https://gcc.gnu.org/g:bb99672e0c49d8b8822664eaabc10cd51a42aab4
commit r15-1246-gbb99672e0c49d8b8822664eaabc10cd51a42aab4 Author: Ken Matsui <kmat...@gcc.gnu.org> Date: Wed Mar 22 16:28:06 2023 -0700 libstdc++: Optimize std::is_volatile compilation performance This patch optimizes the compilation performance of std::is_volatile by dispatching to the new __is_volatile built-in trait. libstdc++-v3/ChangeLog: * include/std/type_traits (is_volatile): Use __is_volatile built-in trait. (is_volatile_v): Likewise. Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org> Reviewed-by: Patrick Palka <ppa...@redhat.com> Reviewed-by: Jonathan Wakely <jwak...@redhat.com> Diff: --- libstdc++-v3/include/std/type_traits | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index 8df0cf3ac3b8..748fa186881d 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -851,6 +851,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #endif /// is_volatile +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_volatile) + template<typename _Tp> + struct is_volatile + : public __bool_constant<__is_volatile(_Tp)> + { }; +#else template<typename> struct is_volatile : public false_type { }; @@ -858,6 +864,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _Tp> struct is_volatile<_Tp volatile> : public true_type { }; +#endif /// is_trivial template<typename _Tp> @@ -3360,10 +3367,15 @@ template <typename _Tp> inline constexpr bool is_function_v<_Tp&&> = false; #endif +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_volatile) +template <typename _Tp> + inline constexpr bool is_volatile_v = __is_volatile(_Tp); +#else template <typename _Tp> inline constexpr bool is_volatile_v = false; template <typename _Tp> inline constexpr bool is_volatile_v<volatile _Tp> = true; +#endif template <typename _Tp> inline constexpr bool is_trivial_v = __is_trivial(_Tp);