Locus: a system and a language for program optimization

We discuss the design and the implementation of Locus, a system and a language to orchestrate the optimization of applications. The increasing complexity of machines and the large space of program variants, produced by the many transformations available, conspire to make compilers deliver unsatisfactory performance. As a result, optimization experts must intervene to manually explore the space of program variants seeking the best version for each target machine. This intervention is unproductive, and maintaining and managing sequences of transformations as new architectures are adopted and new application features are incorporated is challenging.