[PATCH] D110518: [SCEV] Prove isKnown(Non)Negative using CtxI when possible

Mon Sep 27 12:50:23 PDT 2021

nikic requested changes to this revision.
nikic added a comment.
This revision now requires changes to proceed.

In D110518#3023518 <https://reviews.llvm.org/D110518#3023518>, @mkazantsev wrote:

> Theoretically can be costly in terms of CT. Nikita, could you pls check?

Yeah, it is: https://llvm-compile-time-tracker.com/compare.php?from=02d425d09d9da6786500f7bc620fe615c1c2dbf6&to=6373f1816403f66a10407d4227895aaa3b3b85b2&stat=instructions +50% on ClamAV

I think we ran into this with pretty much all attempts to use more context-sensitive reasoning in SCEV, though this is probably the worst impact yet. Probably because this is doing a context-sensitive walk inside another context-sensitive walk.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110518/new/

https://reviews.llvm.org/D110518