[Mesa-dev] [PATCH 2/3] st: Sweep NIR after linking phase to free held memory

Eric Anholt eric at anholt.net
Fri Jul 20 18:32:18 UTC 2018

Timothy Arceri <tarceri at itsqueeze.com> writes:

>> On 19.07.18 11:47, Timothy Arceri wrote:
>>> On 19/07/18 08:31, Eric Anholt wrote:
>>>> Danylo Piliaiev <danylo.piliaiev at gmail.com> writes:
>>>>> After optimization passes and many trasfromations most of memory
>>>> "transformations"
>>>>> NIR holds is a garbage which was being freed only after shader 
>>>>> deletion.
>>>> "is garbage"
>>>>> Freeing it at the end of linking will save memory which would be useful
>>>>> in case there are a lot of complex shaders being compiled.
>>>>> The common case for this issue is 32bit game running under Wine.
>>>>> The cost of the optimization is around ~3-5% of compilation speed
>>>>> with complex shaders.
>>>>> Signed-off-by: Danylo Piliaiev <danylo.piliaiev at globallogic.com>
>>>> This seems good, and I'm running it through the CTS now.
>>> The problem is this does the sweep too early. We still do lots of work 
>>> on NIR after this, I've thought about this a few times and it really 
>>> seems we should be able to call a driver specific function from the st 
>>> and pass it the IR so it can do what ever it wants (lowering opts etc) 
>>> and spits it back out. Once this is done we should then call sweep and 
>>> cache the IR.
>>> At the very least we should call sweep before we cache NIR rather than 
>>> where this patch places it.
>> I debugged mesa once more and cannot see where else memory is allocated 
>> for NIR after this sweep. Could you point it to me? After this sweep the 
>> memory NIR holds never grows. Later this NIR is cloned from and these 
>> cloned NIRs are being sweeped in other place.
> Ah yes you are right. We do clone it when creating variants I'd 
> forgotten about that. In that case please ignore my comment.

I've gone ahead and pushed this patch now.
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