ipa-pure-const.c (local_pure_const): Do NORETURN discovery.

	* ipa-pure-const.c (local_pure_const): Do NORETURN discovery.

	* testsuite/gcc.dg/noreturn-8.c: New testcase.

From-SVN: r160124

gcc/ChangeLog

 2010-06-01  Jan Hubicka  <jh@suse.cz>
 
+	* ipa-pure-const.c (local_pure_const): Do NORETURN discovery.
+
+2010-06-01  Jan Hubicka  <jh@suse.cz>
+
 	* tree-cfgcleanup.c (fixup_noreturn_call): Break out from ...;
 	remove return value.
 	(split_bbs_on_noreturn_calls) .... here.

gcc/ipa-pure-const.c

@@ -1362,6 +1362,27 @@ local_pure_const (void)
       && !warn_suggest_attribute_pure
       && skip)
     return 0;
+
+  /* First do NORETURN discovery.  */
+  if (!skip && !TREE_THIS_VOLATILE (current_function_decl)
+      && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0)
+    {
+      if (warn_missing_noreturn
+	  && !lang_hooks.missing_noreturn_ok_p (cfun->decl))
+	warning_at (DECL_SOURCE_LOCATION (cfun->decl), OPT_Wmissing_noreturn,
+		    "function might be possible candidate "
+		    "for attribute %<noreturn%>");
+      if (dump_file)
+        fprintf (dump_file, "Function found to be noreturn: %s\n",
+	         lang_hooks.decl_printable_name (current_function_decl, 2));
+
+      /* Update declaration and reduce profile to executed once.  */
+      TREE_THIS_VOLATILE (current_function_decl) = 1;
+      if (node->frequency > NODE_FREQUENCY_EXECUTED_ONCE)
+        node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;
+
+      changed = true;
+    }
   l = analyze_function (node, false);
 
   switch (l->pure_const_state)

gcc/testsuite/ChangeLog

 2010-05-31 Jan Hubicka  <jh@suse.cz>
 
+	* testsuite/gcc.dg/noreturn-8.c: New testcase.
+
+2010-05-31 Jan Hubicka  <jh@suse.cz>
+
 	* testsuite/gcc.dg/lto/noreturn-1_1.c: Remove dg-do annotations.
 	* testsuite/gcc.dg/lto/noreturn-1_0.c: Move it here.
 

gcc/testsuite/gcc.dg/noreturn-8.c

+/* { dg-do run } */
+/* { dg-options "-O2" } */
+void exit (int);
+void noreturn_autodetection_failed ();
+__attribute__ ((noinline))
+detect_noreturn ()
+{
+  exit (0);
+}
+int
+main (void)
+{
+  detect_noreturn ();
+  noreturn_autodetection_failed ();
+  return 0;
+}