v8/src/contexts.cc
Igor Sheludko 6767c3dec2 [ic] Encode lexical variable access as a smi in Load/StoreGlobalIC.
This CL removes LoadScriptContextFieldStub and StoreScriptContextFieldStub.

Bug: v8:7206, chromium:576312
Change-Id: I217eeb726ca7d1ec85a67331da4941b9ac2a4b7a
Reviewed-on: https://chromium-review.googlesource.com/831867
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50177}
2017-12-18 22:15:01 +00:00

557 lines
19 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/contexts.h"
#include "src/ast/modules.h"
#include "src/bootstrapper.h"
#include "src/debug/debug.h"
#include "src/isolate-inl.h"
namespace v8 {
namespace internal {
Handle<ScriptContextTable> ScriptContextTable::Extend(
Handle<ScriptContextTable> table, Handle<Context> script_context) {
Handle<ScriptContextTable> result;
int used = table->used();
int length = table->length();
CHECK(used >= 0 && length > 0 && used < length);
if (used + kFirstContextSlotIndex == length) {
CHECK(length < Smi::kMaxValue / 2);
Isolate* isolate = table->GetIsolate();
Handle<FixedArray> copy =
isolate->factory()->CopyFixedArrayAndGrow(table, length);
copy->set_map(isolate->heap()->script_context_table_map());
result = Handle<ScriptContextTable>::cast(copy);
} else {
result = table;
}
result->set_used(used + 1);
DCHECK(script_context->IsScriptContext());
result->set(used + kFirstContextSlotIndex, *script_context);
return result;
}
bool ScriptContextTable::Lookup(Handle<ScriptContextTable> table,
Handle<String> name, LookupResult* result) {
for (int i = 0; i < table->used(); i++) {
Handle<Context> context = GetContext(table, i);
DCHECK(context->IsScriptContext());
Handle<ScopeInfo> scope_info(context->scope_info());
int slot_index = ScopeInfo::ContextSlotIndex(
scope_info, name, &result->mode, &result->init_flag,
&result->maybe_assigned_flag);
if (slot_index >= 0) {
result->context_index = i;
result->slot_index = slot_index;
return true;
}
}
return false;
}
bool Context::is_declaration_context() {
if (IsFunctionContext() || IsNativeContext() || IsScriptContext() ||
IsModuleContext()) {
return true;
}
if (IsEvalContext())
return closure()->shared()->language_mode() == LanguageMode::kStrict;
if (!IsBlockContext()) return false;
Object* ext = extension();
// If we have the special extension, we immediately know it must be a
// declaration scope. That's just a small performance shortcut.
return ext->IsContextExtension() ||
ScopeInfo::cast(ext)->is_declaration_scope();
}
Context* Context::declaration_context() {
Context* current = this;
while (!current->is_declaration_context()) {
current = current->previous();
}
return current;
}
Context* Context::closure_context() {
Context* current = this;
while (!current->IsFunctionContext() && !current->IsScriptContext() &&
!current->IsModuleContext() && !current->IsNativeContext() &&
!current->IsEvalContext()) {
current = current->previous();
DCHECK(current->closure() == closure());
}
return current;
}
JSObject* Context::extension_object() {
DCHECK(IsNativeContext() || IsFunctionContext() || IsBlockContext() ||
IsEvalContext());
HeapObject* object = extension();
if (object->IsTheHole(GetIsolate())) return nullptr;
if (IsBlockContext()) {
if (!object->IsContextExtension()) return nullptr;
object = JSObject::cast(ContextExtension::cast(object)->extension());
}
DCHECK(object->IsJSContextExtensionObject() ||
(IsNativeContext() && object->IsJSGlobalObject()));
return JSObject::cast(object);
}
JSReceiver* Context::extension_receiver() {
DCHECK(IsNativeContext() || IsWithContext() || IsEvalContext() ||
IsFunctionContext() || IsBlockContext());
return IsWithContext() ? JSReceiver::cast(
ContextExtension::cast(extension())->extension())
: extension_object();
}
ScopeInfo* Context::scope_info() {
DCHECK(!IsNativeContext());
if (IsFunctionContext() || IsModuleContext() || IsEvalContext()) {
return closure()->shared()->scope_info();
}
HeapObject* object = extension();
if (object->IsContextExtension()) {
DCHECK(IsBlockContext() || IsCatchContext() || IsWithContext() ||
IsDebugEvaluateContext());
object = ContextExtension::cast(object)->scope_info();
}
return ScopeInfo::cast(object);
}
Module* Context::module() {
Context* current = this;
while (!current->IsModuleContext()) {
current = current->previous();
}
return Module::cast(current->extension());
}
String* Context::catch_name() {
DCHECK(IsCatchContext());
return String::cast(ContextExtension::cast(extension())->extension());
}
JSGlobalObject* Context::global_object() {
return JSGlobalObject::cast(native_context()->extension());
}
Context* Context::script_context() {
Context* current = this;
while (!current->IsScriptContext()) {
current = current->previous();
}
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<bool> UnscopableLookup(LookupIterator* it) {
Isolate* isolate = it->isolate();
Maybe<bool> found = JSReceiver::HasProperty(it);
if (found.IsNothing() || !found.FromJust()) return found;
Handle<Object> unscopables;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate, unscopables,
JSReceiver::GetProperty(Handle<JSReceiver>::cast(it->GetReceiver()),
isolate->factory()->unscopables_symbol()),
Nothing<bool>());
if (!unscopables->IsJSReceiver()) return Just(true);
Handle<Object> blacklist;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate, blacklist,
JSReceiver::GetProperty(Handle<JSReceiver>::cast(unscopables),
it->name()),
Nothing<bool>());
return Just(!blacklist->BooleanValue());
}
static PropertyAttributes GetAttributesForMode(VariableMode mode) {
DCHECK(IsDeclaredVariableMode(mode));
return mode == CONST ? READ_ONLY : NONE;
}
Handle<Object> Context::Lookup(Handle<String> name, ContextLookupFlags flags,
int* index, PropertyAttributes* attributes,
InitializationFlag* init_flag,
VariableMode* variable_mode,
bool* is_sloppy_function_name) {
Isolate* isolate = GetIsolate();
Handle<Context> context(this, isolate);
bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0;
bool failed_whitelist = false;
*index = kNotFound;
*attributes = ABSENT;
*init_flag = kCreatedInitialized;
*variable_mode = VAR;
if (is_sloppy_function_name != nullptr) {
*is_sloppy_function_name = false;
}
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->IsScriptContext()) PrintF(" (script context)");
if (context->IsNativeContext()) PrintF(" (native context)");
PrintF("\n");
}
// 1. Check global objects, subjects of with, and extension objects.
DCHECK_IMPLIES(context->IsEvalContext(),
context->extension()->IsTheHole(isolate));
if ((context->IsNativeContext() ||
(context->IsWithContext() && ((flags & SKIP_WITH_CONTEXT) == 0)) ||
context->IsFunctionContext() || context->IsBlockContext()) &&
context->extension_receiver() != nullptr) {
Handle<JSReceiver> object(context->extension_receiver());
if (context->IsNativeContext()) {
if (FLAG_trace_contexts) {
PrintF(" - trying other script contexts\n");
}
// Try other script contexts.
Handle<ScriptContextTable> script_contexts(
context->global_object()->native_context()->script_context_table());
ScriptContextTable::LookupResult r;
if (ScriptContextTable::Lookup(script_contexts, name, &r)) {
if (FLAG_trace_contexts) {
Handle<Context> c = ScriptContextTable::GetContext(script_contexts,
r.context_index);
PrintF("=> found property in script context %d: %p\n",
r.context_index, reinterpret_cast<void*>(*c));
}
*index = r.slot_index;
*variable_mode = r.mode;
*init_flag = r.init_flag;
*attributes = GetAttributesForMode(r.mode);
return ScriptContextTable::GetContext(script_contexts,
r.context_index);
}
}
// 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 = Nothing<PropertyAttributes>();
if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 ||
object->IsJSContextExtensionObject()) {
maybe = JSReceiver::GetOwnPropertyAttributes(object, name);
} else if (context->IsWithContext()) {
// A with context will never bind "this", but debug-eval may look into
// a with context when resolving "this". Other synthetic variables such
// as new.target may be resolved as DYNAMIC_LOCAL due to bug v8:5405 ,
// skipping them here serves as a workaround until a more thorough
// fix can be applied.
// TODO(v8:5405): Replace this check with a DCHECK when resolution of
// of synthetic variables does not go through this code path.
if (ScopeInfo::VariableIsSynthetic(*name)) {
maybe = Just(ABSENT);
} else {
LookupIterator it(object, name, object);
Maybe<bool> found = UnscopableLookup(&it);
if (found.IsNothing()) {
maybe = Nothing<PropertyAttributes>();
} else {
// Luckily, consumers of |maybe| only care whether the property
// was absent or not, so we can return a dummy |NONE| value
// for its attributes when it was present.
maybe = Just(found.FromJust() ? NONE : ABSENT);
}
}
} else {
maybe = JSReceiver::GetPropertyAttributes(object, name);
}
if (maybe.IsNothing()) return Handle<Object>();
DCHECK(!isolate->has_pending_exception());
*attributes = maybe.FromJust();
if (maybe.FromJust() != 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() ||
context->IsScriptContext() || context->IsEvalContext() ||
context->IsModuleContext()) {
// Use serialized scope information of functions and blocks to search
// for the context index.
Handle<ScopeInfo> scope_info(context->scope_info());
VariableMode mode;
InitializationFlag flag;
MaybeAssignedFlag maybe_assigned_flag;
int slot_index = ScopeInfo::ContextSlotIndex(scope_info, name, &mode,
&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;
*variable_mode = mode;
*init_flag = flag;
*attributes = GetAttributesForMode(mode);
return context;
}
// Check the slot corresponding to the intermediate context holding
// only the function name variable. It's conceptually (and spec-wise)
// in an outer scope of the function's declaration scope.
if (follow_context_chain && (flags & STOP_AT_DECLARATION_SCOPE) == 0 &&
context->IsFunctionContext()) {
int function_index = scope_info->FunctionContextSlotIndex(*name);
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;
*init_flag = kCreatedInitialized;
*variable_mode = CONST;
if (is_sloppy_function_name != nullptr &&
is_sloppy(scope_info->language_mode())) {
*is_sloppy_function_name = true;
}
return context;
}
}
// Lookup variable in module imports and exports.
if (context->IsModuleContext()) {
VariableMode mode;
InitializationFlag flag;
MaybeAssignedFlag maybe_assigned_flag;
int cell_index =
scope_info->ModuleIndex(name, &mode, &flag, &maybe_assigned_flag);
if (cell_index != 0) {
if (FLAG_trace_contexts) {
PrintF("=> found in module imports or exports\n");
}
*index = cell_index;
*variable_mode = mode;
*init_flag = flag;
*attributes = ModuleDescriptor::GetCellIndexKind(cell_index) ==
ModuleDescriptor::kExport
? GetAttributesForMode(mode)
: READ_ONLY;
return handle(context->module(), isolate);
}
}
} else if (context->IsCatchContext()) {
// Catch contexts have the variable name in the extension slot.
if (String::Equals(name, handle(context->catch_name()))) {
if (FLAG_trace_contexts) {
PrintF("=> found in catch context\n");
}
*index = Context::THROWN_OBJECT_INDEX;
*attributes = NONE;
*init_flag = kCreatedInitialized;
*variable_mode = VAR;
return context;
}
} else if (context->IsDebugEvaluateContext()) {
// Check materialized locals.
Object* ext = context->get(EXTENSION_INDEX);
if (ext->IsContextExtension()) {
Object* obj = ContextExtension::cast(ext)->extension();
if (obj->IsJSReceiver()) {
Handle<JSReceiver> extension(JSReceiver::cast(obj));
LookupIterator it(extension, name, extension);
Maybe<bool> found = JSReceiver::HasProperty(&it);
if (found.FromMaybe(false)) {
*attributes = NONE;
return extension;
}
}
}
// Check the original context, but do not follow its context chain.
Object* obj = context->get(WRAPPED_CONTEXT_INDEX);
if (obj->IsContext()) {
Handle<Object> result =
Context::cast(obj)->Lookup(name, DONT_FOLLOW_CHAINS, index,
attributes, init_flag, variable_mode);
if (!result.is_null()) return result;
}
// Check whitelist. Names that do not pass whitelist shall only resolve
// to with, script or native contexts up the context chain.
obj = context->get(WHITE_LIST_INDEX);
if (obj->IsStringSet()) {
failed_whitelist = failed_whitelist || !StringSet::cast(obj)->Has(name);
}
}
// 3. Prepare to continue with the previous (next outermost) context.
if (context->IsNativeContext() ||
((flags & STOP_AT_DECLARATION_SCOPE) != 0 &&
context->is_declaration_context())) {
follow_context_chain = false;
} else {
do {
context = Handle<Context>(context->previous(), isolate);
// If we come across a whitelist context, and the name is not
// whitelisted, then only consider with, script, module or native
// contexts.
} while (failed_whitelist && !context->IsScriptContext() &&
!context->IsNativeContext() && !context->IsWithContext() &&
!context->IsModuleContext());
}
} while (follow_context_chain);
if (FLAG_trace_contexts) {
PrintF("=> no property/slot found\n");
}
return Handle<Object>::null();
}
void Context::AddOptimizedCode(Code* code) {
DCHECK(IsNativeContext());
DCHECK(code->kind() == Code::OPTIMIZED_FUNCTION);
DCHECK(code->next_code_link()->IsUndefined(GetIsolate()));
code->set_next_code_link(get(OPTIMIZED_CODE_LIST));
set(OPTIMIZED_CODE_LIST, code, UPDATE_WEAK_WRITE_BARRIER);
}
void Context::SetOptimizedCodeListHead(Object* head) {
DCHECK(IsNativeContext());
set(OPTIMIZED_CODE_LIST, head, UPDATE_WEAK_WRITE_BARRIER);
}
Object* Context::OptimizedCodeListHead() {
DCHECK(IsNativeContext());
return get(OPTIMIZED_CODE_LIST);
}
void Context::SetDeoptimizedCodeListHead(Object* head) {
DCHECK(IsNativeContext());
set(DEOPTIMIZED_CODE_LIST, head, UPDATE_WEAK_WRITE_BARRIER);
}
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(isolate)) return result;
return isolate->factory()->NewStringFromStaticChars(
"Code generation from strings disallowed for this context");
}
#define COMPARE_NAME(index, type, name) \
if (string->IsOneByteEqualTo(STATIC_CHAR_VECTOR(#name))) return index;
int Context::ImportedFieldIndexForName(Handle<String> string) {
NATIVE_CONTEXT_IMPORTED_FIELDS(COMPARE_NAME)
return kNotFound;
}
int Context::IntrinsicIndexForName(Handle<String> string) {
NATIVE_CONTEXT_INTRINSIC_FUNCTIONS(COMPARE_NAME);
return kNotFound;
}
#undef COMPARE_NAME
#define COMPARE_NAME(index, type, name) \
if (strncmp(string, #name, length) == 0) return index;
int Context::IntrinsicIndexForName(const unsigned char* unsigned_string,
int length) {
const char* string = reinterpret_cast<const char*>(unsigned_string);
NATIVE_CONTEXT_INTRINSIC_FUNCTIONS(COMPARE_NAME);
return kNotFound;
}
#undef COMPARE_NAME
#ifdef DEBUG
bool Context::IsBootstrappingOrNativeContext(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->IsNativeContext();
}
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->IsScriptContext() ||
context->IsModuleContext() || !child->IsModuleContext();
}
#endif
void Context::ResetErrorsThrown() {
DCHECK(IsNativeContext());
set_errors_thrown(Smi::FromInt(0));
}
void Context::IncrementErrorsThrown() {
DCHECK(IsNativeContext());
int previous_value = errors_thrown()->value();
set_errors_thrown(Smi::FromInt(previous_value + 1));
}
int Context::GetErrorsThrown() { return errors_thrown()->value(); }
} // namespace internal
} // namespace v8