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Merge pull request #1804 from terrelln/wild-and-fast

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Optimize (de)compression and fix wildcopy overread
This commit is contained in:
Nick Terrell
2019-09-21 17:04:36 -07:00
committed by GitHub
parent c047fcf7bf 5cb7615f1f
commit 7451c6578c
10 changed files with 246 additions and 235 deletions
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lib/common/compiler.h
+7
View File
@@ -61,6 +61,13 @@
# define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR
#endif
/* UNUSED_ATTR tells the compiler it is okay if the function is unused. */
#if defined(__GNUC__)
# define UNUSED_ATTR __attribute__((unused))
#else
# define UNUSED_ATTR
#endif
/* force no inlining */
#ifdef _MSC_VER
# define FORCE_NOINLINE static __declspec(noinline)
lib/common/zstd_internal.h
+37 -62
View File
@@ -197,8 +197,8 @@ static void ZSTD_copy8(void* dst, const void* src) { memcpy(dst, src, 8); }
static void ZSTD_copy16(void* dst, const void* src) { memcpy(dst, src, 16); }
#define COPY16(d,s) { ZSTD_copy16(d,s); d+=16; s+=16; }
#define WILDCOPY_OVERLENGTH 8
#define VECLEN 16
#define WILDCOPY_OVERLENGTH 32
#define WILDCOPY_VECLEN 16
typedef enum {
ZSTD_no_overlap,
@@ -207,83 +207,58 @@ typedef enum {
} ZSTD_overlap_e;
/*! ZSTD_wildcopy() :
* custom version of memcpy(), can overwrite up to WILDCOPY_OVERLENGTH bytes (if length==0) */
* Custom version of memcpy(), can over read/write up to WILDCOPY_OVERLENGTH bytes (if length==0)
* @param ovtype controls the overlap detection
* - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart.
* - ZSTD_overlap_src_before_dst: The src and dst may overlap, but they MUST be at least 8 bytes apart.
* The src buffer must be before the dst buffer.
*/
MEM_STATIC FORCE_INLINE_ATTR DONT_VECTORIZE
void ZSTD_wildcopy(void* dst, const void* src, BYTE* oend_g, ptrdiff_t length, ZSTD_overlap_e ovtype)
void ZSTD_wildcopy(void* dst, const void* src, ptrdiff_t length, ZSTD_overlap_e const ovtype)
{
ptrdiff_t diff = (BYTE*)dst - (const BYTE*)src;
const BYTE* ip = (const BYTE*)src;
BYTE* op = (BYTE*)dst;
BYTE* const oend = op + length;
assert(diff >= 8 || (ovtype == ZSTD_no_overlap && diff < -8));
assert(diff >= 8 || (ovtype == ZSTD_no_overlap && diff <= -WILDCOPY_VECLEN));
if (length < VECLEN || (ovtype == ZSTD_overlap_src_before_dst && diff < VECLEN)) {
do
COPY8(op, ip)
while (op < oend);
}
else {
if (oend < oend_g-16) {
/* common case */
if (ovtype == ZSTD_overlap_src_before_dst && diff < WILDCOPY_VECLEN) {
/* Handle short offset copies. */
do {
COPY16(op, ip);
COPY8(op, ip)
} while (op < oend);
} else {
assert(diff >= WILDCOPY_VECLEN || diff <= -WILDCOPY_VECLEN);
/* Separate out the first two COPY16() calls because the copy length is
* almost certain to be short, so the branches have different
* probabilities.
* On gcc-9 unrolling once is +1.6%, twice is +2%, thrice is +1.8%.
* On clang-8 unrolling once is +1.4%, twice is +3.3%, thrice is +3%.
*/
COPY16(op, ip);
COPY16(op, ip);
if (op >= oend) return;
do {
COPY16(op, ip);
COPY16(op, ip);
}
while (op < oend);
}
else {
do {
COPY8(op, ip);
}
while (op < oend);
}
}
}
/*! ZSTD_wildcopy_16min() :
* same semantics as ZSTD_wildcopy() except guaranteed to be able to copy 16 bytes at the start */
MEM_STATIC FORCE_INLINE_ATTR DONT_VECTORIZE
void ZSTD_wildcopy_16min(void* dst, const void* src, BYTE* oend_g, ptrdiff_t length, ZSTD_overlap_e ovtype)
{
ptrdiff_t diff = (BYTE*)dst - (const BYTE*)src;
const BYTE* ip = (const BYTE*)src;
BYTE* op = (BYTE*)dst;
BYTE* const oend = op + length;
assert(length >= 8);
assert(diff >= 8 || (ovtype == ZSTD_no_overlap && diff < -8));
if (ovtype == ZSTD_overlap_src_before_dst && diff < VECLEN) {
do {
COPY8(op, ip);
}
while (op < oend);
}
else {
if (oend < oend_g-16) {
/* common case */
do {
COPY16(op, ip);
}
while (op < oend);
}
else {
do {
COPY8(op, ip);
}
while (op < oend);
}
}
}
MEM_STATIC void ZSTD_wildcopy_e(void* dst, const void* src, void* dstEnd) /* should be faster for decoding, but strangely, not verified on all platform */
/*! ZSTD_wildcopy8() :
* The same as ZSTD_wildcopy(), but it can only overwrite 8 bytes, and works for
* overlapping buffers that are at least 8 bytes apart.
*/
MEM_STATIC void ZSTD_wildcopy8(void* dst, const void* src, ptrdiff_t length)
{
const BYTE* ip = (const BYTE*)src;
BYTE* op = (BYTE*)dst;
BYTE* const oend = (BYTE*)dstEnd;
do
COPY8(op, ip)
while (op < oend);
BYTE* const oend = (BYTE*)op + length;
do {
COPY8(op, ip);
} while (op < oend);
}
lib/compress/zstd_compress_internal.h
+33 -2
View File
@@ -340,13 +340,32 @@ MEM_STATIC size_t ZSTD_minGain(size_t srcSize, ZSTD_strategy strat)
return (srcSize >> minlog) + 2;
}
/*! ZSTD_safecopyLiterals() :
* memcpy() function that won't read beyond more than WILDCOPY_OVERLENGTH bytes past ilimit_w.
* Only called when the sequence ends past ilimit_w, so it only needs to be optimized for single
* large copies.
*/
static void ZSTD_safecopyLiterals(BYTE* op, BYTE const* ip, BYTE const* const iend, BYTE const* ilimit_w) {
assert(iend > ilimit_w);
if (ip <= ilimit_w) {
ZSTD_wildcopy(op, ip, ilimit_w - ip, ZSTD_no_overlap);
op += ilimit_w - ip;
ip = ilimit_w;
}
while (ip < iend) *op++ = *ip++;
}
/*! ZSTD_storeSeq() :
* Store a sequence (litlen, litPtr, offCode and mlBase) into seqStore_t.
* `offCode` : distance to match + ZSTD_REP_MOVE (values <= ZSTD_REP_MOVE are repCodes).
* `mlBase` : matchLength - MINMATCH
* Allowed to overread literals up to litLimit.
*/
MEM_STATIC void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const void* literals, U32 offCode, size_t mlBase)
HINT_INLINE UNUSED_ATTR
void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const BYTE* literals, const BYTE* litLimit, U32 offCode, size_t mlBase)
{
BYTE const* const litLimit_w = litLimit - WILDCOPY_OVERLENGTH;
BYTE const* const litEnd = literals + litLength;
#if defined(DEBUGLEVEL) && (DEBUGLEVEL >= 6)
static const BYTE* g_start = NULL;
if (g_start==NULL) g_start = (const BYTE*)literals; /* note : index only works for compression within a single segment */
@@ -359,7 +378,19 @@ MEM_STATIC void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const v
/* copy Literals */
assert(seqStorePtr->maxNbLit <= 128 KB);
assert(seqStorePtr->lit + litLength <= seqStorePtr->litStart + seqStorePtr->maxNbLit);
ZSTD_wildcopy(seqStorePtr->lit, literals, seqStorePtr->lit + litLength + 8, (ptrdiff_t)litLength, ZSTD_no_overlap);
assert(literals + litLength <= litLimit);
if (litEnd <= litLimit_w) {
/* Common case we can use wildcopy.
* First copy 16 bytes, because literals are likely short.
*/
assert(WILDCOPY_OVERLENGTH >= 16);
ZSTD_copy16(seqStorePtr->lit, literals);
if (litLength > 16) {
ZSTD_wildcopy(seqStorePtr->lit+16, literals+16, (ptrdiff_t)litLength-16, ZSTD_no_overlap);
}
} else {
ZSTD_safecopyLiterals(seqStorePtr->lit, literals, litEnd, litLimit_w);
}
seqStorePtr->lit += litLength;
/* literal Length */
lib/compress/zstd_double_fast.c
+9 -9
View File
@@ -148,7 +148,7 @@ size_t ZSTD_compressBlock_doubleFast_generic(
const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;
ip++;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, mLength-MINMATCH);
goto _match_stored;
}
@@ -157,7 +157,7 @@ size_t ZSTD_compressBlock_doubleFast_generic(
&& ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {
mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
ip++;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, mLength-MINMATCH);
goto _match_stored;
}
@@ -247,7 +247,7 @@ _match_found:
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
_match_stored:
/* match found */
@@ -278,7 +278,7 @@ _match_stored:
const BYTE* const repEnd2 = repIndex2 < prefixLowestIndex ? dictEnd : iend;
size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixLowest) + 4;
U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, repLength2-MINMATCH);
hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = current2;
hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = current2;
ip += repLength2;
@@ -297,7 +297,7 @@ _match_stored:
U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; /* swap offset_2 <=> offset_1 */
hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = (U32)(ip-base);
hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = (U32)(ip-base);
ZSTD_storeSeq(seqStore, 0, anchor, 0, rLength-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, rLength-MINMATCH);
ip += rLength;
anchor = ip;
continue; /* faster when present ... (?) */
@@ -411,7 +411,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic(
const BYTE* repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
ip++;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, mLength-MINMATCH);
} else {
if ((matchLongIndex > dictStartIndex) && (MEM_read64(matchLong) == MEM_read64(ip))) {
const BYTE* const matchEnd = matchLongIndex < prefixStartIndex ? dictEnd : iend;
@@ -422,7 +422,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic(
while (((ip>anchor) & (matchLong>lowMatchPtr)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
} else if ((matchIndex > dictStartIndex) && (MEM_read32(match) == MEM_read32(ip))) {
size_t const h3 = ZSTD_hashPtr(ip+1, hBitsL, 8);
@@ -447,7 +447,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic(
}
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
} else {
ip += ((ip-anchor) >> kSearchStrength) + 1;
@@ -479,7 +479,7 @@ static size_t ZSTD_compressBlock_doubleFast_extDict_generic(
const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
U32 const tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, repLength2-MINMATCH);
hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = current2;
hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = current2;
ip += repLength2;
lib/compress/zstd_fast.c
+9 -9
View File
@@ -136,7 +136,7 @@ _offset: /* Requires: ip0, match0 */
_match: /* Requires: ip0, match0, offcode */
/* Count the forward length */
mLength += ZSTD_count(ip0+mLength+4, match0+mLength+4, iend) + 4;
ZSTD_storeSeq(seqStore, (size_t)(ip0-anchor), anchor, offcode, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip0-anchor), anchor, iend, offcode, mLength-MINMATCH);
/* match found */
ip0 += mLength;
anchor = ip0;
@@ -156,7 +156,7 @@ _match: /* Requires: ip0, match0, offcode */
hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base);
ip0 += rLength;
ip1 = ip0 + 1;
ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, 0 /*offCode*/, rLength-MINMATCH);
ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, 0 /*offCode*/, rLength-MINMATCH);
anchor = ip0;
continue; /* faster when present (confirmed on gcc-8) ... (?) */
}
@@ -261,7 +261,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(
const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
ip++;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, mLength-MINMATCH);
} else if ( (matchIndex <= prefixStartIndex) ) {
size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls);
U32 const dictMatchIndex = dictHashTable[dictHash];
@@ -281,7 +281,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(
} /* catch up */
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
}
} else if (MEM_read32(match) != MEM_read32(ip)) {
/* it's not a match, and we're not going to check the dictionary */
@@ -296,7 +296,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(
&& (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
}
/* match found */
@@ -321,7 +321,7 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(
const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, repLength2-MINMATCH);
hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
ip += repLength2;
anchor = ip;
@@ -411,7 +411,7 @@ static size_t ZSTD_compressBlock_fast_extDict_generic(
const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
size_t const rLength = ZSTD_count_2segments(ip+1 +4, repMatch +4, iend, repMatchEnd, prefixStart) + 4;
ip++;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, 0, rLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, rLength-MINMATCH);
ip += rLength;
anchor = ip;
} else {
@@ -427,7 +427,7 @@ static size_t ZSTD_compressBlock_fast_extDict_generic(
size_t mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, prefixStart) + 4;
while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
offset_2 = offset_1; offset_1 = offset; /* update offset history */
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
ip += mLength;
anchor = ip;
} }
@@ -446,7 +446,7 @@ static size_t ZSTD_compressBlock_fast_extDict_generic(
const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
{ U32 const tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; } /* swap offset_2 <=> offset_1 */
ZSTD_storeSeq(seqStore, 0 /*litlen*/, anchor, 0 /*offcode*/, repLength2-MINMATCH);
ZSTD_storeSeq(seqStore, 0 /*litlen*/, anchor, iend, 0 /*offcode*/, repLength2-MINMATCH);
hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
ip += repLength2;
anchor = ip;
lib/compress/zstd_lazy.c
+5 -5
View File
@@ -810,7 +810,7 @@ ZSTD_compressBlock_lazy_generic(
/* store sequence */
_storeSequence:
{ size_t const litLength = start - anchor;
ZSTD_storeSeq(seqStore, litLength, anchor, (U32)offset, matchLength-MINMATCH);
ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offset, matchLength-MINMATCH);
anchor = ip = start + matchLength;
}
@@ -828,7 +828,7 @@ _storeSequence:
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, 0, matchLength-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength-MINMATCH);
ip += matchLength;
anchor = ip;
continue;
@@ -843,7 +843,7 @@ _storeSequence:
/* 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, 0, matchLength-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength-MINMATCH);
ip += matchLength;
anchor = ip;
continue; /* faster when present ... (?) */
@@ -1051,7 +1051,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(
/* store sequence */
_storeSequence:
{ size_t const litLength = start - anchor;
ZSTD_storeSeq(seqStore, litLength, anchor, (U32)offset, matchLength-MINMATCH);
ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offset, matchLength-MINMATCH);
anchor = ip = start + matchLength;
}
@@ -1066,7 +1066,7 @@ _storeSequence:
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, 0, matchLength-MINMATCH);
ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength-MINMATCH);
ip += matchLength;
anchor = ip;
continue; /* faster when present ... (?) */
lib/compress/zstd_ldm.c
+1 -1
View File
@@ -583,7 +583,7 @@ size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
rep[i] = rep[i-1];
rep[0] = sequence.offset;
/* Store the sequence */
ZSTD_storeSeq(seqStore, newLitLength, ip - newLitLength,
ZSTD_storeSeq(seqStore, newLitLength, ip - newLitLength, iend,
sequence.offset + ZSTD_REP_MOVE,
sequence.matchLength - MINMATCH);
ip += sequence.matchLength;
lib/compress/zstd_opt.c
+1 -1
View File
@@ -1098,7 +1098,7 @@ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
assert(anchor + llen <= iend);
ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen);
ZSTD_storeSeq(seqStore, llen, anchor, offCode, mlen-MINMATCH);
ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH);
anchor += advance;
ip = anchor;
} }
lib/decompress/zstd_decompress_block.c
+142 -144
View File
@@ -573,38 +573,118 @@ typedef struct {
size_t pos;
} seqState_t;
/*! ZSTD_overlapCopy8() :
* Copies 8 bytes from ip to op and updates op and ip where ip <= op.
* If the offset is < 8 then the offset is spread to at least 8 bytes.
*
* Precondition: *ip <= *op
* Postcondition: *op - *op >= 8
*/
static void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) {
assert(*ip <= *op);
if (offset < 8) {
/* close range match, overlap */
static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
int const sub2 = dec64table[offset];
(*op)[0] = (*ip)[0];
(*op)[1] = (*ip)[1];
(*op)[2] = (*ip)[2];
(*op)[3] = (*ip)[3];
*ip += dec32table[offset];
ZSTD_copy4(*op+4, *ip);
*ip -= sub2;
} else {
ZSTD_copy8(*op, *ip);
}
*ip += 8;
*op += 8;
assert(*op - *ip >= 8);
}
/* ZSTD_execSequenceLast7():
* exceptional case : decompress a match starting within last 7 bytes of output buffer.
* requires more careful checks, to ensure there is no overflow.
* performance does not matter though.
* note : this case is supposed to be never generated "naturally" by reference encoder,
* since in most cases it needs at least 8 bytes to look for a match.
* but it's allowed by the specification. */
/*! ZSTD_safecopy() :
* Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer
* and write up to 16 bytes past oend_w (op >= oend_w is allowed).
* This function is only called in the uncommon case where the sequence is near the end of the block. It
* should be fast for a single long sequence, but can be slow for several short sequences.
*
* @param ovtype controls the overlap detection
* - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart.
* - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart.
* The src buffer must be before the dst buffer.
*/
static void ZSTD_safecopy(BYTE* op, BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) {
ptrdiff_t const diff = op - ip;
BYTE* const oend = op + length;
assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8)) ||
(ovtype == ZSTD_overlap_src_before_dst && diff >= 0));
if (length < 8) {
/* Handle short lengths. */
while (op < oend) *op++ = *ip++;
return;
}
if (ovtype == ZSTD_overlap_src_before_dst) {
/* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */
assert(length >= 8);
ZSTD_overlapCopy8(&op, &ip, diff);
assert(op - ip >= 8);
assert(op <= oend);
}
if (oend <= oend_w) {
/* No risk of overwrite. */
ZSTD_wildcopy(op, ip, length, ovtype);
return;
}
if (op <= oend_w) {
/* Wildcopy until we get close to the end. */
assert(oend > oend_w);
ZSTD_wildcopy(op, ip, oend_w - op, ovtype);
ip += oend_w - op;
op = oend_w;
}
/* Handle the leftovers. */
while (op < oend) *op++ = *ip++;
}
/* ZSTD_execSequenceEnd():
* This version handles cases that are near the end of the output buffer. It requires
* more careful checks to make sure there is no overflow. By separating out these hard
* and unlikely cases, we can speed up the common cases.
*
* NOTE: This function needs to be fast for a single long sequence, but doesn't need
* to be optimized for many small sequences, since those fall into ZSTD_execSequence().
*/
FORCE_NOINLINE
size_t ZSTD_execSequenceLast7(BYTE* op,
BYTE* const oend, seq_t sequence,
const BYTE** litPtr, const BYTE* const litLimit,
const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd)
size_t ZSTD_execSequenceEnd(BYTE* op,
BYTE* const oend, seq_t sequence,
const BYTE** litPtr, const BYTE* const litLimit,
const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
{
BYTE* const oLitEnd = op + sequence.litLength;
size_t const sequenceLength = sequence.litLength + sequence.matchLength;
BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
const BYTE* const iLitEnd = *litPtr + sequence.litLength;
const BYTE* match = oLitEnd - sequence.offset;
BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
/* check */
RETURN_ERROR_IF(oMatchEnd>oend, dstSize_tooSmall, "last match must fit within dstBuffer");
/* bounds checks */
assert(oLitEnd < oMatchEnd);
RETURN_ERROR_IF(oMatchEnd > oend, dstSize_tooSmall, "last match must fit within dstBuffer");
RETURN_ERROR_IF(iLitEnd > litLimit, corruption_detected, "try to read beyond literal buffer");
/* copy literals */
while (op < oLitEnd) *op++ = *(*litPtr)++;
ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap);
op = oLitEnd;
*litPtr = iLitEnd;
/* copy Match */
if (sequence.offset > (size_t)(oLitEnd - base)) {
if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
/* offset beyond prefix */
RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - vBase),corruption_detected);
match = dictEnd - (base-match);
RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected);
match = dictEnd - (prefixStart-match);
if (match + sequence.matchLength <= dictEnd) {
memmove(oLitEnd, match, sequence.matchLength);
return sequenceLength;
@@ -614,13 +694,12 @@ size_t ZSTD_execSequenceLast7(BYTE* op,
memmove(oLitEnd, match, length1);
op = oLitEnd + length1;
sequence.matchLength -= length1;
match = base;
match = prefixStart;
} }
while (op < oMatchEnd) *op++ = *match++;
ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst);
return sequenceLength;
}
HINT_INLINE
size_t ZSTD_execSequence(BYTE* op,
BYTE* const oend, seq_t sequence,
@@ -634,20 +713,29 @@ size_t ZSTD_execSequence(BYTE* op,
const BYTE* const iLitEnd = *litPtr + sequence.litLength;
const BYTE* match = oLitEnd - sequence.offset;
/* check */
RETURN_ERROR_IF(oMatchEnd>oend, dstSize_tooSmall, "last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend");
RETURN_ERROR_IF(iLitEnd > litLimit, corruption_detected, "over-read beyond lit buffer");
if (oLitEnd>oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
/* Errors and uncommon cases handled here. */
assert(oLitEnd < oMatchEnd);
if (iLitEnd > litLimit || oMatchEnd > oend_w)
return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
/* copy Literals */
if (sequence.litLength > 8)
ZSTD_wildcopy_16min(op, (*litPtr), oend, sequence.litLength, ZSTD_no_overlap); /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
else
ZSTD_copy8(op, *litPtr);
/* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
assert(iLitEnd <= litLimit /* Literal length is in bounds */);
assert(oLitEnd <= oend_w /* Can wildcopy literals */);
assert(oMatchEnd <= oend_w /* Can wildcopy matches */);
/* Copy Literals:
* Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9.
* We likely don't need the full 32-byte wildcopy.
*/
assert(WILDCOPY_OVERLENGTH >= 16);
ZSTD_copy16(op, (*litPtr));
if (sequence.litLength > 16) {
ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap);
}
op = oLitEnd;
*litPtr = iLitEnd; /* update for next sequence */
/* copy Match */
/* Copy Match */
if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
/* offset beyond prefix -> go into extDict */
RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected);
@@ -662,123 +750,33 @@ size_t ZSTD_execSequence(BYTE* op,
op = oLitEnd + length1;
sequence.matchLength -= length1;
match = prefixStart;
if (op > oend_w || sequence.matchLength < MINMATCH) {
U32 i;
for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
return sequenceLength;
}
} }
/* Requirement: op <= oend_w && sequence.matchLength >= MINMATCH */
/* Match within prefix of 1 or more bytes */
assert(op <= oMatchEnd);
assert(oMatchEnd <= oend_w);
assert(match >= prefixStart);
assert(sequence.matchLength >= 1);
/* match within prefix */
if (sequence.offset < 8) {
/* close range match, overlap */
static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
int const sub2 = dec64table[sequence.offset];
op[0] = match[0];
op[1] = match[1];
op[2] = match[2];
op[3] = match[3];
match += dec32table[sequence.offset];
ZSTD_copy4(op+4, match);
match -= sub2;
} else {
ZSTD_copy8(op, match);
/* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
* without overlap checking.
*/
if (sequence.offset >= WILDCOPY_VECLEN) {
/* We bet on a full wildcopy for matches, since we expect matches to be
* longer than literals (in general). In silesia, ~10% of matches are longer
* than 16 bytes.
*/
ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap);
return sequenceLength;
}
op += 8; match += 8;
assert(sequence.offset < WILDCOPY_VECLEN);
if (oMatchEnd > oend-(16-MINMATCH)) {
if (op < oend_w) {
ZSTD_wildcopy(op, match, oend, oend_w - op, ZSTD_overlap_src_before_dst);
match += oend_w - op;
op = oend_w;
}
while (op < oMatchEnd) *op++ = *match++;
} else {
ZSTD_wildcopy(op, match, oend, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst); /* works even if matchLength < 8 */
}
return sequenceLength;
}
/* Copy 8 bytes and spread the offset to be >= 8. */
ZSTD_overlapCopy8(&op, &match, sequence.offset);
HINT_INLINE
size_t ZSTD_execSequenceLong(BYTE* op,
BYTE* const oend, seq_t sequence,
const BYTE** litPtr, const BYTE* const litLimit,
const BYTE* const prefixStart, const BYTE* const dictStart, const BYTE* const dictEnd)
{
BYTE* const oLitEnd = op + sequence.litLength;
size_t const sequenceLength = sequence.litLength + sequence.matchLength;
BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
const BYTE* const iLitEnd = *litPtr + sequence.litLength;
const BYTE* match = sequence.match;
/* check */
RETURN_ERROR_IF(oMatchEnd > oend, dstSize_tooSmall, "last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend");
RETURN_ERROR_IF(iLitEnd > litLimit, corruption_detected, "over-read beyond lit buffer");
if (oLitEnd > oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, prefixStart, dictStart, dictEnd);
/* copy Literals */
if (sequence.litLength > 8)
ZSTD_wildcopy_16min(op, *litPtr, oend, sequence.litLength, ZSTD_no_overlap); /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
else
ZSTD_copy8(op, *litPtr); /* note : op <= oLitEnd <= oend_w == oend - 8 */
op = oLitEnd;
*litPtr = iLitEnd; /* update for next sequence */
/* copy Match */
if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
/* offset beyond prefix */
RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - dictStart), corruption_detected);
if (match + sequence.matchLength <= dictEnd) {
memmove(oLitEnd, match, sequence.matchLength);
return sequenceLength;
}
/* span extDict & currentPrefixSegment */
{ size_t const length1 = dictEnd - match;
memmove(oLitEnd, match, length1);
op = oLitEnd + length1;
sequence.matchLength -= length1;
match = prefixStart;
if (op > oend_w || sequence.matchLength < MINMATCH) {
U32 i;
for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
return sequenceLength;
}
} }
assert(op <= oend_w);
assert(sequence.matchLength >= MINMATCH);
/* match within prefix */
if (sequence.offset < 8) {
/* close range match, overlap */
static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
int const sub2 = dec64table[sequence.offset];
op[0] = match[0];
op[1] = match[1];
op[2] = match[2];
op[3] = match[3];
match += dec32table[sequence.offset];
ZSTD_copy4(op+4, match);
match -= sub2;
} else {
ZSTD_copy8(op, match);
}
op += 8; match += 8;
if (oMatchEnd > oend-(16-MINMATCH)) {
if (op < oend_w) {
ZSTD_wildcopy(op, match, oend, oend_w - op, ZSTD_overlap_src_before_dst);
match += oend_w - op;
op = oend_w;
}
while (op < oMatchEnd) *op++ = *match++;
} else {
ZSTD_wildcopy(op, match, oend, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst); /* works even if matchLength < 8 */
/* If the match length is > 8 bytes, then continue with the wildcopy. */
if (sequence.matchLength > 8) {
assert(op < oMatchEnd);
ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst);
}
return sequenceLength;
}
@@ -1098,7 +1096,7 @@ ZSTD_decompressSequencesLong_body(
/* decode and decompress */
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb<nbSeq) ; seqNb++) {
seq_t const sequence = ZSTD_decodeSequenceLong(&seqState, isLongOffset);
size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
PREFETCH_L1(sequence.match); PREFETCH_L1(sequence.match + sequence.matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
sequences[seqNb & STORED_SEQS_MASK] = sequence;
@@ -1109,7 +1107,7 @@ ZSTD_decompressSequencesLong_body(
/* finish queue */
seqNb -= seqAdvance;
for ( ; seqNb<nbSeq ; seqNb++) {
size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[seqNb&STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[seqNb&STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
op += oneSeqSize;
}
tests/decodecorpus.c
+2 -2
View File
@@ -758,8 +758,8 @@ static U32 generateSequences(U32* seed, frame_t* frame, seqStore_t* seqStore,
DISPLAYLEVEL(7, " repeat offset: %d\n", (int)repIndex);
}
/* use libzstd sequence handling */
ZSTD_storeSeq(seqStore, literalLen, literals, offsetCode,
matchLen - MINMATCH);
ZSTD_storeSeq(seqStore, literalLen, literals, literals + literalLen,
offsetCode, matchLen - MINMATCH);
literalsSize -= literalLen;
excessMatch -= (matchLen - MIN_SEQ_LEN);