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[huf] Add generic C versions of the fast decoding loops

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Add generic C versions of the fast decoding loops to serve architectures
that don't have an assembly implementation. Also allow selecting the C
decoding loop over the assembly decoding loop through a zstd
decompression parameter `ZSTD_d_disableHuffmanAssembly`.

I benchmarked on my Intel i9-9900K and my Macbook Air with an M1 processor.
The benchmark command forces zstd to compress without any matches, using
only literals compression, and measures only Huffman decompression speed:

```
zstd -b1e1 --compress-literals --zstd=tlen=131072 silesia.tar
```

The new fast decoding loops outperform the previous implementation uniformly,
but don't beat the x86-64 assembly. Additionally, the fast C decoding loops suffer
from the same stability problems that we've seen in the past, where the assembly
version doesn't. So even though clang gets close to assembly on x86-64, it still
has stability issues.

| Arch    | Function       | Compiler     | Default (MB/s) | Assembly (MB/s) | Fast (MB/s) |
|---------|----------------|--------------|----------------|-----------------|-------------|
| x86-64  | decompress 4X1 | gcc-12.2.0   |         1029.6 |          1308.1 |      1208.1 |
| x86-64  | decompress 4X1 | clang-14.0.6 |         1019.3 |          1305.6 |      1276.3 |
| x86-64  | decompress 4X2 | gcc-12.2.0   |         1348.5 |          1657.0 |      1374.1 |
| x86-64  | decompress 4X2 | clang-14.0.6 |         1027.6 |          1659.9 |      1468.1 |
| aarch64 | decompress 4X1 | clang-12.0.5 |         1081.0 |             N/A |      1234.9 |
| aarch64 | decompress 4X2 | clang-12.0.5 |         1270.0 |             N/A |      1516.6 |
This commit is contained in:
Nick Terrell 2023-01-13 16:34:52 -08:00 committed by Nick Terrell
parent f3255bfeff
commit 8957fef554
13 changed files with 448 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
lib/common/entropy_common.c
View File

@ -236,7 +236,7 @@ size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
const void* src, size_t srcSize)
{
U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0);
return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* flags */ 0);
}
FORCE_INLINE_TEMPLATE size_t
@ -328,13 +328,13 @@ size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats,
U32* nbSymbolsPtr, U32* tableLogPtr,
const void* src, size_t srcSize,
void* workSpace, size_t wkspSize,
int bmi2)
int flags)
{
#if DYNAMIC_BMI2
if (bmi2) {
if (flags & HUF_flags_bmi2) {
return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
}
#endif
(void)bmi2;
(void)flags;
return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
}

7
lib/common/huf.h
View File

@ -107,7 +107,12 @@ typedef enum {
* If set: Don't use assembly implementations
* If unset: Allow using assembly implementations
*/
HUF_flags_disableAsm = (1 << 4)
HUF_flags_disableAsm = (1 << 4),
/**
* If set: Don't use the fast decoding loop, always use the fallback decoding loop.
* If unset: Use the fast decoding loop when possible.
*/
HUF_flags_disableFast = (1 << 5)
} HUF_flags_e;

8
lib/common/portability_macros.h
View File

@ -137,12 +137,20 @@
/*
* For x86 ELF targets, add .note.gnu.property section for Intel CET in
* assembly sources when CET is enabled.
*
* Additionally, any function that may be called indirectly must begin
* with ZSTD_CET_ENDBRANCH.
*/
#if defined(__ELF__) && (defined(__x86_64__) || defined(__i386__)) \
&& defined(__has_include)
# if __has_include(<cet.h>)
# include <cet.h>
# define ZSTD_CET_ENDBRANCH _CET_ENDBR
# endif
#endif
#ifndef ZSTD_CET_ENDBRANCH
# define ZSTD_CET_ENDBRANCH
#endif
#endif /* ZSTD_PORTABILITY_MACROS_H */

425
lib/decompress/huf_decompress.c
View File

@ -43,10 +43,14 @@
#error "Cannot force the use of the X1 and X2 decoders at the same time!"
#endif
#if ZSTD_ENABLE_ASM_X86_64_BMI2 && DYNAMIC_BMI2
# define HUF_ASM_X86_64_BMI2_ATTRS BMI2_TARGET_ATTRIBUTE
/* When DYNAMIC_BMI2 is enabled, fast decoders are only called when bmi2 is
* supported at runtime, so we can add the BMI2 target attribute.
* When it is disabled, we will still get BMI2 if it is enabled statically.
*/
#if DYNAMIC_BMI2
# define HUF_FAST_BMI2_ATTRS BMI2_TARGET_ATTRIBUTE
#else
# define HUF_ASM_X86_64_BMI2_ATTRS
# define HUF_FAST_BMI2_ATTRS
#endif
#ifdef __cplusplus
@ -56,7 +60,7 @@
#endif
#define HUF_ASM_DECL HUF_EXTERN_C
#if DYNAMIC_BMI2 || (ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__))
#if DYNAMIC_BMI2
# define HUF_NEED_BMI2_FUNCTION 1
#else
# define HUF_NEED_BMI2_FUNCTION 0
@ -78,6 +82,11 @@
/* **************************************************************
* BMI2 Variant Wrappers
****************************************************************/
typedef size_t (*HUF_DecompressUsingDTableFn)(void *dst, size_t dstSize,
const void *cSrc,
size_t cSrcSize,
const HUF_DTable *DTable);
#if DYNAMIC_BMI2
#define HUF_DGEN(fn) \
@ -132,15 +141,28 @@ static DTableDesc HUF_getDTableDesc(const HUF_DTable* table)
return dtd;
}
#if ZSTD_ENABLE_ASM_X86_64_BMI2
static size_t HUF_initDStream(BYTE const* ip) {
static size_t HUF_initFastDStream(BYTE const* ip) {
BYTE const lastByte = ip[7];
size_t const bitsConsumed = lastByte ? 8 - ZSTD_highbit32(lastByte) : 0;
size_t const value = MEM_readLEST(ip) | 1;
assert(bitsConsumed <= 8);
assert(sizeof(size_t) == 8);
return value << bitsConsumed;
}
/**
* The input/output arguments to the Huffman fast decoding loop:
*
* ip [in/out] - The input pointers, must be updated to reflect what is consumed.
* op [in/out] - The output pointers, must be updated to reflect what is written.
* bits [in/out] - The bitstream containers, must be updated to reflect the current state.
* dt [in] - The decoding table.
* ilimit [in] - The input limit, stop when any input pointer is below ilimit.
* oend [in] - The end of the output stream. op[3] must not cross oend.
* iend [in] - The end of each input stream. ip[i] may cross iend[i],
* as long as it is above ilimit, but that indicates corruption.
*/
typedef struct {
BYTE const* ip[4];
BYTE* op[4];
@ -149,15 +171,17 @@ typedef struct {
BYTE const* ilimit;
BYTE* oend;
BYTE const* iend[4];
} HUF_DecompressAsmArgs;
} HUF_DecompressFastArgs;
typedef void (*HUF_DecompressFastLoopFn)(HUF_DecompressFastArgs*);
/**
* Initializes args for the asm decoding loop.
* @returns 0 on success
* 1 if the fallback implementation should be used.
* Initializes args for the fast decoding loop.
* @returns 1 on success
* 0 if the fallback implementation should be used.
* Or an error code on failure.
*/
static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst, size_t dstSize, void const* src, size_t srcSize, const HUF_DTable* DTable)
static size_t HUF_DecompressFastArgs_init(HUF_DecompressFastArgs* args, void* dst, size_t dstSize, void const* src, size_t srcSize, const HUF_DTable* DTable)
{
void const* dt = DTable + 1;
U32 const dtLog = HUF_getDTableDesc(DTable).tableLog;
@ -166,9 +190,11 @@ static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst,
BYTE* const oend = (BYTE*)dst + dstSize;
/* The following condition is false on x32 platform,
* but HUF_asm is not compatible with this ABI */
if (!(MEM_isLittleEndian() && !MEM_32bits())) return 1;
/* The fast decoding loop assumes 64-bit little-endian.
* This condition is false on x32.
*/
if (!MEM_isLittleEndian() || MEM_32bits())
return 0;
/* strict minimum : jump table + 1 byte per stream */
if (srcSize < 10)
@ -179,7 +205,7 @@ static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst,
* On small inputs we don't have enough data to trigger the fast loop, so use the old decoder.
*/
if (dtLog != HUF_DECODER_FAST_TABLELOG)
return 1;
return 0;
/* Read the jump table. */
{
@ -193,13 +219,13 @@ static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst,
args->iend[2] = args->iend[1] + length2;
args->iend[3] = args->iend[2] + length3;
/* HUF_initDStream() requires this, and this small of an input
/* HUF_initFastDStream() requires this, and this small of an input
* won't benefit from the ASM loop anyways.
* length1 must be >= 16 so that ip[0] >= ilimit before the loop
* starts.
*/
if (length1 < 16 || length2 < 8 || length3 < 8 || length4 < 8)
return 1;
return 0;
if (length4 > srcSize) return ERROR(corruption_detected); /* overflow */
}
/* ip[] contains the position that is currently loaded into bits[]. */
@ -216,7 +242,7 @@ static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst,
/* No point to call the ASM loop for tiny outputs. */
if (args->op[3] >= oend)
return 1;
return 0;
/* bits[] is the bit container.
* It is read from the MSB down to the LSB.
@ -225,10 +251,10 @@ static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst,
* set, so that CountTrailingZeros(bits[]) can be used
* to count how many bits we've consumed.
*/
args->bits[0] = HUF_initDStream(args->ip[0]);
args->bits[1] = HUF_initDStream(args->ip[1]);
args->bits[2] = HUF_initDStream(args->ip[2]);
args->bits[3] = HUF_initDStream(args->ip[3]);
args->bits[0] = HUF_initFastDStream(args->ip[0]);
args->bits[1] = HUF_initFastDStream(args->ip[1]);
args->bits[2] = HUF_initFastDStream(args->ip[2]);
args->bits[3] = HUF_initFastDStream(args->ip[3]);
/* If ip[] >= ilimit, it is guaranteed to be safe to
* reload bits[]. It may be beyond its section, but is
@ -239,10 +265,10 @@ static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst,
args->oend = oend;
args->dt = dt;
return 0;
return 1;
}
static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressAsmArgs const* args, int stream, BYTE* segmentEnd)
static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressFastArgs const* args, int stream, BYTE* segmentEnd)
{
/* Validate that we haven't overwritten. */
if (args->op[stream] > segmentEnd)
@ -257,7 +283,7 @@ static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressAsmArgs
/* Construct the BIT_DStream_t. */
assert(sizeof(size_t) == 8);
bit->bitContainer = MEM_readLE64(args->ip[stream]);
bit->bitContainer = MEM_readLEST(args->ip[stream]);
bit->bitsConsumed = ZSTD_countTrailingZeros64(args->bits[stream]);
bit->start = (const char*)args->iend[0];
bit->limitPtr = bit->start + sizeof(size_t);
@ -265,7 +291,6 @@ static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressAsmArgs
return 0;
}
#endif
#ifndef HUF_FORCE_DECOMPRESS_X2
@ -655,27 +680,132 @@ size_t HUF_decompress4X1_usingDTable_internal_default(void* dst, size_t dstSize,
#if ZSTD_ENABLE_ASM_X86_64_BMI2
HUF_ASM_DECL void HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop(HUF_DecompressAsmArgs* args) ZSTDLIB_HIDDEN;
HUF_ASM_DECL void HUF_decompress4X1_usingDTable_internal_fast_asm_loop(HUF_DecompressFastArgs* args) ZSTDLIB_HIDDEN;
static HUF_ASM_X86_64_BMI2_ATTRS
#endif
static HUF_FAST_BMI2_ATTRS
void HUF_decompress4X1_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs* args)
{
U64 bits[4];
BYTE const* ip[4];
BYTE* op[4];
U16 const* const dtable = (U16 const*)args->dt;
BYTE* const oend = args->oend;
BYTE const* const ilimit = args->ilimit;
/* Copy the arguments to local variables */
ZSTD_memcpy(&bits, &args->bits, sizeof(bits));
ZSTD_memcpy(&ip, &args->ip, sizeof(ip));
ZSTD_memcpy(&op, &args->op, sizeof(op));
assert(MEM_isLittleEndian());
assert(!MEM_32bits());
for (;;) {
BYTE* olimit;
int stream;
int symbol;
/* Assert loop preconditions */
#ifndef NDEBUG
for (stream = 0; stream < 4; ++stream) {
assert(op[stream] <= (stream == 3 ? oend : op[stream + 1]));
assert(ip[stream] >= ilimit);
}
#endif
/* Compute olimit */
{
/* Each iteration produces 5 output symbols per stream */
size_t const oiters = (size_t)(oend - op[3]) / 5;
/* Each iteration consumes up to 11 bits * 5 = 55 bits < 7 bytes
* per stream.
*/
size_t const iiters = (size_t)(ip[0] - ilimit) / 7;
/* We can safely run iters iterations before running bounds checks */
size_t const iters = MIN(oiters, iiters);
size_t const symbols = iters * 5;
/* We can simply check that op[3] < olimit, instead of checking all
* of our bounds, since we can't hit the other bounds until we've run
* iters iterations, which only happens when op[3] == olimit.
*/
olimit = op[3] + symbols;
/* Exit fast decoding loop once we get close to the end. */
if (op[3] + 20 > olimit)
break;
/* Exit the decoding loop if any input pointer has crossed the
* previous one. This indicates corruption, and a precondition
* to our loop is that ip[i] >= ip[0].
*/
for (stream = 1; stream < 4; ++stream) {
if (ip[stream] < ip[stream - 1])
break;
}
}
#ifndef NDEBUG
for (stream = 1; stream < 4; ++stream) {
assert(ip[stream] >= ip[stream - 1]);
}
#endif
do {
/* Decode 5 symbols in each of the 4 streams */
for (symbol = 0; symbol < 5; ++symbol) {
for (stream = 0; stream < 4; ++stream) {
int const index = (int)(bits[stream] >> 53);
int const entry = (int)dtable[index];
bits[stream] <<= (entry & 63);
op[stream][symbol] = (BYTE)((entry >> 8) & 0xFF);
}
}
/* Reload the bitstreams */
for (stream = 0; stream < 4; ++stream) {
int const ctz = ZSTD_countTrailingZeros64(bits[stream]);
int const nbBits = ctz & 7;
int const nbBytes = ctz >> 3;
op[stream] += 5;
ip[stream] -= nbBytes;
bits[stream] = MEM_read64(ip[stream]) | 1;
bits[stream] <<= nbBits;
}
} while (op[3] < olimit);
}
/* Save the final values of each of the state variables back to args. */
ZSTD_memcpy(&args->bits, &bits, sizeof(bits));
ZSTD_memcpy(&args->ip, &ip, sizeof(ip));
ZSTD_memcpy(&args->op, &op, sizeof(op));
}
/**
* @returns @p dstSize on success (>= 6)
* 0 if the fallback implementation should be used
* An error if an error occurred
*/
static HUF_FAST_BMI2_ATTRS
size_t
HUF_decompress4X1_usingDTable_internal_bmi2_asm(
HUF_decompress4X1_usingDTable_internal_fast(
void* dst, size_t dstSize,
const void* cSrc, size_t cSrcSize,
const HUF_DTable* DTable)
const HUF_DTable* DTable,
HUF_DecompressFastLoopFn loopFn)
{
void const* dt = DTable + 1;
const BYTE* const iend = (const BYTE*)cSrc + 6;
BYTE* const oend = (BYTE*)dst + dstSize;
HUF_DecompressAsmArgs args;
{ size_t const ret = HUF_DecompressAsmArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
FORWARD_IF_ERROR(ret, "Failed to init asm args");
if (ret != 0)
return HUF_decompress4X1_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
HUF_DecompressFastArgs args;
{ size_t const ret = HUF_DecompressFastArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
FORWARD_IF_ERROR(ret, "Failed to init fast loop args");
if (ret == 0)
return 0;
}
assert(args.ip[0] >= args.ilimit);
HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop(&args);
loopFn(&args);
/* Our loop guarantees that ip[] >= ilimit and that we haven't
* overwritten any op[].
@ -705,37 +835,43 @@ HUF_decompress4X1_usingDTable_internal_bmi2_asm(
}
/* decoded size */
assert(dstSize != 0);
return dstSize;
}
#endif /* ZSTD_ENABLE_ASM_X86_64_BMI2 */
typedef size_t (*HUF_decompress_usingDTable_t)(void *dst, size_t dstSize,
const void *cSrc,
size_t cSrcSize,
const HUF_DTable *DTable);
HUF_DGEN(HUF_decompress1X1_usingDTable_internal)
static size_t HUF_decompress4X1_usingDTable_internal(void* dst, size_t dstSize, void const* cSrc,
size_t cSrcSize, HUF_DTable const* DTable, int flags)
{
HUF_DecompressUsingDTableFn fallbackFn = HUF_decompress4X1_usingDTable_internal_default;
HUF_DecompressFastLoopFn loopFn = HUF_decompress4X1_usingDTable_internal_fast_c_loop;
#if DYNAMIC_BMI2
if (flags & HUF_flags_bmi2) {
fallbackFn = HUF_decompress4X1_usingDTable_internal_bmi2;
# if ZSTD_ENABLE_ASM_X86_64_BMI2
if (!(flags & HUF_flags_disableAsm))
return HUF_decompress4X1_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
if (!(flags & HUF_flags_disableAsm)) {
loopFn = HUF_decompress4X1_usingDTable_internal_fast_asm_loop;
}
# endif
return HUF_decompress4X1_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
} else {
return fallbackFn(dst, dstSize, cSrc, cSrcSize, DTable);
}
#else
(void)flags;
#endif
#if ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__)
if (!(flags & HUF_flags_disableAsm))
return HUF_decompress4X1_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
if (!(flags & HUF_flags_disableAsm)) {
loopFn = HUF_decompress4X1_usingDTable_internal_fast_asm_loop;
}
#endif
return HUF_decompress4X1_usingDTable_internal_default(dst, dstSize, cSrc, cSrcSize, DTable);
if (!(flags & HUF_flags_disableFast)) {
size_t const ret = HUF_decompress4X1_usingDTable_internal_fast(dst, dstSize, cSrc, cSrcSize, DTable, loopFn);
if (ret != 0)
return ret;
}
return fallbackFn(dst, dstSize, cSrc, cSrcSize, DTable);
}
static size_t HUF_decompress4X1_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize,
@ -1322,26 +1458,167 @@ size_t HUF_decompress4X2_usingDTable_internal_default(void* dst, size_t dstSize,
#if ZSTD_ENABLE_ASM_X86_64_BMI2
HUF_ASM_DECL void HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop(HUF_DecompressAsmArgs* args) ZSTDLIB_HIDDEN;
HUF_ASM_DECL void HUF_decompress4X2_usingDTable_internal_fast_asm_loop(HUF_DecompressFastArgs* args) ZSTDLIB_HIDDEN;
static HUF_ASM_X86_64_BMI2_ATTRS size_t
HUF_decompress4X2_usingDTable_internal_bmi2_asm(
#endif
static HUF_FAST_BMI2_ATTRS
void HUF_decompress4X2_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs* args)
{
U64 bits[4];
BYTE const* ip[4];
BYTE* op[4];
BYTE* oend[4];
HUF_DEltX2 const* const dtable = (HUF_DEltX2 const*)args->dt;
BYTE const* const ilimit = args->ilimit;
/* Copy the arguments to local registers. */
ZSTD_memcpy(&bits, &args->bits, sizeof(bits));
ZSTD_memcpy(&ip, &args->ip, sizeof(ip));
ZSTD_memcpy(&op, &args->op, sizeof(op));
oend[0] = op[1];
oend[1] = op[2];
oend[2] = op[3];
oend[3] = args->oend;
assert(MEM_isLittleEndian());
assert(!MEM_32bits());
for (;;) {
BYTE* olimit;
int stream;
int symbol;
/* Assert loop preconditions */
#ifndef NDEBUG
for (stream = 0; stream < 4; ++stream) {
assert(op[stream] <= oend[stream]);
assert(ip[stream] >= ilimit);
}
#endif
/* Compute olimit */
{
/* Each loop does 5 table lookups for each of the 4 streams.
* Each table lookup consumes up to 11 bits of input, and produces
* up to 2 bytes of output.
*/
/* We can consume up to 7 bytes of input per iteration per stream.
* We also know that each input pointer is >= ip[0]. So we can run
* iters loops before running out of input.
*/
size_t iters = (size_t)(ip[0] - ilimit) / 7;
/* Each iteration can produce up to 10 bytes of output per stream.
* Each output stream my advance at different rates. So take the
* minimum number of safe iterations among all the output streams.
*/
for (stream = 0; stream < 4; ++stream) {
size_t const oiters = (size_t)(oend[stream] - op[stream]) / 10;
iters = MIN(iters, oiters);
}
/* Each iteration produces at least 5 output symbols. So until
* op[3] crosses olimit, we know we haven't executed iters
* iterations yet. This saves us maintaining an iters counter,
* at the expense of computing the remaining # of iterations
* more frequently.
*/
olimit = op[3] + (iters * 5);
/* Exit the fast decoding loop if we are too close to the end. */
if (op[3] + 10 > olimit)
break;
/* Exit the decoding loop if any input pointer has crossed the
* previous one. This indicates corruption, and a precondition
* to our loop is that ip[i] >= ip[0].
*/
for (stream = 1; stream < 4; ++stream) {
if (ip[stream] < ip[stream - 1])
break;
}
}
#ifndef NDEBUG
for (stream = 1; stream < 4; ++stream) {
assert(ip[stream] >= ip[stream - 1]);
}
#endif
do {
/* Do 5 table lookups for each of the first 3 streams */
for (symbol = 0; symbol < 5; ++symbol) {
for (stream = 0; stream < 3; ++stream) {
int const index = (int)(bits[stream] >> 53);
HUF_DEltX2 const entry = dtable[index];
MEM_write16(op[stream], entry.sequence);
bits[stream] <<= (entry.nbBits);
op[stream] += (entry.length);
}
}
/* Do 1 table lookup from the final stream */
{
int const index = (int)(bits[3] >> 53);
HUF_DEltX2 const entry = dtable[index];
MEM_write16(op[3], entry.sequence);
bits[3] <<= (entry.nbBits);
op[3] += (entry.length);
}
/* Do 4 table lookups from the final stream & reload bitstreams */
for (stream = 0; stream < 4; ++stream) {
/* Do a table lookup from the final stream.
* This is interleaved with the reloading to reduce register
* pressure. This shouldn't be necessary, but compilers can
* struggle with codegen with high register pressure.
*/
{
int const index = (int)(bits[3] >> 53);
HUF_DEltX2 const entry = dtable[index];
MEM_write16(op[3], entry.sequence);
bits[3] <<= (entry.nbBits);
op[3] += (entry.length);
}
/* Reload the bistreams. The final bitstream must be reloaded
* after the 5th symbol was decoded.
*/
{
int const ctz = ZSTD_countTrailingZeros64(bits[stream]);
int const nbBits = ctz & 7;
int const nbBytes = ctz >> 3;
ip[stream] -= nbBytes;
bits[stream] = MEM_read64(ip[stream]) | 1;
bits[stream] <<= nbBits;
}
}
} while (op[3] < olimit);
}
/* Save the final values of each of the state variables back to args. */
ZSTD_memcpy(&args->bits, &bits, sizeof(bits));
ZSTD_memcpy(&args->ip, &ip, sizeof(ip));
ZSTD_memcpy(&args->op, &op, sizeof(op));
}
static HUF_FAST_BMI2_ATTRS size_t
HUF_decompress4X2_usingDTable_internal_fast(
void* dst, size_t dstSize,
const void* cSrc, size_t cSrcSize,
const HUF_DTable* DTable) {
const HUF_DTable* DTable,
HUF_DecompressFastLoopFn loopFn) {
void const* dt = DTable + 1;
const BYTE* const iend = (const BYTE*)cSrc + 6;
BYTE* const oend = (BYTE*)dst + dstSize;
HUF_DecompressAsmArgs args;
HUF_DecompressFastArgs args;
{
size_t const ret = HUF_DecompressAsmArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
size_t const ret = HUF_DecompressFastArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
FORWARD_IF_ERROR(ret, "Failed to init asm args");
if (ret != 0)
return HUF_decompress4X2_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
if (ret == 0)
return 0;
}
assert(args.ip[0] >= args.ilimit);
HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop(&args);
loopFn(&args);
/* note : op4 already verified within main loop */
assert(args.ip[0] >= iend);
@ -1372,28 +1649,38 @@ HUF_decompress4X2_usingDTable_internal_bmi2_asm(
/* decoded size */
return dstSize;
}
#endif /* ZSTD_ENABLE_ASM_X86_64_BMI2 */
static size_t HUF_decompress4X2_usingDTable_internal(void* dst, size_t dstSize, void const* cSrc,
size_t cSrcSize, HUF_DTable const* DTable, int flags)
{
HUF_DecompressUsingDTableFn fallbackFn = HUF_decompress4X2_usingDTable_internal_default;
HUF_DecompressFastLoopFn loopFn = HUF_decompress4X2_usingDTable_internal_fast_c_loop;
#if DYNAMIC_BMI2
if (flags & HUF_flags_bmi2) {
fallbackFn = HUF_decompress4X2_usingDTable_internal_bmi2;
# if ZSTD_ENABLE_ASM_X86_64_BMI2
if (!(flags & HUF_flags_disableAsm))
return HUF_decompress4X2_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
if (!(flags & HUF_flags_disableAsm)) {
loopFn = HUF_decompress4X2_usingDTable_internal_fast_asm_loop;
}
# endif
return HUF_decompress4X2_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
} else {
return fallbackFn(dst, dstSize, cSrc, cSrcSize, DTable);
}
#else
(void)flags;
#endif
#if ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__)
if (!(flags & HUF_flags_disableAsm))
return HUF_decompress4X2_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
if (!(flags & HUF_flags_disableAsm)) {
loopFn = HUF_decompress4X2_usingDTable_internal_fast_asm_loop;
}
#endif
return HUF_decompress4X2_usingDTable_internal_default(dst, dstSize, cSrc, cSrcSize, DTable);
if (!(flags & HUF_flags_disableFast)) {
size_t const ret = HUF_decompress4X2_usingDTable_internal_fast(dst, dstSize, cSrc, cSrcSize, DTable, loopFn);
if (ret != 0)
return ret;
}
return fallbackFn(dst, dstSize, cSrc, cSrcSize, DTable);
}
HUF_DGEN(HUF_decompress1X2_usingDTable_internal)

26
lib/decompress/huf_decompress_amd64.S
View File

@ -30,14 +30,14 @@
* TODO: Support Windows calling convention.
*/
ZSTD_HIDE_ASM_FUNCTION(HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop)
ZSTD_HIDE_ASM_FUNCTION(HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop)
ZSTD_HIDE_ASM_FUNCTION(_HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop)
ZSTD_HIDE_ASM_FUNCTION(_HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop)
.global HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop
.global HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop
.global _HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop
.global _HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop
ZSTD_HIDE_ASM_FUNCTION(HUF_decompress4X1_usingDTable_internal_fast_asm_loop)
ZSTD_HIDE_ASM_FUNCTION(HUF_decompress4X2_usingDTable_internal_fast_asm_loop)
ZSTD_HIDE_ASM_FUNCTION(_HUF_decompress4X2_usingDTable_internal_fast_asm_loop)
ZSTD_HIDE_ASM_FUNCTION(_HUF_decompress4X1_usingDTable_internal_fast_asm_loop)
.global HUF_decompress4X1_usingDTable_internal_fast_asm_loop
.global HUF_decompress4X2_usingDTable_internal_fast_asm_loop
.global _HUF_decompress4X1_usingDTable_internal_fast_asm_loop
.global _HUF_decompress4X2_usingDTable_internal_fast_asm_loop
.text
/* Sets up register mappings for clarity.
@ -95,8 +95,9 @@ ZSTD_HIDE_ASM_FUNCTION(_HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop)
/* Define both _HUF_* & HUF_* symbols because MacOS
* C symbols are prefixed with '_' & Linux symbols aren't.
*/
_HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop:
HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop:
_HUF_decompress4X1_usingDTable_internal_fast_asm_loop:
HUF_decompress4X1_usingDTable_internal_fast_asm_loop:
ZSTD_CET_ENDBRANCH
/* Save all registers - even if they are callee saved for simplicity. */
push %rax
push %rbx
@ -350,8 +351,9 @@ HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop:
pop %rax
ret
_HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop:
HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop:
_HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
ZSTD_CET_ENDBRANCH
/* Save all registers - even if they are callee saved for simplicity. */
push %rax
push %rbx

13
lib/decompress/zstd_decompress.c
View File

@ -243,6 +243,7 @@ static void ZSTD_DCtx_resetParameters(ZSTD_DCtx* dctx)
dctx->outBufferMode = ZSTD_bm_buffered;
dctx->forceIgnoreChecksum = ZSTD_d_validateChecksum;
dctx->refMultipleDDicts = ZSTD_rmd_refSingleDDict;
dctx->disableHufAsm = 0;
}
static void ZSTD_initDCtx_internal(ZSTD_DCtx* dctx)
@ -1811,6 +1812,11 @@ ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam)
bounds.lowerBound = (int)ZSTD_rmd_refSingleDDict;
bounds.upperBound = (int)ZSTD_rmd_refMultipleDDicts;
return bounds;
case ZSTD_d_disableHuffmanAssembly:
bounds.lowerBound = 0;
bounds.upperBound = 1;
return bounds;
default:;
}
bounds.error = ERROR(parameter_unsupported);
@ -1851,6 +1857,9 @@ size_t ZSTD_DCtx_getParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int* value
case ZSTD_d_refMultipleDDicts:
*value = (int)dctx->refMultipleDDicts;
return 0;
case ZSTD_d_disableHuffmanAssembly:
*value = (int)dctx->disableHufAsm;
return 0;
default:;
}
RETURN_ERROR(parameter_unsupported, "");
@ -1884,6 +1893,10 @@ size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter dParam, int value
}
dctx->refMultipleDDicts = (ZSTD_refMultipleDDicts_e)value;
return 0;
case ZSTD_d_disableHuffmanAssembly:
CHECK_DBOUNDS(ZSTD_d_disableHuffmanAssembly, value);
dctx->disableHufAsm = value != 0;
return 0;
default:;
}
RETURN_ERROR(parameter_unsupported, "");

4
lib/decompress/zstd_decompress_block.c
View File

@ -141,7 +141,9 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
U32 const lhc = MEM_readLE32(istart);
size_t hufSuccess;
size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
int const flags = ZSTD_DCtx_get_bmi2(dctx) ? HUF_flags_bmi2 : 0;
int const flags = 0
| (ZSTD_DCtx_get_bmi2(dctx) ? HUF_flags_bmi2 : 0)
| (dctx->disableHufAsm ? HUF_flags_disableAsm : 0);
switch(lhlCode)
{
case 0: case 1: default: /* note : default is impossible, since lhlCode into [0..3] */

1
lib/decompress/zstd_decompress_internal.h
View File

@ -165,6 +165,7 @@ struct ZSTD_DCtx_s
ZSTD_dictUses_e dictUses;
ZSTD_DDictHashSet* ddictSet; /* Hash set for multiple ddicts */
ZSTD_refMultipleDDicts_e refMultipleDDicts; /* User specified: if == 1, will allow references to multiple DDicts. Default == 0 (disabled) */
int disableHufAsm;
/* streaming */
ZSTD_dStreamStage streamStage;

15
lib/zstd.h
View File

@ -614,13 +614,15 @@ typedef enum {
* ZSTD_d_stableOutBuffer
* ZSTD_d_forceIgnoreChecksum
* ZSTD_d_refMultipleDDicts
* ZSTD_d_disableHuffmanAssembly
* Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them.
* note : never ever use experimentalParam? names directly
*/
ZSTD_d_experimentalParam1=1000,
ZSTD_d_experimentalParam2=1001,
ZSTD_d_experimentalParam3=1002,
ZSTD_d_experimentalParam4=1003
ZSTD_d_experimentalParam4=1003,
ZSTD_d_experimentalParam5=1004
} ZSTD_dParameter;
@ -2345,6 +2347,17 @@ ZSTDLIB_STATIC_API size_t ZSTD_DCtx_getParameter(ZSTD_DCtx* dctx, ZSTD_dParamete
*/
#define ZSTD_d_refMultipleDDicts ZSTD_d_experimentalParam4
/* ZSTD_d_disableHuffmanAssembly
* Set to 1 to disable the Huffman assembly implementation.
* The default value is 0, which allows zstd to use the Huffman assembly
* implementation if available.
*
* This parameter can be used to disable Huffman assembly at runtime.
* If you want to disable it at compile time you can define the macro
* ZSTD_DISABLE_ASM.
*/
#define ZSTD_d_disableHuffmanAssembly ZSTD_d_experimentalParam5
/*! ZSTD_DCtx_setFormat() :
* This function is REDUNDANT. Prefer ZSTD_DCtx_setParameter().

3
tests/fuzz/huf_decompress.c
View File

@ -33,7 +33,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_optimalDepth : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_preferRepeat : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_suspectUncompressible : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_disableAsm : 0);
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_disableAsm : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_disableFast : 0);
/* Select a random cBufSize - it may be too small */
size_t const dBufSize = FUZZ_dataProducer_uint32Range(producer, 0, 8 * size + 500);
size_t const maxTableLog = FUZZ_dataProducer_uint32Range(producer, 1, HUF_TABLELOG_MAX);

3
tests/fuzz/huf_round_trip.c
View File

@ -49,7 +49,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_optimalDepth : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_preferRepeat : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_suspectUncompressible : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_disableAsm : 0);
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_disableAsm : 0)
| (FUZZ_dataProducer_int32Range(producer, 0, 1) ? HUF_flags_disableFast : 0);
/* Select a random cBufSize - it may be too small */
size_t const cBufSize = FUZZ_dataProducer_uint32Range(producer, 0, 4 * size);
/* Select a random tableLog - we'll adjust it up later */

11
tests/fuzzer.c
View File

@ -684,6 +684,17 @@ static int basicUnitTests(U32 const seed, double compressibility)
if (r != CNBuffSize) goto _output_error; }
DISPLAYLEVEL(3, "OK \n");
DISPLAYLEVEL(3, "test%3i : decompress %u bytes with Huffman assembly disabled : ", testNb++, (unsigned)CNBuffSize);
{
ZSTD_DCtx* dctx = ZSTD_createDCtx();
size_t r;
CHECK_Z(ZSTD_DCtx_setParameter(dctx, ZSTD_d_disableHuffmanAssembly, 1));
r = ZSTD_decompress(decodedBuffer, CNBuffSize, compressedBuffer, cSize);
if (r != CNBuffSize || memcmp(decodedBuffer, CNBuffer, CNBuffSize)) goto _output_error;
ZSTD_freeDCtx(dctx);
}
DISPLAYLEVEL(3, "OK \n");
DISPLAYLEVEL(3, "test%3i : check decompressed result : ", testNb++);
{ size_t u;
for (u=0; u<CNBuffSize; u++) {

15
tests/zstreamtest.c
View File

@ -2889,6 +2889,9 @@ static int fuzzerTests_newAPI(U32 seed, int nbTests, int startTest,
CHECK(badParameters(zc, savedParams), "CCtx params are wrong");
/* multi - fragments decompression test */
if (FUZ_rand(&lseed) & 1) {
CHECK_Z(ZSTD_DCtx_reset(zd, ZSTD_reset_session_and_parameters));
}
if (!dictSize /* don't reset if dictionary : could be different */ && (FUZ_rand(&lseed) & 1)) {
DISPLAYLEVEL(5, "resetting DCtx (dict:%p) \n", (void const*)dict);
CHECK_Z( ZSTD_resetDStream(zd) );
@ -2897,6 +2900,9 @@ static int fuzzerTests_newAPI(U32 seed, int nbTests, int startTest,
DISPLAYLEVEL(5, "using dictionary of size %zu \n", dictSize);
CHECK_Z( ZSTD_initDStream_usingDict(zd, dict, dictSize) );
}
if (FUZ_rand(&lseed) & 1) {
CHECK_Z(ZSTD_DCtx_setParameter(zd, ZSTD_d_disableHuffmanAssembly, FUZ_rand(&lseed) & 1));
}
{ size_t decompressionResult = 1;
ZSTD_inBuffer inBuff = { cBuffer, cSize, 0 };
ZSTD_outBuffer outBuff= { dstBuffer, dstBufferSize, 0 };
@ -2938,7 +2944,14 @@ static int fuzzerTests_newAPI(U32 seed, int nbTests, int startTest,
} }
/* try decompression on noisy data */
CHECK_Z( ZSTD_initDStream(zd_noise) ); /* note : no dictionary */
if (FUZ_rand(&lseed) & 1) {
CHECK_Z(ZSTD_DCtx_reset(zd_noise, ZSTD_reset_session_and_parameters));
} else {
CHECK_Z(ZSTD_DCtx_reset(zd_noise, ZSTD_reset_session_only));
}
if (FUZ_rand(&lseed) & 1) {
CHECK_Z(ZSTD_DCtx_setParameter(zd_noise, ZSTD_d_disableHuffmanAssembly, FUZ_rand(&lseed) & 1));
}
{ ZSTD_inBuffer inBuff = { cBuffer, cSize, 0 };
ZSTD_outBuffer outBuff= { dstBuffer, dstBufferSize, 0 };
while (outBuff.pos < dstBufferSize) {