From: Aurelien Jarno <aurelien@aurel32.net>
To: Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH] arm: Enable USE_ATOMIC_COMPILER_BUILTINS (BZ #24774)
Date: Fri, 7 Oct 2022 20:40:17 +0200 [thread overview]
Message-ID: <Y0BykcYbBWLpkHMJ@aurel32.net> (raw)
In-Reply-To: <20210929191430.884057-1-adhemerval.zanella@linaro.org>
On 2021-09-29 16:14, Adhemerval Zanella via Libc-alpha wrote:
> As per other architectures. I have checked on a armv8 hardware with
> the following configurations:
>
> arm-linux-gnueabihf (gcc built with --with-float=hard --with-cpu=arm926ej-s)
> armv5-linux-gnueabihf (-march=armv5te -mfpu=vfpv3)
> armv7-linux-gnueabihf (-march=armv7-a -mfpu=vfpv3)
> armv7-thumb-linux-gnueabihf (-march=armv7-a -mfpu=vfpv3 -mthumb)
> armv7-neon-linux-gnueabihf (-march=armv7-a -mfpu=neon)
> armv7-neonhard-linux-gnueabihf (-march=armv7-a -mfpu=neon -mfloat-abi=hard)
>
> Without any regression.
>
> I haven't dig into the code, but since Linux atomic-machine.h handle
> pre-ARMv6 and ARMv6 I expect the compiler might have some small room
> to optimize.
>
> The code size also improves is most of the configurations:
>
> * master
>
> text data bss dec hex filename
> 1727801 9720 37928 1775449 1b1759 arm-linux-gnueabihf/libc.so
> 1691729 9720 37928 1739377 1a8a71 arm-linux-gnueabihf-armv7-disable-multi-arch/libc.so
> 1725509 9720 37928 1773157 1b0e65 armv5-linux-gnueabihf/libc.so
> 1700757 9720 37928 1748405 1aadb5 armv6-linux-gnueabihf/libc.so
> 1698973 9720 37928 1746621 1aa6bd armv6t2-linux-gnueabihf/libc.so
> 1695481 9752 37928 1743161 1a9939 armv7-linux-gnueabihf/libc.so
> 1692917 9744 37928 1740589 1a8f2d armv7-neonhard-linux-gnueabihf/libc.so
> 1692917 9744 37928 1740589 1a8f2d armv7-neon-linux-gnueabihf/libc.so
> 1225353 9752 37928 1273033 136cc9 armv7-thumb-linux-gnueabihf/libc.so
>
> * patched
>
> text data bss dec hex filename
> 1726805 9720 37928 1774453 1b1375 arm-linux-gnueabihf/libc.so
> 1689321 9720 37928 1736969 1a8109 arm-linux-gnueabihf-armv7-disable-multi-arch/libc.so
> 1724433 9720 37928 1772081 1b0a31 armv5-linux-gnueabihf/libc.so
> 1698301 9720 37928 1745949 1aa41d armv6-linux-gnueabihf/libc.so
> 1696525 9720 37928 1744173 1a9d2d armv6t2-linux-gnueabihf/libc.so
> 1693009 9752 37928 1740689 1a8f91 armv7-linux-gnueabihf/libc.so
> 1690493 9744 37928 1738165 1a85b5 armv7-neonhard-linux-gnueabihf/libc.so
> 1690493 9744 37928 1738165 1a85b5 armv7-neon-linux-gnueabihf/libc.so
> 1223837 9752 37928 1271517 1366dd armv7-thumb-linux-gnueabihf/libc.so
>
> The idea is eventually move all architectures to use compiler builtins.
> ---
> sysdeps/arm/atomic-machine.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sysdeps/arm/atomic-machine.h b/sysdeps/arm/atomic-machine.h
> index 7928ff29d8..0275fcd2f7 100644
> --- a/sysdeps/arm/atomic-machine.h
> +++ b/sysdeps/arm/atomic-machine.h
> @@ -34,7 +34,7 @@ typedef intmax_t atomic_max_t;
> typedef uintmax_t uatomic_max_t;
>
> #define __HAVE_64B_ATOMICS 0
> -#define USE_ATOMIC_COMPILER_BUILTINS 0
> +#define USE_ATOMIC_COMPILER_BUILTINS 1
> #define ATOMIC_EXCHANGE_USES_CAS 1
>
> void __arm_link_error (void);
> --
I have just found your patch after I stumbled on BZ #24774. I confirm it
fixes this bug and also the flaky nptl/tst-rwlock9 test on arm. I did
not find any regression on the testsuite on Debian armel
(armv5-linux-gnueabi) and Debian armhf (armv7-linux-gnueabihf), using
GCC 11.
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
prev parent reply other threads:[~2022-10-07 18:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 19:14 Adhemerval Zanella
2022-01-19 12:49 ` Adhemerval Zanella
2022-10-07 18:40 ` Aurelien Jarno [this message]
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=Y0BykcYbBWLpkHMJ@aurel32.net \
--to=aurelien@aurel32.net \
--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).