pmux2shiftx - transform $pmux cells to $shiftx cells

yosys> help pmux2shiftx
pmux2shiftx [options] [selection]
This pass transforms $pmux cells to $shiftx cells.
-v, -vv
verbose output
-min_density <percentage>
specifies the minimum density for the shifter
default: 50
-min_choices <int>
specified the minimum number of choices for a control signal
default: 3
-onehot ignore|pmux|shiftx
select strategy for one-hot encoded control signals
default: pmux
disable $sub inference for "range decoders"