On Wed, 10 Jan 2024 at 19:47, Ken Matsui <kmat...@gcc.gnu.org> wrote:
>
> This patch optimizes the compilation performance of std::is_scalar
> by dispatching to the new __is_scalar built-in trait.
OK for trunk (if the new built-in is approved).
>
> libstdc++-v3/ChangeLog:
>
> * include/std/type_traits (is_scalar): Use __is_scalar built-in
> trait.
> (is_scalar_v): Likewise.
>
> Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
> ---
> libstdc++-v3/include/std/type_traits | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> index b917c743aea..9ace6a9f08f 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -775,11 +775,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct is_member_pointer;
>
> /// is_scalar
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scalar)
> + template<typename _Tp>
> + struct is_scalar
> + : public __bool_constant<__is_scalar(_Tp)>
> + { };
> +#else
> template<typename _Tp>
> struct is_scalar
> : public __or_<is_arithmetic<_Tp>, is_enum<_Tp>, is_pointer<_Tp>,
> is_member_pointer<_Tp>, is_null_pointer<_Tp>>::type
> { };
> +#endif
>
> /// is_compound
> template<typename _Tp>
> @@ -3369,8 +3376,14 @@ template <typename _Tp>
> inline constexpr bool is_object_v = is_object<_Tp>::value;
> #endif
>
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scalar)
> +template <typename _Tp>
> + inline constexpr bool is_scalar_v = __is_scalar(_Tp);
> +#else
> template <typename _Tp>
> inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
> +#endif
> +
> template <typename _Tp>
> inline constexpr bool is_compound_v = !is_fundamental_v<_Tp>;
>
> --
> 2.43.0
>
