[llvm] [AArch64] Let patterns for NEON instructions check runtime mode. (PR #95560)

[Eli Friedman via llvm-commits]

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

If I'm understanding correctly, this makes "HasNEONorSME" mean "this target supports NEON encodings", and "HasNEON" means "this target supports NEON encodings, and the current configuration of the SME registers allows executing the full NEON instruction set".

I don't think I like these names... can we rename them in a followup?  Maybe use the same names as the Subtarget methods?

That said, the approach here makes sense.

https://github.com/llvm/llvm-project/pull/95560