Automatic generation of application specific processors

Abstract

An application-specific instruction-set processor (ASIP) is ideally suited for embedded applications that have demanding performance, size, and power requirements that cannot be satisfied by a general purpose processor. ASIPs also have time-to-market and programmability advantages when compared to custom ASICs. The AutoTIE system simplifies the creation of ASIPs by automatically enhancing a base processor with application specific instruction set architecture (ISA) extensions, including instructions, operations, and register files. The new instructions, operations, and register files are automatically recognized and exploited by the entire software tool chain, including the C/C++ compiler. Thus, taking advantage of the generated ASIP does not require any changes to the application or any assembly language coding. AutoTIE uses the C/C++ compiler to analyze an application, and based on the analysis generates thousands, or even millions, of possible ISA extensions for the application. AutoTIE then uses performance and hardware estimation techniques to combine the ISA extensions into a large number of potential ASIPs, and for a range of hardware costs, chooses the ASIP that provides the maximum performance improvement. For example, for an application performing a radix-4 FFT, AutoTIE considers over 34,000 potential sets of ISA extensions. For hardware costs ranging from 7800 gates to 128,000 gates, AutoTIE combines these extensions to form 31 ASIPs, which provide performance improvements ranging from a factor of 1.12 to a factor of 11.3 compared to a general-purpose processor.