On Thu, Jan 4, 2024 at 2:13 PM Jonathan Wakely <jwak...@redhat.com> wrote: > > On Sat, 23 Dec 2023 at 22:07, Ken Matsui <kmat...@gcc.gnu.org> wrote: > > > > This patch optimizes the compilation performance of std::is_pointer > > by dispatching to the new __is_pointer built-in trait. > > > > libstdc++-v3/ChangeLog: > > > > * include/bits/cpp_type_traits.h (__is_pointer): Use > > __is_pointer built-in trait. Optimize its implementation. > > * include/std/type_traits (is_pointer): Likewise. > > (is_pointer_v): Likewise. > > > > Co-authored-by: Jonathan Wakely <jwak...@redhat.com> > > Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org> > > --- > > libstdc++-v3/include/bits/cpp_type_traits.h | 29 ++++++++++++++ > > libstdc++-v3/include/std/type_traits | 44 +++++++++++++++++---- > > 2 files changed, 65 insertions(+), 8 deletions(-) > > > > diff --git a/libstdc++-v3/include/bits/cpp_type_traits.h > > b/libstdc++-v3/include/bits/cpp_type_traits.h > > index 4312f32a4e0..c348df97f72 100644 > > --- a/libstdc++-v3/include/bits/cpp_type_traits.h > > +++ b/libstdc++-v3/include/bits/cpp_type_traits.h > > @@ -363,6 +363,13 @@ __INT_N(__GLIBCXX_TYPE_INT_N_3) > > // > > // Pointer types > > // > > +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_pointer) > > + template<typename _Tp, bool _IsPtr = __is_pointer(_Tp)> > > + struct __is_pointer : __truth_type<_IsPtr> > > + { > > + enum { __value = _IsPtr }; > > + }; > > +#else > > template<typename _Tp> > > struct __is_pointer > > { > > @@ -377,6 +384,28 @@ __INT_N(__GLIBCXX_TYPE_INT_N_3) > > typedef __true_type __type; > > }; > > > > + template<typename _Tp> > > + struct __is_pointer<_Tp* const> > > + { > > + enum { __value = 1 }; > > + typedef __true_type __type; > > + }; > > + > > + template<typename _Tp> > > + struct __is_pointer<_Tp* volatile> > > + { > > + enum { __value = 1 }; > > + typedef __true_type __type; > > + }; > > +#endif > > + > > + template<typename _Tp> > > + struct __is_pointer<_Tp* const volatile> > > + { > > + enum { __value = 1 }; > > + typedef __true_type __type; > > + }; > > Why is this partial specialization outside the #else group? >
This is totally my fault. Thank you for pointing this out! > > > + > > // > > // An arithmetic type is an integer type or a floating point type > > // > > diff --git a/libstdc++-v3/include/std/type_traits > > b/libstdc++-v3/include/std/type_traits > > index 30b0778e58a..d53911b2fa0 100644 > > --- a/libstdc++-v3/include/std/type_traits > > +++ b/libstdc++-v3/include/std/type_traits > > @@ -542,19 +542,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > : public true_type { }; > > #endif > > > > - template<typename> > > - struct __is_pointer_helper > > + /// is_pointer > > +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_pointer) > > + template<typename _Tp> > > + struct is_pointer > > + : public __bool_constant<__is_pointer(_Tp)> > > + { }; > > +#else > > + template<typename _Tp> > > + struct is_pointer > > : public false_type { }; > > > > template<typename _Tp> > > - struct __is_pointer_helper<_Tp*> > > + struct is_pointer<_Tp*> > > : public true_type { }; > > > > - /// is_pointer > > template<typename _Tp> > > - struct is_pointer > > - : public __is_pointer_helper<__remove_cv_t<_Tp>>::type > > - { }; > > + struct is_pointer<_Tp* const> > > + : public true_type { }; > > + > > + template<typename _Tp> > > + struct is_pointer<_Tp* volatile> > > + : public true_type { }; > > + > > + template<typename _Tp> > > + struct is_pointer<_Tp* const volatile> > > + : public true_type { }; > > +#endif > > > > /// is_lvalue_reference > > template<typename> > > @@ -3252,8 +3266,22 @@ template <typename _Tp, size_t _Num> > > inline constexpr bool is_array_v<_Tp[_Num]> = true; > > #endif > > > > +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_pointer) > > +template <typename _Tp> > > + inline constexpr bool is_pointer_v = __is_pointer(_Tp); > > +#else > > template <typename _Tp> > > - inline constexpr bool is_pointer_v = is_pointer<_Tp>::value; > > + 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 > > + > > template <typename _Tp> > > inline constexpr bool is_lvalue_reference_v = false; > > template <typename _Tp> > > -- > > 2.43.0 > > >