================ @@ -0,0 +1,65 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +// https://github.com/llvm/llvm-project/issues/30023 +// compare exchange does not work with types of which the size is not a power of 2 + +#include <atomic> +#include <cstring> +#include <cassert> + +template <int Size> +struct S { + char data[Size]; + + explicit S(char v = 0) noexcept { memset(&data[0], v, sizeof(data)); } + + // only used in the test to check the results. Not used in atomic operations. + friend bool operator==(const S& lhs, const S& rhs) noexcept { + return memcmp(&lhs.data[0], &rhs.data[0], sizeof(lhs.data)) == 0; + } + friend bool operator!=(const S& lhs, const S& rhs) noexcept { return !(lhs == rhs); } +}; + +template <int Size> +struct Expected { + S<Size> s; + bool b = true; // used to validate that s's operation won't overwrite the memory next to it +}; + +template <int Size> +void test() { + using T = S<Size>; + std::atomic<T> a(T(0)); + Expected<Size> expected{T(17)}; + + assert(a.load() != expected.s); + assert(expected.b); + + auto r1 = a.compare_exchange_strong(expected.s, T(18), std::memory_order_relaxed); + + assert(!r1); + assert(expected.s == T(0)); // expected.s is modified by compare_exchange_strong + assert(expected.b); + assert(a.load() == T(0)); + + auto r2 = a.compare_exchange_strong(expected.s, T(18), std::memory_order_relaxed); + assert(r2); + assert(a.load() == T(18)); + assert(expected.s == T(0)); + assert(expected.b); +} + +int main() { + test<1>(); + test<2>(); + test<3>(); + test<4>(); + test<5>(); + test<6>(); +} ---------------- ldionne wrote:
```suggestion test<6>(); return 0; } ``` https://github.com/llvm/llvm-project/pull/78707 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
