Bug 220914 – [JSC] WebAssembly.Global should support Funcref and Externref

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Yusuke Suzuki]

https://webassembly.github.io/reference-types/js-api/index.html#dom-global-global

[Yusuke Suzuki]

Note,

1. Wasm::Global itself supports externref / funcref already.
2. But JS binding around WebAssembly.Global does not support it (e.g. new WebAssembly.Global({ type: "externref", mutable: true });

[Dmitry]

Created attachment 418433 [details]
Patch

[Yusuke Suzuki]

Comment on attachment 418433 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=418433&action=review

r=me with comments.

> Source/JavaScriptCore/wasm/js/WebAssemblyGlobalConstructor.cpp:146
> +    RETURN_IF_EXCEPTION(throwScope, encodedJSValue());

Use `RETURN_IF_EXCEPTION(throwScope, {});` in newer code.

> Source/JavaScriptCore/wasm/js/WebAssemblyGlobalConstructor.cpp:151
> +        if (type == Wasm::Type::Funcref && argument.isUndefined())
> +            argument = jsNull();

Can we share this "default value" part with WasmTable etc.?

> Source/JavaScriptCore/wasm/js/WebAssemblyGlobalConstructor.cpp:152
> +        jsWebAssemblyGlobal->global()->set(globalObject, argument);

Insert `RETURN_IF_EXCEPTION(throwScope, { });` after calling a function which takes `globalObject` as a first parameter (this is a rough indicator of "it can throw").

> Source/JavaScriptCore/wasm/js/WebAssemblyGlobalConstructor.cpp:154
> +    RELEASE_AND_RETURN(throwScope, JSValue::encode(jsWebAssemblyGlobal));

RELEASE_AND_RETURN is not necessary if the evaluated part will not throw. Let's use `return`.

> JSTests/wasm/references/globals.js:42
> +  assert.throws(() => new WebAssembly.Global({ value: "anyfunc", mutable: true }, new Pelmen(calories)), WebAssembly.RuntimeError, "Funcref must be an exported wasm function (evaluating 'new WebAssembly.Global({ value: \"anyfunc\", mutable: true }, new Pelmen(calories))')");

Let's add a test, setting a wrong value via `.value = xxx`.

[Dmitry]

Created attachment 418707 [details]
Patch

[Yusuke Suzuki]

Comment on attachment 418707 [details]
Patch

r=me

[EWS]

Committed r272071: <https://trac.webkit.org/changeset/272071>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 418707 [details].

[Radar WebKit Bug Importer]

<rdar://problem/73763872>

[Yusuke Suzuki]

Oops! ::set should not be used since mutability can be an immutable. In that case, assertion hits. https://results.webkit.org/?suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fwasm%2Fjsapi%2Fglobal%2Ftype.tentative.any.html

I'll fix.

[Yusuke Suzuki]

Committed r272119: <https://trac.webkit.org/changeset/272119>