A Machine-Verified Code Generator

We consider the machine-supported verification of a code generator computing machine code from WHILE-programs, i.e. abstract syntax trees which may be obtained by a parser from programs of an imperative programming language. We motivate the representation of states developed for the verification, which is crucial for success, as the interpretation of tree-structured WHILE-programs differs significantly in its operation from the interpretation of the linear machine code. This work has been developed for a course to demonstrate to the students the support gained by computer-aided verification in a central subject of computer science, boiled down to the classroom-level. We report about the insights obtained into the properties of machine code as well as the challenges and efforts encountered when verifying the correctness of the code generator. We also illustrate the performance of the eriFunsystem that was used for this work.