[Mesa-dev] [PATCH 06/21] etnaviv: nir: hardwire position location

[Philipp Zabel]

On Tue, 2018-06-05 at 11:50 -0400, Rob Clark wrote:
> On Tue, Jun 5, 2018 at 10:38 AM, Philipp Zabel <p.zabel at pengutronix.de> wrote:
> > The temporary input/output register 0 is reserved for position in the
> > fragment shader. Hardwire it to 0 and start other input/output variables
> > at 1. The intrinsic input load and output store base corresponds to the
> > temporary register number.
> 
> I didn't look at this very closely, but at RA time you can pre-color
> (pre-assign) specific registers, see ra_set_node_reg().. not sure if
> this would be a better approach.  I do this for a few frag shader
> registers, mostly because at the time I hadn't found the cmdstream
> register/bitfield to configure it to something other than r0.x..

Yes, thank you. We already pre-color, but with the output of this pass.
I'll have a look into whether this can be simplified by doing the pre-
color first and then afterwards fixing up the load/store intrinsics.
We keep around the intrinsics as we use them to configure the shader
inputs/outputs later.

regards
Philipp