const bool PruneDefendingMoves = false;
const bool PruneBlockingMoves = false;
+ // Only move margin
+ const Value OnlyMoveMargin = Value(100);
+
// Margins for futility pruning in the quiescence search, and at frontier
// and near frontier nodes.
const Value FutilityMarginQS = Value(0x80);
+ // Each move futility margin is decreased
+ const Value IncrementalFutilityMargin = Value(0x8);
+
// Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270),
// 4 ply 4.5 ply 5 ply 5.5 ply 6 ply 6.5 ply
Depth ThreatDepth; // heavy SMP read access
// Last seconds noise filtering (LSN)
- const bool UseLSNFiltering = false;
+ const bool UseLSNFiltering = true;
const int LSNTime = 4000; // In milliseconds
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
Value id_loop(const Position& pos, Move searchMoves[]);
Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta);
Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
- Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID);
+ Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move forbiddenMove = MOVE_NONE);
Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
void sp_search(SplitPoint* sp, int threadID);
void sp_search_pv(SplitPoint* sp, int threadID);
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 ok_to_history(const Position& pos, Move m);
void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
void ponderhit();
void print_current_line(SearchStack ss[], int ply, int threadID);
void wait_for_stop_or_ponderhit();
+ void init_ss_array(SearchStack ss[]);
void idle_loop(int threadID, SplitPoint* waitSp);
void init_split_point_stack();
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,
+ const Value futilityValue, const Value approximateValue,
+ Depth depth, int *moves,
+ MovePicker *mp, int master, bool pvNode);
void wake_sleeping_threads();
#if !defined(_MSC_VER)
//// Functions
////
+
+/// perft() is our utility to verify move generation is bug free. All the
+/// legal moves up to given depth are generated and counted and the sum returned.
+
+int perft(Position& pos, Depth depth)
+{
+ Move move;
+ int sum = 0;
+ MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
+
+ // If we are at the last ply we don't need to do and undo
+ // the moves, just to count them.
+ if (depth <= OnePly) // Replace with '<' to test also qsearch
+ {
+ while (mp.get_next_move()) sum++;
+ return sum;
+ }
+
+ // Loop through all legal moves
+ CheckInfo ci(pos);
+ while ((move = mp.get_next_move()) != MOVE_NONE)
+ {
+ StateInfo st;
+ pos.do_move(move, st, ci, pos.move_is_check(move, ci));
+ sum += perft(pos, depth - OnePly);
+ pos.undo_move(move);
+ }
+ return sum;
+}
+
+
/// think() is the external interface to Stockfish's search, and is called when
/// the program receives the UCI 'go' command. It initializes various
/// search-related global variables, and calls root_search(). It returns false
if (movesToGo == 1)
{
MaxSearchTime = myTime / 2;
- AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500);
+ AbsoluteMaxSearchTime =
+ (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
} else {
MaxSearchTime = myTime / Min(movesToGo, 20);
AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
NodesBetweenPolls = Min(MaxNodes, 30000);
InfiniteSearch = true; // HACK
}
+ else if (myTime && myTime < 1000)
+ NodesBetweenPolls = 1000;
+ else if (myTime && myTime < 5000)
+ NodesBetweenPolls = 5000;
else
NodesBetweenPolls = 30000;
// Initialize
TT.new_search();
H.clear();
- for (int i = 0; i < 3; i++)
- {
- ss[i].init(i);
- ss[i].initKillers();
- }
+ init_ss_array(ss);
IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
Iteration = 1;
Value oldAlpha = alpha;
Value value;
- Bitboard dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
+ CheckInfo ci(pos);
// Loop through all the moves in the root move list
for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
<< " currmovenumber " << i + 1 << std::endl;
// Decide search depth for this move
- bool moveIsCapture = pos.move_is_capture(move);
+ bool moveIsCheck = pos.move_is_check(move);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
bool dangerous;
- ext = extension(pos, move, true, moveIsCapture, pos.move_is_check(move), false, false, &dangerous);
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
// Make the move, and search it
- pos.do_move(move, st, dcCandidates);
+ pos.do_move(move, st, ci, moveIsCheck);
if (i < MultiPV)
{
if ( newDepth >= 3*OnePly
&& i >= MultiPV + LMRPVMoves
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move))
{
ss[0].reduction = OnePly;
// Update PV
rml.set_move_score(i, value);
update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
rml.set_move_pv(i, ss[0].pv);
if (MultiPV == 1)
std::cout << std::endl;
if (UseLogFile)
- LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv)
+ LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value,
+ ((value >= beta)? VALUE_TYPE_LOWER
+ : ((value <= alpha)? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)),
+ ss[0].pv)
<< std::endl;
if (value > alpha)
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ Move movesSearched[256];
+ EvalInfo ei;
+ StateInfo st;
+ const TTEntry* tte;
+ Move ttMove, move;
+ Depth ext, newDepth;
+ Value oldAlpha, value;
+ bool isCheck, mateThreat, singleReply, moveIsCheck, captureOrPromotion, dangerous;
+ int moveCount = 0;
+ Value bestValue = -VALUE_INFINITE;
+
if (depth < OnePly)
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
if (pos.is_draw())
return VALUE_DRAW;
- EvalInfo ei;
-
if (ply >= PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Mate distance pruning
- Value oldAlpha = alpha;
+ oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
beta = Min(value_mate_in(ply+1), beta);
if (alpha >= beta)
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- const TTEntry* tte = TT.retrieve(pos.get_key());
- Move ttMove = (tte ? tte->move() : MOVE_NONE);
+ tte = TT.retrieve(pos.get_key());
+ ttMove = (tte ? tte->move() : MOVE_NONE);
// Go with internal iterative deepening if we don't have a TT move
if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly)
// Initialize a MovePicker object for the current position, and prepare
// to search all moves
- Move move, movesSearched[256];
- int moveCount = 0;
- Value value, bestValue = -VALUE_INFINITE;
- Color us = pos.side_to_move();
- bool isCheck = pos.is_check();
- bool mateThreat = pos.has_mate_threat(opposite_color(us));
-
+ isCheck = pos.is_check();
+ mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
+ CheckInfo ci(pos);
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
- Bitboard dcCandidates = mp.discovered_check_candidates();
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
{
assert(move_is_ok(move));
- bool singleReply = (isCheck && mp.number_of_evasions() == 1);
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ singleReply = (isCheck && mp.number_of_evasions() == 1);
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- movesSearched[moveCount++] = ss[ply].currentMove = move;
+ movesSearched[moveCount++] = move;
// Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
- Depth newDepth = depth - OnePly + ext;
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+
+ // Only move extension
+ if ( moveCount == 1
+ && ext < OnePly
+ && depth >= 8 * OnePly
+ && tte
+ && (tte->type() & VALUE_TYPE_LOWER)
+ && tte->move() != MOVE_NONE
+ && tte->depth() >= depth - 3 * OnePly)
+ {
+ Value ttValue = value_from_tt(tte->value(), ply);
+ if (abs(ttValue) < VALUE_KNOWN_WIN)
+ {
+ Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, depth / 2, ply, false, threadID, tte->move());
+ if (excValue < ttValue - OnlyMoveMargin)
+ ext = OnePly;
+ }
+ }
+
+ newDepth = depth - OnePly + ext;
+
+ // Update current move
+ ss[ply].currentMove = move;
// Make and search the move
- StateInfo st;
- pos.do_move(move, st, dcCandidates);
+ pos.do_move(move, st, ci, moveIsCheck);
if (moveCount == 1) // The first move in list is the PV
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
if ( depth >= 3*OnePly
&& moveCount >= LMRPVMoves
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
- && split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
- &moveCount, &mp, dcCandidates, threadID, true))
+ && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE,
+ depth, &moveCount, &mp, threadID, true))
break;
}
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
+ move = ss[ply].pv[ply];
+ if (!pos.move_is_capture_or_promotion(move))
{
- update_history(pos, m, depth, movesSearched, moveCount);
- update_killers(m, ss[ply]);
+ update_history(pos, move, depth, movesSearched, moveCount);
+ update_killers(move, ss[ply]);
}
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, m);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
}
else
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss[ply].pv[ply]);
// search() is the search function for zero-width nodes.
Value search(Position& pos, SearchStack ss[], Value beta, Depth depth,
- int ply, bool allowNullmove, int threadID) {
+ int ply, bool allowNullmove, int threadID, Move forbiddenMove) {
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ Move movesSearched[256];
+ EvalInfo ei;
+ StateInfo st;
+ const TTEntry* tte;
+ Move ttMove, move;
+ Depth ext, newDepth;
+ Value approximateEval, nullValue, value, futilityValue, futilityValueScaled;
+ bool isCheck, useFutilityPruning, singleReply, moveIsCheck, captureOrPromotion, dangerous;
+ bool mateThreat = false;
+ int moveCount = 0;
+ Value bestValue = -VALUE_INFINITE;
+
if (depth < OnePly)
return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
if (pos.is_draw())
return VALUE_DRAW;
- EvalInfo ei;
-
if (ply >= PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Mate distance pruning
if (value_mated_in(ply) >= beta)
if (value_mate_in(ply + 1) < beta)
return beta - 1;
+ // Position key calculation
+ Key posKey = pos.get_key();
+
+ if (forbiddenMove != MOVE_NONE)
+ posKey ^= Position::zobExclusion;
+
// Transposition table lookup
- const TTEntry* tte = TT.retrieve(pos.get_key());
- Move ttMove = (tte ? tte->move() : MOVE_NONE);
+ tte = TT.retrieve(posKey);
+ ttMove = (tte ? tte->move() : MOVE_NONE);
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
return value_from_tt(tte->value(), ply);
}
- Value approximateEval = quick_evaluate(pos);
- bool mateThreat = false;
- bool isCheck = pos.is_check();
+ approximateEval = quick_evaluate(pos);
+ isCheck = pos.is_check();
// Null move search
if ( allowNullmove
{
ss[ply].currentMove = MOVE_NULL;
- 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);
+ // Null move dynamic reduction based on depth
+ int R = (depth >= 5 * OnePly ? 4 : 3);
+
+ // Null move dynamic reduction based on value
+ if (approximateEval - beta > PawnValueMidgame)
+ R++;
+
+ nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
pos.undo_null_move();
&& 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 - RazorMargins[int(depth) - 2])
+ Value rbeta = beta - RazorMargins[int(depth) - 2];
+ Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
+ if (v < rbeta)
return v;
}
// Initialize a MovePicker object for the current position, and prepare
// to search all moves.
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
-
- Move move, movesSearched[256];
- int moveCount = 0;
- Value value, bestValue = -VALUE_INFINITE;
- Bitboard dcCandidates = mp.discovered_check_candidates();
- Value futilityValue = VALUE_NONE;
- bool useFutilityPruning = depth < SelectiveDepth
- && !isCheck;
+ CheckInfo ci(pos);
+ futilityValue = VALUE_NONE;
+ useFutilityPruning = depth < SelectiveDepth && !isCheck;
// Avoid calling evaluate() if we already have the score in TT
if (tte && (tte->type() & VALUE_TYPE_EVAL))
futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2];
+ // Move count pruning limit
+ const int MCLimit = 3 + (1 << (3*int(depth)/8));
+
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
while ( bestValue < beta
{
assert(move_is_ok(move));
- bool singleReply = (isCheck && mp.number_of_evasions() == 1);
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ if (move == forbiddenMove)
+ continue;
+
+ singleReply = (isCheck && mp.number_of_evasions() == 1);
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- movesSearched[moveCount++] = ss[ply].currentMove = move;
+ movesSearched[moveCount++] = move;
// Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
- Depth newDepth = depth - OnePly + ext;
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+
+ // Only move extension
+ if ( forbiddenMove == MOVE_NONE
+ && moveCount == 1
+ && ext < OnePly
+ && depth >= 8 * OnePly
+ && tte
+ && (tte->type() & VALUE_TYPE_LOWER)
+ && tte->move() != MOVE_NONE
+ && tte->depth() >= depth - 3 * OnePly)
+ {
+ Value ttValue = value_from_tt(tte->value(), ply);
+ if (abs(ttValue) < VALUE_KNOWN_WIN)
+ {
+ Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, depth / 2, ply, false, threadID, tte->move());
+ if (excValue < ttValue - OnlyMoveMargin)
+ ext = OnePly;
+ }
+ }
+
+ newDepth = depth - OnePly + ext;
+
+ // Update current move
+ ss[ply].currentMove = move;
// Futility pruning
if ( useFutilityPruning
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move))
+ && !captureOrPromotion
+ && move != ttMove)
{
+ //std::cout << std::endl;
+ //for (int d = 2; d < 14; d++)
+ // std::cout << d << ", " << 64*(1+bitScanReverse32(d*d)) << std::endl;
+
+ //std::cout << std::endl;
+/*
+ 64*(1+bitScanReverse32(d*d))
+
+ 2 -> 256 - 256
+ 3 -> 288 - 320
+ 4 -> 512 - 384
+ 5 -> 544 - 384
+ 6 -> 592 - 448
+ 7 -> 624 - 448
+ 8 -> 672 - 512
+ 9 -> 704 - 512
+ 10 -> 832 - 512
+ 11 -> 864 - 512
+ 12 -> 928 - 576
+ 13 -> 960 - 576
+
+ 300 + 2*(1 << (3*d/4))
+
+ 2 -> 256 - 304
+ 3 -> 288 - 308
+ 4 -> 512 - 316
+ 5 -> 544 - 316
+ 6 -> 592 - 332
+ 7 -> 624 - 364
+ 8 -> 672 - 428
+ 9 -> 704 - 428
+ 10 -> 832 - 556
+ 11 -> 864 - 812
+ 12 -> 928 - 1324
+ 13 -> 960 - 1324
+
+
+ 3 + (1 << (3*int(depth)/8))
+
+ 1 * onePly - > moveCount >= 4
+ 2 * onePly - > moveCount >= 5
+ 3 * onePly - > moveCount >= 7
+ 4 * onePly - > moveCount >= 11
+ 5 * onePly - > moveCount >= 11
+ 6 * onePly - > moveCount >= 19
+ 7 * onePly - > moveCount >= 35
+*/
// History pruning. See ok_to_prune() definition
- if ( moveCount >= 2 + int(depth)
- && ok_to_prune(pos, move, ss[ply].threatMove, depth))
+ if ( moveCount >= MCLimit
+ && ok_to_prune(pos, move, ss[ply].threatMove, depth)
+ && bestValue > value_mated_in(PLY_MAX))
continue;
// Value based pruning
{
if (futilityValue == VALUE_NONE)
futilityValue = evaluate(pos, ei, threadID)
- + FutilityMargins[int(depth) - 2];
+ + 64*(2+bitScanReverse32(int(depth) * int(depth)));
+
+ futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
- if (futilityValue < beta)
+ if (futilityValueScaled < beta)
{
- if (futilityValue > bestValue)
- bestValue = futilityValue;
+ if (futilityValueScaled > bestValue)
+ bestValue = futilityValueScaled;
continue;
}
}
}
// Make and search the move
- StateInfo st;
- pos.do_move(move, st, dcCandidates);
+ pos.do_move(move, st, ci, moveIsCheck);
// 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 >= 3*OnePly
&& moveCount >= LMRNonPVMoves
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
- && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
- &mp, dcCandidates, threadID, false))
+ && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval,
+ depth, &moveCount, &mp, threadID, false))
break;
}
// All legal moves have been searched. A special case: If there were
// no legal moves, it must be mate or stalemate.
if (moveCount == 0)
- return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
+ return (forbiddenMove == MOVE_NONE ? (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW) : beta - 1);
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
return bestValue;
if (bestValue < beta)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
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
+ move = ss[ply].pv[ply];
+ if (!pos.move_is_capture_or_promotion(move))
{
- update_history(pos, m, depth, movesSearched, moveCount);
- update_killers(m, ss[ply]);
+ update_history(pos, move, depth, movesSearched, moveCount);
+ update_killers(move, ss[ply]);
}
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, m);
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ EvalInfo ei;
+ StateInfo st;
+ Move ttMove, move;
+ Value staticValue, bestValue, value, futilityValue;
+ bool isCheck, enoughMaterial, moveIsCheck;
+ const TTEntry* tte = NULL;
+ int moveCount = 0;
+ bool pvNode = (beta - alpha != 1);
+
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
init_node(ss, ply, threadID);
return VALUE_DRAW;
// Transposition table lookup, only when not in PV
- TTEntry* tte = NULL;
- bool pvNode = (beta - alpha != 1);
if (!pvNode)
{
tte = TT.retrieve(pos.get_key());
return value_from_tt(tte->value(), ply);
}
}
- Move ttMove = (tte ? tte->move() : MOVE_NONE);
+ ttMove = (tte ? tte->move() : MOVE_NONE);
// Evaluate the position statically
- EvalInfo ei;
- Value staticValue;
- bool isCheck = pos.is_check();
+ isCheck = pos.is_check();
ei.futilityMargin = Value(0); // Manually initialize futilityMargin
if (isCheck)
else
staticValue = evaluate(pos, ei, threadID);
- if (ply == PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ if (ply >= PLY_MAX - 1)
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
- Value bestValue = staticValue;
+ bestValue = staticValue;
if (bestValue >= beta)
{
// 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, ttMove, depth, H);
- Move move;
- int moveCount = 0;
- Bitboard dcCandidates = mp.discovered_check_candidates();
- Color us = pos.side_to_move();
- bool enoughMaterial = pos.non_pawn_material(us) > RookValueMidgame;
+ CheckInfo ci(pos);
+ enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
moveCount++;
ss[ply].currentMove = move;
+ moveIsCheck = pos.move_is_check(move, ci);
+
// Futility pruning
if ( enoughMaterial
&& !isCheck
&& !pvNode
+ && !moveIsCheck
+ && move != ttMove
&& !move_is_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)))
- + (move_is_ep(move) ? PawnValueEndgame : Value(0))
- + FutilityMarginQS
- + ei.futilityMargin;
+ futilityValue = staticValue
+ + Max(pos.midgame_value_of_piece_on(move_to(move)),
+ pos.endgame_value_of_piece_on(move_to(move)))
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0))
+ + FutilityMarginQS
+ + ei.futilityMargin;
if (futilityValue < alpha)
{
// Don't search captures and checks with negative SEE values
if ( !isCheck
+ && move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
continue;
- // Make and search the move.
- StateInfo st;
- pos.do_move(move, st, dcCandidates);
- Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
+ // Make and search the move
+ pos.do_move(move, st, ci, moveIsCheck);
+ value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
- if (pos.is_check() && moveCount == 0) // Mate!
+ if (!moveCount && pos.is_check()) // Mate!
return value_mated_in(ply);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// Update transposition table
- Move m = ss[ply].pv[ply];
+ move = ss[ply].pv[ply];
if (!pvNode)
{
// If bestValue isn't changed it means it is still the static evaluation of
if (bestValue < beta)
TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, m);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
}
// Update killers only for good check moves
- if (alpha >= beta && ok_to_history(pos, m)) // Only non capture moves are considered
- update_killers(m, ss[ply]);
+ if (alpha >= beta && !pos.move_is_capture_or_promotion(move))
+ update_killers(move, ss[ply]);
return bestValue;
}
assert(ActiveThreads > 1);
Position pos = Position(sp->pos);
+ CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
Value value;
Move move;
{
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ bool moveIsCheck = pos.move_is_check(move, ci);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
// Decide the new search depth.
bool dangerous;
- Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, false, false, &dangerous);
+ Depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Prune?
if ( useFutilityPruning
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
- && moveCount >= 2 + int(sp->depth)
- && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
- continue;
+ && !captureOrPromotion)
+ {
+ // History pruning. See ok_to_prune() definition
+ if ( moveCount >= 2 + int(sp->depth)
+ && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth)
+ && sp->bestValue > value_mated_in(PLY_MAX))
+ continue;
+
+ // Value based pruning
+ if (sp->approximateEval < sp->beta)
+ {
+ if (sp->futilityValue == VALUE_NONE)
+ {
+ EvalInfo ei;
+ sp->futilityValue = evaluate(pos, ei, threadID)
+ + FutilityMargins[int(sp->depth) - 2];
+ }
+
+ if (sp->futilityValue < sp->beta)
+ {
+ if (sp->futilityValue > sp->bestValue) // Less then 1% of cases
+ {
+ lock_grab(&(sp->lock));
+ if (sp->futilityValue > sp->bestValue)
+ sp->bestValue = sp->futilityValue;
+ lock_release(&(sp->lock));
+ }
+ continue;
+ }
+ }
+ }
// Make and search the move.
StateInfo st;
- pos.do_move(move, st, sp->dcCandidates);
+ pos.do_move(move, st, ci, moveIsCheck);
// 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 ( !dangerous
&& moveCount >= LMRNonPVMoves
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
break;
// New best move?
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+ if (value > sp->bestValue) // Less then 2% of cases
{
- sp->bestValue = value;
- if (sp->bestValue >= sp->beta)
+ lock_grab(&(sp->lock));
+ if (value > sp->bestValue && !thread_should_stop(threadID))
{
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
+ sp->bestValue = value;
+ if (sp->bestValue >= sp->beta)
+ {
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
+ for (int i = 0; i < ActiveThreads; i++)
+ if (i != threadID && (i == sp->master || sp->slaves[i]))
+ Threads[i].stop = true;
- sp->finished = true;
- }
+ sp->finished = true;
+ }
+ }
+ lock_release(&(sp->lock));
}
- lock_release(&(sp->lock));
}
lock_grab(&(sp->lock));
assert(ActiveThreads > 1);
Position pos = Position(sp->pos);
+ CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
Value value;
Move move;
&& !thread_should_stop(threadID)
&& (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
{
- bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ bool moveIsCheck = pos.move_is_check(move, ci);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
assert(move_is_ok(move));
// Decide the new search depth.
bool dangerous;
- Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, false, false, &dangerous);
+ Depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
StateInfo st;
- pos.do_move(move, st, sp->dcCandidates);
+ pos.do_move(move, st, ci, moveIsCheck);
// 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 ( !dangerous
&& moveCount >= LMRPVMoves
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
// Find a quick score for the move
StateInfo st;
SearchStack ss[PLY_MAX_PLUS_2];
+ init_ss_array(ss);
moves[count].move = cur->move;
pos.do_move(moves[count].move, st);
// 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 captureOrPromotion,
+ bool check, bool singleReply, bool mateThreat, bool* dangerous) {
assert(m != MOVE_NONE);
}
}
- if ( capture
+ if ( captureOrPromotion
&& 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))
}
if ( pvNode
- && capture
+ && captureOrPromotion
&& pos.type_of_piece_on(move_to(m)) != PAWN
&& pos.see_sign(m) >= 0)
{
assert(move_is_ok(m));
assert(threat == MOVE_NONE || move_is_ok(threat));
- assert(!move_is_promotion(m));
assert(!pos.move_is_check(m));
- assert(!pos.move_is_capture(m));
+ assert(!pos.move_is_capture_or_promotion(m));
assert(!pos.move_is_passed_pawn_push(m));
assert(d >= OnePly);
}
- // ok_to_history() returns true if a move m can be stored
- // in history. Should be a non capturing move nor a promotion.
-
- bool ok_to_history(const Position& pos, Move m) {
-
- return !pos.move_is_capture(m) && !move_is_promotion(m);
- }
-
-
// update_history() registers a good move that produced a beta-cutoff
// in history and marks as failures all the other moves of that ply.
for (int i = 0; i < moveCount - 1; i++)
{
assert(m != movesSearched[i]);
- if (ok_to_history(pos, movesSearched[i]))
+ if (!pos.move_is_capture_or_promotion(movesSearched[i]))
H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i]));
}
}
}
+ // init_ss_array() does a fast reset of the first entries of a SearchStack array
+
+ void init_ss_array(SearchStack ss[]) {
+
+ for (int i = 0; i < 3; i++)
+ {
+ ss[i].init(i);
+ ss[i].initKillers();
+ }
+ }
+
+
// wait_for_stop_or_ponderhit() is called when the maximum depth is reached
// while the program is pondering. The point is to work around a wrinkle in
// the UCI protocol: When pondering, the engine is not allowed to give a
// 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,
- MovePicker* mp, Bitboard dcCandidates, int master, bool pvNode) {
+ Value* alpha, Value* beta, Value* bestValue, const Value futilityValue,
+ const Value approximateEval, Depth depth, int* moves,
+ MovePicker* mp, int master, bool pvNode) {
assert(p.is_ok());
assert(sstck != NULL);
splitPoint->alpha = pvNode? *alpha : (*beta - 1);
splitPoint->beta = *beta;
splitPoint->pvNode = pvNode;
- splitPoint->dcCandidates = dcCandidates;
splitPoint->bestValue = *bestValue;
+ splitPoint->futilityValue = futilityValue;
+ splitPoint->approximateEval = approximateEval;
splitPoint->master = master;
splitPoint->mp = mp;
splitPoint->moves = *moves;
projects / stockfish / blobdiff