Re: Buggy ssereg float function return on amd64

[Tobias Burnus <burnus at net-b dot de>]

Hi Kevin,

Kevin B. McCarty wrote:
> you wrote (sort of as an aside to the main point
>> I start with a comment to:
>> http://wiki.debian.org/GfortranTransition
>> "getarg and some other g77 specific functions have been removed from
>> gfortran."
>>
>> This is not the case. See:
>> http://gcc.gnu.org/onlinedocs/gfortran/GETARG.html
>>
>> My guess would be that the program contained an
>>    EXTERNAL GETARG
>> which instructs gfortran to regard GETARG a user-supplied function.
>> Simply removing the EXTERNAL line or using
>>    INTRINSIC GETARG
>> should work.
>>     
>
> Actually, the case in which this is a significant issue is *C or C++*
> code trying to call FORTRAN's GETARG.  Since libgfortran now has several
> versions of getarg (the symbols in the library are named things like
> _gfortran_getarg_i4), it is no longer possible for C/C++ code to access
> that function via the old usual method of adding an underscore to the
> FORTRAN function name, i.e. getarg_().
>
> Is it not possible to include a default version of getarg_ in
> libgfortran that is just an alias to _gfortran_getarg_i4 ?  There might
> be similar issues for other libgfortran functions, I don't personally know.
>   

The problem with having "xxx_" symbols in the libgfortran file is that
this potentially clashes with user functions such as especially for
"gamma_" vs. _gfortran_gamma*.

Besides, I still do not quite understand why it should be needed. If I
understood the problem correctly, only MPICH is affected. Why do you not
use a patch like the attached one, which seems to work for other
vendors. Or do I miss something else? (I do not know MPICH that well, I
use OpenMPI.)

Tobias

PS: Attached patch comes from mpich-1.2.7p1-125.src.rpm of openSUSE Factory.
ftp://ftp.gwdg.de/pub/opensuse/distribution/SL-OSS-factory/inst-source/suse/src/mpich-1.2.7p1-125.src.rpm

In the SPEC file one finds:
%if %{gnu}
    %define c_compiler gcc
    %define compiler_path /usr/bin
    %define setenvs export FC=gfortran; export F77_GETARGDECL="intrinsic
GETARG"
    %define fopts %{nil}
    %define extralibs %{nil}
    %define extraldopts %{nil}
%endif

--- mpe/aclocal_f77.m4.orig	2006-01-24 13:09:59.000000000 +0100
+++ mpe/aclocal_f77.m4	2006-01-24 14:08:55.000000000 +0100
@@ -348,10 +348,10 @@
 dnl will catch most systems and will speed up the tests.
 dnl
 dnl Next, the libraries are only added if they are needed to complete a 
-dnl link; they aren't added just because they exist.
+dnl link; they aren''t added just because they exist.
 dnl
 dnl f77argdef
-dnlD*/
+dnl D*/
 dnl
 dnl Random notes
 dnl You can export the command line arguments from C to the g77 compiler
@@ -396,9 +396,10 @@
     if test -z "$ac_fcompilelink" ; then
         ac_fcompilelink="${F77-f77} -o conftest $FFLAGS $flags conftest.f $LDFLAGS $LIBS 1>&AC_FD_CC"
     fi
-    AC_MSG_CHECKING([if ${F77-f77} $flags $libs works with GETARG and IARGC])
+    AC_MSG_CHECKING([whether ${F77-f77} $flags $libs works with GETARG and IARGC])
     if AC_TRY_EVAL(ac_fcompilelink) && test -x conftest ; then
-	if test "$ac_cv_prog_f77_cross" = "no" ; then
+	# Check that cross != yes so that this works with autoconf 2.52
+	if test "$ac_cv_prog_f77_cross" != "yes" ; then
 	    if ./conftest >/dev/null 2>&1 ; then
 		found_answer="yes"
 	        FXX_MODULE="$fxx_module"
@@ -492,7 +493,7 @@
 +U77"
     fi
     # Discard options that are not available:
-    save_IFS="$IFS"
+    # (IFS already saved above)
     IFS=" 
 "
     save_trial_FLAGS="$trial_FLAGS"
@@ -518,7 +519,7 @@
         end
 EOF
 	    if test -n "$fflag" ; then flagval="with $fflag" ; else flagval="" ; fi
-	    AC_MSG_CHECKING([that Fortran 77 routine names are case-insensitive $flagval])
+	    AC_MSG_CHECKING([whether Fortran 77 routine names are case-insensitive $flagval])
 	    dnl we can use double quotes here because all is already
             dnl evaluated
             ac_fcompilelink_test="${F77-f77} -o conftest $fflag $FFLAGS conftest.f $LDFLAGS $LIBS 1>&AC_FD_CC"
@@ -594,6 +595,13 @@
 		continue
 	   fi
 	   ;;
+	7) # gfortran won't find getarg if it is marked as external 
+	   FXX_MODULE=""
+	   F77_GETARGDECL="intrinsic GETARG"
+	   F77_GETARG="call GETARG(i,s)"
+	   F77_IARGC="IARGC()"
+	   MSG="intrinsic GETARG and IARGC"
+	   ;;
         *) # exit from while loop
 	   FXX_MODULE=""
 	   F77_GETARGDECL=""
@@ -631,13 +639,13 @@
 	    if test "$libs" = " " -o "$libs" = "0" ; then libs="" ; fi
             for flags in $trial_FLAGS ; do
 	        if test "$flags" = " " -o "$flags" = "000"; then flags="" ; fi
-                AC_MSG_CHECKING([if ${F77-f77} $flags $libs works with $MSG])
+                AC_MSG_CHECKING([whether ${F77-f77} $flags $libs works with $MSG])
 		IFS="$save_IFS"
 		dnl We need this here because we've fiddled with IFS
 	        ac_fcompilelink_test="${F77-f77} -o conftest $FFLAGS $flags conftest.f $LDFLAGS $libs $LIBS 1>&AC_FD_CC"
 		found_answer="no"
                 if AC_TRY_EVAL(ac_fcompilelink_test) && test -x conftest ; then
-		    if test "$ac_cv_prog_f77_cross" = "no" ; then
+		    if test "$ac_cv_prog_f77_cross" != "yes" ; then
 			if ./conftest >/dev/null 2>&1 ; then
 			    found_answer="yes"
 			fi