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Fix nits

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This commit is contained in:
Elliot Gorokhovsky 2022-02-07 12:22:04 -05:00
parent 796182652d
commit 529cd7b821
3 changed files with 102 additions and 162 deletions
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251
lib/common/bits.h
View File

@ -14,16 +14,19 @@
#include "mem.h"
MEM_STATIC unsigned ZSTD_highbit32_fallback(U32 val) {
static const U32 DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29,
11, 14, 16, 18, 22, 25, 3, 30,
8, 12, 20, 28, 15, 17, 24, 7,
19, 27, 23, 6, 26, 5, 4, 31 };
val |= val >> 1;
val |= val >> 2;
val |= val >> 4;
val |= val >> 8;
val |= val >> 16;
return DeBruijnClz[(val * 0x07C4ACDDU) >> 27];
assert(val != 0);
{
static const U32 DeBruijnClz[32] = {0, 9, 1, 10, 13, 21, 2, 29,
11, 14, 16, 18, 22, 25, 3, 30,
8, 12, 20, 28, 15, 17, 24, 7,
19, 27, 23, 6, 26, 5, 4, 31};
val |= val >> 1;
val |= val >> 2;
val |= val >> 4;
val |= val >> 8;
val |= val >> 16;
return DeBruijnClz[(val * 0x07C4ACDDU) >> 27];
}
}
MEM_STATIC unsigned ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCorpus */
@ -34,16 +37,11 @@ MEM_STATIC unsigned ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCo
# if STATIC_BMI2 == 1
return _lzcnt_u32(val)^31;
# else
if (val != 0) {
unsigned long r;
_BitScanReverse(&r, val);
return (unsigned)r;
} else {
/* Should not reach this code path */
__assume(0);
}
unsigned long r;
_BitScanReverse(&r, val);
return (unsigned)r;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */
# elif defined(__GNUC__) && (__GNUC__ >= 4) /* GCC Intrinsic */
return (unsigned)__builtin_clz (val) ^ 31;
# elif defined(__ICCARM__) /* IAR Intrinsic */
return 31 - __CLZ(val);
@ -55,45 +53,54 @@ MEM_STATIC unsigned ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCo
MEM_STATIC unsigned ZSTD_countTrailingZeros32_fallback(U32 val)
{
static const int DeBruijnBytePos[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 DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
assert(val != 0);
{
static const int DeBruijnBytePos[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 DeBruijnBytePos[((U32) ((val & -(S32) val) * 0x077CB531U)) >> 27];
}
}
MEM_STATIC unsigned ZSTD_countTrailingZeros32(U32 val)
{
assert(val != 0);
# if defined(_MSC_VER)
if (val != 0) {
unsigned long r;
_BitScanForward(&r, val);
return (unsigned)r;
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
unsigned long r;
_BitScanForward(&r, val);
return (unsigned)r;
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)__builtin_ctz(val);
# elif defined(__ICCARM__) /* IAR Intrinsic */
return __CTZ(val);
# else
return ZSTD_countTrailingZeros32_fallback(val);
# endif
}
MEM_STATIC unsigned ZSTD_countTrailingZeros64_fallback(U64 val)
MEM_STATIC unsigned ZSTD_countLeadingZeros32_fallback(U32 val) {
assert(val != 0);
{
unsigned result = 0;
while ((val & 0x80000000) == 0) {
result++;
val <<= 1;
}
return result;
}
}
MEM_STATIC unsigned ZSTD_countLeadingZeros32(U32 val)
{
static const int DeBruijnBytePos[64] = { 0, 1, 2, 7, 3, 13, 8, 19,
4, 25, 14, 28, 9, 34, 20, 56,
5, 17, 26, 54, 15, 41, 29, 43,
10, 31, 38, 35, 21, 45, 49, 57,
63, 6, 12, 18, 24, 27, 33, 55,
16, 53, 40, 42, 30, 37, 44, 48,
62, 11, 23, 32, 52, 39, 36, 47,
61, 22, 51, 46, 60, 50, 59, 58 };
return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
assert(val != 0);
# if defined(_MSC_VER)
unsigned long r;
_BitScanReverse(&r, val);
return (unsigned)r;
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)__builtin_clz(val);
# else
return ZSTD_countLeadingZeros32_fallback(val);
# endif
}
MEM_STATIC unsigned ZSTD_countTrailingZeros64(U64 val)
@ -103,142 +110,66 @@ MEM_STATIC unsigned ZSTD_countTrailingZeros64(U64 val)
# if STATIC_BMI2
return _tzcnt_u64(val);
# else
if (val != 0) {
unsigned long r;
_BitScanForward64(&r, val);
return (unsigned)r;
} else {
/* Should not reach this code path */
__assume(0);
}
unsigned long r;
_BitScanForward64(&r, val);
return (unsigned)r;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
if (MEM_32bits()) {
# elif defined(__GNUC__) && (__GNUC__ >= 4) && defined(__LP64__)
return (unsigned)__builtin_ctzll(val);
# else
{
U32 mostSignificantWord = (U32)(val >> 32);
U32 leastSignificantWord = (U32)val;
if (leastSignificantWord == 0) {
return 32 + (unsigned)__builtin_ctz(mostSignificantWord);
return 32 + ZSTD_countTrailingZeros32(mostSignificantWord);
} else {
return (unsigned)__builtin_ctz(leastSignificantWord);
return ZSTD_countTrailingZeros32(leastSignificantWord);
}
} else {
return (unsigned)__builtin_ctzll(val);
}
# else
return ZSTD_countTrailingZeros64_fallback(val);
# endif
}
MEM_STATIC unsigned ZSTD_NbCommonBytes_fallback(size_t val)
MEM_STATIC unsigned ZSTD_countLeadingZeros64(U64 val)
{
if (MEM_isLittleEndian()) {
if (MEM_64bits()) {
static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2,
0, 3, 1, 3, 1, 4, 2, 7,
0, 2, 3, 6, 1, 5, 3, 5,
1, 3, 4, 4, 2, 5, 6, 7,
7, 0, 1, 2, 3, 3, 4, 6,
2, 6, 5, 5, 3, 4, 5, 6,
7, 1, 2, 4, 6, 4, 4, 5,
7, 2, 6, 5, 7, 6, 7, 7 };
return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
} else { /* 32 bits */
static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0,
3, 2, 2, 1, 3, 2, 0, 1,
3, 3, 1, 2, 2, 2, 2, 0,
3, 1, 2, 0, 1, 0, 1, 1 };
return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
assert(val != 0);
# if defined(_MSC_VER) && defined(_WIN64)
# if STATIC_BMI2
return _lzcnt_u64(val);
# else
unsigned long r;
_BitScanReverse64(&r, val);
return (unsigned)r;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)(__builtin_clzll(val));
# else
{
U32 mostSignificantWord = (U32)(val >> 32);
U32 leastSignificantWord = (U32)val;
if (mostSignificantWord == 0) {
return 32 + ZSTD_countLeadingZeros32(leastSignificantWord);
} else {
return ZSTD_countLeadingZeros32(mostSignificantWord);
}
}
} else { /* Big Endian CPU */
unsigned r;
if (MEM_64bits()) {
const unsigned n32 = sizeof(size_t)*4; /* calculate this way due to compiler complaining in 32-bits mode */
if (!(val>>n32)) { r=4; } else { r=0; val>>=n32; }
if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
r += (!val);
return r;
} else { /* 32 bits */
if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; }
r += (!val);
return r;
}
}
# endif
}
MEM_STATIC unsigned ZSTD_NbCommonBytes(size_t val)
{
if (MEM_isLittleEndian()) {
if (MEM_64bits()) {
# if defined(_MSC_VER) && defined(_WIN64)
# if STATIC_BMI2
return _tzcnt_u64(val) >> 3;
# else
if (val != 0) {
unsigned long r;
_BitScanForward64(&r, (U64)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)(__builtin_ctzll((U64)val) >> 3);
# else
return ZSTD_NbCommonBytes_fallback(val);
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
if (val != 0) {
unsigned long r;
_BitScanForward(&r, (U32)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_ctz((U32)val) >> 3);
# else
return ZSTD_NbCommonBytes_fallback(val);
# endif
return ZSTD_countTrailingZeros64((U64)val) >> 3;
} else {
return ZSTD_countTrailingZeros32((U32)val) >> 3;
}
} else { /* Big Endian CPU */
if (MEM_64bits()) {
# if defined(_MSC_VER) && defined(_WIN64)
# if STATIC_BMI2
return _lzcnt_u64(val) >> 3;
# else
if (val != 0) {
unsigned long r;
_BitScanReverse64(&r, (U64)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)(__builtin_clzll(val) >> 3);
# else
return ZSTD_NbCommonBytes_fallback(val);
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
if (val != 0) {
unsigned long r;
_BitScanReverse(&r, (unsigned long)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_clz((U32)val) >> 3);
# else
return ZSTD_NbCommonBytes_fallback(val);
# endif
} }
return ZSTD_countLeadingZeros64((U64)val) >> 3;
} else {
return ZSTD_countLeadingZeros32((U32)val) >> 3;
}
}
}
#endif /* ZSTD_BITS_H */

12
lib/compress/zstd_lazy.c
View File

@ -766,6 +766,14 @@ size_t ZSTD_HcFindBestMatch(
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.
*/
MEM_STATIC U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
return ZSTD_countTrailingZeros64(val);
}
/* 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
@ -1165,7 +1173,7 @@ size_t ZSTD_RowFindBestMatch(
/* Cycle through the matches and prefetch */
for (; (matches > 0) && (nbAttempts > 0); --nbAttempts, matches &= (matches - 1)) {
U32 const matchPos = (head + ZSTD_countTrailingZeros64(matches)) & rowMask;
U32 const matchPos = (head + ZSTD_VecMask_next(matches)) & rowMask;
U32 const matchIndex = row[matchPos];
assert(numMatches < rowEntries);
if (matchIndex < lowLimit)
@ -1233,7 +1241,7 @@ size_t ZSTD_RowFindBestMatch(
ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, head, rowEntries);
for (; (matches > 0) && (nbAttempts > 0); --nbAttempts, matches &= (matches - 1)) {
U32 const matchPos = (head + ZSTD_countTrailingZeros64(matches)) & rowMask;
U32 const matchPos = (head + ZSTD_VecMask_next(matches)) & rowMask;
U32 const matchIndex = dmsRow[matchPos];
if (matchIndex < dmsLowestIndex)
break;

1
lib/decompress/huf_decompress.c
View File

@ -263,6 +263,7 @@ static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressAsmArgs
return ERROR(corruption_detected);
/* Construct the BIT_DStream_t. */
assert(sizeof(size_t) == 8);
bit->bitContainer = MEM_readLE64(args->ip[stream]);
bit->bitsConsumed = ZSTD_countTrailingZeros64(args->bits[stream]);
bit->start = (const char*)args->iend[0];