adjust SLP tree dumping

This also dumps the root node we eventually smuggle in.

2020-03-20  Richard Biener  <rguenther@suse.de>

	* tree-vect-slp.c (vect_analyze_slp_instance): Dump SLP tree
	from the possibly modified root.

gcc/ChangeLog

+2020-03-20  Richard Biener  <rguenther@suse.de>
+
+	* tree-vect-slp.c (vect_analyze_slp_instance): Dump SLP tree
+	from the possibly modified root.
+
 2020-03-20  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>
             Andre Vieira  <andre.simoesdiasvieira@arm.com>
             Mihail Ionescu  <mihail.ionescu@arm.com>

gcc/tree-vect-slp.c

@@ -2435,7 +2435,8 @@ vect_analyze_slp_instance (vec_info *vinfo,
 	    {
 	      dump_printf_loc (MSG_NOTE, vect_location,
 			       "Final SLP tree for instance:\n");
-	      vect_print_slp_tree (MSG_NOTE, vect_location, node);
+	      vect_print_slp_tree (MSG_NOTE, vect_location,
+				   SLP_INSTANCE_TREE (new_instance));
 	    }
 
 	  return true;