MediaBench: a tool for evaluating and synthesizing multimedia and communicatons systems
MICRO 30 Proceedings of the 30th annual ACM/IEEE international symposium on Microarchitecture
Advanced compiler design and implementation
Advanced compiler design and implementation
Code selection for media processors with SIMD instructions
DATE '00 Proceedings of the conference on Design, automation and test in Europe
Data cache locking for higher program predictability
SIGMETRICS '03 Proceedings of the 2003 ACM SIGMETRICS international conference on Measurement and modeling of computer systems
RTSS '04 Proceedings of the 25th IEEE International Real-Time Systems Symposium
Improving WCET by Optimizing Worst-Case Paths
RTAS '05 Proceedings of the 11th IEEE Real Time on Embedded Technology and Applications Symposium
Cache Contents Selection for Statically-Locked Instruction Caches: An Algorithm Comparison
ECRTS '05 Proceedings of the 17th Euromicro Conference on Real-Time Systems
Scratchpad memories vs locked caches in hard real-time systems: a quantitative comparison
Proceedings of the conference on Design, automation and test in Europe
WCET-Directed Dynamic Scratchpad Memory Allocation of Data
ECRTS '07 Proceedings of the 19th Euromicro Conference on Real-Time Systems
Compile-time decided instruction cache locking using worst-case execution paths
CODES+ISSS '07 Proceedings of the 5th IEEE/ACM international conference on Hardware/software codesign and system synthesis
Design of a WCET-Aware C Compiler
ESTMED '06 Proceedings of the 2006 IEEE/ACM/IFIP Workshop on Embedded Systems for Real Time Multimedia
Predictable Code and Data Paging for Real Time Systems
ECRTS '08 Proceedings of the 2008 Euromicro Conference on Real-Time Systems
WCET-driven Cache-based Procedure Positioning Optimizations
ECRTS '08 Proceedings of the 2008 Euromicro Conference on Real-Time Systems
Static profiling of the worst-case in real-time programs
Proceedings of the 20th International Conference on Real-Time and Network Systems
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The worst-case execution time (WCET) being the upper bound of the maximum execution time corresponds to the longest path through the program's control flow graph. Its reduction is the objective of a WCET optimization. Unlike average-case execution time compiler optimizations which consider a static (most frequently executed) path, the longest path is variable since its optimization might result in another path becoming the effective longest path. To keep path information valid, WCET optimizations typically perform a time-consuming static WCET analysis after each code modification to ensure that subsequent optimization steps operate on the critical path. However, a code modification does not always lead to a path switch, making many WCET analyses superfluous. To cope with this problem, we propose a new paradigm called Invariant Path which eliminates the pessimism by indicating whether a path update is mandatory. To demonstrate the paradigm's practical use, we developed a novel optimization called WCET-driven Loop Unswitching which exploits the Invariant Path information. In a case study, our optimization reduced the WCET of real-world benchmarks by up to 17.4%, while exploiting the Invariant Path paradigm led to a reduction of the optimization time by 57.5% on average.