128 lines · cpp
1// This file tests the coro_await_elidable attribute semantics.2// RUN: %clang_cc1 -triple=x86_64-unknown-linux-gnu -std=c++20 -disable-llvm-passes -emit-llvm %s -o - | FileCheck %s3 4#include "Inputs/coroutine.h"5#include "Inputs/utility.h"6 7template <typename T>8struct [[clang::coro_await_elidable]] Task {9 struct promise_type {10 struct FinalAwaiter {11 bool await_ready() const noexcept { return false; }12 13 template <typename P>14 std::coroutine_handle<> await_suspend(std::coroutine_handle<P> coro) noexcept {15 if (!coro)16 return std::noop_coroutine();17 return coro.promise().continuation;18 }19 void await_resume() noexcept {}20 };21 22 Task get_return_object() noexcept {23 return std::coroutine_handle<promise_type>::from_promise(*this);24 }25 26 std::suspend_always initial_suspend() noexcept { return {}; }27 FinalAwaiter final_suspend() noexcept { return {}; }28 void unhandled_exception() noexcept {}29 void return_value(T x) noexcept {30 value = x;31 }32 33 std::coroutine_handle<> continuation;34 T value;35 };36 37 Task(std::coroutine_handle<promise_type> handle) : handle(handle) {}38 ~Task() {39 if (handle)40 handle.destroy();41 }42 43 struct Awaiter {44 Awaiter(Task *t) : task(t) {}45 bool await_ready() const noexcept { return false; }46 void await_suspend(std::coroutine_handle<void> continuation) noexcept {}47 T await_resume() noexcept {48 return task->handle.promise().value;49 }50 51 Task *task;52 };53 54 auto operator co_await() {55 return Awaiter{this};56 }57 58private:59 std::coroutine_handle<promise_type> handle;60};61 62// CHECK-LABEL: define{{.*}} @_Z6calleev{{.*}} {63Task<int> callee() {64 co_return 1;65}66 67// CHECK-LABEL: define{{.*}} @_Z8elidablev{{.*}} {68Task<int> elidable() {69 // CHECK: %[[TASK_OBJ:.+]] = alloca %struct.Task70 // CHECK: call void @_Z6calleev(ptr dead_on_unwind writable sret(%struct.Task) align 8 %[[TASK_OBJ]]) #[[ELIDE_SAFE:.+]]71 co_return co_await callee();72}73 74// CHECK-LABEL: define{{.*}} @_Z11nonelidablev{{.*}} {75Task<int> nonelidable() {76 // CHECK: %[[TASK_OBJ:.+]] = alloca %struct.Task77 auto t = callee();78 // Because we aren't co_awaiting a prvalue, we cannot elide here.79 // CHECK: call void @_Z6calleev(ptr dead_on_unwind writable sret(%struct.Task) align 8 %[[TASK_OBJ]])80 // CHECK-NOT: #[[ELIDE_SAFE]]81 co_await t;82 co_await std::move(t);83 84 co_return 1;85}86 87// CHECK-LABEL: define{{.*}} @_Z8addTasksO4TaskIiES1_{{.*}} {88Task<int> addTasks([[clang::coro_await_elidable_argument]] Task<int> &&t1, Task<int> &&t2) {89 int i1 = co_await t1;90 int i2 = co_await t2;91 co_return i1 + i2;92}93 94// CHECK-LABEL: define{{.*}} @_Z10returnSamei{{.*}} {95Task<int> returnSame(int i) {96 co_return i;97}98 99// CHECK-LABEL: define{{.*}} @_Z21elidableWithMustAwaitv{{.*}} {100Task<int> elidableWithMustAwait() {101 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 2) #[[ELIDE_SAFE]]102 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 3){{$}}103 co_return co_await addTasks(returnSame(2), returnSame(3));104}105 106template <typename... Args>107Task<int> sumAll([[clang::coro_await_elidable_argument]] Args && ... tasks);108 109// CHECK-LABEL: define{{.*}} @_Z16elidableWithPackv{{.*}} {110Task<int> elidableWithPack() {111 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 1){{$}}112 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 2) #[[ELIDE_SAFE]]113 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 3) #[[ELIDE_SAFE]]114 auto t = returnSame(1);115 co_return co_await sumAll(t, returnSame(2), returnSame(3));116}117 118 119// CHECK-LABEL: define{{.*}} @_Z25elidableWithPackRecursivev{{.*}} {120Task<int> elidableWithPackRecursive() {121 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 1) #[[ELIDE_SAFE]]122 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 2){{$}}123 // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 3) #[[ELIDE_SAFE]]124 co_return co_await sumAll(addTasks(returnSame(1), returnSame(2)), returnSame(3));125}126 127// CHECK: attributes #[[ELIDE_SAFE]] = { coro_elide_safe }128