1499789 - [android] flickering black stuff on top of glyphs on some devices

Status: RESOLVED WORKSFORME

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

Description

[Kartikaya Gupta (email:[e-mail])]

On GeckoView with WR enabled (via extra patches) there is some flickering stuff that appears on top of text as you scroll. I see this on my Xperia XZ1 although I wasn't seeing it on my Z3C. This happens independently of the black glyphs which I filed bug 1499785 for.

Here are bunch of builds based on android nightly m-c revisions:
https://treeherder.mozilla.org/#/jobs?repo=try&author=kgupta%40mozilla.com&group_state=expanded&fromchange=d5d68cf6e33f568ee806bd1a868188d8587ced57&tochange=53892fbb31ba1fff82fb70a62b0725dd6ee30ca8

The flickering started between Oct 4 and Oct 5, which gives me this regression range:

https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=f87eeba88f1c&tochange=863c5a0642a8

Comment 1

[Kartikaya Gupta (email:[e-mail])]

The STR are just to load the GVE app, wait for it to load the default mozilla.org start page, and scroll down.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Confirmed that this doesn't happen on the Z3C, so it's likely hardware/driver specific.

Comment 3

[Kartikaya Gupta (email:[e-mail])]

Attachment: Video of flickering

This is what it looks like, for the record

Comment 4

[Kartikaya Gupta (email:[e-mail])]

I bisected this and it seems to be a result of servo/webrender#3150

Comment 5

[Kartikaya Gupta (email:[e-mail])]

I bisected further and it specifically came from commit b0d71365a57da6efaefddc5edd5e549864e03a8d.

https://github.com/servo/webrender/commit/b0d71365a57da6efaefddc5edd5e549864e03a8d

Comment 6

[Kartikaya Gupta (email:[e-mail])]

I don't see this any more in recent GVE.