Rust hides operations like register-register vpshufb behind unsafe despite this instruction having no implications for memory safety and crashing on CPUs that d

Rust hides operations like register-register vpshufb behind unsafe despite this instruction having no implications for memory safety and crashing on CPUs that don't support it (just like auto-vectorized "safe" code built for a different set of extensions than the CPU it's running on). Zig formerly exposed a subset of SIMD operations via LLVM intrinsics, but this was a bug and was fixed, so we now must use inline assembly to recreate immintrin.h and arm_neon.h.