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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/180090">180090</a></dd>
<dt>Author</dt> <dd>cdumez@apple.com</dd>
<dt>Date</dt> <dd>2015-02-13 16:37:40 -0800 (Fri, 13 Feb 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>RenderListItem resets its marker's style on style change even if the diff is StyleDifferenceEqual
https://bugs.webkit.org/show_bug.cgi?id=141572
<rdar://problem/19759818>
Reviewed by Simon Fraser.
Source/WebCore:
Do not unnecessarily update the marker's style in RenderListItem::styleDidChange()
if the RenderStyle diff is StyleDifferenceEqual. Doing so can cause unnecessary
layouts.
This was causing high cpu usage on
http://www.nokogiri.org/tutorials/searching_a_xml_html_document.html because there
is an animation that changes the style every second (but the diff is equal) and the
RenderListItem keeps resetting its marker's margin, which triggers a layout and the
RenderListMarker re-computes its margin during layout and updates its style again.
With this change, CPU usage on the page goes from 150% to 20%. There is only a style
recalc happening every second, no more relayouts and repaints.
Test: fast/repaint/list-item-equal-style-change-no-repaint.html
* rendering/RenderListItem.cpp:
(WebCore::RenderListItem::styleDidChange):
LayoutTests:
Add a layout test to make sure that an animation causing a style change
with StyleDifferenceEqual diff does not cause a repaint.
* fast/repaint/list-item-equal-style-change-no-repaint-expected.txt: Added.
* fast/repaint/list-item-equal-style-change-no-repaint.html: Added.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsChangeLog">trunk/LayoutTests/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderListItemcpp">trunk/Source/WebCore/rendering/RenderListItem.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsfastrepaintlistitemequalstylechangenorepaintexpectedtxt">trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint-expected.txt</a></li>
<li><a href="#trunkLayoutTestsfastrepaintlistitemequalstylechangenorepainthtml">trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint.html</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (180089 => 180090)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog        2015-02-14 00:15:27 UTC (rev 180089)
+++ trunk/LayoutTests/ChangeLog        2015-02-14 00:37:40 UTC (rev 180090)
</span><span class="lines">@@ -1,3 +1,17 @@
</span><ins>+2015-02-13 Chris Dumez <cdumez@apple.com>
+
+ RenderListItem resets its marker's style on style change even if the diff is StyleDifferenceEqual
+ https://bugs.webkit.org/show_bug.cgi?id=141572
+ <rdar://problem/19759818>
+
+ Reviewed by Simon Fraser.
+
+ Add a layout test to make sure that an animation causing a style change
+ with StyleDifferenceEqual diff does not cause a repaint.
+
+ * fast/repaint/list-item-equal-style-change-no-repaint-expected.txt: Added.
+ * fast/repaint/list-item-equal-style-change-no-repaint.html: Added.
+
</ins><span class="cx"> 2015-02-12 Enrica Casucci <enrica@apple.com>
</span><span class="cx">
</span><span class="cx"> Additional emoji group support.
</span></span></pre></div>
<a id="trunkLayoutTestsfastrepaintlistitemequalstylechangenorepaintexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint-expected.txt (0 => 180090)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint-expected.txt         (rev 0)
+++ trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint-expected.txt        2015-02-14 00:37:40 UTC (rev 180090)
</span><span class="lines">@@ -0,0 +1,2 @@
</span><ins>+Test
+
</ins></span></pre></div>
<a id="trunkLayoutTestsfastrepaintlistitemequalstylechangenorepainthtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint.html (0 => 180090)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint.html         (rev 0)
+++ trunk/LayoutTests/fast/repaint/list-item-equal-style-change-no-repaint.html        2015-02-14 00:37:40 UTC (rev 180090)
</span><span class="lines">@@ -0,0 +1,35 @@
</span><ins>+<!DOCTYPE html>
+<html>
+ <head>
+ <style>
+ body {
+ margin: 0;
+ }
+
+ .animated {
+ -webkit-animation: test 1s;
+ }
+
+ @-webkit-keyframes test {
+ from {
+ padding: 0;
+ }
+ to {
+ padding: 0;
+ }
+ }
+ </style>
+ <script src="resources/text-based-repaint.js"></script>
+ <script>
+ function repaintTest() {
+ // This should not trigger a repaint.
+ document.body.classList.add('animated');
+ }
+ </script>
+ </head>
+ <body onload="runRepaintTest();">
+ <ul>
+ <li>Test</li>
+ </ul>
+ </body>
+</html>
</ins></span></pre></div>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (180089 => 180090)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog        2015-02-14 00:15:27 UTC (rev 180089)
+++ trunk/Source/WebCore/ChangeLog        2015-02-14 00:37:40 UTC (rev 180090)
</span><span class="lines">@@ -1,3 +1,29 @@
</span><ins>+2015-02-13 Chris Dumez <cdumez@apple.com>
+
+ RenderListItem resets its marker's style on style change even if the diff is StyleDifferenceEqual
+ https://bugs.webkit.org/show_bug.cgi?id=141572
+ <rdar://problem/19759818>
+
+ Reviewed by Simon Fraser.
+
+ Do not unnecessarily update the marker's style in RenderListItem::styleDidChange()
+ if the RenderStyle diff is StyleDifferenceEqual. Doing so can cause unnecessary
+ layouts.
+
+ This was causing high cpu usage on
+ http://www.nokogiri.org/tutorials/searching_a_xml_html_document.html because there
+ is an animation that changes the style every second (but the diff is equal) and the
+ RenderListItem keeps resetting its marker's margin, which triggers a layout and the
+ RenderListMarker re-computes its margin during layout and updates its style again.
+
+ With this change, CPU usage on the page goes from 150% to 20%. There is only a style
+ recalc happening every second, no more relayouts and repaints.
+
+ Test: fast/repaint/list-item-equal-style-change-no-repaint.html
+
+ * rendering/RenderListItem.cpp:
+ (WebCore::RenderListItem::styleDidChange):
+
</ins><span class="cx"> 2015-02-13 Timothy Horton <timothy_horton@apple.com>
</span><span class="cx">
</span><span class="cx"> Make WebCore::IOSurface have single ownership instead of refcounting
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderListItemcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderListItem.cpp (180089 => 180090)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderListItem.cpp        2015-02-14 00:15:27 UTC (rev 180089)
+++ trunk/Source/WebCore/rendering/RenderListItem.cpp        2015-02-14 00:37:40 UTC (rev 180090)
</span><span class="lines">@@ -82,8 +82,11 @@
</span><span class="cx"> if (!m_marker) {
</span><span class="cx"> m_marker = createRenderer<RenderListMarker>(*this, WTF::move(newStyle)).leakPtr();
</span><span class="cx"> m_marker->initializeStyle();
</span><del>- } else
- m_marker->setStyle(WTF::move(newStyle));
</del><ins>+ } else {
+ // Do not alter our marker's style unless our style has actually changed.
+ if (diff != StyleDifferenceEqual)
+ m_marker->setStyle(WTF::move(newStyle));
+ }
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void RenderListItem::insertedIntoTree()
</span></span></pre>
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