nir/algebraic: Simplify fsqrt domain guard

All Gen7+ platforms had similar results. (Ice Lake shown)
total instructions in shared programs: 17228376 -> 17225365 (-0.02%)
instructions in affected programs: 280732 -> 277721 (-1.07%)
helped: 1072
HURT: 0
helped stats (abs) min: 1 max: 12 x̄: 2.81 x̃: 2
helped stats (rel) min: 0.16% max: 5.10% x̄: 1.43% x̃: 1.07%
95% mean confidence interval for instructions value: -2.92 -2.70
95% mean confidence interval for instructions %-change: -1.48% -1.37%
Instructions are helped.

total cycles in shared programs: 360935690 -> 360842788 (-0.03%)
cycles in affected programs: 7838017 -> 7745115 (-1.19%)
helped: 1569
HURT: 69
helped stats (abs) min: 1 max: 1198 x̄: 63.53 x̃: 20
helped stats (rel) min: 0.06% max: 26.17% x̄: 3.44% x̃: 2.12%
HURT stats (abs)   min: 1 max: 2820 x̄: 98.22 x̃: 47
HURT stats (rel)   min: 0.05% max: 16.67% x̄: 3.50% x̃: 2.31%
95% mean confidence interval for cycles value: -63.55 -49.89
95% mean confidence interval for cycles %-change: -3.33% -2.96%
Cycles are helped.

No changes on any other platform.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Thomas Helland <thomashelland90@gmail.com>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index ccf57fd4b8670e8a4d4646d727d74a647fa278ba..15ac3bd32ca7ee45b7acb910fc88d9f603389676 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -570,6 +570,7 @@ optimizations = [
    (('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
    (('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
    (('~fmul', ('fexp2(is_used_once)', a), ('fexp2(is_used_once)', b)), ('fexp2', ('fadd', a, b))),
+   (('bcsel', ('flt', a, 0.0), 0.0, ('fsqrt', a)), ('fsqrt', ('fmax', a, 0.0))),
    # Division and reciprocal
    (('~fdiv', 1.0, a), ('frcp', a)),
    (('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),