[Mesa-dev] Adjust MIMG writemask to only the used components

[Christian König]

Am 03.04.2013 15:19, schrieb Michel Dänzer:
> On Mit, 2013-03-27 at 17:57 +0100, Christian König wrote:
>> the attached patches dynamically adjust the writemask of MIMG
>> instructions depending on the used components. Additional to that it
>> also adjust the register class of MIMG instruction so that we also
>> reduce register pressure.
> There's mainly one thing that isn't clear to me: My understanding from
> the ISA is that even if the instruction writemask operand has 'gaps',
> e.g. 0x9, the enabled components will always be written to consecutive
> VGPRs. So in this example, the instruction would write to two
> consecutive VGPRs, one for component 0/'x' and one for component 3/'w'
> of a four component vector. Is this handled correctly?
>

Yes your understanding is correct, and it is indeed handled correctly.

I just analyze the used register components to figure out the needed 
writemask and while doing so remember which instruction uses which 
component. So after updating the writemask I just change the index of 
the used component as well.

Christian.