Re: code speed moving from fortran 77 compiler to f2003 compiler



When I read the original post, the first thing I though was that a
modern compiler is more likely to use SSE instructions than an older
compiler, especially the newer SSE3 and SSE4 instructions. If you
have tight well-written do loops, then this is likely to result in
significant performance improvements, even without changing any of
the code, but perhaps some tweaking of the code might help this
process even more. There are also memory-related optimizations that
can be done on modern compilers to account for cache effects on
newer hardware.

We have sloppy, thousands of lines of code with multitudes of
subroutine calls, do loops all over the place. All of our
floating point is in double precision. I would like to see the
effects of the SSE instructions but I need get a fully working
version of the code in IVF first. It goes without saying that
Open Watcom F77 does not have a clue about the SSE instructions.

Thanks,
Lynn

.