[llvm] [Transforms][Utils] Add LoopSplitUtils for iteration-space loop splitting (PR #205995)

[Ashutosh Nema via llvm-commits]

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nema-ashutosh wrote:

when the latch uses an eq/ne predicate and the recurrence carries neither nsw nor nuw, we genuinely can't tell whether the iteration ordering is signed or unsigned, so the current code bails out with return false instead of silently assuming unsigned.

https://github.com/llvm/llvm-project/pull/205995