Forwarding

• Result of ALU operation is known at end of EXE stage

• Forwarding between:

  • EXE/MEM pipeline register to ALUinput for instructions i and i+1
  • MEM/WB pipeline register to ALUinput for instructions i and i+2
    • Note that if the same register has to be forwarded, forward the last one to be written
  • Forwarding through register file (write 1st half of cycle, read 2nd half of cycle)

• Forwarding between load and store (memory copy)

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