nir_to_tgsi: TGSI register allocation
Replacement for !14158 (closed).
Allocating NIR registers ends up being required for drivers like r600 and
nv30, which don't do their own allocation (except in some cases on r600
where sb is used).
Rather than add a NIR register liveness impl
(https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14158), switch
from NIR-based liveness to just doing the same channel-based liveness
logic that the NIR registers needed at the TGSI level. The actual
liveness code here basically comes straight out of
brw_vec4_live_variables.cpp.
Since we do the liveness in TGSI now, it also means we don't need to be
careful about not reading SSA values from later TGSI instructions (which
may be useful for doing some greedy instruction in generating TGSI
instructions).
softpipe:
total temps in shared programs: 563136 -> 332833 (-40.90%)
temps in affected programs: 552348 -> 322045 (-41.70%)
i915g:
total instructions in shared programs: 400719 -> 380730 (-4.99%)
instructions in affected programs: 284760 -> 264771 (-7.02%)
total tex_indirect in shared programs: 12289 -> 12290 (<.01%)
tex_indirect in affected programs: 4 -> 5 (25.00%)
total temps in shared programs: 32172 -> 22086 (-31.35%)
temps in affected programs: 30647 -> 20561 (-32.91%)
LOST: 0
GAINED: 148
r300:
total instructions in shared programs: 1472463 -> 1459286 (-0.89%)
instructions in affected programs: 507009 -> 493832 (-2.60%)
total temps in shared programs: 212143 -> 201678 (-4.93%)
temps in affected programs: 78007 -> 67542 (-13.42%)
softpipe:
total temps in shared programs: 517071 -> 294387 (-43.07%)
temps in affected programs: 509324 -> 286640 (-43.72%)
Edited by Emma Anholt