Deriving annotations for tight calculation of execution time

Abstract

A number of methods have been presented to calculate the worst case execution time (WCET) of real-time programs. However, to properly handle semantic dependencies, which in most cases is needed to reduce overestimation, all these methods require extra semantic information to be given by the programmer (manual annotations for paths, loops and recursion depth). To manually derive these annotations is often difficult and the process is error-prone. In this paper we present a new method to automatically derive safe and tight annotations for paths and loops. We illustrate our method by giving some examples and by presenting a prototype tool, implementing the method for a subset of C.