[llvm] [LoopIdiom] Perform loop versioning to use memcpy (PR #125043)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

This causes some substantial compile-time regressions: https://llvm-compile-time-tracker.com/compare.php?from=62bcbe62dd635ceaad25d2fb2c94e9914451dc99&to=69b5e923d1bbf900a53984f684c22d7b31c1db68&stat=instructions%3Au

If I'm reading this right, you are currently unconditionally computing LAA, even if you will not actually end up using it. Delaying that may help.

https://github.com/llvm/llvm-project/pull/125043