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Comment by fenomas | Hacker News Reader

Speaking as someone tuning a JS game, I focus on V8 over other engines because there are great articles around that explain in detail what v8 knows how to optimize, what causes functions to deopt, what kicks object property lookups into slow mode, etc. Articles explaining this for SpiderMonkey would be greatly appreciated!

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FWIW, people in Mozilla are working on a "JIT coach", which will tell you if performance critical sections of your code aren't getting JITed, and why. I believe this is almost ready for use, though I'm not sure when it will be presented.

Sounds analogous to the way the chrome profiler tells you when functions have permanently deoptimized, right? That would be a terrific feature for Firefox, looking forward to it!

Could you recommend a few articles?

On v8 right? This one is probably the best broad overview:

http://www.html5rocks.com/en/tutorials/speed/v8/

To get into the gory details google Vyacheslav Egorov - he's a v8 engineer with a number of talks on YouTube, presentation slides, and blog posts on v8 internals. He also maintains a tool called IRhydra, that lets you examine functions after they've been compiled into v8's internal representation.

I am glad you find my stuff useful enough to recommend it to other people! Thanks.

I just wanted to point out a minor detail: I am an ex-V8 engineer - I have not been working on V8 since 2012.

Duly noted, and thanks ;)

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