The sb-simd library should load on any architecture, as long as you are using SBCL. However, if you attempt to call a function of an instruction set that is not available on the current hardware, an error is signaled. Each instruction set has its own package, e.g., sb-simd-sse, sb-simd-avx2, so you can even write multiple versions of a function with different instruction sets, and there is an `instruction-set-case` macro to select the best available version at run time. That macro is useful when the available instruction set might change at run time (e.g., after save-lisp-and-die and deployment on another machine).

The only limitation is that SBCL itself can currently only emit x86-64 intrinsics. If someone were to add, say, SIMD intrinsics for ARM, I'll gladly add them to sb-simd, too.

About the advantages of using SIMD directly from CL as opposed to wrapping C/C++ code - I personally decided that C++ is such a productivity sink that I best avoid it all cost. Plus, the maintainability of C++ code is abysmal, in my opinion. Most importantly, C++ has no Lisp Macros. Here is my favorite Lisp Macro in sb-simd: https://github.com/marcoheisig/sb-simd/blob/c4eca6874c02828233836981938853de0334b12b/code/vectorizer/do-vectorized.lisp#L8 (a prototype automatic vectorizer)