1566466 - JSScript isRelazifiable check should be consistent with when we keep LazyScript

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[Ted Campbell [:tcampbell]]

The check in [1] where we decide if we entrain the LazyScript after delazification is not the same as the check in [2] we use to allow relazification. The result is we keep LazyScripts alive when we'll never be able to use them again.

Another minor nit here is that we check hasDoNotRelazify() in [2] which is a runtime flag (used for pinning functions on stack for testing). This should be excluded from this check like jitcode is. We can have another helper function that checks the dynamic condition.

[1] https://searchfox.org/mozilla-central/rev/07f7390618692fa4f2a674a96b9b677df3a13450/js/src/vm/JSFunction.cpp#1563
[2] https://searchfox.org/mozilla-central/source/js/src/vm/JSScript.h#2683

Comment 1

[Ted Campbell [:tcampbell]]

Attachment: Bug 1566466 - Clean up relazification conditions. r?jandem

Move the relazification decisions to JSScript since the check is made after
delazification happens. The JSScript::isRelazifiable check inspects
characteristics of the script itself, while JSScript::canRelazify includes
additional checks for runtime conditions outside the script.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/14f33b78f0eb
Clean up relazification conditions. r=jandem

Comment 3

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/14f33b78f0eb

Comment 4

[Cristina Coroiu [:ccoroiu]]

Backed out 7 changesets (bug 1600439, bug 1566466, bug 1591598) for raptor crashes

Backout: https://hg.mozilla.org/integration/autoland/rev/4cb3934b76b14f04d8f8cd781f14a56693312f40

Failure push: https://treeherder.mozilla.org/#/jobs?repo=autoland&revision=14f33b78f0eb5e32fd3e9c116f21a23ab7221f26

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=279099999&repo=autoland&lineNumber=829

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1bd1069fa2b2
Clean up relazification conditions. r=jandem

Comment 6

[Cristina Coroiu [:ccoroiu]]

Backed out changeset 1bd1069fa2b2 (bug 1566466) on request by tcampbell for causing ccov Jit6 permafails

Backout: https://hg.mozilla.org/integration/autoland/rev/fde74a46394f181a273198dacaf3081223c4ea20

Comment 7

[Ted Campbell [:tcampbell]]

This patch changed the semantics of a test-only shell function. It failed on ccov builds because they still disable lazy parsing. The isRelazifiableFunction testing function should have old functionality restored, or the tests should be adjusted. The testing function should be better documented about what expectations are, especially transient blockers to relazification.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/mozilla-central/rev/616c216abffd
Clean up relazification conditions. r=jandem a=backout-reversal DONTBUILD

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9160b2617014
Clean up relazification conditions. r=jandem

Comment 10

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/9160b2617014

Comment 11

[Florin Strugariu [:Bebe]]

== Change summary for alert #24206 (as of Tue, 03 Dec 2019 00:08:40 GMT) ==

Improvements:

13% raptor-tp6-imgur-firefox-cold loadtime macosx1014-64-shippable opt 3,505.17 -> 3,042.50

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=24206