freduce - perform functional reduction

yosys> help freduce
freduce [options] [selection]
This pass performs functional reduction in the circuit. I.e. if two nodes are
equivalent, they are merged to one node and one of the redundant drivers is
disconnected. A subsequent call to 'clean' will remove the redundant drivers.
-v, -vv
enable verbose or very verbose output
enable explicit handling of inverted signals
-stop <n>
stop after <n> reduction operations. this is mostly used for
debugging the freduce command itself.
-dump <prefix>
dump the design to <prefix>_<module>_<num>.il after each reduction
operation. this is mostly used for debugging the freduce command.
This pass is undef-aware, i.e. it considers don't-care values for detecting
equivalent nodes.

All selected wires are considered for rewiring. The selected cells cover the
circuit that is analyzed.