[llvm] [LLVM][AMDGPU] AMDGPUInstCombineIntrinsic for *lane intrinsics (PR #99878)

[Matt Arsenault via llvm-commits]

arsenm wrote:

It's also possible for transforms based on uniformity to become incorrect later after code motion until we have convergence tokens wired up to prevent that 

https://github.com/llvm/llvm-project/pull/99878