make debug comment more explicit

2016-01-28  Abderrazek Zaafrani  <a.zaafrani@samsung.com>

	* graphite-optimize-isl.c (optimize_isl): Print a different debug
	message when isl does not return a valid schedule.

From-SVN: r232935

gcc/ChangeLog

+2016-01-28  Abderrazek Zaafrani  <a.zaafrani@samsung.com>
+
+	* graphite-optimize-isl.c (optimize_isl): Print a different debug
+	message when isl does not return a valid schedule.
+
 2016-01-28  Sebastian Pop  <s.pop@samsung.com>
 
 	* graphite-isl-ast-to-gimple.c (class translate_isl_ast_to_gimple):

gcc/graphite-optimize-isl.c

@@ -477,8 +477,15 @@ optimize_isl (scop_p scop)
   if (!schedule || isl_ctx_last_error (scop->isl_context) == isl_error_quota)
     {
       if (dump_file && dump_flags)
-	fprintf (dump_file, "isl timed out --param max-isl-operations=%d\n",
-		 max_operations);
+	{
+	  if (!schedule)
+	    fprintf (dump_file, "isl did not return any schedule.\n",
+		     max_operations);
+	  else
+	    fprintf (dump_file, "isl timed out --param max-isl-operations=%d\n",
+		     max_operations);
+	}
+
       if (schedule)
 	isl_schedule_free (schedule);
       return false;