profile-count.h (profile_count::split): Give better result when splitting…

profile-count.h (profile_count::split): Give better result when splitting profile_probability::always.


	* profile-count.h (profile_count::split): Give better result when
	splitting profile_probability::always.

From-SVN: r266584

gcc/ChangeLog

+2018-11-28  Jan Hubicka  <jh@suse.cz>
+
+	* profile-count.h (profile_count::split): Give better result when
+	splitting profile_probability::always.
+
 2018-11-28  Vladimir Makarov  <vmakarov@redhat.com>
 
 	PR target/88207

gcc/profile-count.h

@@ -447,8 +447,12 @@ public:
     {
       profile_probability ret = *this * cprob;
       /* The following is equivalent to:
-         *this = cprob.invert () * *this / ret.invert ();  */
-      *this = (*this - ret) / ret.invert ();
+         *this = cprob.invert () * *this / ret.invert ();
+	 Avoid scaling when overall outcome is supposed to be always.
+	 Without knowing that one is inverse of toher, the result would be
+	 conservative.  */
+      if (!(*this == profile_probability::always ()))
+        *this = (*this - ret) / ret.invert ();
       return ret;
     }