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 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
