nir/algebraic: Strip double negatives from comparison sources

All Intel platforms had similar results. (Ice Lake shown)
total instructions in shared programs: 17224623 -> 17224337 (<.01%)
instructions in affected programs: 32648 -> 32362 (-0.88%)
helped: 148
HURT: 0
helped stats (abs) min: 1 max: 2 x̄: 1.93 x̃: 2
helped stats (rel) min: 0.16% max: 2.74% x̄: 1.07% x̃: 1.08%
95% mean confidence interval for instructions value: -1.97 -1.89
95% mean confidence interval for instructions %-change: -1.15% -1.00%
Instructions are helped.

total cycles in shared programs: 360828714 -> 360826090 (<.01%)
cycles in affected programs: 347416 -> 344792 (-0.76%)
helped: 148
HURT: 26
helped stats (abs) min: 1 max: 426 x̄: 26.33 x̃: 18
helped stats (rel) min: 0.03% max: 15.10% x̄: 1.78% x̃: 1.41%
HURT stats (abs)   min: 2 max: 337 x̄: 48.96 x̃: 6
HURT stats (rel)   min: 0.04% max: 18.82% x̄: 2.15% x̃: 0.27%
95% mean confidence interval for cycles value: -23.78 -6.38
95% mean confidence interval for cycles %-change: -1.59% -0.79%
Cycles are helped.

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

src/compiler/nir/nir_opt_algebraic.py

@@ -199,6 +199,20 @@ optimizations = [
    (('inot', ('ieq', a, b)), ('ine', a, b)),
    (('inot', ('ine', a, b)), ('ieq', a, b)),
 
+   # This helps some shaders because, after some optimizations, they end up
+   # with patterns like (-a < -b) || (b < a).  In an ideal world, this sort of
+   # matching would be handled by CSE.
+   (('flt', ('fneg', a), ('fneg', b)), ('flt', b, a)),
+   (('fge', ('fneg', a), ('fneg', b)), ('fge', b, a)),
+   (('feq', ('fneg', a), ('fneg', b)), ('feq', b, a)),
+   (('fne', ('fneg', a), ('fneg', b)), ('fne', b, a)),
+   (('flt', ('fneg', a), -1.0), ('flt', 1.0, a)),
+   (('flt', -1.0, ('fneg', a)), ('flt', a, 1.0)),
+   (('fge', ('fneg', a), -1.0), ('fge', 1.0, a)),
+   (('fge', -1.0, ('fneg', a)), ('fge', a, 1.0)),
+   (('fne', ('fneg', a), -1.0), ('fne', 1.0, a)),
+   (('feq', -1.0, ('fneg', a)), ('feq', a, 1.0)),
+
    # 0.0 >= b2f(a)
    # b2f(a) <= 0.0
    # b2f(a) == 0.0 because b2f(a) can only be 0 or 1
@@ -1124,6 +1138,20 @@ late_optimizations = [
 
    (('~fge', ('fmin(is_used_once)', ('fadd(is_used_once)', a, b), ('fadd', c, d)), 0.0), ('iand', ('fge', a, ('fneg', b)), ('fge', c, ('fneg', d)))),
 
+   (('flt', ('fneg', a), ('fneg', b)), ('flt', b, a)),
+   (('fge', ('fneg', a), ('fneg', b)), ('fge', b, a)),
+   (('feq', ('fneg', a), ('fneg', b)), ('feq', b, a)),
+   (('fne', ('fneg', a), ('fneg', b)), ('fne', b, a)),
+   (('flt', ('fneg', a), -1.0), ('flt', 1.0, a)),
+   (('flt', -1.0, ('fneg', a)), ('flt', a, 1.0)),
+   (('fge', ('fneg', a), -1.0), ('fge', 1.0, a)),
+   (('fge', -1.0, ('fneg', a)), ('fge', a, 1.0)),
+   (('fne', ('fneg', a), -1.0), ('fne', 1.0, a)),
+   (('feq', -1.0, ('fneg', a)), ('feq', a, 1.0)),
+
+   (('ior', a, a), a),
+   (('iand', a, a), a),
+
    (('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
    (('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
    (('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),