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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 - segmentation fault in libomptarget when using taskloop and target nowait"
href="https://bugs.llvm.org/show_bug.cgi?id=50002">50002</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>segmentation fault in libomptarget when using taskloop and target nowait
</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>Linux
</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>Runtime Library
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>xw111luoye@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>LIBOMP_USE_HIDDEN_HELPER_TASK=0 makes the reproducer to work. So there are some
correlations.
reproducer: clang++ -fopenmp -fopenmp-targets=nvptx64
taskloop_offload_nowait.cpp
#include <iostream>
#include <cstdlib>
#include <cmath>
bool almost_equal(float x, float gold, float tol) {
if ( std::signbit(x) != std::signbit(gold) )
{
x = std::abs(gold) - std::abs(x);
}
return std::abs(gold) * (1-tol) <= std::abs(x) && std::abs(x) <=
std::abs(gold) * (1 + tol);
}
int main()
{
const int N0 { 2 };
const int N1 { 182 };
const float expected_value { N0*N1 };
float counter_N0{};
#pragma omp target data map(tofrom: counter_N0)
{
#pragma omp taskloop shared(counter_N0)
for (int i0 = 0 ; i0 < N0 ; i0++ )
{
#pragma omp target teams distribute parallel for map(tofrom: counter_N0)
nowait
for (int i1 = 0 ; i1 < N1 ; i1++ )
{
#pragma omp atomic update
counter_N0 = counter_N0 + 1. ;
}
}
}
if (!almost_equal(counter_N0, expected_value, 0.1)) {
std::cerr << "Expected: " << expected_value << " Got: " << counter_N0 <<
std::endl;
std::exit(112);
}
}</pre>
</div>
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