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Search Tune
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@PikaCat-OuO
PikaCat-OuO committed May 19, 2024
1 parent 9ae2831 commit 061f513
Showing 1 changed file with 56 additions and 56 deletions.
112 changes: 56 additions & 56 deletions src/search.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -51,14 +51,14 @@ using namespace Search;

namespace {

static constexpr double EvalLevel[10] = {0.981, 0.956, 0.895, 0.949, 0.913,
0.942, 0.933, 0.890, 0.984, 0.941};
static constexpr double EvalLevel[10] = {0.889, 0.918, 0.978, 0.982, 0.913,
1.039, 0.909, 0.921, 1.027, 1.008};

// Futility margin
Value futility_margin(Depth d, bool noTtCutNode, bool improving, bool oppWorsening) {
Value futilityMult = 158 - 33 * noTtCutNode;
Value futilityMult = 154 - 31 * noTtCutNode;
Value improvingDeduction = 2 * improving * futilityMult;
Value worseningDeduction = 392 * oppWorsening * futilityMult / 1024;
Value worseningDeduction = 338 * oppWorsening * futilityMult / 1144;

return futilityMult * d - improvingDeduction - worseningDeduction;
}
Expand All @@ -75,10 +75,10 @@ Value to_corrected_static_eval(Value v, const Worker& w, const Position& pos) {
}

// History and stats update bonus, based on depth
int stat_bonus(Depth d) { return std::clamp(279 * d - 291, 0, 1460); }
int stat_bonus(Depth d) { return std::clamp(261 * d - 296, 0, 1556); }

// History and stats update malus, based on depth
int stat_malus(Depth d) { return (d < 4 ? 612 * d - 254 : 1405); }
int stat_malus(Depth d) { return (d < 4 ? 647 * d - 251 : 1540); }

// Add a small random component to draw evaluations to avoid 3-fold blindness
Value value_draw(size_t nodes) { return VALUE_DRAW - 1 + Value(nodes & 0x2); }
Expand Down Expand Up @@ -267,12 +267,12 @@ void Search::Worker::iterative_deepening() {

// Reset aspiration window starting size
Value avg = rootMoves[pvIdx].averageScore;
delta = 15 + avg * avg / 33838;
delta = 14 + avg * avg / 33070;
alpha = std::max(avg - delta, -VALUE_INFINITE);
beta = std::min(avg + delta, VALUE_INFINITE);

// Adjust optimism based on root move's averageScore (~4 Elo)
optimism[us] = 203 * avg / (std::abs(avg) + 87);
optimism[us] = 188 * avg / (std::abs(avg) + 88);
optimism[~us] = -optimism[us];

// Start with a small aspiration window and, in the case of a fail
Expand Down Expand Up @@ -387,26 +387,26 @@ void Search::Worker::iterative_deepening() {
// Do we have time for the next iteration? Can we stop searching now?
if (limits.use_time_management() && !threads.stop && !mainThread->stopOnPonderhit)
{
int nodesEffort = rootMoves[0].effort * 100 / std::max(size_t(1), size_t(nodes));
int nodesEffort = rootMoves[0].effort * 114 / std::max(size_t(1), size_t(nodes));

double fallingEval = (70 + 20 * (mainThread->bestPreviousAverageScore - bestValue)
+ 5 * (mainThread->iterValue[iterIdx] - bestValue))
/ 713.30;
fallingEval = std::clamp(fallingEval, 0.50, 1.70);
double fallingEval = (68 + 19 * (mainThread->bestPreviousAverageScore - bestValue)
+ 4 * (mainThread->iterValue[iterIdx] - bestValue))
/ 732.06;
fallingEval = std::clamp(fallingEval, 0.49, 1.53);

// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.66 : 0.65;
double reduction = (1.71 + mainThread->previousTimeReduction) / (2.49 * timeReduction);
double bestMoveInstability = 1.02 + 1.86 * totBestMoveChanges / threads.size();
timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.64 : 0.70;
double reduction = (1.84 + mainThread->previousTimeReduction) / (2.31 * timeReduction);
double bestMoveInstability = 0.98 + 1.90 * totBestMoveChanges / threads.size();
int el = std::clamp((bestValue + 750) / 150, 0, 9);
double recapture = limits.capSq == rootMoves[0].pv[0].to_sq() ? 0.955 : 1.005;
double recapture = limits.capSq == rootMoves[0].pv[0].to_sq() ? 0.983 : 1.027;

double totalTime = mainThread->tm.optimum() * fallingEval * reduction
* bestMoveInstability * EvalLevel[el] * recapture;

auto elapsedTime = elapsed();

if (completedDepth >= 10 && nodesEffort >= 95 && elapsedTime > totalTime * 0.75
if (completedDepth >= 10 && nodesEffort >= 97 && elapsedTime > totalTime * 0.76
&& !mainThread->ponder)
threads.stop = true;

Expand All @@ -421,7 +421,7 @@ void Search::Worker::iterative_deepening() {
threads.stop = true;
}
else
threads.increaseDepth = mainThread->ponder || elapsedTime <= totalTime * 0.430;
threads.increaseDepth = mainThread->ponder || elapsedTime <= totalTime * 0.447;
}

mainThread->iterValue[iterIdx] = bestValue;
Expand All @@ -448,7 +448,7 @@ void Search::Worker::clear() {
h->fill(-71);

for (size_t i = 1; i < reductions.size(); ++i)
reductions[i] = int((18.36 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
reductions[i] = int((20.22 + std::log(size_t(options["Threads"])) / 2) * std::log(i));

refreshTable.clear(network);
}
Expand Down Expand Up @@ -635,7 +635,7 @@ Value Search::Worker::search(
// Use static evaluation difference to improve quiet move ordering (~9 Elo)
if (((ss - 1)->currentMove).is_ok() && !(ss - 1)->inCheck && !priorCapture)
{
int bonus = std::clamp(-12 * int((ss - 1)->staticEval + ss->staticEval), -1130, 2009);
int bonus = std::clamp(-13 * int((ss - 1)->staticEval + ss->staticEval), -924, 1987);
bonus = bonus > 0 ? 2 * bonus : bonus / 2;
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()] << bonus;
if (type_of(pos.piece_on(prevSq)) != PAWN)
Expand All @@ -657,7 +657,7 @@ Value Search::Worker::search(
// Step 6. Razoring (~1 Elo)
// If eval is really low check with qsearch if it can exceed alpha, if it can't,
// return a fail low.
if (eval < alpha - 797 - (332 - 172 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
if (eval < alpha - 911 - (319 - 162 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
{
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha)
Expand All @@ -668,22 +668,22 @@ Value Search::Worker::search(
// The depth condition is important for mate finding.
if (!ss->ttPv && depth < 8
&& eval - futility_margin(depth, cutNode && !ss->ttHit, improving, opponentWorsening)
- (ss - 1)->statScore / 230
- (ss - 1)->statScore / 210
>= beta
&& eval >= beta && eval < 18702 // smaller than wins.
&& eval >= beta && eval < 18675 // smaller than wins.
&& (!ttMove || ttCapture))
return beta > VALUE_MATED_IN_MAX_PLY ? (eval + beta) / 2 : eval;

// Step 8. Null move search with verification search (~35 Elo)
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 12852
&& eval >= beta && ss->staticEval >= beta - 12 * depth + 120 && !excludedMove
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 11973
&& eval >= beta && ss->staticEval >= beta - 12 * depth + 118 && !excludedMove
&& pos.major_material(us) && ss->ply >= thisThread->nmpMinPly
&& beta > VALUE_MATED_IN_MAX_PLY)
{
assert(eval - beta >= 0);

// Null move dynamic reduction based on depth and eval
Depth R = std::min(int(eval - beta) / 122, 5) + depth / 3 + 5;
Depth R = std::min(int(eval - beta) / 129, 5) + depth / 3 + 5;

ss->currentMove = Move::null();
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
Expand All @@ -697,7 +697,7 @@ Value Search::Worker::search(
// Do not return unproven mate
if (nullValue >= beta && nullValue < VALUE_MATE_IN_MAX_PLY)
{
if (thisThread->nmpMinPly || depth < 14)
if (thisThread->nmpMinPly || depth < 13)
return nullValue;

assert(!thisThread->nmpMinPly); // Recursive verification is not allowed
Expand Down Expand Up @@ -731,7 +731,7 @@ Value Search::Worker::search(
// Step 10. ProbCut (~10 Elo)
// If we have a good enough capture and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move.
probCutBeta = beta + 148 - 60 * improving;
probCutBeta = beta + 151 - 62 * improving;
if (
!PvNode && depth > 4
&& std::abs(beta) < VALUE_MATE_IN_MAX_PLY
Expand Down Expand Up @@ -787,7 +787,7 @@ Value Search::Worker::search(
moves_loop: // When in check, search starts here

// Step 11. A small Probcut idea, when we are in check (~4 Elo)
probCutBeta = beta + 416;
probCutBeta = beta + 428;
if (ss->inCheck && !PvNode && ttCapture && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 && ttValue >= probCutBeta
&& std::abs(ttValue) < VALUE_MATE_IN_MAX_PLY && std::abs(beta) < VALUE_MATE_IN_MAX_PLY)
Expand Down Expand Up @@ -869,17 +869,17 @@ Value Search::Worker::search(
thisThread->captureHistory[movedPiece][move.to_sq()][type_of(capturedPiece)];

// Futility pruning for captures (~2 Elo)
if (!givesCheck && lmrDepth < 15 && !ss->inCheck)
if (!givesCheck && lmrDepth < 16 && !ss->inCheck)
{
Value futilityValue = ss->staticEval + 334 + 272 * lmrDepth
Value futilityValue = ss->staticEval + 348 + 290 * lmrDepth
+ PieceValue[capturedPiece] + captHist / 5;
if (futilityValue <= alpha)
continue;
}

// SEE based pruning for captures and checks (~11 Elo)
int seeHist = std::clamp(captHist / 32, -199 * depth, 199 * depth);
if (!pos.see_ge(move, -272 * depth - seeHist))
int seeHist = std::clamp(captHist / 34, -211 * depth, 189 * depth);
if (!pos.see_ge(move, -270 * depth - seeHist))
continue;
}
else
Expand All @@ -890,18 +890,18 @@ Value Search::Worker::search(
+ thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()];

// Continuation history based pruning (~2 Elo)
if (lmrDepth < 6 && history < -3845 * depth)
if (lmrDepth < 6 && history < -3666 * depth)
continue;

history += 2 * thisThread->mainHistory[us][move.from_to()];

lmrDepth += history / 5557;
lmrDepth += history / 5484;

Value futilityValue =
ss->staticEval + (bestValue < ss->staticEval - 58 ? 139 : 115) + 139 * lmrDepth;
ss->staticEval + (bestValue < ss->staticEval - 60 ? 127 : 120) + 135 * lmrDepth;

// Futility pruning: parent node (~13 Elo)
if (!ss->inCheck && lmrDepth < 9 && futilityValue <= alpha)
if (!ss->inCheck && lmrDepth < 8 && futilityValue <= alpha)
{
if (bestValue <= futilityValue && std::abs(bestValue) < VALUE_MATE_IN_MAX_PLY
&& futilityValue < VALUE_MATE_IN_MAX_PLY)
Expand All @@ -912,7 +912,7 @@ Value Search::Worker::search(
lmrDepth = std::max(lmrDepth, 0);

// Prune moves with negative SEE (~4 Elo)
if (!pos.see_ge(move, -37 * lmrDepth * lmrDepth))
if (!pos.see_ge(move, -33 * lmrDepth * lmrDepth))
continue;
}
}
Expand All @@ -932,11 +932,11 @@ Value Search::Worker::search(
// so changing them requires tests at these types of time controls.
// Recursive singular search is avoided.
if (!rootNode && move == ttMove && !excludedMove
&& depth >= 4 - (thisThread->completedDepth > 33) + ss->ttPv
&& depth >= 4 - (thisThread->completedDepth > 34) + ss->ttPv
&& std::abs(ttValue) < VALUE_MATE_IN_MAX_PLY && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3)
{
Value singularBeta = ttValue - (51 + 65 * (ss->ttPv && !PvNode)) * depth / 78;
Value singularBeta = ttValue - (53 + 67 * (ss->ttPv && !PvNode)) * depth / 74;
Depth singularDepth = newDepth / 2;

ss->excludedMove = move;
Expand All @@ -946,16 +946,16 @@ Value Search::Worker::search(

if (value < singularBeta)
{
int doubleMargin = 251 * PvNode - 241 * !ttCapture;
int doubleMargin = 297 * PvNode - 208 * !ttCapture;
int tripleMargin =
135 + 234 * PvNode - 248 * !ttCapture + 124 * (ss->ttPv || !ttCapture);
int quadMargin = 447 + 354 * PvNode - 300 * !ttCapture + 206 * ss->ttPv;
152 + 219 * PvNode - 241 * !ttCapture + 126 * (ss->ttPv || !ttCapture);
int quadMargin = 446 + 364 * PvNode - 283 * !ttCapture + 216 * ss->ttPv;

extension = 1 + (value < singularBeta - doubleMargin)
+ (value < singularBeta - tripleMargin)
+ (value < singularBeta - quadMargin);

depth += ((!PvNode) && (depth < 14));
depth += ((!PvNode) && (depth < 15));
}

// Multi-cut pruning
Expand Down Expand Up @@ -990,7 +990,7 @@ Value Search::Worker::search(
else if (PvNode && move == ttMove && move.to_sq() == prevSq
&& thisThread->captureHistory[movedPiece][move.to_sq()]
[type_of(pos.piece_on(move.to_sq()))]
> 3708)
> 3712)
extension = 1;
}

Expand Down Expand Up @@ -1041,10 +1041,10 @@ Value Search::Worker::search(

ss->statScore = 2 * thisThread->mainHistory[us][move.from_to()]
+ (*contHist[0])[movedPiece][move.to_sq()]
+ (*contHist[1])[movedPiece][move.to_sq()] - 5705;
+ (*contHist[1])[movedPiece][move.to_sq()] - 5696;

// Decrease/increase reduction for moves with a good/bad history (~8 Elo)
r -= ss->statScore / (17662 - std::min(depth, 16) * 105);
r -= ss->statScore / (12495 - std::min(depth, 16) * 107);

// Step 16. Late moves reduction / extension (LMR, ~117 Elo)
if (depth >= 2 && moveCount > 1 + rootNode)
Expand All @@ -1063,7 +1063,7 @@ Value Search::Worker::search(
{
// Adjust full-depth search based on LMR results - if the result
// was good enough search deeper, if it was bad enough search shallower.
const bool doDeeperSearch = value > (bestValue + 65 + 2 * newDepth); // (~1 Elo)
const bool doDeeperSearch = value > (bestValue + 64 + 2 * newDepth); // (~1 Elo)
const bool doShallowerSearch = value < bestValue + newDepth; // (~2 Elo)

newDepth += doDeeperSearch - doShallowerSearch;
Expand Down Expand Up @@ -1224,9 +1224,9 @@ Value Search::Worker::search(
// Bonus for prior countermove that caused the fail low
else if (!priorCapture && prevSq != SQ_NONE)
{
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -12710)
+ ((ss - 1)->moveCount > 12) + (!ss->inCheck && bestValue <= ss->staticEval - 157)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 77);
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -12449)
+ ((ss - 1)->moveCount > 13) + (!ss->inCheck && bestValue <= ss->staticEval - 146)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 78);
update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
stat_bonus(depth) * bonus);
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()]
Expand Down Expand Up @@ -1401,7 +1401,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
if (bestValue > alpha)
alpha = bestValue;

futilityBase = ss->staticEval + 108;
futilityBase = ss->staticEval + 129;
}

const PieceToHistory* contHist[] = {(ss - 1)->continuationHistory,
Expand Down Expand Up @@ -1475,7 +1475,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
continue;

// Do not search moves with bad enough SEE values (~5 Elo)
if (!pos.see_ge(move, -115))
if (!pos.see_ge(move, -116))
continue;
}

Expand Down Expand Up @@ -1541,7 +1541,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,

Depth Search::Worker::reduction(bool i, Depth d, int mn, int delta) {
int reductionScale = reductions[d] * reductions[mn];
return (reductionScale + 1883 - delta * 1567 / rootDelta) / 1318 + (!i && reductionScale > 903);
return (reductionScale + 2054 - delta * 1570 / rootDelta) / 1321 + (!i && reductionScale > 904);
}

// elapsed() returns the time elapsed since the search started. If the
Expand Down Expand Up @@ -1626,7 +1626,7 @@ void update_all_stats(const Position& pos,

if (!pos.capture(bestMove))
{
int bestMoveBonus = bestValue > beta + 101 ? quietMoveBonus // larger bonus
int bestMoveBonus = bestValue > beta + 107 ? quietMoveBonus // larger bonus
: stat_bonus(depth); // smaller bonus

update_quiet_stats(pos, ss, workerThread, bestMove, bestMoveBonus);
Expand Down

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