implement 'x-(x&y) => x & ~y' localopt

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 0a97728..79d0960 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -2360,8 +2360,8 @@ restart:
        }
 
        if (get_mode_arithmetic(mode) == irma_twos_complement) {
+               /* c - ~X = X + (c+1) */
                if (is_Const(a) && is_Not(b)) {
-                       /* c - ~X = X + (c+1) */
                        ir_tarval *tv = get_Const_tarval(a);
 
                        tv = tarval_add(tv, get_mode_one(mode));
@@ -2374,6 +2374,24 @@ restart:
                                return n;
                        }
                }
+               /* x-(x&y) = x & ~y */
+               if (is_And(b)) {
+                       ir_node *and_left  = get_And_left(b);
+                       ir_node *and_right = get_And_right(b);
+                       if (and_right == a) {
+                               ir_node *tmp = and_left;
+                               and_left  = and_right;
+                               and_right = tmp;
+                       }
+                       if (and_left == a) {
+                               dbg_info *dbgi  = get_irn_dbg_info(n);
+                               ir_node  *block = get_nodes_block(n);
+                               ir_mode  *mode  = get_irn_mode(n);
+                               ir_node  *notn  = new_rd_Not(dbgi, block, and_right, mode);
+                               ir_node  *and   = new_rd_And(dbgi, block, a, notn, mode);
+                               return and;
+                       }
+               }
        }
        return n;
 }  /* transform_node_Sub */