pan/mdg: Remove midgard_opt_copy_prop_reg

This is known broken code, and the fix is highly nontrivial. It isn't
doing terribly much for perf, so just rip off the band-aid. Prevents a
dEQP regression, and likely fixes bugs in real apps too.

total instructions in shared programs: 96640 -> 97089 (0.46%)
instructions in affected programs: 27831 -> 28280 (1.61%)
helped: 33
HURT: 301
helped stats (abs) min: 1 max: 6 x̄: 3.64 x̃: 5
helped stats (rel) min: 1.96% max: 10.00% x̄: 6.48% x̃: 7.94%
HURT stats (abs)   min: 1 max: 18 x̄: 1.89 x̃: 1
HURT stats (rel)   min: 0.46% max: 15.00% x̄: 3.17% x̃: 2.38%
95% mean confidence interval for instructions value: 1.09 1.59
95% mean confidence interval for instructions %-change: 1.80% 2.63%
Instructions are HURT.

total bundles in shared programs: 45615 -> 45612 (<.01%)
bundles in affected programs: 11257 -> 11254 (-0.03%)
helped: 121
HURT: 146
helped stats (abs) min: 1 max: 7 x̄: 2.34 x̃: 1
helped stats (rel) min: 1.22% max: 23.33% x̄: 7.85% x̃: 5.26%
HURT stats (abs)   min: 1 max: 17 x̄: 1.92 x̃: 2
HURT stats (rel)   min: 0.42% max: 25.00% x̄: 5.17% x̃: 3.85%
95% mean confidence interval for bundles value: -0.34 0.31
95% mean confidence interval for bundles %-change: -1.69% 0.23%
Inconclusive result (value mean confidence interval includes 0).

total quadwords in shared programs: 76662 -> 77275 (0.80%)
quadwords in affected programs: 20148 -> 20761 (3.04%)
helped: 28
HURT: 275
helped stats (abs) min: 1 max: 4 x̄: 1.54 x̃: 1
helped stats (rel) min: 0.43% max: 25.00% x̄: 4.89% x̃: 2.50%
HURT stats (abs)   min: 1 max: 12 x̄: 2.39 x̃: 2
HURT stats (rel)   min: 0.51% max: 28.57% x̄: 5.18% x̃: 4.26%
95% mean confidence interval for quadwords value: 1.80 2.25
95% mean confidence interval for quadwords %-change: 3.64% 4.86%
Quadwords are HURT.

total registers in shared programs: 7078 -> 7081 (0.04%)
registers in affected programs: 1028 -> 1031 (0.29%)
helped: 62
HURT: 70
helped stats (abs) min: 1 max: 2 x̄: 1.11 x̃: 1
helped stats (rel) min: 8.33% max: 50.00% x̄: 15.03% x̃: 12.50%
HURT stats (abs)   min: 1 max: 2 x̄: 1.03 x̃: 1
HURT stats (rel)   min: 8.33% max: 66.67% x̄: 20.13% x̃: 11.25%
95% mean confidence interval for registers value: -0.17 0.21
95% mean confidence interval for registers %-change: -0.14% 7.38%
Inconclusive result (value mean confidence interval includes 0).

total threads in shared programs: 5032 -> 5036 (0.08%)
threads in affected programs: 31 -> 35 (12.90%)
helped: 12
HURT: 6
helped stats (abs) min: 1 max: 2 x̄: 1.08 x̃: 1
helped stats (rel) min: 100.00% max: 100.00% x̄: 100.00% x̃: 100.00%
HURT stats (abs)   min: 1 max: 2 x̄: 1.50 x̃: 1
HURT stats (rel)   min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for threads value: -0.43 0.87
95% mean confidence interval for threads %-change: 13.82% 86.18%
Inconclusive result (value mean confidence interval includes 0).

total loops in shared programs: 19 -> 19 (0.00%)
loops in affected programs: 0 -> 0
helped: 0
HURT: 0

total spills in shared programs: 0 -> 2
spills in affected programs: 0 -> 2
helped: 0
HURT: 1

total fills in shared programs: 0 -> 15
fills in affected programs: 0 -> 15
helped: 0
HURT: 1

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10652>

2 files changed, 7 insertions, 37 deletions

diff --git a/src/panfrost/midgard/midgard_opt_copy_prop.c b/src/panfrost/midgard/midgard_opt_copy_prop.c
index 331c3d1dfa2..667440aea19 100644
--- a/src/panfrost/midgard/midgard_opt_copy_prop.c
+++ b/src/panfrost/midgard/midgard_opt_copy_prop.c
@@ -25,42 +25,6 @@
 #include "compiler.h"
 #include "midgard_ops.h"
 
-/* Special case for copypropagating the results of vectors */
-
-static bool
-midgard_opt_copy_prop_reg(compiler_context *ctx, midgard_block *block)
-{
-        bool progress = false;
-
-        mir_foreach_instr_in_block_safe(block, ins) {
-                if (ins->type != TAG_ALU_4) continue;
-                if (!OP_IS_MOVE(ins->op)) continue;
-                if (ins->is_pack) continue;
-
-                unsigned from = ins->src[1];
-                unsigned to = ins->dest;
-
-                if (!(to & PAN_IS_REG))  continue;
-                if (from & PAN_IS_REG) continue;
-
-                if (ins->has_inline_constant) continue;
-                if (ins->has_constants) continue;
-                if (mir_nontrivial_mod(ins, 1, true)) continue;
-                if (mir_nontrivial_outmod(ins)) continue;
-                if (!mir_single_use(ctx, from)) continue;
-
-                /* Ensure mask is continguous from 0 */
-                if (!(ins->mask & (1 << COMPONENT_X))) continue;
-                if (ins->mask & (ins->mask + 1)) continue;
-
-                mir_rewrite_index_dst(ctx, from, ins->dest);
-                mir_remove_instruction(ins);
-                progress |= true;
-        }
-
-        return progress;
-}
-
 bool
 midgard_opt_copy_prop(compiler_context *ctx, midgard_block *block)
 {
@@ -129,5 +93,5 @@ midgard_opt_copy_prop(compiler_context *ctx, midgard_block *block)
                 progress |= true;
         }
 
-        return progress | midgard_opt_copy_prop_reg(ctx, block);
+        return progress;
 }
diff --git a/src/panfrost/midgard/mir.c b/src/panfrost/midgard/mir.c
index 1ad223a554f..426eab8e812 100644
--- a/src/panfrost/midgard/mir.c
+++ b/src/panfrost/midgard/mir.c
@@ -98,6 +98,12 @@ mir_use_count(compiler_context *ctx, unsigned value)
                         ++used_count;
         }
 
+        if (ctx->blend_input == value)
+                ++used_count;
+
+        if (ctx->blend_src1 == value)
+                ++used_count;
+
         return used_count;
 }