[llvm-branch-commits] [llvm] release/21.x: [MachinePipeliner] Detect a cycle in PHI dependencies early on (#167095) (PR #171472)

[Ikhlas Ajbar via llvm-branch-commits]

iajbar wrote:

https://github.com/llvm/llvm-project/pull/170749 depends on this patch to be merged to fix the failing lit test CodeGen/Hexagon/phi-elim.ll

https://github.com/llvm/llvm-project/pull/171472