Design and Implementation of an Escape Analysis in the Context of Safety-Critical Embedded Systems

Abstract

The use of a managed, type-safe language such as Standard ML, Ada Ravenscar, or Java in hard real-time and embedded systems offers productivity, safety, and dependability benefits at a reasonable cost. Static software systems, that is systems in which all relevant resource entities such as threads and their priorities, for instance, and the entire source code are known ahead of time, are particularly interesting for the deployment in safety-critical embedded systems: Code verification is rather maintainable in contrast to dynamic systems. Additionally, static analyses can incorporate information from all software and system layers to assist compilers in emitting code that is well suited to an application on a particular hardware device. It was shown in the past that a program composed in type-safe Java in combination with a static system setup can be as efficient as one that is written in C [30], which is still the most widely used language in the embedded domain. Escape analysis (EA) is one of several static-analysis techniques. It supports, for instance, runtime efficiency by enabling automated stack allocation of objects. In addition, Stilkerich et al. [27, 28] have argued that EA enables further applications in safety-critical embedded systems such as the computation of memory classes stated in the Real-Time Specification for Java (RTSJ) [6]. EA can be applied to any programming language but the quality of its results greatly benefits from the properties of a type-safe language. Notably, embedded multicore devices can positively be affected by the use of EA. Thus, we explore an ahead-of-time (AOT) escape analysis in the context of the KESO JVM featuring a Java AOT compiler targeting (deeply) embedded (hard) real-time systems.