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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - PowerPC inline assembly "=&r" constraint failing"
href="http://llvm.org/bugs/show_bug.cgi?id=21452">21452</a>
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<th>Summary</th>
<td>PowerPC inline assembly "=&r" constraint failing
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<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: PowerPC
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>anton@samba.org
</td>
</tr>
<tr>
<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=13272" name="attach_13272" title="Inline assembly testcase">attachment 13272</a> <a href="attachment.cgi?id=13272&action=edit" title="Inline assembly testcase">[details]</a></span>
Inline assembly testcase
The attached testcase built with -O2 -mcpu=power7 is buggy.
asm volatile(" lwsync\n"
"1: lwarx %0,0,%1 # atomic_dec_return\n"
" addic %0,%0,-1\n"
" stwcx. %0,0,%1\n"
" bne- 1b\n"
" sync\n"
:"=&r"(t)
:"r"(&v->counter)
:"cr0", "xer", "memory");
"=&r" should be enough to prevent t and v->counter ending up in the same
register, but it does:
1: lwarx 30,0,30 # atomic_dec_return
addic 30,30,-1
stwcx. 30,0,30</pre>
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