Support SIMD

[dtruffaut]

SIMD instructions (https://v8.dev/features/simd) are interesting for parallel processing tasks like

• Machine Learning (Tensorflow)
• Image manipulation
• ...etc.

For example, WASM VIPS (https://github.com/kleisauke/wasm-vips), used for image manipulation, requires a platform that supports SIMD.

For V8-based engines, at least version 9.1.54 is required to match the final SIMD opcodes, this corresponds to Chrome 91, Node.js 16.4.0 and Deno 1.9.0.

For Spidermonkey-based engines, the JavaScript engine used in Mozilla Firefox and whose version numbers are aligned, at least version 89 is required.

JavaScriptCore-based (e.g. Safari, Bun) engines are currently not supported.

WASM VIPS cannot currently run on Cloudflare Workers for other reasons (SharedBufferAPI)
See kleisauke/wasm-vips#2

That being said, supporting SIMD would make Cloudflare Workers a step closer to the browser's web workers.

[anarchodin]

The V8 documentation page you referred to suggests using wasm-feature-detect to check if the WASM engine supports SIMD instructions. According to that, workerd already supports SIMD instructions, so that shouldn't be an obstacle to getting wasm-vips to work. The fact that it assumes that thread spawning (new Worker()) is available seems to be the real stumbling block.

[kentonv]

AFAIK, Cloudflare Workers has supported SIMD ever since V8 turned it on by default, which was years ago.

That said, I haven't tested it personally. Do you have some reason to believe that SIMD doesn't work on Workers?

[dtruffaut]

Good to know !

I did not test the support of SIMD.

I simply needed to know if it was supported or not.

As a developer, it is sometimes hard to track what feature is available or not on the platform, as Workers is not exactly Chrome nor V8.

I understand that documenting every supported feature can be complex and time consuming.

Maybe a matrix with known supported or at least known unsupported features could help to enlight developers in their design choices, before the development phase (before they engage development costs).

I close this issue.

Thanks for your reactivity !

[irvinebroque]

We've tested and verified that SIMD is supported and works on Workers:

https://developers.cloudflare.com/workers/platform/web-assembly/#simd