1938859 - Remove JS::TransitiveCompileOptions::deoptimizeModuleGlobalVars

Status: REOPENED

(Core :: JavaScript Engine, task, P3)

Description

[Tooru Fujisawa [:arai]]

The JS::TransitiveCompileOptions::deoptimizeModuleGlobalVars was added to keep the backward compatibility of the Cu.import behavior with the "JSM to ESM" shim, which required all the global variables being on the environment object.

https://searchfox.org/mozilla-central/rev/ab26669b610c2245ac9fcf9cecc3612d73297d93/js/public/CompileOptions.h#335-343

// De-optimize ES module's top-level `var`s, in order to define all of them
// on the ModuleEnvironmentObject, instead of local slot.
//
// This is used for providing all global variables in Cu.import return value
// (see bug 1766761 for more details), and this is temporary solution until
// ESM-ification finishes.
//
// WARNING: This option will eventually be removed.
bool deoptimizeModuleGlobalVars = false;

Once the JSM API is removed, this option can be removed.
The last and the only consumer will be removed in bug 1881888

Comment 1

[Tooru Fujisawa [:arai]]

Attachment: Bug 1938859 - Remove TransitiveCompileOptions.deoptimizeModuleGlobalVars. r?jonco!

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e9c90fbcc514
Remove TransitiveCompileOptions.deoptimizeModuleGlobalVars. r=jonco

Comment 3

[Cristina Horotan [:chorotan]]

https://hg.mozilla.org/mozilla-central/rev/e9c90fbcc514

Comment 4

[Serban Stanca [:SerbanS]]

Backed out as requested by arai for causing Bug 1946592.

• Backout link

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9a3a01f76cb5
Remove TransitiveCompileOptions.deoptimizeModuleGlobalVars. r=jonco

Comment 6

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/9a3a01f76cb5

Comment 7

[Pulsebot]

Backout by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/6900871c5dfc
Backed out 2 changesets (bug 1938859, bug 1941472) for causing high frequency failures at browser_bannerClicking.js.

Comment 8

[Atila Butkovits]

Backed out for causing high frequency failures at browser_bannerClicking.js

Backout link: https://hg.mozilla.org/integration/autoland/rev/6900871c5dfcdeb2e0de821f57f877b64d43bd5e

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=9a3a01f76cb54396262610ed1487e7cd994a2e61&selectedTaskRun=eS5P6QbUTlqiztIrMXgReQ.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=497828384&repo=autoland&lineNumber=5608

Comment 9

[Cosmin Sabou [:CosminS]]

Backout merged to central: https://hg.mozilla.org/mozilla-central/rev/6900871c5dfc