avoid using mode_Iu directly

[r23963]

ir/be/beabi.c

@@ -913,12 +913,12 @@ static ir_node *adjust_alloc(be_abi_irg_t *env, ir_node *alloc, ir_node *curr_sp
 
 	/* we might need to multiply the size with the element size */
 	if (type != firm_unknown_type && get_type_size_bytes(type) != 1) {
+		size = get_Alloc_size(alloc);
+		ir_mode *mode = get_irn_mode(size);
 		tarval *tv    = new_tarval_from_long(get_type_size_bytes(type),
-		                                     mode_Iu);
-		ir_node *cnst = new_rd_Const(dbg, irg, mode_Iu, tv);
-		ir_node *mul  = new_rd_Mul(dbg, irg, block, get_Alloc_size(alloc),
-		                           cnst, mode_Iu);
-		size = mul;
+		                                     mode);
+		ir_node *cnst = new_rd_Const(dbg, irg, mode, tv);
+		size          = new_rd_Mul(dbg, irg, block, size, cnst, mode);
 	} else {
 		size = get_Alloc_size(alloc);
 	}