diff options
Diffstat (limited to 'src/mem/cache/tags/indexing_policies/set_associative.hh')
| -rw-r--r-- | src/mem/cache/tags/indexing_policies/set_associative.hh | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/src/mem/cache/tags/indexing_policies/set_associative.hh b/src/mem/cache/tags/indexing_policies/set_associative.hh new file mode 100644 index 000000000..216172395 --- /dev/null +++ b/src/mem/cache/tags/indexing_policies/set_associative.hh @@ -0,0 +1,132 @@ +/* + * Copyright (c) 2018 Inria + * Copyright (c) 2012-2014,2017 ARM Limited + * All rights reserved. + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * + * Copyright (c) 2003-2005,2014 The Regents of The University of Michigan + * 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 + * Erik Hallnor + */ + +/** + * @file + * Declaration of a set associative indexing policy. + */ + +#ifndef __MEM_CACHE_INDEXING_POLICIES_SET_ASSOCIATIVE_HH__ +#define __MEM_CACHE_INDEXING_POLICIES_SET_ASSOCIATIVE_HH__ + +#include <vector> + +#include "mem/cache/tags/indexing_policies/base.hh" +#include "params/SetAssociative.hh" + +class ReplaceableEntry; + +/** + * A set associative indexing policy. + * @sa \ref gem5MemorySystem "gem5 Memory System" + * + * The set associative indexing policy has an immutable/identity mapping, so a + * value x is always mapped to set x, independent of the way, that is, + * Hash(A, 0) = Hash(A, 1) = Hash(A, N-1), where N is the number of ways. + * + * For example, let's assume address A maps to set 3 on way 0. This policy + * makes so that A is also mappable to set 3 on every other way. Visually, the + * possible locations of A are, for a table with 4 ways and 8 sets: + * Way 0 1 2 3 + * Set _ _ _ _ + * 0 |_| |_| |_| |_| + * 1 |_| |_| |_| |_| + * 2 |_| |_| |_| |_| + * 3 |X| |X| |X| |X| + * 4 |_| |_| |_| |_| + * 5 |_| |_| |_| |_| + * 6 |_| |_| |_| |_| + * 7 |_| |_| |_| |_| + */ +class SetAssociative : public BaseIndexingPolicy +{ + private: + /** + * Apply a hash function to calculate address set. + * + * @param addr The address to calculate the set for. + * @return The set index for given combination of address and way. + */ + uint32_t extractSet(const Addr addr) const; + + public: + /** + * Convenience typedef. + */ + typedef SetAssociativeParams Params; + + /** + * Construct and initialize this policy. + */ + SetAssociative(const Params *p); + + /** + * Destructor. + */ + ~SetAssociative() {}; + + /** + * Find all possible entries for insertion and replacement of an address. + * Should be called immediately before ReplacementPolicy's findVictim() + * not to break cache resizing. + * Returns entries in all ways belonging to the set of the address. + * + * @param addr The addr to a find possible entries for. + * @return The possible entries. + */ + std::vector<ReplaceableEntry*> getPossibleEntries(const Addr addr) const + override; + + /** + * Regenerate an entry's address from its tag and assigned set and way. + * + * @param tag The tag bits. + * @param entry The entry. + * @return the entry's original addr value. + */ + Addr regenerateAddr(const Addr tag, const ReplaceableEntry* entry) const + override; +}; + +#endif //__MEM_CACHE_INDEXING_POLICIES_SET_ASSOCIATIVE_HH__ |