nir/algebraic: Add some max/min optimizations

Found by inspection.  This doesn't help much now but we'll see this
pattern with images if you load UNORM and then store UNORM.

Shader-db results on Kaby Lake:

    total instructions in shared programs: 15166916 -> 15166910 (<.01%)
    instructions in affected programs: 761 -> 755 (-0.79%)
    helped: 6
    HURT: 0

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 8a0ddf1..ae1261f 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -302,6 +302,12 @@ optimizations = [
    (('imax', a, a), a),
    (('umin', a, a), a),
    (('umax', a, a), a),
+   (('fmax', ('fmax', a, b), b), ('fmax', a, b)),
+   (('umax', ('umax', a, b), b), ('umax', a, b)),
+   (('imax', ('imax', a, b), b), ('imax', a, b)),
+   (('fmin', ('fmin', a, b), b), ('fmin', a, b)),
+   (('umin', ('umin', a, b), b), ('umin', a, b)),
+   (('imin', ('imin', a, b), b), ('imin', a, b)),
    (('fmax', a, ('fneg', a)), ('fabs', a)),
    (('imax', a, ('ineg', a)), ('iabs', a)),
    (('fmin', a, ('fneg', a)), ('fneg', ('fabs', a))),