[mpich-commits] [mpich] MPICH primary repository branch, master, updated. v3.0.2-15-g0a452a2
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http://git.mpich.org/mpich.git/commitdiff/0a452a24cf55b8a648965ca1f5a504955880c354
commit 0a452a24cf55b8a648965ca1f5a504955880c354
Author: William Gropp <wgropp at illinois.edu>
Date: Wed Feb 6 07:31:15 2013 -0600
Added support for passing the length of a Fortran CHARACTER as size_t instead of int. Added a configure option to set; note that despite documentation to the contrary, it looks like some compilers still pass the length as an int (the common practice for decades), so changing to size_t must be made with extreme caution
diff --git a/configure.ac b/configure.ac
index f17eb74..e3cd063 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1882,6 +1882,66 @@ information to configure with the FCFLAGS environment variable.])
AC_DEFINE(HAVE_MPI_F_INIT_WORKS_WITH_C,1,[Define if the Fortran init code for MPI works from C programs without special libraries])
fi
+ #
+ # Some Fortran compilers now pass CHARACTER length as a size_t instead
+ # of as an int. This is hard to test for, since the data is passed by
+ # value and for characters less than about 2GB long, the correct
+ # value will be used. In this case, we must use an approach similar to
+ # the one used by libtool for shared library options - look at the
+ # compiler name or vendor.
+ # Known compilers that use size_t instead of int:
+ # Intel Fortran
+ # gfortran
+ # Add others as they become known
+ AC_ARG_ENABLE(f77characterlen,
+ AC_HELP_STRING([--enable-f77characterlen],
+ [Select between int and size_t for the length of a Fortran CHARACTER, depending on the F77 compiler. If --enable-f77characterlen=size_t is given, force the use of size_t. This is used for passing Fortran CHARACTER data between C and Fortran, and is provided for experts. Note that the documentation provided by compiler vendors on the calling convention may not be accurate.]),,enable_f77characterlen=no)
+
+ # Set the default
+ f77_uses_int_for_str=default
+
+ case "$enable_f77characterlen" in
+ yes|no)
+ ;;
+ size_t)
+ f77_uses_int_for_str=no
+ enable_f77characterlen=yes
+ ;;
+ int)
+ f77_uses_int_for_str=yes
+ enable_f77characterlen=yes
+ ;;
+ *)
+ AC_MSG_ERROR([Invalid value provided for --enable-f77characterlen])
+ ;;
+ esac
+
+ # If we might change the size (enable) and we haven't set the choice,
+ # attempt to determine it from the compiler name. Risky, but we haven't
+ # found a reliable way to do this with test codes.
+ if test "$enable_f77characterlen" = "yes" -a \
+ "$f77_uses_int_for_str" = "default" ; then
+ f77_uses_int_for_str=yes
+ f77Basename=`basename $F77`
+ case $f77Basename in
+ ifort*)
+ f77_uses_int_for_str=no
+ ;;
+ gfortran*)
+ f77_uses_int_for_str=no
+ ;;
+ esac
+ fi
+ # This test is disabled for now. Despite information in documentation
+ # on gfortran, it appears to pass lengths as int, at least in some
+ # builds (it used movl when tested in 2/2013). Tests that failed
+ # included infotestf.f, in a call to mpi_info_get.
+ # Leave this as a place holder until a proper test can be determined.
+ if test "$enable_f77characterlen" = "yes" -a \
+ "$f77_uses_int_for_str" = "no" ; then
+ AC_DEFINE(USE_FORT_STR_LEN_SIZET,1,[Define if the length of a CHARACTER*(*) string in Fortran should be passed as size_t instead of int] )
+ fi
+
fi
# FC requires F77 as well. If the user disabled f77, do not run the
diff --git a/src/binding/f77/mpi_fortimpl.h b/src/binding/f77/mpi_fortimpl.h
index f8eb11f..0adfa11 100644
--- a/src/binding/f77/mpi_fortimpl.h
+++ b/src/binding/f77/mpi_fortimpl.h
@@ -22,16 +22,35 @@
* an MPI_Fint instead of an int. In that case, we will need an additional
* case.
*/
+/*
+ * Many Fortran compilers at some point changed from passing the length of
+ * a CHARACTER*(N) in an int to using a size_t. This definition allows
+ * us to select either size_t or int. Determining which one the compiler
+ * is using may require reading the documentation or examining the generated
+ * code.
+ *
+ * The default is left as "int" because that is the correct legacy choice.
+ * Configure may need to check the compiler vendor and version to decide
+ * whether to select size_t. And despite documentation to the contrary,
+ * in our experiments, gfortran used int instead of size_t, which was
+ * verified by inspecting the assembly code.
+ */
+#ifdef USE_FORT_STR_LEN_SIZET
+#define FORT_SIZE_INT size_t
+#else
+#define FORT_SIZE_INT int
+#endif
+
#ifdef USE_FORT_MIXED_STR_LEN
-#define FORT_MIXED_LEN_DECL , int
+#define FORT_MIXED_LEN_DECL , FORT_SIZE_INT
#define FORT_END_LEN_DECL
-#define FORT_MIXED_LEN(a) , int a
+#define FORT_MIXED_LEN(a) , FORT_SIZE_INT a
#define FORT_END_LEN(a)
#else
#define FORT_MIXED_LEN_DECL
-#define FORT_END_LEN_DECL , int
+#define FORT_END_LEN_DECL , FORT_SIZE_INT
#define FORT_MIXED_LEN(a)
-#define FORT_END_LEN(a) , int a
+#define FORT_END_LEN(a) , FORT_SIZE_INT a
#endif
/* ------------------------------------------------------------------------- */
-----------------------------------------------------------------------
Summary of changes:
configure.ac | 60 ++++++++++++++++++++++++++++++++++++++++
src/binding/f77/mpi_fortimpl.h | 27 +++++++++++++++--
2 files changed, 83 insertions(+), 4 deletions(-)
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