Transformation of Path Information for WCET Analysis during Compilation

Performing worst case execution time WCET analysis on machine code with program path annota tion provided at high level source code level requires the transformation of path annotations from the source code level to assembly object code level This path information transformation can be done outside or in tegrated into the compiler during code compilation The rst approach is easier to implement but lacks for the support of strong code optimizations performed by the compiler because the external tool would have to make guesses about optimizations In this paper we present an approach for the program code compilation that inte grates the transformation of program path information into the compiler Path information is transformed through all compiler stages to the adequate path infor mation for the corresponding assembly code level The WCET analysis tool processes the program at assembly code level with the correctly transformed program path information to obtain accurate runtime bounds Sev eral experiments were performed to demonstrate the importance of supporting the transformation of path information in aggressively optimizing compilers