Most of the other if-form pseudos of this type are implemented but this one was missing. .ifnes is the sibling to .ifeqs.
Looks good in general with a few comments.
Also, for future reference, please include full context in your patches. See the following link on how to get a full context in Phabricator:
Update comment to reflect that this parse .ifeqs and .ifnes.
This logic is specific to .ifeqs.
You'll need to conditionalize more of the code, if you'd like to reuse the function.