equiv_struct - structural equivalence checking

yosys> help equiv_struct
equiv_struct [options] [selection]
This command adds additional $equiv cells based on the assumption that the
gold and gate circuit are structurally equivalent. Note that this can introduce
bad $equiv cells in cases where the netlists are not structurally equivalent,
for example when analyzing circuits with cells with commutative inputs. This
command will also de-duplicate gates.
by default this command performans forward sweeps until nothing can
be merged by forwards sweeps, then backward sweeps until forward
sweeps are effective again. with this option set only forward sweeps
are performed.
-fwonly <cell_type>
add the specified cell type to the list of cell types that are only
merged in forward sweeps and never in backward sweeps. $equiv is in
this list automatically.
by default, the internal RTL and gate cell types are ignored. add
this option to also process those cell types with this command.
-maxiter <N>
maximum number of iterations to run before aborting