beloopana: Remove duplicate comments.

[libfirm] / ir / opt / fp-vrp.c

diff --git a/ir/opt/fp-vrp.c b/ir/opt/fp-vrp.c
index 3bee116..8f28622 100644 (file)
--- a/ir/opt/fp-vrp.c
+++ b/ir/opt/fp-vrp.c
@@ -1,20 +1,6 @@
 /*
- * Copyright (C) 1995-2010 University of Karlsruhe.  All right reserved.
- *
  * This file is part of libFirm.
- *
- * This file may be distributed and/or modified under the terms of the
- * GNU General Public License version 2 as published by the Free Software
- * Foundation and appearing in the file LICENSE.GPL included in the
- * packaging of this file.
- *
- * Licensees holding valid libFirm Professional Edition licenses may use
- * this file in accordance with the libFirm Commercial License.
- * Agreement provided with the Software.
- *
- * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
- * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE.
+ * Copyright (C) 2012 University of Karlsruhe.
  */
 
 /**
@@ -746,6 +732,24 @@ exchange_only:
                        break;
                }
 
+               case iro_Minus: {
+                       ir_mode *mode = get_irn_mode(irn);
+
+                       /* If all bits except the highest bit are zero the Minus is superfluous. */
+                       if (get_mode_arithmetic(mode) == irma_twos_complement) {
+                               ir_node         *const op  = get_Minus_op(irn);
+                               bitinfo   const *const b   = get_bitinfo(op);
+                               ir_tarval       *const min = get_mode_min(mode);
+
+                               if (b->z == min) {
+                                       DB((dbg, LEVEL_2, "%+F(%+F) is superfluous\n", irn, op));
+                                       exchange(irn, op);
+                                       env->modified = 1;
+                               }
+                       }
+                       break;
+               }
+
                case iro_Or: {
                        ir_node*       const l  = get_Or_left(irn);
                        ir_node*       const r  = get_Or_right(irn);