Question

Provide detailed description of Pipeline Control Logic in the context of four control cases.
[5 Marks]​

Answer 1

Answer:

The four control cases in pipeline architecture are :

1. Processing ret:

The pipeline must stall until the ret instruction reaches the

write-back stage

2. Load/user hazards:

The pipeline must stall for one cycle between an instruction

that reads a value from memory and an instruction that uses this value.

3. Mispredicted branches:

By the time the branch logic detects that a jump should

not have been taken, several instructions at the branch target will have

started down the pipeline. These instructions must be removed from the

pipeline.

4. Exceptions:

When an instruction causes an exception, we want to disable the

updating of the programmer-visible state by later instructions and halt

execution once the excepting instruction reaches the write-back stage.

You can get detailed information about them in the book COMPUTER SYSTEMS A Programmmer's Perspective by Randal E.Bryant David R.O'Hallaron

Good Luck