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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - TailDuplicate makes bad assumption about SSA form"
href="http://llvm.org/bugs/show_bug.cgi?id=17876">17876</a>
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<th>Summary</th>
<td>TailDuplicate makes bad assumption about SSA form
</td>
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<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>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>justin.holewinski@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</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=11508" name="attach_11508" title="Repro for TailDuplicate assert failure">attachment 11508</a> <a href="attachment.cgi?id=11508&action=edit" title="Repro for TailDuplicate assert failure">[details]</a></span>
Repro for TailDuplicate assert failure
During late machine code optimization with NVPTX, the following code in
TailDuplicate.cpp may be hit:
236├> MachineInstr *DefMI = MRI->getVRegDef(VReg);
MachineRegisterInfo::getVRegDef() assumes SSA form, but when running
TailDuplicate MRI->isSSA() is false.
For repro, the attached .ll file can be used with the nvptx target with the
following change to NVPTXTargetMachine.cpp:
1. Remove "disablePass(&TailDuplicateID);"
The TailDuplicate pass is currently disabled in NVPTX for a few reasons,
including this one.</pre>
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