Bug 1421825 - Fix crash and re-enable crashtest. r?jrmuizel
In some cases we get a gecko display list that looks like this:
WrapList with asr(<A>, <B>)
Item with asr (<B>) and clipchain(<something> [A])
In this case, we would initialize the WebRenderLayerScrollData for the
nested item using a stop-at ancestor of A (because that was the leafmost
ASR from the containing WrapList) but the item itself has an ASR of B,
which is an ancestor of A. So when walking up from B we'd never hit the
stop-at ancestor, and so we'd end up duplicating metrics from the
containing WRLSD onto the nested WRLSD. This generated an assertion
failure in the APZ code.
This patch detects this scenario and skips adding metrics on the nested
WRLSD. This produces an APZ tree equivalent to what the non-WebRender
path would produce.
MozReview-Commit-ID: 8eo6pzXXKBd
--- a/gfx/layers/wr/WebRenderScrollData.cpp
+++ b/gfx/layers/wr/WebRenderScrollData.cpp
@@ -45,31 +45,39 @@ WebRenderLayerScrollData::Initialize(Web
const Maybe<gfx::Matrix4x4>& aAncestorTransform)
{
MOZ_ASSERT(aDescendantCount >= 0); // Ensure value is valid
MOZ_ASSERT(mDescendantCount == -1); // Don't allow re-setting an already set value
mDescendantCount = aDescendantCount;
MOZ_ASSERT(aItem);
aItem->UpdateScrollData(&aOwner, this);
- for (const ActiveScrolledRoot* asr = aItem->GetActiveScrolledRoot();
- asr && asr != aStopAtAsr;
- asr = asr->mParent) {
+
+ const ActiveScrolledRoot* asr = aItem->GetActiveScrolledRoot();
+ if (ActiveScrolledRoot::IsAncestor(asr, aStopAtAsr)) {
+ // If the item's ASR is an ancestor of the stop-at ASR, then we don't need
+ // any more metrics information because we'll end up duplicating what the
+ // ancestor WebRenderLayerScrollData already has.
+ asr = nullptr;
+ }
+
+ while (asr && asr != aStopAtAsr) {
MOZ_ASSERT(aOwner.GetManager());
FrameMetrics::ViewID scrollId = asr->GetViewId();
if (Maybe<size_t> index = aOwner.HasMetadataFor(scrollId)) {
mScrollIds.AppendElement(index.ref());
} else {
Maybe<ScrollMetadata> metadata = asr->mScrollableFrame->ComputeScrollMetadata(
aOwner.GetManager(), aItem->ReferenceFrame(),
ContainerLayerParameters(), nullptr);
MOZ_ASSERT(metadata);
MOZ_ASSERT(metadata->GetMetrics().GetScrollId() == scrollId);
mScrollIds.AppendElement(aOwner.AddMetadata(metadata.ref()));
}
+ asr = asr->mParent;
}
// aAncestorTransform, if present, is the transform from an ancestor
// nsDisplayTransform that was stored on the stacking context in order to
// propagate it downwards in the tree. (i.e. |aItem| is a strict descendant of
// the nsDisplayTranform which produced aAncestorTransform). We store this
// separately from mTransform because in the case where we have multiple
// scroll metadata on this layer item, the mAncestorTransform is associated
--- a/layout/painting/crashtests/crashtests.list
+++ b/layout/painting/crashtests/crashtests.list
@@ -3,14 +3,14 @@ skip-if(Android) load 1407470-1.html
load 1413073-1.html
load 1413073-2.html
load 1405881-1.html
load 1418177-1.html
load 1418722-1.html
load 1419917.html
load 1425271-1.html
load 1428906-1.html
-skip-if(webrender) load 1430589-1.html # bug 1421825 for webrender
+load 1430589-1.html
load 1454105-1.html
load 1455944-1.html
load 1465305-1.html
load 1468124-1.html
load 1469472.html
