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LibJS: Use local variables for function declarations when possible

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Previously, the usage of local variables was limited for all function
declarations. This change relaxes the restriction and only prohibits
locals for hoistable annexB declarations.
This commit is contained in:
Aliaksandr Kalenik 2023-07-08 19:31:41 +02:00 • committed by Andreas Kling
parent 167495b87b
commit 8b6450842e
Notes: sideshowbarker 2024-07-16 23:57:20 +09:00
4 changed files with 36 additions and 26 deletions
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8
Userland/Libraries/LibJS/AST.cpp
View file

@ -4769,8 +4769,12 @@ void ScopeNode::block_declaration_instantiation(VM& vm, Environment* environment
if (is<FunctionDeclaration>(declaration)) {
auto& function_declaration = static_cast<FunctionDeclaration const&>(declaration);
auto function = ECMAScriptFunctionObject::create(realm, function_declaration.name(), function_declaration.source_text(), function_declaration.body(), function_declaration.parameters(), function_declaration.function_length(), function_declaration.local_variables_names(), environment, private_environment, function_declaration.kind(), function_declaration.is_strict_mode(), function_declaration.might_need_arguments_object(), function_declaration.contains_direct_call_to_eval());
VERIFY(is<DeclarativeEnvironment>(*environment));
static_cast<DeclarativeEnvironment&>(*environment).initialize_or_set_mutable_binding({}, vm, function_declaration.name(), function);
if (vm.bytecode_interpreter_if_exists() && function_declaration.name_identifier()->is_local()) {
vm.running_execution_context().local_variables[function_declaration.name_identifier()->local_variable_index()] = function;
} else {
VERIFY(is<DeclarativeEnvironment>(*environment));
static_cast<DeclarativeEnvironment&>(*environment).initialize_or_set_mutable_binding({}, vm, function_declaration.name(), function);
}
}
}));
}

1
Userland/Libraries/LibJS/AST.h
View file

@ -707,6 +707,7 @@ struct FunctionParameter {
class FunctionNode {
public:
StringView name() const { return m_name ? m_name->string().view() : ""sv; }
RefPtr<Identifier const> name_identifier() const { return m_name; }
DeprecatedString const& source_text() const { return m_source_text; }
Statement const& body() const { return *m_body; }
Vector<FunctionParameter> const& parameters() const { return m_parameters; }

47
Userland/Libraries/LibJS/Parser.cpp
View file

@ -283,18 +283,6 @@ public:
return;
}
for (size_t i = 0; i < m_functions_to_hoist.size(); i++) {
auto const& function_declaration = m_functions_to_hoist[i];
if (m_lexical_names.contains(function_declaration->name()) || m_forbidden_var_names.contains(function_declaration->name()))
continue;
if (is_top_level()) {
m_node->add_hoisted_function(move(m_functions_to_hoist[i]));
} else {
if (!m_parent_scope->m_lexical_names.contains(function_declaration->name()) && !m_parent_scope->m_function_names.contains(function_declaration->name()))
m_parent_scope->m_functions_to_hoist.append(move(m_functions_to_hoist[i]));
}
}
for (auto& it : m_identifier_groups) {
auto const& identifier_group_name = it.key;
auto& identifier_group = it.value;
@ -316,20 +304,21 @@ public:
scope_has_declaration = true;
}));
bool function_declaration = false;
MUST(m_node->for_each_var_function_declaration_in_reverse_order([&](auto const& declaration) {
if (declaration.name() == identifier_group_name)
function_declaration = true;
scope_has_declaration = true;
}));
MUST(m_node->for_each_lexical_function_declaration_in_reverse_order([&](auto const& declaration) {
if (declaration.name() == identifier_group_name)
function_declaration = true;
}));
MUST(m_node->for_each_function_hoistable_with_annexB_extension([&](auto const& declaration) {
if (declaration.name() == identifier_group_name)
function_declaration = true;
scope_has_declaration = true;
}));
bool hoistable_function_declaration = false;
for (auto const& function_declaration : m_functions_to_hoist) {
if (function_declaration->name() == identifier_group_name)
hoistable_function_declaration = true;
}
if ((m_type == ScopeType::ClassDeclaration || m_type == ScopeType::Catch) && m_bound_names.contains(identifier_group_name)) {
// NOTE: Currently class names and catch section parameters are not considered to become local variables
// but this might be fixed in the future
@ -346,7 +335,7 @@ public:
}
if (scope_has_declaration) {
if (function_declaration)
if (hoistable_function_declaration)
continue;
if (!identifier_group.captured_by_nested_function) {
@ -377,6 +366,18 @@ public:
}
}
for (size_t i = 0; i < m_functions_to_hoist.size(); i++) {
auto const& function_declaration = m_functions_to_hoist[i];
if (m_lexical_names.contains(function_declaration->name()) || m_forbidden_var_names.contains(function_declaration->name()))
continue;
if (is_top_level()) {
m_node->add_hoisted_function(move(m_functions_to_hoist[i]));
} else {
if (!m_parent_scope->m_lexical_names.contains(function_declaration->name()) && !m_parent_scope->m_function_names.contains(function_declaration->name()))
m_parent_scope->m_functions_to_hoist.append(move(m_functions_to_hoist[i]));
}
}
VERIFY(m_parser.m_state.current_scope_pusher == this);
m_parser.m_state.current_scope_pusher = m_parent_scope;
}
@ -2799,15 +2800,15 @@ NonnullRefPtr<FunctionNodeType> Parser::parse_function_node(u16 parse_options, O
}
if (parse_options & FunctionNodeParseOptions::HasDefaultExportName) {
name = create_ast_node<Identifier const>(
name = create_identifier_and_register_in_current_scope(
{ m_source_code, rule_start.position(), position() },
ExportStatement::local_name_for_default);
} else if (FunctionNodeType::must_have_name() || match_identifier()) {
name = create_ast_node<Identifier const>(
name = create_identifier_and_register_in_current_scope(
{ m_source_code, rule_start.position(), position() },
consume_identifier().DeprecatedFlyString_value());
} else if (is_function_expression && (match(TokenType::Yield) || match(TokenType::Await))) {
name = create_ast_node<Identifier const>(
name = create_identifier_and_register_in_current_scope(
{ m_source_code, rule_start.position(), position() },
consume().DeprecatedFlyString_value());
}

6
Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
View file

@ -616,7 +616,11 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::function_declaration_instantia
auto private_environment = callee_context.private_environment;
for (auto& declaration : functions_to_initialize) {
auto function = ECMAScriptFunctionObject::create(realm, declaration.name(), declaration.source_text(), declaration.body(), declaration.parameters(), declaration.function_length(), declaration.local_variables_names(), lex_environment, private_environment, declaration.kind(), declaration.is_strict_mode(), declaration.might_need_arguments_object(), declaration.contains_direct_call_to_eval());
MUST(var_environment->set_mutable_binding(vm, declaration.name(), function, false));
if ((vm.bytecode_interpreter_if_exists() || kind() == FunctionKind::Generator) && declaration.name_identifier()->is_local()) {
callee_context.local_variables[declaration.name_identifier()->local_variable_index()] = function;
} else {
MUST(var_environment->set_mutable_binding(vm, declaration.name(), function, false));
}
}
if (is<DeclarativeEnvironment>(*lex_environment))