Static Worst-Case Execution Time (WCET) analysis is a technique to derive upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A key component for static derivation of precise WCET estimates is upper bounds on the number of times different loops can be iterated.
As the manual annotation of all loops with such bounds is difficult and time consuming, the WCET analyzer aiT originally developed by Saarland University and AbsInt GmbH uses static analysis to determine the needed bounds as far as possible. In this talk I describe a novel data-flow based analysis for aiT to calculate the needed loop bounds on the C code level.