schuay's comments

schuay | 7 years ago | on: JIT-Less V8

> I'm curious if the runtime flag to enable JITless mode could also be enabled at compile time, removing the JIT compiler from the binary entirely. That could be really useful for projects where memory comes at a premium (and performance is not a major concern), like micropython but for JavaScript.

Theoretically yes, but this is not implemented. It should not be too hard to drastically reduce binary size with a build-time flag.

> I assume this also doesn't support WASM when the JIT is disabled (or rather, when you can't write to executable memory), but if it did it could be a neat way to write decently performant software for tiny systems with just some JavaScript "glue".

Correct, wasm is currently unsupported. Interpreted wasm is possible in the future, but would likely be very slow.

schuay | 7 years ago | on: JIT-Less V8

While bytecode handlers (and other builtins) are generated by TurboFan, this happens at V8-compile-time, not at runtime. Their generated code is shipped embedded into the binary as embedded builtins.

schuay | 7 years ago | on: JIT-Less V8

That is not yet clear. Early adopters have reported (jitless) V8 to be at least as fast as (jitless) JSC on Octane2 on a native iOS device.

schuay | 7 years ago | on: JIT-Less V8

A fast V8 with jitting isn't going away. Jitless V8 is meant for embedders that either cannot or do not want to allocate executable memory at runtime.

(Also, in many common real-world workloads the performance regression is minimal.)

schuay | 7 years ago | on: JIT-Less V8

I think that should be possible. The main restriction seems to be

2.5.6 Apps that browse the web must use the appropriate WebKit framework and WebKit Javascript.

Using V8 to execute JS without 'browsing the web' sounds okay.

And perhaps also this, although it is not clear to me whether downloaded JS scripts are considered 'code':

2.5.2 Apps should be self-contained in their bundles, and may not read or write data outside the designated container area, nor may they download, install, or execute code which introduces or changes features or functionality of the app, including other apps. [...]

https://developer.apple.com/app-store/review/guidelines/

Anything else? I'm curious to learn more..