1//
2// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3// See https://llvm.org/LICENSE.txt for license information.
4// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5//
6//===----------------------------------------------------------------------===//
7
8// UNSUPPORTED: c++03, c++11, c++14, c++17
9// XFAIL: !has-64-bit-atomics
10
11// integral-type fetch_sub(integral-type, memory_order = memory_order::seq_cst) const noexcept;
12// floating-point-type fetch_sub(floating-point-type, memory_order = memory_order::seq_cst) const noexcept;
13// T* fetch_sub(difference_type, memory_order = memory_order::seq_cst) const noexcept;
14
15#include <atomic>
16#include <cassert>
17#include <concepts>
18#include <type_traits>
19#include <utility>
20
21#include "atomic_helpers.h"
22#include "test_helper.h"
23#include "test_macros.h"
24
25template <typename T>
26concept has_fetch_sub = requires {
27 std::declval<T const>().fetch_sub(std::declval<T>());
28 std::declval<T const>().fetch_sub(std::declval<T>(), std::declval<std::memory_order>());
29};
30
31template <typename T>
32struct TestDoesNotHaveFetchSub {
33 void operator()() const { static_assert(!has_fetch_sub<std::atomic_ref<T>>); }
34};
35
36template <typename T>
37struct TestFetchSub {
38 void operator()() const {
39 if constexpr (std::is_arithmetic_v<T>) {
40 T x(T(7));
41 std::atomic_ref<T> const a(x);
42
43 {
44 std::same_as<T> decltype(auto) y = a.fetch_sub(T(4));
45 assert(y == T(7));
46 assert(x == T(3));
47 ASSERT_NOEXCEPT(a.fetch_sub(T(0)));
48 }
49
50 {
51 std::same_as<T> decltype(auto) y = a.fetch_sub(T(2), std::memory_order_relaxed);
52 assert(y == T(3));
53 assert(x == T(1));
54 ASSERT_NOEXCEPT(a.fetch_sub(T(0), std::memory_order_relaxed));
55 }
56 } else if constexpr (std::is_pointer_v<T>) {
57 using U = std::remove_pointer_t<T>;
58 U t[9] = {};
59 T p{&t[7]};
60 std::atomic_ref<T> const a(p);
61
62 {
63 std::same_as<T> decltype(auto) y = a.fetch_sub(4);
64 assert(y == &t[7]);
65 assert(a == &t[3]);
66 ASSERT_NOEXCEPT(a.fetch_sub(0));
67 }
68
69 {
70 std::same_as<T> decltype(auto) y = a.fetch_sub(2, std::memory_order_relaxed);
71 assert(y == &t[3]);
72 assert(a == &t[1]);
73 ASSERT_NOEXCEPT(a.fetch_sub(0, std::memory_order_relaxed));
74 }
75 } else {
76 static_assert(std::is_void_v<T>);
77 }
78
79 // memory_order::release
80 {
81 auto fetch_sub = [](std::atomic_ref<T> const& x, T old_val, T new_val) {
82 x.fetch_sub(old_val - new_val, std::memory_order::release);
83 };
84 auto load = [](std::atomic_ref<T> const& x) { return x.load(std::memory_order::acquire); };
85 test_acquire_release<T>(fetch_sub, load);
86 }
87
88 // memory_order::seq_cst
89 {
90 auto fetch_sub_no_arg = [](std::atomic_ref<T> const& x, T old_val, T new_val) { x.fetch_sub(old_val - new_val); };
91 auto fetch_sub_with_order = [](std::atomic_ref<T> const& x, T old_val, T new_val) {
92 x.fetch_sub(old_val - new_val, std::memory_order::seq_cst);
93 };
94 auto load = [](std::atomic_ref<T> const& x) { return x.load(); };
95 test_seq_cst<T>(fetch_sub_no_arg, load);
96 test_seq_cst<T>(fetch_sub_with_order, load);
97 }
98 }
99};
100
101int main(int, char**) {
102 TestEachIntegralType<TestFetchSub>()();
103
104 TestFetchSub<float>()();
105 TestFetchSub<double>()();
106
107 TestEachPointerType<TestFetchSub>()();
108
109 TestDoesNotHaveFetchSub<bool>()();
110 TestDoesNotHaveFetchSub<UserAtomicType>()();
111 TestDoesNotHaveFetchSub<LargeUserAtomicType>()();
112
113 return 0;
114}
115

source code of libcxx/test/std/atomics/atomics.ref/fetch_sub.pass.cpp