[Mesa-dev] [PATCH 00/23] Handle Booleans and things better

[Ian Romanick]

This is a series that I've been working on for quite some time.  Some of
these patches data from as long ago as July 2014.  It's finally time to
just send it out.  I have felt like I have been shaving an infinite yak,
and I have some additional patchs in-progress that will go on top of
this series.

Overall results for the without NIR:

GM45 (0x2A42):
total instructions in shared programs: 3550788 -> 3544141 (-0.19%)
instructions in affected programs:     513721 -> 507074 (-1.29%)
helped:                                1409
HURT:                                  269

Iron Lake (0x0046):
total instructions in shared programs: 4980593 -> 4973020 (-0.15%)
instructions in affected programs:     572150 -> 564577 (-1.32%)
helped:                                1649
HURT:                                  386
GAINED:                                5
LOST:                                  24

Sandy Bridge (0x0116):
total instructions in shared programs: 6817068 -> 6797680 (-0.28%)
instructions in affected programs:     1388229 -> 1368841 (-1.40%)
helped:                                5343
HURT:                                  319
GAINED:                                4
LOST:                                  11

Ivy Bridge (0x0166):
total instructions in shared programs: 6290138 -> 6273022 (-0.27%)
instructions in affected programs:     1204828 -> 1187712 (-1.42%)
helped:                                4558
HURT:                                  825
GAINED:                                1
LOST:                                  3

Haswell (0x0426):
total instructions in shared programs: 5777876 -> 5759525 (-0.32%)
instructions in affected programs:     1130638 -> 1112287 (-1.62%)
helped:                                4830
HURT:                                  606
GAINED:                                1
LOST:                                  3

Broadwell (0x162E):
total instructions in shared programs: 6821191 -> 6806526 (-0.21%)
instructions in affected programs:     1252081 -> 1237416 (-1.17%)
helped:                                5090
HURT:                                  608
GAINED:                                4
LOST:                                  4

In some ways the results with NIR are even better (if you ignore Sandy
Bridge):

Sandy Bridge (0x0116) NIR:
total instructions in shared programs: 6820689 -> 6785869 (-0.51%)
instructions in affected programs:     1858575 -> 1823755 (-1.87%)
helped:                                4559
HURT:                                  3320
GAINED:                                3
LOST:                                  29

Ivy Bridge (0x0166) NIR:
total instructions in shared programs: 6309309 -> 6276897 (-0.51%)
instructions in affected programs:     1639688 -> 1607276 (-1.98%)
helped:                                4053
HURT:                                  3496
GAINED:                                34
LOST:                                  3

Haswell (0x0426) NIR:
total instructions in shared programs: 5790261 -> 5751689 (-0.67%)
instructions in affected programs:     1506127 -> 1467555 (-2.56%)
helped:                                5407
HURT:                                  1957
GAINED:                                28
LOST:                                  3

Broadwell (0x162E) NIR:
total instructions in shared programs: 7012929 -> 6977716 (-0.50%)
instructions in affected programs:     1604094 -> 1568881 (-2.20%)
helped:                                5626
HURT:                                  2029
GAINED:                                20
LOST:                                  3

In that there are 12 shaders that are hurt (by ~40 instructions) because
we are now able to unroll a loop.  This is noted in the commit message
of "glsl: Optimize certain if-statements to just casts from the
condition".

There are a couple commits that hurt a fair number of shaders with NIR.
It doesn't seem like this should be the case, and it seems like there is
probably work that can be done in brw_fs_nir.cpp to account for this.
Without some of the initial changes to brw_fs_visitor.cpp, there were
also regressions without NIR.  All of the changes in this series at the
GLSL IR level are things that could have been written in the shader
source.

At the end of the day on Broadwell with NIR, there are a bunch of
shaders (some as small as ~22 instructions) hurt by 1 to 4 instructions.
Only one shader is really hurt (119 -> 139).  This shader is noted in
patch "glsl: Distribute multiply over b2f".  At the same time, over 250
shaders with more than 100 instructions are helped by more than 20%.
Oh, and we gained 20 SIMD16 shaders. :)

This series is also available as the bool-optimizations-v6 branch in my
fd.o Mesa repo.