Automating Proofs of Guaranteed Optimization

Guaranteed optimization is a technique for building compilers that have proven guarantees of what optimizations they perform. Such compilers optimize predictably and thoroughly, finding optimal forms of programs with respect to an approximate program equivalence. Guaranteed optimization is a “design-by-proof” technique: in attempting to verify a compiler has a certain property one uncovers failures in its design, and when the proof finally succeeds the compiler has the desired property. The proof technique is somewhat cumbersome, so maintaining the proof as the compiler evolves can be tedious. We describe a specialized theorem prover for guaranteed optimization that has been successfully used to verify a nontrivial compiler having 8 simultaneous program analyses.