#include "misc.h"
#include "movegen.h"
#include "movepick.h"
+#include "position.h"
#include "search.h"
#include "timeman.h"
#include "thread.h"
SignalsType Signals;
LimitsType Limits;
- StateStackPtr SetupStates;
}
namespace Tablebases {
// Razoring and futility margin based on depth
const int razor_margin[4] = { 483, 570, 603, 554 };
- Value futility_margin(Depth d) { return Value(200 * d); }
+ Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
// Futility and reductions lookup tables, initialized at startup
- int FutilityMoveCounts[2][16]; // [improving][depth]
- Depth Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
+ int FutilityMoveCounts[2][16]; // [improving][depth]
+ int Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
template <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
- return Reductions[PvNode][i][std::min(d, 63 * ONE_PLY)][std::min(mn, 63)];
+ return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY;
}
// Skill structure is used to implement strength limit
std::copy(newPv.begin(), newPv.begin() + 3, pv);
StateInfo st[2];
- pos.do_move(newPv[0], st[0], pos.gives_check(newPv[0], CheckInfo(pos)));
- pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1], CheckInfo(pos)));
+ pos.do_move(newPv[0], st[0], pos.gives_check(newPv[0]));
+ pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1]));
expectedPosKey = pos.key();
pos.undo_move(newPv[1]);
pos.undo_move(newPv[0]);
EasyMoveManager EasyMove;
Value DrawValue[COLOR_NB];
- CounterMoveHistoryStats CounterMoveHistory;
template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
void update_pv(Move* pv, Move move, Move* childPv);
- void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
+ void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus);
+ void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, Value bonus);
void check_time();
} // namespace
void Search::init() {
- const bool PV=true;
-
for (int imp = 0; imp <= 1; ++imp)
for (int d = 1; d < 64; ++d)
for (int mc = 1; mc < 64; ++mc)
if (r < 0.80)
continue;
- Reductions[!PV][imp][d][mc] = int(std::round(r)) * ONE_PLY;
- Reductions[PV][imp][d][mc] = std::max(Reductions[!PV][imp][d][mc] - ONE_PLY, DEPTH_ZERO);
-
+ Reductions[NonPV][imp][d][mc] = int(std::round(r));
+ Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0);
+
// Increase reduction for non-PV nodes when eval is not improving
- if (!imp && Reductions[!PV][imp][d][mc] >= 2 * ONE_PLY)
- Reductions[!PV][imp][d][mc] += ONE_PLY;
+ if (!imp && Reductions[NonPV][imp][d][mc] >= 2)
+ Reductions[NonPV][imp][d][mc]++;
}
for (int d = 0; d < 16; ++d)
void Search::clear() {
TT.clear();
- CounterMoveHistory.clear();
for (Thread* th : Threads)
{
th->history.clear();
th->counterMoves.clear();
+ th->fromTo.clear();
+ th->counterMoveHistory.clear();
}
Threads.main()->previousScore = VALUE_INFINITE;
StateInfo st;
uint64_t cnt, nodes = 0;
- CheckInfo ci(pos);
const bool leaf = (depth == 2 * ONE_PLY);
for (const auto& m : MoveList<LEGAL>(pos))
cnt = 1, nodes++;
else
{
- pos.do_move(m, st, pos.gives_check(m, ci));
+ pos.do_move(m, st, pos.gives_check(m));
cnt = leaf ? MoveList<LEGAL>(pos).size() : perft<false>(pos, depth - ONE_PLY);
nodes += cnt;
pos.undo_move(m);
DrawValue[ us] = VALUE_DRAW - Value(contempt);
DrawValue[~us] = VALUE_DRAW + Value(contempt);
- TB::Hits = 0;
- TB::RootInTB = false;
- TB::UseRule50 = Options["Syzygy50MoveRule"];
- TB::ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
- TB::Cardinality = Options["SyzygyProbeLimit"];
-
- // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality
- if (TB::Cardinality > TB::MaxCardinality)
- {
- TB::Cardinality = TB::MaxCardinality;
- TB::ProbeDepth = DEPTH_ZERO;
- }
-
if (rootMoves.empty())
{
rootMoves.push_back(RootMove(MOVE_NONE));
}
else
{
- if ( TB::Cardinality >= rootPos.count<ALL_PIECES>(WHITE)
- + rootPos.count<ALL_PIECES>(BLACK)
- && !rootPos.can_castle(ANY_CASTLING))
- {
- // If the current root position is in the tablebases, then RootMoves
- // contains only moves that preserve the draw or the win.
- TB::RootInTB = Tablebases::root_probe(rootPos, rootMoves, TB::Score);
-
- if (TB::RootInTB)
- TB::Cardinality = 0; // Do not probe tablebases during the search
-
- else // If DTZ tables are missing, use WDL tables as a fallback
- {
- // Filter out moves that do not preserve the draw or the win.
- TB::RootInTB = Tablebases::root_probe_wdl(rootPos, rootMoves, TB::Score);
-
- // Only probe during search if winning
- if (TB::Score <= VALUE_DRAW)
- TB::Cardinality = 0;
- }
-
- if (TB::RootInTB)
- {
- TB::Hits = rootMoves.size();
-
- if (!TB::UseRule50)
- TB::Score = TB::Score > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1
- : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
- : VALUE_DRAW;
- }
- }
-
for (Thread* th : Threads)
- {
- th->maxPly = 0;
- th->rootDepth = DEPTH_ZERO;
if (th != this)
- {
- th->rootPos = Position(rootPos, th);
- th->rootMoves = rootMoves;
th->start_searching();
- }
- }
Thread::search(); // Let's start searching!
}
Thread* bestThread = this;
if ( !this->easyMovePlayed
&& Options["MultiPV"] == 1
- && !Skill(Options["Skill Level"]).enabled())
+ && !Limits.depth
+ && !Skill(Options["Skill Level"]).enabled()
+ && rootMoves[0].pv[0] != MOVE_NONE)
{
for (Thread* th : Threads)
if ( th->completedDepth > bestThread->completedDepth
void Thread::search() {
- Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
+ Stack stack[MAX_PLY+7], *ss = stack+5; // To allow referencing (ss-5) and (ss+2)
Value bestValue, alpha, beta, delta;
Move easyMove = MOVE_NONE;
MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
- std::memset(ss-2, 0, 5 * sizeof(Stack));
+ std::memset(ss-5, 0, 8 * sizeof(Stack));
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
multiPV = std::min(multiPV, rootMoves.size());
- // Iterative deepening loop until requested to stop or the target depth is reached.
- while (++rootDepth < DEPTH_MAX && !Signals.stop && (!Limits.depth || rootDepth <= Limits.depth))
+ // Iterative deepening loop until requested to stop or the target depth is reached
+ while ( (rootDepth += ONE_PLY) < DEPTH_MAX
+ && !Signals.stop
+ && (!Limits.depth || Threads.main()->rootDepth / ONE_PLY <= Limits.depth))
{
// Set up the new depths for the helper threads skipping on average every
// 2nd ply (using a half-density matrix).
if (!mainThread)
{
const Row& row = HalfDensity[(idx - 1) % HalfDensitySize];
- if (row[(rootDepth + rootPos.game_ply()) % row.size()])
+ if (row[(rootDepth / ONE_PLY + rootPos.game_ply()) % row.size()])
continue;
}
// search the already searched PV lines are preserved.
std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.end());
- // Write PV back to the transposition table in case the relevant
- // entries have been overwritten during the search.
- for (size_t i = 0; i <= PVIdx; ++i)
- rootMoves[i].insert_pv_in_tt(rootPos);
-
// If search has been stopped, break immediately. Sorting and
// writing PV back to TT is safe because RootMoves is still
// valid, although it refers to the previous iteration.
std::stable_sort(rootMoves.begin(), rootMoves.begin() + PVIdx + 1);
if (!mainThread)
- break;
+ continue;
if (Signals.stop)
sync_cout << "info nodes " << Threads.nodes_searched()
// Stop the search if only one legal move is available, or if all
// of the available time has been used, or if we matched an easyMove
// from the previous search and just did a fast verification.
- const bool F[] = { !mainThread->failedLow,
- bestValue >= mainThread->previousScore };
+ const int F[] = { mainThread->failedLow,
+ bestValue - mainThread->previousScore };
- int improvingFactor = 640 - 160*F[0] - 126*F[1] - 124*F[0]*F[1];
+ int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1]));
double unstablePvFactor = 1 + mainThread->bestMoveChanges;
bool doEasyMove = rootMoves[0].pv[0] == easyMove
&& mainThread->bestMoveChanges < 0.03
- && Time.elapsed() > Time.optimum() * 25 / 204;
+ && Time.elapsed() > Time.optimum() * 5 / 42;
if ( rootMoves.size() == 1
- || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 634
- || (mainThread->easyMovePlayed = doEasyMove))
+ || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628
+ || (mainThread->easyMovePlayed = doEasyMove, doEasyMove))
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
assert(DEPTH_ZERO < depth && depth < DEPTH_MAX);
+ assert(!(PvNode && cutNode));
+ assert(depth / ONE_PLY * ONE_PLY == depth);
Move pv[MAX_PLY+1], quietsSearched[64];
StateInfo st;
TTEntry* tte;
Key posKey;
Move ttMove, move, excludedMove, bestMove;
- Depth extension, newDepth, predictedDepth;
- Value bestValue, value, ttValue, eval, nullValue, futilityValue;
+ Depth extension, newDepth;
+ Value bestValue, value, ttValue, eval, nullValue;
bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
- bool captureOrPromotion, doFullDepthSearch;
+ bool captureOrPromotion, doFullDepthSearch, moveCountPruning;
+ Piece moved_piece;
int moveCount, quietCount;
// Step 1. Initialize node
assert(0 <= ss->ply && ss->ply < MAX_PLY);
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
+ ss->counterMoves = nullptr;
(ss+1)->skipEarlyPruning = false;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
// 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 = excludedMove ? pos.exclusion_key() : pos.key();
+ posKey = pos.key() ^ Key(excludedMove);
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttMove = rootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0]
ss->currentMove = ttMove; // Can be MOVE_NONE
// If ttMove is quiet, update killers, history, counter move on TT hit
- if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove))
- update_stats(pos, ss, ttMove, depth, nullptr, 0);
+ if (ttValue >= beta && ttMove)
+ {
+ int d = depth / ONE_PLY;
+ if (!pos.capture_or_promotion(ttMove))
+ {
+ Value bonus = Value(d * d + 2 * d - 2);
+ update_stats(pos, ss, ttMove, nullptr, 0, bonus);
+ }
+
+ // Extra penalty for a quiet TT move in previous ply when it gets refuted
+ if ((ss-1)->moveCount == 1 && !pos.captured_piece())
+ {
+ Value penalty = Value(d * d + 4 * d + 1);
+ Square prevSq = to_sq((ss-1)->currentMove);
+ update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -penalty);
+ }
+ }
return ttValue;
}
// Step 6. Razoring (skipped when in check)
if ( !PvNode
&& depth < 4 * ONE_PLY
- && eval + razor_margin[depth] <= alpha
- && ttMove == MOVE_NONE)
+ && ttMove == MOVE_NONE
+ && eval + razor_margin[depth / ONE_PLY] <= alpha)
{
if ( depth <= ONE_PLY
&& eval + razor_margin[3 * ONE_PLY] <= alpha)
return qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO);
- Value ralpha = alpha - razor_margin[depth];
+ Value ralpha = alpha - razor_margin[depth / ONE_PLY];
Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
if (v <= ralpha)
return v;
// Step 8. Null move search with verification search (is omitted in PV nodes)
if ( !PvNode
- && depth >= 2 * ONE_PLY
&& eval >= beta
+ && (ss->staticEval >= beta - 35 * (depth / ONE_PLY - 6) || depth >= 13 * ONE_PLY)
&& pos.non_pawn_material(pos.side_to_move()))
{
ss->currentMove = MOVE_NULL;
+ ss->counterMoves = nullptr;
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
- Depth R = ((823 + 67 * depth) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
+ Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
pos.do_null_move(st);
(ss+1)->skipEarlyPruning = true;
}
// Step 9. ProbCut (skipped when in check)
- // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type])
- // and a reduced search returns a value much above beta, we can (almost)
- // safely prune the previous move.
+ // 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 * ONE_PLY
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
assert((ss-1)->currentMove != MOVE_NONE);
assert((ss-1)->currentMove != MOVE_NULL);
- MovePicker mp(pos, ttMove, thisThread->history, PieceValue[MG][pos.captured_piece_type()]);
- CheckInfo ci(pos);
+ MovePicker mp(pos, ttMove, rbeta - ss->staticEval);
while ((move = mp.next_move()) != MOVE_NONE)
- if (pos.legal(move, ci.pinned))
+ if (pos.legal(move))
{
ss->currentMove = move;
- pos.do_move(move, st, pos.gives_check(move, ci));
+ ss->counterMoves = &thisThread->counterMoveHistory[pos.moved_piece(move)][to_sq(move)];
+ pos.do_move(move, st, pos.gives_check(move));
value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
pos.undo_move(move);
if (value >= rbeta)
}
// Step 10. Internal iterative deepening (skipped when in check)
- if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY)
+ if ( depth >= 6 * ONE_PLY
&& !ttMove
&& (PvNode || ss->staticEval + 256 >= beta))
{
- Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
+ Depth d = (3 * depth / (4 * ONE_PLY) - 2) * ONE_PLY;
ss->skipEarlyPruning = true;
- search<NT>(pos, ss, alpha, beta, d, true);
+ search<NT>(pos, ss, alpha, beta, d, cutNode);
ss->skipEarlyPruning = false;
tte = TT.probe(posKey, ttHit);
moves_loop: // When in check search starts from here
- Square prevSq = to_sq((ss-1)->currentMove);
- Move cm = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
- const CounterMoveStats& cmh = CounterMoveHistory[pos.piece_on(prevSq)][prevSq];
+ const CounterMoveStats* cmh = (ss-1)->counterMoves;
+ const CounterMoveStats* fmh = (ss-2)->counterMoves;
+ const CounterMoveStats* fmh2 = (ss-4)->counterMoves;
- MovePicker mp(pos, ttMove, depth, thisThread->history, cmh, cm, ss);
- CheckInfo ci(pos);
+ MovePicker mp(pos, ttMove, depth, ss);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval
- || ss->staticEval == VALUE_NONE
+ /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */
||(ss-2)->staticEval == VALUE_NONE;
singularExtensionNode = !rootNode
&& depth >= 8 * ONE_PLY
&& ttMove != MOVE_NONE
- /* && ttValue != VALUE_NONE Already implicit in the next condition */
- && abs(ttValue) < VALUE_KNOWN_WIN
+ && ttValue != VALUE_NONE
&& !excludedMove // Recursive singular search is not allowed
&& (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
extension = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
+ moved_piece = pos.moved_piece(move);
+
+ givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
+ ? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move)
+ : pos.gives_check(move);
- givesCheck = type_of(move) == NORMAL && !ci.dcCandidates
- ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
- : pos.gives_check(move, ci);
+ moveCountPruning = depth < 16 * ONE_PLY
+ && moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
// Step 12. Extend checks
- if (givesCheck && pos.see_sign(move) >= VALUE_ZERO)
+ if ( givesCheck
+ && !moveCountPruning
+ && pos.see_sign(move) >= VALUE_ZERO)
extension = ONE_PLY;
// Singular extension search. If all moves but one fail low on a search of
if ( singularExtensionNode
&& move == ttMove
&& !extension
- && pos.legal(move, ci.pinned))
+ && pos.legal(move))
{
- Value rBeta = ttValue - 2 * depth / ONE_PLY;
+ Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
+ Depth d = (depth / (2 * ONE_PLY)) * ONE_PLY;
ss->excludedMove = move;
ss->skipEarlyPruning = true;
- value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, d, cutNode);
ss->skipEarlyPruning = false;
ss->excludedMove = MOVE_NONE;
newDepth = depth - ONE_PLY + extension;
// Step 13. Pruning at shallow depth
- if ( !rootNode
- && !captureOrPromotion
+ if ( !rootNode
&& !inCheck
- && !givesCheck
- && !pos.advanced_pawn_push(move)
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
- // Move count based pruning
- if ( depth < 16 * ONE_PLY
- && moveCount >= FutilityMoveCounts[improving][depth])
- continue;
+ if ( !captureOrPromotion
+ && !givesCheck
+ && !pos.advanced_pawn_push(move))
+ {
+ // Move count based pruning
+ if (moveCountPruning)
+ continue;
- // History based pruning
- if ( depth <= 4 * ONE_PLY
- && move != ss->killers[0]
- && thisThread->history[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO
- && cmh[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO)
- continue;
+ // Reduced depth of the next LMR search
+ int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
- predictedDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
+ // Countermoves based pruning
+ if ( lmrDepth < 3
+ && (!cmh || (*cmh )[moved_piece][to_sq(move)] < VALUE_ZERO)
+ && (!fmh || (*fmh )[moved_piece][to_sq(move)] < VALUE_ZERO)
+ && (!fmh2 || (*fmh2)[moved_piece][to_sq(move)] < VALUE_ZERO || (cmh && fmh)))
+ continue;
- // Futility pruning: parent node
- if (predictedDepth < 7 * ONE_PLY)
- {
- futilityValue = ss->staticEval + futility_margin(predictedDepth) + 256;
+ // Futility pruning: parent node
+ if ( lmrDepth < 7
+ && ss->staticEval + 256 + 200 * lmrDepth <= alpha)
+ continue;
- if (futilityValue <= alpha)
- {
- bestValue = std::max(bestValue, futilityValue);
+ // Prune moves with negative SEE
+ if ( lmrDepth < 8
+ && pos.see_sign(move) < Value(-35 * lmrDepth * lmrDepth))
continue;
- }
}
-
- // Prune moves with negative SEE at low depths
- if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
- continue;
+ else if ( depth < 7 * ONE_PLY
+ && pos.see_sign(move) < Value(-35 * depth / ONE_PLY * depth / ONE_PLY))
+ continue;
}
// Speculative prefetch as early as possible
prefetch(TT.first_entry(pos.key_after(move)));
// Check for legality just before making the move
- if (!rootNode && !pos.legal(move, ci.pinned))
+ if (!rootNode && !pos.legal(move))
{
ss->moveCount = --moveCount;
continue;
}
ss->currentMove = move;
+ ss->counterMoves = &thisThread->counterMoveHistory[moved_piece][to_sq(move)];
// Step 14. Make the move
pos.do_move(move, st, givesCheck);
// re-searched at full depth.
if ( depth >= 3 * ONE_PLY
&& moveCount > 1
- && !captureOrPromotion)
+ && (!captureOrPromotion || moveCountPruning))
{
Depth r = reduction<PvNode>(improving, depth, moveCount);
- // Increase reduction for cut nodes and moves with a bad history
- if ( (!PvNode && cutNode)
- || ( thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
- && cmh[pos.piece_on(to_sq(move))][to_sq(move)] <= VALUE_ZERO))
- r += ONE_PLY;
-
- // Decrease/increase reduction for moves with a good/bad history
- int rHist = ( thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)]
- + cmh[pos.piece_on(to_sq(move))][to_sq(move)]) / 14980;
- r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY);
-
- // 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(). Also use see() instead of see_sign(),
- // because the destination square is empty.
- if ( r
- && type_of(move) == NORMAL
- && type_of(pos.piece_on(to_sq(move))) != PAWN
- && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO)
- r = std::max(DEPTH_ZERO, r - ONE_PLY);
+ if (captureOrPromotion)
+ r -= r ? ONE_PLY : DEPTH_ZERO;
+ else
+ {
+ // Increase reduction for cut nodes
+ if (cutNode)
+ r += 2 * ONE_PLY;
+
+ // 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(). Also use see() instead of see_sign(),
+ // because the destination square is empty.
+ else if ( type_of(move) == NORMAL
+ && type_of(pos.piece_on(to_sq(move))) != PAWN
+ && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO)
+ r -= 2 * ONE_PLY;
+
+ // Decrease/increase reduction for moves with a good/bad history
+ Value val = thisThread->history[moved_piece][to_sq(move)]
+ + (cmh ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
+ + (fmh ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
+ + (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO)
+ + thisThread->fromTo.get(~pos.side_to_move(), move);
+ int rHist = (val - 8000) / 20000;
+ r = std::max(DEPTH_ZERO, (r / ONE_PLY - rHist) * ONE_PLY);
+ }
Depth d = std::max(newDepth - r, ONE_PLY);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
- doFullDepthSearch = (value > alpha && r != DEPTH_ZERO);
+ doFullDepthSearch = (value > alpha && d != newDepth);
}
else
doFullDepthSearch = !PvNode || moveCount > 1;
if (!moveCount)
bestValue = excludedMove ? alpha
: inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+ else if (bestMove)
+ {
+ int d = depth / ONE_PLY;
- // Quiet best move: update killers, history and countermoves
- else if (bestMove && !pos.capture_or_promotion(bestMove))
- update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount);
+ // Quiet best move: update killers, history and countermoves
+ if (!pos.capture_or_promotion(bestMove))
+ {
+ Value bonus = Value(d * d + 2 * d - 2);
+ update_stats(pos, ss, bestMove, quietsSearched, quietCount, bonus);
+ }
+ // Extra penalty for a quiet TT move in previous ply when it gets refuted
+ if ((ss-1)->moveCount == 1 && !pos.captured_piece())
+ {
+ Value penalty = Value(d * d + 4 * d + 1);
+ Square prevSq = to_sq((ss-1)->currentMove);
+ update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -penalty);
+ }
+ }
// Bonus for prior countermove that caused the fail low
else if ( depth >= 3 * ONE_PLY
- && !bestMove
- && !inCheck
- && !pos.captured_piece_type()
- && is_ok((ss - 1)->currentMove)
- && is_ok((ss - 2)->currentMove))
+ && !pos.captured_piece()
+ && is_ok((ss-1)->currentMove))
{
- Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
- Square prevPrevSq = to_sq((ss - 2)->currentMove);
- CounterMoveStats& prevCmh = CounterMoveHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
- prevCmh.update(pos.piece_on(prevSq), prevSq, bonus);
+ int d = depth / ONE_PLY;
+ Value bonus = Value(d * d + 2 * d - 2);
+ Square prevSq = to_sq((ss-1)->currentMove);
+ update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, bonus);
}
tte->save(posKey, value_to_tt(bestValue, ss->ply),
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
+ assert(depth / ONE_PLY * ONE_PLY == depth);
Move pv[MAX_PLY+1];
StateInfo st;
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
// be generated.
- MovePicker mp(pos, ttMove, depth, pos.this_thread()->history, to_sq((ss-1)->currentMove));
- CheckInfo ci(pos);
+ MovePicker mp(pos, ttMove, depth, to_sq((ss-1)->currentMove));
// Loop through the moves until no moves remain or a beta cutoff occurs
while ((move = mp.next_move()) != MOVE_NONE)
{
assert(is_ok(move));
- givesCheck = type_of(move) == NORMAL && !ci.dcCandidates
- ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
- : pos.gives_check(move, ci);
+ givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
+ ? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move)
+ : pos.gives_check(move);
// Futility pruning
if ( !InCheck
prefetch(TT.first_entry(pos.key_after(move)));
// Check for legality just before making the move
- if (!pos.legal(move, ci.pinned))
+ if (!pos.legal(move))
continue;
ss->currentMove = move;
}
- // update_stats() updates killers, history, countermove and countermove
- // history when a new quiet best move is found.
+ // update_cm_stats() updates countermove and follow-up move history
+
+ void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus) {
+
+ CounterMoveStats* cmh = (ss-1)->counterMoves;
+ CounterMoveStats* fmh1 = (ss-2)->counterMoves;
+ CounterMoveStats* fmh2 = (ss-4)->counterMoves;
+
+ if (cmh)
+ cmh->update(pc, s, bonus);
+
+ if (fmh1)
+ fmh1->update(pc, s, bonus);
+
+ if (fmh2)
+ fmh2->update(pc, s, bonus);
+ }
+
+
+ // update_stats() updates killers, history, countermove and countermove plus
+ // follow-up move history when a new quiet best move is found.
void update_stats(const Position& pos, Stack* ss, Move move,
- Depth depth, Move* quiets, int quietsCnt) {
+ Move* quiets, int quietsCnt, Value bonus) {
if (ss->killers[0] != move)
{
ss->killers[0] = move;
}
- Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
-
- Square prevSq = to_sq((ss-1)->currentMove);
- CounterMoveStats& cmh = CounterMoveHistory[pos.piece_on(prevSq)][prevSq];
+ Color c = pos.side_to_move();
Thread* thisThread = pos.this_thread();
-
+ thisThread->fromTo.update(c, move, bonus);
thisThread->history.update(pos.moved_piece(move), to_sq(move), bonus);
+ update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus);
- if (is_ok((ss-1)->currentMove))
+ if ((ss-1)->counterMoves)
{
+ Square prevSq = to_sq((ss-1)->currentMove);
thisThread->counterMoves.update(pos.piece_on(prevSq), prevSq, move);
- cmh.update(pos.moved_piece(move), to_sq(move), bonus);
}
// Decrease all the other played quiet moves
for (int i = 0; i < quietsCnt; ++i)
{
+ thisThread->fromTo.update(c, quiets[i], -bonus);
thisThread->history.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
-
- if (is_ok((ss-1)->currentMove))
- cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
- }
-
- // Extra penalty for a quiet TT move in previous ply when it gets refuted
- if ( (ss-1)->moveCount == 1
- && !pos.captured_piece_type()
- && is_ok((ss-2)->currentMove))
- {
- Square prevPrevSq = to_sq((ss-2)->currentMove);
- CounterMoveStats& prevCmh = CounterMoveHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
- prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY);
+ update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}
Move Skill::pick_best(size_t multiPV) {
- const Search::RootMoveVector& rootMoves = Threads.main()->rootMoves;
+ const RootMoves& rootMoves = Threads.main()->rootMoves;
static PRNG rng(now()); // PRNG sequence should be non-deterministic
// RootMoves are already sorted by score in descending order
std::stringstream ss;
int elapsed = Time.elapsed() + 1;
- const Search::RootMoveVector& rootMoves = pos.this_thread()->rootMoves;
+ const RootMoves& rootMoves = pos.this_thread()->rootMoves;
size_t PVIdx = pos.this_thread()->PVIdx;
size_t multiPV = std::min((size_t)Options["MultiPV"], rootMoves.size());
uint64_t nodes_searched = Threads.nodes_searched();
}
-/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
-/// inserts the PV back into the TT. This makes sure the old PV moves are searched
-/// first, even if the old TT entries have been overwritten.
-
-void RootMove::insert_pv_in_tt(Position& pos) {
-
- StateInfo state[MAX_PLY], *st = state;
- bool ttHit;
-
- for (Move m : pv)
- {
- assert(MoveList<LEGAL>(pos).contains(m));
-
- TTEntry* tte = TT.probe(pos.key(), ttHit);
-
- if (!ttHit || tte->move() != m) // Don't overwrite correct entries
- tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE,
- m, VALUE_NONE, TT.generation());
-
- pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos)));
- }
-
- for (size_t i = pv.size(); i > 0; )
- pos.undo_move(pv[--i]);
-}
-
-
/// RootMove::extract_ponder_from_tt() is called in case we have no ponder move
/// before exiting the search, for instance, in case we stop the search during a
/// fail high at root. We try hard to have a ponder move to return to the GUI,
/// otherwise in case of 'ponder on' we have nothing to think on.
-bool RootMove::extract_ponder_from_tt(Position& pos)
-{
+bool RootMove::extract_ponder_from_tt(Position& pos) {
+
StateInfo st;
bool ttHit;
assert(pv.size() == 1);
- pos.do_move(pv[0], st, pos.gives_check(pv[0], CheckInfo(pos)));
+ if (!pv[0])
+ return false;
+
+ pos.do_move(pv[0], st, pos.gives_check(pv[0]));
TTEntry* tte = TT.probe(pos.key(), ttHit);
- pos.undo_move(pv[0]);
if (ttHit)
{
Move m = tte->move(); // Local copy to be SMP safe
if (MoveList<LEGAL>(pos).contains(m))
- return pv.push_back(m), true;
+ pv.push_back(m);
}
- return false;
+ pos.undo_move(pv[0]);
+ return pv.size() > 1;
+}
+
+void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves) {
+
+ Hits = 0;
+ RootInTB = false;
+ UseRule50 = Options["Syzygy50MoveRule"];
+ ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
+ Cardinality = Options["SyzygyProbeLimit"];
+
+ // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality
+ if (Cardinality > MaxCardinality)
+ {
+ Cardinality = MaxCardinality;
+ ProbeDepth = DEPTH_ZERO;
+ }
+
+ if (Cardinality < popcount(pos.pieces()) || pos.can_castle(ANY_CASTLING))
+ return;
+
+ // If the current root position is in the tablebases, then RootMoves
+ // contains only moves that preserve the draw or the win.
+ RootInTB = root_probe(pos, rootMoves, TB::Score);
+
+ if (RootInTB)
+ Cardinality = 0; // Do not probe tablebases during the search
+
+ else // If DTZ tables are missing, use WDL tables as a fallback
+ {
+ // Filter out moves that do not preserve the draw or the win.
+ RootInTB = root_probe_wdl(pos, rootMoves, TB::Score);
+
+ // Only probe during search if winning
+ if (RootInTB && TB::Score <= VALUE_DRAW)
+ Cardinality = 0;
+ }
+
+ if (RootInTB)
+ {
+ Hits = rootMoves.size();
+
+ if (!UseRule50)
+ TB::Score = TB::Score > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1
+ : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
+ : VALUE_DRAW;
+ }
}
projects / stockfish / blobdiff