[flac-dev] Questions about libFLAC and SSE/SSE2/...

[Erik de Castro Lopo]

lvqcl.mail wrote:

> Erik de Castro Lopo wrote:
> 
> > lvqcl.mail wrote:
> >> now. Removing OS check will greatly simplify src/libFLAC/cpu.c.
> >
> > That makes sense.
> 
> Should I post a patch that removes OS check and keeps only CPU check?

Yes that would be appreciated.

> >> 2.
> >> "configure" build system adds -msse2 option by default. It means that
> >> x86 (32-bit) library won't work on older, non-SSE2 processors. So if
> 
> > It does that depending on the architecture. Since Debian won't be  
> > supporting
> > i386 for the next release, I wonder how important that is.
> 
> As far as I understand, Debian 9.0 Stretch will support i386/x86
> _architecture_, it just won't support 386/486/586 _processors_.
> It will work on i686+ CPUs, and some of them (Pentium Pro, II, III,
> Athlon, Athlon XP) don't support SSE2.

I don't think this change should be made for this upcoming release.

Happy to have it after.

> >> FreeBSD just comments out this option:
> >> <https://svnweb.freebsd.org/ports/head/audio/flac/files/patch-configure?view=markup#l28>
> >>
> >> Maybe it makes sense to remove this option?
> >
> > Without knowing why FreeBSD disabled it, I'd prefer not to change it.
> 
> Probably because they want to build libFLAC so that it supports older
> processors?

So why disable it for all the CPUs that do support SSE?

> >> 3.
> >> What's the intended meaning of --enable-sse / --disable-sse options?
> >> What should they do/enable/disable?
> >
> > I really could not tell you without reading configure.ac and the code.
> 
> Actually I don't want to know its current meaning, I can figure it out
> myself. I want to know what it _should_ do, ideally...

Well I actually don't think it should ba c onfigure option at all, but a
run time option. Again, that is not something that should changes for this
release.

Erik
-- 
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Erik de Castro Lopo
http://www.mega-nerd.com/