89 lines
2 KiB
C++
89 lines
2 KiB
C++
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// Test for PR59221. Tests the compiler wouldn't misoptimize the final result.
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//
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// REQUIRES: x86-registered-target
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//
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 %s -O1 -S -emit-llvm -o - | FileCheck %s
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#include "Inputs/coroutine.h"
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template <typename T> struct task {
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struct promise_type {
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T value{123};
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std::coroutine_handle<> caller{std::noop_coroutine()};
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struct final_awaiter: std::suspend_always {
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auto await_suspend(std::coroutine_handle<promise_type> me) const noexcept {
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return me.promise().caller;
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}
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};
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constexpr auto initial_suspend() const noexcept {
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return std::suspend_always();
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}
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constexpr auto final_suspend() const noexcept {
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return final_awaiter{};
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}
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auto unhandled_exception() noexcept {
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// ignore
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}
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constexpr void return_value(T v) noexcept {
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value = v;
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}
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constexpr auto & get_return_object() noexcept {
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return *this;
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}
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};
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using coroutine_handle = std::coroutine_handle<promise_type>;
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promise_type & promise{nullptr};
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task(promise_type & p) noexcept: promise{p} { }
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~task() noexcept {
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coroutine_handle::from_promise(promise).destroy();
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}
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auto await_ready() noexcept {
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return false;
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}
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auto await_suspend(std::coroutine_handle<> caller) noexcept {
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promise.caller = caller;
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return coroutine_handle::from_promise(promise);
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}
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constexpr auto await_resume() const noexcept {
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return promise.value;
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}
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// non-coroutine access to result
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auto get() noexcept {
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const auto handle = coroutine_handle::from_promise(promise);
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if (!handle.done()) {
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handle.resume();
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}
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return promise.value;
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}
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};
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static inline auto a() noexcept -> task<int> {
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co_return 42;
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}
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static inline auto test() noexcept -> task<int> {
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co_return co_await a();
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}
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int foo() {
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return test().get();
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}
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// Checks that the store for the result value 42 is not misoptimized out.
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// CHECK: define{{.*}}_Z3foov(
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// CHECK: store i32 42, ptr %{{.*}}
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// CHECK: }
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