1c57195d7f
As long as the AssociativeCache Entry parameter satisfies the interface it should be fine. We enforce the bare minimum of having a replaceable entry. Doing otherwise will restrict our capability to have a generic cache with generic tags Change-Id: I23e32b7540fea6b6e5894aca3d91538e81214932 Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
327 lines
9.6 KiB
C++
327 lines
9.6 KiB
C++
/*
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* Copyright (c) 2024 Arm Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2024 Pranith Kumar
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* Copyright (c) 2018 Metempsy Technology Consulting
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* All rights reserved
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __BASE_CACHE_ASSOCIATIVE_CACHE_HH__
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#define __BASE_CACHE_ASSOCIATIVE_CACHE_HH__
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#include <type_traits>
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#include <vector>
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#include "base/cache/cache_entry.hh"
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#include "base/intmath.hh"
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#include "base/logging.hh"
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#include "base/named.hh"
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#include "base/types.hh"
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#include "mem/cache/replacement_policies/base.hh"
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#include "mem/cache/replacement_policies/replaceable_entry.hh"
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#include "mem/cache/tags/indexing_policies/base.hh"
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namespace gem5
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{
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template <typename Entry>
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class AssociativeCache : public Named
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{
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protected:
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static_assert(std::is_base_of_v<ReplaceableEntry, Entry>,
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"Entry should be derived from ReplaceableEntry");
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typedef replacement_policy::Base BaseReplacementPolicy;
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typedef typename Entry::IndexingPolicy IndexingPolicy;
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typedef typename Entry::KeyType KeyType;
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/** Associativity of the cache. */
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size_t associativity;
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/** The replacement policy of the cache. */
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BaseReplacementPolicy *replPolicy;
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/** Indexing policy of the cache */
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IndexingPolicy *indexingPolicy;
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/** The entries */
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std::vector<Entry> entries;
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private:
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void
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initParams(size_t _num_entries, size_t _assoc)
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{
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fatal_if((_num_entries % _assoc) != 0, "The number of entries of an "
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"AssociativeCache<> must be a multiple of its associativity");
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for (auto entry_idx = 0; entry_idx < _num_entries; entry_idx++) {
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Entry *entry = &entries[entry_idx];
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indexingPolicy->setEntry(entry, entry_idx);
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entry->replacementData = replPolicy->instantiateEntry();
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}
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}
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public:
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/**
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* Empty constructor - need to call init() later with all args
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*/
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AssociativeCache(const char *name) : Named(std::string(name)) {}
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/**
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* Public constructor
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* @param name Name of the cache
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* @param num_entries total number of entries of the container, the number
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* of sets can be calculated dividing this balue by the 'assoc' value
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* @param associativity number of elements in each associative set
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* @param repl_policy replacement policy
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* @param indexing_policy indexing policy
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*/
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AssociativeCache(const char *name, const size_t num_entries,
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const size_t associativity_,
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BaseReplacementPolicy *repl_policy,
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IndexingPolicy *indexing_policy,
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Entry const &init_val = Entry())
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: Named(std::string(name)),
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associativity(associativity_),
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replPolicy(repl_policy),
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indexingPolicy(indexing_policy),
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entries(num_entries, init_val)
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{
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initParams(num_entries, associativity);
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}
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/**
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* Default destructor
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*/
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~AssociativeCache() = default;
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/**
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* Disable copy and assignment
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*/
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AssociativeCache(const AssociativeCache&) = delete;
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AssociativeCache& operator=(const AssociativeCache&) = delete;
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/**
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* Clear the entries in the cache.
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*/
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void
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clear()
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{
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for (auto &entry : entries) {
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invalidate(&entry);
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}
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}
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void
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init(const size_t num_entries,
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const size_t associativity_,
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BaseReplacementPolicy *_repl_policy,
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IndexingPolicy *_indexing_policy,
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Entry const &init_val = Entry())
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{
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associativity = associativity_;
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replPolicy = _repl_policy;
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indexingPolicy = _indexing_policy;
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entries.resize(num_entries, init_val);
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initParams(num_entries, associativity);
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}
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/**
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* Do an access to the entry if it exists.
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* This is required to update the replacement information data.
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* @param key key to the entry
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* @return The entry if it exists
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*/
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virtual Entry*
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accessEntry(const KeyType &key)
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{
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auto entry = findEntry(key);
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if (entry) {
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accessEntry(entry);
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}
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return entry;
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}
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/**
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* Update the replacement information for an entry
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* @param Entry to access and upate
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*/
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virtual void
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accessEntry(Entry *entry)
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{
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replPolicy->touch(entry->replacementData);
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}
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/**
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* Find an entry within the set
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* @param key key element
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* @return returns a pointer to the wanted entry or nullptr if it does not
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* exist.
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*/
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virtual Entry*
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findEntry(const KeyType &key) const
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{
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auto candidates = indexingPolicy->getPossibleEntries(key);
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for (auto candidate : candidates) {
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Entry *entry = static_cast<Entry*>(candidate);
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if (entry->match(key)) {
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return entry;
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}
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}
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return nullptr;
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}
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/**
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* Find a victim to be replaced
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* @param key key to select the possible victim
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* @result entry to be victimized
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*/
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virtual Entry*
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findVictim(const KeyType &key)
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{
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auto candidates = indexingPolicy->getPossibleEntries(key);
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auto victim = static_cast<Entry*>(replPolicy->getVictim(candidates));
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invalidate(victim);
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return victim;
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}
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/**
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* Invalidate an entry and its respective replacement data.
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*
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* @param entry Entry to be invalidated.
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*/
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virtual void
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invalidate(Entry *entry)
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{
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entry->invalidate();
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replPolicy->invalidate(entry->replacementData);
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}
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/**
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* Indicate that an entry has just been inserted
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* @param key key of the container
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* @param entry pointer to the container entry to be inserted
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*/
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virtual void
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insertEntry(const KeyType &key, Entry *entry)
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{
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entry->insert(key);
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replPolicy->reset(entry->replacementData);
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}
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/**
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* Find the set of entries that could be replaced given
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* that we want to add a new entry with the provided key
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* @param addr key to select the set of entries
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* @result vector of candidates matching with the provided key
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*/
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std::vector<Entry *>
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getPossibleEntries(const KeyType &key) const
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{
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std::vector<ReplaceableEntry *> selected_entries =
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indexingPolicy->getPossibleEntries(key);
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std::vector<Entry *> entries;
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std::transform(selected_entries.begin(), selected_entries.end(),
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std::back_inserter(entries), [](auto &entry) {
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return static_cast<Entry *>(entry);
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});
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return entries;
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}
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/** Iterator types */
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using const_iterator = typename std::vector<Entry>::const_iterator;
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using iterator = typename std::vector<Entry>::iterator;
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/**
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* Returns an iterator to the first entry of the dictionary
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* @result iterator to the first element
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*/
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iterator
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begin()
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{
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return entries.begin();
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}
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/**
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* Returns an iterator pointing to the end of the the dictionary
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* (placeholder element, should not be accessed)
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* @result iterator to the end element
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*/
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iterator
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end()
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{
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return entries.end();
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}
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/**
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* Returns an iterator to the first entry of the dictionary
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* @result iterator to the first element
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*/
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const_iterator
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begin() const
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{
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return entries.begin();
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}
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/**
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* Returns an iterator pointing to the end of the the dictionary
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* (placeholder element, should not be accessed)
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* @result iterator to the end element
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*/
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const_iterator
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end() const
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{
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return entries.end();
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}
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};
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}
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#endif
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