[PATCH] D150425: [ValueTracking] deduce `X * Y != 0` if `LowestKnownBit(X) * LowestKnownBit(Y) != 0`

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added a comment.

In D150425#4340180 <https://reviews.llvm.org/D150425#4340180>, @nikic wrote:

> I find the formulation here kind of confusing. Wouldn't something like this be more obvious? https://alive2.llvm.org/ce/z/p5wWid

That works for the second proof, but not the first. We can't actually compute the LSB. Only the Lowest KnownBit.
Truthfully the first formula is enough for everything (as the arbitrary `x_subset` and `y_subset` include the set
of an known lowest bit).


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