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Unformatted text preview: tags to indicate these different values. Tags are bit patterns rather than symbolic names such as “%edx.1,” but they serve the same purpose. Processing of Operations by the Execution Unit
Figure 5.13 shows the operations in two forms: that generated by the instruction decoder and as a computation graph where operations are represented by rounded boxes and arrows indicate the passing of data between operations. We only show the arrows for the operands that change from one iteration to the next, since only these values are passed directly between functional units. The height of each operator box indicates how many cycles the operation requires, that is, the latency of that particular function. In this case, integer multiplication imull requires four cycles, load requires three, and the other operations require one. In demonstrating the timing of a loop, we position the blocks vertically to represent the times when operations are performed, with time increasing in the downward direction. We can see that the ﬁve operations for the loop form two parallel cha...
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- Spring '10
- The American