mem-ruby: Allow Ruby to use all replacement policies in Classic

Add support in Ruby to use all replacement policies in Classic.
Furthermore, if new replacement policies are added to the
Classic system, the Ruby system will recognize new policies
without any other changes in Ruby system. The following list
all the major changes:

  * Make Ruby cache entries (AbstractCacheEntry) inherit from
    Classic cache entries (ReplaceableEntry). By doing this,
    replacement policies can use cache entries from Ruby caches.
    AccessPermission and print function are moved from
    AbstractEntry to AbstractCacheEntry, so AbstractEntry is no
    longer needed.

  * DirectoryMemory and all SLICC files are changed to use
    AbstractCacheEntry as their cache entry interface. So do the
    python files in mem/slicc/ast which check the entry
    interface.

  * "main='false'" argument is added to the protocol files where
    the DirectoryEntry is defined. This change helps
    differentiate DirectoryEntry from CacheEntry because they are
    both the instances of AbstractCacheEntry now.

  * Use BaseReplacementPolicy in Ruby caches instead of
    AbstractReplacementPolicy so that Ruby caches will recognize
    the replacement policies from Classic.

  * Add getLastAccess() and useOccupancy() function to Classic
    system so that Ruby caches can use them. Move lastTouchTick
    to ReplacementData struct because it's needed by
    getLastAccess() to return the correct value.

  * Add a 2-dimensional array of ReplacementData in Ruby caches
    to store information for different replacement policies. Note
    that, unlike Classic caches, where policy information is
    stored in cache entries, the policy information needs to be
    stored in a new 2-dimensional array. This is due to Ruby
    caches deleting the cache entry every time the corresponding
    cache line get evicted.

Change-Id: Idff6fdd2102a552c103e9d5f31f779aae052943f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20879
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

4 files changed, 15 insertions, 10 deletions

diff --git a/src/mem/slicc/ast/FormalParamAST.py b/src/mem/slicc/ast/FormalParamAST.py
index ce73304f1..778b5c1aa 100644
--- a/src/mem/slicc/ast/FormalParamAST.py
+++ b/src/mem/slicc/ast/FormalParamAST.py
@@ -53,9 +53,10 @@ class FormalParamAST(AST):
         self.symtab.newSymbol(v)
 
         if self.pointer or str(type) == "TBE" or (
+        # Check whether type is entry by checking the interface since
+        # in protocol files, entries use AbstractCacheEntry as interfaces.
            "interface" in type and (
-               type["interface"] == "AbstractCacheEntry" or
-               type["interface"] == "AbstractEntry")):
+               type["interface"] == "AbstractCacheEntry")):
             return type, "%s* %s" % (type.c_ident, param)
         else:
             return type, "const %s& %s" % (type.c_ident, param)
diff --git a/src/mem/slicc/ast/LocalVariableAST.py b/src/mem/slicc/ast/LocalVariableAST.py
index 5c6bfe80a..c1a5fdbd9 100644
--- a/src/mem/slicc/ast/LocalVariableAST.py
+++ b/src/mem/slicc/ast/LocalVariableAST.py
@@ -61,9 +61,10 @@ class LocalVariableAST(StatementAST):
                 self.pairs)
         self.symtab.newSymbol(v)
         if self.pointer or str(type) == "TBE" or (
+        # Check whether type is Entry by checking interface since
+        # entries in protocol files use AbstractCacheEntry as interfaces.
            "interface" in type and (
-               type["interface"] == "AbstractCacheEntry" or
-               type["interface"] == "AbstractEntry")):
+               type["interface"] == "AbstractCacheEntry")):
             code += "%s* %s" % (type.c_ident, ident)
         else:
             code += "%s %s" % (type.c_ident, ident)
diff --git a/src/mem/slicc/ast/MemberExprAST.py b/src/mem/slicc/ast/MemberExprAST.py
index 320146065..50151bd0a 100644
--- a/src/mem/slicc/ast/MemberExprAST.py
+++ b/src/mem/slicc/ast/MemberExprAST.py
@@ -41,10 +41,13 @@ class MemberExprAST(ExprAST):
         return_type, gcode = self.expr_ast.inline(True)
         fix = code.nofix()
 
+
+        # Check whether return_type is Entry by checking
+        # interfaces since entries in protocol files use
+        # AbstractCacheEntry as interfaces.
         if str(return_type) == "TBE" \
            or ("interface" in return_type and
-            (return_type["interface"] == "AbstractCacheEntry" or
-             return_type["interface"] == "AbstractEntry")):
+            (return_type["interface"] == "AbstractCacheEntry")):
             code("(*$gcode).m_${{self.field}}")
         else:
             code("($gcode).m_${{self.field}}")
diff --git a/src/mem/slicc/ast/MethodCallExprAST.py b/src/mem/slicc/ast/MethodCallExprAST.py
index 104d6f8df..102ab6e4c 100644
--- a/src/mem/slicc/ast/MethodCallExprAST.py
+++ b/src/mem/slicc/ast/MethodCallExprAST.py
@@ -143,18 +143,18 @@ class MemberMethodCallExprAST(MethodCallExprAST):
                   methodId = implementedMethodId
                   return_type = obj_type.methods[methodId].return_type
 
+        # Check object type or interface of entries by checking
+        # AbstractCacheEntry since AbstractCacheEntry is used in
+        # protocol files.
         if str(obj_type) == "AbstractCacheEntry" or \
-           str(obj_type) == "AbstractEntry" or \
            ("interface" in obj_type and (
-            obj_type["interface"] == "AbstractCacheEntry" or
-            obj_type["interface"] == "AbstractEntry")):
+            obj_type["interface"] == "AbstractCacheEntry")):
             prefix = "%s((*(%s))." % (prefix, code)
         else:
             prefix = "%s((%s)." % (prefix, code)
 
         return obj_type, methodId, prefix
 
-
 class ClassMethodCallExprAST(MethodCallExprAST):
     def __init__(self, slicc, type_ast, proc_name, expr_ast_vec):
         s = super(ClassMethodCallExprAST, self)