forked from OSchip/llvm-project
44 lines
1.7 KiB
C++
44 lines
1.7 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: libcpp-has-no-threads
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// This test verifies behavior specified by [atomics.types.operations.req]/21:
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//
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// When only one memory_order argument is supplied, the value of success is
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// order, and the value of failure is order except that a value of
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// memory_order_acq_rel shall be replaced by the value memory_order_acquire
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// and a value of memory_order_release shall be replaced by the value
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// memory_order_relaxed.
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//
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// Clang's atomic intrinsics do this for us, but GCC's do not. We don't actually
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// have visibility to see what these memory orders are lowered to, but we can at
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// least check that they are lowered at all (otherwise there is a compile
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// failure with GCC).
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#include <atomic>
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int main() {
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std::atomic<int> i;
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volatile std::atomic<int> v;
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int exp = 0;
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i.compare_exchange_weak(exp, 0, std::memory_order_acq_rel);
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i.compare_exchange_weak(exp, 0, std::memory_order_release);
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i.compare_exchange_strong(exp, 0, std::memory_order_acq_rel);
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i.compare_exchange_strong(exp, 0, std::memory_order_release);
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v.compare_exchange_weak(exp, 0, std::memory_order_acq_rel);
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v.compare_exchange_weak(exp, 0, std::memory_order_release);
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v.compare_exchange_strong(exp, 0, std::memory_order_acq_rel);
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v.compare_exchange_strong(exp, 0, std::memory_order_release);
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return 0;
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}
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