Two Approaches of Showing Program Equivalence CSC 2108 Automated Verification

We describe two approaches to showing program equivalence. Program equivalence is useful for showing that a program created by an optimizing compiler is correct. The optimized version of the program can be compared to a program that is created from the same source code by a verified compiler that performs no optimizations. Our first approach consists of using a theorem prover, ACL2, to prove that two programs are equivalent. For this approach to work we must transform the instructions of the programs into a representation that ACL2 can work with. Our second approach consists of calculating the weakest pre-condition needed for two programs to be correct, and then using ACL2 to prove that the pre-condition is met. We use both approaches to show the equivalence of several programs.