Transformation of path information for WCET analysis during compilation

Abstract

Performing worst-case execution time (WCET) analysis on machine code with program path annotation 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 integrated into the compiler during code compilation. The first 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 integrates the transformation of program path information into the compiler. Path information is transformed through all compiler stages to the adequate path information 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. Several experiments were performed to demonstrate the importance of supporting the transformation of path-information in aggressively optimizing compilers.