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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/191350">191350</a></dd>
<dt>Author</dt> <dd>sbarati@apple.com</dd>
<dt>Date</dt> <dd>2015-10-20 11:37:38 -0700 (Tue, 20 Oct 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>GCAwareJITStubRoutineWithExceptionHandler has a stale CodeBlock pointer in its destructor
https://bugs.webkit.org/show_bug.cgi?id=150351
Reviewed by Mark Lam.
We may regenerate many GCAwareJITStubRoutineWithExceptionHandler stubs per one PolymorphicAccess.
Only the last GCAwareJITStubRoutineWithExceptionHandler stub that was generated will get the CodeBlock's aboutToDie()
notification. All other GCAwareJITStubRoutineWithExceptionHandler stubs will still be holding a stale CodeBlock pointer
that they will use in their destructor. The solution is to have GCAwareJITStubRoutineWithExceptionHandler remove its
exception handler in observeZeroRefCount() instead of its destructor. observeZeroRefCount() will run when a PolymorphicAccess
replaces its m_stubRoutine.
* jit/GCAwareJITStubRoutine.cpp:
(JSC::GCAwareJITStubRoutineWithExceptionHandler::aboutToDie):
(JSC::GCAwareJITStubRoutineWithExceptionHandler::observeZeroRefCount):
(JSC::createJITStubRoutine):
(JSC::GCAwareJITStubRoutineWithExceptionHandler::~GCAwareJITStubRoutineWithExceptionHandler): Deleted.
* jit/GCAwareJITStubRoutine.h:</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorejitGCAwareJITStubRoutinecpp">trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCorejitGCAwareJITStubRoutineh">trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.h</a></li>
</ul>
</div>
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<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (191349 => 191350)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-10-20 18:33:38 UTC (rev 191349)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-10-20 18:37:38 UTC (rev 191350)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2015-10-20 Saam barati <sbarati@apple.com>
+
+ GCAwareJITStubRoutineWithExceptionHandler has a stale CodeBlock pointer in its destructor
+ https://bugs.webkit.org/show_bug.cgi?id=150351
+
+ Reviewed by Mark Lam.
+
+ We may regenerate many GCAwareJITStubRoutineWithExceptionHandler stubs per one PolymorphicAccess.
+ Only the last GCAwareJITStubRoutineWithExceptionHandler stub that was generated will get the CodeBlock's aboutToDie()
+ notification. All other GCAwareJITStubRoutineWithExceptionHandler stubs will still be holding a stale CodeBlock pointer
+ that they will use in their destructor. The solution is to have GCAwareJITStubRoutineWithExceptionHandler remove its
+ exception handler in observeZeroRefCount() instead of its destructor. observeZeroRefCount() will run when a PolymorphicAccess
+ replaces its m_stubRoutine.
+
+ * jit/GCAwareJITStubRoutine.cpp:
+ (JSC::GCAwareJITStubRoutineWithExceptionHandler::aboutToDie):
+ (JSC::GCAwareJITStubRoutineWithExceptionHandler::observeZeroRefCount):
+ (JSC::createJITStubRoutine):
+ (JSC::GCAwareJITStubRoutineWithExceptionHandler::~GCAwareJITStubRoutineWithExceptionHandler): Deleted.
+ * jit/GCAwareJITStubRoutine.h:
+
</ins><span class="cx"> 2015-10-20 Tim Horton <timothy_horton@apple.com>
</span><span class="cx">
</span><span class="cx"> Try to fix the build by disabling MAC_GESTURE_EVENTS on 10.9 and 10.10
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorejitGCAwareJITStubRoutinecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.cpp (191349 => 191350)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.cpp 2015-10-20 18:33:38 UTC (rev 191349)
+++ trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.cpp 2015-10-20 18:37:38 UTC (rev 191350)
</span><span class="lines">@@ -113,15 +113,18 @@
</span><span class="cx"> m_codeBlockWithExceptionHandler = nullptr;
</span><span class="cx"> }
</span><span class="cx">
</span><del>-GCAwareJITStubRoutineWithExceptionHandler::~GCAwareJITStubRoutineWithExceptionHandler()
</del><ins>+void GCAwareJITStubRoutineWithExceptionHandler::observeZeroRefCount()
</ins><span class="cx"> {
</span><span class="cx"> if (m_codeBlockWithExceptionHandler) {
</span><span class="cx"> m_codeBlockWithExceptionHandler->jitCode()->dfgCommon()->removeCallSiteIndex(m_exceptionHandlerCallSiteIndex);
</span><span class="cx"> m_codeBlockWithExceptionHandler->removeExceptionHandlerForCallSite(m_exceptionHandlerCallSiteIndex);
</span><ins>+ m_codeBlockWithExceptionHandler = nullptr;
</ins><span class="cx"> }
</span><ins>+
+ Base::observeZeroRefCount();
</ins><span class="cx"> }
</span><del>-
</del><span class="cx">
</span><ins>+
</ins><span class="cx"> PassRefPtr<JITStubRoutine> createJITStubRoutine(
</span><span class="cx"> const MacroAssemblerCodeRef& code,
</span><span class="cx"> VM& vm,
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorejitGCAwareJITStubRoutineh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.h (191349 => 191350)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.h 2015-10-20 18:33:38 UTC (rev 191349)
+++ trunk/Source/JavaScriptCore/jit/GCAwareJITStubRoutine.h 2015-10-20 18:37:38 UTC (rev 191350)
</span><span class="lines">@@ -95,10 +95,12 @@
</span><span class="cx"> // for new exception handlers to use the same CallSiteIndex.
</span><span class="cx"> class GCAwareJITStubRoutineWithExceptionHandler : public GCAwareJITStubRoutine {
</span><span class="cx"> public:
</span><ins>+ typedef GCAwareJITStubRoutine Base;
+
</ins><span class="cx"> GCAwareJITStubRoutineWithExceptionHandler(const MacroAssemblerCodeRef&, VM&, CodeBlock*, CallSiteIndex);
</span><del>- ~GCAwareJITStubRoutineWithExceptionHandler() override;
</del><span class="cx">
</span><span class="cx"> void aboutToDie() override;
</span><ins>+ void observeZeroRefCount() override;
</ins><span class="cx">
</span><span class="cx"> private:
</span><span class="cx"> CodeBlock* m_codeBlockWithExceptionHandler;
</span></span></pre>
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