Perform a serializing operation on all load-from-memory instructions that were issued prior
to this instruction. Guarantees that every load instruction that precedes, in program order,
is globally visible before any load instruction which follows the fence in program order.
Perform a serializing operation on all load-from-memory instructions that were issued prior to this instruction. Guarantees that every load instruction that precedes, in program order, is globally visible before any load instruction which follows the fence in program order.