[llvm] [AArch64] Treat NOP as a separate instruction. (PR #170968)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

OK - for bolt. Sounds good.

We usually don't generate these for codegen (usually we use alignment directives instead). If we were adding them, and the instruction had no side-effects and no inputs/outputs, what is to stop it from being removed? It looks like it is only the late positions in the pipelines of the current uses that is preventing it?

https://github.com/llvm/llvm-project/pull/170968