[llvm] [PassBuilder] Remove LoopFullUnrollPass from before LoopVectorize in the FullLTO pipeline (PR #197176)

[Momchil Velikov via llvm-commits]

momchil-velikov wrote:

> Is it possible to add a phase ordering test that shows a situation where this is beneficial? This will help regressing on future pipeline changes.

Luckily there's already the quant_4x4 test, I just added an LTO RUN line here: https://github.com/llvm/llvm-project/pull/210088

That test passes on main. It also passes with this PR (vectorisation happens in pre-link stage).

It would fail with **only** https://github.com/llvm/llvm-project/pull/195886 applied, but it will pass (with a FileCheck variable rename) when **both** this and https://github.com/llvm/llvm-project/pull/195886 are applied.

https://github.com/llvm/llvm-project/pull/197176