mem-cache: Create tags initialization function

Having the blocks initialized in the constructor makes it harder
to apply inheritance in the tags classes. This patch decouples
the block initialization functionality from the constructor by
using an init() function. It also sets the parent cache.

Change-Id: I0da7fdaae492b1177c7cc3bda8639f79921fbbeb
Reviewed-on: https://gem5-review.googlesource.com/c/11509
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

src/mem/cache/base.cc

@@ -115,7 +115,7 @@ BaseCache::BaseCache(const BaseCacheParams *p, unsigned blk_size)
 
     tempBlock = new TempCacheBlk(blkSize);
 
-    tags->setCache(this);
+    tags->init(this);
     if (prefetcher)
         prefetcher->setCache(this);
 }

src/mem/cache/tags/base.hh

@@ -154,6 +154,13 @@ class BaseTags : public ClockedObject
      * @}
      */
 
+    /**
+     * Set the parent cache back pointer.
+     *
+     * @param _cache Pointer to parent cache.
+     */
+    void setCache(BaseCache *_cache);
+
   public:
     typedef BaseTagsParams Params;
     BaseTags(const Params *p);
@@ -164,10 +171,11 @@ class BaseTags : public ClockedObject
     virtual ~BaseTags() {}
 
     /**
-     * Set the parent cache back pointer.
+     * Initialize blocks and set the parent cache back pointer.
+     *
      * @param _cache Pointer to parent cache.
      */
-    void setCache(BaseCache *_cache);
+    virtual void init(BaseCache *_cache) = 0;
 
     /**
      * Register local statistics.

src/mem/cache/tags/base_set_assoc.cc

@@ -73,7 +73,15 @@ BaseSetAssoc::BaseSetAssoc(const Params *p)
     setShift = floorLog2(blkSize);
     setMask = numSets - 1;
     tagShift = setShift + floorLog2(numSets);
+}
 
+void
+BaseSetAssoc::init(BaseCache* cache)
+{
+    // Set parent cache
+    setCache(cache);
+
+    // Initialize blocks
     unsigned blkIndex = 0;       // index into blks array
     for (unsigned i = 0; i < numSets; ++i) {
         sets[i].assoc = assoc;

src/mem/cache/tags/base_set_assoc.hh

@@ -120,6 +120,13 @@ class BaseSetAssoc : public BaseTags
      */
     virtual ~BaseSetAssoc() {};
 
+    /**
+     * Initialize blocks and set the parent cache back pointer.
+     *
+     * @param _cache Pointer to parent cache.
+     */
+    void init(BaseCache *_cache) override;
+
     /**
      * This function updates the tags when a block is invalidated. It also
      * updates the replacement data.

src/mem/cache/tags/fa_lru.cc

@@ -69,6 +69,18 @@ FALRU::FALRU(const Params *p)
         fatal("Cache Size must be power of 2 for now");
 
     blks = new FALRUBlk[numBlocks];
+}
+
+FALRU::~FALRU()
+{
+    delete[] blks;
+}
+
+void
+FALRU::init(BaseCache* cache)
+{
+    // Set parent cache
+    setCache(cache);
 
     head = &(blks[0]);
     head->prev = nullptr;
@@ -97,11 +109,6 @@ FALRU::FALRU(const Params *p)
     cacheTracking.init(head, tail);
 }
 
-FALRU::~FALRU()
-{
-    delete[] blks;
-}
-
 void
 FALRU::regStats()
 {

src/mem/cache/tags/fa_lru.hh

@@ -68,6 +68,7 @@
 // TrackedCaches class
 //#define FALRU_DEBUG
 
+class BaseCache;
 class ReplaceableEntry;
 
 // A bitmask of the caches we are keeping track of. Currently the
@@ -150,6 +151,13 @@ class FALRU : public BaseTags
     FALRU(const Params *p);
     ~FALRU();
 
+    /**
+     * Initialize blocks and set the parent cache back pointer.
+     *
+     * @param _cache Pointer to parent cache.
+     */
+    void init(BaseCache *_cache) override;
+
     /**
      * Register the stats for this object.
      */

src/mem/cache/tags/sector_tags.cc

@@ -67,6 +67,13 @@ SectorTags::SectorTags(const SectorTagsParams *p)
     fatal_if(!isPowerOf2(numBlocksPerSector),
              "# of blocks per sector must be non-zero and a power of 2");
     fatal_if(assoc <= 0, "associativity must be greater than zero");
+}
+
+void
+SectorTags::init(BaseCache* cache)
+{
+    // Set parent cache
+    setCache(cache);
 
     // Initialize all sets
     unsigned sec_blk_index = 0;   // index into sector blks array

src/mem/cache/tags/sector_tags.hh

@@ -43,6 +43,7 @@
 #include "mem/cache/tags/base.hh"
 #include "params/SectorTags.hh"
 
+class BaseCache;
 class BaseReplacementPolicy;
 class ReplaceableEntry;
 
@@ -113,6 +114,13 @@ class SectorTags : public BaseTags
      */
     virtual ~SectorTags() {};
 
+    /**
+     * Initialize blocks and set the parent cache back pointer.
+     *
+     * @param _cache Pointer to parent cache.
+     */
+    void init(BaseCache *_cache) override;
+
     /**
      * This function updates the tags when a block is invalidated but does
      * not invalidate the block itself. It also updates the replacement data.