Resume buffer

• In some “old” machines (e.g., IBM 360/91 circa 1967), branch prediction was implemented by fetching both paths (limited to 1 branch)

• Similar idea: “resume buffer” in MIPS R10000.

  • If branch predicted taken, it takes one cycle to compute and fetch the target
  • During that cycle save the NT sequential instruction in a buffer (4 entries of 4 instructions each).
  • If mispredict, reload from the “resume buffer” thus saving one cycle

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