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Add ZSTD_DECOMPRESS_MINIMAL Macro, Which Reduces Branching of Decompress Variants

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This commit is contained in:
W. Felix Handte 2018-11-16 15:02:11 -08:00
parent f45c9df42e
commit df28e5babd
1 changed files with 8 additions and 1 deletions
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9
lib/decompress/zstd_decompress_block.c
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@ -1201,13 +1201,17 @@ ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
} }
/* Build Decoding Tables */ /* Build Decoding Tables */
{ int usePrefetchDecoder = dctx->ddictIsCold; {
#ifndef ZSTD_DECOMPRESS_MINIMAL
int usePrefetchDecoder = dctx->ddictIsCold;
#endif
int nbSeq; int nbSeq;
size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize); size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize);
if (ZSTD_isError(seqHSize)) return seqHSize; if (ZSTD_isError(seqHSize)) return seqHSize;
ip += seqHSize; ip += seqHSize;
srcSize -= seqHSize; srcSize -= seqHSize;
#ifndef ZSTD_DECOMPRESS_MINIMAL
if ( !usePrefetchDecoder if ( !usePrefetchDecoder
&& (!frame || (dctx->fParams.windowSize > (1<<24))) && (!frame || (dctx->fParams.windowSize > (1<<24)))
&& (nbSeq>ADVANCED_SEQS) ) { /* could probably use a larger nbSeq limit */ && (nbSeq>ADVANCED_SEQS) ) { /* could probably use a larger nbSeq limit */
@ -1215,11 +1219,14 @@ ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */ U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */
usePrefetchDecoder = (shareLongOffsets >= minShare); usePrefetchDecoder = (shareLongOffsets >= minShare);
} }
#endif
dctx->ddictIsCold = 0; dctx->ddictIsCold = 0;
#ifndef ZSTD_DECOMPRESS_MINIMAL
if (usePrefetchDecoder) if (usePrefetchDecoder)
return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset); return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset);
#endif
/* else */ /* else */
return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset); return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset);