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<title>[189531] trunk/Source/JavaScriptCore</title>
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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/189531">189531</a></dd>
<dt>Author</dt> <dd>benjamin@webkit.org</dd>
<dt>Date</dt> <dd>2015-09-08 21:02:24 -0700 (Tue, 08 Sep 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>[JSC] reduce the amount of memory access needed for LivenessAnalysisPhase
https://bugs.webkit.org/show_bug.cgi?id=148414
Patch by Benjamin Poulain <bpoulain@apple.com> on 2015-09-08
Reviewed by Mark Lam.
LivenessAnalysisPhase still causes a huge number of cache miss.
This patch reduces the amount of accesses needed by the HashTables.
* dfg/DFGBasicBlock.h:
* dfg/DFGLivenessAnalysisPhase.cpp:
(JSC::DFG::LivenessAnalysisPhase::run):
(JSC::DFG::LivenessAnalysisPhase::process):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGBasicBlockh">trunk/Source/JavaScriptCore/dfg/DFGBasicBlock.h</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGLivenessAnalysisPhasecpp">trunk/Source/JavaScriptCore/dfg/DFGLivenessAnalysisPhase.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (189530 => 189531)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-09-09 03:27:48 UTC (rev 189530)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-09-09 04:02:24 UTC (rev 189531)
</span><span class="lines">@@ -1,3 +1,18 @@
</span><ins>+2015-09-08 Benjamin Poulain <bpoulain@apple.com>
+
+ [JSC] reduce the amount of memory access needed for LivenessAnalysisPhase
+ https://bugs.webkit.org/show_bug.cgi?id=148414
+
+ Reviewed by Mark Lam.
+
+ LivenessAnalysisPhase still causes a huge number of cache miss.
+ This patch reduces the amount of accesses needed by the HashTables.
+
+ * dfg/DFGBasicBlock.h:
+ * dfg/DFGLivenessAnalysisPhase.cpp:
+ (JSC::DFG::LivenessAnalysisPhase::run):
+ (JSC::DFG::LivenessAnalysisPhase::process):
+
</ins><span class="cx"> 2015-09-08 Myles C. Maxfield <mmaxfield@apple.com>
</span><span class="cx">
</span><span class="cx"> Prospective build fix after r189517
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGBasicBlockh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGBasicBlock.h (189530 => 189531)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGBasicBlock.h 2015-09-09 03:27:48 UTC (rev 189530)
+++ trunk/Source/JavaScriptCore/dfg/DFGBasicBlock.h 2015-09-09 04:02:24 UTC (rev 189531)
</span><span class="lines">@@ -239,8 +239,9 @@
</span><span class="cx"> AvailabilityMap availabilityAtHead;
</span><span class="cx"> AvailabilityMap availabilityAtTail;
</span><span class="cx">
</span><ins>+ bool liveAtTailIsDirty { false };
+ HashSet<Node*> liveAtTail;
</ins><span class="cx"> HashSet<Node*> liveAtHead;
</span><del>- HashSet<Node*> liveAtTail;
</del><span class="cx"> HashMap<Node*, AbstractValue> valuesAtHead;
</span><span class="cx"> HashMap<Node*, AbstractValue> valuesAtTail;
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGLivenessAnalysisPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGLivenessAnalysisPhase.cpp (189530 => 189531)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGLivenessAnalysisPhase.cpp 2015-09-09 03:27:48 UTC (rev 189530)
+++ trunk/Source/JavaScriptCore/dfg/DFGLivenessAnalysisPhase.cpp 2015-09-09 04:02:24 UTC (rev 189531)
</span><span class="lines">@@ -1,5 +1,5 @@
</span><span class="cx"> /*
</span><del>- * Copyright (C) 2013 Apple Inc. All rights reserved.
</del><ins>+ * Copyright (C) 2013, 2015 Apple Inc. All rights reserved.
</ins><span class="cx"> *
</span><span class="cx"> * Redistribution and use in source and binary forms, with or without
</span><span class="cx"> * modification, are permitted provided that the following conditions
</span><span class="lines">@@ -57,6 +57,7 @@
</span><span class="cx"> BasicBlock* block = m_graph.block(blockIndex);
</span><span class="cx"> if (!block)
</span><span class="cx"> continue;
</span><ins>+ block->ssa->liveAtTailIsDirty = true;
</ins><span class="cx"> block->ssa->liveAtHead.clear();
</span><span class="cx"> block->ssa->liveAtTail.clear();
</span><span class="cx"> }
</span><span class="lines">@@ -85,8 +86,11 @@
</span><span class="cx"> if (!block)
</span><span class="cx"> return;
</span><span class="cx">
</span><ins>+ if (!block->ssa->liveAtTailIsDirty)
+ return;
+ block->ssa->liveAtTailIsDirty = false;
+
</ins><span class="cx"> m_live = block->ssa->liveAtTail;
</span><del>-
</del><span class="cx"> for (unsigned nodeIndex = block->size(); nodeIndex--;) {
</span><span class="cx"> Node* node = block->at(nodeIndex);
</span><span class="cx">
</span><span class="lines">@@ -128,12 +132,16 @@
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><del>- if (m_live == block->ssa->liveAtHead)
- return;
-
- m_changed = true;
- for (unsigned i = block->predecessors.size(); i--;)
- block->predecessors[i]->ssa->liveAtTail.add(m_live.begin(), m_live.end());
</del><ins>+ for (Node* node : m_live) {
+ if (!block->ssa->liveAtHead.contains(node)) {
+ m_changed = true;
+ for (unsigned i = block->predecessors.size(); i--;) {
+ BasicBlock* predecessor = block->predecessors[i];
+ if (predecessor->ssa->liveAtTail.add(node).isNewEntry)
+ predecessor->ssa->liveAtTailIsDirty = true;
+ }
+ }
+ }
</ins><span class="cx"> block->ssa->liveAtHead = WTF::move(m_live);
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre>
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