https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107304
--- Comment #17 from H.J. Lu <hjl.tools at gmail dot com> ---
Since this type
typedef struct {
unsigned char v __attribute__((aligned(256))) __attribute__
((vector_size(64 * sizeof(unsigned char))));
} stress_vec_u8_64_t;
is processed outside of the function and AVX512 is enabled by default, it
has V64QImode instead of BLKmode. If the target attribute disables AVX512,
V64QImode becomes unusable.
