yosys/tests/ice40/counter.ys

read_verilog counter.v
hierarchy -top top
proc
flatten
equiv_opt -map +/ice40/cells_sim.v synth_ice40 # equivalency check
design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
cd top # Constrain all select calls below inside the top module
select -assert-count 6 t:SB_CARRY
select -assert-count 8 t:SB_DFFR
select -assert-count 8 t:SB_LUT4
select -assert-none t:SB_CARRY t:SB_DFFR t:SB_LUT4 %% t:* %D