1620986 - Create run-time switch for wasm multi-value

Status: RESOLVED FIXED

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

Description

[Lars T Hansen [:lth]]

For ease of Cranelift testing there should be a run-time switch for every feature that is supported by our regular compilers but not by Cranelift, and that is enabled by default at compile time. That way, Cranelift testers don't need a separate configuration.

The only such feature we have right now is multi-value.

With Wingo's latest multi-value patch it is easy to add such a switch in the validator: if the switch disables the feature we allow at most one function result, and there are restrictions on blocks and loops that escape me at the moment.

Comment 1

[Lars T Hansen [:lth]]

It looks like this is all very nicely set up, as far as I can tell whether we allow multiple values for anything depends on the value of WasmMultiValueFlag(cx) in WasmJS.cpp, so all we need to do is to add the command-line switch in the shell and the pref in the browser and the plumbing to get those values into the cx, and then test the value in the cx.

Comment 2

[Lars T Hansen [:lth]]

Attachment: Bug 1620986 - Introduce run-time switch for multi-value. r?bbouvier,wingo

This adds a JS shell command line argument to disable multi-value (if
it is enabled at compile time) and an about:config option to do the
same in the browser.

At this time, multi-values are not enabled in the browser, so the
about:config option is not visible.

Comment 3

[Lars T Hansen [:lth]]

Manually tested this in the shell; with a default configuration but with switches --no-wasm-multi-value --shared-memory=off --wasm-compiler=cranelift, cranelift is indeed available as it should be.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/531bdd018faa
Introduce run-time switch for multi-value.  r=bbouvier,wingo

Comment 5

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/531bdd018faa

Comment 6

[Lars T Hansen [:lth]]

This needs an additional refinement in dom/workers/RuntimeService.cpp, which also reads prefs.

Comment 7

[Lars T Hansen [:lth]]

Attachment: Bug 1620986 - Workers should read multi-value pref. r?bbouvier

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/230b51ed8bdf
Workers should read multi-value pref.  r=bbouvier

Comment 9

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/230b51ed8bdf