Alex MacLean d881bac6fa [BasicAA] Consider 'nneg' flag when comparing CastedValues (#94129) ...

Any of the `zext` bits in a `zext nneg` can be converted to `sext` but
when checking if casts are compatible `BasicAA` fails to take into
account `nneg`. This change adds tracking of `nneg` to the `CastedValue`
struct and ensures that `sext` and `zext` bits are treated as
interchangeable when either `CastedValue` has a `nneg`. When
distributing casted values in `GetLinearExpression` we conservatively
discard the `nneg` from the `CastedValue`, except in the case of `shl
nsw`, where we know the sign has not changed to negative.

2024-06-04 08:32:57 -07:00

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