re PR middle-end/65950 (exit in main is causing the path to it to become unlikely.)

2016-10-18  Andrew Pinski  <apinski@cavium.com>

        PR tree-opt/65950
        * predict.c (is_exit_with_zero_arg): New function.
        (tree_bb_level_predictions): Don't consider paths leading to exit(0)
        as nottaken.

From-SVN: r241309

gcc/ChangeLog

+2016-10-18  Andrew Pinski  <apinski@cavium.com>
+
+	PR tree-opt/65950
+	* predict.c (is_exit_with_zero_arg): New function.
+	(tree_bb_level_predictions): Don't consider paths leading to exit(0)
+	as nottaken.
+
 2016-10-18  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/77991

gcc/predict.c

@@ -2512,6 +2512,21 @@ tree_predict_by_opcode (basic_block bb)
       }
 }
 
+/* Returns TRUE if the STMT is exit(0) like statement. */
+
+static bool
+is_exit_with_zero_arg (const gimple *stmt)
+{
+  /* This is not exit, _exit or _Exit. */
+  if (!gimple_call_builtin_p (stmt, BUILT_IN_EXIT)
+      && !gimple_call_builtin_p (stmt, BUILT_IN__EXIT)
+      && !gimple_call_builtin_p (stmt, BUILT_IN__EXIT2))
+    return false;
+
+  /* Argument is an interger zero. */
+  return integer_zerop (gimple_call_arg (stmt, 0));
+}
+
 /* Try to guess whether the value of return means error code.  */
 
 static enum br_predictor
@@ -2638,7 +2653,9 @@ tree_bb_level_predictions (void)
 
 	  if (is_gimple_call (stmt))
 	    {
-	      if (gimple_call_noreturn_p (stmt) && has_return_edges)
+	      if (gimple_call_noreturn_p (stmt)
+		  && has_return_edges
+		  && !is_exit_with_zero_arg (stmt))
 		predict_paths_leading_to (bb, PRED_NORETURN,
 					  NOT_TAKEN);
 	      decl = gimple_call_fndecl (stmt);