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Merge commit 'db147fe2586527a854516016699949af53dc5b17' into cluster

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This is the last commit before there are more conflicts.
This commit is contained in:
Steinar H. Gunderson
2025-12-24 15:14:23 +01:00
parent b7045f1bf6 db147fe258
commit 649004ed47
13 changed files with 336 additions and 485 deletions
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src/search.cpp
+101 -86
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@@ -60,9 +60,9 @@ static constexpr double EvalLevel[10] = {0.981, 0.956, 0.895, 0.949, 0.913,
// Futility margin
Value futility_margin(Depth d, bool noTtCutNode, bool improving, bool oppWorsening) {
Value futilityMult = 118 - 45 * noTtCutNode;
Value improvingDeduction = 52 * improving * futilityMult / 32;
Value worseningDeduction = (316 + 48 * improving) * oppWorsening * futilityMult / 1024;
Value futilityMult = 126 - 46 * noTtCutNode;
Value improvingDeduction = 58 * improving * futilityMult / 32;
Value worseningDeduction = (323 + 52 * improving) * oppWorsening * futilityMult / 1024;
return futilityMult * d - improvingDeduction - worseningDeduction;
}
@@ -74,15 +74,15 @@ constexpr int futility_move_count(bool improving, Depth depth) {
// Add correctionHistory value to raw staticEval and guarantee evaluation does not hit the tablebase range
Value to_corrected_static_eval(Value v, const Worker& w, const Position& pos) {
auto cv = w.correctionHistory[pos.side_to_move()][pawn_structure_index<Correction>(pos)];
v += cv * std::abs(cv) / 9260;
v += cv * std::abs(cv) / 7350;
return std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
}
// History and stats update bonus, based on depth
int stat_bonus(Depth d) { return std::clamp(214 * d - 318, 16, 1304); }
int stat_bonus(Depth d) { return std::clamp(208 * d - 297, 16, 1406); }
// History and stats update malus, based on depth
int stat_malus(Depth d) { return (d < 4 ? 572 * d - 284 : 1355); }
int stat_malus(Depth d) { return (d < 4 ? 520 * d - 312 : 1479); }
// 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); }
@@ -115,8 +115,11 @@ Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply, int r50c);
void update_pv(Move* pv, Move move, const Move* childPv);
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
void update_quiet_stats(
void update_refutations(const Position& pos, Stack* ss, Search::Worker& workerThread, Move move);
void update_quiet_histories(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus);
void update_quiet_stats(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus);
void update_all_stats(const Position& pos,
Stack* ss,
Search::Worker& workerThread,
@@ -148,9 +151,6 @@ Search::Worker::Worker(SharedState& sharedState,
void Search::Worker::start_searching() {
// Initialize accumulator refresh entries
refreshTable.clear(networks);
// Non-main threads go directly to iterative_deepening()
if (!is_mainthread())
{
@@ -352,12 +352,12 @@ void Search::Worker::iterative_deepening() {
// Reset aspiration window starting size
Value avg = rootMoves[pvIdx].averageScore;
delta = 10 + avg * avg / 11480;
delta = 10 + avg * avg / 9530;
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] = 122 * avg / (std::abs(avg) + 92);
optimism[us] = 119 * avg / (std::abs(avg) + 88);
optimism[~us] = -optimism[us];
// Start with a small aspiration window and, in the case of a fail
@@ -550,10 +550,12 @@ void Search::Worker::clear() {
for (StatsType c : {NoCaptures, Captures})
for (auto& to : continuationHistory[inCheck][c])
for (auto& h : to)
h->fill(-65);
h->fill(-60);
for (size_t i = 1; i < reductions.size(); ++i)
reductions[i] = int((20.14 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
reductions[i] = int((18.93 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
refreshTable.clear(networks);
}
@@ -642,7 +644,6 @@ Value Search::Worker::search(
bestMove = Move::none();
(ss + 2)->killers[0] = (ss + 2)->killers[1] = Move::none();
(ss + 2)->cutoffCnt = 0;
ss->multipleExtensions = (ss - 1)->multipleExtensions;
Square prevSq = ((ss - 1)->currentMove).is_ok() ? ((ss - 1)->currentMove).to_sq() : SQ_NONE;
ss->statScore = 0;
@@ -785,7 +786,7 @@ 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(-14 * int((ss - 1)->staticEval + ss->staticEval), -1644, 1384);
int bonus = std::clamp(-13 * int((ss - 1)->staticEval + ss->staticEval), -1796, 1526);
bonus = bonus > 0 ? 2 * bonus : bonus / 2;
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()] << bonus;
if (type_of(pos.piece_on(prevSq)) != PAWN && ((ss - 1)->currentMove).type_of() != PROMOTION)
@@ -808,7 +809,7 @@ Value Search::Worker::search(
// If eval is really low check with qsearch if it can exceed alpha, if it can't,
// return a fail low.
// Adjust razor margin according to cutoffCnt. (~1 Elo)
if (eval < alpha - 471 - (275 - 148 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
if (eval < alpha - 433 - (302 - 141 * ((ss + 1)->cutoffCnt > 3)) * depth * depth)
{
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha)
@@ -817,23 +818,23 @@ Value Search::Worker::search(
// Step 8. Futility pruning: child node (~40 Elo)
// The depth condition is important for mate finding.
if (!ss->ttPv && depth < 12
if (!ss->ttPv && depth < 11
&& eval - futility_margin(depth, cutNode && !ss->ttHit, improving, opponentWorsening)
- (ss - 1)->statScore / 286
- (ss - 1)->statScore / 254
>= beta
&& eval >= beta && eval < VALUE_TB_WIN_IN_MAX_PLY && (!ttMove || ttCapture))
return beta > VALUE_TB_LOSS_IN_MAX_PLY ? (eval + beta) / 2 : eval;
// Step 9. Null move search with verification search (~35 Elo)
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 18001
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 312 && !excludedMove
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 16993
&& eval >= beta && ss->staticEval >= beta - 19 * depth + 326 && !excludedMove
&& pos.non_pawn_material(us) && ss->ply >= thisThread->nmpMinPly
&& beta > VALUE_TB_LOSS_IN_MAX_PLY)
{
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and eval
Depth R = std::min(int(eval - beta) / 152, 6) + depth / 3 + 4;
Depth R = std::min(int(eval - beta) / 134, 6) + depth / 3 + 4;
ss->currentMove = Move::null();
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -875,13 +876,13 @@ Value Search::Worker::search(
return qsearch<PV>(pos, ss, alpha, beta);
// For cutNodes without a ttMove, we decrease depth by 2 if depth is high enough.
if (cutNode && depth >= 8 && !ttMove)
depth -= 2;
if (cutNode && depth >= 8 && (!ttMove || tte->bound() == BOUND_UPPER))
depth -= 1 + !ttMove;
// Step 11. ProbCut (~10 Elo)
// If we have a good enough capture (or queen promotion) and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move.
probCutBeta = beta + 169 - 63 * improving;
probCutBeta = beta + 159 - 66 * improving;
if (
!PvNode && depth > 3
&& std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
@@ -938,7 +939,7 @@ Value Search::Worker::search(
moves_loop: // When in check, search starts here
// Step 12. A small Probcut idea, when we are in check (~4 Elo)
probCutBeta = beta + 452;
probCutBeta = beta + 420;
if (ss->inCheck && !PvNode && ttCapture && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 4 && ttValue >= probCutBeta
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
@@ -1016,20 +1017,22 @@ moves_loop: // When in check, search starts here
if (capture || givesCheck)
{
Piece capturedPiece = pos.piece_on(move.to_sq());
int captHist =
thisThread->captureHistory[movedPiece][move.to_sq()][type_of(capturedPiece)];
// Futility pruning for captures (~2 Elo)
if (!givesCheck && lmrDepth < 7 && !ss->inCheck)
{
Piece capturedPiece = pos.piece_on(move.to_sq());
Value futilityValue =
ss->staticEval + 285 + 277 * lmrDepth + PieceValue[capturedPiece]
+ thisThread->captureHistory[movedPiece][move.to_sq()][type_of(capturedPiece)]
/ 7;
Value futilityValue = ss->staticEval + 295 + 280 * lmrDepth
+ PieceValue[capturedPiece] + captHist / 7;
if (futilityValue <= alpha)
continue;
}
// SEE based pruning for captures and checks (~11 Elo)
if (!pos.see_ge(move, -203 * depth))
int seeHist = std::clamp(captHist / 32, -197 * depth, 196 * depth);
if (!pos.see_ge(move, -186 * depth - seeHist))
continue;
}
else
@@ -1037,22 +1040,22 @@ moves_loop: // When in check, search starts here
int history =
(*contHist[0])[movedPiece][move.to_sq()]
+ (*contHist[1])[movedPiece][move.to_sq()]
+ (*contHist[3])[movedPiece][move.to_sq()]
+ (*contHist[3])[movedPiece][move.to_sq()] / 2
+ thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()];
// Continuation history based pruning (~2 Elo)
if (lmrDepth < 6 && history < -4173 * depth)
if (lmrDepth < 6 && history < -4081 * depth)
continue;
history += 2 * thisThread->mainHistory[us][move.from_to()];
lmrDepth += history / 5285;
lmrDepth += history / 4768;
Value futilityValue =
ss->staticEval + (bestValue < ss->staticEval - 54 ? 128 : 57) + 131 * lmrDepth;
ss->staticEval + (bestValue < ss->staticEval - 52 ? 134 : 54) + 142 * lmrDepth;
// Futility pruning: parent node (~13 Elo)
if (!ss->inCheck && lmrDepth < 14 && futilityValue <= alpha)
if (!ss->inCheck && lmrDepth < 13 && futilityValue <= alpha)
{
if (bestValue <= futilityValue && std::abs(bestValue) < VALUE_TB_WIN_IN_MAX_PLY
&& futilityValue < VALUE_TB_WIN_IN_MAX_PLY)
@@ -1063,7 +1066,7 @@ moves_loop: // When in check, search starts here
lmrDepth = std::max(lmrDepth, 0);
// Prune moves with negative SEE (~4 Elo)
if (!pos.see_ge(move, -27 * lmrDepth * lmrDepth))
if (!pos.see_ge(move, -28 * lmrDepth * lmrDepth))
continue;
}
}
@@ -1083,11 +1086,11 @@ moves_loop: // When in check, search starts here
// 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 > 32) + ss->ttPv
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3)
{
Value singularBeta = ttValue - (65 + 59 * (ss->ttPv && !PvNode)) * depth / 63;
Value singularBeta = ttValue - (65 + 52 * (ss->ttPv && !PvNode)) * depth / 63;
Depth singularDepth = newDepth / 2;
ss->excludedMove = move;
@@ -1097,17 +1100,16 @@ moves_loop: // When in check, search starts here
if (value < singularBeta)
{
extension = 1;
int doubleMargin = 251 * PvNode - 241 * !ttCapture;
int tripleMargin =
135 + 234 * PvNode - 248 * !ttCapture + 124 * (ss->ttPv || !ttCapture);
int quadMargin = 447 + 354 * PvNode - 300 * !ttCapture + 206 * ss->ttPv;
// We make sure to limit the extensions in some way to avoid a search explosion
if (!PvNode && ss->multipleExtensions <= 16)
{
extension = 2 + (value < singularBeta - 11 && !ttCapture);
depth += depth < 14;
}
if (PvNode && !ttCapture && ss->multipleExtensions <= 5
&& value < singularBeta - 38)
extension = 2;
extension = 1 + (value < singularBeta - doubleMargin)
+ (value < singularBeta - tripleMargin)
+ (value < singularBeta - quadMargin);
depth += ((!PvNode) && (depth < 14));
}
// Multi-cut pruning
@@ -1116,7 +1118,12 @@ moves_loop: // When in check, search starts here
// we assume this expected cut-node is not singular (multiple moves fail high),
// and we can prune the whole subtree by returning a softbound.
else if (singularBeta >= beta)
{
if (!ttCapture)
update_quiet_histories(pos, ss, *this, ttMove, -stat_malus(depth));
return singularBeta;
}
// Negative extensions
// If other moves failed high over (ttValue - margin) without the ttMove on a reduced search,
@@ -1141,13 +1148,12 @@ moves_loop: // When in check, search starts here
else if (PvNode && move == ttMove && move.to_sq() == prevSq
&& thisThread->captureHistory[movedPiece][move.to_sq()]
[type_of(pos.piece_on(move.to_sq()))]
> 3807)
> 4016)
extension = 1;
}
// Add extension to new depth
newDepth += extension;
ss->multipleExtensions = (ss - 1)->multipleExtensions + (extension >= 2);
// Speculative prefetch as early as possible
prefetch(tt.first_entry(pos.key_after(move)));
@@ -1167,6 +1173,9 @@ moves_loop: // When in check, search starts here
if (ss->ttPv)
r -= 1 + (ttValue > alpha) + (tte->depth() >= depth);
else if (cutNode && move != ttMove && move != ss->killers[0])
r++;
// Increase reduction for cut nodes (~4 Elo)
if (cutNode)
r += 2 - (tte->depth() >= depth && ss->ttPv);
@@ -1191,10 +1200,10 @@ moves_loop: // When in check, search starts here
ss->statScore = 2 * thisThread->mainHistory[us][move.from_to()]
+ (*contHist[0])[movedPiece][move.to_sq()]
+ (*contHist[1])[movedPiece][move.to_sq()]
+ (*contHist[3])[movedPiece][move.to_sq()] - 5024;
+ (*contHist[3])[movedPiece][move.to_sq()] - 5078;
// Decrease/increase reduction for moves with a good/bad history (~8 Elo)
r -= ss->statScore / 13182;
r -= ss->statScore / (17662 - std::min(depth, 16) * 105);
// Step 17. Late moves reduction / extension (LMR, ~117 Elo)
if (depth >= 2 && moveCount > 1 + rootNode)
@@ -1213,7 +1222,7 @@ moves_loop: // When in check, search starts here
{
// 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 + 42 + 2 * newDepth); // (~1 Elo)
const bool doDeeperSearch = value > (bestValue + 40 + 2 * newDepth); // (~1 Elo)
const bool doShallowerSearch = value < bestValue + newDepth; // (~2 Elo)
newDepth += doDeeperSearch - doShallowerSearch;
@@ -1331,7 +1340,7 @@ moves_loop: // When in check, search starts here
else
{
// Reduce other moves if we have found at least one score improvement (~2 Elo)
if (depth > 2 && depth < 12 && beta < 13546 && value > -13478)
if (depth > 2 && depth < 13 && beta < 15868 && value > -14630)
depth -= 2;
assert(depth > 0);
@@ -1374,9 +1383,9 @@ moves_loop: // When in check, search starts here
// Bonus for prior countermove that caused the fail low
else if (!priorCapture && prevSq != SQ_NONE)
{
int bonus = (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -14761)
+ ((ss - 1)->moveCount > 11)
+ (!ss->inCheck && bestValue <= ss->staticEval - 142);
int bonus = (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -14455)
+ ((ss - 1)->moveCount > 10) + (!ss->inCheck && bestValue <= ss->staticEval - 130)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 77);
update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
stat_bonus(depth) * bonus);
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()]
@@ -1537,7 +1546,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
if (bestValue > alpha)
alpha = bestValue;
futilityBase = ss->staticEval + 250;
futilityBase = ss->staticEval + 270;
}
const PieceToHistory* contHist[] = {(ss - 1)->continuationHistory,
@@ -1612,12 +1621,16 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
break;
// Continuation history based pruning (~3 Elo)
if (!capture && (*contHist[0])[pos.moved_piece(move)][move.to_sq()] < 0
&& (*contHist[1])[pos.moved_piece(move)][move.to_sq()] < 0)
if (!capture
&& (*contHist[0])[pos.moved_piece(move)][move.to_sq()]
+ (*contHist[1])[pos.moved_piece(move)][move.to_sq()]
+ thisThread->pawnHistory[pawn_structure_index(pos)][pos.moved_piece(move)]
[move.to_sq()]
<= 4000)
continue;
// Do not search moves with bad enough SEE values (~5 Elo)
if (!pos.see_ge(move, -79))
if (!pos.see_ge(move, -69))
continue;
}
@@ -1685,7 +1698,7 @@ 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 + 1150 - delta * 832 / rootDelta) / 1024 + (!i && reductionScale > 1025);
return (reductionScale + 1318 - delta * 760 / rootDelta) / 1024 + (!i && reductionScale > 1066);
}
TimePoint Search::Worker::elapsed() const {
@@ -1769,7 +1782,6 @@ void update_all_stats(const Position& pos,
int captureCount,
Depth depth) {
Color us = pos.side_to_move();
CapturePieceToHistory& captureHistory = workerThread.captureHistory;
Piece moved_piece = pos.moved_piece(bestMove);
PieceType captured;
@@ -1779,26 +1791,14 @@ void update_all_stats(const Position& pos,
if (!pos.capture_stage(bestMove))
{
int bestMoveBonus = bestValue > beta + 185 ? quietMoveBonus // larger bonus
int bestMoveBonus = bestValue > beta + 165 ? quietMoveBonus // larger bonus
: stat_bonus(depth); // smaller bonus
// Increase stats for the best move in case it was a quiet move
update_quiet_stats(pos, ss, workerThread, bestMove, bestMoveBonus);
int pIndex = pawn_structure_index(pos);
workerThread.pawnHistory[pIndex][moved_piece][bestMove.to_sq()] << quietMoveBonus;
// Decrease stats for all non-best quiet moves
for (int i = 0; i < quietCount; ++i)
{
workerThread
.pawnHistory[pIndex][pos.moved_piece(quietsSearched[i])][quietsSearched[i].to_sq()]
<< -quietMoveMalus;
workerThread.mainHistory[us][quietsSearched[i].from_to()] << -quietMoveMalus;
update_continuation_histories(ss, pos.moved_piece(quietsSearched[i]),
quietsSearched[i].to_sq(), -quietMoveMalus);
}
update_quiet_histories(pos, ss, workerThread, quietsSearched[i], -quietMoveMalus);
}
else
{
@@ -1839,10 +1839,8 @@ void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
}
}
// Updates move sorting heuristics
void update_quiet_stats(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus) {
void update_refutations(const Position& pos, Stack* ss, Search::Worker& workerThread, Move move) {
// Update killers
if (ss->killers[0] != move)
@@ -1851,10 +1849,6 @@ void update_quiet_stats(
ss->killers[0] = move;
}
Color us = pos.side_to_move();
workerThread.mainHistory[us][move.from_to()] << bonus;
update_continuation_histories(ss, pos.moved_piece(move), move.to_sq(), bonus);
// Update countermove history
if (((ss - 1)->currentMove).is_ok())
{
@@ -1862,6 +1856,27 @@ void update_quiet_stats(
workerThread.counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
}
void update_quiet_histories(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus) {
Color us = pos.side_to_move();
workerThread.mainHistory[us][move.from_to()] << bonus;
update_continuation_histories(ss, pos.moved_piece(move), move.to_sq(), bonus);
int pIndex = pawn_structure_index(pos);
workerThread.pawnHistory[pIndex][pos.moved_piece(move)][move.to_sq()] << bonus;
}
// Updates move sorting heuristics
void update_quiet_stats(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus) {
update_refutations(pos, ss, workerThread, move);
update_quiet_histories(pos, ss, workerThread, move, bonus);
}
}
// When playing with strength handicap, choose the best move among a set of RootMoves