Low cost instruction cache designs for tag comparison elimination

Abstract

Tag comparison elimination (TCE) is an effective approach to reduce I-cache energy. Current research focuses on finding good tradeoffs between hardware cost and percentage of comparisons that can be removed. For this purpose, two low cost innovations are proposed in this paper. We design a small dedicated TCE table whose size is flexible both horizontally (entry size) and vertically (number of entries). The design also minimizes interactions with the I-cache. For a 64-way 16K cache, the new design reduces the tag comparisons to 4.0% with a fraction only 20% of the hardware cost of the way memoization technique. The result is 40% better compared to a recent proposed low cost design of comparable hardware cost.