Re: trying out openacc 2.0

[Tobias Burnus <tobias dot burnus at physik dot fu-berlin dot de>]

Mark Farnell wrote:
> Has OpenACC 2.0 support been merged into the trunk yet?  If not, then
> is it contained in gomp-4_0-branch?
>
> If so, what parameters should I pass to ./configure to enable OpenACC
> 2.0, and relevant backends such as CUDA, MIC and other GPGPU/manycore
> architecture?
>
> Also, I have a feeling that OpenACC 2.0 did NOT make it to gcc 5.0, am
> I correct?  If I am correct, then will it be included in gcc 5.1?  If
> I am wrong and it is already included into gcc 5.0, then I would
> really really like to use it.
>
> In the latter case, will I be able to write OpenACC 2.0 / OpenMP 4.0
> code that runs on my nvidia GPU and/or Intel Xeon Phi?

Let's start from the end: OpenMP 4 support for Intel's Xeon Phi is in the
trunk and - in principle - working. The only problem is that only
Knights Landing (knl) is supported and not the old Knights Corner (knc);
given that Knights Landing is not yet available, you currently can only use
it with a simulator.

Regarding the question how to build GCC with accelerator support, see
https://gcc.gnu.org/wiki/Offloading - That page applies both to OpenACC
and OpenMP and to KNL and Nvidia's PTX. However, it is currently still a bit
KNL centric.

Regarding OpenACC: The support has not yet been merged, however, I think the
goal is still to get it included in GCC 5. The first bits - like PTX support -
have already been merged. I think the gomp-4_0-branch provides all what's
needed and it has been recently updated to match the trunk (last Sunday).
For building the branch and using OpenACC+PTX, again start with
https://gcc.gnu.org/wiki/Offloading

Tobias,
who has yet to try offloading himself