1423104 - regression: Children of transformed parent elements with overflow:hidden are not displayed correctly with WebRender enabled

Status: VERIFIED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Emmy]

Attachment: example.html

Steps to reproduce:
- Have "gfx.webrender.enabled" set to "true"
- Have a parent element with overflow:hidden and any CSS transform (I've tested with rotate() and skew())
- Have a child element larger than its parent, transformed as well.

Expected result:
- The child element will be clipped at the boundaries of its parent.

Actual result:
- The child element is displayed outside the bounds of its parent.

 - - -

See attachment for a working example.
The attachment without WebRender: https://i.imgur.com/IGo99Ce.png
And with WebRender: https://i.imgur.com/CoamO4G.png

Comment 1

[Darkspirit]

Thank you! Confirmed in Nightly 59 x64 20171205123322 de_DE @ Debian Testing (KDE, Radeon RX480)
fresh profile: layers.acceleration.force-enabled, gfx.webrender.enabled, gfx.webrender.blob-images, image.mem.shared

https://bug1423104.bmoattachments.org/attachment.cgi?id=8934421

mozregression --good 2017-11-01 --bad 2017-12-04 --pref "layers.acceleration.force-enabled:true" "gfx.webrender.enabled:true" "gfx.webrender.blob-images:true" "image.mem.shared:true"
> 11:43.09 INFO: Last good revision: ee838fa888aca9f77a8503b5411372d8b56e3341
> 11:43.09 INFO: First bad revision: 50b9ed9a12af2b0e1a3289a65a7ebcfd72976a31
> 11:43.09 INFO: Pushlog:
> https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=ee838fa888aca9f77a8503b5411372d8b56e3341&tochange=50b9ed9a12af2b0e1a3289a65a7ebcfd72976a31

> 50b9ed9a12af	Kartikaya Gupta — Bug 1420163 - Update for API change in WR PR 2105. r=jrmuizel
> fff0793b7854	Kartikaya Gupta — Bug 1420163 - Update webrender to commit e30886d78c91bdd433fd978a39c511ef9416608e. r=jrmuizel

Comment 2

[Darkspirit]

Attachment: Screenshot_20171205_222314.png

Comment 3

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

I bisected this using the try pushes on bug 1420163, and got this WR range:

*   f21cc30e Auto merge of #2104 - mrobinson:optimize-clipping-1, r=glennw
|\
| * 71ffd505 Better ClipChain optimization
*   2ca69913 Auto merge of #2102 - glennw:bs-xf-3, r=kvark
|\
| * 86348b29 Add support for brushes with transforms plus edge AA.
* 95f253fc Auto merge of #2107 - nical:compact-prof-ui, r=glennw
* 0c35ab6d Move profiler ui elements so that they are less likely to end up off screen.

So it's almost certainly from servo/webrender#2104. Filed https://github.com/servo/webrender/issues/2167 for it.

Comment 4

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

Fix is in https://github.com/servo/webrender/pull/2189, we should get it with the next WR update.

Comment 5

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

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #4)
> Fix is in https://github.com/servo/webrender/pull/2189, we should get it
> with the next WR update.

Sadly this PR also caused a talos-g1 failure so we're doing the update to just before that PR landed. Hopefully this will be resolved in time for the next update.

Comment 6

[Darkspirit]

Verified fixed in Nightly 59 x64 20171210220040 de_DE @ Debian Testing (KDE, Radeon RX480).

https://bug1423104.bmoattachments.org/attachment.cgi?id=8934421

mozregression --find-fix --bad 2017-12-09 --good 2017-12-10 --pref "layers.acceleration.force-enabled:true" "gfx.webrender.enabled:true" "gfx.webrender.blob-images:true" "image.mem.shared:true"
> 3:05.50 INFO: First good revision: 8df51ada197d54315b90575afdbe9a351b92f374
> 3:05.50 INFO: Last bad revision: 7c6b568981b8db4b9cb8a04f3f0d3dc2fcc575bc
> 3:05.50 INFO: Pushlog:
> https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=7c6b568981b8db4b9cb8a04f3f0d3dc2fcc575bc&tochange=8df51ada197d54315b90575afdbe9a351b92f374

Fixed by:
> c9af377b8594	Kartikaya Gupta — Bug 1424280 - Update webrender to commit f9bc4a5c263e707e3498bea47d3ec9096cc3d099. r=jrmuizel

According to https://github.com/servo/webrender/pull/2189#issuecomment-350367105
the fix might have been https://github.com/servo/webrender/pull/2205