1722968 - Add an optimization for GetAllInFlowRects to avoid expensive ancestor lookups in DOMIntersectionObserver.

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, task)

Comment 1

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1722968 - Add an optimization for GetAllInFlowRects to avoid expensive ancestor lookups in DOMIntersectionObserver. r=dholbert,jfkthame,TYLin,#layout-reviewers

Part of the issue with the profile in the blocked bug is that 30% of the
time is spent in nsLayoutUtils::FindNearestCommonAncestorFrame from
DOMIntersectionObserver::Update. That shouldn't be needed since in most
cases we know we're an ancestor.

We have an optimization for the root frame but DOMIntersectionObserver
keeps its rects relative to target. So we only need to do the
expensive transform for IB splits / fragmented flows.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e5c5516d8b08
Add an optimization for GetAllInFlowRects to avoid expensive ancestor lookups in DOMIntersectionObserver. r=jwatt

Comment 3

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/e5c5516d8b08