diff mbox series

Do not make profile insane when it is not present at all

Message ID 20180110082310.GA14222@kam.mff.cuni.cz
State New
Headers show
Series Do not make profile insane when it is not present at all | expand

Commit Message

Jan Hubicka Jan. 10, 2018, 8:23 a.m. UTC 
Hi,
this patch makes ICE in the testcase in PR83575 go away, it however is not complete
fix.  The problem there is that bb-reorder messes up block partitioning when profile
is insane and we ICE on multiple hot-cold partition transitions.

This patch fixes the origin of insane profile that is caused by force_edge_cold
getting out of hand on uninitialized profile.

Martin liska has patch to fix partitining fixup in bb-reorder and I will take a look
why that one does not seem to remove the ICE incrementally.

Bootstrapped/regtested x86_64-linux, comitted.

Honza

	PR middle-end/83575
	* predict.c (force_edge_cold): Handle in more sane way edges
	with no prediction.
diff mbox series

Patch

Index: predict.c
===================================================================
--- predict.c	(revision 256390)
+++ predict.c	(working copy)
@@ -4040,6 +4040,10 @@  force_edge_cold (edge e, bool impossible
   edge e2;
   bool uninitialized_exit = false;
 
+  /* When branch probability guesses are not known, then do nothing.  */
+  if (!impossible && !e->count ().initialized_p ())
+    return;
+
   profile_probability goal = (impossible ? profile_probability::never ()
 			      : profile_probability::very_unlikely ());
 
@@ -4050,17 +4054,23 @@  force_edge_cold (edge e, bool impossible
   FOR_EACH_EDGE (e2, ei, e->src->succs)
     if (e2 != e)
       {
+	if (e->flags & EDGE_FAKE)
+	  continue;
 	if (e2->count ().initialized_p ())
 	  count_sum += e2->count ();
-	else
-	  uninitialized_exit = true;
 	if (e2->probability.initialized_p ())
 	  prob_sum += e2->probability;
+	else 
+	  uninitialized_exit = true;
       }
 
+  /* If we are not guessing profiles but have some other edges out,
+     just assume the control flow goes elsewhere.  */
+  if (uninitialized_exit)
+    e->probability = goal;
   /* If there are other edges out of e->src, redistribute probabilitity
      there.  */
-  if (prob_sum > profile_probability::never ())
+  else if (prob_sum > profile_probability::never ())
     {
       if (!(e->probability < goal))
 	e->probability = goal;
@@ -4100,8 +4110,7 @@  force_edge_cold (edge e, bool impossible
 	update_br_prob_note (e->src);
       if (e->src->count == profile_count::zero ())
 	return;
-      if (count_sum == profile_count::zero () && !uninitialized_exit
-	  && impossible)
+      if (count_sum == profile_count::zero () && impossible)
 	{
 	  bool found = false;
 	  if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))