clang/test/CodeGenCoroutines/coro-symmetric-transfer-03.cpp

   1 // This tests that the symmetric transfer at the final suspend point could happen successfully.
   2 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -O2 -emit-llvm %s -o - | FileCheck %s
   3
   4 #include "Inputs/coroutine.h"
   5
   6 struct Task {
   7   struct promise_type {
   8     struct FinalAwaiter {
   9       bool await_ready() const noexcept { return false; }
  10       template <typename PromiseType>
  11       std::coroutine_handle<> await_suspend(std::coroutine_handle<PromiseType> h) noexcept {
  12         return h.promise().continuation;
  13       }
  14       void await_resume() noexcept {}
  15     };
  16     Task get_return_object() noexcept {
  17       return std::coroutine_handle<promise_type>::from_promise(*this);
  18     }
  19     std::suspend_always initial_suspend() noexcept { return {}; }
  20     FinalAwaiter final_suspend() noexcept { return {}; }
  21     void unhandled_exception() noexcept {}
  22     void return_value(int x) noexcept {
  23       _value = x;
  24     }
  25     std::coroutine_handle<> continuation;
  26     int _value;
  27   };
  28
  29   Task(std::coroutine_handle<promise_type> handle) : handle(handle) {}
  30   ~Task() {
  31     if (handle)
  32       handle.destroy();
  33   }
  34
  35   struct Awaiter {
  36     std::coroutine_handle<promise_type> handle;
  37     Awaiter(std::coroutine_handle<promise_type> handle) : handle(handle) {}
  38     bool await_ready() const noexcept { return false; }
  39     std::coroutine_handle<void> await_suspend(std::coroutine_handle<void> continuation) noexcept {
  40       handle.promise().continuation = continuation;
  41       return handle;
  42     }
  43     int await_resume() noexcept {
  44       int ret = handle.promise()._value;
  45       handle.destroy();
  46       return ret;
  47     }
  48   };
  49
  50   auto operator co_await() {
  51     auto handle_ = handle;
  52     handle = nullptr;
  53     return Awaiter(handle_);
  54   }
  55
  56 private:
  57   std::coroutine_handle<promise_type> handle;
  58 };
  59
  60 Task task0() {
  61   co_return 43;
  62 }
  63
  64 // CHECK-LABEL: define{{.*}} void @_Z5task0v.resume
  65 // This checks we are still in the scope of the current function.
  66 // CHECK-NOT: {{^}}}
  67 // CHECK: musttail call fastcc void
  68 // CHECK-NEXT: ret void