source: anr-2010/section-3.2.tex

% les objectifs scientifiques/techniques du projet.
The design steps are presented figure~\ref{coach-flow}.
\begin{figure}[hbtp]\leavevmode\center
  \includegraphics[width=.8\linewidth]{flow}
  \caption{\label{coach-flow} COACH design flow}
\end{figure}
\begin{description}
\item[HPC setup:] During this step, the user splits the application into 2 parts: the host application
which remains on the PC and the SoC application which is mapped on the FPGA. 
COACH will provide a complete simulation model of the whole system (PC+communication+FPGA-SoC) 
which will allow performance evaluation.
\item[SoC design:] In this phase, 
COACH will allow the user to obtain virtual prototypes for the SoC at different abstraction levels.
The user input will consist of a process network describing the coarse grain parallelism
of the application, an instance of a generic hardware platform
and a mapping of processes on the platform components. 
COACH will offer different targets to map the processes:  
software (the process runs as a software task on a SoC processor),
ASIP (the process runs as a software task on a SoC processor enhanced with dedicated instructions),
and hardware (the process is implemented as a synthesized hardware coprocessor).
\item[Application compilation:] Once the SoC architecture is validated through performances 
analysis, COACH will generate automatically an executable containing the host application and
the FPGA bitstream. This bitstream contains 
both the hardware architecture and the SoC application software.
The user will be able to launch the application by
loading the bitstream on an FPGA and running the executable on PC.
\end{description}
 
% l'avancee scientifique attendue. Preciser l'originalite et le caractere 
% ambitieux du projet. 
%FIXME == {NON ceci n'est pas une contribution scientifique. A re-ecrire}

%The main scientific contribution of the project is to unify various synthesis techniques
%(same input and output formats) allowing the user to swap without engineering effort
%from one to another and even to chain them. For instance, it will be possible to run loop transformations before synthesis.
%Another advantage of this framework is to provide different abstraction levels from
%a single description.
%Finally, this description is device family independent and its hardware implementation
%is automatically generated.

% Detailler les verrous scientifiques et techniques a lever par la realisation du projet.
Hardware/Software co-design is a very complex task. To simplify it, COACH will address the
following scientific and technological barriers:
\begin{description}
\item[\textit{Design Space Exploration by Virtual Prototyping}]:
        The COACH environment will allow to easily map a parallel application (formally described as
        an abstract network of process and communication channels)  
        COACH will permit the system designer to explore the design space, and to define the best 
        hardware/software partitioning of the application.
\item[\textit{Integration of system level modeling and HLS tools}]:
        COACH will support the automated generation of hardware accelerators when required
        by using High-Level Synthesis (HLS) tools. These HLS tools will be
        fully integrated into a complete system-level design environment.
        Moreover, COACH will support both data and control dominated applications,
        and the HLS tools of COACH will support a common language and coding style 
        to avoid re-engineering by the designer.
        COACH will provide a tool which will automatically explore the micro-architectural 
        design space of coprocessor.
\item[\textit{High-level code transformation}]:
        COACH will allow to optimize the memory usage, to enhance the parallelism through 
        loop transformations and parallelization. The challenge is to identify the coarse 
        grained parallelism and to generate,
        from a sequential algorithm, application containing multiple communicating
        tasks. COACH will adapt techniques which were developed in the 1990 for 
        the construction of distributed programs. However, in the context of HLS, there are 
        several original problems to be solved, related to the  FIFO communication channels and with 
        memory optimization. 
        COACH will support code transformation by providing a source to source C2C tool.
\item[\textit{Unified Hardware/Software communication middleware}]:
        COACH will rely on he SoCLib experience to implement an unified hardware/software communication 
        infrastructure and communication APIs (Application Programming Interface), to support  
        communications between software tasks running on embedded processors and dedicated 
        hardware coprocessors. The main issue here is to support easy migration 
        from a software implementation to an hardware implementation.
\item[\textit{Processor customization}]:
        ASIP (Application Specific Instruction Processor) design will be addressed by the COACH project. 
        COACH will allow system designers to explore the various level of interactions between 
        the original CPU micro-architecture and its extension. It will also allow to retarget 
        the compiler instruction-selection pass. Finally, COACH will integrate ASIP synthesis
        in a complete System-level design framework.
\end{description}

%Presenter les resultats escomptes en proposant si possible des criteres de reussite 
%et d'evaluation adaptes au type de projet, permettant d'evaluer les resultats en 
%fin de projet.
The main result is the framework. It is composed concretely of: 
a communication middleware for HPC, 
5 HAS tools (control dominated HLS, data dominated HLS, Coarse grained HLS, 
Memory optimisation HLS and ASIP),
3 architectural templates that are synthesizable and that can be prototyped,
one design space exploration tool,
2 operating systems (DNA/OS and MUTEKH).
\\
The framework fonctionality will be demonstrated with the demonstrators
(see task-7 page~\pageref{task-7}) and the tutorial example (see task-8
page~\ref{subtask-tutorial}).