Summit2008/Sessions/Proposals/Tracing and JavaScript performance
Andreas Gal, Jim Blandy, Brendan Eich, Mike Shaver
Tracing and JavaScript performance
Tracing is a technique for implementation of just-in-time compilation well-suited to the needs of JavaScript on the web: it exhibits extremely good compilation performance (in space and speed), even when performing aggressive optimizations, and can efficiently cope with dynamic typing. In addition, it can be implemented in a minimally invasive and incremental manner. Tracing is employed in the experimental Hotpath Java virtual machine, the upcoming luajit2 implementation of the Lua language, the "Tamarin Tracing" ActionScript/JavaScript runtime, and now in the "Tracemonkey" project to bring native code performance to Mozilla's Spidermonkey JavaScript engine.
This session will provide a background in trace-based JIT compilation, an overview of the current state of Mozilla's tracing-related work, and future plans. Spirited discussion of relative implementation priorities and schedules will no doubt ensue.
Fundamentals of tracing: an introduction to the basic principles of tracing (link to papers)
- trace specialization and guarding
- shape induction
- interaction between interpreter and JIT compiler
- applying optimizations to traces
nanojit: a lightweight native code generator specialized for tracing
- implementation of TSSA
- back-end implementation status
Tamarin Tracing status:
- relationship to "Tamarin Central"
- status and near-term goals
- performance characteristics
- current challenges
Tracemonkey status: an overview of current Tracemonkey capabilities, and discussion
- differences from Tamarin Tracing
- work so far (timeline, design choices)
- near-term goals
- preliminary performance results
- current challenges
Future work: making more of our code available to tracing, additional optimizations
- self-hosting the DOM
- escape analysis and allocation removal
Tracing beyond JavaScript: can we apply tracing techniques to other areas of code?
Further reading:
