The module gethutil tried to provide identical output from APIs debug_trace* of latest geth as test vectors for zkevm-circuits.

The execution traces returned by geth omit some information like execution errors in some situations. Moreover you may want to inspect some intermediate values of the EVM execution for debugging purposes.

Print debugging can be easily achieved by replacing the dependency of go-ethereum by a local copy of the repository. Just clone go-ethereum into a folder next to the zkevm-circuits repository, and uncomment the following line in go.mod:

replace github.com/ethereum/go-ethereum => ../../go-ethereum

Now you can add print logs in your go-ethereum copy as necessary.