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[HUF] Improve Huffman encoding speed

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Improve Huffman encoding speed by 20% for gcc and 10% for clang.

| Compiler |     Benchmark     | Config  |   Dataset   | Ratio | Speed MB/s (dev) | Speed MB/s (huf-cspeed) | Speed MB/s (huf-cspeed - dev) |
|----------|-------------------|---------|-------------|-------|------------------|-------------------------|-------------------------------|
| gcc      | compress          | level_1 | enwik7      | 2.43  | 253.70           | 258.72                  | 2.0%                          |
| gcc      | compress          | level_1 | silesia     | 2.88  | 341.90           | 348.15                  | 1.8%                          |
| gcc      | compress_literals | level_1 | enwik7      | 1.49  | 761.83           | 912.76                  | 19.8%                         |
| gcc      | compress_literals | level_1 | silesia     | 1.28  | 754.83           | 902.37                  | 19.5%                         |
| gcc      | compress_literals | level_7 | enwik7      | 1.29  | 502.81           | 552.79                  | 9.9%                          |
| gcc      | compress_literals | level_7 | silesia     | 1.11  | 675.97           | 776.44                  | 14.9%                         |
| clang    | compress          | level_1 | enwik7      | 2.43  | 277.54           | 280.98                  | 1.2%                          |
| clang    | compress          | level_1 | silesia     | 2.88  | 369.98           | 375.46                  | 1.5%                          |
| clang    | compress_literals | level_1 | enwik7      | 1.49  | 828.83           | 918.41                  | 10.8%                         |
| clang    | compress_literals | level_1 | silesia     | 1.28  | 815.81           | 905.41                  | 11.0%                         |
| clang    | compress_literals | level_7 | enwik7      | 1.29  | 533.13           | 553.30                  | 3.8%                          |
| clang    | compress_literals | level_7 | silesia     | 1.11  | 714.52           | 775.38                  | 8.5%                          |
This commit is contained in:
Nick Terrell
2021-07-27 15:10:35 -07:00
parent b3e372c171
commit 46f2710562
5 changed files with 382 additions and 88 deletions
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lib/compress/zstd_opt.c
+1 -1
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@@ -126,7 +126,7 @@ ZSTD_rescaleFreqs(optState_t* const optPtr,
optPtr->litSum = 0;
for (lit=0; lit<=MaxLit; lit++) {
U32 const scaleLog = 11; /* scale to 2K */
U32 const bitCost = HUF_getNbBits(optPtr->symbolCosts->huf.CTable, lit);
U32 const bitCost = HUF_getNbBitsFromCTable(optPtr->symbolCosts->huf.CTable, lit);
assert(bitCost <= scaleLog);
optPtr->litFreq[lit] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/;
optPtr->litSum += optPtr->litFreq[lit];