[Fiber] Set profiler values to doubles

[sebmarkbage]

At some point this trick was added to initialize the value first to NaN and then replace them with zeros and negative ones.

This is to address the issue noted in #14365 where these hidden classes can be initialized to SMIs at first and then deopt when we realize they're actually doubles.

However, this fix has been long broken and has deopted the profiling build for years because closure compiler optimizes out the first write.

I'm not sure because I haven't A/B-tested this in the JIT yet but I think we can use negative zero and -1.1 as the initial values instead since they're not simple integers. Negative zero === zero (but not Object.is) so is the same as far as our code is concerned. The negative value is just < 0 comparisons.

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
react-compiler-playground	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 11, 2024 0:33am

[react-sizebot]

Comparing: bac33d1...2dff09c

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.js	=	6.68 kB	6.68 kB	=	1.82 kB	1.82 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	505.22 kB	505.22 kB	=	90.29 kB	90.29 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	=	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	=	512.56 kB	512.56 kB	=	91.52 kB	91.52 kB
facebook-www/ReactDOM-prod.classic.js	=	600.88 kB	600.88 kB	=	106.29 kB	106.29 kB
facebook-www/ReactDOM-prod.modern.js	=	577.17 kB	577.17 kB	=	102.43 kB	102.43 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 87b3818

[rickhanlonii]

I've also noticed that the effects in the profiling builds are like 2x as slow or more because of the time spent in the recordLayoutEffectsDuration and recordLayoutEffectsDuration functions

react/packages/react-reconciler/src/ReactProfilerTimer.js

Line 133 in 6ddcbd4

function recordLayoutEffectDuration(fiber: Fiber): void {

I assumed that this is because we're searching back up the tree for the Profiler component to store the duration on, but would this also depot, because this.stateNode.effectDuration isn't defined until it's dynamically set:

react/packages/react-reconciler/src/ReactFiber.js

Lines 827 to 830 in 8d68da3

	fiber.stateNode = {
	effectDuration: 0,
	passiveEffectDuration: 0,
	};

[sebmarkbage]

The stateNode is always created as a pointer field in createFiber. It’s just updated later. So that should be fine.

[kassens]

Thanks for the fix!

Build diff view doesn't load (500) but your description makes sense.