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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - CFI ICall metadata is generated incorrectly for functions with void parameter"
href="https://llvm.org/bugs/show_bug.cgi?id=28185">28185</a>
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<th>Summary</th>
<td>CFI ICall metadata is generated incorrectly for functions with void parameter
</td>
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<th>Product</th>
<td>clang
</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>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>d.c.ddcc@gmail.com
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>When compiling the attached testcase with CFI ICall enabled, the metadata that
is generated is incorrect: the callsite has metadata "_ZTSFivE", and the
potential call target has metadata "_ZTSFiE". As a result, the LowerBitSets
pass in LLVM does not realize that this is a potential valid call target. But,
according to both the C and C++ specifications, functions with a single void
parameter are equivalent to the same function with an empty parameter list.
Unfortunately, I am not familiar enough with the Clang front-end to track down
the source of the bug. However, the key difference is that when
"CreateMetadataIdentifierForType(QualType(FnType, 0))" is called in
"CodeGenFunction::EmitCall()", in one instance the "FnType" variable is of type
"FunctionProtoType", whereas in the other instance it is of type
"FunctionNoProtoType". Then, when the Itanium name mangler is called at
"CXXNameMangler::mangleType()", the mangled name is represented differently.</pre>
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