WebAssembly build with NativeAOT-LLVM

[yowl]

Hi, has anyone attempted to build the Wasm head with NativeAOT-LLVM? I did this for Uno as an experiment some time ago and it was quite a bit of effort, but NativeAOT-LLVM and Mono are more closely aligned these days so it might not be so hard.

[maxkatz6]

No, I don't think anybody tried, but there was an interest.
It will likely involve some wasm backend changes as well.

From what we need to be working:

1. JS interop like JSImport with callbacks and JSHost.ImportAsync. I don't think we have any JSExport. But it might be needed as a replacement for Task Main call, which is required to initialize Avalonia backend. https://github.com/AvaloniaUI/Avalonia/tree/master/src/Browser/Avalonia.Browser/Interop
2. StaticWebAssets support OR WasmExtraFilesToDeploy support - Avalonia needs to include avalonia.js and storage.js files from the nuget package via props/targets - https://github.com/AvaloniaUI/Avalonia/tree/master/src/Browser/Avalonia.Browser/build
3. Emscripten GL support - https://github.com/AvaloniaUI/Avalonia/blob/master/src/Browser/Avalonia.Browser/build/Avalonia.Browser.targets#L8C6-L8C31 +

   Avalonia/src/Browser/Avalonia.Browser/webapp/modules/avalonia/canvas.ts

   Line 16 in 9646164

   return module?.GL ?? self.AvaloniaGL ?? self.SkiaSharpGL;

4. And SkiaSharp working on top of that Emscripten GL. Can be either 2.88 or 3.0 (newer one is experimental).

Preferably to try it with latest nightly builds (master) or release/11.1 branch.

[yowl]

Or they are all WebGL I suppose.

[maxkatz6]

Yeah, they all are webgl. Just at different times it was different one. Since we dropped support for .NET 7 WASM SDK, and I don't think SkiaSharpGL exists anymore either, only the first one makes the most sense.

[maxkatz6]

I.e. before we had such hacks for Emscripten https://github.com/AvaloniaUI/Avalonia/blob/11.0.10/src/Browser/Avalonia.Browser/interop.js#L8. mergeInto usage was later removed in master, and replaced with <EmccExportedRuntimeMethod Include="GL" />

[yowl]

I did have WebGPU working with some manual bindings but haven't tried WebGL, so that will be interesting. For the JS side we have at least some of JSImport working, I will create some tests for the async and callbacks to see what state they are in.

[maxkatz6]

Hi!
I am tinkering software renderer support right now, and was wondering if I can try NativeAOT-LLVM running.

Do you know if there is a Hello World app similar to .NET 8 WASM templates? Something like this but with NativeAOT-LLVM. Specifically with a support of JSImport/JSExport and dotnetjs.
This doc also doesn't have information on that.

I know it should be possible to run Avalonia now without any JSImport/JSExport, but with some work around dll imports, but I was wondering if we can go easier now.

[yowl]

Awesome, I did have skia sharp working with just the software renderer a few years back https://github.com/yowl/wskia, but hit mono/SkiaSharp#1931 hopefully that problem no longer exists.

[yowl]

I see you are having a go from the runtimelab board (dotnet/runtimelab#2434 (comment)) I've been busy fixing the nuget for NativeAOT-LLVM (merging from upstream) so haven't had a chance to start looking at this. Let me know if you have any questions with the build or support.

[yowl]

The latest packages have better JS support, but there are still some problems getting the template app to start. For example SkiaSharp uses managed delegates to pass to Skia. These wont work in AOT and need to be converted to function pointers. I have started to try that, but building SkiaSharp just for wasm doesnt seem easy.

[charlesroddie]

FYI @mattleibow
We are using skiasharp in browser (which currently involves mono/blazor) as a POC and wait on nativeaot for having something release-worthy. I think others will be in the same boat and that skiasharp/nativeaot/wasm is going to be an v impactful combo.

[maxkatz6]

I haven't had time recently to do another test on LLVM. But I still planning to do that.
Meanwhile we had some improvements with .NET 9 WASM threading support in Avalonia, making backend a bit more flexible on the way.

[maxkatz6]

See #16211 for continuation of the discussion