Mesa (master): pan/bi: Only run DCE once

[GitLab Mirror]

Module: Mesa
Branch: master
Commit: 93cdb072a82334c30acdb66936f09ecfaa0b5484
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=93cdb072a82334c30acdb66936f09ecfaa0b5484

Author: Alyssa Rosenzweig <alyssa at collabora.com>
Date:   Tue Mar  2 20:22:26 2021 +0000

pan/bi: Only run DCE once

No more progress loop needed. I'm skeptical we really want a dataflow
approach long-term, though, this is annoyingly expensive.

No shader-db changes.

Signed-off-by: Alyssa Rosenzweig <alyssa at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9421>

---

 src/panfrost/bifrost/bi_opt_dce.c      | 29 ++++++++++++++---------------
 src/panfrost/bifrost/bifrost_compile.c |  9 +--------
 src/panfrost/bifrost/compiler.h        |  2 +-
 3 files changed, 16 insertions(+), 24 deletions(-)

diff --git a/src/panfrost/bifrost/bi_opt_dce.c b/src/panfrost/bifrost/bi_opt_dce.c
index 39fc5d7ad6c..fbed0df4350 100644
--- a/src/panfrost/bifrost/bi_opt_dce.c
+++ b/src/panfrost/bifrost/bi_opt_dce.c
@@ -33,18 +33,22 @@
  * encodings will result.)
  */
 
-bool
+void
 bi_opt_dead_code_eliminate(bi_context *ctx, bool soft)
 {
-        bool progress = false;
         unsigned temp_count = bi_max_temp(ctx);
 
         bi_invalidate_liveness(ctx);
         bi_compute_liveness(ctx);
 
-        bi_foreach_block(ctx, _block) {
+        bi_foreach_block_rev(ctx, _block) {
                 bi_block *block = (bi_block *) _block;
-                uint16_t *live = mem_dup(block->base.live_out, temp_count * sizeof(uint16_t));
+                uint16_t *live = rzalloc_array(_block, uint16_t, temp_count);
+
+                pan_foreach_successor(_block, succ) {
+                        for (unsigned i = 0; i < temp_count; ++i)
+                                live[i] |= succ->live_in[i];
+                }
 
                 bi_foreach_instr_in_block_safe_rev(block, ins) {
                         bool all_null = true;
@@ -52,24 +56,19 @@ bi_opt_dead_code_eliminate(bi_context *ctx, bool soft)
                         bi_foreach_dest(ins, d) {
                                 unsigned index = bi_get_node(ins->dest[d]);
 
-                                if (index < temp_count && !(live[index] & bi_writemask(ins, d))) {
+                                if (index < temp_count && !(live[index] & bi_writemask(ins, d)))
                                         ins->dest[d] = bi_null();
-                                        progress = true;
-                                }
 
                                 all_null &= bi_is_null(ins->dest[d]);
                         }
 
-                        if (all_null && !soft && !bi_side_effects(ins->op)) {
+                        if (all_null && !soft && !bi_side_effects(ins->op))
                                 bi_remove_instruction(ins);
-                                progress = true;
-                        }
-
-                        bi_liveness_ins_update(live, ins, temp_count);
+                        else
+                                bi_liveness_ins_update(live, ins, temp_count);
                 }
 
-                free(live);
+                ralloc_free(block->base.live_in);
+                block->base.live_in = live;
         }
-
-        return progress;
 }
diff --git a/src/panfrost/bifrost/bifrost_compile.c b/src/panfrost/bifrost/bifrost_compile.c
index 26ed1b53d1e..f662911fd96 100644
--- a/src/panfrost/bifrost/bifrost_compile.c
+++ b/src/panfrost/bifrost/bifrost_compile.c
@@ -3036,14 +3036,7 @@ bifrost_compile_shader_nir(nir_shader *nir,
         /* Runs before copy prop */
         bi_opt_push_ubo(ctx);
         bi_opt_copy_prop(ctx);
-
-        bool progress = false;
-
-        do {
-                progress = false;
-
-                progress |= bi_opt_dead_code_eliminate(ctx, false);
-        } while(progress);
+        bi_opt_dead_code_eliminate(ctx, false);
 
         bi_foreach_block(ctx, _block) {
                 bi_block *block = (bi_block *) _block;
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index d082a09949d..d2b1d414ccd 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -745,7 +745,7 @@ void bi_print_shader(bi_context *ctx, FILE *fp);
 /* BIR passes */
 
 void bi_opt_copy_prop(bi_context *ctx);
-bool bi_opt_dead_code_eliminate(bi_context *ctx, bool soft);
+void bi_opt_dead_code_eliminate(bi_context *ctx, bool soft);
 void bi_opt_push_ubo(bi_context *ctx);
 void bi_schedule(bi_context *ctx);
 void bi_assign_scoreboard(bi_context *ctx);