From: Nick Terrell Date: Tue, 26 Nov 2019 02:26:19 +0000 (-0800) Subject: Optimize decompression speed for gcc and clang (#1892) X-Git-Tag: v1.4.5^2~144 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=718f00ff6fe42db7e6ba09a7f7992b3e85283f77;p=thirdparty%2Fzstd.git Optimize decompression speed for gcc and clang (#1892) * Optimize `ZSTD_decodeSequence()` * Optimize Huffman decoding * Optimize `ZSTD_decompressSequences()` * Delete `ZSTD_decodeSequenceLong()` --- diff --git a/lib/common/bitstream.h b/lib/common/bitstream.h index 1c294b80d..fe3148eeb 100644 --- a/lib/common/bitstream.h +++ b/lib/common/bitstream.h @@ -48,6 +48,7 @@ extern "C" { * Dependencies ******************************************/ #include "mem.h" /* unaligned access routines */ +#include "compiler.h" /* UNLIKELY() */ #include "debug.h" /* assert(), DEBUGLOG(), RAWLOG() */ #include "error_private.h" /* error codes and messages */ @@ -411,6 +412,23 @@ MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits) return value; } +/*! BIT_reloadDStreamFast() : + * Similar to BIT_reloadDStream(), but with two differences: + * 1. bitsConsumed <= sizeof(bitD->bitContainer)*8 must hold! + * 2. Returns BIT_DStream_overflow when bitD->ptr < bitD->limitPtr, at this + * point you must use BIT_reloadDStream() to reload. + */ +MEM_STATIC BIT_DStream_status BIT_reloadDStreamFast(BIT_DStream_t* bitD) +{ + if (UNLIKELY(bitD->ptr < bitD->limitPtr)) + return BIT_DStream_overflow; + assert(bitD->bitsConsumed <= sizeof(bitD->bitContainer)*8); + bitD->ptr -= bitD->bitsConsumed >> 3; + bitD->bitsConsumed &= 7; + bitD->bitContainer = MEM_readLEST(bitD->ptr); + return BIT_DStream_unfinished; +} + /*! BIT_reloadDStream() : * Refill `bitD` from buffer previously set in BIT_initDStream() . * This function is safe, it guarantees it will not read beyond src buffer. @@ -422,10 +440,7 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD) return BIT_DStream_overflow; if (bitD->ptr >= bitD->limitPtr) { - bitD->ptr -= bitD->bitsConsumed >> 3; - bitD->bitsConsumed &= 7; - bitD->bitContainer = MEM_readLEST(bitD->ptr); - return BIT_DStream_unfinished; + return BIT_reloadDStreamFast(bitD); } if (bitD->ptr == bitD->start) { if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer; diff --git a/lib/common/compiler.h b/lib/common/compiler.h index 1877a0c1d..228845aa9 100644 --- a/lib/common/compiler.h +++ b/lib/common/compiler.h @@ -146,6 +146,19 @@ # define DONT_VECTORIZE #endif +/* Tell the compiler that a branch is likely or unlikely. + * Only use these macros if it causes the compiler to generate better code. + * If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc + * and clang, please do. + */ +#if defined(__GNUC__) +#define LIKELY(x) (__builtin_expect((x), 1)) +#define UNLIKELY(x) (__builtin_expect((x), 0)) +#else +#define LIKELY(x) (x) +#define UNLIKELY(x) (x) +#endif + /* disable warnings */ #ifdef _MSC_VER /* Visual Studio */ # include /* For Visual 2005 */ diff --git a/lib/decompress/huf_decompress.c b/lib/decompress/huf_decompress.c index 12c1fce51..732e1c93b 100644 --- a/lib/decompress/huf_decompress.c +++ b/lib/decompress/huf_decompress.c @@ -294,6 +294,7 @@ HUF_decompress4X1_usingDTable_internal_body( { const BYTE* const istart = (const BYTE*) cSrc; BYTE* const ostart = (BYTE*) dst; BYTE* const oend = ostart + dstSize; + BYTE* const olimit = oend - 3; const void* const dtPtr = DTable + 1; const HUF_DEltX1* const dt = (const HUF_DEltX1*)dtPtr; @@ -318,9 +319,9 @@ HUF_decompress4X1_usingDTable_internal_body( BYTE* op2 = opStart2; BYTE* op3 = opStart3; BYTE* op4 = opStart4; - U32 endSignal = BIT_DStream_unfinished; DTableDesc const dtd = HUF_getDTableDesc(DTable); U32 const dtLog = dtd.tableLog; + U32 endSignal = 1; if (length4 > cSrcSize) return ERROR(corruption_detected); /* overflow */ CHECK_F( BIT_initDStream(&bitD1, istart1, length1) ); @@ -329,8 +330,7 @@ HUF_decompress4X1_usingDTable_internal_body( CHECK_F( BIT_initDStream(&bitD4, istart4, length4) ); /* up to 16 symbols per loop (4 symbols per stream) in 64-bit mode */ - endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4); - while ( (endSignal==BIT_DStream_unfinished) && (op4<(oend-3)) ) { + for ( ; (endSignal) & (op4 < olimit) ; ) { HUF_DECODE_SYMBOLX1_2(op1, &bitD1); HUF_DECODE_SYMBOLX1_2(op2, &bitD2); HUF_DECODE_SYMBOLX1_2(op3, &bitD3); @@ -347,10 +347,10 @@ HUF_decompress4X1_usingDTable_internal_body( HUF_DECODE_SYMBOLX1_0(op2, &bitD2); HUF_DECODE_SYMBOLX1_0(op3, &bitD3); HUF_DECODE_SYMBOLX1_0(op4, &bitD4); - BIT_reloadDStream(&bitD1); - BIT_reloadDStream(&bitD2); - BIT_reloadDStream(&bitD3); - BIT_reloadDStream(&bitD4); + endSignal &= BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished; } /* check corruption */ @@ -769,7 +769,6 @@ HUF_decompress1X2_usingDTable_internal_body( return dstSize; } - FORCE_INLINE_TEMPLATE size_t HUF_decompress4X2_usingDTable_internal_body( void* dst, size_t dstSize, @@ -781,6 +780,7 @@ HUF_decompress4X2_usingDTable_internal_body( { const BYTE* const istart = (const BYTE*) cSrc; BYTE* const ostart = (BYTE*) dst; BYTE* const oend = ostart + dstSize; + BYTE* const olimit = oend - (sizeof(size_t)-1); const void* const dtPtr = DTable+1; const HUF_DEltX2* const dt = (const HUF_DEltX2*)dtPtr; @@ -805,7 +805,7 @@ HUF_decompress4X2_usingDTable_internal_body( BYTE* op2 = opStart2; BYTE* op3 = opStart3; BYTE* op4 = opStart4; - U32 endSignal; + U32 endSignal = 1; DTableDesc const dtd = HUF_getDTableDesc(DTable); U32 const dtLog = dtd.tableLog; @@ -816,8 +816,29 @@ HUF_decompress4X2_usingDTable_internal_body( CHECK_F( BIT_initDStream(&bitD4, istart4, length4) ); /* 16-32 symbols per loop (4-8 symbols per stream) */ - endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4); - for ( ; (endSignal==BIT_DStream_unfinished) & (op4<(oend-(sizeof(bitD4.bitContainer)-1))) ; ) { + for ( ; (endSignal) & (op4 < olimit); ) { +#ifdef __clang__ + HUF_DECODE_SYMBOLX2_2(op1, &bitD1); + HUF_DECODE_SYMBOLX2_1(op1, &bitD1); + HUF_DECODE_SYMBOLX2_2(op1, &bitD1); + HUF_DECODE_SYMBOLX2_0(op1, &bitD1); + HUF_DECODE_SYMBOLX2_2(op2, &bitD2); + HUF_DECODE_SYMBOLX2_1(op2, &bitD2); + HUF_DECODE_SYMBOLX2_2(op2, &bitD2); + HUF_DECODE_SYMBOLX2_0(op2, &bitD2); + endSignal &= BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished; + HUF_DECODE_SYMBOLX2_2(op3, &bitD3); + HUF_DECODE_SYMBOLX2_1(op3, &bitD3); + HUF_DECODE_SYMBOLX2_2(op3, &bitD3); + HUF_DECODE_SYMBOLX2_0(op3, &bitD3); + HUF_DECODE_SYMBOLX2_2(op4, &bitD4); + HUF_DECODE_SYMBOLX2_1(op4, &bitD4); + HUF_DECODE_SYMBOLX2_2(op4, &bitD4); + HUF_DECODE_SYMBOLX2_0(op4, &bitD4); + endSignal &= BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished; +#else HUF_DECODE_SYMBOLX2_2(op1, &bitD1); HUF_DECODE_SYMBOLX2_2(op2, &bitD2); HUF_DECODE_SYMBOLX2_2(op3, &bitD3); @@ -834,8 +855,11 @@ HUF_decompress4X2_usingDTable_internal_body( HUF_DECODE_SYMBOLX2_0(op2, &bitD2); HUF_DECODE_SYMBOLX2_0(op3, &bitD3); HUF_DECODE_SYMBOLX2_0(op4, &bitD4); - - endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4); + endSignal &= BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished; + endSignal &= BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished; +#endif } /* check corruption */ diff --git a/lib/decompress/zstd_decompress_block.c b/lib/decompress/zstd_decompress_block.c index 767e5f9a0..ce43c5255 100644 --- a/lib/decompress/zstd_decompress_block.c +++ b/lib/decompress/zstd_decompress_block.c @@ -715,7 +715,7 @@ size_t ZSTD_execSequence(BYTE* op, /* Errors and uncommon cases handled here. */ assert(oLitEnd < oMatchEnd); - if (iLitEnd > litLimit || oMatchEnd > oend_w) + if (UNLIKELY(iLitEnd > litLimit || oMatchEnd > oend_w)) return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd); /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */ @@ -729,7 +729,7 @@ size_t ZSTD_execSequence(BYTE* op, */ assert(WILDCOPY_OVERLENGTH >= 16); ZSTD_copy16(op, (*litPtr)); - if (sequence.litLength > 16) { + if (UNLIKELY(sequence.litLength > 16)) { ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap); } op = oLitEnd; @@ -738,7 +738,7 @@ size_t ZSTD_execSequence(BYTE* op, /* 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); + RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected); match = dictEnd + (match - prefixStart); if (match + sequence.matchLength <= dictEnd) { memmove(oLitEnd, match, sequence.matchLength); @@ -760,7 +760,7 @@ size_t ZSTD_execSequence(BYTE* op, /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy * without overlap checking. */ - if (sequence.offset >= WILDCOPY_VECLEN) { + if (LIKELY(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. @@ -802,6 +802,14 @@ ZSTD_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD) DStatePtr->state = DInfo.nextState + lowBits; } +FORCE_INLINE_TEMPLATE void +ZSTD_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, ZSTD_seqSymbol const DInfo) +{ + U32 const nbBits = DInfo.nbBits; + size_t const lowBits = BIT_readBits(bitD, nbBits); + DStatePtr->state = DInfo.nextState + lowBits; +} + /* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum * offset bits. But we can only read at most (STREAM_ACCUMULATOR_MIN_32 - 1) * bits before reloading. This value is the maximum number of bytes we read @@ -813,25 +821,26 @@ ZSTD_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD) : 0) typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e; +typedef enum { ZSTD_p_noPrefetch=0, ZSTD_p_prefetch=1 } ZSTD_prefetch_e; -#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG FORCE_INLINE_TEMPLATE seq_t -ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets) +ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets, const ZSTD_prefetch_e prefetch) { seq_t seq; - U32 const llBits = seqState->stateLL.table[seqState->stateLL.state].nbAdditionalBits; - U32 const mlBits = seqState->stateML.table[seqState->stateML.state].nbAdditionalBits; - U32 const ofBits = seqState->stateOffb.table[seqState->stateOffb.state].nbAdditionalBits; - U32 const totalBits = llBits+mlBits+ofBits; - U32 const llBase = seqState->stateLL.table[seqState->stateLL.state].baseValue; - U32 const mlBase = seqState->stateML.table[seqState->stateML.state].baseValue; - U32 const ofBase = seqState->stateOffb.table[seqState->stateOffb.state].baseValue; + ZSTD_seqSymbol const llDInfo = seqState->stateLL.table[seqState->stateLL.state]; + ZSTD_seqSymbol const mlDInfo = seqState->stateML.table[seqState->stateML.state]; + ZSTD_seqSymbol const ofDInfo = seqState->stateOffb.table[seqState->stateOffb.state]; + U32 const llBase = llDInfo.baseValue; + U32 const mlBase = mlDInfo.baseValue; + U32 const ofBase = ofDInfo.baseValue; + BYTE const llBits = llDInfo.nbAdditionalBits; + BYTE const mlBits = mlDInfo.nbAdditionalBits; + BYTE const ofBits = ofDInfo.nbAdditionalBits; + BYTE const totalBits = llBits+mlBits+ofBits; /* sequence */ { size_t offset; - if (!ofBits) - offset = 0; - else { + if (ofBits > 1) { ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1); ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5); assert(ofBits <= MaxOff); @@ -845,53 +854,89 @@ ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets) offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */ if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); } - } - - if (ofBits <= 1) { - offset += (llBase==0); - if (offset) { - size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset]; - temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */ - if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1]; - seqState->prevOffset[1] = seqState->prevOffset[0]; - seqState->prevOffset[0] = offset = temp; - } else { /* offset == 0 */ - offset = seqState->prevOffset[0]; - } - } else { seqState->prevOffset[2] = seqState->prevOffset[1]; seqState->prevOffset[1] = seqState->prevOffset[0]; seqState->prevOffset[0] = offset; - } + } else { + U32 const ll0 = (llBase == 0); + if (LIKELY((ofBits == 0))) { + if (LIKELY(!ll0)) + offset = seqState->prevOffset[0]; + else { + offset = seqState->prevOffset[1]; + seqState->prevOffset[1] = seqState->prevOffset[0]; + seqState->prevOffset[0] = offset; + } + } else { + offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1); + { size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset]; + temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */ + if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1]; + seqState->prevOffset[1] = seqState->prevOffset[0]; + seqState->prevOffset[0] = offset = temp; + } } } seq.offset = offset; } - seq.matchLength = mlBase - + ((mlBits>0) ? BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/) : 0); /* <= 16 bits */ + seq.matchLength = mlBase; + if (mlBits > 0) + seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/); + if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32)) BIT_reloadDStream(&seqState->DStream); - if (MEM_64bits() && (totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog))) + if (MEM_64bits() && UNLIKELY(totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog))) BIT_reloadDStream(&seqState->DStream); /* Ensure there are enough bits to read the rest of data in 64-bit mode. */ ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64); - seq.litLength = llBase - + ((llBits>0) ? BIT_readBitsFast(&seqState->DStream, llBits/*>0*/) : 0); /* <= 16 bits */ + seq.litLength = llBase; + if (llBits > 0) + seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/); + if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u", (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset); - /* ANS state update */ - ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */ - ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */ - if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ - ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */ + if (prefetch == ZSTD_p_prefetch) { + size_t const pos = seqState->pos + seq.litLength; + const BYTE* const matchBase = (seq.offset > pos) ? seqState->dictEnd : seqState->prefixStart; + seq.match = matchBase + pos - seq.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted. + * No consequence though : no memory access will occur, offset is only used for prefetching */ + seqState->pos = pos + seq.matchLength; + } + + /* ANS state update + * gcc-9.0.0 does 2.5% worse with ZSTD_updateFseStateWithDInfo(). + * clang-9.2.0 does 7% worse with ZSTD_updateFseState(). + * Naturally it seems like ZSTD_updateFseStateWithDInfo() should be the + * better option, so it is the default for other compilers. But, if you + * measure that it is worse, please put up a pull request. + */ + { +#if defined(__GNUC__) && !defined(__clang__) + const int kUseUpdateFseState = 1; +#else + const int kUseUpdateFseState = 0; +#endif + if (kUseUpdateFseState) { + ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */ + ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */ + if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ + ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */ + } else { + ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llDInfo); /* <= 9 bits */ + ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlDInfo); /* <= 9 bits */ + if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ + ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofDInfo); /* <= 8 bits */ + } + } return seq; } +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG FORCE_INLINE_TEMPLATE size_t DONT_VECTORIZE ZSTD_decompressSequences_body( ZSTD_DCtx* dctx, @@ -914,6 +959,7 @@ ZSTD_decompressSequences_body( ZSTD_DCtx* dctx, /* Regen sequences */ if (nbSeq) { seqState_t seqState; + size_t error = 0; dctx->fseEntropy = 1; { U32 i; for (i=0; ientropy.rep[i]; } RETURN_ERROR_IF( @@ -928,17 +974,25 @@ ZSTD_decompressSequences_body( ZSTD_DCtx* dctx, BIT_DStream_endOfBuffer < BIT_DStream_completed && BIT_DStream_completed < BIT_DStream_overflow); - for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) { - nbSeq--; - { seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); - size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd); - DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); - if (ZSTD_isError(oneSeqSize)) return oneSeqSize; - op += oneSeqSize; - } } + for ( ; ; ) { + seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_noPrefetch); + size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd); + DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); + BIT_reloadDStream(&(seqState.DStream)); + /* gcc and clang both don't like early returns in this loop. + * gcc doesn't like early breaks either. + * Instead save an error and report it at the end. + * When there is an error, don't increment op, so we don't + * overwrite. + */ + if (UNLIKELY(ZSTD_isError(oneSeqSize))) error = oneSeqSize; + else op += oneSeqSize; + if (UNLIKELY(!--nbSeq)) break; + } /* check if reached exact end */ DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq); + if (ZSTD_isError(error)) return error; RETURN_ERROR_IF(nbSeq, corruption_detected); RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected); /* save reps for next block */ @@ -965,87 +1019,7 @@ ZSTD_decompressSequences_default(ZSTD_DCtx* dctx, } #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ - - #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT -FORCE_INLINE_TEMPLATE seq_t -ZSTD_decodeSequenceLong(seqState_t* seqState, ZSTD_longOffset_e const longOffsets) -{ - seq_t seq; - U32 const llBits = seqState->stateLL.table[seqState->stateLL.state].nbAdditionalBits; - U32 const mlBits = seqState->stateML.table[seqState->stateML.state].nbAdditionalBits; - U32 const ofBits = seqState->stateOffb.table[seqState->stateOffb.state].nbAdditionalBits; - U32 const totalBits = llBits+mlBits+ofBits; - U32 const llBase = seqState->stateLL.table[seqState->stateLL.state].baseValue; - U32 const mlBase = seqState->stateML.table[seqState->stateML.state].baseValue; - U32 const ofBase = seqState->stateOffb.table[seqState->stateOffb.state].baseValue; - - /* sequence */ - { size_t offset; - if (!ofBits) - offset = 0; - else { - ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1); - ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5); - assert(ofBits <= MaxOff); - if (MEM_32bits() && longOffsets) { - U32 const extraBits = ofBits - MIN(ofBits, STREAM_ACCUMULATOR_MIN_32-1); - offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits); - if (MEM_32bits() || extraBits) BIT_reloadDStream(&seqState->DStream); - if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits); - } else { - offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */ - if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); - } - } - - if (ofBits <= 1) { - offset += (llBase==0); - if (offset) { - size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset]; - temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */ - if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1]; - seqState->prevOffset[1] = seqState->prevOffset[0]; - seqState->prevOffset[0] = offset = temp; - } else { - offset = seqState->prevOffset[0]; - } - } else { - seqState->prevOffset[2] = seqState->prevOffset[1]; - seqState->prevOffset[1] = seqState->prevOffset[0]; - seqState->prevOffset[0] = offset; - } - seq.offset = offset; - } - - seq.matchLength = mlBase + ((mlBits>0) ? BIT_readBitsFast(&seqState->DStream, mlBits) : 0); /* <= 16 bits */ - if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32)) - BIT_reloadDStream(&seqState->DStream); - if (MEM_64bits() && (totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog))) - BIT_reloadDStream(&seqState->DStream); - /* Verify that there is enough bits to read the rest of the data in 64-bit mode. */ - ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64); - - seq.litLength = llBase + ((llBits>0) ? BIT_readBitsFast(&seqState->DStream, llBits) : 0); /* <= 16 bits */ - if (MEM_32bits()) - BIT_reloadDStream(&seqState->DStream); - - { size_t const pos = seqState->pos + seq.litLength; - const BYTE* const matchBase = (seq.offset > pos) ? seqState->dictEnd : seqState->prefixStart; - seq.match = matchBase + pos - seq.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted. - * No consequence though : no memory access will occur, overly large offset will be detected in ZSTD_execSequenceLong() */ - seqState->pos = pos + seq.matchLength; - } - - /* ANS state update */ - ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */ - ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */ - if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ - ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */ - - return seq; -} - FORCE_INLINE_TEMPLATE size_t ZSTD_decompressSequencesLong_body( ZSTD_DCtx* dctx, @@ -1088,14 +1062,14 @@ ZSTD_decompressSequencesLong_body( /* prepare in advance */ for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb