cellmatch - match cells to their targets in cell library

yosys> help cellmatch

cellmatch -lib <design> [module selection]

This pass identifies functionally equivalent counterparts between each of the
selected modules and a module from the secondary design <design>. For every such
correspondence found, a techmap rule is generated for mapping instances of the
former to instances of the latter. This techmap rule is saved in yet another
design called '$cellmatch', which is created if non-existent.

This pass restricts itself to combinational modules. Modules are functionally
equivalent as long as their truth tables are identical upto a permutation of
inputs and outputs. The supported number of inputs is limited to 6.