WDCM and WQCM: reset $of and $err

[acerone85]

[Link to related issue(s) here, if any]

Closes #791

[Short description of the changes.]

The specification requires that WDCM and WDQCM reset the $of and $err registers, but this was not the case.

Questions:

• Is this a breaking change?
• I could not find any test that I could look at for the changes. Are there any?

Checklist

• Breaking changes are clearly marked as such in the PR description and changelog
• New behavior is reflected in tests
• If performance characteristic of an instruction change, update gas costs as well or make a follow-up PR for that
• The specification matches the implemented behavior (link update PR if changes are needed)

Before requesting review

• I have reviewed the code myself
• I have created follow-up issues caused by this PR and linked them here

After merging, notify other teams

[Add or remove entries as needed]

• Rust SDK
• Sway compiler
• Platform documentation (for out-of-organization contributors, the person merging the PR will do this)
• Someone else?

[xgreenx]

It would be nice to add a test case for it

[acerone85]

It would be nice to add a test case for it

Yes, I'm just not sure how, I could not find where we test the opcodes in the source

[acerone85]

It would be nice to add a test case for it

4 Tests added, one for each possible combination of operand size and register to be checked).

[Dentosal]

Good test structure. I had some small suggestions, and the changelog needs fixing, but other than that seems good to go.

[xgreenx]

If I remove these lines, tests still passes

[acerone85]

Can confirm, but I don't have any idea why.
I have checked, and log does not reset the registers, so the only option is that the registers are reset already somewhere while executing the wideint compare instruction. Will check more in depth

[Dentosal]

It's because code generated by make_u128 and make_u256 used in the tests reset $err and $of as they use movi internally.

You should first create all values, and only after that call the opcodes that access flags.

[acerone85]

I wish I looked at this comment three hours ago :)

[acerone85]

fixed tests in 18b6008 and verified that they fail before applying the changes to the wideint cmp alu operation

Isues found by Green, will re-review