The LangRef describes preserve_mostcc and preserve_allcc as experimental, to be used by a future version of the ObjectiveC runtime, possibly useful for other runtimes, and supported only on X86-64 but with the intention to support more architectures. AArch64 already has an implementation of preserve_mostcc.
I’d be interested in using preserve_allcc on AArch64. I’m writing to ask:
Is anybody already working on that?
If not, and I implement it, should I expect that upstreaming it would meet with approval? (wanted to check that e.g. it’s not slated for deprecation)
Any gotchas I should be aware of?