[clang] [llvm] [AArch64] Support preserve_none calling convention (PR #91046)

[Diego Russo via cfe-commits]

diegorusso wrote:

We (CPython project) will use it for the new JIT. I'll be testing the current implementation and report back any issue. I don't think you need to revert the PR but please let me know when you create the new one to address the post-merge comments so I can test it again.

Thanks

https://github.com/llvm/llvm-project/pull/91046