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

[Måns Rullgård]

Panagiotis Issaris <takis.issaris at uhasselt.be> writes:

> M?ns Rullg?rd schreef:
>> Panagiotis Issaris <takis.issaris at uhasselt.be> writes:
>>
>>> Hi,
>>>
>>> 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.
>
> Yes, you're both right. How about something like the attached patch?
>
> Index: configure
> ===================================================================
> --- configure	(revision 12535)
> +++ configure	(working copy)
> @@ -119,6 +119,7 @@
>    echo "                           instruction selection, may crash on older CPUs)"
>    echo "  --enable-powerpc-perf    enable performance report on PPC"
>    echo "                           (requires enabling PMC)"
> +  echo "  --disable-simd           disable all SIMD usage"
>    echo "  --disable-mmx            disable MMX usage"
>    echo "  --disable-mmx2           disable MMX2 usage"
>    echo "  --disable-ssse3          disable SSSE3 usage"
> @@ -702,6 +703,7 @@
>      mmi
>      mmx
>      mmx2
> +    simd
>      ssse3
>      vis
>  '
> @@ -778,15 +780,15 @@
>  # code dependency declarations
>
>  # architecture extensions
> -altivec_deps="powerpc"
> +altivec_deps="powerpc simd"
>  armv5te_deps="armv4l"
>  armv6_deps="armv4l"
> -iwmmxt_deps="armv4l"
> +iwmmxt_deps="armv4l simd"
>  mmi_deps="mips"
> -mmx_deps="x86"
> -mmx2_deps="x86"
> -ssse3_deps="x86"
> -vis_deps="sparc"
> +mmx_deps="x86 simd"
> +mmx2_deps="x86 simd"
> +ssse3_deps="x86 simd"
> +vis_deps="sparc simd"

I don't think SIMD is the proper qualifier.  I see no reason why to
disable SIMD optimisations while keeping non-SIMD CPU-specific code
(e.g. armv5te).  Either way, armv6 and mmi (iirc) are also SIMD.

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