[v2,3/3] libstdc++: Optimize is_fundamental performance by __is_arithmetic built-in
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Commit Message
This patch optimizes the performance of the is_fundamental trait by
dispatching to the new __is_arithmetic built-in trait.
libstdc++-v3/ChangeLog:
* include/std/type_traits (is_fundamental_v): Use __is_arithmetic
built-in trait.
(is_fundamental): Likewise. Optimize the original implementation.
Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
Comments
Hi,
Here are the benchmarks for this change:
* is_fundamental
https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental.md#fri-jul-14-091146-pm-pdt-2023
Time: -37.1619%
Peak Memory Usage: -29.4294%
Total Memory Usage: -29.4783%
* is_fundamental_v
https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental_v.md#fri-jul-14-091757-pm-pdt-2023
Time: -35.5446%
Peak Memory Usage: -30.0096%
Total Memory Usage: -30.6021%
* is_fundamental with bool_constant (on trunk
[18dac101678b8c0aed4bd995351e47f26cd54dec])
https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-bool_constant.md#fri-jul-14-094237-pm-pdt-2023
Time: -28.3908%
Peak Memory Usage: -18.5403%
Total Memory Usage: -19.9045%
---
It appears using bool_constant is better than disjunction. If my
understanding is correct, disjunction can avoid later instantiations
when short-circuiting, but might the evaluation of disjunction be more
expensive than evaluating is_void and is_null_pointer? Or my benchmark
might be just incorrect.
Sincerely,
Ken Matsui
On Fri, Jul 14, 2023 at 9:57 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
>
> This patch optimizes the performance of the is_fundamental trait by
> dispatching to the new __is_arithmetic built-in trait.
>
> libstdc++-v3/ChangeLog:
>
> * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
> built-in trait.
> (is_fundamental): Likewise. Optimize the original implementation.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
> libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> index 7ebbe04c77b..cf24de2fcac 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif
>
> /// is_fundamental
> +#if __has_builtin(__is_arithmetic)
> + template<typename _Tp>
> + struct is_fundamental
> + : public __bool_constant<__is_arithmetic(_Tp)
> + || is_void<_Tp>::value
> + || is_null_pointer<_Tp>::value>
> + { };
> +#else
> template<typename _Tp>
> struct is_fundamental
> - : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
> - is_null_pointer<_Tp>>::type
> + : public __bool_constant<is_arithmetic<_Tp>::value
> + || is_void<_Tp>::value
> + || is_null_pointer<_Tp>::value>
> { };
> +#endif
>
> /// is_object
> template<typename _Tp>
> @@ -3209,13 +3219,16 @@ template <typename _Tp>
> #if __has_builtin(__is_arithmetic)
> template <typename _Tp>
> inline constexpr bool is_arithmetic_v = __is_arithmetic(_Tp);
> +template <typename _Tp>
> + inline constexpr bool is_fundamental_v
> + = __is_arithmetic(_Tp) || is_void_v<_Tp> || is_null_pointer_v<_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;
> +#endif
> +
> template <typename _Tp>
> inline constexpr bool is_object_v = is_object<_Tp>::value;
> template <typename _Tp>
> --
> 2.41.0
>
On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> This patch optimizes the performance of the is_fundamental trait by
> dispatching to the new __is_arithmetic built-in trait.
>
> libstdc++-v3/ChangeLog:
>
> * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
> built-in trait.
> (is_fundamental): Likewise. Optimize the original implementation.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
> libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> index 7ebbe04c77b..cf24de2fcac 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif
>
> /// is_fundamental
> +#if __has_builtin(__is_arithmetic)
> + template<typename _Tp>
> + struct is_fundamental
> + : public __bool_constant<__is_arithmetic(_Tp)
> + || is_void<_Tp>::value
> + || is_null_pointer<_Tp>::value>
> + { };
What about doing this ?
template<typename _Tp>
struct is_fundamental
: public __bool_constant<__is_arithmetic(_Tp)
|| __or_<is_void<_Tp>,
is_null_pointer<_Tp>>::value>
{ };
Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
>
>
> On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> > This patch optimizes the performance of the is_fundamental trait by
> > dispatching to the new __is_arithmetic built-in trait.
> >
> > libstdc++-v3/ChangeLog:
> >
> > * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
> > built-in trait.
> > (is_fundamental): Likewise. Optimize the original implementation.
> >
> > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > ---
> > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> > 1 file changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> > index 7ebbe04c77b..cf24de2fcac 100644
> > --- a/libstdc++-v3/include/std/type_traits
> > +++ b/libstdc++-v3/include/std/type_traits
> > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > #endif
> >
> > /// is_fundamental
> > +#if __has_builtin(__is_arithmetic)
> > + template<typename _Tp>
> > + struct is_fundamental
> > + : public __bool_constant<__is_arithmetic(_Tp)
> > + || is_void<_Tp>::value
> > + || is_null_pointer<_Tp>::value>
> > + { };
>
> What about doing this ?
>
> template<typename _Tp>
> struct is_fundamental
> : public __bool_constant<__is_arithmetic(_Tp)
> || __or_<is_void<_Tp>,
> is_null_pointer<_Tp>>::value>
> { };
>
> Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
>
Let me take a benchmark for this later.
Hi,
I took a benchmark for this.
https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
template<typename _Tp>
struct is_fundamental
: public std::bool_constant<__is_arithmetic(_Tp)
|| std::is_void<_Tp>::value
|| std::is_null_pointer<_Tp>::value>
{ };
is faster than:
template<typename _Tp>
struct is_fundamental
: public std::bool_constant<__is_arithmetic(_Tp)
|| std::disjunction<std::is_void<_Tp>,
std::is_null_pointer<_Tp>
>::value>
{ };
Time: -32.2871%
Peak Memory: -18.5071%
Total Memory: -20.1991%
Sincerely,
Ken Matsui
On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
> >
> >
> > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> > > This patch optimizes the performance of the is_fundamental trait by
> > > dispatching to the new __is_arithmetic built-in trait.
> > >
> > > libstdc++-v3/ChangeLog:
> > >
> > > * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
> > > built-in trait.
> > > (is_fundamental): Likewise. Optimize the original implementation.
> > >
> > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > > ---
> > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> > > 1 file changed, 17 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> > > index 7ebbe04c77b..cf24de2fcac 100644
> > > --- a/libstdc++-v3/include/std/type_traits
> > > +++ b/libstdc++-v3/include/std/type_traits
> > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > #endif
> > >
> > > /// is_fundamental
> > > +#if __has_builtin(__is_arithmetic)
> > > + template<typename _Tp>
> > > + struct is_fundamental
> > > + : public __bool_constant<__is_arithmetic(_Tp)
> > > + || is_void<_Tp>::value
> > > + || is_null_pointer<_Tp>::value>
> > > + { };
> >
> > What about doing this ?
> >
> > template<typename _Tp>
> > struct is_fundamental
> > : public __bool_constant<__is_arithmetic(_Tp)
> > || __or_<is_void<_Tp>,
> > is_null_pointer<_Tp>>::value>
> > { };
> >
> > Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
> >
> Let me take a benchmark for this later.
I will eventually work on disjunction to somehow optimize, but in the
meantime, this might be a better implementation. Of course, my
benchmark could be wrong.
On Mon, Jul 17, 2023 at 11:24 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> Hi,
>
> I took a benchmark for this.
>
> https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
>
> template<typename _Tp>
> struct is_fundamental
> : public std::bool_constant<__is_arithmetic(_Tp)
> || std::is_void<_Tp>::value
> || std::is_null_pointer<_Tp>::value>
> { };
>
> is faster than:
>
> template<typename _Tp>
> struct is_fundamental
> : public std::bool_constant<__is_arithmetic(_Tp)
> || std::disjunction<std::is_void<_Tp>,
> std::is_null_pointer<_Tp>
> >::value>
> { };
>
> Time: -32.2871%
> Peak Memory: -18.5071%
> Total Memory: -20.1991%
>
> Sincerely,
> Ken Matsui
>
> On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
> >
> > On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
> > >
> > >
> > > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> > > > This patch optimizes the performance of the is_fundamental trait by
> > > > dispatching to the new __is_arithmetic built-in trait.
> > > >
> > > > libstdc++-v3/ChangeLog:
> > > >
> > > > * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
> > > > built-in trait.
> > > > (is_fundamental): Likewise. Optimize the original implementation.
> > > >
> > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > > > ---
> > > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> > > > 1 file changed, 17 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> > > > index 7ebbe04c77b..cf24de2fcac 100644
> > > > --- a/libstdc++-v3/include/std/type_traits
> > > > +++ b/libstdc++-v3/include/std/type_traits
> > > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > #endif
> > > >
> > > > /// is_fundamental
> > > > +#if __has_builtin(__is_arithmetic)
> > > > + template<typename _Tp>
> > > > + struct is_fundamental
> > > > + : public __bool_constant<__is_arithmetic(_Tp)
> > > > + || is_void<_Tp>::value
> > > > + || is_null_pointer<_Tp>::value>
> > > > + { };
> > >
> > > What about doing this ?
> > >
> > > template<typename _Tp>
> > > struct is_fundamental
> > > : public __bool_constant<__is_arithmetic(_Tp)
> > > || __or_<is_void<_Tp>,
> > > is_null_pointer<_Tp>>::value>
> > > { };
> > >
> > > Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
> > >
> > Let me take a benchmark for this later.
It seems rather logical cause std::disjunction is supposed to avoid
instantiations but in case of:
std::disjunction<std::is_void<_Tp>, std::is_null_pointer<_Tp>>
you'll avoid std::is_null_pointer instantiation only for 'void' type and
at the price of instantiating std::disjunction so 2 instantiations at
best but most of the time 3, clearly useless here.
On 18/07/2023 08:24, Ken Matsui wrote:
> Hi,
>
> I took a benchmark for this.
>
> https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
>
> template<typename _Tp>
> struct is_fundamental
> : public std::bool_constant<__is_arithmetic(_Tp)
> || std::is_void<_Tp>::value
> || std::is_null_pointer<_Tp>::value>
> { };
>
> is faster than:
>
> template<typename _Tp>
> struct is_fundamental
> : public std::bool_constant<__is_arithmetic(_Tp)
> || std::disjunction<std::is_void<_Tp>,
> std::is_null_pointer<_Tp>
> >::value>
> { };
>
> Time: -32.2871%
> Peak Memory: -18.5071%
> Total Memory: -20.1991%
>
> Sincerely,
> Ken Matsui
>
> On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>> On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
>>>
>>> On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
>>>> This patch optimizes the performance of the is_fundamental trait by
>>>> dispatching to the new __is_arithmetic built-in trait.
>>>>
>>>> libstdc++-v3/ChangeLog:
>>>>
>>>> * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
>>>> built-in trait.
>>>> (is_fundamental): Likewise. Optimize the original implementation.
>>>>
>>>> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
>>>> ---
>>>> libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
>>>> 1 file changed, 17 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
>>>> index 7ebbe04c77b..cf24de2fcac 100644
>>>> --- a/libstdc++-v3/include/std/type_traits
>>>> +++ b/libstdc++-v3/include/std/type_traits
>>>> @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>>> #endif
>>>>
>>>> /// is_fundamental
>>>> +#if __has_builtin(__is_arithmetic)
>>>> + template<typename _Tp>
>>>> + struct is_fundamental
>>>> + : public __bool_constant<__is_arithmetic(_Tp)
>>>> + || is_void<_Tp>::value
>>>> + || is_null_pointer<_Tp>::value>
>>>> + { };
>>> What about doing this ?
>>>
>>> template<typename _Tp>
>>> struct is_fundamental
>>> : public __bool_constant<__is_arithmetic(_Tp)
>>> || __or_<is_void<_Tp>,
>>> is_null_pointer<_Tp>>::value>
>>> { };
>>>
>>> Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
>>>
>> Let me take a benchmark for this later.
On Tue, 18 Jul 2023 at 07:28, Ken Matsui via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:
> I will eventually work on disjunction to somehow optimize, but in the
> meantime, this might be a better implementation. Of course, my
> benchmark could be wrong.
>
You should use __or_ internally in libstdc++ code, not std::disjunction.
Patrick already optimized both of those, and __or_ is slightly faster
(because it doesn't have to conform to the full requirements of
std::disjunction).
A compiler built-in for __or_ / __disjunction might perform better. But
eventually if we're going to have built-ins for all of __is_arithmetic,
__is_void, and __is_null_pointer, then we would want simply:
__is_arithmetic(T) || __is_void(T) || __is_null_pointer(T)
and so we wouldn't need to avoid instantiating any class templates at all.
>
> On Mon, Jul 17, 2023 at 11:24 PM Ken Matsui <kmatsui@cs.washington.edu>
> wrote:
> >
> > Hi,
> >
> > I took a benchmark for this.
> >
> >
> https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
> >
> > template<typename _Tp>
> > struct is_fundamental
> > : public std::bool_constant<__is_arithmetic(_Tp)
> > || std::is_void<_Tp>::value
> > || std::is_null_pointer<_Tp>::value>
> > { };
> >
> > is faster than:
> >
> > template<typename _Tp>
> > struct is_fundamental
> > : public std::bool_constant<__is_arithmetic(_Tp)
> > || std::disjunction<std::is_void<_Tp>,
> > std::is_null_pointer<_Tp>
> > >::value>
> > { };
> >
> > Time: -32.2871%
> > Peak Memory: -18.5071%
> > Total Memory: -20.1991%
> >
> > Sincerely,
> > Ken Matsui
> >
> > On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu>
> wrote:
> > >
> > > On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com>
> wrote:
> > > >
> > > >
> > > > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> > > > > This patch optimizes the performance of the is_fundamental trait by
> > > > > dispatching to the new __is_arithmetic built-in trait.
> > > > >
> > > > > libstdc++-v3/ChangeLog:
> > > > >
> > > > > * include/std/type_traits (is_fundamental_v): Use
> __is_arithmetic
> > > > > built-in trait.
> > > > > (is_fundamental): Likewise. Optimize the original
> implementation.
> > > > >
> > > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > > > > ---
> > > > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> > > > > 1 file changed, 17 insertions(+), 4 deletions(-)
> > > > >
> > > > > diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> > > > > index 7ebbe04c77b..cf24de2fcac 100644
> > > > > --- a/libstdc++-v3/include/std/type_traits
> > > > > +++ b/libstdc++-v3/include/std/type_traits
> > > > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > #endif
> > > > >
> > > > > /// is_fundamental
> > > > > +#if __has_builtin(__is_arithmetic)
> > > > > + template<typename _Tp>
> > > > > + struct is_fundamental
> > > > > + : public __bool_constant<__is_arithmetic(_Tp)
> > > > > + || is_void<_Tp>::value
> > > > > + || is_null_pointer<_Tp>::value>
> > > > > + { };
> > > >
> > > > What about doing this ?
> > > >
> > > > template<typename _Tp>
> > > > struct is_fundamental
> > > > : public __bool_constant<__is_arithmetic(_Tp)
> > > > || __or_<is_void<_Tp>,
> > > > is_null_pointer<_Tp>>::value>
> > > > { };
> > > >
> > > > Based on your benches it seems that builtin __is_arithmetic is much
> better that std::is_arithmetic. But __or_ could still avoid instantiation
> of is_null_pointer.
> > > >
> > > Let me take a benchmark for this later.
>
>
On Tue, 18 Jul 2023 at 07:25, Ken Matsui via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:
> Hi,
>
> I took a benchmark for this.
>
>
> https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
>
> template<typename _Tp>
> struct is_fundamental
> : public std::bool_constant<__is_arithmetic(_Tp)
> || std::is_void<_Tp>::value
> || std::is_null_pointer<_Tp>::value>
> { };
>
> is faster than:
>
> template<typename _Tp>
> struct is_fundamental
> : public std::bool_constant<__is_arithmetic(_Tp)
> || std::disjunction<std::is_void<_Tp>,
> std::is_null_pointer<_Tp>
> >::value>
> { };
>
> Time: -32.2871%
> Peak Memory: -18.5071%
> Total Memory: -20.1991%
>
But what about the fallback implementation of is_fundamental where we don't
have the __is_arithmetic built-in?
- : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
- is_null_pointer<_Tp>>::type
+ : public __bool_constant<is_arithmetic<_Tp>::value
+ || is_void<_Tp>::value
+ || is_null_pointer<_Tp>::value>
Here the use of __or_ means that for is_fundamental<int> we don't
instantiate is_void<int> and is_null_pointer<int>. Isn't that still
worthwhile?
>
> Sincerely,
> Ken Matsui
>
> On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu>
> wrote:
> >
> > On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com>
> wrote:
> > >
> > >
> > > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> > > > This patch optimizes the performance of the is_fundamental trait by
> > > > dispatching to the new __is_arithmetic built-in trait.
> > > >
> > > > libstdc++-v3/ChangeLog:
> > > >
> > > > * include/std/type_traits (is_fundamental_v): Use
> __is_arithmetic
> > > > built-in trait.
> > > > (is_fundamental): Likewise. Optimize the original
> implementation.
> > > >
> > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > > > ---
> > > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> > > > 1 file changed, 17 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> > > > index 7ebbe04c77b..cf24de2fcac 100644
> > > > --- a/libstdc++-v3/include/std/type_traits
> > > > +++ b/libstdc++-v3/include/std/type_traits
> > > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > #endif
> > > >
> > > > /// is_fundamental
> > > > +#if __has_builtin(__is_arithmetic)
> > > > + template<typename _Tp>
> > > > + struct is_fundamental
> > > > + : public __bool_constant<__is_arithmetic(_Tp)
> > > > + || is_void<_Tp>::value
> > > > + || is_null_pointer<_Tp>::value>
> > > > + { };
> > >
> > > What about doing this ?
> > >
> > > template<typename _Tp>
> > > struct is_fundamental
> > > : public __bool_constant<__is_arithmetic(_Tp)
> > > || __or_<is_void<_Tp>,
> > > is_null_pointer<_Tp>>::value>
> > > { };
> > >
> > > Based on your benches it seems that builtin __is_arithmetic is much
> better that std::is_arithmetic. But __or_ could still avoid instantiation
> of is_null_pointer.
> > >
> > Let me take a benchmark for this later.
>
>
On Tue, Aug 8, 2023 at 1:14 PM Jonathan Wakely <jwakely@redhat.com> wrote:
>
>
>
> On Tue, 18 Jul 2023 at 07:28, Ken Matsui via Libstdc++ <libstdc++@gcc.gnu.org> wrote:
>>
>> I will eventually work on disjunction to somehow optimize, but in the
>> meantime, this might be a better implementation. Of course, my
>> benchmark could be wrong.
>
>
> You should use __or_ internally in libstdc++ code, not std::disjunction.
>
> Patrick already optimized both of those, and __or_ is slightly faster (because it doesn't have to conform to the full requirements of std::disjunction).
>
I will! Thank you!
> A compiler built-in for __or_ / __disjunction might perform better. But eventually if we're going to have built-ins for all of __is_arithmetic, __is_void, and __is_null_pointer, then we would want simply:
>
> __is_arithmetic(T) || __is_void(T) || __is_null_pointer(T)
>
> and so we wouldn't need to avoid instantiating any class templates at all.
>
I think we are not going to define built-ins for is_void and
is_null_pointer as their type trait implementations are already
optimal.
>
>>
>>
>> On Mon, Jul 17, 2023 at 11:24 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>> >
>> > Hi,
>> >
>> > I took a benchmark for this.
>> >
>> > https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
>> >
>> > template<typename _Tp>
>> > struct is_fundamental
>> > : public std::bool_constant<__is_arithmetic(_Tp)
>> > || std::is_void<_Tp>::value
>> > || std::is_null_pointer<_Tp>::value>
>> > { };
>> >
>> > is faster than:
>> >
>> > template<typename _Tp>
>> > struct is_fundamental
>> > : public std::bool_constant<__is_arithmetic(_Tp)
>> > || std::disjunction<std::is_void<_Tp>,
>> > std::is_null_pointer<_Tp>
>> > >::value>
>> > { };
>> >
>> > Time: -32.2871%
>> > Peak Memory: -18.5071%
>> > Total Memory: -20.1991%
>> >
>> > Sincerely,
>> > Ken Matsui
>> >
>> > On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>> > >
>> > > On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
>> > > >
>> > > >
>> > > > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
>> > > > > This patch optimizes the performance of the is_fundamental trait by
>> > > > > dispatching to the new __is_arithmetic built-in trait.
>> > > > >
>> > > > > libstdc++-v3/ChangeLog:
>> > > > >
>> > > > > * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
>> > > > > built-in trait.
>> > > > > (is_fundamental): Likewise. Optimize the original implementation.
>> > > > >
>> > > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
>> > > > > ---
>> > > > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
>> > > > > 1 file changed, 17 insertions(+), 4 deletions(-)
>> > > > >
>> > > > > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
>> > > > > index 7ebbe04c77b..cf24de2fcac 100644
>> > > > > --- a/libstdc++-v3/include/std/type_traits
>> > > > > +++ b/libstdc++-v3/include/std/type_traits
>> > > > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>> > > > > #endif
>> > > > >
>> > > > > /// is_fundamental
>> > > > > +#if __has_builtin(__is_arithmetic)
>> > > > > + template<typename _Tp>
>> > > > > + struct is_fundamental
>> > > > > + : public __bool_constant<__is_arithmetic(_Tp)
>> > > > > + || is_void<_Tp>::value
>> > > > > + || is_null_pointer<_Tp>::value>
>> > > > > + { };
>> > > >
>> > > > What about doing this ?
>> > > >
>> > > > template<typename _Tp>
>> > > > struct is_fundamental
>> > > > : public __bool_constant<__is_arithmetic(_Tp)
>> > > > || __or_<is_void<_Tp>,
>> > > > is_null_pointer<_Tp>>::value>
>> > > > { };
>> > > >
>> > > > Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
>> > > >
>> > > Let me take a benchmark for this later.
>>
On Tue, Aug 8, 2023 at 1:19 PM Jonathan Wakely <jwakely@redhat.com> wrote:
>
>
>
> On Tue, 18 Jul 2023 at 07:25, Ken Matsui via Libstdc++ <libstdc++@gcc.gnu.org> wrote:
>>
>> Hi,
>>
>> I took a benchmark for this.
>>
>> https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
>>
>> template<typename _Tp>
>> struct is_fundamental
>> : public std::bool_constant<__is_arithmetic(_Tp)
>> || std::is_void<_Tp>::value
>> || std::is_null_pointer<_Tp>::value>
>> { };
>>
>> is faster than:
>>
>> template<typename _Tp>
>> struct is_fundamental
>> : public std::bool_constant<__is_arithmetic(_Tp)
>> || std::disjunction<std::is_void<_Tp>,
>> std::is_null_pointer<_Tp>
>> >::value>
>> { };
>>
>> Time: -32.2871%
>> Peak Memory: -18.5071%
>> Total Memory: -20.1991%
>
>
> But what about the fallback implementation of is_fundamental where we don't have the __is_arithmetic built-in?
That fallback implementation would be this:
https://github.com/ken-matsui/gsoc23/blob/967e20770599f2a8925c9794669111faef11beb7/is_fundamental.cc#L11-L15.
The is_fundamental-disjunction.cc benchmark used the USE_BUILTIN
macro, but in this benchmark, I used it to just switch two different
implementations that use the __is_arithmetic built-in.
> - : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
> - is_null_pointer<_Tp>>::type
> + : public __bool_constant<is_arithmetic<_Tp>::value
> + || is_void<_Tp>::value
> + || is_null_pointer<_Tp>::value>
>
> Here the use of __or_ means that for is_fundamental<int> we don't instantiate is_void<int> and is_null_pointer<int>. Isn't that still worthwhile?
>
Let me take a benchmark with __or_ later! We may see a difference.
>
>
>
>>
>>
>> Sincerely,
>> Ken Matsui
>>
>> On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>> >
>> > On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
>> > >
>> > >
>> > > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
>> > > > This patch optimizes the performance of the is_fundamental trait by
>> > > > dispatching to the new __is_arithmetic built-in trait.
>> > > >
>> > > > libstdc++-v3/ChangeLog:
>> > > >
>> > > > * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
>> > > > built-in trait.
>> > > > (is_fundamental): Likewise. Optimize the original implementation.
>> > > >
>> > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
>> > > > ---
>> > > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
>> > > > 1 file changed, 17 insertions(+), 4 deletions(-)
>> > > >
>> > > > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
>> > > > index 7ebbe04c77b..cf24de2fcac 100644
>> > > > --- a/libstdc++-v3/include/std/type_traits
>> > > > +++ b/libstdc++-v3/include/std/type_traits
>> > > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>> > > > #endif
>> > > >
>> > > > /// is_fundamental
>> > > > +#if __has_builtin(__is_arithmetic)
>> > > > + template<typename _Tp>
>> > > > + struct is_fundamental
>> > > > + : public __bool_constant<__is_arithmetic(_Tp)
>> > > > + || is_void<_Tp>::value
>> > > > + || is_null_pointer<_Tp>::value>
>> > > > + { };
>> > >
>> > > What about doing this ?
>> > >
>> > > template<typename _Tp>
>> > > struct is_fundamental
>> > > : public __bool_constant<__is_arithmetic(_Tp)
>> > > || __or_<is_void<_Tp>,
>> > > is_null_pointer<_Tp>>::value>
>> > > { };
>> > >
>> > > Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
>> > >
>> > Let me take a benchmark for this later.
>>
On Thu, Aug 31, 2023 at 6:57 AM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> On Tue, Aug 8, 2023 at 1:19 PM Jonathan Wakely <jwakely@redhat.com> wrote:
> >
> >
> >
> > On Tue, 18 Jul 2023 at 07:25, Ken Matsui via Libstdc++ <libstdc++@gcc.gnu.org> wrote:
> >>
> >> Hi,
> >>
> >> I took a benchmark for this.
> >>
> >> https://github.com/ken-matsui/gcc-benches/blob/main/is_fundamental-disjunction.md#mon-jul-17-105937-pm-pdt-2023
> >>
> >> template<typename _Tp>
> >> struct is_fundamental
> >> : public std::bool_constant<__is_arithmetic(_Tp)
> >> || std::is_void<_Tp>::value
> >> || std::is_null_pointer<_Tp>::value>
> >> { };
> >>
> >> is faster than:
> >>
> >> template<typename _Tp>
> >> struct is_fundamental
> >> : public std::bool_constant<__is_arithmetic(_Tp)
> >> || std::disjunction<std::is_void<_Tp>,
> >> std::is_null_pointer<_Tp>
> >> >::value>
> >> { };
> >>
> >> Time: -32.2871%
> >> Peak Memory: -18.5071%
> >> Total Memory: -20.1991%
> >
> >
> > But what about the fallback implementation of is_fundamental where we don't have the __is_arithmetic built-in?
>
> That fallback implementation would be this:
> https://github.com/ken-matsui/gsoc23/blob/967e20770599f2a8925c9794669111faef11beb7/is_fundamental.cc#L11-L15.
>
> The is_fundamental-disjunction.cc benchmark used the USE_BUILTIN
> macro, but in this benchmark, I used it to just switch two different
> implementations that use the __is_arithmetic built-in.
>
> > - : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
> > - is_null_pointer<_Tp>>::type
> > + : public __bool_constant<is_arithmetic<_Tp>::value
> > + || is_void<_Tp>::value
> > + || is_null_pointer<_Tp>::value>
> >
> > Here the use of __or_ means that for is_fundamental<int> we don't instantiate is_void<int> and is_null_pointer<int>. Isn't that still worthwhile?
> >
> Let me take a benchmark with __or_ later! We may see a difference.
>
Here is the benchmark result with __or_:
https://github.com/ken-matsui/gsoc23/blob/main/is_fundamental-disjunction.md#thu-aug-31-075127-am-pdt-2023
Time: -23.3935%
Peak Memory: -10.2915%
Total Memory: -14.4165%
Considering the following was with disjunction, __or_ is faster than
disjunction, but still just || seems much faster.
Time: -32.2871%
Peak Memory: -18.5071%
Total Memory: -20.1991%
> >
> >
> >
> >>
> >>
> >> Sincerely,
> >> Ken Matsui
> >>
> >> On Sun, Jul 16, 2023 at 9:49 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
> >> >
> >> > On Sun, Jul 16, 2023 at 5:41 AM François Dumont <frs.dumont@gmail.com> wrote:
> >> > >
> >> > >
> >> > > On 15/07/2023 06:55, Ken Matsui via Libstdc++ wrote:
> >> > > > This patch optimizes the performance of the is_fundamental trait by
> >> > > > dispatching to the new __is_arithmetic built-in trait.
> >> > > >
> >> > > > libstdc++-v3/ChangeLog:
> >> > > >
> >> > > > * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
> >> > > > built-in trait.
> >> > > > (is_fundamental): Likewise. Optimize the original implementation.
> >> > > >
> >> > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> >> > > > ---
> >> > > > libstdc++-v3/include/std/type_traits | 21 +++++++++++++++++----
> >> > > > 1 file changed, 17 insertions(+), 4 deletions(-)
> >> > > >
> >> > > > diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> >> > > > index 7ebbe04c77b..cf24de2fcac 100644
> >> > > > --- a/libstdc++-v3/include/std/type_traits
> >> > > > +++ b/libstdc++-v3/include/std/type_traits
> >> > > > @@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> >> > > > #endif
> >> > > >
> >> > > > /// is_fundamental
> >> > > > +#if __has_builtin(__is_arithmetic)
> >> > > > + template<typename _Tp>
> >> > > > + struct is_fundamental
> >> > > > + : public __bool_constant<__is_arithmetic(_Tp)
> >> > > > + || is_void<_Tp>::value
> >> > > > + || is_null_pointer<_Tp>::value>
> >> > > > + { };
> >> > >
> >> > > What about doing this ?
> >> > >
> >> > > template<typename _Tp>
> >> > > struct is_fundamental
> >> > > : public __bool_constant<__is_arithmetic(_Tp)
> >> > > || __or_<is_void<_Tp>,
> >> > > is_null_pointer<_Tp>>::value>
> >> > > { };
> >> > >
> >> > > Based on your benches it seems that builtin __is_arithmetic is much better that std::is_arithmetic. But __or_ could still avoid instantiation of is_null_pointer.
> >> > >
> >> > Let me take a benchmark for this later.
> >>
@@ -668,11 +668,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
/// is_fundamental
+#if __has_builtin(__is_arithmetic)
+ template<typename _Tp>
+ struct is_fundamental
+ : public __bool_constant<__is_arithmetic(_Tp)
+ || is_void<_Tp>::value
+ || is_null_pointer<_Tp>::value>
+ { };
+#else
template<typename _Tp>
struct is_fundamental
- : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
- is_null_pointer<_Tp>>::type
+ : public __bool_constant<is_arithmetic<_Tp>::value
+ || is_void<_Tp>::value
+ || is_null_pointer<_Tp>::value>
{ };
+#endif
/// is_object
template<typename _Tp>
@@ -3209,13 +3219,16 @@ template <typename _Tp>
#if __has_builtin(__is_arithmetic)
template <typename _Tp>
inline constexpr bool is_arithmetic_v = __is_arithmetic(_Tp);
+template <typename _Tp>
+ inline constexpr bool is_fundamental_v
+ = __is_arithmetic(_Tp) || is_void_v<_Tp> || is_null_pointer_v<_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;
+#endif
+
template <typename _Tp>
inline constexpr bool is_object_v = is_object<_Tp>::value;
template <typename _Tp>