Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Software pipeline for ZSTD_compressBlock_fast_dictMatchState (+5-6% compression speed) #3086

Merged
merged 10 commits into from
Mar 17, 2022
Merged

Software pipeline for ZSTD_compressBlock_fast_dictMatchState (+5-6% compression speed) #3086

Changes from 9 commits
Commits
Show all changes
10 commits
Select commit Hold shift + click to select a range
bd4b2c0
prefetch dict content inside loop
embg Feb 23, 2022
744f7c1
ip0/ip1 pipeline
embg Feb 28, 2022
ef1949f
add L2_4 prefetch to dms pipeline
embg Mar 1, 2022
c0a306b
Remove L1 prefetch
embg Mar 2, 2022
6f6de06
Remove L2 prefetching
embg Mar 2, 2022
ced6f72
Reduce # of gotos
embg Mar 2, 2022
af68080
Cosmetic fixes
embg Mar 4, 2022
6cba817
Check final position sometimes
embg Mar 9, 2022
b4f9a3f
Track step size as in bc768bc
embg Mar 10, 2022
201f0e2
Fix nits
embg Mar 10, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
162 changes: 98 additions & 64 deletions lib/compress/zstd_fast.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -380,7 +380,8 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(
U32 const stepSize = cParams->targetLength + !(cParams->targetLength);
const BYTE* const base = ms->window.base;
const BYTE* const istart = (const BYTE*)src;
const BYTE* ip = istart;
const BYTE* ip0 = istart;
const BYTE* ip1 = ip0 + stepSize; /* we assert below that stepSize >= 1 */
const BYTE* anchor = istart;
const U32 prefixStartIndex = ms->window.dictLimit;
const BYTE* const prefixStart = base + prefixStartIndex;
Expand All @@ -397,13 +398,13 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(
const BYTE* const dictStart = dictBase + dictStartIndex;
const BYTE* const dictEnd = dms->window.nextSrc;
const U32 dictIndexDelta = prefixStartIndex - (U32)(dictEnd - dictBase);
const U32 dictAndPrefixLength = (U32)(ip - prefixStart + dictEnd - dictStart);
const U32 dictAndPrefixLength = (U32)(istart - prefixStart + dictEnd - dictStart);
const U32 dictHLog = dictCParams->hashLog;

/* if a dictionary is still attached, it necessarily means that
* it is within window size. So we just check it. */
const U32 maxDistance = 1U << cParams->windowLog;
const U32 endIndex = (U32)((size_t)(ip - base) + srcSize);
const U32 endIndex = (U32)((size_t)(istart - base) + srcSize);
assert(endIndex - prefixStartIndex <= maxDistance);
(void)maxDistance; (void)endIndex; /* these variables are not used when assert() is disabled */

Expand All @@ -415,101 +416,134 @@ size_t ZSTD_compressBlock_fast_dictMatchState_generic(

/* init */
DEBUGLOG(5, "ZSTD_compressBlock_fast_dictMatchState_generic");
ip += (dictAndPrefixLength == 0);
ip0 += (dictAndPrefixLength == 0);
/* dictMatchState repCode checks don't currently handle repCode == 0
* disabling. */
assert(offset_1 <= dictAndPrefixLength);
assert(offset_2 <= dictAndPrefixLength);

/* Main Search Loop */
while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
/* Outer search loop */
assert(stepSize >= 1);
while (ip1 <= ilimit) { /* repcode check at (ip0 + 1) is safe because ip0 < ip1 */
size_t mLength;
size_t const h = ZSTD_hashPtr(ip, hlog, mls);
U32 const curr = (U32)(ip-base);
U32 const matchIndex = hashTable[h];
const BYTE* match = base + matchIndex;
const U32 repIndex = curr + 1 - offset_1;
const BYTE* repMatch = (repIndex < prefixStartIndex) ?
dictBase + (repIndex - dictIndexDelta) :
base + repIndex;
hashTable[h] = curr; /* update hash table */

if ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */
&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
ip++;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, REPCODE1_TO_OFFBASE, mLength);
} else if ( (matchIndex <= prefixStartIndex) ) {
size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls);
U32 const dictMatchIndex = dictHashTable[dictHash];
const BYTE* dictMatch = dictBase + dictMatchIndex;
if (dictMatchIndex <= dictStartIndex ||
MEM_read32(dictMatch) != MEM_read32(ip)) {
assert(stepSize >= 1);
ip += ((ip-anchor) >> kSearchStrength) + stepSize;
continue;
} else {
/* found a dict match */
U32 const offset = (U32)(curr-dictMatchIndex-dictIndexDelta);
mLength = ZSTD_count_2segments(ip+4, dictMatch+4, iend, dictEnd, prefixStart) + 4;
while (((ip>anchor) & (dictMatch>dictStart))
&& (ip[-1] == dictMatch[-1])) {
ip--; dictMatch--; mLength++;
size_t hash0 = ZSTD_hashPtr(ip0, hlog, mls);
size_t dictHash = ZSTD_hashPtr(ip0, dictHLog, mls);
embg marked this conversation as resolved.
Show resolved Hide resolved
U32 dictMatchIndex = dictHashTable[dictHash];
U32 matchIndex = hashTable[hash0];
U32 curr = (U32)(ip0 - base);
size_t step = stepSize;
const size_t kStepIncr = 1 << kSearchStrength;
const BYTE* nextStep = ip0 + kStepIncr;

/* Inner search loop */
while (1) {
const BYTE *match = base + matchIndex;
embg marked this conversation as resolved.
Show resolved Hide resolved
const U32 repIndex = curr + 1 - offset_1;
const BYTE *repMatch = (repIndex < prefixStartIndex) ?
dictBase + (repIndex - dictIndexDelta) :
base + repIndex;
size_t hash1 = ZSTD_hashPtr(ip1, hlog, mls);
embg marked this conversation as resolved.
Show resolved Hide resolved
dictHash = ZSTD_hashPtr(ip1, dictHLog, mls);
embg marked this conversation as resolved.
Show resolved Hide resolved
embg marked this conversation as resolved.
Show resolved Hide resolved
hashTable[hash0] = curr; /* update hash table */

if (((U32) ((prefixStartIndex - 1) - repIndex) >=
3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */
&& (MEM_read32(repMatch) == MEM_read32(ip0 + 1))) {
const BYTE *const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
mLength = ZSTD_count_2segments(ip0 + 1 + 4, repMatch + 4, iend, repMatchEnd, prefixStart) + 4;
embg marked this conversation as resolved.
Show resolved Hide resolved
ip0++;
ZSTD_storeSeq(seqStore, (size_t) (ip0 - anchor), anchor, iend, REPCODE1_TO_OFFBASE, mLength);
break;
} else if (matchIndex <= prefixStartIndex) {
/* We only look for a dict match if the normal matchIndex is invalid */
const BYTE *dictMatch = dictBase + dictMatchIndex;
if (dictMatchIndex > dictStartIndex &&
MEM_read32(dictMatch) == MEM_read32(ip0)) {
/* found a dict match */
U32 const offset = (U32) (curr - dictMatchIndex - dictIndexDelta);
mLength = ZSTD_count_2segments(ip0 + 4, dictMatch + 4, iend, dictEnd, prefixStart) + 4;
while (((ip0 > anchor) & (dictMatch > dictStart))
&& (ip0[-1] == dictMatch[-1])) {
ip0--;
dictMatch--;
mLength++;
} /* catch up */
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t) (ip0 - anchor), anchor, iend, OFFSET_TO_OFFBASE(offset), mLength);
break;
}
} else if (MEM_read32(match) == MEM_read32(ip0)) {
/* found a regular match */
U32 const offset = (U32) (ip0 - match);
mLength = ZSTD_count(ip0 + 4, match + 4, iend) + 4;
while (((ip0 > anchor) & (match > prefixStart))
&& (ip0[-1] == match[-1])) {
ip0--;
match--;
mLength++;
} /* catch up */
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, OFFSET_TO_OFFBASE(offset), mLength);
ZSTD_storeSeq(seqStore, (size_t) (ip0 - anchor), anchor, iend, OFFSET_TO_OFFBASE(offset), mLength);
break;
}
} else if (MEM_read32(match) != MEM_read32(ip)) {
/* it's not a match, and we're not going to check the dictionary */
assert(stepSize >= 1);
ip += ((ip-anchor) >> kSearchStrength) + stepSize;
continue;
} else {
/* found a regular match */
U32 const offset = (U32)(ip-match);
mLength = ZSTD_count(ip+4, match+4, iend) + 4;
while (((ip>anchor) & (match>prefixStart))
&& (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
offset_2 = offset_1;
offset_1 = offset;
ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, OFFSET_TO_OFFBASE(offset), mLength);

/* Prepare for next iteration */
dictMatchIndex = dictHashTable[dictHash];
matchIndex = hashTable[hash1];

if (ip1 >= nextStep) {
step++;
nextStep += kStepIncr;
}
ip0 = ip1;
ip1 = ip1 + step;
if (ip1 > ilimit) goto _cleanup;

curr = (U32)(ip0 - base);
hash0 = hash1;
}
embg marked this conversation as resolved.
Show resolved Hide resolved

/* match found */
ip += mLength;
anchor = ip;
assert(mLength);
embg marked this conversation as resolved.
Show resolved Hide resolved
ip0 += mLength;
anchor = ip0;

if (ip <= ilimit) {
if (ip0 <= ilimit) {
/* Fill Table */
assert(base+curr+2 > istart); /* check base overflow */
hashTable[ZSTD_hashPtr(base+curr+2, hlog, mls)] = curr+2; /* here because curr+2 could be > iend-8 */
hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);
hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base);

/* check immediate repcode */
while (ip <= ilimit) {
U32 const current2 = (U32)(ip-base);
while (ip0 <= ilimit) {
U32 const current2 = (U32)(ip0-base);
U32 const repIndex2 = current2 - offset_2;
const BYTE* repMatch2 = repIndex2 < prefixStartIndex ?
dictBase - dictIndexDelta + repIndex2 :
base + repIndex2;
if ( ((U32)((prefixStartIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)
&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
&& (MEM_read32(repMatch2) == MEM_read32(ip0))) {
const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
size_t const repLength2 = ZSTD_count_2segments(ip0+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, repLength2);
hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
ip += repLength2;
anchor = ip;
hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = current2;
ip0 += repLength2;
anchor = ip0;
continue;
}
break;
}
}

/* Prepare for next iteration */
assert(ip0 == anchor);
ip1 = ip0 + stepSize;
embg marked this conversation as resolved.
Show resolved Hide resolved
}

_cleanup:
/* save reps for next block */
rep[0] = offset_1 ? offset_1 : offsetSaved;
rep[1] = offset_2 ? offset_2 : offsetSaved;
Expand Down