+ /* Empty stages anywhere in the pipe are OK. Also we can be confident
+ * that if the linked_stages mask matches we are looking at the same
+ * linked program because a previous validation call to
+ * program_stages_all_active() will have already failed if two different
+ * programs with the sames stages linked are not active for all linked
+ * stages.
+ */
+ if (!cur || cur->data->linked_stages == prev_linked_stages)