A customized source-to-object code traceability analysis tool, GNAT Pro’s Traceability Analysis Package comprises an Ada language feature analysis, including test cases and GNAT Pro switch recommendations, that can help developers demonstrate compliance of safety-critical software with the DO-178B avionics standard. It enables the use of the GNAT Pro compiler to meet Table A7 objective 7, in accordance with the guidelines described in the Certification Authority Software Team’s Position Paper CAST-12.
Depending on the application’s criticality level, DO-178B demands varying depths of analysis for showing coverage of the requirements by the software. In general it is sufficient to demonstrate coverage based on the source code. However, at the highest level (DO-178B, Level A), if the compiler generates object code not directly traceable to source code, then the developer needs to perform additional verification on the object code to establish the correctness of such generated code. The traceability analysis material establishes traceability between source code and object code and provides additional verification for untraceable code, as described in section 18.104.22.168.b of the DO-178B standard.
The GNAT Pro Traceability Analysis Package permits the use of a rich safety-oriented coding standard. It includes the following items, which AdaCore prepares based on the customer's coding standard:
- Consistency analysis of the coding standard
- Recommendations for those compilation switches and language restrictions offering the best tradeoff between performance of generated code and ease of showing traceability between source and object code
- A test suite representative of the subset of the Ada language allowed by the customer’s coding standard
- The analysis, for each test, of the traceability of the generated object code
- Additional verification to establish the correctness of generated code that is not directly traceable to source code.