1638413 - gfx.webrender.compositor pref not honored on macOS after bug 1632259

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P3)

Description

[Sam Johnson]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

1. Install Nightly 2020-05-03 build on a macOS system
2. Enable gfx.webrender.all and gfx.webrender.compositor prefs in about:config and restart Nightly
3. Observe compositor preference being honored (i.e., partial present and black displayed in place of vibrancy)
4. Update Nightly to 2020-05-04 build
5. Observe compositor preference is no longer honored (partial present is no longer working, and vibrancy is working)

Actual results:

macOS compositor support in WebRender is not being used (partial present is not working; small animations cause the entire window to be updated per Quartz Debug observation)
I am using macOS 10.13.6 on this system, but the regression is observed on a 10.15.5 system as well.

Expected results:

The gfx.webrender.compositor preference should be honored, since it is enabled.

Mozregression narrowed this down to the following:
2020-05-15T12:24:34.683000: INFO : Narrowed integration regression window from [bb2c3cc7, 8accdd61] (3 builds) to [bb2c3cc7, 7ba7a04c] (2 builds) (~1 steps left)
2020-05-15T12:24:34.710000: DEBUG : Starting merge handling...
2020-05-15T12:24:34.710000: DEBUG : Using url: https://hg.mozilla.org/integration/autoland/json-pushes?changeset=7ba7a04cfa43596cdd87041c50563adc55445dd3&full=1
2020-05-15T12:24:35.390000: DEBUG : Found commit message:
Bug 1632259 - Refactor WebRender configuration logic in gfxPlatform to be testable. r=jrmuizel

We have encountered issues when rolling out WebRender because the
configuration logic is quite complicated. It would serve us well to have
it in a form that we can easily test. This patch does said refactor, as
well as adds an initial set of tests.

Differential Revision: https://phabricator.services.mozilla.com/D72027

2020-05-15T12:24:35.390000: DEBUG : Did not find a branch, checking all integration branches
2020-05-15T12:24:35.392000: INFO : The bisection is done.
2020-05-15T12:24:35.392000: INFO : Stopped

Comment 1

[Sam Johnson]

Attachment: about:support

Here is my about:support output. It claims the compositor support is enabled, even though this behavior is not observed.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 3

[Darkspirit]

Thanks for the report!

Comment 4

[Andrew Osmond [:aosmond] (he/him)]

Hm, yes, it probably should not be predicated on DirectComposition support on non-Windows:

https://searchfox.org/mozilla-central/rev/3ce874dc2703831af3e5ef3a1d216ffd08057fa5/gfx/config/gfxConfigManager.cpp#323

Comment 5

[Andrew Osmond [:aosmond] (he/him)]

Attachment: Bug 1638413 - Allow WebRender compositor to be used without DirectComposition on non-Windows.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8cf3b9e2c3c4
Allow WebRender compositor to be used without DirectComposition on non-Windows. r=jrmuizel

Comment 7

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/8cf3b9e2c3c4