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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -fno-zero-initialized-in-bss -fno-common and tentative definitions"
href="https://llvm.org/bugs/show_bug.cgi?id=31625">31625</a>
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<th>Summary</th>
<td>-fno-zero-initialized-in-bss -fno-common and tentative definitions
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<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>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Frontend
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hstong@ca.ibm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Clang's support for -fno-zero-initialized-in-bss does not match GCC's.
In particular, when using -fno-common, tentative definitions are still placed
by GCC into BSS.
Online compiler:
<a href="http://melpon.org/wandbox/permlink/76ugV7cPaxxqjIMl">http://melpon.org/wandbox/permlink/76ugV7cPaxxqjIMl</a>
### Source (<stdin>):
int x;
### Compiler invocation:
clang -c -o a.o -x c -fno-common -fno-zero-initialized-in-bss -
### Additional commands:
objdump -wt a.o | grep -P '\b''x\b'
### Expected output:
0000000000000000 g O .bss 0000000000000004 x
### Actual output:
0000000000000000 g O .data 0000000000000004 x
### clang -v:
clang version 4.0.0 (trunk 290110)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/llvm-head/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64</pre>
</div>
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