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Comment by mort96 | Hacker News Reader

So I'm not overly familiar with either JITs, Apple's policies or emulators, so this may be a stupid idea, but I was thinking: Apple does allow exactly one JIT on iOS, in its JavaScript engine. What, technically, is preventing anyone from writing a recompiler from PowerPC machine code for the Wii to ASM.js (or even WebAssembly) and then throwing JavaScriptCore at it? It's not gonna be as fast as a recompiler straight to native code I guess, but could it be significantly faster than interpreting?

From some quick Googling, it seems like JavaScriptCore is running with the JIT disabled in most apps, but surely e.g Chrome is running with JIT enabled. Convincing Apple to let you use JavaScriptCore with JIT enabled might be easier than convincing them to let one run one's own JIT.

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JavaScriptCore doesn't use a JIT when used in your own apps. When you embed a WKWebView it runs out-of-process and has JIT enabled. Without the entitlement you cannot execute any written memory by your own process.

All 3rd party browsers today use WKWebView and add their own "chrome" over the rendered page. In essence Chrome/Firefox for iOS are really just Safari with custom chrome for bookmarks etc…

What exactly is preventing you from making an off-screen WKWebView and pointing it at some bundled HTML/JS which allows the app to run arbitrary JS through some IPC? I guess App Store guidelines would come in the way, but I bet it it would be technically possible

It is technically possible but the IPC will destroy you. You would need to transfer inputs and outputs as well as have JS shims to call it. Most of the code will be doing tons of memory accesses which will need to be transferred back and forth across the process boundary and orders of magnitude more cost.

If you did want to try the best approach is probably to compile Dolphin to WASM and render via WebGPU. Then you can JIT WASM. But I suspect that the overall performance will still be lower. (Although a web version of Dolphin would still be super cool.)

I don't think it would be as simple as compiling Dolphin to WASM. Since Dolphin itself implements a JIT compiler that emits native code you would need to also teach Dolphin to emit WASM code.

> e.g Chrome is running with JIT enabled. Convincing Apple to let you use

Current Chrome iOS app uses Webkit and JavascriptCore. I believe Chrome uses WKWebViews and so can take advantage of JIT-enbaled JSC.

As pointed out in the article, in the EU Apple has APIs and entitlements for other browser engines, including allowances for JIT. But as it's an entitlement you apply for, you'll only get it for web browsers

https://developer.apple.com/documentation/browserenginekit

https://developer.apple.com/support/alternative-browser-engi...

Other concerns raised by sibling comments aside, that'd amount to a new port effort, virtually equivalent to a web app.

Oh yeah it's a huge amount of work, I don't want to make it sound like I think people should "just" take Dolphin and port its JIT to JavaScript.

Bet there'd be interest in a web version of Dolphin.

Dosbox-on-the-web has proved pretty popular, and a lot of old games are available on the web that way.

> What, technically, is preventing anyone from writing a recompiler from PowerPC machine code for the Wii to ASM.js (or even WebAssembly) and then throwing JavaScriptCore at it

Self respect. At some point you have to recognize that the platform is hostile and abusive towards you, and it's not healthy to continue to engage.

> recognize that the platform is hostile and abusive

That's how Apple lost me as a customer, who had been a life-long user since early Macintosh days. It's an example of enshittification, death by a thousand cuts. Shame what they've done to the legacy, but the magic has been waning for a while. The elves left a long time ago, replaced by greedy sneaky humans.

Honestly it would be more cool if developers for once started to boycott Apple here, instead of jumping through their hoops.

Meh that won't happen until there are decent alternatives out there. Google's Android isn't such an alternative, and other options aren't supported by all the services people need to use.

> Google's Android isn't such an alternative

It absolutely is. Don't be delusional lol. Here's a video of dolphin running on android: https://www.youtube.com/watch?v=Tp-D4GvUxY4

Yes, but you get more money out a single Apple customer than from 5 android users, and that's the problem of this alternative.

It's about money, not technical capabilities.

Dolphin is free. 5x0=0. Then you have to consider the platform fees.

So for android: One time fee of $20, yearly $0 profit

For apple: Yearly fee of $100, yearly $-100 profit

It's an alternative if all you want is emulators on your phone of course. For me, Google Android isn't a meaningful alternative to iOS, simply because I trust Google even less than I trust Apple.

that's easy to alleviate https://grapheneos.org/

Custom ROMs is in the category of "other options", i.e not "Google Android" and not "iOS". I can't install the money transfer and banking apps I need on a phone with a custom ROM.

You can though. Google Play is available if you want it – preferably in a separated profile. Most banks work. Only NFC in Google Wallet/Pay is blocked.

Well I wish this was the case as well. Most developers writing apps are making them a for a company/employer. Try to telling whoever you work for to ignore iOS for moral/ethical reasons. Companies and even independent devs are just trying to make money. Also if a company or dev says no I am not going to jump through your crazy hoops Apple. Apple is not going to care some other company or dev will. It won't really effect apples bottom line much if at all. Entities publishing apps are a disparate group there is no coordination, Apple a single entity that also has the private cryptographic keys for these horribly locked down devices. So apple basically holds all the cards here when dealing with a non-coordinated of people and companies making apps. The only way Apple would care is you could some how basically get almost everyone to boycott making Apple apps.

It also does not help that most users don't understand that the way the device is locked down really limits their ability to truly own their device. Even those that have some understanding of how apple is basically infringing on the owners right of exclusion by not letting them load their own boot ROM and/or OS keys to sign OSes/apps themselves or sideload. Some how think that this being prevented is a good thing cause "security". Like what? You can't trust yourself, but will trust Apple okay then...

It’s a commonly repeated point that Apple needs developers, but it’s even more true to say that developers need Apple’s users.

Is the IT job market in such a state that we need Apple to have a decent income?

Isn’t that sort of what we’re seeing on VisionOS, where Netflix and YouTube are both like “Nah, we’ll wait…”?

A boycott here would be strange. This is a type of app that Apple did not support until recently, and I’m sure doesn’t really want to support. Finally they were strong armed into allowing it… I’m not sure what a boycott would prove, or to whom. Apple would just use it to argue against further opening up their App Store—saying “look, the developers don’t want to be here anyway”. The developers themselves wouldn’t lose out, since until recently it wasn’t even an option. I guess the only people who would even mind would be users who would want to run emulators on their iOS devices.

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