Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Description • 10 years ago

I landed bug 928833 [1] but it was backed out for test failures. All of the mochitests that failed had this assertion:

 F/MOZ_Assert( 777): Assertion failure: buildingForChild.GetPrevAnimatedGeometryRoot() == aBuilder->FindAnimatedGeometryRootFor(child->GetParent()), at ../../../gecko/layout/generic/nsFrame.cpp:2425

[1] https://treeherder.mozilla.org/ui/#/jobs?repo=b2g-inbound&revision=a686c6909b22

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 1 • 10 years ago

I'm able to reproduce on the device just by opening the settings app as well. In that case the buildingForChild.GetPrevAnimatedGeometryRoot() is the same as child->GetParent(), and the aBuilder->FindAnimatedGeometryRootFor(child->GetParent()) returns something that's not inside the frame tree of the presshell (at least it doesn't show up in PresContext()->PresShell()->GetRootFrame()->DumpFrameTree();

Log attached.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 2 • 10 years ago

So the problem here is actually that sometimes the nsDisplayListBuilder is created with a reference frame that is not an animated geometry root. When an AutoBuildingDisplayList is created on top of that, the GetPrevAnimatedGeometryRoot() is not what would normally be returned by aBuilder->FindAnimatedGeometryRootFor(child->GetParent()).

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 3 • 10 years ago

This fixes it for me locally. Try push: https://treeherder.mozilla.org/ui/#/jobs?repo=try&revision=4c8f8c944d44

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 4 • 10 years ago

The try push fixes the B2G debug mochitest assertions. There's still reftest failures (and tons of failures on non-B2G) platforms. There's definitely some bugs with this event-regions stuff that we'll need to get to the bottom of.

	Timothy Nikkel (:tnikkel)
	Comment 5 • 10 years ago

I'm curious why we are building event regions in a case where the root reference frame for the builder is not the root document root frame. All cases where we do that I don't think we need event regions.

But we should also set the initial animated geometry root correctly, it should be the animated geometry root of the reference frame, not the reference frame.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 6 • 10 years ago

(In reply to Timothy Nikkel (:tn) from comment #5)
> I'm curious why we are building event regions in a case where the root
> reference frame for the builder is not the root document root frame. All
> cases where we do that I don't think we need event regions.

I'm not sure. This sounds like an optimization we can do, but it would mask legitimate errors such as the one below so perhaps we should wait on this.

> 
> But we should also set the initial animated geometry root correctly, it
> should be the animated geometry root of the reference frame, not the
> reference frame.

Fixing this also fixes the assertion. Patch coming.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 8 • 10 years ago

Looks like many of the oranges in the above try run are due to assertion errors because of a copy/paste error.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 9 • 10 years ago

remote:   https://hg.mozilla.org/integration/mozilla-inbound/rev/a808168ae839
remote:   https://hg.mozilla.org/integration/mozilla-inbound/rev/ce7b5ae7376d

	Timothy Nikkel (:tnikkel)
	Comment 10 • 10 years ago

(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #6)
> (In reply to Timothy Nikkel (:tn) from comment #5)
> > I'm curious why we are building event regions in a case where the root
> > reference frame for the builder is not the root document root frame. All
> > cases where we do that I don't think we need event regions.
> 
> I'm not sure. This sounds like an optimization we can do, but it would mask
> legitimate errors such as the one below so perhaps we should wait on this.

Okay, let's just not forget to do it though.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 11 • 10 years ago

Filed bug 1107143 for it.

	Carsten Book [:Tomcat]
	Comment 12 • 10 years ago

https://hg.mozilla.org/mozilla-central/rev/a808168ae839
https://hg.mozilla.org/mozilla-central/rev/ce7b5ae7376d