Resource conflict detection in simulation of function unit pipelines

Processor simulators are important parts of processor design toolsets in which they are used to verify and evaluate the properties of the designed processors. While simulating architectures with independent function unit pipelines using simulation techniques that avoid the overhead of instruction bit-string interpretation, such as compiled simulation, the simulation of function unit pipelines can become one of the new bottlenecks for simulation speed. This paper evaluates several resource conflict detection models, commonly used in compiler instruction scheduling, in the context of function unit pipeline simulation. The evaluated models include the conventional reservation table based-model, the dynamic collision matrix model, and an finite state automata (FSA) based model. In addition, an improvement to the simulation initialization time by means of lazy initialization of states in the FSA-based approach is proposed. The resulting model is faster to initialize and provides comparable simulation speed to the actively initialized FSA.