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<title>[211112] trunk/Source/JavaScriptCore</title>
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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/211112">211112</a></dd>
<dt>Author</dt> <dd>commit-queue@webkit.org</dd>
<dt>Date</dt> <dd>2017-01-24 14:40:40 -0800 (Tue, 24 Jan 2017)</dd>
</dl>
<h3>Log Message</h3>
<pre>Unreviewed, rolling out <a href="http://trac.webkit.org/projects/webkit/changeset/211091">r211091</a>.
https://bugs.webkit.org/show_bug.cgi?id=167384
introduces a subtle bug in InferredTypeTable, huge
Octane/deltablue regression (Requested by pizlo on #webkit).
Reverted changeset:
"InferredTypeTable entry manipulation is not TOCTOU race safe"
https://bugs.webkit.org/show_bug.cgi?id=167344
http://trac.webkit.org/changeset/211091</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeInferredTypeTablecpp">trunk/Source/JavaScriptCore/runtime/InferredTypeTable.cpp</a></li>
</ul>
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<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (211111 => 211112)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2017-01-24 22:07:34 UTC (rev 211111)
+++ trunk/Source/JavaScriptCore/ChangeLog 2017-01-24 22:40:40 UTC (rev 211112)
</span><span class="lines">@@ -1,3 +1,17 @@
</span><ins>+2017-01-24 Commit Queue <commit-queue@webkit.org>
+
+ Unreviewed, rolling out r211091.
+ https://bugs.webkit.org/show_bug.cgi?id=167384
+
+ introduces a subtle bug in InferredTypeTable, huge
+ Octane/deltablue regression (Requested by pizlo on #webkit).
+
+ Reverted changeset:
+
+ "InferredTypeTable entry manipulation is not TOCTOU race safe"
+ https://bugs.webkit.org/show_bug.cgi?id=167344
+ http://trac.webkit.org/changeset/211091
+
</ins><span class="cx"> 2017-01-24 Filip Pizlo <fpizlo@apple.com>
</span><span class="cx">
</span><span class="cx"> Enable the stochastic space-time scheduler on the larger multicores
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeInferredTypeTablecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/InferredTypeTable.cpp (211111 => 211112)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/InferredTypeTable.cpp 2017-01-24 22:07:34 UTC (rev 211111)
+++ trunk/Source/JavaScriptCore/runtime/InferredTypeTable.cpp 2017-01-24 22:40:40 UTC (rev 211112)
</span><span class="lines">@@ -57,12 +57,10 @@
</span><span class="cx"> ConcurrentJSLocker locker(inferredTypeTable->m_lock);
</span><span class="cx">
</span><span class="cx"> for (auto& entry : inferredTypeTable->m_table) {
</span><del>- auto entryValue = entry.value;
-
- if (!entryValue)
</del><ins>+ if (!entry.value)
</ins><span class="cx"> continue;
</span><del>- if (entryValue->isRelevant())
- visitor.append(entryValue);
</del><ins>+ if (entry.value->isRelevant())
+ visitor.append(entry.value);
</ins><span class="cx"> else
</span><span class="cx"> entry.value.clear();
</span><span class="cx"> }
</span><span class="lines">@@ -71,20 +69,16 @@
</span><span class="cx"> InferredType* InferredTypeTable::get(const ConcurrentJSLocker&, UniquedStringImpl* uid)
</span><span class="cx"> {
</span><span class="cx"> auto iter = m_table.find(uid);
</span><del>- if (iter == m_table.end())
</del><ins>+ if (iter == m_table.end() || !iter->value)
</ins><span class="cx"> return nullptr;
</span><span class="cx">
</span><del>- auto entryValue = iter->value;
- if (!entryValue)
- return nullptr;
-
</del><span class="cx"> // Take this opportunity to prune invalidated types.
</span><del>- if (!entryValue->isRelevant()) {
</del><ins>+ if (!iter->value->isRelevant()) {
</ins><span class="cx"> iter->value.clear();
</span><span class="cx"> return nullptr;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- return entryValue.get();
</del><ins>+ return iter->value.get();
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> InferredType* InferredTypeTable::get(UniquedStringImpl* uid)
</span><span class="lines">@@ -105,14 +99,10 @@
</span><span class="cx">
</span><span class="cx"> if (age == OldProperty) {
</span><span class="cx"> TableType::iterator iter = m_table.find(propertyName.uid());
</span><del>- if (iter == m_table.end())
</del><ins>+ if (iter == m_table.end() || !iter->value)
</ins><span class="cx"> return false; // Absence on replace => top.
</span><del>-
- auto entryValue = iter->value;
- if (!entryValue)
- return false;
</del><span class="cx">
</span><del>- if (entryValue->willStoreValue(vm, propertyName, value))
</del><ins>+ if (iter->value->willStoreValue(vm, propertyName, value))
</ins><span class="cx"> return true;
</span><span class="cx">
</span><span class="cx"> iter->value.clear();
</span><span class="lines">@@ -124,16 +114,14 @@
</span><span class="cx"> ConcurrentJSLocker locker(m_lock);
</span><span class="cx"> result = m_table.add(propertyName.uid(), WriteBarrier<InferredType>());
</span><span class="cx"> }
</span><del>- auto entryValue = result.iterator->value;
-
</del><span class="cx"> if (result.isNewEntry) {
</span><span class="cx"> InferredType* inferredType = InferredType::create(vm);
</span><span class="cx"> WTF::storeStoreFence();
</span><del>- entryValue.set(vm, this, inferredType);
- } else if (!entryValue)
</del><ins>+ result.iterator->value.set(vm, this, inferredType);
+ } else if (!result.iterator->value)
</ins><span class="cx"> return false;
</span><span class="cx">
</span><del>- if (entryValue->willStoreValue(vm, propertyName, value))
</del><ins>+ if (result.iterator->value->willStoreValue(vm, propertyName, value))
</ins><span class="cx"> return true;
</span><span class="cx">
</span><span class="cx"> result.iterator->value.clear();
</span><span class="lines">@@ -145,15 +133,10 @@
</span><span class="cx"> // The algorithm here relies on the fact that only one thread modifies the hash map.
</span><span class="cx"> if (age == OldProperty) {
</span><span class="cx"> TableType::iterator iter = m_table.find(propertyName.uid());
</span><del>- if (iter == m_table.end())
</del><ins>+ if (iter == m_table.end() || !iter->value)
</ins><span class="cx"> return; // Absence on replace => top.
</span><span class="cx">
</span><del>- auto entryValue = iter->value;
-
- if (!entryValue)
- return;
-
- entryValue->makeTop(vm, propertyName);
</del><ins>+ iter->value->makeTop(vm, propertyName);
</ins><span class="cx"> iter->value.clear();
</span><span class="cx"> return;
</span><span class="cx"> }
</span></span></pre>
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