fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2025-12-29 18:50:10 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

v3d: enable NIR loop unrolling

Browse source 
The GL driver was getting loop unrolling from the GLSL compiler frontend,
but NIR unrolling is more sophisticated, so prefer that.

The only caveat is that loop unrolling is implemented in the Mesa state
tracker, so our backend won't have a chance to undo the optimization if
it causes us to lower thread count or spill, so we choose to be a bit more
conservative with the configuration than what we were doing with GLSL.

Shader-db results follow. Increase in instruction counts is expected due
to additional unrolling. We lose threads in very few shaders, but we
make up for this with the additional unrolling and reduced spilling. We
also managed to get 3 more shaders to compile successfully.

total instructions in shared programs: 13416427 -> 13461431 (0.34%)
instructions in affected programs: 96936 -> 141940 (46.43%)
helped: 58
HURT: 216
Instructions are HURT.

total threads in shared programs: 410626 -> 410598 (<.01%)
threads in affected programs: 56 -> 28 (-50.00%)
helped: 0
HURT: 14
Threads are HURT.

total loops in shared programs: 2121 -> 1708 (-19.47%)
loops in affected programs: 468 -> 55 (-88.25%)
helped: 446
HURT: 47
Loops are helped.

total uniforms in shared programs: 3676567 -> 3691185 (0.40%)
uniforms in affected programs: 25304 -> 39922 (57.77%)
helped: 23
HURT: 199
Uniforms are HURT.

total spills in shared programs: 5902 -> 5727 (-2.97%)
spills in affected programs: 285 -> 110 (-61.40%)
helped: 19
HURT: 0

total fills in shared programs: 13308 -> 13121 (-1.41%)
fills in affected programs: 301 -> 114 (-62.13%)
helped: 19
HURT: 0

total sfu-stalls in shared programs: 31860 -> 32856 (3.13%)
sfu-stalls in affected programs: 1692 -> 2688 (58.87%)
helped: 25
HURT: 196
Sfu-stalls are HURT.

total inst-and-stalls in shared programs: 13448287 -> 13494287 (0.34%)
inst-and-stalls in affected programs: 98404 -> 144404 (46.75%)
helped: 57
HURT: 217
Inst-and-stalls are HURT.

total nops in shared programs: 329276 -> 329551 (0.08%)
nops in affected programs: 2189 -> 2464 (12.56%)
helped: 58
HURT: 181
Nops are HURT.

LOST:   0
GAINED: 3

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10647>
This commit is contained in:
Iago Toral Quiroga 2021-05-03 11:12:43 +02:00
parent c11e479852
commit ca9e0871fb
1 changed files with 8 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
src/gallium/drivers/v3d/v3d_screen.c
View file

@ -423,7 +423,8 @@ v3d_screen_get_shader_param(struct pipe_screen *pscreen, unsigned shader,
case PIPE_SHADER_CAP_SUPPORTED_IRS:
return 1 << PIPE_SHADER_IR_NIR;
case PIPE_SHADER_CAP_MAX_UNROLL_ITERATIONS_HINT:
return 32;
/* Disable GLSL loop unrolling, we'll use NIR's */
return 0;
case PIPE_SHADER_CAP_LOWER_IF_THRESHOLD:
case PIPE_SHADER_CAP_TGSI_SKIP_MERGE_REGISTERS:
return 0;
@ -668,6 +669,12 @@ static const nir_shader_compiler_options v3d_nir_options = {
.has_isub = true,
.divergence_analysis_options =
nir_divergence_multiple_workgroup_per_compute_subgroup,
/* This will enable loop unrolling in the state tracker so we won't
* be able to selectively disable it in backend if it leads to
* lower thread counts or TMU spills. Choose a conservative maximum to
* limit register pressure impact.
*/
.max_unroll_iterations = 16,
};
static const void *