Subtree caching implementation in blink-core

Source/core/layout/LayoutObject.cpp

Index: Source/core/layout/LayoutObject.cpp
diff --git a/Source/core/layout/LayoutObject.cpp b/Source/core/layout/LayoutObject.cpp
index 0892709745635288d2a7b1efe0030c0615333d8e..8b278ff0d07ea5e3b0942f2289aa478ffa85b9b7 100644
--- a/Source/core/layout/LayoutObject.cpp
+++ b/Source/core/layout/LayoutObject.cpp
@@ -1164,7 +1164,21 @@ void LayoutObject::invalidatePaintUsingContainer(const LayoutBoxModelObject& pai
     }
 }
 
-void LayoutObject::invalidateDisplayItemClient(const DisplayItemClientWrapper& displayItemClient) const
+void LayoutObject::invalidateDisplayItemClient(const NonLayoutObjectDisplayItemClientWrapper& displayItemClient)
+{
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+        setChildNeedsRepaint();
+    invalidateDisplayItemClientInternal(displayItemClient);
+}
+
+void LayoutObject::invalidateDisplayItemClient(LayoutObject& object)
+{
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+        object.setNeedsRepaint();
+    invalidateDisplayItemClientInternal(object);
+}
+
+void LayoutObject::invalidateDisplayItemClientInternal(const DisplayItemClientWrapper& displayItemClient)
 {
     if (!RuntimeEnabledFeatures::slimmingPaintEnabled())
         return;
@@ -1178,12 +1192,65 @@ void LayoutObject::invalidateDisplayItemClient(const DisplayItemClientWrapper& d
     }
 }
 
-void LayoutObject::invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer) const
+void LayoutObject::invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer)
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+        setNeedsRepaint();
     paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*this);
 }
 
+void LayoutObject::setNeedsRepaint()
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());

[pdr., 2015/08/20 22:45:05]

Can we assert that we're in the appropriate document lifecycle phase here and
below?

[Xianzhu, 2015/08/21 00:31:38]

Done. The condition will change in next steps for combining paint invalidation
into painting and combining paint invalidation flags with repaint flags.

+    if (!selfNeedsRepaint()) {
+        m_bitfields.setSelfNeedsRepaint(true);
+        markContainerChainForRepaint();
+    }
+}
+
+void LayoutObject::setChildNeedsRepaint()
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    if (!childNeedsRepaint()) {
+        m_bitfields.setChildNeedsRepaint(true);
+        markContainerChainForRepaint();
+    }
+}
+
+void LayoutObject::markContainerChainForRepaint()

[pdr., 2015/08/20 22:45:05]

markContainerChainForChildNeedsRepaint?

[Xianzhu, 2015/08/21 00:31:38]

Done.

+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    for (LayoutObject* container = this->containerCrossingFrameBoundaries(); container && !container->childNeedsRepaint(); container = container->containerCrossingFrameBoundaries())
+        container->m_bitfields.setChildNeedsRepaint(true);

[trchen, 2015/08/21 00:37:29]

I think we need to special case fixed-pos elements.

If I understand correctly, we want to mark all ancestors in the painting order,
but instead this marks all ancestors in the positioning order. For most element
isPaintingAncestor(o) implies isPositionAncestor(o). Fixed-pos is the only
exception.

[Xianzhu, 2015/08/21 04:54:51]

container() is actually equivalent to paintingAncestor(). It has a special case
for fixed position. If not, the original paint invalidation would have been
incorrect.

However, I need to confirm the paint invalidation traversal sequence (which is
also the clearRepaintFlagsRecursively traversal sequence) about fixed-pos.

[Xianzhu, 2015/08/21 05:52:45]

Scratch the above. Perhaps I misunderstood painting order about fixed-pos. Will
investigate more.

+}
+
+bool LayoutObject::clearRepaintFlagsRecursively()
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    m_bitfields.setSelfNeedsRepaint(false);
+
+    if (!m_bitfields.childNeedsRepaint())
+        return true;
+
+    if (clearRepaintFlagsOfSubtrees()) {
+        m_bitfields.setChildNeedsRepaint(false);
+        return true;
+    }
+    return false;
+}
+
+bool LayoutObject::clearRepaintFlagsOfSubtrees()
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    bool result = true;
+    for (LayoutObject* child = slowFirstChild(); child; child = child->nextSibling()) {
+        if (!child->isOutOfFlowPositioned())
+            result &= child->clearRepaintFlagsRecursively();
+    }
+    return result;
+}
+
 LayoutRect LayoutObject::boundsRectForPaintInvalidation(const LayoutBoxModelObject* paintInvalidationContainer, const PaintInvalidationState* paintInvalidationState) const
 {
     if (!paintInvalidationContainer)
@@ -1191,7 +1258,7 @@ LayoutRect LayoutObject::boundsRectForPaintInvalidation(const LayoutBoxModelObje
     return DeprecatedPaintLayer::computePaintInvalidationRect(this, paintInvalidationContainer->layer(), paintInvalidationState);
 }
 
-const LayoutBoxModelObject* LayoutObject::invalidatePaintRectangleInternal(const LayoutRect& r) const
+const LayoutBoxModelObject* LayoutObject::invalidatePaintRectangleInternal(const LayoutRect& r)
 {
     RELEASE_ASSERT(isRooted());
 
@@ -1209,7 +1276,7 @@ const LayoutBoxModelObject* LayoutObject::invalidatePaintRectangleInternal(const
     return &paintInvalidationContainer;
 }
 
-void LayoutObject::invalidatePaintRectangle(const LayoutRect& r) const
+void LayoutObject::invalidatePaintRectangle(const LayoutRect& r)
 {
     if (const LayoutBoxModelObject* paintInvalidationContainer = invalidatePaintRectangleInternal(r)) {
         if (RuntimeEnabledFeatures::slimmingPaintEnabled())
@@ -3286,7 +3353,7 @@ void traverseNonCompositingDescendants(LayoutObject& object, const LayoutObjectT
 
 } // unnamed namespace
 
-void LayoutObject::invalidateDisplayItemClientForNonCompositingDescendantsOf(const LayoutObject& object) const
+void LayoutObject::invalidateDisplayItemClientForNonCompositingDescendantsOf(LayoutObject& object)
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());