Building SWIFT ============== SWIFT is built from a clean source repository using the commands: ./autogen ./configure make and from a distribution tarball using: ./configure make The compiler choice is GCC by default, but that can be changed using the "CC" environment variable. This can be just set, or passed on the ./configure command line, i.e.: bash: export CC=icc ./configure [t]csh: setenv CC=icc ./configure or: ./configure CC=icc to use an Intel compiler. The main "programs" can be found in the "examples/" directory. See README for run parameters. SWIFT has been successfully built and tested with the following compilers: - GCC 4.8.x - Intel ICC 15.0.x - clang 3.4.x - aocc 3.x - icx (oneAPI) 2022.x More recent versions and slightly older ones should also be able to build the software. It has also been built with Intel and GNU C++ compilers, but that currently requires the --disable-vec and, for Intel, --disable-compiler-warnings configure options. By default an attempt to choose suitable set of optimizing compiler flags will be made, targeted for the host machine of the build. If this doesn't work or the binaries will for another architecture then you can stop the selection of flags using: ./configure --disable-optimization and then supply your own flags using the "CFLAGS" environment variable, as for CC. Note that any CFLAGS that you supply will be added to those determined by configure in all circumstances. To build SWIFT with debugging support you can use: ./configure --enable-debug --disable-optimization You could also add some additional flags: ./configure --enable-debug --disable-optimization CFLAGS="-O2" for instance. GCC address sanitizer flags can be included using the ./configure --enable-sanitizer option. Note this requires a GCC compiler version of at least 4.8. By default vectorization is switched on. The highest instruction set available on the platform will be automatically used. However, not all implementations of SPH available in the code have vectorized routines. Vectorization will have to be switched off for these. It can also be switched off for benchmarking purposes. To do so, you can use: ./configure --disable-vec Please note that to build SWIFT on MacOS, you will need to configure using ./configure --disable-compiler-warnings due to the incorrect behaviour of the LLVM compiler on this platform that raises warnings when the pthread flags are passed to the linker. Dependencies ============ SWIFT depends on a number of third party libraries that should be available before you can build it. - HDF5: A HDF5 library (v. 1.10.x or higher) is required to read and write particle data. One of the commands "h5cc" or "h5pcc" should be available. If "h5pcc" is located then a parallel HDF5 built for the version of MPI located should be provided. If the command is not available then it can be located using the "--with-hdf5" configure option. The value should be the full path to the "h5cc" or "h5pcc" commands. SWIFT makes effective use of parallel HDF5 when running on more than one node, so this option is highly recommended. - MPI: To run on more than one node an MPI library that fully supports MPI_THREAD_MULTIPLE is required. Before running configure the "mpirun" command should be available in the shell. If your command isn't called "mpirun" then define the "MPIRUN" environment variable, either in the shell or when running configure. The MPI compiler can be controlled using the MPICC variable, much like the CC one. Use this when your MPI compiler has a none-standard name. - GSL: To use cosmological time integration, a version of the GSL must be available. - FFTW 3.x: To run with periodic gravity forces, a build of the FFTW 3 library must be available. Note that SWIFT does not make use of the parallel capability of FFTW. Calculations are done by single MPI nodes independently. - libtool: The build system relies on libtool as well as the other autotools. Optional Dependencies ===================== - METIS/ParMETIS: a build of the METIS or ParMETIS library should be used to optimize the load between MPI nodes. This should be found in the standard installation directories, or pointed at using the "--with-metis" or "--with-parmetis" configuration options. In this case the top-level installation directory of the build should be given. Note to use METIS or ParMETIS you should supply at least "--with-metis". ParMETIS is preferred over METIS when there is a choice. - libNUMA: a build of the NUMA library can be used to pin the threads to the physical core of the machine SWIFT is running on. This is not always necessary as the OS scheduler may do a good job at distributing the threads among the different cores on each computing node. Note that if you have libNUMA outside of the system include directories it may fail to compile as the headers do not pass the -Wstrict-prototype check of GCC. In that case you will need to use --enable-compiler-warnings=yes configure option to stop this being an error. - tcmalloc / jemalloc / TBBmalloc: a build of the tcmalloc library (part of gperftools), jemalloc or TBBmalloc can be used be used to obtain faster and more scalable allocations than the standard C malloc function part of glibc. Using one of these is highly recommended on systems with many cores per node. One of the options "--with-tcmalloc", "--with-jemalloc" or "--with-tbbmalloc" should be passed to the configuration script to use it. - gperftools: a build of gperftools can be used to obtain good profiling of the code. The option "--with-profiler" needs to be passed to the configuration script to use it. - DOXYGEN: the doxygen library is required to create the SWIFT API documentation. - python: Examples and solution script use python 3 and rely on the numpy library version 1.8.2 or higher. SWIFT Coding style ================== The SWIFT source code uses a variation of 'Google' style. The script 'format.sh' in the root directory applies the clang-format-18 tool with our style choices to all the SWIFT C source file. Please apply the formatting script to the files before submitting a merge request. The Python scripts in the repository use default formatting enforced by 'black'. Since 'black' formatting still strongly depends on the version, we currently enforce use of 'black==19.3b0' using a virtual environment. The setup of the virtual environment and formatting of all PYthon scripts is done automatically by the Python formatting script 'format_python.sh'. Please apply this script before submitting a merge request containing new or updated Python scripts.