https://doc.rust-lang.org/nightly/core/arch/x86/fn._mm512_castpd512_pd256.html
_mm512_castpd512_pd256 in core::arch::x86 - Rust
Cast vector of type __m512d to type __m256d. This intrinsic is only used for compilation and does not generate any instructions, thus it has zero latency.
corearchrust