[PATCH] D98422: [Alias] Add a ah-hoc pattern with two PHI for isKnownNonEqual

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

I think the main problem here is that the review tries doing too much. Yes, the BasicAA test case can be handled as a combination of simple phi handling plus some additional mul handling. But from the code comments and discussion the intention is to also handle some kind of additional case involving add recurrences.

It would be great if this patch can be cut down to just basic phi-phi handling, with dedicated ValueTracking tests -- even if that does not cover the motivational case in isolation.

As @reames has mentioned before, the code should also only recurse into one pair of operands, and require trivially non-equal constants for the rest. At least we have been following this rule in the rest of the isKnownNonEqual code.


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  https://reviews.llvm.org/D98422/new/

https://reviews.llvm.org/D98422