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Merge pull request #2029 from terrelln/minor-opt

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[opt] Update repcodes less often
This commit is contained in:
Nick Terrell
2020-03-23 18:12:32 -07:00
committed by GitHub
parent 40414f984a 81fda0419e
commit d34204a7b7
1 changed files with 26 additions and 22 deletions
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lib/compress/zstd_opt.c
+26 -22
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@@ -894,7 +894,6 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
for (matchNb = 0; matchNb < nbMatches; matchNb++) {
U32 const offset = matches[matchNb].off;
U32 const end = matches[matchNb].len;
repcodes_t const repHistory = ZSTD_updateRep(rep, offset, ll0);
for ( ; pos <= end ; pos++ ) {
U32 const matchPrice = ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel);
U32 const sequencePrice = literalsPrice + matchPrice;
@@ -904,8 +903,6 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
opt[pos].off = offset;
opt[pos].litlen = litlen;
opt[pos].price = sequencePrice;
ZSTD_STATIC_ASSERT(sizeof(opt[pos].rep) == sizeof(repHistory));
memcpy(opt[pos].rep, &repHistory, sizeof(repHistory));
} }
last_pos = pos-1;
}
@@ -932,7 +929,6 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
opt[cur].off = 0;
opt[cur].litlen = litlen;
opt[cur].price = price;
memcpy(opt[cur].rep, opt[cur-1].rep, sizeof(opt[cur].rep));
} else {
DEBUGLOG(7, "cPos:%zi==rPos:%u : literal would cost more (%.2f>%.2f) (hist:%u,%u,%u)",
inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price),
@@ -940,6 +936,21 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
}
}
/* Set the repcodes of the current position. We must do it here
* because we rely on the repcodes of the 2nd to last sequence being
* correct to set the next chunks repcodes during the backward
* traversal.
*/
ZSTD_STATIC_ASSERT(sizeof(opt[cur].rep) == sizeof(repcodes_t));
assert(cur >= opt[cur].mlen);
if (opt[cur].mlen != 0) {
U32 const prev = cur - opt[cur].mlen;
repcodes_t newReps = ZSTD_updateRep(opt[prev].rep, opt[cur].off, opt[cur].litlen==0);
memcpy(opt[cur].rep, &newReps, sizeof(repcodes_t));
} else {
memcpy(opt[cur].rep, opt[cur - 1].rep, sizeof(repcodes_t));
}
/* last match must start at a minimum distance of 8 from oend */
if (inr > ilimit) continue;
@@ -980,7 +991,6 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
/* set prices using matches found at position == cur */
for (matchNb = 0; matchNb < nbMatches; matchNb++) {
U32 const offset = matches[matchNb].off;
repcodes_t const repHistory = ZSTD_updateRep(opt[cur].rep, offset, ll0);
U32 const lastML = matches[matchNb].len;
U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch;
U32 mlen;
@@ -1000,8 +1010,6 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
opt[pos].off = offset;
opt[pos].litlen = litlen;
opt[pos].price = price;
ZSTD_STATIC_ASSERT(sizeof(opt[pos].rep) == sizeof(repHistory));
memcpy(opt[pos].rep, &repHistory, sizeof(repHistory));
} else {
DEBUGLOG(7, "rPos:%u (ml=%2u) => new price is worse (%.2f>=%.2f)",
pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price));
@@ -1017,6 +1025,17 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
_shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
assert(opt[0].mlen == 0);
/* Set the next chunk's repcodes based on the repcodes of the beginning
* of the last match, and the last sequence. This avoids us having to
* update them while traversing the sequences.
*/
if (lastSequence.mlen != 0) {
repcodes_t reps = ZSTD_updateRep(opt[cur].rep, lastSequence.off, lastSequence.litlen==0);
memcpy(rep, &reps, sizeof(reps));
} else {
memcpy(rep, opt[cur].rep, sizeof(repcodes_t));
}
{ U32 const storeEnd = cur + 1;
U32 storeStart = storeEnd;
U32 seqPos = cur;
@@ -1053,20 +1072,6 @@ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
continue; /* will finish */
}
/* repcodes update : like ZSTD_updateRep(), but update in place */
if (offCode >= ZSTD_REP_NUM) { /* full offset */
rep[2] = rep[1];
rep[1] = rep[0];
rep[0] = offCode - ZSTD_REP_MOVE;
} else { /* repcode */
U32 const repCode = offCode + (llen==0);
if (repCode) { /* note : if repCode==0, no change */
U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
if (repCode >= 2) rep[2] = rep[1];
rep[1] = rep[0];
rep[0] = currentOffset;
} }
assert(anchor + llen <= iend);
ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen);
ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH);
@@ -1075,7 +1080,6 @@ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
} }
ZSTD_setBasePrices(optStatePtr, optLevel);
}
} /* while (ip < ilimit) */
/* Return the last literals size */