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+/**
+ * Copyright (c) 2018 Inria
+ * 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
+ */
+
+#include "mem/cache/replacement_policies/second_chance_rp.hh"
+
+SecondChanceRP::SecondChanceRP(const Params *p)
+ : FIFORP(p)
+{
+}
+
+void
+SecondChanceRP::useSecondChance(
+ const std::shared_ptr<SecondChanceReplData>& replacement_data) const
+{
+ // Reset FIFO data
+ FIFORP::reset(replacement_data);
+
+ // Use second chance
+ replacement_data->hasSecondChance = false;
+}
+
+void
+SecondChanceRP::invalidate(
+ const std::shared_ptr<ReplacementData>& replacement_data) const
+{
+ FIFORP::invalidate(replacement_data);
+
+ // Do not give a second chance to invalid entries
+ std::static_pointer_cast<SecondChanceReplData>(
+ replacement_data)->hasSecondChance = false;
+}
+
+void
+SecondChanceRP::touch(const std::shared_ptr<ReplacementData>& replacement_data) const
+{
+ FIFORP::touch(replacement_data);
+
+ // Whenever an entry is touched, it is given a second chance
+ std::static_pointer_cast<SecondChanceReplData>(
+ replacement_data)->hasSecondChance = true;
+}
+
+void
+SecondChanceRP::reset(const std::shared_ptr<ReplacementData>& replacement_data) const
+{
+ FIFORP::reset(replacement_data);
+
+ // Entries are inserted with a second chance
+ std::static_pointer_cast<SecondChanceReplData>(
+ replacement_data)->hasSecondChance = true;
+}
+
+ReplaceableEntry*
+SecondChanceRP::getVictim(const ReplacementCandidates& candidates) const
+{
+ // There must be at least one replacement candidate
+ assert(candidates.size() > 0);
+
+ // Search for invalid entries, as they have the eviction priority
+ for (const auto& candidate : candidates) {
+ // Cast candidate's replacement data
+ std::shared_ptr<SecondChanceReplData> candidate_replacement_data =
+ std::static_pointer_cast<SecondChanceReplData>(
+ candidate->replacementData);
+
+ // Stop iteration if found an invalid entry
+ if ((candidate_replacement_data->tickInserted == Tick(0)) &&
+ !candidate_replacement_data->hasSecondChance) {
+ return candidate;
+ }
+ }
+
+ // Visit all candidates to find victim
+ ReplaceableEntry* victim = candidates[0];
+ bool search_victim = true;
+ while (search_victim) {
+ // Do a FIFO victim search
+ victim = FIFORP::getVictim(candidates);
+
+ // Cast victim's replacement data for code readability
+ std::shared_ptr<SecondChanceReplData> victim_replacement_data =
+ std::static_pointer_cast<SecondChanceReplData>(
+ victim->replacementData);
+
+ // If victim has a second chance, use it and repeat search
+ if (victim_replacement_data->hasSecondChance) {
+ useSecondChance(victim_replacement_data);
+ } else {
+ // Found victim
+ search_victim = false;
+ }
+ }
+
+ return victim;
+}
+
+std::shared_ptr<ReplacementData>
+SecondChanceRP::instantiateEntry()
+{
+ return std::shared_ptr<ReplacementData>(new SecondChanceReplData());
+}
+
+SecondChanceRP*
+SecondChanceRPParams::create()
+{
+ return new SecondChanceRP(this);
+}