[llvm] [KnownBits] Make nuw and nsw support in computeForAddSub optimal (PR #83382)

[Nikita Popov via llvm-commits]

nikic wrote:

This seems to add a good bit of compile-time overhead: http://llvm-compile-time-tracker.com/compare.php?from=2a67c28abe8cfde47c5058abbeb4b5ff9a393192&to=e383a7e50bf0b4303931ef119c856dcf53f3dd9e&stat=instructions%3Au 

https://github.com/llvm/llvm-project/pull/83382