Compiler transformations for high-performance computing
ACM Computing Surveys (CSUR)
Advanced compiler design and implementation
Advanced compiler design and implementation
Control Flow Driven Splitting of Loop Nests at the Source Code Level
DATE '03 Proceedings of the conference on Design, Automation and Test in Europe - Volume 1
Improving WCET by applying a WC code-positioning optimization
ACM Transactions on Architecture and Code Optimization (TACO)
MiBench: A free, commercially representative embedded benchmark suite
WWC '01 Proceedings of the Workload Characterization, 2001. WWC-4. 2001 IEEE International Workshop
Loop Nest Splitting for WCET-Optimization and Predictability Improvement
ESTMED '06 Proceedings of the 2006 IEEE/ACM/IFIP Workshop on Embedded Systems for Real Time Multimedia
Design of a WCET-Aware C Compiler
ESTMED '06 Proceedings of the 2006 IEEE/ACM/IFIP Workshop on Embedded Systems for Real Time Multimedia
WCET-driven, code-size critical procedure cloning
SCOPES '08 Proceedings of the 11th international workshop on Software & compilers for embedded systems
A compiler framework for the reduction of worst-case execution times
Real-Time Systems
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For the worst-case execution time (WCET) analysis, especially loops are an inherent source of unpredictability and loss of precision. This is caused by the difficulty to obtain safe and tight information on the number of iterations executed by a loop in the worst case. In particular, data-dependent loops whose iteration counts depend on function parameters are extremely difficult to analyze precisely. Procedure cloning helps by making such data-dependent loops explicit within the source code, thus making them accessible for high-precision WCET analyses. This paper presents the effect of procedure cloning applied at the source-code level on worst-case execution time. Theoptimization generates specialized versions of functionsbeing called with constant values as arguments. In standardliterature, it is used to enable further optimizations like constant propagation within functions and to reduce calling overhead. We show that procedure cloning for WCET minimization leads to significant improvements. Reductions of the WCET from 12% up to 95% were measured for real-life benchmarks. These results demonstrate that procedure cloning improves analyzability and predictability of real-time applications dramatically. In contrast, average-case performance as the criterion procedure cloning was developed for is reduced by only 3% at most. Our results also show that these WCET reductions only implied small overhead during WCET analysis.