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Simplify condition for assigning static-eval based bonus

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for quiet move ordering and simplify bonus formula.

Due to clamping the bonus to relative low values the impact on high
depths is minimal, thus the restriction to low depths seems not
necessary.
Also the condition of movecount in previous node seems to be not
determinant.

Passed STC:
LLR: 2.95 (-2.94,2.94) {-1.25,0.25}
Total: 14600 W: 1424 L: 1323 D: 11853
Ptnml(0-2): 55, 1033, 5020, 1140, 52
https://tests.stockfishchess.org/tests/view/5fd67b381ac16912018885ec

Passed LTC:
LLR: 2.95 (-2.94,2.94) {-0.75,0.25}
Total: 85008 W: 3218 L: 3206 D: 78584
Ptnml(0-2): 49, 2840, 36700, 2880, 35
https://tests.stockfishchess.org/tests/view/5fd6af041ac16912018885f8

closes https://github.com/official-stockfish/Stockfish/pull/3265

bench: 4524994
This commit is contained in:
pb00067 2020-12-14 16:30:56 +01:00 • committed by Joost VandeVondele
parent 66a7a8a0cc
commit 1f3b5b8b54
1 changed files with 3 additions and 2 deletions
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5
src/search.cpp
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@ -815,9 +815,10 @@ namespace {
tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
}
if ((ss-1)->moveCount > 1 && is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture && depth < 7)
// Use static evaluation difference to improve quiet move ordering
if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture)
{
int bonus = std::clamp(- (depth+1) * 2 * int((ss-1)->staticEval + ss->staticEval - 2 * Tempo), -1000, 1000);
int bonus = std::clamp(-depth * 4 * int((ss-1)->staticEval + ss->staticEval - 2 * Tempo), -1000, 1000);
thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus;
}