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Merge branch 'master' into clusterMergeMaster8

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This commit is contained in:
Joost VandeVondele
2020-01-18 08:26:43 +01:00
parent 8a9d269855 c3483fa9a7
commit 8ec5faa46e
42 changed files with 771 additions and 604 deletions
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src/search.cpp
+208 -164
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@@ -2,7 +2,7 @@
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -62,10 +62,13 @@ namespace {
// Different node types, used as a template parameter
enum NodeType { NonPV, PV };
constexpr uint64_t ttHitAverageWindow = 4096;
constexpr uint64_t ttHitAverageResolution = 1024;
// Razor and futility margins
constexpr int RazorMargin = 661;
constexpr int RazorMargin = 531;
Value futility_margin(Depth d, bool improving) {
return Value(198 * (d - improving));
return Value(217 * (d - improving));
}
// Reductions lookup table, initialized at startup
@@ -73,16 +76,16 @@ namespace {
Depth reduction(bool i, Depth d, int mn) {
int r = Reductions[d] * Reductions[mn];
return (r + 520) / 1024 + (!i && r > 999);
return (r + 511) / 1024 + (!i && r > 1007);
}
constexpr int futility_move_count(bool improving, int depth) {
return (5 + depth * depth) * (1 + improving) / 2;
constexpr int futility_move_count(bool improving, Depth depth) {
return (5 + depth * depth) * (1 + improving) / 2 - 1;
}
// History and stats update bonus, based on depth
int stat_bonus(Depth d) {
return d > 17 ? -8 : 22 * d * d + 151 * d - 140;
return d > 15 ? -8 : 19 * d * d + 155 * d - 132;
}
// Add a small random component to draw evaluations to avoid 3fold-blindness
@@ -151,11 +154,12 @@ namespace {
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = 0);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
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, Move* quiets, int quietCount, int bonus);
void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCount, int bonus);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus);
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);
// perft() is our utility to verify move generation. All the leaf nodes up
// to the given depth are generated and counted, and the sum is returned.
@@ -191,7 +195,7 @@ namespace {
void Search::init() {
for (int i = 1; i < MAX_MOVES; ++i)
Reductions[i] = int((23.4 + std::log(Threads.size()) / 2) * std::log(i));
Reductions[i] = int((24.8 + std::log(Threads.size()) / 2) * std::log(i));
}
@@ -361,6 +365,7 @@ void Thread::search() {
MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
double timeReduction = 1, totBestMoveChanges = 0;
Color us = rootPos.side_to_move();
int iterIdx = 0;
std::memset(ss-7, 0, 10 * sizeof(Stack));
for (int i = 7; i > 0; i--)
@@ -371,6 +376,16 @@ void Thread::search() {
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
if (mainThread)
{
if (mainThread->previousScore == 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;
}
size_t multiPV = Options["MultiPV"];
// Pick integer skill levels, but non-deterministically round up or down
@@ -392,6 +407,7 @@ void Thread::search() {
multiPV = std::max(multiPV, (size_t)4);
multiPV = std::min(multiPV, rootMoves.size());
ttHitAverage = ttHitAverageWindow * ttHitAverageResolution / 2;
int ct = int(Options["Contempt"]) * PawnValueEg / 100; // From centipawns
@@ -407,6 +423,8 @@ void Thread::search() {
contempt = (us == WHITE ? make_score(ct, ct / 2)
: -make_score(ct, ct / 2));
int searchAgainCounter = 0;
// Iterative deepening loop until requested to stop or the target depth is reached
while ( ++rootDepth < MAX_PLY
&& !Threads.stop
@@ -425,6 +443,9 @@ void Thread::search() {
size_t pvFirst = 0;
pvLast = 0;
if (!Threads.increaseDepth)
searchAgainCounter++;
// MultiPV loop. We perform a full root search for each PV line
for (pvIdx = 0; pvIdx < multiPV && !Threads.stop; ++pvIdx)
{
@@ -443,12 +464,12 @@ void Thread::search() {
if (rootDepth >= 4)
{
Value previousScore = rootMoves[pvIdx].previousScore;
delta = Value(21 + abs(previousScore) / 128);
delta = Value(21 + abs(previousScore) / 256);
alpha = std::max(previousScore - delta,-VALUE_INFINITE);
beta = std::min(previousScore + delta, VALUE_INFINITE);
// Adjust contempt based on root move's previousScore (dynamic contempt)
int dct = ct + 86 * previousScore / (abs(previousScore) + 176);
int dct = ct + (102 - ct / 2) * previousScore / (abs(previousScore) + 157);
contempt = (us == WHITE ? make_score(dct, dct / 2)
: -make_score(dct, dct / 2));
@@ -460,7 +481,7 @@ void Thread::search() {
int failedHighCnt = 0;
while (true)
{
Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt);
Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - searchAgainCounter);
bestValue = ::search<PV>(rootPos, ss, alpha, beta, adjustedDepth, false);
// Bring the best move to the front. It is critical that sorting
@@ -553,12 +574,13 @@ void Thread::search() {
&& !Threads.stop
&& !mainThread->stopOnPonderhit)
{
double fallingEval = (354 + 10 * (mainThread->previousScore - bestValue)) / 692.0;
double fallingEval = (332 + 6 * (mainThread->previousScore - bestValue)
+ 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 704.0;
fallingEval = clamp(fallingEval, 0.5, 1.5);
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.97 : 0.98;
double reduction = (1.36 + mainThread->previousTimeReduction) / (2.29 * timeReduction);
timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.94 : 0.91;
double reduction = (1.41 + mainThread->previousTimeReduction) / (2.27 * timeReduction);
// Use part of the gained time from a previous stable move for the current move
for (Thread* th : Threads)
@@ -579,7 +601,16 @@ void Thread::search() {
else
Threads.stop = true;
}
else if ( Threads.increaseDepth
&& !mainThread->ponder
&& Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6)
Threads.increaseDepth = false;
else
Threads.increaseDepth = true;
}
mainThread->iterValue[iterIdx] = bestValue;
iterIdx = (iterIdx + 1) & 3;
}
if (!mainThread)
@@ -632,17 +663,17 @@ namespace {
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth;
Value bestValue, value, ttValue, eval, maxValue;
bool ttHit, ttPv, inCheck, givesCheck, improving, doLMR, priorCapture;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
Piece movedPiece;
int moveCount, captureCount, quietCount, singularLMR;
int moveCount, captureCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
priorCapture = pos.captured_piece();
Color us = pos.side_to_move();
moveCount = captureCount = quietCount = singularLMR = ss->moveCount = 0;
moveCount = captureCount = quietCount = ss->moveCount = 0;
bestValue = -VALUE_INFINITE;
maxValue = VALUE_INFINITE;
@@ -698,10 +729,13 @@ namespace {
excludedMove = ss->excludedMove;
posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
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());
// thisThread->ttHitAverage can be used to approximate the running average of ttHit
thisThread->ttHitAverage = (ttHitAverageWindow - 1) * thisThread->ttHitAverage / ttHitAverageWindow
+ ttHitAverageResolution * ttHit;
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
@@ -717,7 +751,7 @@ namespace {
if (ttValue >= beta)
{
if (!pos.capture_or_promotion(ttMove))
update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
update_quiet_stats(pos, ss, ttMove, stat_bonus(depth));
// Extra penalty for early quiet moves of the previous ply
if ((ss-1)->moveCount <= 2 && !priorCapture)
@@ -731,7 +765,9 @@ namespace {
update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
return ttValue;
if (pos.rule50_count() < 90)
return ttValue;
}
// Step 5. Tablebases probe
@@ -824,18 +860,18 @@ namespace {
eval);
}
// Step 7. Razoring (~2 Elo)
// Step 7. Razoring (~1 Elo)
if ( !rootNode // The required rootNode PV handling is not available in qsearch
&& depth < 2
&& eval <= alpha - RazorMargin)
return qsearch<NT>(pos, ss, alpha, beta);
improving = ss->staticEval >= (ss-2)->staticEval
|| (ss-2)->staticEval == VALUE_NONE;
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 (~30 Elo)
// Step 8. Futility pruning: child node (~50 Elo)
if ( !PvNode
&& depth < 7
&& depth < 6
&& eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;
@@ -843,10 +879,10 @@ namespace {
// Step 9. Null move search with verification search (~40 Elo)
if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 22661
&& (ss-1)->statScore < 23397
&& eval >= beta
&& eval >= ss->staticEval
&& ss->staticEval >= beta - 33 * depth + 299 - improving * 30
&& ss->staticEval >= beta - 32 * depth + 292 - improving * 30
&& !excludedMove
&& pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -854,7 +890,7 @@ namespace {
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
Depth R = (835 + 70 * depth) / 256 + std::min(int(eval - beta) / 185, 3);
Depth R = (854 + 68 * depth) / 258 + std::min(int(eval - beta) / 192, 3);
ss->currentMove = MOVE_NULL;
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
@@ -897,7 +933,7 @@ namespace {
&& depth >= 5
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
Value raisedBeta = std::min(beta + 191 - 46 * improving, VALUE_INFINITE);
Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE);
MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory);
int probCutCount = 0;
@@ -933,13 +969,13 @@ namespace {
}
}
// Step 11. Internal iterative deepening (~2 Elo)
// Step 11. Internal iterative deepening (~1 Elo)
if (depth >= 7 && !ttMove)
{
search<NT>(pos, ss, alpha, beta, depth - 7, cutNode);
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
ttMove = ttHit ? tte->move() : MOVE_NONE;
}
@@ -958,7 +994,7 @@ moves_loop: // When in check, search starts from here
ss->killers);
value = bestValue;
moveCountPruning = false;
singularLMR = moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove);
// Mark this node as being searched
@@ -995,9 +1031,50 @@ moves_loop: // When in check, search starts from here
movedPiece = pos.moved_piece(move);
givesCheck = pos.gives_check(move);
// Step 13. Extensions (~70 Elo)
// Calculate new depth for this move
newDepth = depth - 1;
// Singular extension search (~60 Elo). If all moves but one fail low on a
// Step 13. Pruning at shallow depth (~200 Elo)
if ( !rootNode
&& pos.non_pawn_material(us)
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
moveCountPruning = moveCount >= futility_move_count(improving, depth);
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
&& (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
continue;
// 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)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)] < 25000)
continue;
// Prune moves with negative SEE (~20 Elo)
if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
continue;
}
else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
continue;
}
// Step 14. Extensions (~75 Elo)
// Singular extension search (~70 Elo). If all moves but one fail low on a
// search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
// then that move is singular and should be extended. To verify this we do
// a reduced search on all the other moves but the ttMove and if the
@@ -1021,10 +1098,7 @@ moves_loop: // When in check, search starts from here
if (value < singularBeta)
{
extension = 1;
singularLMR++;
if (value < singularBeta - std::min(4 * depth, 36))
singularLMR++;
singularLMR = true;
}
// Multi-cut pruning
@@ -1032,8 +1106,7 @@ moves_loop: // When in check, search starts from here
// search without the ttMove. So we assume this expected Cut-node is not singular,
// that multiple moves fail high, and we can prune the whole subtree by returning
// a soft bound.
else if ( eval >= beta
&& singularBeta >= beta)
else if (singularBeta >= beta)
return singularBeta;
}
@@ -1042,65 +1115,23 @@ moves_loop: // When in check, search starts from here
&& (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move)))
extension = 1;
// Shuffle extension
else if ( PvNode
&& pos.rule50_count() > 18
&& depth < 3
&& ++thisThread->shuffleExts < thisThread->nodes.load(std::memory_order_relaxed) / 4) // To avoid too many extensions
extension = 1;
// Passed pawn extension
else if ( move == ss->killers[0]
&& pos.advanced_pawn_push(move)
&& pos.pawn_passed(us, to_sq(move)))
extension = 1;
// Last captures extension
else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg
&& pos.non_pawn_material() <= 2 * RookValueMg)
extension = 1;
// Castling extension
if (type_of(move) == CASTLING)
extension = 1;
// Calculate new depth for this move
newDepth = depth - 1 + extension;
// Step 14. Pruning at shallow depth (~170 Elo)
if ( !rootNode
&& pos.non_pawn_material(us)
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
moveCountPruning = moveCount >= futility_move_count(improving, depth);
if ( !captureOrPromotion
&& !givesCheck
&& (!pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
{
// Move count based pruning
if (moveCountPruning)
continue;
// 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
&& (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
continue;
// Futility pruning: parent node (~2 Elo)
if ( lmrDepth < 6
&& !inCheck
&& ss->staticEval + 250 + 211 * lmrDepth <= alpha)
continue;
// Prune moves with negative SEE (~10 Elo)
if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
continue;
}
else if ( !(givesCheck && extension)
&& !pos.see_ge(move, Value(-199) * depth)) // (~20 Elo)
continue;
}
// Add extension to new depth
newDepth += extension;
// Speculative prefetch as early as possible
prefetch(TT.first_entry(pos.key_after(move)));
@@ -1122,46 +1153,52 @@ moves_loop: // When in check, search starts from here
// Step 15. Make the move
pos.do_move(move, st, givesCheck);
// Step 16. Reduced depth search (LMR). If the move fails high it will be
// 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 + 2 * rootNode
&& moveCount > 1 + rootNode + (rootNode && bestValue < alpha)
&& (!rootNode || thisThread->best_move_count(move) == 0)
&& ( !captureOrPromotion
|| moveCountPruning
|| ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
|| cutNode))
|| cutNode
|| thisThread->ttHitAverage < 375 * 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)
r--;
// Reduction if other threads are searching this position.
if (th.marked())
r++;
// Decrease reduction if position is or has been on the PV
// Decrease reduction if position is or has been on the PV (~10 Elo)
if (ttPv)
r -= 2;
// Decrease reduction if opponent's move count is high (~10 Elo)
if ((ss-1)->moveCount > 15)
// Decrease reduction if opponent's move count is high (~5 Elo)
if ((ss-1)->moveCount > 14)
r--;
// Decrease reduction if ttMove has been singularly extended
r -= singularLMR;
// Decrease reduction if ttMove has been singularly extended (~3 Elo)
if (singularLMR)
r -= 2;
if (!captureOrPromotion)
{
// Increase reduction if ttMove is a capture (~0 Elo)
// Increase reduction if ttMove is a capture (~5 Elo)
if (ttCapture)
r++;
// Increase reduction for cut nodes (~5 Elo)
// Increase reduction for cut nodes (~10 Elo)
if (cutNode)
r += 2;
// Decrease reduction for moves that escape a capture. Filter out
// castling moves, because they are coded as "king captures rook" and
// hence break make_move(). (~5 Elo)
// hence break make_move(). (~2 Elo)
else if ( type_of(move) == NORMAL
&& !pos.see_ge(reverse_move(move)))
r -= 2;
@@ -1170,7 +1207,7 @@ moves_loop: // When in check, search starts from here
+ (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)]
- 4729;
- 4926;
// Reset statScore to zero if negative and most stats shows >= 0
if ( ss->statScore < 0
@@ -1180,31 +1217,35 @@ moves_loop: // When in check, search starts from here
ss->statScore = 0;
// Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
if (ss->statScore >= -99 && (ss-1)->statScore < -116)
if (ss->statScore >= -102 && (ss-1)->statScore < -114)
r--;
else if ((ss-1)->statScore >= -117 && ss->statScore < -144)
else if ((ss-1)->statScore >= -116 && ss->statScore < -154)
r++;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 16384;
}
// 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);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
doFullDepthSearch = (value > alpha && d != newDepth), doLMR = true;
doFullDepthSearch = (value > alpha && d != newDepth), didLMR = true;
}
else
doFullDepthSearch = !PvNode || moveCount > 1, doLMR = false;
doFullDepthSearch = !PvNode || moveCount > 1, didLMR = false;
// Step 17. Full depth search when LMR is skipped or fails high
if (doFullDepthSearch)
{
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
if (doLMR && !captureOrPromotion)
if (didLMR && !captureOrPromotion)
{
int bonus = value > alpha ? stat_bonus(newDepth)
: -stat_bonus(newDepth);
@@ -1319,21 +1360,11 @@ moves_loop: // When in check, search starts from here
if (!moveCount)
bestValue = excludedMove ? alpha
: inCheck ? mated_in(ss->ply) : VALUE_DRAW;
else if (bestMove)
{
// Quiet best move: update move sorting heuristics
if (!pos.capture_or_promotion(bestMove))
update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount,
stat_bonus(depth + (bestValue > beta + PawnValueMg)));
update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq,
quietsSearched, quietCount, capturesSearched, captureCount, depth);
update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth + 1));
// Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
if ( ((ss-1)->moveCount == 1 || ((ss-1)->currentMove == (ss-1)->killers[0]))
&& !priorCapture)
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + 1));
}
// Bonus for prior countermove that caused the fail low
else if ( (depth >= 3 || PvNode)
&& !priorCapture)
@@ -1404,7 +1435,7 @@ moves_loop: // When in check, search starts from here
// Transposition table lookup
posKey = pos.key();
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
ttMove = ttHit ? tte->move() : MOVE_NONE;
pvHit = ttHit && tte->is_pv();
@@ -1454,7 +1485,7 @@ moves_loop: // When in check, search starts from here
if (PvNode && bestValue > alpha)
alpha = bestValue;
futilityBase = bestValue + 153;
futilityBase = bestValue + 154;
}
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
@@ -1510,9 +1541,7 @@ moves_loop: // When in check, search starts from here
&& !pos.capture(move);
// Don't search moves with negative SEE values
if ( (!inCheck || evasionPrunable)
&& (!givesCheck || !(pos.blockers_for_king(~pos.side_to_move()) & from_sq(move)))
&& !pos.see_ge(move))
if ( (!inCheck || evasionPrunable) && !pos.see_ge(move))
continue;
// Speculative prefetch as early as possible
@@ -1592,11 +1621,11 @@ moves_loop: // When in check, search starts from here
// 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".
Value value_from_tt(Value v, int ply) {
Value value_from_tt(Value v, int ply, int r50c) {
return v == VALUE_NONE ? VALUE_NONE
: v >= VALUE_MATE_IN_MAX_PLY ? v - ply
: v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v;
: 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;
}
@@ -1610,6 +1639,51 @@ moves_loop: // When in check, search starts from here
}
// update_all_stats() updates stats at the end of search() when a bestMove is found
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) {
int bonus1, bonus2;
Color us = pos.side_to_move();
Thread* thisThread = pos.this_thread();
CapturePieceToHistory& captureHistory = thisThread->captureHistory;
Piece moved_piece = pos.moved_piece(bestMove);
PieceType captured = type_of(pos.piece_on(to_sq(bestMove)));
bonus1 = stat_bonus(depth + 1);
bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus
: stat_bonus(depth); // smaller bonus
if (!pos.capture_or_promotion(bestMove))
{
update_quiet_stats(pos, ss, bestMove, bonus2);
// Decrease all the non-best quiet moves
for (int i = 0; i < quietCount; ++i)
{
thisThread->mainHistory[us][from_to(quietsSearched[i])] << -bonus2;
update_continuation_histories(ss, pos.moved_piece(quietsSearched[i]), to_sq(quietsSearched[i]), -bonus2);
}
}
else
captureHistory[moved_piece][to_sq(bestMove)][captured] << bonus1;
// Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
if ( ((ss-1)->moveCount == 1 || ((ss-1)->currentMove == (ss-1)->killers[0]))
&& !pos.captured_piece())
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -bonus1);
// Decrease all the non-best capture moves
for (int i = 0; i < captureCount; ++i)
{
moved_piece = pos.moved_piece(capturesSearched[i]);
captured = type_of(pos.piece_on(to_sq(capturesSearched[i])));
captureHistory[moved_piece][to_sq(capturesSearched[i])][captured] << -bonus1;
}
}
// update_continuation_histories() updates histories of the move pairs formed
// by moves at ply -1, -2, and -4 with current move.
@@ -1621,32 +1695,9 @@ moves_loop: // When in check, search starts from here
}
// update_capture_stats() updates move sorting heuristics when a new capture best move is found
// update_quiet_stats() updates move sorting heuristics
void update_capture_stats(const Position& pos, Move move,
Move* captures, int captureCount, int bonus) {
CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
Piece moved_piece = pos.moved_piece(move);
PieceType captured = type_of(pos.piece_on(to_sq(move)));
if (pos.capture_or_promotion(move))
captureHistory[moved_piece][to_sq(move)][captured] << bonus;
// Decrease all the other played capture moves
for (int i = 0; i < captureCount; ++i)
{
moved_piece = pos.moved_piece(captures[i]);
captured = type_of(pos.piece_on(to_sq(captures[i])));
captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus;
}
}
// update_quiet_stats() updates move sorting heuristics when a new quiet best move is found
void update_quiet_stats(const Position& pos, Stack* ss, Move move,
Move* quiets, int quietCount, int bonus) {
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus) {
if (ss->killers[0] != move)
{
@@ -1667,13 +1718,6 @@ moves_loop: // When in check, search starts from here
Square prevSq = to_sq((ss-1)->currentMove);
thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
// Decrease all the other played quiet moves
for (int i = 0; i < quietCount; ++i)
{
thisThread->mainHistory[us][from_to(quiets[i])] << -bonus;
update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}
// When playing with strength handicap, choose best move among a set of RootMoves
@@ -1762,7 +1806,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
for (size_t i = 0; i < multiPV; ++i)
{
bool updated = (i <= pvIdx && rootMoves[i].score != -VALUE_INFINITE);
bool updated = rootMoves[i].score != -VALUE_INFINITE;
if (depth == 1 && !updated)
continue;