commit 57c9fc3cbaf59320d397df840d3004a58335aa04
author Jason Ekstrand <jason@jlekstrand.net> Wed Sep 23 15:54:08 2020 -0500
committer Marge Bot <eric+marge@anholt.net> Wed Sep 30 16:46:11 2020 +0000
tree 1efaf7799ebe69ba1f78f37f9b791e3d94e7f40e
parent 7749983658ec32ead48f0557d5661df91ca3a60c

nir/lower_goto_ifs: Always include level dom_frontiers in prev_frontier

When we come in from some other level or from the parent, we need to
ensure that the reach set is in prev_frontier but we also need to
consider the dominance frontier of our level.  Otherwise, we may end up
leaving out possible blocks when computing the reach of a level.

Acked-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6750>

src/compiler/nir/nir_lower_goto_ifs.c

diff --git a/src/compiler/nir/nir_lower_goto_ifs.c b/src/compiler/nir/nir_lower_goto_ifs.c
index 9b842a9..f5532e0 100644
--- a/src/compiler/nir/nir_lower_goto_ifs.c
+++ b/src/compiler/nir/nir_lower_goto_ifs.c
@@ -738,28 +738,20 @@
 
       struct set *prev_frontier = NULL;
       if (!prev_level) {
-         prev_frontier = reach;
+         prev_frontier = _mesa_set_clone(reach, curr_level);
       } else if (prev_level->irreducible) {
-         prev_frontier = prev_level->reach;
-      } else {
-         set_foreach(curr_level->blocks, blocks_entry) {
-            nir_block *level_block = (nir_block *) blocks_entry->key;
-            if (curr_level->blocks->entries == 1) {
-               /* If we only have one block, there's no union operation and we
-                * can just use the one from the one block.
-                */
-               prev_frontier = level_block->dom_frontier;
-               break;
-            }
+         prev_frontier = _mesa_set_clone(prev_level->reach, curr_level);
+      }
 
-            if (prev_frontier == NULL) {
-               prev_frontier =
-                  _mesa_set_clone(level_block->dom_frontier, prev_level);
-            } else {
-               set_foreach(level_block->dom_frontier, entry)
-                  _mesa_set_add_pre_hashed(prev_frontier, entry->hash,
-                                           entry->key);
-            }
+      set_foreach(curr_level->blocks, blocks_entry) {
+         nir_block *level_block = (nir_block *) blocks_entry->key;
+         if (prev_frontier == NULL) {
+            prev_frontier =
+               _mesa_set_clone(level_block->dom_frontier, curr_level);
+         } else {
+            set_foreach(level_block->dom_frontier, entry)
+               _mesa_set_add_pre_hashed(prev_frontier, entry->hash,
+                                        entry->key);
          }
       }