intel/brw: Use nir_opt_generate_bfi

No shader-db changes on any Intel platform.

The "regression" in SEND messages occurs because a loop containing a
SEND is unrolled.

v2: Move after nir_opt_algebraic. Suggested by Georg.

shader-db:

All Intel platforms had similar results. (Meteor Lake shown)
total instructions in shared programs: 19787034 -> 19785933 (<.01%)
instructions in affected programs: 373573 -> 372472 (-0.29%)
helped: 541 / HURT: 6

total cycles in shared programs: 906012612 -> 905626304 (-0.04%)
cycles in affected programs: 58456516 -> 58070208 (-0.66%)
helped: 382 / HURT: 180

fossil-db:

Lunar Lake
Totals:
Instrs: 140671401 -> 140670495 (-0.00%); split: -0.00%, +0.00%
Send messages: 12891430822 -> 12891430834 (+0.00%)
Loop count: 46905 -> 46904 (-0.00%)
Cycle count: 21527511599 -> 21530278999 (+0.01%); split: -0.00%, +0.02%
Spill count: 70728 -> 70766 (+0.05%)
Fill count: 139397 -> 139254 (-0.10%); split: -0.13%, +0.02%
Max live registers: 47512432 -> 47512500 (+0.00%)

Totals from 355 (0.06% of 549270) affected shaders:
Instrs: 878953 -> 878047 (-0.10%); split: -0.18%, +0.08%
Send messages: 19289 -> 19301 (+0.06%)
Loop count: 1243 -> 1242 (-0.08%)
Cycle count: 1434664642 -> 1437432042 (+0.19%); split: -0.06%, +0.25%
Spill count: 15826 -> 15864 (+0.24%)
Fill count: 38454 -> 38311 (-0.37%); split: -0.46%, +0.08%
Max live registers: 52530 -> 52598 (+0.13%)

Meteor Lake and DG2 had similar results. (Meteor Lake shown)
Totals:
Instrs: 152516575 -> 152516147 (-0.00%); split: -0.00%, +0.00%
Send messages: 7491001 -> 7491013 (+0.00%)
Loop count: 47588 -> 47587 (-0.00%)
Cycle count: 17124433133 -> 17126147156 (+0.01%); split: -0.01%, +0.02%
Max live registers: 31854704 -> 31854764 (+0.00%)

Totals from 402 (0.06% of 633223) affected shaders:
Instrs: 839338 -> 838910 (-0.05%); split: -0.09%, +0.04%
Send messages: 20203 -> 20215 (+0.06%)
Loop count: 1243 -> 1242 (-0.08%)
Cycle count: 1327042160 -> 1328756183 (+0.13%); split: -0.11%, +0.24%
Max live registers: 33237 -> 33297 (+0.18%)

Tiger Lake
*** Shaders only in 'before' results are ignored:
fossil-db/steam-native/wolfenstein_youngblood/b8cefe7f700304c4/fs.32/0
from 1 apps: fossil-db/steam-native/wolfenstein_youngblood

Totals:
Instrs: 150549467 -> 150548952 (-0.00%); split: -0.00%, +0.00%
Send messages: 7495582 -> 7495594 (+0.00%)
Loop count: 46605 -> 46604 (-0.00%)
Cycle count: 15472381586 -> 15472247085 (-0.00%); split: -0.00%, +0.00%
Spill count: 59776 -> 59775 (-0.00%)
Fill count: 103475 -> 103464 (-0.01%)
Scratch Memory Size: 2384896 -> 2383872 (-0.04%)
Max live registers: 31760724 -> 31760787 (+0.00%)
Max dispatch width: 5569928 -> 5569912 (-0.00%)

Totals from 525 (0.08% of 632443) affected shaders:
Instrs: 349074 -> 348559 (-0.15%); split: -0.25%, +0.11%
Send messages: 24355 -> 24367 (+0.05%)
Loop count: 849 -> 848 (-0.12%)
Cycle count: 187080291 -> 186945790 (-0.07%); split: -0.19%, +0.12%
Spill count: 483 -> 482 (-0.21%)
Fill count: 1372 -> 1361 (-0.80%)
Scratch Memory Size: 22528 -> 21504 (-4.55%)
Max live registers: 36705 -> 36768 (+0.17%)
Max dispatch width: 6272 -> 6256 (-0.26%)

Ice Lake
Totals:
Instrs: 151804923 -> 151804396 (-0.00%); split: -0.00%, +0.00%
Send messages: 7553216 -> 7553228 (+0.00%)
Loop count: 46196 -> 46195 (-0.00%)
Cycle count: 15099805668 -> 15099533898 (-0.00%); split: -0.00%, +0.00%
Fill count: 103978 -> 103979 (+0.00%)
Max live registers: 32168254 -> 32168323 (+0.00%)

Totals from 527 (0.08% of 637191) affected shaders:
Instrs: 347482 -> 346955 (-0.15%); split: -0.25%, +0.10%
Send messages: 24586 -> 24598 (+0.05%)
Loop count: 849 -> 848 (-0.12%)
Cycle count: 191147758 -> 190875988 (-0.14%); split: -0.16%, +0.02%
Fill count: 1392 -> 1393 (+0.07%)
Max live registers: 37379 -> 37448 (+0.18%)

Skylake
Totals:
Instrs: 140981504 -> 140980647 (-0.00%); split: -0.00%, +0.00%
Cycle count: 14653477192 -> 14653249734 (-0.00%); split: -0.00%, +0.00%
Fill count: 99636 -> 99637 (+0.00%)
Max live registers: 31472062 -> 31472126 (+0.00%)

Totals from 523 (0.08% of 626432) affected shaders:
Instrs: 335551 -> 334694 (-0.26%); split: -0.26%, +0.01%
Cycle count: 178047284 -> 177819826 (-0.13%); split: -0.14%, +0.02%
Fill count: 1100 -> 1101 (+0.09%)
Max live registers: 36734 -> 36798 (+0.17%)

Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31006>

src/intel/compiler/brw_nir.c

@@ -803,6 +803,7 @@ brw_nir_optimize(nir_shader *nir,
       LOOP_OPT(nir_opt_idiv_const, 32);
       LOOP_OPT_NOT_IDEMPOTENT(nir_opt_algebraic);
 
+      LOOP_OPT(nir_opt_generate_bfi);
       LOOP_OPT(nir_opt_reassociate_bfi);
 
       LOOP_OPT(nir_lower_constant_convert_alu_types);