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-rw-r--r--lib/zstd/compress/zstd_lazy.c518
1 files changed, 287 insertions, 231 deletions
diff --git a/lib/zstd/compress/zstd_lazy.c b/lib/zstd/compress/zstd_lazy.c
index 0298a01a7504a5..f6b4978ceba7f1 100644
--- a/lib/zstd/compress/zstd_lazy.c
+++ b/lib/zstd/compress/zstd_lazy.c
@@ -1,5 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
/*
- * Copyright (c) Yann Collet, Facebook, Inc.
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
@@ -10,6 +11,9 @@
#include "zstd_compress_internal.h"
#include "zstd_lazy.h"
+#include "../common/bits.h" /* ZSTD_countTrailingZeros64 */
+
+#define kLazySkippingStep 8
/*-*************************************
@@ -197,8 +201,8 @@ ZSTD_DUBT_findBetterDictMatch (
U32 matchIndex = dictMatchIndex + dictIndexDelta;
if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) {
DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)",
- curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, STORE_OFFSET(curr - matchIndex), dictMatchIndex, matchIndex);
- bestLength = matchLength, *offsetPtr = STORE_OFFSET(curr - matchIndex);
+ curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, OFFSET_TO_OFFBASE(curr - matchIndex), dictMatchIndex, matchIndex);
+ bestLength = matchLength, *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
}
if (ip+matchLength == iend) { /* reached end of input : ip[matchLength] is not valid, no way to know if it's larger or smaller than match */
break; /* drop, to guarantee consistency (miss a little bit of compression) */
@@ -218,7 +222,7 @@ ZSTD_DUBT_findBetterDictMatch (
}
if (bestLength >= MINMATCH) {
- U32 const mIndex = curr - (U32)STORED_OFFSET(*offsetPtr); (void)mIndex;
+ U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offsetPtr); (void)mIndex;
DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
curr, (U32)bestLength, (U32)*offsetPtr, mIndex);
}
@@ -230,7 +234,7 @@ ZSTD_DUBT_findBetterDictMatch (
static size_t
ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
const BYTE* const ip, const BYTE* const iend,
- size_t* offsetPtr,
+ size_t* offBasePtr,
U32 const mls,
const ZSTD_dictMode_e dictMode)
{
@@ -327,8 +331,8 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
if (matchLength > bestLength) {
if (matchLength > matchEndIdx - matchIndex)
matchEndIdx = matchIndex + (U32)matchLength;
- if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) )
- bestLength = matchLength, *offsetPtr = STORE_OFFSET(curr - matchIndex);
+ if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr - matchIndex + 1) - ZSTD_highbit32((U32)*offBasePtr)) )
+ bestLength = matchLength, *offBasePtr = OFFSET_TO_OFFBASE(curr - matchIndex);
if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
if (dictMode == ZSTD_dictMatchState) {
nbCompares = 0; /* in addition to avoiding checking any
@@ -361,16 +365,16 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
if (dictMode == ZSTD_dictMatchState && nbCompares) {
bestLength = ZSTD_DUBT_findBetterDictMatch(
ms, ip, iend,
- offsetPtr, bestLength, nbCompares,
+ offBasePtr, bestLength, nbCompares,
mls, dictMode);
}
assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */
ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
if (bestLength >= MINMATCH) {
- U32 const mIndex = curr - (U32)STORED_OFFSET(*offsetPtr); (void)mIndex;
+ U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offBasePtr); (void)mIndex;
DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
- curr, (U32)bestLength, (U32)*offsetPtr, mIndex);
+ curr, (U32)bestLength, (U32)*offBasePtr, mIndex);
}
return bestLength;
}
@@ -381,14 +385,14 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
FORCE_INLINE_TEMPLATE size_t
ZSTD_BtFindBestMatch( ZSTD_matchState_t* ms,
const BYTE* const ip, const BYTE* const iLimit,
- size_t* offsetPtr,
+ size_t* offBasePtr,
const U32 mls /* template */,
const ZSTD_dictMode_e dictMode)
{
DEBUGLOG(7, "ZSTD_BtFindBestMatch");
if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */
ZSTD_updateDUBT(ms, ip, iLimit, mls);
- return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offsetPtr, mls, dictMode);
+ return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offBasePtr, mls, dictMode);
}
/* *********************************
@@ -561,7 +565,7 @@ size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nb
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
- *offsetPtr = STORE_OFFSET(curr - (matchIndex + ddsIndexDelta));
+ *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta));
if (ip+currentMl == iLimit) {
/* best possible, avoids read overflow on next attempt */
return ml;
@@ -598,7 +602,7 @@ size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nb
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
- *offsetPtr = STORE_OFFSET(curr - (matchIndex + ddsIndexDelta));
+ *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta));
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
}
@@ -617,7 +621,7 @@ size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nb
FORCE_INLINE_TEMPLATE U32 ZSTD_insertAndFindFirstIndex_internal(
ZSTD_matchState_t* ms,
const ZSTD_compressionParameters* const cParams,
- const BYTE* ip, U32 const mls)
+ const BYTE* ip, U32 const mls, U32 const lazySkipping)
{
U32* const hashTable = ms->hashTable;
const U32 hashLog = cParams->hashLog;
@@ -632,6 +636,9 @@ FORCE_INLINE_TEMPLATE U32 ZSTD_insertAndFindFirstIndex_internal(
NEXT_IN_CHAIN(idx, chainMask) = hashTable[h];
hashTable[h] = idx;
idx++;
+ /* Stop inserting every position when in the lazy skipping mode. */
+ if (lazySkipping)
+ break;
}
ms->nextToUpdate = target;
@@ -640,7 +647,7 @@ FORCE_INLINE_TEMPLATE U32 ZSTD_insertAndFindFirstIndex_internal(
U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) {
const ZSTD_compressionParameters* const cParams = &ms->cParams;
- return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch);
+ return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch, /* lazySkipping*/ 0);
}
/* inlining is important to hardwire a hot branch (template emulation) */
@@ -684,14 +691,15 @@ size_t ZSTD_HcFindBestMatch(
}
/* HC4 match finder */
- matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls);
+ matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls, ms->lazySkipping);
for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) {
size_t currentMl=0;
if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
const BYTE* const match = base + matchIndex;
assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */
- if (match[ml] == ip[ml]) /* potentially better */
+ /* read 4B starting from (match + ml + 1 - sizeof(U32)) */
+ if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */
currentMl = ZSTD_count(ip, match, iLimit);
} else {
const BYTE* const match = dictBase + matchIndex;
@@ -703,7 +711,7 @@ size_t ZSTD_HcFindBestMatch(
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
- *offsetPtr = STORE_OFFSET(curr - matchIndex);
+ *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
@@ -739,7 +747,7 @@ size_t ZSTD_HcFindBestMatch(
if (currentMl > ml) {
ml = currentMl;
assert(curr > matchIndex + dmsIndexDelta);
- *offsetPtr = STORE_OFFSET(curr - (matchIndex + dmsIndexDelta));
+ *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta));
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
@@ -756,8 +764,6 @@ size_t ZSTD_HcFindBestMatch(
* (SIMD) Row-based matchfinder
***********************************/
/* Constants for row-based hash */
-#define ZSTD_ROW_HASH_TAG_OFFSET 16 /* byte offset of hashes in the match state's tagTable from the beginning of a row */
-#define ZSTD_ROW_HASH_TAG_BITS 8 /* nb bits to use for the tag */
#define ZSTD_ROW_HASH_TAG_MASK ((1u << ZSTD_ROW_HASH_TAG_BITS) - 1)
#define ZSTD_ROW_HASH_MAX_ENTRIES 64 /* absolute maximum number of entries per row, for all configurations */
@@ -769,64 +775,19 @@ typedef U64 ZSTD_VecMask; /* Clarifies when we are interacting with a U64 repr
* Starting from the LSB, returns the idx of the next non-zero bit.
* Basically counting the nb of trailing zeroes.
*/
-static U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
- assert(val != 0);
-# if (defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4))))
- if (sizeof(size_t) == 4) {
- U32 mostSignificantWord = (U32)(val >> 32);
- U32 leastSignificantWord = (U32)val;
- if (leastSignificantWord == 0) {
- return 32 + (U32)__builtin_ctz(mostSignificantWord);
- } else {
- return (U32)__builtin_ctz(leastSignificantWord);
- }
- } else {
- return (U32)__builtin_ctzll(val);
- }
-# else
- /* Software ctz version: http://aggregate.org/MAGIC/#Trailing%20Zero%20Count
- * and: https://stackoverflow.com/questions/2709430/count-number-of-bits-in-a-64-bit-long-big-integer
- */
- val = ~val & (val - 1ULL); /* Lowest set bit mask */
- val = val - ((val >> 1) & 0x5555555555555555);
- val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL);
- return (U32)((((val + (val >> 4)) & 0xF0F0F0F0F0F0F0FULL) * 0x101010101010101ULL) >> 56);
-# endif
-}
-
-/* ZSTD_rotateRight_*():
- * Rotates a bitfield to the right by "count" bits.
- * https://en.wikipedia.org/w/index.php?title=Circular_shift&oldid=991635599#Implementing_circular_shifts
- */
-FORCE_INLINE_TEMPLATE
-U64 ZSTD_rotateRight_U64(U64 const value, U32 count) {
- assert(count < 64);
- count &= 0x3F; /* for fickle pattern recognition */
- return (value >> count) | (U64)(value << ((0U - count) & 0x3F));
-}
-
-FORCE_INLINE_TEMPLATE
-U32 ZSTD_rotateRight_U32(U32 const value, U32 count) {
- assert(count < 32);
- count &= 0x1F; /* for fickle pattern recognition */
- return (value >> count) | (U32)(value << ((0U - count) & 0x1F));
-}
-
-FORCE_INLINE_TEMPLATE
-U16 ZSTD_rotateRight_U16(U16 const value, U32 count) {
- assert(count < 16);
- count &= 0x0F; /* for fickle pattern recognition */
- return (value >> count) | (U16)(value << ((0U - count) & 0x0F));
+MEM_STATIC U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
+ return ZSTD_countTrailingZeros64(val);
}
/* ZSTD_row_nextIndex():
* Returns the next index to insert at within a tagTable row, and updates the "head"
- * value to reflect the update. Essentially cycles backwards from [0, {entries per row})
+ * value to reflect the update. Essentially cycles backwards from [1, {entries per row})
*/
FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextIndex(BYTE* const tagRow, U32 const rowMask) {
- U32 const next = (*tagRow - 1) & rowMask;
- *tagRow = (BYTE)next;
- return next;
+ U32 next = (*tagRow-1) & rowMask;
+ next += (next == 0) ? rowMask : 0; /* skip first position */
+ *tagRow = (BYTE)next;
+ return next;
}
/* ZSTD_isAligned():
@@ -840,7 +801,7 @@ MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) {
/* ZSTD_row_prefetch():
* Performs prefetching for the hashTable and tagTable at a given row.
*/
-FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, U16 const* tagTable, U32 const relRow, U32 const rowLog) {
+FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, BYTE const* tagTable, U32 const relRow, U32 const rowLog) {
PREFETCH_L1(hashTable + relRow);
if (rowLog >= 5) {
PREFETCH_L1(hashTable + relRow + 16);
@@ -864,13 +825,13 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const B
U32 idx, const BYTE* const iLimit)
{
U32 const* const hashTable = ms->hashTable;
- U16 const* const tagTable = ms->tagTable;
+ BYTE const* const tagTable = ms->tagTable;
U32 const hashLog = ms->rowHashLog;
U32 const maxElemsToPrefetch = (base + idx) > iLimit ? 0 : (U32)(iLimit - (base + idx) + 1);
U32 const lim = idx + MIN(ZSTD_ROW_HASH_CACHE_SIZE, maxElemsToPrefetch);
for (; idx < lim; ++idx) {
- U32 const hash = (U32)ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
+ U32 const hash = (U32)ZSTD_hashPtrSalted(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt);
U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
ms->hashCache[idx & ZSTD_ROW_HASH_CACHE_MASK] = hash;
@@ -886,11 +847,12 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const B
* base + idx + ZSTD_ROW_HASH_CACHE_SIZE. Also prefetches the appropriate rows from hashTable and tagTable.
*/
FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextCachedHash(U32* cache, U32 const* hashTable,
- U16 const* tagTable, BYTE const* base,
+ BYTE const* tagTable, BYTE const* base,
U32 idx, U32 const hashLog,
- U32 const rowLog, U32 const mls)
+ U32 const rowLog, U32 const mls,
+ U64 const hashSalt)
{
- U32 const newHash = (U32)ZSTD_hashPtr(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
+ U32 const newHash = (U32)ZSTD_hashPtrSalted(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt);
U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
{ U32 const hash = cache[idx & ZSTD_ROW_HASH_CACHE_MASK];
@@ -908,22 +870,21 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_update_internalImpl(ZSTD_matchState_t* ms,
U32 const rowMask, U32 const useCache)
{
U32* const hashTable = ms->hashTable;
- U16* const tagTable = ms->tagTable;
+ BYTE* const tagTable = ms->tagTable;
U32 const hashLog = ms->rowHashLog;
const BYTE* const base = ms->window.base;
DEBUGLOG(6, "ZSTD_row_update_internalImpl(): updateStartIdx=%u, updateEndIdx=%u", updateStartIdx, updateEndIdx);
for (; updateStartIdx < updateEndIdx; ++updateStartIdx) {
- U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls)
- : (U32)ZSTD_hashPtr(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
+ U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls, ms->hashSalt)
+ : (U32)ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt);
U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
U32* const row = hashTable + relRow;
- BYTE* tagRow = (BYTE*)(tagTable + relRow); /* Though tagTable is laid out as a table of U16, each tag is only 1 byte.
- Explicit cast allows us to get exact desired position within each row */
+ BYTE* tagRow = tagTable + relRow;
U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
- assert(hash == ZSTD_hashPtr(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls));
- ((BYTE*)tagRow)[pos + ZSTD_ROW_HASH_TAG_OFFSET] = hash & ZSTD_ROW_HASH_TAG_MASK;
+ assert(hash == ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt));
+ tagRow[pos] = hash & ZSTD_ROW_HASH_TAG_MASK;
row[pos] = updateStartIdx;
}
}
@@ -971,7 +932,35 @@ void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) {
const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */);
DEBUGLOG(5, "ZSTD_row_update(), rowLog=%u", rowLog);
- ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* dont use cache */);
+ ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* don't use cache */);
+}
+
+/* Returns the mask width of bits group of which will be set to 1. Given not all
+ * architectures have easy movemask instruction, this helps to iterate over
+ * groups of bits easier and faster.
+ */
+FORCE_INLINE_TEMPLATE U32
+ZSTD_row_matchMaskGroupWidth(const U32 rowEntries)
+{
+ assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
+ assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES);
+ (void)rowEntries;
+#if defined(ZSTD_ARCH_ARM_NEON)
+ /* NEON path only works for little endian */
+ if (!MEM_isLittleEndian()) {
+ return 1;
+ }
+ if (rowEntries == 16) {
+ return 4;
+ }
+ if (rowEntries == 32) {
+ return 2;
+ }
+ if (rowEntries == 64) {
+ return 1;
+ }
+#endif
+ return 1;
}
#if defined(ZSTD_ARCH_X86_SSE2)
@@ -994,71 +983,82 @@ ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U
}
#endif
-/* Returns a ZSTD_VecMask (U32) that has the nth bit set to 1 if the newly-computed "tag" matches
- * the hash at the nth position in a row of the tagTable.
- * Each row is a circular buffer beginning at the value of "head". So we must rotate the "matches" bitfield
- * to match up with the actual layout of the entries within the hashTable */
+#if defined(ZSTD_ARCH_ARM_NEON)
+FORCE_INLINE_TEMPLATE ZSTD_VecMask
+ZSTD_row_getNEONMask(const U32 rowEntries, const BYTE* const src, const BYTE tag, const U32 headGrouped)
+{
+ assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
+ if (rowEntries == 16) {
+ /* vshrn_n_u16 shifts by 4 every u16 and narrows to 8 lower bits.
+ * After that groups of 4 bits represent the equalMask. We lower
+ * all bits except the highest in these groups by doing AND with
+ * 0x88 = 0b10001000.
+ */
+ const uint8x16_t chunk = vld1q_u8(src);
+ const uint16x8_t equalMask = vreinterpretq_u16_u8(vceqq_u8(chunk, vdupq_n_u8(tag)));
+ const uint8x8_t res = vshrn_n_u16(equalMask, 4);
+ const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0);
+ return ZSTD_rotateRight_U64(matches, headGrouped) & 0x8888888888888888ull;
+ } else if (rowEntries == 32) {
+ /* Same idea as with rowEntries == 16 but doing AND with
+ * 0x55 = 0b01010101.
+ */
+ const uint16x8x2_t chunk = vld2q_u16((const uint16_t*)(const void*)src);
+ const uint8x16_t chunk0 = vreinterpretq_u8_u16(chunk.val[0]);
+ const uint8x16_t chunk1 = vreinterpretq_u8_u16(chunk.val[1]);
+ const uint8x16_t dup = vdupq_n_u8(tag);
+ const uint8x8_t t0 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk0, dup)), 6);
+ const uint8x8_t t1 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk1, dup)), 6);
+ const uint8x8_t res = vsli_n_u8(t0, t1, 4);
+ const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0) ;
+ return ZSTD_rotateRight_U64(matches, headGrouped) & 0x5555555555555555ull;
+ } else { /* rowEntries == 64 */
+ const uint8x16x4_t chunk = vld4q_u8(src);
+ const uint8x16_t dup = vdupq_n_u8(tag);
+ const uint8x16_t cmp0 = vceqq_u8(chunk.val[0], dup);
+ const uint8x16_t cmp1 = vceqq_u8(chunk.val[1], dup);
+ const uint8x16_t cmp2 = vceqq_u8(chunk.val[2], dup);
+ const uint8x16_t cmp3 = vceqq_u8(chunk.val[3], dup);
+
+ const uint8x16_t t0 = vsriq_n_u8(cmp1, cmp0, 1);
+ const uint8x16_t t1 = vsriq_n_u8(cmp3, cmp2, 1);
+ const uint8x16_t t2 = vsriq_n_u8(t1, t0, 2);
+ const uint8x16_t t3 = vsriq_n_u8(t2, t2, 4);
+ const uint8x8_t t4 = vshrn_n_u16(vreinterpretq_u16_u8(t3), 4);
+ const U64 matches = vget_lane_u64(vreinterpret_u64_u8(t4), 0);
+ return ZSTD_rotateRight_U64(matches, headGrouped);
+ }
+}
+#endif
+
+/* Returns a ZSTD_VecMask (U64) that has the nth group (determined by
+ * ZSTD_row_matchMaskGroupWidth) of bits set to 1 if the newly-computed "tag"
+ * matches the hash at the nth position in a row of the tagTable.
+ * Each row is a circular buffer beginning at the value of "headGrouped". So we
+ * must rotate the "matches" bitfield to match up with the actual layout of the
+ * entries within the hashTable */
FORCE_INLINE_TEMPLATE ZSTD_VecMask
-ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 head, const U32 rowEntries)
+ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 headGrouped, const U32 rowEntries)
{
- const BYTE* const src = tagRow + ZSTD_ROW_HASH_TAG_OFFSET;
+ const BYTE* const src = tagRow;
assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES);
+ assert(ZSTD_row_matchMaskGroupWidth(rowEntries) * rowEntries <= sizeof(ZSTD_VecMask) * 8);
#if defined(ZSTD_ARCH_X86_SSE2)
- return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, head);
+ return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, headGrouped);
#else /* SW or NEON-LE */
# if defined(ZSTD_ARCH_ARM_NEON)
/* This NEON path only works for little endian - otherwise use SWAR below */
if (MEM_isLittleEndian()) {
- if (rowEntries == 16) {
- const uint8x16_t chunk = vld1q_u8(src);
- const uint16x8_t equalMask = vreinterpretq_u16_u8(vceqq_u8(chunk, vdupq_n_u8(tag)));
- const uint16x8_t t0 = vshlq_n_u16(equalMask, 7);
- const uint32x4_t t1 = vreinterpretq_u32_u16(vsriq_n_u16(t0, t0, 14));
- const uint64x2_t t2 = vreinterpretq_u64_u32(vshrq_n_u32(t1, 14));
- const uint8x16_t t3 = vreinterpretq_u8_u64(vsraq_n_u64(t2, t2, 28));
- const U16 hi = (U16)vgetq_lane_u8(t3, 8);
- const U16 lo = (U16)vgetq_lane_u8(t3, 0);
- return ZSTD_rotateRight_U16((hi << 8) | lo, head);
- } else if (rowEntries == 32) {
- const uint16x8x2_t chunk = vld2q_u16((const U16*)(const void*)src);
- const uint8x16_t chunk0 = vreinterpretq_u8_u16(chunk.val[0]);
- const uint8x16_t chunk1 = vreinterpretq_u8_u16(chunk.val[1]);
- const uint8x16_t equalMask0 = vceqq_u8(chunk0, vdupq_n_u8(tag));
- const uint8x16_t equalMask1 = vceqq_u8(chunk1, vdupq_n_u8(tag));
- const int8x8_t pack0 = vqmovn_s16(vreinterpretq_s16_u8(equalMask0));
- const int8x8_t pack1 = vqmovn_s16(vreinterpretq_s16_u8(equalMask1));
- const uint8x8_t t0 = vreinterpret_u8_s8(pack0);
- const uint8x8_t t1 = vreinterpret_u8_s8(pack1);
- const uint8x8_t t2 = vsri_n_u8(t1, t0, 2);
- const uint8x8x2_t t3 = vuzp_u8(t2, t0);
- const uint8x8_t t4 = vsri_n_u8(t3.val[1], t3.val[0], 4);
- const U32 matches = vget_lane_u32(vreinterpret_u32_u8(t4), 0);
- return ZSTD_rotateRight_U32(matches, head);
- } else { /* rowEntries == 64 */
- const uint8x16x4_t chunk = vld4q_u8(src);
- const uint8x16_t dup = vdupq_n_u8(tag);
- const uint8x16_t cmp0 = vceqq_u8(chunk.val[0], dup);
- const uint8x16_t cmp1 = vceqq_u8(chunk.val[1], dup);
- const uint8x16_t cmp2 = vceqq_u8(chunk.val[2], dup);
- const uint8x16_t cmp3 = vceqq_u8(chunk.val[3], dup);
-
- const uint8x16_t t0 = vsriq_n_u8(cmp1, cmp0, 1);
- const uint8x16_t t1 = vsriq_n_u8(cmp3, cmp2, 1);
- const uint8x16_t t2 = vsriq_n_u8(t1, t0, 2);
- const uint8x16_t t3 = vsriq_n_u8(t2, t2, 4);
- const uint8x8_t t4 = vshrn_n_u16(vreinterpretq_u16_u8(t3), 4);
- const U64 matches = vget_lane_u64(vreinterpret_u64_u8(t4), 0);
- return ZSTD_rotateRight_U64(matches, head);
- }
+ return ZSTD_row_getNEONMask(rowEntries, src, tag, headGrouped);
}
# endif /* ZSTD_ARCH_ARM_NEON */
/* SWAR */
- { const size_t chunkSize = sizeof(size_t);
+ { const int chunkSize = sizeof(size_t);
const size_t shiftAmount = ((chunkSize * 8) - chunkSize);
const size_t xFF = ~((size_t)0);
const size_t x01 = xFF / 0xFF;
@@ -1091,11 +1091,11 @@ ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 head,
}
matches = ~matches;
if (rowEntries == 16) {
- return ZSTD_rotateRight_U16((U16)matches, head);
+ return ZSTD_rotateRight_U16((U16)matches, headGrouped);
} else if (rowEntries == 32) {
- return ZSTD_rotateRight_U32((U32)matches, head);
+ return ZSTD_rotateRight_U32((U32)matches, headGrouped);
} else {
- return ZSTD_rotateRight_U64((U64)matches, head);
+ return ZSTD_rotateRight_U64((U64)matches, headGrouped);
}
}
#endif
@@ -1125,7 +1125,7 @@ size_t ZSTD_RowFindBestMatch(
const U32 rowLog)
{
U32* const hashTable = ms->hashTable;
- U16* const tagTable = ms->tagTable;
+ BYTE* const tagTable = ms->tagTable;
U32* const hashCache = ms->hashCache;
const U32 hashLog = ms->rowHashLog;
const ZSTD_compressionParameters* const cParams = &ms->cParams;
@@ -1143,8 +1143,11 @@ size_t ZSTD_RowFindBestMatch(
const U32 rowEntries = (1U << rowLog);
const U32 rowMask = rowEntries - 1;
const U32 cappedSearchLog = MIN(cParams->searchLog, rowLog); /* nb of searches is capped at nb entries per row */
+ const U32 groupWidth = ZSTD_row_matchMaskGroupWidth(rowEntries);
+ const U64 hashSalt = ms->hashSalt;
U32 nbAttempts = 1U << cappedSearchLog;
size_t ml=4-1;
+ U32 hash;
/* DMS/DDS variables that may be referenced laster */
const ZSTD_matchState_t* const dms = ms->dictMatchState;
@@ -1168,7 +1171,7 @@ size_t ZSTD_RowFindBestMatch(
if (dictMode == ZSTD_dictMatchState) {
/* Prefetch DMS rows */
U32* const dmsHashTable = dms->hashTable;
- U16* const dmsTagTable = dms->tagTable;
+ BYTE* const dmsTagTable = dms->tagTable;
U32 const dmsHash = (U32)ZSTD_hashPtr(ip, dms->rowHashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
U32 const dmsRelRow = (dmsHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
dmsTag = dmsHash & ZSTD_ROW_HASH_TAG_MASK;
@@ -1178,23 +1181,34 @@ size_t ZSTD_RowFindBestMatch(
}
/* Update the hashTable and tagTable up to (but not including) ip */
- ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 1 /* useCache */);
+ if (!ms->lazySkipping) {
+ ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 1 /* useCache */);
+ hash = ZSTD_row_nextCachedHash(hashCache, hashTable, tagTable, base, curr, hashLog, rowLog, mls, hashSalt);
+ } else {
+ /* Stop inserting every position when in the lazy skipping mode.
+ * The hash cache is also not kept up to date in this mode.
+ */
+ hash = (U32)ZSTD_hashPtrSalted(ip, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt);
+ ms->nextToUpdate = curr;
+ }
+ ms->hashSaltEntropy += hash; /* collect salt entropy */
+
{ /* Get the hash for ip, compute the appropriate row */
- U32 const hash = ZSTD_row_nextCachedHash(hashCache, hashTable, tagTable, base, curr, hashLog, rowLog, mls);
U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
U32 const tag = hash & ZSTD_ROW_HASH_TAG_MASK;
U32* const row = hashTable + relRow;
BYTE* tagRow = (BYTE*)(tagTable + relRow);
- U32 const head = *tagRow & rowMask;
+ U32 const headGrouped = (*tagRow & rowMask) * groupWidth;
U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES];
size_t numMatches = 0;
size_t currMatch = 0;
- ZSTD_VecMask matches = ZSTD_row_getMatchMask(tagRow, (BYTE)tag, head, rowEntries);
+ ZSTD_VecMask matches = ZSTD_row_getMatchMask(tagRow, (BYTE)tag, headGrouped, rowEntries);
/* Cycle through the matches and prefetch */
- for (; (matches > 0) && (nbAttempts > 0); --nbAttempts, matches &= (matches - 1)) {
- U32 const matchPos = (head + ZSTD_VecMask_next(matches)) & rowMask;
+ for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) {
+ U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask;
U32 const matchIndex = row[matchPos];
+ if(matchPos == 0) continue;
assert(numMatches < rowEntries);
if (matchIndex < lowLimit)
break;
@@ -1204,13 +1218,14 @@ size_t ZSTD_RowFindBestMatch(
PREFETCH_L1(dictBase + matchIndex);
}
matchBuffer[numMatches++] = matchIndex;
+ --nbAttempts;
}
/* Speed opt: insert current byte into hashtable too. This allows us to avoid one iteration of the loop
in ZSTD_row_update_internal() at the next search. */
{
U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
- tagRow[pos + ZSTD_ROW_HASH_TAG_OFFSET] = (BYTE)tag;
+ tagRow[pos] = (BYTE)tag;
row[pos] = ms->nextToUpdate++;
}
@@ -1224,7 +1239,8 @@ size_t ZSTD_RowFindBestMatch(
if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
const BYTE* const match = base + matchIndex;
assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */
- if (match[ml] == ip[ml]) /* potentially better */
+ /* read 4B starting from (match + ml + 1 - sizeof(U32)) */
+ if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */
currentMl = ZSTD_count(ip, match, iLimit);
} else {
const BYTE* const match = dictBase + matchIndex;
@@ -1236,7 +1252,7 @@ size_t ZSTD_RowFindBestMatch(
/* Save best solution */
if (currentMl > ml) {
ml = currentMl;
- *offsetPtr = STORE_OFFSET(curr - matchIndex);
+ *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
}
@@ -1254,19 +1270,21 @@ size_t ZSTD_RowFindBestMatch(
const U32 dmsSize = (U32)(dmsEnd - dmsBase);
const U32 dmsIndexDelta = dictLimit - dmsSize;
- { U32 const head = *dmsTagRow & rowMask;
+ { U32 const headGrouped = (*dmsTagRow & rowMask) * groupWidth;
U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES];
size_t numMatches = 0;
size_t currMatch = 0;
- ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, head, rowEntries);
+ ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, headGrouped, rowEntries);
- for (; (matches > 0) && (nbAttempts > 0); --nbAttempts, matches &= (matches - 1)) {
- U32 const matchPos = (head + ZSTD_VecMask_next(matches)) & rowMask;
+ for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) {
+ U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask;
U32 const matchIndex = dmsRow[matchPos];
+ if(matchPos == 0) continue;
if (matchIndex < dmsLowestIndex)
break;
PREFETCH_L1(dmsBase + matchIndex);
matchBuffer[numMatches++] = matchIndex;
+ --nbAttempts;
}
/* Return the longest match */
@@ -1285,7 +1303,7 @@ size_t ZSTD_RowFindBestMatch(
if (currentMl > ml) {
ml = currentMl;
assert(curr > matchIndex + dmsIndexDelta);
- *offsetPtr = STORE_OFFSET(curr - (matchIndex + dmsIndexDelta));
+ *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta));
if (ip+currentMl == iLimit) break;
}
}
@@ -1491,7 +1509,8 @@ ZSTD_compressBlock_lazy_generic(
const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6);
const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6);
- U32 offset_1 = rep[0], offset_2 = rep[1], savedOffset=0;
+ U32 offset_1 = rep[0], offset_2 = rep[1];
+ U32 offsetSaved1 = 0, offsetSaved2 = 0;
const int isDMS = dictMode == ZSTD_dictMatchState;
const int isDDS = dictMode == ZSTD_dedicatedDictSearch;
@@ -1512,8 +1531,8 @@ ZSTD_compressBlock_lazy_generic(
U32 const curr = (U32)(ip - base);
U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, ms->cParams.windowLog);
U32 const maxRep = curr - windowLow;
- if (offset_2 > maxRep) savedOffset = offset_2, offset_2 = 0;
- if (offset_1 > maxRep) savedOffset = offset_1, offset_1 = 0;
+ if (offset_2 > maxRep) offsetSaved2 = offset_2, offset_2 = 0;
+ if (offset_1 > maxRep) offsetSaved1 = offset_1, offset_1 = 0;
}
if (isDxS) {
/* dictMatchState repCode checks don't currently handle repCode == 0
@@ -1522,10 +1541,11 @@ ZSTD_compressBlock_lazy_generic(
assert(offset_2 <= dictAndPrefixLength);
}
+ /* Reset the lazy skipping state */
+ ms->lazySkipping = 0;
+
if (searchMethod == search_rowHash) {
- ZSTD_row_fillHashCache(ms, base, rowLog,
- MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */),
- ms->nextToUpdate, ilimit);
+ ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
}
/* Match Loop */
@@ -1537,7 +1557,7 @@ ZSTD_compressBlock_lazy_generic(
#endif
while (ip < ilimit) {
size_t matchLength=0;
- size_t offcode=STORE_REPCODE_1;
+ size_t offBase = REPCODE1_TO_OFFBASE;
const BYTE* start=ip+1;
DEBUGLOG(7, "search baseline (depth 0)");
@@ -1562,14 +1582,23 @@ ZSTD_compressBlock_lazy_generic(
}
/* first search (depth 0) */
- { size_t offsetFound = 999999999;
- size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offsetFound, mls, rowLog, searchMethod, dictMode);
+ { size_t offbaseFound = 999999999;
+ size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offbaseFound, mls, rowLog, searchMethod, dictMode);
if (ml2 > matchLength)
- matchLength = ml2, start = ip, offcode=offsetFound;
+ matchLength = ml2, start = ip, offBase = offbaseFound;
}
if (matchLength < 4) {
- ip += ((ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */
+ size_t const step = ((size_t)(ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */;
+ ip += step;
+ /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time.
+ * In this mode we stop inserting every position into our tables, and only insert
+ * positions that we search, which is one in step positions.
+ * The exact cutoff is flexible, I've just chosen a number that is reasonably high,
+ * so we minimize the compression ratio loss in "normal" scenarios. This mode gets
+ * triggered once we've gone 2KB without finding any matches.
+ */
+ ms->lazySkipping = step > kLazySkippingStep;
continue;
}
@@ -1579,12 +1608,12 @@ ZSTD_compressBlock_lazy_generic(
DEBUGLOG(7, "search depth 1");
ip ++;
if ( (dictMode == ZSTD_noDict)
- && (offcode) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
+ && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
int const gain2 = (int)(mlRep * 3);
- int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
+ int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1);
if ((mlRep >= 4) && (gain2 > gain1))
- matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
+ matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
}
if (isDxS) {
const U32 repIndex = (U32)(ip - base) - offset_1;
@@ -1596,17 +1625,17 @@ ZSTD_compressBlock_lazy_generic(
const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;
int const gain2 = (int)(mlRep * 3);
- int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
+ int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1);
if ((mlRep >= 4) && (gain2 > gain1))
- matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
+ matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
}
}
- { size_t offset2=999999999;
- size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, dictMode);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 4);
+ { size_t ofbCandidate=999999999;
+ size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode);
+ int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4);
if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offcode = offset2, start = ip;
+ matchLength = ml2, offBase = ofbCandidate, start = ip;
continue; /* search a better one */
} }
@@ -1615,12 +1644,12 @@ ZSTD_compressBlock_lazy_generic(
DEBUGLOG(7, "search depth 2");
ip ++;
if ( (dictMode == ZSTD_noDict)
- && (offcode) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
+ && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
int const gain2 = (int)(mlRep * 4);
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1);
if ((mlRep >= 4) && (gain2 > gain1))
- matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
+ matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
}
if (isDxS) {
const U32 repIndex = (U32)(ip - base) - offset_1;
@@ -1632,17 +1661,17 @@ ZSTD_compressBlock_lazy_generic(
const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;
int const gain2 = (int)(mlRep * 4);
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1);
if ((mlRep >= 4) && (gain2 > gain1))
- matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
+ matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
}
}
- { size_t offset2=999999999;
- size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, dictMode);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 7);
+ { size_t ofbCandidate=999999999;
+ size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode);
+ int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7);
if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offcode = offset2, start = ip;
+ matchLength = ml2, offBase = ofbCandidate, start = ip;
continue;
} } }
break; /* nothing found : store previous solution */
@@ -1653,26 +1682,33 @@ ZSTD_compressBlock_lazy_generic(
* notably if `value` is unsigned, resulting in a large positive `-value`.
*/
/* catch up */
- if (STORED_IS_OFFSET(offcode)) {
+ if (OFFBASE_IS_OFFSET(offBase)) {
if (dictMode == ZSTD_noDict) {
- while ( ((start > anchor) & (start - STORED_OFFSET(offcode) > prefixLowest))
- && (start[-1] == (start-STORED_OFFSET(offcode))[-1]) ) /* only search for offset within prefix */
+ while ( ((start > anchor) & (start - OFFBASE_TO_OFFSET(offBase) > prefixLowest))
+ && (start[-1] == (start-OFFBASE_TO_OFFSET(offBase))[-1]) ) /* only search for offset within prefix */
{ start--; matchLength++; }
}
if (isDxS) {
- U32 const matchIndex = (U32)((size_t)(start-base) - STORED_OFFSET(offcode));
+ U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase));
const BYTE* match = (matchIndex < prefixLowestIndex) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex;
const BYTE* const mStart = (matchIndex < prefixLowestIndex) ? dictLowest : prefixLowest;
while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */
}
- offset_2 = offset_1; offset_1 = (U32)STORED_OFFSET(offcode);
+ offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase);
}
/* store sequence */
_storeSequence:
{ size_t const litLength = (size_t)(start - anchor);
- ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offcode, matchLength);
+ ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength);
anchor = ip = start + matchLength;
}
+ if (ms->lazySkipping) {
+ /* We've found a match, disable lazy skipping mode, and refill the hash cache. */
+ if (searchMethod == search_rowHash) {
+ ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
+ }
+ ms->lazySkipping = 0;
+ }
/* check immediate repcode */
if (isDxS) {
@@ -1686,8 +1722,8 @@ _storeSequence:
&& (MEM_read32(repMatch) == MEM_read32(ip)) ) {
const BYTE* const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend;
matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd2, prefixLowest) + 4;
- offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap offset_2 <=> offset_1 */
- ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength);
+ offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset_2 <=> offset_1 */
+ ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength);
ip += matchLength;
anchor = ip;
continue;
@@ -1701,16 +1737,20 @@ _storeSequence:
&& (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) {
/* store sequence */
matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
- offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap repcodes */
- ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength);
+ offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap repcodes */
+ ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength);
ip += matchLength;
anchor = ip;
continue; /* faster when present ... (?) */
} } }
- /* Save reps for next block */
- rep[0] = offset_1 ? offset_1 : savedOffset;
- rep[1] = offset_2 ? offset_2 : savedOffset;
+ /* If offset_1 started invalid (offsetSaved1 != 0) and became valid (offset_1 != 0),
+ * rotate saved offsets. See comment in ZSTD_compressBlock_fast_noDict for more context. */
+ offsetSaved2 = ((offsetSaved1 != 0) && (offset_1 != 0)) ? offsetSaved1 : offsetSaved2;
+
+ /* save reps for next block */
+ rep[0] = offset_1 ? offset_1 : offsetSaved1;
+ rep[1] = offset_2 ? offset_2 : offsetSaved2;
/* Return the last literals size */
return (size_t)(iend - anchor);
@@ -1886,12 +1926,13 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
DEBUGLOG(5, "ZSTD_compressBlock_lazy_extDict_generic (searchFunc=%u)", (U32)searchMethod);
+ /* Reset the lazy skipping state */
+ ms->lazySkipping = 0;
+
/* init */
ip += (ip == prefixStart);
if (searchMethod == search_rowHash) {
- ZSTD_row_fillHashCache(ms, base, rowLog,
- MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */),
- ms->nextToUpdate, ilimit);
+ ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
}
/* Match Loop */
@@ -1903,7 +1944,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
#endif
while (ip < ilimit) {
size_t matchLength=0;
- size_t offcode=STORE_REPCODE_1;
+ size_t offBase = REPCODE1_TO_OFFBASE;
const BYTE* start=ip+1;
U32 curr = (U32)(ip-base);
@@ -1922,14 +1963,23 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
} }
/* first search (depth 0) */
- { size_t offsetFound = 999999999;
- size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offsetFound, mls, rowLog, searchMethod, ZSTD_extDict);
+ { size_t ofbCandidate = 999999999;
+ size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict);
if (ml2 > matchLength)
- matchLength = ml2, start = ip, offcode=offsetFound;
+ matchLength = ml2, start = ip, offBase = ofbCandidate;
}
if (matchLength < 4) {
- ip += ((ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */
+ size_t const step = ((size_t)(ip-anchor) >> kSearchStrength);
+ ip += step + 1; /* jump faster over incompressible sections */
+ /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time.
+ * In this mode we stop inserting every position into our tables, and only insert
+ * positions that we search, which is one in step positions.
+ * The exact cutoff is flexible, I've just chosen a number that is reasonably high,
+ * so we minimize the compression ratio loss in "normal" scenarios. This mode gets
+ * triggered once we've gone 2KB without finding any matches.
+ */
+ ms->lazySkipping = step > kLazySkippingStep;
continue;
}
@@ -1939,7 +1989,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
ip ++;
curr++;
/* check repCode */
- if (offcode) {
+ if (offBase) {
const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog);
const U32 repIndex = (U32)(curr - offset_1);
const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
@@ -1951,18 +2001,18 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
int const gain2 = (int)(repLength * 3);
- int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
+ int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1);
if ((repLength >= 4) && (gain2 > gain1))
- matchLength = repLength, offcode = STORE_REPCODE_1, start = ip;
+ matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip;
} }
/* search match, depth 1 */
- { size_t offset2=999999999;
- size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, ZSTD_extDict);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 4);
+ { size_t ofbCandidate = 999999999;
+ size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict);
+ int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4);
if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offcode = offset2, start = ip;
+ matchLength = ml2, offBase = ofbCandidate, start = ip;
continue; /* search a better one */
} }
@@ -1971,7 +2021,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
ip ++;
curr++;
/* check repCode */
- if (offcode) {
+ if (offBase) {
const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog);
const U32 repIndex = (U32)(curr - offset_1);
const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
@@ -1983,38 +2033,45 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
int const gain2 = (int)(repLength * 4);
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1);
if ((repLength >= 4) && (gain2 > gain1))
- matchLength = repLength, offcode = STORE_REPCODE_1, start = ip;
+ matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip;
} }
/* search match, depth 2 */
- { size_t offset2=999999999;
- size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, ZSTD_extDict);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 7);
+ { size_t ofbCandidate = 999999999;
+ size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict);
+ int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
+ int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7);
if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offcode = offset2, start = ip;
+ matchLength = ml2, offBase = ofbCandidate, start = ip;
continue;
} } }
break; /* nothing found : store previous solution */
}
/* catch up */
- if (STORED_IS_OFFSET(offcode)) {
- U32 const matchIndex = (U32)((size_t)(start-base) - STORED_OFFSET(offcode));
+ if (OFFBASE_IS_OFFSET(offBase)) {
+ U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase));
const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex;
const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart;
while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */
- offset_2 = offset_1; offset_1 = (U32)STORED_OFFSET(offcode);
+ offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase);
}
/* store sequence */
_storeSequence:
{ size_t const litLength = (size_t)(start - anchor);
- ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offcode, matchLength);
+ ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength);
anchor = ip = start + matchLength;
}
+ if (ms->lazySkipping) {
+ /* We've found a match, disable lazy skipping mode, and refill the hash cache. */
+ if (searchMethod == search_rowHash) {
+ ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
+ }
+ ms->lazySkipping = 0;
+ }
/* check immediate repcode */
while (ip <= ilimit) {
@@ -2029,8 +2086,8 @@ _storeSequence:
/* repcode detected we should take it */
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
- offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap offset history */
- ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength);
+ offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset history */
+ ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength);
ip += matchLength;
anchor = ip;
continue; /* faster when present ... (?) */
@@ -2096,7 +2153,6 @@ size_t ZSTD_compressBlock_lazy_extDict_row(
size_t ZSTD_compressBlock_lazy2_extDict_row(
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
void const* src, size_t srcSize)
-
{
return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2);
}
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-05-31 10:06:50 +0000