clang/test/CIR/CodeGen/coro-task.cpp

// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR

namespace std {

template<typename T> struct remove_reference       { typedef T type; };
template<typename T> struct remove_reference<T &>  { typedef T type; };
template<typename T> struct remove_reference<T &&> { typedef T type; };

template<typename T>
typename remove_reference<T>::type &&move(T &&t) noexcept;

template <class Ret, typename... T>
struct coroutine_traits { using promise_type = typename Ret::promise_type; };

template <class Promise = void>
struct coroutine_handle {
  static coroutine_handle from_address(void *) noexcept;
};
template <>
struct coroutine_handle<void> {
  template <class PromiseType>
  coroutine_handle(coroutine_handle<PromiseType>) noexcept;
  static coroutine_handle from_address(void *);
};

struct suspend_always {
  bool await_ready() noexcept { return false; }
  void await_suspend(coroutine_handle<>) noexcept {}
  void await_resume() noexcept {}
};

struct suspend_never {
  bool await_ready() noexcept { return true; }
  void await_suspend(coroutine_handle<>) noexcept {}
  void await_resume() noexcept {}
};

} // namespace std

namespace folly {
namespace coro {

using std::suspend_always;
using std::suspend_never;
using std::coroutine_handle;

using SemiFuture = int;

template<class T>
struct Task {
    struct promise_type {
        Task<T> get_return_object() noexcept;
        suspend_always initial_suspend() noexcept;
        suspend_always final_suspend() noexcept;
        void return_value(T);
        void unhandled_exception();
        auto yield_value(Task<T>) noexcept { return final_suspend(); }
    };
    bool await_ready() noexcept { return false; }
    void await_suspend(coroutine_handle<>) noexcept {}
    T await_resume();
};

template<>
struct Task<void> {
    struct promise_type {
        Task<void> get_return_object() noexcept;
        suspend_always initial_suspend() noexcept;
        suspend_always final_suspend() noexcept;
        void return_void() noexcept;
        void unhandled_exception() noexcept;
        auto yield_value(Task<void>) noexcept { return final_suspend(); }
    };
    bool await_ready() noexcept { return false; }
    void await_suspend(coroutine_handle<>) noexcept {}
    void await_resume() noexcept {}
    SemiFuture semi();
};

// FIXME: add CIRGen support here.
// struct blocking_wait_fn {
//   template <typename T>
//   T operator()(Task<T>&& awaitable) const {
//     return T();
//   }
// };

// inline constexpr blocking_wait_fn blocking_wait{};
// static constexpr blocking_wait_fn const& blockingWait = blocking_wait;

struct co_invoke_fn {
  template <typename F, typename... A>
  Task<void> operator()(F&& f, A&&... a) const {
    return Task<void>();
  }
};

co_invoke_fn co_invoke;

}} // namespace folly::coro

// CIR-DAG: ![[VoidTask:.*]] = !cir.record<struct "folly::coro::Task<void>" padded {!u8i}>

// CIR: module {{.*}} {
// CIR-NEXT: cir.global external @_ZN5folly4coro9co_invokeE = #cir.zero : !rec_folly3A3Acoro3A3Aco_invoke_fn

// CIR: cir.func builtin private @__builtin_coro_id(!u32i, !cir.ptr<!void>, !cir.ptr<!void>, !cir.ptr<!void>) -> !u32i

using VoidTask = folly::coro::Task<void>;

VoidTask silly_task() {
  co_await std::suspend_always();
}

// CIR: cir.func coroutine dso_local @_Z10silly_taskv() -> ![[VoidTask]]
// CHECK: %[[#VoidTaskAddr:]] = cir.alloca ![[VoidTask]], {{.*}}, ["__retval"]

// Get coroutine id with __builtin_coro_id.

// CIR: %[[NullPtr:.*]] = cir.const #cir.ptr<null> : !cir.ptr<!void>
// CIR: %[[Align:.*]] = cir.const #cir.int<16> : !u32i
// CIR: %[[CoroId:.*]] = cir.call @__builtin_coro_id(%[[Align]], %[[NullPtr]], %[[NullPtr]], %[[NullPtr]])