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Update Stockfish to development version from 2020-06-17

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This commit is contained in:
Peter Osterlund
2020-06-19 11:49:56 +02:00
parent a64eab03cc
commit 6bcbd6d080
34 changed files with 1445 additions and 885 deletions
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408
DroidFishApp/src/main/cpp/stockfish/search.cpp
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@@ -61,13 +61,13 @@ namespace {
// Different node types, used as a template parameter
enum NodeType { NonPV, PV };
constexpr uint64_t ttHitAverageWindow = 4096;
constexpr uint64_t ttHitAverageResolution = 1024;
constexpr uint64_t TtHitAverageWindow = 4096;
constexpr uint64_t TtHitAverageResolution = 1024;
// Razor and futility margins
constexpr int RazorMargin = 531;
constexpr int RazorMargin = 527;
Value futility_margin(Depth d, bool improving) {
return Value(217 * (d - improving));
return Value(227 * (d - improving));
}
// Reductions lookup table, initialized at startup
@@ -75,16 +75,16 @@ namespace {
Depth reduction(bool i, Depth d, int mn) {
int r = Reductions[d] * Reductions[mn];
return (r + 511) / 1024 + (!i && r > 1007);
return (r + 570) / 1024 + (!i && r > 1018);
}
constexpr int futility_move_count(bool improving, Depth depth) {
return (5 + depth * depth) * (1 + improving) / 2 - 1;
return (3 + depth * depth) / (2 - improving);
}
// History and stats update bonus, based on depth
int stat_bonus(Depth d) {
return d > 15 ? -8 : 19 * d * d + 155 * d - 132;
return d > 15 ? 27 : 17 * d * d + 133 * d - 134;
}
// Add a small random component to draw evaluations to avoid 3fold-blindness
@@ -156,7 +156,7 @@ namespace {
Value value_from_tt(Value v, int ply, int r50c);
void update_pv(Move* pv, Move move, Move* childPv);
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth);
void update_all_stats(const Position& pos, Stack* ss, Move bestMove, Value bestValue, Value beta, Square prevSq,
Move* quietsSearched, int quietCount, Move* capturesSearched, int captureCount, Depth depth);
@@ -194,7 +194,7 @@ namespace {
void Search::init() {
for (int i = 1; i < MAX_MOVES; ++i)
Reductions[i] = int((24.8 + std::log(Threads.size()) / 2) * std::log(i));
Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i));
}
@@ -236,14 +236,8 @@ void MainThread::search() {
}
else
{
for (Thread* th : Threads)
{
th->bestMoveChanges = 0;
if (th != this)
th->start_searching();
}
Thread::search(); // Let's start searching!
Threads.start_searching(); // start non-main threads
Thread::search(); // main thread start searching
}
// When we reach the maximum depth, we can arrive here without a raise of
@@ -260,9 +254,7 @@ void MainThread::search() {
Threads.stop = true;
// Wait until all threads have finished
for (Thread* th : Threads)
if (th != this)
th->wait_for_search_finished();
Threads.wait_for_search_finished();
// When playing in 'nodes as time' mode, subtract the searched nodes from
// the available ones before exiting.
@@ -271,38 +263,13 @@ void MainThread::search() {
Thread* bestThread = this;
// Check if there are threads with a better score than main thread
if ( Options["MultiPV"] == 1
&& !Limits.depth
&& !(Skill(Options["Skill Level"]).enabled() || Options["UCI_LimitStrength"])
&& rootMoves[0].pv[0] != MOVE_NONE)
{
std::map<Move, int64_t> votes;
Value minScore = this->rootMoves[0].score;
if (int(Options["MultiPV"]) == 1 &&
!Limits.depth &&
!(Skill(Options["Skill Level"]).enabled() || int(Options["UCI_LimitStrength"])) &&
rootMoves[0].pv[0] != MOVE_NONE)
bestThread = Threads.get_best_thread();
// Find out minimum score
for (Thread* th: Threads)
minScore = std::min(minScore, th->rootMoves[0].score);
// Vote according to score and depth, and select the best thread
for (Thread* th : Threads)
{
votes[th->rootMoves[0].pv[0]] +=
(th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
if (bestThread->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY)
{
// Make sure we pick the shortest mate
if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
bestThread = th;
}
else if ( th->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY
|| votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
bestThread = th;
}
}
previousScore = bestThread->rootMoves[0].score;
bestPreviousScore = bestThread->rootMoves[0].score;
// Send again PV info if we have a new best thread
if (bestThread != this)
@@ -348,15 +315,18 @@ void Thread::search() {
if (mainThread)
{
if (mainThread->previousScore == VALUE_INFINITE)
for (int i=0; i<4; ++i)
if (mainThread->bestPreviousScore == VALUE_INFINITE)
for (int i = 0; i < 4; ++i)
mainThread->iterValue[i] = VALUE_ZERO;
else
for (int i=0; i<4; ++i)
mainThread->iterValue[i] = mainThread->previousScore;
for (int i = 0; i < 4; ++i)
mainThread->iterValue[i] = mainThread->bestPreviousScore;
}
size_t multiPV = Options["MultiPV"];
std::copy(&lowPlyHistory[2][0], &lowPlyHistory.back().back() + 1, &lowPlyHistory[0][0]);
std::fill(&lowPlyHistory[MAX_LPH - 2][0], &lowPlyHistory.back().back() + 1, 0);
size_t multiPV = size_t(Options["MultiPV"]);
// Pick integer skill levels, but non-deterministically round up or down
// such that the average integer skill corresponds to the input floating point one.
@@ -365,7 +335,7 @@ void Thread::search() {
// for match (TC 60+0.6) results spanning a wide range of k values.
PRNG rng(now());
double floatLevel = Options["UCI_LimitStrength"] ?
clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
Utility::clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
double(Options["Skill Level"]);
int intLevel = int(floatLevel) +
((floatLevel - int(floatLevel)) * 1024 > rng.rand<unsigned>() % 1024 ? 1 : 0);
@@ -377,7 +347,7 @@ void Thread::search() {
multiPV = std::max(multiPV, (size_t)4);
multiPV = std::min(multiPV, rootMoves.size());
ttHitAverage = ttHitAverageWindow * ttHitAverageResolution / 2;
ttHitAverage = TtHitAverageWindow * TtHitAverageResolution / 2;
int ct = int(Options["Contempt"]) * PawnValueEg / 100; // From centipawns
@@ -432,13 +402,13 @@ void Thread::search() {
// Reset aspiration window starting size
if (rootDepth >= 4)
{
Value previousScore = rootMoves[pvIdx].previousScore;
delta = Value(21 + abs(previousScore) / 256);
alpha = std::max(previousScore - delta,-VALUE_INFINITE);
beta = std::min(previousScore + delta, VALUE_INFINITE);
Value prev = rootMoves[pvIdx].previousScore;
delta = Value(19);
alpha = std::max(prev - delta,-VALUE_INFINITE);
beta = std::min(prev + delta, VALUE_INFINITE);
// Adjust contempt based on root move's previousScore (dynamic contempt)
int dct = ct + (102 - ct / 2) * previousScore / (abs(previousScore) + 157);
int dct = ct + (110 - ct / 2) * prev / (abs(prev) + 140);
contempt = (us == WHITE ? make_score(dct, dct / 2)
: -make_score(dct, dct / 2));
@@ -536,13 +506,13 @@ void Thread::search() {
&& !Threads.stop
&& !mainThread->stopOnPonderhit)
{
double fallingEval = (332 + 6 * (mainThread->previousScore - bestValue)
+ 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 704.0;
fallingEval = clamp(fallingEval, 0.5, 1.5);
double fallingEval = (296 + 6 * (mainThread->bestPreviousScore - bestValue)
+ 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 725.0;
fallingEval = Utility::clamp(fallingEval, 0.5, 1.5);
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.94 : 0.91;
double reduction = (1.41 + mainThread->previousTimeReduction) / (2.27 * timeReduction);
timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.92 : 0.95;
double reduction = (1.47 + mainThread->previousTimeReduction) / (2.22 * timeReduction);
// Use part of the gained time from a previous stable move for the current move
for (Thread* th : Threads)
@@ -552,9 +522,11 @@ void Thread::search() {
}
double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
// Stop the search if we have only one legal move, or if available time elapsed
if ( rootMoves.size() == 1
|| Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability)
double totalTime = rootMoves.size() == 1 ? 0 :
Time.optimum() * fallingEval * reduction * bestMoveInstability;
// Stop the search if we have exceeded the totalTime, at least 1ms search.
if (Time.elapsed() > totalTime)
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
@@ -565,7 +537,7 @@ void Thread::search() {
}
else if ( Threads.increaseDepth
&& !mainThread->ponder
&& Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6)
&& Time.elapsed() > totalTime * 0.56)
Threads.increaseDepth = false;
else
Threads.increaseDepth = true;
@@ -625,14 +597,15 @@ namespace {
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth;
Value bestValue, value, ttValue, eval, maxValue;
bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
ttCapture, singularQuietLMR;
Piece movedPiece;
int moveCount, captureCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
ss->inCheck = pos.checkers();
priorCapture = pos.captured_piece();
Color us = pos.side_to_move();
moveCount = captureCount = quietCount = ss->moveCount = 0;
@@ -653,7 +626,7 @@ namespace {
if ( Threads.stop.load(std::memory_order_relaxed)
|| pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos)
return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos)
: value_draw(pos.this_thread());
// Step 3. Mate distance pruning. Even if we mate at the next move our score
@@ -689,15 +662,20 @@ namespace {
// search to overwrite a previous full search TT value, so we use a different
// position key in case of an excluded move.
excludedMove = ss->excludedMove;
posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash
posKey = pos.key() ^ (Key(excludedMove) << 48); // Isn't a very good hash
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
: ttHit ? tte->move() : MOVE_NONE;
ttPv = PvNode || (ttHit && tte->is_pv());
formerPv = ttPv && !PvNode;
if (ttPv && depth > 12 && ss->ply - 1 < MAX_LPH && !pos.captured_piece() && is_ok((ss-1)->currentMove))
thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5);
// thisThread->ttHitAverage can be used to approximate the running average of ttHit
thisThread->ttHitAverage = (ttHitAverageWindow - 1) * thisThread->ttHitAverage / ttHitAverageWindow
+ ttHitAverageResolution * ttHit;
thisThread->ttHitAverage = (TtHitAverageWindow - 1) * thisThread->ttHitAverage / TtHitAverageWindow
+ TtHitAverageResolution * ttHit;
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
@@ -713,7 +691,7 @@ namespace {
if (ttValue >= beta)
{
if (!pos.capture_or_promotion(ttMove))
update_quiet_stats(pos, ss, ttMove, stat_bonus(depth));
update_quiet_stats(pos, ss, ttMove, stat_bonus(depth), depth);
// Extra penalty for early quiet moves of the previous ply
if ((ss-1)->moveCount <= 2 && !priorCapture)
@@ -755,9 +733,10 @@ namespace {
int drawScore = TB::UseRule50 ? 1 : 0;
value = wdl < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply + 1
: wdl > drawScore ? VALUE_MATE - MAX_PLY - ss->ply - 1
: VALUE_DRAW + 2 * wdl * drawScore;
// use the range VALUE_MATE_IN_MAX_PLY to VALUE_TB_WIN_IN_MAX_PLY to score
value = wdl < -drawScore ? VALUE_MATED_IN_MAX_PLY + ss->ply + 1
: wdl > drawScore ? VALUE_MATE_IN_MAX_PLY - ss->ply - 1
: VALUE_DRAW + 2 * wdl * drawScore;
Bound b = wdl < -drawScore ? BOUND_UPPER
: wdl > drawScore ? BOUND_LOWER : BOUND_EXACT;
@@ -783,8 +762,10 @@ namespace {
}
}
CapturePieceToHistory& captureHistory = thisThread->captureHistory;
// Step 6. Static evaluation of the position
if (inCheck)
if (ss->inCheck)
{
ss->staticEval = eval = VALUE_NONE;
improving = false;
@@ -814,19 +795,19 @@ namespace {
ss->staticEval = eval = evaluate(pos) + bonus;
}
else
ss->staticEval = eval = -(ss-1)->staticEval + 2 * Eval::Tempo;
ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo;
tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
}
// Step 7. Razoring (~1 Elo)
if ( !rootNode // The required rootNode PV handling is not available in qsearch
&& depth < 2
&& depth == 1
&& eval <= alpha - RazorMargin)
return qsearch<NT>(pos, ss, alpha, beta);
improving = (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval
|| (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval;
improving = (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval
|| (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval;
// Step 8. Futility pruning: child node (~50 Elo)
if ( !PvNode
@@ -838,10 +819,10 @@ namespace {
// Step 9. Null move search with verification search (~40 Elo)
if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 23397
&& (ss-1)->statScore < 23824
&& eval >= beta
&& eval >= ss->staticEval
&& ss->staticEval >= beta - 32 * depth + 292 - improving * 30
&& ss->staticEval >= beta - 33 * depth - 33 * improving + 112 * ttPv + 311
&& !excludedMove
&& pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -849,7 +830,7 @@ namespace {
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
Depth R = (854 + 68 * depth) / 258 + std::min(int(eval - beta) / 192, 3);
Depth R = (737 + 77 * depth) / 246 + std::min(int(eval - beta) / 192, 3);
ss->currentMove = MOVE_NULL;
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -862,8 +843,8 @@ namespace {
if (nullValue >= beta)
{
// Do not return unproven mate scores
if (nullValue >= VALUE_MATE_IN_MAX_PLY)
// Do not return unproven mate or TB scores
if (nullValue >= VALUE_TB_WIN_IN_MAX_PLY)
nullValue = beta;
if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 13))
@@ -889,15 +870,19 @@ namespace {
// 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.
if ( !PvNode
&& depth >= 5
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
&& depth > 4
&& abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
{
Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE);
MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory);
Value raisedBeta = beta + 176 - 49 * improving;
assert(raisedBeta < VALUE_INFINITE);
MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &captureHistory);
int probCutCount = 0;
while ( (move = mp.next_move()) != MOVE_NONE
&& probCutCount < 2 + 2 * cutNode)
while ( (move = mp.next_move()) != MOVE_NONE
&& probCutCount < 2 + 2 * cutNode
&& !( move == ttMove
&& tte->depth() >= depth - 4
&& ttValue < raisedBeta))
if (move != excludedMove && pos.legal(move))
{
assert(pos.capture_or_promotion(move));
@@ -907,7 +892,7 @@ namespace {
probCutCount++;
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[inCheck]
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[pos.moved_piece(move)]
[to_sq(move)];
@@ -947,13 +932,15 @@ moves_loop: // When in check, search starts from here
Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
&thisThread->captureHistory,
&thisThread->lowPlyHistory,
&captureHistory,
contHist,
countermove,
ss->killers);
ss->killers,
ss->ply);
value = bestValue;
singularLMR = moveCountPruning = false;
singularQuietLMR = moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove);
// Mark this node as being searched
@@ -996,17 +983,17 @@ moves_loop: // When in check, search starts from here
// Step 13. Pruning at shallow depth (~200 Elo)
if ( !rootNode
&& pos.non_pawn_material(us)
&& bestValue > VALUE_MATED_IN_MAX_PLY)
&& bestValue > VALUE_TB_LOSS_IN_MAX_PLY)
{
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
moveCountPruning = moveCount >= futility_move_count(improving, depth);
// Reduced depth of the next LMR search
int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
if ( !captureOrPromotion
&& !givesCheck)
{
// Reduced depth of the next LMR search
int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
// Countermoves based pruning (~20 Elo)
if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
&& (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
@@ -1015,20 +1002,38 @@ moves_loop: // When in check, search starts from here
// Futility pruning: parent node (~5 Elo)
if ( lmrDepth < 6
&& !inCheck
&& ss->staticEval + 235 + 172 * lmrDepth <= alpha
&& thisThread->mainHistory[us][from_to(move)]
+ (*contHist[0])[movedPiece][to_sq(move)]
&& !ss->inCheck
&& ss->staticEval + 284 + 188 * lmrDepth <= alpha
&& (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)] < 25000)
+ (*contHist[3])[movedPiece][to_sq(move)]
+ (*contHist[5])[movedPiece][to_sq(move)] / 2 < 28388)
continue;
// Prune moves with negative SEE (~20 Elo)
if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 17)) * lmrDepth * lmrDepth)))
continue;
}
else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
else
{
// Capture history based pruning when the move doesn't give check
if ( !givesCheck
&& lmrDepth < 1
&& captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
continue;
// Futility pruning for captures
if ( !givesCheck
&& lmrDepth < 6
&& !(PvNode && abs(bestValue) < 2)
&& !ss->inCheck
&& ss->staticEval + 267 + 391 * lmrDepth + PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] <= alpha)
continue;
// See based pruning
if (!pos.see_ge(move, Value(-202) * depth)) // (~25 Elo)
continue;
}
}
// Step 14. Extensions (~75 Elo)
@@ -1048,16 +1053,16 @@ moves_loop: // When in check, search starts from here
&& tte->depth() >= depth - 3
&& pos.legal(move))
{
Value singularBeta = ttValue - 2 * depth;
Depth halfDepth = depth / 2;
Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
ss->excludedMove = move;
value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
ss->excludedMove = MOVE_NONE;
if (value < singularBeta)
{
extension = 1;
singularLMR = true;
singularQuietLMR = !ttCapture;
}
// Multi-cut pruning
@@ -1067,6 +1072,18 @@ moves_loop: // When in check, search starts from here
// a soft bound.
else if (singularBeta >= beta)
return singularBeta;
// If the eval of ttMove is greater than beta we try also if there is an other move that
// pushes it over beta, if so also produce a cutoff
else if (ttValue >= beta)
{
ss->excludedMove = move;
value = search<NonPV>(pos, ss, beta - 1, beta, (depth + 3) / 2, cutNode);
ss->excludedMove = MOVE_NONE;
if (value >= beta)
return beta;
}
}
// Check extension (~2 Elo)
@@ -1089,6 +1106,12 @@ moves_loop: // When in check, search starts from here
if (type_of(move) == CASTLING)
extension = 1;
// Late irreversible move extension
if ( move == ttMove
&& pos.rule50_count() > 80
&& (captureOrPromotion || type_of(movedPiece) == PAWN))
extension = 2;
// Add extension to new depth
newDepth += extension;
@@ -1104,7 +1127,7 @@ moves_loop: // When in check, search starts from here
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[inCheck]
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[movedPiece]
[to_sq(move)];
@@ -1115,18 +1138,18 @@ moves_loop: // When in check, search starts from here
// Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
// re-searched at full depth.
if ( depth >= 3
&& moveCount > 1 + rootNode + (rootNode && bestValue < alpha)
&& moveCount > 1 + 2 * rootNode
&& (!rootNode || thisThread->best_move_count(move) == 0)
&& ( !captureOrPromotion
|| moveCountPruning
|| ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
|| cutNode
|| thisThread->ttHitAverage < 375 * ttHitAverageResolution * ttHitAverageWindow / 1024))
|| thisThread->ttHitAverage < 415 * TtHitAverageResolution * TtHitAverageWindow / 1024))
{
Depth r = reduction(improving, depth, moveCount);
// Decrease reduction if the ttHit running average is large
if (thisThread->ttHitAverage > 500 * ttHitAverageResolution * ttHitAverageWindow / 1024)
if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024)
r--;
// Reduction if other threads are searching this position.
@@ -1137,13 +1160,16 @@ moves_loop: // When in check, search starts from here
if (ttPv)
r -= 2;
if (moveCountPruning && !formerPv)
r++;
// Decrease reduction if opponent's move count is high (~5 Elo)
if ((ss-1)->moveCount > 14)
if ((ss-1)->moveCount > 13)
r--;
// Decrease reduction if ttMove has been singularly extended (~3 Elo)
if (singularLMR)
r -= 2;
if (singularQuietLMR)
r -= 1 + formerPv;
if (!captureOrPromotion)
{
@@ -1160,44 +1186,50 @@ moves_loop: // When in check, search starts from here
// hence break make_move(). (~2 Elo)
else if ( type_of(move) == NORMAL
&& !pos.see_ge(reverse_move(move)))
r -= 2;
r -= 2 + ttPv - (type_of(movedPiece) == PAWN);
ss->statScore = thisThread->mainHistory[us][from_to(move)]
+ (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)]
- 4926;
// Reset statScore to zero if negative and most stats shows >= 0
if ( ss->statScore < 0
&& (*contHist[0])[movedPiece][to_sq(move)] >= 0
&& (*contHist[1])[movedPiece][to_sq(move)] >= 0
&& thisThread->mainHistory[us][from_to(move)] >= 0)
ss->statScore = 0;
- 4826;
// Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
if (ss->statScore >= -102 && (ss-1)->statScore < -114)
if (ss->statScore >= -100 && (ss-1)->statScore < -112)
r--;
else if ((ss-1)->statScore >= -116 && ss->statScore < -154)
else if ((ss-1)->statScore >= -125 && ss->statScore < -138)
r++;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 16384;
r -= ss->statScore / 14615;
}
else
{
// Increase reduction for captures/promotions if late move and at low depth
if (depth < 8 && moveCount > 2)
r++;
// Unless giving check, this capture is likely bad
if ( !givesCheck
&& ss->staticEval + PieceValue[EG][pos.captured_piece()] + 211 * depth <= alpha)
r++;
}
// Increase reduction for captures/promotions if late move and at low depth
else if (depth < 8 && moveCount > 2)
r++;
Depth d = clamp(newDepth - r, 1, newDepth);
Depth d = Utility::clamp(newDepth - r, 1, newDepth);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
doFullDepthSearch = (value > alpha && d != newDepth), didLMR = true;
doFullDepthSearch = value > alpha && d != newDepth;
didLMR = true;
}
else
doFullDepthSearch = !PvNode || moveCount > 1, didLMR = false;
{
doFullDepthSearch = !PvNode || moveCount > 1;
didLMR = false;
}
// Step 17. Full depth search when LMR is skipped or fails high
if (doFullDepthSearch)
@@ -1314,11 +1346,11 @@ moves_loop: // When in check, search starts from here
// must be a mate or a stalemate. If we are in a singular extension search then
// return a fail low score.
assert(moveCount || !inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
assert(moveCount || !ss->inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
if (!moveCount)
bestValue = excludedMove ? alpha
: inCheck ? mated_in(ss->ply) : VALUE_DRAW;
: ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW;
else if (bestMove)
update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq,
@@ -1332,7 +1364,7 @@ moves_loop: // When in check, search starts from here
if (PvNode)
bestValue = std::min(bestValue, maxValue);
if (!excludedMove)
if (!excludedMove && !(rootNode && thisThread->pvIdx))
tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv,
bestValue >= beta ? BOUND_LOWER :
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
@@ -1362,7 +1394,7 @@ moves_loop: // When in check, search starts from here
Move ttMove, move, bestMove;
Depth ttDepth;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion, evasionPrunable;
bool ttHit, pvHit, givesCheck, captureOrPromotion;
int moveCount;
if (PvNode)
@@ -1375,20 +1407,20 @@ moves_loop: // When in check, search starts from here
Thread* thisThread = pos.this_thread();
(ss+1)->ply = ss->ply + 1;
bestMove = MOVE_NONE;
inCheck = pos.checkers();
ss->inCheck = pos.checkers();
moveCount = 0;
// Check for an immediate draw or maximum ply reached
if ( pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW;
return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos) : VALUE_DRAW;
assert(0 <= ss->ply && ss->ply < MAX_PLY);
// Decide whether or not to include checks: this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
ttDepth = ss->inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
: DEPTH_QS_NO_CHECKS;
// Transposition table lookup
posKey = pos.key();
@@ -1406,7 +1438,7 @@ moves_loop: // When in check, search starts from here
return ttValue;
// Evaluate the position statically
if (inCheck)
if (ss->inCheck)
{
ss->staticEval = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
@@ -1427,13 +1459,13 @@ moves_loop: // When in check, search starts from here
else
ss->staticEval = bestValue =
(ss-1)->currentMove != MOVE_NULL ? evaluate(pos)
: -(ss-1)->staticEval + 2 * Eval::Tempo;
: -(ss-1)->staticEval + 2 * Tempo;
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
{
if (!ttHit)
tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, BOUND_LOWER,
tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER,
DEPTH_NONE, MOVE_NONE, ss->staticEval);
return bestValue;
@@ -1442,7 +1474,7 @@ moves_loop: // When in check, search starts from here
if (PvNode && bestValue > alpha)
alpha = bestValue;
futilityBase = bestValue + 154;
futilityBase = bestValue + 141;
}
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
@@ -1469,7 +1501,7 @@ moves_loop: // When in check, search starts from here
moveCount++;
// Futility pruning
if ( !inCheck
if ( !ss->inCheck
&& !givesCheck
&& futilityBase > -VALUE_KNOWN_WIN
&& !pos.advanced_pawn_push(move))
@@ -1491,14 +1523,8 @@ moves_loop: // When in check, search starts from here
}
}
// Detect non-capture evasions that are candidates to be pruned
evasionPrunable = inCheck
&& (depth != 0 || moveCount > 2)
&& bestValue > VALUE_MATED_IN_MAX_PLY
&& !pos.capture(move);
// Don't search moves with negative SEE values
if ( (!inCheck || evasionPrunable) && !pos.see_ge(move))
if ( !ss->inCheck && !pos.see_ge(move))
continue;
// Speculative prefetch as early as possible
@@ -1512,7 +1538,7 @@ moves_loop: // When in check, search starts from here
}
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[inCheck]
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[pos.moved_piece(move)]
[to_sq(move)];
@@ -1546,7 +1572,7 @@ moves_loop: // When in check, search starts from here
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
if (inCheck && bestValue == -VALUE_INFINITE)
if (ss->inCheck && bestValue == -VALUE_INFINITE)
return mated_in(ss->ply); // Plies to mate from the root
tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit,
@@ -1560,28 +1586,47 @@ moves_loop: // When in check, search starts from here
}
// value_to_tt() adjusts a mate score from "plies to mate from the root" to
// "plies to mate from the current position". Non-mate scores are unchanged.
// value_to_tt() adjusts a mate or TB score from "plies to mate from the root" to
// "plies to mate from the current position". standard scores are unchanged.
// The function is called before storing a value in the transposition table.
Value value_to_tt(Value v, int ply) {
assert(v != VALUE_NONE);
return v >= VALUE_MATE_IN_MAX_PLY ? v + ply
: v <= VALUE_MATED_IN_MAX_PLY ? v - ply : v;
return v >= VALUE_TB_WIN_IN_MAX_PLY ? v + ply
: v <= VALUE_TB_LOSS_IN_MAX_PLY ? v - ply : v;
}
// value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score
// value_from_tt() is the inverse of value_to_tt(): It adjusts a mate or TB score
// from the transposition table (which refers to the plies to mate/be mated
// from current position) to "plies to mate/be mated from the root".
// from current position) to "plies to mate/be mated (TB win/loss) from the root".
// However, for mate scores, to avoid potentially false mate scores related to the 50 moves rule,
// and the graph history interaction, return an optimal TB score instead.
Value value_from_tt(Value v, int ply, int r50c) {
return v == VALUE_NONE ? VALUE_NONE
: v >= VALUE_MATE_IN_MAX_PLY ? VALUE_MATE - v > 99 - r50c ? VALUE_MATE_IN_MAX_PLY : v - ply
: v <= VALUE_MATED_IN_MAX_PLY ? VALUE_MATE + v > 99 - r50c ? VALUE_MATED_IN_MAX_PLY : v + ply : v;
if (v == VALUE_NONE)
return VALUE_NONE;
if (v >= VALUE_TB_WIN_IN_MAX_PLY) // TB win or better
{
if (v >= VALUE_MATE_IN_MAX_PLY && VALUE_MATE - v > 99 - r50c)
return VALUE_MATE_IN_MAX_PLY - 1; // do not return a potentially false mate score
return v - ply;
}
if (v <= VALUE_TB_LOSS_IN_MAX_PLY) // TB loss or worse
{
if (v <= VALUE_MATED_IN_MAX_PLY && VALUE_MATE + v > 99 - r50c)
return VALUE_MATED_IN_MAX_PLY + 1; // do not return a potentially false mate score
return v + ply;
}
return v;
}
@@ -1613,7 +1658,7 @@ moves_loop: // When in check, search starts from here
if (!pos.capture_or_promotion(bestMove))
{
update_quiet_stats(pos, ss, bestMove, bonus2);
update_quiet_stats(pos, ss, bestMove, bonus2, depth);
// Decrease all the non-best quiet moves
for (int i = 0; i < quietCount; ++i)
@@ -1641,19 +1686,23 @@ moves_loop: // When in check, search starts from here
// update_continuation_histories() updates histories of the move pairs formed
// by moves at ply -1, -2, and -4 with current move.
// by moves at ply -1, -2, -4, and -6 with current move.
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
for (int i : {1, 2, 4, 6})
{
if (ss->inCheck && i > 2)
break;
if (is_ok((ss-i)->currentMove))
(*(ss-i)->continuationHistory)[pc][to] << bonus;
}
}
// update_quiet_stats() updates move sorting heuristics
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus) {
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth) {
if (ss->killers[0] != move)
{
@@ -1674,6 +1723,9 @@ moves_loop: // When in check, search starts from here
Square prevSq = to_sq((ss-1)->currentMove);
thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
if (depth > 11 && ss->ply < MAX_LPH)
thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 6);
}
// When playing with strength handicap, choose best move among a set of RootMoves
@@ -1767,7 +1819,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
Depth d = updated ? depth : depth - 1;
Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore;
bool tb = TB::RootInTB && abs(v) < VALUE_MATE - MAX_PLY;
bool tb = TB::RootInTB && abs(v) < VALUE_MATE_IN_MAX_PLY;
v = tb ? rootMoves[i].tbScore : v;
if (ss.rdbuf()->in_avail()) // Not at first line