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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect data sharing analysis leads to kernel crash"
href="https://bugs.llvm.org/show_bug.cgi?id=52109">52109</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Incorrect data sharing analysis leads to kernel crash
</td>
</tr>
<tr>
<th>Product</th>
<td>OpenMP
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<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>Clang Compiler Support
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>xjin@anl.gov
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre><a href="https://godbolt.org/z/4o7fbPbYW">https://godbolt.org/z/4o7fbPbYW</a>
First, the compiler finds data sharing, which is incorrect. There's no sharing
of these stack variables.
example.cpp:820:62: remark: Found thread data sharing on the GPU. Expect
degraded performance due to data globalization. [OMP112]
[-Rpass-missed=openmp-opt]
ColorSpinor<typename Arg::realIn, Arg::nColor, Arg::nSpin> in =
arg.in(x_cb, (parity+arg.inParity)&1);
^
example.cpp:821:63: remark: Found thread data sharing on the GPU. Expect
degraded performance due to data globalization. [OMP112]
[-Rpass-missed=openmp-opt]
ColorSpinor<typename Arg::realOut, Arg::nColor, Arg::nSpin>
out;
^
example.cpp:665:8: remark: Found thread data sharing on the GPU. Expect
degraded performance due to data globalization. [OMP112]
[-Rpass-missed=openmp-opt]
real v[length];
^
example.cpp:682:8: remark: Found thread data sharing on the GPU. Expect
degraded performance due to data globalization. [OMP112]
[-Rpass-missed=openmp-opt]
real v[length];
^
Second, the generated code crashes in kernels, with
CUDA error: an illegal memory access was encountered
Close inspections (debug by commenting out code) show that some of the accesses
to the above variables caused the illegal memory access.</pre>
</div>
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