Thank you @leeexyz. Yeah, we can use tvm.tir.const or a new buffer. I means, it there any mechanism to prevent users using python variables within a if_scope. For example, error message to tell users to utilize tvm.tir.const since it’s quite easy to confuse the python variable with tvm Expr. It still works sometimes event thought we define some python variables within a if_scope. That really causes me a lot of trouble.