[llvm-branch-commits] [llvm] Backport ARM64EC variadic args fixes to LLVM 18 (PR #81800)

[Eli Friedman via llvm-branch-commits]

efriedma-quic wrote:

I was sort of waiting until the discussion on #80994 resolves... we might end up reverting parts of #80595 .

I guess it won't do any harm to land as-is, though.

https://github.com/llvm/llvm-project/pull/81800