g77: Different results when compiling with/without -fbounds-check ?!

[Richard Ems]

 
 
Hi all,
After 2 days searching for errors and comparing my test case result's
with different option combinations, I found
that compiling with -fbounds-check and without it returns (for my test
case) different results.
Attached are my two files, the main program file and the subroutine
one.
After running:
clear
set -x
for OPT in O0 O3
do
  g77 -$OPT -o testit-$OPT testit.f zwwe.f && time ./testit-$OPT
  mv -f fort.77 fort-$OPT.77
done
diff fort-O0.77 fort-O3.77
set +x
(the same in one line:   clear ; set -x ; for OPT in O0 O3
; do g77 -$OPT -o testit-$OPT testit.f zwwe.f && time ./testit-$OPT
&& mv -f fort.77 fort-$OPT.77 ; done && diff fort-O0.77
fort-O3.77 ; set +x   )
several times, I get no differences from the diff command. As you can
see, I'm compiling WITHOUT -fbounds-check.
Running the same, also several times, but now compiling WITH -fbounds-check,
I get different results for the executable compiled with -O0 and the one
compiled with -O3.
( The same as above WITH -fbaound-check :
clear ; set -x ; for OPT in O0 O3 ; do g77 -fbounds-check -$OPT -o
testit-$OPT testit.f zwwe.f && time ./testit-$OPT && mv
-f fort.77 fort-$OPT.77 ; done && diff fort-O0.77 fort-O3.77 ;
set +x   )
Is this supposed to behave like this? I suppose not!
I'm runing on SuSE Linux 6.4, kernel 2.2.16
g77 --version: GNU Fortran 0.5.25 19991030 (prerelease)
gcc --version: 2.95.2
as --version:GNU assembler 2.9.5
 
Many thanks, Richard Ems
 
 
-- 
   Richard Ems
   ... e-mail: r.ems@gmx.net
   ... Computer Science, University of Hamburg

   Unix IS user friendly. It's just selective about who its friends are.
 
 
 
 
 
 
 
 
      program testit
c
      implicit none
c
      integer i, mynx
      parameter (mynx=100)
      real a, myx, myxu, mydx, zwwe
      real myf(mynx)
c
      myx = acos(-1.)
      myxu = 1.0
      mydx = 1.0
c
      do 1 i=1,mynx,1
         myf(i) = real(i)/100000*rand(i)
 1    continue 
c
      do 2 i=1,10000,1
         myx = myx*(rand(i)+0.6)
         write (77,*) 'in testit: vor zwwe: ', myx, myxu, mydx, mynx
         a = zwwe(myx, myxu, mydx, mynx, myf)
         write (77,*) 'in testit: a = ', a
 2    continue
c
      end
c