1 //===----------------------------------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 // UNSUPPORTED: libcpp-has-no-threads
11
12 // This test verifies behavior specified by [atomics.types.operations.req]/21:
13 //
14 // When only one memory_order argument is supplied, the value of success is
15 // order, and the value of failure is order except that a value of
16 // memory_order_acq_rel shall be replaced by the value memory_order_acquire
17 // and a value of memory_order_release shall be replaced by the value
18 // memory_order_relaxed.
19 //
20 // Clang's atomic intrinsics do this for us, but GCC's do not. We don't actually
21 // have visibility to see what these memory orders are lowered to, but we can at
22 // least check that they are lowered at all (otherwise there is a compile
23 // failure with GCC).
24
25 #include <atomic>
26
main()27 int main() {
28 std::atomic<int> i;
29 volatile std::atomic<int> v;
30 int exp = 0;
31
32 i.compare_exchange_weak(exp, 0, std::memory_order_acq_rel);
33 i.compare_exchange_weak(exp, 0, std::memory_order_release);
34 i.compare_exchange_strong(exp, 0, std::memory_order_acq_rel);
35 i.compare_exchange_strong(exp, 0, std::memory_order_release);
36
37 v.compare_exchange_weak(exp, 0, std::memory_order_acq_rel);
38 v.compare_exchange_weak(exp, 0, std::memory_order_release);
39 v.compare_exchange_strong(exp, 0, std::memory_order_acq_rel);
40 v.compare_exchange_strong(exp, 0, std::memory_order_release);
41
42 return 0;
43 }
44