From: Jonathan Wakely <jwakely@redhat.com>
To: Ken Matsui <kmatsui@cs.washington.edu>
Cc: Ken Matsui <kmatsui@gcc.gnu.org>,
gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
Subject: Re: [PATCH v2 1/2] c++, libstdc++: implement __is_pointer built-in trait
Date: Fri, 14 Jul 2023 11:48:35 +0100 [thread overview]
Message-ID: <CACb0b4kQKq8F3WTSQXpJshGav0BfsKi+43NdW8rJKmG-fLCO-w@mail.gmail.com> (raw)
In-Reply-To: <CAML+3pXbAmc8M682qXhSm6XDPzbeMM6aydRu5s7fsorVBc72kA@mail.gmail.com>
On Thu, 13 Jul 2023 at 21:04, Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> On Thu, Jul 13, 2023 at 2:22 AM Jonathan Wakely <jwakely@redhat.com> wrote:
> >
> > On Wed, 12 Jul 2023 at 21:42, Ken Matsui <kmatsui@cs.washington.edu> wrote:
> > >
> > > On Wed, Jul 12, 2023 at 3:01 AM Jonathan Wakely <jwakely@redhat.com> wrote:
> > > >
> > > > On Mon, 10 Jul 2023 at 06:51, Ken Matsui via Libstdc++
> > > > <libstdc++@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
> > >
> > > Hi François and Jonathan,
> > >
> > > Thank you for your reviews! I will rename the four underscores to the
> > > appropriate name and take a benchmark once I get home.
> > >
> > > If I apply your change on is_pointer_v, is it better to add the
> > > `Co-authored-by:` line in the commit?
> >
> > Yes, that would be the correct thing to do (although in this case the
> > change is small enough that I don't really care about getting credit
> > for it :-)
> >
> Thank you! I will include it in my commit :) I see that you included
> the DCO sign-off in the MAINTAINERS file. However, if a reviewer
> doesn't, should I include the `Signed-off-by:` line for the reviewer
> as well?
No, reviewers should not sign-off, that's for the code author. And
authors should add that themselves (or clearly state that they agree
to the DCO terms). You should not sign-off on someone else's behalf.
next prev parent reply other threads:[~2023-07-14 10:48 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-10 5:23 [PATCH " Ken Matsui
2023-07-10 5:23 ` [PATCH 2/2] libstdc++: use new built-in trait __is_pointer Ken Matsui
2023-07-10 5:32 ` Daniel Krügler
2023-07-10 5:34 ` Ken Matsui
2023-07-10 5:38 ` [PATCH v2 1/2] c++, libstdc++: implement __is_pointer built-in trait Ken Matsui
2023-07-10 5:38 ` [PATCH v2 2/2] libstdc++: use new built-in trait __is_pointer Ken Matsui
2023-07-10 5:50 ` [PATCH v2 1/2] c++, libstdc++: implement __is_pointer built-in trait Ken Matsui
2023-07-12 10:01 ` Jonathan Wakely
2023-07-12 20:42 ` Ken Matsui
2023-07-13 1:11 ` [PATCH v3 1/2] c++, libstdc++: Implement " Ken Matsui
2023-07-13 1:11 ` [PATCH v3 2/2] libstdc++: Use new built-in trait __is_pointer Ken Matsui
2023-07-13 1:13 ` [PATCH v3 1/2] c++, libstdc++: Implement __is_pointer built-in trait Ken Matsui
2023-07-13 1:15 ` Ken Matsui
2023-07-13 3:16 ` [PATCH v4 " Ken Matsui
2023-07-13 3:16 ` [PATCH v4 2/2] libstdc++: Use new built-in trait __is_pointer Ken Matsui
2023-07-13 3:19 ` [PATCH v5 1/2] c++, libstdc++: Implement __is_pointer built-in trait Ken Matsui
2023-07-13 3:19 ` [PATCH v5 2/2] libstdc++: Use new built-in trait __is_pointer Ken Matsui
2023-07-13 20:48 ` [PATCH v6 1/2] c++, libstdc++: Implement __is_pointer built-in trait Ken Matsui
2023-07-13 20:48 ` [PATCH v6 2/2] libstdc++: Use new built-in trait __is_pointer Ken Matsui
2023-09-01 13:00 ` [PING][PATCH " Ken Matsui
2023-07-13 9:21 ` [PATCH v2 1/2] c++, libstdc++: implement __is_pointer built-in trait Jonathan Wakely
2023-07-13 20:04 ` Ken Matsui
2023-07-14 10:48 ` Jonathan Wakely [this message]
2023-07-14 10:49 ` Jonathan Wakely
2023-07-14 19:55 ` Ken Matsui
2023-07-12 4:40 ` [PATCH " François Dumont
2023-07-12 9:47 ` Jonathan Wakely
2023-07-12 9:48 ` Jonathan Wakely
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