PR tree-optimization/38074

	* cgraphbuild.c (compute_call_stmt_bb_frequency): Fix handling of 0
	entry frequency.
	* predict.c (combine_predictions_for_bb): Ignore predictor predicting
	in both dirrection for first match heuristics.
	(tree_bb_level_predictions): Disable noreturn heuristic when there
	is no returning path.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@142517 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 38 insertions, 2 deletions

diff --git a/gcc/predict.c b/gcc/predict.c
index c6e933f5101..73dbcbdc4ce 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -820,8 +820,33 @@ combine_predictions_for_bb (basic_block bb)
 	    probability = REG_BR_PROB_BASE - probability;
 
 	  found = true;
+	  /* First match heuristics would be widly confused if we predicted
+	     both directions.  */
 	  if (best_predictor > predictor)
-	    best_probability = probability, best_predictor = predictor;
+	    {
+              struct edge_prediction *pred2;
+	      int prob = probability;
+
+              for (pred2 = (struct edge_prediction *) *preds; pred2; pred2 = pred2->ep_next)
+	       if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor)
+	         {
+	           int probability2 = pred->ep_probability;
+
+		   if (pred2->ep_edge != first)
+		     probability2 = REG_BR_PROB_BASE - probability2;
+
+		   if ((probability < REG_BR_PROB_BASE / 2) != 
+		       (probability2 < REG_BR_PROB_BASE / 2))
+		     break;
+
+		   /* If the same predictor later gave better result, go for it! */
+		   if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability))
+		       || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability)))
+		     prob = probability2;
+		 }
+	      if (!pred2)
+	        best_probability = prob, best_predictor = predictor;
+	    }
 
 	  d = (combined_probability * probability
 	       + (REG_BR_PROB_BASE - combined_probability)
@@ -1521,6 +1546,16 @@ static void
 tree_bb_level_predictions (void)
 {
   basic_block bb;
+  bool has_return_edges = false;
+  edge e;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
+    if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH)))
+      {
+        has_return_edges = true;
+	break;
+      }
 
   apply_return_prediction ();
 
@@ -1535,7 +1570,8 @@ tree_bb_level_predictions (void)
 
 	  if (is_gimple_call (stmt))
 	    {
-	      if (gimple_call_flags (stmt) & ECF_NORETURN)
+	      if ((gimple_call_flags (stmt) & ECF_NORETURN)
+	          && has_return_edges)
 		predict_paths_leading_to (bb, PRED_NORETURN,
 					  NOT_TAKEN);
 	      decl = gimple_call_fndecl (stmt);