From: hubicka <hubicka@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 28 Nov 2018 20:34:06 +0000 (+0000)
Subject: 	* tree-ssa-ifcombine.c (update_profile_after_ifcombine): Handle
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02fa15302a63a5244d0e6e4859e44bf0d7685b00;p=thirdparty%2Fgcc.git

	* tree-ssa-ifcombine.c (update_profile_after_ifcombine): Handle
	profile_probability::always better.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@266585 138bc75d-0d04-0410-961f-82ee72b054a4
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3c1f926e239f..bc49105e219f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-11-28  Jan Hubicka  <jh@suse.cz>
+
+	* tree-ssa-ifcombine.c (update_profile_after_ifcombine): Handle
+	profile_probability::always better.
+
 2018-11-28  Jan Hubicka  <jh@suse.cz>
 
 	* profile-count.h (profile_count::split): Give better result when
diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
index b63c600c47b2..2b969378d650 100644
--- a/gcc/tree-ssa-ifcombine.c
+++ b/gcc/tree-ssa-ifcombine.c
@@ -360,8 +360,15 @@ update_profile_after_ifcombine (basic_block inner_cond_bb,
 
   inner_cond_bb->count = outer_cond_bb->count;
 
-  inner_taken->probability = outer2->probability + outer_to_inner->probability
-			     * inner_taken->probability;
+  /* Handle special case where inner_taken probability is always. In this case
+     we know that the overall outcome will be always as well, but combining
+     probabilities will be conservative because it does not know that
+     outer2->probability is inverse of outer_to_inner->probability.  */
+  if (inner_taken->probability == profile_probability::always ())
+    ;
+  else
+    inner_taken->probability = outer2->probability + outer_to_inner->probability
+			       * inner_taken->probability;
   inner_not_taken->probability = profile_probability::always ()
 				 - inner_taken->probability;