Hardware techniques to enhance ILP

• At the ISA level

  • Conditional or predicated instructions (eliminates branches)

• Speculation

  • Execute an instruction before knowing whether it is needed
  • Can be done at the compiler level (move code across basic blocks)
  • Can be done at the hardware level (branch prediction)
  • Be sure to get the correct results and not to generate exceptions during the speculation

• Register renaming

  • Removes more WAR and WAW hazards

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