moebius#138: Optimize operations on root of deeply-nested frame tree

https://github.com/MoonchildProductions/moebius/pull/138

1 files changed, 7 insertions, 21 deletions

diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index eab11b80c..553239e0e 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -1629,28 +1629,11 @@ nsStylePosition::CalcDifference(const nsStylePosition& aNewData,
   if (aOldStyleVisibility) {
     bool isVertical = WritingMode(aOldStyleVisibility).IsVertical();
     if (isVertical ? widthChanged : heightChanged) {
-      // Block-size changes can affect descendant intrinsic sizes due to
-      // replaced elements with percentage bsizes in descendants which
-      // also have percentage bsizes. This is handled via
-      // nsChangeHint_UpdateComputedBSize which clears intrinsic sizes
-      // for frames that have such replaced elements.
-      //
-      // We need to use nsChangeHint_ClearAncestorIntrinsics for
-      // block-size changes so we clear results of cached CSS Flex
-      // measuring reflows.
-      hint |= nsChangeHint_NeedReflow |
-              nsChangeHint_UpdateComputedBSize |
-              nsChangeHint_ReflowChangesSizeOrPosition |
-              nsChangeHint_ClearAncestorIntrinsics;
+      hint |= nsChangeHint_ReflowHintsForBSizeChange;
     }
 
     if (isVertical ? heightChanged : widthChanged) {
-      // None of our inline-size differences can affect descendant
-      // intrinsic sizes and none of them need to force children to
-      // reflow.
-      hint |= nsChangeHint_AllReflowHints &
-              ~(nsChangeHint_ClearDescendantIntrinsics |
-                nsChangeHint_NeedDirtyReflow);
+      hint |= nsChangeHint_ReflowHintsForISizeChange;
     }
   } else {
     if (widthChanged || heightChanged) {
@@ -3263,8 +3246,6 @@ nsStyleDisplay::CalcDifference(const nsStyleDisplay& aNewData) const
       || mDisplay != aNewData.mDisplay
       || mContain != aNewData.mContain
       || (mFloat == StyleFloat::None) != (aNewData.mFloat == StyleFloat::None)
-      || mOverflowX != aNewData.mOverflowX
-      || mOverflowY != aNewData.mOverflowY
       || mScrollBehavior != aNewData.mScrollBehavior
       || mScrollSnapTypeX != aNewData.mScrollSnapTypeX
       || mScrollSnapTypeY != aNewData.mScrollSnapTypeY
@@ -3276,6 +3257,11 @@ nsStyleDisplay::CalcDifference(const nsStyleDisplay& aNewData) const
     hint |= nsChangeHint_ReconstructFrame;
   }
 
+  if (mOverflowX != aNewData.mOverflowX
+      || mOverflowY != aNewData.mOverflowY) {
+    hint |= nsChangeHint_CSSOverflowChange;
+  }
+
   /* Note: When mScrollBehavior, mScrollSnapTypeX, mScrollSnapTypeY,
    * mScrollSnapPointsX, mScrollSnapPointsY, or mScrollSnapDestination are
    * changed, nsChangeHint_NeutralChange is not sufficient to enter