1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// This test verifies behavior specified by [atomics.types.operations.req]/21:
10//
11// When only one memory_order argument is supplied, the value of success is
12// order, and the value of failure is order except that a value of
13// memory_order_acq_rel shall be replaced by the value memory_order_acquire
14// and a value of memory_order_release shall be replaced by the value
15// memory_order_relaxed.
16//
17// Clang's atomic intrinsics do this for us, but GCC's do not. We don't actually
18// have visibility to see what these memory orders are lowered to, but we can at
19// least check that they are lowered at all (otherwise there is a compile
20// failure with GCC).
21
22#include <atomic>
23
24#include "test_macros.h"
25
26int main(int, char**) {
27 std::atomic<int> i;
28 volatile std::atomic<int> v;
29 int exp = 0;
30
31 (void) i.compare_exchange_weak(i1&: exp, i2: 0, m: std::memory_order_acq_rel);
32 (void) i.compare_exchange_weak(i1&: exp, i2: 0, m: std::memory_order_release);
33 i.compare_exchange_strong(i1&: exp, i2: 0, m: std::memory_order_acq_rel);
34 i.compare_exchange_strong(i1&: exp, i2: 0, m: std::memory_order_release);
35
36 (void) v.compare_exchange_weak(i1&: exp, i2: 0, m: std::memory_order_acq_rel);
37 (void) v.compare_exchange_weak(i1&: exp, i2: 0, m: std::memory_order_release);
38 v.compare_exchange_strong(i1&: exp, i2: 0, m: std::memory_order_acq_rel);
39 v.compare_exchange_strong(i1&: exp, i2: 0, m: std::memory_order_release);
40
41 return 0;
42}
43

source code of libcxx/test/std/atomics/atomics.general/replace_failure_order.pass.cpp