[llvm] [AMDGPU] - Fix non-deterministic compile issue (PR #126271)

[Jay Foad via llvm-commits]

jayfoad wrote:

Sounds reasonable, but I don't immediately see anything in #124327 which iterates over `RematDefToLiveInRegions`. How and where does that happen?

https://github.com/llvm/llvm-project/pull/126271