[FFmpeg-devel] [PATCH] Make mmx2 dependent on mmx/ssse3 dependent on mmx2

[Måns Rullgård]

Loren Merritt <lorenm at u.washington.edu> writes:

> On Fri, 21 Mar 2008, M?ns Rullg?rd wrote:
>> Panagiotis Issaris <takis.issaris at uhasselt.be> writes:
>>>
>>> First of all, I'm not sure about this patch... The thing is, I had
>>> expected the configure script to disable mmx2 and ssse3 too when
>>> disabling mmx, which it currently doesn't do. But, that's just because
>>> I'm not aware of any machines implementing mmx2 but not mmx. Anyway,
>>> attached patch makes mmx2 dependent on mmx, likewise for ssse3 which
>>> becomes dependent on mmx2. So, with the attached patch --disable-mmx
>>> disables them all.
>>>
>>> Index: configure
>>> ===================================================================
>>> --- configure	(revision 12527)
>>> +++ configure	(working copy)
>>> @@ -782,8 +784,8 @@
>>>  iwmmxt_deps="armv4l"
>>>  mmi_deps="mips"
>>>  mmx_deps="x86"
>>> -mmx2_deps="x86"
>>> -ssse3_deps="x86"
>>> +mmx2_deps="x86 mmx"
>>> +ssse3_deps="x86 mmx2"
>>>  vis_deps="sparc"
>>>
>>>  # decoders / encoders
>>
>> I can imagine someone wishing to disable only mmx on an sse-capable
>> machine to save some space.  If you want an option to disable all
>> assembler optimisations, it should be called something else.
>
> In that case, you want an option that disables only those functions
> that have an sse replacement.

Good point.

> Also what about --disable-sse1, sse2, sse3? I though just mmx and
> ssse3 were ok because --disable-mmx disabled all x86 simd, and ssse3
> was needed because it's a recent addition so some toolchains don't
> support it yet. But if you care about exactly which sets to disable...

configure checks whether ssse3 can be compiled.  It can be disabled
simply because it uses the same template as all the other optional
arch-specific features.

-- 
M?ns Rullg?rd
mans at mansr.com