[llvm] [PeepholeOptimizer] Recognize new move-immediate instructions (PR #72128)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Perhaps other targets never create sequences where a move-immediate feeds into another move? Perhaps AMDGPU should not create them either?

For the most part, we shouldn't. I think in general this is the class of problem that RegBankSelect or follow up optimizations should be avoiding before selection. It might make sense to preserve this pattern in rare situations with multiple uses of the constant 


https://github.com/llvm/llvm-project/pull/72128