#start: passes in the most common order.
#end: This replaces the processes
proc_clean # removes empty branches and processes
proc_rmdead # removes unreachable branches
proc_prune
proc_init # special handling of “initial” blocks
proc_arst # identifies modeling of async resets
proc_rom
proc_mux # converts decision trees to multiplexer networks
proc_dlatch
proc_dff # extracts registers from processes
proc_memwr
proc_clean # this should remove all the processes, provided all went fine
opt_expr -keepdc