javascriptfirefoxjit

Profiling Javascript JIT in Firefox


I recently came across this awesome article and presentation about Breaking the JavaScript Speed Limit with V8. This is awesome!

However, I'm a Firefox fan and wondering if there's a way to profile the JIT for Mozilla's tools. Mostly I'd like to see if a compilation has to bail or is missing out on some kind of optimization that could otherwise be had.

Is this possible? Thanks!


Solution

  • It's possible in debug Firefox builds to some extent. In an opt build you can install https://addons.mozilla.org/en-US/firefox/addon/jit-inspector/ which will tell you what the JIT is doing, but not what it could have done....