1315854 - [debug build] Assertion failure: localTransform.IsIdentity(), at gfx/layers/composite/AsyncCompositionManager.cpp:491

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect, P3)

Description

[Shih-Chiang Chien [:schien] (UTC+8) (use ni? plz)]

[STR]
simply open https://w3c-test.org/tools/runner/index.html on debug build of Fennec

[EXPECTED RESULT]
web page is loaded and rendered correctly

[ACTUAL RESULT]
Fennec crashed and Assertion failure: localTransform.IsIdentity() showed in logcat

Comment 1

[Botond Ballo [:botond]]

This is the same assertion failure as in bug 1313610 - could be the same underlying issue.

Perhaps this one I can reproduce.

Comment 2

[Botond Ballo [:botond]]

(In reply to Botond Ballo [:botond] from comment #1)
> Perhaps this one I can reproduce.

Yup!

Comment 3

[Botond Ballo [:botond]]

Attachment: Layer tree that triggers the assertion failure

Here's the layer tree that triggers the assertion failure. The layer 0x60899400 is both fixed and has a transform.

Comment 4

[Botond Ballo [:botond]]

(In reply to Botond Ballo [:botond] from comment #3)
> Here's the layer tree that triggers the assertion failure. The layer
> 0x60899400 is both fixed and has a transform.

Actually, it just has a base-transform and a pre-scale that cancel each other out. Due to rounding error, the product of the two isn't exactly the identity, so the assertion is tripped.

Comment 5

[Botond Ballo [:botond]]

Attachment: Bug 1315854 - Account for rounding error when checking if certain transforms are the identity in AsyncCompositionManager::AlignFixedAndStickyLayers().

Review commit: https://reviewboard.mozilla.org/r/93536/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/93536/

Comment 6

[Markus Stange [:mstange]]

Comment on attachment 8811459 [details]
Bug 1315854 - Account for rounding error when checking if certain transforms are the identity in AsyncCompositionManager::AlignFixedAndStickyLayers().

https://reviewboard.mozilla.org/r/93536/#review93614

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ef895cb3fb7d
Account for rounding error when checking if certain transforms are the identity in AsyncCompositionManager::AlignFixedAndStickyLayers(). r=mstange

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/ef895cb3fb7d

Comment 10

[Botond Ballo [:botond]]

Comment on attachment 8811459 [details]
Bug 1315854 - Account for rounding error when checking if certain transforms are the identity in AsyncCompositionManager::AlignFixedAndStickyLayers().

Let's get this uplifted to 52, since the regressing bug 1288210 landed on 52.

Approval Request Comment
[Feature/regressing bug #]:
  Bug 1288210

[User impact if declined]:
  In debug builds, an assertion may incorrectly be tripped
  on pages involving fixed-position content, crashing the
  browser. This is particularly likely to happen on Fennec
  during zooming.

[Describe test coverage new/current, TreeHerder]:
  Manual.

[Risks and why]: 
  Very low. The fix only affects debug builds, and reduces
  the scope of the assertion.

[String/UUID change made/needed]:
  None.

Comment 11

[Julien Cristau [:jcristau]]

Comment on attachment 8811459 [details]
Bug 1315854 - Account for rounding error when checking if certain transforms are the identity in AsyncCompositionManager::AlignFixedAndStickyLayers().

fix recent regression for debug builds in aurora52

Comment 12

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/0057723898d4