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cobalt / cobalt / 3933d9286b8c6b81e480dfbd894336405c89faa3 / . / src / v8 / src / ast / scopes.cc
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// Copyright 2012 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/ast/scopes.h"
#include <set>
#include "src/accessors.h"
#include "src/ast/ast.h"
#include "src/base/optional.h"
#include "src/bootstrapper.h"
#include "src/counters.h"
#include "src/messages.h"
#include "src/objects-inl.h"
#include "src/objects/module.h"
#include "src/objects/scope-info.h"
#include "src/parsing/parse-info.h"
#include "src/parsing/preparsed-scope-data.h"
namespace v8 {
namespace internal {
namespace {
void* kDummyPreParserVariable = reinterpret_cast<void*>(0x1);
void* kDummyPreParserLexicalVariable = reinterpret_cast<void*>(0x2);
bool IsLexical(Variable* variable) {
if (variable == kDummyPreParserLexicalVariable) return true;
if (variable == kDummyPreParserVariable) return false;
return IsLexicalVariableMode(variable->mode());
}
} // namespace
// ----------------------------------------------------------------------------
// Implementation of LocalsMap
//
// Note: We are storing the handle locations as key values in the hash map.
// When inserting a new variable via Declare(), we rely on the fact that
// the handle location remains alive for the duration of that variable
// use. Because a Variable holding a handle with the same location exists
// this is ensured.
VariableMap::VariableMap(Zone* zone)
: ZoneHashMap(8, ZoneAllocationPolicy(zone)) {}
Variable* VariableMap::Declare(Zone* zone, Scope* scope,
const AstRawString* name, VariableMode mode,
VariableKind kind,
InitializationFlag initialization_flag,
MaybeAssignedFlag maybe_assigned_flag,
bool* added) {
// AstRawStrings are unambiguous, i.e., the same string is always represented
// by the same AstRawString*.
// FIXME(marja): fix the type of Lookup.
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->Hash(),
ZoneAllocationPolicy(zone));
if (added) *added = p->value == nullptr;
if (p->value == nullptr) {
// The variable has not been declared yet -> insert it.
DCHECK_EQ(name, p->key);
p->value = new (zone) Variable(scope, name, mode, kind, initialization_flag,
maybe_assigned_flag);
}
return reinterpret_cast<Variable*>(p->value);
}
Variable* VariableMap::DeclareName(Zone* zone, const AstRawString* name,
VariableMode mode) {
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->Hash(),
ZoneAllocationPolicy(zone));
if (p->value == nullptr) {
// The variable has not been declared yet -> insert it.
DCHECK_EQ(name, p->key);
p->value =
mode == VAR ? kDummyPreParserVariable : kDummyPreParserLexicalVariable;
}
return reinterpret_cast<Variable*>(p->value);
}
void VariableMap::Remove(Variable* var) {
const AstRawString* name = var->raw_name();
ZoneHashMap::Remove(const_cast<AstRawString*>(name), name->Hash());
}
void VariableMap::Add(Zone* zone, Variable* var) {
const AstRawString* name = var->raw_name();
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->Hash(),
ZoneAllocationPolicy(zone));
DCHECK_NULL(p->value);
DCHECK_EQ(name, p->key);
p->value = var;
}
Variable* VariableMap::Lookup(const AstRawString* name) {
Entry* p = ZoneHashMap::Lookup(const_cast<AstRawString*>(name), name->Hash());
if (p != nullptr) {
DCHECK(reinterpret_cast<const AstRawString*>(p->key) == name);
DCHECK_NOT_NULL(p->value);
return reinterpret_cast<Variable*>(p->value);
}
return nullptr;
}
void SloppyBlockFunctionMap::Delegate::set_statement(Statement* statement) {
if (statement_ != nullptr) {
statement_->set_statement(statement);
}
}
SloppyBlockFunctionMap::SloppyBlockFunctionMap(Zone* zone)
: ZoneHashMap(8, ZoneAllocationPolicy(zone)), count_(0) {}
void SloppyBlockFunctionMap::Declare(Zone* zone, const AstRawString* name,
Scope* scope,
SloppyBlockFunctionStatement* statement) {
auto* delegate = new (zone) Delegate(scope, statement, count_++);
// AstRawStrings are unambiguous, i.e., the same string is always represented
// by the same AstRawString*.
Entry* p =
ZoneHashMap::LookupOrInsert(const_cast<AstRawString*>(name), name->Hash(),
ZoneAllocationPolicy(zone));
delegate->set_next(static_cast<SloppyBlockFunctionMap::Delegate*>(p->value));
p->value = delegate;
}
// ----------------------------------------------------------------------------
// Implementation of Scope
Scope::Scope(Zone* zone)
: zone_(zone),
outer_scope_(nullptr),
variables_(zone),
scope_type_(SCRIPT_SCOPE) {
SetDefaults();
}
Scope::Scope(Zone* zone, Scope* outer_scope, ScopeType scope_type)
: zone_(zone),
outer_scope_(outer_scope),
variables_(zone),
scope_type_(scope_type) {
DCHECK_NE(SCRIPT_SCOPE, scope_type);
SetDefaults();
set_language_mode(outer_scope->language_mode());
outer_scope_->AddInnerScope(this);
}
Scope::Snapshot::Snapshot(Scope* scope)
: outer_scope_(scope),
top_inner_scope_(scope->inner_scope_),
top_unresolved_(scope->unresolved_),
top_local_(scope->GetClosureScope()->locals_.end()),
top_decl_(scope->GetClosureScope()->decls_.end()),
outer_scope_calls_eval_(scope->scope_calls_eval_) {
// Reset in order to record eval calls during this Snapshot's lifetime.
outer_scope_->scope_calls_eval_ = false;
}
Scope::Snapshot::~Snapshot() {
// Restore previous calls_eval bit if needed.
if (outer_scope_calls_eval_) {
outer_scope_->scope_calls_eval_ = true;
}
}
DeclarationScope::DeclarationScope(Zone* zone,
AstValueFactory* ast_value_factory)
: Scope(zone), function_kind_(kNormalFunction), params_(4, zone) {
DCHECK_EQ(scope_type_, SCRIPT_SCOPE);
SetDefaults();
// Make sure that if we don't find the global 'this', it won't be declared as
// a regular dynamic global by predeclaring it with the right variable kind.
DeclareDynamicGlobal(ast_value_factory->this_string(), THIS_VARIABLE);
}
DeclarationScope::DeclarationScope(Zone* zone, Scope* outer_scope,
ScopeType scope_type,
FunctionKind function_kind)
: Scope(zone, outer_scope, scope_type),
function_kind_(function_kind),
params_(4, zone) {
DCHECK_NE(scope_type, SCRIPT_SCOPE);
SetDefaults();
}
ModuleScope::ModuleScope(DeclarationScope* script_scope,
AstValueFactory* ast_value_factory)
: DeclarationScope(ast_value_factory->zone(), script_scope, MODULE_SCOPE,
kModule) {
Zone* zone = ast_value_factory->zone();
module_descriptor_ = new (zone) ModuleDescriptor(zone);
set_language_mode(LanguageMode::kStrict);
DeclareThis(ast_value_factory);
}
ModuleScope::ModuleScope(Handle<ScopeInfo> scope_info,
AstValueFactory* avfactory)
: DeclarationScope(avfactory->zone(), MODULE_SCOPE, scope_info) {
Zone* zone = avfactory->zone();
Isolate* isolate = scope_info->GetIsolate();
Handle<ModuleInfo> module_info(scope_info->ModuleDescriptorInfo(), isolate);
set_language_mode(LanguageMode::kStrict);
module_descriptor_ = new (zone) ModuleDescriptor(zone);
// Deserialize special exports.
Handle<FixedArray> special_exports(module_info->special_exports(), isolate);
for (int i = 0, n = special_exports->length(); i < n; ++i) {
Handle<ModuleInfoEntry> serialized_entry(
ModuleInfoEntry::cast(special_exports->get(i)), isolate);
module_descriptor_->AddSpecialExport(
ModuleDescriptor::Entry::Deserialize(isolate, avfactory,
serialized_entry),
avfactory->zone());
}
// Deserialize regular exports.
module_descriptor_->DeserializeRegularExports(isolate, avfactory,
module_info);
// Deserialize namespace imports.
Handle<FixedArray> namespace_imports(module_info->namespace_imports(),
isolate);
for (int i = 0, n = namespace_imports->length(); i < n; ++i) {
Handle<ModuleInfoEntry> serialized_entry(
ModuleInfoEntry::cast(namespace_imports->get(i)), isolate);
module_descriptor_->AddNamespaceImport(
ModuleDescriptor::Entry::Deserialize(isolate, avfactory,
serialized_entry),
avfactory->zone());
}
// Deserialize regular imports.
Handle<FixedArray> regular_imports(module_info->regular_imports(), isolate);
for (int i = 0, n = regular_imports->length(); i < n; ++i) {
Handle<ModuleInfoEntry> serialized_entry(
ModuleInfoEntry::cast(regular_imports->get(i)), isolate);
module_descriptor_->AddRegularImport(ModuleDescriptor::Entry::Deserialize(
isolate, avfactory, serialized_entry));
}
}
Scope::Scope(Zone* zone, ScopeType scope_type, Handle<ScopeInfo> scope_info)
: zone_(zone),
outer_scope_(nullptr),
variables_(zone),
scope_info_(scope_info),
scope_type_(scope_type) {
DCHECK(!scope_info.is_null());
SetDefaults();
#ifdef DEBUG
already_resolved_ = true;
#endif
if (scope_info->CallsSloppyEval()) scope_calls_eval_ = true;
set_language_mode(scope_info->language_mode());
num_heap_slots_ = scope_info->ContextLength();
DCHECK_LE(Context::MIN_CONTEXT_SLOTS, num_heap_slots_);
// We don't really need to use the preparsed scope data; this is just to
// shorten the recursion in SetMustUsePreParsedScopeData.
must_use_preparsed_scope_data_ = true;
}
DeclarationScope::DeclarationScope(Zone* zone, ScopeType scope_type,
Handle<ScopeInfo> scope_info)
: Scope(zone, scope_type, scope_info),
function_kind_(scope_info->function_kind()),
params_(0, zone) {
DCHECK_NE(scope_type, SCRIPT_SCOPE);
SetDefaults();
}
Scope::Scope(Zone* zone, const AstRawString* catch_variable_name,
MaybeAssignedFlag maybe_assigned, Handle<ScopeInfo> scope_info)
: zone_(zone),
outer_scope_(nullptr),
variables_(zone),
scope_info_(scope_info),
scope_type_(CATCH_SCOPE) {
SetDefaults();
#ifdef DEBUG
already_resolved_ = true;
#endif
// Cache the catch variable, even though it's also available via the
// scope_info, as the parser expects that a catch scope always has the catch
// variable as first and only variable.
Variable* variable = Declare(zone, catch_variable_name, VAR, NORMAL_VARIABLE,
kCreatedInitialized, maybe_assigned);
AllocateHeapSlot(variable);
}
void DeclarationScope::SetDefaults() {
is_declaration_scope_ = true;
has_simple_parameters_ = true;
asm_module_ = false;
force_eager_compilation_ = false;
has_arguments_parameter_ = false;
scope_uses_super_property_ = false;
has_rest_ = false;
sloppy_block_function_map_ = nullptr;
receiver_ = nullptr;
new_target_ = nullptr;
function_ = nullptr;
arguments_ = nullptr;
rare_data_ = nullptr;
should_eager_compile_ = false;
was_lazily_parsed_ = false;
is_skipped_function_ = false;
produced_preparsed_scope_data_ = nullptr;
#ifdef DEBUG
DeclarationScope* outer_declaration_scope =
outer_scope_ ? outer_scope_->GetDeclarationScope() : nullptr;
is_being_lazily_parsed_ =
outer_declaration_scope ? outer_declaration_scope->is_being_lazily_parsed_
: false;
#endif
}
void Scope::SetDefaults() {
#ifdef DEBUG
scope_name_ = nullptr;
already_resolved_ = false;
needs_migration_ = false;
#endif
inner_scope_ = nullptr;
sibling_ = nullptr;
unresolved_ = nullptr;
start_position_ = kNoSourcePosition;
end_position_ = kNoSourcePosition;
num_stack_slots_ = 0;
num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
set_language_mode(LanguageMode::kSloppy);
scope_calls_eval_ = false;
scope_nonlinear_ = false;
is_hidden_ = false;
is_debug_evaluate_scope_ = false;
inner_scope_calls_eval_ = false;
force_context_allocation_ = false;
force_context_allocation_for_parameters_ = false;
is_declaration_scope_ = false;
must_use_preparsed_scope_data_ = false;
}
bool Scope::HasSimpleParameters() {
DeclarationScope* scope = GetClosureScope();
return !scope->is_function_scope() || scope->has_simple_parameters();
}
bool DeclarationScope::ShouldEagerCompile() const {
return force_eager_compilation_ || should_eager_compile_;
}
void DeclarationScope::set_should_eager_compile() {
should_eager_compile_ = !was_lazily_parsed_;
}
void DeclarationScope::set_asm_module() {
asm_module_ = true;
}
bool Scope::IsAsmModule() const {
return is_function_scope() && AsDeclarationScope()->asm_module();
}
bool Scope::ContainsAsmModule() const {
if (IsAsmModule()) return true;
// Check inner scopes recursively
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
// Don't check inner functions which won't be eagerly compiled.
if (!scope->is_function_scope() ||
scope->AsDeclarationScope()->ShouldEagerCompile()) {
if (scope->ContainsAsmModule()) return true;
}
}
return false;
}
Scope* Scope::DeserializeScopeChain(Zone* zone, ScopeInfo* scope_info,
DeclarationScope* script_scope,
AstValueFactory* ast_value_factory,
DeserializationMode deserialization_mode) {
// Reconstruct the outer scope chain from a closure's context chain.
Scope* current_scope = nullptr;
Scope* innermost_scope = nullptr;
Scope* outer_scope = nullptr;
while (scope_info) {
if (scope_info->scope_type() == WITH_SCOPE) {
// For scope analysis, debug-evaluate is equivalent to a with scope.
outer_scope = new (zone) Scope(zone, WITH_SCOPE, handle(scope_info));
// TODO(yangguo): Remove once debug-evaluate properly keeps track of the
// function scope in which we are evaluating.
if (scope_info->IsDebugEvaluateScope()) {
outer_scope->set_is_debug_evaluate_scope();
}
} else if (scope_info->scope_type() == SCRIPT_SCOPE) {
// If we reach a script scope, it's the outermost scope. Install the
// scope info of this script context onto the existing script scope to
// avoid nesting script scopes.
if (deserialization_mode == DeserializationMode::kIncludingVariables) {
script_scope->SetScriptScopeInfo(handle(scope_info));
}
DCHECK(!scope_info->HasOuterScopeInfo());
break;
} else if (scope_info->scope_type() == FUNCTION_SCOPE) {
outer_scope =
new (zone) DeclarationScope(zone, FUNCTION_SCOPE, handle(scope_info));
if (scope_info->IsAsmModule())
outer_scope->AsDeclarationScope()->set_asm_module();
} else if (scope_info->scope_type() == EVAL_SCOPE) {
outer_scope =
new (zone) DeclarationScope(zone, EVAL_SCOPE, handle(scope_info));
} else if (scope_info->scope_type() == BLOCK_SCOPE) {
if (scope_info->is_declaration_scope()) {
outer_scope =
new (zone) DeclarationScope(zone, BLOCK_SCOPE, handle(scope_info));
} else {
outer_scope = new (zone) Scope(zone, BLOCK_SCOPE, handle(scope_info));
}
} else if (scope_info->scope_type() == MODULE_SCOPE) {
outer_scope =
new (zone) ModuleScope(handle(scope_info), ast_value_factory);
} else {
DCHECK_EQ(scope_info->scope_type(), CATCH_SCOPE);
DCHECK_EQ(scope_info->LocalCount(), 1);
DCHECK_EQ(scope_info->ContextLocalCount(), 1);
DCHECK_EQ(scope_info->ContextLocalMode(0), VAR);
DCHECK_EQ(scope_info->ContextLocalInitFlag(0), kCreatedInitialized);
String* name = scope_info->ContextLocalName(0);
MaybeAssignedFlag maybe_assigned =
scope_info->ContextLocalMaybeAssignedFlag(0);
outer_scope =
new (zone) Scope(zone, ast_value_factory->GetString(handle(name)),
maybe_assigned, handle(scope_info));
}
if (deserialization_mode == DeserializationMode::kScopesOnly) {
outer_scope->scope_info_ = Handle<ScopeInfo>::null();
}
if (current_scope != nullptr) {
outer_scope->AddInnerScope(current_scope);
}
current_scope = outer_scope;
if (innermost_scope == nullptr) innermost_scope = current_scope;
scope_info = scope_info->HasOuterScopeInfo() ? scope_info->OuterScopeInfo()
: nullptr;
}
if (innermost_scope == nullptr) return script_scope;
script_scope->AddInnerScope(current_scope);
return innermost_scope;
}
DeclarationScope* Scope::AsDeclarationScope() {
DCHECK(is_declaration_scope());
return static_cast<DeclarationScope*>(this);
}
const DeclarationScope* Scope::AsDeclarationScope() const {
DCHECK(is_declaration_scope());
return static_cast<const DeclarationScope*>(this);
}
ModuleScope* Scope::AsModuleScope() {
DCHECK(is_module_scope());
return static_cast<ModuleScope*>(this);
}
const ModuleScope* Scope::AsModuleScope() const {
DCHECK(is_module_scope());
return static_cast<const ModuleScope*>(this);
}
int Scope::num_parameters() const {
return is_declaration_scope() ? AsDeclarationScope()->num_parameters() : 0;
}
void DeclarationScope::DeclareSloppyBlockFunction(
const AstRawString* name, Scope* scope,
SloppyBlockFunctionStatement* statement) {
if (sloppy_block_function_map_ == nullptr) {
sloppy_block_function_map_ =
new (zone()->New(sizeof(SloppyBlockFunctionMap)))
SloppyBlockFunctionMap(zone());
}
sloppy_block_function_map_->Declare(zone(), name, scope, statement);
}
void DeclarationScope::HoistSloppyBlockFunctions(AstNodeFactory* factory) {
DCHECK(is_sloppy(language_mode()));
DCHECK(is_function_scope() || is_eval_scope() || is_script_scope() ||
(is_block_scope() && outer_scope()->is_function_scope()));
DCHECK(HasSimpleParameters() || is_block_scope() || is_being_lazily_parsed_);
DCHECK_EQ(factory == nullptr, is_being_lazily_parsed_);
SloppyBlockFunctionMap* map = sloppy_block_function_map();
if (map == nullptr) return;
const bool has_simple_parameters = HasSimpleParameters();
// The declarations need to be added in the order they were seen,
// so accumulate declared names sorted by index.
ZoneMap<int, const AstRawString*> names_to_declare(zone());
// For each variable which is used as a function declaration in a sloppy
// block,
for (ZoneHashMap::Entry* p = map->Start(); p != nullptr; p = map->Next(p)) {
const AstRawString* name = static_cast<AstRawString*>(p->key);
// If the variable wouldn't conflict with a lexical declaration
// or parameter,
// Check if there's a conflict with a parameter.
// This depends on the fact that functions always have a scope solely to
// hold complex parameters, and the names local to that scope are
// precisely the names of the parameters. IsDeclaredParameter(name) does
// not hold for names declared by complex parameters, nor are those
// bindings necessarily declared lexically, so we have to check for them
// explicitly. On the other hand, if there are not complex parameters,
// it is sufficient to just check IsDeclaredParameter.
if (!has_simple_parameters) {
if (outer_scope_->LookupLocal(name) != nullptr) {
continue;
}
} else {
if (IsDeclaredParameter(name)) {
continue;
}
}
bool declaration_queued = false;
// Write in assignments to var for each block-scoped function declaration
auto delegates = static_cast<SloppyBlockFunctionMap::Delegate*>(p->value);
DeclarationScope* decl_scope = this;
while (decl_scope->is_eval_scope()) {
decl_scope = decl_scope->outer_scope()->GetDeclarationScope();
}
Scope* outer_scope = decl_scope->outer_scope();
for (SloppyBlockFunctionMap::Delegate* delegate = delegates;
delegate != nullptr; delegate = delegate->next()) {
// Check if there's a conflict with a lexical declaration
Scope* query_scope = delegate->scope()->outer_scope();
Variable* var = nullptr;
bool should_hoist = true;
// Note that we perform this loop for each delegate named 'name',
// which may duplicate work if those delegates share scopes.
// It is not sufficient to just do a Lookup on query_scope: for
// example, that does not prevent hoisting of the function in
// `{ let e; try {} catch (e) { function e(){} } }`
do {
var = query_scope->LookupLocal(name);
if (var != nullptr && IsLexical(var)) {
should_hoist = false;
break;
}
query_scope = query_scope->outer_scope();
} while (query_scope != outer_scope);
if (!should_hoist) continue;
if (!declaration_queued) {
declaration_queued = true;
names_to_declare.insert({delegate->index(), name});
}
if (factory) {
DCHECK(!is_being_lazily_parsed_);
Assignment* assignment = factory->NewAssignment(
Token::ASSIGN, NewUnresolved(factory, name),
delegate->scope()->NewUnresolved(factory, name), kNoSourcePosition);
assignment->set_lookup_hoisting_mode(LookupHoistingMode::kLegacySloppy);
Statement* statement =
factory->NewExpressionStatement(assignment, kNoSourcePosition);
delegate->set_statement(statement);
}
}
}
if (names_to_declare.empty()) return;
for (const auto& index_and_name : names_to_declare) {
const AstRawString* name = index_and_name.second;
if (factory) {
DCHECK(!is_being_lazily_parsed_);
VariableProxy* proxy = factory->NewVariableProxy(name, NORMAL_VARIABLE);
auto declaration =
factory->NewVariableDeclaration(proxy, kNoSourcePosition);
// Based on the preceding checks, it doesn't matter what we pass as
// sloppy_mode_block_scope_function_redefinition.
bool ok = true;
DeclareVariable(declaration, VAR,
Variable::DefaultInitializationFlag(VAR), nullptr, &ok);
DCHECK(ok);
} else {
DCHECK(is_being_lazily_parsed_);
Variable* var = DeclareVariableName(name, VAR);
if (var != kDummyPreParserVariable &&
var != kDummyPreParserLexicalVariable) {
DCHECK(FLAG_preparser_scope_analysis);
var->set_maybe_assigned();
}
}
}
}
void DeclarationScope::AttachOuterScopeInfo(ParseInfo* info, Isolate* isolate) {
DCHECK(scope_info_.is_null());
Handle<ScopeInfo> outer_scope_info;
if (info->maybe_outer_scope_info().ToHandle(&outer_scope_info)) {
// If we have a scope info we will potentially need to lookup variable names
// on the scope info as internalized strings, so make sure ast_value_factory
// is internalized.
info->ast_value_factory()->Internalize(isolate);
if (outer_scope()) {
DeclarationScope* script_scope = new (info->zone())
DeclarationScope(info->zone(), info->ast_value_factory());
info->set_script_scope(script_scope);
ReplaceOuterScope(Scope::DeserializeScopeChain(
info->zone(), *outer_scope_info, script_scope,
info->ast_value_factory(),
Scope::DeserializationMode::kIncludingVariables));
} else {
DCHECK_EQ(outer_scope_info->scope_type(), SCRIPT_SCOPE);
SetScriptScopeInfo(outer_scope_info);
}
}
}
void DeclarationScope::Analyze(ParseInfo* info) {
RuntimeCallTimerScope runtimeTimer(
info->runtime_call_stats(),
info->on_background_thread()
? RuntimeCallCounterId::kCompileBackgroundScopeAnalysis
: RuntimeCallCounterId::kCompileScopeAnalysis);
DCHECK_NOT_NULL(info->literal());
DeclarationScope* scope = info->literal()->scope();
base::Optional<AllowHandleDereference> allow_deref;
if (!info->maybe_outer_scope_info().is_null()) {
// Allow dereferences to the scope info if there is one.
allow_deref.emplace();
}
if (scope->is_eval_scope() && is_sloppy(scope->language_mode())) {
AstNodeFactory factory(info->ast_value_factory(), info->zone());
scope->HoistSloppyBlockFunctions(&factory);
}
// We are compiling one of four cases:
// 1) top-level code,
// 2) a function/eval/module on the top-level
// 3) a function/eval in a scope that was already resolved.
DCHECK(scope->scope_type() == SCRIPT_SCOPE ||
scope->outer_scope()->scope_type() == SCRIPT_SCOPE ||
scope->outer_scope()->already_resolved_);
// The outer scope is never lazy.
scope->set_should_eager_compile();
if (scope->must_use_preparsed_scope_data_) {
DCHECK(FLAG_preparser_scope_analysis);
DCHECK_EQ(scope->scope_type_, ScopeType::FUNCTION_SCOPE);
allow_deref.emplace();
info->consumed_preparsed_scope_data()->RestoreScopeAllocationData(scope);
}
scope->AllocateVariables(info);
#ifdef DEBUG
if (info->is_native() ? FLAG_print_builtin_scopes : FLAG_print_scopes) {
PrintF("Global scope:\n");
scope->Print();
}
scope->CheckScopePositions();
scope->CheckZones();
#endif
}
void DeclarationScope::DeclareThis(AstValueFactory* ast_value_factory) {
DCHECK(!already_resolved_);
DCHECK(is_declaration_scope());
DCHECK(has_this_declaration());
bool derived_constructor = IsDerivedConstructor(function_kind_);
Variable* var =
Declare(zone(), ast_value_factory->this_string(),
derived_constructor ? CONST : VAR, THIS_VARIABLE,
derived_constructor ? kNeedsInitialization : kCreatedInitialized);
receiver_ = var;
}
void DeclarationScope::DeclareArguments(AstValueFactory* ast_value_factory) {
DCHECK(is_function_scope());
DCHECK(!is_arrow_scope());
arguments_ = LookupLocal(ast_value_factory->arguments_string());
if (arguments_ == nullptr) {
// Declare 'arguments' variable which exists in all non arrow functions.
// Note that it might never be accessed, in which case it won't be
// allocated during variable allocation.
arguments_ = Declare(zone(), ast_value_factory->arguments_string(), VAR);
} else if (IsLexical(arguments_)) {
// Check if there's lexically declared variable named arguments to avoid
// redeclaration. See ES#sec-functiondeclarationinstantiation, step 20.
arguments_ = nullptr;
}
}
void DeclarationScope::DeclareDefaultFunctionVariables(
AstValueFactory* ast_value_factory) {
DCHECK(is_function_scope());
DCHECK(!is_arrow_scope());
DeclareThis(ast_value_factory);
new_target_ = Declare(zone(), ast_value_factory->new_target_string(), CONST);
if (IsConciseMethod(function_kind_) || IsClassConstructor(function_kind_) ||
IsAccessorFunction(function_kind_)) {
EnsureRareData()->this_function =
Declare(zone(), ast_value_factory->this_function_string(), CONST);
}
}
Variable* DeclarationScope::DeclareFunctionVar(const AstRawString* name) {
DCHECK(is_function_scope());
DCHECK_NULL(function_);
DCHECK_NULL(variables_.Lookup(name));
VariableKind kind = is_sloppy(language_mode()) ? SLOPPY_FUNCTION_NAME_VARIABLE
: NORMAL_VARIABLE;
function_ =
new (zone()) Variable(this, name, CONST, kind, kCreatedInitialized);
if (calls_sloppy_eval()) {
NonLocal(name, DYNAMIC);
} else {
variables_.Add(zone(), function_);
}
return function_;
}
Variable* DeclarationScope::DeclareGeneratorObjectVar(
const AstRawString* name) {
DCHECK(is_function_scope() || is_module_scope());
DCHECK_NULL(generator_object_var());
Variable* result = EnsureRareData()->generator_object =
NewTemporary(name, kNotAssigned);
result->set_is_used();
return result;
}
Variable* DeclarationScope::DeclarePromiseVar(const AstRawString* name) {
DCHECK(is_function_scope());
DCHECK_NULL(promise_var());
Variable* result = EnsureRareData()->promise = NewTemporary(name);
result->set_is_used();
return result;
}
bool Scope::HasBeenRemoved() const {
if (sibling() == this) {
DCHECK_NULL(inner_scope_);
DCHECK(is_block_scope());
return true;
}
return false;
}
Scope* Scope::GetUnremovedScope() {
Scope* scope = this;
while (scope != nullptr && scope->HasBeenRemoved()) {
scope = scope->outer_scope();
}
DCHECK_NOT_NULL(scope);
return scope;
}
Scope* Scope::FinalizeBlockScope() {
DCHECK(is_block_scope());
DCHECK(!HasBeenRemoved());
if (variables_.occupancy() > 0 ||
(is_declaration_scope() && AsDeclarationScope()->calls_sloppy_eval())) {
return this;
}
// Remove this scope from outer scope.
outer_scope()->RemoveInnerScope(this);
// Reparent inner scopes.
if (inner_scope_ != nullptr) {
Scope* scope = inner_scope_;
scope->outer_scope_ = outer_scope();
while (scope->sibling_ != nullptr) {
scope = scope->sibling_;
scope->outer_scope_ = outer_scope();
}
scope->sibling_ = outer_scope()->inner_scope_;
outer_scope()->inner_scope_ = inner_scope_;
inner_scope_ = nullptr;
}
// Move unresolved variables
if (unresolved_ != nullptr) {
if (outer_scope()->unresolved_ != nullptr) {
VariableProxy* unresolved = unresolved_;
while (unresolved->next_unresolved() != nullptr) {
unresolved = unresolved->next_unresolved();
}
unresolved->set_next_unresolved(outer_scope()->unresolved_);
}
outer_scope()->unresolved_ = unresolved_;
unresolved_ = nullptr;
}
if (inner_scope_calls_eval_) outer_scope()->inner_scope_calls_eval_ = true;
// No need to propagate scope_calls_eval_, since if it was relevant to
// this scope we would have had to bail out at the top.
DCHECK(!scope_calls_eval_ || !is_declaration_scope() ||
!is_sloppy(language_mode()));
// This block does not need a context.
num_heap_slots_ = 0;
// Mark scope as removed by making it its own sibling.
sibling_ = this;
DCHECK(HasBeenRemoved());
return nullptr;
}
void DeclarationScope::AddLocal(Variable* var) {
DCHECK(!already_resolved_);
// Temporaries are only placed in ClosureScopes.
DCHECK_EQ(GetClosureScope(), this);
locals_.Add(var);
}
Variable* Scope::Declare(Zone* zone, const AstRawString* name,
VariableMode mode, VariableKind kind,
InitializationFlag initialization_flag,
MaybeAssignedFlag maybe_assigned_flag) {
bool added;
Variable* var =
variables_.Declare(zone, this, name, mode, kind, initialization_flag,
maybe_assigned_flag, &added);
if (added) locals_.Add(var);
return var;
}
void Scope::Snapshot::Reparent(DeclarationScope* new_parent) const {
DCHECK_EQ(new_parent, outer_scope_->inner_scope_);
DCHECK_EQ(new_parent->outer_scope_, outer_scope_);
DCHECK_EQ(new_parent, new_parent->GetClosureScope());
DCHECK_NULL(new_parent->inner_scope_);
DCHECK_NULL(new_parent->unresolved_);
DCHECK(new_parent->locals_.is_empty());
Scope* inner_scope = new_parent->sibling_;
if (inner_scope != top_inner_scope_) {
for (; inner_scope->sibling() != top_inner_scope_;
inner_scope = inner_scope->sibling()) {
inner_scope->outer_scope_ = new_parent;
if (inner_scope->inner_scope_calls_eval_) {
new_parent->inner_scope_calls_eval_ = true;
}
DCHECK_NE(inner_scope, new_parent);
}
inner_scope->outer_scope_ = new_parent;
if (inner_scope->inner_scope_calls_eval_) {
new_parent->inner_scope_calls_eval_ = true;
}
new_parent->inner_scope_ = new_parent->sibling_;
inner_scope->sibling_ = nullptr;
// Reset the sibling rather than the inner_scope_ since we
// want to keep new_parent there.
new_parent->sibling_ = top_inner_scope_;
}
if (outer_scope_->unresolved_ != top_unresolved_) {
VariableProxy* last = outer_scope_->unresolved_;
while (last->next_unresolved() != top_unresolved_) {
last = last->next_unresolved();
}
last->set_next_unresolved(nullptr);
new_parent->unresolved_ = outer_scope_->unresolved_;
outer_scope_->unresolved_ = top_unresolved_;
}
// TODO(verwaest): This currently only moves do-expression declared variables
// in default arguments that weren't already previously declared with the same
// name in the closure-scope. See
// test/mjsunit/harmony/default-parameter-do-expression.js.
DeclarationScope* outer_closure = outer_scope_->GetClosureScope();
new_parent->locals_.MoveTail(outer_closure->locals(), top_local_);
for (Variable* local : new_parent->locals_) {
DCHECK(local->mode() == TEMPORARY || local->mode() == VAR);
DCHECK_EQ(local->scope(), local->scope()->GetClosureScope());
DCHECK_NE(local->scope(), new_parent);
local->set_scope(new_parent);
if (local->mode() == VAR) {
outer_closure->variables_.Remove(local);
new_parent->variables_.Add(new_parent->zone(), local);
}
}
outer_closure->locals_.Rewind(top_local_);
outer_closure->decls_.Rewind(top_decl_);
// Move eval calls since Snapshot's creation into new_parent.
if (outer_scope_->scope_calls_eval_) {
new_parent->scope_calls_eval_ = true;
new_parent->inner_scope_calls_eval_ = true;
}
// Reset the outer_scope's eval state. It will be restored to its
// original value as necessary in the destructor of this class.
outer_scope_->scope_calls_eval_ = false;
}
void Scope::ReplaceOuterScope(Scope* outer) {
DCHECK_NOT_NULL(outer);
DCHECK_NOT_NULL(outer_scope_);
DCHECK(!already_resolved_);
outer_scope_->RemoveInnerScope(this);
outer->AddInnerScope(this);
outer_scope_ = outer;
}
Variable* Scope::LookupInScopeInfo(const AstRawString* name) {
Handle<String> name_handle = name->string();
// The Scope is backed up by ScopeInfo. This means it cannot operate in a
// heap-independent mode, and all strings must be internalized immediately. So
// it's ok to get the Handle<String> here.
// If we have a serialized scope info, we might find the variable there.
// There should be no local slot with the given name.
DCHECK_LT(scope_info_->StackSlotIndex(*name_handle), 0);
bool found = false;
VariableLocation location;
int index;
VariableMode mode;
InitializationFlag init_flag;
MaybeAssignedFlag maybe_assigned_flag;
{
location = VariableLocation::CONTEXT;
index = ScopeInfo::ContextSlotIndex(scope_info_, name_handle, &mode,
&init_flag, &maybe_assigned_flag);
found = index >= 0;
}
if (!found && scope_type() == MODULE_SCOPE) {
location = VariableLocation::MODULE;
index = scope_info_->ModuleIndex(name_handle, &mode, &init_flag,
&maybe_assigned_flag);
found = index != 0;
}
if (!found) {
index = scope_info_->FunctionContextSlotIndex(*name_handle);
if (index < 0) return nullptr; // Nowhere found.
Variable* var = AsDeclarationScope()->DeclareFunctionVar(name);
DCHECK_EQ(CONST, var->mode());
var->AllocateTo(VariableLocation::CONTEXT, index);
return variables_.Lookup(name);
}
VariableKind kind = NORMAL_VARIABLE;
if (location == VariableLocation::CONTEXT &&
index == scope_info_->ReceiverContextSlotIndex()) {
kind = THIS_VARIABLE;
}
// TODO(marja, rossberg): Correctly declare FUNCTION, CLASS, NEW_TARGET, and
// ARGUMENTS bindings as their corresponding VariableKind.
Variable* var = variables_.Declare(zone(), this, name, mode, kind, init_flag,
maybe_assigned_flag);
var->AllocateTo(location, index);
return var;
}
Variable* Scope::Lookup(const AstRawString* name) {
for (Scope* scope = this; scope != nullptr; scope = scope->outer_scope()) {
Variable* var = scope->LookupLocal(name);
if (var != nullptr) return var;
}
return nullptr;
}
Variable* DeclarationScope::DeclareParameter(
const AstRawString* name, VariableMode mode, bool is_optional, bool is_rest,
bool* is_duplicate, AstValueFactory* ast_value_factory, int position) {
DCHECK(!already_resolved_);
DCHECK(is_function_scope() || is_module_scope());
DCHECK(!has_rest_);
DCHECK(!is_optional || !is_rest);
DCHECK(!is_being_lazily_parsed_);
DCHECK(!was_lazily_parsed_);
Variable* var;
if (mode == TEMPORARY) {
var = NewTemporary(name);
} else {
DCHECK_EQ(mode, VAR);
var = Declare(zone(), name, mode);
// TODO(wingo): Avoid O(n^2) check.
if (is_duplicate != nullptr) {
*is_duplicate = *is_duplicate || IsDeclaredParameter(name);
}
}
has_rest_ = is_rest;
var->set_initializer_position(position);
params_.Add(var, zone());
if (name == ast_value_factory->arguments_string()) {
has_arguments_parameter_ = true;
}
return var;
}
Variable* DeclarationScope::DeclareParameterName(
const AstRawString* name, bool is_rest, AstValueFactory* ast_value_factory,
bool declare_as_local, bool add_parameter) {
DCHECK(!already_resolved_);
DCHECK(is_function_scope() || is_module_scope());
DCHECK(!has_rest_ || is_rest);
DCHECK(is_being_lazily_parsed_);
has_rest_ = is_rest;
if (name == ast_value_factory->arguments_string()) {
has_arguments_parameter_ = true;
}
if (FLAG_preparser_scope_analysis) {
Variable* var;
if (declare_as_local) {
var = Declare(zone(), name, VAR);
} else {
var = new (zone())
Variable(this, name, TEMPORARY, NORMAL_VARIABLE, kCreatedInitialized);
}
if (add_parameter) {
params_.Add(var, zone());
}
return var;
}
DeclareVariableName(name, VAR);
return nullptr;
}
Variable* Scope::DeclareLocal(const AstRawString* name, VariableMode mode,
InitializationFlag init_flag, VariableKind kind,
MaybeAssignedFlag maybe_assigned_flag) {
DCHECK(!already_resolved_);
// This function handles VAR, LET, and CONST modes. DYNAMIC variables are
// introduced during variable allocation, and TEMPORARY variables are
// allocated via NewTemporary().
DCHECK(IsDeclaredVariableMode(mode));
DCHECK_IMPLIES(GetDeclarationScope()->is_being_lazily_parsed(),
mode == VAR || mode == LET || mode == CONST);
DCHECK(!GetDeclarationScope()->was_lazily_parsed());
return Declare(zone(), name, mode, kind, init_flag, maybe_assigned_flag);
}
Variable* Scope::DeclareVariable(
Declaration* declaration, VariableMode mode, InitializationFlag init,
bool* sloppy_mode_block_scope_function_redefinition, bool* ok) {
DCHECK(IsDeclaredVariableMode(mode));
DCHECK(!already_resolved_);
DCHECK(!GetDeclarationScope()->is_being_lazily_parsed());
DCHECK(!GetDeclarationScope()->was_lazily_parsed());
if (mode == VAR && !is_declaration_scope()) {
return GetDeclarationScope()->DeclareVariable(
declaration, mode, init, sloppy_mode_block_scope_function_redefinition,
ok);
}
DCHECK(!is_catch_scope());
DCHECK(!is_with_scope());
DCHECK(is_declaration_scope() ||
(IsLexicalVariableMode(mode) && is_block_scope()));
VariableProxy* proxy = declaration->proxy();
DCHECK_NOT_NULL(proxy->raw_name());
const AstRawString* name = proxy->raw_name();
bool is_function_declaration = declaration->IsFunctionDeclaration();
// Pessimistically assume that top-level variables will be assigned.
//
// Top-level variables in a script can be accessed by other scripts or even
// become global properties. While this does not apply to top-level variables
// in a module (assuming they are not exported), we must still mark these as
// assigned because they might be accessed by a lazily parsed top-level
// function, which, for efficiency, we preparse without variable tracking.
if (is_script_scope() || is_module_scope()) {
if (mode != CONST) proxy->set_is_assigned();
}
Variable* var = nullptr;
if (is_eval_scope() && is_sloppy(language_mode()) && mode == VAR) {
// In a var binding in a sloppy direct eval, pollute the enclosing scope
// with this new binding by doing the following:
// The proxy is bound to a lookup variable to force a dynamic declaration
// using the DeclareEvalVar or DeclareEvalFunction runtime functions.
var = new (zone())
Variable(this, name, mode, NORMAL_VARIABLE, init, kMaybeAssigned);
var->AllocateTo(VariableLocation::LOOKUP, -1);
} else {
// Declare the variable in the declaration scope.
var = LookupLocal(name);
if (var == nullptr) {
// Declare the name.
VariableKind kind = NORMAL_VARIABLE;
if (is_function_declaration) {
kind = FUNCTION_VARIABLE;
}
var = DeclareLocal(name, mode, init, kind, kNotAssigned);
} else if (IsLexicalVariableMode(mode) ||
IsLexicalVariableMode(var->mode())) {
// Allow duplicate function decls for web compat, see bug 4693.
bool duplicate_allowed = false;
if (is_sloppy(language_mode()) && is_function_declaration &&
var->is_function()) {
DCHECK(IsLexicalVariableMode(mode) &&
IsLexicalVariableMode(var->mode()));
// If the duplication is allowed, then the var will show up
// in the SloppyBlockFunctionMap and the new FunctionKind
// will be a permitted duplicate.
FunctionKind function_kind =
declaration->AsFunctionDeclaration()->fun()->kind();
SloppyBlockFunctionMap* map =
GetDeclarationScope()->sloppy_block_function_map();
duplicate_allowed = map != nullptr &&
map->Lookup(const_cast<AstRawString*>(name),
name->Hash()) != nullptr &&
!IsAsyncFunction(function_kind) &&
!IsGeneratorFunction(function_kind);
}
if (duplicate_allowed) {
*sloppy_mode_block_scope_function_redefinition = true;
} else {
// The name was declared in this scope before; check for conflicting
// re-declarations. We have a conflict if either of the declarations
// is not a var (in script scope, we also have to ignore legacy const
// for compatibility). There is similar code in runtime.cc in the
// Declare functions. The function CheckConflictingVarDeclarations
// checks for var and let bindings from different scopes whereas this
// is a check for conflicting declarations within the same scope. This
// check also covers the special case
//
// function () { let x; { var x; } }
//
// because the var declaration is hoisted to the function scope where
// 'x' is already bound.
DCHECK(IsDeclaredVariableMode(var->mode()));
// In harmony we treat re-declarations as early errors. See
// ES5 16 for a definition of early errors.
*ok = false;
return nullptr;
}
} else if (mode == VAR) {
var->set_maybe_assigned();
}
}
DCHECK_NOT_NULL(var);
// We add a declaration node for every declaration. The compiler
// will only generate code if necessary. In particular, declarations
// for inner local variables that do not represent functions won't
// result in any generated code.
//
// This will lead to multiple declaration nodes for the
// same variable if it is declared several times. This is not a
// semantic issue, but it may be a performance issue since it may
// lead to repeated DeclareEvalVar or DeclareEvalFunction calls.
decls_.Add(declaration);
proxy->BindTo(var);
return var;
}
Variable* Scope::DeclareVariableName(const AstRawString* name,
VariableMode mode) {
DCHECK(IsDeclaredVariableMode(mode));
DCHECK(!already_resolved_);
DCHECK(GetDeclarationScope()->is_being_lazily_parsed());
if (mode == VAR && !is_declaration_scope()) {
return GetDeclarationScope()->DeclareVariableName(name, mode);
}
DCHECK(!is_with_scope());
DCHECK(!is_eval_scope());
DCHECK(is_declaration_scope() || IsLexicalVariableMode(mode));
DCHECK(scope_info_.is_null());
// Declare the variable in the declaration scope.
if (FLAG_preparser_scope_analysis) {
Variable* var = LookupLocal(name);
DCHECK_NE(var, kDummyPreParserLexicalVariable);
DCHECK_NE(var, kDummyPreParserVariable);
if (var == nullptr) {
var = DeclareLocal(name, mode);
} else if (IsLexicalVariableMode(mode) ||
IsLexicalVariableMode(var->mode())) {
// Duplicate functions are allowed in the sloppy mode, but if this is not
// a function declaration, it's an error. This is an error PreParser
// hasn't previously detected. TODO(marja): Investigate whether we can now
// start returning this error.
} else if (mode == VAR) {
var->set_maybe_assigned();
}
var->set_is_used();
return var;
} else {
return variables_.DeclareName(zone(), name, mode);
}
}
void Scope::DeclareCatchVariableName(const AstRawString* name) {
DCHECK(!already_resolved_);
DCHECK(GetDeclarationScope()->is_being_lazily_parsed());
DCHECK(is_catch_scope());
DCHECK(scope_info_.is_null());
if (FLAG_preparser_scope_analysis) {
Declare(zone(), name, VAR);
} else {
variables_.DeclareName(zone(), name, VAR);
}
}
void Scope::AddUnresolved(VariableProxy* proxy) {
DCHECK(!already_resolved_);
DCHECK(!proxy->is_resolved());
proxy->set_next_unresolved(unresolved_);
unresolved_ = proxy;
}
Variable* DeclarationScope::DeclareDynamicGlobal(const AstRawString* name,
VariableKind kind) {
DCHECK(is_script_scope());
return variables_.Declare(zone(), this, name, DYNAMIC_GLOBAL, kind);
// TODO(neis): Mark variable as maybe-assigned?
}
bool Scope::RemoveUnresolved(VariableProxy* var) {
if (unresolved_ == var) {
unresolved_ = var->next_unresolved();
var->set_next_unresolved(nullptr);
return true;
}
VariableProxy* current = unresolved_;
while (current != nullptr) {
VariableProxy* next = current->next_unresolved();
if (var == next) {
current->set_next_unresolved(next->next_unresolved());
var->set_next_unresolved(nullptr);
return true;
}
current = next;
}
return false;
}
Variable* Scope::NewTemporary(const AstRawString* name) {
return NewTemporary(name, kMaybeAssigned);
}
Variable* Scope::NewTemporary(const AstRawString* name,
MaybeAssignedFlag maybe_assigned) {
DeclarationScope* scope = GetClosureScope();
Variable* var = new (zone())
Variable(scope, name, TEMPORARY, NORMAL_VARIABLE, kCreatedInitialized);
scope->AddLocal(var);
if (maybe_assigned == kMaybeAssigned) var->set_maybe_assigned();
return var;
}
Declaration* Scope::CheckConflictingVarDeclarations() {
for (Declaration* decl : decls_) {
VariableMode mode = decl->proxy()->var()->mode();
// Lexical vs lexical conflicts within the same scope have already been
// captured in Parser::Declare. The only conflicts we still need to check
// are lexical vs nested var, or any declarations within a declaration
// block scope vs lexical declarations in its surrounding (function) scope.
Scope* current = this;
if (decl->IsVariableDeclaration() &&
decl->AsVariableDeclaration()->AsNested() != nullptr) {
DCHECK_EQ(mode, VAR);
current = decl->AsVariableDeclaration()->AsNested()->scope();
} else if (IsLexicalVariableMode(mode)) {
if (!is_block_scope()) continue;
DCHECK(is_declaration_scope());
DCHECK_EQ(outer_scope()->scope_type(), FUNCTION_SCOPE);
current = outer_scope();
}
// Iterate through all scopes until and including the declaration scope.
while (true) {
// There is a conflict if there exists a non-VAR binding.
Variable* other_var =
current->variables_.Lookup(decl->proxy()->raw_name());
if (other_var != nullptr && IsLexicalVariableMode(other_var->mode())) {
return decl;
}
if (current->is_declaration_scope()) break;
current = current->outer_scope();
}
}
return nullptr;
}
Declaration* Scope::CheckLexDeclarationsConflictingWith(
const ZoneList<const AstRawString*>& names) {
DCHECK(is_block_scope());
for (int i = 0; i < names.length(); ++i) {
Variable* var = LookupLocal(names.at(i));
if (var != nullptr) {
// Conflict; find and return its declaration.
DCHECK(IsLexicalVariableMode(var->mode()));
const AstRawString* name = names.at(i);
for (Declaration* decl : decls_) {
if (decl->proxy()->raw_name() == name) return decl;
}
DCHECK(false);
}
}
return nullptr;
}
void DeclarationScope::AllocateVariables(ParseInfo* info) {
// Module variables must be allocated before variable resolution
// to ensure that UpdateNeedsHoleCheck() can detect import variables.
if (is_module_scope()) AsModuleScope()->AllocateModuleVariables();
ResolveVariablesRecursively(info);
AllocateVariablesRecursively();
}
bool Scope::AllowsLazyParsingWithoutUnresolvedVariables(
const Scope* outer) const {
// If none of the outer scopes need to decide whether to context allocate
// specific variables, we can preparse inner functions without unresolved
// variables. Otherwise we need to find unresolved variables to force context
// allocation of the matching declarations. We can stop at the outer scope for
// the parse, since context allocation of those variables is already
// guaranteed to be correct.
for (const Scope* s = this; s != outer; s = s->outer_scope_) {
// Eval forces context allocation on all outer scopes, so we don't need to
// look at those scopes. Sloppy eval makes top-level non-lexical variables
// dynamic, whereas strict-mode requires context allocation.
if (s->is_eval_scope()) return is_sloppy(s->language_mode());
// Catch scopes force context allocation of all variables.
if (s->is_catch_scope()) continue;
// With scopes do not introduce variables that need allocation.
if (s->is_with_scope()) continue;
DCHECK(s->is_module_scope() || s->is_block_scope() ||
s->is_function_scope());
return false;
}
return true;
}
bool DeclarationScope::AllowsLazyCompilation() const {
return !force_eager_compilation_;
}
int Scope::ContextChainLength(Scope* scope) const {
int n = 0;
for (const Scope* s = this; s != scope; s = s->outer_scope_) {
DCHECK_NOT_NULL(s); // scope must be in the scope chain
if (s->NeedsContext()) n++;
}
return n;
}
int Scope::ContextChainLengthUntilOutermostSloppyEval() const {
int result = 0;
int length = 0;
for (const Scope* s = this; s != nullptr; s = s->outer_scope()) {
if (!s->NeedsContext()) continue;
length++;
if (s->is_declaration_scope() &&
s->AsDeclarationScope()->calls_sloppy_eval()) {
result = length;
}
}
return result;
}
DeclarationScope* Scope::GetDeclarationScope() {
Scope* scope = this;
while (!scope->is_declaration_scope()) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
const DeclarationScope* Scope::GetClosureScope() const {
const Scope* scope = this;
while (!scope->is_declaration_scope() || scope->is_block_scope()) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
DeclarationScope* Scope::GetClosureScope() {
Scope* scope = this;
while (!scope->is_declaration_scope() || scope->is_block_scope()) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
bool Scope::NeedsScopeInfo() const {
DCHECK(!already_resolved_);
DCHECK(GetClosureScope()->ShouldEagerCompile());
// The debugger expects all functions to have scope infos.
// TODO(jochen|yangguo): Remove this requirement.
if (is_function_scope()) return true;
return NeedsContext();
}
bool Scope::ShouldBanArguments() {
return GetReceiverScope()->should_ban_arguments();
}
DeclarationScope* Scope::GetReceiverScope() {
Scope* scope = this;
while (!scope->is_script_scope() &&
(!scope->is_function_scope() ||
scope->AsDeclarationScope()->is_arrow_scope())) {
scope = scope->outer_scope();
}
return scope->AsDeclarationScope();
}
Scope* Scope::GetOuterScopeWithContext() {
Scope* scope = outer_scope_;
while (scope && !scope->NeedsContext()) {
scope = scope->outer_scope();
}
return scope;
}
Handle<StringSet> DeclarationScope::CollectNonLocals(
ParseInfo* info, Handle<StringSet> non_locals) {
VariableProxy* free_variables = FetchFreeVariables(this, info);
for (VariableProxy* proxy = free_variables; proxy != nullptr;
proxy = proxy->next_unresolved()) {
non_locals = StringSet::Add(non_locals, proxy->name());
}
return non_locals;
}
void DeclarationScope::ResetAfterPreparsing(AstValueFactory* ast_value_factory,
bool aborted) {
DCHECK(is_function_scope());
// Reset all non-trivial members.
if (!aborted || !IsArrowFunction(function_kind_)) {
// Do not remove parameters when lazy parsing an Arrow Function has failed,
// as the formal parameters are not re-parsed.
params_.Clear();
}
decls_.Clear();
locals_.Clear();
inner_scope_ = nullptr;
unresolved_ = nullptr;
sloppy_block_function_map_ = nullptr;
rare_data_ = nullptr;
if (aborted) {
// Prepare scope for use in the outer zone.
zone_ = ast_value_factory->zone();
variables_.Reset(ZoneAllocationPolicy(zone_));
if (!IsArrowFunction(function_kind_)) {
DeclareDefaultFunctionVariables(ast_value_factory);
}
} else {
// Make sure this scope isn't used for allocation anymore.
zone_ = nullptr;
variables_.Invalidate();
}
#ifdef DEBUG
needs_migration_ = false;
is_being_lazily_parsed_ = false;
#endif
was_lazily_parsed_ = !aborted;
}
void Scope::SavePreParsedScopeData() {
DCHECK(FLAG_preparser_scope_analysis);
if (ProducedPreParsedScopeData::ScopeIsSkippableFunctionScope(this)) {
AsDeclarationScope()->SavePreParsedScopeDataForDeclarationScope();
}
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
scope->SavePreParsedScopeData();
}
}
void DeclarationScope::SavePreParsedScopeDataForDeclarationScope() {
if (produced_preparsed_scope_data_ != nullptr) {
DCHECK(FLAG_preparser_scope_analysis);
produced_preparsed_scope_data_->SaveScopeAllocationData(this);
}
}
void DeclarationScope::AnalyzePartially(AstNodeFactory* ast_node_factory) {
DCHECK(!force_eager_compilation_);
VariableProxy* unresolved = nullptr;
if (!outer_scope_->is_script_scope() ||
(FLAG_preparser_scope_analysis &&
produced_preparsed_scope_data_ != nullptr &&
produced_preparsed_scope_data_->ContainsInnerFunctions())) {
// Try to resolve unresolved variables for this Scope and migrate those
// which cannot be resolved inside. It doesn't make sense to try to resolve
// them in the outer Scopes here, because they are incomplete.
for (VariableProxy* proxy = FetchFreeVariables(this); proxy != nullptr;
proxy = proxy->next_unresolved()) {
DCHECK(!proxy->is_resolved());
VariableProxy* copy = ast_node_factory->CopyVariableProxy(proxy);
copy->set_next_unresolved(unresolved);
unresolved = copy;
}
// Migrate function_ to the right Zone.
if (function_ != nullptr) {
function_ = ast_node_factory->CopyVariable(function_);
}
if (FLAG_preparser_scope_analysis) {
SavePreParsedScopeData();
}
}
#ifdef DEBUG
if (FLAG_print_scopes) {
PrintF("Inner function scope:\n");
Print();
}
#endif
ResetAfterPreparsing(ast_node_factory->ast_value_factory(), false);
unresolved_ = unresolved;
}
#ifdef DEBUG
namespace {
const char* Header(ScopeType scope_type, FunctionKind function_kind,
bool is_declaration_scope) {
switch (scope_type) {
case EVAL_SCOPE: return "eval";
// TODO(adamk): Should we print concise method scopes specially?
case FUNCTION_SCOPE:
if (IsGeneratorFunction(function_kind)) return "function*";
if (IsAsyncFunction(function_kind)) return "async function";
if (IsArrowFunction(function_kind)) return "arrow";
return "function";
case MODULE_SCOPE: return "module";
case SCRIPT_SCOPE: return "global";
case CATCH_SCOPE: return "catch";
case BLOCK_SCOPE: return is_declaration_scope ? "varblock" : "block";
case WITH_SCOPE: return "with";
}
UNREACHABLE();
}
void Indent(int n, const char* str) { PrintF("%*s%s", n, "", str); }
void PrintName(const AstRawString* name) {
PrintF("%.*s", name->length(), name->raw_data());
}
void PrintLocation(Variable* var) {
switch (var->location()) {
case VariableLocation::UNALLOCATED:
break;
case VariableLocation::PARAMETER:
PrintF("parameter[%d]", var->index());
break;
case VariableLocation::LOCAL:
PrintF("local[%d]", var->index());
break;
case VariableLocation::CONTEXT:
PrintF("context[%d]", var->index());
break;
case VariableLocation::LOOKUP:
PrintF("lookup");
break;
case VariableLocation::MODULE:
PrintF("module");
break;
}
}
void PrintVar(int indent, Variable* var) {
Indent(indent, VariableMode2String(var->mode()));
PrintF(" ");
if (var->raw_name()->IsEmpty())
PrintF(".%p", reinterpret_cast<void*>(var));
else
PrintName(var->raw_name());
PrintF("; // (%p) ", reinterpret_cast<void*>(var));
PrintLocation(var);
bool comma = !var->IsUnallocated();
if (var->has_forced_context_allocation()) {
if (comma) PrintF(", ");
PrintF("forced context allocation");
comma = true;
}
if (var->maybe_assigned() == kNotAssigned) {
if (comma) PrintF(", ");
PrintF("never assigned");
comma = true;
}
if (var->initialization_flag() == kNeedsInitialization &&
!var->binding_needs_init()) {
if (comma) PrintF(", ");
PrintF("hole initialization elided");
}
PrintF("\n");
}
void PrintMap(int indent, const char* label, VariableMap* map, bool locals,
Variable* function_var) {
bool printed_label = false;
for (VariableMap::Entry* p = map->Start(); p != nullptr; p = map->Next(p)) {
Variable* var = reinterpret_cast<Variable*>(p->value);
if (var == function_var) continue;
if (var == kDummyPreParserVariable ||
var == kDummyPreParserLexicalVariable) {
continue;
}
bool local = !IsDynamicVariableMode(var->mode());
if ((locals ? local : !local) &&
(var->is_used() || !var->IsUnallocated())) {
if (!printed_label) {
Indent(indent, label);
printed_label = true;
}
PrintVar(indent, var);
}
}
}
} // anonymous namespace
void DeclarationScope::PrintParameters() {
PrintF(" (");
for (int i = 0; i < params_.length(); i++) {
if (i > 0) PrintF(", ");
const AstRawString* name = params_[i]->raw_name();
if (name->IsEmpty())
PrintF(".%p", reinterpret_cast<void*>(params_[i]));
else
PrintName(name);
}
PrintF(")");
}
void Scope::Print(int n) {
int n0 = (n > 0 ? n : 0);
int n1 = n0 + 2; // indentation
// Print header.
FunctionKind function_kind = is_function_scope()
? AsDeclarationScope()->function_kind()
: kNormalFunction;
Indent(n0, Header(scope_type_, function_kind, is_declaration_scope()));
if (scope_name_ != nullptr && !scope_name_->IsEmpty()) {
PrintF(" ");
PrintName(scope_name_);
}
// Print parameters, if any.
Variable* function = nullptr;
if (is_function_scope()) {
AsDeclarationScope()->PrintParameters();
function = AsDeclarationScope()->function_var();
}
PrintF(" { // (%p) (%d, %d)\n", reinterpret_cast<void*>(this),
start_position(), end_position());
if (is_hidden()) {
Indent(n1, "// is hidden\n");
}
// Function name, if any (named function literals, only).
if (function != nullptr) {
Indent(n1, "// (local) function name: ");
PrintName(function->raw_name());
PrintF("\n");
}
// Scope info.
if (is_strict(language_mode())) {
Indent(n1, "// strict mode scope\n");
}
if (IsAsmModule()) Indent(n1, "// scope is an asm module\n");
if (is_declaration_scope() && AsDeclarationScope()->calls_sloppy_eval()) {
Indent(n1, "// scope calls sloppy 'eval'\n");
}
if (is_declaration_scope() && AsDeclarationScope()->NeedsHomeObject()) {
Indent(n1, "// scope needs home object\n");
}
if (inner_scope_calls_eval_) Indent(n1, "// inner scope calls 'eval'\n");
if (is_declaration_scope()) {
DeclarationScope* scope = AsDeclarationScope();
if (scope->was_lazily_parsed()) Indent(n1, "// lazily parsed\n");
if (scope->ShouldEagerCompile()) Indent(n1, "// will be compiled\n");
}
if (num_stack_slots_ > 0) {
Indent(n1, "// ");
PrintF("%d stack slots\n", num_stack_slots_);
}
if (num_heap_slots_ > 0) {
Indent(n1, "// ");
PrintF("%d heap slots\n", num_heap_slots_);
}
// Print locals.
if (function != nullptr) {
Indent(n1, "// function var:\n");
PrintVar(n1, function);
}
// Print temporaries.
{
bool printed_header = false;
for (Variable* local : locals_) {
if (local->mode() != TEMPORARY) continue;
if (!printed_header) {
printed_header = true;
Indent(n1, "// temporary vars:\n");
}
PrintVar(n1, local);
}
}
if (variables_.occupancy() > 0) {
PrintMap(n1, "// local vars:\n", &variables_, true, function);
PrintMap(n1, "// dynamic vars:\n", &variables_, false, function);
}
// Print inner scopes (disable by providing negative n).
if (n >= 0) {
for (Scope* scope = inner_scope_; scope != nullptr;
scope = scope->sibling_) {
PrintF("\n");
scope->Print(n1);
}
}
Indent(n0, "}\n");
}
void Scope::CheckScopePositions() {
// Visible leaf scopes must have real positions.
if (!is_hidden() && inner_scope_ == nullptr) {
DCHECK_NE(kNoSourcePosition, start_position());
DCHECK_NE(kNoSourcePosition, end_position());
}
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
scope->CheckScopePositions();
}
}
void Scope::CheckZones() {
DCHECK(!needs_migration_);
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
if (scope->is_declaration_scope() &&
scope->AsDeclarationScope()->was_lazily_parsed()) {
DCHECK_NULL(scope->zone());
DCHECK_NULL(scope->inner_scope_);
continue;
}
scope->CheckZones();
}
}
#endif // DEBUG
Variable* Scope::NonLocal(const AstRawString* name, VariableMode mode) {
// Declare a new non-local.
DCHECK(IsDynamicVariableMode(mode));
Variable* var = variables_.Declare(zone(), nullptr, name, mode);
// Allocate it by giving it a dynamic lookup.
var->AllocateTo(VariableLocation::LOOKUP, -1);
return var;
}
Variable* Scope::LookupRecursive(VariableProxy* proxy, Scope* outer_scope_end) {
DCHECK_NE(outer_scope_end, this);
// Short-cut: whenever we find a debug-evaluate scope, just look everything up
// dynamically. Debug-evaluate doesn't properly create scope info for the
// lookups it does. It may not have a valid 'this' declaration, and anything
// accessed through debug-evaluate might invalidly resolve to stack-allocated
// variables.
// TODO(yangguo): Remove once debug-evaluate creates proper ScopeInfo for the
// scopes in which it's evaluating.
if (is_debug_evaluate_scope_) return NonLocal(proxy->raw_name(), DYNAMIC);
// Try to find the variable in this scope.
Variable* var = LookupLocal(proxy->raw_name());
// We found a variable and we are done. (Even if there is an 'eval' in this
// scope which introduces the same variable again, the resulting variable
// remains the same.)
if (var != nullptr) return var;
if (outer_scope_ == outer_scope_end) {
// We may just be trying to find all free variables. In that case, don't
// declare them in the outer scope.
if (!is_script_scope()) return nullptr;
// No binding has been found. Declare a variable on the global object.
return AsDeclarationScope()->DeclareDynamicGlobal(proxy->raw_name(),
NORMAL_VARIABLE);
}
DCHECK(!is_script_scope());
var = outer_scope_->LookupRecursive(proxy, outer_scope_end);
// The variable could not be resolved statically.
if (var == nullptr) return var;
// TODO(marja): Separate LookupRecursive for preparsed scopes better.
if (var == kDummyPreParserVariable || var == kDummyPreParserLexicalVariable) {
DCHECK(GetDeclarationScope()->is_being_lazily_parsed());
DCHECK(FLAG_lazy_inner_functions);
return var;
}
if (is_function_scope() && !var->is_dynamic()) {
var->ForceContextAllocation();
}
// "this" can't be shadowed by "eval"-introduced bindings or by "with"
// scopes.
// TODO(wingo): There are other variables in this category; add them.
if (var->is_this()) return var;
if (is_with_scope()) {
// The current scope is a with scope, so the variable binding can not be
// statically resolved. However, note that it was necessary to do a lookup
// in the outer scope anyway, because if a binding exists in an outer
// scope, the associated variable has to be marked as potentially being
// accessed from inside of an inner with scope (the property may not be in
// the 'with' object).
if (!var->is_dynamic() && var->IsUnallocated()) {
DCHECK(!already_resolved_);
var->set_is_used();
var->ForceContextAllocation();
if (proxy->is_assigned()) var->set_maybe_assigned();
}
return NonLocal(proxy->raw_name(), DYNAMIC);
}
if (is_declaration_scope() && AsDeclarationScope()->calls_sloppy_eval()) {
// A variable binding may have been found in an outer scope, but the current
// scope makes a sloppy 'eval' call, so the found variable may not be the
// correct one (the 'eval' may introduce a binding with the same name). In
// that case, change the lookup result to reflect this situation. Only
// scopes that can host var bindings (declaration scopes) need be considered
// here (this excludes block and catch scopes), and variable lookups at
// script scope are always dynamic.
if (var->IsGlobalObjectProperty()) {
return NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL);
}
if (var->is_dynamic()) return var;
Variable* invalidated = var;
var = NonLocal(proxy->raw_name(), DYNAMIC_LOCAL);
var->set_local_if_not_shadowed(invalidated);
}
return var;
}
void Scope::ResolveVariable(ParseInfo* info, VariableProxy* proxy) {
DCHECK(info->script_scope()->is_script_scope());
DCHECK(!proxy->is_resolved());
Variable* var = LookupRecursive(proxy, nullptr);
ResolveTo(info, proxy, var);
}
namespace {
void SetNeedsHoleCheck(Variable* var, VariableProxy* proxy) {
proxy->set_needs_hole_check();
var->ForceHoleInitialization();
}
void UpdateNeedsHoleCheck(Variable* var, VariableProxy* proxy, Scope* scope) {
if (var->mode() == DYNAMIC_LOCAL) {
// Dynamically introduced variables never need a hole check (since they're
// VAR bindings, either from var or function declarations), but the variable
// they shadow might need a hole check, which we want to do if we decide
// that no shadowing variable was dynamically introoduced.
DCHECK_EQ(kCreatedInitialized, var->initialization_flag());
return UpdateNeedsHoleCheck(var->local_if_not_shadowed(), proxy, scope);
}
if (var->initialization_flag() == kCreatedInitialized) return;
// It's impossible to eliminate module import hole checks here, because it's
// unknown at compilation time whether the binding referred to in the
// exporting module itself requires hole checks.
if (var->location() == VariableLocation::MODULE && !var->IsExport()) {
return SetNeedsHoleCheck(var, proxy);
}
// Check if the binding really needs an initialization check. The check
// can be skipped in the following situation: we have a LET or CONST
// binding, both the Variable and the VariableProxy have the same
// declaration scope (i.e. they are both in global code, in the
// same function or in the same eval code), the VariableProxy is in
// the source physically located after the initializer of the variable,
// and that the initializer cannot be skipped due to a nonlinear scope.
//
// The condition on the closure scopes is a conservative check for
// nested functions that access a binding and are called before the
// binding is initialized:
// function() { f(); let x = 1; function f() { x = 2; } }
//
// The check cannot be skipped on non-linear scopes, namely switch
// scopes, to ensure tests are done in cases like the following:
// switch (1) { case 0: let x = 2; case 1: f(x); }
// The scope of the variable needs to be checked, in case the use is
// in a sub-block which may be linear.
if (var->scope()->GetClosureScope() != scope->GetClosureScope()) {
return SetNeedsHoleCheck(var, proxy);
}
if (var->is_this()) {
DCHECK(IsDerivedConstructor(scope->GetClosureScope()->function_kind()));
// TODO(littledan): implement 'this' hole check elimination.
return SetNeedsHoleCheck(var, proxy);
}
// We should always have valid source positions.
DCHECK_NE(var->initializer_position(), kNoSourcePosition);
DCHECK_NE(proxy->position(), kNoSourcePosition);
if (var->scope()->is_nonlinear() ||
var->initializer_position() >= proxy->position()) {
return SetNeedsHoleCheck(var, proxy);
}
}
} // anonymous namespace
void Scope::ResolveTo(ParseInfo* info, VariableProxy* proxy, Variable* var) {
#ifdef DEBUG
if (info->is_native()) {
// To avoid polluting the global object in native scripts
// - Variables must not be allocated to the global scope.
DCHECK_NOT_NULL(outer_scope());
// - Variables must be bound locally or unallocated.
if (var->IsGlobalObjectProperty()) {
// The following variable name may be minified. If so, disable
// minification in js2c.py for better output.
Handle<String> name = proxy->raw_name()->string();
V8_Fatal(__FILE__, __LINE__, "Unbound variable: '%s' in native script.",
name->ToCString().get());
}
VariableLocation location = var->location();
DCHECK(location == VariableLocation::LOCAL ||
location == VariableLocation::CONTEXT ||
location == VariableLocation::PARAMETER ||
location == VariableLocation::UNALLOCATED);
}
#endif
DCHECK_NOT_NULL(var);
UpdateNeedsHoleCheck(var, proxy, this);
proxy->BindTo(var);
}
void Scope::ResolveVariablesRecursively(ParseInfo* info) {
DCHECK(info->script_scope()->is_script_scope());
// Lazy parsed declaration scopes are already partially analyzed. If there are
// unresolved references remaining, they just need to be resolved in outer
// scopes.
if (is_declaration_scope() && AsDeclarationScope()->was_lazily_parsed()) {
DCHECK_EQ(variables_.occupancy(), 0);
for (VariableProxy* proxy = unresolved_; proxy != nullptr;
proxy = proxy->next_unresolved()) {
Variable* var = outer_scope()->LookupRecursive(proxy, nullptr);
if (!var->is_dynamic()) {
var->set_is_used();
var->ForceContextAllocation();
if (proxy->is_assigned()) var->set_maybe_assigned();
}
}
} else {
// Resolve unresolved variables for this scope.
for (VariableProxy* proxy = unresolved_; proxy != nullptr;
proxy = proxy->next_unresolved()) {
ResolveVariable(info, proxy);
}
// Resolve unresolved variables for inner scopes.
for (Scope* scope = inner_scope_; scope != nullptr;
scope = scope->sibling_) {
scope->ResolveVariablesRecursively(info);
}
}
}
VariableProxy* Scope::FetchFreeVariables(DeclarationScope* max_outer_scope,
ParseInfo* info,
VariableProxy* stack) {
// Module variables must be allocated before variable resolution
// to ensure that UpdateNeedsHoleCheck() can detect import variables.
if (info != nullptr && is_module_scope()) {
AsModuleScope()->AllocateModuleVariables();
}
// Lazy parsed declaration scopes are already partially analyzed. If there are
// unresolved references remaining, they just need to be resolved in outer
// scopes.
Scope* lookup =
is_declaration_scope() && AsDeclarationScope()->was_lazily_parsed()
? outer_scope()
: this;
for (VariableProxy *proxy = unresolved_, *next = nullptr; proxy != nullptr;
proxy = next) {
next = proxy->next_unresolved();
DCHECK(!proxy->is_resolved());
Variable* var =
lookup->LookupRecursive(proxy, max_outer_scope->outer_scope());
if (var == nullptr) {
proxy->set_next_unresolved(stack);
stack = proxy;
} else if (var != kDummyPreParserVariable &&
var != kDummyPreParserLexicalVariable) {
if (info != nullptr) {
// In this case we need to leave scopes in a way that they can be
// allocated. If we resolved variables from lazy parsed scopes, we need
// to context allocate the var.
ResolveTo(info, proxy, var);
if (!var->is_dynamic() && lookup != this) var->ForceContextAllocation();
} else {
var->set_is_used();
if (proxy->is_assigned()) {
var->set_maybe_assigned();
}
}
}
}
// Clear unresolved_ as it's in an inconsistent state.
unresolved_ = nullptr;
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
stack = scope->FetchFreeVariables(max_outer_scope, info, stack);
}
return stack;
}
bool Scope::MustAllocate(Variable* var) {
if (var == kDummyPreParserLexicalVariable || var == kDummyPreParserVariable) {
return true;
}
DCHECK(var->location() != VariableLocation::MODULE);
// Give var a read/write use if there is a chance it might be accessed
// via an eval() call. This is only possible if the variable has a
// visible name.
if ((var->is_this() || !var->raw_name()->IsEmpty()) &&
(inner_scope_calls_eval_ || is_catch_scope() || is_script_scope())) {
var->set_is_used();
if (inner_scope_calls_eval_) var->set_maybe_assigned();
}
DCHECK(!var->has_forced_context_allocation() || var->is_used());
// Global variables do not need to be allocated.
return !var->IsGlobalObjectProperty() && var->is_used();
}
bool Scope::MustAllocateInContext(Variable* var) {
// If var is accessed from an inner scope, or if there is a possibility
// that it might be accessed from the current or an inner scope (through
// an eval() call or a runtime with lookup), it must be allocated in the
// context.
//
// Temporary variables are always stack-allocated. Catch-bound variables are
// always context-allocated.
if (var->mode() == TEMPORARY) return false;
if (is_catch_scope()) return true;
if ((is_script_scope() || is_eval_scope()) &&
IsLexicalVariableMode(var->mode())) {
return true;
}
return var->has_forced_context_allocation() || inner_scope_calls_eval_;
}
void Scope::AllocateStackSlot(Variable* var) {
if (is_block_scope()) {
outer_scope()->GetDeclarationScope()->AllocateStackSlot(var);
} else {
var->AllocateTo(VariableLocation::LOCAL, num_stack_slots_++);
}
}
void Scope::AllocateHeapSlot(Variable* var) {
var->AllocateTo(VariableLocation::CONTEXT, num_heap_slots_++);
}
void DeclarationScope::AllocateParameterLocals() {
DCHECK(is_function_scope());
bool uses_sloppy_arguments = false;
if (arguments_ != nullptr) {
DCHECK(!is_arrow_scope());
// 'arguments' is used. Unless there is also a parameter called
// 'arguments', we must be conservative and allocate all parameters to
// the context assuming they will be captured by the arguments object.
// If we have a parameter named 'arguments', a (new) value is always
// assigned to it via the function invocation. Then 'arguments' denotes
// that specific parameter value and cannot be used to access the
// parameters, which is why we don't need to allocate an arguments
// object in that case.
if (MustAllocate(arguments_) && !has_arguments_parameter_) {
// In strict mode 'arguments' does not alias formal parameters.
// Therefore in strict mode we allocate parameters as if 'arguments'
// were not used.
// If the parameter list is not simple, arguments isn't sloppy either.
uses_sloppy_arguments =
is_sloppy(language_mode()) && has_simple_parameters();
} else {
// 'arguments' is unused. Tell the code generator that it does not need to
// allocate the arguments object by nulling out arguments_.
arguments_ = nullptr;
}
}
// The same parameter may occur multiple times in the parameters_ list.
// If it does, and if it is not copied into the context object, it must
// receive the highest parameter index for that parameter; thus iteration
// order is relevant!
for (int i = num_parameters() - 1; i >= 0; --i) {
Variable* var = params_[i];
DCHECK(!has_rest_ || var != rest_parameter());
DCHECK_EQ(this, var->scope());
if (uses_sloppy_arguments) {
var->set_is_used();
var->set_maybe_assigned();
var->ForceContextAllocation();
}
AllocateParameter(var, i);
}
}
void DeclarationScope::AllocateParameter(Variable* var, int index) {
if (MustAllocate(var)) {
if (has_forced_context_allocation_for_parameters() ||
MustAllocateInContext(var)) {
DCHECK(var->IsUnallocated() || var->IsContextSlot());
if (var->IsUnallocated()) {
AllocateHeapSlot(var);
}
} else {
DCHECK(var->IsUnallocated() || var->IsParameter());
if (var->IsUnallocated()) {
var->AllocateTo(VariableLocation::PARAMETER, index);
}
}
}
}
void DeclarationScope::AllocateReceiver() {
if (!has_this_declaration()) return;
DCHECK_NOT_NULL(receiver());
DCHECK_EQ(receiver()->scope(), this);
AllocateParameter(receiver(), -1);
}
void Scope::AllocateNonParameterLocal(Variable* var) {
DCHECK(var->scope() == this);
if (var->IsUnallocated() && MustAllocate(var)) {
if (MustAllocateInContext(var)) {
AllocateHeapSlot(var);
} else {
AllocateStackSlot(var);
}
}
}
void Scope::AllocateNonParameterLocalsAndDeclaredGlobals() {
for (Variable* local : locals_) {
AllocateNonParameterLocal(local);
}
if (is_declaration_scope()) {
AsDeclarationScope()->AllocateLocals();
}
}
void DeclarationScope::AllocateLocals() {
// For now, function_ must be allocated at the very end. If it gets
// allocated in the context, it must be the last slot in the context,
// because of the current ScopeInfo implementation (see
// ScopeInfo::ScopeInfo(FunctionScope* scope) constructor).
if (function_ != nullptr && MustAllocate(function_)) {
AllocateNonParameterLocal(function_);
} else {
function_ = nullptr;
}
DCHECK(!has_rest_ || !MustAllocate(rest_parameter()) ||
!rest_parameter()->IsUnallocated());
if (new_target_ != nullptr && !MustAllocate(new_target_)) {
new_target_ = nullptr;
}
NullifyRareVariableIf(RareVariable::kThisFunction,
[=](Variable* var) { return !MustAllocate(var); });
}
void ModuleScope::AllocateModuleVariables() {
for (const auto& it : module()->regular_imports()) {
Variable* var = LookupLocal(it.first);
var->AllocateTo(VariableLocation::MODULE, it.second->cell_index);
DCHECK(!var->IsExport());
}
for (const auto& it : module()->regular_exports()) {
Variable* var = LookupLocal(it.first);
var->AllocateTo(VariableLocation::MODULE, it.second->cell_index);
DCHECK(var->IsExport());
}
}
void Scope::AllocateVariablesRecursively() {
DCHECK(!already_resolved_);
DCHECK_IMPLIES(!FLAG_preparser_scope_analysis, num_stack_slots_ == 0);
// Don't allocate variables of preparsed scopes.
if (is_declaration_scope() && AsDeclarationScope()->was_lazily_parsed()) {
return;
}
// Allocate variables for inner scopes.
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
scope->AllocateVariablesRecursively();
}
DCHECK(!already_resolved_);
DCHECK_EQ(Context::MIN_CONTEXT_SLOTS, num_heap_slots_);
// Allocate variables for this scope.
// Parameters must be allocated first, if any.
if (is_declaration_scope()) {
if (is_function_scope()) {
AsDeclarationScope()->AllocateParameterLocals();
}
AsDeclarationScope()->AllocateReceiver();
}
AllocateNonParameterLocalsAndDeclaredGlobals();
// Force allocation of a context for this scope if necessary. For a 'with'
// scope and for a function scope that makes an 'eval' call we need a context,
// even if no local variables were statically allocated in the scope.
// Likewise for modules and function scopes representing asm.js modules.
bool must_have_context =
is_with_scope() || is_module_scope() || IsAsmModule() ||
(is_function_scope() && AsDeclarationScope()->calls_sloppy_eval()) ||
(is_block_scope() && is_declaration_scope() &&
AsDeclarationScope()->calls_sloppy_eval());
// If we didn't allocate any locals in the local context, then we only
// need the minimal number of slots if we must have a context.
if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS && !must_have_context) {
num_heap_slots_ = 0;
}
// Allocation done.
DCHECK(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
}
void Scope::AllocateScopeInfosRecursively(Isolate* isolate,
MaybeHandle<ScopeInfo> outer_scope) {
DCHECK(scope_info_.is_null());
MaybeHandle<ScopeInfo> next_outer_scope = outer_scope;
if (NeedsScopeInfo()) {
scope_info_ = ScopeInfo::Create(isolate, zone(), this, outer_scope);
// The ScopeInfo chain should mirror the context chain, so we only link to
// the next outer scope that needs a context.
if (NeedsContext()) next_outer_scope = scope_info_;
}
// Allocate ScopeInfos for inner scopes.
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
if (!scope->is_function_scope() ||
scope->AsDeclarationScope()->ShouldEagerCompile()) {
scope->AllocateScopeInfosRecursively(isolate, next_outer_scope);
}
}
}
void Scope::AllocateDebuggerScopeInfos(Isolate* isolate,
MaybeHandle<ScopeInfo> outer_scope) {
if (scope_info_.is_null()) {
scope_info_ = ScopeInfo::Create(isolate, zone(), this, outer_scope);
}
MaybeHandle<ScopeInfo> outer = NeedsContext() ? scope_info_ : outer_scope;
for (Scope* scope = inner_scope_; scope != nullptr; scope = scope->sibling_) {
if (scope->is_function_scope()) continue;
scope->AllocateDebuggerScopeInfos(isolate, outer);
}
}
// static
void DeclarationScope::AllocateScopeInfos(ParseInfo* info, Isolate* isolate,
AnalyzeMode mode) {
DeclarationScope* scope = info->literal()->scope();
if (!scope->scope_info_.is_null()) return; // Allocated by outer function.
MaybeHandle<ScopeInfo> outer_scope;
if (scope->outer_scope_ != nullptr) {
outer_scope = scope->outer_scope_->scope_info_;
}
scope->AllocateScopeInfosRecursively(isolate, outer_scope);
if (mode == AnalyzeMode::kDebugger) {
scope->AllocateDebuggerScopeInfos(isolate, outer_scope);
}
// The debugger expects all shared function infos to contain a scope info.
// Since the top-most scope will end up in a shared function info, make sure
// it has one, even if it doesn't need a scope info.
// TODO(jochen|yangguo): Remove this requirement.
if (scope->scope_info_.is_null()) {
scope->scope_info_ =
ScopeInfo::Create(isolate, scope->zone(), scope, outer_scope);
}
// Ensuring that the outer script scope has a scope info avoids having
// special case for native contexts vs other contexts.
if (info->script_scope() && info->script_scope()->scope_info_.is_null()) {
info->script_scope()->scope_info_ = handle(ScopeInfo::Empty(isolate));
}
}
int Scope::StackLocalCount() const {
Variable* function =
is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;
return num_stack_slots() -
(function != nullptr && function->IsStackLocal() ? 1 : 0);
}
int Scope::ContextLocalCount() const {
if (num_heap_slots() == 0) return 0;
Variable* function =
is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;
bool is_function_var_in_context =
function != nullptr && function->IsContextSlot();
return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
(is_function_var_in_context ? 1 : 0);
}
} // namespace internal
} // namespace v8