[llvm] [AMDGPU] Improved register pressure estimates for rescheduling (PR #213116)

[Jay Foad via llvm-commits]

jayfoad wrote:

The test you added fails in an EXPENSIVE_CHECKS build with:
```
*** Bad machine code: Multiple connected components in live interval ***
```
You should be able to reproduce this just by adding -verify-machineinstrs to the RUN line.

Please fix or revert.


https://github.com/llvm/llvm-project/pull/213116