const bool FakeSplit = false;
// Different node types, used as template parameter
- enum NodeType { NonPV, PV };
+ enum NodeType { Root, PV, NonPV, SplitPointPV, SplitPointNonPV };
// RootMove struct is used for moves at the root of the tree. For each root
// move, we store two scores, a node count, and a PV (really a refutation
void extract_pv_from_tt(Position& pos);
void insert_pv_in_tt(Position& pos);
- std::string pv_info_to_uci(Position& pos, int depth, int selDepth,
- Value alpha, Value beta, int pvIdx);
+
int64_t nodes;
Value pv_score;
Value non_pv_score;
void init(Position& pos, Move searchMoves[]);
void sort() { insertion_sort<RootMove, Base::iterator>(begin(), end()); }
- void sort_multipv(int n) { insertion_sort<RootMove, Base::iterator>(begin(), begin() + n); }
+ void sort_first(int n) { insertion_sort<RootMove, Base::iterator>(begin(), begin() + n); }
int bestMoveChanges;
};
- // MovePickerExt template class extends MovePicker and allows to choose at compile
- // time the proper moves source according to the type of node. In the default case
- // we simply create and use a standard MovePicker object.
- template<bool SpNode, bool Root> struct MovePickerExt : public MovePicker {
-
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b) {}
-
- RootMoveList::iterator rm; // Dummy, needed to compile
- };
-
- // In case of a SpNode we use split point's shared MovePicker object as moves source
- template<> struct MovePickerExt<true, false> : public MovePicker {
-
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
-
- Move get_next_move() { return mp->get_next_move(); }
-
- RootMoveList::iterator rm; // Dummy, needed to compile
- MovePicker* mp;
- };
-
- // In case of a Root node we use RootMoveList as moves source
- template<> struct MovePickerExt<false, true> : public MovePicker {
-
- MovePickerExt(const Position&, Move, Depth, const History&, SearchStack*, Value);
- Move get_next_move();
-
- RootMoveList::iterator rm;
- bool firstCall;
- };
-
/// Constants
// Reduction lookup tables (initialized at startup) and their access function
int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
- template <NodeType PV> inline Depth reduction(Depth d, int mn) {
+ template <bool PvNode> inline Depth reduction(Depth d, int mn) {
- return (Depth) Reductions[PV][Min(d / ONE_PLY, 63)][Min(mn, 63)];
+ return (Depth) Reductions[PvNode][Min(d / ONE_PLY, 63)][Min(mn, 63)];
}
// Easy move margin. An easy move candidate must be at least this much
Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
- template <NodeType PvNode, bool SpNode, bool Root>
+ template <NodeType NT>
Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
- template <NodeType PvNode>
+ template <NodeType NT>
Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
- template <NodeType PvNode>
- inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
-
- return depth < ONE_PLY ? qsearch<PvNode>(pos, ss, alpha, beta, DEPTH_ZERO)
- : search<PvNode, false, false>(pos, ss, alpha, beta, depth);
- }
-
- template <NodeType PvNode>
- Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous);
-
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
Value value_to_tt(Value v, int ply);
void do_skill_level(Move* best, Move* ponder);
int current_search_time(int set = 0);
- std::string value_to_uci(Value v);
+ std::string score_to_uci(Value v, Value alpha, Value beta);
std::string speed_to_uci(int64_t nodes);
+ std::string pv_to_uci(Move pv[], int pvNum);
+ std::string depth_to_uci(Depth depth);
void poll(const Position& pos);
void wait_for_stop_or_ponderhit();
+ // MovePickerExt template class extends MovePicker and allows to choose at compile
+ // time the proper moves source according to the type of node. In the default case
+ // we simply create and use a standard MovePicker object.
+ template<NodeType> struct MovePickerExt : public MovePicker {
+
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b) {}
+
+ RootMove& current() { assert(false); return Rml[0]; } // Dummy, needed to compile
+ };
+
+ // In case of a SpNode we use split point's shared MovePicker object as moves source
+ template<> struct MovePickerExt<SplitPointNonPV> : public MovePickerExt<NonPV> {
+
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ : MovePickerExt<NonPV>(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
+
+ Move get_next_move() { return mp->get_next_move(); }
+ MovePicker* mp;
+ };
+
+ template<> struct MovePickerExt<SplitPointPV> : public MovePickerExt<SplitPointNonPV> {
+
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ : MovePickerExt<SplitPointNonPV>(p, ttm, d, h, ss, b) {}
+ };
+
+ // In case of a Root node we use RootMoveList as moves source
+ template<> struct MovePickerExt<Root> : public MovePicker {
+
+ MovePickerExt(const Position&, Move, Depth, const History&, SearchStack*, Value);
+ RootMove& current() { return Rml[cur]; }
+ Move get_next_move() { return ++cur < (int)Rml.size() ? Rml[cur].pv[0] : MOVE_NONE; }
+
+ int cur;
+ };
+
// Overload operator<<() to make it easier to print moves in a coordinate
// notation compatible with UCI protocol.
std::ostream& operator<<(std::ostream& os, Move m) {
return os;
}
+ // 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 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.
+ template <bool PvNode>
+ FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion,
+ bool moveIsCheck, bool* dangerous) {
+ assert(m != MOVE_NONE);
+
+ Depth result = DEPTH_ZERO;
+ *dangerous = moveIsCheck;
+
+ if (moveIsCheck && pos.see_sign(m) >= 0)
+ result += CheckExtension[PvNode];
+
+ if (pos.type_of_piece_on(move_from(m)) == PAWN)
+ {
+ Color c = pos.side_to_move();
+ if (relative_rank(c, move_to(m)) == RANK_7)
+ {
+ result += PawnPushTo7thExtension[PvNode];
+ *dangerous = true;
+ }
+ if (pos.pawn_is_passed(c, move_to(m)))
+ {
+ result += PassedPawnExtension[PvNode];
+ *dangerous = true;
+ }
+ }
+
+ 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_ZERO)
+ && !move_is_special(m))
+ {
+ result += PawnEndgameExtension[PvNode];
+ *dangerous = true;
+ }
+
+ return Min(result, ONE_PLY);
+ }
+
} // namespace
{
double pvRed = log(double(hd)) * log(double(mc)) / 3.0;
double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
- Reductions[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
- Reductions[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
+ Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
+ Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
}
// Init futility margins array
Limits = limits;
TimeMgr.init(Limits, pos.startpos_ply_counter());
+ // Set output steram in normal or chess960 mode
+ cout << set960(pos.is_chess960());
+
// Set best NodesBetweenPolls interval to avoid lagging under time pressure
if (Limits.maxNodes)
NodesBetweenPolls = Min(Limits.maxNodes, 30000);
// Read UCI options
UCIMultiPV = Options["MultiPV"].value<int>();
- SkillLevel = Options["Skill level"].value<int>();
+ SkillLevel = Options["Skill Level"].value<int>();
read_evaluation_uci_options(pos.side_to_move());
Threads.read_uci_options();
Move ponderMove = MOVE_NONE;
Move bestMove = id_loop(pos, searchMoves, &ponderMove);
- cout << "info" << speed_to_uci(pos.nodes_searched()) << endl;
-
// Write final search statistics and close log file
if (LogFile.is_open())
{
SearchStack ss[PLY_MAX_PLUS_2];
Value bestValues[PLY_MAX_PLUS_2];
int bestMoveChanges[PLY_MAX_PLUS_2];
- int depth, selDepth, aspirationDelta;
+ int depth, aspirationDelta;
Value value, alpha, beta;
Move bestMove, easyMove, skillBest, skillPonder;
Rml.init(pos, searchMoves);
// Handle special case of searching on a mate/stalemate position
- if (Rml.size() == 0)
+ if (!Rml.size())
{
- cout << "info depth 0 score "
- << value_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW)
- << endl;
+ cout << "info" << depth_to_uci(DEPTH_ZERO)
+ << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl;
return MOVE_NONE;
}
while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
{
Rml.bestMoveChanges = 0;
- cout << set960(pos.is_chess960()) << "info depth " << depth << endl;
// Calculate dynamic aspiration window based on previous iterations
if (MultiPV == 1 && depth >= 5 && abs(bestValues[depth - 1]) < VALUE_KNOWN_WIN)
// research with bigger window until not failing high/low anymore.
do {
// Search starting from ss+1 to allow calling update_gains()
- value = search<PV, false, true>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+ value = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
// Write PV back to transposition table in case the relevant entries
// have been overwritten during the search.
if (StopRequest)
break;
- assert(value >= alpha);
+ // Send full PV info to GUI if we are going to leave the loop or
+ // if we have a fail high/low and we are deep in the search.
+ if ((value > alpha && value < beta) || current_search_time() > 2000)
+ for (int i = 0; i < Min(UCIMultiPV, (int)Rml.size()); i++)
+ cout << "info"
+ << depth_to_uci(depth * ONE_PLY)
+ << score_to_uci(Rml[i].pv_score, alpha, beta)
+ << speed_to_uci(pos.nodes_searched())
+ << pv_to_uci(Rml[i].pv, i + 1) << endl;
// In case of failing high/low increase aspiration window and research,
// otherwise exit the fail high/low loop.
if (SkillLevelEnabled && depth == 1 + SkillLevel)
do_skill_level(&skillBest, &skillPonder);
- // Retrieve max searched depth among threads
- selDepth = 0;
- for (int i = 0; i < Threads.size(); i++)
- if (Threads[i].maxPly > selDepth)
- selDepth = Threads[i].maxPly;
-
- // Send PV line to GUI and to log file
- for (int i = 0; i < Min(UCIMultiPV, (int)Rml.size()); i++)
- cout << Rml[i].pv_info_to_uci(pos, depth, selDepth, alpha, beta, i) << endl;
-
if (LogFile.is_open())
LogFile << pretty_pv(pos, depth, value, current_search_time(), Rml[0].pv) << endl;
// all this work again. We also don't need to store anything to the hash table
// here: This is taken care of after we return from the split point.
- template <NodeType PvNode, bool SpNode, bool Root>
+ template <NodeType NT>
Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV);
+ const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV);
+ const bool RootNode = (NT == Root);
+
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
ValueType vt;
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
- bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous, isBadCap;
+ bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
int moveCount = 0, playedMoveCount = 0;
- int threadID = pos.thread();
+ Thread& thread = Threads[pos.thread()];
SplitPoint* sp = NULL;
refinedValue = bestValue = value = -VALUE_INFINITE;
ss->ply = (ss-1)->ply + 1;
// Used to send selDepth info to GUI
- if (PvNode && Threads[threadID].maxPly < ss->ply)
- Threads[threadID].maxPly = ss->ply;
+ if (PvNode && thread.maxPly < ss->ply)
+ thread.maxPly = ss->ply;
if (SpNode)
{
threatMove = sp->threatMove;
goto split_point_start;
}
- else if (Root)
- bestValue = alpha;
// Step 1. Initialize node and poll. Polling can abort search
ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE;
(ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
- (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE;
+ (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
- if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
+ if (pos.thread() == 0 && ++NodesSincePoll > NodesBetweenPolls)
{
NodesSincePoll = 0;
poll(pos);
// Step 2. Check for aborted search and immediate draw
if (( StopRequest
- || Threads[threadID].cutoff_occurred()
- || pos.is_draw()
- || ss->ply > PLY_MAX) && !Root)
+ || pos.is_draw<false>()
+ || ss->ply > PLY_MAX) && !RootNode)
return VALUE_DRAW;
// Step 3. Mate distance pruning
- alpha = Max(value_mated_in(ss->ply), alpha);
- beta = Min(value_mate_in(ss->ply+1), beta);
- if (alpha >= beta)
- return alpha;
+ if (!RootNode)
+ {
+ alpha = Max(value_mated_in(ss->ply), alpha);
+ beta = Min(value_mate_in(ss->ply+1), beta);
+ if (alpha >= beta)
+ return alpha;
+ }
// Step 4. Transposition table lookup
// We don't want the score of a partial search to overwrite a previous full search
// At PV nodes we check for exact scores, while at non-PV nodes we check for
// a fail high/low. Biggest advantage at probing at PV nodes is to have a
// smooth experience in analysis mode.
- if ( !Root
- && tte
- && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
- : ok_to_use_TT(tte, depth, beta, ss->ply)))
+ if (tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
+ : ok_to_use_TT(tte, depth, beta, ss->ply)))
{
TT.refresh(tte);
ss->bestMove = ttMove; // Can be MOVE_NONE
pos.do_null_move(st);
(ss+1)->skipNullMove = true;
- nullValue = -search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY);
+ nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY);
(ss+1)->skipNullMove = false;
pos.undo_null_move();
}
}
- // Step 9. Internal iterative deepening
+ // Step 9. ProbCut (is omitted in PV nodes)
+ // 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 ( !PvNode
+ && depth >= RazorDepth + ONE_PLY
+ && !inCheck
+ && !ss->skipNullMove
+ && excludedMove == MOVE_NONE
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX)
+ {
+ Value rbeta = beta + 200;
+ Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY;
+
+ assert(rdepth >= ONE_PLY);
+
+ MovePicker mp(pos, ttMove, H, Position::see_value(pos.captured_piece_type()));
+ CheckInfo ci(pos);
+
+ while ((move = mp.get_next_move()) != MOVE_NONE)
+ if (pos.pl_move_is_legal(move, ci.pinned))
+ {
+ pos.do_move(move, st, ci, pos.move_gives_check(move, ci));
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth);
+ pos.undo_move(move);
+ if (value >= rbeta)
+ return value;
+ }
+ }
+
+ // Step 10. Internal iterative deepening
if ( depth >= IIDDepth[PvNode]
&& ttMove == MOVE_NONE
&& (PvNode || (!inCheck && ss->eval + IIDMargin >= beta)))
Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
ss->skipNullMove = true;
- search<PvNode>(pos, ss, alpha, beta, d);
+ search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d);
ss->skipNullMove = false;
- ttMove = ss->bestMove;
tte = TT.probe(posKey);
+ ttMove = tte ? tte->move() : MOVE_NONE;
}
split_point_start: // At split points actual search starts from here
// Initialize a MovePicker object for the current position
- MovePickerExt<SpNode, Root> mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta));
+ MovePickerExt<NT> mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta);
CheckInfo ci(pos);
ss->bestMove = MOVE_NONE;
futilityBase = ss->eval + ss->evalMargin;
- singularExtensionNode = !Root
+ singularExtensionNode = !RootNode
&& !SpNode
&& depth >= SingularExtensionDepth[PvNode]
- && tte
- && tte->move()
+ && ttMove != MOVE_NONE
&& !excludedMove // Do not allow recursive singular extension search
&& (tte->type() & VALUE_TYPE_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
bestValue = sp->bestValue;
}
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ // Step 11. Loop through moves
+ // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !Threads[threadID].cutoff_occurred())
+ && !thread.cutoff_occurred())
{
assert(move_is_ok(move));
+ if (move == excludedMove)
+ continue;
+
+ // At PV and SpNode nodes we want the moves to be legal
+ if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, ci.pinned))
+ continue;
+
if (SpNode)
{
moveCount = ++sp->moveCount;
lock_release(&(sp->lock));
}
- else if (move == excludedMove)
- continue;
else
moveCount++;
- if (Root)
+ if (RootNode)
{
// This is used by time management
FirstRootMove = (moveCount == 1);
cout << "info" << speed_to_uci(pos.nodes_searched()) << endl;
}
+ // For long searches send to GUI current move
if (current_search_time() > 2000)
- cout << "info currmove " << move
- << " currmovenumber " << moveCount << endl;
+ cout << "info" << depth_to_uci(depth)
+ << " currmove " << move << " currmovenumber " << moveCount << endl;
}
// At Root and at first iteration do a PV search on all the moves to score root moves
- isPvMove = (PvNode && moveCount <= (Root ? depth <= ONE_PLY ? 1000 : MultiPV : 1));
+ isPvMove = (PvNode && moveCount <= (RootNode ? depth <= ONE_PLY ? MAX_MOVES : MultiPV : 1));
givesCheck = pos.move_gives_check(move, ci);
- captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ captureOrPromotion = pos.move_is_capture(move) || move_is_promotion(move);
- // Step 11. Decide the new search depth
+ // Step 12. Decide the new search depth
ext = extension<PvNode>(pos, move, captureOrPromotion, givesCheck, &dangerous);
// Singular extension search. If all moves but one fail low on a search of
// on all the other moves but the ttMove, if result is lower than ttValue minus
// a margin then we extend ttMove.
if ( singularExtensionNode
- && move == tte->move()
+ && move == ttMove
+ && pos.pl_move_is_legal(move, ci.pinned)
&& ext < ONE_PLY)
{
Value ttValue = value_from_tt(tte->value(), ss->ply);
}
// Update current move (this must be done after singular extension search)
- ss->currentMove = move;
newDepth = depth - ONE_PLY + ext;
- // Step 12. Futility pruning (is omitted in PV nodes)
+ // Step 13. Futility pruning (is omitted in PV nodes)
if ( !PvNode
&& !captureOrPromotion
&& !inCheck
// Value based pruning
// We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth,
// but fixing this made program slightly weaker.
- Depth predictedDepth = newDepth - reduction<NonPV>(depth, moveCount);
+ Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount)
+ H.gain(pos.piece_on(move_from(move)), move_to(move));
}
}
- // Bad capture detection. Will be used by prob-cut search
- isBadCap = depth >= 3 * ONE_PLY
- && depth < 8 * ONE_PLY
- && captureOrPromotion
- && move != ttMove
- && !dangerous
- && !move_is_promotion(move)
- && abs(alpha) < VALUE_MATE_IN_PLY_MAX
- && pos.see_sign(move) < 0;
-
- // Step 13. Make the move
+ // Check for legality only before to do the move
+ if (!pos.pl_move_is_legal(move, ci.pinned))
+ {
+ moveCount--;
+ continue;
+ }
+
+ ss->currentMove = move;
+
+ // Step 14. Make the move
pos.do_move(move, st, ci, givesCheck);
if (!SpNode && !captureOrPromotion)
// Step extra. pv search (only in PV nodes)
// The first move in list is the expected PV
if (isPvMove)
- {
- // Aspiration window is disabled in multi-pv case
- if (Root && MultiPV > 1)
- alpha = -VALUE_INFINITE;
-
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- }
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
else
{
- // Step 14. Reduced depth search
+ // Step 15. Reduced depth search
// If the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
alpha = SpNode ? sp->alpha : alpha;
- if ( depth >= 3 * ONE_PLY
+ if ( depth > 3 * ONE_PLY
&& !captureOrPromotion
&& !dangerous
&& !move_is_castle(move)
ss->reduction = reduction<PvNode>(depth, moveCount);
if (ss->reduction)
{
- alpha = SpNode ? sp->alpha : alpha;
Depth d = newDepth - ss->reduction;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
-
+ value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
doFullDepthSearch = (value > alpha);
}
ss->reduction = DEPTH_ZERO; // Restore original reduction
}
- // Probcut search for bad captures. If a reduced search returns a value
- // very below beta then we can (almost) safely prune the bad capture.
- if (isBadCap)
- {
- ss->reduction = 3 * ONE_PLY;
- Value rAlpha = alpha - 300;
- Depth d = newDepth - ss->reduction;
- value = -search<NonPV>(pos, ss+1, -(rAlpha+1), -rAlpha, d);
- doFullDepthSearch = (value > rAlpha);
- ss->reduction = DEPTH_ZERO; // Restore original reduction
- }
-
- // Step 15. Full depth search
+ // Step 16. Full depth search
if (doFullDepthSearch)
{
alpha = SpNode ? sp->alpha : alpha;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
// Step extra. pv search (only in PV nodes)
// Search only for possible new PV nodes, if instead value >= beta then
// parent node fails low with value <= alpha and tries another move.
- if (PvNode && value > alpha && (Root || value < beta))
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+ if (PvNode && value > alpha && (RootNode || value < beta))
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
}
}
- // Step 16. Undo move
+ // Step 17. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // Step 17. Check for new best move
+ // Step 18. Check for new best move
if (SpNode)
{
lock_grab(&(sp->lock));
alpha = sp->alpha;
}
- if (value > bestValue && !(SpNode && Threads[threadID].cutoff_occurred()))
+ if (value > bestValue && !(SpNode && thread.cutoff_occurred()))
{
bestValue = value;
if (SpNode)
sp->bestValue = value;
- if (!Root && value > alpha)
+ if (!RootNode && value > alpha)
{
if (PvNode && value < beta) // We want always alpha < beta
{
else if (SpNode)
sp->is_betaCutoff = true;
- if (value == value_mate_in(ss->ply + 1))
- ss->mateKiller = move;
-
ss->bestMove = move;
if (SpNode)
}
}
- if (Root)
+ if (RootNode)
{
// Finished searching the move. If StopRequest is true, the search
// was aborted because the user interrupted the search or because we
break;
// Remember searched nodes counts for this move
- mp.rm->nodes += pos.nodes_searched() - nodes;
+ mp.current().nodes += pos.nodes_searched() - nodes;
// PV move or new best move ?
if (isPvMove || value > alpha)
{
// Update PV
ss->bestMove = move;
- mp.rm->pv_score = value;
- mp.rm->extract_pv_from_tt(pos);
+ mp.current().pv_score = value;
+ mp.current().extract_pv_from_tt(pos);
// We record how often the best move has been changed in each
// iteration. This information is used for time management: When
if (!isPvMove && MultiPV == 1)
Rml.bestMoveChanges++;
- Rml.sort_multipv(moveCount);
+ // It is critical that sorting is done with a stable algorithm
+ // because all the values but the first are usually set to
+ // -VALUE_INFINITE and we want to keep the same order for all
+ // the moves but the new PV that goes to head.
+ Rml.sort_first(moveCount);
- // Update alpha. In multi-pv we don't use aspiration window, so
- // set alpha equal to minimum score among the PV lines.
+ // Update alpha. In multi-pv we don't use aspiration window, so set
+ // alpha equal to minimum score among the PV lines searched so far.
if (MultiPV > 1)
- alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score; // FIXME why moveCount?
+ alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score;
else if (value > alpha)
alpha = value;
}
else
- mp.rm->pv_score = -VALUE_INFINITE;
+ // All other moves but the PV are set to the lowest value, this
+ // is not a problem when sorting becuase sort is stable and move
+ // position in the list is preserved, just the PV is pushed up.
+ mp.current().pv_score = -VALUE_INFINITE;
- } // Root
+ } // RootNode
- // Step 18. Check for split
- if ( !Root
+ // Step 19. Check for split
+ if ( !RootNode
&& !SpNode
&& depth >= Threads.min_split_depth()
&& bestValue < beta
- && Threads.available_slave_exists(threadID)
+ && Threads.available_slave_exists(pos.thread())
&& !StopRequest
- && !Threads[threadID].cutoff_occurred())
+ && !thread.cutoff_occurred())
Threads.split<FakeSplit>(pos, ss, &alpha, beta, &bestValue, depth,
threatMove, moveCount, &mp, PvNode);
}
- // Step 19. Check for mate and stalemate
+ // Step 20. Check for mate and stalemate
// All legal moves have been searched and if there are
// no legal moves, it must be mate or stalemate.
// If one move was excluded return fail low score.
if (!SpNode && !moveCount)
return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
- // Step 20. Update tables
+ // Step 21. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (!SpNode && !StopRequest && !Threads[threadID].cutoff_occurred())
+ if (!SpNode && !StopRequest && !thread.cutoff_occurred())
{
move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
// Update killers and history only for non capture moves that fails high
if ( bestValue >= beta
- && !pos.move_is_capture_or_promotion(move))
+ && !pos.move_is_capture(move)
+ && !move_is_promotion(move))
{
if (move != ss->killers[0])
{
if (SpNode)
{
// Here we have the lock still grabbed
- sp->is_slave[threadID] = false;
+ sp->is_slave[pos.thread()] = false;
sp->nodes += pos.nodes_searched();
lock_release(&(sp->lock));
}
// search function when the remaining depth is zero (or, to be more precise,
// less than ONE_PLY).
- template <NodeType PvNode>
+ template <NodeType NT>
Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ const bool PvNode = (NT == PV);
+
+ assert(NT == PV || NT == NonPV);
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
- if (ss->ply > PLY_MAX || pos.is_draw())
+ if (pos.is_draw<true>() || ss->ply > PLY_MAX)
return VALUE_DRAW;
// Decide whether or not to include checks, this fixes also the type of
else
ss->eval = bestValue = evaluate(pos, evalMargin);
- update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
-
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
{
// 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, H);
+ MovePicker mp(pos, ttMove, depth, H, move_to((ss-1)->currentMove));
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
}
// Detect non-capture evasions that are candidate to be pruned
- evasionPrunable = inCheck
+ evasionPrunable = !PvNode
+ && inCheck
&& bestValue > VALUE_MATED_IN_PLY_MAX
&& !pos.move_is_capture(move)
&& !pos.can_castle(pos.side_to_move());
&& !inCheck
&& givesCheck
&& move != ttMove
- && !pos.move_is_capture_or_promotion(move)
+ && !pos.move_is_capture(move)
+ && !move_is_promotion(move)
&& ss->eval + PawnValueMidgame / 4 < beta
&& !check_is_dangerous(pos, move, futilityBase, beta, &bestValue))
{
continue;
}
+ // Check for legality only before to do the move
+ if (!pos.pl_move_is_legal(move, ci.pinned))
+ continue;
+
// Update current move
ss->currentMove = move;
// Make and search the move
pos.do_move(move, st, ci, givesCheck);
- value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-ONE_PLY);
+ value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth-ONE_PLY);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
}
- // 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 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.
- template <NodeType PvNode>
- Depth extension(const Position& pos, Move m, bool captureOrPromotion,
- bool moveIsCheck, bool* dangerous) {
-
- assert(m != MOVE_NONE);
-
- Depth result = DEPTH_ZERO;
- *dangerous = moveIsCheck;
-
- if (moveIsCheck && pos.see_sign(m) >= 0)
- result += CheckExtension[PvNode];
-
- if (pos.type_of_piece_on(move_from(m)) == PAWN)
- {
- Color c = pos.side_to_move();
- if (relative_rank(c, move_to(m)) == RANK_7)
- {
- result += PawnPushTo7thExtension[PvNode];
- *dangerous = true;
- }
- if (pos.pawn_is_passed(c, move_to(m)))
- {
- result += PassedPawnExtension[PvNode];
- *dangerous = true;
- }
- }
-
- 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_ZERO)
- && !move_is_special(m))
- {
- result += PawnEndgameExtension[PvNode];
- *dangerous = true;
- }
-
- return Min(result, ONE_PLY);
- }
-
-
// connected_threat() tests whether it is safe to forward prune a move or if
// is somehow connected to the threat move returned by null search.
assert(move_is_ok(m));
assert(threat && move_is_ok(threat));
- assert(!pos.move_gives_check(m));
- assert(!pos.move_is_capture_or_promotion(m));
+ assert(!pos.move_is_capture(m) && !move_is_promotion(m));
assert(!pos.move_is_passed_pawn_push(m));
Square mfrom, mto, tfrom, tto;
}
- // value_to_uci() converts a value to a string suitable for use with the UCI
+ // score_to_uci() converts a value to a string suitable for use with the UCI
// protocol specifications:
//
// cp <x> The score from the engine's point of view in centipawns.
// mate <y> Mate in y moves, not plies. If the engine is getting mated
// use negative values for y.
- std::string value_to_uci(Value v) {
+ std::string score_to_uci(Value v, Value alpha, Value beta) {
std::stringstream s;
if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY)
- s << "cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns
+ s << " score cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns
else
- s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
+ s << " score mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
+
+ s << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
return s.str();
}
int t = current_search_time();
s << " nodes " << nodes
- << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
+ << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
<< " time " << t;
return s.str();
}
+ // pv_to_uci() returns a string with information on the current PV line
+ // formatted according to UCI specification.
+
+ std::string pv_to_uci(Move pv[], int pvNum) {
+
+ std::stringstream s;
+
+ s << " multipv " << pvNum << " pv ";
+
+ for ( ; *pv != MOVE_NONE; pv++)
+ s << *pv << " ";
+
+ return s.str();
+ }
+
+ // depth_to_uci() returns a string with information on the current depth and
+ // seldepth formatted according to UCI specification.
+
+ std::string depth_to_uci(Depth depth) {
+
+ std::stringstream s;
+
+ // Retrieve max searched depth among threads
+ int selDepth = 0;
+ for (int i = 0; i < Threads.size(); i++)
+ if (Threads[i].maxPly > selDepth)
+ selDepth = Threads[i].maxPly;
+
+ s << " depth " << depth / ONE_PLY << " seldepth " << selDepth;
+
+ return s.str();
+ }
+
// poll() performs two different functions: It polls for user input, and it
// looks at the time consumed so far and decides if it's time to abort the
TTEntry* tte;
int ply = 1;
- assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0]));
+ assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0]));
pos.do_move(pv[0], *st++);
while ( (tte = TT.probe(pos.get_key())) != NULL
&& tte->move() != MOVE_NONE
- && pos.move_is_legal(tte->move())
+ && pos.move_is_pl(tte->move())
+ && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces(pos.side_to_move()))
&& ply < PLY_MAX
- && (!pos.is_draw() || ply < 2))
+ && (!pos.is_draw<false>() || ply < 2))
{
pv[ply] = tte->move();
pos.do_move(pv[ply++], *st++);
Value v, m = VALUE_NONE;
int ply = 0;
- assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0]));
+ assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0]));
do {
k = pos.get_key();
do pos.undo_move(pv[--ply]); while (ply);
}
- // pv_info_to_uci() returns a string with information on the current PV line
- // formatted according to UCI specification.
-
- std::string RootMove::pv_info_to_uci(Position& pos, int depth, int selDepth, Value alpha,
- Value beta, int pvIdx) {
- std::stringstream s;
-
- s << "info depth " << depth
- << " seldepth " << selDepth
- << " multipv " << pvIdx + 1
- << " score " << value_to_uci(pv_score)
- << (pv_score >= beta ? " lowerbound" : pv_score <= alpha ? " upperbound" : "")
- << speed_to_uci(pos.nodes_searched())
- << " pv ";
-
- for (Move* m = pv; *m != MOVE_NONE; m++)
- s << *m << " ";
-
- return s.str();
- }
-
// Specializations for MovePickerExt in case of Root node
- MovePickerExt<false, true>::MovePickerExt(const Position& p, Move ttm, Depth d,
- const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b), firstCall(true) {
+ MovePickerExt<Root>::MovePickerExt(const Position& p, Move ttm, Depth d,
+ const History& h, SearchStack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b), cur(-1) {
Move move;
Value score = VALUE_ZERO;
// This is the second order score that is used to compare the moves when
// the first orders pv_score of both moves are equal.
while ((move = MovePicker::get_next_move()) != MOVE_NONE)
- for (rm = Rml.begin(); rm != Rml.end(); ++rm)
+ for (RootMoveList::iterator rm = Rml.begin(); rm != Rml.end(); ++rm)
if (rm->pv[0] == move)
{
rm->non_pv_score = score--;
}
Rml.sort();
- rm = Rml.begin();
- }
-
- Move MovePickerExt<false, true>::get_next_move() {
-
- if (!firstCall)
- ++rm;
- else
- firstCall = false;
-
- return rm != Rml.end() ? rm->pv[0] : MOVE_NONE;
}
} // namespace
(ss+1)->sp = tsp;
if (tsp->pvNode)
- search<PV, true, false>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ search<SplitPointPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
else
- search<NonPV, true, false>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ search<SplitPointNonPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
assert(threads[threadID].state == Thread::SEARCHING);
projects / stockfish / blobdiff