/// Types
+ // The BetaCounterType class is used to order moves at ply one.
+ // Apart for the first one that has its score, following moves
+ // normally have score -VALUE_INFINITE, so are ordered according
+ // to the number of beta cutoffs occurred under their subtree during
+ // the last iteration.
+
+ struct BetaCounterType {
+
+ BetaCounterType();
+ void clear();
+ void add(Color us, Depth d, int threadID);
+ void read(Color us, int64_t& our, int64_t& their);
+
+ int64_t hits[THREAD_MAX][2];
+ };
+
+
// The RootMove class is used for moves at the root at the tree. For each
// root move, we store a score, a node count, and a PV (really a refutation
// in the case of moves which fail low).
Value score;
int64_t nodes, cumulativeNodes;
Move pv[PLY_MAX_PLUS_2];
+ int64_t ourBeta, theirBeta;
};
inline Value get_move_score(int moveNum) const;
inline void set_move_score(int moveNum, Value score);
inline void set_move_nodes(int moveNum, int64_t nodes);
+ inline void set_beta_counters(int moveNum, int64_t our, int64_t their);
void set_move_pv(int moveNum, const Move pv[]);
inline Move get_move_pv(int moveNum, int i) const;
inline int64_t get_move_cumulative_nodes(int moveNum) const;
// when the static evaluation is at most IIDMargin below beta.
const Value IIDMargin = Value(0x100);
- // Use easy moves?
- const bool UseEasyMove = true;
-
// Easy move margin. An easy move candidate must be at least this much
// better than the second best move.
const Value EasyMoveMargin = Value(0x200);
bool UseQSearchFutilityPruning = true;
bool UseFutilityPruning = true;
- // Margins for futility pruning in the quiescence search, at frontier
- // nodes, and at pre-frontier nodes
- Value FutilityMargin0 = Value(0x80);
- Value FutilityMargin1 = Value(0x100);
- Value FutilityMargin2 = Value(0x300);
+ // Margins for futility pruning in the quiescence search, and at frontier
+ // and near frontier nodes
+ Value FutilityMarginQS = Value(0x80);
+ Value FutilityMargins[6] = { Value(0x100), Value(0x200), Value(0x250),
+ Value(0x2A0), Value(0x340), Value(0x3A0) };
// Razoring
+ const bool RazorAtDepthOne = false;
Depth RazorDepth = 4*OnePly;
Value RazorMargin = Value(0x300);
int NodesSincePoll;
int NodesBetweenPolls = 30000;
- // Iteration counter
+ // Iteration counters
int Iteration;
- bool LastIterations;
+ BetaCounterType BetaCounter;
// Scores and number of times the best move changed for each iteration:
Value ValueByIteration[PLY_MAX_PLUS_2];
// Time managment variables
int SearchStartTime;
int MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, TimeAdvantage;
- Move BestRootMove, PonderMove, EasyMove;
+ int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
+ Move EasyMove;
int RootMoveNumber;
bool InfiniteSearch;
bool PonderSearch;
Depth depth, int ply, int threadID);
void sp_search(SplitPoint *sp, int threadID);
void sp_search_pv(SplitPoint *sp, int threadID);
- void init_search_stack(SearchStack& ss);
- void init_search_stack(SearchStack ss[]);
- void init_node(const Position &pos, SearchStack ss[], int ply, int threadID);
+ void init_node(SearchStack ss[], int ply, int threadID);
void update_pv(SearchStack ss[], int ply);
void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply);
bool connected_moves(const Position &pos, Move m1, Move m2);
+ bool value_is_mate(Value value);
bool move_is_killer(Move m, const SearchStack& ss);
- Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat);
+ Depth extension(const Position &pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
bool ok_to_do_nullmove(const Position &pos);
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
bool thread_is_available(int slave, int master);
bool idle_thread_exists(int master);
bool split(const Position &pos, SearchStack *ss, int ply,
- Value *alpha, Value *beta, Value *bestValue, Depth depth,
- int *moves, MovePicker *mp, Bitboard dcCandidates, int master,
- bool pvNode);
+ Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
+ MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
void wake_sleeping_threads();
#if !defined(_MSC_VER)
SearchStack EmptySearchStack;
+// SearchStack::init() initializes a search stack. Used at the beginning of a
+// new search from the root.
+void SearchStack::init(int ply) {
+
+ pv[ply] = pv[ply + 1] = MOVE_NONE;
+ currentMove = threatMove = MOVE_NONE;
+ reduction = Depth(0);
+ currentMoveCaptureValue = Value(0);
+}
+
+void SearchStack::initKillers() {
+
+ mateKiller = MOVE_NONE;
+ for (int i = 0; i < KILLER_MAX; i++)
+ killers[i] = MOVE_NONE;
+}
+
+
////
//// Functions
////
// Initialize global search variables
Idle = false;
SearchStartTime = get_system_time();
- BestRootMove = MOVE_NONE;
- PonderMove = MOVE_NONE;
EasyMove = MOVE_NONE;
for (int i = 0; i < THREAD_MAX; i++)
{
UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
- FutilityMargin0 = value_from_centipawns(get_option_value_int("Futility Margin 0"));
- FutilityMargin1 = value_from_centipawns(get_option_value_int("Futility Margin 1"));
- FutilityMargin2 = value_from_centipawns(get_option_value_int("Futility Margin 2"));
+ FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)"));
+ int fmScale = get_option_value_int("Futility Margin Scale Factor (Main Search)");
+ for (int i = 0; i < 6; i++)
+ FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly;
RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin"));
// Set thinking time:
int myTime = time[side_to_move];
int myIncrement = increment[side_to_move];
- int oppTime = time[1 - side_to_move];
-
- TimeAdvantage = myTime - oppTime;
if (!movesToGo) // Sudden death time control
{
- if (increment)
+ if (myIncrement)
{
MaxSearchTime = myTime / 30 + myIncrement;
AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
} else { // Blitz game without increment
- MaxSearchTime = myTime / 40;
+ MaxSearchTime = myTime / 30;
AbsoluteMaxSearchTime = myTime / 8;
}
}
}
// Init also the empty search stack
- init_search_stack(EmptySearchStack);
+ EmptySearchStack.init(0);
+ EmptySearchStack.initKillers();
}
// Initialize
TT.new_search();
H.clear();
- init_search_stack(ss);
-
+ for (int i = 0; i < 3; i++)
+ {
+ ss[i].init(i);
+ ss[i].initKillers();
+ }
ValueByIteration[0] = Value(0);
ValueByIteration[1] = rml.get_move_score(0);
Iteration = 1;
- LastIterations = false;
EasyMove = rml.scan_for_easy_move();
ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2)
+ BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
- // If we need some more and we are in time advantage take it
- if (ExtraSearchTime > 0 && TimeAdvantage > 2 * MaxSearchTime)
- ExtraSearchTime += MaxSearchTime / 2;
-
- // Try to guess if the current iteration is the last one or the last two
- LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128);
-
// Stop search if most of MaxSearchTime is consumed at the end of the
// iteration. We probably don't have enough time to search the first
// move at the next iteration anyway.
<< " hashfull " << TT.full() << std::endl;
// Print the best move and the ponder move to the standard output
+ if (ss[0].pv[0] == MOVE_NONE)
+ {
+ ss[0].pv[0] = rml.get_move(0);
+ ss[0].pv[1] = MOVE_NONE;
+ }
std::cout << "bestmove " << ss[0].pv[0];
if (ss[0].pv[1] != MOVE_NONE)
std::cout << " ponder " << ss[0].pv[1];
if (UseLogFile)
{
- UndoInfo u;
+ if (dbg_show_mean)
+ dbg_print_mean(LogFile);
+
+ if (dbg_show_hit_rate)
+ dbg_print_hit_rate(LogFile);
+
+ StateInfo st;
LogFile << "Nodes: " << nodes_searched() << std::endl
<< "Nodes/second: " << nps() << std::endl
<< "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl;
- p.do_move(ss[0].pv[0], u);
+ p.do_move(ss[0].pv[0], st);
LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1])
<< std::endl << std::endl;
}
{
int64_t nodes;
Move move;
- UndoInfo u;
+ StateInfo st;
Depth ext, newDepth;
RootMoveNumber = i + 1;
// are used to sort the root moves at the next iteration.
nodes = nodes_searched();
+ // Reset beta cut-off counters
+ BetaCounter.clear();
+
// Pick the next root move, and print the move and the move number to
// the standard output.
move = ss[0].currentMove = rml.get_move(i);
<< " currmovenumber " << i + 1 << std::endl;
// Decide search depth for this move
- ext = extension(pos, move, true, pos.move_is_check(move), false, false);
+ bool dangerous;
+ ext = extension(pos, move, true, pos.move_is_capture(move), pos.move_is_check(move), false, false, &dangerous);
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
// Make the move, and search it
- pos.do_move(move, u, dcCandidates);
+ pos.do_move(move, st, dcCandidates);
if (i < MultiPV)
{
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
// Finished searching the move. If AbortSearch is true, the search
// was aborted because the user interrupted the search or because we
// sort the root moves at the next iteration.
rml.set_move_nodes(i, nodes_searched() - nodes);
+ // Remember the beta-cutoff statistics
+ int64_t our, their;
+ BetaCounter.read(pos.side_to_move(), our, their);
+ rml.set_beta_counters(i, our, their);
+
assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
if (value <= alpha && i >= MultiPV)
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ if (depth < OnePly)
+ return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
+
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (depth < OnePly)
- return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
-
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
int moveCount = 0;
Value value, bestValue = -VALUE_INFINITE;
Bitboard dcCandidates = mp.discovered_check_candidates();
+ Color us = pos.side_to_move();
bool isCheck = pos.is_check();
- bool mateThreat = MateThreatExtension[1] > Depth(0)
- && pos.has_mate_threat(opposite_color(pos.side_to_move()));
+ bool mateThreat = pos.has_mate_threat(opposite_color(us));
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
movesSearched[moveCount++] = ss[ply].currentMove = move;
if (moveIsCapture)
- ss[ply].currentMoveCaptureValue = pos.midgame_value_of_piece_on(move_to(move));
- else if (move_is_ep(move))
- ss[ply].currentMoveCaptureValue = PawnValueMidgame;
+ ss[ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
else
ss[ply].currentMoveCaptureValue = Value(0);
// Decide the new search depth
- Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat);
+ bool dangerous;
+ Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
Depth newDepth = depth - OnePly + ext;
// Make and search the move
- UndoInfo u;
- pos.do_move(move, u, dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
if (moveCount == 1) // The first move in list is the PV
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
if ( depth >= 2*OnePly
- && ext == Depth(0)
&& moveCount >= LMRPVMoves
+ && !dangerous
&& !moveIsCapture
&& !move_promotion(move)
- && !moveIsPassedPawnPush
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
else
value = alpha + 1; // Just to trigger next condition
- if (value > alpha) // Go with full depth pv search
+ if (value > alpha) // Go with full depth non-pv search
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
}
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
// (from the computer's point of view) since the previous iteration:
- if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ if ( ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
Problem = true;
}
else if (bestValue >= beta)
{
+ BetaCounter.add(pos.side_to_move(), depth, threadID);
Move m = ss[ply].pv[ply];
if (ok_to_history(pos, m)) // Only non capture moves are considered
{
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
+ if (depth < OnePly)
+ return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (depth < OnePly)
- return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
-
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
+ EvalInfo ei;
+
if (ply >= PLY_MAX - 1)
return evaluate(pos, ei, threadID);
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
- ss[ply].currentMove = ttMove; // can be MOVE_NONE ?
+ ss[ply].currentMove = ttMove; // can be MOVE_NONE
return value_from_tt(tte->value(), ply);
}
// Null move search
if ( allowNullmove
+ && depth > OnePly
&& !isCheck
+ && !value_is_mate(beta)
&& ok_to_do_nullmove(pos)
&& approximateEval >= beta - NullMoveMargin)
{
ss[ply].currentMove = MOVE_NULL;
- UndoInfo u;
- pos.do_null_move(u);
- int R = (depth > 7 ? 4 : 3);
+ StateInfo st;
+ pos.do_null_move(st);
+ int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
+
Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
- pos.undo_null_move(u);
- if (nullValue >= beta)
+ pos.undo_null_move();
+
+ if (value_is_mate(nullValue))
+ {
+ /* Do not return unproven mates */
+ }
+ else if (nullValue >= beta)
{
if (depth < 6 * OnePly)
return beta;
return beta;
} else {
// The null move failed low, which means that we may be faced with
- // some kind of threat. If the previous move was reduced, check if
+ // some kind of threat. If the previous move was reduced, check if
// the move that refuted the null move was somehow connected to the
- // move which was reduced. If a connection is found, return a fail
+ // move which was reduced. If a connection is found, return a fail
// low score (which will cause the reduced move to fail high in the
// parent node, which will trigger a re-search with full depth).
if (nullValue == value_mated_in(ply + 2))
}
}
// Null move search not allowed, try razoring
- else if ( (approximateEval < beta - RazorMargin && depth < RazorDepth)
- ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly))
+ else if ( !value_is_mate(beta)
+ && approximateEval < beta - RazorMargin
+ && depth < RazorDepth
+ && (RazorAtDepthOne || depth > OnePly)
+ && ttMove == MOVE_NONE
+ && !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
- if (v < beta)
+ if ( (v < beta - RazorMargin - RazorMargin / 4)
+ || (depth <= 2*OnePly && v < beta - RazorMargin)
+ || (depth <= OnePly && v < beta - RazorMargin / 2))
return v;
}
bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
movesSearched[moveCount++] = ss[ply].currentMove = move;
// Decide the new search depth
- Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat);
+ bool dangerous;
+ Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
Depth newDepth = depth - OnePly + ext;
// Futility pruning
if ( useFutilityPruning
- && ext == Depth(0)
+ && !dangerous
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move))
{
+ // History pruning. See ok_to_prune() definition
if ( moveCount >= 2 + int(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove, depth))
continue;
- if (depth < 3 * OnePly && approximateEval < beta)
+ // Value based pruning
+ if (depth < 7 * OnePly && approximateEval < beta)
{
if (futilityValue == VALUE_NONE)
futilityValue = evaluate(pos, ei, threadID)
- + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2);
+ + FutilityMargins[int(depth)/2 - 1]
+ + 32 * (depth & 1);
if (futilityValue < beta)
{
}
// Make and search the move
- UndoInfo u;
- pos.do_move(move, u, dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
- if ( depth >= 2*OnePly
- && ext == Depth(0)
- && moveCount >= LMRNonPVMoves
+ if ( depth >= 2*OnePly
+ && moveCount >= LMRNonPVMoves
+ && !dangerous
&& !moveIsCapture
&& !move_promotion(move)
- && !moveIsPassedPawnPush
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
else
{
+ BetaCounter.add(pos.side_to_move(), depth, threadID);
Move m = ss[ply].pv[ply];
if (ok_to_history(pos, m)) // Only non capture moves are considered
{
}
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
}
+
+ assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
+
return bestValue;
}
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
-
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
- // Transposition table lookup
- const TTEntry* tte = TT.retrieve(pos);
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
- return value_from_tt(tte->value(), ply);
+ // Transposition table lookup, only when not in PV
+ TTEntry* tte = NULL;
+ bool pvNode = (beta - alpha != 1);
+ if (!pvNode)
+ {
+ tte = TT.retrieve(pos);
+ if (tte && ok_to_use_TT(tte, depth, beta, ply))
+ {
+ assert(tte->type() != VALUE_TYPE_EVAL);
+
+ return value_from_tt(tte->value(), ply);
+ }
+ }
// Evaluate the position statically
- Value staticValue = evaluate(pos, ei, threadID);
+ EvalInfo ei;
+ Value staticValue;
+ bool isCheck = pos.is_check();
+ ei.futilityMargin = Value(0); // Manually initialize futilityMargin
+
+ if (isCheck)
+ staticValue = -VALUE_INFINITE;
+
+ else if (tte && tte->type() == VALUE_TYPE_EVAL)
+ {
+ // Use the cached evaluation score if possible
+ assert(tte->value() == evaluate(pos, ei, threadID));
+ assert(ei.futilityMargin == Value(0));
+
+ staticValue = tte->value();
+ }
+ else
+ staticValue = evaluate(pos, ei, threadID);
if (ply == PLY_MAX - 1)
- return staticValue;
+ return evaluate(pos, ei, threadID);
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
- Value bestValue = (pos.is_check() ? -VALUE_INFINITE : staticValue);
+ Value bestValue = staticValue;
if (bestValue >= beta)
+ {
+ // Store the score to avoid a future costly evaluation() call
+ if (!isCheck && !tte && ei.futilityMargin == 0)
+ TT.store(pos, value_to_tt(bestValue, ply), Depth(-127*OnePly), MOVE_NONE, VALUE_TYPE_EVAL);
+
return bestValue;
+ }
if (bestValue > alpha)
alpha = bestValue;
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth == 0) will be generated.
- MovePicker mp = MovePicker(pos, false, MOVE_NONE, EmptySearchStack, depth, &ei);
+ MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth);
Move move;
int moveCount = 0;
Bitboard dcCandidates = mp.discovered_check_candidates();
- bool isCheck = pos.is_check();
- bool pvNode = (beta - alpha != 1);
- bool enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
+ Color us = pos.side_to_move();
+ bool enoughMaterial = pos.non_pawn_material(us) > RookValueMidgame;
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
{
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
-
moveCount++;
ss[ply].currentMove = move;
// Futility pruning
if ( UseQSearchFutilityPruning
+ && enoughMaterial
&& !isCheck
- && !moveIsCheck
- && !move_promotion(move)
- && !moveIsPassedPawnPush
&& !pvNode
- && enoughMaterial)
+ && !move_promotion(move)
+ && !pos.move_is_check(move, dcCandidates)
+ && !pos.move_is_passed_pawn_push(move))
{
Value futilityValue = staticValue
+ Max(pos.midgame_value_of_piece_on(move_to(move)),
pos.endgame_value_of_piece_on(move_to(move)))
- + FutilityMargin0
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0))
+ + FutilityMarginQS
+ ei.futilityMargin;
if (futilityValue < alpha)
continue;
// Make and search the move.
- UndoInfo u;
- pos.do_move(move, u, dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// Update transposition table
- TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT);
+ if (!pvNode)
+ {
+ Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ if (bestValue < beta)
+ TT.store(pos, value_to_tt(bestValue, ply), d, MOVE_NONE, VALUE_TYPE_UPPER);
+ else
+ TT.store(pos, value_to_tt(bestValue, ply), d, MOVE_NONE, VALUE_TYPE_LOWER);
+ }
// Update killers only for good check moves
Move m = ss[ply].currentMove;
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
ss[sp->ply].currentMove = move;
// Decide the new search depth.
- Depth ext = extension(pos, move, false, moveIsCheck, false, false);
+ bool dangerous;
+ Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Prune?
if ( useFutilityPruning
- && ext == Depth(0)
+ && !dangerous
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move)
&& moveCount >= 2 + int(sp->depth)
&& ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
continue;
// Make and search the move.
- UndoInfo u;
- pos.do_move(move, u, sp->dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, sp->dcCandidates);
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
- if ( ext == Depth(0)
+ if ( !dangerous
&& moveCount >= LMRNonPVMoves
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move)
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
ss[sp->ply].reduction = Depth(0);
value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
{
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
assert(move_is_ok(move));
- ss[sp->ply].currentMoveCaptureValue = move_is_ep(move)?
- PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ if (moveIsCapture)
+ ss[sp->ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ else
+ ss[sp->ply].currentMoveCaptureValue = Value(0);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
ss[sp->ply].currentMove = move;
// Decide the new search depth.
- Depth ext = extension(pos, move, true, moveIsCheck, false, false);
+ bool dangerous;
+ Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
- UndoInfo u;
- pos.do_move(move, u, sp->dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, sp->dcCandidates);
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
- if ( ext == Depth(0)
+ if ( !dangerous
&& moveCount >= LMRPVMoves
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move)
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
Threads[threadID].failHighPly1 = false;
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
}
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration:
- if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ // (from the computer's point of view) since the previous iteration.
+ if ( sp->ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
Problem = true;
}
lock_release(&(sp->lock));
lock_grab(&(sp->lock));
// If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads:
+ // a beta cutoff higher up in the tree, stop all slave threads.
if (sp->master == threadID && thread_should_stop(threadID))
for (int i = 0; i < ActiveThreads; i++)
if (sp->slaves[i])
lock_release(&(sp->lock));
}
+ /// The BetaCounterType class
+
+ BetaCounterType::BetaCounterType() { clear(); }
+
+ void BetaCounterType::clear() {
+
+ for (int i = 0; i < THREAD_MAX; i++)
+ hits[i][WHITE] = hits[i][BLACK] = 0ULL;
+ }
+
+ void BetaCounterType::add(Color us, Depth d, int threadID) {
+
+ // Weighted count based on depth
+ hits[threadID][us] += int(d);
+ }
+
+ void BetaCounterType::read(Color us, int64_t& our, int64_t& their) {
+
+ our = their = 0UL;
+ for (int i = 0; i < THREAD_MAX; i++)
+ {
+ our += hits[i][us];
+ their += hits[i][opposite_color(us)];
+ }
+ }
+
/// The RootMove class
if (score != m.score)
return (score < m.score);
- return nodes <= m.nodes;
+ return theirBeta <= m.theirBeta;
}
/// The RootMoveList class
if (includeMove)
{
// Find a quick score for the move
- UndoInfo u;
+ StateInfo st;
SearchStack ss[PLY_MAX_PLUS_2];
moves[count].move = mlist[i].move;
moves[count].nodes = 0ULL;
- pos.do_move(moves[count].move, u);
+ pos.do_move(moves[count].move, st);
moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE,
Depth(0), 1, 0);
- pos.undo_move(moves[count].move, u);
+ pos.undo_move(moves[count].move);
moves[count].pv[0] = moves[i].move;
moves[count].pv[1] = MOVE_NONE; // FIXME
count++;
moves[moveNum].cumulativeNodes += nodes;
}
+ inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
+ moves[moveNum].ourBeta = our;
+ moves[moveNum].theirBeta = their;
+ }
+
void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
int j;
for(j = 0; pv[j] != MOVE_NONE; j++)
}
- // init_search_stack() initializes a search stack at the beginning of a
- // new search from the root.
- void init_search_stack(SearchStack& ss) {
-
- ss.pv[0] = MOVE_NONE;
- ss.pv[1] = MOVE_NONE;
- ss.currentMove = MOVE_NONE;
- ss.threatMove = MOVE_NONE;
- ss.reduction = Depth(0);
- for (int j = 0; j < KILLER_MAX; j++)
- ss.killers[j] = MOVE_NONE;
- }
-
- void init_search_stack(SearchStack ss[]) {
-
- for (int i = 0; i < 3; i++)
- {
- ss[i].pv[i] = MOVE_NONE;
- ss[i].pv[i+1] = MOVE_NONE;
- ss[i].currentMove = MOVE_NONE;
- ss[i].threatMove = MOVE_NONE;
- ss[i].reduction = Depth(0);
- for (int j = 0; j < KILLER_MAX; j++)
- ss[i].killers[j] = MOVE_NONE;
- }
- }
-
-
// init_node() is called at the beginning of all the search functions
// (search(), search_pv(), qsearch(), and so on) and initializes the search
// stack object corresponding to the current node. Once every
// NodesBetweenPolls nodes, init_node() also calls poll(), which polls
// for user input and checks whether it is time to stop the search.
- void init_node(const Position &pos, SearchStack ss[], int ply, int threadID) {
+ void init_node(SearchStack ss[], int ply, int threadID) {
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
}
}
- ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE;
- ss[ply+2].mateKiller = MOVE_NONE;
- ss[ply].threatMove = MOVE_NONE;
- ss[ply].reduction = Depth(0);
- ss[ply].currentMoveCaptureValue = Value(0);
- for (int j = 0; j < KILLER_MAX; j++)
- ss[ply+2].killers[j] = MOVE_NONE;
+ ss[ply].init(ply);
+ ss[ply+2].initKillers();
if(Threads[threadID].printCurrentLine)
print_current_line(ss, ply, threadID);
// Case 4: The destination square for m2 is attacked by the moving piece
// in m1:
- if(pos.piece_attacks_square(t1, t2))
+ if(pos.piece_attacks_square(pos.piece_on(t1), t1, t2))
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1:
}
+ // value_is_mate() checks if the given value is a mate one
+ // eventually compensated for the ply.
+
+ bool value_is_mate(Value value) {
+
+ assert(abs(value) <= VALUE_INFINITE);
+
+ return value <= value_mated_in(PLY_MAX)
+ || value >= value_mate_in(PLY_MAX);
+ }
+
+
// move_is_killer() checks if the given move is among the
// killer moves of that ply.
// extension() decides whether a move should be searched with normal depth,
// or with extended depth. Certain classes of moves (checking moves, in
- // particular) are searched with bigger depth than ordinary moves.
+ // particular) are searched with bigger depth than ordinary moves and in
+ // any case are marked as 'dangerous'. Note that also if a move is not
+ // extended, as example because the corresponding UCI option is set to zero,
+ // the move is marked as 'dangerous' so, at least, we avoid to prune it.
+
+ Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check,
+ bool singleReply, bool mateThreat, bool* dangerous) {
- Depth extension(const Position &pos, Move m, bool pvNode,
- bool check, bool singleReply, bool mateThreat) {
+ assert(m != MOVE_NONE);
Depth result = Depth(0);
+ *dangerous = check || singleReply || mateThreat;
if (check)
result += CheckExtension[pvNode];
if (singleReply)
result += SingleReplyExtension[pvNode];
- if (pos.move_is_pawn_push_to_7th(m))
- result += PawnPushTo7thExtension[pvNode];
-
- if (pos.move_is_passed_pawn_push(m))
- result += PassedPawnExtension[pvNode];
-
if (mateThreat)
result += MateThreatExtension[pvNode];
- if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame
+ if (pos.type_of_piece_on(move_from(m)) == PAWN)
+ {
+ if (pos.move_is_pawn_push_to_7th(m))
+ {
+ result += PawnPushTo7thExtension[pvNode];
+ *dangerous = true;
+ }
+ if (pos.move_is_passed_pawn_push(m))
+ {
+ result += PassedPawnExtension[pvNode];
+ *dangerous = true;
+ }
+ }
+
+ if ( capture
+ && pos.type_of_piece_on(move_to(m)) != PAWN
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
- && !move_promotion(m))
+ && !move_promotion(m)
+ && !move_is_ep(m))
+ {
result += PawnEndgameExtension[pvNode];
+ *dangerous = true;
+ }
if ( pvNode
- && pos.move_is_capture(m)
+ && capture
&& pos.type_of_piece_on(move_to(m)) != PAWN
&& pos.see(m) >= 0)
+ {
result += OnePly/2;
+ *dangerous = true;
+ }
return Min(result, OnePly);
}
tto = move_to(threat);
// Case 1: Castling moves are never pruned.
- if(move_is_castle(m))
- return false;
+ if (move_is_castle(m))
+ return false;
// Case 2: Don't prune moves which move the threatened piece
- if(!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
- return false;
+ if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
+ return false;
// Case 3: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune move which defend it.
- if(!PruneDefendingMoves && threat != MOVE_NONE
- && (piece_value_midgame(pos.piece_on(tfrom))
- >= piece_value_midgame(pos.piece_on(tto)))
- && pos.move_attacks_square(m, tto))
+ if ( !PruneDefendingMoves
+ && threat != MOVE_NONE
+ && pos.move_is_capture(threat)
+ && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
+ || pos.type_of_piece_on(tfrom) == KING)
+ && pos.move_attacks_square(m, tto))
return false;
// Case 4: Don't prune moves with good history.
- if(!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
- return false;
+ if (!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
+ return false;
// Case 5: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
- if(!PruneBlockingMoves && threat != MOVE_NONE
- && piece_is_slider(pos.piece_on(tfrom))
- && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0)
- return false;
+ if ( !PruneBlockingMoves
+ && threat != MOVE_NONE
+ && piece_is_slider(pos.piece_on(tfrom))
+ && bit_is_set(squares_between(tfrom, tto), mto)
+ && pos.see(m) >= 0)
+ return false;
return true;
}
|| ( !FailHigh && !fail_high_ply_1() && !Problem
&& t > 6*(MaxSearchTime + ExtraSearchTime));
- if ( (Iteration >= 2 && (!InfiniteSearch && overTime))
+ if ( (Iteration >= 3 && (!InfiniteSearch && overTime))
|| (ExactMaxTime && t >= ExactMaxTime)
|| (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
AbortSearch = true;
void ponderhit() {
int t = current_search_time();
PonderSearch = false;
- if(Iteration >= 2 &&
+ if(Iteration >= 3 &&
(!InfiniteSearch && (StopOnPonderhit ||
t > AbsoluteMaxSearchTime ||
(RootMoveNumber == 1 &&
// splitPoint->cpus becomes 0), split() returns true.
bool split(const Position &p, SearchStack *sstck, int ply,
- Value *alpha, Value *beta, Value *bestValue,
- Depth depth, int *moves,
+ Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode) {
+
assert(p.is_ok());
assert(sstck != NULL);
assert(ply >= 0 && ply < PLY_MAX);
projects / stockfish / blobdiff