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LibJS: Localize popping of execution context in AsyncFunctionDriver

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Instead of adding a flag for the two callers that need a pop of the
execution context stack when invoking continue_async_execution inline
the pop of the execution context.

This makes the management of these stacks and surrounding VERIFY calls
much more obvious.
This commit is contained in:
Shannon Booth 2025-01-22 18:59:37 +13:00 • committed by Andrew Kaster
commit b58ba2e1bd
Notes: github-actions[bot] 2025-01-30 20:58:24 +00:00
2 changed files with 6 additions and 15 deletions
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14
Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.cpp
View file

@ -24,7 +24,7 @@ GC::Ref<Promise> AsyncFunctionDriverWrapper::create(Realm& realm, GeneratorObjec
auto wrapper = realm.create<AsyncFunctionDriverWrapper>(realm, *generator_object, *top_level_promise); auto wrapper = realm.create<AsyncFunctionDriverWrapper>(realm, *generator_object, *top_level_promise);
// Prime the generator: // Prime the generator:
// This runs until the first `await value;` // This runs until the first `await value;`
wrapper->continue_async_execution(realm.vm(), js_undefined(), true, IsInitialExecution::Yes); wrapper->continue_async_execution(realm.vm(), js_undefined(), true);
return top_level_promise; return top_level_promise;
} }
@ -64,6 +64,7 @@ ThrowCompletionOr<void> AsyncFunctionDriverWrapper::await(JS::Value value)
// d. Resume the suspended evaluation of asyncContext using NormalCompletion(v) as the result of the operation that // d. Resume the suspended evaluation of asyncContext using NormalCompletion(v) as the result of the operation that
// suspended it. // suspended it.
continue_async_execution(vm, value, true); continue_async_execution(vm, value, true);
vm.pop_execution_context();
// e. Assert: When we reach this step, asyncContext has already been removed from the execution context stack and // e. Assert: When we reach this step, asyncContext has already been removed from the execution context stack and
// prevContext is the currently running execution context. // prevContext is the currently running execution context.
@ -91,6 +92,7 @@ ThrowCompletionOr<void> AsyncFunctionDriverWrapper::await(JS::Value value)
// d. Resume the suspended evaluation of asyncContext using ThrowCompletion(reason) as the result of the operation that // d. Resume the suspended evaluation of asyncContext using ThrowCompletion(reason) as the result of the operation that
// suspended it. // suspended it.
continue_async_execution(vm, reason, false); continue_async_execution(vm, reason, false);
vm.pop_execution_context();
// e. Assert: When we reach this step, asyncContext has already been removed from the execution context stack and // e. Assert: When we reach this step, asyncContext has already been removed from the execution context stack and
// prevContext is the currently running execution context. // prevContext is the currently running execution context.
@ -107,11 +109,9 @@ ThrowCompletionOr<void> AsyncFunctionDriverWrapper::await(JS::Value value)
m_current_promise = as<Promise>(promise_object); m_current_promise = as<Promise>(promise_object);
m_current_promise->perform_then(on_fulfilled, on_rejected, {}); m_current_promise->perform_then(on_fulfilled, on_rejected, {});
// NOTE: None of these are necessary. 8-12 are handled by step d of the above lambdas.
// 8. Remove asyncContext from the execution context stack and restore the execution context that is at the top of the // 8. Remove asyncContext from the execution context stack and restore the execution context that is at the top of the
// execution context stack as the running execution context. // execution context stack as the running execution context.
// NOTE: This is done later on for us in continue_async_execution.
// NOTE: None of these are necessary. 10-12 are handled by step d of the above lambdas.
// 9. Let callerContext be the running execution context. // 9. Let callerContext be the running execution context.
// 10. Resume callerContext passing empty. If asyncContext is ever resumed again, let completion be the Completion Record with which it is resumed. // 10. Resume callerContext passing empty. If asyncContext is ever resumed again, let completion be the Completion Record with which it is resumed.
// 11. Assert: If control reaches here, then asyncContext is the running execution context again. // 11. Assert: If control reaches here, then asyncContext is the running execution context again.
@ -119,7 +119,7 @@ ThrowCompletionOr<void> AsyncFunctionDriverWrapper::await(JS::Value value)
return {}; return {};
} }
void AsyncFunctionDriverWrapper::continue_async_execution(VM& vm, Value value, bool is_successful, IsInitialExecution is_initial_execution) void AsyncFunctionDriverWrapper::continue_async_execution(VM& vm, Value value, bool is_successful)
{ {
auto generator_result = is_successful auto generator_result = is_successful
? m_generator_object->resume(vm, value, {}) ? m_generator_object->resume(vm, value, {})
@ -168,10 +168,6 @@ void AsyncFunctionDriverWrapper::continue_async_execution(VM& vm, Value value, b
if (result.is_throw_completion()) { if (result.is_throw_completion()) {
m_top_level_promise->reject(result.throw_completion().value().value_or(js_undefined())); m_top_level_promise->reject(result.throw_completion().value().value_or(js_undefined()));
} }
// For the initial execution, the execution context will be popped for us later on by ECMAScriptFunctionObject.
if (is_initial_execution == IsInitialExecution::No)
vm.pop_execution_context();
} }
void AsyncFunctionDriverWrapper::visit_edges(Cell::Visitor& visitor) void AsyncFunctionDriverWrapper::visit_edges(Cell::Visitor& visitor)

7
Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.h
View file

@ -19,17 +19,12 @@ class AsyncFunctionDriverWrapper final : public Promise {
GC_DECLARE_ALLOCATOR(AsyncFunctionDriverWrapper); GC_DECLARE_ALLOCATOR(AsyncFunctionDriverWrapper);
public: public:
enum class IsInitialExecution {
No,
Yes,
};
[[nodiscard]] static GC::Ref<Promise> create(Realm&, GeneratorObject*); [[nodiscard]] static GC::Ref<Promise> create(Realm&, GeneratorObject*);
virtual ~AsyncFunctionDriverWrapper() override = default; virtual ~AsyncFunctionDriverWrapper() override = default;
void visit_edges(Cell::Visitor&) override; void visit_edges(Cell::Visitor&) override;
void continue_async_execution(VM&, Value, bool is_successful, IsInitialExecution is_initial_execution = IsInitialExecution::No); void continue_async_execution(VM&, Value, bool is_successful);
private: private:
AsyncFunctionDriverWrapper(Realm&, GC::Ref<GeneratorObject>, GC::Ref<Promise> top_level_promise); AsyncFunctionDriverWrapper(Realm&, GC::Ref<GeneratorObject>, GC::Ref<Promise> top_level_promise);