[llvm] [SLP]Add runtime stride support for strided loads. (PR #81517)

[Philip Reames via llvm-commits]

https://github.com/preames approved this pull request.

LGTM

I'll comment that I find the guess and check style logic used in this patch to be very confusing without clear comments as to exactly what's going on.  I think you could make this much clearer if you used appropriate variable names, or at least some clear comments about the point where you transfer from best effort guessing to checking your result and relying on it's correctness.  

https://github.com/llvm/llvm-project/pull/81517