Changeset 116203 in webkit

Timestamp:

May 4, 2012 7:17:15 PM (12 years ago)

Author:

jchaffraix@webkit.org

Message:

Leaf non self-painting layers should bail out early in RenderLayer::paintLayer
​https://bugs.webkit.org/show_bug.cgi?id=85678

Reviewed by Darin Adler.

Performance optimization, no expected change in behavior.

The gist of the change is that leaf non self-painting layers don't need to be painted as their
associated RenderBoxModelObject should properly paint itself without any help.

For RenderLayer trees that have a large number of leafs nodes (like a table with a leaf RenderLayer for
each cells), not bailing out is a big overhead as it ends up doing a lot of computation for no real
painting. See ​http://dglazkov.github.com/performance-tests/biggrid.html for a benchmark for that. On
my machine, it reduces the paint time when scrolling to 70ms from 120ms (45% speedup).

• rendering/RenderLayer.cpp:

(WebCore::RenderLayer::paintLayer):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• rendering/RenderLayer.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-05-04  Julien Chaffraix  <jchaffraix@webkit.org>
+
+        Leaf non self-painting layers should bail out early in RenderLayer::paintLayer
+        https://bugs.webkit.org/show_bug.cgi?id=85678
+
+        Reviewed by Darin Adler.
+
+        Performance optimization, no expected change in behavior.
+
+        The gist of the change is that leaf non self-painting layers don't need to be painted as their
+        associated RenderBoxModelObject should properly paint itself without any help.
+
+        For RenderLayer trees that have a large number of leafs nodes (like a table with a leaf RenderLayer for
+        each cells), not bailing out is a big overhead as it ends up doing a lot of computation for no real
+        painting. See http://dglazkov.github.com/performance-tests/biggrid.html for a benchmark for that. On
+        my machine, it reduces the paint time when scrolling to 70ms from 120ms (45% speedup).
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::paintLayer):
+
 2012-05-04  Rob Buis  <rbuis@rim.com>
 

trunk/Source/WebCore/rendering/RenderLayer.cpp

@@ -2901 +2901 @@
         return;
 
+    // Non self-painting leaf layers don't need to be painted as their renderer() should properly paint itself.
+    if (!isSelfPaintingLayer() && !firstChild())
+        return;
+
     if (paintsWithTransparency(paintBehavior))
         paintFlags |= PaintLayerHaveTransparency;