nir/algebraic: Pull common multiplication out of flrp arguments

All Intel platforms had similar results. (Skylake shown)
total instructions in shared programs: 15342485 -> 15337495 (-0.03%)
instructions in affected programs: 217456 -> 212466 (-2.29%)
helped: 1539
HURT: 1
helped stats (abs) min: 1 max: 17 x̄: 3.24 x̃: 3
helped stats (rel) min: 0.22% max: 18.75% x̄: 3.10% x̃: 1.91%
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.56% max: 0.56% x̄: 0.56% x̃: 0.56%
95% mean confidence interval for instructions value: -3.39 -3.09
95% mean confidence interval for instructions %-change: -3.24% -2.96%
Instructions are helped.

total cycles in shared programs: 355734320 -> 355728237 (<.01%)
cycles in affected programs: 1851555 -> 1845472 (-0.33%)
helped: 835
HURT: 575
helped stats (abs) min: 1 max: 658 x̄: 40.62 x̃: 14
helped stats (rel) min: <.01% max: 35.69% x̄: 3.78% x̃: 1.81%
HURT stats (abs)   min: 1 max: 322 x̄: 48.40 x̃: 14
HURT stats (rel)   min: 0.04% max: 71.02% x̄: 8.06% x̃: 2.43%
95% mean confidence interval for cycles value: -8.50 -0.13
95% mean confidence interval for cycles %-change: 0.48% 1.62%
Inconclusive result (value mean confidence interval and %-change mean confidence interval disagree).

Reviewed-by: Matt Turner <mattst88@gmail.com>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 59ba4add43e227f1dbfa437863e4e69cab627634..53beb4a8546de3bb9209ee81e3386b56c7184d48 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -136,6 +136,11 @@ optimizations = [
    (('~flrp@32', ('fadd', a, b), ('fadd', a, c), d), ('fadd', ('flrp', b, c, d), a), 'options->lower_flrp32'),
    (('~flrp@64', ('fadd', a, b), ('fadd', a, c), d), ('fadd', ('flrp', b, c, d), a), 'options->lower_flrp64'),
 
+   (('~flrp@32', a, ('fmul(is_used_once)', a, b), c), ('fmul', ('flrp', 1.0, b, c), a), 'options->lower_flrp32'),
+   (('~flrp@64', a, ('fmul(is_used_once)', a, b), c), ('fmul', ('flrp', 1.0, b, c), a), 'options->lower_flrp64'),
+
+   (('~flrp', ('fmul(is_used_once)', a, b), ('fmul(is_used_once)', a, c), d), ('fmul', ('flrp', b, c, d), a)),
+
    (('~flrp', a, b, ('b2f', 'c@1')), ('bcsel', c, b, a), 'options->lower_flrp32'),
    (('~flrp', a, 0.0, c), ('fadd', ('fmul', ('fneg', a), c), a)),
    (('flrp@16', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp16'),