Bug 178946 – WebAssembly: update arbitrary limits to what browsers use

• Component: WebAssembly
• Status: RESOLVED FIXED

[JF Bastien]

https://github.com/WebAssembly/design/issues/1138 discusses the arbitrary function size limit, which it turns out Chrome and Firefox didn't enforce. We didn't use it because it was ridiculously low and actual programs ran into that limit (bummer for Edge which just shipped it...). Now that we agree on a high arbitrary program limit, let's update it! While I'm doing this there are a few other spots that I'd polish.

[JF Bastien]

<rdar://problem/34257412>

[JF Bastien]

<rdar://problem/34501154>

[JF Bastien]

Created attachment 325177 [details]
patch

[Saam Barati]

Comment on attachment 325177 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=325177&action=review

> Source/JavaScriptCore/wasm/WasmB3IRGenerator.cpp:514
> +    size_t totalBytes = m_locals.size() + count;

Don't you want this to be Checked?

> Source/JavaScriptCore/wasm/WasmB3IRGenerator.cpp:515
> +    WASM_COMPILE_FAIL_IF((static_cast<uint32_t>(totalBytes) < count) || !m_locals.tryReserveCapacity(totalBytes), "can't allocate memory for ", totalBytes, " locals");

Why not use Checked?

> Source/JavaScriptCore/wasm/WasmFormat.cpp:41
> +    size_t totalBytes = sizeof(Segment) + sizeInBytes;
> +    if (static_cast<uint32_t>(totalBytes) < sizeInBytes)
> +        return nullptr;

Why not use checked<uint32_t>?

> Source/JavaScriptCore/wasm/js/JSWebAssemblyTable.cpp:65
> +    m_jsFunctions = MallocPtr<WriteBarrier<JSObject>>::malloc((sizeof(WriteBarrier<JSObject>) * Checked<size_t>(size())).unsafeGet());

why?

[JF Bastien]

Created attachment 325180 [details]
patch

Address comments.

[WebKit Commit Bot]

Comment on attachment 325180 [details]
patch

Clearing flags on attachment: 325180

Committed r224122: <https://trac.webkit.org/changeset/224122>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.