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changed ZSTD_decompressSequences_bodySplitLitBuffer() decoding loop

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to behave more like the regular decoding loop.
This commit is contained in:
Yann Collet
2023-06-16 15:32:07 -07:00
parent 84e898a76c
commit 33fca19dd4
1 changed files with 20 additions and 22 deletions
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lib/decompress/zstd_decompress_block.c
+20 -22
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@@ -1532,7 +1532,7 @@ ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer (%i seqs)", nbSeq); DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer (%i seqs)", nbSeq);
/* Regen sequences */ /* Literals are split between internal buffer & output buffer */
if (nbSeq) { if (nbSeq) {
seqState_t seqState; seqState_t seqState;
dctx->fseEntropy = 1; dctx->fseEntropy = 1;
@@ -1551,8 +1551,7 @@ ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
BIT_DStream_completed < BIT_DStream_overflow); BIT_DStream_completed < BIT_DStream_overflow);
/* decompress without overrunning litPtr begins */ /* decompress without overrunning litPtr begins */
{ { seq_t sequence;
seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset, nbSeq==1);
/* Align the decompression loop to 32 + 16 bytes. /* Align the decompression loop to 32 + 16 bytes.
* *
* zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression
@@ -1614,20 +1613,19 @@ ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
#endif #endif
/* Handle the initial state where litBuffer is currently split between dst and litExtraBuffer */ /* Handle the initial state where litBuffer is currently split between dst and litExtraBuffer */
for (; litPtr + sequence.litLength <= dctx->litBufferEnd; ) { for ( ; nbSeq; nbSeq--) {
size_t const oneSeqSize = ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence.litLength - WILDCOPY_OVERLENGTH, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
assert(!ZSTD_isError(oneSeqSize));
ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
#endif
if (UNLIKELY(ZSTD_isError(oneSeqSize)))
return oneSeqSize;
DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
op += oneSeqSize;
if (UNLIKELY(!--nbSeq))
break;
sequence = ZSTD_decodeSequence(&seqState, isLongOffset, nbSeq==1); sequence = ZSTD_decodeSequence(&seqState, isLongOffset, nbSeq==1);
} if (litPtr + sequence.litLength > dctx->litBufferEnd) break;
{ size_t const oneSeqSize = ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence.litLength - WILDCOPY_OVERLENGTH, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
assert(!ZSTD_isError(oneSeqSize));
ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
#endif
if (UNLIKELY(ZSTD_isError(oneSeqSize)))
return oneSeqSize;
DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
op += oneSeqSize;
} }
DEBUGLOG(6, "reached: (litPtr + sequence.litLength > dctx->litBufferEnd)"); DEBUGLOG(6, "reached: (litPtr + sequence.litLength > dctx->litBufferEnd)");
/* If there are more sequences, they will need to read literals from litExtraBuffer; copy over the remainder from dst and update litPtr and litEnd */ /* If there are more sequences, they will need to read literals from litExtraBuffer; copy over the remainder from dst and update litPtr and litEnd */
@@ -1657,8 +1655,8 @@ ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
} }
} }
if (nbSeq > 0) /* there is remaining lit from extra buffer */ if (nbSeq > 0) {
{ /* there is remaining lit from extra buffer */
#if defined(__GNUC__) && defined(__x86_64__) #if defined(__GNUC__) && defined(__x86_64__)
__asm__(".p2align 6"); __asm__(".p2align 6");
@@ -1701,8 +1699,8 @@ ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
} }
/* last literal segment */ /* last literal segment */
if (dctx->litBufferLocation == ZSTD_split) /* split hasn't been reached yet, first get dst then copy litExtraBuffer */ if (dctx->litBufferLocation == ZSTD_split) {
{ /* split hasn't been reached yet, first get dst then copy litExtraBuffer */
size_t const lastLLSize = litBufferEnd - litPtr; size_t const lastLLSize = litBufferEnd - litPtr;
RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, ""); RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, "");
if (op != NULL) { if (op != NULL) {
@@ -1713,13 +1711,13 @@ ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE; litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
dctx->litBufferLocation = ZSTD_not_in_dst; dctx->litBufferLocation = ZSTD_not_in_dst;
} }
/* copy last literals from interal buffer */
{ size_t const lastLLSize = litBufferEnd - litPtr; { size_t const lastLLSize = litBufferEnd - litPtr;
RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
if (op != NULL) { if (op != NULL) {
ZSTD_memcpy(op, litPtr, lastLLSize); ZSTD_memcpy(op, litPtr, lastLLSize);
op += lastLLSize; op += lastLLSize;
} } }
}
return op-ostart; return op-ostart;
} }