Worst-Case Execution Time analysis at low cost

The computation of Worst-Case Execution Times (WCETs) of tasks involves the description of possible execution paths on source level, the translation of the program and the path information to the machine level, the timing analysis at the machine level, and the documentation of the timing at the source level. These steps of WCET analysis strongly suggest the cooperation between compilers and machine-level WCET tools, and in fact some prototype compilers/WCET analyzers exist. To this date there exists, however, no commercial compiler that supports WCET analysis. This paper describes a light-weight approach to WCET analysis that does not depend on a specific compiler and thus reduces the dependency on compiler builders. The approach uses a tool to read the path information contained in the source code and map this information onto the assembler program. A low-level WCET analysis tool then computes the desired timing information of the annotated assembler program. Experiments with a simple prototype tool demonstrate the feasibility of the approach for simple programs and a moderately optimizing compiler.