1696447 - Consider sharing `CascadeData` objects more aggressively across shadow roots.

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Emilio Cobos Álvarez (:emilio)]

For shadow roots in the same document, with the same stylesheet list, we should be able to do something like this.

We have something like this already for UA sheets, so most of the code should be written already, I think.

Comment 1

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1696447 - Make the cascade data cache generic. r=#style,#layout-reviewers

We're going to use it both for UA sheets and for author styles in Shadow
DOM.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1696447 - Share CascadeData instances across ShadowRoots. r=#style,#layout-reviewers

This should be both a memory and speed win for pages using a lot of
Shadow DOM.

Depends on D107265

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5f595b1443a0
Make the cascade data cache generic. r=boris
https://hg.mozilla.org/integration/autoland/rev/f088cf41fc03
Share CascadeData instances across ShadowRoots. r=boris

Comment 4

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/5f595b1443a0
https://hg.mozilla.org/mozilla-central/rev/f088cf41fc03

Comment 5

[Andra Esanu (needinfo me)]

== Change summary for alert #29227 (as of Thu, 11 Mar 2021 22:45:52 GMT) ==

Improvements:

Ratio	Suite	Test	Platform	Options	Absolute values (old vs new)
38%	perf_reftest_singletons	link-style-cache-1.html	macosx1015-64-shippable-qr	e10s stylo webrender	600.88 -> 372.65
31%	perf_reftest_singletons	link-style-cache-1.html	windows10-64-shippable	e10s stylo	709.48 -> 489.06
30%	perf_reftest_singletons	link-style-cache-1.html	windows10-64-shippable-qr	e10s stylo webrender	701.73 -> 494.38
15%	perf_reftest_singletons	inline-style-cache-1.html	windows10-64-shippable	e10s stylo	1,744.20 -> 1,477.40
15%	perf_reftest_singletons	inline-style-cache-1.html	macosx1015-64-shippable-qr	e10s stylo webrender	1,283.24 -> 1,090.57

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=29227