Instruction commit step
Need of a mechanism to:
- Know when an instruction has completed non-speculatively
- Know whether the result of an instruction is correct
- “Complete”instructions in order. This commits the instruction (easy in single pipeline since commit is last stage of the pipe)
Note that in Tomasulo’s solution
- An instruction completes as soon as it has finished executing (i.e., result put in register unless there is a WAW condition)
- Leads necessarily to imprecise exceptions (unless handled by software tests)