opt_lut - optimize LUT cells
opt_lut [options] [selection] This pass combines cascaded $lut cells with unused inputs. -dlogic <type>:<cell-port>=<LUT-input>[:<cell-port>=<LUT-input>...] preserve connections to dedicated logic cell <type> that has ports <cell-port> connected to LUT inputs <LUT-input>. this includes the case where both LUT and dedicated logic input are connected to the same constant. -limit N only perform the first N combines, then stop. useful for debugging.