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Misc Refactor of DDS Search Code

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This commit is contained in:
W. Felix Handte 2020-08-13 11:57:31 -04:00
parent f1b428fdac
commit eede46a47e
1 changed files with 40 additions and 28 deletions
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68
lib/compress/zstd_lazy.c
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@ -523,13 +523,21 @@ size_t ZSTD_HcFindBestMatch_generic (
U32 nbAttempts = 1U << cParams->searchLog; U32 nbAttempts = 1U << cParams->searchLog;
size_t ml=4-1; size_t ml=4-1;
/* HC4 match finder */ const ZSTD_matchState_t* const dms = ms->dictMatchState;
U32 matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls); const U32 ddsHashLog = dictMode == ZSTD_dedicatedDictSearch
? dms->cParams.hashLog - DD_BLOG : 0;
const U32 ddsIdx = dictMode == ZSTD_dedicatedDictSearch
? ZSTD_hashPtr(ip, ddsHashLog, mls) << DD_BLOG : 0;
if (dictMode == ZSTD_dedicatedDictSearch) U32 matchIndex;
PREFETCH_L1(ms->dictMatchState->hashTable +
(ZSTD_hashPtr(ip, ms->dictMatchState->cParams.hashLog - DD_BLOG, /* HC4 match finder */
ms->dictMatchState->cParams.minMatch) << DD_BLOG)); matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls);
if (dictMode == ZSTD_dedicatedDictSearch) {
const U32* entry = &dms->hashTable[ddsIdx];
PREFETCH_L1(entry);
}
for ( ; (matchIndex>lowLimit) & (nbAttempts>0) ; nbAttempts--) { for ( ; (matchIndex>lowLimit) & (nbAttempts>0) ; nbAttempts--) {
size_t currentMl=0; size_t currentMl=0;
@ -557,47 +565,51 @@ size_t ZSTD_HcFindBestMatch_generic (
} }
if (dictMode == ZSTD_dedicatedDictSearch) { if (dictMode == ZSTD_dedicatedDictSearch) {
const ZSTD_matchState_t* const dms = ms->dictMatchState; const U32 ddsChainSize = (1 << dms->cParams.chainLog);
const U32 dmsChainSize = (1 << dms->cParams.chainLog); const U32 ddsChainMask = ddsChainSize - 1;
const U32 dmsChainMask = dmsChainSize - 1; const U32 ddsLowestIndex = dms->window.dictLimit;
const U32 dmsLowestIndex = dms->window.dictLimit; const BYTE* const ddsBase = dms->window.base;
const BYTE* const dmsBase = dms->window.base; const BYTE* const ddsEnd = dms->window.nextSrc;
const BYTE* const dmsEnd = dms->window.nextSrc; const U32 ddsSize = (U32)(ddsEnd - ddsBase);
const U32 dmsSize = (U32)(dmsEnd - dmsBase); const U32 ddsIndexDelta = dictLimit - ddsSize;
const U32 dmsIndexDelta = dictLimit - dmsSize; const U32 ddsMinChain = ddsSize > ddsChainSize ? ddsSize - ddsChainSize : 0;
const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0;
const U32 bucketSize = (1 << DD_BLOG); const U32 bucketSize = (1 << DD_BLOG);
U32 hash = ZSTD_hashPtr(ip, dms->cParams.hashLog - DD_BLOG,
dms->cParams.minMatch) << DD_BLOG;
U32 attemptNb = 0; U32 attemptNb = 0;
matchIndex = dms->hashTable[hash];
matchIndex = dms->hashTable[ddsIdx];
/* Empty chain */ /* Empty chain */
if (!matchIndex) if (!matchIndex)
return ml; return ml;
for ( ; (matchIndex>dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--, attemptNb++) { for ( ; (matchIndex>ddsLowestIndex) & (nbAttempts>0) ; nbAttempts--, attemptNb++) {
size_t currentMl=0; size_t currentMl=0;
const BYTE* const match = dmsBase + matchIndex; const BYTE* const match = ddsBase + matchIndex;
assert(match+4 <= dmsEnd); assert(match+4 <= ddsEnd);
if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ if (MEM_read32(match) == MEM_read32(ip)) {
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; /* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4;
}
/* save best solution */ /* save best solution */
if (currentMl > ml) { if (currentMl > ml) {
ml = currentMl; ml = currentMl;
*offsetPtr = curr - (matchIndex + dmsIndexDelta) + ZSTD_REP_MOVE; *offsetPtr = curr - (matchIndex + ddsIndexDelta) + ZSTD_REP_MOVE;
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
} }
if (matchIndex <= dmsMinChain) break; if (matchIndex <= ddsMinChain) {
break;
}
if (attemptNb < bucketSize - 1) matchIndex = dms->hashTable[++hash]; if (attemptNb < bucketSize - 1) {
else matchIndex = dms->chainTable[matchIndex & dmsChainMask]; matchIndex = dms->hashTable[ddsIdx + attemptNb];
} else {
matchIndex = dms->chainTable[matchIndex & ddsChainMask];
}
} }
} else if (dictMode == ZSTD_dictMatchState) { } else if (dictMode == ZSTD_dictMatchState) {
const ZSTD_matchState_t* const dms = ms->dictMatchState;
const U32* const dmsChainTable = dms->chainTable; const U32* const dmsChainTable = dms->chainTable;
const U32 dmsChainSize = (1 << dms->cParams.chainLog); const U32 dmsChainSize = (1 << dms->cParams.chainLog);
const U32 dmsChainMask = dmsChainSize - 1; const U32 dmsChainMask = dmsChainSize - 1;