gromacs: add sve variant on aarch64 (#35614)

var/spack/repos/builtin/packages/gromacs/package.py

@@ -113,6 +113,15 @@ class Gromacs(CMakePackage):
         "+mdrun_only", when="@2021:", msg="mdrun-only build option was removed for GROMACS 2021."
     )
     variant("openmp", default=True, description="Enables OpenMP at configure time")
+    variant(
+        "sve",
+        default=True,
+        description="Enable SVE on aarch64 if available",
+        when="target=neoverse_v1",
+    )
+    variant(
+        "sve", default=True, description="Enable SVE on aarch64 if available", when="target=a64fx"
+    )
     variant(
         "relaxed_double_precision",
         default=False,
@@ -450,6 +459,8 @@ def cmake_args(self):
             # ARMv8
             if self.spec.satisfies("%nvhpc"):
                 options.append("-DGMX_SIMD=None")
+            elif "sve" in target.features and "+sve" in self.spec:
+                options.append("-DGMX_SIMD=ARM_SVE")
             else:
                 options.append("-DGMX_SIMD=ARM_NEON_ASIMD")
         elif target == "mic_knl":