One of the things the flow does is take the PDK provided liberty file and trim out a bunch of cells before giving it to yosys/abc. The excluded cells are listed in runs/<date>/tmp/trimmed.lib.exclude.list. One of the things I am curious about is why are these gates trimmed? For example sky130_fd_sc_hd__dfxtp_1 is trimmed but sky130_fd_sc_hd__dfxtp_[24] are not. Maybe to keep ABC’s run time down?