<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - -fopenmp-simd incorrectly defines _OPENMP"
href="https://bugs.llvm.org/show_bug.cgi?id=37536">37536</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>-fopenmp-simd incorrectly defines _OPENMP
</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>Clang Compiler Support
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>steffen.seckler@tum.de
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>clang incorrectly defines _OPENMP if -fopenmp-simd is specified. This should
only happen if full openmp support is available:
this shows, whether _OPENMP has been defined, based on different parameters:
<span class="quote">> clang -fopenmp-simd -dM -E - < /dev/null | grep -i openmp </span >
#define _OPENMP 201511
(this should not be defined here)
<span class="quote">> clang -fno-openmp -fopenmp-simd -dM -E - < /dev/null | grep -i openmp </span >
#define _OPENMP 201511
(this should not be defined here)
<span class="quote">> clang -fopenmp -dM -E - < /dev/null | grep -i openmp </span >
#define _OPENMP 201107
(ok, should be defined)
<span class="quote">> clang -fopenmp-simd -fopenmp -dM -E - < /dev/null | grep -i openmp </span >
#define _OPENMP 201107
(ok, should be defined)
The openmp standard provides a reference style to check for openmp support,
that is checking for the definition of _OPENMP, e.g. example from openmp
standard (<a href="https://www.openmp.org/wp-content/uploads/openmp-4.5.pdf">https://www.openmp.org/wp-content/uploads/openmp-4.5.pdf</a>, page 35):
<span class="quote">> #ifdef _OPENMP
> iam = omp_get_thread_num() + &index
> #endif</span >
This simple example code breaks if -fopenmp-simd is defined and -fopenmp is
not.
build environment:
clang version: 6.0.1-svn331815-1~exp1~20180510082943.84
comparison with other compilers:
g++ 7.3.0:
<span class="quote">> g++ -fopenmp-simd -dD -E - < /dev/null | grep -i openmp</span >
(empty, _OPENMP not defined)
<span class="quote">> g++ -fopenmp-simd -fopenmp -dD -E - < /dev/null | grep -i openmp</span >
#define _OPENMP 201511
icpc 16.0.4:
<span class="quote">> icpc -dD -E -qopenmp-simd - </dev/null | grep -i openmp</span >
(empty, _OPENMP not defined)
<span class="quote">> icpc -dD -E -qopenmp -qopenmp-simd - </dev/null | grep -i openmp</span >
#define _OPENMP 201307
icpc 17.0.6:
<span class="quote">> icpc -dD -E -qopenmp-simd - </dev/null | grep -i openmp</span >
(empty, _OPENMP not defined)
<span class="quote">> icpc -dD -E -qopenmp -qopenmp-simd - </dev/null | grep -i openmp</span >
#define _OPENMP 201511
P.S: it also seems, that the defined openmp versions are quite erratic (201511
if openmp has not been defined, but openmp-simd has; 201107 if openmp has ALSO
been defined)</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>