[gmx-users] intel compiler + amd64: help needed.

[David Mathog]

> But now I have a (big) question: this code
> compiles properly with gcc.
> Ok, maybe that means difference of tolerance
> between different compilers. But the code also compiles with intel on
intel
> machines, and seems to work properly on older amd machines (not quite sure
> if they need to be so old that there is no SSE even).

There have been in the past versions of Intel compilers that checked
for a genuine Intel chip and then disabled certain CPU optimizations
(like SSE2) if they didn't find it.  That may or may not be what's
going on here.  My gut feeling is that it's probably just a bug in the
gromacs code which happens to "bite" on some platforms and not
on others.  It's a common experience to move code from one platform
to another and uncover a bunch of latent bugs that were never
seen on the first platform.  Running the code with a malloc checker 
tends to reduce the number of these latent bugs, but unless you
can test every possible path through the code while doing that, it
won't find them all.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech