A Compilation Flow for Parametric Dataflow: Programming Model, Scheduling, and Application to Heterogeneous MPSoC

International audienceEfficient programming of signal processing applications on embedded systems is a complex problem. High level models such as Synchronous dataflow (SDF) have been privileged candidates for dealing with this complexity. These models permit to express inherent application parallelism, as well as analysis for both verification and optimization. Parametric dataflow models aim at providing sufficient dynamicity to model new applications, while at the same time maintaining the high level of analyzability needed for efficient real life implementations. This paper presents a new compilation flow that targets parametric dataflows. Built on the LLVM compiler infrastructure, it offers an actor based C++ programming model to describe parametric graphs, a compilation front-end providing graph analysis features, and a retargetable back-end to map the application on real hardware. This paper gives an overview of this flow, with a specific focus on scheduling. The crucial gap between dataflow models and real hardware on which actor firing is not atomic, as well as the consequences on FIFOs sizing and execution pipelining are taken into account.The experimental results illustrate our compilation flow applied to compilation of 3GPP LTE-Advanced demodulation on a heterogeneous MPSoC with distributed scheduling features. This achieves performances similar to time-consuming hand made optimizations

Enforcing Multifunctionality: A Pressure-Induced Spin-Crossover Photomagnet

Photomagnetic compounds are usually achieved by assembling preorganized individual molecules into rationally designed molecular architectures via the bottom-up approach. Here we show that a magnetic response to light can also be enforced in a nonphotomagnetic compound by applying mechanical stress. The nonphotomagnetic cyano-bridged Fe^II–Nb^IV coordination polymer {[Fe^II(pyrazole)₄]₂[Nb^IV(CN)₈]·4H₂O}_<i>n</i> (<b>FeNb</b>) has been subjected to high-pressure structural, magnetic and photomagnetic studies at low temperature, which revealed a wide spectrum of pressure-related functionalities including the light-induced magnetization. The multifunctionality of <b>FeNb</b> is compared with a simple structural and magnetic pressure response of its analog {[Mn^II(pyrazole)₄]₂[Nb^IV(CN)₈]·4H₂O}_<i>n</i> (<b>MnNb</b>). The <b>FeNb</b> coordination polymer is the first pressure-induced spin-crossover photomagnet

Uniformization of affine dependence programs for parallel embedded system design

This paper is concerned with the uniformization of a system of afine recurrence equations. This transformation is used in the design (or compilation) of highly parallel embedded systems (VLSI systolic arrays, signal processing filters, etc.). In this paper, we present and implement an automatic system to achieve uniformization of systems of afine recurrence equations. We unify the results from many earlier papers, develop some theoretical extensions, and then propose effective uniformization algorithms. Our results can be used in any high level synthesis tool based on polyhedral representation of nested loop computations

Uniformization tool for systolic array designs

The paper is concerned with the uniformization of a system of affine recurrence equations. This transformation is used in the design (or compilation) of highly parallel embedded systems (VLSI systolic arrays, signal processing filters, etc.). We present and implement an automatic system to achieve uniformization of systems of affine recurrence equations. We unify the results from many earlier papers, develop some theoretical extensions, and then propose effective uniformization algorithms. Our results can be used in any high level synthesis tool based on polyhedral representation of nested loop computations