[llvm] [CodeGen][MachineLICM] Use RegUnits in HoistRegionPostRA (PR #94608)

[Pierre van Houtryve via llvm-commits]

Pierre-vh wrote:

It seems to be causing tiny regressions in some cases, but I think the change is worth it. I did some small optimizations in the previous commit to see if it helps.

At worst, we get +0.1% but at best, we get -1% in large AMDGPU programs due to how expensive RegAliasIterator is.

https://github.com/llvm/llvm-project/pull/94608