A heuristic search algorithm based on unified transformation framework

Modern compilers have limited ability to exploit the performance improvement potential of complex transformation compositions. This is due to the ad-hoc nature of different transformations. Various frameworks have been proposed to provide a unified representation of different transformations, among them is Pugh´s unified transformation framework (UTF) (Kelly et al., 1993). It presents a unified and systematic representation of iteration reordering transformations and their arbitrary combination, which results in a large and complex optimization space for a compiler to explore. This paper presents a heuristic search algorithm capable of efficiently locating good program optimizations within such a space. Preliminary experimental results on Java show that it can achieve an average speedup of 1.14 on Linux + Celeron and 1.10 on Windows + PentiumPro, and more than 75% of the maximum performance available can be obtained within 20 evaluations or less.