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Merge pull request #2112 from facebook/cfast

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small speed improvement for strategy fast
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Yann Collet 2020-05-07 13:13:34 -07:00 committed by GitHub
commit 1afe57cff7
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1 changed files with 20 additions and 21 deletions
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41
lib/compress/zstd_fast.c
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@ -81,9 +81,9 @@ ZSTD_compressBlock_fast_generic(
/* Main Search Loop */ /* Main Search Loop */
#ifdef __INTEL_COMPILER #ifdef __INTEL_COMPILER
/* From intel 'The vector pragma indicates that the loop should be /* From intel 'The vector pragma indicates that the loop should be
* vectorized if it is legal to do so'. Can be used together with * vectorized if it is legal to do so'. Can be used together with
* #pragma ivdep (but have opted to exclude that because intel * #pragma ivdep (but have opted to exclude that because intel
* warns against using it).*/ * warns against using it).*/
#pragma vector always #pragma vector always
#endif #endif
@ -98,7 +98,7 @@ ZSTD_compressBlock_fast_generic(
U32 const current1 = (U32)(ip1-base); U32 const current1 = (U32)(ip1-base);
U32 const matchIndex0 = hashTable[h0]; U32 const matchIndex0 = hashTable[h0];
U32 const matchIndex1 = hashTable[h1]; U32 const matchIndex1 = hashTable[h1];
BYTE const* repMatch = ip2-offset_1; BYTE const* repMatch = ip2 - offset_1;
const BYTE* match0 = base + matchIndex0; const BYTE* match0 = base + matchIndex0;
const BYTE* match1 = base + matchIndex1; const BYTE* match1 = base + matchIndex1;
U32 offcode; U32 offcode;
@ -113,9 +113,10 @@ ZSTD_compressBlock_fast_generic(
assert(ip0 + 1 == ip1); assert(ip0 + 1 == ip1);
if ((offset_1 > 0) & (MEM_read32(repMatch) == MEM_read32(ip2))) { if ((offset_1 > 0) & (MEM_read32(repMatch) == MEM_read32(ip2))) {
mLength = ip2[-1] == repMatch[-1] ? 1 : 0; mLength = (ip2[-1] == repMatch[-1]) ? 1 : 0;
ip0 = ip2 - mLength; ip0 = ip2 - mLength;
match0 = repMatch - mLength; match0 = repMatch - mLength;
mLength += 4;
offcode = 0; offcode = 0;
goto _match; goto _match;
} }
@ -140,19 +141,18 @@ _offset: /* Requires: ip0, match0 */
offset_2 = offset_1; offset_2 = offset_1;
offset_1 = (U32)(ip0-match0); offset_1 = (U32)(ip0-match0);
offcode = offset_1 + ZSTD_REP_MOVE; offcode = offset_1 + ZSTD_REP_MOVE;
mLength = 0; mLength = 4;
/* Count the backwards match length */ /* Count the backwards match length */
while (((ip0>anchor) & (match0>prefixStart)) while (((ip0>anchor) & (match0>prefixStart))
&& (ip0[-1] == match0[-1])) { ip0--; match0--; mLength++; } /* catch up */ && (ip0[-1] == match0[-1])) { ip0--; match0--; mLength++; } /* catch up */
_match: /* Requires: ip0, match0, offcode */ _match: /* Requires: ip0, match0, offcode */
/* Count the forward length */ /* Count the forward length */
mLength += ZSTD_count(ip0+mLength+4, match0+mLength+4, iend) + 4; mLength += ZSTD_count(ip0+mLength, match0+mLength, iend);
ZSTD_storeSeq(seqStore, (size_t)(ip0-anchor), anchor, iend, offcode, mLength-MINMATCH); ZSTD_storeSeq(seqStore, (size_t)(ip0-anchor), anchor, iend, offcode, mLength-MINMATCH);
/* match found */ /* match found */
ip0 += mLength; ip0 += mLength;
anchor = ip0; anchor = ip0;
ip1 = ip0 + 1;
if (ip0 <= ilimit) { if (ip0 <= ilimit) {
/* Fill Table */ /* Fill Table */
@ -160,19 +160,18 @@ _match: /* Requires: ip0, match0, offcode */
hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2; /* here because current+2 could be > iend-8 */ hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2; /* here because current+2 could be > iend-8 */
hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base); hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base);
while ( ((ip0 <= ilimit) & (offset_2>0)) /* offset_2==0 means offset_2 is invalidated */ if (offset_2 > 0) { /* offset_2==0 means offset_2 is invalidated */
&& (MEM_read32(ip0) == MEM_read32(ip0 - offset_2)) ) { while ( (ip0 <= ilimit) && (MEM_read32(ip0) == MEM_read32(ip0 - offset_2)) ) {
/* store sequence */ /* store sequence */
size_t const rLength = ZSTD_count(ip0+4, ip0+4-offset_2, iend) + 4; size_t const rLength = ZSTD_count(ip0+4, ip0+4-offset_2, iend) + 4;
{ U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; } /* swap offset_2 <=> offset_1 */ { U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; } /* swap offset_2 <=> offset_1 */
hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base); hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base);
ip0 += rLength; ip0 += rLength;
ip1 = ip0 + 1; ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, 0 /*offCode*/, rLength-MINMATCH);
ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, 0 /*offCode*/, rLength-MINMATCH); anchor = ip0;
anchor = ip0; continue; /* faster when present (confirmed on gcc-8) ... (?) */
continue; /* faster when present (confirmed on gcc-8) ... (?) */ } } }
} ip1 = ip0 + 1;
}
} }
/* save reps for next block */ /* save reps for next block */