Re: [AMBER] Fwd: AmberTools 16: IBM XL Compiler Support

From: James Ostrander <>
Date: Tue, 20 Dec 2016 14:29:34 -0500

Sorry for the late reply, Jason.

The XL compilers actually have a free community edition available here: Registration
is required and it is a "community edition," but IIRC the only difference
is that -O5 is unavailable.

There is also a Docker image containing the compilers:
This could be used to set up a build bot if you were so inclined.

Since XL compiler flags are different than GCC's, I don't think that proper
support can be attained in less-maintenance-cumbersome way than the
addition of a new compiler option in the build system. But let me know if
you change your mind and I will submit the patch to you if/when it is made.

On Wed, Dec 14, 2016 at 1:14 AM, Jason Swails <>

> On Tue, Dec 13, 2016 at 3:52 PM, James Ostrander <> wrote:
> > Hi, I am trying to use AmberTools on an IBM POWER8 system (ppc64le).
> IBM's
> > compilers produce the fastest machine code for this system, so I always
> try
> > to use them first.
> >
> > AmberTools seems to have no direct support for the IBM XL compilers
> > although it does offer out-of-the-box options for Intel, Clang, etc. I
> also
> > had a quick look at the build system and it seems non-trivial to manually
> > configure or add your own (unless I'm just missing something!).
> >
> > So from there, I have a few questions:
> > - I didn't see any options in configure --full-help that suggested a
> direct
> > compiler override. Am I missing something?
> > - If not, are there any plans to support IBM's compilers?
> > - If not, and someone offered you a patch that added support, would you
> be
> > willing to accept it into the official codebase?
> > - If so, is there any specific guidance you can offer that would get
> > someone started on adding the support?
> >
> ​You can always try to configure Amber (I would suggest using the
> --with-netcdf flag and use a pre-built NetCDF library if possible) and
> specify the gnu compilers. Then replace the compiler binaries in config.h
> with the IBM compiler names (and replace compiler flags if necessary). If
> the IBM compilers have flags compatible with another supported compiler,
> then you may be able to set the CC, FC, and CXX environment variables to
> point at the IBM compilers while specifying the flag-compatible compiler
> suite to configure.
> Note that these compilers are not supported because developers do not have
> access to these compilers. And adding support is only a relatively small
> part of the job -- the much bigger part is maintaining that support through
> multiple versions of the various libraries, codes, and compiler versions.
> It can sometimes be better to not have a feature at all than have some
> untested code that *might* provide support.
> That's not to say there's no value, though. If there are small changes
> necessary to improve IBM compiler support​
> that also improves the configure script as a whole (and does not introduce
> maintenance headaches), I imagine such a patch would be welcome.
> HTH,
> Jason
> --
> Jason M. Swails
> _______________________________________________
> AMBER mailing list

*James Ostrander*
*ITS Administrative Info Srvcs*
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Received on Tue Dec 20 2016 - 11:30:03 PST
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