nir/algebraic: Simplify max(abs(a), 0.0) -> abs(a)

This pattern was noticed in glmark's jellyfish scene.

v2: Add inexact qualifier due to NaN behaviour.

Minimal shader-db changes (slightly helped).

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Elie Tournier <tournier.elie@gmail.com>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 594f521a66b19fa4c58a4d6d31fab45ad14258e2..d36131ae1ac21df4f6624a6b8f49dd274cd606bc 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -399,6 +399,7 @@ optimizations = [
    (('imax', a, ('iabs', a)), ('iabs', a)),
    (('fmax', a, ('fneg', a)), ('fabs', a)),
    (('imax', a, ('ineg', a)), ('iabs', a)),
+   (('~fmax', ('fabs', a), 0.0), ('fabs', a)),
    (('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
    (('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
    (('~fmin', ('fmax', a, -1.0),  0.0), ('fneg', ('fsat', ('fneg', a))), '!options->lower_negate && !options->lower_fsat'),