box_derive [-base <base_module>] [-naming_attr <attr>] [selection]

As part of the assembly of the design hierarchy done by the 'hierarchy' command,
specializations of parametric modules are derived on demand: for each choice of
parameter values appearing in the design, a copy of the parametric module is
derived which is specialized to that choice.

This derivation process ignores blackboxes and whiteboxes (boxes). To supplement,
this 'box_derive' command can be used to request the derivation of modules based
on box instances appearing in the design, which is desirable in certain use
cases. Only the selected cells are considered as the instances that steer the
derivation process.

    -base <base_module>
        instead of deriving the module that directly corresponds to each box
        instance, derive a specialization of <base_module> (this option applies
        to all selected box cells)

    -naming_attr <attr>
        once a specialization is derived, use the value of the module attribute
        <attr> for a name which should be used for the derived module (this
        replaces the internal Yosys naming scheme in which the names of derived
        modules start with '$paramod$')