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A Region-Based Compilation Technique for a Java Just-In-Time Compiler

A Region-Based Compilation Technique for a Java Just-In-Time Compiler. Toshio Suganuma, Toshiaki Yasue and Toshio Nakatani. Presenter: Ioana Burcea. Agenda. Research question FBC – function based compilation VS RBC – region based compilation System overview Region exit handling

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A Region-Based Compilation Technique for a Java Just-In-Time Compiler

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  1. A Region-Based Compilation Technique for a Java Just-In-Time Compiler Toshio Suganuma, Toshiaki Yasue and Toshio Nakatani Presenter: Ioana Burcea

  2. Agenda • Research question • FBC – function based compilation VS • RBC – region based compilation • System overview • Region exit handling • Region selection • Special optimizations • Partial inlining • Partial dead code elimination • Escape analysis • Experimental results

  3. Research Question • Method – the right unit of compilation? • Methods often contain rarely or never executed code • Waste of compilation time • Conservative data flow analysis • Restrictive method inlining • Possible solution: • Region-based compilation (RBC) • Region selection • Partial inlining • Region exit handling

  4. Dynamic Optimization Framework • Sampling profiler • The more CPU time used the hotter the method • Instrumenting profiler • Basic block execution frequency • Virtual/interface call receiver type distribution

  5. Region-Based Compilation

  6. Intra-Procedural Region Selection • Static heuristics • Rare • Backup blocks / guards (e.g., devirtualizations) • Blocks that end with an exception throwing instruction • Exception handler blocks • Blocks containing unresolved or uninitialized class references • Non-rare • Blocks that end with normal return instructions • Dynamic profile information • A block is non-rare if its dynamic count is beyond a certain threshold (which value they use?) • Higher priority when conflicting with static heuristics • Iterative framework for region selection

  7. Region Exit Handling

  8. Partial Inlining

  9. Special Optimizations • Partial dead code elimination • Pushing computations that are only live in the region exit paths to the region exit BB • Partial escape analysis • Objects that are local to the method are allocated to the stack • Objects that are local to a single thread do not need synchronization

  10. Partial Escape Analysis

  11. Experimental Results • Machine • Pentium 4 Xeon 2.8GHz, 1Gb • WinXP • Benchmarks • SPECjvm98-1.04 • Initial and max heap 128 Mb • SPECjbb2000-1.02 • Initial and max heap 256 Mb • Thresholds • MMI to level-0 compilation: 500 • Timer interval for sampling profiler: 3 ms • The number of samples: 10,000 • The max number of OSR: 10 • Other thresholds (rare bb, promotion to level-1 & level-2 compilation) ??

  12. Configurations • 5 configurations • FBC – function based compilation (the baseline) • RBC-noopt – RBC without any special optimizations • RBC-nopi – RBC with partial dead code elimination and partial escape analysis, without partial inlining • RBC-full – all optimizations on • RBC-offline – RBC-full with offline profile information • No OSR, no recompilation (?)

  13. Statistics for RBC

  14. Performance Improvement

  15. Compile Time Ratio

  16. Compiled Code Size Ratio

  17. Peak Work Memory Usage Ratio

  18. Discussion

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