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From: "Rémi Denis-Courmont" <remi@remlab.net>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH 4/4] lavu/riscv: use Zbb CLZ/CTZ/CLZW/CTZW at run-time
Date: Sat, 08 Jun 2024 21:17:08 +0300
Message-ID: <2767730.msZjcf25lr@basile.remlab.net> (raw)
In-Reply-To: <c3b1238c-54f3-4c27-aac6-7b41c8790ddc@lynne.ee>

Le lauantaina 8. kesäkuuta 2024, 21.01.08 EEST Lynne via ffmpeg-devel a écrit :
> >   #if HAVE_RV && !defined(__riscv_zbb)
> 
> Could you add a ./configure flag or a check for enabling non-dynamic Zbb?

That's defined by the compiler target architecture and/or CPU. Adding a 
configure flag wouldn't work since the compiler wouldn't know that it can use 
emit Zbb instructions for the corresponding built-ins.

And before you ask, to my knowledge, GCC exposes no ad-hoc `-m` flags. This has 
to be included in -march or -mcpu instead, e.g.:
CFLAGS="-march=rv64gc_zba_zbb"

-- 
雷米‧德尼-库尔蒙
http://www.remlab.net/



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      reply	other threads:[~2024-06-08 18:17 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-08 11:37 [FFmpeg-devel] [PATCH 1/4] riscv: probe for Zbb extension at load time Rémi Denis-Courmont
2024-06-08 11:37 ` [FFmpeg-devel] [PATCH 2/4] lavu/riscv: use Zbb REV8 at run-time Rémi Denis-Courmont
2024-06-08 11:37 ` [FFmpeg-devel] [PATCH 3/4] lavu/riscv: use Zbb CPOP/CPOPW " Rémi Denis-Courmont
2024-06-08 11:37 ` [FFmpeg-devel] [PATCH 4/4] lavu/riscv: use Zbb CLZ/CTZ/CLZW/CTZW " Rémi Denis-Courmont
2024-06-08 18:01   ` Lynne via ffmpeg-devel
2024-06-08 18:17     ` Rémi Denis-Courmont [this message]

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