Timing analysis is a crucial test for dependable hard real-time systems (DHRTS). The calculation of the worst-case execution time (WCET) is mandatory. As modern compilers are capable to produce small and efficient code, software development for DHRTS today is mostly done in high-level languages instead of assembly code. Execution path information available at source code (flow facts) therefore have to be trans- formed correctly in accordance with code optimisations by the compiler to allow safe and precise WCET analysis. In this paper we present a framework based on abstract interpretation to perform this mandatory transformation of flow facts. Conventional WCET analysis approaches use this information to analyse the object code.