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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - APFloat does not correctly handle signaling NaN"
href="https://llvm.org/bugs/show_bug.cgi?id=30781">30781</a>
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<th>Summary</th>
<td>APFloat does not correctly handle signaling NaN
</td>
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<tr>
<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Support Libraries
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>dan@su-root.co.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>According to IEEE-754 2008 (7.2 Invalid operation) "any general-computational
or signaling-computational operation on a signaling NaN" should generate an
invalid operation exception and return a quiet NaN.
APFloat is supposed to be IEEE-754 2008 compliant but it does not handle this
part of the spec correctly. Currently if it performs an operation on a
signaling NaN it returns `APFloat::opOK` and a signaling NaN. Instead it should
return `APFloat::opInvalidOp` and a quiet NaN.
It appears this limitation is known about because in
`unittests/ADT/APFloatTest.cpp` there is this comment
```
// TODOS/NOTES:
// 1. Since we perform only default exception handling all operations with
// signaling NaNs should have a result that is a quiet NaN. Currently they
// return sNaN.
```
I couldn't find an open bug specifically for this issue so I'm opening this
one.</pre>
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