Skip PaintPhaseDescendantOutlinesOnly if no descendent outlines in the layer

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1367 matching lines @@
         invalidateDisplayItemClients(paintInvalidationContainer, PaintInvalidationSelection, nullptr);
 
     if (fullInvalidation)
         return;
 
     fullyInvalidatePaint(paintInvalidationContainer, PaintInvalidationSelection, oldSelectionRect, newSelectionRect);
 }
 
 PaintInvalidationReason LayoutObject::invalidatePaintIfNeeded(PaintInvalidationState& paintInvalidationState, const LayoutBoxModelObject& paintInvalidationContainer)
 {
+    if (styleRef().hasOutline()) {
+        PaintLayer* layer = enclosingLayer()->enclosingSelfPaintingLayer();

[chrishtr, 2016/01/12 23:52:24]

This is a tree walk for every LayoutObject. PaintInvalidationState goes to great
lengths to avoid this for paint invalidation container, I don't think we can
afford this cost...

[Xianzhu, 2016/01/13 00:11:03]

Not every LayoutObject, but only LayoutObject having outline which is relatively
rare.

Just noticed that we already have such tree walk in
LayoutObject::invalidateDisplayItemClients(), but there haven't been performance
regressions reported, so we should definitely fix this. Will land the fix before
this CL.

[chrishtr, 2016/01/13 05:01:17]

I'll wait for that patch first then.

+        if (layer->layoutObject() != this)

[chrishtr, 2016/01/12 23:52:24]

Why this conditional?

[Xianzhu, 2016/01/13 00:11:03]

We paint self outline and child outlines in different phases. Here we need to
exclude self outline.

+            layer->setNeedsPaintPhaseChildOutlines();
+    }
+
     LayoutView* v = view();
     if (v->document().printing())
         return PaintInvalidationNone; // Don't invalidate paints if we're printing.
 
     const LayoutRect oldBounds = previousPaintInvalidationRect();
     const LayoutPoint oldLocation = RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() ? LayoutPoint() : previousPositionFromPaintInvalidationBacking();
     LayoutRect newBounds = boundsRectForPaintInvalidation(paintInvalidationContainer, &paintInvalidationState);
     LayoutPoint newLocation = RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() ? LayoutPoint() : PaintLayer::positionFromPaintInvalidationBacking(this, &paintInvalidationContainer, &paintInvalidationState);
 
     // Composited scrolling should not be included in the bounds and position tracking, because the graphics layer backing the scroller
@@ skipping 2122 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif