rs6000.c (output_cbranch): Don't statically predict branches if using guessed profile.

	* config/rs6000/rs6000.c (output_cbranch): Don't statically predict
	branches if using guessed profile.

From-SVN: r232945

gcc/ChangeLog

+2016-01-28  Pat Haugen  <pthaugen@us.ibm.com>
+
+	* config/rs6000/rs6000.c (output_cbranch): Don't statically predict
+	branches if using guessed profile.
+
 2016-01-28  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* graphite-optimize-isl.c (optimize_isl): Fix dump.

gcc/config/rs6000/rs6000.c

@@ -21432,14 +21432,15 @@ output_cbranch (rtx op, const char *label, int reversed, rtx_insn *insn)
       /* PROB is the difference from 50%.  */
       int prob = XINT (note, 0) - REG_BR_PROB_BASE / 2;
 
-      /* Only hint for highly probable/improbable branches on newer
-	 cpus as static prediction overrides processor dynamic
-	 prediction.  For older cpus we may as well always hint, but
+      /* Only hint for highly probable/improbable branches on newer cpus when
+	 we have real profile data, as static prediction overrides processor
+	 dynamic prediction.  For older cpus we may as well always hint, but
 	 assume not taken for branches that are very close to 50% as a
 	 mispredicted taken branch is more expensive than a
 	 mispredicted not-taken branch.  */
       if (rs6000_always_hint
 	  || (abs (prob) > REG_BR_PROB_BASE / 100 * 48
+	      && (profile_status_for_fn (cfun) != PROFILE_GUESSED)
 	      && br_prob_note_reliable_p (note)))
 	{
 	  if (abs (prob) > REG_BR_PROB_BASE / 20