Previously lower_flrp32 was only set for vertex shaders.  Fragment
shaders performed a(1-c)+bc lowering during code generation.

The shaders with loops hurt are SIMD8 and SIMD16 shaders for a
text-identical fragment shader.

v2: Rebase on 26391cce ("intel/compiler: Lower ffma on Gen4 and
Gen5").

v3: Rebase on a004e95d ("radeonsi/nir: create si_nir_opts() helper")

Iron Lake
total instructions in shared programs: 8211385 -> 8185974 (-0.31%)
instructions in affected programs: 2503898 -> 2478487 (-1.01%)
helped: 9936
HURT: 921
helped stats (abs) min: 1 max: 155 x̄: 2.86 x̃: 2
helped stats (rel) min: 0.10% max: 35.48% x̄: 1.67% x̃: 1.11%
HURT stats (abs)   min: 1 max: 12 x̄: 3.24 x̃: 2
HURT stats (rel)   min: 0.21% max: 13.64% x̄: 1.86% x̃: 0.89%
95% mean confidence interval for instructions value: -2.43 -2.25
95% mean confidence interval for instructions %-change: -1.41% -1.33%
Instructions are helped.

total cycles in shared programs: 188523186 -> 188401198 (-0.06%)
cycles in affected programs: 71541604 -> 71419616 (-0.17%)
helped: 11649
HURT: 1871
helped stats (abs) min: 2 max: 930 x̄: 12.62 x̃: 6
helped stats (rel) min: <.01% max: 44.61% x̄: 0.68% x̃: 0.25%
HURT stats (abs)   min: 2 max: 138 x̄: 13.38 x̃: 8
HURT stats (rel)   min: <.01% max: 10.99% x̄: 0.49% x̃: 0.17%
95% mean confidence interval for cycles value: -9.42 -8.63
95% mean confidence interval for cycles %-change: -0.54% -0.50%
Cycles are helped.

total loops in shared programs: 852 -> 856 (0.47%)
loops in affected programs: 0 -> 4
helped: 0
HURT: 4
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.00% max: 0.00% x̄: 0.00% x̃: 0.00%
95% mean confidence interval for loops value: 1.00 1.00
95% mean confidence interval for loops %-change: 0.00% 0.00%
Loops are HURT.

LOST:   3
GAINED: 12

GM45
total instructions in shared programs: 5046407 -> 5033694 (-0.25%)
instructions in affected programs: 1303584 -> 1290871 (-0.98%)
helped: 5010
HURT: 464
helped stats (abs) min: 1 max: 155 x̄: 2.85 x̃: 2
helped stats (rel) min: 0.10% max: 34.38% x̄: 1.63% x̃: 1.08%
HURT stats (abs)   min: 1 max: 75 x̄: 3.39 x̃: 2
HURT stats (rel)   min: 0.20% max: 13.04% x̄: 1.84% x̃: 0.87%
95% mean confidence interval for instructions value: -2.45 -2.20
95% mean confidence interval for instructions %-change: -1.40% -1.28%
Instructions are helped.

total cycles in shared programs: 128889476 -> 128812366 (-0.06%)
cycles in affected programs: 44845402 -> 44768292 (-0.17%)
helped: 6079
HURT: 940
helped stats (abs) min: 2 max: 930 x̄: 15.16 x̃: 8
helped stats (rel) min: <.01% max: 41.03% x̄: 0.71% x̃: 0.25%
HURT stats (abs)   min: 2 max: 138 x̄: 16.01 x̃: 8
HURT stats (rel)   min: <.01% max: 10.99% x̄: 0.50% x̃: 0.17%
95% mean confidence interval for cycles value: -11.63 -10.34
95% mean confidence interval for cycles %-change: -0.58% -0.52%
Cycles are helped.

total loops in shared programs: 633 -> 635 (0.32%)
loops in affected programs: 0 -> 2
helped: 0
HURT: 2

total spills in shared programs: 60 -> 69 (15.00%)
spills in affected programs: 54 -> 63 (16.67%)
helped: 0
HURT: 1

total fills in shared programs: 92 -> 105 (14.13%)
fills in affected programs: 80 -> 93 (16.25%)
helped: 0
HURT: 1

LOST:   15
GAINED: 15

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> [v2]
Reviewed-by: Matt Turner <mattst88@gmail.com> [v2]