Hi,
AC_OPENMP returns "none needed" for the IBM xl Fortran compilers (xlf*,
bgxlf*, mpixlf*). This is wrong, you need to use -qsmp=omp.
configure tries to compile following program:
| program main
| call omp_get_num_threads
| end
Compilation succeeds without specifying any OpenMP flag. If you modify
the test program to
program main
implicit none
!$ integer tid
tid = 42
call omp_set_num_threads(2)
end
the correct flags are detected. See the attached patch where I also
added OpenMP flags for the Cray and NEC compilers. If you are happy with
this patch, please add Markus Geimer to THANKS, too.
BTW, the pgf* compilers also return "none needed", this patch might
solve this problem, too (untested).
Cheers,
Christian
diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4
index 871e1c9..89e6b49 100644
--- a/lib/autoconf/c.m4
+++ b/lib/autoconf/c.m4
@@ -1957,7 +1957,14 @@ m4_copy([_AC_LANG_OPENMP(C)], [_AC_LANG_OPENMP(C++)])
# _AC_LANG_OPENMP(Fortran 77)
# ---------------------------
m4_define([_AC_LANG_OPENMP(Fortran 77)],
-[AC_LANG_FUNC_LINK_TRY([omp_get_num_threads])])
+[
+ program main
+ implicit none
+!$ integer tid
+ tid = 42
+ call omp_set_num_threads(2)
+ end
+])
# _AC_LANG_OPENMP(Fortran)
# ------------------------
@@ -1992,12 +1999,14 @@ AC_DEFUN([AC_OPENMP],
dnl SGI C, PGI C -mp
dnl Tru64 Compaq C -omp
dnl IBM C (AIX, Linux) -qsmp=omp
+ dnl Cray CCE -homp
+ dnl NEC SX -Popenmp
dnl If in this loop a compiler is passed an option that it doesn't
dnl understand or that it misinterprets, the AC_LINK_IFELSE test
dnl will fail (since we know that it failed without the option),
dnl therefore the loop will continue searching for an option, and
dnl no output file called 'penmp' or 'mp' is created.
- for ac_option in -fopenmp -xopenmp -openmp -mp -omp -qsmp=omp; do
+ for ac_option in -fopenmp -xopenmp -openmp -mp -omp -qsmp=omp -homp -Popenmp; do
ac_save_[]_AC_LANG_PREFIX[]FLAGS=$[]_AC_LANG_PREFIX[]FLAGS
_AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $ac_option"
AC_LINK_IFELSE([_AC_LANG_OPENMP],
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