re PR middle-end/56977 (gcc -Og incorrectly warns about 'constant zero length parameter')

2013-06-25  Richard Biener  <rguenther@suse.de>

	PR middle-end/56977
	* passes.c (init_optimization_passes): Move pass_fold_builtins
	and pass_dce earlier with -Og.

	* gcc.dg/pr56977.c: New testcase.

From-SVN: r200391

gcc/ChangeLog

+2013-06-25  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/56977
+	* passes.c (init_optimization_passes): Move pass_fold_builtins
+	and pass_dce earlier with -Og.
+
 2013-06-25  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* expr.c (expand_expr_real_1) <ARRAY_REF>: Fix formatting glitches.

gcc/passes.c

@@ -1536,15 +1536,15 @@ init_optimization_passes (void)
       /* Perform simple scalar cleanup which is constant/copy propagation.  */
       NEXT_PASS (pass_ccp);
       NEXT_PASS (pass_object_sizes);
+      /* Fold remaining builtins.  */
+      NEXT_PASS (pass_fold_builtins);
       /* Copy propagation also copy-propagates constants, this is necessary
-         to forward object-size results properly.  */
+         to forward object-size and builtin folding results properly.  */
       NEXT_PASS (pass_copy_prop);
+      NEXT_PASS (pass_dce);
       NEXT_PASS (pass_asan);
       NEXT_PASS (pass_tsan);
       NEXT_PASS (pass_rename_ssa_copies);
-      NEXT_PASS (pass_dce);
-      /* Fold remaining builtins.  */
-      NEXT_PASS (pass_fold_builtins);
       /* ???  We do want some kind of loop invariant motion, but we possibly
          need to adjust LIM to be more friendly towards preserving accurate
 	 debug information here.  */

gcc/testsuite/ChangeLog

+2013-06-25  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/56977
+	* gcc.dg/pr56977.c: New testcase.
+
 2013-06-24  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/57358

gcc/testsuite/gcc.dg/pr56977.c

+/* { dg-do compile } */
+/* { dg-options "-Og" } */
+
+__attribute__((__error__("error"))) void error ();
+
+void f (int i) {
+    if (__builtin_constant_p (i)) {
+	error ();
+    }
+}