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Use New Index Invariant to Simplify Conditionals
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2d598e6fed
commit
1a7b34ef28
@ -74,16 +74,18 @@ size_t ZSTD_compressBlock_fast_generic(
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const U32 dictIndexDelta = dictMode == ZSTD_dictMatchState ?
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const U32 dictIndexDelta = dictMode == ZSTD_dictMatchState ?
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localLowestIndex - (U32)(dictEnd - dictBase) :
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localLowestIndex - (U32)(dictEnd - dictBase) :
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0;
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0;
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ptrdiff_t dictLowestLocalIndex = dictMode == ZSTD_dictMatchState ?
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lowestDictIndex + dictIndexDelta :
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localLowestIndex;
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assert(dictMode == ZSTD_noDict || dictMode == ZSTD_dictMatchState);
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assert(dictMode == ZSTD_noDict || dictMode == ZSTD_dictMatchState);
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/* otherwise, we would get index underflow when translating a dict index
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* into a local index */
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assert(dictMode != ZSTD_dictMatchState
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|| localLowestIndex >= (U32)(dictEnd - dictBase));
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/* init */
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/* init */
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ip += (dictMode == ZSTD_noDict && ip == localLowest);
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ip += (dictMode == ZSTD_noDict && ip == localLowest);
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{ U32 const maxRep = dictMode == ZSTD_dictMatchState ?
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{ U32 const maxRep = dictMode == ZSTD_dictMatchState ?
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(U32)(ip - dictLowest) :
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(U32)(ip - localLowest + dictEnd - dictLowest) :
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(U32)(ip - localLowest);
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(U32)(ip - localLowest);
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if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
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if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
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if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
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if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
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@ -96,23 +98,22 @@ size_t ZSTD_compressBlock_fast_generic(
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U32 const current = (U32)(ip-base);
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U32 const current = (U32)(ip-base);
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U32 const matchIndex = hashTable[h];
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U32 const matchIndex = hashTable[h];
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const BYTE* match = base + matchIndex;
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const BYTE* match = base + matchIndex;
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const ptrdiff_t repIndex = (ptrdiff_t)current + 1 - offset_1;
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const U32 repIndex = current + 1 - offset_1;
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const BYTE* repBase = (dictMode == ZSTD_dictMatchState
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const BYTE* repBase = (dictMode == ZSTD_dictMatchState
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&& repIndex < (ptrdiff_t)localLowestIndex) ?
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&& repIndex < localLowestIndex) ?
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dictBase - dictIndexDelta : base;
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dictBase - dictIndexDelta : base;
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const BYTE* repMatch = repBase + repIndex;
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const BYTE* repMatch = repBase + repIndex;
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hashTable[h] = current; /* update hash table */
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hashTable[h] = current; /* update hash table */
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if (dictMode == ZSTD_dictMatchState
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if (dictMode == ZSTD_dictMatchState
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&& (((U32)((localLowestIndex-1) - repIndex) >= 3 /* intentional underflow */)
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&& ((U32)((localLowestIndex-1) - repIndex) >= 3 /* intentional underflow */)
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& (repIndex > dictLowestLocalIndex))
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&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
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&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
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const BYTE* repMatchEnd = repIndex < (ptrdiff_t)localLowestIndex ? dictEnd : iend;
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const BYTE* repMatchEnd = repIndex < localLowestIndex ? dictEnd : iend;
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mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, istart) + 4;
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mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, istart) + 4;
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ip++;
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ip++;
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ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
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ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
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} else if ( dictMode == ZSTD_noDict
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} else if ( dictMode == ZSTD_noDict
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&& (offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) {
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&& ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {
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mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
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mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
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ip++;
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ip++;
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ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
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ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
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@ -167,15 +168,14 @@ size_t ZSTD_compressBlock_fast_generic(
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if (dictMode == ZSTD_dictMatchState) {
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if (dictMode == ZSTD_dictMatchState) {
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while (ip <= ilimit) {
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while (ip <= ilimit) {
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U32 const current2 = (U32)(ip-base);
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U32 const current2 = (U32)(ip-base);
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ptrdiff_t const repIndex2 = (ptrdiff_t)current2 - offset_2;
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U32 const repIndex2 = current2 - offset_2;
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const BYTE* repMatch2 = dictMode == ZSTD_dictMatchState
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const BYTE* repMatch2 = dictMode == ZSTD_dictMatchState
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&& repIndex2 < (ptrdiff_t)localLowestIndex ?
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&& repIndex2 < localLowestIndex ?
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dictBase - dictIndexDelta + repIndex2 :
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dictBase - dictIndexDelta + repIndex2 :
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base + repIndex2;
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base + repIndex2;
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if ( (((U32)((localLowestIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)
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if ( ((U32)((localLowestIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)
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& (repIndex2 > dictLowestLocalIndex))
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&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
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&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
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const BYTE* const repEnd2 = repIndex2 < (ptrdiff_t)localLowestIndex ? dictEnd : iend;
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const BYTE* const repEnd2 = repIndex2 < localLowestIndex ? dictEnd : iend;
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size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, istart) + 4;
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size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, istart) + 4;
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U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
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U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
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ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
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ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
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@ -190,7 +190,6 @@ size_t ZSTD_compressBlock_fast_generic(
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if (dictMode == ZSTD_noDict) {
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if (dictMode == ZSTD_noDict) {
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while ( (ip <= ilimit)
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while ( (ip <= ilimit)
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&& (ip - offset_2 >= istart)
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&& ( (offset_2>0)
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&& ( (offset_2>0)
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& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
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& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
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/* store sequence */
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/* store sequence */
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