Store Key in Accumulator Cache

Description

Store the position key in the accumulator cache entries and skip other checks if a matching key is found.

Branches

• 38e0cc7b-2

Tests

Test #1

Stockfish Testing Framework

Result

Stopped

Stats

LLR: -1.25 (-2.94,2.94) <0.00,2.00>
Total: 135040 W: 34991 L: 34905 D: 65144
Ptnml(0-2): 438, 15341, 35859, 15461, 421

The hit rate of pos.key() == entry.key was approx. 1% in default bench (depth 14). Test result indicates that It is not enough to compensate the additional comparison overhead.

Test #2

Stockfish Testing Framework

Result

Failed

Stats

LLR: -2.93 (-2.94,2.94) <0.00,2.00>
Total: 78656 W: 20301 L: 20443 D: 37912
Ptnml(0-2): 260, 8896, 21169, 8732, 271

Instead of storing a key in cache entries, skip checks and return early if removed and added are both empty.