[Bug fortran/17987] New: multidimensional array problem

Thu Oct 14 02:24:00 GMT 2004

Dear GNU developers:

I find a bug in the GNU g77 compiler. But I do not know what the proper way to
report this bug is. 

At least from your website, it did not say anything.

http://www.gnu.org/software/fortran/fortran.html

I think this bug might be a common problem and may affect anyone who uses GNU
g77 for scientific computation.

It does not properly handle multi-dimensional array, and overwrite the array
when the array is called twice.

Here is a sample code to show this bug:

        write(*,*)'======1st time================='

        r = 0.23

        x1 = shap(r)

        write(*,*)' '

        write(*,*)'=======2nd time================'

        r = 0.43

        x1 = shap(r)

        write(*,*)' '

      end

      FUNCTION SHAP(R)

      PARAMETER (NIC=2,DR=1.0)

      DIMENSION ZZZ(NIC,2,2)

C

C

      LOGICAL FIRST

      DATA FIRST/.TRUE./

C

      IF(FIRST)THEN

        write(*,*) ' '

        write(*,*)'first time is=:'

        DO 20 K=1,2

        DO 30 IR = 1, NIC

        ZZZ(IR,1,K)=IR*0.2

        ZZZ(IR,2,K)=IR*1.0

        write(*,*) IR,1,k,ZZZ(IR,1,k)

     c      ,'   ',IR,2,k,ZZZ(IR,2,k)

 30     continue

 20     CONTINUE

        FIRST=.FALSE.

      ENDIF

C

      X=R/DR

      IR=X

      IR = IR+1

      SHAP=ZZZ(IR,1,1)

      write(*,*)' '

      write(*,*)'ZZZ are=:'

      do ir = 1,NIC

      write(*,*) IR,ZZZ(IR,1,1),ZZZ(IR,2,1)

     c ,ZZZ(IR,1,2),ZZZ(IR,2,2)

      enddo

      write(*,*)' '

C

      END

=================

here is the output after compiled with g77 and run

======1st time=================

 first time is=:

 1 1 1  0.200000003    1 2 1  1.

 2 1 1  0.400000006    2 2 1  2.

 1 1 2  0.200000003    1 2 2  1.

 2 1 2  0.400000006    2 2 2  2.

 ZZZ are=:

 1  0.200000003  1.  0.200000003  1.

 2  0.400000006  2.  0.400000006  2.

 =======2nd time================

 ZZZ are=:

 1  4.01037576E-34  3.99528214E-34  0.200000003  1.

 2 -1.99970341  1.40129846E-44  0.400000006  2.

The machine I tested is a linux machine with GNU compiler. 

I do not know how to read the version number, but here is the output from version:

g77 version 2.95.4 20011002 (Debian prerelease) (from FSF-g77 version 0.5.25
20010319 (prerelease))

Driving: g77 -v -c -xf77-version /dev/null -xnone

Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.4/specs

gcc version 2.95.4 20011002 (Debian prerelease)

 /usr/lib/gcc-lib/i386-linux/2.95.4/cpp0 -lang-c -v -D__GNUC__=2
-D__GNUC_MINOR__=95 -D__ELF__ -D__unix__ -D__i386__ -D__linux__ -D__unix
-D__linux -Asystem(posix) -D_LANGUAGE_FORTRAN -traditional -Acpu(i386)
-Amachine(i386) -Di386 -D__i386 -D__i386__ /dev/null /dev/null

GNU CPP version 2.95.4 20011002 (Debian prerelease) (i386 Linux/ELF)

#include "..." search starts here:

#include <...> search starts here:

 /usr/local/include

 /usr/lib/gcc-lib/i386-linux/2.95.4/include

 /usr/include

End of search list.

The following default directories have been omitted from the search path:

 /usr/lib/gcc-lib/i386-linux/2.95.4/../../../../include/g++-3

 /usr/lib/gcc-lib/i386-linux/2.95.4/../../../../i386-linux/include

End of omitted list.

 /usr/lib/gcc-lib/i386-linux/2.95.4/f771 -fnull-version -quiet -dumpbase
g77-version.f -version -fversion -o /tmp/ccHI4ihp.s /dev/null

GNU F77 version 2.95.4 20011002 (Debian prerelease) (i386-linux) compiled by GNU
C version 2.95.4 20011002 (Debian prerelease).

GNU Fortran Front End version 0.5.25 20010319 (prerelease)

 as -V -Qy -o /tmp/cc6Q5cUG.o /tmp/ccHI4ihp.s

GNU assembler version 2.14.90.0.7 (i386-linux) using BFD version 2.14.90.0.7
20031029 Debian GNU/Linux

 ld -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o /tmp/ccD1JxIY
/tmp/cc6Q5cUG.o /usr/lib/crt1.o /usr/lib/crti.o
/usr/lib/gcc-lib/i386-linux/2.95.4/crtbegin.o
-L/usr/lib/gcc-lib/i386-linux/2.95.4 -lg2c -lm -lgcc -lc -lgcc
/usr/lib/gcc-lib/i386-linux/2.95.4/crtend.o /usr/lib/crtn.o

 /tmp/ccD1JxIY

__G77_LIBF77_VERSION__: 0.5.25 20010319 (prerelease)

@(#)LIBF77 VERSION 19990503

__G77_LIBI77_VERSION__: 0.5.25 20010319 (prerelease)

@(#) LIBI77 VERSION pjw,dmg-mods 19990503

__G77_LIBU77_VERSION__: 0.5.25 20010319 (prerelease)

@(#) LIBU77 VERSION 19980709

Please let me know if you can reproduce this bug.

Best,

-- 
           Summary: multidimensional array problem
           Product: gcc
           Version: 2.95.4
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: shil at hep dot physics dot mcgill dot ca
                CC: gcc-bugs at gcc dot gnu dot org

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17987