From mboxrd@z Thu Jan 1 00:00:00 1970
Return-Path: <ffmpeg-devel-bounces@ffmpeg.org>
Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100])
by master.gitmailbox.com (Postfix) with ESMTPS id D48C04DA51
for <ffmpegdev@gitmailbox.com>; Fri, 28 Feb 2025 01:14:21 +0000 (UTC)
Received: from [127.0.1.1] (localhost [127.0.0.1])
by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 4A30F68DCC2;
Fri, 28 Feb 2025 03:14:18 +0200 (EET)
Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net
[217.70.183.198])
by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 8155768DA84
for <ffmpeg-devel@ffmpeg.org>; Fri, 28 Feb 2025 03:14:11 +0200 (EET)
Received: by mail.gandi.net (Postfix) with ESMTPSA id EFB4244213
for <ffmpeg-devel@ffmpeg.org>; Fri, 28 Feb 2025 01:14:10 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=niedermayer.cc;
s=gm1; t=1740705251;
h=from:from:reply-to:subject:subject:date:date:message-id:message-id:
to:to:cc:mime-version:mime-version:content-type:content-type:
in-reply-to:in-reply-to:references:references;
bh=w9REyuHT84oeX4nWWlS1Mb9OY1asNfuzIgRTo/MksYA=;
b=BNjJTVhm+n4sUjO6WzdIXg6Ggdf2hqm9rL9CJ3lu72dm9cYclJtOaV/idwFxp1WQ1dT340
C48hW2W79EYIk2R2BzUqdj2o980f/zK7SWkeEsVHJTkNXI1jrehVawG49cnjnxo9BzJKFg
B/w2fz3/ExjNLudqEQ1GgXwnReSdJA7m9ecvf3yzM6MfQRfcFyaWddF3ueOEgzXj94QM7F
wa0Z/3jTnh/wD1FPeer2KmQUfN3QykLP9G80Yb4LfOimyl4SEPmHDrncE2v1vFkuT9a7c8
lImd7kzx3Xrkl4BBo2FDwVEfMiAd3enG3CdwHl//Cqh7hyPhRCEj8Rp1xeOOGA==
Date: Fri, 28 Feb 2025 02:14:09 +0100
From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Message-ID: <20250228011409.GN4991@pb2>
References: <20250225213717.3373852-1-prka@google.com>
<20250226194437.121075-1-prka@google.com>
MIME-Version: 1.0
In-Reply-To: <20250226194437.121075-1-prka@google.com>
X-GND-State: clean
X-GND-Score: -90
X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdekledtfecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnegfrhhlucfvnfffucdluddtmdenucfjughrpeffhffvuffkfhggtggujgesghdtreertddtvdenucfhrhhomhepofhitghhrggvlhcupfhivgguvghrmhgrhigvrhcuoehmihgthhgrvghlsehnihgvuggvrhhmrgihvghrrdgttgeqnecuggftrfgrthhtvghrnhepueejieffkeegteethfekvdejheektdevfeevtddviedtvdekhfejvdefvdduueevnecuffhomhgrihhnpehthhgvghhrvggvnhhplhgrtggvrdhnvghtnecukfhppeeguddrieeirdeijedruddufeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeguddrieeirdeijedruddufedphhgvlhhopehlohgtrghlhhhoshhtpdhmrghilhhfrhhomhepmhhitghhrggvlhesnhhivgguvghrmhgrhigvrhdrtggtpdhnsggprhgtphhtthhopedupdhrtghpthhtohepfhhfmhhpvghgqdguvghvvghlsehffhhmphgvghdrohhrgh
X-GND-Sasl: michael@niedermayer.cc
Subject: Re: [FFmpeg-devel] [PATCH] Mark C globals with small code model
X-BeenThere: ffmpeg-devel@ffmpeg.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: FFmpeg development discussions and patches <ffmpeg-devel.ffmpeg.org>
List-Unsubscribe: <https://ffmpeg.org/mailman/options/ffmpeg-devel>,
<mailto:ffmpeg-devel-request@ffmpeg.org?subject=unsubscribe>
List-Archive: <https://ffmpeg.org/pipermail/ffmpeg-devel>
List-Post: <mailto:ffmpeg-devel@ffmpeg.org>
List-Help: <mailto:ffmpeg-devel-request@ffmpeg.org?subject=help>
List-Subscribe: <https://ffmpeg.org/mailman/listinfo/ffmpeg-devel>,
<mailto:ffmpeg-devel-request@ffmpeg.org?subject=subscribe>
Reply-To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Content-Type: multipart/mixed; boundary="===============2437127058204022145=="
Errors-To: ffmpeg-devel-bounces@ffmpeg.org
Sender: "ffmpeg-devel" <ffmpeg-devel-bounces@ffmpeg.org>
Archived-At: <https://master.gitmailbox.com/ffmpegdev/20250228011409.GN4991@pb2/>
List-Archive: <https://master.gitmailbox.com/ffmpegdev/>
List-Post: <mailto:ffmpegdev@gitmailbox.com>
--===============2437127058204022145==
Content-Type: multipart/signed; micalg=pgp-sha512;
protocol="application/pgp-signature"; boundary="hub17ppRPupoDoTD"
Content-Disposition: inline
--hub17ppRPupoDoTD
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
On Wed, Feb 26, 2025 at 07:44:37PM +0000, Pranav Kant via ffmpeg-devel wrot=
e:
> By default, all globals in C/C++ compiled by clang are allocated
> in non-large data sections. See [1] for background on code models.
> For PIC (Position independent code), this is fine as long as binary is
> small but as binary size increases, users maybe want to use medium/large
> code models (-mcmodel=3Dmedium) which moves data in to large sections.
> As data in these large sections cannot be accessed using PIC code
> anymore (as it may be too far away), compiler ends up using a different
> instruction sequence when building C/C++ code -- using GOT to access
> these globals (which can be relaxed by linker at link time if binary
> ends up being smaller). However, assembly files continue to access these
> globals defined in C/C++ files using older (and invalid instruction
> sequence). So, we mark all such globals with an attribute that forces
> them to be allocated in small sections allowing them to validly be
> accessed from the assembly code.
>=20
> This patch should not have any affect on builds that use small code
> model, which is the default mode.
>=20
> [1] https://eli.thegreenplace.net/2012/01/03/understanding-the-x64-code-m=
odels
>=20
> Signed-off-by: Pranav Kant <prka@google.com>
> ---
> libavcodec/ac3dsp.c | 2 ++
> libavcodec/cabac.c | 2 ++
> libavcodec/x86/constants.c | 8 ++++++++
> libavutil/attributes_internal.h | 15 +++++++++++++++
> 4 files changed, 27 insertions(+)
This produces many warnings:
CC libavcodec/svq1.o
In file included from libavcodec/svq1.h:40,
from libavcodec/svq1.c:35:
=2E/libavutil/attributes_internal.h:43:5: warning: "ARCH_X86_64" is not def=
ined, evaluates to 0 [-Wundef]
43 | #if ARCH_X86_64 && defined(__ELF__) && __has_attribute(model)
| ^~~~~~~~~~~
[...]
--=20
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
If you fake or manipulate statistics in a paper in physics you will never
get a job again.
If you fake or manipulate statistics in a paper in medicin you will get
a job for life at the pharma industry.
--hub17ppRPupoDoTD
Content-Type: application/pgp-signature; name="signature.asc"
-----BEGIN PGP SIGNATURE-----
iF0EABEKAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCZ8EN3gAKCRBhHseHBAsP
q+zoAKCB7iYjrXocqQI/3coYciFiNNw62wCfYx0ysQ8dU2MZTbwWd8Ko5WLwBKY=
=WTZG
-----END PGP SIGNATURE-----
--hub17ppRPupoDoTD--
--===============2437127058204022145==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
--===============2437127058204022145==--