Section: Software

Introduction

This section lists and briefly describes the software developments conducted within Compsys. Most are tools that we extend and maintain over the years. They now concern two activities only: a) the development of tools linked to polyhedra and loop/array transformations, b) the development of algorithms within the back-end compiler of STMicroelectronics.

Many tools based on the polyhedral representation of codes with nested loops are now available. They have been developed and maintained over the years by different teams, after the introduction of Paul Feautrier's Pip, a tool for parametric integer linear programming. This “polytope model” view of codes is now widely accepted: it used by Inria projects-teams Cairn and Alchemy/Parkas, PIPS at École des Mines de Paris, Suif from Stanford University, Compaan at Berkeley and Leiden, PiCo from the HP-Labs (continued as PicoExpress by Synfora and now Synopsis), the DTSE methodology at Imec, Sadayappan's group at Ohio State University, Rajopadhye's group at Colorado State's University, etc. More recently, several compiler groups have shown their interest in polyhedral methods, e.g., the Gcc group, IBM, and Reservoir Labs, a company that develops a compiler fully based on the polytope model and on the techniques that we (the french community) introduced for loop and array transformations. Polyhedra are also used in test and certification projects (Verimag, Lande, Vertecs). Now that these techniques are well-established and disseminated in and by other groups, we prefer to focus on the development of new techniques and tools, which are described here.

The other activity concerns the developments within the compiler of STMicroelectronics. These are not stand-alone tools, which could be used externally, but algorithms and data structures implemented inside the LAO back-end compiler, year after year, with the help of STMicroelectronics colleagues. As these are also important developments, it is worth mentioning them in this section. They are also completed by important efforts for integration and evaluation within the complete STMicroelectronics toolchain. They concern exact (ILP-based) methods, algorithms for aggressive optimizations, techniques for just-in-time compilation, and for improving the design of the compiler.