Detecting a Hazard

• The EXECUTE entity must look at in src1, src2 values and compare them against dest values from the other inputs.

  • Comparison order is IMPORTANT. Must compare mpacket, then wpacket, then rpacket.

• Some special cases:

  • If dest value is 0, (indicates r0), no need to forward because r0 never changes.
  • If mpacket opcode is Load or Store, NEVER forward (dest value is never produced by execute unit)
  • If wpacket opcode is Load, need to use mem_data value!
  • If rpacket write_flag is false, never forward!

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