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introduce macros STORE_OFFSET() and STORE_REPCODE()

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this meant to abstract the sumtype representation required
to transfert `offcode` to `ZSTD_storeSeq()`.

Unfortunately, the sumtype numeric representation is currently a leaky abstraction
that has permeated many other parts of the code,
especially within `zstd_lazy.c` and also within `zstd_opt.c` and `zstd_compress.c`.

While this PR makes a good job a transfering a large nb of call sites
to using the new macros, there are still a few sites where this transformation is more complex,
or where the numeric representation itself it used "as is".

One of the problematics area is the decision to use the numeric format of the sumtype
within the match finders of `zstd_lazy`.

This commit doesn't change the behavior, it only introduces and employes the macros,
but eventually the resulting code remains identical.

At target, if the numeric representation of the sumtype can be completely abstracted
and no other part of the code depends on it,
it will be possible to move it towards something slightly more efficient.
This commit is contained in:
Yann Collet
2021-12-23 22:03:30 -08:00
parent bec7bbb5a4
commit 1aed962216
8 changed files with 158 additions and 137 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/compress/zstd_compress.c
+65 -59
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@@ -3449,11 +3449,16 @@ static U32 ZSTD_resolveRepcodeToRawOffset(const U32 rep[ZSTD_REP_NUM], const U32
/**
* ZSTD_seqStore_resolveOffCodes() reconciles any possible divergences in offset history that may arise
* due to emission of RLE/raw blocks that disturb the offset history, and replaces any repcodes within
* the seqStore that may be invalid.
* due to emission of RLE/raw blocks that disturb the offset history,
* and replaces any repcodes within the seqStore that may be invalid.
*
* dRepcodes are updated as would be on the decompression side. cRepcodes are updated exactly in
* accordance with the seqStore.
* dRepcodes are updated as would be on the decompression side.
* cRepcodes are updated exactly in accordance with the seqStore.
*
* Note : this function assumes seq->offBase respects the following numbering scheme :
* 0 : invalid
* 1-3 : repcode 1-3
* 4+ : real_offset+3
*/
static void ZSTD_seqStore_resolveOffCodes(repcodes_t* const dRepcodes, repcodes_t* const cRepcodes,
seqStore_t* const seqStore, U32 const nbSeq) {
@@ -3461,9 +3466,9 @@ static void ZSTD_seqStore_resolveOffCodes(repcodes_t* const dRepcodes, repcodes_
for (; idx < nbSeq; ++idx) {
seqDef* const seq = seqStore->sequencesStart + idx;
U32 const ll0 = (seq->litLength == 0);
U32 offCode = seq->offBase - 1;
U32 const offCode = seq->offBase - 1;
assert(seq->offBase > 0);
if (offCode <= ZSTD_REP_MOVE) {
if (offCode < ZSTD_REP_NUM) {
U32 const dRawOffset = ZSTD_resolveRepcodeToRawOffset(dRepcodes->rep, offCode, ll0);
U32 const cRawOffset = ZSTD_resolveRepcodeToRawOffset(cRepcodes->rep, offCode, ll0);
/* Adjust simulated decompression repcode history if we come across a mismatch. Replace
@@ -5738,39 +5743,39 @@ typedef struct {
size_t posInSrc; /* Number of bytes given by sequences provided so far */
} ZSTD_sequencePosition;
/* Returns a ZSTD error code if sequence is not valid */
static size_t ZSTD_validateSequence(U32 offCode, U32 matchLength,
size_t posInSrc, U32 windowLog, size_t dictSize, U32 minMatch) {
size_t offsetBound;
U32 windowSize = 1 << windowLog;
/* ZSTD_validateSequence() :
* @offCode : is presumed to follow format required by ZSTD_storeSeq()
* @returns a ZSTD error code if sequence is not valid
*/
static size_t
ZSTD_validateSequence(U32 offCode, U32 matchLength,
size_t posInSrc, U32 windowLog, size_t dictSize)
{
U32 const windowSize = 1 << windowLog;
/* posInSrc represents the amount of data the the decoder would decode up to this point.
* As long as the amount of data decoded is less than or equal to window size, offsets may be
* larger than the total length of output decoded in order to reference the dict, even larger than
* window size. After output surpasses windowSize, we're limited to windowSize offsets again.
*/
offsetBound = posInSrc > windowSize ? (size_t)windowSize : posInSrc + (size_t)dictSize;
RETURN_ERROR_IF(offCode > offsetBound + ZSTD_REP_MOVE, corruption_detected, "Offset too large!");
RETURN_ERROR_IF(matchLength < minMatch, corruption_detected, "Matchlength too small");
size_t const offsetBound = posInSrc > windowSize ? (size_t)windowSize : posInSrc + (size_t)dictSize;
RETURN_ERROR_IF(offCode > STORE_OFFSET(offsetBound), corruption_detected, "Offset too large!");
RETURN_ERROR_IF(matchLength < MINMATCH, corruption_detected, "Matchlength too small");
return 0;
}
/* Returns an offset code, given a sequence's raw offset, the ongoing repcode array, and whether litLength == 0 */
static U32 ZSTD_finalizeOffCode(U32 rawOffset, const U32 rep[ZSTD_REP_NUM], U32 ll0) {
U32 offCode = rawOffset + ZSTD_REP_MOVE;
U32 repCode = 0;
static U32 ZSTD_finalizeOffCode(U32 rawOffset, const U32 rep[ZSTD_REP_NUM], U32 ll0)
{
U32 offCode = STORE_OFFSET(rawOffset);
if (!ll0 && rawOffset == rep[0]) {
repCode = 1;
offCode = STORE_REPCODE_1;
} else if (rawOffset == rep[1]) {
repCode = 2 - ll0;
offCode = STORE_REPCODE(2 - ll0);
} else if (rawOffset == rep[2]) {
repCode = 3 - ll0;
offCode = STORE_REPCODE(3 - ll0);
} else if (ll0 && rawOffset == rep[0] - 1) {
repCode = 3;
}
if (repCode) {
/* ZSTD_storeSeq expects a number in the range [0, 2] to represent a repcode */
offCode = repCode - 1;
offCode = STORE_REPCODE_3;
}
return offCode;
}
@@ -5778,18 +5783,17 @@ static U32 ZSTD_finalizeOffCode(U32 rawOffset, const U32 rep[ZSTD_REP_NUM], U32
/* Returns 0 on success, and a ZSTD_error otherwise. This function scans through an array of
* ZSTD_Sequence, storing the sequences it finds, until it reaches a block delimiter.
*/
static size_t ZSTD_copySequencesToSeqStoreExplicitBlockDelim(ZSTD_CCtx* cctx, ZSTD_sequencePosition* seqPos,
const ZSTD_Sequence* const inSeqs, size_t inSeqsSize,
const void* src, size_t blockSize) {
static size_t
ZSTD_copySequencesToSeqStoreExplicitBlockDelim(ZSTD_CCtx* cctx,
ZSTD_sequencePosition* seqPos,
const ZSTD_Sequence* const inSeqs, size_t inSeqsSize,
const void* src, size_t blockSize)
{
U32 idx = seqPos->idx;
BYTE const* ip = (BYTE const*)(src);
const BYTE* const iend = ip + blockSize;
repcodes_t updatedRepcodes;
U32 dictSize;
U32 litLength;
U32 matchLength;
U32 ll0;
U32 offCode;
if (cctx->cdict) {
dictSize = (U32)cctx->cdict->dictContentSize;
@@ -5800,18 +5804,17 @@ static size_t ZSTD_copySequencesToSeqStoreExplicitBlockDelim(ZSTD_CCtx* cctx, ZS
}
ZSTD_memcpy(updatedRepcodes.rep, cctx->blockState.prevCBlock->rep, sizeof(repcodes_t));
for (; (inSeqs[idx].matchLength != 0 || inSeqs[idx].offset != 0) && idx < inSeqsSize; ++idx) {
litLength = inSeqs[idx].litLength;
matchLength = inSeqs[idx].matchLength;
ll0 = litLength == 0;
offCode = ZSTD_finalizeOffCode(inSeqs[idx].offset, updatedRepcodes.rep, ll0);
U32 const litLength = inSeqs[idx].litLength;
U32 const ll0 = (litLength == 0);
U32 const matchLength = inSeqs[idx].matchLength;
U32 const offCode = ZSTD_finalizeOffCode(inSeqs[idx].offset, updatedRepcodes.rep, ll0);
updatedRepcodes = ZSTD_updateRep(updatedRepcodes.rep, offCode, ll0);
DEBUGLOG(6, "Storing sequence: (of: %u, ml: %u, ll: %u)", offCode, matchLength, litLength);
if (cctx->appliedParams.validateSequences) {
seqPos->posInSrc += litLength + matchLength;
FORWARD_IF_ERROR(ZSTD_validateSequence(offCode, matchLength, seqPos->posInSrc,
cctx->appliedParams.cParams.windowLog, dictSize,
cctx->appliedParams.cParams.minMatch),
cctx->appliedParams.cParams.windowLog, dictSize),
"Sequence validation failed");
}
RETURN_ERROR_IF(idx - seqPos->idx > cctx->seqStore.maxNbSeq, memory_allocation,
@@ -5843,9 +5846,11 @@ static size_t ZSTD_copySequencesToSeqStoreExplicitBlockDelim(ZSTD_CCtx* cctx, ZS
* avoid splitting a match, or to avoid splitting a match such that it would produce a match
* smaller than MINMATCH. In this case, we return the number of bytes that we didn't read from this block.
*/
static size_t ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_sequencePosition* seqPos,
const ZSTD_Sequence* const inSeqs, size_t inSeqsSize,
const void* src, size_t blockSize) {
static size_t
ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_sequencePosition* seqPos,
const ZSTD_Sequence* const inSeqs, size_t inSeqsSize,
const void* src, size_t blockSize)
{
U32 idx = seqPos->idx;
U32 startPosInSequence = seqPos->posInSequence;
U32 endPosInSequence = seqPos->posInSequence + (U32)blockSize;
@@ -5855,10 +5860,6 @@ static size_t ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_seq
repcodes_t updatedRepcodes;
U32 bytesAdjustment = 0;
U32 finalMatchSplit = 0;
U32 litLength;
U32 matchLength;
U32 rawOffset;
U32 offCode;
if (cctx->cdict) {
dictSize = cctx->cdict->dictContentSize;
@@ -5872,9 +5873,10 @@ static size_t ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_seq
ZSTD_memcpy(updatedRepcodes.rep, cctx->blockState.prevCBlock->rep, sizeof(repcodes_t));
while (endPosInSequence && idx < inSeqsSize && !finalMatchSplit) {
const ZSTD_Sequence currSeq = inSeqs[idx];
litLength = currSeq.litLength;
matchLength = currSeq.matchLength;
rawOffset = currSeq.offset;
U32 litLength = currSeq.litLength;
U32 matchLength = currSeq.matchLength;
U32 const rawOffset = currSeq.offset;
U32 offCode;
/* Modify the sequence depending on where endPosInSequence lies */
if (endPosInSequence >= currSeq.litLength + currSeq.matchLength) {
@@ -5927,7 +5929,7 @@ static size_t ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_seq
}
}
/* Check if this offset can be represented with a repcode */
{ U32 ll0 = (litLength == 0);
{ U32 const ll0 = (litLength == 0);
offCode = ZSTD_finalizeOffCode(rawOffset, updatedRepcodes.rep, ll0);
updatedRepcodes = ZSTD_updateRep(updatedRepcodes.rep, offCode, ll0);
}
@@ -5935,8 +5937,7 @@ static size_t ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_seq
if (cctx->appliedParams.validateSequences) {
seqPos->posInSrc += litLength + matchLength;
FORWARD_IF_ERROR(ZSTD_validateSequence(offCode, matchLength, seqPos->posInSrc,
cctx->appliedParams.cParams.windowLog, dictSize,
cctx->appliedParams.cParams.minMatch),
cctx->appliedParams.cParams.windowLog, dictSize),
"Sequence validation failed");
}
DEBUGLOG(6, "Storing sequence: (of: %u, ml: %u, ll: %u)", offCode, matchLength, litLength);
@@ -5967,7 +5968,8 @@ static size_t ZSTD_copySequencesToSeqStoreNoBlockDelim(ZSTD_CCtx* cctx, ZSTD_seq
typedef size_t (*ZSTD_sequenceCopier) (ZSTD_CCtx* cctx, ZSTD_sequencePosition* seqPos,
const ZSTD_Sequence* const inSeqs, size_t inSeqsSize,
const void* src, size_t blockSize);
static ZSTD_sequenceCopier ZSTD_selectSequenceCopier(ZSTD_sequenceFormat_e mode) {
static ZSTD_sequenceCopier ZSTD_selectSequenceCopier(ZSTD_sequenceFormat_e mode)
{
ZSTD_sequenceCopier sequenceCopier = NULL;
assert(ZSTD_cParam_withinBounds(ZSTD_c_blockDelimiters, mode));
if (mode == ZSTD_sf_explicitBlockDelimiters) {
@@ -5981,12 +5983,15 @@ static ZSTD_sequenceCopier ZSTD_selectSequenceCopier(ZSTD_sequenceFormat_e mode)
/* Compress, block-by-block, all of the sequences given.
*
* Returns the cumulative size of all compressed blocks (including their headers), otherwise a ZSTD error.
* Returns the cumulative size of all compressed blocks (including their headers),
* otherwise a ZSTD error.
*/
static size_t ZSTD_compressSequences_internal(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const ZSTD_Sequence* inSeqs, size_t inSeqsSize,
const void* src, size_t srcSize) {
static size_t
ZSTD_compressSequences_internal(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const ZSTD_Sequence* inSeqs, size_t inSeqsSize,
const void* src, size_t srcSize)
{
size_t cSize = 0;
U32 lastBlock;
size_t blockSize;
@@ -5996,7 +6001,7 @@ static size_t ZSTD_compressSequences_internal(ZSTD_CCtx* cctx,
BYTE const* ip = (BYTE const*)src;
BYTE* op = (BYTE*)dst;
ZSTD_sequenceCopier sequenceCopier = ZSTD_selectSequenceCopier(cctx->appliedParams.blockDelimiters);
ZSTD_sequenceCopier const sequenceCopier = ZSTD_selectSequenceCopier(cctx->appliedParams.blockDelimiters);
DEBUGLOG(4, "ZSTD_compressSequences_internal srcSize: %zu, inSeqsSize: %zu", srcSize, inSeqsSize);
/* Special case: empty frame */
@@ -6096,7 +6101,8 @@ static size_t ZSTD_compressSequences_internal(ZSTD_CCtx* cctx,
size_t ZSTD_compressSequences(ZSTD_CCtx* const cctx, void* dst, size_t dstCapacity,
const ZSTD_Sequence* inSeqs, size_t inSeqsSize,
const void* src, size_t srcSize) {
const void* src, size_t srcSize)
{
BYTE* op = (BYTE*)dst;
size_t cSize = 0;
size_t compressedBlocksSize = 0;