On: iOS 14 will let you change your default email and web browser apps

[tarkin2]

Do you know of these security privileges? I've never heard either google or mozilla complain about them.

[JoshTriplett → tarkin2]

A browser's JIT needs permission to dynamically generate code and then execute it, which is the primary permission Apple doesn't grant to third parties.

Other browsers on iOS just wrap Safari's WebKit in a different UI.

[tarkin2 → JoshTriplett]

They're not allowed to ship their own engines, in addition, rather than this being framed as a JIT issue.

[rictic → JoshTriplett]

This isn't true, other browsers can run JITless. JIT is a performance optimization to be sure, but this doesn't explain why Apple bans other browsers. See https://twitter.com/slightlylate/status/1274012259451207681

Disclosure: I work at Google, formerly Chrome team, never worked on this.

[shuckles → rictic]

I didn't know about this. Thanks for sharing. It does mention a 40% performance impact to running JITless. What is the power impact?

[robocat → JoshTriplett]

V8 has a pure interpreted mode for JavaScript and RegExps: https://v8.dev/blog/jitless

Many sites only need light JavaScript usage and would not run significantly slower. wasm is not supported in jitless mode. Link pulled from twitter link in sister comment by rictic.

[monocasa → robocat]

It destroys battery life though.

[sudosysgen → JoshTriplett]

Code generation is not a safety issue. If you have the privileges to run code then generating code should not cause more problems unless the OS has significant vulnerabilities.

[miohtama → JoshTriplett]

I think they had fixed this in the latest iOS versions. It is good for AAA game engines and such as well.