bug in g77 for at least IA64 and AMD64

[Winfrid Tschiedel <winfrid dot tschiedel at hpc dot fujitsu-siemens dot com>]

Hi,

This small fortran program causes a segmentation fault :
      program test
      parameter ( n3=257)
      common /abc/ a ,b
      real*8 a(1024,1024,n3),b(1024,1024,255)
      b(1,100,3)=1.0d0
      a(1,100,3)=1.0d0
      a(1024,1024,n3)=2.d0
      b(1024,1024,255)=3.0
      print *,a(1,100,3),b(1,100,3)
      print *,a(1024,1024,n3),b(1024,1024,255)
      end

[winfrid@rxiX00-rhel ~]$ g77  big-mem.f
[winfrid@rxiX00-rhel ~]$ ./a.out
Segmentation fault (core dumped)

If you change n3 to 255 or if you split common /abc/ into 2 common zones
the program works
      program test
      parameter ( n3=257)
      common /abc_1/ a
      common /abc_2/ b
      real*8 a(1024,1024,n3),b(1024,1024,255)
      b(1,100,3)=1.0d0
      a(1,100,3)=1.0d0
      a(1024,1024,n3)=2.d0
      b(1024,1024,255)=3.0
      print *,a(1,100,3),b(1,100,3)
      print *,a(1024,1024,n3),b(1024,1024,255)
      end

time ./a.out
  1.  1.
  2.  3.
0.000u 0.000s 0:00.00 0.0%      0+0k 0+0io 80pf+0w

Information concerning the invirionment :
[winfrid@rxiX00-rhel ~]$ uname -a
Linux rxiX00-rhel 2.4.21-4.EL #1 SMP Fri Oct 3 17:29:39 EDT 2003 ia64 ia64 ia64 GNU/Linux

[winfrid@rxiX00-rhel ~]$ rpm -qa | fgrep g77
gcc-g77-ssa-3.5ssa-0.20030801.41
gcc-g77-3.2.3-20

Same problem on gcc-3.4 ( gcc-3.4-20030903 ) :

[winfrid@rxiX00-rhel ~]$ set path=(/opt/gcc-3.4/bin $path)
[winfrid@rxiX00-rhel ~]$ setenv LD_LIBRARY_PATH /opt/gcc-3.4/lib
[winfrid@rxiX00-rhel ~]$ g77 big-mem.f
[winfrid@rxiX00-rhel ~]$ !t
time ./a.out
Segmentation fault (core dumped)
0.000u 0.159s 0:00.15 100.0%    0+0k 0+0io 67pf+0w
[winfrid@rxiX00-rhel ~]$ g77 big-mem2.f
[winfrid@rxiX00-rhel ~]$ !t
time ./a.out
  1.  1.
  2.  3.
0.000u 0.000s 0:00.00 0.0%      0+0k 0+0io 78pf+0w

Same problem on AMD64 ( SLES 8 )
/home/winfrid> uname -a
Linux arima 2.4.21-111-smp #1 SMP Wed Oct 1 11:39:54 UTC 2003 x86_64 unknown

/home/winfrid> g77 -mcmodel=medium /tmp/big-mem.f/home/winfrid> time ./a.out
Segmentation fault
0.000u 0.000s 0:00.00 0.0%      0+0k 0+0io 123pf+0w
/home/winfrid> g77 -mcmodel=medium /tmp/big-mem2.f
/home/winfrid> time ./a.out
  1.  1.
  2.  3.

Note I could not use gcc-3.4 for the test on AMD Opteron, because of the
following error :

/home/winfrid> set path=(/home/gcc-3.4.2/bin $path)
/home/winfrid> setenv LD_LIBRARY_PATH /home/gcc-3.4.2/lib64
/home/winfrid> which g77
/home/gcc-3.4.2/bin/g77
/home/winfrid> g77 -mcmodel=medium big-mem.f
/tmp/ccROxIQa.s: Assembler messages:
/tmp/ccROxIQa.s:118: Error: .COMMon length (-2139095040.) <0! Ignored.
/tmp/ccROxIQa.s:118: Warning: rest of line ignored; first ignored character is `
,'

I hope this information will be helpful for improving g77/gcc

Take care,

Winfrid

PS.: I am on holiday until Nov. 24
-- 
_______________________________________________________________________________

Fujitsu Siemens Computers
SMCS G LE PCO Süd            Email: winfrid.tschiedel@hpc.fujitsu-siemens.com
Otto-Hahn-Ring 6             Tel. : ++49-89-636-45652
81739 Muenchen               Fax  : ++49-89-636-43604 

MS Exchange : winfrid.tschiedel@fujitsu-siemens.com