[PATCH] D86262: [LoopIdiomRecognizePass] Options to disable part or the entire Loop Idiom Recognize Pass

[Nemanja Ivanovic via Phabricator via llvm-commits]

nemanjai added a comment.

I agree that the justification provided seems somewhat inadequate - using `memset/memcpy` as a canonical form and teaching DA to handle it seems quite reasonable. However, there are libraries that are highly tuned wrt. when to call these functions and when not to. So it seems to me perfectly reasonable to provide an option to disable this for such uses. For example, a function may perform a memcpy/memset operation on data that is known to only be called only from range-limited sites. The compiler (without PGO+LTO which are often not an option) cannot know that it should expand such calls in the back end.

However, I am not sure I agree with this being the best approach for the implementation. Presumably (now or in the future) there may be other places in this pass that produce memset/memcpy. Also, we will unnecessarily collect stores in in `collectStores()`. So it seems to me like it might be more advantageous to have these options prevent `isLegalStore()` from returning the corresponding store type.


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  https://reviews.llvm.org/D86262/new/

https://reviews.llvm.org/D86262