From: DJ Delorie via Libc-alpha <libc-alpha@sourceware.org>
To: Noah Goldstein <goldstein.w.n@gmail.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH 5/5] x86_64: Add evex optimized bcmp implementation in bcmp-evex.S
Date: Tue, 14 Sep 2021 00:21:39 -0400 [thread overview]
Message-ID: <xnpmtb4wj0.fsf@greed.delorie.com> (raw)
In-Reply-To: <CAFUsyfLM_M63uykH0-mB=yy+5=JjM0SHKg-Cj2qDE7g_JNJMdQ@mail.gmail.com>
Noah Goldstein <goldstein.w.n@gmail.com> writes:
> So I think I was able to fix the build by making a new file in glibc/string/bcmp.c
> and just having bcmp call memcmp
>
> Is there another/better way to fix the build? I don't think it's really fair that every
> arch other than x86_64 should have to pay an extra function call cost to use bcmp.
There are at least three...
First, note that bcmp is a weak alias to memcmp already - see
strings/memcmp.c - which avoids the extra call you mention.
So, you could either move that weak alias into bcmp.c, or arrange for
bcmp.c to not be needed by the Makefile for non-x86_64 platforms.
Lastly, an empty bcmp.c wouldn't override the alias in memcmp.c. I
think the first would be easiest, although it may be tricky to compile a
source file that seems to do "nothing". Also, I suspect liberal use of
comments would be beneficial for the unsuspecting reader ;-)
Alternately, you could change your patch to provide alternate versions
of memcmp() instead of bcmp(), as glibc's bcmp *is* memcmp. This is
what other arches (and x86_64) do:
$ find . -name 'memcmp*' -print
next prev parent reply other threads:[~2021-09-14 4:22 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 23:05 [PATCH 1/5] x86_64: Add support for bcmp using sse2, sse4_1, avx2, and evex Noah Goldstein via Libc-alpha
2021-09-13 23:05 ` [PATCH 2/5] x86_64: Add sse2 optimized bcmp implementation in memcmp.S Noah Goldstein via Libc-alpha
2021-09-13 23:05 ` [PATCH 3/5] x86_64: Add sse4_1 optimized bcmp implementation in memcmp-sse4.S Noah Goldstein via Libc-alpha
2021-09-13 23:05 ` [PATCH 4/5] x86_64: Add avx2 optimized bcmp implementation in bcmp-avx2.S Noah Goldstein via Libc-alpha
2021-09-13 23:05 ` [PATCH 5/5] x86_64: Add evex optimized bcmp implementation in bcmp-evex.S Noah Goldstein via Libc-alpha
2021-09-14 1:18 ` Carlos O'Donell via Libc-alpha
2021-09-14 2:05 ` Noah Goldstein via Libc-alpha
2021-09-14 2:35 ` Carlos O'Donell via Libc-alpha
2021-09-14 2:55 ` DJ Delorie via Libc-alpha
2021-09-14 3:24 ` Noah Goldstein via Libc-alpha
2021-09-14 3:40 ` Noah Goldstein via Libc-alpha
2021-09-14 4:21 ` DJ Delorie via Libc-alpha [this message]
2021-09-14 5:29 ` Noah Goldstein via Libc-alpha
2021-09-14 5:42 ` DJ Delorie via Libc-alpha
2021-09-14 5:55 ` Noah Goldstein via Libc-alpha
2021-09-13 23:22 ` [PATCH 1/5] x86_64: Add support for bcmp using sse2, sse4_1, avx2, and evex Noah Goldstein via Libc-alpha
2021-09-14 6:30 ` [PATCH v2 " Noah Goldstein via Libc-alpha
2021-09-14 6:30 ` [PATCH v2 2/5] x86_64: Add sse2 optimized bcmp implementation in memcmp.S Noah Goldstein via Libc-alpha
2021-09-14 6:30 ` [PATCH v2 3/5] x86_64: Add sse4_1 optimized bcmp implementation in memcmp-sse4.S Noah Goldstein via Libc-alpha
2021-09-14 6:30 ` [PATCH v2 4/5] x86_64: Add avx2 optimized bcmp implementation in bcmp-avx2.S Noah Goldstein via Libc-alpha
2021-09-14 6:30 ` [PATCH v2 5/5] x86_64: Add evex optimized bcmp implementation in bcmp-evex.S Noah Goldstein via Libc-alpha
2021-09-14 14:40 ` [PATCH v2 1/5] x86_64: Add support for bcmp using sse2, sse4_1, avx2, and evex H.J. Lu via Libc-alpha
2021-09-14 19:23 ` Noah Goldstein via Libc-alpha
2021-09-14 20:30 ` Florian Weimer via Libc-alpha
2021-09-15 0:00 ` [PATCH " Joseph Myers
2021-09-15 13:37 ` Zack Weinberg via Libc-alpha
2021-09-15 14:01 ` Re: [PATCH 1/5] x86_64: Add support for bcmp using sse2, sse 4_1, " Florian Weimer via Libc-alpha
2021-09-15 18:06 ` Noah Goldstein via Libc-alpha
2021-09-15 18:30 ` Joseph Myers
2021-09-27 1:35 ` Noah Goldstein via Libc-alpha
2021-09-27 7:29 ` Florian Weimer via Libc-alpha
2021-09-27 16:49 ` Noah Goldstein via Libc-alpha
2021-09-27 16:54 ` Florian Weimer via Libc-alpha
2021-09-27 17:54 ` Noah Goldstein via Libc-alpha
2021-09-27 17:56 ` Florian Weimer via Libc-alpha
2021-09-27 18:05 ` Noah Goldstein via Libc-alpha
2021-09-27 18:10 ` Florian Weimer via Libc-alpha
2021-09-27 18:15 ` Noah Goldstein via Libc-alpha
2021-09-27 18:22 ` Florian Weimer via Libc-alpha
2021-09-27 18:34 ` Noah Goldstein via Libc-alpha
2021-09-27 18:56 ` Florian Weimer via Libc-alpha
2021-09-27 19:20 ` Noah Goldstein via Libc-alpha
2021-09-27 19:34 ` Florian Weimer via Libc-alpha
2021-09-27 19:43 ` Noah Goldstein via Libc-alpha
2021-09-27 19:59 ` Florian Weimer via Libc-alpha
2021-09-27 20:22 ` Noah Goldstein via Libc-alpha
2021-09-27 20:24 ` Florian Weimer via Libc-alpha
2021-09-27 20:38 ` Noah Goldstein via Libc-alpha
2021-09-28 0:07 ` Noah Goldstein via Libc-alpha
2021-09-27 17:42 ` Joseph Myers
2021-09-27 17:48 ` Noah Goldstein via Libc-alpha
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
List information: https://www.gnu.org/software/libc/involved.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=xnpmtb4wj0.fsf@greed.delorie.com \
--to=libc-alpha@sourceware.org \
--cc=dj@redhat.com \
--cc=goldstein.w.n@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).