1871146 - ToValType support for GC types is non-standard

Status: RESOLVED FIXED

(Core :: JavaScript: WebAssembly, task, P2)

Description

[Ryan Hunt [:rhunt]]

The JS-API for the GC proposal was not extended to support 'anyref' and others for ToValType. We implemented all the GC heap type shorthands plus a form for non-nullable types. V8 also implemented some of the GC heap type shorthands. This is being discussed upstream in (https://github.com/WebAssembly/gc/issues/500). We should probably unship our support for the non-nullable types at a minimum.

Comment 1

[Ryan Hunt [:rhunt]]

As a first step, let's remove support for parsing objects into 'reftype' by removing MaybeToRefType [1]. I'm not sure if we use this in tests or not, if we do we'll need to find a workaround.

The easiest way to test this is to use the Global JS-API: new WebAssembly.Global({value: V, mutable: true}, initialValue).

[1] https://searchfox.org/mozilla-central/rev/3c72de9280ec57dc55c24886c6334d9e340500e8/js/src/wasm/WasmValType.cpp#153

Comment 2

[Julien Pages [:jpages]]

This is used in some tests:
https://searchfox.org/mozilla-central/source/js/src/jit-test/tests/wasm/function-references/reftype-parse.js#20-51
https://searchfox.org/mozilla-central/source/js/src/jit-test/tests/wasm/function-references/non-nullable-table.js#43-44,52-61

Comment 3

[Ryan Hunt [:rhunt]]

The reftype-parse.js tests you link to can be removed, as they're only really testing that this functionality exists.

The non-nullable-table.js tests are a little trickier. I think the simplest thing would be to change from:

let x = new WebAssembly.Table({initial: X, element: { ... }});

To:

let x = new wasmEvalText(`(module (table (export "x") ${elementType} ${initialValue}))`).exports.x;

My table syntax might not be right, but basically instantiate a module that defines and exports a table with the non-nullable reference type in it. This should do the same thing as the JS-API table constructor.

Comment 4

[Julien Pages [:jpages]]

Attachment: Bug 1871146 - wasm: Unship the support for non-nullable types in the JS-API. r=rhunt

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5e82ea558f45
wasm: Unship the support for non-nullable types in the JS-API. r=rhunt

Comment 6

[pstanciu]

https://hg.mozilla.org/mozilla-central/rev/5e82ea558f45