WILDCOPY_VECLEN
if (ovtype == ZSTD_overlap_src_before_dst && diff < WILDCOPY_VECLEN) {
assert(diff >= WILDCOPY_VECLEN || diff <= -WILDCOPY_VECLEN);
if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
assert(sequence.offset < WILDCOPY_VECLEN);
if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
assert(sequence.offset < WILDCOPY_VECLEN);
if (op <= oend - WILDCOPY_OVERLENGTH && diff < -WILDCOPY_VECLEN) {