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Unformatted text preview: iler, the general principles also apply to other machine and compiler combinations. Of course, the optimal strategy may be very machine dependent. As an example, Figure 5.28 shows performance results for a Compaq Alpha 21164 processor for conditions comparable to those for a Pentium III shown in Figure 5.27. These measurements were taken for code generated by the Compaq C compiler, which applies more advanced optimizations than GCC. Observe how the cycle times generally decline as we move down the table, just as they did for the other machine. We see that we can effectively exploit a higher (eight-way) degree of parallelism, because the Alpha has 32 integer and 32 ﬂoating-point registers. As this example illustrates, the general principles of program optimization apply to a variety of different machines, even if the particular combination of features leading to optimum performance depend on the speciﬁc machine. 5.12 Branch Prediction and Misprediction Penalties
As we have mentioned, modern processors work well ahead of the currently executing instructions, reading new instruct...
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