mem: refactor LRU cache tags and add random replacement tags

this patch implements a new tags class that uses a random replacement policy.
these tags prefer to evict invalid blocks first, if none are available a
replacement candidate is chosen at random.

this patch factors out the common code in the LRU class and creates a new
abstract class: the BaseSetAssoc class. any set associative tag class must
implement the functionality related to the actual replacement policy in the
following methods:

accessBlock()
findVictim()
insertBlock()
invalidate()

1 files changed, 3 insertions, 0 deletions

diff --git a/src/mem/cache/base.cc b/src/mem/cache/base.cc
index af324527f..dd1306270 100644
--- a/src/mem/cache/base.cc
+++ b/src/mem/cache/base.cc
@@ -49,6 +49,7 @@
 #include "debug/Drain.hh"
 #include "mem/cache/tags/fa_lru.hh"
 #include "mem/cache/tags/lru.hh"
+#include "mem/cache/tags/random_repl.hh"
 #include "mem/cache/base.hh"
 #include "mem/cache/cache.hh"
 #include "mem/cache/mshr.hh"
@@ -783,6 +784,8 @@ BaseCacheParams::create()
         if (numSets == 1)
             warn("Consider using FALRU tags for a fully associative cache\n");
         return new Cache<LRU>(this);
+    } else if (dynamic_cast<RandomRepl*>(tags)) {
+        return new Cache<RandomRepl>(this);
     } else {
         fatal("No suitable tags selected\n");
     }