BasicAA itself doesn't make use of AA metadata, but passes it through to recursive queries and makes it part of the cache key. Aliasing decisions that are based on AA metadata (i.e. TBAA and ScopedAA) are based *only* on AA metadata, so checking them with different pointer values or sizes is not useful, the result will always be the same.
By itself, this change is a mild compile-time improvement (https://llvm-compile-time-tracker.com/compare.php?from=93127a4d7350261ed9ee2ccaa9c369eda2b60198&to=f4d0c5f01dc446f0c40e8dd81e6b9e9b02217c4d&stat=instructions). However, the actual goal here is to remove the AA metadata from the cache key and thus reduce it's size significantly (from 96 to 32 bytes), which will be the more impactful change. I plan to do that as a followup, but could also include it here.