1463752 - Optimize merging and flattening during ContainerState::ProcessDisplayItems()

Status: RESOLVED FIXED

(Core :: Web Painting, enhancement)

Description

[Miko Mynttinen]

I spotted a couple of small optimizations for ContainerState::ProcessDisplayItems():
1) Avoid unnecessary casts and checks during FLBDisplayItemIterator::StartNested()
2) Avoid allocating AutoTArray for merged display items, when merging cannot be done.

Locally on MBP these give roughly 2.5% performance improvement in talos displaylist_mutate test.

Comment 1

[Miko Mynttinen]

Attachment: Bug 1463752 - Part 1: Avoid unnecessary cast in FLBDisplayItemIterator::StartNested()

Review commit: https://reviewboard.mozilla.org/r/246134/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/246134/

Comment 2

[Miko Mynttinen]

Attachment: Bug 1463752 - Part 2: Avoid allocating AutoTArray when there are no items that can be merged together

Review commit: https://reviewboard.mozilla.org/r/246136/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/246136/

Comment 3

[Matt Woodrow (:mattwoodrow)]

Comment on attachment 8979957 [details]
Bug 1463752 - Part 1: Avoid unnecessary cast in FLBDisplayItemIterator::StartNested()

https://reviewboard.mozilla.org/r/246134/#review252376

Comment 4

[Matt Woodrow (:mattwoodrow)]

Comment on attachment 8979958 [details]
Bug 1463752 - Part 2: Avoid allocating AutoTArray when there are no items that can be merged together

https://reviewboard.mozilla.org/r/246136/#review252378

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ffb639607291
Part 1: Avoid unnecessary cast in FLBDisplayItemIterator::StartNested() r=mattwoodrow
https://hg.mozilla.org/integration/autoland/rev/cd3e33ad7970
Part 2: Avoid allocating AutoTArray when there are no items that can be merged together r=mattwoodrow

Comment 6

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/ffb639607291
https://hg.mozilla.org/mozilla-central/rev/cd3e33ad7970