feat: Deduplicate localize method for Step.sol

[pcw109550]

Description

Upstream cannon directly embeds PreimageKeyLib methods to its step contract. By including library functions(which only holds internal methods), bytecodes of localize method will be stored in step contract and called by JUMP instruction.

In asterisc's case, this change is nontrivial because entire Step method is implemented in yul. Previous PRs relied on duplication of implementation inside of STF code.

I found a workaround; define wrapper method which calls localize method from the library. The compiler thinks this method is not used by anywhere when it is not declared as public method, so explicitly mark as public. After that, delegatecall the method, to preserve msg.sender.

However after finding this approach, It feels like it is overly complicated. Should we allow duplications and copy-paste localize implementation, by closing this PR?

Is there any better method while deduplication?

Tests

EVM mode tests will cover this diff.

Additional context

Current dependencies on/for this PR:

• master
  • PR feat: Fetch PreimageOracle from upstream #13
    • PR feat: Deduplicate localize method for Step.sol #12 (this PR)

[ImTei]

I think the problem is that the gas cost of delegateCall is a bit expensive and someone can feel confused when reading the code. It may be worth If the duplicated code is more complicated or written in solidity, but it isn't. so I think it's ok to reuse same code for localize(). wdyt?

[clabby]

Should we allow duplications and copy-paste localize implementation, by closing this PR?

Yes, this is fine. The Preimage localization isn't too complex, just a few lines of code - I'd opt for duplicating the code rather than adding complexity here.

[pcw109550]

Thanks for everyone's feedback: Agree with all of you and will close this.