nir/algebraic: Optimize zero comparisons of umax or umin

I observered some of the existing patterns stopped being applied after
some of the ult-to-ieq optimizations in !33498. It turns out that these
patterns occur even without those changes.

shader-db:

All Intel platforms had similar results. (Lunar Lake shown)
total instructions in shared programs: 16973339 -> 16973331 (<.01%)
instructions in affected programs: 7977 -> 7969 (-0.10%)
helped: 2 / HURT: 0

total cycles in shared programs: 915620938 -> 915620774 (<.01%)
cycles in affected programs: 136022 -> 135858 (-0.12%)
helped: 2 / HURT: 0

fossil-db:

Lunar Lake
Totals:
Instrs: 209748173 -> 209748011 (-0.00%); split: -0.00%, +0.00%
Cycle count: 30514361348 -> 30514920286 (+0.00%); split: -0.00%, +0.00%
Spill count: 511813 -> 511808 (-0.00%)
Fill count: 622537 -> 622533 (-0.00%)
Max live registers: 65477033 -> 65477183 (+0.00%); split: -0.00%, +0.00%
Non SSA regs after NIR: 237334728 -> 237334726 (-0.00%); split: -0.00%, +0.00%

Totals from 26 (0.00% of 706651) affected shaders:
Instrs: 332073 -> 331911 (-0.05%); split: -0.05%, +0.00%
Cycle count: 959758560 -> 960317498 (+0.06%); split: -0.03%, +0.09%
Spill count: 10293 -> 10288 (-0.05%)
Fill count: 23784 -> 23780 (-0.02%)
Max live registers: 9682 -> 9832 (+1.55%); split: -0.08%, +1.63%
Non SSA regs after NIR: 232135 -> 232133 (-0.00%); split: -0.03%, +0.03%

Meteor Lake and DG2 had similar results. (Meteor Lake shown)
Totals:
Instrs: 233538532 -> 233536113 (-0.00%); split: -0.00%, +0.00%
Cycle count: 24428142259 -> 24426705655 (-0.01%); split: -0.01%, +0.00%
Spill count: 513128 -> 512923 (-0.04%)
Fill count: 557329 -> 557108 (-0.04%)
Max live registers: 42129806 -> 42129881 (+0.00%); split: -0.00%, +0.00%
Non SSA regs after NIR: 256711720 -> 256711718 (-0.00%); split: -0.00%, +0.00%

Totals from 26 (0.00% of 805759) affected shaders:
Instrs: 325629 -> 323210 (-0.74%); split: -0.74%, +0.00%
Cycle count: 893896782 -> 892460178 (-0.16%); split: -0.21%, +0.05%
Spill count: 10467 -> 10262 (-1.96%)
Fill count: 24291 -> 24070 (-0.91%)
Max live registers: 4946 -> 5021 (+1.52%); split: -0.08%, +1.60%
Non SSA regs after NIR: 232980 -> 232978 (-0.00%); split: -0.03%, +0.03%

Tiger Lake, Ice Lake, and Skylake had similar results. (Tiger Lake shown)
Totals:
Instrs: 237289818 -> 237289714 (-0.00%); split: -0.00%, +0.00%
Cycle count: 22959586058 -> 22960049302 (+0.00%); split: -0.00%, +0.00%
Max live registers: 42182257 -> 42182337 (+0.00%)
Non SSA regs after NIR: 255579974 -> 255579970 (-0.00%); split: -0.00%, +0.00%

Totals from 23 (0.00% of 802019) affected shaders:
Instrs: 27051 -> 26947 (-0.38%); split: -0.39%, +0.01%
Cycle count: 10545917 -> 11009161 (+4.39%); split: -0.09%, +4.49%
Max live registers: 2198 -> 2278 (+3.64%)
Non SSA regs after NIR: 31741 -> 31737 (-0.01%); split: -0.20%, +0.19%

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33648>

src/compiler/nir/nir_opt_algebraic.py

@@ -1368,6 +1368,14 @@ optimizations.extend([
    (('uge', '#a', ('umax', '#b', c)), ('iand', ('uge', a, b), ('uge', a, c))),
    (('uge', ('umin', '#a', b), '#c'), ('iand', ('uge', a, c), ('uge', b, c))),
 
+   # These follow from the preceeding uge and ult patterns if various patterns
+   # like uge(0, a) or ult(a, 1) are replaced with ieq or ine comparisons with
+   # zero.
+   (('ieq', ('umin', '#a', b), 0), ('ior', ('ieq', a, 0), ('ieq', b, 0))),
+   (('ine', ('umax', '#a', b), 0), ('ior', ('ine', a, 0), ('ine', b, 0))),
+   (('ieq', ('umax', '#a', b), 0), ('iand', ('ieq', a, 0), ('ieq', b, 0))),
+   (('ine', ('umin', '#a', b), 0), ('iand', ('ine', a, 0), ('ine', b, 0))),
+
    # Thanks to sign extension, the ishr(a, b) is negative if and only if a is
    # negative.
    (('bcsel', ('ilt', a, 0), ('ineg', ('ishr', a, b)), ('ishr', a, b)),