Emulators

Motivation and Usage

Are you hoping for a world with full compiler support for recent Fortran standards? Emulating an unsupported feature facilitates using the feature prior to compiler support. This path offers minimal impact on future code. Switching to the compiler's version of a feature might involve little more than toggling a preprocessor macro:

#ifdef EMULATE_COLLECTIVES
  use collectives_m, only : co_sum
#endif

and then not passing the macro at EMULATE_COLLECTIVES to the compiler to turn eliminate the emulated version of co_sum from the source code before compiling.

Emulators contains a few emulated procedures and preprocessor macros that trigger their compilation. We make no attempt at comprehensiveness. We support only the procedures, arguments, and argument types, kinds, and ranks that we have found useful in our own work. We welcome pull requests that expand Emulators's emulators in number or capability.

Contents

Emulated features:

• Fortran 2008 intrinsic function: findloc
• Fortran 2018 collective subroutines: co_sum, co_broadcast

Those who find the collective subroutines useful might also be interested in language extensions such as the Sourcery library's co_all subroutine, which provides a parallel, collective logical operation analogous to the all intrinsic function.

Prerequisites

Emulators builds with a Fortran compiler that supports the following features:

• Error stop

  • Emulators's only dependency, Assert, uses Fortran 2018 error stop, which several compilers have supported before supporting the features that Emulators emulates. Please submit an issue or pull request if you prefer to have the option to build without Assert.

• Coarrays and synchronization

  • Emulators's Fortran 2018 collective-subroutine emulators use Fortran 2008 coarrays and synchronization.

Downloading, building and testing

Parallel execution

With gfortran and OpenCoarrays installed, execute the following commands in a bash-like shell to include all emulators in the build:

git clone [email protected]:sourceryinstitute/emulators
fpm test \
  --runner cafrun -n 2 \
  --compiler caf \
  --flag "-cpp -DEMULATE_INTRINSICS -DEMULATE_COLLECTIVES"

Serial execution

With gfortran installed, execute the following commands in a bash-like shell to include all emulators in the build:

git clone [email protected]:sourceryinstitute/emulators
fpm test --flag "-cpp -DEMULATE_INTRINSICS -DEMULATE_COLLECTIVES -fcoarray=single"