Instead of passing raw u32's arround, this adds a new Phi wrapper struct
which is treated as opaque by most of the rest of the compiler. This is
similar to what we're already doing with Label and SSAValue. This also
gives us the opportunity to properly document NAK's phi model.
Reviewed-by: Mel Henning <mhenning@darkrefraction.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34994>
Faith Ekstrand
52dcb1c9c1