Yes, we have plans to propose our LLVM Xtensa back-end to upstream, but it's a quite long process, because there is several stages to promote new back-end to the official mode and each stage may took monthes Great! And yes I know the process can take quite some time. However, even an experimental b...

This is great news!
Are there plans to get this backend upstreamed after it has been rebased? I'm working on porting Go to microcontrollers (see tinygo.org) and I would really like to support this chip as well. Having it upstream would make it much easier to add support.