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<title>[200898] trunk/Source/JavaScriptCore</title>
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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/200898">200898</a></dd>
<dt>Author</dt> <dd>benjamin@webkit.org</dd>
<dt>Date</dt> <dd>2016-05-13 16:45:44 -0700 (Fri, 13 May 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>[JSC] SetLocal without exit do not need phantoms
https://bugs.webkit.org/show_bug.cgi?id=157653
Patch by Benjamin Poulain <bpoulain@apple.com> on 2016-05-13
Reviewed by Filip Pizlo.
I made a mistake in <a href="http://trac.webkit.org/projects/webkit/changeset/200498">r200498</a>.
If a SetLocal cannot possibly exit, we were not clearing
the source of the operand. As a result, we sometime kept
a value alive up to the end of the block.
That's uncommon because SetLocal typically appear
toward the end of blocks. That's probably why there was
no perf impact with that fix.
* dfg/DFGPhantomInsertionPhase.cpp:</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGPhantomInsertionPhasecpp">trunk/Source/JavaScriptCore/dfg/DFGPhantomInsertionPhase.cpp</a></li>
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<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (200897 => 200898)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-05-13 23:45:15 UTC (rev 200897)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-05-13 23:45:44 UTC (rev 200898)
</span><span class="lines">@@ -1,5 +1,24 @@
</span><span class="cx"> 2016-05-13 Benjamin Poulain <bpoulain@apple.com>
</span><span class="cx">
</span><ins>+ [JSC] SetLocal without exit do not need phantoms
+ https://bugs.webkit.org/show_bug.cgi?id=157653
+
+ Reviewed by Filip Pizlo.
+
+ I made a mistake in r200498.
+
+ If a SetLocal cannot possibly exit, we were not clearing
+ the source of the operand. As a result, we sometime kept
+ a value alive up to the end of the block.
+
+ That's uncommon because SetLocal typically appear
+ toward the end of blocks. That's probably why there was
+ no perf impact with that fix.
+
+ * dfg/DFGPhantomInsertionPhase.cpp:
+
+2016-05-13 Benjamin Poulain <bpoulain@apple.com>
+
</ins><span class="cx"> [JSC] Move the CheckTierUp function calls out of the main path
</span><span class="cx"> https://bugs.webkit.org/show_bug.cgi?id=157668
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGPhantomInsertionPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGPhantomInsertionPhase.cpp (200897 => 200898)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGPhantomInsertionPhase.cpp 2016-05-13 23:45:15 UTC (rev 200897)
+++ trunk/Source/JavaScriptCore/dfg/DFGPhantomInsertionPhase.cpp 2016-05-13 23:45:44 UTC (rev 200898)
</span><span class="lines">@@ -173,12 +173,14 @@
</span><span class="cx"> killedNode->defaultEdge());
</span><span class="cx"> };
</span><span class="cx">
</span><del>- if (nodeMayExit && node->op() == SetLocal) {
- // If the SetLocal does exit, we need the MovHint of its local
- // to be live until the SetLocal is done.
</del><ins>+ if (node->op() == SetLocal) {
</ins><span class="cx"> VirtualRegister local = node->local();
</span><del>- processKilledOperand(local);
- alreadyKilled = local;
</del><ins>+ if (nodeMayExit) {
+ // If the SetLocal does exit, we need the MovHint of its local
+ // to be live until the SetLocal is done.
+ processKilledOperand(local);
+ alreadyKilled = local;
+ }
</ins><span class="cx"> m_values.operand(local) = nullptr;
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre>
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