read_rtlil - read modules from RTLIL file

    read_rtlil [filename]

Load modules from an RTLIL file to the current design. (RTLIL is a text
representation of a design in yosys's internal format.)

    -nooverwrite
        ignore re-definitions of modules. (the default behavior is to
        create an error message if the existing module is not a blackbox
        module, and overwrite the existing module if it is a blackbox module.)

    -overwrite
        overwrite existing modules with the same name

    -lib
        only create empty blackbox modules