[llvm] [NVPTX] Avoid introducing unnecessary ProxyRegs and Movs in ISel (PR #120486)

[Alex MacLean via llvm-commits]

AlexMaclean wrote:

> > These nodes are all erased by a later pass
> 
> What pass does this?

NVPTXProxyRegErasure

https://github.com/llvm/llvm-project/pull/120486