Credits to Stefan Geschwentner (locutus2) showing that the hint
is useful on PvNodes. In contrast to his test,
this version avoids to use the hint when in check.
I believe checking positions aren't good candidates for the hint
because:
- evasion moves are rather few, so a checking pos. has much less childs
than a normal position
- if the king has to move the NNUE eval can't use incremental updates,
so the child nodes have to do a full refresh anyway.
Passed STC:
https://tests.stockfishchess.org/tests/view/
63f9c5b1e74a12625bcdf585
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 124472 W: 33268 L: 32846 D: 58358
Ptnml(0-2): 350, 12986, 35170, 13352, 378
closes https://github.com/official-stockfish/Stockfish/pull/4410
no functional change
if (eval == VALUE_NONE)
ss->staticEval = eval = evaluate(pos, &complexity);
else // Fall back to (semi)classical complexity for TT hits, the NNUE complexity is lost
+ {
complexity = abs(ss->staticEval - pos.psq_eg_stm());
+ if (PvNode)
+ Eval::NNUE::hint_common_parent_position(pos);
+ }
// ttValue can be used as a better position evaluation (~7 Elo)
if ( ttValue != VALUE_NONE