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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/185099">185099</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2015-06-01 19:59:39 -0700 (Mon, 01 Jun 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>If a call has ever taken the virtual slow path, make sure that the DFG knows this
https://bugs.webkit.org/show_bug.cgi?id=145501
Reviewed by Geoffrey Garen.
Now now return higher fidelity information in the case of no polymorphic call stub. If the
virtual slow path was ever taken, we note this, and we note either zero or one call variant
based on the IC's last callee.
* bytecode/CallLinkStatus.cpp:
(JSC::CallLinkStatus::computeFromCallLinkInfo):
(JSC::CallLinkStatus::computeFor):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorebytecodeCallLinkStatuscpp">trunk/Source/JavaScriptCore/bytecode/CallLinkStatus.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 (185098 => 185099)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-06-02 02:55:36 UTC (rev 185098)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-06-02 02:59:39 UTC (rev 185099)
</span><span class="lines">@@ -1,3 +1,18 @@
</span><ins>+2015-05-31 Filip Pizlo <fpizlo@apple.com>
+
+ If a call has ever taken the virtual slow path, make sure that the DFG knows this
+ https://bugs.webkit.org/show_bug.cgi?id=145501
+
+ Reviewed by Geoffrey Garen.
+
+ Now now return higher fidelity information in the case of no polymorphic call stub. If the
+ virtual slow path was ever taken, we note this, and we note either zero or one call variant
+ based on the IC's last callee.
+
+ * bytecode/CallLinkStatus.cpp:
+ (JSC::CallLinkStatus::computeFromCallLinkInfo):
+ (JSC::CallLinkStatus::computeFor):
+
</ins><span class="cx"> 2015-06-01 Michael Saboff <msaboff@apple.com>
</span><span class="cx">
</span><span class="cx"> Crash in com.apple.WebKit.WebContent at com.apple.JavaScriptCore: JSC::revertCall + 24
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorebytecodeCallLinkStatuscpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/bytecode/CallLinkStatus.cpp (185098 => 185099)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/bytecode/CallLinkStatus.cpp 2015-06-02 02:55:36 UTC (rev 185098)
+++ trunk/Source/JavaScriptCore/bytecode/CallLinkStatus.cpp 2015-06-02 02:59:39 UTC (rev 185099)
</span><span class="lines">@@ -150,6 +150,11 @@
</span><span class="cx"> // that is still marginally valid (i.e. the pointers ain't stale). This kind of raciness
</span><span class="cx"> // is probably OK for now.
</span><span class="cx">
</span><ins>+ // FIXME: If the GC often clears this call, we should probably treat it like it always takes the
+ // slow path. We could be smart about this; for example if we cleared a specific callee but the
+ // despecified executable was alive then we could note that separately.
+ // https://bugs.webkit.org/show_bug.cgi?id=145502
+
</ins><span class="cx"> // PolymorphicCallStubRoutine is a GCAwareJITStubRoutine, so if non-null, it will stay alive
</span><span class="cx"> // until next GC even if the CallLinkInfo is concurrently cleared. Also, the variants list is
</span><span class="cx"> // never mutated after the PolymorphicCallStubRoutine is instantiated. We have some conservative
</span><span class="lines">@@ -209,17 +214,18 @@
</span><span class="cx"> return result;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- if (callLinkInfo.slowPathCount >= Options::couldTakeSlowCaseMinimumCount())
- return takesSlowPath();
</del><ins>+ CallLinkStatus result;
</ins><span class="cx">
</span><del>- JSFunction* target = callLinkInfo.lastSeenCallee.get();
- if (!target)
- return takesSlowPath();
</del><ins>+ if (JSFunction* target = callLinkInfo.lastSeenCallee.get()) {
+ CallVariant variant(target);
+ if (callLinkInfo.hasSeenClosure)
+ variant = variant.despecifiedClosure();
+ result.m_variants.append(variant);
+ }
</ins><span class="cx">
</span><del>- if (callLinkInfo.hasSeenClosure)
- return CallLinkStatus(target->executable());
</del><ins>+ result.m_couldTakeSlowPath = !!callLinkInfo.slowPathCount;
</ins><span class="cx">
</span><del>- return CallLinkStatus(target);
</del><ins>+ return result;
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> CallLinkStatus CallLinkStatus::computeFor(
</span></span></pre>
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