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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - crash in FlattenCFG: MergeIfRegion"
href="https://llvm.org/bugs/show_bug.cgi?id=31322">31322</a>
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<th>Summary</th>
<td>crash in FlattenCFG: MergeIfRegion
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</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>
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<th>Component</th>
<td>Backend: AMDGPU
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>pichet2000@gmail.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>Created <span class=""><a href="attachment.cgi?id=17742" name="attach_17742" title="reduced test case">attachment 17742</a> <a href="attachment.cgi?id=17742&action=edit" title="reduced test case">[details]</a></span>
reduced test case
FlattenCFG seem to be used only by AMDGPU.
I found this bug by using FlattenCFG pass for another out of tree target but I
can reproduce it with AMDGPU too.
Seem like MergeIfRegion is removing a BB still referenced by a PHI node.
reduction in test.ll
opt -flattencfg -disable-output test.ll
opt will crash</pre>
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