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Skip most long matches in lazy hash table update

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This commit is contained in:
Sen Huang 2021-08-18 06:52:17 -07:00
parent 9ef055d706
commit b8fd6bf30c
2 changed files with 804 additions and 793 deletions
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17
lib/compress/zstd_lazy.c
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@ -971,7 +971,7 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, U16 const* ta
* Fill up the hash cache starting at idx, prefetching up to ZSTD_ROW_HASH_CACHE_SIZE entries,
* but not beyond iLimit.
*/
static void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const BYTE* base,
FORCE_INLINE_TEMPLATE void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const BYTE* base,
U32 const rowLog, U32 const mls,
U32 idx, const BYTE* const iLimit)
{
@ -1022,9 +1022,20 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const
U32* const hashTable = ms->hashTable;
U16* const tagTable = ms->tagTable;
U32 const hashLog = ms->rowHashLog;
U32 idx = ms->nextToUpdate;
const BYTE* const base = ms->window.base;
const U32 target = (U32)(ip - base);
U32 idx = ms->nextToUpdate;
const U32 kMaxPositionsToUpdate = 256;
assert(target >= idx);
if (useCache) {
/* Only skip positions when using hash cache, i.e.
if we are loading a dict, don't skip anything */
if (UNLIKELY(target - idx > kMaxPositionsToUpdate)) {
idx = target - kMaxPositionsToUpdate;
ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1);
}
}
DEBUGLOG(6, "ZSTD_row_update_internal(): nextToUpdate=%u, current=%u", idx, target);
for (; idx < target; ++idx) {
@ -1037,7 +1048,7 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const
U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
assert(hash == ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls));
((BYTE*)tagRow)[pos + ZSTD_ROW_HASH_TAG_OFFSET] = hash & ZSTD_ROW_HASH_TAG_MASK;
tagRow[pos + ZSTD_ROW_HASH_TAG_OFFSET] = hash & ZSTD_ROW_HASH_TAG_MASK;
row[pos] = idx;
}
ms->nextToUpdate = target;

1580
tests/regression/results.csv
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