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Shrink Pipeline from 4 Positions to 3

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This commit is contained in:
W. Felix Handte 2021-08-18 13:44:27 -04:00
parent 387840af79
commit b092dd75b7
1 changed files with 10 additions and 32 deletions
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42
lib/compress/zstd_fast.c
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@ -247,7 +247,6 @@ ZSTD_compressBlock_fast_generic_pipelined(
const BYTE* ip0 = istart; const BYTE* ip0 = istart;
const BYTE* ip1; const BYTE* ip1;
const BYTE* ip2; const BYTE* ip2;
const BYTE* ip3;
U32 current0; U32 current0;
U32 rep_offset1 = rep[0]; U32 rep_offset1 = rep[0];
@ -257,12 +256,9 @@ ZSTD_compressBlock_fast_generic_pipelined(
size_t hash0; /* hash for ip0 */ size_t hash0; /* hash for ip0 */
size_t hash1; /* hash for ip1 */ size_t hash1; /* hash for ip1 */
size_t hash2; /* hash for ip2 */ size_t hash2; /* hash for ip2 */
size_t hash3; /* hash for ip3 */
U32 idx0; /* match idx for ip0 */ U32 idx0; /* match idx for ip0 */
U32 idx1; /* match idx for ip1 */ U32 idx1; /* match idx for ip1 */
U32 idx2; /* match idx for ip2 */
U32 mval; /* src value at match idx */ U32 mval; /* src value at match idx */
U32 rval; /* src value at ip2 - repcode */
U32 offcode; U32 offcode;
const BYTE* match0; const BYTE* match0;
@ -290,32 +286,20 @@ _start: /* Requires: ip0 */
/* calculate positions, ip0 - anchor == 0, so we skip step calc */ /* calculate positions, ip0 - anchor == 0, so we skip step calc */
ip1 = ip0 + stepSize; ip1 = ip0 + stepSize;
ip2 = ip1 + stepSize; ip2 = ip1 + stepSize;
ip3 = ip2 + stepSize;
if (ip3 >= ilimit) { if (ip2 >= ilimit) {
goto _cleanup; goto _cleanup;
} }
hash0 = ZSTD_hashPtr(ip0, hlog, mls); hash0 = ZSTD_hashPtr(ip0, hlog, mls);
hash1 = ZSTD_hashPtr(ip1, hlog, mls); hash1 = ZSTD_hashPtr(ip1, hlog, mls);
hash2 = ZSTD_hashPtr(ip2, hlog, mls);
idx0 = hashTable[hash0]; idx0 = hashTable[hash0];
idx1 = hashTable[hash1];
if (idx0 >= prefixStartIndex) {
mval = MEM_read32(base + idx0);
} else {
mval = MEM_read32(ip0) ^ 1;
}
rval = MEM_read32(ip2 - rep_offset1);
do { do {
const U32 rval = MEM_read32(ip2 - rep_offset1);
current0 = ip0 - base; current0 = ip0 - base;
// DEBUGLOG(5, "Searching ip0 = %u", (U32)(ip0 - istart));
/* write back hash table entry */ /* write back hash table entry */
hashTable[hash0] = current0; hashTable[hash0] = current0;
@ -331,7 +315,7 @@ _start: /* Requires: ip0 */
goto _match; goto _match;
} }
/* load match for ip[1] */ /* load match for ip[0] */
if (idx0 >= prefixStartIndex) { if (idx0 >= prefixStartIndex) {
mval = MEM_read32(base + idx0); mval = MEM_read32(base + idx0);
} else { } else {
@ -344,35 +328,29 @@ _start: /* Requires: ip0 */
goto _offset; goto _offset;
} }
/* hash ip[3] */ /* hash ip[2] */
hash3 = ZSTD_hashPtr(ip3, hlog, mls); hash2 = ZSTD_hashPtr(ip2, hlog, mls);
/* lookup ip[2] */ /* lookup ip[1] */
idx2 = hashTable[hash2]; idx1 = hashTable[hash1];
/* load next rval */
rval = MEM_read32(ip3 - rep_offset1);
/* advance to next positions */ /* advance to next positions */
{ {
if (ip2 >= nextStep) { if (ip1 >= nextStep) {
step++; step++;
nextStep += kStepIncr; nextStep += kStepIncr;
} }
idx0 = idx1; idx0 = idx1;
idx1 = idx2;
hash0 = hash1; hash0 = hash1;
hash1 = hash2; hash1 = hash2;
hash2 = hash3;
ip0 = ip1; ip0 = ip1;
ip1 = ip2; ip1 = ip2;
ip2 = ip3; ip2 = ip2 + step;
ip3 = ip3 + step;
} }
} while (ip3 < ilimit); } while (ip2 < ilimit);
_cleanup: _cleanup: