[llvm] [AMDGPU] NFC: Provide RPTracker interface for external iterators (PR #93088)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> In the latest, I've ported over RP speculation code from the generic trackers to GCN Trackers. While this does introduce code duplication, I thought this to be the better approach than to try to support subreg liveness in generic speculation and introduce generic tracker copies per speculation.

The generic tracker really just should support subregister liveness 

https://github.com/llvm/llvm-project/pull/93088