go-lang.c (go_langhook_post_options): Disable sibling calls by default.

	* go-lang.c (go_langhook_post_options): Disable sibling calls by
	default.

From-SVN: r205915

gcc/go/ChangeLog

+2013-12-11  Ian Lance Taylor  <iant@google.com>
+
+	* go-lang.c (go_langhook_post_options): Disable sibling calls by
+	default.
+
 2013-12-10  Ian Lance Taylor  <iant@google.com>
 
 	* Make-lang.in (check_go_parallelize): Test go-test.exp r* tests

gcc/go/go-lang.c

@@ -270,6 +270,10 @@ go_langhook_post_options (const char **pfilename ATTRIBUTE_UNUSED)
   if (flag_excess_precision_cmdline == EXCESS_PRECISION_DEFAULT)
     flag_excess_precision_cmdline = EXCESS_PRECISION_STANDARD;
 
+  /* Tail call optimizations can confuse uses of runtime.Callers.  */
+  if (!global_options_set.x_flag_optimize_sibling_calls)
+    global_options.x_flag_optimize_sibling_calls = 0;
+
   /* Returning false means that the backend should be used.  */
   return false;
 }