Re: [AMBER-Developers] SSE2 / SSE3 settings no longer used for ifort?

From: Ben Roberts <>
Date: Mon, 26 Oct 2009 11:07:55 -0400


> fast does not activate those options on all platforms.
> But fast seems like the best optimized-flags option because it does
> activate different options on different platforms.
> So I don't know why it has not been used in configure for a long time.
> Of course, if we make this change now then we have to test it...

The fly in the ointment here is that netCDF configuration does not seem
to like -fast.

To be more specific, it doesn't like -ipo (which seems to be part and
parcel of -fast). To be even more specific, configuring netCDF with -ipo
gives the following fatal error:

checking NM... /usr/bin/nm
checking NMFLAGS...
checking for /usr/bin/nm... /usr/bin/nm
checking nm flags...
checking for C-equivalent to Fortran routine "SUB"... configure: error:
not found

This problem seems to be related to -ipo in particular, not to -ipo in
combination with the other flags implied by -fast, because if I try
"-ipo -O3", I get the exact same error. (Compare with -ip -O3, which
works OK.)

Unless there's a workaround I've missed here, I'd therefore caution
against using -fast in the configure script as the default.


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Received on Mon Oct 26 2009 - 08:30:02 PDT
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