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Remove Dead(!) HC3 DMS Lookup

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This commit is contained in:
W. Felix Handte
2018-06-20 15:27:12 -04:00
parent 03c39c540b
commit ae1f3898a2
1 changed files with 2 additions and 28 deletions
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lib/compress/zstd_opt.c
+2 -28
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@@ -580,7 +580,7 @@ U32 ZSTD_insertBtAndGetAllMatches (
/* HC3 match finder */ /* HC3 match finder */
if ((mls == 3) /*static*/ && (bestLength < mls)) { if ((mls == 3) /*static*/ && (bestLength < mls)) {
U32 matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, ip); U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, ip);
if ((matchIndex3 > windowLow) if ((matchIndex3 > windowLow)
& (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) { & (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) {
size_t mlen; size_t mlen;
@@ -608,34 +608,8 @@ U32 ZSTD_insertBtAndGetAllMatches (
return 1; return 1;
} }
} }
} else if (dictMode == ZSTD_dictMatchState) {
/* should we perform this search even if the working ctx search
* found a match? */
U32 const hashLog3 = ms->hashLog3;
size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3);
U32 const dmsMatchIndex3 = dms->hashTable3[hash3];
matchIndex3 = dmsMatchIndex3 + dmsIndexDelta;
if ((dmsMatchIndex3 >= dmsLowLimit) & (current - matchIndex3 < (1<<18))) {
const BYTE* const match = dmsBase + dmsMatchIndex3;
size_t mlen = ZSTD_count_2segments(ip, match, iLimit, dmsEnd, prefixStart);
if (mlen >= mls) {
matchIndex3 = dmsMatchIndex3 + dmsIndexDelta;
DEBUGLOG(8, "found small dms match with hlog3, of length %u",
(U32)mlen);
bestLength = mlen;
assert(current > matchIndex3);
assert(mnum==0); /* no prior solution */
matches[0].off = (current - matchIndex3) + ZSTD_REP_MOVE;
matches[0].len = (U32)mlen;
mnum = 1;
if ( (mlen > sufficient_len) |
(ip+mlen == iLimit) ) { /* best possible length */
ms->nextToUpdate = current+1; /* skip insertion */
return 1;
}
}
}
} }
/* no dictMatchState lookup: dicts don't have a populated HC3 table */
} }
hashTable[h] = current; /* Update Hash Table */ hashTable[h] = current; /* Update Hash Table */