[llvm] [MachineScheduler][AMDGPU] Allow scheduling of single-MI regions (PR #128739)

[Nikita Popov via llvm-commits]

nikic wrote:

This has some compile-time impact (https://llvm-compile-time-tracker.com/compare.php?from=c0b5451129bba52e33cd7957d58af897a58d14c6&to=15e295d30aa356a0ab1d83e477375cf3ef314947&stat=instructions:u). Can we not do this on targets that don't need it?

https://github.com/llvm/llvm-project/pull/128739