[PATCH] D136753: [DemandedBits] Add Div instruction to DetermineLiveOperandBits

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

In D136753#3915555 <https://reviews.llvm.org/D136753#3915555>, @t.p.northover wrote:

> I don't think this is how division works. It mixes bits up far more than add/sub/mul for which a bit in the input can only affect equal or lower ones in the output.

This is why I wanted to see an exhaustive test, its more subtle than the current attempt - but there's definitely a case for a suitable demanded bitmask of the lower bits based off the number of common known leading sign/zero bits of the arguments.


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