aiT Worst-Case Execution Time Analyzers

The industry standard for WCET analysis.

aiT WCET Analyzers statically compute tight bounds for the worst-case execution time (WCET) of tasks in real-time systems. They directly analyze binary executables and take the intrinsic cache and pipeline behavior into account.

The challenge

In real-time systems, timely task completion is of the essence. Each real-time task has to be completed within a specified time frame in order to ensure that the system works correctly. In other words, it is essential that the WCET of each task is known.

However, computing the WCET is a challenge:

Testing by repeatedly measuring the execution time of a task is not only tedious, but also typically not safe. It is often impossible to prove that the conditions determining maximum execution time have been taken into account.
Modern processor components such as caches and pipelines complicate the task of determining the WCET considerably, since the execution time of a single instruction may depend on the execution history.
Analysis methods that do not consider cache and pipeline behavior typically overestimate the WCET by several orders of magnitude, thus leading to a substantial waste of hardware resources.

The solution

aiT WCET Analyzers provide the solution to these problems: they statically analyze a task’s intrinsic cache and pipeline behavior based on formal cache and pipeline models. This enables correct and tight upper bounds to be computed for the worst-case execution time.

aiT was designed in the IST project DAEDALUS according to the requirements of Airbus France for validating the timing behavior of critical avionics software, including the flight control software of the A380, the world’s largest passenger aircraft.

The analyzers are based on the technique of abstract interpretation. A graphical user interface supports the visualization of the worst-case program path and the interactive inspection of all pipeline and cache states at arbitrary program points.

Your benefits

Chart showing aiT analysis results vs Volvo’s traditional method vs measured WCET

— Volvo’s traditional method
— aiT analysis results
— measured WCET

aiT-computed bounds are extremely tight and thus reflect the actual performance of your system. Ensuring deadline adherence is not done at the expense of hardware resources.
aiT-computed bounds are valid for all inputs and each execution of a task. Extensive timing testing is a thing of the past.
aiT directly analyzes binary executables. It is widely independent of the compiler and source code language used. This means no modification of your toolchain or the system’s operational behavior and performance is required.

Seamless integration into your toolchain

aiT supports tight integration with many state-of-the-art development tools, including:

SCADE Suite, the market-leading embedded-software development environment from Esterel
ASCET modeling tools from ETAS
SymTA/S scheduling analysis tools from Symtavision
WCC, the first WCET-aware C compiler from TU Dortmund
RT-Druid, the Eclipse-based development environment from Evidence
T1, the runtime measuring software from Gliwa

aiT can also be combined with other analysis tools from AbsInt (e.g. StackAnalyzer for stack usage analysis) in a single intuitive user interface.

Supported targets

aiT is available for a growing number of target processors and compilers.

Compliance with DO-178B level A

aiT itself cannot be qualified for DO-178B by definition, since it is not part of the final system and does not contribute to it in terms of code, but is rather used to analyze already existing code.

Nevertheless, we offer special Qualification Support Kits (QSKs) that simplify the qualification process for DO-178B level A. The QSKs have been successfully used by leading corporations in their DO-178B qualification process, most notably in the avionics industry.

aiT is also an integral part of the SCADE development environment, which is DO-178B qualified up to level A for Military and Aerospace Industries, IEC 61508 certified at SIL 3 by TÜV for Heavy Equipment and Energy, and EN 50128 certified at SIL 4 by TÜV for Rail Transportation.