[llvm] [BasicAA] Consider 'nneg' flag when comparing CastedValues (PR #94129)

[Nikita Popov via llvm-commits]

================
@@ -268,43 +268,59 @@ struct CastedValue {
   unsigned ZExtBits = 0;
   unsigned SExtBits = 0;
   unsigned TruncBits = 0;
+  bool IsNonNegative = false;
----------------
nikic wrote:

`/// Whether trunc(V) is non-negative.` Should clarify that this does not apply to `V`.

https://github.com/llvm/llvm-project/pull/94129