gcc optimizer problem
Tue Apr 7 17:08:00 GMT 1998
> I'm a member of a large collaboration performing research
> in high energy physics ( http://www-h1.desy.de ) and I have
> a problem with the GCC optimizer for some Fortran code
> on a PC running Linux. The code performs only correct
> without optimization (-O0).
> The compiler options used are:
> g77 -c -w -fno-automatic -finit-local-zero -O2
> -fno-backslash gcc -c -w -ansi -O2
* isolated maximum found,check it
* worse isolation?
CHK the magic print statement
C PRINT *, ' IXCLU1- '
IF (FRAC.LT.FRACX) GOTO 500
Could you try this routine compiled with the additional flag
-ffloat-store ? I bet the "adding this print solves the problem" is
a dead give-away that FRAC normally is kept in a register, which
gives it a slightly different value from when it has to be stored
(which is the case around the calls resulting from the print
Grrrr, don't you love the ix86 architecture :-(
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