1622828 - Implement wasm->js multi-value calls

Status: RESOLVED FIXED

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

Description

[Andy Wingo [:wingo]]

The patch to be attached will let wasm modules import JS functions that return multiple values.

Spec here: https://webassembly.github.io/multi-value/js-api/index.html#exported-function-exotic-objects

Specifically, I paste some contents inline here:

To run a host function from the JavaScript object func, type functype, and list of WebAssembly values arguments, perform the following steps:

1. Let [parameters] → [results] be functype.
2. Let ret be ? Call(func, undefined, jsArguments).
3. If results is empty, return « ».
4. Otherwise, if results’s size is 1, return « ? ToWebAssemblyValue(ret, results[0]) ».
5. Otherwise:
   1. Let method be ? GetMethod(ret, @@iterator).
   2. If method is undefined, throw a TypeError.
   3. Let values be ? IterableToList(ret, method).
   4. Let wasmValues be a new, empty list.
   5. If values and results do not have the same length, throw a TypeError.
   6. For each value and resultType in values and results, paired linearly, append ToWebAssemblyValue(value, resultType) to wasmValues.
   7. Return wasmValues.

Comment 1

[Andy Wingo [:wingo]]

Attachment: Bug 1622828 - Implement wasm->js multi-value calls

This patch implements calls from WebAssembly to JS, where the JS
function returns multiple values. The multiple values are returned as
an iterable.

Spec here:
https://webassembly.github.io/multi-value/js-api/index.html#exported-function-exotic-objects

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5bd28470648f
Implement wasm->js multi-value calls r=lth

Comment 3

[Stefan Hindli [:stefan_hindli]]

Backed out changeset 5bd28470648f (Bug 1622828) for linux build bustages CLOSED TREE

https://treeherder.mozilla.org/#/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception&classifiedState=unclassified&fromchange=ebedd05e0d17283d20d2a4082c61cbc041765b54&selectedJob=295602693

https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=295602693&repo=autoland&lineNumber=7125

Comment 4

[Pulsebot]

Backout by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/746cfdd2c4d5
Backed out changeset 5bd28470648f for linux build bustages CLOSED TREE

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5c02a3e6d56e
Implement wasm->js multi-value calls r=lth

Comment 6

[Razvan Maries]

Backed out for build bustages.

Push with failure: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedJob=295618032&resultStatus=testfailed%2Cbusted%2Cexception&revision=5c02a3e6d56e78a513a67ad7c6119062c81a72a3

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=295618032&repo=autoland&lineNumber=4522

Backout: https://hg.mozilla.org/integration/autoland/rev/dc1c34d3f21b9a0ee12ac53c7db1a75804c21feb

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4f66cfb5d2f2
Implement wasm->js multi-value calls r=lth

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/4f66cfb5d2f2