1. Data value prediction Bas van der Tol

2. Limits to ILP Instruction Level Parallelism is limited by Control flow Data flow: true dependencies

3. Types of Speculative Execution

4. Sources of predicatable data Data redundancy Error-checking Program constants Virtual function calls Glue code Call-subgraph identities Register spill code

5. Register value locality

6. Value Prediction Unit

7. VPT Hit rate sensitivity to Size

8. Example use of Value Prediction

9. Penalties Misprediction penalty Structural hazards, both on correct and mispredictions Penalties

10. Configurations used for experiments

11. PowerPC 620 Speedup

12. PowerPC 620+ Speedup

13. Infinite Machine Model Speedup

14. Data cache vs. Value Prediction

15. Improving Prediction Accuracy Last Value Prediction Stride Prediction Finite Context Method Predictors (fcm)

16. Finite Context Models

17. Prediction Success

18. Conclusions Data value prediction increases performance by 5% on PowerPC 620 A performance gain of 23% is possible Future Developments More parallel execution units Better prediction models