equiv_opt - prove equivalence for optimized circuit

yosys> help equiv_opt
equiv_opt [options] [command]
This command uses temporal induction to check circuit equivalence before and
after an optimization pass.
-run <from_label>:<to_label>
only run the commands between the labels (see below). an empty
from label is synonymous to the start of the command list, and empty to
label is synonymous to the end of the command list.
-map <filename>
expand the modules in this file before proving equivalence. this is
useful for handling architecture-specific primitives.
-blacklist <file>
Do not match cells or signals that match the names in the file
(passed to equiv_make).
produce an error if the circuits are not equivalent.
run clk2fflogic before equivalence checking.
run async2sync before equivalence checking.
enable modelling of undef states during equiv_induct.
disable running check before and after the command under test.
The following commands are executed by this verification command:

        hierarchy -auto-top
        design -save preopt
        check -assert    (unless -nocheck)
        check -assert    (unless -nocheck)
        design -stash postopt

        design -copy-from preopt  -as gold A:top
        design -copy-from postopt -as gate A:top

    techmap:    (only with -map)
        techmap -wb -D EQUIV -autoproc -map <filename> ...

        clk2fflogic    (only with -multiclock)
        async2sync     (only with -async2sync)
        equiv_make -blacklist <filename> ... gold gate equiv
        equiv_induct [-undef] equiv
        equiv_status [-assert] equiv

        design -load preopt