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LibWeb+LibJS: Skip function environment allocation if possible
If a function has the following properties: - uses only local variables and registers - does not use `this` - does not use `new.target` - does not use `super` - does not use direct eval() calls then it is possible to entirely skip function environment allocation because it will never be used This change adds gathering of information whether a function needs to access `this` from environment and updates `prepare_for_ordinary_call()` to skip allocation when possible. For now, this optimisation is too aggressively blocked; e.g. if `this` is used in a function scope, then all functions in outer scopes have to allocate an environment. It could be improved in the future, although this implementation already allows skipping >80% of environment allocations on Discord, GitHub and Twitter.
This commit is contained in:
Aliaksandr Kalenik
Andreas Kling
parent
aede010096
commit
4d5823a5bc
Notes:
sideshowbarker
2024-07-17 06:20:50 +09:00
Author: https://github.com/kalenikaliaksandr
Commit: 4d5823a5bc
Pull-request: https://github.com/SerenityOS/serenity/pull/24194
12 changed files with 94 additions and 46 deletions
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@ -33,7 +33,7 @@ namespace JS {
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JS_DEFINE_ALLOCATOR(ECMAScriptFunctionObject);
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NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
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NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, UsesThis uses_this, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
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{
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Object* prototype = nullptr;
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switch (kind) {
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@ -50,15 +50,15 @@ NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& r
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prototype = realm.intrinsics().async_generator_function_prototype();
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break;
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}
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return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, move(local_variables_names), parent_environment, private_environment, *prototype, kind, is_strict, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
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return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, move(local_variables_names), parent_environment, private_environment, *prototype, kind, is_strict, uses_this, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
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}
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NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, Object& prototype, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
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NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, Object& prototype, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, UsesThis uses_this, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
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{
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return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, move(local_variables_names), parent_environment, private_environment, prototype, kind, is_strict, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
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return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, move(local_variables_names), parent_environment, private_environment, prototype, kind, is_strict, uses_this, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
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}
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ECMAScriptFunctionObject::ECMAScriptFunctionObject(DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> formal_parameters, i32 function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind kind, bool strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
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ECMAScriptFunctionObject::ECMAScriptFunctionObject(DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> formal_parameters, i32 function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind kind, bool strict, UsesThis uses_this, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
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: FunctionObject(prototype)
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, m_name(move(name))
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, m_function_length(function_length)
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@ -327,6 +327,8 @@ ECMAScriptFunctionObject::ECMAScriptFunctionObject(DeprecatedFlyString name, Byt
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(*lex_environment_size)++;
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}));
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}
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m_function_environment_needed = m_arguments_object_needed || m_function_environment_bindings_count > 0 || m_var_environment_bindings_count > 0 || m_lex_environment_bindings_count > 0 || uses_this == UsesThis::Yes || m_contains_direct_call_to_eval;
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}
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void ECMAScriptFunctionObject::initialize(Realm& realm)
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@ -405,7 +407,8 @@ ThrowCompletionOr<Value> ECMAScriptFunctionObject::internal_call(Value this_argu
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}
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// 5. Perform OrdinaryCallBindThis(F, calleeContext, thisArgument).
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ordinary_call_bind_this(*callee_context, this_argument);
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if (m_function_environment_needed)
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ordinary_call_bind_this(*callee_context, this_argument);
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// 6. Let result be Completion(OrdinaryCallEvaluateBody(F, argumentsList)).
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auto result = ordinary_call_evaluate_body();
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@ -464,7 +467,8 @@ ThrowCompletionOr<NonnullGCPtr<Object>> ECMAScriptFunctionObject::internal_const
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// 6. If kind is base, then
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if (kind == ConstructorKind::Base) {
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// a. Perform OrdinaryCallBindThis(F, calleeContext, thisArgument).
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ordinary_call_bind_this(*callee_context, this_argument);
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if (m_function_environment_needed)
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ordinary_call_bind_this(*callee_context, this_argument);
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// b. Let initializeResult be Completion(InitializeInstanceElements(thisArgument, F)).
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auto initialize_result = this_argument->initialize_instance_elements(*this);
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@ -929,7 +933,7 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::function_declaration_instantia
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for (auto& declaration : m_functions_to_initialize) {
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// a. Let fn be the sole element of the BoundNames of f.
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// b. Let fo be InstantiateFunctionObject of f with arguments lexEnv and privateEnv.
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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());
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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.uses_this(), declaration.might_need_arguments_object(), declaration.contains_direct_call_to_eval());
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// c. Perform ! varEnv.SetMutableBinding(fn, fo, false).
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if (declaration.name_identifier()->is_local()) {
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@ -984,15 +988,20 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::prepare_for_ordinary_call(Exec
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// 6. Set the ScriptOrModule of calleeContext to F.[[ScriptOrModule]].
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callee_context.script_or_module = m_script_or_module;
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// 7. Let localEnv be NewFunctionEnvironment(F, newTarget).
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auto local_environment = new_function_environment(*this, new_target);
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local_environment->ensure_capacity(m_function_environment_bindings_count);
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if (m_function_environment_needed) {
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// 7. Let localEnv be NewFunctionEnvironment(F, newTarget).
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auto local_environment = new_function_environment(*this, new_target);
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local_environment->ensure_capacity(m_function_environment_bindings_count);
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// 8. Set the LexicalEnvironment of calleeContext to localEnv.
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callee_context.lexical_environment = local_environment;
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// 8. Set the LexicalEnvironment of calleeContext to localEnv.
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callee_context.lexical_environment = local_environment;
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// 9. Set the VariableEnvironment of calleeContext to localEnv.
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callee_context.variable_environment = local_environment;
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// 9. Set the VariableEnvironment of calleeContext to localEnv.
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callee_context.variable_environment = local_environment;
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} else {
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callee_context.lexical_environment = environment();
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callee_context.variable_environment = environment();
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}
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// 10. Set the PrivateEnvironment of calleeContext to F.[[PrivateEnvironment]].
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callee_context.private_environment = m_private_environment;
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