Refinement of Parallel Algorithms down to LLVM applied to practically efficient parallel sorting

Abstract

We present a stepwise refinement approach to develop verified parallel algorithms, down to efficient LLVM code. The resulting algorithms' performance is competitive with their counterparts implemented in C/C++. Our approach is backwards compatible with the Isabelle Refinement Framework, such that existing sequential formalizations can easily be adapted or re-used. As case study, we verify a parallel quicksort algorithm that is competitive to unverified state-of-the-art algorithms.