⚡️ Memory safe assembly

[axic]

Description

Mark assembly blocks memory-safe, so that they can be used with optimizer stages (for example the stack-to-memory elevation). See https://docs.soliditylang.org/en/v0.8.17/assembly.html?highlight=memory-safe#memory-safety for details.

I did spend quite some time manually reviewing each case in this codebase, but I don't feel confident merging this without at least 2 proper reviews (cc @hrkrshnn).

Checklist

Ensure you completed all of the steps below before submitting your pull request:

• Ran forge snapshot?
• Ran npm run lint?
• Ran forge test?

Pull requests with an incomplete checklist will be thrown out.

[hrkrshnn]

There can be dirty values at the end of the bytes btw.

Need to clean the last memory chunk here.

Take size to be 31 and have all the memory to be dirty. The last bit of the data would be dirty.

[axic]

Yes, that's correct, but shouldn't affect memory-safe?

[hrkrshnn]

Yeah. This is independently of memory safe. I'll separate it into a new issue.

[axic]

@transmissions11 ready for review, will squash once we get closer to merging.

[transmissions11]

isn't this (memory-safe) modifier for the assembly block only available in more recent versions of 0.8? since we want to maintain compatibility with all versions we should probably use the comment syntax, no?

[axic]

isn't this (memory-safe) modifier for the assembly block only available in more recent versions of 0.8? since we want to maintain compatibility with all versions we should probably use the comment syntax, no?

Good point, can change to that. Hmm, actually wonder how compatible that is given it starts with @solidity as a new natspec tag 😬

Btw, the assembly <string literal> {} syntax was valid since assembly was introduced, but it only accepted evmasm as the sole value plus the parenthesis syntax is new.

[axic]

@transmissions11 what is the earliest 0.8.x version do you want to support? There should be a CI run for that version, just to be sure.

[transmissions11]

@transmissions11 what is the earliest 0.8.x version do you want to support? There should be a CI run for that version, just to be sure.

This is a good point, ideally 0.8.0 itself. I'll open an issue.