Fix tp_first_run update in split_function.

The value 0 in tp_first_run is special meaing that profile is unknown.  We
should not set it to 1.

	* ipa-split.c (split_function): Preserve 0 tp_first_run.

From-SVN: r279091

gcc/ChangeLog

 2019-12-07  Jan Hubicka  <hubicka@ucw.cz>
 
+	* ipa-split.c (split_function): Preserve 0 tp_first_run.
+
+2019-12-07  Jan Hubicka  <hubicka@ucw.cz>
+
 	* ipa-inline-analysis.c (do_estimate_edge_time): Silence overactive
 	sanity check.
 

gcc/ipa-split.c

@@ -1369,7 +1369,8 @@ split_function (basic_block return_bb, class split_point *split_point,
 
 
   /* Let's take a time profile for splitted function.  */
-  node->tp_first_run = cur_node->tp_first_run + 1;
+  if (cur_node->tp_first_run)
+    node->tp_first_run = cur_node->tp_first_run + 1;
 
   /* For usual cloning it is enough to clear builtin only when signature
      changes.  For partial inlining we however cannot expect the part