mem-cache: Use ReplaceableEntry in findBlockBySetAndWay

With a sector cache you can't find a block using only its set
and way, as there is the sector offset to take into account. As
all of these blocks inherit from ReplaceableEntry, the return
type of this function has been updated.

This function has also been declared closer to findBlock() due
to their similar functionality.

Change-Id: I4730a2b4ebb5738f7fc118201e208a1b9c3ba8e8
Reviewed-on: https://gem5-review.googlesource.com/10141
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/mem/cache/tags/base.hh

@@ -195,6 +195,15 @@ class BaseTags : public ClockedObject
      */
     virtual CacheBlk * findBlock(Addr addr, bool is_secure) const = 0;
 
+    /**
+     * Find a block given set and way.
+     *
+     * @param set The set of the block.
+     * @param way The way of the block.
+     * @return The block.
+     */
+    virtual ReplaceableEntry* findBlockBySetAndWay(int set, int way) const = 0;
+
     /**
      * Align an address to the block size.
      * @param addr the address to align.
@@ -215,14 +224,6 @@ class BaseTags : public ClockedObject
         return (addr & blkMask);
     }
 
-    /**
-     * Find the cache block given set and way
-     * @param set The set of the block.
-     * @param way The way of the block.
-     * @return The cache block.
-     */
-    virtual CacheBlk *findBlockBySetAndWay(int set, int way) const = 0;
-
     /**
      * Limit the allocation for the cache ways.
      * @param ways The maximum number of ways available for replacement.

src/mem/cache/tags/base_set_assoc.cc

@@ -126,7 +126,7 @@ BaseSetAssoc::findBlock(Addr addr, bool is_secure) const
     return blk;
 }
 
-CacheBlk*
+ReplaceableEntry*
 BaseSetAssoc::findBlockBySetAndWay(int set, int way) const
 {
     return sets[set].blks[way];

src/mem/cache/tags/base_set_assoc.hh

@@ -129,14 +129,6 @@ class BaseSetAssoc : public BaseTags
      */
     void invalidate(CacheBlk *blk) override;
 
-    /**
-     * Find the cache block given set and way
-     * @param set The set of the block.
-     * @param way The way of the block.
-     * @return The cache block.
-     */
-    CacheBlk *findBlockBySetAndWay(int set, int way) const override;
-
     /**
      * Access block and update replacement data. May not succeed, in which case
      * nullptr is returned. This has all the implications of a cache
@@ -198,6 +190,15 @@ class BaseSetAssoc : public BaseTags
      */
     CacheBlk* findBlock(Addr addr, bool is_secure) const override;
 
+    /**
+     * Find a block given set and way.
+     *
+     * @param set The set of the block.
+     * @param way The way of the block.
+     * @return The block.
+     */
+    ReplaceableEntry* findBlockBySetAndWay(int set, int way) const override;
+
     /**
      * Find replacement victim based on address.
      *

src/mem/cache/tags/fa_lru.cc

@@ -185,7 +185,7 @@ FALRU::findBlock(Addr addr, bool is_secure) const
     return blk;
 }
 
-CacheBlk*
+ReplaceableEntry*
 FALRU::findBlockBySetAndWay(int set, int way) const
 {
     assert(set == 0);

src/mem/cache/tags/fa_lru.hh

@@ -185,6 +185,15 @@ class FALRU : public BaseTags
      */
     CacheBlk* findBlock(Addr addr, bool is_secure) const override;
 
+    /**
+     * Find a block given set and way.
+     *
+     * @param set The set of the block.
+     * @param way The way of the block.
+     * @return The block.
+     */
+    ReplaceableEntry* findBlockBySetAndWay(int set, int way) const override;
+
     /**
      * Find replacement victim based on address.
      *
@@ -201,14 +210,6 @@ class FALRU : public BaseTags
      */
     void insertBlock(PacketPtr pkt, CacheBlk *blk) override;
 
-    /**
-     * Find the cache block given set and way
-     * @param set The set of the block.
-     * @param way The way of the block.
-     * @return The cache block.
-     */
-    CacheBlk* findBlockBySetAndWay(int set, int way) const override;
-
     /**
      * Generate the tag from the addres. For fully associative this is just the
      * block address.