[llvm-branch-commits] [llvm] [release/18.x] Backport fixes for ARM64EC thunk generation (PR #92580)

[Daniel Paoliello via llvm-branch-commits]

dpaoliello wrote:

> @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.

Fixes issues where LLVM is either generating the incorrect thunk for a function with aligned parameters or didn't correctly pass through the return value when `StructRet` was used.

https://github.com/llvm/llvm-project/pull/92580