aco: fix reset_block_regs() in postRA-optimizer

Accidentally, we picked the index of the predecessors instead of the predecessors.

Totals from 8496 (6.30% of 134913) affected shaders: (GFX10.3)
CodeSize: 64070724 -> 64022516 (-0.08%); split: -0.08%, +0.00%
Instrs: 11932750 -> 11920698 (-0.10%); split: -0.10%, +0.00%
Latency: 144040266 -> 144017062 (-0.02%); split: -0.02%, +0.00%
InvThroughput: 29327735 -> 29326421 (-0.00%); split: -0.00%, +0.00%

Fossil DB stats on Rembrandt (RDNA2):
Totals from 4488 (3.33% of 134906) affected shaders:
CodeSize: 42759736 -> 42735392 (-0.06%); split: -0.06%, +0.00%
Instrs: 7960522 -> 7954436 (-0.08%); split: -0.08%, +0.00%
Latency: 96192647 -> 96172571 (-0.02%); split: -0.02%, +0.00%
InvThroughput: 19313576 -> 19312575 (-0.01%); split: -0.01%, +0.00%

Fixes: 75967a4814be7988afc20e59bac4b48bafacab00 ('aco/optimizer_postRA: Speed up reset_block() with predecessors.')
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16161>

diff --git a/src/amd/compiler/aco_optimizer_postRA.cpp b/src/amd/compiler/aco_optimizer_postRA.cpp
index 8ced375..59c0d12 100644 (file)
--- a/src/amd/compiler/aco_optimizer_postRA.cpp
+++ b/src/amd/compiler/aco_optimizer_postRA.cpp
@@ -89,13 +89,14 @@ struct pr_opt_ctx {
 
       /* Mark overwritten if it doesn't match with other predecessors. */
       const unsigned until_reg = min_reg + num_regs;
-      for (unsigned pred = 1; pred < num_preds; ++pred) {
-         for (unsigned i = min_reg; i < until_reg; ++i) {
-            Idx& idx = instr_idx_by_regs[block_index][i];
+      for (unsigned i = 1; i < num_preds; ++i) {
+         unsigned pred = preds[i];
+         for (unsigned reg = min_reg; reg < until_reg; ++reg) {
+            Idx& idx = instr_idx_by_regs[block_index][reg];
             if (idx == overwritten_untrackable)
                continue;
 
-            if (idx != instr_idx_by_regs[pred][i])
+            if (idx != instr_idx_by_regs[pred][reg])
                idx = overwritten_untrackable;
          }
       }