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Merge pull request #471 from lz4/fasterHC

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Faster HC
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Yann Collet 2018-02-20 21:04:07 -08:00 committed by GitHub
commit 71e16fa11a
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1 changed files with 18 additions and 25 deletions
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lib/lz4hc.c
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@ -123,17 +123,20 @@ LZ4_FORCE_INLINE
int LZ4HC_countBack(const BYTE* const ip, const BYTE* const match, int LZ4HC_countBack(const BYTE* const ip, const BYTE* const match,
const BYTE* const iMin, const BYTE* const mMin) const BYTE* const iMin, const BYTE* const mMin)
{ {
int back=0; int back = 0;
while ( (ip+back > iMin) int const min = (int)MAX(iMin - ip, mMin - match);
&& (match+back > mMin) assert(ip >= iMin); assert((size_t)(ip-iMin) < (1U<<31));
&& (ip[back-1] == match[back-1])) assert(match >= mMin); assert((size_t)(match - mMin) < (1U<<31));
while ( (back > min)
&& (ip[back-1] == match[back-1]) )
back--; back--;
return back; return back;
} }
/* LZ4HC_countPattern() : /* LZ4HC_countPattern() :
* pattern32 must be a sample of repetitive pattern of length 1, 2 or 4 (but not 3!) */ * pattern32 must be a sample of repetitive pattern of length 1, 2 or 4 (but not 3!) */
static unsigned LZ4HC_countPattern(const BYTE* ip, const BYTE* const iEnd, U32 const pattern32) static unsigned
LZ4HC_countPattern(const BYTE* ip, const BYTE* const iEnd, U32 const pattern32)
{ {
const BYTE* const iStart = ip; const BYTE* const iStart = ip;
reg_t const pattern = (sizeof(pattern)==8) ? (reg_t)pattern32 + (((reg_t)pattern32) << 32) : pattern32; reg_t const pattern = (sizeof(pattern)==8) ? (reg_t)pattern32 + (((reg_t)pattern32) << 32) : pattern32;
@ -165,7 +168,8 @@ static unsigned LZ4HC_countPattern(const BYTE* ip, const BYTE* const iEnd, U32 c
/* LZ4HC_reverseCountPattern() : /* LZ4HC_reverseCountPattern() :
* pattern must be a sample of repetitive pattern of length 1, 2 or 4 (but not 3!) * pattern must be a sample of repetitive pattern of length 1, 2 or 4 (but not 3!)
* read using natural platform endianess */ * read using natural platform endianess */
static unsigned LZ4HC_reverseCountPattern(const BYTE* ip, const BYTE* const iLow, U32 pattern) static unsigned
LZ4HC_reverseCountPattern(const BYTE* ip, const BYTE* const iLow, U32 pattern)
{ {
const BYTE* const iStart = ip; const BYTE* const iStart = ip;
@ -183,7 +187,8 @@ static unsigned LZ4HC_reverseCountPattern(const BYTE* ip, const BYTE* const iLow
typedef enum { rep_untested, rep_not, rep_confirmed } repeat_state_e; typedef enum { rep_untested, rep_not, rep_confirmed } repeat_state_e;
LZ4_FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch ( LZ4_FORCE_INLINE int
LZ4HC_InsertAndGetWiderMatch (
LZ4HC_CCtx_internal* hc4, LZ4HC_CCtx_internal* hc4,
const BYTE* const ip, const BYTE* const ip,
const BYTE* const iLowLimit, const BYTE* const iLowLimit,
@ -220,20 +225,11 @@ LZ4_FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
nbAttempts--; nbAttempts--;
if (matchIndex >= dictLimit) { if (matchIndex >= dictLimit) {
const BYTE* const matchPtr = base + matchIndex; const BYTE* const matchPtr = base + matchIndex;
if (*(iLowLimit + longest) == *(matchPtr - delta + longest)) { assert(longest >= 1);
if (LZ4_read16(iLowLimit + longest - 1) == LZ4_read16(matchPtr - delta + longest - 1)) {
if (LZ4_read32(matchPtr) == pattern) { if (LZ4_read32(matchPtr) == pattern) {
int mlt = MINMATCH + LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, iHighLimit); int mlt = MINMATCH + LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, iHighLimit);
#if 0 int const back = delta ? LZ4HC_countBack(ip, matchPtr, iLowLimit, lowPrefixPtr) : 0;
/* more generic but unfortunately slower on clang */
int const back = LZ4HC_countBack(ip, matchPtr, iLowLimit, lowPrefixPtr);
#else
int back = 0;
while ( (ip+back > iLowLimit)
&& (matchPtr+back > lowPrefixPtr)
&& (ip[back-1] == matchPtr[back-1])) {
back--;
}
#endif
mlt -= back; mlt -= back;
if (mlt > longest) { if (mlt > longest) {
@ -252,10 +248,7 @@ LZ4_FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
mlt = LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, vLimit) + MINMATCH; mlt = LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, vLimit) + MINMATCH;
if ((ip+mlt == vLimit) && (vLimit < iHighLimit)) if ((ip+mlt == vLimit) && (vLimit < iHighLimit))
mlt += LZ4_count(ip+mlt, base+dictLimit, iHighLimit); mlt += LZ4_count(ip+mlt, base+dictLimit, iHighLimit);
while ( (ip+back > iLowLimit) back = delta ? LZ4HC_countBack(ip, matchPtr, iLowLimit, dictBase+lowLimit) : 0;
&& (matchIndex+back > lowLimit)
&& (ip[back-1] == matchPtr[back-1]))
back--;
mlt -= back; mlt -= back;
if (mlt > longest) { if (mlt > longest) {
longest = mlt; longest = mlt;
@ -333,7 +326,7 @@ LZ4_FORCE_INLINE int LZ4HC_encodeSequence (
size_t length; size_t length;
BYTE* const token = (*op)++; BYTE* const token = (*op)++;
#if defined(LZ4_DEBUG) && (LZ4_DEBUG >= 2) #if defined(LZ4_DEBUG) && (LZ4_DEBUG >= 6)
static const BYTE* start = NULL; static const BYTE* start = NULL;
static U32 totalCost = 0; static U32 totalCost = 0;
U32 const pos = (start==NULL) ? 0 : (U32)(*anchor - start); U32 const pos = (start==NULL) ? 0 : (U32)(*anchor - start);
@ -343,7 +336,7 @@ LZ4_FORCE_INLINE int LZ4HC_encodeSequence (
U32 const cost = 1 + llAdd + ll + 2 + mlAdd; U32 const cost = 1 + llAdd + ll + 2 + mlAdd;
if (start==NULL) start = *anchor; /* only works for single segment */ if (start==NULL) start = *anchor; /* only works for single segment */
//g_debuglog_enable = (pos >= 2228) & (pos <= 2262); //g_debuglog_enable = (pos >= 2228) & (pos <= 2262);
DEBUGLOG(2, "pos:%7u -- literals:%3u, match:%4i, offset:%5u, cost:%3u + %u", DEBUGLOG(6, "pos:%7u -- literals:%3u, match:%4i, offset:%5u, cost:%3u + %u",
pos, pos,
(U32)(*ip - *anchor), matchLength, (U32)(*ip-match), (U32)(*ip - *anchor), matchLength, (U32)(*ip-match),
cost, totalCost); cost, totalCost);