Escape Analysis for the HotSpot Client Compiler

In this research project, we implemented a fast algorithm for escape analysis. It detects objects that are accessible only by a single method or thread. Its results are used to replace fields of objects with scalar variables, to allocate objects on the stack instead of the heap, and to remove synchronization. The produced machine code is smaller and executes faster because fewer objects are allocated on the heap and the garbage collector runs less frequently. Deoptimization is used to handle dynamic class loading. There are currently no plans to integrate this work into the product version, however it influenced the implementation of escape analysis for the server compiler.

Publications

• Thomas Kotzmann:
  Escape Analysis in the Context of Dynamic Compilation and Deoptimization
  PhD thesis, Institute for System Software, Johannes Kepler University Linz, 2005.
  Describes the details of all algorithms and contains an extensive evaluation as well as a survey of related work.
• Thomas Kotzmann, Hanspeter Mössenböck:
  Run-Time Support for Optimizations Based on Escape Analysis
  Intl. Symposium on Code Generation and Optimization (CGO'07), pp. 49-60. IEEE Computer Society, 2007. doi:10.1109/CGO.2007.34
  Conference paper that describes the support necessary in the runtime system, the garbage collector, and the deoptimization framework.
• Thomas Kotzmann, Hanspeter Mössenböck:
  Escape Analysis in the Context of Dynamic Compilation and Deoptimization
  ACM/USENIX Intl. Conf. on Virtual Execution Environments (VEE'05), pp. 111-120. ACM Press, 2005. doi:10.1145/1064979.1064996
  Conference paper that describes the core algorithm for escape analysis that is integrated into the client compiler.