hierarchy - check, expand and clean up design hierarchy

yosys> help hierarchy

hierarchy [-check] [-top <module>]

hierarchy -generate <cell-types> <port-decls>

In parametric designs, a module might exists in several variations with
different parameter values. This pass looks at all modules in the current
design and re-runs the language frontends for the parametric modules as
needed. It also resolves assignments to wired logic data types (wand/wor),
resolves positional module parameters, unrolls array instances, and more.

-check

also check the design hierarchy. this generates an error when
an unknown module is used as cell type.

-simcheck

like -check, but also throw an error if blackbox modules are
instantiated, and throw an error if the design has no top module.

-smtcheck

like -simcheck, but allow smtlib2_module modules.

-purge_lib

by default the hierarchy command will not remove library (blackbox)
modules. use this option to also remove unused blackbox modules.

-libdir <directory>

search for files named <module_name>.v in the specified directory
for unknown modules and automatically run read_verilog for each
unknown module.

-keep_positionals

per default this pass also converts positional arguments in cells
to arguments using port names. This option disables this behavior.

-keep_portwidths

per default this pass adjusts the port width on cells that are
module instances when the width does not match the module port. This
option disables this behavior.

-nodefaults

do not resolve input port default values

-nokeep_prints

per default this pass sets the "keep" attribute on all modules
that directly or indirectly display text on the terminal.
This option disables this behavior.

-nokeep_asserts

per default this pass sets the "keep" attribute on all modules
that directly or indirectly contain one or more formal properties.
This option disables this behavior.

-top <module>

use the specified top module to build the design hierarchy. Modules
outside this tree (unused modules) are removed.

when the -top option is used, the 'top' attribute will be set on the
specified top module. otherwise a module with the 'top' attribute set
will implicitly be used as top module, if such a module exists.

-auto-top

automatically determine the top of the design hierarchy and mark it.

-chparam name value

elaborate the top module using this parameter value. Modules on which
this parameter does not exist may cause a warning message to be output.
This option can be specified multiple times to override multiple
parameters. String values must be passed in double quotes (").

In -generate mode this pass generates blackbox modules for the given cell
types (wildcards supported). For this the design is searched for cells that
match the given types and then the given port declarations are used to
determine the direction of the ports. The syntax for a port declaration is:

    {i|o|io}[@<num>]:<portname>

Input ports are specified with the 'i' prefix, output ports with the 'o'
prefix and inout ports with the 'io' prefix. The optional <num> specifies
the position of the port in the parameter list (needed when instantiated
using positional arguments). When <num> is not specified, the <portname> can
also contain wildcard characters.

This pass ignores the current selection and always operates on all modules
in the current design.