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Merge pull request #1013 from facebook/fasterDec32

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Disable Long Offset mode in 32-bits
This commit is contained in:
Yann Collet
2018-02-09 16:13:55 -08:00
committed by GitHub
parent d6e841d609 de68c2ff10
commit 4e3db17cab
5 changed files with 59 additions and 66 deletions
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lib/common/fse_decompress.c
+2 -2
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@@ -139,8 +139,8 @@ size_t FSE_buildDTable(FSE_DTable* dt, const short* normalizedCounter, unsigned
{ U32 u;
for (u=0; u<tableSize; u++) {
FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
U16 nextState = symbolNext[symbol]++;
tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32 ((U32)nextState) );
U32 const nextState = symbolNext[symbol]++;
tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
} }
lib/compress/zstd_compress.c
+26 -13
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@@ -1223,32 +1223,44 @@ size_t ZSTD_copyCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx, unsigned long
#define ZSTD_ROWSIZE 16
/*! ZSTD_reduceTable_internal() :
* reduce table indexes by `reducerValue`
* presume table size is a multiple of ZSTD_ROWSIZE.
* Helps auto-vectorization */
static void ZSTD_reduceTable_internal (U32* const table, int const nbRows, U32 const reducerValue)
/*! ZSTD_reduceTable() :
* reduce table indexes by `reducerValue`, or squash to zero.
* PreserveMark preserves "unsorted mark" for btlazy2 strategy.
* It must be set to a clear 0/1 value, to remove branch during inlining.
* Presume table size is a multiple of ZSTD_ROWSIZE
* to help auto-vectorization */
FORCE_INLINE_TEMPLATE void
ZSTD_reduceTable_internal (U32* const table, U32 const size, U32 const reducerValue, int const preserveMark)
{
int const nbRows = (int)size / ZSTD_ROWSIZE;
int cellNb = 0;
int rowNb;
assert((size & (ZSTD_ROWSIZE-1)) == 0); /* multiple of ZSTD_ROWSIZE */
assert(size < (1U<<31)); /* can be casted to int */
for (rowNb=0 ; rowNb < nbRows ; rowNb++) {
int column;
for (column=0; column<ZSTD_ROWSIZE; column++) {
if (preserveMark) {
U32 const adder = (table[cellNb] == ZSTD_DUBT_UNSORTED_MARK) ? reducerValue : 0;
table[cellNb] += adder;
}
if (table[cellNb] < reducerValue) table[cellNb] = 0;
else table[cellNb] -= reducerValue;
cellNb++;
} }
}
/*! ZSTD_reduceTable() :
* reduce table indexes by `reducerValue` */
static void ZSTD_reduceTable (U32* const table, U32 const size, U32 const reducerValue)
static void ZSTD_reduceTable(U32* const table, U32 const size, U32 const reducerValue)
{
assert((size & (ZSTD_ROWSIZE-1)) == 0); /* multiple of ZSTD_ROWSIZE */
assert(size < (1U<<31)); /* can be casted to int */
ZSTD_reduceTable_internal(table, size/ZSTD_ROWSIZE, reducerValue);
ZSTD_reduceTable_internal(table, size, reducerValue, 0);
}
static void ZSTD_reduceTable_btlazy2(U32* const table, U32 const size, U32 const reducerValue)
{
ZSTD_reduceTable_internal(table, size, reducerValue, 1);
}
/*! ZSTD_ldm_reduceTable() :
* reduce table indexes by `reducerValue` */
static void ZSTD_ldm_reduceTable(ldmEntry_t* const table, U32 const size,
@@ -1273,8 +1285,9 @@ static void ZSTD_reduceIndex (ZSTD_CCtx* zc, const U32 reducerValue)
if (zc->appliedParams.cParams.strategy != ZSTD_fast) {
U32 const chainSize = (U32)1 << zc->appliedParams.cParams.chainLog;
if (zc->appliedParams.cParams.strategy == ZSTD_btlazy2)
ZSTD_preserveUnsortedMark(ms->chainTable, chainSize, reducerValue);
ZSTD_reduceTable(ms->chainTable, chainSize, reducerValue);
ZSTD_reduceTable_btlazy2(ms->chainTable, chainSize, reducerValue);
else
ZSTD_reduceTable(ms->chainTable, chainSize, reducerValue);
}
if (ms->hashLog3) {
lib/compress/zstd_compress_internal.h
+6
View File
@@ -32,6 +32,12 @@ extern "C" {
***************************************/
static const U32 g_searchStrength = 8;
#define HASH_READ_SIZE 8
#define ZSTD_DUBT_UNSORTED_MARK 1 /* For btlazy2 strategy, index 1 now means "unsorted".
It could be confused for a real successor at index "1", if sorted as larger than its predecessor.
It's not a big deal though : candidate will just be sorted again.
Additionnally, candidate position 1 will be lost.
But candidate 1 cannot hide a large tree of candidates, so it's a minimal loss.
The benefit is that ZSTD_DUBT_UNSORTED_MARK cannot be misdhandled after table re-use with a different strategy */
/*-*************************************
lib/compress/zstd_lazy.c
-29
View File
@@ -15,35 +15,6 @@
/*-*************************************
* Binary Tree search
***************************************/
#define ZSTD_DUBT_UNSORTED_MARK 1 /* note : index 1 will now be confused with "unsorted" if sorted as larger than its predecessor.
It's not a big deal though : the candidate will just be considered unsorted, and be sorted again.
Additionnally, candidate position 1 will be lost.
But candidate 1 cannot hide a large tree of candidates, so it's a moderate loss.
The benefit is that ZSTD_DUBT_UNSORTED_MARK cannot be misdhandled by a table re-use using a different strategy */
/*! ZSTD_preserveUnsortedMark() :
* pre-emptively increase value of ZSTD_DUBT_UNSORTED_MARK before ZSTD_reduceTable()
* so that combined operation preserves its value.
* Without it, ZSTD_DUBT_UNSORTED_MARK==1 would be squashed to 0.
* As a consequence, the list of unsorted elements would stop on the first element,
* removing candidates, resulting in a negligible loss to compression ratio
* (since overflow protection with ZSTD_reduceTable() is relatively rare).
* Another potential risk is that a position will be promoted from *unsorted*
* to *sorted=>smaller:0*, meaning the next candidate will be considered smaller.
* This could be wrong, and result in data corruption.
* On second thought, this corruption might be impossible,
* because unsorted elements are always at the beginning of the list,
* and squashing to zero reduce the list to a single element,
* which needs to be sorted anyway.
* I haven't spent much thoughts into this possible scenario,
* and just felt it was safer to implement ZSTD_preserveUnsortedMark() */
void ZSTD_preserveUnsortedMark (U32* const table, U32 const size, U32 const reducerValue)
{
U32 u;
for (u=0; u<size; u++)
if (table[u] == ZSTD_DUBT_UNSORTED_MARK)
table[u] = ZSTD_DUBT_UNSORTED_MARK + reducerValue;
}
void ZSTD_updateDUBT(
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
lib/decompress/zstd_decompress.c
+25 -22
View File
@@ -23,7 +23,7 @@
/*!
* LEGACY_SUPPORT :
* if set to 1, ZSTD_decompress() can decode older formats (v0.1+)
* if set to 1+, ZSTD_decompress() can decode older formats (v0.1+)
*/
#ifndef ZSTD_LEGACY_SUPPORT
# define ZSTD_LEGACY_SUPPORT 0
@@ -235,8 +235,8 @@ void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
/*-*************************************************************
* Decompression section
***************************************************************/
* Frame header decoding
***************************************************************/
/*! ZSTD_isFrame() :
* Tells if the content of `buffer` starts with a valid Frame Identifier.
@@ -258,7 +258,7 @@ unsigned ZSTD_isFrame(const void* buffer, size_t size)
/** ZSTD_frameHeaderSize_internal() :
* srcSize must be large enough to reach header size fields.
* note : only works for formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless
* note : only works for formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless.
* @return : size of the Frame Header
* or an error code, which can be tested with ZSTD_isError() */
static size_t ZSTD_frameHeaderSize_internal(const void* src, size_t srcSize, ZSTD_format_e format)
@@ -481,6 +481,10 @@ static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t he
}
/*-*************************************************************
* Block decoding
***************************************************************/
/*! ZSTD_getcBlockSize() :
* Provides the size of compressed block from block header `src` */
size_t ZSTD_getcBlockSize(const void* src, size_t srcSize,
@@ -651,6 +655,7 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
typedef union {
FSE_decode_t realData;
FSE_DTable dtable;
U32 alignedBy4;
} FSE_decode_t4;
@@ -729,7 +734,6 @@ static size_t ZSTD_buildSeqTable(FSE_DTable* DTableSpace, const FSE_DTable** DTa
const void* src, size_t srcSize,
const FSE_decode_t4* defaultTable, U32 flagRepeatTable)
{
const void* const tmpPtr = defaultTable; /* bypass strict aliasing */
switch(type)
{
case set_rle :
@@ -739,7 +743,7 @@ static size_t ZSTD_buildSeqTable(FSE_DTable* DTableSpace, const FSE_DTable** DTa
*DTablePtr = DTableSpace;
return 1;
case set_basic :
*DTablePtr = (const FSE_DTable*)tmpPtr;
*DTablePtr = &defaultTable->dtable;
return 0;
case set_repeat:
if (!flagRepeatTable) return ERROR(corruption_detected);
@@ -936,13 +940,14 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e l
ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
assert(ofBits <= MaxOff);
if (MEM_32bits() && longOffsets) {
U32 const extraBits = ofBits - MIN(ofBits, STREAM_ACCUMULATOR_MIN_32-1);
if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) {
U32 const extraBits = ofBits - MIN(ofBits, 32 - seqState->DStream.bitsConsumed);
offset = OF_base[ofCode] + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
if (MEM_32bits() || extraBits) BIT_reloadDStream(&seqState->DStream);
BIT_reloadDStream(&seqState->DStream);
if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits);
assert(extraBits <= LONG_OFFSETS_MAX_EXTRA_BITS_32); /* to avoid another reload */
} else {
offset = OF_base[ofCode] + BIT_readBitsFast(&seqState->DStream, ofBits); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
offset = OF_base[ofCode] + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
}
}
@@ -955,7 +960,7 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e l
if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
seqState->prevOffset[1] = seqState->prevOffset[0];
seqState->prevOffset[0] = offset = temp;
} else {
} else { /* offset == 0 */
offset = seqState->prevOffset[0];
}
} else {
@@ -967,16 +972,16 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e l
}
seq.matchLength = ML_base[mlCode]
+ ((mlCode>31) ? BIT_readBitsFast(&seqState->DStream, mlBits) : 0); /* <= 16 bits */
+ ((mlCode>31) ? BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/) : 0); /* <= 16 bits */
if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
BIT_reloadDStream(&seqState->DStream);
if (MEM_64bits() && (totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog)))
BIT_reloadDStream(&seqState->DStream);
/* Verify that there is enough bits to read the rest of the data in 64-bit mode. */
/* Ensure there are enough bits to read the rest of data in 64-bit mode. */
ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64);
seq.litLength = LL_base[llCode]
+ ((llCode>15) ? BIT_readBitsFast(&seqState->DStream, llBits) : 0); /* <= 16 bits */
+ ((llCode>15) ? BIT_readBitsFast(&seqState->DStream, llBits/*>0*/) : 0); /* <= 16 bits */
if (MEM_32bits())
BIT_reloadDStream(&seqState->DStream);
@@ -1364,13 +1369,13 @@ static size_t ZSTD_decompressSequencesLong(
FSE_initDState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
/* prepare in advance */
for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && seqNb<seqAdvance; seqNb++) {
for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) {
sequences[seqNb] = ZSTD_decodeSequenceLong(&seqState, isLongOffset);
}
if (seqNb<seqAdvance) return ERROR(corruption_detected);
/* decode and decompress */
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && seqNb<nbSeq ; seqNb++) {
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb<nbSeq) ; seqNb++) {
seq_t const sequence = ZSTD_decodeSequenceLong(&seqState, isLongOffset);
size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STOSEQ_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
@@ -1411,13 +1416,9 @@ static size_t ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
/* isLongOffset must be true if there are long offsets.
* Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN.
* We don't expect that to be the case in 64-bit mode.
* If we are in block mode we don't know the window size, so we have to be
* conservative.
* In block mode, window size is not known, so we have to be conservative. (note: but it could be evaluated from current-lowLimit)
*/
ZSTD_longOffset_e const isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (!frame || dctx->fParams.windowSize > (1ULL << STREAM_ACCUMULATOR_MIN)));
/* windowSize could be any value at this point, since it is only validated
* in the streaming API.
*/
DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize);
if (srcSize >= ZSTD_BLOCKSIZE_MAX) return ERROR(srcSize_wrong);
@@ -1429,7 +1430,9 @@ static size_t ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
ip += litCSize;
srcSize -= litCSize;
}
if (frame && dctx->fParams.windowSize > (1<<23))
if ( frame /* windowSize exists */
&& (dctx->fParams.windowSize > (1<<24))
&& MEM_64bits() /* x86 benefits less from long mode than x64 */ )
return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, isLongOffset);
return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, isLongOffset);
}