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<base href="http://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - __atomic_* builtins need to link -latomic with -rtlib=libgcc"
href="http://bugs.llvm.org/show_bug.cgi?id=31979">31979</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>__atomic_* builtins need to link -latomic with -rtlib=libgcc
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Driver
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mgorny@gentoo.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>While running libomp tests, I've noticed that some tests fail with undefined
references for 32-bit x86:
$ "/usr/lib/llvm/5/bin/i686-pc-linux-gnu-clang" "-fopenmp" "-I"
"/tmp/portage/sys-libs/libomp-9999/work/libomp-9999/runtime/test" "-I"
"/tmp/portage/sys-libs/libomp-9999/work/libomp-9999-abi_x86_32.x86/runtime/src"
"-L"
"/tmp/portage/sys-libs/libomp-9999/work/libomp-9999-abi_x86_32.x86/runtime/src"
"/tmp/portage/sys-libs/libomp-9999/work/libomp-9999/runtime/test/atomic/omp_atomic.c"
"-o"
"/tmp/portage/sys-libs/libomp-9999/work/libomp-9999-abi_x86_32.x86/runtime/test/atomic/Output/omp_atomic.c.tmp"
"-lm"
# command stderr:
/tmp/portage/sys-libs/libomp-9999/temp/omp_atomic-bc2a2f.o: In function
`.omp_outlined..4':
/tmp/portage/sys-libs/libomp-9999/work/libomp-9999/runtime/test/atomic/omp_atomic.c:(.text+0xe14):
undefined reference to `__atomic_load'
/tmp/portage/sys-libs/libomp-9999/temp/omp_atomic-bc2a2f.o: In function
`.omp_outlined..6':
/tmp/portage/sys-libs/libomp-9999/work/libomp-9999/runtime/test/atomic/omp_atomic.c:(.text+0x1044):
undefined reference to `__atomic_load'
/tmp/portage/sys-libs/libomp-9999/temp/omp_atomic-bc2a2f.o: In function
`.omp_outlined..12':
/tmp/portage/sys-libs/libomp-9999/work/libomp-9999/runtime/test/atomic/omp_atomic.c:(.text+0x154a):
undefined reference to `__atomic_load'
clang-5.0: error: linker command failed with exit code 1 (use -v to see
invocation)
error: command failed with exit status: 1
[this is using default -rtlib=libgcc]
After some investigation, it seems that when using -rtlib=libgcc, the __atomic*
functions are provided by libatomic rather than libgcc*. I'm not sure if we
should link it in unconditionally, or if we can do some heuristic to determine
if it should be linked in.
Furthermore, I don't know how many GCC versions actually supply the library.</pre>
</div>
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