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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/145947">145947</a></dd>
<dt>Author</dt> <dd>akling@apple.com</dd>
<dt>Date</dt> <dd>2013-03-15 14:57:55 -0700 (Fri, 15 Mar 2013)</dd>
</dl>

<h3>Log Message</h3>
<pre>Don't also clone StructureRareData when cloning Structure.
&lt;http://webkit.org/b/111672&gt;

Reviewed by Mark Hahnenberg.

We were cloning a lot of StructureRareData with only the previousID pointer set since
the enumerationCache is not shared between clones.

Let the Structure copy constructor decide whether it wants to clone the rare data.
The decision is made by StructureRareData::needsCloning() and will currently always
return false, since StructureRareData only holds on to caches at present.
This may change in the future as more members are added to StructureRareData.

* runtime/Structure.cpp:
(JSC::Structure::Structure):
(JSC::Structure::cloneRareDataFrom):
* runtime/StructureInlines.h:
(JSC::Structure::create):</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeStructurecpp">trunk/Source/JavaScriptCore/runtime/Structure.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeStructureInlinesh">trunk/Source/JavaScriptCore/runtime/StructureInlines.h</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeStructureRareDatah">trunk/Source/JavaScriptCore/runtime/StructureRareData.h</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (145946 => 145947)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog        2013-03-15 21:55:27 UTC (rev 145946)
+++ trunk/Source/JavaScriptCore/ChangeLog        2013-03-15 21:57:55 UTC (rev 145947)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2013-03-15  Andreas Kling  &lt;akling@apple.com&gt;
+
+        Don't also clone StructureRareData when cloning Structure.
+        &lt;http://webkit.org/b/111672&gt;
+
+        Reviewed by Mark Hahnenberg.
+
+        We were cloning a lot of StructureRareData with only the previousID pointer set since
+        the enumerationCache is not shared between clones.
+
+        Let the Structure copy constructor decide whether it wants to clone the rare data.
+        The decision is made by StructureRareData::needsCloning() and will currently always
+        return false, since StructureRareData only holds on to caches at present.
+        This may change in the future as more members are added to StructureRareData.
+
+        * runtime/Structure.cpp:
+        (JSC::Structure::Structure):
+        (JSC::Structure::cloneRareDataFrom):
+        * runtime/StructureInlines.h:
+        (JSC::Structure::create):
+
</ins><span class="cx"> 2013-03-15  Mark Hahnenberg  &lt;mhahnenberg@apple.com&gt;
</span><span class="cx"> 
</span><span class="cx">         Roll out r145838
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeStructurecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/Structure.cpp (145946 => 145947)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/Structure.cpp        2013-03-15 21:55:27 UTC (rev 145946)
+++ trunk/Source/JavaScriptCore/runtime/Structure.cpp        2013-03-15 21:57:55 UTC (rev 145947)
</span><span class="lines">@@ -207,7 +207,7 @@
</span><span class="cx">     , m_classInfo(previous-&gt;m_classInfo)
</span><span class="cx">     , m_transitionWatchpointSet(InitializedWatching)
</span><span class="cx">     , m_offset(invalidOffset)
</span><del>-    , m_typeInfo(previous-&gt;typeInfo())
</del><ins>+    , m_typeInfo(previous-&gt;typeInfo().type(), previous-&gt;typeInfo().flags() &amp; ~StructureHasRareData)
</ins><span class="cx">     , m_indexingType(previous-&gt;indexingTypeIncludingHistory())
</span><span class="cx">     , m_inlineCapacity(previous-&gt;m_inlineCapacity)
</span><span class="cx">     , m_dictionaryKind(previous-&gt;m_dictionaryKind)
</span><span class="lines">@@ -221,6 +221,11 @@
</span><span class="cx">     , m_didTransition(true)
</span><span class="cx">     , m_staticFunctionReified(previous-&gt;m_staticFunctionReified)
</span><span class="cx"> {
</span><ins>+    if (previous-&gt;typeInfo().structureHasRareData() &amp;&amp; previous-&gt;rareData()-&gt;needsCloning())
+        cloneRareDataFrom(globalData, previous);
+    else if (previous-&gt;previousID())
+        m_previousOrRareData.set(globalData, this, previous-&gt;previousID());
+
</ins><span class="cx">     previous-&gt;notifyTransitionFromThisStructure();
</span><span class="cx">     if (previous-&gt;m_globalObject)
</span><span class="cx">         m_globalObject.set(globalData, this, previous-&gt;m_globalObject.get());
</span><span class="lines">@@ -692,6 +697,7 @@
</span><span class="cx"> {
</span><span class="cx">     ASSERT(other-&gt;typeInfo().structureHasRareData());
</span><span class="cx">     StructureRareData* newRareData = StructureRareData::clone(globalData, other-&gt;rareData());
</span><ins>+    m_typeInfo = TypeInfo(typeInfo().type(), typeInfo().flags() | StructureHasRareData);
</ins><span class="cx">     m_previousOrRareData.set(globalData, this, newRareData);
</span><span class="cx"> }
</span><span class="cx"> 
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeStructureInlinesh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/StructureInlines.h (145946 => 145947)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/StructureInlines.h        2013-03-15 21:55:27 UTC (rev 145946)
+++ trunk/Source/JavaScriptCore/runtime/StructureInlines.h        2013-03-15 21:57:55 UTC (rev 145947)
</span><span class="lines">@@ -53,8 +53,6 @@
</span><span class="cx">     ASSERT(globalData.structureStructure);
</span><span class="cx">     Structure* newStructure = new (NotNull, allocateCell&lt;Structure&gt;(globalData.heap)) Structure(globalData, structure);
</span><span class="cx">     newStructure-&gt;finishCreation(globalData);
</span><del>-    if (structure-&gt;typeInfo().structureHasRareData())
-        newStructure-&gt;cloneRareDataFrom(globalData, structure);
</del><span class="cx">     return newStructure;
</span><span class="cx"> }
</span><span class="cx"> 
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeStructureRareDatah"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/StructureRareData.h (145946 => 145947)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/StructureRareData.h        2013-03-15 21:55:27 UTC (rev 145946)
+++ trunk/Source/JavaScriptCore/runtime/StructureRareData.h        2013-03-15 21:57:55 UTC (rev 145947)
</span><span class="lines">@@ -45,6 +45,9 @@
</span><span class="cx"> 
</span><span class="cx">     static Structure* createStructure(JSGlobalData&amp;, JSGlobalObject*, JSValue prototype);
</span><span class="cx"> 
</span><ins>+    // Returns true if this StructureRareData should also be cloned when cloning the owner Structure.
+    bool needsCloning() const { return false; }
+
</ins><span class="cx">     Structure* previousID() const;
</span><span class="cx">     void setPreviousID(JSGlobalData&amp;, Structure* transition, Structure*);
</span><span class="cx">     void clearPreviousID();
</span></span></pre>
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