Section: Overall Objectives

Introduction

Keywords:

Compilation, code analysis, code optimization, memory optimization, combinatorial optimization, algorithmics, polyhedral optimization, hardware accelerators, high-level synthesis, high-performance computing.

The objective of Compsys is to adapt and to extend code optimization techniques primarily designed in compilers/parallelizers for high performance computing to the special case of embedded computing systems. In particular, Compsys works on back-end optimizations for specialized processors and on high-level program transformations for the synthesis of hardware accelerators. The main characteristic of Compsys is its focus on combinatorial problems (graph algorithms, linear programming, polyhedra) coming from code optimizations (register allocation, cache and memory optimizations, scheduling, optimizations for power, automatic generation of software/hardware interfaces, etc.) and the validation of techniques developed in compilation tools.

Compsys started as an Inria project in 2004, after 2 years of maturation. This first period of Compsys, Compsys I, was positively evaluated in Spring 2007 after its first 4 years period (2004-2007). It was again evaluated by AERES in 2009, as part of the general evaluation of Lip, and got the best possible mark, A+. The second period (2007-2012), Compsys II, was evaluated again by Inria in Spring 2012, positively. The move in 2013 of Fabrice Rastello to Grenoble, whose goal is to expand the activities of Compsys in the context of Giant, a R&D technology center with several industrial and academic actors, has not been validated by all concerned institutions (yet). As a consequence, Compsys II has not been formally prolonged yet into Compsys III. This is why the new research directions of Compsys III, presented in the 2012 evaluation report – mainly a shift towards dynamic compilation and the compilation of streaming programming, with an even stronger focus on polyhedral optimizations – are not described in this 2012 annual report. They should appear in the 2013 report.

Section  2.2 defines the general context of the team's activities. Section  2.3 presents the research objectives and main achievements in Compsys I, i.e., until 2007, and how its research directions were modified for Compsys II. Section  2.4 briefly presents the main achievements of Compsys II, referring to the annual reports from 2008 to 2011 for details. Finally, Section  2.5 highlights the main novelties of the past year, i.e., 2012.