set_associative.hh revision 13219:454ecc63338d
1/* 2 * Copyright (c) 2018 Inria 3 * Copyright (c) 2012-2014,2017 ARM Limited 4 * All rights reserved. 5 * 6 * The license below extends only to copyright in the software and shall 7 * not be construed as granting a license to any other intellectual 8 * property including but not limited to intellectual property relating 9 * to a hardware implementation of the functionality of the software 10 * licensed hereunder. You may use the software subject to the license 11 * terms below provided that you ensure that this notice is replicated 12 * unmodified and in its entirety in all distributions of the software, 13 * modified or unmodified, in source code or in binary form. 14 * 15 * Copyright (c) 2003-2005,2014 The Regents of The University of Michigan 16 * All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions are 20 * met: redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer; 22 * redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution; 25 * neither the name of the copyright holders nor the names of its 26 * contributors may be used to endorse or promote products derived from 27 * this software without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 40 * 41 * Authors: Daniel Carvalho 42 * Erik Hallnor 43 */ 44 45/** 46 * @file 47 * Declaration of a set associative indexing policy. 48 */ 49 50#ifndef __MEM_CACHE_INDEXING_POLICIES_SET_ASSOCIATIVE_HH__ 51#define __MEM_CACHE_INDEXING_POLICIES_SET_ASSOCIATIVE_HH__ 52 53#include <vector> 54 55#include "mem/cache/tags/indexing_policies/base.hh" 56#include "params/SetAssociative.hh" 57 58class ReplaceableEntry; 59 60/** 61 * A set associative indexing policy. 62 * @sa \ref gem5MemorySystem "gem5 Memory System" 63 * 64 * The set associative indexing policy has an immutable/identity mapping, so a 65 * value x is always mapped to set x, independent of the way, that is, 66 * Hash(A, 0) = Hash(A, 1) = Hash(A, N-1), where N is the number of ways. 67 * 68 * For example, let's assume address A maps to set 3 on way 0. This policy 69 * makes so that A is also mappable to set 3 on every other way. Visually, the 70 * possible locations of A are, for a table with 4 ways and 8 sets: 71 * Way 0 1 2 3 72 * Set _ _ _ _ 73 * 0 |_| |_| |_| |_| 74 * 1 |_| |_| |_| |_| 75 * 2 |_| |_| |_| |_| 76 * 3 |X| |X| |X| |X| 77 * 4 |_| |_| |_| |_| 78 * 5 |_| |_| |_| |_| 79 * 6 |_| |_| |_| |_| 80 * 7 |_| |_| |_| |_| 81 */ 82class SetAssociative : public BaseIndexingPolicy 83{ 84 private: 85 /** 86 * Apply a hash function to calculate address set. 87 * 88 * @param addr The address to calculate the set for. 89 * @return The set index for given combination of address and way. 90 */ 91 uint32_t extractSet(const Addr addr) const; 92 93 public: 94 /** 95 * Convenience typedef. 96 */ 97 typedef SetAssociativeParams Params; 98 99 /** 100 * Construct and initialize this policy. 101 */ 102 SetAssociative(const Params *p); 103 104 /** 105 * Destructor. 106 */ 107 ~SetAssociative() {}; 108 109 /** 110 * Find all possible entries for insertion and replacement of an address. 111 * Should be called immediately before ReplacementPolicy's findVictim() 112 * not to break cache resizing. 113 * Returns entries in all ways belonging to the set of the address. 114 * 115 * @param addr The addr to a find possible entries for. 116 * @return The possible entries. 117 */ 118 std::vector<ReplaceableEntry*> getPossibleEntries(const Addr addr) const 119 override; 120 121 /** 122 * Regenerate an entry's address from its tag and assigned set and way. 123 * 124 * @param tag The tag bits. 125 * @param entry The entry. 126 * @return the entry's original addr value. 127 */ 128 Addr regenerateAddr(const Addr tag, const ReplaceableEntry* entry) const 129 override; 130}; 131 132#endif //__MEM_CACHE_INDEXING_POLICIES_SET_ASSOCIATIVE_HH__ 133