Frontier (OLCF): cupy (ECP-WarpX#4247)

Documenting cupy installation for Frontier.

Tools/machines/frontier-olcf/install_dependencies.sh

@@ -90,7 +90,10 @@ python3 -m pip install --upgrade build
 python3 -m pip install --upgrade packaging
 python3 -m pip install --upgrade wheel
 python3 -m pip install --upgrade setuptools
-python3 -m pip install --upgrade cython
+# cupy and h5py need an older Cython
+# https://github.com/cupy/cupy/issues/4610
+# https://github.com/h5py/h5py/issues/2268
+python3 -m pip install --upgrade "cython<3.0"
 python3 -m pip install --upgrade numpy
 python3 -m pip install --upgrade pandas
 python3 -m pip install --upgrade scipy
@@ -100,6 +103,14 @@ python3 -m pip install --upgrade matplotlib
 python3 -m pip install --upgrade yt
 # install or update WarpX dependencies such as picmistandard
 python3 -m pip install --upgrade -r $HOME/src/warpx/requirements.txt
+# cupy for ROCm
+#   https://docs.cupy.dev/en/stable/install.html#building-cupy-for-rocm-from-source
+#   https://github.com/cupy/cupy/issues/7830
+CC=cc CXX=CC \
+CUPY_INSTALL_USE_HIP=1  \
+ROCM_HOME=${ROCM_PATH}  \
+HCC_AMDGPU_TARGET=${AMREX_AMD_ARCH}  \
+  python3 -m pip install -v cupy
 # optional: for libEnsemble
 python3 -m pip install -r $HOME/src/warpx/Tools/LibEnsemble/requirements.txt
 # optional: for optimas (based on libEnsemble & ax->botorch->gpytorch->pytorch)