Cache which provides partial tags from non-predicted ways to direct search if way prediction misses

Abstract

A cache is coupled to receive an input address and a corresponding way prediction. The cache provides output bytes in response to the predicted way (instead of, performing tag comparisons to select the output bytes). Furthermore, a tag may be read from the predicted way and only partial tags are read from the non-predicted ways. The tag is compared to the tag portion of the input address, and the partial tags are compared to a corresponding partial tag portion of the input address. If the tag matches the tag portion of the input address, a hit in the predicted way is detected and the bytes provided in response to the predicted way are correct. If the tag does not match the tag portion of the input address, a miss in the predicted way is detected. If none of the partial tags match the corresponding partial tag portion of the input address, a miss in the cache is determined. On the other hand, if one or more of the partial tags match the corresponding partial tags portion of the input address, the cache searches the corresponding ways to determine whether or not the input address hits or misses in the cache.