Prefabrication and postfabrication architecture exploration for partially reconfigurable VLIW processors

Abstract

Modern application-specific instruction-set processors (ASIPs) face the daunting task of delivering high performance for a wide range of applications. For enhancing the performance, architectural features, for example, pipelining, VLIW, are often employed in ASIPs, leading to high design complexity. Integrated ASIP design environments, like template-based approaches and language-driven approaches, provide an answer to this growing design complexity. At the same time, increasing hardware design costs have motivated the processor designers to introduce high flexibility in the processor. Flexibility, in its most effective form, can be introduced to the ASIP by coupling a reconfigurable unit to the base processor. Because of its obvious benefits, several reconfigurable ASIPs (rASIPs) have been designed for years. This design paradigm gained momentum with the advent of coarse-grained FPGAs, where the lack of domain-specific performance common in general-purpose FPGAs are largely overcome by choosing application-dependent basic functional units. These rASIP designs lack a generic flow from high-level specification, resulting in intuitive design decisions and hard-to-retarget processor design tools. Although partial, template-based approaches for rASIP design is existent, a clear design methodology especially for the prefabrication architecture exploration is not present. In order to address this issue, a high-level specification and design methodology for partially reconfigurable VLIW processors is proposed in this article. To show the benefit of this approach, a commercial VLIW processor is used as the base architecture and two domains of applications are studied for potential performance gain.