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40 * Authors: Erik Hallnor
45 * Declaration of a base set associative tag store.
48 #ifndef __MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__
49 #define __MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__
55 #include "base/logging.hh"
56 #include "base/types.hh"
57 #include "mem/cache/base.hh"
58 #include "mem/cache/blk.hh"
59 #include "mem/cache/replacement_policies/base.hh"
60 #include "mem/cache/tags/base.hh"
61 #include "mem/cache/tags/indexing_policies/base.hh"
62 #include "params/BaseSetAssoc.hh"
65 * A basic cache tag store.
66 * @sa \ref gem5MemorySystem "gem5 Memory System"
68 * The BaseSetAssoc placement policy divides the cache into s sets of w
71 class BaseSetAssoc : public BaseTags
74 /** The allocatable associativity of the cache (alloc mask). */
77 /** The cache blocks. */
78 std::vector<CacheBlk> blks;
80 /** Whether tags and data are accessed sequentially. */
81 const bool sequentialAccess;
83 /** Replacement policy */
84 BaseReplacementPolicy *replacementPolicy;
87 /** Convenience typedef. */
88 typedef BaseSetAssocParams Params;
91 * Construct and initialize this tag store.
93 BaseSetAssoc(const Params *p);
98 virtual ~BaseSetAssoc() {};
101 * Initialize blocks and set the parent cache back pointer.
103 * @param _cache Pointer to parent cache.
105 void init(BaseCache *_cache) override;
108 * This function updates the tags when a block is invalidated. It also
109 * updates the replacement data.
111 * @param blk The block to invalidate.
113 void invalidate(CacheBlk *blk) override;
116 * Access block and update replacement data. May not succeed, in which case
117 * nullptr is returned. This has all the implications of a cache
118 * access and should only be used as such. Returns the access latency as a
120 * @param addr The address to find.
121 * @param is_secure True if the target memory space is secure.
122 * @param lat The access latency.
123 * @return Pointer to the cache block if found.
125 CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) override
127 CacheBlk *blk = findBlock(addr, is_secure);
129 // Access all tags in parallel, hence one in each way. The data side
130 // either accesses all blocks in parallel, or one block sequentially on
131 // a hit. Sequential access with a miss doesn't access data.
132 tagAccesses += allocAssoc;
133 if (sequentialAccess) {
134 if (blk != nullptr) {
138 dataAccesses += allocAssoc;
141 if (blk != nullptr) {
144 // Check if the block to be accessed is available. If not,
145 // apply the accessLatency on top of block->whenReady.
146 if (blk->whenReady > curTick() &&
147 cache->ticksToCycles(blk->whenReady - curTick()) >
149 lat = cache->ticksToCycles(blk->whenReady - curTick()) +
153 // Update number of references to accessed block
156 // Update replacement data of accessed block
157 replacementPolicy->touch(blk->replacementData);
167 * Find replacement victim based on address. The list of evicted blocks
168 * only contains the victim.
170 * @param addr Address to find a victim for.
171 * @param is_secure True if the target memory space is secure.
172 * @param evict_blks Cache blocks to be evicted.
173 * @return Cache block to be replaced.
175 CacheBlk* findVictim(Addr addr, const bool is_secure,
176 std::vector<CacheBlk*>& evict_blks) const override
178 // Get possible entries to be victimized
179 const std::vector<ReplaceableEntry*> entries =
180 indexingPolicy->getPossibleEntries(addr);
182 // Choose replacement victim from replacement candidates
183 CacheBlk* victim = static_cast<CacheBlk*>(replacementPolicy->getVictim(
186 // There is only one eviction for this replacement
187 evict_blks.push_back(victim);
193 * Insert the new block into the cache and update replacement data.
195 * @param addr Address of the block.
196 * @param is_secure Whether the block is in secure space or not.
197 * @param src_master_ID The source requestor ID.
198 * @param task_ID The new task ID.
199 * @param blk The block to update.
201 void insertBlock(const Addr addr, const bool is_secure,
202 const int src_master_ID, const uint32_t task_ID,
203 CacheBlk *blk) override
206 BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk);
208 // Increment tag counter
211 // Update replacement policy
212 replacementPolicy->reset(blk->replacementData);
216 * Limit the allocation for the cache ways.
217 * @param ways The maximum number of ways available for replacement.
219 virtual void setWayAllocationMax(int ways) override
221 fatal_if(ways < 1, "Allocation limit must be greater than zero");
226 * Get the way allocation mask limit.
227 * @return The maximum number of ways available for replacement.
229 virtual int getWayAllocationMax() const override
235 * Regenerate the block address from the tag and indexing location.
237 * @param block The block.
238 * @return the block address.
240 Addr regenerateBlkAddr(const CacheBlk* blk) const override
242 return indexingPolicy->regenerateAddr(blk->tag, blk);
245 void forEachBlk(std::function<void(CacheBlk &)> visitor) override {
246 for (CacheBlk& blk : blks) {
251 bool anyBlk(std::function<bool(CacheBlk &)> visitor) override {
252 for (CacheBlk& blk : blks) {
261 #endif //__MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__