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LibJS: Simplify ECMAScriptFunctionObject.[[Realm]] slot handling

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Our engine already keeps track of the home realm for all objects.
This is stored in Shape::realm(). We can use that instead of having
a dedicated member in ESFO for the same pointer.

Since there's always a home realm these days, we can also remove some
outdated fallback code from the days when having a realm was not
guaranteed due to LibWeb shenanigans.
This commit is contained in:
Andreas Kling 2025-04-11 18:55:01 +02:00 • committed by Andreas Kling
parent e4941a36b0
commit 6db20a9453
Notes: github-actions[bot] 2025-04-12 09:08:41 +00:00
2 changed files with 4 additions and 29 deletions
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30
Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
View file

@ -426,10 +426,9 @@ ECMAScriptFunctionObject::ECMAScriptFunctionObject(
, m_shared_data(move(shared_data))
, m_environment(parent_environment)
, m_private_environment(private_environment)
, m_realm(&prototype.shape().realm())
{
if (!is_arrow_function() && kind() == FunctionKind::Normal)
unsafe_set_shape(m_realm->intrinsics().normal_function_shape());
unsafe_set_shape(realm()->intrinsics().normal_function_shape());
// 15. Set F.[[ScriptOrModule]] to GetActiveScriptOrModule().
m_script_or_module = vm().get_active_script_or_module();
@ -643,7 +642,6 @@ void ECMAScriptFunctionObject::visit_edges(Visitor& visitor)
Base::visit_edges(visitor);
visitor.visit(m_environment);
visitor.visit(m_private_environment);
visitor.visit(m_realm);
visitor.visit(m_home_object);
visitor.visit(m_name_string);
@ -694,27 +692,13 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::prepare_for_ordinary_call(Exec
// 1. Let callerContext be the running execution context.
// 2. Let calleeContext be a new ECMAScript code execution context.
// NOTE: In the specification, PrepareForOrdinaryCall "returns" a new callee execution context.
// To avoid heap allocations, we put our ExecutionContext objects on the C++ stack instead.
// Whoever calls us should put an ExecutionContext on their stack and pass that as the `callee_context`.
// 3. Set the Function of calleeContext to F.
callee_context.function = this;
callee_context.function_name = m_name_string;
// 4. Let calleeRealm be F.[[Realm]].
auto callee_realm = m_realm;
// NOTE: This non-standard fallback is needed until we can guarantee that literally
// every function has a realm - especially in LibWeb that's sometimes not the case
// when a function is created while no JS is running, as we currently need to rely on
// that (:acid2:, I know - see set_event_handler_attribute() for an example).
// If there's no 'current realm' either, we can't continue and crash.
if (!callee_realm)
callee_realm = vm.current_realm();
VERIFY(callee_realm);
// 5. Set the Realm of calleeContext to calleeRealm.
callee_context.realm = callee_realm;
callee_context.realm = realm();
// 6. Set the ScriptOrModule of calleeContext to F.[[ScriptOrModule]].
callee_context.script_or_module = m_script_or_module;
@ -758,15 +742,7 @@ void ECMAScriptFunctionObject::ordinary_call_bind_this(ExecutionContext& callee_
return;
// 3. Let calleeRealm be F.[[Realm]].
auto callee_realm = m_realm;
// NOTE: This non-standard fallback is needed until we can guarantee that literally
// every function has a realm - especially in LibWeb that's sometimes not the case
// when a function is created while no JS is running, as we currently need to rely on
// that (:acid2:, I know - see set_event_handler_attribute() for an example).
// If there's no 'current realm' either, we can't continue and crash.
if (!callee_realm)
callee_realm = vm.current_realm();
VERIFY(callee_realm);
auto callee_realm = realm();
// 4. Let localEnv be the LexicalEnvironment of calleeContext.
auto local_env = callee_context.lexical_environment;

3
Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
View file

@ -135,7 +135,7 @@ public:
auto& bytecode_executable() const { return m_bytecode_executable; }
Environment* environment() { return m_environment; }
virtual Realm* realm() const override { return m_realm; }
virtual Realm* realm() const override { return &shape().realm(); }
[[nodiscard]] ConstructorKind constructor_kind() const { return shared_data().m_constructor_kind; }
void set_constructor_kind(ConstructorKind constructor_kind) { const_cast<SharedFunctionInstanceData&>(shared_data()).m_constructor_kind = constructor_kind; }
@ -210,7 +210,6 @@ private:
// Internal Slots of ECMAScript Function Objects, https://tc39.es/ecma262/#table-internal-slots-of-ecmascript-function-objects
GC::Ptr<Environment> m_environment; // [[Environment]]
GC::Ptr<PrivateEnvironment> m_private_environment; // [[PrivateEnvironment]]
GC::Ptr<Realm> m_realm; // [[Realm]]
ScriptOrModule m_script_or_module; // [[ScriptOrModule]]
GC::Ptr<Object> m_home_object; // [[HomeObject]]
struct ClassData {