Scenario-Aware Program Specialization for Timing Predictability

The successful application of static program analysis strongly depends on flow facts of a program such as loop bounds, control-flow constraints, and operating modes. This problem heavily affects the design of real-time systems, since static program analyses are a prerequisite to determine the timing behavior of a program. For example, this becomes obvious in worst-case execution time (WCET) analysis, which is often infeasible without user-annotated flow facts. Moreover, many timing simulation approaches use statically derived timings of partial program paths to reduce simulation overhead. Annotating flow facts on binary or source level is either error-prone and tedious, or requires specialized compilers that can transform source-level annotations along with the program during optimization. To overcome these obstacles, so-called scenarios can be used. Scenarios are a design-time methodology that describe a set of possible system parameters, such as image resolutions, operating modes, or application-dependent flow facts. The information described by a scenario is unknown in general but known and constant for a specific system. In this article, 1 we present a methodology for scenario-aware program specialization to improve timing predictability. Moreover, we provide an implementation of this methodology for embedded software written in C/C++. We show the effectiveness of our approach by evaluating its impact on WCET analysis using almost all of TACLeBench–achieving an average reduction of WCET of 31%. In addition, we provide a thorough qualitative and evaluation-based comparison to closely related work, as well as two case studies.

ABench2020: A WCET Benchmark Suite in Ada Programming Language

Validation is an important part of the development process of real-time systems. During validation, it should be proved that, the system meets its timing constraints. Therefore, worst-case execution time (WCET) analysis is performed. Currently, several WCET analysis tools are being developed. Researchers who develop new WCET analysis tools, need benchmarks to evaluate and compare their tools with alternatives. These benchmarks are called WCET benchmarks. In this paper a new WCET benchmark suite named ABench2020 is introduced. Its main focus is to provide benchmark programs in Ada programming language for WCET research. Therefore, ABench2020 includes several benchmark programs which were written in Ada programming language. The benchmark programs implement different program structures and properties to help researchers test their systems from different aspects. ABench2020 was published as open source. It is freely available over the Internet.