Re: [FFmpeg-devel] [PATCH v5] gcc: Don't disable '-ftree-vectorize' if gcc version higher than 13.

From: "Martin Storsjö" <martin@martin.st>
To: Jiawei <jiawei@iscas.ac.cn>
Cc: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH v5] gcc: Don't disable '-ftree-vectorize' if gcc version higher than 13.
Date: Thu, 10 Jul 2025 14:35:10 +0300 (EEST)
Message-ID: <7634ba8e-7e76-a11b-98f-d7d5cb61eb1@martin.st> (raw)
In-Reply-To: <ec574b73-bf1d-4174-9e8f-617101a5820c@iscas.ac.cn>

On Thu, 10 Jul 2025, Jiawei wrote:

> Hi Martin,
>
> Is there any progress for this patch, should I resend it to the mailing list 
> again?

When I posted the updated version of the patch, the patchwork test runners 
noticed that this patch causes test failures on Loongarch. So modern 
versions of GCC still do have vectorization bugs, at least on some 
architectures.

I'm unsure if we should allow it everywhere, and just single out loongarch 
as a case where it is known broken, or if we should only let GCC enable it 
on the major architectures that we've tested.

In either case, we should isolate the compiler bugs on loongarch and 
report them, as well, so that they have a chance of getting the 
vectorization to work properly.

// Martin

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