On Mon, 10 Jul 2023 at 06:51, Ken Matsui via Libstdc++ <libstd...@gcc.gnu.org> wrote: > > Hi, > > Here is the benchmark result for is_pointer: > > https://github.com/ken-matsui/gcc-benches/blob/main/is_pointer.md#sun-jul--9-103948-pm-pdt-2023 > > Time: -62.1344% > Peak Memory Usage: -52.4281% > Total Memory Usage: -53.5889%
Wow! Although maybe we could have improved our std::is_pointer_v anyway, like so: template <typename _Tp> inline constexpr bool is_pointer_v = false; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp*> = true; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp* const> = true; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp* volatile> = true; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp* const volatile> = true; I'm not sure why I didn't already do that. Could you please benchmark that? And if it is better than the current impl using is_pointer<_Tp>::value then we should do this in the library: #if __has_builtin(__is_pointer) template <typename _Tp> inline constexpr bool is_pointer_v = __is_pointer(_Tp); #else template <typename _Tp> inline constexpr bool is_pointer_v = false; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp*> = true; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp* const> = true; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp* volatile> = true; template <typename _Tp> inline constexpr bool is_pointer_v<_Tp* const volatile> = true; #endif
