[PATCH] D100917: [NewPM] Only invalidate modified functions' analyses in CGSCC passes

Tue May 4 10:21:45 PDT 2021

mtrofin added a comment.

In D100917#2736702 <https://reviews.llvm.org/D100917#2736702>, @aeubanks wrote:

> In D100917#2735651 <https://reviews.llvm.org/D100917#2735651>, @nikic wrote:
>
>> An unfortunate side-effect of this change is that NewPM uses even more memory. tramp3d-v4 is up 20% in max-rss (https://llvm-compile-time-tracker.com/compare.php?from=4ef1f90e4d564b872e3598ccef45adb740eb0f0d&to=d14d84af2f5ebb8ae2188ce6884a29a586dc0a40&stat=max-rss)
>
> Hmm that is a concern. I'm not sure how we want to balance memory vs compile times. Any thoughts?

(Drive-by thought) - maybe this is because a bunch of analyses that are needed during function simplification aren't needed anymore after. We could quickly check by adding a pass at the end of all function simplification, module-wide, that clears all fct analyses, and see if the memory overhead is still there?

If that's the case, we could identify what's not needed after function simplification and scope it somehow in a less hacky way than my above suggestion.

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  https://reviews.llvm.org/D100917/new/

https://reviews.llvm.org/D100917