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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/207230">207230</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2016-10-12 12:01:21 -0700 (Wed, 12 Oct 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>REGRESSION (<a href="http://trac.webkit.org/projects/webkit/changeset/207179">r207179</a>): ASSERTION FAILED: node.cell != previousCell
https://bugs.webkit.org/show_bug.cgi?id=163337
Reviewed by Mark Lam.
It turns out that HeapSnapshot was not down with revisiting. The concurrent GC is going to be
built around the idea that we can revisit objects many times. This means that any action that
should only take place once per object must check the object's state. This fixes the snapshot
code to do this.
While writing this code, I realized that we're actually doing this check incorrectly, so I
filed bug 163343. That bug requires a race, so we aren't going to see it yet.
* heap/HeapSnapshot.cpp:
(JSC::HeapSnapshot::finalize):
* heap/SlotVisitor.cpp:
(JSC::SlotVisitor::appendToMarkStack):
(JSC::SlotVisitor::visitChildren):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapHeapSnapshotcpp">trunk/Source/JavaScriptCore/heap/HeapSnapshot.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapSlotVisitorcpp">trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (207229 => 207230)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-10-12 18:47:53 UTC (rev 207229)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-10-12 19:01:21 UTC (rev 207230)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2016-10-12 Filip Pizlo <fpizlo@apple.com>
+
+ REGRESSION (r207179): ASSERTION FAILED: node.cell != previousCell
+ https://bugs.webkit.org/show_bug.cgi?id=163337
+
+ Reviewed by Mark Lam.
+
+ It turns out that HeapSnapshot was not down with revisiting. The concurrent GC is going to be
+ built around the idea that we can revisit objects many times. This means that any action that
+ should only take place once per object must check the object's state. This fixes the snapshot
+ code to do this.
+
+ While writing this code, I realized that we're actually doing this check incorrectly, so I
+ filed bug 163343. That bug requires a race, so we aren't going to see it yet.
+
+ * heap/HeapSnapshot.cpp:
+ (JSC::HeapSnapshot::finalize):
+ * heap/SlotVisitor.cpp:
+ (JSC::SlotVisitor::appendToMarkStack):
+ (JSC::SlotVisitor::visitChildren):
+
</ins><span class="cx"> 2016-10-12 Joseph Pecoraro <pecoraro@apple.com>
</span><span class="cx">
</span><span class="cx"> Web Inspector: Improve support for logging Proxy objects in console
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapHeapSnapshotcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/HeapSnapshot.cpp (207229 => 207230)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/HeapSnapshot.cpp 2016-10-12 18:47:53 UTC (rev 207229)
+++ trunk/Source/JavaScriptCore/heap/HeapSnapshot.cpp 2016-10-12 19:01:21 UTC (rev 207230)
</span><span class="lines">@@ -121,8 +121,10 @@
</span><span class="cx"> for (auto& node : m_nodes) {
</span><span class="cx"> ASSERT(node.cell);
</span><span class="cx"> ASSERT(!(reinterpret_cast<intptr_t>(node.cell) & CellToSweepTag));
</span><del>- if (previousCell)
</del><ins>+ if (node.cell == previousCell) {
+ dataLog("Seeing same cell twice: ", RawPointer(previousCell), "\n");
</ins><span class="cx"> ASSERT(node.cell != previousCell);
</span><ins>+ }
</ins><span class="cx"> previousCell = node.cell;
</span><span class="cx"> }
</span><span class="cx"> #endif
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapSlotVisitorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp (207229 => 207230)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp 2016-10-12 18:47:53 UTC (rev 207229)
+++ trunk/Source/JavaScriptCore/heap/SlotVisitor.cpp 2016-10-12 19:01:21 UTC (rev 207230)
</span><span class="lines">@@ -237,9 +237,6 @@
</span><span class="cx"> m_bytesVisited += container.cellSize();
</span><span class="cx">
</span><span class="cx"> m_stack.append(cell);
</span><del>-
- if (UNLIKELY(m_heapSnapshotBuilder))
- m_heapSnapshotBuilder->appendNode(cell);
</del><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void SlotVisitor::markAuxiliary(const void* base)
</span><span class="lines">@@ -319,6 +316,11 @@
</span><span class="cx"> cell->methodTable()->visitChildren(const_cast<JSCell*>(cell), *this);
</span><span class="cx"> break;
</span><span class="cx"> }
</span><ins>+
+ if (UNLIKELY(m_heapSnapshotBuilder)) {
+ if (cell->cellState() != CellState::OldBlack)
+ m_heapSnapshotBuilder->appendNode(const_cast<JSCell*>(cell));
+ }
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void SlotVisitor::donateKnownParallel()
</span></span></pre>
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