Abstract

This paper describes how program-checking can be used to significantly reduce the amount of verification work to establish the implementation correctness of software systems which may be partly generated by unverified construction tools. We show the practicability of our approach with an application to the construction of verified compiler back-ends. The basic idea of program-checking is to use an unverified algorithm whose results are checked by a verified component at run time. Run-Time Result Verification in our approach assures formal correctness of the software system and its implementation if partial correctness of the application is sufficient. In our example the approach does not only simplify the construction of verified compilers because checking the result of the transformations is much simpler to verify than the verification of an optimizing code selection. Furthermore, we are still able to use existing compiler generator tools without modifications. Compiler verification plays two roles in this paper: First it closes the gap between verification on high-level programming language and the implementation on machine level using a verified compiler to translate the verified program to machine code. Second it serves as a large-scale case study for software verification. This work points out the tasks which still have to be verified and it discusses the flexibility of the approach.

Citations