Optimizing compiler having data cache prefetch spreading

Abstract

A method of scheduling prefetch instructions in a compiler is described that improves performance by minimizing the performance degradation due to dirty cache misses. The method determines the length N of a loop (step 66). The number of prefetch instructions were M within that loop are then determined (step 68). A prefetch spacing P is then calculated according to the formula P=N/M, where the length of the loop is expressed in cycles (step 70). This prefetch spacing is then attached to each prefetch instruction and the instruction scheduler schedules the prefetch instructions so as to space the prefetch instructions apart by approximately the prefetch spacing P (step 72). After the scheduler arranged for P cycles, a prefetch instruction will be assigned a higher priority for scheduling in the next lot.

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