re PR rtl-optimization/31391 (undefined label with -O -g due to cfglayout)

	PR rtl-optimization/31391
	* cfgcleanup.c (try_optimize_cfg): If a removed label is turned
	into a DELETED_LABEL note, and the label is in an empty basic
	block, update BB_END as well as BB_HEAD.

From-SVN: r123406

gcc/ChangeLog

+2007-04-01  Steven Bosscher  <steven@gcc.gnu.org>
+
+	PR rtl-optimization/31391
+	* cfgcleanup.c (try_optimize_cfg): If a removed label is turned
+	into a DELETED_LABEL note, and the label is in an empty basic
+	block, update BB_END as well as BB_HEAD.
+
 2007-04-01  Richard Henderson  <rth@redhat.com>
 
 	PR tree-optimization/31169

gcc/cfgcleanup.c

@@ -2034,6 +2034,8 @@ try_optimize_cfg (int mode)
 
 		      reorder_insns_nobb (label, label, bb_note);
 		      BB_HEAD (b) = bb_note;
+		      if (BB_END (b) == bb_note)
+			BB_END (b) = label;
 		    }
 		  if (dump_file)
 		    fprintf (dump_file, "Deleted label in block %i.\n",