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<title>[184414] trunk/Source/JavaScriptCore</title>
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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/184414">184414</a></dd>
<dt>Author</dt> <dd>benjamin@webkit.org</dd>
<dt>Date</dt> <dd>2015-05-15 14:10:11 -0700 (Fri, 15 May 2015)</dd>
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<h3>Log Message</h3>
<pre>[ARM64] Do not fail branchConvertDoubleToInt32 when the result is zero and not negative zero
https://bugs.webkit.org/show_bug.cgi?id=144976
Patch by Benjamin Poulain <bpoulain@apple.com> on 2015-05-15
Reviewed by Michael Saboff.
Failing the conversion on zero is pretty dangerous as we discovered on x86.
This patch does not really impact performance significantly because
<a href="http://trac.webkit.org/projects/webkit/changeset/184220">r184220</a> removed the zero checks from Kraken. This patch is just to be
on the safe side for cases not covered by existing benchmarks.
* assembler/MacroAssemblerARM64.h:
(JSC::MacroAssemblerARM64::branchConvertDoubleToInt32):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreassemblerMacroAssemblerARM64h">trunk/Source/JavaScriptCore/assembler/MacroAssemblerARM64.h</a></li>
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<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (184413 => 184414)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-05-15 20:48:21 UTC (rev 184413)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-05-15 21:10:11 UTC (rev 184414)
</span><span class="lines">@@ -1,3 +1,19 @@
</span><ins>+2015-05-15 Benjamin Poulain <bpoulain@apple.com>
+
+ [ARM64] Do not fail branchConvertDoubleToInt32 when the result is zero and not negative zero
+ https://bugs.webkit.org/show_bug.cgi?id=144976
+
+ Reviewed by Michael Saboff.
+
+ Failing the conversion on zero is pretty dangerous as we discovered on x86.
+
+ This patch does not really impact performance significantly because
+ r184220 removed the zero checks from Kraken. This patch is just to be
+ on the safe side for cases not covered by existing benchmarks.
+
+ * assembler/MacroAssemblerARM64.h:
+ (JSC::MacroAssemblerARM64::branchConvertDoubleToInt32):
+
</ins><span class="cx"> 2015-05-15 Sungmann Cho <sungmann.cho@navercorp.com>
</span><span class="cx">
</span><span class="cx"> Remove unnecessary forward declarations in PropertyNameArray.h.
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreassemblerMacroAssemblerARM64h"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/assembler/MacroAssemblerARM64.h (184413 => 184414)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/assembler/MacroAssemblerARM64.h 2015-05-15 20:48:21 UTC (rev 184413)
+++ trunk/Source/JavaScriptCore/assembler/MacroAssemblerARM64.h 2015-05-15 21:10:11 UTC (rev 184414)
</span><span class="lines">@@ -1213,9 +1213,14 @@
</span><span class="cx"> m_assembler.scvtf<64, 32>(fpTempRegister, dest);
</span><span class="cx"> failureCases.append(branchDouble(DoubleNotEqualOrUnordered, src, fpTempRegister));
</span><span class="cx">
</span><del>- // If the result is zero, it might have been -0.0, and the double comparison won't catch this!
- if (negZeroCheck)
- failureCases.append(branchTest32(Zero, dest));
</del><ins>+ // Test for negative zero.
+ if (negZeroCheck) {
+ Jump valueIsNonZero = branchTest32(NonZero, dest);
+ RegisterID scratch = getCachedMemoryTempRegisterIDAndInvalidate();
+ m_assembler.fmov<64>(scratch, src);
+ failureCases.append(makeTestBitAndBranch(scratch, 63, IsNonZero));
+ valueIsNonZero.link(this);
+ }
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> Jump branchDouble(DoubleCondition cond, FPRegisterID left, FPRegisterID right)
</span></span></pre>
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