1 # ===========================================================================
2 # https://www.gnu.org/software/autoconf-archive/ax_openmp.html
3 # ===========================================================================
7 # AX_OPENMP([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
11 # This macro tries to find out how to compile programs that use OpenMP a
12 # standard API and set of compiler directives for parallel programming
13 # (see http://www-unix.mcs/)
15 # On success, it sets the OPENMP_CFLAGS/OPENMP_CXXFLAGS/OPENMP_F77FLAGS
16 # output variable to the flag (e.g. -omp) used both to compile *and* link
17 # OpenMP programs in the current language.
19 # NOTE: You are assumed to not only compile your program with these flags,
20 # but also link it with them as well.
22 # If you want to compile everything with OpenMP, you should set:
24 # CFLAGS="$CFLAGS $OPENMP_CFLAGS"
25 # #OR# CXXFLAGS="$CXXFLAGS $OPENMP_CXXFLAGS"
26 # #OR# FFLAGS="$FFLAGS $OPENMP_FFLAGS"
28 # (depending on the selected language).
30 # The user can override the default choice by setting the corresponding
31 # environment variable (e.g. OPENMP_CFLAGS).
33 # ACTION-IF-FOUND is a list of shell commands to run if an OpenMP flag is
34 # found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it is
35 # not found. If ACTION-IF-FOUND is not specified, the default action will
40 # Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
41 # Copyright (c) 2015 John W. Peterson <jwpeterson@gmail.com>
42 # Copyright (c) 2016 Nick R. Papior <nickpapior@gmail.com>
44 # This program is free software: you can redistribute it and/or modify it
45 # under the terms of the GNU General Public License as published by the
46 # Free Software Foundation, either version 3 of the License, or (at your
47 # option) any later version.
49 # This program is distributed in the hope that it will be useful, but
50 # WITHOUT ANY WARRANTY; without even the implied warranty of
51 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
52 # Public License for more details.
54 # You should have received a copy of the GNU General Public License along
55 # with this program. If not, see <https://www.gnu.org/licenses/>.
57 # As a special exception, the respective Autoconf Macro's copyright owner
58 # gives unlimited permission to copy, distribute and modify the configure
59 # scripts that are the output of Autoconf when processing the Macro. You
60 # need not follow the terms of the GNU General Public License when using
61 # or distributing such scripts, even though portions of the text of the
62 # Macro appear in them. The GNU General Public License (GPL) does govern
63 # all other use of the material that constitutes the Autoconf Macro.
65 # This special exception to the GPL applies to versions of the Autoconf
66 # Macro released by the Autoconf Archive. When you make and distribute a
67 # modified version of the Autoconf Macro, you may extend this special
68 # exception to the GPL to apply to your modified version as well.
72 AC_DEFUN([AX_OPENMP], [
73 AC_PREREQ([2.69]) dnl for _AC_LANG_PREFIX
75 AC_CACHE_CHECK([for OpenMP flag of _AC_LANG compiler], ax_cv_[]_AC_LANG_ABBREV[]_openmp, [save[]_AC_LANG_PREFIX[]FLAGS=$[]_AC_LANG_PREFIX[]FLAGS
76 ax_cv_[]_AC_LANG_ABBREV[]_openmp=unknown
77 # Flags to try: -fopenmp (gcc), -mp (SGI & PGI),
78 # -qopenmp (icc>=15), -openmp (icc),
79 # -xopenmp (Sun), -omp (Tru64),
82 ax_openmp_flags="-fopenmp -openmp -qopenmp -mp -xopenmp -omp -qsmp=omp none"
83 if test "x$OPENMP_[]_AC_LANG_PREFIX[]FLAGS" != x; then
84 ax_openmp_flags="$OPENMP_[]_AC_LANG_PREFIX[]FLAGS $ax_openmp_flags"
86 for ax_openmp_flag in $ax_openmp_flags; do
87 case $ax_openmp_flag in
88 none) []_AC_LANG_PREFIX[]FLAGS=$save[]_AC_LANG_PREFIX[] ;;
89 *) []_AC_LANG_PREFIX[]FLAGS="$save[]_AC_LANG_PREFIX[]FLAGS $ax_openmp_flag" ;;
91 AC_LINK_IFELSE([AC_LANG_SOURCE([[
95 parallel_fill(int * data, int n)
98 @%:@pragma omp parallel for
99 for (i = 0; i < n; ++i)
107 omp_set_num_threads(2);
108 parallel_fill(arr, 100000);
111 ]])],[ax_cv_[]_AC_LANG_ABBREV[]_openmp=$ax_openmp_flag; break],[])
113 []_AC_LANG_PREFIX[]FLAGS=$save[]_AC_LANG_PREFIX[]FLAGS
115 if test "x$ax_cv_[]_AC_LANG_ABBREV[]_openmp" = "xunknown"; then
118 if test "x$ax_cv_[]_AC_LANG_ABBREV[]_openmp" != "xnone"; then
119 OPENMP_[]_AC_LANG_PREFIX[]FLAGS=$ax_cv_[]_AC_LANG_ABBREV[]_openmp
121 m4_default([$1], [AC_DEFINE(HAVE_OPENMP,1,[Define if OpenMP is enabled])])