Og2ForVector
- Version: V2R2
- Status: OK
- Date: 2025/01/20
- commit：xxx
Overall design
Overall Block Diagram
Interface list
Refer to the interface documentation.
Function
For regular scalar instructions, after passing through the DataPath, they are directly sent to the BypassNetwork, where the final operands are generated via multiplexing. For vector computation and vector memory access instructions, since the timing for reading the vector register file is tighter than for scalars, and the vector execution unit has stringent timing requirements for the first cycle of data, an additional OG2 stage is introduced after the DataPath before entering the BypassNetwork for operand selection.
The Og2ForVector module only performs simple pipelining without logical operations. Whether an instruction can proceed to the OG2 stage depends solely on global cancellation. The Og2ForVector module contains the pipeline registers for the OG2 stage. Instructions in the OG1 stage can advance to OG2 if they do not encounter a load cancellation or redirection flush.
Another function of the Og2ForVector module is to send OG2-stage responses back to the issue queue. The OG2 stage does not have cancellations due to its own reasons. Whether an instruction can be successfully sent to the subsequent stage depends solely on whether the latter can accept it. If the subsequent stage cannot accept the instruction, it cannot proceed to the execution unit, and the issue queue is notified with a "block" status, indicating that the instruction needs to be reissued later. If the subsequent stage can accept the instruction, vector computation instructions are guaranteed to execute successfully, and the issue queue is notified with a "success" status, allowing the corresponding queue entry to be cleared. For vector memory access instructions, it is only after entering the memory execution unit that the success of execution can be determined. Here, the issue queue is simply notified with an "uncertain" status to remain unchanged, with subsequent clearance or reissue responses being handled by the execution unit.