1573871 - Create less nsDisplayBackdropRootContainer items

Status: RESOLVED FIXED

(Core :: Web Painting, enhancement, P2)

Description

[Miko Mynttinen]

Bug 1178765 added support for backdrop-filter, for which we now create new display items when the frame has opacity or any filters set.

These items are big (they derive from nsDisplayWrapList) and for performance reasons we should avoid creating them whenever possible. We can definitely avoid creating them when WebRender is disabled, since the items are flattened for non-WR code path.
For WebRender, it might be possible to only create them when backdrop filter is inside the container, similarly how we do with nsDisplayBlendContainer and nsDisplayMixBlendMode.

Comment 1

[Connor Brewster [:cbrewster]]

Attachment: Bug 1573871 - Only create backdrop root containers when needed r?miko,mstange

Comment 2

[Connor Brewster [:cbrewster]]

https://treeherder.mozilla.org/#/jobs?repo=try&resultStatus=testfailed%2Cbusted%2Cexception&classifiedState=unclassified&revision=94534ff63263c205b30669009ad98dc9fee3b4a6

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e777dd79ae26
Only create backdrop root containers when needed r=miko,mstange

Comment 4

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/e777dd79ae26