Today I want to make some refactoring to the garbage that has become the src/opcodes/runners.ts file. It's currently 586 lines. I would like to split the runners by Opcode category, and I noticed that both evm.codes and the ethereum execution specs have a nice categorization of each opcode. I'm going to use that to split the runners into separate files.
Here are the instruction categories as defined here:
- Arithmetic
- Bitwise Logic
- Block
- Comparison
- Control Flow
- Environmental
- Keccak
- Logging
- Memory
- Stack
- Storage
- System
After this small refactoring, I proceeded with the next instructions: DELEGATECALL and STATICCALL. These are very similar to their CALL sibling, so most of the runner code was reused. There are some changes that make a huge difference when it comes to actual execution, and learning them by having to implement them manually was a great learning experience.
For instance, the STATICCALL Opcode required a new flag inside the MachineState struct: "static" now identifies if the current execution context is running in static mode. In this particular mode, the opcodes that change the global state of Ethereum are disallowed, for instance SSTORE and CREATE. What I didn't realize is that a simple CALL can be executed in static mode, but only if its context txData.value sent is equal to 0.
This course is making me appreciate the smart implementations baked in the EVM and the Ethereum protocol. I know I've said it already, but this has been a learning experience like no others for me. I'm really enjoying it.