Hi, Here is the benchmark result for is_reference:
https://github.com/ken-matsui/gcc-benches/blob/main/is_reference.md#wed-jul-12-074702-pm-pdt-2023 Time: -8.15593% Peak Memory Usage: -4.48408% Total Memory Usage: -8.03783% Sincerely, Ken Matsui On Wed, Jul 12, 2023 at 7:39 PM Ken Matsui <kmat...@gcc.gnu.org> wrote: > > This patch gets std::is_reference to dispatch to new built-in trait > __is_reference. > > libstdc++-v3/ChangeLog: > > * include/std/type_traits (is_reference): Use __is_reference built-in > trait. > (is_reference_v): Likewise. > > Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org> > --- > 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..2a14df7e5f9 100644 > --- a/libstdc++-v3/include/std/type_traits > +++ b/libstdc++-v3/include/std/type_traits > @@ -639,6 +639,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > // Composite type categories. > > /// is_reference > +#if __has_builtin(__is_reference) > + template<typename _Tp> > + struct is_reference > + : public __bool_constant<__is_reference(_Tp)> > + { }; > +#else > template<typename _Tp> > struct is_reference > : public false_type > @@ -653,6 +659,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > struct is_reference<_Tp&&> > : public true_type > { }; > +#endif > > /// is_arithmetic > template<typename _Tp> > @@ -3192,12 +3199,19 @@ template <typename _Tp> > inline constexpr bool is_class_v = __is_class(_Tp); > template <typename _Tp> > inline constexpr bool is_function_v = is_function<_Tp>::value; > + > +#if __has_builtin(__is_reference) > +template <typename _Tp> > + inline constexpr bool is_reference_v = __is_reference(_Tp); > +#else > template <typename _Tp> > inline constexpr bool is_reference_v = false; > template <typename _Tp> > inline constexpr bool is_reference_v<_Tp&> = true; > template <typename _Tp> > inline constexpr bool is_reference_v<_Tp&&> = true; > +#endif > + > template <typename _Tp> > inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value; > template <typename _Tp> > -- > 2.41.0 >
