- Cache predicates in the same stage using a cached module.
- Introduce `DefUse::defUseVariableUpdate()` and use in `CallableReturns.qll`.
The updated file `csharp/ql/test/library-tests/cil/dataflow/Nullness.expected`
demonstrates why this is needed.
- Utilize CIL analysis in `Guards::nonNullValue()`.
- Analyze SSA definitions in `AlwaysNullExpr`, similar to `NonNullExpr`.