It'd be great if Miri would support at least a reasonable subset of Rust's portable SIMD API -- and from what I heard in the past, that is much more feasible than supporting things from core::arch. Now that rust-lang/rust#89167 has landed I'd like to add corresponding tests in Miri to ensure we cover the required intrinsics.

@workingjubilee what would be a good small-ish set of tests to start with here, that cover as much of the underlying support infrastructure as possible?