spatter: new package (#50326)

* add spatter package
* update license, change default backend
* move package to new location
* rearrage spack directives

---------

Co-authored-by: Patrick Lavin <prlavin@sandia.gov>
Co-authored-by: plavin <plavin@users.noreply.github.com>

var/spack/repos/spack_repo/builtin/packages/spatter/package.py

@@ -0,0 +1,54 @@
+# Copyright Spack Project Developers. See COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+
+class Spatter(CMakePackage, CudaPackage):
+    """A microbenchmark for timing Gather/Scatter kernels on CPUs and GPUs."""
+
+    homepage = "https://github.com/hpcgarage/spatter"
+    git = "https://github.com/hpcgarage/spatter.git"
+
+    maintainers("plavin", "jyoung3131")
+
+    license("MIT", checked_by="plavin")
+
+    version("develop", branch="spatter-devel")
+    version("main", branch="main", preferred=True)
+    version("2.1", tag="v2.1", commit="ec8923711f8dc21eedff7189f12b02eb06845d2f")
+
+    variant(
+        "backend",
+        default="openmp",
+        values=["serial", "openmp", "cuda"],
+        description="Configuration string",
+    )
+    variant("mpi", default=False, description="Enable MPI support")
+    variant("cuda_arch", default="none", multi=True, description="CUDA architecture")
+
+    depends_on("cmake@3.25:", type="build")
+    depends_on("mpi", when="+mpi")
+    depends_on("cuda", when="backend=cuda")
+
+    conflicts(
+        "backend=cuda",
+        when="cuda_arch=none",
+        msg="CUDA architecture must be specified when CUDA support is enabled.",
+    )
+
+    def cmake_args(self):
+        args = []
+
+        if self.spec.satisfies("backend=openmp"):
+            args.append(self.define("USE_OPENMP", "On"))
+        elif self.spec.satisfies("backend=cuda"):
+            args.append(self.define("USE_CUDA", "On"))
+            args.append(
+                self.define("CMAKE_CUDA_ARCHITECTURES", self.spec.variants["cuda_arch"].value)
+            )
+
+        args.append(self.define_from_variant("USE_MPI", "mpi"))
+
+        return args