clang/test/CodeGenCoroutines/coro-symmetric-transfer-04.cpp

   1 // This tests that the symmetric transfer at the final suspend point could happen successfully.
   2 // Based on https://github.com/llvm/llvm-project/pull/85271#issuecomment-2007554532
   3 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -O2 -emit-llvm %s -o - | FileCheck %s
   4
   5 #include "Inputs/coroutine.h"
   6
   7 struct Task {
   8   struct promise_type {
   9     struct FinalAwaiter {
  10       bool await_ready() const noexcept { return false; }
  11       template <typename PromiseType>
  12       std::coroutine_handle<> await_suspend(std::coroutine_handle<PromiseType> h) noexcept {
  13         return h.promise().continuation;
  14       }
  15       void await_resume() noexcept {}
  16     };
  17     Task get_return_object() noexcept {
  18       return std::coroutine_handle<promise_type>::from_promise(*this);
  19     }
  20     std::suspend_always initial_suspend() noexcept { return {}; }
  21     FinalAwaiter final_suspend() noexcept { return {}; }
  22     void unhandled_exception() noexcept {}
  23     void return_value(int x) noexcept {
  24       _value = x;
  25     }
  26     std::coroutine_handle<> continuation;
  27     int _value;
  28   };
  29
  30   Task(std::coroutine_handle<promise_type> handle) : handle(handle), stuff(123) {}
  31
  32   struct Awaiter {
  33     std::coroutine_handle<promise_type> handle;
  34     Awaiter(std::coroutine_handle<promise_type> handle) : handle(handle) {}
  35     bool await_ready() const noexcept { return false; }
  36     std::coroutine_handle<void> await_suspend(std::coroutine_handle<void> continuation) noexcept {
  37       handle.promise().continuation = continuation;
  38       return handle;
  39     }
  40     int await_resume() noexcept {
  41       int ret = handle.promise()._value;
  42       handle.destroy();
  43       return ret;
  44     }
  45   };
  46
  47   auto operator co_await() {
  48     auto handle_ = handle;
  49     handle = nullptr;
  50     return Awaiter(handle_);
  51   }
  52
  53 private:
  54   std::coroutine_handle<promise_type> handle;
  55   int stuff;
  56 };
  57
  58 Task task0() {
  59   co_return 43;
  60 }
  61
  62 // CHECK-LABEL: define{{.*}} void @_Z5task0v.resume
  63 // This checks we are still in the scope of the current function.
  64 // CHECK-NOT: {{^}}}
  65 // CHECK: musttail call fastcc void
  66 // CHECK-NEXT: ret void