On Thu, May 23, 2024 at 3:15 PM Patrick Palka <ppa...@redhat.com> wrote:
>
> On Sat, 11 May 2024, Ken Matsui wrote:
>
> > This patch optimizes the compilation performance of std::is_const
> > by dispatching to the new __is_const built-in trait.
>
> This patch series LGTM
Thank you!
>
> >
> > libstdc++-v3/ChangeLog:
> >
> > * include/std/type_traits (is_const): Use __is_const built-in
> > trait.
> > (is_const_v): Likewise.
> >
> > Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
> > ---
> > 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 b441bf9908f..8df0cf3ac3b 100644
> > --- a/libstdc++-v3/include/std/type_traits
> > +++ b/libstdc++-v3/include/std/type_traits
> > @@ -835,6 +835,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > // Type properties.
> >
> > /// is_const
> > +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_const)
> > + template<typename _Tp>
> > + struct is_const
> > + : public __bool_constant<__is_const(_Tp)>
> > + { };
> > +#else
> > template<typename>
> > struct is_const
> > : public false_type { };
> > @@ -842,6 +848,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > template<typename _Tp>
> > struct is_const<_Tp const>
> > : public true_type { };
> > +#endif
> >
> > /// is_volatile
> > template<typename>
> > @@ -3331,10 +3338,15 @@ template <typename _Tp>
> > inline constexpr bool is_member_pointer_v =
> > is_member_pointer<_Tp>::value;
> > #endif
> >
> > +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_const)
> > +template <typename _Tp>
> > + inline constexpr bool is_const_v = __is_const(_Tp);
> > +#else
> > template <typename _Tp>
> > inline constexpr bool is_const_v = false;
> > template <typename _Tp>
> > inline constexpr bool is_const_v<const _Tp> = true;
> > +#endif
> >
> > #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function)
> > template <typename _Tp>
> > --
> > 2.44.0
> >
> >
>
