexts) {
PrintF("=> found intermediate function in context slot %d\n",
index);
}
*index_ = index;
*attributes = READ_ONLY;
return context;
}
}
}
// Proceed with the previous context.
if (context->IsGlobalContext()) {
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();
}
bool Context::GlobalIfNotShadowedByEval(Handle<String> name) {
Context* context = this;
// Check that there is no local with the given name in contexts
// before the global context and check that there are no context
// extension objects (conservative check for with statements).
while (!context->IsGlobalContext()) {
// Check if the context is a catch or with context, or has introduced
// bindings by calling non-strict eval.
if (context->has_extension()) return false;
// Not a with context so it must be a function context.
ASSERT(context->IsFunctionContext());
// Check non-parameter locals.
Handle<SerializedScopeInfo> scope_info(
context->closure()->shared()->scope_info());
Variable::Mode mode;
int index = scope_info->ContextSlotIndex(*name, &mode);
ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS);
if (index >= 0) return false;
// Check parameter locals.
int param_index = scope_info->ParameterIndex(*name);
if (param_index >= 0) return false;
// Check context only holding the function name variable.
index = scope_info->FunctionContextSlotIndex(*name);
if (index >= 0) return false;
context = context->previous();
}
// No local or potential with statement found so the variable is
// global unless it is shadowed by an eval-introduced variable.
return true;
}
void Context::ComputeEvalScopeInfo(bool* outer_scope_calls_eval,
bool* outer_scope_calls_non_strict_eval) {
// Skip up the context chain checking all the function contexts to see
// whether they call eval.
Context* context = this;
while (!context->IsGlobalContext()) {
if (context->IsFunctionContext()) {
Handle<SerializedScopeInfo> scope_info(
context->closure()->shared()->scope_info());
if (scope_info->CallsEval()) {
*outer_scope_calls_eval = true;
if (!scope_info->IsStrictMode()) {
// No need to go further since the answers will not change from
// here.
*outer_scope_calls_non_strict_eval = true;
return;
}
}
}
context = context->previous();
}
}
void Context::AddOptimizedFunction(JSFunction* function) {
ASSERT(IsGlobalContext());
#ifdef DEBUG
Object* element = get(OPTIMIZED_FUNCTIONS_LIST);
while (!element->IsUndefined()) {
CHECK(element != function);
element = JSFunction::cast(element)->next_function_link();
}
CHECK(function->next_function_link()->IsUndefined());
// Check that the context belongs to the weak global contexts list.
bool found = false;
Object* context = GetHeap()->global_contexts_list();
while (!context->IsUndefined()) {
if (context == this) {
found = true;
break;
}
context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
}
CHECK(found);
#endif
function->set_next_function_link(get(OPTIMIZED_FUNCTIONS_LIST));
set(OPTIMIZED_FUNCTIONS_LIST, function);
}
void Context::RemoveOptimizedFunction(JSFunction* function) {
ASSERT(IsGlobalContext());
Object* element = get(OPTIMIZED_FUNCTIONS_LIST);
JSFunction* prev = NULL;
while (!element->IsUndefined()) {
JSFunction* element_function = JSFunction::cast(element);
ASSERT(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();
}
Object* Context::OptimizedFunctionsListHead() {
ASSERT(IsGlobalContext());
return get(OPTIMIZED_FUNCTIONS_LIST);
}
void Context::ClearOptimizedFunctions() {
set(OPTIMIZED_FUNCTIONS_LIST, GetHeap()->undefined_value());
}
#ifdef DEBUG
bool Context::IsBootstrappingOrContext(Object* object) {
// During bootstrapping we allow all objects to pass as
// contexts. This is necessary to fix circular dependencies.
return Isolate::Current()->bootstrapper()->IsActive() || object->IsContext();
}
bool Context::IsBootstrappingOrGlobalObject(Object* object) {
// During bootstrapping we allow all objects to pass as global
// objects. This is necessary to fix circular dependencies.
Isolate* isolate = Isolate::Current();
return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
isolate->bootstrapper()->IsActive() ||
object->IsGlobalObject();
}
#endif
} } // namespace v8::internal