From: Christoph Mallon <christoph.mallon@gmx.de>
Date: Thu, 14 Aug 2008 09:37:18 +0000 (+0000)
Subject: Local opt: -1 - x -> ~x.
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=5f2e3f9708d6440955a8142566625bb54d08159d;p=libfirm

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

[r21159]
---

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 85c527014..03d03d401 100644
--- 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: