zstd: Update to upstream version 1.5.2

Release notes:
- https://github.com/facebook/zstd/releases/tag/v1.5.1
- https://github.com/facebook/zstd/releases/tag/v1.5.2

1 files changed, 482 insertions, 562 deletions

diff --git a/thirdparty/zstd/compress/zstd_lazy.c b/thirdparty/zstd/compress/zstd_lazy.c
index 3d523e8472..2e38dcb46d 100644
--- a/thirdparty/zstd/compress/zstd_lazy.c
+++ b/thirdparty/zstd/compress/zstd_lazy.c
@@ -61,7 +61,7 @@ ZSTD_updateDUBT(ZSTD_matchState_t* ms,
  *  assumption : curr >= btlow == (curr - btmask)
  *  doesn't fail */
 static void
-ZSTD_insertDUBT1(ZSTD_matchState_t* ms,
+ZSTD_insertDUBT1(const ZSTD_matchState_t* ms,
                  U32 curr, const BYTE* inputEnd,
                  U32 nbCompares, U32 btLow,
                  const ZSTD_dictMode_e dictMode)
@@ -93,7 +93,7 @@ ZSTD_insertDUBT1(ZSTD_matchState_t* ms,
     assert(curr >= btLow);
     assert(ip < iend);   /* condition for ZSTD_count */
 
-    while (nbCompares-- && (matchIndex > windowLow)) {
+    for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
         U32* const nextPtr = bt + 2*(matchIndex & btMask);
         size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
         assert(matchIndex < curr);
@@ -151,7 +151,7 @@ ZSTD_insertDUBT1(ZSTD_matchState_t* ms,
 
 static size_t
 ZSTD_DUBT_findBetterDictMatch (
-        ZSTD_matchState_t* ms,
+        const ZSTD_matchState_t* ms,
         const BYTE* const ip, const BYTE* const iend,
         size_t* offsetPtr,
         size_t bestLength,
@@ -185,7 +185,7 @@ ZSTD_DUBT_findBetterDictMatch (
     (void)dictMode;
     assert(dictMode == ZSTD_dictMatchState);
 
-    while (nbCompares-- && (dictMatchIndex > dictLowLimit)) {
+    for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) {
         U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask);
         size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
         const BYTE* match = dictBase + dictMatchIndex;
@@ -197,8 +197,8 @@ 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, ZSTD_REP_MOVE + curr - matchIndex, dictMatchIndex, matchIndex);
-                bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + curr - matchIndex;
+                    curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, STORE_OFFSET(curr - matchIndex), dictMatchIndex, matchIndex);
+                bestLength = matchLength, *offsetPtr = STORE_OFFSET(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 +218,7 @@ ZSTD_DUBT_findBetterDictMatch (
     }
 
     if (bestLength >= MINMATCH) {
-        U32 const mIndex = curr - ((U32)*offsetPtr - ZSTD_REP_MOVE); (void)mIndex;
+        U32 const mIndex = curr - (U32)STORED_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);
     }
@@ -309,7 +309,7 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
         matchIndex  = hashTable[h];
         hashTable[h] = curr;   /* Update Hash Table */
 
-        while (nbCompares-- && (matchIndex > windowLow)) {
+        for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
             U32* const nextPtr = bt + 2*(matchIndex & btMask);
             size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
             const BYTE* match;
@@ -328,7 +328,7 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
                 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 = ZSTD_REP_MOVE + curr - matchIndex;
+                    bestLength = matchLength, *offsetPtr = STORE_OFFSET(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
@@ -357,6 +357,7 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
 
         *smallerPtr = *largerPtr = 0;
 
+        assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
         if (dictMode == ZSTD_dictMatchState && nbCompares) {
             bestLength = ZSTD_DUBT_findBetterDictMatch(
                     ms, ip, iend,
@@ -367,7 +368,7 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
         assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */
         ms->nextToUpdate = matchEndIdx - 8;   /* skip repetitive patterns */
         if (bestLength >= MINMATCH) {
-            U32 const mIndex = curr - ((U32)*offsetPtr - ZSTD_REP_MOVE); (void)mIndex;
+            U32 const mIndex = curr - (U32)STORED_OFFSET(*offsetPtr); (void)mIndex;
             DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
                         curr, (U32)bestLength, (U32)*offsetPtr, mIndex);
         }
@@ -390,54 +391,6 @@ ZSTD_BtFindBestMatch( ZSTD_matchState_t* ms,
     return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offsetPtr, mls, dictMode);
 }
 
-
-static size_t
-ZSTD_BtFindBestMatch_selectMLS (  ZSTD_matchState_t* ms,
-                            const BYTE* ip, const BYTE* const iLimit,
-                                  size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 4, ZSTD_noDict);
-    case 5 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 5, ZSTD_noDict);
-    case 7 :
-    case 6 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 6, ZSTD_noDict);
-    }
-}
-
-
-static size_t ZSTD_BtFindBestMatch_dictMatchState_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 4, ZSTD_dictMatchState);
-    case 5 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 5, ZSTD_dictMatchState);
-    case 7 :
-    case 6 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 6, ZSTD_dictMatchState);
-    }
-}
-
-
-static size_t ZSTD_BtFindBestMatch_extDict_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 4, ZSTD_extDict);
-    case 5 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 5, ZSTD_extDict);
-    case 7 :
-    case 6 : return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 6, ZSTD_extDict);
-    }
-}
-
 /***********************************
 * Dedicated dict search
 ***********************************/
@@ -450,7 +403,7 @@ void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_matchState_t* ms, const B
     U32* const chainTable = ms->chainTable;
     U32 const chainSize = 1 << ms->cParams.chainLog;
     U32 idx = ms->nextToUpdate;
-    U32 const minChain = chainSize < target ? target - chainSize : idx;
+    U32 const minChain = chainSize < target - idx ? target - chainSize : idx;
     U32 const bucketSize = 1 << ZSTD_LAZY_DDSS_BUCKET_LOG;
     U32 const cacheSize = bucketSize - 1;
     U32 const chainAttempts = (1 << ms->cParams.searchLog) - cacheSize;
@@ -464,7 +417,7 @@ void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_matchState_t* ms, const B
     U32 const hashLog = ms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG;
     U32* const tmpHashTable = hashTable;
     U32* const tmpChainTable = hashTable + ((size_t)1 << hashLog);
-    U32 const tmpChainSize = ((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog;
+    U32 const tmpChainSize = (U32)((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog;
     U32 const tmpMinChain = tmpChainSize < target ? target - tmpChainSize : idx;
     U32 hashIdx;
 
@@ -608,7 +561,7 @@ size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nb
         /* save best solution */
         if (currentMl > ml) {
             ml = currentMl;
-            *offsetPtr = curr - (matchIndex + ddsIndexDelta) + ZSTD_REP_MOVE;
+            *offsetPtr = STORE_OFFSET(curr - (matchIndex + ddsIndexDelta));
             if (ip+currentMl == iLimit) {
                 /* best possible, avoids read overflow on next attempt */
                 return ml;
@@ -645,7 +598,7 @@ size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nb
             /* save best solution */
             if (currentMl > ml) {
                 ml = currentMl;
-                *offsetPtr = curr - (matchIndex + ddsIndexDelta) + ZSTD_REP_MOVE;
+                *offsetPtr = STORE_OFFSET(curr - (matchIndex + ddsIndexDelta));
                 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
             }
         }
@@ -692,7 +645,7 @@ U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) {
 
 /* inlining is important to hardwire a hot branch (template emulation) */
 FORCE_INLINE_TEMPLATE
-size_t ZSTD_HcFindBestMatch_generic (
+size_t ZSTD_HcFindBestMatch(
                         ZSTD_matchState_t* ms,
                         const BYTE* const ip, const BYTE* const iLimit,
                         size_t* offsetPtr,
@@ -750,7 +703,7 @@ size_t ZSTD_HcFindBestMatch_generic (
         /* save best solution */
         if (currentMl > ml) {
             ml = currentMl;
-            *offsetPtr = curr - matchIndex + ZSTD_REP_MOVE;
+            *offsetPtr = STORE_OFFSET(curr - matchIndex);
             if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
         }
 
@@ -758,6 +711,7 @@ size_t ZSTD_HcFindBestMatch_generic (
         matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
     }
 
+    assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
     if (dictMode == ZSTD_dedicatedDictSearch) {
         ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms,
                                                   ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);
@@ -784,7 +738,8 @@ size_t ZSTD_HcFindBestMatch_generic (
             /* save best solution */
             if (currentMl > ml) {
                 ml = currentMl;
-                *offsetPtr = curr - (matchIndex + dmsIndexDelta) + ZSTD_REP_MOVE;
+                assert(curr > matchIndex + dmsIndexDelta);
+                *offsetPtr = STORE_OFFSET(curr - (matchIndex + dmsIndexDelta));
                 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
             }
 
@@ -797,310 +752,80 @@ size_t ZSTD_HcFindBestMatch_generic (
     return ml;
 }
 
-
-FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_noDict);
-    case 5 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_noDict);
-    case 7 :
-    case 6 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_noDict);
-    }
-}
-
-
-static size_t ZSTD_HcFindBestMatch_dictMatchState_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_dictMatchState);
-    case 5 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_dictMatchState);
-    case 7 :
-    case 6 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_dictMatchState);
-    }
-}
-
-
-static size_t ZSTD_HcFindBestMatch_dedicatedDictSearch_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_dedicatedDictSearch);
-    case 5 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_dedicatedDictSearch);
-    case 7 :
-    case 6 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_dedicatedDictSearch);
-    }
-}
-
-
-FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_extDict_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_extDict);
-    case 5 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_extDict);
-    case 7 :
-    case 6 : return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_extDict);
-    }
-}
-
 /* *********************************
 * (SIMD) Row-based matchfinder
 ***********************************/
 /* Constants for row-based hash */
-#define ZSTD_ROW_HASH_TAG_OFFSET 1                               /* 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_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 */
 
 #define ZSTD_ROW_HASH_CACHE_MASK (ZSTD_ROW_HASH_CACHE_SIZE - 1)
 
-typedef U32 ZSTD_VecMask;   /* Clarifies when we are interacting with a U32 representing a mask of matches */
-
-#if !defined(ZSTD_NO_INTRINSICS) && defined(__SSE2__) /* SIMD SSE version */
-
-#include <emmintrin.h>
-typedef __m128i ZSTD_Vec128;
-
-/* Returns a 128-bit container with 128-bits from src */
-static ZSTD_Vec128 ZSTD_Vec128_read(const void* const src) {
-  return _mm_loadu_si128((ZSTD_Vec128 const*)src);
-}
-
-/* Returns a ZSTD_Vec128 with the byte "val" packed 16 times */
-static ZSTD_Vec128 ZSTD_Vec128_set8(BYTE val) {
-  return _mm_set1_epi8((char)val);
-}
-
-/* Do byte-by-byte comparison result of x and y. Then collapse 128-bit resultant mask
- * into a 32-bit mask that is the MSB of each byte.
- * */
-static ZSTD_VecMask ZSTD_Vec128_cmpMask8(ZSTD_Vec128 x, ZSTD_Vec128 y) {
-  return (ZSTD_VecMask)_mm_movemask_epi8(_mm_cmpeq_epi8(x, y));
-}
-
-typedef struct {
-  __m128i fst;
-  __m128i snd;
-} ZSTD_Vec256;
-
-static ZSTD_Vec256 ZSTD_Vec256_read(const void* const ptr) {
-  ZSTD_Vec256 v;
-  v.fst = ZSTD_Vec128_read(ptr);
-  v.snd = ZSTD_Vec128_read((ZSTD_Vec128 const*)ptr + 1);
-  return v;
-}
-
-static ZSTD_Vec256 ZSTD_Vec256_set8(BYTE val) {
-  ZSTD_Vec256 v;
-  v.fst = ZSTD_Vec128_set8(val);
-  v.snd = ZSTD_Vec128_set8(val);
-  return v;
-}
-
-static ZSTD_VecMask ZSTD_Vec256_cmpMask8(ZSTD_Vec256 x, ZSTD_Vec256 y) {
-  ZSTD_VecMask fstMask;
-  ZSTD_VecMask sndMask;
-  fstMask = ZSTD_Vec128_cmpMask8(x.fst, y.fst);
-  sndMask = ZSTD_Vec128_cmpMask8(x.snd, y.snd);
-  return fstMask | (sndMask << 16);
-}
-
-#elif !defined(ZSTD_NO_INTRINSICS) && defined(__ARM_NEON) /* SIMD ARM NEON Version */
-
-#include <arm_neon.h>
-typedef uint8x16_t ZSTD_Vec128;
-
-static ZSTD_Vec128 ZSTD_Vec128_read(const void* const src) {
-  return vld1q_u8((const BYTE* const)src);
-}
-
-static ZSTD_Vec128 ZSTD_Vec128_set8(BYTE val) {
-  return vdupq_n_u8(val);
-}
-
-/* Mimics '_mm_movemask_epi8()' from SSE */
-static U32 ZSTD_vmovmaskq_u8(ZSTD_Vec128 val) {
-    /* Shift out everything but the MSB bits in each byte */
-    uint16x8_t highBits = vreinterpretq_u16_u8(vshrq_n_u8(val, 7));
-    /* Merge the even lanes together with vsra (right shift and add) */
-    uint32x4_t paired16 = vreinterpretq_u32_u16(vsraq_n_u16(highBits, highBits, 7));
-    uint64x2_t paired32 = vreinterpretq_u64_u32(vsraq_n_u32(paired16, paired16, 14));
-    uint8x16_t paired64 = vreinterpretq_u8_u64(vsraq_n_u64(paired32, paired32, 28));
-    /* Extract the low 8 bits from each lane, merge */
-    return vgetq_lane_u8(paired64, 0) | ((U32)vgetq_lane_u8(paired64, 8) << 8);
-}
-
-static ZSTD_VecMask ZSTD_Vec128_cmpMask8(ZSTD_Vec128 x, ZSTD_Vec128 y) {
-  return (ZSTD_VecMask)ZSTD_vmovmaskq_u8(vceqq_u8(x, y));
-}
-
-typedef struct {
-    uint8x16_t fst;
-    uint8x16_t snd;
-} ZSTD_Vec256;
-
-static ZSTD_Vec256 ZSTD_Vec256_read(const void* const ptr) {
-  ZSTD_Vec256 v;
-  v.fst = ZSTD_Vec128_read(ptr);
-  v.snd = ZSTD_Vec128_read((ZSTD_Vec128 const*)ptr + 1);
-  return v;
-}
-
-static ZSTD_Vec256 ZSTD_Vec256_set8(BYTE val) {
-  ZSTD_Vec256 v;
-  v.fst = ZSTD_Vec128_set8(val);
-  v.snd = ZSTD_Vec128_set8(val);
-  return v;
-}
-
-static ZSTD_VecMask ZSTD_Vec256_cmpMask8(ZSTD_Vec256 x, ZSTD_Vec256 y) {
-  ZSTD_VecMask fstMask;
-  ZSTD_VecMask sndMask;
-  fstMask = ZSTD_Vec128_cmpMask8(x.fst, y.fst);
-  sndMask = ZSTD_Vec128_cmpMask8(x.snd, y.snd);
-  return fstMask | (sndMask << 16);
-}
-
-#else /* Scalar fallback version */
-
-#define VEC128_NB_SIZE_T (16 / sizeof(size_t))
-typedef struct {
-    size_t vec[VEC128_NB_SIZE_T];
-} ZSTD_Vec128;
-
-static ZSTD_Vec128 ZSTD_Vec128_read(const void* const src) {
-    ZSTD_Vec128 ret;
-    ZSTD_memcpy(ret.vec, src, VEC128_NB_SIZE_T*sizeof(size_t));
-    return ret;
-}
-
-static ZSTD_Vec128 ZSTD_Vec128_set8(BYTE val) {
-    ZSTD_Vec128 ret = { {0} };
-    int startBit = sizeof(size_t) * 8 - 8;
-    for (;startBit >= 0; startBit -= 8) {
-        unsigned j = 0;
-        for (;j < VEC128_NB_SIZE_T; ++j) {
-            ret.vec[j] |= ((size_t)val << startBit);
-        }
-    }
-    return ret;
-}
-
-/* Compare x to y, byte by byte, generating a "matches" bitfield */
-static ZSTD_VecMask ZSTD_Vec128_cmpMask8(ZSTD_Vec128 x, ZSTD_Vec128 y) {
-    ZSTD_VecMask res = 0;
-    unsigned i = 0;
-    unsigned l = 0;
-    for (; i < VEC128_NB_SIZE_T; ++i) {
-        const size_t cmp1 = x.vec[i];
-        const size_t cmp2 = y.vec[i];
-        unsigned j = 0;
-        for (; j < sizeof(size_t); ++j, ++l) {
-            if (((cmp1 >> j*8) & 0xFF) == ((cmp2 >> j*8) & 0xFF)) {
-                res |= ((U32)1 << (j+i*sizeof(size_t)));
-            }
-        }
-    }
-    return res;
-}
-
-#define VEC256_NB_SIZE_T 2*VEC128_NB_SIZE_T
-typedef struct {
-    size_t vec[VEC256_NB_SIZE_T];
-} ZSTD_Vec256;
-
-static ZSTD_Vec256 ZSTD_Vec256_read(const void* const src) {
-    ZSTD_Vec256 ret;
-    ZSTD_memcpy(ret.vec, src, VEC256_NB_SIZE_T*sizeof(size_t));
-    return ret;
-}
-
-static ZSTD_Vec256 ZSTD_Vec256_set8(BYTE val) {
-    ZSTD_Vec256 ret = { {0} };
-    int startBit = sizeof(size_t) * 8 - 8;
-    for (;startBit >= 0; startBit -= 8) {
-        unsigned j = 0;
-        for (;j < VEC256_NB_SIZE_T; ++j) {
-            ret.vec[j] |= ((size_t)val << startBit);
-        }
-    }
-    return ret;
-}
-
-/* Compare x to y, byte by byte, generating a "matches" bitfield */
-static ZSTD_VecMask ZSTD_Vec256_cmpMask8(ZSTD_Vec256 x, ZSTD_Vec256 y) {
-    ZSTD_VecMask res = 0;
-    unsigned i = 0;
-    unsigned l = 0;
-    for (; i < VEC256_NB_SIZE_T; ++i) {
-        const size_t cmp1 = x.vec[i];
-        const size_t cmp2 = y.vec[i];
-        unsigned j = 0;
-        for (; j < sizeof(size_t); ++j, ++l) {
-            if (((cmp1 >> j*8) & 0xFF) == ((cmp2 >> j*8) & 0xFF)) {
-                res |= ((U32)1 << (j+i*sizeof(size_t)));
-            }
-        }
-    }
-    return res;
-}
-
-#endif /* !defined(ZSTD_NO_INTRINSICS) && defined(__SSE2__) */
+typedef U64 ZSTD_VecMask;   /* Clarifies when we are interacting with a U64 representing a mask of matches */
 
 /* ZSTD_VecMask_next():
  * 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) {
-#   if defined(_MSC_VER)   /* Visual */
-    unsigned long r=0;
-    return _BitScanForward(&r, val) ? (U32)r : 0;
-#   elif defined(__GNUC__) && (__GNUC__ >= 3)
-    return (U32)__builtin_ctz(val);
+    assert(val != 0);
+#   if defined(_MSC_VER) && defined(_WIN64)
+        if (val != 0) {
+            unsigned long r;
+            _BitScanForward64(&r, val);
+            return (U32)(r);
+        } else {
+            /* Should not reach this code path */
+            __assume(0);
+        }
+#   elif (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://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightMultLookup */
-    static const U32 multiplyDeBruijnBitPosition[32] =
-    {
-        0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
-		31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
-    };
-	return multiplyDeBruijnBitPosition[((U32)((v & -(int)v) * 0x077CB531U)) >> 27];
+    /* 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_VecMask_rotateRight():
- * Rotates a bitfield to the right by "rotation" bits.
- * If the rotation is greater than totalBits, the returned mask is 0.
+/* 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 ZSTD_VecMask
-ZSTD_VecMask_rotateRight(ZSTD_VecMask mask, U32 const rotation, U32 const totalBits) {
-  if (rotation == 0)
-    return mask;
-  switch (totalBits) {
-    default:
-      assert(0);
-    case 16:
-      return (mask >> rotation) | (U16)(mask << (16 - rotation));
-    case 32:
-      return (mask >> rotation) | (U32)(mask << (32 - rotation));
-  }
+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));
 }
 
 /* ZSTD_row_nextIndex():
@@ -1126,20 +851,24 @@ MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) {
  */
 FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, U16 const* tagTable, U32 const relRow, U32 const rowLog) {
     PREFETCH_L1(hashTable + relRow);
-    if (rowLog == 5) {
+    if (rowLog >= 5) {
         PREFETCH_L1(hashTable + relRow + 16);
+        /* Note: prefetching more of the hash table does not appear to be beneficial for 128-entry rows */
     }
     PREFETCH_L1(tagTable + relRow);
-    assert(rowLog == 4 || rowLog == 5);
+    if (rowLog == 6) {
+        PREFETCH_L1(tagTable + relRow + 32);
+    }
+    assert(rowLog == 4 || rowLog == 5 || rowLog == 6);
     assert(ZSTD_isAligned(hashTable + relRow, 64));                 /* prefetched hash row always 64-byte aligned */
-    assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on a multiple of 32 or 64 bytes */
+    assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on correct multiple of bytes (32,64,128) */
 }
 
 /* ZSTD_row_fillHashCache():
  * 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)
 {
@@ -1179,35 +908,65 @@ FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextCachedHash(U32* cache, U32 const* hashTab
     }
 }
 
-/* ZSTD_row_update_internal():
- * Inserts the byte at ip into the appropriate position in the hash table.
- * Determines the relative row, and the position within the {16, 32} entry row to insert at.
+/* ZSTD_row_update_internalImpl():
+ * Updates the hash table with positions starting from updateStartIdx until updateEndIdx.
  */
-FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const BYTE* ip,
-                                                    U32 const mls, U32 const rowLog,
-                                                    U32 const rowMask, U32 const useCache)
+FORCE_INLINE_TEMPLATE void ZSTD_row_update_internalImpl(ZSTD_matchState_t* ms,
+                                                        U32 updateStartIdx, U32 const updateEndIdx,
+                                                        U32 const mls, U32 const rowLog,
+                                                        U32 const rowMask, U32 const useCache)
 {
     U32* const hashTable = ms->hashTable;
     U16* const tagTable = ms->tagTable;
     U32 const hashLog = ms->rowHashLog;
     const BYTE* const base = ms->window.base;
-    const U32 target = (U32)(ip - base);
-    U32 idx = ms->nextToUpdate;
 
-    DEBUGLOG(6, "ZSTD_row_update_internal(): nextToUpdate=%u, current=%u", idx, target);
-    for (; idx < target; ++idx) {
-        U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, idx, hashLog, rowLog, mls)
-                                  : (U32)ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
+    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 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 */
         U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
 
-        assert(hash == ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls));
+        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;
-        row[pos] = idx;
+        row[pos] = updateStartIdx;
     }
+}
+
+/* ZSTD_row_update_internal():
+ * Inserts the byte at ip into the appropriate position in the hash table, and updates ms->nextToUpdate.
+ * Skips sections of long matches as is necessary.
+ */
+FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const BYTE* ip,
+                                                    U32 const mls, U32 const rowLog,
+                                                    U32 const rowMask, U32 const useCache)
+{
+    U32 idx = ms->nextToUpdate;
+    const BYTE* const base = ms->window.base;
+    const U32 target = (U32)(ip - base);
+    const U32 kSkipThreshold = 384;
+    const U32 kMaxMatchStartPositionsToUpdate = 96;
+    const U32 kMaxMatchEndPositionsToUpdate = 32;
+
+    if (useCache) {
+        /* Only skip positions when using hash cache, i.e.
+         * if we are loading a dict, don't skip anything.
+         * If we decide to skip, then we only update a set number
+         * of positions at the beginning and end of the match.
+         */
+        if (UNLIKELY(target - idx > kSkipThreshold)) {
+            U32 const bound = idx + kMaxMatchStartPositionsToUpdate;
+            ZSTD_row_update_internalImpl(ms, idx, bound, mls, rowLog, rowMask, useCache);
+            idx = target - kMaxMatchEndPositionsToUpdate;
+            ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1);
+        }
+    }
+    assert(target >= idx);
+    ZSTD_row_update_internalImpl(ms, idx, target, mls, rowLog, rowMask, useCache);
     ms->nextToUpdate = target;
 }
 
@@ -1216,7 +975,7 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const
  * processing.
  */
 void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) {
-    const U32 rowLog = ms->cParams.searchLog < 5 ? 4 : 5;
+    const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6);
     const U32 rowMask = (1u << rowLog) - 1;
     const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */);
 
@@ -1224,26 +983,131 @@ void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) {
     ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* dont use cache */);
 }
 
+#if defined(ZSTD_ARCH_X86_SSE2)
+FORCE_INLINE_TEMPLATE ZSTD_VecMask
+ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U32 head)
+{
+    const __m128i comparisonMask = _mm_set1_epi8((char)tag);
+    int matches[4] = {0};
+    int i;
+    assert(nbChunks == 1 || nbChunks == 2 || nbChunks == 4);
+    for (i=0; i<nbChunks; i++) {
+        const __m128i chunk = _mm_loadu_si128((const __m128i*)(const void*)(src + 16*i));
+        const __m128i equalMask = _mm_cmpeq_epi8(chunk, comparisonMask);
+        matches[i] = _mm_movemask_epi8(equalMask);
+    }
+    if (nbChunks == 1) return ZSTD_rotateRight_U16((U16)matches[0], head);
+    if (nbChunks == 2) return ZSTD_rotateRight_U32((U32)matches[1] << 16 | (U32)matches[0], head);
+    assert(nbChunks == 4);
+    return ZSTD_rotateRight_U64((U64)matches[3] << 48 | (U64)matches[2] << 32 | (U64)matches[1] << 16 | (U64)matches[0], head);
+}
+#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.
- */
-FORCE_INLINE_TEMPLATE
-ZSTD_VecMask ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 head, const U32 rowEntries) {
-    ZSTD_VecMask matches = 0;
-    if (rowEntries == 16) {
-        ZSTD_Vec128 hashes        = ZSTD_Vec128_read(tagRow + ZSTD_ROW_HASH_TAG_OFFSET);
-        ZSTD_Vec128 expandedTags  = ZSTD_Vec128_set8(tag);
-        matches                   = ZSTD_Vec128_cmpMask8(hashes, expandedTags);
-    } else if (rowEntries == 32) {
-        ZSTD_Vec256 hashes        = ZSTD_Vec256_read(tagRow + ZSTD_ROW_HASH_TAG_OFFSET);
-        ZSTD_Vec256 expandedTags  = ZSTD_Vec256_set8(tag);
-        matches                   = ZSTD_Vec256_cmpMask8(hashes, expandedTags);
-    } else {
-        assert(0);
+ * 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 */
+FORCE_INLINE_TEMPLATE ZSTD_VecMask
+ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 head, const U32 rowEntries)
+{
+    const BYTE* const src = tagRow + ZSTD_ROW_HASH_TAG_OFFSET;
+    assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
+    assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES);
+
+#if defined(ZSTD_ARCH_X86_SSE2)
+
+    return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, head);
+
+#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);
+        }
     }
-    /* 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 */
-    return ZSTD_VecMask_rotateRight(matches, head, rowEntries);
+# endif /* ZSTD_ARCH_ARM_NEON */
+    /* SWAR */
+    {   const size_t chunkSize = sizeof(size_t);
+        const size_t shiftAmount = ((chunkSize * 8) - chunkSize);
+        const size_t xFF = ~((size_t)0);
+        const size_t x01 = xFF / 0xFF;
+        const size_t x80 = x01 << 7;
+        const size_t splatChar = tag * x01;
+        ZSTD_VecMask matches = 0;
+        int i = rowEntries - chunkSize;
+        assert((sizeof(size_t) == 4) || (sizeof(size_t) == 8));
+        if (MEM_isLittleEndian()) { /* runtime check so have two loops */
+            const size_t extractMagic = (xFF / 0x7F) >> chunkSize;
+            do {
+                size_t chunk = MEM_readST(&src[i]);
+                chunk ^= splatChar;
+                chunk = (((chunk | x80) - x01) | chunk) & x80;
+                matches <<= chunkSize;
+                matches |= (chunk * extractMagic) >> shiftAmount;
+                i -= chunkSize;
+            } while (i >= 0);
+        } else { /* big endian: reverse bits during extraction */
+            const size_t msb = xFF ^ (xFF >> 1);
+            const size_t extractMagic = (msb / 0x1FF) | msb;
+            do {
+                size_t chunk = MEM_readST(&src[i]);
+                chunk ^= splatChar;
+                chunk = (((chunk | x80) - x01) | chunk) & x80;
+                matches <<= chunkSize;
+                matches |= ((chunk >> 7) * extractMagic) >> shiftAmount;
+                i -= chunkSize;
+            } while (i >= 0);
+        }
+        matches = ~matches;
+        if (rowEntries == 16) {
+            return ZSTD_rotateRight_U16((U16)matches, head);
+        } else if (rowEntries == 32) {
+            return ZSTD_rotateRight_U32((U32)matches, head);
+        } else {
+            return ZSTD_rotateRight_U64((U64)matches, head);
+        }
+    }
+#endif
 }
 
 /* The high-level approach of the SIMD row based match finder is as follows:
@@ -1262,7 +1126,7 @@ ZSTD_VecMask ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, con
  * - Pick the longest match.
  */
 FORCE_INLINE_TEMPLATE
-size_t ZSTD_RowFindBestMatch_generic (
+size_t ZSTD_RowFindBestMatch(
                         ZSTD_matchState_t* ms,
                         const BYTE* const ip, const BYTE* const iLimit,
                         size_t* offsetPtr,
@@ -1293,11 +1157,13 @@ size_t ZSTD_RowFindBestMatch_generic (
 
     /* DMS/DDS variables that may be referenced laster */
     const ZSTD_matchState_t* const dms = ms->dictMatchState;
-    size_t ddsIdx;
-    U32 ddsExtraAttempts; /* cctx hash tables are limited in searches, but allow extra searches into DDS */
-    U32 dmsTag;
-    U32* dmsRow;
-    BYTE* dmsTagRow;
+
+    /* Initialize the following variables to satisfy static analyzer */
+    size_t ddsIdx = 0;
+    U32 ddsExtraAttempts = 0; /* cctx hash tables are limited in searches, but allow extra searches into DDS */
+    U32 dmsTag = 0;
+    U32* dmsRow = NULL;
+    BYTE* dmsTagRow = NULL;
 
     if (dictMode == ZSTD_dedicatedDictSearch) {
         const U32 ddsHashLog = dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG;
@@ -1329,7 +1195,7 @@ size_t ZSTD_RowFindBestMatch_generic (
         U32* const row = hashTable + relRow;
         BYTE* tagRow = (BYTE*)(tagTable + relRow);
         U32 const head = *tagRow & rowMask;
-        U32 matchBuffer[32 /* maximum nb entries per row */];
+        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);
@@ -1379,12 +1245,13 @@ size_t ZSTD_RowFindBestMatch_generic (
             /* Save best solution */
             if (currentMl > ml) {
                 ml = currentMl;
-                *offsetPtr = curr - matchIndex + ZSTD_REP_MOVE;
+                *offsetPtr = STORE_OFFSET(curr - matchIndex);
                 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
             }
         }
     }
 
+    assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
     if (dictMode == ZSTD_dedicatedDictSearch) {
         ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts + ddsExtraAttempts, dms,
                                                   ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);
@@ -1397,7 +1264,7 @@ size_t ZSTD_RowFindBestMatch_generic (
         const U32 dmsIndexDelta        = dictLimit - dmsSize;
 
         {   U32 const head = *dmsTagRow & rowMask;
-            U32 matchBuffer[32 /* maximum nb row entries */];
+            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);
@@ -1426,7 +1293,8 @@ size_t ZSTD_RowFindBestMatch_generic (
 
                 if (currentMl > ml) {
                     ml = currentMl;
-                    *offsetPtr = curr - (matchIndex + dmsIndexDelta) + ZSTD_REP_MOVE;
+                    assert(curr > matchIndex + dmsIndexDelta);
+                    *offsetPtr = STORE_OFFSET(curr - (matchIndex + dmsIndexDelta));
                     if (ip+currentMl == iLimit) break;
                 }
             }
@@ -1435,84 +1303,175 @@ size_t ZSTD_RowFindBestMatch_generic (
     return ml;
 }
 
-/* Inlining is important to hardwire a hot branch (template emulation) */
-FORCE_INLINE_TEMPLATE size_t ZSTD_RowFindBestMatch_selectMLS (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        const ZSTD_dictMode_e dictMode, size_t* offsetPtr, const U32 rowLog)
-{
-    switch(ms->cParams.minMatch)
-    {
-    default : /* includes case 3 */
-    case 4 : return ZSTD_RowFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, dictMode, rowLog);
-    case 5 : return ZSTD_RowFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, dictMode, rowLog);
-    case 7 :
-    case 6 : return ZSTD_RowFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, dictMode, rowLog);
-    }
-}
 
-FORCE_INLINE_TEMPLATE size_t ZSTD_RowFindBestMatch_selectRowLog (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    const U32 cappedSearchLog = MIN(ms->cParams.searchLog, 5);
-    switch(cappedSearchLog)
-    {
-    default :
-    case 4 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_noDict, offsetPtr, 4);
-    case 5 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_noDict, offsetPtr, 5);
+typedef size_t (*searchMax_f)(
+                    ZSTD_matchState_t* ms,
+                    const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
+
+/**
+ * This struct contains the functions necessary for lazy to search.
+ * Currently, that is only searchMax. However, it is still valuable to have the
+ * VTable because this makes it easier to add more functions to the VTable later.
+ *
+ * TODO: The start of the search function involves loading and calculating a
+ * bunch of constants from the ZSTD_matchState_t. These computations could be
+ * done in an initialization function, and saved somewhere in the match state.
+ * Then we could pass a pointer to the saved state instead of the match state,
+ * and avoid duplicate computations.
+ *
+ * TODO: Move the match re-winding into searchMax. This improves compression
+ * ratio, and unlocks further simplifications with the next TODO.
+ *
+ * TODO: Try moving the repcode search into searchMax. After the re-winding
+ * and repcode search are in searchMax, there is no more logic in the match
+ * finder loop that requires knowledge about the dictMode. So we should be
+ * able to avoid force inlining it, and we can join the extDict loop with
+ * the single segment loop. It should go in searchMax instead of its own
+ * function to avoid having multiple virtual function calls per search.
+ */
+typedef struct {
+    searchMax_f searchMax;
+} ZSTD_LazyVTable;
+
+#define GEN_ZSTD_BT_VTABLE(dictMode, mls)                                             \
+    static size_t ZSTD_BtFindBestMatch_##dictMode##_##mls(                            \
+            ZSTD_matchState_t* ms,                                                    \
+            const BYTE* ip, const BYTE* const iLimit,                                 \
+            size_t* offsetPtr)                                                        \
+    {                                                                                 \
+        assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls);                          \
+        return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode); \
+    }                                                                                 \
+    static const ZSTD_LazyVTable ZSTD_BtVTable_##dictMode##_##mls = {                 \
+        ZSTD_BtFindBestMatch_##dictMode##_##mls                                       \
+    };
+
+#define GEN_ZSTD_HC_VTABLE(dictMode, mls)                                             \
+    static size_t ZSTD_HcFindBestMatch_##dictMode##_##mls(                            \
+            ZSTD_matchState_t* ms,                                                    \
+            const BYTE* ip, const BYTE* const iLimit,                                 \
+            size_t* offsetPtr)                                                        \
+    {                                                                                 \
+        assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls);                          \
+        return ZSTD_HcFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode); \
+    }                                                                                 \
+    static const ZSTD_LazyVTable ZSTD_HcVTable_##dictMode##_##mls = {                 \
+        ZSTD_HcFindBestMatch_##dictMode##_##mls                                       \
+    };
+
+#define GEN_ZSTD_ROW_VTABLE(dictMode, mls, rowLog)                                             \
+    static size_t ZSTD_RowFindBestMatch_##dictMode##_##mls##_##rowLog(                         \
+            ZSTD_matchState_t* ms,                                                             \
+            const BYTE* ip, const BYTE* const iLimit,                                          \
+            size_t* offsetPtr)                                                                 \
+    {                                                                                          \
+        assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls);                                   \
+        assert(MAX(4, MIN(6, ms->cParams.searchLog)) == rowLog);                               \
+        return ZSTD_RowFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode, rowLog); \
+    }                                                                                          \
+    static const ZSTD_LazyVTable ZSTD_RowVTable_##dictMode##_##mls##_##rowLog = {              \
+        ZSTD_RowFindBestMatch_##dictMode##_##mls##_##rowLog                                    \
+    };
+
+#define ZSTD_FOR_EACH_ROWLOG(X, dictMode, mls) \
+    X(dictMode, mls, 4)                        \
+    X(dictMode, mls, 5)                        \
+    X(dictMode, mls, 6)
+
+#define ZSTD_FOR_EACH_MLS_ROWLOG(X, dictMode) \
+    ZSTD_FOR_EACH_ROWLOG(X, dictMode, 4)      \
+    ZSTD_FOR_EACH_ROWLOG(X, dictMode, 5)      \
+    ZSTD_FOR_EACH_ROWLOG(X, dictMode, 6)
+
+#define ZSTD_FOR_EACH_MLS(X, dictMode) \
+    X(dictMode, 4)                     \
+    X(dictMode, 5)                     \
+    X(dictMode, 6)
+
+#define ZSTD_FOR_EACH_DICT_MODE(X, ...) \
+    X(__VA_ARGS__, noDict)              \
+    X(__VA_ARGS__, extDict)             \
+    X(__VA_ARGS__, dictMatchState)      \
+    X(__VA_ARGS__, dedicatedDictSearch)
+
+/* Generate Row VTables for each combination of (dictMode, mls, rowLog) */
+ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS_ROWLOG, GEN_ZSTD_ROW_VTABLE)
+/* Generate Binary Tree VTables for each combination of (dictMode, mls) */
+ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_BT_VTABLE)
+/* Generate Hash Chain VTables for each combination of (dictMode, mls) */
+ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_HC_VTABLE)
+
+#define GEN_ZSTD_BT_VTABLE_ARRAY(dictMode) \
+    {                                      \
+        &ZSTD_BtVTable_##dictMode##_4,     \
+        &ZSTD_BtVTable_##dictMode##_5,     \
+        &ZSTD_BtVTable_##dictMode##_6      \
     }
-}
 
-FORCE_INLINE_TEMPLATE size_t ZSTD_RowFindBestMatch_dictMatchState_selectRowLog(
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    const U32 cappedSearchLog = MIN(ms->cParams.searchLog, 5);
-    switch(cappedSearchLog)
-    {
-    default :
-    case 4 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_dictMatchState, offsetPtr, 4);
-    case 5 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_dictMatchState, offsetPtr, 5);
+#define GEN_ZSTD_HC_VTABLE_ARRAY(dictMode) \
+    {                                      \
+        &ZSTD_HcVTable_##dictMode##_4,     \
+        &ZSTD_HcVTable_##dictMode##_5,     \
+        &ZSTD_HcVTable_##dictMode##_6      \
     }
-}
 
-FORCE_INLINE_TEMPLATE size_t ZSTD_RowFindBestMatch_dedicatedDictSearch_selectRowLog(
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    const U32 cappedSearchLog = MIN(ms->cParams.searchLog, 5);
-    switch(cappedSearchLog)
-    {
-    default :
-    case 4 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_dedicatedDictSearch, offsetPtr, 4);
-    case 5 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_dedicatedDictSearch, offsetPtr, 5);
+#define GEN_ZSTD_ROW_VTABLE_ARRAY_(dictMode, mls) \
+    {                                             \
+        &ZSTD_RowVTable_##dictMode##_##mls##_4,   \
+        &ZSTD_RowVTable_##dictMode##_##mls##_5,   \
+        &ZSTD_RowVTable_##dictMode##_##mls##_6    \
     }
-}
 
-FORCE_INLINE_TEMPLATE size_t ZSTD_RowFindBestMatch_extDict_selectRowLog (
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* const iLimit,
-                        size_t* offsetPtr)
-{
-    const U32 cappedSearchLog = MIN(ms->cParams.searchLog, 5);
-    switch(cappedSearchLog)
-    {
-    default :
-    case 4 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_extDict, offsetPtr, 4);
-    case 5 : return ZSTD_RowFindBestMatch_selectMLS(ms, ip, iLimit, ZSTD_extDict, offsetPtr, 5);
+#define GEN_ZSTD_ROW_VTABLE_ARRAY(dictMode)      \
+    {                                            \
+        GEN_ZSTD_ROW_VTABLE_ARRAY_(dictMode, 4), \
+        GEN_ZSTD_ROW_VTABLE_ARRAY_(dictMode, 5), \
+        GEN_ZSTD_ROW_VTABLE_ARRAY_(dictMode, 6)  \
     }
-}
 
+#define GEN_ZSTD_VTABLE_ARRAY(X) \
+    {                            \
+        X(noDict),               \
+        X(extDict),              \
+        X(dictMatchState),       \
+        X(dedicatedDictSearch)   \
+    }
 
 /* *******************************
 *  Common parser - lazy strategy
 *********************************/
 typedef enum { search_hashChain=0, search_binaryTree=1, search_rowHash=2 } searchMethod_e;
 
+/**
+ * This table is indexed first by the four ZSTD_dictMode_e values, and then
+ * by the two searchMethod_e values. NULLs are placed for configurations
+ * that should never occur (extDict modes go to the other implementation
+ * below and there is no DDSS for binary tree search yet).
+ */
+
+static ZSTD_LazyVTable const*
+ZSTD_selectLazyVTable(ZSTD_matchState_t const* ms, searchMethod_e searchMethod, ZSTD_dictMode_e dictMode)
+{
+    /* Fill the Hc/Bt VTable arrays with the right functions for the (dictMode, mls) combination. */
+    ZSTD_LazyVTable const* const hcVTables[4][3] = GEN_ZSTD_VTABLE_ARRAY(GEN_ZSTD_HC_VTABLE_ARRAY);
+    ZSTD_LazyVTable const* const btVTables[4][3] = GEN_ZSTD_VTABLE_ARRAY(GEN_ZSTD_BT_VTABLE_ARRAY);
+    /* Fill the Row VTable array with the right functions for the (dictMode, mls, rowLog) combination. */
+    ZSTD_LazyVTable const* const rowVTables[4][3][3] = GEN_ZSTD_VTABLE_ARRAY(GEN_ZSTD_ROW_VTABLE_ARRAY);
+
+    U32 const mls = MAX(4, MIN(6, ms->cParams.minMatch));
+    U32 const rowLog = MAX(4, MIN(6, ms->cParams.searchLog));
+    switch (searchMethod) {
+        case search_hashChain:
+            return hcVTables[dictMode][mls - 4];
+        case search_binaryTree:
+            return btVTables[dictMode][mls - 4];
+        case search_rowHash:
+            return rowVTables[dictMode][mls - 4][rowLog - 4];
+        default:
+            return NULL;
+    }
+}
+
 FORCE_INLINE_TEMPLATE size_t
 ZSTD_compressBlock_lazy_generic(
                         ZSTD_matchState_t* ms, seqStore_t* seqStore,
@@ -1525,46 +1484,12 @@ ZSTD_compressBlock_lazy_generic(
     const BYTE* ip = istart;
     const BYTE* anchor = istart;
     const BYTE* const iend = istart + srcSize;
-    const BYTE* const ilimit = searchMethod == search_rowHash ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8;
+    const BYTE* const ilimit = (searchMethod == search_rowHash) ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8;
     const BYTE* const base = ms->window.base;
     const U32 prefixLowestIndex = ms->window.dictLimit;
     const BYTE* const prefixLowest = base + prefixLowestIndex;
-    const U32 rowLog = ms->cParams.searchLog < 5 ? 4 : 5;
 
-    typedef size_t (*searchMax_f)(
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
-
-    /**
-     * This table is indexed first by the four ZSTD_dictMode_e values, and then
-     * by the two searchMethod_e values. NULLs are placed for configurations
-     * that should never occur (extDict modes go to the other implementation
-     * below and there is no DDSS for binary tree search yet).
-     */
-    const searchMax_f searchFuncs[4][3] = {
-        {
-            ZSTD_HcFindBestMatch_selectMLS,
-            ZSTD_BtFindBestMatch_selectMLS,
-            ZSTD_RowFindBestMatch_selectRowLog
-        },
-        {
-            NULL,
-            NULL,
-            NULL
-        },
-        {
-            ZSTD_HcFindBestMatch_dictMatchState_selectMLS,
-            ZSTD_BtFindBestMatch_dictMatchState_selectMLS,
-            ZSTD_RowFindBestMatch_dictMatchState_selectRowLog
-        },
-        {
-            ZSTD_HcFindBestMatch_dedicatedDictSearch_selectMLS,
-            NULL,
-            ZSTD_RowFindBestMatch_dedicatedDictSearch_selectRowLog
-        }
-    };
-
-    searchMax_f const searchMax = searchFuncs[dictMode][(int)searchMethod];
+    searchMax_f const searchMax = ZSTD_selectLazyVTable(ms, searchMethod, dictMode)->searchMax;
     U32 offset_1 = rep[0], offset_2 = rep[1], savedOffset=0;
 
     const int isDMS = dictMode == ZSTD_dictMatchState;
@@ -1599,6 +1524,7 @@ ZSTD_compressBlock_lazy_generic(
     }
 
     if (searchMethod == search_rowHash) {
+        const U32 rowLog = MAX(4, MIN(6, ms->cParams.searchLog));
         ZSTD_row_fillHashCache(ms, base, rowLog,
                             MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */),
                             ms->nextToUpdate, ilimit);
@@ -1613,8 +1539,9 @@ ZSTD_compressBlock_lazy_generic(
 #endif
     while (ip < ilimit) {
         size_t matchLength=0;
-        size_t offset=0;
+        size_t offcode=STORE_REPCODE_1;
         const BYTE* start=ip+1;
+        DEBUGLOG(7, "search baseline (depth 0)");
 
         /* check repCode */
         if (isDxS) {
@@ -1640,7 +1567,7 @@ ZSTD_compressBlock_lazy_generic(
         {   size_t offsetFound = 999999999;
             size_t const ml2 = searchMax(ms, ip, iend, &offsetFound);
             if (ml2 > matchLength)
-                matchLength = ml2, start = ip, offset=offsetFound;
+                matchLength = ml2, start = ip, offcode=offsetFound;
         }
 
         if (matchLength < 4) {
@@ -1651,14 +1578,15 @@ ZSTD_compressBlock_lazy_generic(
         /* let's try to find a better solution */
         if (depth>=1)
         while (ip<ilimit) {
+            DEBUGLOG(7, "search depth 1");
             ip ++;
             if ( (dictMode == ZSTD_noDict)
-              && (offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
+              && (offcode) && ((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)offset+1) + 1);
+                int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
                 if ((mlRep >= 4) && (gain2 > gain1))
-                    matchLength = mlRep, offset = 0, start = ip;
+                    matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
             }
             if (isDxS) {
                 const U32 repIndex = (U32)(ip - base) - offset_1;
@@ -1670,30 +1598,31 @@ 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)offset+1) + 1);
+                    int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
                     if ((mlRep >= 4) && (gain2 > gain1))
-                        matchLength = mlRep, offset = 0, start = ip;
+                        matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
                 }
             }
             {   size_t offset2=999999999;
                 size_t const ml2 = searchMax(ms, ip, iend, &offset2);
-                int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
-                int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
+                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);
                 if ((ml2 >= 4) && (gain2 > gain1)) {
-                    matchLength = ml2, offset = offset2, start = ip;
+                    matchLength = ml2, offcode = offset2, start = ip;
                     continue;   /* search a better one */
             }   }
 
             /* let's find an even better one */
             if ((depth==2) && (ip<ilimit)) {
+                DEBUGLOG(7, "search depth 2");
                 ip ++;
                 if ( (dictMode == ZSTD_noDict)
-                  && (offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
+                  && (offcode) && ((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)offset+1) + 1);
+                    int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
                     if ((mlRep >= 4) && (gain2 > gain1))
-                        matchLength = mlRep, offset = 0, start = ip;
+                        matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
                 }
                 if (isDxS) {
                     const U32 repIndex = (U32)(ip - base) - offset_1;
@@ -1705,46 +1634,45 @@ 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)offset+1) + 1);
+                        int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
                         if ((mlRep >= 4) && (gain2 > gain1))
-                            matchLength = mlRep, offset = 0, start = ip;
+                            matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip;
                     }
                 }
                 {   size_t offset2=999999999;
                     size_t const ml2 = searchMax(ms, ip, iend, &offset2);
-                    int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
-                    int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
+                    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);
                     if ((ml2 >= 4) && (gain2 > gain1)) {
-                        matchLength = ml2, offset = offset2, start = ip;
+                        matchLength = ml2, offcode = offset2, start = ip;
                         continue;
             }   }   }
             break;  /* nothing found : store previous solution */
         }
 
         /* NOTE:
-         * start[-offset+ZSTD_REP_MOVE-1] is undefined behavior.
-         * (-offset+ZSTD_REP_MOVE-1) is unsigned, and is added to start, which
-         * overflows the pointer, which is undefined behavior.
+         * Pay attention that `start[-value]` can lead to strange undefined behavior
+         * notably if `value` is unsigned, resulting in a large positive `-value`.
          */
         /* catch up */
-        if (offset) {
+        if (STORED_IS_OFFSET(offcode)) {
             if (dictMode == ZSTD_noDict) {
-                while ( ((start > anchor) & (start - (offset-ZSTD_REP_MOVE) > prefixLowest))
-                     && (start[-1] == (start-(offset-ZSTD_REP_MOVE))[-1]) )  /* only search for offset within prefix */
+                while ( ((start > anchor) & (start - STORED_OFFSET(offcode) > prefixLowest))
+                     && (start[-1] == (start-STORED_OFFSET(offcode))[-1]) )  /* only search for offset within prefix */
                     { start--; matchLength++; }
             }
             if (isDxS) {
-                U32 const matchIndex = (U32)((start-base) - (offset - ZSTD_REP_MOVE));
+                U32 const matchIndex = (U32)((size_t)(start-base) - STORED_OFFSET(offcode));
                 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)(offset - ZSTD_REP_MOVE);
+            offset_2 = offset_1; offset_1 = (U32)STORED_OFFSET(offcode);
         }
         /* store sequence */
 _storeSequence:
-        {   size_t const litLength = start - anchor;
-            ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offset, matchLength-MINMATCH);
+        {   size_t const litLength = (size_t)(start - anchor);
+            ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offcode, matchLength);
             anchor = ip = start + matchLength;
         }
 
@@ -1760,8 +1688,8 @@ _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;
-                    offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset;   /* swap offset_2 <=> offset_1 */
-                    ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength-MINMATCH);
+                    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);
                     ip += matchLength;
                     anchor = ip;
                     continue;
@@ -1775,8 +1703,8 @@ _storeSequence:
                  && (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) {
                 /* store sequence */
                 matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
-                offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset; /* swap repcodes */
-                ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength-MINMATCH);
+                offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap repcodes */
+                ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength);
                 ip += matchLength;
                 anchor = ip;
                 continue;   /* faster when present ... (?) */
@@ -1955,15 +1883,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
     const U32 windowLog = ms->cParams.windowLog;
     const U32 rowLog = ms->cParams.searchLog < 5 ? 4 : 5;
 
-    typedef size_t (*searchMax_f)(
-                        ZSTD_matchState_t* ms,
-                        const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
-    const searchMax_f searchFuncs[3] = {
-        ZSTD_HcFindBestMatch_extDict_selectMLS,
-        ZSTD_BtFindBestMatch_extDict_selectMLS,
-        ZSTD_RowFindBestMatch_extDict_selectRowLog
-    };
-    searchMax_f searchMax = searchFuncs[(int)searchMethod];
+    searchMax_f const searchMax = ZSTD_selectLazyVTable(ms, searchMethod, ZSTD_extDict)->searchMax;
     U32 offset_1 = rep[0], offset_2 = rep[1];
 
     DEBUGLOG(5, "ZSTD_compressBlock_lazy_extDict_generic (searchFunc=%u)", (U32)searchMethod);
@@ -1985,7 +1905,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
 #endif
     while (ip < ilimit) {
         size_t matchLength=0;
-        size_t offset=0;
+        size_t offcode=STORE_REPCODE_1;
         const BYTE* start=ip+1;
         U32 curr = (U32)(ip-base);
 
@@ -1995,7 +1915,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
             const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
             const BYTE* const repMatch = repBase + repIndex;
             if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow */
-               & (offset_1 < curr+1 - windowLow) ) /* note: we are searching at curr+1 */
+               & (offset_1 <= curr+1 - windowLow) ) /* note: we are searching at curr+1 */
             if (MEM_read32(ip+1) == MEM_read32(repMatch)) {
                 /* repcode detected we should take it */
                 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
@@ -2007,10 +1927,10 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
         {   size_t offsetFound = 999999999;
             size_t const ml2 = searchMax(ms, ip, iend, &offsetFound);
             if (ml2 > matchLength)
-                matchLength = ml2, start = ip, offset=offsetFound;
+                matchLength = ml2, start = ip, offcode=offsetFound;
         }
 
-         if (matchLength < 4) {
+        if (matchLength < 4) {
             ip += ((ip-anchor) >> kSearchStrength) + 1;   /* jump faster over incompressible sections */
             continue;
         }
@@ -2021,30 +1941,30 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
             ip ++;
             curr++;
             /* check repCode */
-            if (offset) {
+            if (offcode) {
                 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog);
                 const U32 repIndex = (U32)(curr - offset_1);
                 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
                 const BYTE* const repMatch = repBase + repIndex;
                 if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments  */
-                   & (offset_1 < curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
+                   & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
                 if (MEM_read32(ip) == MEM_read32(repMatch)) {
                     /* repcode detected */
                     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)offset+1) + 1);
+                    int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
                     if ((repLength >= 4) && (gain2 > gain1))
-                        matchLength = repLength, offset = 0, start = ip;
+                        matchLength = repLength, offcode = STORE_REPCODE_1, start = ip;
             }   }
 
             /* search match, depth 1 */
             {   size_t offset2=999999999;
                 size_t const ml2 = searchMax(ms, ip, iend, &offset2);
-                int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
-                int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
+                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);
                 if ((ml2 >= 4) && (gain2 > gain1)) {
-                    matchLength = ml2, offset = offset2, start = ip;
+                    matchLength = ml2, offcode = offset2, start = ip;
                     continue;   /* search a better one */
             }   }
 
@@ -2053,48 +1973,48 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
                 ip ++;
                 curr++;
                 /* check repCode */
-                if (offset) {
+                if (offcode) {
                     const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog);
                     const U32 repIndex = (U32)(curr - offset_1);
                     const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
                     const BYTE* const repMatch = repBase + repIndex;
                     if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments  */
-                       & (offset_1 < curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
+                       & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
                     if (MEM_read32(ip) == MEM_read32(repMatch)) {
                         /* repcode detected */
                         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)offset+1) + 1);
+                        int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1);
                         if ((repLength >= 4) && (gain2 > gain1))
-                            matchLength = repLength, offset = 0, start = ip;
+                            matchLength = repLength, offcode = STORE_REPCODE_1, start = ip;
                 }   }
 
                 /* search match, depth 2 */
                 {   size_t offset2=999999999;
                     size_t const ml2 = searchMax(ms, ip, iend, &offset2);
-                    int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
-                    int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
+                    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);
                     if ((ml2 >= 4) && (gain2 > gain1)) {
-                        matchLength = ml2, offset = offset2, start = ip;
+                        matchLength = ml2, offcode = offset2, start = ip;
                         continue;
             }   }   }
             break;  /* nothing found : store previous solution */
         }
 
         /* catch up */
-        if (offset) {
-            U32 const matchIndex = (U32)((start-base) - (offset - ZSTD_REP_MOVE));
+        if (STORED_IS_OFFSET(offcode)) {
+            U32 const matchIndex = (U32)((size_t)(start-base) - STORED_OFFSET(offcode));
             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)(offset - ZSTD_REP_MOVE);
+            offset_2 = offset_1; offset_1 = (U32)STORED_OFFSET(offcode);
         }
 
         /* store sequence */
 _storeSequence:
-        {   size_t const litLength = start - anchor;
-            ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offset, matchLength-MINMATCH);
+        {   size_t const litLength = (size_t)(start - anchor);
+            ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offcode, matchLength);
             anchor = ip = start + matchLength;
         }
 
@@ -2106,13 +2026,13 @@ _storeSequence:
             const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
             const BYTE* const repMatch = repBase + repIndex;
             if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments  */
-               & (offset_2 < repCurrent - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
+               & (offset_2 <= repCurrent - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
             if (MEM_read32(ip) == MEM_read32(repMatch)) {
                 /* 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;
-                offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset;   /* swap offset history */
-                ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength-MINMATCH);
+                offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode;   /* swap offset history */
+                ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength);
                 ip += matchLength;
                 anchor = ip;
                 continue;   /* faster when present ... (?) */