Subtree caching implementation in blink-core

Source/core/layout/LayoutObject.h

Index: Source/core/layout/LayoutObject.h
diff --git a/Source/core/layout/LayoutObject.h b/Source/core/layout/LayoutObject.h
index 06e8d0270fba1af8f836169364b4e2f30ebf0d3b..43b9cb0b6ce68abaebc19d0a050859c774b364af 100644
--- a/Source/core/layout/LayoutObject.h
+++ b/Source/core/layout/LayoutObject.h
@@ -115,6 +115,15 @@ typedef WTF::HashMap<const DeprecatedPaintLayer*, Vector<LayoutRect>> LayerHitTe
 const int showTreeCharacterOffset = 39;
 #endif
 
+class NonLayoutObjectDisplayItemClientWrapper : public DisplayItemClientWrapper {
+public:
+    template <typename T>
+    NonLayoutObjectDisplayItemClientWrapper(const T& client)
+        : DisplayItemClientWrapper(client) { }
+
+    NonLayoutObjectDisplayItemClientWrapper(const LayoutObject&) = delete;
+};
+
 // Base class for all layout tree objects.
 class CORE_EXPORT LayoutObject : public ImageResourceClient {
     friend class LayoutBlock;
@@ -856,8 +865,8 @@ public:
     void invalidatePaintUsingContainer(const LayoutBoxModelObject& paintInvalidationContainer, const LayoutRect&, PaintInvalidationReason) const;
 
     // Invalidate the paint of a specific subrectangle within a given object. The rect |r| is in the object's coordinate space.
-    void invalidatePaintRectangle(const LayoutRect&) const;
-    void invalidatePaintRectangleNotInvalidatingDisplayItemClients(const LayoutRect& r) const { invalidatePaintRectangleInternal(r); }
+    void invalidatePaintRectangle(const LayoutRect&);
+    void invalidatePaintRectangleNotInvalidatingDisplayItemClients(const LayoutRect& r) { invalidatePaintRectangleInternal(r); }
 
     // Walk the tree after layout issuing paint invalidations for layoutObjects that have changed or moved, updating bounds that have changed, and clearing paint invalidation state.
     virtual void invalidateTreeIfNeeded(PaintInvalidationState&);
@@ -1043,15 +1052,25 @@ public:
 
     DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
 
-    void invalidateDisplayItemClient(const DisplayItemClientWrapper&) const;
-    void invalidateDisplayItemClientForNonCompositingDescendants() const { invalidateDisplayItemClientForNonCompositingDescendantsOf(*this); }
+    void invalidateDisplayItemClient(const NonLayoutObjectDisplayItemClientWrapper&);
+    void invalidateDisplayItemClient(LayoutObject&);
+    void invalidateDisplayItemClientForNonCompositingDescendants() { invalidateDisplayItemClientForNonCompositingDescendantsOf(*this); }
     // A normal object should use invalidateDisplayItemClientForNonCompositingDescendants()
     // to invalidate its descendants which are painted on the same backing. However, for
     // an object (e.g. LayoutScrollbarPart, custom scroll corner, custom resizer) which is
     // not hooked up in the layout tree and not able to find its paint backing, it should
     // let its owning layout object call the following function.
     // FIXME: should we hook up scrollbar parts in the layout tree? crbug.com/484263.
-    void invalidateDisplayItemClientForNonCompositingDescendantsOf(const LayoutObject&) const;
+    void invalidateDisplayItemClientForNonCompositingDescendantsOf(LayoutObject&);
+
+    // Slimming paint v2 tracks whether a LayoutObject is invalid instead of using invalidation rects.
+    // For more information, see: https://docs.google.com/a/chromium.org/document/d/1FTqk3MwUAS1qLJsnA9zgfDbeqAQBdLYC4GJ9jpN-xdA
+    bool selfNeedsRepaint() const { return m_bitfields.selfNeedsRepaint(); }
+    void setNeedsRepaint();
+    bool childNeedsRepaint() const { return m_bitfields.childNeedsRepaint(); }
+    bool shouldCheckForRepaint() const { return selfNeedsRepaint() || childNeedsRepaint(); }
+
+    void clearRepaintFlagsRecursively();
 
 protected:
     enum LayoutObjectType {
@@ -1179,7 +1198,9 @@ protected:
     // owned by this object, including the object itself, LayoutText/LayoutInline line boxes, etc.,
     // not including children which will be invalidated normally during invalidateTreeIfNeeded() and
     // parts which are invalidated separately (e.g. scrollbars).
-    virtual void invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer) const;
+    virtual void invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer);
+
+    virtual void clearRepaintFlagsOfSubtrees();
 
     void setIsSlowRepaintObject(bool);
 
@@ -1210,6 +1231,9 @@ private:
 
     inline void markContainerChainForPaintInvalidation();
 
+    void markContainerChainForChildNeedsRepaint();
+    void setChildNeedsRepaint();
+
     inline void invalidateSelectionIfNeeded(const LayoutBoxModelObject&, PaintInvalidationReason);
 
     inline void invalidateContainerPreferredLogicalWidths();
@@ -1240,7 +1264,9 @@ private:
 
     static bool isAllowedToModifyLayoutTreeStructure(Document&);
 
-    const LayoutBoxModelObject* invalidatePaintRectangleInternal(const LayoutRect&) const;
+    const LayoutBoxModelObject* invalidatePaintRectangleInternal(const LayoutRect&);
+
+    void invalidateDisplayItemClientInternal(const DisplayItemClientWrapper&);
 
     RefPtr<ComputedStyle> m_style;
 
@@ -1311,6 +1337,8 @@ private:
             , m_alwaysCreateLineBoxesForLayoutInline(false)
             , m_lastBoxDecorationBackgroundObscured(false)
             , m_isSlowRepaintObject(false)
+            , m_selfNeedsRepaint(false)
+            , m_childNeedsRepaint(false)
             , m_positionedState(IsStaticallyPositioned)
             , m_selectionState(SelectionNone)
             , m_boxDecorationBackgroundState(NoBoxDecorationBackground)
@@ -1318,7 +1346,7 @@ private:
         {
         }
 
-        // 32 bits have been used in the first word, and 16 in the second.
+        // 32 bits have been used in the first word, and 18 in the second.
         ADD_BOOLEAN_BITFIELD(selfNeedsLayout, SelfNeedsLayout);
         ADD_BOOLEAN_BITFIELD(shouldInvalidateOverflowForPaint, ShouldInvalidateOverflowForPaint); // TODO(wangxianzhu): Remove for slimming paint v2.
         ADD_BOOLEAN_BITFIELD(childShouldCheckForPaintInvalidation, ChildShouldCheckForPaintInvalidation);
@@ -1370,6 +1398,12 @@ private:
 
         ADD_BOOLEAN_BITFIELD(isSlowRepaintObject, IsSlowRepaintObject);
 
+        // For slimming-paint v2.
+        // TODO(wangxianzhu): Combine repaint flags with paint invalidation flags when we remove
+        // old paint invalidation code.
+        ADD_BOOLEAN_BITFIELD(selfNeedsRepaint, SelfNeedsRepaint);
+        ADD_BOOLEAN_BITFIELD(childNeedsRepaint, ChildNeedsRepaint);
+
     private:
         unsigned m_positionedState : 2; // PositionedState
         unsigned m_selectionState : 3; // SelectionState