A Conservative Approach to Handle Full Functions in the Polyhedral Model

The Polyhedral Model is one of the most powerful framework for automatic optimization and parallelization of high-level programs. It is based on an algebraic representation of program parts and allows to achieve exact data dependence analysis and to apply complex sequences of optimizations seamlessly. After more than twenty years of research and development, this model is now quite mature and reaches production compilers as GCC 4.4 and its GRAPHITE framework. The main limitation of the Polyhedral Model is known to be its restricted application domain. Traditionally, it is used to manipulate very regular program parts only. The goal of this paper is to show this limitation is mostly artificial. We identify the main problem as the code generation step. We propose an extension to the polyhedral representation and to a code generation algorithm that allows to manipulate full functions in the Polyhedral Model