Towards Designing WCET-Predictable Processors.
Christine Rochange, Pascal Sainrat · 2003
Several methods based on a static analysis of the executable code have been proposed in the past to estimate the worst-case execution time of programs. Their main advantage is to limit measurements to small parts of code (e.g. basic blocks). However these methods have been designed for basic processor architectures and recent work by Engblom has shown that they would not be safe for more advanced designs. Actually, the execution of a basic block could have an impact on the execution of a distant subsequent basic block. Ignoring this impact could result in an under-estimated WCET, which could be dramatic in a hard real-time context. In this paper, we suggest that advanced architectures could include specific hardware that would eliminate all possible long timing effects. We show how this idea could permit to make superscalar pipelines analyzable for the WCET.