24.17.1.3.1. gem5 DerivO3CPU pipeline stages
-
fetch: besides obviously fetching the instruction, this is also where branch prediction runs. Presumably because you need to branch predict before deciding what to fetch next.
-
retire: the instruction is completely and totally done with.
Mispeculated instructions never reach this stage as can be seen at: gem5 event queue DerivO3CPU syscall emulation freestanding example analysis: speculative.
The
ExecAllhappens at this time as well. And thereforeExecAlldoes not happen for mispeculated instructions.