[llvm] [MachineLICM] Use `RegisterClassInfo::getRegPressureSetLimit` (PR #119826)

[Nikita Popov via llvm-commits]

nikic wrote:

I've reverted this in https://github.com/llvm/llvm-project/commit/eeac0ffaf46cf9f9b0f680b9940cc4b68a0286d8, because it causes a very large compile-time regression, see https://llvm-compile-time-tracker.com/compare.php?from=e3e26dc41a6ad78c35a1a723cd77f5db8599797d&to=b4e17d4a314ed87ff6b40b4b05397d4b25b6636a&stat=instructions:u.

If you need a test case for analysis, a good one is probably k.cc from kimwitu++, which regresses by more than 6%.

https://github.com/llvm/llvm-project/pull/119826