Abstract interpretation (AI) and integer linear programming (ILP) are
two techniques which were used independently from each other for worst
case execution time (WCET) approximation.

With AI one can compute interesting properties of programs.  It can be
implemented efficiently and yields provably correct results.  Previous
work has shown that it is suitable for cache behaviour prediction of
memory references of a program.

By using ILP the structure of a program and the program path can be
described easily and in a very natural way.  A set of constraints
describes the overall structure of the program and solving the
constraints yields very precise results.  However, when modelling
microarchitectural components like caches or pipelines the complexity
of the solving process can increase dramatically.

Our approach uses AI to model the microarchitecture's behaviour and
ILP for finding worst case program paths using the results of the AI.
This combines the advantages of both approaches.