HPXMP Meta

This project contains tests, examples and useful scripts for compiling and using HPXMP, the HPX-enabled OpenMP implementation.

Building HPXMP

HPXMP is a modified version of llvm-project/openmp, which utilizes the HPXC interface to run on top of the HPX runtime.

Thus HPX, HPXC and llvm-project/openmp must be built using CMake (in that order, as each depends on the previous one).

The scripts/ directory contains scripts which can be used directly (or referenced for the appropriate CMake configuration commands) for building all above libraries.

Using HPXMP

As HPXMP is a modification of the llvm-project/openmp library, HPXMP builds a library named libomp.so, which is a drop-in replacement for any typical libomp.so/libgomp.so OpenMP library provided by your system.

Important: Since pretty much all systems provide a libomp.so, it is easy to accidentally link to some other one. The only ways to make sure that the correct library is linked are 1) Prepending(!) HPXMP's libomp.so path to LD_LIBRARY_PATH, or 2) Adding HPXMP's libomp.so to LD_PRELOAD.

Please always check that the correct OpenMP shared library is linked to your program by using the ldd utility (or some equivalent).

There are two ways to link your program to the HPXMP library:

1. For programs built with CMake:

   1. Include the CMake Find Module for HPXMP (located in cmake/FindHPXMP.cmake) in your CMake project, and use find_package(HPXMP) to introduce the HPXMP::hpxmp target to your project. Then, link your program to the HPXMP::hpxmp target using target_add_libraries(<my_program> HPX::hpxmp).

2. Manually:

   1. Link the HPXMP shared library (libomp.so) to your program.

   2. Link to HPXC's libhpx_hpxc_wrap.a and add the -Wl,-wrap=main linker flag when compiling your program. This will initialize HPXC/HPX before entering your program's main function. This is crucial as HPXMP functionality only works inside the context of the HPX runtime. Failing to do this properly will lead to exceptions/segfaults.