Right now we had two methods that tries to optimize the nir shader,
nir_optimize and st_nir_opts. The latter is being used when we are
linking, but again, it has basically the same purpose that
nir_optimize.
So this commit adds more lowerings to nir_optimize_nir, add some extra
comments on the method, and replaces st_nir_opts with nir_optimize.
Ideally we would like to just use the already existing
v3d_optimize_nir that we have at the backend But:
* Using it leads to some regressions on Vulkan CTS tests, due some
lowerings that are already there.
* We would need to move to the backend some additional
lowerings/optimizations that are used on the Vulkan
frontend. That would require to check that we are not getting any
regression or performance drop on OpenGL
So for now we are keeping a Vulkan specific nir_optimize method.
Additionally this fixes the following test:
dEQP-VK.graphicsfuzz.cov-loop-condition-clamp-vec-of-ones
Shaderdb stats, using some well known Vulkan apps (ue4 demos, Quake3e,
etc):
total instructions in shared programs: 124974 -> 125108 (0.11%)
instructions in affected programs: 50328 -> 50462 (0.27%)
helped: 4
HURT: 79
total uniforms in shared programs: 19019 -> 19020 (<.01%)
uniforms in affected programs: 60 -> 61 (1.67%)
helped: 0
HURT: 1
total max-temps in shared programs: 13438 -> 13444 (0.04%)
max-temps in affected programs: 85 -> 91 (7.06%)
helped: 0
HURT: 2
total inst-and-stalls in shared programs: 125715 -> 125849 (0.11%)
inst-and-stalls in affected programs: 50429 -> 50563 (0.27%)
helped: 4
HURT: 79
total nops in shared programs: 8203 -> 8204 (0.01%)
nops in affected programs: 732 -> 733 (0.14%)
helped: 7
HURT: 9
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16986>
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