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<title>[199710] trunk/Source/JavaScriptCore</title>
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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/199710">199710</a></dd>
<dt>Author</dt> <dd>commit-queue@webkit.org</dd>
<dt>Date</dt> <dd>2016-04-18 23:54:25 -0700 (Mon, 18 Apr 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>[JSC] Fix some overhead affecting small codegen
https://bugs.webkit.org/show_bug.cgi?id=156728
Patch by Benjamin Poulain <bpoulain@apple.com> on 2016-04-18
Reviewed by Filip Pizlo.
* assembler/AbstractMacroAssembler.h:
(JSC::AbstractMacroAssembler::AbstractMacroAssembler):
(JSC::AbstractMacroAssembler::random):
cryptographicallyRandomNumber() is very costly.
We only need it in lowering some very particular cases
of non-trusted immediates. No inline cache needs that.
* assembler/LinkBuffer.h:
(JSC::LinkBuffer::link):
* jit/JIT.h:
* jit/JITInlines.h:
(JSC::JIT::addSlowCase):
Do not copy the JumpList to access its elements.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreassemblerAbstractMacroAssemblerh">trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.h</a></li>
<li><a href="#trunkSourceJavaScriptCoreassemblerLinkBufferh">trunk/Source/JavaScriptCore/assembler/LinkBuffer.h</a></li>
<li><a href="#trunkSourceJavaScriptCorejitJITh">trunk/Source/JavaScriptCore/jit/JIT.h</a></li>
<li><a href="#trunkSourceJavaScriptCorejitJITInlinesh">trunk/Source/JavaScriptCore/jit/JITInlines.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (199709 => 199710)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-04-19 06:33:05 UTC (rev 199709)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-04-19 06:54:25 UTC (rev 199710)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2016-04-18 Benjamin Poulain <bpoulain@apple.com>
+
+ [JSC] Fix some overhead affecting small codegen
+ https://bugs.webkit.org/show_bug.cgi?id=156728
+
+ Reviewed by Filip Pizlo.
+
+ * assembler/AbstractMacroAssembler.h:
+ (JSC::AbstractMacroAssembler::AbstractMacroAssembler):
+ (JSC::AbstractMacroAssembler::random):
+ cryptographicallyRandomNumber() is very costly.
+ We only need it in lowering some very particular cases
+ of non-trusted immediates. No inline cache needs that.
+
+ * assembler/LinkBuffer.h:
+ (JSC::LinkBuffer::link):
+ * jit/JIT.h:
+ * jit/JITInlines.h:
+ (JSC::JIT::addSlowCase):
+ Do not copy the JumpList to access its elements.
+
</ins><span class="cx"> 2016-04-18 Saam barati <sbarati@apple.com>
</span><span class="cx">
</span><span class="cx"> implement dynamic scope accesses in the DFG/FTL
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreassemblerAbstractMacroAssemblerh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.h (199709 => 199710)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.h 2016-04-19 06:33:05 UTC (rev 199709)
+++ trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.h 2016-04-19 06:54:25 UTC (rev 199710)
</span><span class="lines">@@ -711,8 +711,6 @@
</span><span class="cx"> // A JumpList is a set of Jump objects.
</span><span class="cx"> // All jumps in the set will be linked to the same destination.
</span><span class="cx"> class JumpList {
</span><del>- friend class LinkBuffer;
-
</del><span class="cx"> public:
</span><span class="cx"> typedef Vector<Jump, 2> JumpVector;
</span><span class="cx">
</span><span class="lines">@@ -1040,16 +1038,21 @@
</span><span class="cx">
</span><span class="cx"> protected:
</span><span class="cx"> AbstractMacroAssembler()
</span><del>- : m_randomSource(cryptographicallyRandomNumber())
</del><ins>+ : m_randomSource(0)
</ins><span class="cx"> {
</span><span class="cx"> invalidateAllTempRegisters();
</span><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> uint32_t random()
</span><span class="cx"> {
</span><ins>+ if (!m_randomSourceIsInitialized) {
+ m_randomSourceIsInitialized = true;
+ m_randomSource.setSeed(cryptographicallyRandomNumber());
+ }
</ins><span class="cx"> return m_randomSource.getUint32();
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ bool m_randomSourceIsInitialized { false };
</ins><span class="cx"> WeakRandom m_randomSource;
</span><span class="cx">
</span><span class="cx"> #if ENABLE(DFG_REGISTER_ALLOCATION_VALIDATION)
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreassemblerLinkBufferh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/assembler/LinkBuffer.h (199709 => 199710)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/assembler/LinkBuffer.h 2016-04-19 06:33:05 UTC (rev 199709)
+++ trunk/Source/JavaScriptCore/assembler/LinkBuffer.h 2016-04-19 06:54:25 UTC (rev 199710)
</span><span class="lines">@@ -144,10 +144,10 @@
</span><span class="cx"> MacroAssembler::linkJump(code(), jump, label);
</span><span class="cx"> }
</span><span class="cx">
</span><del>- void link(JumpList list, CodeLocationLabel label)
</del><ins>+ void link(const JumpList& list, CodeLocationLabel label)
</ins><span class="cx"> {
</span><del>- for (unsigned i = 0; i < list.m_jumps.size(); ++i)
- link(list.m_jumps[i], label);
</del><ins>+ for (const Jump& jump : list.jumps())
+ link(jump, label);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void patch(DataLabelPtr label, void* value)
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorejitJITh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/jit/JIT.h (199709 => 199710)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/jit/JIT.h 2016-04-19 06:33:05 UTC (rev 199709)
+++ trunk/Source/JavaScriptCore/jit/JIT.h 2016-04-19 06:54:25 UTC (rev 199710)
</span><span class="lines">@@ -307,7 +307,7 @@
</span><span class="cx"> void privateCompileExceptionHandlers();
</span><span class="cx">
</span><span class="cx"> void addSlowCase(Jump);
</span><del>- void addSlowCase(JumpList);
</del><ins>+ void addSlowCase(const JumpList&);
</ins><span class="cx"> void addSlowCase();
</span><span class="cx"> void addJump(Jump, int);
</span><span class="cx"> void emitJumpSlowToHot(Jump, int);
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorejitJITInlinesh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/jit/JITInlines.h (199709 => 199710)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/jit/JITInlines.h 2016-04-19 06:33:05 UTC (rev 199709)
+++ trunk/Source/JavaScriptCore/jit/JITInlines.h 2016-04-19 06:54:25 UTC (rev 199710)
</span><span class="lines">@@ -831,14 +831,12 @@
</span><span class="cx"> m_slowCases.append(SlowCaseEntry(jump, m_bytecodeOffset));
</span><span class="cx"> }
</span><span class="cx">
</span><del>-ALWAYS_INLINE void JIT::addSlowCase(JumpList jumpList)
</del><ins>+ALWAYS_INLINE void JIT::addSlowCase(const JumpList& jumpList)
</ins><span class="cx"> {
</span><span class="cx"> ASSERT(m_bytecodeOffset != std::numeric_limits<unsigned>::max()); // This method should only be called during hot/cold path generation, so that m_bytecodeOffset is set.
</span><span class="cx">
</span><del>- const JumpList::JumpVector& jumpVector = jumpList.jumps();
- size_t size = jumpVector.size();
- for (size_t i = 0; i < size; ++i)
- m_slowCases.append(SlowCaseEntry(jumpVector[i], m_bytecodeOffset));
</del><ins>+ for (const Jump& jump : jumpList.jumps())
+ m_slowCases.append(SlowCaseEntry(jump, m_bytecodeOffset));
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> ALWAYS_INLINE void JIT::addSlowCase()
</span></span></pre>
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