Symbolic WCET Analysis of Programs Containing Input-Dependent Branches

Symbolic WCET (worst-case execution time) analysis yields symbolic upper bound expressions for tasks that contain parameters. Quickly evaluated at run-time, such expressions can improve the accuracy of WCET estimate. This paper proposes a symbolic WCET analysis method that is especially for the input-data dependent branches. First, the formulas described by Blieberger is expanded, so that they can express the input-data dependent branches. Simplification of the formulas using control-dependent graph yields conditional symbolic expressions that have different forms corresponding to different input value ranges. Different from the existing methods, the symbolic formulas are directly dependent on input-data, so WCET estimate evaluation at run-time is more simple and straightforward.