Tag Pipeline
The portion of a cache pipeline responsible for reading tags and checking whether the requested address matches a stored cache line.
Detailed Explanation
The tag pipeline is the control-heavy side of cache access. After the address indexes a set, the cache reads the tags stored for each way in that set and compares them against the requested address tag. If one way matches and the line is valid, the access is a hit. If none match, the cache reports a miss and hands control to refill logic.
Tag processing is where many correctness decisions happen: valid-bit checks, hit-way selection, replacement-way choice, and sometimes permission or coherence-state checks. Even when the data array is large, the tag path can still be timing critical because it feeds hit/miss decisions that determine what the processor should do next.