Developers

CMake is our primary build system. If you are new to CMake, this short tutorial from the HEP Software foundation is the perfect place to get started. If you just want to use CMake to build the project, jump into sections 1. Introduction, 2. Building with CMake and 9. Finding Packages.

Dependencies

Before you start, you will need a copy of the WarpX source code:

git clone https://github.com/ECP-WarpX/WarpX.git $HOME/src/warpx
cd $HOME/src/warpx

WarpX depends on popular third party software.

Compile

From the base of the WarpX source directory, execute:

# find dependencies & configure
#   see additional options below, e.g.
#                   -DCMAKE_INSTALL_PREFIX=$HOME/sw/warpx
cmake -S . -B build

# compile, here we use four threads
cmake --build build -j 4

That’s it! A 3D WarpX binary is now in build/bin/ and can be run with a 3D example inputs file. Most people execute the binary directly or copy it out.

If you want to install the executables in a programmatic way, run this:

# for default install paths, you will need administrator rights, e.g. with sudo:
cmake --build build --target install

You can inspect and modify build options after running cmake -S . -B build with either

ccmake build

or by adding arguments with -D<OPTION>=<VALUE> to the first CMake call. For example, this builds WarpX in 2D geometry and enables Nvidia GPU (CUDA) support:

cmake -S . -B build -DWarpX_DIMS=2 -DWarpX_COMPUTE=CUDA

Build Options

CMake Option

Default & Values

Description

CMAKE_BUILD_TYPE

RelWithDebInfo/Release/Debug

Type of build, symbols & optimizations

CMAKE_INSTALL_PREFIX

system-dependent path

Install path prefix

CMAKE_VERBOSE_MAKEFILE

ON/OFF

Print all compiler commands to the terminal during build

PYINSTALLOPTIONS

Additional options for pip install, e.g., -v --user

WarpX_APP

ON/OFF

Build the WarpX executable application

WarpX_ASCENT

ON/OFF

Ascent in situ visualization

WarpX_COMPUTE

NOACC/OMP/CUDA/SYCL/HIP

On-node, accelerated computing backend

WarpX_DIMS

3/2/1/RZ

Simulation dimensionality

WarpX_EB

ON/OFF

Embedded boundary support (not supported in RZ yet)

WarpX_GPUCLOCK

ON/OFF

Add GPU kernel timers (cost function, +4 registers/kernel)

WarpX_IPO

ON/OFF

Compile WarpX with interprocedural optimization (aka LTO)

WarpX_LIB

ON/OFF

Build WarpX as a shared library, e.g., for PICMI Python

WarpX_MPI

ON/OFF

Multi-node support (message-passing)

WarpX_MPI_THREAD_MULTIPLE

ON/OFF

MPI thread-multiple support, i.e. for async_io

WarpX_OPENPMD

ON/OFF

openPMD I/O (HDF5, ADIOS)

WarpX_PRECISION

SINGLE/DOUBLE

Floating point precision (single/double)

WarpX_PSATD

ON/OFF

Spectral solver

WarpX_QED

ON/OFF

QED support (requires PICSAR)

WarpX_QED_TABLE_GEN

ON/OFF

QED table generation support (requires PICSAR and Boost)

WarpX_SENSEI

ON/OFF

SENSEI in situ visualization

WarpX can be configured in further detail with options from AMReX, which are documented in the AMReX manual:

Developers might be interested in additional options that control dependencies of WarpX. By default, the most important dependencies of WarpX are automatically downloaded for convenience:

CMake Option

Default & Values

Description

CCACHE_PROGRAM

First found ccache executable.

Set to -DCCACHE_PROGRAM=NO to disable CCache.

AMReX_CUDA_PTX_VERBOSE

ON/OFF

Print CUDA code generation statistics from ptxas.

WarpX_amrex_src

None

Path to AMReX source directory (preferred if set)

WarpX_amrex_repo

https://github.com/AMReX-Codes/amrex.git

Repository URI to pull and build AMReX from

WarpX_amrex_branch

we set and maintain a compatible commit

Repository branch for WarpX_amrex_repo

WarpX_amrex_internal

ON/OFF

Needs a pre-installed AMReX library if set to OFF

WarpX_openpmd_src

None

Path to openPMD-api source directory (preferred if set)

WarpX_openpmd_repo

https://github.com/openPMD/openPMD-api.git

Repository URI to pull and build openPMD-api from

WarpX_openpmd_branch

0.14.3

Repository branch for WarpX_openpmd_repo

WarpX_openpmd_internal

ON/OFF

Needs a pre-installed openPMD-api library if set to OFF

WarpX_picsar_src

None

Path to PICSAR source directory (preferred if set)

WarpX_picsar_repo

https://github.com/ECP-WarpX/picsar.git

Repository URI to pull and build PICSAR from

WarpX_picsar_branch

we set and maintain a compatible commit

Repository branch for WarpX_picsar_repo

WarpX_picsar_internal

ON/OFF

Needs a pre-installed PICSAR library if set to OFF

For example, one can also build against a local AMReX copy. Assuming AMReX’ source is located in $HOME/src/amrex, add the cmake argument -DWarpX_amrex_src=$HOME/src/amrex. Relative paths are also supported, e.g. -DWarpX_amrex_src=../amrex.

Or build against an AMReX feature branch of a colleague. Assuming your colleague pushed AMReX to https://github.com/WeiqunZhang/amrex/ in a branch new-feature then pass to cmake the arguments: -DWarpX_amrex_repo=https://github.com/WeiqunZhang/amrex.git -DWarpX_amrex_branch=new-feature.

You can speed up the install further if you pre-install these dependencies, e.g. with a package manager. Set -DWarpX_<dependency-name>_internal=OFF and add installation prefix of the dependency to the environment variable CMAKE_PREFIX_PATH. Please see the introduction to CMake if this sounds new to you.

If you re-compile often, consider installing the Ninja build system. Pass -G Ninja to the CMake configuration call to speed up parallel compiles.

Configure your compiler

If you don’t want to use your default compiler, you can set the following environment variables. For example, using a Clang/LLVM:

export CC=$(which clang)
export CXX=$(which clang++)

If you also want to select a CUDA compiler:

export CUDACXX=$(which nvcc)
export CUDAHOSTCXX=$(which clang++)

We also support adding additional compiler flags via environment variables such as CXXFLAGS/LDFLAGS:

# example: treat all compiler warnings as errors
export CXXFLAGS="-Werror"

Note

Please clean your build directory with rm -rf build/ after changing the compiler. Now call cmake -S . -B build (+ further options) again to re-initialize the build configuration.

Run

An executable WarpX binary with the current compile-time options encoded in its file name will be created in build/bin/. Note that you need separate binaries to run 1D, 2D, 3D, and RZ geometry inputs scripts. Additionally, a symbolic link named warpx can be found in that directory, which points to the last built WarpX executable.

More details on running simulations are in the section Run WarpX. Alternatively, read on and also build our PICMI Python interface.

PICMI Python Bindings

Note

Preparation: make sure you work with up-to-date Python tooling.

python3 -m pip install -U pip setuptools wheel
python3 -m pip install -U cmake

For PICMI Python bindings, configure WarpX to produce a library and call our pip_install CMake target:

# find dependencies & configure
cmake -S . -B build -DWarpX_LIB=ON

# build and then call "python3 -m pip install ..."
cmake --build build --target pip_install -j 4

That’s it! You can now run a first 3D PICMI script from our examples.

Developers could now change the WarpX source code and then call the build line again to refresh the Python installation.

Note

These commands build one -DWarpX_DIMS=... dimensionality (default: 3) at a time. If your build/lib*/ directory contains previously built libwarpx* libraries, then --target pip_install picks them up as well. A new call to cmake --build build ... will only rebuild one dimensionality, as set via WarpX_DIMS.

If you like to build a WarpX Python package that supports all dimensionalities, you can run this:

for d in 1 2 3 RZ; do
    cmake -S . -B build -DWarpX_DIMS=$d -DWarpX_LIB=ON
    cmake --build build -j 4
done
cmake --build build --target pip_install

Tip

If you do not develop with a user-level package manager, e.g., because you rely on a HPC system’s environment modules, then consider to set up a virtual environment via Python venv. Otherwise, without a virtual environment, you likely need to add the CMake option -DPYINSTALLOPTIONS="--user".

Python Bindings (Package Management)

This section is relevant for Python package management, mainly for maintainers or people that rather like to interact only with pip.

One can build and install pywarpx from the root of the WarpX source tree:

python3 -m pip wheel -v .
python3 -m pip install pywarpx*whl

This will call the CMake logic above implicitly. Using this workflow has the advantage that it can build and package up multiple libraries with varying WarpX_DIMS into one pywarpx package.

Environment variables can be used to control the build step:

Environment Variable

Default & Values

Description

WARPX_COMPUTE

NOACC/OMP/CUDA/SYCL/HIP

On-node, accelerated computing backend

WARPX_DIMS

"1;2;3;RZ"

Simulation dimensionalities (semicolon-separated list)

WARPX_EB

ON/OFF

Embedded boundary support (not supported in RZ yet)

WARPX_MPI

ON/OFF

Multi-node support (message-passing)

WARPX_OPENPMD

ON/OFF

openPMD I/O (HDF5, ADIOS)

WARPX_PRECISION

SINGLE/DOUBLE

Floating point precision (single/double)

WARPX_PSATD

ON/OFF

Spectral solver

WARPX_QED

ON/OFF

PICSAR QED (requires PICSAR)

WARPX_QED_TABLE_GEN

ON/OFF

QED table generation (requires PICSAR and Boost)

BUILD_PARALLEL

2

Number of threads to use for parallel builds

BUILD_SHARED_LIBS

ON/OFF

Build shared libraries for dependencies

HDF5_USE_STATIC_LIBRARIES

ON/OFF

Prefer static libraries for HDF5 dependency (openPMD)

ADIOS_USE_STATIC_LIBS

ON/OFF

Prefer static libraries for ADIOS1 dependency (openPMD)

WARPX_AMREX_SRC

None

Absolute path to AMReX source directory (preferred if set)

WARPX_AMREX_REPO

None (uses cmake default)

Repository URI to pull and build AMReX from

WARPX_AMREX_BRANCH

None (uses cmake default)

Repository branch for WARPX_AMREX_REPO

WARPX_AMREX_INTERNAL

ON/OFF

Needs a pre-installed AMReX library if set to OFF

WARPX_OPENPMD_SRC

None

Absolute path to openPMD-api source directory (preferred if set)

WARPX_OPENPMD_INTERNAL

ON/OFF

Needs a pre-installed openPMD-api library if set to OFF

WARPX_PICSAR_SRC

None

Absolute path to PICSAR source directory (preferred if set)

WARPX_PICSAR_INTERNAL

ON/OFF

Needs a pre-installed PICSAR library if set to OFF

WARPX_CCACHE_PROGRAM

First found ccache executable.

Set to NO to disable CCache.

PYWARPX_LIB_DIR

None

If set, search for pre-built WarpX C++ libraries (see below)

Note that we currently change the WARPX_MPI default intentionally to OFF, to simplify a first install from source.

Some hints and workflows follow. Developers, that want to test a change of the source code but did not change the pywarpx version number, can force a reinstall via:

python3 -m pip install --force-reinstall --no-deps -v .

Some Developers like to code directly against a local copy of AMReX, changing both code-bases at a time:

WARPX_AMREX_SRC=$PWD/../amrex python3 -m pip install --force-reinstall --no-deps -v .

Additional environment control as common for CMake (see above) can be set as well, e.g. CC, CXX`, and CMAKE_PREFIX_PATH hints. So another sophisticated example might be: use Clang as the compiler, build with local source copies of PICSAR and AMReX, support the PSATD solver, MPI and openPMD, hint a parallel HDF5 installation in $HOME/sw/hdf5-parallel-1.10.4, and only build 3D geometry:

CC=$(which clang) CXX=$(which clang++) WARPX_AMREX_SRC=$PWD/../amrex WARPX_PICSAR_SRC=$PWD/../picsar WARPX_PSATD=ON WARPX_MPI=ON WARPX_DIMS=3 CMAKE_PREFIX_PATH=$HOME/sw/hdf5-parallel-1.10.4:$CMAKE_PREFIX_PATH python3 -m pip install --force-reinstall --no-deps -v .

Here we wrote this all in one line, but one can also set all environment variables in a development environment and keep the pip call nice and short as in the beginning. Note that you need to use absolute paths for external source trees, because pip builds in a temporary directory, e.g. export WARPX_AMREX_SRC=$HOME/src/amrex.

The Python library pywarpx can also be created by pre-building WarpX into one or more shared libraries externally. For example, a package manager might split WarpX into a C++ package and a Python package. If the C++ libraries are already pre-compiled, we can pick them up in the Python build step instead of compiling them again:

# build WarpX executables and libraries
for d in 1 2 3 RZ; do
  cmake -S . -B build -DWarpX_DIMS=$d -DWarpX_LIB=ON
  cmake --build build -j 4
done

# Python package
PYWARPX_LIB_DIR=$PWD/build/lib python3 -m pip wheel .

# install
python3 -m pip install pywarpx-*whl

WarpX release managers might also want to generate a self-contained source package that can be distributed to exotic architectures:

python setup.py sdist --dist-dir .
python3 -m pip wheel -v pywarpx-*.tar.gz
python3 -m pip install *whl

The above steps can also be executed in one go to build from source on a machine:

python3 setup.py sdist --dist-dir .
python3 -m pip install -v pywarpx-*.tar.gz

Last but not least, you can uninstall pywarpx as usual with:

python3 -m pip uninstall pywarpx