I've been diving into V8's JIT compiler and I'm curious about how it optimizes JavaScript functions. I understand that factors like function usage frequency and type stability play a role in optimization, but I'm wondering if there's a way to actually see which functions are being optimized or potentially de-optimized.
3 Answers
You can actually check this out! First, download V8 and compile it on your machine. Then run your JavaScript code through it. Just a heads up though, you might need some knowledge of Assembly to fully get it.
Appreciate the info! Will definitely try that out.
I heard that there are flags to check for inlined and not inlined functions in Node.js. Not too sure about the compiled functions though; maybe there are flags for functions that are just generally optimized?
Not exactly sure how granular you can get, but there are several `--v8` flags you can pass when running Node.js to get some insight into the optimization details. Check out the official Node.js docs for more on that.
Good to know! I found that using `--allow-natives-syntax` lets you access a ton of native V8 methods like `%GetOptimizationStatus(fn)` which can give you more info about how functions are optimized.
Exactly! Using those flags can really help you understand what's happening under the hood.
That sounds like a cool approach! Thanks for the tip!