[Bug target/65671] Assembly failure (invalid register operand) with -O3 -mavx512vl

[kyukhin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65671

--- Comment #1 from Kirill Yukhin <kyukhin at gcc dot gnu.org> ---
Confirmed. 

Workaround: add `-mavx512dq' option, which will enable vextractf64x2 w/ 256b
registers.