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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - PowerPC64: CR spill code causes SEGV"
href="https://llvm.org/bugs/show_bug.cgi?id=26500">26500</a>
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<th>Summary</th>
<td>PowerPC64: CR spill code causes SEGV
</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>Linux
</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>Backend: PowerPC
</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>anton@samba.org
</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>I've seen a few SEGVs when running csmith. In all the cases I have looked at,
we've dereferenced what looks like a condition register value:
One example:
r3 0x42000042
=> 0x0000000010000bdc <+1516>: lhz r3,30996(r3)
What is interesting is that the CR spill gets scheduled quite a way into the
function, after we've used r12 for something else. Later on we reuse r12 (which
has now been contaminated with a CR).
Use r12:
10000734: ff ff 82 3d addis r12,r2,-1
Spill CR using r12 as scratch:
100007fc: 26 00 80 7d mfcr r12
1000080c: 08 00 81 91 stw r12,8(r1)
Use value in r12 later on:
10000914: a8 00 9f f9 std r12,168(r31)
10000bcc: a8 00 7f e8 ld r3,168(r31)
LLVM seems to use r12 unconditionally for CR spill, are we missing some sort of
r12 clobber?</pre>
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