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

[Michel Dänzer]

On Mit, 2013-04-03 at 15:38 +0200, Christian König wrote: 
> 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.

Excellent. Sounds and looks good to me then. 

-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer