Since last update we continued to work on the project and update patches in Phabricator. Currently Xtensa backend is ported on LLVM release 15.0.0.
The process of reviewing patches in Phabricator also significantly accelerated. An additional five patches have been approved, for a total of 8 out of 10 patches now approved. We are updating the last two patches according to the comments and will publish them soon. Many thanks to @Sterling-Augustine and all participants!
This has been discussed a number of times, and I believe all previous discussions were generally positive towards inclusion of this target into LLVM. The linked thread already discussed how the target meets the policy to accept a new experimental target, and that all seems fine.
So, I think at this point, you only need to wait for the entire 10-patch series to be approved. After the last 2 patches have been reviewed and approved, I think you should be good to go!
Nice! That’s great to hear, and I’m sure it’ll be helpful for quite a few people to have this full ISA document publicly available. (Also, the name of the document makes me laugh – “Instruction Set Architecture Summary” – at 700 pages, that’s the longest summary I’ve ever seen!)