Loop Nest Splitting for WCET-Optimization and Predictability Improvement

This paper presents the influence of the loop nest splitting source code optimization on the worst-case execution time (WCET). Loop nest splitting minimizes the number of executed if-statements in loop nests of embedded multimedia applications. It identifies iterations of a loop nest where all if-statements are satisfied and splits the loop nest such that if-statements are not executed at all for large parts of the loop nest's iteration space. Especially loops and if-statements of high-level languages are an inherent source of unpredictability and loss of precision for WCET analysis. This is caused by the fact that it is difficult to obtain safe and tight worst-case estimates of an application's flow of control through these high-level constructs. In addition, the corresponding control flow redirections expressed at the assembly level reduce predictability even more due to the complex pipeline and branch prediction behavior of modern embedded processors. The analysis techniq...

• Type: Conference
• Year: 2006
• Where: ESTIMEDIA
• Authors: Heiko Falk, Martin Schwarzer
• Keywords: ESTIMEDIA 2006, Loop Nest, Loop Nest Iteration, Loop Nest Splitting, Multimedia