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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/189554">189554</a></dd>
<dt>Author</dt> <dd>ggaren@apple.com</dd>
<dt>Date</dt> <dd>2015-09-09 15:06:49 -0700 (Wed, 09 Sep 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>CodeBlocks should strongly visit their OSR exit targets
https://bugs.webkit.org/show_bug.cgi?id=148988
Reviewed by Saam Barati.
CodeBlocks jump to their OSR exit targets, so we need to keep them alive
explicitly.
This is a step toward throwing away CodeBlocks, which is only safe
if we keep alive logically in-use CodeBlocks.
* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::CodeBlock):
(JSC::CodeBlock::visitStrongly): Added a flag to indicate if visit
strongly had been performed yet, since we are likely to revisit
the same CodeBlock many times now.
(JSC::CodeBlock::visitOSRExitTargets):
(JSC::CodeBlock::stronglyVisitStrongReferences): Do the visiting.
* bytecode/CodeBlock.h:
(JSC::CodeBlock::clearMarks):
(JSC::CodeBlockSet::mark): Added a helper function for clearing out
two flags.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorebytecodeCodeBlockcpp">trunk/Source/JavaScriptCore/bytecode/CodeBlock.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCorebytecodeCodeBlockh">trunk/Source/JavaScriptCore/bytecode/CodeBlock.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (189553 => 189554)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-09-09 22:00:58 UTC (rev 189553)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-09-09 22:06:49 UTC (rev 189554)
</span><span class="lines">@@ -1,5 +1,32 @@
</span><span class="cx"> 2015-09-09 Geoffrey Garen <ggaren@apple.com>
</span><span class="cx">
</span><ins>+ CodeBlocks should strongly visit their OSR exit targets
+ https://bugs.webkit.org/show_bug.cgi?id=148988
+
+ Reviewed by Saam Barati.
+
+ CodeBlocks jump to their OSR exit targets, so we need to keep them alive
+ explicitly.
+
+ This is a step toward throwing away CodeBlocks, which is only safe
+ if we keep alive logically in-use CodeBlocks.
+
+ * bytecode/CodeBlock.cpp:
+ (JSC::CodeBlock::CodeBlock):
+ (JSC::CodeBlock::visitStrongly): Added a flag to indicate if visit
+ strongly had been performed yet, since we are likely to revisit
+ the same CodeBlock many times now.
+
+ (JSC::CodeBlock::visitOSRExitTargets):
+ (JSC::CodeBlock::stronglyVisitStrongReferences): Do the visiting.
+
+ * bytecode/CodeBlock.h:
+ (JSC::CodeBlock::clearMarks):
+ (JSC::CodeBlockSet::mark): Added a helper function for clearing out
+ two flags.
+
+2015-09-09 Geoffrey Garen <ggaren@apple.com>
+
</ins><span class="cx"> Unreviewed, rolling back in r189516.
</span><span class="cx"> https://bugs.webkit.org/show_bug.cgi?id=148989
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorebytecodeCodeBlockcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/bytecode/CodeBlock.cpp (189553 => 189554)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/bytecode/CodeBlock.cpp 2015-09-09 22:00:58 UTC (rev 189553)
+++ trunk/Source/JavaScriptCore/bytecode/CodeBlock.cpp 2015-09-09 22:06:49 UTC (rev 189554)
</span><span class="lines">@@ -1708,6 +1708,7 @@
</span><span class="cx"> , m_capabilityLevelState(DFG::CapabilityLevelNotSet)
</span><span class="cx"> #endif
</span><span class="cx"> {
</span><ins>+ m_visitStronglyHasBeenCalled.store(false, std::memory_order_relaxed);
</ins><span class="cx"> m_visitAggregateHasBeenCalled.store(false, std::memory_order_relaxed);
</span><span class="cx">
</span><span class="cx"> ASSERT(m_heap->isDeferred());
</span><span class="lines">@@ -1761,6 +1762,7 @@
</span><span class="cx"> , m_capabilityLevelState(DFG::CapabilityLevelNotSet)
</span><span class="cx"> #endif
</span><span class="cx"> {
</span><ins>+ m_visitStronglyHasBeenCalled.store(false, std::memory_order_relaxed);
</ins><span class="cx"> m_visitAggregateHasBeenCalled.store(false, std::memory_order_relaxed);
</span><span class="cx">
</span><span class="cx"> ASSERT(m_heap->isDeferred());
</span><span class="lines">@@ -2299,6 +2301,10 @@
</span><span class="cx">
</span><span class="cx"> void CodeBlock::visitStrongly(SlotVisitor& visitor)
</span><span class="cx"> {
</span><ins>+ bool setByMe = m_visitStronglyHasBeenCalled.compareExchangeStrong(false, true);
+ if (!setByMe)
+ return;
+
</ins><span class="cx"> visitAggregate(visitor);
</span><span class="cx">
</span><span class="cx"> stronglyVisitStrongReferences(visitor);
</span><span class="lines">@@ -2816,6 +2822,21 @@
</span><span class="cx"> }
</span><span class="cx"> #endif
</span><span class="cx">
</span><ins>+void CodeBlock::visitOSRExitTargets(SlotVisitor& visitor)
+{
+ // OSR exits, once compiled, link themselves directly to their targets.
+ // We need to keep those targets alive in order to keep OSR exit from
+ // jumping to an invalid destination.
+
+ alternative()->visitStrongly(visitor);
+
+ DFG::CommonData* dfgCommon = m_jitCode->dfgCommon();
+ if (dfgCommon->inlineCallFrames) {
+ for (auto* inlineCallFrame : *dfgCommon->inlineCallFrames)
+ inlineCallFrame->baselineCodeBlock()->visitStrongly(visitor);
+ }
+}
+
</ins><span class="cx"> void CodeBlock::stronglyVisitStrongReferences(SlotVisitor& visitor)
</span><span class="cx"> {
</span><span class="cx"> visitor.append(&m_globalObject);
</span><span class="lines">@@ -2831,6 +2852,11 @@
</span><span class="cx"> for (unsigned i = 0; i < m_objectAllocationProfiles.size(); ++i)
</span><span class="cx"> m_objectAllocationProfiles[i].visitAggregate(visitor);
</span><span class="cx">
</span><ins>+#if ENABLE(DFG_JIT)
+ if (JITCode::isOptimizingJIT(jitType()))
+ visitOSRExitTargets(visitor);
+#endif
+
</ins><span class="cx"> updateAllPredictions();
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorebytecodeCodeBlockh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/bytecode/CodeBlock.h (189553 => 189554)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/bytecode/CodeBlock.h 2015-09-09 22:00:58 UTC (rev 189553)
+++ trunk/Source/JavaScriptCore/bytecode/CodeBlock.h 2015-09-09 22:06:49 UTC (rev 189554)
</span><span class="lines">@@ -972,6 +972,7 @@
</span><span class="cx">
</span><span class="cx"> void stronglyVisitStrongReferences(SlotVisitor&);
</span><span class="cx"> void stronglyVisitWeakReferences(SlotVisitor&);
</span><ins>+ void visitOSRExitTargets(SlotVisitor&);
</ins><span class="cx">
</span><span class="cx"> void createRareDataIfNecessary()
</span><span class="cx"> {
</span><span class="lines">@@ -1003,6 +1004,7 @@
</span><span class="cx"> bool m_needsActivation;
</span><span class="cx">
</span><span class="cx"> Atomic<bool> m_visitAggregateHasBeenCalled;
</span><ins>+ Atomic<bool> m_visitStronglyHasBeenCalled;
</ins><span class="cx">
</span><span class="cx"> RefPtr<SourceProvider> m_source;
</span><span class="cx"> unsigned m_sourceOffset;
</span><span class="lines">@@ -1208,6 +1210,7 @@
</span><span class="cx">
</span><span class="cx"> inline void CodeBlock::clearMarks()
</span><span class="cx"> {
</span><ins>+ m_visitStronglyHasBeenCalled.store(false, std::memory_order_relaxed);
</ins><span class="cx"> m_visitAggregateHasBeenCalled.store(false, std::memory_order_relaxed);
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -1238,7 +1241,7 @@
</span><span class="cx"> // that have not executed a barrier. This is overkill, but we have always
</span><span class="cx"> // done this, and it might help us recover gracefully if we forget to execute
</span><span class="cx"> // a barrier when a CodeBlock needs it.
</span><del>- codeBlock->m_visitAggregateHasBeenCalled.store(false, std::memory_order_relaxed);
</del><ins>+ codeBlock->clearMarks();
</ins><span class="cx">
</span><span class="cx"> #if ENABLE(GGC)
</span><span class="cx"> m_currentlyExecuting.add(codeBlock);
</span></span></pre>
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