scc - detect strongly connected components (logic loops)

    scc [options] [selection]

This command identifies strongly connected components (aka logic loops) in the

    -expect <num>
        expect to find exactly <num> SCCs. A different number of SCCs will
        produce an error.

    -max_depth <num>
        limit to loops not longer than the specified number of cells. This
        can e.g. be useful in identifying small local loops in a module that
        implements one large SCC.

        do not count cells that have their output fed back into one of their
        inputs as single-cell scc.

        Usually this command only considers internal non-memory cells. With
        this option set, all cells are considered. For unknown cells all ports
        are assumed to be bidirectional 'inout' ports.

    -set_attr <name> <value>
        set the specified attribute on all cells that are part of a logic
        loop. the special token {} in the value is replaced with a unique
        identifier for the logic loop.

        replace the current selection with a selection of all cells and wires
        that are part of a found logic loop

        examine specify rules to detect logic loops in whitebox/blackbox cells