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

[Eli Friedman via llvm-branch-commits]

https://github.com/efriedma-quic approved this pull request.

LGTM

This only affects Arm64EC targets, the fixes are relatively small, and this affects correctness of generated thunks.

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