[Mesa-dev] [PATCH v2 08/13] mesa/format_utils: Add a general format conversion function

[Jason Ekstrand]

On Thu, Sep 11, 2014 at 3:53 PM, Dieter Nützel <Dieter at nuetzel-hh.de> wrote:

> Am 12.09.2014 00:31, schrieb Jason Ekstrand:
>
>  On Thu, Sep 11, 2014 at 2:55 PM, Dieter Nützel <Dieter at nuetzel-hh.de>
>> wrote:
>>
>>  Am 15.08.2014 04:50, schrieb Jason Ekstrand:
>>>
>>>  On Aug 14, 2014 7:13 PM, "Dieter Nützel" <Dieter at nuetzel-hh.de>
>>>> wrote:
>>>>
>>>>>
>>>>> Am 15.08.2014 02:36, schrieb Dave Airlie:
>>>>>
>>>>>  On 08/02/2014 02:11 PM, Jason Ekstrand wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Most format conversion operations required by GL can be
>>>>>>>>>
>>>>>>>> performed by
>>>>
>>>>> converting one channel at a time, shuffling the channels
>>>>>>>>>
>>>>>>>> around, and
>>>>
>>>>> optionally filling missing channels with zeros and ones.
>>>>>>>>>
>>>>>>>> This
>>>> adds a
>>>>
>>>>> function to do just that in a general, yet efficient, way.
>>>>>>>>>
>>>>>>>>> v2:
>>>>>>>>> * Add better comments including full docs for functions
>>>>>>>>> * Don't use __typeof__
>>>>>>>>> * Use inline helpers instead of writing out conversions
>>>>>>>>>
>>>>>>>> by
>>>> hand,
>>>>
>>>>> * Force full loop unrolling for better performance
>>>>>>>>>
>>>>>>>>>
>>>>>>
>>>>>> This file seems to anger gcc a lot.
>>>>>>
>>>>>> It seems to take upwards of a minute or two to compile here.
>>>>>>
>>>>>> gcc 4.8.3 on 32-bit x86.
>>>>>>
>>>>>> Dave.
>>>>>>
>>>>>
>>>>>
>>>>> For me (on our poor little Duron 1800/2 GB) it ran ~5
>>>>>
>>>> minutes...
>>>>
>>>>>
>>>>> gcc 4.8.1 on 32-bit x86.
>>>>>
>>>>
>>>> If we'd like, the way the macros are set up, it would be easy to
>>>> change it so that we do less unrolling in the cases where we are
>>>> actually doing substantial format conversion and wouldn't notice
>>>> the
>>>> extra logic quite as much. I'll play with it a bit tomorrow or
>>>> next
>>>> week and see how how much of a hit we would actually take if we
>>>> unrolled a little less in places.
>>>> --Jason Ekstrand
>>>>
>>>
>>> Ping.
>>>
>>> In a second it took 11+ minutes , here...
>>>
>>
>> 11 minutes! What system are you running?  and are you using -03 or
>> something?  Yes, we can do something to cut it down, but it will
>> probably require a configure flag; the question is what flag.
>>
>> --Jason
>>
>
> See above, the old children's system... ;-)
> -O2 -m32 -march=athlon-mp -mtune=athlon-mp -m3dnow -msse -mmmx
> -mfpmath=sse,387 -pipe
>
> Bad? - Worked for ages on AthlonMP....8-)
> Maybe it is bad on Duron (the MP thing, much smaller cache and better
> GCC), now.
>
> Dieter
>

Yeah, my recommendation would be hacking the macros to not unroll and keep
the patch locally.  If you've got a better idea as to how to organize the
code so the compiler likes it, I'm open as long as we don't loose
performance.
--Jason
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