Replacing conjectures by positive knowledge: Inferring proven precise worst-case execution time bounds using symbolic execution

Symbolic Worst Case Execution Times

In immediate or hard real-time systems the correctness of an operation depends not only upon its logical correctness, but also on the time in which it is is computed. In such systems, it is imperative that operations are performed within a given deadline because missing this deadline constitutes the failure of the complete system. Such systems include medical systems, flight control systems and...

Refinement of worst-case execution time bounds by graph pruning

Inferring Invariants by Symbolic Execution

In this paper we propose a method for inferring invariants for loops in Java programs. An example of a simple while loop is used throughout the paper to explain our approach. The method is based on a combination of symbolic execution and computing fixed points via predicate abstraction. It reuses the axiomatisation of the Java semantics of the KeY system. The method has been implemented within ...

An Approach to Symbolic Worst-case Execution Time Analysis

Using the constant value for the worst case execution time for all calls to a subprogram is safe but pessimistic. We address the problem of tailoring the WCET of each call to a subprogram by building the WCET as an algebraic expression parameterised with some of the subprogram parameters. The WCET of each call may then be constrained to particular ranges of values that lead to tighter WCET. The...

Combining Symbolic Execution and Path Enumeration in Worst-Case Execution Time Analysis

This paper examines the problem of determining bounds on execution time of real-time programs. Execution time estimation is generally useful in real-time software verification phase, but may be used in other phases of the design and execution of real-time programs (scheduling, automatic parallelizing, etc.). This paper is devoted to the worst-case execution time (WCET) analysis. We present a st...