1. Modern Processor Architectures Make WCET Analysis for HUME Challenging Christian Ferdinand AbsInt Angewandte Informatik GmbH

2. The Timing Problem P r o b a b i l i t y Execution Time Best Case Execution Time Exact Worst Case Execution Time

3. End-to-end Measurements P r o b a b i l i t y Execution Time Best Case Execution Time Exact Worst Case Execution Time Measured Worst-case Unsafe: Execution Time Measurement

4. Hybrid Approachs P r o b a b i l i t y Execution Time Best Case Execution Time Exact Worst Case Execution Time Combination of Local Measurements

5. Static Timing Analysis (Abstract Interpretation) P r o b a b i l i t y Execution Time Best Case Execution Time Exact Worst Case Execution Time SafeWorst Case Execution Time Estimate

6. EmBounded Low-Level Timing Analysis for Renesas M32C85  High-level source code: Hume … … is translated to HAM code (Hume Abstract Machine)  HAM code is translated to C  Each HAM instruction becomes a snippet of C code  C code is translated to M32C binary code  Each HAM instruction then becomes a snippet of M32C code  Use AbsInt’s aiT to analyze the M32C code corresponding to the HAM instructions

7. aiT vs. Measurement  Good precision in general  Note for MatchRule: Measurement error up to 3 cycles  See IFL06 paper Armelle Bonenfant et al., Worst-Case Execution Times for a Purely Functional Language

8. aiT WCET Analyzer Structure Interprocedural PAG-generated analyzers based on AI

9. Contexts with Loops INTERPROC: VIVU INTERPROC_L: 3

10. e300  e300 / PPC603e  +- 450 MHz  Double precision FPU  Caches (LRU) + store buffer  Superscalar pipeline with out- of-order execution  Branch prediction (static)  Available in various processors, e.g. Freescale MPC82xx

11. Recursive C-Program Example

12. Conclusion  On M32-class processors  Current WCET analysis for Hume works well  On e300-class processors  Current WCET analysis for Hume will largely overestimate