mem-cache: Split Tags for indexing policies

Split indexing functionality from tags, so that code duplication
is reduced when adding new classes that use different indexing
policies, such as set associative, skewed associative or other
hash-based policies.

An indexing policy defines the mapping between an address' set
and its physical location. For example, a conventional set assoc
cache maps an address to all ways in a set using an immutable
function, that is, a set x is always mapped to set x. However,
skewed assoc caches map an address to a different set for each way,
using a skewing function.

FALRU has been left unmodified as it is a specialization with its
own complexity.

Change-Id: I0838b41663f21eba0aeab7aeb7839e3703ca3324
Reviewed-on: https://gem5-review.googlesource.com/c/8885
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

1 files changed, 82 insertions, 0 deletions

diff --git a/src/mem/cache/tags/indexing_policies/set_associative.cc b/src/mem/cache/tags/indexing_policies/set_associative.cc
new file mode 100644
index 000000000..d5fe8ffd0
--- /dev/null
+++ b/src/mem/cache/tags/indexing_policies/set_associative.cc
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2018 Inria
+ * Copyright (c) 2012-2014,2017 ARM Limited
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2003-2005,2014 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Daniel Carvalho
+ *          Erik Hallnor
+ */
+
+/**
+ * @file
+ * Definitions of a set associative indexing policy.
+ */
+
+#include "mem/cache/tags/indexing_policies/set_associative.hh"
+
+#include "mem/cache/replacement_policies/base.hh"
+
+SetAssociative::SetAssociative(const Params *p)
+    : BaseIndexingPolicy(p)
+{
+}
+
+uint32_t
+SetAssociative::extractSet(const Addr addr) const
+{
+    return (addr >> setShift) & setMask;
+}
+
+Addr
+SetAssociative::regenerateAddr(const Addr tag, const ReplaceableEntry* entry)
+                                                                        const
+{
+    return (tag << tagShift) | (entry->getSet() << setShift);
+}
+
+std::vector<ReplaceableEntry*>
+SetAssociative::getPossibleEntries(const Addr addr) const
+{
+    return sets[extractSet(addr)];
+}
+
+SetAssociative*
+SetAssociativeParams::create()
+{
+    return new SetAssociative(this);
+}