Scoreboarding mechanism in a pipeline that includes replays and redirects

摘要

An apparatus for a processor includes a first scoreboard, a second scoreboard, and a control circuit coupled to the first scoreboard and the second scoreboard. The control circuit is configured to update the first scoreboard to indicate that a write is pending for a first destination register of a first instruction in response to issuing the first instruction into a first pipeline. The control circuit is configured to update the second scoreboard to indicate that the write is pending for the first destination register in response to the first instruction passing a first stage of the pipeline. Replay may be signaled for a given instruction at the first stage. In response to a replay of a second instruction, the control circuit is configured to copy a contents of the second scoreboard to the first scoreboard. In various embodiments, additional scoreboards may be used for detecting different types of dependencies.