2989	 Empirical Evaluation of Some Features of Instruction Set Processor Architectures	 This paper presents methods for empirical evaluation of features of Instruction Set Processors ISPs . ISP features are evaluated in terms of the time used or saved by having or not having the feature. The methods are based on analysis of traces of program executions. The concept of a register life is in troduced and used to answer questions like How many registers are used simultaneously How many would be sufficient all of the time Most of the time What would the overhead be if the number of registers were reduced What are registers used for during their lives The paper also discusses the problem of detecting desirable but non-existing instructions. Other problems are briefly discussed. Experimental results are presented obtained by analyzing programs running on the DEC system ISP. computer architecture program behavior instruction sets op code utilization register structures register utilization simultaneous register lives instruction tracing execution time
