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: Wed, 12 Jul 2023 11:01:24 +0100 [thread overview]
Message-ID: <CACb0b4=gR8ahznNaqtL7BUs_ZE0tXFLMYKpd1VWLMf03htmvGg@mail.gmail.com> (raw)
In-Reply-To: <CAML+3pVbyfnZxnzcXXBg937yz7kgjSdAK6ZJLrspy=WovSov=A@mail.gmail.com>
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
next prev parent reply other threads:[~2023-07-12 10:01 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CACb0b4=gR8ahznNaqtL7BUs_ZE0tXFLMYKpd1VWLMf03htmvGg@mail.gmail.com' \
--to=jwakely@redhat.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=kmatsui@cs.washington.edu \
--cc=kmatsui@gcc.gnu.org \
--cc=libstdc++@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).