For example in cycle 3 of the graph of figure 515 we

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Unformatted text preview: dicted, the instruction can be retired, with any updates to the program registers being made. If some branch point leading to this instruction was mispredicted, on the other hand, the instruction will be flushed, discarding any results that may have been computed. By this means, mispredictions will not alter the program state. As we have described, any updates to the program registers occur only as instructions are being retired, and this takes place only after the processor can be certain that any branches leading to this instruction have been correctly predicted. To expedite the communication of results from one instruction to another, much of this information is exchanged among the execution units, shown in the figure as “Operation Results.” As the arrows in the figure show, the execution units can send results directly to each other. The most common mechanism for controlling the communication of operands among the execution units is called register renaming. When an instructio...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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