Preliminary paint property walk implementation for SPv2

third_party/WebKit/Source/core/layout/LayoutObject.cpp

Index: third_party/WebKit/Source/core/layout/LayoutObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.cpp b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
index c315cbe789a331920d0e7dc6c21f7b659a6bfabd..b72ab3947176b6b766007e36e07b89730a5dfbfc 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -74,6 +74,7 @@
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/Page.h"
+#include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/ObjectPainter.h"
 #include "core/paint/PaintInfo.h"
 #include "core/paint/PaintLayer.h"
@@ -148,6 +149,9 @@ bool LayoutObject::s_affectsParentBlock = false;
 typedef HashMap<const LayoutObject*, LayoutRect> SelectionPaintInvalidationMap;
 static SelectionPaintInvalidationMap* selectionPaintInvalidationMap = nullptr;
 
+typedef HashMap<const LayoutObject*, OwnPtr<ObjectPaintProperties>> ObjectPaintPropertiesMap;
+static ObjectPaintPropertiesMap* objectPaintPropertiesMap = nullptr;
+

[pdr., 2015/10/20 22:02:30]

To avoid having to create this map in ensureObjectPaintProperties, lets add a
static here:

// The storage for paint properties is temporarily implemented as a static
// map to avoid a memory regression if this were on LayoutObject. This is
// only used in slimming paint v2.
typedef HashMap<const LayoutObject*, OwnPtr<ObjectPaintProperties>>
ObjectPaintPropertiesMap;
static ObjectPaintPropertiesMap& objectPaintPropertiesMap()
{
    DEFINE_STATIC_LOCAL(ObjectPaintPropertiesMap,
staticObjectPaintPropertiesMap, ());
    return staticObjectPaintPropertiesMap;
}

[trchen, 2015/10/21 06:16:19]

Done.

 void* LayoutObject::operator new(size_t sz)
 {
     ASSERT(isMainThread());
@@ -2513,6 +2517,11 @@ void LayoutObject::willBeDestroyed()
     if (selectionPaintInvalidationMap)
         selectionPaintInvalidationMap->remove(this);
 
+    if (objectPaintPropertiesMap) {

[pdr., 2015/10/20 22:02:30]

We should check for the property here instead of the map:

if (objectPaintProperties()) {
    ...
}

May need to update objectPaintProperties like so:
ObjectPaintProperties* LayoutObject::objectPaintProperties() const
{
    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
        return objectPaintPropertiesMap().get(this);
    return nullptr;
}

[jbroman, 2015/10/20 23:50:13]

We could just do it unconditionally (well, perhaps with a REF check just to
avoid the assert). No need to search the hashmap twice (once to see if it's
there, and again to remove it). It should be safe to remove a non-existent
element.

[trchen, 2015/10/21 06:16:19]

Done as jbroman's proposal.

The check was to make sure there is no ObjectPaintProperties ever created in
non-SPv2 mode, but I agree the check was extraneous.

+        ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+        clearObjectPaintProperties();
+    }
+
     clearLayoutRootIfNeeded();
 
     if (m_style) {
@@ -3458,6 +3467,38 @@ void LayoutObject::setIsSlowRepaintObject(bool isSlowRepaintObject)
         frameView()->removeSlowRepaintObject();
 }
 
+ObjectPaintProperties* LayoutObject::objectPaintProperties() const
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+
+    if (!objectPaintPropertiesMap)
+        return nullptr;
+
+    return objectPaintPropertiesMap->get(this);
+}
+
+ObjectPaintProperties& LayoutObject::ensureObjectPaintProperties()
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+
+    if (ObjectPaintProperties* properties = objectPaintProperties())
+        return *properties;
+
+    if (!objectPaintPropertiesMap)
+        objectPaintPropertiesMap = new ObjectPaintPropertiesMap;
+
+    return *objectPaintPropertiesMap->set(this, ObjectPaintProperties::create()).storedValue->value.get();
+}
+
+void LayoutObject::clearObjectPaintProperties()
+{
+    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+
+    if (!objectPaintPropertiesMap)
+        return;
+    objectPaintPropertiesMap->remove(this);
+}
+
 } // namespace blink
 
 #ifndef NDEBUG