A hierarchical mathematical model for automatic pipelining and allocation using elastic systems

The advent of FPGA-based accelerators has encouraged the use of high-level synthesis (HLS) for rapid prototyping and design space exploration. In this context, design optimization at behavioral level becomes a critical task for the delivery of high-quality solutions. Time elasticity opens a new avenue of optimizations that can be applied after HLS and before logic synthesis, proposing new sequential transformations that expand beyond classical retiming and enlarge the register-transfer level (RTL) exploration space. This paper proposes a mathematical model for RTL transformations that exploit elasticity to select the best implementation for each functional unit and add pipeline registers to increase performance. Two simple examples are used to validate the effectiveness and potential benefits of the model.Peer ReviewedPostprint (author's final draft

A Survey and Evaluation of FPGA High-Level Synthesis Tools

High-level synthesis (HLS) is increasingly popular for the design of high-performance and energy-efficient heterogeneous systems, shortening time-to-market and addressing today's system complexity. HLS allows designers to work at a higher-level of abstraction by using a software program to specify the hardware functionality. Additionally, HLS is particularly interesting for designing field-programmable gate array circuits, where hardware implementations can be easily refined and replaced in the target device. Recent years have seen much activity in the HLS research community, with a plethora of HLS tool offerings, from both industry and academia. All these tools may have different input languages, perform different internal optimizations, and produce results of different quality, even for the very same input description. Hence, it is challenging to compare their performance and understand which is the best for the hardware to be implemented. We present a comprehensive analysis of recent HLS tools, as well as overview the areas of active interest in the HLS research community. We also present a first-published methodology to evaluate different HLS tools. We use our methodology to compare one commercial and three academic tools on a common set of C benchmarks, aiming at performing an in-depth evaluation in terms of performance and the use of resources