[llvm] [LV] Implement integer part of VPDerivedIV cost model (PR #198252)

[David Sherwood via llvm-commits]

david-arm wrote:

It sounds like whatever transformation https://github.com/llvm/llvm-project/pull/149047 is doing in VectorCombine we need to be doing in the loop vectoriser, or at least recognising that the loop is less expensive than it appears.

https://github.com/llvm/llvm-project/pull/198252