From: "Rémi Denis-Courmont" <remi@remlab.net>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH] lavu/arm: remove GCC 4.6- stuff
Date: Sat, 08 Jun 2024 09:15:11 +0300
Message-ID: <2053795.EyUWCETuIM@basile.remlab.net> (raw)
In-Reply-To: <AS8P250MB07447D91031F1E9709F8E8138FFB2@AS8P250MB0744.EURP250.PROD.OUTLOOK.COM>
Le lauantaina 8. kesäkuuta 2024, 0.26.21 EEST Andreas Rheinhardt a écrit :
> (Also: IIRC Clang actually parses inline assembler and optimize it;
That sounds sketchy. While FFmpeg only uses inline assembler as intrinsic
ersatz, other projects can and definitely do use them for weirder stuff. That
will fail miserably if the compiler modifies the sequence.
The Linux kernel for instance pushes/pops sections or patches the byte
sequence at load time or even run time. Some code also assumes exact byte
offsets between instructions (not sure Linux specifically). So, AFAICT, the only
thing the compiler can sanely do is move, and maybe eliminate/replicate, the
entire assembler block.
--
レミ・デニ-クールモン
http://www.remlab.net/
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next prev parent reply other threads:[~2024-06-08 6:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-07 16:49 Rémi Denis-Courmont
2024-06-07 21:16 ` Sean McGovern
2024-06-07 21:26 ` Andreas Rheinhardt
2024-06-08 6:15 ` Rémi Denis-Courmont [this message]
2024-06-08 6:23 ` Andreas Rheinhardt
2024-06-08 6:43 ` Rémi Denis-Courmont
2024-06-08 13:41 ` Andreas Rheinhardt
2024-06-08 14:38 ` Rémi Denis-Courmont
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