[Mesa-dev] tgsi_set_exec_mask?

[Roland Scheidegger]

Am 21.03.2016 um 03:08 schrieb Dave Airlie:
> This appears to set some values into some temp register that we never
> read from or look at again,
> 
> should it be setting something that ExecMask gets set to at machine run time?
> 
> just noticed it while trying to work out the various mask for shader images.
> Dave.
> _______________________________________________


I'm not really sure. Maybe it was meant to be combined with ExecMask to
avoid unnecessary branches (so, if you run a vs but only have 1 vertex
left and not 4, and then have some if branch not including it, you'd not
need to run the branch). Albeit you can't skip everything at least with
fs, as you still need to be able to calculate derivatives, but just
skipping branches should be still ok. llvmpipe does something similar.

fwiw there's also tgsi_set_kill_mask() which isn't used neither (albeit
in this case, the mask is).

Roland