builtins.c (fold_builtin_1): Delete free (0).

2010-04-30  Richard Guenther  <rguenther@suse.de>

	* builtins.c (fold_builtin_1): Delete free (0).

	* gcc.dg/tree-ssa/builtin-free.c: New testcase.

From-SVN: r158923

gcc/ChangeLog

+2010-04-30  Richard Guenther  <rguenther@suse.de>
+
+	* builtins.c (fold_builtin_1): Delete free (0).
+
 2010-04-29  Jan HUbicka  <jh@suse.cz>
 
 	* gengtype.c (open_base_files): Add lto-streamer.h

gcc/builtins.c

@@ -9817,7 +9817,6 @@ fold_builtin_1 (location_t loc, tree fndecl, tree arg0, bool ignore)
   enum built_in_function fcode = DECL_FUNCTION_CODE (fndecl);
   switch (fcode)
     {
-
     case BUILT_IN_CONSTANT_P:
       {
 	tree val = fold_builtin_constant_p (arg0);
@@ -10199,6 +10198,11 @@ fold_builtin_1 (location_t loc, tree fndecl, tree arg0, bool ignore)
     case BUILT_IN_VPRINTF:
       return fold_builtin_printf (loc, fndecl, arg0, NULL_TREE, ignore, fcode);
 
+    case BUILT_IN_FREE:
+      if (integer_zerop (arg0))
+	return build_empty_stmt (loc);
+      break;
+
     default:
       break;
     }

gcc/testsuite/ChangeLog

+2010-04-30  Richard Guenther  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/builtin-free.c: New testcase.
+
 2010-04-29  Fabien Chêne  <fabien.chene@gmail.com>
 
 	PR c++/43890

gcc/testsuite/gcc.dg/tree-ssa/builtin-free.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+void bar (void *);
+void foo(unsigned n)
+{
+  void *p = __builtin_malloc (n);
+  if (p)
+    {
+      bar (p);
+      __builtin_free (p);
+      p = 0;
+    }
+  __builtin_free (p);
+}
+
+/* We should remove the redundant call to free.  */
+
+/* { dg-final { scan-tree-dump-times "free" 1 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */