Bug 1526972 - P8: Reset InInvalidSubtree when processing unrelated frames. r=mattwoodrow

Differential Revision: https://phabricator.services.mozilla.com/D26141

--HG--
extra : moz-landing-system : lando

layout/generic/nsGfxScrollFrame.cpp

@@ -3746,6 +3746,9 @@ void ScrollFrameHelper::MaybeAddTopLayerItems(nsDisplayListBuilder* aBuilder,
       nsDisplayList topLayerList;
       viewportFrame->BuildDisplayListForTopLayer(aBuilder, &topLayerList);
       if (!topLayerList.IsEmpty()) {
+        nsDisplayListBuilder::AutoBuildingDisplayList buildingDisplayList(
+            aBuilder, viewportFrame);
+
         // Wrap the whole top layer in a single item with maximum z-index,
         // and append it at the very end, so that it stays at the topmost.
         nsDisplayWrapList* wrapList = MakeDisplayItem<nsDisplayWrapList>(

layout/painting/RetainedDisplayListBuilder.cpp

@@ -214,8 +214,8 @@ void RetainedDisplayListBuilder::IncrementSubDocPresShellPaintCount(
 }
 
 bool AnyContentAncestorModified(nsIFrame* aFrame, nsIFrame* aStopAtFrame) {
-  for (nsIFrame* f = aFrame; f;
-       f = nsLayoutUtils::GetParentOrPlaceholderForCrossDoc(f)) {
+  nsIFrame* f = aFrame;
+  while (f) {
     if (f->IsFrameModified()) {
       return true;
     }
@@ -223,6 +223,12 @@ bool AnyContentAncestorModified(nsIFrame* aFrame, nsIFrame* aStopAtFrame) {
     if (aStopAtFrame && f == aStopAtFrame) {
       break;
     }
+
+    if (f->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT) {
+      f = f->GetParent();
+    } else {
+      f = nsLayoutUtils::GetParentOrPlaceholderForCrossDoc(f);
+    }
   }
 
   return false;

layout/painting/nsDisplayList.cpp

@@ -10290,6 +10290,25 @@ PaintTelemetry::AutoRecord::~AutoRecord() {
 
 }  // namespace mozilla
 
+static nsIFrame* GetSelfOrPlaceholderFor(nsIFrame* aFrame) {
+  if (aFrame->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT) {
+    return aFrame;
+  }
+
+  if ((aFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) &&
+      !aFrame->GetPrevInFlow()) {
+    return aFrame->GetPlaceholderFrame();
+  }
+
+  return aFrame;
+}
+
+static nsIFrame* GetAncestorFor(nsIFrame* aFrame) {
+  nsIFrame* f = GetSelfOrPlaceholderFor(aFrame);
+  MOZ_ASSERT(f);
+  return nsLayoutUtils::GetCrossDocParentFrame(f);
+}
+
 nsDisplayListBuilder::AutoBuildingDisplayList::AutoBuildingDisplayList(
     nsDisplayListBuilder* aBuilder, nsIFrame* aForChild,
     const nsRect& aVisibleRect, const nsRect& aDirtyRect,
@@ -10331,8 +10350,16 @@ nsDisplayListBuilder::AutoBuildingDisplayList::AutoBuildingDisplayList(
 
   MOZ_ASSERT(nsLayoutUtils::IsAncestorFrameCrossDoc(
       aBuilder->RootReferenceFrame(), *aBuilder->mCurrentAGR));
-  aBuilder->mInInvalidSubtree =
-      aBuilder->mInInvalidSubtree || aForChild->IsFrameModified();
+
+  // If aForChild is being visited from a frame other than it's ancestor frame,
+  // mInInvalidSubtree will need to be recalculated the slow way.
+  if (aForChild == mPrevFrame || GetAncestorFor(aForChild) == mPrevFrame) {
+    aBuilder->mInInvalidSubtree =
+        aBuilder->mInInvalidSubtree || aForChild->IsFrameModified();
+  } else {
+    aBuilder->mInInvalidSubtree = AnyContentAncestorModified(aForChild);
+  }
+
   aBuilder->mCurrentFrame = aForChild;
   aBuilder->mVisibleRect = aVisibleRect;
   aBuilder->mDirtyRect =

layout/painting/nsDisplayList.h

@@ -1132,6 +1132,11 @@ class nsDisplayListBuilder {
    */
   class AutoBuildingDisplayList {
    public:
+    AutoBuildingDisplayList(nsDisplayListBuilder* aBuilder, nsIFrame* aForChild)
+        : AutoBuildingDisplayList(
+              aBuilder, aForChild, aBuilder->GetVisibleRect(),
+              aBuilder->GetDirtyRect(), aForChild->IsTransformed()) {}
+
     AutoBuildingDisplayList(nsDisplayListBuilder* aBuilder, nsIFrame* aForChild,
                             const nsRect& aVisibleRect,
                             const nsRect& aDirtyRect)