[Mesa-dev] [PATCH 10/11] nir/algebraic: Replace a pattern where iand with a Boolean is used as a bcsel

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

All of the affected shaders are in Mad Max.  I noticed this while
looking at some other things.  I tried a couple similar patterns, but
the affect on cycles was general negative.  It may be worth revisiting
this later.

All Gen7+ platforms had similar results. (Skylake shown)
total instructions in shared programs: 15090929 -> 15090909 (<.01%)
instructions in affected programs: 1192 -> 1172 (-1.68%)
helped: 14
HURT: 0
helped stats (abs) min: 1 max: 2 x̄: 1.43 x̃: 1
helped stats (rel) min: 1.16% max: 2.17% x̄: 1.65% x̃: 1.39%
95% mean confidence interval for instructions value: -1.73 -1.13
95% mean confidence interval for instructions %-change: -1.91% -1.38%
Instructions are helped.

total cycles in shared programs: 565826044 -> 565824622 (<.01%)
cycles in affected programs: 11477 -> 10055 (-12.39%)
helped: 14
HURT: 0
helped stats (abs) min: 76 max: 122 x̄: 101.57 x̃: 104
helped stats (rel) min: 7.76% max: 15.62% x̄: 12.94% x̃: 14.78%
95% mean confidence interval for cycles value: -111.05 -92.09
95% mean confidence interval for cycles %-change: -14.90% -10.98%
Cycles are helped.

No changes on any Gen6 or earlier platforms.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/compiler/nir/nir_opt_algebraic.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 6d963cede93..cada08d274d 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -34,6 +34,7 @@ a = 'a'
 b = 'b'
 c = 'c'
 d = 'd'
+e = 'e'
 
 # Written in the form (<search>, <replace>) where <search> is an expression
 # and <replace> is either an expression or a value.  An expression is
@@ -133,6 +134,9 @@ optimizations = [
    (('ffma', a, b, c), ('fadd', ('fmul', a, b), c), 'options->lower_ffma'),
    (('~fadd', ('fmul', a, b), c), ('ffma', a, b, c), 'options->fuse_ffma'),
 
+   (('~fmul', ('fadd', ('iand', 'a at bool', ('fmul', b, c)), '#d'), '#e'),
+    ('bcsel', a, ('fmul', ('fadd', ('fmul', b, c), d), e), ('fmul', d, e))),
+
    (('fdot4', ('vec4', a, b,   c,   1.0), d), ('fdph',  ('vec3', a, b, c), d)),
    (('fdot4', ('vec4', a, 0.0, 0.0, 0.0), b), ('fmul', a, b)),
    (('fdot4', ('vec4', a, b,   0.0, 0.0), c), ('fdot2', ('vec2', a, b), c)),
-- 
2.14.4