[llvm] [PassBuilder] Run trivial loop unswitching after late function-simpli… (PR #215899)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Here are the compile-time tracker results: https://llvm-compile-time-tracker.com/compare.php?from=bcbe2e2dbc6c5ee44536aff93579fa0d8d7ed34f&to=4353feb4e455b6f3d82248f49f984ac69e842a3f&stat=instructions:u

Mostly in noise, for a few workloads there's a larger-than-noise increase, but still pretty small.

If all additional opportunities are from IndVars creating invariant checks in the loop, maybe it would be worth adjusting IndVars to create the simplified check in the preheader?

https://github.com/llvm/llvm-project/pull/215899