Improving Processor Efficiency

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Background: Dr. Whalley's team has created  a data cache systems designed to enhance energy efficiency and performance of computing systems. A data filter cache herein may be designed to store a portion of data stored in a level one (L1) data cache. The data filter cache may reside between the L1 data cache and a register file in the primary compute unit. The data filter cache may therefore be accessed before the L1 data cache when a request for data is received and processed. Upon a data filter cache hit, access to the L1 data cache may be avoided. The smaller data filter cache may therefore be accessed earlier in the pipeline than the larger L1 data cache to promote improved energy utilization and performance. The data filter cache may also be accessed speculatively based on various conditions to increase the chances of having a data filter cache hit. Furthermore,  tagless access buffers (TABs) can optimize energy efficiency in various computing systems. Candidate memory references in an L1 data cache may be identified and stored in the TAB. Various techniques may be implemented for identifying the candidate references and allocating the references into the TAB. Groups of memory references may also be allocate to a single TAB entry or may be allocated to an extra TAB entry (such that two lines in the TAB may be used to store L1 data cache lines), for example, when a strided access pattern spans two consecutive L1 data cache lines. Certain other embodiments are related to data filter cache and multi-issue tagless hit instruction cache (TH-IC) techniques.