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

[David Sherwood via llvm-commits]

david-arm wrote:

There was a buildbot failure after landing this PR (https://lab.llvm.org/buildbot/#/builders/193/builds/16567) which is unfortunate because the bug relates to a fragile test (that can change depending upon target rounding behaviour). I have a PR to fix the test here: https://github.com/llvm/llvm-project/pull/201580

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