Local opt: -1 - x -> ~x.

[r21159]

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 85c5270..03d03d4 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -2321,6 +2321,15 @@ static ir_node *transform_node_Sub(ir_node *n) {
                        dbg_info *dbg = get_irn_dbg_info(n);
                        return new_rd_Conv(dbg, current_ir_graph, get_nodes_block(n), a, mode);
                }
+
+               if (mode == lmode                                     &&
+                   get_mode_arithmetic(mode) == irma_twos_complement &&
+                   is_Const(a)                                       &&
+                   get_Const_tarval(a) == get_mode_minus_one(mode)) {
+                       /* -1 - x -> ~x */
+                       dbg_info *dbg = get_irn_dbg_info(n);
+                       return new_rd_Not(dbg, current_ir_graph, get_nodes_block(n), b, mode);
+               }
        }
 
 restart: