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authorDaniel R. Carvalho <odanrc@yahoo.com.br>2019-07-15 16:21:24 +0200
committerDaniel Carvalho <odanrc@yahoo.com.br>2019-10-29 21:32:02 +0000
commit7ce9fe0af9f04a6f94bec9542af025a043c46b35 (patch)
tree39ee68ae2ad98e3bf1d419686c5721d2715c5adf /src/mem/cache/compressors/cpack.hh
parent70dc35a659d024a4362c7b3f08887f04285b34f9 (diff)
downloadgem5-7ce9fe0af9f04a6f94bec9542af025a043c46b35.tar.xz
mem-cache: Factor out CPack's dictionary functionality
Factor out dictionary functionality of CPack, so that it can be used easily for other compressors. As a side effect, create an addToDictionary function to allow subclasses to chose how to handle insertion. Change-Id: I02fae4e98b02db5a40467ec470b71020d5e867cb Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21147 Tested-by: kokoro <noreply+kokoro@google.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Diffstat (limited to 'src/mem/cache/compressors/cpack.hh')
-rw-r--r--src/mem/cache/compressors/cpack.hh329
1 files changed, 34 insertions, 295 deletions
diff --git a/src/mem/cache/compressors/cpack.hh b/src/mem/cache/compressors/cpack.hh
index 1a271eeae..bd258b372 100644
--- a/src/mem/cache/compressors/cpack.hh
+++ b/src/mem/cache/compressors/cpack.hh
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2018 Inria
+ * Copyright (c) 2018-2019 Inria
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -31,14 +31,6 @@
/** @file
* Definition of CPack compression, from "C-Pack: A High-Performance
* Microprocessor Cache Compression Algorithm".
- *
- * The dictionary is composed of 32-bit entries.
- *
- * The patterns are implemented as individual classes that have a checking
- * function isPattern(), to determine if the data fits the pattern, and a
- * decompress() function, which decompresses the contents of a pattern.
- * Every new pattern must inherit from the Pattern class and be added to the
- * patternFactory.
*/
#ifndef __MEM_CACHE_COMPRESSORS_CPACK_HH__
@@ -48,23 +40,16 @@
#include <cstdint>
#include <map>
#include <memory>
-#include <vector>
#include "base/types.hh"
-#include "mem/cache/compressors/base.hh"
+#include "mem/cache/compressors/dictionary_compressor.hh"
struct CPackParams;
-class CPack : public BaseCacheCompressor
+class CPack : public DictionaryCompressor
{
private:
- /**
- * Compression data for CPack. It consists of a vector of patterns.
- */
- class CompData;
-
// Forward declaration of all possible patterns
- class Pattern;
class PatternZZZZ;
class PatternXXXX;
class PatternMMMM;
@@ -73,46 +58,14 @@ class CPack : public BaseCacheCompressor
class PatternMMMX;
/**
- * Create a factory to determine if input matches a pattern. The if else
- * chains are constructed by recursion. The patterns should be explored
- * sorted by size for correct behaviour.
- */
- template <class Head, class... Tail>
- struct Factory
- {
- static std::unique_ptr<Pattern> getPattern(
- const std::array<uint8_t, 4>& bytes,
- const std::array<uint8_t, 4>& dict_bytes, const int match_location)
- {
- // If match this pattern, instantiate it. If a negative match
- // location is used, the patterns that use the dictionary bytes
- // must return false. This is used when there are no dictionary
- // entries yet
- if (Head::isPattern(bytes, dict_bytes, match_location)) {
- return std::unique_ptr<Pattern>(
- new Head(bytes, match_location));
- // Otherwise, go for next pattern
- } else {
- return Factory<Tail...>::getPattern(bytes, dict_bytes,
- match_location);
- }
- }
- };
-
- /**
- * Specialization to end the recursion.
+ * The patterns proposed in the paper. Each letter represents a byte:
+ * Z is a null byte, M is a dictionary match, X is a new value.
+ * These are used as indexes to reference the pattern data. If a new
+ * pattern is added, it must be done before NUM_PATTERNS.
*/
- template <class Head>
- struct Factory<Head>
- {
- static std::unique_ptr<Pattern> getPattern(
- const std::array<uint8_t, 4>& bytes,
- const std::array<uint8_t, 4>& dict_bytes, const int match_location)
- {
- // Instantiate last pattern. Should be the XXXX pattern.
- return std::unique_ptr<Pattern>(new Head(bytes, match_location));
- }
- };
+ typedef enum {
+ ZZZZ, XXXX, MMMM, MMXX, ZZZX, MMMX, NUM_PATTERNS
+ } PatternNumber;
/**
* Convenience factory declaration. The templates must be organized by
@@ -121,55 +74,28 @@ class CPack : public BaseCacheCompressor
using PatternFactory = Factory<PatternZZZZ, PatternMMMM, PatternZZZX,
PatternMMMX, PatternMMXX, PatternXXXX>;
- /**
- * The dictionary.
- */
- std::vector<std::array<uint8_t, 4>> dictionary;
-
- /**
- * Dictionary size.
- */
- const std::size_t dictionarySize;
-
- /**
- * Number of valid entries in the dictionary.
- */
- std::size_t numEntries;
-
- /**
- * @defgroup CompressionStats Compression specific statistics.
- * @{
- */
+ uint64_t getNumPatterns() const override { return NUM_PATTERNS; }
- /**
- * Number of data entries that were compressed to each pattern.
- */
- Stats::Vector patternStats;
-
- /**
- * @}
- */
+ std::string
+ getName(int number) const override
+ {
+ static std::map<int, std::string> patternNames = {
+ {ZZZZ, "ZZZZ"}, {XXXX, "XXXX"}, {MMMM, "MMMM"},
+ {MMXX, "MMXX"}, {ZZZX, "ZZZX"}, {MMMX, "MMMX"}
+ };
- /**
- * Compress data.
- *
- * @param data Data to be compressed.
- * @return The pattern this data matches.
- */
- std::unique_ptr<Pattern> compressWord(const uint32_t data);
+ return patternNames[number];
+ };
- /**
- * Decompress a word.
- *
- * @param pattern The pattern to be decompressed.
- * @return The decompressed word.
- */
- uint32_t decompressWord(const Pattern* pattern);
+ std::unique_ptr<Pattern> getPattern(
+ const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location) const override
+ {
+ return PatternFactory::getPattern(bytes, dict_bytes, match_location);
+ }
- /**
- * Clear all dictionary entries.
- */
- void resetDictionary();
+ void addToDictionary(std::array<uint8_t, 4> data) override;
/**
* Apply compression.
@@ -182,14 +108,6 @@ class CPack : public BaseCacheCompressor
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.
- */
- void decompress(const CompressionData* comp_data, uint64_t* data) override;
-
public:
/** Convenience typedef. */
typedef CPackParams Params;
@@ -203,167 +121,9 @@ class CPack : public BaseCacheCompressor
* Default destructor.
*/
~CPack() {};
-
- /**
- * Register local statistics.
- */
- void regStats() override;
-};
-
-/**
- * The compressed data is composed of multiple pattern entries. To add a new
- * pattern one should inherit from this class and implement isPattern() and
- * decompress. Then the new pattern must be added to the PatternFactory
- * declaration in crescent order of size (in the CPack class). The pattern
- * must be also added to the Name enum in the CPack::Pattern class before
- * NUM_PATTERNS.
- */
-class CPack::Pattern
-{
- protected:
-
- /**
- * The patterns proposed in the paper. Each letter represents a byte:
- * Z is a null byte, M is a dictionary match, X is a new value.
- * These are used as indexes to reference the pattern data. If a new
- * pattern is added, it must be done before NUM_PATTERNS.
- */
- typedef enum {
- ZZZZ, XXXX, MMMM, MMXX, ZZZX, MMMX, NUM_PATTERNS
- } PatternNumber;
-
- /**
- * Pattern enum number.
- */
- const PatternNumber patternNumber;
-
- /**
- * Code associated to the pattern.
- */
- const uint8_t code;
-
- /**
- * Length, in bits, of the code and match location.
- */
- const uint8_t length;
-
- /**
- * Number of unmatched bytes;
- */
- const uint8_t numUnmatchedBytes;
-
- /**
- * Index representing the the match location.
- */
- const int matchLocation;
-
- /**
- * Wether the pattern allocates a dictionary entry or not.
- */
- const bool allocate;
-
- /**
- * Get code of this pattern.
- *
- * @return The code.
- */
- uint8_t getCode() const { return code; }
-
- public:
- /**
- * Default constructor.
- *
- * @param number Pattern number.
- * @param code Code associated to this pattern.
- * @param metadata_length Length, in bits, of the code and match location.
- * @param num_unmatched_bytes Number of unmatched bytes.
- * @param match_location Index of the match location.
- */
- Pattern(const PatternNumber number, const uint64_t code,
- const uint64_t metadata_length, const uint64_t num_unmatched_bytes,
- const int match_location, const bool allocate = true)
- : patternNumber(number), code(code), length(metadata_length),
- numUnmatchedBytes(num_unmatched_bytes),
- matchLocation(match_location), allocate(allocate) {};
-
- /**
- * Default destructor.
- */
- virtual ~Pattern() = default;
-
- /**
- * Trick function to get the number of patterns.
- *
- * @return The number of defined patterns.
- */
- static uint64_t getNumPatterns() { return NUM_PATTERNS; };
-
- /**
- * Get enum number associated to this pattern.
- *
- * @return The pattern enum number.
- */
- PatternNumber getPatternNumber() const { return patternNumber; };
-
- /**
- * Get meta-name assigned to the given pattern.
- *
- * @param number The number of the pattern.
- * @return The meta-name of the pattern.
- */
- static std::string getName(int number)
- {
- static std::map<PatternNumber, std::string> patternNames = {
- {ZZZZ, "ZZZZ"}, {XXXX, "XXXX"}, {MMMM, "MMMM"},
- {MMXX, "MMXX"}, {ZZZX, "ZZZX"}, {MMMX, "MMMX"}
- };
-
- return patternNames[(PatternNumber)number];
- };
-
- /**
- * Get the index of the dictionary match location.
- *
- * @return The index of the match location.
- */
- uint8_t getMatchLocation() const { return matchLocation; }
-
- /**
- * Get size, in bits, of the pattern (excluding prefix). Corresponds to
- * unmatched_data_size + code_length.
- *
- * @return The size.
- */
- std::size_t getSizeBits() const {
- return numUnmatchedBytes*CHAR_BIT + length;
- }
-
- /**
- * Determine if pattern allocates a dictionary entry.
- *
- * @return True if should allocate a dictionary entry.
- */
- bool shouldAllocate() const {
- return allocate;
- }
-
- std::string print() const {
- return csprintf("pattern %s (encoding %x, size %u bits)",
- getName(patternNumber), getCode(), getSizeBits());
- }
-
- /**
- * Decompress the pattern. Each pattern has its own way of interpreting
- * its data.
- *
- * @param dict_bytes The bytes in the corresponding matching entry.
- * @return The decompressed pattern.
- */
- virtual std::array<uint8_t, 4> decompress(
- const std::array<uint8_t, 4> dict_bytes) const = 0;
};
-class CPack::PatternZZZZ : public Pattern
+class CPack::PatternZZZZ : public DictionaryCompressor::Pattern
{
public:
PatternZZZZ(const std::array<uint8_t, 4> bytes, const int match_location)
@@ -384,7 +144,7 @@ class CPack::PatternZZZZ : public Pattern
}
};
-class CPack::PatternXXXX : public Pattern
+class CPack::PatternXXXX : public DictionaryCompressor::Pattern
{
private:
/**
@@ -412,7 +172,7 @@ class CPack::PatternXXXX : public Pattern
}
};
-class CPack::PatternMMMM : public Pattern
+class CPack::PatternMMMM : public DictionaryCompressor::Pattern
{
public:
PatternMMMM(const std::array<uint8_t, 4> bytes, const int match_location)
@@ -432,7 +192,7 @@ class CPack::PatternMMMM : public Pattern
}
};
-class CPack::PatternMMXX : public Pattern
+class CPack::PatternMMXX : public DictionaryCompressor::Pattern
{
private:
/**
@@ -464,7 +224,7 @@ class CPack::PatternMMXX : public Pattern
}
};
-class CPack::PatternZZZX : public Pattern
+class CPack::PatternZZZX : public DictionaryCompressor::Pattern
{
private:
/**
@@ -491,7 +251,7 @@ class CPack::PatternZZZX : public Pattern
}
};
-class CPack::PatternMMMX : public Pattern
+class CPack::PatternMMMX : public DictionaryCompressor::Pattern
{
private:
/**
@@ -520,25 +280,4 @@ class CPack::PatternMMMX : public Pattern
}
};
-class CPack::CompData : public CompressionData
-{
- public:
- /**
- * The patterns matched in the original line.
- */
- std::vector<std::unique_ptr<Pattern>> entries;
-
- /**
- * Default constructor.
- *
- * @param dictionary_size Number of entries in the dictionary.
- */
- CompData(const std::size_t dictionary_size);
-
- /**
- * Default destructor.
- */
- ~CompData();
-};
-
#endif //__MEM_CACHE_COMPRESSORS_CPACK_HH__
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