Hi, I am using spm example for yosys and a custom liberty file, but as soon as I define the DFFs through "dfflibmap -liberty ..." the check pass returns 2 errors:

Checking module delayed_serial_adder...

Warning: Wire delayed_serial_adder.\y_out is used but has no driver.

Warning: Wire delayed_serial_adder.\last_carry is used but has no driver.

Checking module spm...

Found and reported 2 problems.

When I define "abc -liberty ..." the errors reduce to 1, but it is still there:

Checking module delayed_serial_adder...

Warning: Wire delayed_serial_adder.\y_out is used but has no driver.

Checking module spm...

Found and reported 1 problems.

Can someone help me with that?