read_rtlil opt_dff-simplify.il 
opt_dff

select -assert-count 8 t:$ne r:A_WIDTH=3 %i
select -assert-count 5 t:$ne r:A_WIDTH=2 %i

select -assert-none t:$ne r:A_WIDTH=13 %i
select -assert-none t:$ne r:A_WIDTH=14 %i
select -assert-none t:$ne r:A_WIDTH=15 %i
select -assert-none t:$ne r:A_WIDTH=10 %i
select -assert-none t:$ne r:A_WIDTH=12 %i
select -assert-none t:$ne r:A_WIDTH=11 %i