swift

21a4bc51 - [AutoDiff] Fix differentiability witness SIL serialization. (#28463)

[AutoDiff] Fix differentiability witness SIL serialization. (#28463) - Create `SILSerializer::DifferentiabilityWitnessesToEmit` to track differentiability witnesses referenced by `differentiability_witness_function` instructions. These witnesses need to be serialized. - Move differentiability witness serialization before SIL function serialization but after visiting SIL functions (`differentiability_witness_function` instructions). - Use `-emit-sorted-sil` in test/AutoDiff/sil_differentiability_witness.sil for deterministic ordering for printing and deserialization.