Chapter 4 Introduction
Chapter 4 Introduction
Chapter 4 Introduction
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Morgan Kaufmann Publishers 31 January 2013Load-Use Hazard Detectionn Check when using instruction is decodedin ID stagen ALU operand register numbers in ID stageare given byn IF/ID.RegisterRs, IF/ID.RegisterRtn Load-use hazard whenn ID/EX.MemRead and((ID/EX.RegisterRt = IF/ID.RegisterRs) or(ID/EX.RegisterRt = IF/ID.RegisterRt))n If detected, stall and insert bubbleCSE 420 <strong>Chapter</strong> 4 — The Processor — 77How to Stall the Pipelinen Force control values in ID/EX registerto 0n EX, MEM and WB do nop (no-operation)n Prevent update of PC and IF/ID registern Using instruction is decoded againn Following instruction is fetched againn 1-cycle stall allows MEM to read data for lwn Can subsequently forward to EX stageCSE 420 <strong>Chapter</strong> 4 — The Processor — 78
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