nir/algebraic: Move the flrp -> bcsel rule earlier

If multiple rules could match, the rule that appears first in the file
is used.

Only Tiger Lake and Ice Lake are affected.  Other platforms either have
a LRP instruction or can't run any shaders from shader-db that would
benefit.

v2: Fix issues created when this commit was rebased on top of
3c8934a644b8 ("nir/algebraic: add flrp patterns for 16 and 64 bits").
Noticed by Caio.

Tiger Lake and Ice Lake had similar results.
total instructions in shared programs: 20908672 -> 20908661 (<.01%)
instructions in affected programs: 419 -> 408 (-2.63%)
helped: 5
HURT: 0
helped stats (abs) min: 1 max: 3 x̄: 2.20 x̃: 3
helped stats (rel) min: 1.85% max: 3.19% x̄: 2.49% x̃: 2.65%
95% mean confidence interval for instructions value: -3.56 -0.84
95% mean confidence interval for instructions %-change: -3.24% -1.73%
Instructions are helped.

total cycles in shared programs: 473513940 -> 473513793 (<.01%)
cycles in affected programs: 7176 -> 7029 (-2.05%)
helped: 12
HURT: 0
helped stats (abs) min: 5 max: 22 x̄: 12.25 x̃: 12
helped stats (rel) min: 0.84% max: 3.24% x̄: 2.09% x̃: 1.80%
95% mean confidence interval for cycles value: -15.43 -9.07
95% mean confidence interval for cycles %-change: -2.57% -1.61%
Cycles are helped.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6358>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 142bf99..bd9b786 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -168,12 +168,12 @@ optimizations = [
 # Float sizes
 for s in [16, 32, 64]:
     optimizations.extend([
+       (('~flrp@{}'.format(s), a, b, ('b2f', 'c@1')), ('bcsel', c, b, a), 'options->lower_flrp{}'.format(s)),
+
        (('~flrp@{}'.format(s), a, ('fadd', a, b), c), ('fadd', ('fmul', b, c), a), 'options->lower_flrp{}'.format(s)),
        (('~flrp@{}'.format(s), ('fadd', a, b), ('fadd', a, c), d), ('fadd', ('flrp', b, c, d), a), 'options->lower_flrp{}'.format(s)),
        (('~flrp@{}'.format(s), a, ('fmul(is_used_once)', a, b), c), ('fmul', ('flrp', 1.0, b, c), a), 'options->lower_flrp{}'.format(s)),
 
-       (('~flrp@{}'.format(s), a, b, ('b2f', 'c@1')), ('bcsel', c, b, a), 'options->lower_flrp{}'.format(s)),
-
        (('~fadd@{}'.format(s), ('fmul', a, ('fadd', 1.0, ('fneg', c))), ('fmul', b, c)), ('flrp', a, b, c), '!options->lower_flrp{}'.format(s)),
        # These are the same as the previous three rules, but it depends on
        # 1-fsat(x) <=> fsat(1-x).  See below.