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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - missed dead code elimination, linker error"
href="http://llvm.org/bugs/show_bug.cgi?id=17882">17882</a>
</td>
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<th>Summary</th>
<td>missed dead code elimination, linker error
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.3
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>FreeBSD
</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>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>andreast@gcc.gnu.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The below test case fails to link with clang. gcc48 does work.
-----
extern void dead(void);
void test(int x)
{
if (x || 1)
return;
dead();
}
int main()
{
test(0);
return 0;
}
-----
When I change the if (x||1) to if(1||x) the compile/link succeeds.
Here the output of the failing test:
[tcx58:~] andreast% clang -o dead dead.c
/tmp/dead-hllbPY.o: In function `test':
dead.c:(.text+0x2d): undefined reference to `dead'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
The original code was discovered in qemu-trunk, the workaround is to change the
if condition.
The credit for the test case and the workaround goes to Paolo Bonzini.
I have tested this on FreeBSD -CURRENT:
[tcx58:~] andreast% clang -v
FreeBSD clang version 3.3 (tags/RELEASE_33/final 183502) 20130610
Target: x86_64-unknown-freebsd11.0
Thread model: posix</pre>
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