nir/cf: handle jumps better in stitch_blocks()

In particular, handle the case where the earlier block ends in a jump
and the later block is empty. In that case, we want to preserve the jump
and remove any traces of the later block. Before, we would only hit this
case when removing a control flow node after a jump, which wasn't a
common occurance, but we'll need it to handle inserting a control flow
list which ends in a jump, which should be more common/useful.

Signed-off-by: Connor Abbott <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 16 insertions, 6 deletions

diff --git a/src/glsl/nir/nir_control_flow.c b/src/glsl/nir/nir_control_flow.c
index 1f2a681f258..8a4a0bf5f9d 100644
--- a/src/glsl/nir/nir_control_flow.c
+++ b/src/glsl/nir/nir_control_flow.c
@@ -706,14 +706,24 @@ stitch_blocks(nir_block *before, nir_block *after)
     * TODO: special case when before is empty and after isn't?
     */
 
-   move_successors(after, before);
+   if (block_ends_in_jump(before)) {
+      assert(exec_list_is_empty(&after->instr_list));
+      if (after->successors[0])
+         remove_phi_src(after->successors[0], after);
+      if (after->successors[1])
+         remove_phi_src(after->successors[1], after);
+      unlink_block_successors(after);
+      exec_node_remove(&after->cf_node.node);
+   } else {
+      move_successors(after, before);
 
-   foreach_list_typed(nir_instr, instr, node, &after->instr_list) {
-      instr->block = before;
-   }
+      foreach_list_typed(nir_instr, instr, node, &after->instr_list) {
+         instr->block = before;
+      }
 
-   exec_list_append(&before->instr_list, &after->instr_list);
-   exec_node_remove(&after->cf_node.node);
+      exec_list_append(&before->instr_list, &after->instr_list);
+      exec_node_remove(&after->cf_node.node);
+   }
 }