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optimization: instantiate specialized version without Sequence checking code

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results in +4% compression speed,
thanks to removal of branches in the hot loop.
This commit is contained in:
Yann Collet
2024-12-20 10:36:59 -08:00
parent a288751de7
commit 1f6d6815c3
1 changed files with 41 additions and 11 deletions
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lib/compress/zstd_compress.c
+41 -11
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@@ -7102,12 +7102,13 @@ size_t ZSTD_compressSequences(ZSTD_CCtx* cctx,
* seqPos must end on an explicit block delimiter
* @blockSize must be exactly correct.
*/
static size_t
ZSTD_transferSequencesOnly_wBlockDelim(ZSTD_CCtx* cctx,
FORCE_INLINE_TEMPLATE size_t
ZSTD_transferSequencesOnly_wBlockDelim_internal(ZSTD_CCtx* cctx,
ZSTD_SequencePosition* seqPos, size_t* litConsumedPtr,
const ZSTD_Sequence* const inSeqs, size_t nbSequences,
size_t blockSize,
ZSTD_ParamSwitch_e externalRepSearch)
ZSTD_ParamSwitch_e externalRepSearch,
int const checkSequences)
{
U32 idx = seqPos->idx;
U32 const startIdx = idx;
@@ -7119,7 +7120,7 @@ ZSTD_transferSequencesOnly_wBlockDelim(ZSTD_CCtx* cctx,
DEBUGLOG(5, "ZSTD_transferSequencesOnly_wBlockDelim (blockSize = %zu)", blockSize);
/* dictSize is useful to check offset within Sequence validation */
if (cctx->appliedParams.validateSequences) {
if (checkSequences) {
if (cctx->cdict) {
dictSize = (U32)cctx->cdict->dictContentSize;
} else if (cctx->prefixDict.dict) {
@@ -7144,7 +7145,7 @@ ZSTD_transferSequencesOnly_wBlockDelim(ZSTD_CCtx* cctx,
}
DEBUGLOG(6, "Storing sequence: (of: %u, ml: %u, ll: %u)", offBase, matchLength, litLength);
if (cctx->appliedParams.validateSequences) {
if (checkSequences) {
seqPos->posInSrc += litLength + matchLength;
FORWARD_IF_ERROR(ZSTD_validateSequence(offBase, matchLength, cctx->appliedParams.cParams.minMatch,
seqPos->posInSrc,
@@ -7161,7 +7162,7 @@ ZSTD_transferSequencesOnly_wBlockDelim(ZSTD_CCtx* cctx,
/* last sequence (only literals) */
{ size_t const lastLitLength = inSeqs[idx].litLength;
litConsumed += lastLitLength;
if (cctx->appliedParams.validateSequences) {
if (checkSequences) {
seqPos->posInSrc += lastLitLength;
/* blockSize must be exactly correct (checked before calling this function) */
RETURN_ERROR_IF((seqPos->posInSrc - startPosInSrc) != blockSize, externalSequences_invalid, "mismatch between Sequences and specified blockSize");
@@ -7201,6 +7202,32 @@ ZSTD_transferSequencesOnly_wBlockDelim(ZSTD_CCtx* cctx,
return blockSize;
}
typedef size_t (*ZSTD_transferSequencesOnly_f) (ZSTD_CCtx* cctx,
ZSTD_SequencePosition* seqPos, size_t* litConsumedPtr,
const ZSTD_Sequence* const inSeqs, size_t nbSequences,
size_t blockSize,
ZSTD_ParamSwitch_e externalRepSearch);
static size_t
ZSTD_transferSequencesOnly_wBlockDelim(ZSTD_CCtx* cctx,
ZSTD_SequencePosition* seqPos, size_t* litConsumedPtr,
const ZSTD_Sequence* const inSeqs, size_t nbSequences,
size_t blockSize,
ZSTD_ParamSwitch_e externalRepSearch)
{
return ZSTD_transferSequencesOnly_wBlockDelim_internal(cctx, seqPos, litConsumedPtr, inSeqs, nbSequences, blockSize, externalRepSearch, 0);
}
static size_t
ZSTD_transferSequencesOnly_wBlockDelim_andCheckSequences(ZSTD_CCtx* cctx,
ZSTD_SequencePosition* seqPos, size_t* litConsumedPtr,
const ZSTD_Sequence* const inSeqs, size_t nbSequences,
size_t blockSize,
ZSTD_ParamSwitch_e externalRepSearch)
{
return ZSTD_transferSequencesOnly_wBlockDelim_internal(cctx, seqPos, litConsumedPtr, inSeqs, nbSequences, blockSize, externalRepSearch, 1);
}
static size_t
ZSTD_compressSequencesAndLiterals_internal(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
@@ -7211,6 +7238,9 @@ ZSTD_compressSequencesAndLiterals_internal(ZSTD_CCtx* cctx,
size_t remaining = srcSize;
ZSTD_SequencePosition seqPos = {0, 0, 0};
BYTE* op = (BYTE*)dst;
const ZSTD_transferSequencesOnly_f transfer = cctx->appliedParams.validateSequences ?
ZSTD_transferSequencesOnly_wBlockDelim_andCheckSequences
: ZSTD_transferSequencesOnly_wBlockDelim;
DEBUGLOG(4, "ZSTD_compressSequencesAndLiterals_internal: nbSeqs=%zu, litSize=%zu", nbSequences, litSize);
if (cctx->appliedParams.blockDelimiters == ZSTD_sf_noBlockDelimiters) {
@@ -7238,11 +7268,11 @@ ZSTD_compressSequencesAndLiterals_internal(ZSTD_CCtx* cctx,
assert(blockSize <= remaining);
ZSTD_resetSeqStore(&cctx->seqStore);
blockSize = ZSTD_transferSequencesOnly_wBlockDelim(cctx,
&seqPos, &litConsumed,
inSeqs, nbSequences,
blockSize,
cctx->appliedParams.searchForExternalRepcodes);
blockSize = transfer(cctx,
&seqPos, &litConsumed,
inSeqs, nbSequences,
blockSize,
cctx->appliedParams.searchForExternalRepcodes);
RETURN_ERROR_IF(blockSize != remaining, externalSequences_invalid, "Must consume the entire block");
RETURN_ERROR_IF(litConsumed != litSize, externalSequences_invalid, "Must consume the exact amount of literals provided");
FORWARD_IF_ERROR(blockSize, "Bad sequence copy");