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Trace cache efficiency faces many performance limits: indexability, duplication, and fragmentation. Indexability provides information about the presence of a trace; trace lookup is done by using the start address of the first basic block and prediction information, a miss may occur because it is not possible to access interior basic blocks. Duplication measures trace cache efficiency in utilizing the available storage. Duplication is a consequence of the method used for trace cache indexing. A given basic block may begin a trace and also appear as an interior member of many traces. Fragmentation indicates trace cache efficiency in storing instructions, it describes the portion of the trace cache that is unused; this happens when a trace reaches the prediction bandwidth m before filling the whole available trace slots.

A new indexing method was added to the trace cache to gain more performance and throughput, as a …