Function of 

pub fn of(
    func: &Func,
    before: &[Inst],
    allocation: &Allocation,
    frame: &Frame,
    framed: &[(u32, i32, &[Range])],
) -> Vec<Kept>

Which declaration is where, over which instructions, or nothing at all for a function the answer cannot be given about. See the module documentation for which those are.

framed is the locals in the frame whose bytes they share with something else, as the declaration, how far the bytes are from the call frame address and where the local is wanted. Each of them is in the frame over that area and nowhere outside it, which is the same question as a spilled value and gets the same answer.