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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - option for light-weight poisoning of uninitialized variables"
href="http://llvm.org/bugs/show_bug.cgi?id=21176">21176</a>
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<th>Summary</th>
<td>option for light-weight poisoning of uninitialized variables
</td>
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Static Analyzer
</td>
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<th>Assignee</th>
<td>kremenek@apple.com
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<th>Reporter</th>
<td>jhi@iki.fi
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>Tru64 cc used to have a flag called -trapuv which initialized uninitialized
values with 0xfff58005 (repeated, so 64-bit value was 0xfff58005fff58005).
This was a handy value in that it was an illegal pointer value (for Alpha
architecture), and as a floating point value (float or double) it was a signal
NaN. So trying to deference the pointer value or use the fp value lead into a
quick failure (SEGV or FPE).
One cannot win always, of course, in that for integer values the value didn't
(and couldn't) cause a trap, but at least it was not zero, so there was some
change of people noticing that things aren't right.
Some poisoning like this would be a nice light-weight 'sanitizer'. The exact
values for the 'illegal address' and 'signaling nan' would depend on the
architecture.</pre>
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