Do not perform optimization in case of overflows.

This fixes opt/fehler222.c.

ir/ir/iropt.c

@@ -4080,23 +4080,32 @@ static ir_node *transform_node_Cmp(ir_node *n)
 				ir_node *lr = get_binop_right(left);
 				if (is_Shr(ll) && is_Const(lr)) {
 					/* Cmp((x >>u c1) & c2, c3) = Cmp(x & (c2 << c1), c3 << c1) */
-					ir_node *block = get_nodes_block(n);
-					ir_mode *mode = get_irn_mode(left);
-
 					ir_node *llr = get_Shr_right(ll);
-					if (is_Const(llr)) {
-						dbg_info *dbg = get_irn_dbg_info(left);
-						ir_graph *irg = get_irn_irg(left);
-
-						ir_tarval *c1    = get_Const_tarval(llr);
-						ir_tarval *c2    = get_Const_tarval(lr);
-						ir_tarval *c3    = get_Const_tarval(right);
-						ir_tarval *mask  = tarval_shl(c2, c1);
-						ir_tarval *value = tarval_shl(c3, c1);
 
-						left  = new_rd_And(dbg, block, get_Shr_left(ll), new_r_Const(irg, mask), mode);
-						right = new_r_Const(irg, value);
-						changed = true;
+					if (is_Const(llr)) {
+						ir_tarval *c1 = get_Const_tarval(llr);
+						ir_tarval *c2 = get_Const_tarval(lr);
+						ir_tarval *c3 = get_Const_tarval(right);
+
+						assert(tarval_is_long(c1));
+						ir_mode *mode = get_irn_mode(left);
+						long     l1   = get_tarval_long(c1);
+						long     h2   = get_tarval_highest_bit(c2);
+						long     h3   = get_tarval_highest_bit(c3);
+						long     bits = get_mode_size_bits(mode);
+
+						if (l1 + h2 < bits && l1 + h3 < bits) {
+							dbg_info *dbg   = get_irn_dbg_info(left);
+							ir_graph *irg   = get_irn_irg(left);
+							ir_node  *block = get_nodes_block(n);
+
+							ir_tarval *mask  = tarval_shl(c2, c1);
+							ir_tarval *value = tarval_shl(c3, c1);
+
+							left    = new_rd_And(dbg, block, get_Shr_left(ll), new_r_Const(irg, mask), mode);
+							right   = new_r_Const(irg, value);
+							changed = true;
+						}
 					}
 				}
 			}