The trace cache (2)
Each line stores a snapshot, or trace, of the dynamic instruction stream.
The trace construction is of the critical path.
As a group of instructions is processed, it is latched into the fill unit.
The fill unit maximizes the size of the segment and finalizes a segment when the segment can be expanded no further.
- The number of instructions within a trace is limited by the trace cache line size.
- Finalized segments are written into the trace cache.
Instructions can be sent from the trace cache into the reservation stations (??) without having to undergo a large amount of processing and rerouting.
- It is under research if the instructions in the Trace cache are
- fetched but not yet decoded
- decoded but not yet renamed
- or decoded and partly renamed
- Trace cache placement in the microarchitecture is dependent on this decision.