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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - BFI instruction with zero register decoded as bad BFC instruction"
href="https://llvm.org/bugs/show_bug.cgi?id=30611">30611</a>
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<tr>
<th>Summary</th>
<td>BFI instruction with zero register decoded as bad BFC instruction
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>3.8
</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>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: AArch64
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>njholcomb@wi.rr.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>Decoding an A64 base instruction with bytes: 0x331957fa should produce a bit
field insert of the zero register:
bfi w26, wzr, #7, #22
The current output is a BFC instruction (which already cannot be encoded in the
A64 base instruction):
bfc w26, #7, #22
This instruction is incorrect because the BFC instruction only supports 4 bits
of register name, meaning w26 is out of bounds as a register for this
instruction.</pre>
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</p>
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