diff options
Diffstat (limited to 'libcxx/include/new')
| -rw-r--r-- | libcxx/include/new | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/libcxx/include/new b/libcxx/include/new index 06cf4a3e160..6541e021865 100644 --- a/libcxx/include/new +++ b/libcxx/include/new @@ -46,6 +46,8 @@ typedef void (*new_handler)(); new_handler set_new_handler(new_handler new_p) noexcept; new_handler get_new_handler() noexcept; +// 21.6.4, pointer optimization barrier +template <class T> constexpr T* launder(T* p) noexcept; // C++17 } // std void* operator new(std::size_t size); // replaceable @@ -250,6 +252,29 @@ void __throw_bad_array_length() } #endif +template <class _Tp> +_LIBCPP_NODISCARD_AFTER_CXX17 inline +_LIBCPP_CONSTEXPR _Tp* __launder(_Tp* __p) _NOEXCEPT +{ + static_assert (!(is_function<_Tp>::value), "can't launder functions" ); + static_assert (!(is_same<void, typename remove_cv<_Tp>::type>::value), "can't launder cv-void" ); +#ifdef _LIBCPP_COMPILER_HAS_BUILTIN_LAUNDER + return __builtin_launder(__p); +#else + return __p; +#endif +} + + +#if _LIBCPP_STD_VER > 14 +template <class _Tp> +_LIBCPP_NODISCARD_AFTER_CXX17 inline _LIBCPP_INLINE_VISIBILITY +constexpr _Tp* launder(_Tp* __p) noexcept +{ + return __launder(__p); +} +#endif + _LIBCPP_END_NAMESPACE_STD #endif // _LIBCPP_NEW |
