Section: Overall Objectives

Highlights

The year 2011 was marked by strong financial difficulties due to the unilateral decision of the government to stop all Nano2012 fundings. For Compsys, involved in the Mediacom and S2S4HLS projects, this has led to a non-anticipated budget cut of about 60% (excluding salaries). The help of Inria to support the salary of Florian Brandner (post-doc/engineer) and pay some registration fees (in particular CGO'11) was crucial. The research activities in Mediacom still continue, but in a restricted form, until the end of Quentin Colombet's PhD. However, Compsys had to stop its participation to S2S4HLS.

Compsys continued its activities on static single assignment (SSA) and register allocation, as well as on high-level synthesis (HLS) for FPGA. The main achievements in 2011 are:

• The design of a tree-scan allocator was continued and two related contributions were published at SCOPES'11 and CASES'11.

• Our new algorithm for liveness analysis under SSA and a comparison with existing methods were finalized and published at APLAS'11.

• An analysis, based on an integer linear programming formulation, of “optimal spilling” was made with full experiments and published at CASES'11.

• The automatic generation of double-buffered pipelined versions of computation kernels for FPGA was improved and will be presented at PPoPP'12. A simplifier for Boolean affine formulas was designed that should improve the code generation part.

• Alexandru Plesco, following his PhD, initiated a project of start-up, Zettice, supported by Inria and ens -l yon, combining the experience of Compsys on compilation and HLS, and the expertise of Arénaire on floating-point pipelined operators for FPGA. A publication at ARC'11 illustrates this effort.

Also, in 2011, Compsys was very active in the organization of important events for our scientific community:

• Fabrice Rastello, after re-activating the french community in compilation, was very involved in the organization of the main international conference in code generation (CGO'11), in Chamonix, and the organization and advertising of its workshops.

• Christophe Alias was the main organizer of IMPACT'11 (international workshop on polyhedral compilation techniques), held in conjunction with CGO'11. This workshop is the very first international event on this topic. Laure Gonnord was co-organizer of the workshop ACCA'11 (analyze to compile, compile to analyze), also part of CGO'11.

Best Paper Award :

[14] An FPGA Architecture for Solving the Table Maker's Dilemma in 22nd IEEE International Conference on Application-specific Systems, Architectures and Processors (ASAP'11).

F. de Dinechin, J.-M. Muller, B. Pasca, A. Plesco.