Debug

Currently, ExpanderCompilerCollection also supports debugging circuits. To use this feature, you need to make a few adjustments to your circuit definition:

At the beginning, in addition to frontend, you also need to include the contents of the frontend::extra module:

use expander_compiler::frontend::*;
use extra::*;

If you are using Sub-Circuit functions, you need to modify their type as follows:

fn sub_circuit_fn<C: Config, B: RootAPI<C>>(api: &mut B, x: &Vec<Variable>) -> Vec<Variable>

The Define implementation also requires modification (now we use GenericDefine):

impl GenericDefine<GF2Config> for YourCircuit<Variable> {
    fn define<Builder: RootAPI<GF2Config>>(&self, api: &mut Builder) {
        // definition of your circuit
    }
}

Finally, for compilation (similarly, compile_generic):

let compile_result = compile_generic(&YourCircuit::default()).unwrap();

When you need to debug, modify your main function to include the following code:

let mut assignment = YourCircuit::<GF2>::default();
// assign values in the assignment
debug_eval(&YourCircuit::default(), &assignment);

We have also introduced a new API that is only available during debugging:

pub trait DebugAPI<C: Config> {
    fn value_of(&self, x: impl ToVariableOrValue<C::CircuitField>) -> C::CircuitField;
}

Within debug_eval, you can use this API to retrieve the value of a variable and print it for debugging purposes.

For a complete example, please refer to keccak_gf2.rs.