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nir: add heuristic for instructions in loops with GCM

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Moving instructions out of large loops tends to cause excessive
spilling. This appears to be a good limit.

In future it might make sense to make this a NIR options so
other drivers can set their own limits.

Tiger Lake
total instructions in shared programs: 20930180 -> 20926952 (-0.02%)
instructions in affected programs: 280768 -> 277540 (-1.15%)
helped: 734
HURT: 192
helped stats (abs) min: 1 max: 61 x̄: 5.16 x̃: 4
helped stats (rel) min: 0.04% max: 10.64% x̄: 3.23% x̃: 3.14%
HURT stats (abs)   min: 1 max: 52 x̄: 2.90 x̃: 1
HURT stats (rel)   min: 0.03% max: 9.76% x̄: 1.13% x̃: 0.61%
95% mean confidence interval for instructions value: -3.89 -3.08
95% mean confidence interval for instructions %-change: -2.49% -2.16%
Instructions are helped.

total cycles in shared programs: 841825217 -> 838817552 (-0.36%)
cycles in affected programs: 122088078 -> 119080413 (-2.46%)
helped: 941
HURT: 100
helped stats (abs) min: 1 max: 160080 x̄: 3274.31 x̃: 2660
helped stats (rel) min: <.01% max: 41.64% x̄: 5.50% x̃: 4.80%
HURT stats (abs)   min: 1 max: 41856 x̄: 734.62 x̃: 26
HURT stats (rel)   min: <.01% max: 7.29% x̄: 0.44% x̃: 0.27%
95% mean confidence interval for cycles value: -3236.56 -2541.85
95% mean confidence interval for cycles %-change: -5.26% -4.60%
Cycles are helped.

total sends in shared programs: 977905 -> 977782 (-0.01%)
sends in affected programs: 2279 -> 2156 (-5.40%)
helped: 119
HURT: 0
helped stats (abs) min: 1 max: 4 x̄: 1.03 x̃: 1
helped stats (rel) min: 0.60% max: 14.29% x̄: 6.93% x̃: 6.67%
95% mean confidence interval for sends value: -1.09 -0.98
95% mean confidence interval for sends %-change: -7.42% -6.45%
Sends are helped.

LOST:   2
GAINED: 0

Ice Lake
total instructions in shared programs: 19865361 -> 19861747 (-0.02%)
instructions in affected programs: 185789 -> 182175 (-1.95%)
helped: 593
HURT: 47
helped stats (abs) min: 1 max: 27 x̄: 6.17 x̃: 4
helped stats (rel) min: 0.19% max: 8.65% x̄: 4.53% x̃: 4.60%
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.03% max: 0.23% x̄: 0.11% x̃: 0.04%
95% mean confidence interval for instructions value: -5.93 -5.37
95% mean confidence interval for instructions %-change: -4.32% -4.06%
Instructions are helped.

total loops in shared programs: 6120 -> 6117 (-0.05%)
loops in affected programs: 6 -> 3 (-50.00%)
helped: 3
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%

total cycles in shared programs: 961777176 -> 959404350 (-0.25%)
cycles in affected programs: 172224180 -> 169851354 (-1.38%)
helped: 936
HURT: 80
helped stats (abs) min: 1 max: 9566 x̄: 2621.08 x̃: 2550
helped stats (rel) min: <.01% max: 41.77% x̄: 4.22% x̃: 3.84%
HURT stats (abs)   min: 1 max: 59146 x̄: 1006.34 x̃: 24
HURT stats (rel)   min: <.01% max: 3.78% x̄: 0.44% x̃: 0.25%
95% mean confidence interval for cycles value: -2513.72 -2157.20
95% mean confidence interval for cycles %-change: -4.13% -3.57%
Cycles are helped.

total sends in shared programs: 1019995 -> 1019872 (-0.01%)
sends in affected programs: 2283 -> 2160 (-5.39%)
helped: 119
HURT: 0
helped stats (abs) min: 1 max: 4 x̄: 1.03 x̃: 1
helped stats (rel) min: 0.60% max: 14.29% x̄: 6.91% x̃: 6.67%
95% mean confidence interval for sends value: -1.09 -0.98
95% mean confidence interval for sends %-change: -7.39% -6.42%
Sends are helped.

LOST:   4
GAINED: 0

Skylake
total instructions in shared programs: 17994337 -> 17993846 (<.01%)
instructions in affected programs: 146294 -> 145803 (-0.34%)
helped: 190
HURT: 47
helped stats (abs) min: 1 max: 12 x̄: 2.83 x̃: 3
helped stats (rel) min: 0.14% max: 4.29% x̄: 1.08% x̃: 0.90%
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.03% max: 0.22% x̄: 0.11% x̃: 0.04%
95% mean confidence interval for instructions value: -2.30 -1.84
95% mean confidence interval for instructions %-change: -0.95% -0.74%
Instructions are helped.

total loops in shared programs: 6029 -> 6023 (-0.10%)
loops in affected programs: 12 -> 6 (-50.00%)
helped: 6
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for loops value: -1.00 -1.00
95% mean confidence interval for loops %-change: -50.00% -50.00%
Loops are helped.

total cycles in shared programs: 939062940 -> 938023548 (-0.11%)
cycles in affected programs: 169671482 -> 168632090 (-0.61%)
helped: 980
HURT: 134
helped stats (abs) min: 1 max: 25000 x̄: 1075.57 x̃: 1052
helped stats (rel) min: <.01% max: 42.75% x̄: 2.51% x̃: 1.32%
HURT stats (abs)   min: 1 max: 837 x̄: 109.45 x̃: 20
HURT stats (rel)   min: <.01% max: 5.71% x̄: 0.73% x̃: 0.21%
95% mean confidence interval for cycles value: -1005.89 -860.17
95% mean confidence interval for cycles %-change: -2.39% -1.84%
Cycles are helped.

total sends in shared programs: 1026848 -> 1026724 (-0.01%)
sends in affected programs: 2302 -> 2178 (-5.39%)
helped: 120
HURT: 0
helped stats (abs) min: 1 max: 4 x̄: 1.03 x̃: 1
helped stats (rel) min: 0.60% max: 14.29% x̄: 6.91% x̃: 6.67%
95% mean confidence interval for sends value: -1.09 -0.98
95% mean confidence interval for sends %-change: -7.40% -6.43%
Sends are helped.

LOST:   1
GAINED: 1

Broadwell
total instructions in shared programs: 17605621 -> 17605154 (<.01%)
instructions in affected programs: 145691 -> 145224 (-0.32%)
helped: 184
HURT: 48
helped stats (abs) min: 1 max: 12 x̄: 2.83 x̃: 3
helped stats (rel) min: 0.13% max: 4.29% x̄: 1.09% x̃: 0.93%
HURT stats (abs)   min: 1 max: 7 x̄: 1.12 x̃: 1
HURT stats (rel)   min: 0.03% max: 0.48% x̄: 0.12% x̃: 0.04%
95% mean confidence interval for instructions value: -2.26 -1.77
95% mean confidence interval for instructions %-change: -0.95% -0.73%
Instructions are helped.

total loops in shared programs: 5968 -> 5963 (-0.08%)
loops in affected programs: 10 -> 5 (-50.00%)
helped: 5
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for loops value: -1.00 -1.00
95% mean confidence interval for loops %-change: -50.00% -50.00%
Loops are helped.

total cycles in shared programs: 1000679489 -> 998592756 (-0.21%)
cycles in affected programs: 173421234 -> 171334501 (-1.20%)
helped: 993
HURT: 153
helped stats (abs) min: 1 max: 766608 x̄: 2118.49 x̃: 1080
helped stats (rel) min: <.01% max: 54.61% x̄: 2.61% x̃: 1.73%
HURT stats (abs)   min: 1 max: 2200 x̄: 110.61 x̃: 11
HURT stats (rel)   min: <.01% max: 5.68% x̄: 0.63% x̃: 0.06%
95% mean confidence interval for cycles value: -3191.23 -450.54
95% mean confidence interval for cycles %-change: -2.47% -1.89%
Cycles are helped.

total sends in shared programs: 996341 -> 996222 (-0.01%)
sends in affected programs: 2151 -> 2032 (-5.53%)
helped: 115
HURT: 0
helped stats (abs) min: 1 max: 4 x̄: 1.03 x̃: 1
helped stats (rel) min: 0.60% max: 14.29% x̄: 7.07% x̃: 6.67%
95% mean confidence interval for sends value: -1.09 -0.98
95% mean confidence interval for sends %-change: -7.55% -6.58%
Sends are helped.

Haswell
total instructions in shared programs: 16038375 -> 16038121 (<.01%)
instructions in affected programs: 216797 -> 216543 (-0.12%)
helped: 185
HURT: 217
helped stats (abs) min: 1 max: 12 x̄: 2.84 x̃: 3
helped stats (rel) min: 0.13% max: 4.23% x̄: 1.30% x̃: 1.20%
HURT stats (abs)   min: 1 max: 6 x̄: 1.25 x̃: 1
HURT stats (rel)   min: 0.03% max: 5.66% x̄: 0.61% x̃: 0.40%
95% mean confidence interval for instructions value: -0.85 -0.41
95% mean confidence interval for instructions %-change: -0.40% -0.14%
Instructions are helped.

total loops in shared programs: 5947 -> 5942 (-0.08%)
loops in affected programs: 10 -> 5 (-50.00%)
helped: 5
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for loops value: -1.00 -1.00
95% mean confidence interval for loops %-change: -50.00% -50.00%
Loops are helped.

total cycles in shared programs: 967655093 -> 965746713 (-0.20%)
cycles in affected programs: 197288924 -> 195380544 (-0.97%)
helped: 950
HURT: 195
helped stats (abs) min: 1 max: 782820 x̄: 2274.79 x̃: 1260
helped stats (rel) min: <.01% max: 54.26% x̄: 3.02% x̃: 1.71%
HURT stats (abs)   min: 1 max: 15790 x̄: 1295.73 x̃: 21
HURT stats (rel)   min: <.01% max: 119.85% x̄: 7.76% x̃: 0.11%
95% mean confidence interval for cycles value: -3014.22 -319.19
95% mean confidence interval for cycles %-change: -1.83% -0.55%
Cycles are helped.

total sends in shared programs: 934894 -> 934765 (-0.01%)
sends in affected programs: 2192 -> 2063 (-5.89%)
helped: 115
HURT: 2
helped stats (abs) min: 1 max: 4 x̄: 1.14 x̃: 1
helped stats (rel) min: 0.60% max: 28.57% x̄: 7.68% x̃: 6.67%
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 16.67% max: 16.67% x̄: 16.67% x̃: 16.67%
95% mean confidence interval for sends value: -1.23 -0.98
95% mean confidence interval for sends %-change: -8.28% -6.24%
Sends are helped.

LOST:   1
GAINED: 18

Ivy Bridge
total instructions in shared programs: 15269357 -> 15269398 (<.01%)
instructions in affected programs: 190484 -> 190525 (0.02%)
helped: 77
HURT: 206
helped stats (abs) min: 1 max: 6 x̄: 2.47 x̃: 3
helped stats (rel) min: 0.14% max: 5.31% x̄: 1.46% x̃: 1.65%
HURT stats (abs)   min: 1 max: 3 x̄: 1.12 x̃: 1
HURT stats (rel)   min: 0.03% max: 2.38% x̄: 0.42% x̃: 0.40%
95% mean confidence interval for instructions value: -0.06 0.35
95% mean confidence interval for instructions %-change: -0.21% 0.03%
Inconclusive result (value mean confidence interval includes 0).

total loops in shared programs: 4001 -> 3996 (-0.12%)
loops in affected programs: 10 -> 5 (-50.00%)
helped: 5
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for loops value: -1.00 -1.00
95% mean confidence interval for loops %-change: -50.00% -50.00%
Loops are helped.

total cycles in shared programs: 562045564 -> 561063543 (-0.17%)
cycles in affected programs: 200924872 -> 199942851 (-0.49%)
helped: 748
HURT: 160
helped stats (abs) min: 2 max: 14926 x̄: 1692.94 x̃: 1620
helped stats (rel) min: <.01% max: 53.29% x̄: 3.17% x̃: 1.87%
HURT stats (abs)   min: 2 max: 15726 x̄: 1776.86 x̃: 36
HURT stats (rel)   min: <.01% max: 114.43% x̄: 10.66% x̃: 0.21%
95% mean confidence interval for cycles value: -1237.33 -925.71
95% mean confidence interval for cycles %-change: -1.54% 0.08%
Inconclusive result (%-change mean confidence interval includes 0).

total sends in shared programs: 893348 -> 893330 (<.01%)
sends in affected programs: 187 -> 169 (-9.63%)
helped: 14
HURT: 0
helped stats (abs) min: 1 max: 2 x̄: 1.29 x̃: 1
helped stats (rel) min: 4.08% max: 22.22% x̄: 11.70% x̃: 10.10%
95% mean confidence interval for sends value: -1.56 -1.02
95% mean confidence interval for sends %-change: -14.92% -8.48%
Sends are helped.

LOST:   1
GAINED: 19

Sandy Bridge
total instructions in shared programs: 11785227 -> 11785774 (<.01%)
instructions in affected programs: 78403 -> 78950 (0.70%)
helped: 65
HURT: 505
helped stats (abs) min: 1 max: 4 x̄: 2.22 x̃: 3
helped stats (rel) min: 0.14% max: 4.17% x̄: 1.19% x̃: 1.38%
HURT stats (abs)   min: 1 max: 5 x̄: 1.37 x̃: 1
HURT stats (rel)   min: 0.24% max: 3.33% x̄: 1.57% x̃: 1.72%
95% mean confidence interval for instructions value: 0.85 1.07
95% mean confidence interval for instructions %-change: 1.16% 1.36%
Instructions are HURT.

total loops in shared programs: 2441 -> 2437 (-0.16%)
loops in affected programs: 8 -> 4 (-50.00%)
helped: 4
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for loops value: -1.00 -1.00
95% mean confidence interval for loops %-change: -50.00% -50.00%
Loops are helped.

total cycles in shared programs: 497178796 -> 496669298 (-0.10%)
cycles in affected programs: 51483322 -> 50973824 (-0.99%)
helped: 476
HURT: 137
helped stats (abs) min: 2 max: 7502 x̄: 1079.36 x̃: 1260
helped stats (rel) min: <.01% max: 42.50% x̄: 2.31% x̃: 0.86%
HURT stats (abs)   min: 2 max: 754 x̄: 31.23 x̃: 18
HURT stats (rel)   min: <.01% max: 3.01% x̄: 0.09% x̃: 0.02%
95% mean confidence interval for cycles value: -901.99 -760.32
95% mean confidence interval for cycles %-change: -2.20% -1.36%
Cycles are helped.

total sends in shared programs: 642919 -> 642915 (<.01%)
sends in affected programs: 32 -> 28 (-12.50%)
helped: 4
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 11.11% max: 14.29% x̄: 12.70% x̃: 12.70%
95% mean confidence interval for sends value: -1.00 -1.00
95% mean confidence interval for sends %-change: -15.61% -9.78%
Sends are helped.

Iron Lake
total instructions in shared programs: 8180061 -> 8180248 (<.01%)
instructions in affected programs: 65004 -> 65191 (0.29%)
helped: 59
HURT: 253
helped stats (abs) min: 1 max: 4 x̄: 2.24 x̃: 3
helped stats (rel) min: 0.16% max: 2.23% x̄: 1.04% x̃: 1.29%
HURT stats (abs)   min: 1 max: 5 x̄: 1.26 x̃: 1
HURT stats (rel)   min: 0.21% max: 3.85% x̄: 0.93% x̃: 0.60%
95% mean confidence interval for instructions value: 0.43 0.77
95% mean confidence interval for instructions %-change: 0.45% 0.68%
Instructions are HURT.

total loops in shared programs: 863 -> 861 (-0.23%)
loops in affected programs: 4 -> 2 (-50.00%)
helped: 2
HURT: 0

total cycles in shared programs: 239357490 -> 238907668 (-0.19%)
cycles in affected programs: 17314006 -> 16864184 (-2.60%)
helped: 176
HURT: 34
helped stats (abs) min: 4 max: 13400 x̄: 2558.05 x̃: 2920
helped stats (rel) min: 0.01% max: 35.58% x̄: 3.76% x̃: 2.69%
HURT stats (abs)   min: 2 max: 14 x̄: 11.59 x̃: 14
HURT stats (rel)   min: <.01% max: 0.06% x̄: 0.03% x̃: 0.03%
95% mean confidence interval for cycles value: -2440.68 -1843.34
95% mean confidence interval for cycles %-change: -3.78% -2.51%
Cycles are helped.

GM45
total instructions in shared programs: 4985293 -> 4985401 (<.01%)
instructions in affected programs: 58807 -> 58915 (0.18%)
helped: 57
HURT: 202
helped stats (abs) min: 1 max: 4 x̄: 2.26 x̃: 3
helped stats (rel) min: 0.15% max: 2.23% x̄: 1.06% x̃: 1.29%
HURT stats (abs)   min: 1 max: 5 x̄: 1.17 x̃: 1
HURT stats (rel)   min: 0.21% max: 3.85% x̄: 0.76% x̃: 0.48%
95% mean confidence interval for instructions value: 0.22 0.61
95% mean confidence interval for instructions %-change: 0.24% 0.48%
Instructions are HURT.

total loops in shared programs: 639 -> 638 (-0.16%)
loops in affected programs: 2 -> 1 (-50.00%)
helped: 1
HURT: 0

total cycles in shared programs: 153794236 -> 153546274 (-0.16%)
cycles in affected programs: 9947778 -> 9699816 (-2.49%)
helped: 110
HURT: 31
helped stats (abs) min: 4 max: 13400 x̄: 2257.51 x̃: 1796
helped stats (rel) min: 0.01% max: 35.58% x̄: 4.33% x̃: 2.45%
HURT stats (abs)   min: 2 max: 14 x̄: 11.74 x̃: 14
HURT stats (rel)   min: <.01% max: 0.06% x̄: 0.03% x̃: 0.03%
95% mean confidence interval for cycles value: -2113.77 -1403.42
95% mean confidence interval for cycles %-change: -4.27% -2.47%
Cycles are helped.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/2899

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12064>
This commit is contained in:
Timothy Arceri
2021-07-26 23:25:58 +10:00
committed by Marge Bot
parent a7f2e683de
commit 6538b3e566
1 changed files with 101 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

123
src/compiler/nir/nir_opt_gcm.c
View File

@@ -37,10 +37,23 @@
* verify correcness.
*/
/* This is used to stop GCM moving instruction out of a loop if the loop
* contains too many instructions and moving them would create excess spilling.
*
* TODO: Figure out a better way to decide if we should remove instructions from
* a loop.
*/
#define MAX_LOOP_INSTRUCTIONS 100
struct gcm_block_info {
/* Number of loops this block is inside */
unsigned loop_depth;
unsigned loop_instr_count;
/* The loop the block is nested inside or NULL */
nir_loop *loop;
/* The last instruction inserted into this block. This is used as we
* traverse the instructions and insert them back into the program to
* put them in the right order.
@@ -80,27 +93,63 @@ struct gcm_state {
struct gcm_instr_info *instr_infos;
};
static unsigned
get_loop_instr_count(struct exec_list *cf_list)
{
unsigned loop_instr_count = 0;
foreach_list_typed(nir_cf_node, node, node, cf_list) {
switch (node->type) {
case nir_cf_node_block: {
nir_block *block = nir_cf_node_as_block(node);
nir_foreach_instr(instr, block) {
loop_instr_count++;
}
break;
}
case nir_cf_node_if: {
nir_if *if_stmt = nir_cf_node_as_if(node);
loop_instr_count += get_loop_instr_count(&if_stmt->then_list);
loop_instr_count += get_loop_instr_count(&if_stmt->else_list);
break;
}
case nir_cf_node_loop: {
nir_loop *loop = nir_cf_node_as_loop(node);
loop_instr_count += get_loop_instr_count(&loop->body);
break;
}
default:
unreachable("Invalid CF node type");
}
}
return loop_instr_count;
}
/* Recursively walks the CFG and builds the block_info structure */
static void
gcm_build_block_info(struct exec_list *cf_list, struct gcm_state *state,
unsigned loop_depth)
nir_loop *loop, unsigned loop_depth,
unsigned loop_instr_count)
{
foreach_list_typed(nir_cf_node, node, node, cf_list) {
switch (node->type) {
case nir_cf_node_block: {
nir_block *block = nir_cf_node_as_block(node);
state->blocks[block->index].loop_depth = loop_depth;
state->blocks[block->index].loop_instr_count = loop_instr_count;
state->blocks[block->index].loop = loop;
break;
}
case nir_cf_node_if: {
nir_if *if_stmt = nir_cf_node_as_if(node);
gcm_build_block_info(&if_stmt->then_list, state, loop_depth);
gcm_build_block_info(&if_stmt->else_list, state, loop_depth);
gcm_build_block_info(&if_stmt->then_list, state, loop, loop_depth, ~0u);
gcm_build_block_info(&if_stmt->else_list, state, loop, loop_depth, ~0u);
break;
}
case nir_cf_node_loop: {
nir_loop *loop = nir_cf_node_as_loop(node);
gcm_build_block_info(&loop->body, state, loop_depth + 1);
gcm_build_block_info(&loop->body, state, loop, loop_depth + 1,
get_loop_instr_count(&loop->body));
break;
}
default:
@@ -342,6 +391,46 @@ gcm_schedule_early_instr(nir_instr *instr, struct gcm_state *state)
nir_foreach_src(instr, gcm_schedule_early_src, state);
}
static bool
set_block_for_loop_instr(struct gcm_state *state, nir_instr *instr,
nir_block *block)
{
if (nir_block_dominates(instr->block, block))
return true;
/* If the loop only executes a single time i.e its wrapped in a:
* do{ ... break; } while(true)
* Don't move the instruction as it will not help anything.
*/
nir_loop *loop = state->blocks[instr->block->index].loop;
if (loop->info->limiting_terminator == NULL && !loop->info->complex_loop &&
nir_block_ends_in_break(nir_loop_last_block(loop)))
return false;
/* Being too aggressive with how we pull instructions out of loops can
* result in extra register pressure and spilling. For example its fairly
* common for loops in compute shaders to calculate SSBO offsets using
* the workgroup id, subgroup id and subgroup invocation, pulling all
* these calculations outside the loop causes register pressure.
*
* To work around these issues for now we only allow constant and texture
* instructions to be moved outside their original loops, or instructions
* where the total loop instruction count is less than
* MAX_LOOP_INSTRUCTIONS.
*
* TODO: figure out some more heuristics to allow more to be moved out of
* loops.
*/
if (state->blocks[instr->block->index].loop_instr_count < MAX_LOOP_INSTRUCTIONS)
return true;
if (instr->type == nir_instr_type_load_const ||
instr->type == nir_instr_type_tex)
return true;
return false;
}
static nir_block *
gcm_choose_block_for_instr(nir_instr *instr, nir_block *early_block,
nir_block *late_block, struct gcm_state *state)
@@ -350,22 +439,9 @@ gcm_choose_block_for_instr(nir_instr *instr, nir_block *early_block,
nir_block *best = late_block;
for (nir_block *block = late_block; block != NULL; block = block->imm_dom) {
/* Being too aggressive with how we pull instructions out of loops can
* result in extra register pressure and spilling. For example its fairly
* common for loops in compute shaders to calculate SSBO offsets using
* the workgroup id, subgroup id and subgroup invocation, pulling all
* these calculations outside the loop causes register pressure.
*
* To work around these issues for now we only allow constant and texture
* instructions to be moved outside their original loops.
*
* TODO: figure out some heuristics to allow more to be moved out of loops.
*/
if (state->blocks[block->index].loop_depth <
state->blocks[best->index].loop_depth &&
(nir_block_dominates(instr->block, block) ||
instr->type == nir_instr_type_load_const ||
instr->type == nir_instr_type_tex))
set_block_for_loop_instr(state, instr, block))
best = block;
else if (block == instr->block)
best = block;
@@ -557,10 +633,12 @@ gcm_place_instr(nir_instr *instr, struct gcm_state *state)
}
static bool
opt_gcm_impl(nir_function_impl *impl, bool value_number)
opt_gcm_impl(nir_shader *shader, nir_function_impl *impl, bool value_number)
{
nir_metadata_require(impl, nir_metadata_block_index |
nir_metadata_dominance);
nir_metadata_require(impl, nir_metadata_loop_analysis,
shader->options->force_indirect_unrolling);
/* A previous pass may have left pass_flags dirty, so clear it all out. */
nir_foreach_block(block, impl)
@@ -575,7 +653,7 @@ opt_gcm_impl(nir_function_impl *impl, bool value_number)
exec_list_make_empty(&state.instrs);
state.blocks = rzalloc_array(NULL, struct gcm_block_info, impl->num_blocks);
gcm_build_block_info(&impl->body, &state, 0);
gcm_build_block_info(&impl->body, &state, NULL, 0, ~0u);
gcm_pin_instructions(impl, &state);
@@ -610,7 +688,8 @@ opt_gcm_impl(nir_function_impl *impl, bool value_number)
ralloc_free(state.instr_infos);
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
nir_metadata_dominance |
nir_metadata_loop_analysis);
return state.progress;
}
@@ -622,7 +701,7 @@ nir_opt_gcm(nir_shader *shader, bool value_number)
nir_foreach_function(function, shader) {
if (function->impl)
progress |= opt_gcm_impl(function->impl, value_number);
progress |= opt_gcm_impl(shader, function->impl, value_number);
}
return progress;