[llvm] LoopVectorize: run verifyFunction once (PR #91470)

[Nikita Popov via llvm-commits]

nikic wrote:

Compile-time tracker results (for an assertion enabled build): https://llvm-compile-time-tracker.com/compare.php?from=67c18fe6ca0d491bde18dc7f8e7c6e32e52f4dbb&to=cbfebd1b531f905efde60c913c9dd35b6b161019&stat=instructions:u

And as a related curiosity, it seems like assertion-enabled builds have about ~50% mean overhead relative to normal release builds: https://llvm-compile-time-tracker.com/compare.php?from=e2d17a053edff68c9761aceb8ff8303e3e37172c&to=67c18fe6ca0d491bde18dc7f8e7c6e32e52f4dbb&stat=instructions:u

https://github.com/llvm/llvm-project/pull/91470