The instruction-set extension problem: a survey

The extension of a given instruction-set with specialized instructions has become a common tech-nique used to speed up the execution of applications. By identifying computationally intensive portions of an application to be partitioned in segments of code to execute in software and seg-ments of code to execute in hardware, the execution of an application can be considerably speeded up. Each segment of code implemented in hardware can then be seen as a specialized application-specific instruction extending a given instruction-set. Although a number of approaches exists in literature proposing different methodologies to customize an instruction-set, the description of the problem consists only of sporadic comparisons limited to isolated problems. This survey presents a unique detailed description of the problem and provides an exhaustive overview of the research in the past years in instruction-set extension. This paper presents a thorough analysis of the issues involved during the customization of an instruction-set by means of a set of special-ized application-specific instructions. The investigation of the problem covers both instruction generation and instruction selection and different kinds of customizations are analyzed in a great detail