From: Jesse DeGuire <jesse.a.deguire@gmail.com>
To: musl@lists.openwall.com, "Érico Nogueira" <ericonr@disroot.org>
Subject: Re: [musl] [PATCH] shorten __aeabi_memset by one instruction
Date: Wed, 21 Apr 2021 08:32:54 -0400 [thread overview]
Message-ID: <CALqyXLiLn7uKTVHO_BPeWdDVjoMZ5-=vemfUZ-7Zwik=BvXVAQ@mail.gmail.com> (raw)
In-Reply-To: <20210421082458.GI2799122@port70.net>
On Wed, Apr 21, 2021 at 4:25 AM Szabolcs Nagy <nsz@port70.net> wrote:
>
> * Érico Nogueira <ericonr@disroot.org> [2021-04-20 16:15:19 -0300]:
> > when building for armhf, this makes libc.so text smaller by 4 bytes:
> > 606619 to 606615
> > ---
> > src/string/arm/__aeabi_memset.s | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/src/string/arm/__aeabi_memset.s b/src/string/arm/__aeabi_memset.s
> > index f9f60583..980774e8 100644
> > --- a/src/string/arm/__aeabi_memset.s
> > +++ b/src/string/arm/__aeabi_memset.s
> > @@ -24,8 +24,7 @@ __aeabi_memset:
> > cmp r1, #0
> > beq 2f
> > adds r1, r0, r1
> > -1: strb r2, [r0]
> > - adds r0, r0, #1
> > +1: strb r2, [r0], #1
>
> this is not available before armv7 as thumb instruction (and it
> has 32bit thumb encoding, so you replace two 16bit instructions
> with a 32bit one.)
>
> normally this asm is compiled in arm mode even if your toolchain
> defaults to thumb (i'm not sure why), but if you select a cpu or
> arch that only supports thumb then the assembler will try to use
> thumb and fail e.g. on -march=armv6-m (but i'm not sure if musl
> supports that compilation mode throughout)
>
Musl currently does not build on Thumb1-only devices (Armv6-m and
Armv8-m.base). I submitted a patch some time ago to allow it to build,
though life and other obstacles have made me much too slow in actually
getting a functioning toolchain together to test it properly.
> > cmp r1, r0
> > bne 1b
> > 2: bx lr
> > --
> > 2.31.1
next prev parent reply other threads:[~2021-04-21 12:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 19:15 [musl] [PATCH] add pthread_getname_np function Érico Nogueira
2021-04-20 19:15 ` [musl] [PATCH v2] define __STDC_UTF_{16,32}__ macros Érico Nogueira
2021-04-20 19:15 ` [musl] [PATCH] extend gethostid beyond a stub Érico Nogueira
2021-04-20 19:15 ` [musl] [PATCH] remove unnecessary cast for map_library return Érico Nogueira
2021-04-20 19:15 ` [musl] [PATCH] shorten __aeabi_memset by one instruction Érico Nogueira
2021-04-21 8:24 ` Szabolcs Nagy
2021-04-21 12:32 ` Jesse DeGuire [this message]
2021-04-21 17:38 ` Rich Felker
2021-04-21 19:02 ` Érico Nogueira
2021-05-20 13:04 ` [musl] [PATCH] add pthread_getname_np function Stefan Agner
2021-07-09 8:06 ` Michael Forney
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='CALqyXLiLn7uKTVHO_BPeWdDVjoMZ5-=vemfUZ-7Zwik=BvXVAQ@mail.gmail.com' \
--to=jesse.a.deguire@gmail.com \
--cc=ericonr@disroot.org \
--cc=musl@lists.openwall.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.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
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 NNTP newsgroup(s).