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<base href="https://bugs.webkit.org/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Math.pow with Object arguments get deoptimized"
href="https://bugs.webkit.org/show_bug.cgi?id=157938">157938</a>
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<th>Summary</th>
<td>Math.pow with Object arguments get deoptimized
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
</tr>
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<th>Version</th>
<td>WebKit Nightly Build
</td>
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<th>Hardware</th>
<td>Unspecified
</td>
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<th>OS</th>
<td>Unspecified
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>Normal
</td>
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<th>Priority</th>
<td>P2
</td>
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<th>Component</th>
<td>JavaScriptCore
</td>
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>joepeck@webkit.org
</td>
</tr>
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<th>CC</th>
<td>benjamin@webkit.org, fpizlo@apple.com, ggaren@apple.com
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<pre>* SUMMARY
Math.pow with Object arguments get deoptimized.
It seems the DFG doesn't reason about converting Object -> numbers via valueOf() here.
* TEST
var sum = 0;
for (var i = 0; i < 1e5; ++i) {
sum += Math.pow(2, {valueOf() { return 3 }});
}
* NOTES
$ jsc test.js -p profile.json
$ display-profiler-output profile.json
CodeBlock #Instr Source Counts Machine Counts #Compil Inlines #Exits Last Opts Source
Base/DFG/FTL/FTLOSR Base/DFG/FTL/FTLOSR Src/Total Get/Put/Call
valueOf#BI9kVc 8 462/10073/89433/0 462/10073/89433/0 3 0/0 0 0/0/0 function () { return 3 }
<global>#D7oSjt 267 99506/20/0/0 99506/20/0/0 4 0/0 20 1/5/1 var sum = 0; for (var i = 0; i < 1e5; ++i) { sum +
<span class="quote">> log <global>#D7oSjt</span >
Compilation <global>#D7oSjt-1-Baseline:
Total count: 3283261 Max count: 99506
Compilation <global>#D7oSjt-2-DFG:
Total count: 120 Max count: 5
EXIT: at bc#186 due to Uncountable, 5 times
Jettisoned due to BaselineLoopReoptimizationTrigger
Compilation <global>#D7oSjt-3-DFG:
Total count: 240 Max count: 10
EXIT: at bc#186 due to Uncountable, 10 times
Jettisoned due to BaselineLoopReoptimizationTrigger
Compilation <global>#D7oSjt-4-DFG:
Total count: 120 Max count: 5
EXIT: at bc#186 due to Uncountable, 5 times
<span class="quote">> d <global>#D7oSjt-2-DFG</span >
...
5 99486/20/0/0 94:< 5:loc12> NewObject(JS|UseAsOther, Final, %DY:Object, R:HeapObjectCount, W:HeapObjectCount, Exits, bc#99)
...
5 99486/20/0/0 238:<!0:-> InvalidationPoint(MustGen, W:SideState, Exits, bc#177, exit: bc#186)
5 99506/20/0/0 233:< 1:loc14> DoubleConstant(Double|PureInt, Bytecodedouble, Double: 4611686018427387904, 2.000000, bc#186)
5 99506/20/0/0 157:< 2:loc12> ArithPow(DoubleRep:@233<Double>, Check:Int32:@94, Double|UseAsOther, Bytecodedouble, Exits, bc#186)
5 99506/20/0/0 0x510434202461: mov $0x4000000000000000, %rax
5 99506/20/0/0 0x51043420246b: movq %rax, %xmm0
5 99506/20/0/0 0x510434202470: jmp 0x510434202725
!!!!! !!!!! EXIT: due to Uncountable, 5 times</pre>
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