Re: [PATCH 2/2] gnu: icecat: Use libjpeg-turbo instead of bundled libjpeg.

[Tobias Geerinckx-Rice <me@tobias.gr>]

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Andreas, Leo,

Thanks for the feedback!

On 27/11/16 22:41, Leo Famulari wrote:
> I'm not sure, but the comment seems to indicate that we don't want to
> use it:
> 
> ;; According to
> ;; http://sourceforge.net/projects/libjpeg-turbo/ ,
> ;; "libjpeg-turbo is a derivative of libjpeg that
> ;; uses MMX, SSE, SSE2, and NEON SIMD instructions
> ;; to accelerate baseline JPEG compression/
> ;; decompression", so we had better not use it

There seems to be some misunderstanding here. Sorry if it wasn't clear:
this (libjpeg-turbo) was *already* bundled and used by icecat, as the
‘media/libjpeg’ (sic) that this patch removes. You'll find the same SIMD
code there. For the quote above is missing:

> ;; Fails with "libjpeg-turbo JCS_EXTENSIONS required".

Translation: icecat wouldn't build with Guix's ‘libjpeg’ even if we'd
want that.

And we don't. This isn't some dodgy go-faster fork of IJG's ‘real’
libjpeg. It's intended as a sane alternative to the IJG library, albeit
one that doesn't implement every recent extension. It detects CPU
features at runtime — although they're the status quo now, as Andreas
notes — and falls back to other algorithms that might still be faster.

Dang it. I thought I wrote good (description)s. :-(

Kind regards,

T G-R-turbo


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