From: Michael Beck <beck@ipd.info.uni-karlsruhe.de>
Date: Tue, 14 Aug 2007 14:39:40 +0000 (+0000)
Subject: Add x - (a+x) = -a
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=20149b146e357b48366f5e336fe4827d064779b5;p=libfirm

Add x - (a+x) = -a

[r15540]
---

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 698ba0384..22df8268f 100644
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -2023,6 +2023,8 @@ static ir_node *transform_node_Add(ir_node *n) {
  *   Sub(0,a)          -> Minus(a)
  *   Sub(Mul(a, x), a) -> Mul(a, x-1)
  *   Sub(Sub(x, y), b) -> Sub(x, Add(y,b))
+ *   Sub(Add(a, x), x) -> a
+ *   Sub(x, Add(x, a)) -> -a
  */
 static ir_node *transform_node_Sub(ir_node *n) {
 	ir_mode *mode;
@@ -2048,7 +2050,7 @@ restart:
 			ir_node *left  = get_Add_left(a);
 			ir_node *right = get_Add_right(a);
 
-			/* FIXME: Does the Conv's word only for two complement or generally? */
+			/* FIXME: Does the Conv's work only for two complement or generally? */
 			if (left == b) {
 				if (mode != get_irn_mode(right)) {
 					/* This Sub is an effective Cast */
@@ -2065,6 +2067,32 @@ restart:
 				DBG_OPT_ALGSIM1(oldn, a, b, n, FS_OPT_ADD_SUB);
 			}
 		}
+	} else if (is_Add(b)) {
+		if (mode_wrap_around(mode)) {
+			ir_node *left  = get_Add_left(b);
+			ir_node *right = get_Add_right(b);
+
+			/* FIXME: Does the Conv's work only for two complement or generally? */
+			if (left == a) {
+				ir_mode *r_mode = get_irn_mode(right);
+
+				n = new_r_Minus(get_irn_irg(n), get_irn_n(n, -1), right, r_mode);
+				if (mode != r_mode) {
+					/* This Sub is an effective Cast */
+					n = new_r_Conv(get_irn_irg(n), get_irn_n(n, -1), n, mode);
+				}
+				DBG_OPT_ALGSIM1(oldn, a, b, n, FS_OPT_ADD_SUB);
+			} else if (right == a) {
+				ir_mode *l_mode = get_irn_mode(left);
+
+				n = new_r_Minus(get_irn_irg(n), get_irn_n(n, -1), left, l_mode);
+				if (mode != l_mode) {
+ 					/* This Sub is an effective Cast */
+					n = new_r_Conv(get_irn_irg(n), get_irn_n(n, -1), n, mode);
+				}
+				DBG_OPT_ALGSIM1(oldn, a, b, n, FS_OPT_ADD_SUB);
+			}
+		}
 	} else if (mode_is_int(mode) && is_Conv(a) && is_Conv(b)) {
 		ir_mode *mode = get_irn_mode(a);