[llvm] [SCEV] Preserve flags in SCEVLoopGuardRewriter for add and mul. (PR #91472)

[Nikita Popov via llvm-commits]

nikic wrote:

> SCEVLoopGuardRewriter only replaces operands with equivalent values

But aren't the values only equivalent in the scope of the guards, while the generated expressions might potentially have a larger scope?

https://github.com/llvm/llvm-project/pull/91472