Reduce invalidation on children-needs-layout containers

Source/core/rendering/RenderObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 231 matching lines @@
     }
 
     void assertSubtreeIsLaidOut() const
     {
         for (const RenderObject* renderer = this; renderer; renderer = renderer->nextInPreOrder())
             renderer->assertRendererLaidOut();
     }
 
 #endif
 
+    bool skipInvalidationWhenLaidOutChildren() const;
+
+    // FIXME: This could be used when changing the size of a renderer without children to skip some invalidations.
+    bool rendererHasNoBoxEffect() const
+    {
+        return !style()->hasVisualOverflowingEffect() && !style()->hasBorder() && !style()->hasBackground();
+    }
+
     // Obtains the nearest enclosing block (including this block) that contributes a first-line style to our inline
     // children.
     virtual RenderBlock* firstLineBlock() const;
 
     // Called when an object that was floating or positioned becomes a normal flow object
     // again.  We have to make sure the render tree updates as needed to accommodate the new
     // normal flow object.
     void handleDynamicFloatPositionChange();
 
     // RenderObject tree manipulation
@@ skipping 261 matching lines @@
     bool hasBoxDecorationBackground() const { return m_bitfields.boxDecorationBackgroundState() != NoBoxDecorationBackground; }
     bool boxDecorationBackgroundIsKnownToBeObscured();
     bool canRenderBorderImage() const;
     bool mustInvalidateBackgroundOrBorderPaintOnWidthChange() const;
     bool mustInvalidateBackgroundOrBorderPaintOnHeightChange() const;
     bool mustInvalidateFillLayersPaintOnWidthChange(const FillLayer&) const;
     bool mustInvalidateFillLayersPaintOnHeightChange(const FillLayer&) const;
     bool hasBackground() const { return style()->hasBackground(); }
     bool hasEntirelyFixedBackground() const;
 
+    bool needsLayoutBecauseOfChildren() const { return needsLayout() && !selfNeedsLayout() && !needsPositionedMovementLayout() && !needsSimplifiedNormalFlowLayout(); }
+
     bool needsLayout() const
     {
         return m_bitfields.selfNeedsLayout() || m_bitfields.normalChildNeedsLayout() || m_bitfields.posChildNeedsLayout()
             || m_bitfields.needsSimplifiedNormalFlowLayout() || m_bitfields.needsPositionedMovementLayout();
     }
 
     bool selfNeedsLayout() const { return m_bitfields.selfNeedsLayout(); }
     bool needsPositionedMovementLayout() const { return m_bitfields.needsPositionedMovementLayout(); }
     bool needsPositionedMovementLayoutOnly() const
     {
@@ skipping 461 matching lines @@
     bool mayNeedPaintInvalidation() { return m_bitfields.mayNeedPaintInvalidation(); }
     void setMayNeedPaintInvalidation(bool b)
     {
         m_bitfields.setMayNeedPaintInvalidation(b);
 
         // Make sure our parent is marked as needing invalidation.
         if (b && parent() && !parent()->mayNeedPaintInvalidation())
             parent()->setMayNeedPaintInvalidation(b);
     }
 
+    bool neededLayoutBecauseOfChildren() const { return m_bitfields.neededLayoutBecauseOfChildren(); }
+    void setNeededLayoutBecauseOfChildren(bool b) { m_bitfields.setNeededLayoutBecauseOfChildren(b); }
+
     bool shouldCheckForPaintInvalidationAfterLayout()
     {
         return layoutDidGetCalled() || mayNeedPaintInvalidation();
     }
 
     bool supportsLayoutStateCachedOffsets() const { return !hasColumns() && !hasTransform() && !hasReflection() && !style()->isFlippedBlocksWritingMode(); }
 
     void setNeedsOverflowRecalcAfterStyleChange();
     void markContainingBlocksForOverflowRecalc();
 
@@ skipping 114 matching lines @@
             // the layout bits beforeissing paint invalidations when doing invalidateTreeAfterLayout.
             // Holding the layout bits until after paint invalidation would remove the need
             // for this flag.
             , m_shouldDoFullPaintInvalidationAfterLayout(false)
             , m_shouldInvalidateOverflowForPaint(false)
             , m_shouldDoFullPaintInvalidationIfSelfPaintingLayer(false)
             // FIXME: We should remove mayNeedPaintInvalidation once we are able to
             // use the other layout flags to detect the same cases. crbug.com/370118
             , m_mayNeedPaintInvalidation(false)
             , m_onlyNeededPositionedMovementLayout(false)
+            , m_neededLayoutBecauseOfChildren(false)
             , m_needsPositionedMovementLayout(false)
             , m_normalChildNeedsLayout(false)
             , m_posChildNeedsLayout(false)
             , m_needsSimplifiedNormalFlowLayout(false)
             , m_preferredLogicalWidthsDirty(false)
             , m_floating(false)
             , m_selfNeedsOverflowRecalcAfterStyleChange(false)
             , m_childNeedsOverflowRecalcAfterStyleChange(false)
             , m_isAnonymous(!node)
             , m_isText(false)
@@ skipping 20 matching lines @@
         {
         }
 
         // 32 bits have been used in the first word, and 6 in the second.
         ADD_BOOLEAN_BITFIELD(selfNeedsLayout, SelfNeedsLayout);
         ADD_BOOLEAN_BITFIELD(shouldDoFullPaintInvalidationAfterLayout, ShouldDoFullPaintInvalidationAfterLayout);
         ADD_BOOLEAN_BITFIELD(shouldInvalidateOverflowForPaint, ShouldInvalidateOverflowForPaint);
         ADD_BOOLEAN_BITFIELD(shouldDoFullPaintInvalidationIfSelfPaintingLayer, ShouldDoFullPaintInvalidationIfSelfPaintingLayer);
         ADD_BOOLEAN_BITFIELD(mayNeedPaintInvalidation, MayNeedPaintInvalidation);
         ADD_BOOLEAN_BITFIELD(onlyNeededPositionedMovementLayout, OnlyNeededPositionedMovementLayout);
+        ADD_BOOLEAN_BITFIELD(neededLayoutBecauseOfChildren, NeededLayoutBecauseOfChildren);
         ADD_BOOLEAN_BITFIELD(needsPositionedMovementLayout, NeedsPositionedMovementLayout);
         ADD_BOOLEAN_BITFIELD(normalChildNeedsLayout, NormalChildNeedsLayout);
         ADD_BOOLEAN_BITFIELD(posChildNeedsLayout, PosChildNeedsLayout);
         ADD_BOOLEAN_BITFIELD(needsSimplifiedNormalFlowLayout, NeedsSimplifiedNormalFlowLayout);
         ADD_BOOLEAN_BITFIELD(preferredLogicalWidthsDirty, PreferredLogicalWidthsDirty);
         ADD_BOOLEAN_BITFIELD(floating, Floating);
         ADD_BOOLEAN_BITFIELD(selfNeedsOverflowRecalcAfterStyleChange, SelfNeedsOverflowRecalcAfterStyleChange);
         ADD_BOOLEAN_BITFIELD(childNeedsOverflowRecalcAfterStyleChange, ChildNeedsOverflowRecalcAfterStyleChange);
 
         ADD_BOOLEAN_BITFIELD(isAnonymous, IsAnonymous);
@@ skipping 136 matching lines @@
 }
 
 inline void RenderObject::setNeedsLayoutAndFullPaintInvalidation(MarkingBehavior markParents, SubtreeLayoutScope* layouter)
 {
     setNeedsLayout(markParents, layouter);
     setShouldDoFullPaintInvalidationAfterLayout(true);
 }
 
 inline void RenderObject::clearNeedsLayout()
 {
-    if (needsPositionedMovementLayoutOnly())
-        setOnlyNeededPositionedMovementLayout(true);
+    setOnlyNeededPositionedMovementLayout(needsPositionedMovementLayoutOnly());
+    setNeededLayoutBecauseOfChildren(needsLayoutBecauseOfChildren());
     setLayoutDidGetCalled(true);
     setSelfNeedsLayout(false);
     setEverHadLayout(true);
     setPosChildNeedsLayout(false);
     setNeedsSimplifiedNormalFlowLayout(false);
     setNormalChildNeedsLayout(false);
     setNeedsPositionedMovementLayout(false);
     setAncestorLineBoxDirty(false);
 #ifndef NDEBUG
     checkBlockPositionedObjectsNeedLayout();
@@ skipping 121 matching lines @@
 void showTree(const WebCore::RenderObject*);
 void showLineTree(const WebCore::RenderObject*);
 void showRenderTree(const WebCore::RenderObject* object1);
 // We don't make object2 an optional parameter so that showRenderTree
 // can be called from gdb easily.
 void showRenderTree(const WebCore::RenderObject* object1, const WebCore::RenderObject* object2);
 
 #endif
 
 #endif // RenderObject_h