Fix the C types for the following:
* MPI_UNWEIGHTED
* MPI_WEIGHTS_EMPTY
* MPI_ARGV_NULL
* MPI_ARGVS_NULL
* MPI_ERRCODES_IGNORE
There is lengthy discussion on
https://github.com/open-mpi/ompi/pull/7210 describing the issue; the
gist of it is that the C and Fortran types for several MPI global
sentenial values should agree (specifically: their sizes must(**)
agree). We erroneously had several of these array-like sentinel
values be "array-like" values in C. E.g., MPI_ERRCODES_IGNORE was an
(int *) in C while its corresponding Fortran type was "integer,
dimension(1)". On a 64 bit platform, this resulted in C expecting the
symbol size to be sizeof(int*)==8 while Fortran expected the symbol
size to be sizeof(INTEGER, DIMENSION(1))==4.
That is incorrect -- the corresponding C type needed to be (int).
Then both C and Fortran expect the size of the symbol to be the same.
(**) NOTE: This code has been wrong for years. This mismatch of types
typically worked because, due to Fortran's call-by-reference
semantics, Open MPI was comparing the *addresses* of these instances,
not their *types* (or sizes) -- so even if C expected the size of the
symbol to be X and Fortran expected the size of the symbol to be Y
(where X!=Y), all we really checked at run time was that the addresses
of the symbols were the same. But it caused linker warning messages,
and even caused errors in some cases.
Specifically: due to a GNU ld bug
(https://sourceware.org/bugzilla/show_bug.cgi?id=25236), the 5 common
symbols are incorrectly versioned VER_NDX_LOCAL because their
definitions in Fortran sources have smaller st_size than those in
libmpi.so.
This makes the Fortran library not linkable with lld in distributions
that ship openmpi built with -Wl,--version-script
(https://bugs.llvm.org/show_bug.cgi?id=43748):
% mpifort -fuse-ld=lld /dev/null
ld.lld: error: corrupt input file: version definition index 0 for symbol
mpi_fortran_argv_null_ is out of bounds
>>> defined in /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_usempif08.so
...
If we fix the C and Fortran symbols to actually be the same size, the
problem goes away and the GNU ld bug does not come into play.
This commit also fixes a minor issue that MPI_UNWEIGHTED and
MPI_WEIGHTS_EMPTY were not declared as Fortran arrays (not fully fixed
by commit 107c0073dd11fb90d18122c521686f692a32cdd8).
Fixesopen-mpi/ompi#7209
Signed-off-by: Fangrui Song <i@maskray.me>
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
Fortran constants `MPI_ARGV_NULL` and `MPI_ARGVS_NULL` are defined
in MPI-3.1 p.680 as below.
> `MPI_ARGVS_NULL`
> 2-dim. array of `CHARACTER*(*)`
> `MPI_ARGV_NULL`
> array of `CHARACTER*(*)`
`MPI_ARGV_NULL` and `MPI_ARGVS_NULL` are used as an argument of
`MPI_COMM_SPAWN` and `MPI_COMM_SPAWN_MULTIPLE` respectively and
their argument `argv` and `array_of_argv` are defined as below
for `USE mpi_f08` binding in MPI-3.1.
```
CHARACTER(LEN=*), INTENT(IN) :: argv(*)
CHARACTER(LEN=*), INTENT(IN) :: array_of_argv(count, *)
```
Defining them as `INTEGER` in `mpi_f08` module will cause
a compilation error of user programs like
"There is no specific subroutine for the generic 'mpi_comm_spawn'".
Signed-off-by: KAWASHIMA Takahiro <t-kawashima@jp.fujitsu.com>
Without this modification, gfortran throw the following error
if these variables are used for `MPI_DIST_GRAPH_CREATE_ADJACENT` or
`MPI_DIST_GRAPH_CREATE_ADJACENT`.
Error: There is no specific subroutine for the generic
'mpi_dist_graph_create_adjacent' at (1)
only define the unique fortran symbol depending on
- CAPS
- PLAIN
- SINGLE_UNDERSCORE
- DOUBLE_UNDERSCORE
and bind the f08 symbol to the uniquely defined C symbol.
Use real data structures to make the code simpler.
(perl script written by Jeff)
