Re: Thoughts on llvm/clang in base

[Carsten Mattner <carstenmattner@xxxxxxxxx>]

On Mon, Oct 15, 2012 at 4:55 PM, B. Estrade <estrabd@gmail.com> wrote:
> On Mon, Oct 15, 2012 at 03:45:48PM +0100, peeter (must) wrote:
>> On Mon, Oct 15, 2012 at 3:33 PM, B. Estrade <estrabd@gmail.com> wrote:
>> > On Mon, Oct 15, 2012 at 03:17:08PM +0100, peeter (must) wrote:
>> >> Just to chime in with this, we're using OpenMPI on DF and it'd be
>> >> very, very bad news for us if support for OpenMPI would be
>> >> discontinued for the mentioned reason. We'd need to change the
>> >> platform then. . .
>> >>
>> >> Cheers, Peeter
>> >
>> > Do you mean OpenMP (shared memory) or OpenMPI (message passing?).
>> >
>> > OpenMPI is a separate library and not tied into a compiler or its
>> > runtime like OpenMP is (e.g., "GOMP" is the GCC project to handle the
>> > frontend/transformations/runtime).
>
> No problem, it happens all the time in this alphabet soup world in
> which we live.
>
> OpenMPI does have some things that allow you to combine OpenMP
> and OpenMPI for hybrid message passing/shared memory programs.
>
> OpenMPI (as you know) is a library, and pretty agnostic to the
> platform and compiler suite.  OpenMP must be facilitated by the
> compiler because their are frontend changes that must be made to
> recognize and transform the source code directives as well as a
> runtime that supports the OpenMP standard API during execution.  It's
> a common mistake, though.
>
>     http://www.openmp.org
>
>     http://www.openmpi.org
>
> GCC supports OpenMP directly, though OpenMPI can certainly be built
> with GCC (and infact, most often is in commidity beowulf clusters).
>
>     http://gcc.gnu.org/projects/gomp/
>
> Cheers,
> Brett

Some comments:
- There are active OpenMP efforts for inclusion in clang
- Nothing prevents you from using gcc for your project while building base
or world with clang. John, anything wrong with that?

Therefore I don't see any issue for your OpenMP requirement.

>> >
>> > Thank you,
>> > Brett
>> >
>> >>
>> >> --
>> >
>>
>> Oops! Sorry, I meant OpenMPI, the message passing interface. If this
>> has no relevance to the topic, then apologies for the confusion.
>>
>> Peeter