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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/184927">184927</a></dd>
<dt>Author</dt> <dd>basile_clement@apple.com</dd>
<dt>Date</dt> <dd>2015-05-27 16:47:40 -0700 (Wed, 27 May 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>LazyNode comparison can return incorrect results when comparing an empty value
https://bugs.webkit.org/show_bug.cgi?id=145421
Reviewed by Geoffrey Garen.
When comparing a LazyNode to another, we compare the value pointers if
we have one, and otherwise compare the nodes.
We should be comparing value pointers if the other LazyNode has one as
well, otherwise we risk an incoherency when we are a empty LazyNode
being compared to a FrozenValue without node.
Note that this is not a problem in any other case because if we don't
have a FrozenValue and we are not an empty LazyNode, we are a
non-constant node, and comparing the node pointers is correct.
* dfg/DFGLazyNode.h:
(JSC::DFG::LazyNode::operator==):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGLazyNodeh">trunk/Source/JavaScriptCore/dfg/DFGLazyNode.h</a></li>
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<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (184926 => 184927)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-05-27 23:43:22 UTC (rev 184926)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-05-27 23:47:40 UTC (rev 184927)
</span><span class="lines">@@ -1,3 +1,23 @@
</span><ins>+2015-05-27 Basile Clement <basile_clement@apple.com>
+
+ LazyNode comparison can return incorrect results when comparing an empty value
+ https://bugs.webkit.org/show_bug.cgi?id=145421
+
+ Reviewed by Geoffrey Garen.
+
+ When comparing a LazyNode to another, we compare the value pointers if
+ we have one, and otherwise compare the nodes.
+ We should be comparing value pointers if the other LazyNode has one as
+ well, otherwise we risk an incoherency when we are a empty LazyNode
+ being compared to a FrozenValue without node.
+
+ Note that this is not a problem in any other case because if we don't
+ have a FrozenValue and we are not an empty LazyNode, we are a
+ non-constant node, and comparing the node pointers is correct.
+
+ * dfg/DFGLazyNode.h:
+ (JSC::DFG::LazyNode::operator==):
+
</ins><span class="cx"> 2015-05-27 Geoffrey Garen <ggaren@apple.com>
</span><span class="cx">
</span><span class="cx"> REGRESSION: These sorting idioms used by Peacekeeper and Browsermark are ~20X slower
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGLazyNodeh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGLazyNode.h (184926 => 184927)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGLazyNode.h 2015-05-27 23:43:22 UTC (rev 184926)
+++ trunk/Source/JavaScriptCore/dfg/DFGLazyNode.h 2015-05-27 23:47:40 UTC (rev 184927)
</span><span class="lines">@@ -34,8 +34,6 @@
</span><span class="cx">
</span><span class="cx"> namespace JSC { namespace DFG {
</span><span class="cx">
</span><del>-
-
</del><span class="cx"> class LazyNode {
</span><span class="cx"> public:
</span><span class="cx"> static const size_t jsConstantTag = 0;
</span><span class="lines">@@ -119,7 +117,7 @@
</span><span class="cx">
</span><span class="cx"> bool operator==(const LazyNode& other) const
</span><span class="cx"> {
</span><del>- if (asValue())
</del><ins>+ if (asValue() || other.asValue())
</ins><span class="cx"> return m_value == other.m_value;
</span><span class="cx"> return m_node == other.m_node;
</span><span class="cx"> }
</span></span></pre>
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