stride.hh revision 13426 
1/*
2 * Copyright (c) 2012-2013, 2015 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Ron Dreslinski
41 */
42
43/**
44 * @file
45 * Describes a strided prefetcher.
46 */
47
48#ifndef __MEM_CACHE_PREFETCH_STRIDE_HH__
49#define __MEM_CACHE_PREFETCH_STRIDE_HH__
50
51#include <string>
52#include <unordered_map>
53#include <vector>
54
55#include "base/types.hh"
56#include "mem/cache/prefetch/queued.hh"
57#include "mem/packet.hh"
58
59struct StridePrefetcherParams;
60
61class StridePrefetcher : public QueuedPrefetcher
62{
63  protected:
64    const int maxConf;
65    const int threshConf;
66    const int minConf;
67    const int startConf;
68
69    const int pcTableAssoc;
70    const int pcTableSets;
71
72    const bool useMasterId;
73
74    const int degree;
75
76    struct StrideEntry
77    {
78        /** Default constructor */
79        StrideEntry();
80
81        /** Invalidate the entry */
82        void invalidate();
83
84        Addr instAddr;
85        Addr lastAddr;
86        bool isSecure;
87        int stride;
88        int confidence;
89    };
90
91    class PCTable
92    {
93      public:
94        /**
95         * Default constructor. Create a table with given parameters.
96         *
97         * @param assoc Associativity of the table.
98         * @param sets Number of sets in the table.
99         * @param name Name of the prefetcher.
100         */
101        PCTable(int assoc, int sets, const std::string name);
102
103        /**
104         * Default destructor.
105         */
106        ~PCTable();
107
108        /**
109         * Search for an entry in the pc table.
110         *
111         * @param pc The PC to look for.
112         * @param is_secure True if the target memory space is secure.
113         * @return Pointer to the entry.
114         */
115        StrideEntry* findEntry(Addr pc, bool is_secure);
116
117        /**
118         * Find a replacement victim to make room for given PC.
119         *
120         * @param pc The PC value.
121         * @return The victimized entry.
122         */
123        StrideEntry* findVictim(Addr pc);
124
125      private:
126        const std::string name() {return _name; }
127        const int pcTableAssoc;
128        const int pcTableSets;
129        const std::string _name;
130        std::vector<std::vector<StrideEntry>> entries;
131
132        /**
133         * PC hashing function to index sets in the table.
134         *
135         * @param pc The PC value.
136         * @return The set to which this PC maps.
137         */
138        Addr pcHash(Addr pc) const;
139    };
140    std::unordered_map<int, PCTable> pcTables;
141
142    /**
143     * Try to find a table of entries for the given context. If none is
144     * found, a new table is created.
145     *
146     * @param context The context to be searched for.
147     * @return The table corresponding to the given context.
148     */
149    PCTable* findTable(int context);
150
151    /**
152     * Create a PC table for the given context.
153     *
154     * @param context The context of the new PC table.
155     * @return The new PC table
156     */
157    PCTable* allocateNewContext(int context);
158
159  public:
160    StridePrefetcher(const StridePrefetcherParams *p);
161
162    void calculatePrefetch(const PacketPtr &pkt,
163                           std::vector<AddrPriority> &addresses) override;
164};
165
166#endif // __MEM_CACHE_PREFETCH_STRIDE_HH__
167