From: Joseph Myers <joseph@codesourcery.com>
To: Richard Biener <richard.guenther@gmail.com>
Cc: GCC Development <gcc@gcc.gnu.org>,
GNU C Library <libc-alpha@sourceware.org>,
<libc-coord@lists.openwall.com>
Subject: Re: [libc-coord] Add new ABI '__memcmpeq()' to libc
Date: Fri, 17 Sep 2021 14:19:53 +0000 [thread overview]
Message-ID: <alpine.DEB.2.22.394.2109171415400.3813920@digraph.polyomino.org.uk> (raw)
In-Reply-To: <CAFiYyc0nghZMYdhO9T2h92oOZtnxTHUikhgw46Gp9mme5_nVvA@mail.gmail.com>
On Fri, 17 Sep 2021, Richard Biener via Gcc wrote:
> when the libc version targeted does not provide __memcmpeq? Or would
> glibc through <string.h> magically communicate the availability of the new ABI
> without actually declaring the function?
> (I'm not sure whether a GCC build-time decision via configure is the
> very best idea)
I was supposing a build-time decision (using GCC_GLIBC_VERSION_GTE_IFELSE
to know if the glibc version on the target definitely has this function).
But if we add a header declaration, you could check for __memcmpeq being
declared (and so cover arbitrary C libraries, not just glibc, and avoid
issues of needing to disable this logic for freestanding compilations,
which would otherwise be an issue if a glibc-target toolchain is used for
a freestanding kernel compilation). The case of people calling
__builtin_memcmp (or declaring memcmp themselves) without string.h
included probably isn't one it's important to optimize.
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2021-09-17 14:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 17:02 Noah Goldstein
2021-09-16 17:55 ` [libc-coord] " Chris Kennelly
2021-09-16 18:31 ` Noah Goldstein
2021-09-16 20:32 ` Chris Kennelly
2021-09-16 20:35 ` Joseph Myers
2021-09-16 20:55 ` enh
2021-09-17 7:43 ` Richard Biener
2021-09-17 8:08 ` Florian Weimer
2021-09-17 8:31 ` Richard Biener
2021-09-17 8:37 ` Florian Weimer
2021-09-17 9:30 ` Richard Biener
2021-09-17 17:40 ` Noah Goldstein
2021-09-17 9:12 ` Jakub Jelinek
2021-09-17 16:55 ` Martin Sebor
2021-09-17 14:19 ` Joseph Myers [this message]
2021-09-17 14:26 ` Florian Weimer
2021-09-21 19:53 ` Noah Goldstein
2021-09-22 17:46 ` Christoph Müllner
2021-09-22 18:15 ` Noah Goldstein
2021-09-16 21:27 ` James Y Knight
2021-09-16 21:42 ` Joseph Myers
2021-09-16 21:50 ` enh
2021-09-16 21:59 ` Noah Goldstein
2021-09-16 22:17 ` Chris Kennelly
2021-09-16 22:36 ` Joseph Myers
2021-09-16 23:24 ` Noah Goldstein
2021-09-18 1:36 ` James Y Knight
2021-10-26 22:47 ` Noah Goldstein
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=alpine.DEB.2.22.394.2109171415400.3813920@digraph.polyomino.org.uk \
--to=joseph@codesourcery.com \
--cc=gcc@gcc.gnu.org \
--cc=libc-alpha@sourceware.org \
--cc=libc-coord@lists.openwall.com \
--cc=richard.guenther@gmail.com \
/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).