A system-level framework for evaluating area/performance/power trade-offs of VLIW-based embedded systems

Architectures based on Very Long Instruction Word (VLIW) have found fertile ground in multimedia electronic appliances thanks to their ability, to exploit high degrees of Instruction Level Parallelism (ILP) with a reasonable trade-off in complexity and silicon costs. In this case Application Specific Instruction-set Processor (ASIP) specialization may require not only manipulation of the instruction-set but also tuning of the architectural parameters of the processor (e.g. the number and type of functional units, register files, etc.) and the memory subsystem (cache size, associativity, etc.). Setting the parameters so as to optimize certain metnics requires the use of efficient Design Space Exploration (DSE) strategies and also simulation tools (retargetable compilers and simulators) and accurate estimation models operating at a high level of abstraction. In this paper we present a framework for evaluation, in terms of performance, cost and power consumption, of a system based on a parameterized VLIW microprocessor together with the memory hierarchy subsystem following execution of a specific application. The framework, which can be freely downloaded from the Internet, implements a number of multi-objective DSE strategies to obtain Pareto-optimal configurations for the system.