mpiext/shortfloat: Add MPIX_C_FLOAT16 datatype

`MPIX_C_FLOAT16` is defined as a synonym for `MPIX_SHORT_FLOAT`
if the C compiler supports `_Float16`, which is defined in
ISO/IEC JTC 1/SC 22/WG 14 N1945 (ISO/IEC TS 18661-3:2015).
This name and meaning are same as that of MPICH. This may be
a transitional datatype until the MPI Forum decides a proper
name for the type.

Signed-off-by: KAWASHIMA Takahiro <t-kawashima@jp.fujitsu.com>

ompi/mpi/fortran/common_sym_whitelist.txt

@@ -14,6 +14,7 @@ ompi_f08_mpi_byte
 ompi_f08_mpi_c_bool
 ompi_f08_mpi_c_complex
 ompi_f08_mpi_c_double_complex
+ompi_f08_mpi_c_float16
 ompi_f08_mpi_c_float_complex
 ompi_f08_mpi_c_long_double_complex
 ompi_f08_mpi_c_short_float_complex

ompi/mpi/fortran/use-mpi-f08/constants.c

@@ -153,9 +153,11 @@ OMPI_DECLSPEC ompi_fortran_08_handle_t OMPI_F08_HANDLE_ALIGNED ompi_f08_mpi_comp
  * OMPI_MPI_* macros are not defined in ompi/include/mpif-values.pl
  * because they should not be included in mpif.h. So immediate values
  * defined in ompi/datatype/ompi_datatype_module.c are used here.
+ * ompi_f08_mpi_c_float16 is a synonym for ompi_f08_mpi_short_float.
  */
 #if defined(HAVE_SHORT_FLOAT) || defined(HAVE_OPAL_SHORT_FLOAT_T)
 OMPI_DECLSPEC ompi_fortran_08_handle_t OMPI_F08_HANDLE_ALIGNED ompi_f08_mpi_short_float       = {74};
 OMPI_DECLSPEC ompi_fortran_08_handle_t OMPI_F08_HANDLE_ALIGNED ompi_f08_mpi_c_short_float_complex = {75};
 OMPI_DECLSPEC ompi_fortran_08_handle_t OMPI_F08_HANDLE_ALIGNED ompi_f08_mpi_cxx_short_float_complex = {76};
+OMPI_DECLSPEC ompi_fortran_08_handle_t OMPI_F08_HANDLE_ALIGNED ompi_f08_mpi_c_float16         = {74};
 #endif

ompi/mpiext/shortfloat/README.txt

@@ -13,6 +13,13 @@ Each MPI datatype corresponds to the C/C++ type 'short float', the C type
 'short float _Complex', and the C++ type 'std::complex<short float>',
 respectively.
 
+In addition, this extension provides a datatype MPIX_C_FLOAT16 for
+the C type _Float16, which is defined in ISO/IEC JTC 1/SC 22/WG 14
+N1945 (ISO/IEC TS 18661-3:2015). This name and meaning are same as
+that of MPICH.
+
+  https://github.com/pmodels/mpich/pull/3455
+
 This extension is enabled only if the C compiler supports 'short float'
 or '_Float16', or the '--enable-alt-short-float=TYPE' option is passed
 to the configure script.

ompi/mpiext/shortfloat/c/mpiext_shortfloat_c.h.in

@@ -15,3 +15,7 @@ OMPI_DECLSPEC extern struct ompi_predefined_datatype_t ompi_mpi_cxx_sfltcplex;
 #define MPIX_SHORT_FLOAT             OMPI_PREDEFINED_GLOBAL(MPI_Datatype, ompi_mpi_short_float)
 #define MPIX_C_SHORT_FLOAT_COMPLEX   OMPI_PREDEFINED_GLOBAL(MPI_Datatype, ompi_mpi_c_short_float_complex)
 #define MPIX_CXX_SHORT_FLOAT_COMPLEX OMPI_PREDEFINED_GLOBAL(MPI_Datatype, ompi_mpi_cxx_sfltcplex)
+
+#if @OMPI_MPIX_SHORT_FLOAT_IS_C_FLOAT16@
+#define MPIX_C_FLOAT16               OMPI_PREDEFINED_GLOBAL(MPI_Datatype, ompi_mpi_short_float)
+#endif

ompi/mpiext/shortfloat/configure.m4

@@ -17,6 +17,9 @@ AC_DEFUN([OMPI_MPIEXT_shortfloat_CONFIG],[
         ompi/mpiext/shortfloat/mpif-h/Makefile
         ompi/mpiext/shortfloat/use-mpi/Makefile
         ompi/mpiext/shortfloat/use-mpi-f08/Makefile
+        ompi/mpiext/shortfloat/c/mpiext_shortfloat_c.h
+        ompi/mpiext/shortfloat/mpif-h/mpiext_shortfloat_mpifh.h
+        ompi/mpiext/shortfloat/use-mpi-f08/mpiext_shortfloat_usempif08.h
     ])
 
     AS_IF([{ test "$ENABLE_shortfloat" = "1" || \
@@ -25,6 +28,12 @@ AC_DEFUN([OMPI_MPIEXT_shortfloat_CONFIG],[
              test "$ac_cv_type_opal_short_float_t" = "yes"; }],
           [$1],
           [$2])
+
+    AS_IF([test "$opal_short_float_type" = "_Float16"],
+          [AC_SUBST([OMPI_MPIX_SHORT_FLOAT_IS_C_FLOAT16], 1)
+           AC_SUBST([OMPI_MPIX_C_FLOAT16_FORTRAN_COMMENT_OUT], [])],
+          [AC_SUBST([OMPI_MPIX_SHORT_FLOAT_IS_C_FLOAT16], 0),
+           AC_SUBST([OMPI_MPIX_C_FLOAT16_FORTRAN_COMMENT_OUT], [!])])
 ])
 
 # The mpi_f08_ext module should not include mpiext_shortfloat_mpifh.h

ompi/mpiext/shortfloat/mpif-h/mpiext_shortfloat_mpifh.h.in

@@ -11,7 +11,9 @@
         integer MPIX_SHORT_FLOAT
         integer MPIX_C_SHORT_FLOAT_COMPLEX
         integer MPIX_CXX_SHORT_FLOAT_COMPLEX
+@OMPI_MPIX_C_FLOAT16_FORTRAN_COMMENT_OUT@        integer MPIX_C_FLOAT16
 
         parameter (MPIX_SHORT_FLOAT=74)
         parameter (MPIX_C_SHORT_FLOAT_COMPLEX=75)
         parameter (MPIX_CXX_SHORT_FLOAT_COMPLEX=76)
+@OMPI_MPIX_C_FLOAT16_FORTRAN_COMMENT_OUT@        parameter (MPIX_C_FLOAT16=74)

ompi/mpiext/shortfloat/use-mpi-f08/mpiext_shortfloat_usempif08.h.in

@@ -14,3 +14,7 @@
 type(MPI_Datatype), bind(C, name="ompi_f08_mpi_short_float") OMPI_PROTECTED :: MPIX_SHORT_FLOAT
 type(MPI_Datatype), bind(C, name="ompi_f08_mpi_c_short_float_complex") OMPI_PROTECTED :: MPIX_C_SHORT_FLOAT_COMPLEX
 type(MPI_Datatype), bind(C, name="ompi_f08_mpi_cxx_short_float_complex") OMPI_PROTECTED :: MPIX_CXX_SHORT_FLOAT_COMPLEX
+
+#if @OMPI_MPIX_SHORT_FLOAT_IS_C_FLOAT16@
+type(MPI_Datatype), bind(C, name="ompi_f08_mpi_c_float16") OMPI_PROTECTED :: MPIX_C_FLOAT16
+#endif