Pipelining

Structural Hazard

Data Hazard

Control Hazard

Pipelined Datapath and Control

  1. IF: Instruction Fetch
  2. ID: Instruction Decode and register file read
  3. EX: Execution or address calculation
  4. MEM: Data memory access
  5. WB: Write Back

Issues

  1. Write-back stage places the result back into the register file in the middle of the data path (Data Hazard)
  2. Selection of the next value of the PC, between incremented PC and branch address from the MEM stage (Control Hazard)

Data flow does not affect current instruction, but only influence later instructions.