Timing analysis of superscalar processor programs using ACSR

This paper illustrates a formal technique for describing the timing properties and resource constraints of pipelined superscalar processor instructions at high level. Superscalar processors can issue and execute multiple instructions simultaneously. The degree of parallelism depends on the multiplicity of hardware functional units as well as data dependencies among instructions. Thus, the timing properties of a superscalar program is difficult to analyze and predict. We describe how to model the instruction-level architecture of a superscalar processor using ACSR and how to derive the temporal behavior of an assembly program using the ACSR laws. The salient aspect of ACSR is that the notions of time, resources and priorities are supported directly in the algebra. Our approach is to model superscalar processor registers as ACSR resources, instructions as ACSR processes, and use ACSR priorities to achieve maximum possible instruction-level parallelism.