muxcover - cover trees of MUX cells with wider MUXes

yosys> help muxcover

muxcover [options] [selection]

Cover trees of $_MUX_ cells with $_MUX{4,8,16}_ cells

-mux4[=cost], -mux8[=cost], -mux16[=cost]

Cover $_MUX_ trees using the specified types of MUXes (with optional
integer costs). If none of these options are given, the effect is the
same as if all of them are.
Default costs: $_MUX4_ = 220, $_MUX8_ = 460,
               $_MUX16_ = 940

-mux2=cost

Use the specified cost for $_MUX_ cells when making covering decisions.
Default cost: $_MUX_ = 100

-dmux=cost

Use the specified cost for $_MUX_ cells used in decoders.
Default cost: 90

-nodecode

Do not insert decoder logic. This reduces the number of possible
substitutions, but guarantees that the resulting circuit is not
less efficient than the original circuit.

-nopartial

Do not consider mappings that use $_MUX<N>_ to select from less
than <N> different signals.