opt_lut_ins - discard unused LUT inputs

yosys> help opt_lut_ins
opt_lut_ins [options] [selection]
This pass removes unused inputs from LUT cells (that is, inputs that can not
influence the output signal given this LUT's value).  While such LUTs cannot
be directly emitted by ABC, they can be a result of various post-ABC
transformations, such as mapping wide LUTs (not all sub-LUTs will use the
full set of inputs) or optimizations such as xilinx_dffopt.
-tech <technology>
Instead of generic $lut cells, operate on LUT cells specific
to the given technology.  Valid values are: xilinx, lattice, gowin.