Mesa (master): nir: Simplify min and max of b2f

[Ian Romanick]

Module: Mesa
Branch: master
Commit: 68420d8322c2b304a0b15f94b43dec19f082dfae
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=68420d8322c2b304a0b15f94b43dec19f082dfae

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Tue Mar  8 11:11:00 2016 -0800

nir: Simplify min and max of b2f

v2: Rebase on almost 2 years.  Require that one of the arguments to fmin
or fmax be used only once.  This prevents some regressions.

shader-db results:

Skylake and Broadwell had similar results.  Skylake shown.
total instructions in shared programs: 14526021 -> 14525913 (<.01%)
instructions in affected programs: 4613 -> 4505 (-2.34%)
helped: 31
HURT: 0
helped stats (abs) min: 1 max: 4 x̄: 3.48 x̃: 4
helped stats (rel) min: 0.62% max: 6.67% x̄: 3.31% x̃: 2.42%

total cycles in shared programs: 533118710 -> 533118403 (<.01%)
cycles in affected programs: 34334 -> 34027 (-0.89%)
helped: 24
HURT: 0
helped stats (abs) min: 4 max: 24 x̄: 12.79 x̃: 14
helped stats (rel) min: 0.25% max: 2.40% x̄: 1.08% x̃: 1.03%

No changes on GM45, Iron Lake, Sandy Bridge, Ivy Bridge, or Haswell.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Reviewed-by: Elie Tournier <elie.tournier at collabora.com>

---

 src/compiler/nir/nir_opt_algebraic.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index b141f2414d..c097f12832 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -158,6 +158,11 @@ optimizations = [
    # a != 0.0
    (('flt', 0.0, ('fabs', a)), ('fne', a, 0.0)),
 
+   (('fmax',                        ('b2f(is_used_once)', a),           ('b2f', b)),           ('b2f', ('ior', a, b))),
+   (('fmax', ('fneg(is_used_once)', ('b2f(is_used_once)', a)), ('fneg', ('b2f', b))), ('fneg', ('b2f', ('ior', a, b)))),
+   (('fmin',                        ('b2f(is_used_once)', a),           ('b2f', b)),           ('b2f', ('iand', a, b))),
+   (('fmin', ('fneg(is_used_once)', ('b2f(is_used_once)', a)), ('fneg', ('b2f', b))), ('fneg', ('b2f', ('iand', a, b)))),
+
    # ignore this opt when the result is used by a bcsel or if so we can make
    # use of conditional modifiers on supported hardware.
    (('flt(is_not_used_by_conditional)', ('fadd(is_used_once)', a, ('fneg', b)), 0.0), ('flt', a, b)),