mem-cache: Make BDI a multi compressor

BDI is a compressor containing multiple sub-compressors.

Change-Id: I98411e2ef9dcc2182801a172dfc59ed7a8ee7dd4
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21159
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>

1 files changed, 0 insertions, 428 deletions

diff --git a/src/mem/cache/compressors/bdi.hh b/src/mem/cache/compressors/bdi.hh
deleted file mode 100644
index 9a145fa81..000000000
--- a/src/mem/cache/compressors/bdi.hh
+++ /dev/null
@@ -1,428 +0,0 @@
-/*
- * 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
- */
-
-/** @file
- * Definition of "Base-Delta-Immediate Compression: Practical Data Compression
- * for On-Chip Caches".
- */
-
-#ifndef __MEM_CACHE_COMPRESSORS_BDI_HH__
-#define __MEM_CACHE_COMPRESSORS_BDI_HH__
-
-#include <cstdint>
-#include <memory>
-#include <vector>
-
-#include "base/types.hh"
-#include "mem/cache/compressors/base.hh"
-
-struct BDIParams;
-
-/**
- * Default maximum number of bases in the original BDI.
- */
-#define BDI_DEFAULT_MAX_NUM_BASES 2
-
-class BDI : public BaseCacheCompressor
-{
-  protected:
-    /**
-     * Forward declaration of comp data classes.
-     */
-    class BDICompData;
-    class BDICompDataZeros;
-    class BDICompDataRep;
-    class BDICompDataUncompressed;
-    template <class TB, class TD> class BDICompDataBaseDelta;
-
-    /**
-     * The possible encoding values. If modified, ENCODING_NAMES must be too.
-     */
-    enum ENCODING {ZERO, REP_VALUES, BASE8_1, BASE8_2, BASE8_4, BASE4_1,
-                   BASE4_2, BASE2_1, UNCOMPRESSED, NUM_ENCODINGS};
-
-    /**
-     * The respective encoding names. They are indexed by the ENCODING enum.
-     * The values are assigned in the source file, and should be modified if
-     * ENCODING is changed.
-     */
-    static const char* ENCODING_NAMES[];
-
-    /**
-     * If set, create multiple compressor instances for each possible
-     * combination of base and delta size. Otherwise, just create a
-     * compressor for each base size with the highest available delta
-     * size. This can be used to save area and power (having less
-     * compressors). True by default.
-     */
-    const bool useMoreCompressors;
-
-    /**
-     * Number of qwords in a cache line.
-     */
-    const std::size_t qwordsPerCacheLine;
-
-    /**
-     * @defgroup CompressionStats Compression specific statistics.
-     * @{
-     */
-
-    /**
-     * Number of data entries that were compressed to each encoding.
-     */
-    Stats::Vector encodingStats;
-
-    /**
-     * @}
-     */
-
-    /**
-     * Check if the cache line consists of only zero values.
-     *
-     * @param data The cache line.
-     * @return True if it is a ZERO cache line.
-     */
-    bool isZeroPackable(const uint64_t* data) const;
-
-    /**
-     * Check if the cache line consists only of same values.
-     *
-     * @param data The cache line.
-     * @return True if it is a REP_VALUES cache line.
-     */
-    bool isSameValuePackable(const uint64_t* data) const;
-
-    /**
-     * Instantiate a BaseDelta compressor with given TB and TD, and try to
-     * compress the cache line. If the compression fails, it returns a nullptr.
-     * @sa BDICompDataBaseDelta
-     *
-     * @tparam TB Type of a base entry.
-     * @tparam TD Type of a delta entry.
-     * @param data The cache line to be compressed.
-     * @param encoding Encoding value for given TB-TD combination.
-     * @return Cache line after compression or nullptr.
-     */
-    template <class TB, class TD>
-    std::unique_ptr<BDICompData> tryCompress(const uint64_t* data,
-                                             const uint8_t encoding) const;
-
-    /**
-     * Apply compression.
-     *
-     * @param data The cache line to be compressed.
-     * @param comp_lat Compression latency in number of cycles.
-     * @param decomp_lat Decompression latency in number of cycles.
-     * @param comp_size Compressed data size.
-     */
-    std::unique_ptr<BaseCacheCompressor::CompressionData> compress(
-        const uint64_t* data, Cycles& comp_lat, Cycles& decomp_lat) override;
-
-    /**
-     * Decompress data.
-     *
-     * @param comp_data Compressed cache line.
-     * @param data The cache line to be decompressed.
-     * @return Decompression latency in number of cycles.
-     */
-    void decompress(const BaseCacheCompressor::CompressionData* comp_data,
-                                           uint64_t* data) override;
-
-  public:
-    /** Convenience typedef. */
-    typedef BDIParams Params;
-
-    /**
-     * Default constructor.
-     */
-    BDI(const Params *p);
-
-    /**
-     * Default destructor.
-     */
-    ~BDI() = default;
-
-    /**
-     * Register local statistics.
-     */
-    void regStats() override;
-};
-
-/**
- * Template for the BDI compression data.
- */
-class BDI::BDICompData : public CompressionData
-{
-  private:
-    /**
-     * Data encoding.
-     * @sa BDI
-     */
-    const uint8_t _encoding;
-
-  protected:
-    /**
-     * Number of bits needed for the encoding field.
-     */
-    static const std::size_t encodingBits = 4;
-
-    /**
-     * Calculate and set compressed data size.
-     * Each BDI compressor generates compressed data with different sizes.
-    */
-    virtual void calculateCompressedSize() = 0;
-
-  public:
-    /**
-     * Default constructor.
-     *
-     * @param encoding The encoding value.
-     */
-    BDICompData(const uint8_t encoding);
-
-    /**
-     * Default destructor.
-     */
-    virtual ~BDICompData() = default;
-
-    /**
-     * Get and decompress data at given index.
-     *
-     * The index is given relative to 64-bit entries, therefore if the base
-     * size of the given compressed data is smaller than that, this function
-     * joins multiple base-delta entries to generate the respective 64-bit
-     * entry.
-     *
-     * @param index The index of the compressed data.
-     * @return Decompressed data for the given index.
-     */
-    virtual uint64_t access(const int index) const = 0;
-
-    /**
-     * Get encoding.
-     *
-     * @return The encoding.
-     */
-    uint8_t getEncoding() const;
-
-    /**
-     * Get encoding name.
-     *
-     * @return The encoding name.
-     */
-    std::string getName() const;
-};
-
-/**
- * BDI compressed data containing the ZERO encoding.
- */
-class BDI::BDICompDataZeros : public BDICompData
-{
-  protected:
-    /**
-     * Calculate compressed data size using ZERO encoding.
-     */
-    void calculateCompressedSize() override;
-
-  public:
-    /**
-     * Default constructor.
-    */
-    BDICompDataZeros();
-
-    /**
-     * Get and decompress data at given index. Must always return 0.
-     *
-     * @param index The index of the compressed data.
-     * @return Decompressed data for the given index.
-     */
-    uint64_t access(const int index) const override;
-};
-
-/**
- * BDI compressed data containing the REP_VALUES encoding.
- */
-class BDI::BDICompDataRep : public BDICompData
-{
-  private:
-    /**
-     * The repeated value.
-     */
-    uint64_t base;
-
-  protected:
-    /**
-     * Calculate compressed data size using REP_VALUES encoding.
-     */
-    void calculateCompressedSize() override;
-
-  public:
-    /**
-     * Default constructor.
-     *
-     * @param rep_value The repeated value.
-     */
-    BDICompDataRep(const uint64_t rep_value);
-
-    /**
-     * Get and decompress data at given index. Must always return the same
-     * value as data[0].
-     *
-     * @param index The index of the compressed data.
-     * @return Decompressed data for the given index.
-     */
-    uint64_t access(const int index) const override;
-};
-
-/**
- * BDI compressed data containing the UNCOMPRESSED encoding.
- */
-class BDI::BDICompDataUncompressed : public BDICompData
-{
-  private:
-    /**
-     * Uncompressed cache line size (in bytes).
-     */
-    const std::size_t blkSize;
-
-    /**
-     * The compressed data is the original cache line.
-     */
-    const std::vector<uint64_t> _data;
-
-  protected:
-    /**
-     * Calculate compressed data size using UNCOMPRESSED encoding.
-     */
-    void calculateCompressedSize() override;
-
-  public:
-    /**
-     * Default constructor.
-     *
-     * @param data The data on which compression was applied.
-     * @param blk_size Size of a cache line in bytes.
-     */
-    BDICompDataUncompressed(const uint64_t* data,
-                            const std::size_t blk_size);
-
-    /**
-     * Get and decompress data at given index. Must return the same
-     * value as _data[index].
-     *
-     * @param index The index of the compressed data.
-     * @return Decompressed data for the given index.
-     */
-    uint64_t access(const int index) const override;
-};
-
-/**
- * Template class for BDI compressed data containing all the BASE_DELTA
- * encodings. TB's size must always be greater than TD's.
- *
- * @tparam TB Type of a base entry.
- * @tparam TD Type of a delta entry.
-*/
-template <class TB, class TD>
-class BDI::BDICompDataBaseDelta : public BDICompData
-{
-  protected:
-    /**
-     * Maximum number of bases.
-     */
-    const std::size_t maxNumBases;
-
-    /**
-     * Bit mask to differentiate between the bases.
-     */
-    std::vector<uint8_t> bitMask;
-
-    /**
-     * Bases. bases[0] is 0 and is not stored in a hardware implementation.
-     */
-    std::vector<TB> bases;
-
-    /**
-     * Array of deltas (or immediate values).
-     */
-    std::vector<TD> deltas;
-
-    /**
-     * Add a base to the bases vector.
-     *
-     * @param base The base to be added.
-     * @return True on success, false if already used all base slots.
-     */
-    bool addBase(const TB base);
-
-    /**
-     * Add a delta to the deltas vector.
-     *
-     * @param base_index Base to which the delta refers.
-     * @param delta The delta value.
-     */
-    void addDelta(const std::size_t base_index, const TD delta);
-
-    /**
-     * Calculate compressed data size using number of bases, the base size and
-     * the delta size.
-     */
-    void calculateCompressedSize() override;
-
-  public:
-    /**
-     * Default constructor.
-     *
-     * @param encoding The encoding value for this compressor.
-     * @param blk_size Size of a cache line in bytes.
-     * @param max_num_bases Maximum number of bases allowed to be stored.
-     */
-    BDICompDataBaseDelta(const uint8_t encoding, const std::size_t blk_size,
-        const std::size_t max_num_bases = BDI_DEFAULT_MAX_NUM_BASES);
-
-    /**
-     * Get and decompress data at given index.
-     *
-     * @param index The index of the compressed data.
-     * @return Decompressed data for the given index.
-     */
-    uint64_t access(const int index) const override;
-
-    /**
-     * Apply base delta compression.
-     *
-     * @param data The data on which compression was applied.
-     * @param blk_size Size of a cache line in bytes.
-     * @return True on success.
-     */
-    bool compress(const uint64_t* data, const std::size_t blk_size);
-};
-
-#endif //__MEM_CACHE_COMPRESSORS_BDI_HH__