add m4 check for openacc flags and fix for intel

.github/workflows/main.yml

@@ -18,7 +18,7 @@ jobs:
         QUAD_P: ${{ matrix.enable_quad_precision }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
       with:
         submodules: recursive
     - name: Configure

configure.ac

@@ -87,9 +87,15 @@ AM_CONDITIONAL([WITH_MPI_TESTS], [test x"$build_mpi" = x"yes" -a -z "$SKIP_MPI_T
 
 #Build with OpenACC suport.  Default is 'no'
 AC_ARG_ENABLE([acc],
-  [AS_HELP_STRING([--enable-acc], [Build with OpenACC support.  Defaults to 'no'])] )
-AS_IF([test ${enable_acc:-no} = "yes"], [enable_acc=yes], [enable_acc=no])
-AM_CONDITIONAL([ENABLE_ACC], [test $enable_acc = "yes"])
+            [AS_HELP_STRING([--enable-acc],
+                            [Builds with OpenACC. This will result in a second executable for fregrid, fregrid_gpu.(default no)])])
+AS_IF([test ${enable_acc:-no} = yes],
+      [enable_acc=yes],
+      [enable_acc=no])
+# check compile flags
+AS_IF([test ${enable_acc} = yes],
+      [GX_OPENACC_FLAGS()])
+AM_CONDITIONAL([ENABLE_ACC], [test "$enable_acc" = "yes"])
 
 AC_CHECK_FUNCS(gettid, [], [])
 
@@ -123,7 +129,7 @@ AC_CHECK_PROGS(PROVE, [prove])
 AM_CONDITIONAL([WITH_CHECK_PROGS], [test -n "$PROVE" -a -n "$BATS"])
 
 # Check if openacc.h exists
-if test $enable_acc = yes ; then
+if test "$enable_acc" = yes ; then
    AC_CHECK_HEADERS([openacc.h], [], [AC_MSG_ERROR(["Cannot find OpenACC header file"])] )
    AC_MSG_WARN(Currently only NVIDIA compilers are supported to compile with OpenACC in FRE-NCTOOLS)
 fi

m4/gx_openacc_flags.m4

@@ -0,0 +1,74 @@
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   GX_OPENACC_FLAGS()
+#
+# DESCRIPTION
+#
+#  Checks C compiler flags for openacc support.
+#
+# LICENSE
+#
+#   Copyright (c) 2024 Ryan Mulhall
+#
+#   This program is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation; either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+
+# ----------------------------------------------------------------------
+#
+#  Will set OPENACC_CFLAGS to openacc flags for a given compiler if accepted.
+#
+#  Mainly for nvhpc, offloading with gcc is not currently supported,
+#  although the build will still work.
+#
+AC_DEFUN([GX_OPENACC_FLAGS],[
+AC_CACHE_CHECK([whether C compiler accepts OpenACC flags], [gx_cv_openacc_flags],[
+
+AC_LANG_ASSERT(C)
+gx_cv_openacc_flags=unknown
+gx_openacc_flags_CFLAGS_save=$CFLAGS
+
+dnl check for base openacc flag
+for ac_flag in '-acc' \
+               '-fopenacc'; do
+  AC_LINK_IFELSE([AC_LANG_SOURCE(
+          extern int acc_get_device_type();
+          int main(int argc, char** argv){
+              acc_get_device_type();
+              return 0;
+          })],
+     [gx_cv_openacc_flags="$gx_openacc_flags_CFLAGS_save ${ac_flag}"]; break)
+done
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+
+CFLAGS="$gx_openacc_flags_CFLAGS_save"
+
+if test "x$gx_cv_openacc_flags" = xunknown; then
+  m4_default([$2],
+              [AC_MSG_ERROR([no])])
+else
+  OPENACC_CFLAGS="${gx_cv_openacc_flags}"
+  AC_MSG_RESULT([yes])
+fi
+],
+AC_SUBST([OPENACC_CFLAGS])
+)])

tools/fregrid_acc/Makefile.am

@@ -21,7 +21,8 @@ bin_PROGRAMS = fregrid_acc
 
 AM_CFLAGS = -I$(top_srcdir)/tools/libfrencutils $(NETCDF_CFLAGS) \
             -I$(top_srcdir)/tools/libfrencutils_acc \
-            -I$(top_srcdir)/tools/fregrid -acc
+            -I$(top_srcdir)/tools/fregrid \
+            $(OPENACC_CFLAGS)
 LDADD = $(NETCDF_LDFLAGS) $(NETCDF_LIBS) $(RPATH_FLAGS)
 
 fregrid_acc_SOURCES = conserve_interp_acc.c \

tools/libfrencutils_acc/Makefile.am

@@ -19,7 +19,7 @@
 #***********************************************************************
 noinst_LIBRARIES = libfrencutils_acc.a
 
-AM_CFLAGS = $(NETCDF_CFLAGS) -I$(top_srcdir)/tools/libfrencutils -acc
+AM_CFLAGS = $(NETCDF_CFLAGS) $(OPENACC_CFLAGS) -I$(top_srcdir)/tools/libfrencutils
 
 libfrencutils_acc_a_SOURCES = create_xgrid_acc.c \
                               create_xgrid_acc.h

tools/mppncscatter/mppncscatter.c

@@ -44,6 +44,8 @@
 
 #define CHECK_NC_ERRSTAT(ierr) check_error(ierr,__FILE__,__LINE__)
 
+void check_error(int ierr, const char* file, int line);
+
 /*-------------------------------------------------------------------*/
 void printsizetarray(size_t *a, int n) {
   int i=0;