Add a simple space charge benchmark for FFTX. #3920

	name: 🐧 HIP

	on: [push, pull_request]

	concurrency:
	group: ${{ github.ref }}-${{ github.head_ref }}-hip
	cancel-in-progress: true

	jobs:
	build_hip:
	name: HIP
	runs-on: ubuntu-20.04
	env:
	CXXFLAGS: "-Werror -Wno-deprecated-declarations -Wno-error=pass-failed"
	CMAKE_GENERATOR: Ninja
	if: github.event.pull_request.draft == false
	steps:
	- uses: actions/checkout@v4

	- name: install dependencies
	shell: bash
	run: .github/workflows/dependencies/hip-openmpi.sh

	- name: CCache Cache
	uses: actions/cache@v4
	# - once stored under a key, they become immutable (even if local cache path content changes)
	# - for a refresh the key has to change, e.g., hash of a tracked file in the key
	with:
	path: \|
	~/.ccache
	~/.cache/ccache
	key: ccache-hip-clang-${{ hashFiles('.github/workflows/hip.yml') }}-${{ hashFiles('cmake/dependencies/ABLASTR.cmake') }}
	restore-keys: \|
	ccache-hip-clang-${{ hashFiles('.github/workflows/hip.yml') }}-
	ccache-hip-clang-

	- name: build ImpactX
	shell: bash
	run: \|
	source /etc/profile.d/rocm.sh
	hipcc --version
	which clang
	which clang++
	export CXX=$(which clang++)
	export CC=$(which clang)

	# "mpic++ --showme" forgets open-pal in Ubuntu 20.04 + OpenMPI 4.0.3
	# https://bugs.launchpad.net/ubuntu/+source/openmpi/+bug/1941786
	# https://github.com/open-mpi/ompi/issues/9317
	export LDFLAGS="-lopen-pal"

	cmake -S . -B build \
	-DCMAKE_VERBOSE_MAKEFILE=ON \
	-DAMReX_AMD_ARCH=gfx900 \
	-DImpactX_COMPUTE=HIP \
	-DImpactX_FFT=ON \
	-DImpactX_PYTHON=ON
	cmake --build build -j 4

Provide feedback