This paper proposes a retargetable framework for rapid evaluation of processor architecture, which represents abstraction levels of architecture in a hierarchical manner. The basis for such framework is a hierarchical architecture description language, called XR2, which describes architecture at three abstraction levels: instruction set architecture, pipeline architecture and micro-architecture. In addition, a token-level computational model for fast pipeline simulation is proposed, which considers the minimal information required for the given performance measurement of the pipeline. Experimental result shows that token-level simulation is faster than the traditional cycle-accurate one by 50% to 80% in pipeline architecture evaluation.

A packed SIMD type operation or a SIMD operation is n-parallel b/n-bit sub-operations executed by the modified n-bit functional unit. Such a functional unit is called a SIMD functional unit and a processor core which can execute SIMD operations is called a SIMD processor core. SIMD operations can be effectively applied to image processing applications. This paper focuses on hardware/software cosynthesis of SIMD processor cores and particularly proposes a new simulator generator which simulates pipelined instructions for a SIMD processor. Generally, a SIMD functional unit has many options and then we can have so many different SIMD functional unit instances. However, since our hardware/software cosynthesis system synthesizes a special-purpose processor core for an input application program, it uses very limited SIMD functional unit instances. In the proposed approach, we consider a SIMD operation to be a set of SIMD sub-operations. By adding up the appropriate SIMD sub-operations, we construct a single SIMD operation. Then a SIMD functional unit behavior can be characterized by a collection of SIMD operations. This approach has the advantage that: if we have a small number of behavior libraries for SIMD sub-operations, we can instantiate a particular SIMD functional unit behavior. Experimental results demonstrate the effectiveness of the proposed approach.