pan/bi: Use a dynarray for predecessors

This is deterministic, unlike a set. Note we need the extra dereferencing to
keep the macro safe, simple, and standards compliant:

1. Nesting two for-loops would cause break/continue to fail.
2. Declaring variables outside the loop would pollute the namespace.
3. Declaring an anonymous struct is not conformant and doesn't compile in clang.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16279>

src/panfrost/bifrost/bi_helper_invocations.c

@@ -143,8 +143,8 @@ bi_propagate_pass_flag(bi_block *block)
         block->pass_flags = 1;
 
         bi_foreach_predecessor(block, pred) {
-                if (pred->pass_flags == 0)
-                        bi_propagate_pass_flag(pred);
+                if ((*pred)->pass_flags == 0)
+                        bi_propagate_pass_flag(*pred);
         }
 }
 
@@ -243,7 +243,7 @@ bi_analyze_helper_requirements(bi_context *ctx)
 
                 if (bi_helper_block_update(deps, blk)) {
                         bi_foreach_predecessor(blk, pred)
-                                bi_worklist_push_head(&worklist, pred);
+                                bi_worklist_push_head(&worklist, *pred);
                 }
         }
 

src/panfrost/bifrost/bi_liveness.c

@@ -121,7 +121,7 @@ bi_compute_liveness(bi_context *ctx)
                  */
                 if (liveness_block_update(blk, temp_count)) {
                         bi_foreach_predecessor(blk, pred)
-                                bi_worklist_push_head(&worklist, pred);
+                                bi_worklist_push_head(&worklist, *pred);
                 }
         }
 

src/panfrost/bifrost/bi_opt_dce.c

@@ -133,7 +133,7 @@ bi_postra_liveness(bi_context *ctx)
                  */
                 if (bi_postra_liveness_block(blk)) {
                         bi_foreach_predecessor(blk, pred)
-                                bi_worklist_push_head(&worklist, pred);
+                                bi_worklist_push_head(&worklist, *pred);
                 }
         }
 

src/panfrost/bifrost/bi_print.c

@@ -177,11 +177,11 @@ bi_print_block(bi_block *block, FILE *fp)
                         fprintf(fp, "block%u ", succ->index);
         }
 
-        if (block->predecessors->entries) {
+        if (bi_num_predecessors(block)) {
                 fprintf(fp, " from");
 
                 bi_foreach_predecessor(block, pred)
-                        fprintf(fp, " block%u", pred->index);
+                        fprintf(fp, " block%u", (*pred)->index);
         }
 
         if (block->scheduled) {

src/panfrost/bifrost/bi_scoreboard.c

@@ -252,8 +252,8 @@ scoreboard_block_update(bi_block *blk)
         /* pending_in[s] = sum { p in pred[s] } ( pending_out[p] ) */
         bi_foreach_predecessor(blk, pred) {
                 for (unsigned i = 0; i < BI_NUM_SLOTS; ++i) {
-                        blk->scoreboard_in.read[i] |= pred->scoreboard_out.read[i];
-                        blk->scoreboard_in.write[i] |= pred->scoreboard_out.write[i];
+                        blk->scoreboard_in.read[i] |= (*pred)->scoreboard_out.read[i];
+                        blk->scoreboard_in.write[i] |= (*pred)->scoreboard_out.write[i];
                 }
         }
 

src/panfrost/bifrost/bi_test.h

@@ -41,10 +41,7 @@ bit_builder(void *memctx)
 
         bi_block *blk = rzalloc(ctx, bi_block);
 
-        blk->predecessors = _mesa_set_create(blk,
-                        _mesa_hash_pointer,
-                        _mesa_key_pointer_equal);
-
+        util_dynarray_init(&blk->predecessors, blk);
         list_addtail(&blk->link, &ctx->blocks);
         list_inithead(&blk->instructions);
 

src/panfrost/bifrost/bifrost_compile.c

@@ -88,7 +88,7 @@ bi_block_add_successor(bi_block *block, bi_block *successor)
                 }
 
                 block->successors[i] = successor;
-                _mesa_set_add(successor->predecessors, block);
+                util_dynarray_append(&successor->predecessors, bi_block *, block);
                 return;
         }
 
@@ -3539,9 +3539,7 @@ create_empty_block(bi_context *ctx)
 {
         bi_block *blk = rzalloc(ctx, bi_block);
 
-        blk->predecessors = _mesa_set_create(blk,
-                        _mesa_hash_pointer,
-                        _mesa_key_pointer_equal);
+        util_dynarray_init(&blk->predecessors, blk);
 
         return blk;
 }

src/panfrost/bifrost/bir.c

@@ -222,8 +222,7 @@ bi_reconverge_branches(bi_block *block)
 
         /* Must have at least one successor */
         struct bi_block *succ = block->successors[0];
-        assert(succ->predecessors);
 
         /* Reconverge if the successor has multiple predecessors */
-        return (succ->predecessors->entries > 1);
+        return bi_num_predecessors(succ) > 1;
 }

src/panfrost/bifrost/compiler.h

@@ -663,7 +663,7 @@ typedef struct bi_block {
 
         /* Control flow graph */
         struct bi_block *successors[2];
-        struct set *predecessors;
+        struct util_dynarray predecessors;
         bool unconditional_jumps;
 
         /* Per 32-bit word live masks for the block indexed by node */
@@ -684,11 +684,17 @@ typedef struct bi_block {
         uint8_t pass_flags;
 } bi_block;
 
+static inline unsigned
+bi_num_predecessors(bi_block *block)
+{
+        return util_dynarray_num_elements(&block->predecessors, bi_block *);
+}
+
 static inline bi_block *
 bi_start_block(struct list_head *blocks)
 {
         bi_block *first = list_first_entry(blocks, bi_block, link);
-        assert(first->predecessors->entries == 0);
+        assert(bi_num_predecessors(first) == 0);
         return first;
 }
 
@@ -969,16 +975,8 @@ bi_node_to_index(unsigned node, unsigned node_count)
                 v != NULL && _v < &blk->successors[2]; \
                 _v++, v = *_v) \
 
-/* Based on set_foreach, expanded with automatic type casts */
-
 #define bi_foreach_predecessor(blk, v) \
-        struct set_entry *_entry_##v; \
-        bi_block *v; \
-        for (_entry_##v = _mesa_set_next_entry(blk->predecessors, NULL), \
-                v = (bi_block *) (_entry_##v ? _entry_##v->key : NULL);  \
-                _entry_##v != NULL; \
-                _entry_##v = _mesa_set_next_entry(blk->predecessors, _entry_##v), \
-                v = (bi_block *) (_entry_##v ? _entry_##v->key : NULL))
+        util_dynarray_foreach(&(blk)->predecessors, bi_block *, v)
 
 #define bi_foreach_src(ins, v) \
         for (unsigned v = 0; v < ARRAY_SIZE(ins->src); ++v)