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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Segfault in inferPrototypeAttributes"
href="https://llvm.org/bugs/show_bug.cgi?id=25556">25556</a>
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<tr>
<th>Summary</th>
<td>Segfault in inferPrototypeAttributes
</td>
</tr>
<tr>
<th>Product</th>
<td>tools
</td>
</tr>
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<th>Version</th>
<td>3.7
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>opt
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>peter@trailofbits.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>opt produces a NULL-pointer dereference when trying to infer the prototype of a
declaration of __isoc99_sscanf.
If __isoc99_sscanf is declared as having only a single argument then the
following code segfaults when trying to access the parameter type of param 1.
File: llvm/lib/Transforms/IPO/FunctionAttrs.cpp
Function: inferPrototypeAttributes
1714 case LibFunc::dunder_isoc99_sscanf:
1715 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy()
||
1716 !FTy->getParamType(1)->isPointerTy())
1717 return false;
I have ensured that my declaration of __isoc99_sscanf is attributed with
llvm::Attribute::NoBuiltin but this attribute appears to be ignored during this
inference phase. The only checked attribute is llvm::Attribute::OptimizeNone.</pre>
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