Abstract

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. Document type: Part of book or chapter of book

Abstract

Since its inception, a main objective of the Ada language has been to assist in the development of large and robust applications. In addition to that, the language also provides support for building safety-critical applications, e.g. by facilitating validation and verification of such programs. The latest revision of the language has brought some additional improvements in the safety area, such as the Normalize_Scalars pragma, which ensures an automatic initialization of the nonexplicitly initialized scalars. This paper presents Initialize Scalars, an enrichment of the Normalize_Scalars concept, and an extended mode to verify at run-time the validity of scalars, both designed for easy use in existing large applications. Their implementation in GNAT Pro (the GNU Ada 95 compiler) is discussed. The practical results obtained on a large Air Traffic Flow Management application are presented. Document type: Part of book or chapter of book