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

[Tom Stellard via llvm-branch-commits]

tstellar wrote:

Hi @dpaoliello  (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix.  When you are done, please add the release:note label to this PR.

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