LINKED_REGS_MAX
static_assert(LINKED_REGS_MAX < (1 << LR_SIZE_BITS));
static_assert(LINKED_REGS_MAX * LR_ENTRY_BITS + LR_SIZE_BITS <= 64);
struct linked_reg entries[LINKED_REGS_MAX];
if (s->cnt < LINKED_REGS_MAX)