* then we can use that to minimize the value of Add(x, const) or
* Sub(Const, x). In particular this often avoids 1 instruction in some
* backends for the Shift(x, Sub(Const, y)) case because it can be replaced
* then we can use that to minimize the value of Add(x, const) or
* Sub(Const, x). In particular this often avoids 1 instruction in some
* backends for the Shift(x, Sub(Const, y)) case because it can be replaced