From: Elliot Gorokhovsky Date: Thu, 17 Mar 2022 16:35:11 +0000 (-0700) Subject: Software pipeline for ZSTD_compressBlock_fast_dictMatchState (#3086) X-Git-Tag: v1.5.4^2~225 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=64efba4c5ee1e8c9afe92873f79424c9955b82ba;p=thirdparty%2Fzstd.git Software pipeline for ZSTD_compressBlock_fast_dictMatchState (#3086) * prefetch dict content inside loop * ip0/ip1 pipeline * add L2_4 prefetch to dms pipeline * Remove L1 prefetch * Remove L2 prefetching * Reduce # of gotos * Cosmetic fixes * Check final position sometimes * Track step size as in bc768bc * Fix nits --- diff --git a/lib/compress/zstd_fast.c b/lib/compress/zstd_fast.c index 62c4c2cea..5da108c62 100644 --- a/lib/compress/zstd_fast.c +++ b/lib/compress/zstd_fast.c @@ -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; @@ -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 */ @@ -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); + const size_t dictHash0 = ZSTD_hashPtr(ip0, dictHLog, mls); + U32 dictMatchIndex = dictHashTable[dictHash0]; + 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; + const U32 repIndex = curr + 1 - offset_1; + const BYTE* repMatch = (repIndex < prefixStartIndex) ? + dictBase + (repIndex - dictIndexDelta) : + base + repIndex; + const size_t hash1 = ZSTD_hashPtr(ip1, hlog, mls); + const size_t dictHash1 = ZSTD_hashPtr(ip1, dictHLog, mls); + 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; + 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[dictHash1]; + 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; + } /* end inner search loop */ /* match found */ - ip += mLength; - anchor = ip; + assert(mLength); + 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; } +_cleanup: /* save reps for next block */ rep[0] = offset_1 ? offset_1 : offsetSaved; rep[1] = offset_2 ? offset_2 : offsetSaved;