From: "Rémi Denis-Courmont" <remi@remlab.net>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] gcc: Remove auto-vectorization limitation.
Date: Sat, 24 May 2025 19:10:57 +0300
Message-ID: <3356719.44csPzL39Z@basile.remlab.net> (raw)
In-Reply-To: <09d91570-6c20-49a7-aada-ceb18d77c6c3@iscas.ac.cn>
Le torstaina 22. toukokuuta 2025, 9.32.18 Itä-Euroopan kesäaika Jiawei a écrit
:
> > The RISC-V autovectorised output looks like it has a warning "Odd
> > rotation angle" which is not present in the non-autovectorised output.
>
> I found this occured when using '-ffast-math' in RISC-V, also occur in
> -O3 -ffast-math -fno-tree-vectorize case(much slower due to the
> -ffast-math)，supplementary more comparison results here:
Unfortunately, the FFmpeg code is written with x87 semantics in mind. For
instance, the FFmpeg math macros work nicely on x86, but they would work much
better with fabs/fmax/fmin/fabsf/fmaxf/fminf on other platforms. I tried to fix
that with copious amount of _Generic(), but that lead to ICE...
So we are stuck between a rock and a hard place where we need fast math for
good perfs, but we need to turn it off for correct results.
--
ヅニ-クーモン・レミ
Hagalund ny stad, f.d. Finska republik Nylands
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next prev parent reply other threads:[~2025-05-24 16:11 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-21 6:17 Jiawei
2025-05-21 6:52 ` Nicolas George
2025-05-21 10:17 ` Jiawei
2025-05-21 18:21 ` Frank Plowman
2025-05-22 6:32 ` Jiawei
2025-05-24 1:46 ` Kieran Kunhya via ffmpeg-devel
2025-05-24 4:10 ` Jiawei
2025-05-24 16:10 ` Rémi Denis-Courmont [this message]
2025-05-25 21:37 ` Michael Niedermayer
2025-05-26 8:43 ` Rémi Denis-Courmont
2025-05-30 0:46 ` Michael Niedermayer
2025-05-30 6:58 ` Rémi Denis-Courmont
2025-05-31 13:39 ` Michael Niedermayer
2025-06-03 16:14 ` Niklas Haas
2025-06-04 11:13 ` Rémi Denis-Courmont
2025-05-21 7:46 ` Michael Niedermayer
2025-05-21 10:32 ` Jiawei
2025-05-21 11:09 ` Michael Niedermayer
2025-05-21 9:04 ` Zhao Zhili
2025-05-21 10:26 ` Jiawei
2025-05-21 10:33 ` Andreas Rheinhardt
2025-05-21 12:09 ` Martin Storsjö
2025-05-21 12:14 ` Andreas Rheinhardt
2025-05-21 12:22 ` Martin Storsjö
2025-05-21 18:12 ` softworkz .
2025-05-24 12:00 ` Rémi Denis-Courmont
2025-05-21 10:08 Jiawei
2025-05-21 10:14 Jiawei
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