[PATCH] D63065: [InstSimplify] Fix addo/subo undef folds (PR42209)

[Nikita Popov via Phabricator via llvm-commits]

nikic abandoned this revision.
nikic added a comment.

Sorry, I'm still not convinced. Alive evaluates a single atomic with_overflow operation by computing the operation result and the overflow flag independently, which is usually okay but in my eyes not right when it comes to undef modeling, because it artificially increases the number of undef users over what exists in IR. (For reference, some of the discussion is in https://github.com/AliveToolkit/alive2/issues/71.)

I'll leave this to someone else. Undef and I clearly don't get along...


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