Re: [PATCH v2 2/3] libstdc++: Optimize is_arithmetic performance by __is_arithmetic built-in

[Jonathan Wakely <jwakely@redhat.com>]

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On Sat, 15 Jul 2023 at 05:57, Ken Matsui via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:

> This patch optimizes the performance of the is_arithmetic trait by
> dispatching to the new __is_arithmetic built-in trait.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits (is_arithmetic): Use __is_arithmetic
>         built-in trait.
>         (is_arithmetic_v): Likewise.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
>

OK for trunk (if the front-end changes are approved).




> ---
>  libstdc++-v3/include/std/type_traits | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> index 0e7a9c9c7f3..7ebbe04c77b 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -655,10 +655,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      { };
>
>    /// is_arithmetic
> +#if __has_builtin(__is_arithmetic)
> +  template<typename _Tp>
> +    struct is_arithmetic
> +    : public __bool_constant<__is_arithmetic(_Tp)>
> +    { };
> +#else
>    template<typename _Tp>
>      struct is_arithmetic
>      : public __or_<is_integral<_Tp>, is_floating_point<_Tp>>::type
>      { };
> +#endif
>
>    /// is_fundamental
>    template<typename _Tp>
> @@ -3198,8 +3205,15 @@ template <typename _Tp>
>    inline constexpr bool is_reference_v<_Tp&> = true;
>  template <typename _Tp>
>    inline constexpr bool is_reference_v<_Tp&&> = true;
> +
> +#if __has_builtin(__is_arithmetic)
> +template <typename _Tp>
> +  inline constexpr bool is_arithmetic_v = __is_arithmetic(_Tp);
> +#else
>  template <typename _Tp>
>    inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
> +#endif
> +
>  template <typename _Tp>
>    inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
>  template <typename _Tp>
> --
> 2.41.0
>
>