Firefox's JIT is getting significantly faster

Hi all,

The SpiderMonkey (JS) team has been working on a significant update to our JITs called WarpBuilder (or just Warp) [0,1]. Before we enable Warp by default in Nightly (hopefully next cycle in 83) we need your help dogfooding it.

Warp improves performance by reducing the amount of internal type information that is tracked, optimizing for a broader spectrum of cases, and by leveraging the same CacheIR optimizations used by last year’s BaselineInterpreter work [2]. As a result, Warp has a much simpler design and improves responsiveness and page load performance significantly (we're seeing 5-15% improvements on many visual metrics tests). Speedometer is about 10% faster with Warp. The JS engine also uses less memory when Warp is enabled.

To enable Warp in Nightly:

1. Update to a recent Nightly 2. Go to about:config and set the "javascript.options.warp" pref to true 3. Restart the browser

We're especially interested in stability issues and real-world performance problems. Warp is currently slower on various synthetic JS benchmarks such as Octane (which we will continue investigating in the coming months) but should perform well on web content.

If you find any issues, please file bugs blocking:

https://bugzilla.mozilla.org/show_bug.cgi?id=1613592

If you notice any improvements, we'd love to hear about those too.

Finally, we want to thank our amazing contributors André Bargull and Tom Schuster for their help implementing and porting many optimizations.

Turning Warp on is only our first step, and we expect to see a lot of new optimization work over the next year as we build on this. We are excited for what the future holds here.

Thanks! The Warp team

[0] WarpBuilder still utilizes the backend of IonMonkey so we don't feel it has earned the WarpMonkey name just yet. [1] https://bugzilla.mozilla.org/show_bug.cgi?id=1613592 [2] https://hacks.mozilla.org/2019/08/the-baseline-interpreter-a...

I think if Google detects that you've _ever_ logged into Google, it's trying to authenticate you when you visit a Google Groups page. Private mode is my default workaround for Google Groups links these days.

Unless there is another foundation with a browser promoting a free and open internet, my vote will always remain with them.

Is it though? Would you even notice it?

If there was an already short processing action, e.g. 1 second, now it would be 850ms -- hardly noticable.

If there was some long processing action, say 5 minutes, now it would take 4 minutes and 25 seconds.

Hardly something to write home about in either case...

Lars Bak, the v8 head:

"In 1994, he joined LongView Technologies LLC, where he designed and implemented high performance virtual machines for both Smalltalk and Java. After Sun Microsystems acquired LongView in 1997, Bak became engineering manager and technical lead in the HotSpot team at Sun's Java Software Division where he developed a high-performance Java virtual machine.".