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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [RegisterScavenger] Spills dead register."
href="https://bugs.llvm.org/show_bug.cgi?id=47801">47801</a>
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<th>Summary</th>
<td>[RegisterScavenger] Spills dead register.
</td>
</tr>
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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>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</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>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>paulsson@linux.vnet.ibm.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=24047" name="attach_24047" title="reduced testcase">attachment 24047</a> <a href="attachment.cgi?id=24047&action=edit" title="reduced testcase">[details]</a></span>
reduced testcase
llc -mtriple=s390x-linux-gnu -mcpu=z13 -O3 ./tc_regscav.ll
*** Bad machine code: Using an undefined physical register ***
- function:
- basic block: %bb.0 bb (0x2aa051adc30)
- instruction: STG killed $r6d, $r11d, 168, $noreg :: (store 8 into %stack.26)
- operand 0: killed $r6d
In the test case, register $r6D is killed early in the block by it's only user.
Later in that block, RegisterScavenger decides to use that register for a
virtual register created during Frame Lowering (scavengeFrameVirtualRegs()).
This seems to mean that the RegisterScavenger should actually not need to spill
the register, since it is not live.</pre>
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</p>
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