Automated Worst-Case Execution Time Analysis Based on Program Modes

A program mode is a regular trajectory of the execution of a program that is determined by the values of its input variables. By exploiting program modes, we may make worst-case execution time (WCET) analysis more precise. This paper presents a novel method to automatically find program modes and calculate the WCET estimates of programs. First, the modes of a program will be identified automatically by mode-relevant program slicing, and the precondition will be calculated for each mode using a path-wise test data generation method. Then, for each feasible mode, we show how to calculate its WCET estimate for modern reduced instruction set computer (RISC) processors with caches and pipelines and for traditional complex instruction set computer (CISC) processors. We also present a method to obtain the symbolic expression for each mode for CISC processors. The experimental results show the effectiveness of the method.