From: Noah Goldstein <goldstein.w.n@gmail.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH v7] String: Add support for __memcmpeq() ABI on all targets
Date: Thu, 21 Oct 2021 15:01:12 -0500 [thread overview]
Message-ID: <CAFUsyfJH8CteF-qAvZgnv_8j+7WEpzXn4-A4Z0U16YL03jKXVQ@mail.gmail.com> (raw)
In-Reply-To: <8ee11473-cdfd-3dbe-47a1-dffddc996b34@linaro.org>
On Thu, Oct 21, 2021 at 2:33 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 29/09/2021 12:17, Noah Goldstein via Libc-alpha wrote:
> > No bug.
> >
> > This commit adds support for __memcmpeq() as a new ABI for all
> > targets. In this commit __memcmpeq() is implemented only as an alias
> > to the corresponding targets memcmp() implementation. __memcmpeq() is
> > added as a new symbol starting with GLIBC_2.35 and defined in string.h
> > with comments explaining its behavior. Basic tests that it is callable
> > and works where added in string/tester.c
> >
> > As discussed in the proposal "Add new ABI '__memcmpeq()' to libc"
> > __memcmpeq() is essentially a reserved namespace for bcmp(). The means
> > is shares the same specifications as memcmp() except the return value
> > for non-equal byte sequences is any non-zero value. This is less
> > strict than memcmp()'s return value specification and can be better
> > optimized when a boolean return is all that is needed.
> >
> > __memcmpeq() is meant to only be called by compilers if they can prove
> > that the return value of a memcmp() call is only used for its boolean
> > value.
> >
>
> Should we export memcmpeq() as a GNU extension as well?
>
> > All tests in string/tester.c passed. As well build succeeds on
> > x86_64-linux-gnu target.
>
> This patch requires a NEWS entry for the new symbol and most likely
> a manual entry to describe its semantic.
My understanding is that since we are only exporting this symbol for
compiler use (to optimize boolean use of 'memcmp()') we weren't
planning to add a manual entry.
>
> I also think we should model a new testing based on test-memcmp.c
> to check for multiple alignments and random inputs.
In this patch __memcmpeq is always just memcmp which is tested.
In my followup patch (once this one gets through) to add separate
implementations for x86_64 I add tests. Would it be better to include
those tests in this patchset?
next prev parent reply other threads:[~2021-10-21 20:01 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-27 20:38 [PATCH v1] " Noah Goldstein
2021-09-27 20:43 ` Joseph Myers
2021-09-27 21:06 ` Noah Goldstein
2021-09-27 21:06 ` [PATCH v2] " Noah Goldstein
2021-09-27 21:52 ` Joseph Myers
2021-09-28 1:24 ` Noah Goldstein
2021-09-28 1:24 ` [PATCH v3] " Noah Goldstein
2021-09-28 8:15 ` Andreas Schwab
2021-09-28 16:47 ` Noah Goldstein
2021-09-28 8:40 ` Florian Weimer
2021-09-28 16:47 ` Noah Goldstein
2021-09-28 16:51 ` Florian Weimer
2021-09-28 16:46 ` [PATCH v4] " Noah Goldstein
2021-09-28 16:50 ` [PATCH v5] " Noah Goldstein
2021-09-28 16:53 ` [PATCH v6] " Noah Goldstein
2021-09-29 8:36 ` Florian Weimer
2021-09-29 15:17 ` Noah Goldstein
2021-09-29 8:52 ` Andreas Schwab
2021-09-29 9:18 ` Florian Weimer
2021-09-29 9:31 ` Andreas Schwab
2021-09-29 9:44 ` Florian Weimer
2021-09-28 16:57 ` [PATCH v1] " Noah Goldstein
2021-09-29 15:17 ` [PATCH v7] " Noah Goldstein
2021-09-30 19:31 ` Noah Goldstein
2021-10-11 2:33 ` Noah Goldstein
2021-10-18 14:47 ` Noah Goldstein
2021-10-21 19:28 ` H.J. Lu
2021-10-21 19:58 ` Noah Goldstein
2021-10-21 20:00 ` H.J. Lu
2021-10-21 21:04 ` Noah Goldstein
2021-10-21 20:02 ` Adhemerval Zanella
2021-10-21 20:23 ` Noah Goldstein
2021-10-21 20:26 ` Adhemerval Zanella
2021-10-21 19:33 ` Adhemerval Zanella
2021-10-21 20:01 ` Noah Goldstein [this message]
2021-10-21 20:06 ` Adhemerval Zanella
2021-10-21 21:18 ` Florian Weimer
2021-10-21 20:07 ` H.J. Lu
2021-10-21 20:11 ` Noah Goldstein
2021-10-21 22:38 ` [PATCH v8 1/3] " Noah Goldstein
2021-10-21 22:38 ` [PATCH v8 2/3] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-21 22:52 ` H.J. Lu
2021-10-21 23:08 ` Joseph Myers
2021-10-21 23:10 ` H.J. Lu
2021-10-21 23:14 ` Joseph Myers
2021-10-21 23:39 ` Noah Goldstein
2021-10-21 23:45 ` Noah Goldstein
2021-10-22 0:19 ` Joseph Myers
2021-10-22 0:40 ` H.J. Lu
2021-10-25 16:41 ` Joseph Myers
2021-10-22 0:18 ` Joseph Myers
2021-10-21 22:38 ` [PATCH v8 3/3] String: Add tests for __memcmpeq Noah Goldstein
2021-10-21 22:57 ` H.J. Lu
2021-10-21 23:47 ` Noah Goldstein
2021-10-22 0:41 ` H.J. Lu
2021-10-22 1:01 ` Noah Goldstein
2021-10-21 22:50 ` [PATCH v8 1/3] String: Add support for __memcmpeq() ABI on all targets H.J. Lu
2021-10-21 23:42 ` Noah Goldstein
2021-10-22 2:38 ` H.J. Lu
2021-10-22 4:04 ` Noah Goldstein
2021-10-22 5:49 ` [PATCH v9 " Noah Goldstein
2021-10-22 12:38 ` H.J. Lu
2021-10-22 16:07 ` Noah Goldstein
2021-10-22 17:19 ` Noah Goldstein
2021-10-22 17:40 ` Noah Goldstein
2021-10-22 17:44 ` H.J. Lu
2021-10-22 18:09 ` Noah Goldstein
2021-10-22 18:33 ` H.J. Lu
2021-10-22 5:49 ` [PATCH v9 2/3] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-22 12:44 ` H.J. Lu
2021-10-22 5:49 ` [PATCH v9 3/3] String: Add tests for __memcmpeq Noah Goldstein
2021-10-22 12:42 ` H.J. Lu
2021-10-22 16:06 ` [PATCH v10 1/4] String: Add support for __memcmpeq() ABI on all targets Noah Goldstein
2021-10-22 16:06 ` [PATCH v10 2/4] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-22 16:06 ` [PATCH v10 3/4] String: Add tests for __memcmpeq Noah Goldstein
2021-10-22 16:06 ` [PATCH v10 4/4] NEWS: Add item " Noah Goldstein
2021-10-22 16:12 ` H.J. Lu
2021-10-22 16:12 ` [PATCH v10 1/4] String: Add support for __memcmpeq() ABI on all targets H.J. Lu
2021-10-22 16:18 ` Noah Goldstein
2021-10-22 18:37 ` [PATCH v11 " Noah Goldstein
2021-10-22 18:37 ` [PATCH v11 2/4] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-22 18:37 ` [PATCH v11 3/4] String: Add tests for __memcmpeq Noah Goldstein
2021-10-22 18:37 ` [PATCH v11 4/4] NEWS: Add item " Noah Goldstein
2021-10-22 19:46 ` [PATCH v12 1/4] String: Add support for __memcmpeq() ABI on all targets Noah Goldstein
2021-10-22 19:46 ` [PATCH v12 2/4] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-22 19:46 ` [PATCH v12 3/4] String: Add tests for __memcmpeq Noah Goldstein
2021-10-22 19:46 ` [PATCH v12 4/4] NEWS: Add item " Noah Goldstein
2021-10-22 20:28 ` [PATCH v12 1/4] String: Add support for __memcmpeq() ABI on all targets H.J. Lu
2021-10-22 20:33 ` Noah Goldstein
2021-10-22 20:45 ` H.J. Lu
2021-10-22 21:24 ` Noah Goldstein
2021-10-22 21:23 ` [PATCH v13 " Noah Goldstein
2021-10-22 21:23 ` [PATCH v13 2/4] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-22 21:23 ` [PATCH v13 3/4] String: Add tests for __memcmpeq Noah Goldstein
2021-10-22 21:23 ` [PATCH v13 4/4] NEWS: Add item " Noah Goldstein
2021-10-23 23:23 ` [PATCH v13 1/4] String: Add support for __memcmpeq() ABI on all targets Noah Goldstein
2021-10-23 23:24 ` [PATCH v14 " Noah Goldstein
2021-10-23 23:24 ` [PATCH v14 2/4] String: Add hidden defs for __memcmpeq() to enable internal usage Noah Goldstein
2021-10-26 18:56 ` H.J. Lu
2021-10-23 23:24 ` [PATCH v14 3/4] String: Add tests for __memcmpeq Noah Goldstein
2021-10-26 18:57 ` H.J. Lu
2021-10-23 23:24 ` [PATCH v14 4/4] NEWS: Add item " Noah Goldstein
2021-10-26 18:58 ` H.J. Lu
2021-10-25 2:45 ` [PATCH v14 1/4] String: Add support for __memcmpeq() ABI on all targets Noah Goldstein
2021-10-26 18:55 ` H.J. Lu
2021-10-26 22:29 ` 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=CAFUsyfJH8CteF-qAvZgnv_8j+7WEpzXn4-A4Z0U16YL03jKXVQ@mail.gmail.com \
--to=goldstein.w.n@gmail.com \
--cc=adhemerval.zanella@linaro.org \
--cc=libc-alpha@sourceware.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).