Re-order buffer 重排序缓冲区
(重定向自Reorder buffer)
A re-order buffer (ROB) is used in a Tomasulo algorithm for out-of-order instruction execution. It allows instructions to be committed in-order.
Normally, there are three stages of instructions: "Issue", "Execute", "Write Result". In Tomasulo algorithm, there is an additional stage "Commit". In this stage, the results of instructions will be stored in a register or memory. In the "Write Result" stage, the results are just put in the re-order buffer. All contents in this buffer can then be used when executing other instructions depending on these.