nir: add another comparison simplification

On BDW:

total instructions in shared programs: 13061877 -> 13060965 (-0.01%)
instructions in affected programs: 133569 -> 132657 (-0.68%)
helped: 566
HURT: 0

total cycles in shared programs: 256611784 -> 256599536 (-0.00%)
cycles in affected programs: 861016 -> 848768 (-1.42%)
helped: 379
HURT: 73

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 434881f..85cdc7b 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -150,6 +150,8 @@ optimizations = [
    # inot(a)
    (('fge', 0.0, ('b2f', a)), ('inot', a)),
 
+   (('fge', ('fneg', ('b2f', a)), 0.0), ('inot', a)),
+
    # 0.0 < fabs(a)
    # fabs(a) > 0.0
    # fabs(a) != 0.0 because fabs(a) must be >= 0