[PATCH] D150922: [KnownBits] Return `0` for poison {s,u}div inputs

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added a comment.

In D150922#4357344 <https://reviews.llvm.org/D150922#4357344>, @nikic wrote:

> IMHO we shouldn't go out of the way to handle such cases -- if we need to handle this for other reasons (e.g. for shift amounts, or for conflicts) that's one thing, but explicitly checking for poison result for known constant cases is pretty pointless -- those will get folded to actual poison values by code that can do so.

The INT_MIN / -1 case isn't necessary, but the LHS.isZero() || RHS.isZero() cases reduce the number of
checks we need elsewhere (specifically now we know MinTZ < BitWidth)


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https://reviews.llvm.org/D150922