base.hh revision 12684:44ebd2bc020f 
1/**
2 * Copyright (c) 2018 Inria
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Daniel Carvalho
29 */
30
31#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_BASE_HH__
32#define __MEM_CACHE_REPLACEMENT_POLICIES_BASE_HH__
33
34#include <memory>
35
36#include "params/BaseReplacementPolicy.hh"
37#include "sim/sim_object.hh"
38
39/**
40 * The replacement data needed by the replacement policy.
41 * Each replacement policy should have its own replacement data.
42 */
43struct ReplacementData {};
44
45/**
46 * A replaceable entry is used by any table-like structure that needs to
47 * implement replacement functionality. It provides the replacement data
48 * pointer instantiated and needed by the replacement policy used.
49 * @sa Replacement Policies
50 */
51class ReplaceableEntry
52{
53  public:
54    /**
55     * Replacement data associated to this entry.
56     * It is instantiated by the replacement policy.
57     */
58    std::shared_ptr<ReplacementData> replacementData;
59};
60
61/**
62 * Replacement candidates as chosen by the indexing policy.
63 */
64typedef std::vector<ReplaceableEntry*> ReplacementCandidates;
65
66/**
67 * A common base class of cache replacement policy objects.
68 */
69class BaseReplacementPolicy : public SimObject
70{
71  public:
72    /**
73      * Convenience typedef.
74      */
75    typedef BaseReplacementPolicyParams Params;
76
77    /**
78     * Construct and initiliaze this replacement policy.
79     */
80    BaseReplacementPolicy(const Params *p) : SimObject(p) {}
81
82    /**
83     * Destructor.
84     */
85    virtual ~BaseReplacementPolicy() {}
86
87    /**
88     * Invalidate replacement data to set it as the next probable victim.
89     *
90     * @param replacement_data Replacement data to be invalidated.
91     */
92    virtual void invalidate(const std::shared_ptr<ReplacementData>&
93                                                replacement_data) const = 0;
94
95    /**
96     * Update replacement data.
97     *
98     * @param replacement_data Replacement data to be touched.
99     */
100    virtual void touch(const std::shared_ptr<ReplacementData>&
101                                                replacement_data) const = 0;
102
103    /**
104     * Reset replacement data. Used when it's holder is inserted/validated.
105     *
106     * @param replacement_data Replacement data to be reset.
107     */
108    virtual void reset(const std::shared_ptr<ReplacementData>&
109                                                replacement_data) const = 0;
110
111    /**
112     * Find replacement victim among candidates.
113     *
114     * @param candidates Replacement candidates, selected by indexing policy.
115     * @return Replacement entry to be replaced.
116     */
117    virtual ReplaceableEntry* getVictim(
118                           const ReplacementCandidates& candidates) const = 0;
119
120    /**
121     * Instantiate a replacement data entry.
122     *
123     * @return A shared pointer to the new replacement data.
124     */
125    virtual std::shared_ptr<ReplacementData> instantiateEntry() = 0;
126};
127
128#endif // __MEM_CACHE_REPLACEMENT_POLICIES_BASE_HH__
129