[llvm] [AArch64] Avoid NEON ORR when NEON and SVE are unavailable (PR #93940)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic commented:

The code sequence here assumes there's no red zone; is that actually enforced somewhere?  Can we allocate a stack slot instead of modifying the stack pointer?

As an alternative, it might be possible to use an integer register here, but I guess allocating that might be a bit complicated.

https://github.com/llvm/llvm-project/pull/93940