Fortran interfaces to OpenACC runtimes

• This directory provides extensions to the openacc.f90 Fortran interfaces for OpenACC runtimes. In particular, it provides a bridge to runtime functions that realise !$acc enter data, !$acc exit data, and !$acc data. Moreover, a bridge to acc_deviceptr is provided, which is often not found in openacc.f90.

  • Currently only interfaces to GCC's LIBGOMP are provided.

    Features:

    • Thread-safe
    • Standard-compliant runtime API

    Limitations:

    • This runtime does not support the acc_get_cuda_stream vendor-specific extension. Therefore, no hipStream instance can be obtained from the runtime and passed to hipfort API calls or GPUFORT kernel launch routines.
    • Examples are likely outdated

• This directory further contains gpufort_acc_runtime, a minimal non-standard-compliant runtime written completely in Fortran, which can be used for teaching/training or prototyping.

  Features:

  • hipStream instances can be obtained from the runtime. Limitations:
  • Not thread-safe
  • No standard-compliant runtime API (might change in the future)

Runtime subfolders

• openacc_gomp: contains extended interfaces to GCC's LIBGOMP.
• gpufort_acc_runtime: contains a minimal non-standard-compliant runtime written completely in Fortran, which can be used teaching purposes

Building

cd <runtime_subfolder>
make

Take a look into the Makefile in each folder and adapt it to your needs. Certain Makefile variables can be overwritten via the environment variables
FC, HIPFORT_PATH, FCFLAGS, CXX, CXXFLAGS.

Example:

cd <runtime_subfolder>
FC=/usr/bin/gfortran HIPFORT_PATH=/opt/rocm/hipfort/install/ make clean all

NOTE: python3 with jinja2 package installed is required to use the codegen target.`

Outlook

• We require a standard-compliant, thread-safe HIP C++ based runtime that can be used/built for HIP devices from different vendors (AMD, NVIDIA) to support efforts such as GPUFORT. Main purpose of the runtime must be mapping data between host and device and managing HIP streams. Other features are optional.