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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW " title="NEW --- - Inconsistent order of x86 instruction prefixes with -via-file-asm" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23594&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=Au9S236R9tcyreLAxB1rDOhgRslfGOh-v_OxqBTWpYQ&s=j1rGLU5pQqmlHYTcelnQLBM9Olo4iYBlcK7kRQuFqVY&e=">23594</a>
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<th>Summary</th>
<td>Inconsistent order of x86 instruction prefixes with -via-file-asm
</td>
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<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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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>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>MC
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
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<th>Reporter</th>
<td>russell_gallop@sn.scee.net
</td>
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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>The order of x86 instruction prefixes is inconsistent if an asm file is written
out. Tested with revision 237107.
$ cat test.cpp
bool test() {
unsigned short val;
return __sync_bool_compare_and_swap_2(&val, 0, 0);
}
$ clang -c test.cpp && objdump -d test.o
test.o: file format elf64-x86-64
...
c: 66 f0 0f b1 4d fe lock cmpxchg %cx,-0x2(%rbp)
$ clang -via-file-asm -c test.cpp && objdump -d test.o
test.o: file format elf64-x86-64
...
c: f0 66 0f b1 4d fe lock cmpxchg %cx,-0x2(%rbp)</pre>
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</p>
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