along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
+#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
-#include <fstream>
+#include <iomanip>
#include <iostream>
#include <sstream>
#include <vector>
#include "evaluate.h"
#include "history.h"
#include "misc.h"
-#include "move.h"
#include "movegen.h"
#include "movepick.h"
-#include "lock.h"
#include "search.h"
#include "timeman.h"
#include "thread.h"
#include "tt.h"
#include "ucioption.h"
+namespace Search {
+
+ volatile SignalsType Signals;
+ LimitsType Limits;
+ std::vector<Move> SearchMoves;
+ Position RootPosition;
+}
+
+using std::string;
using std::cout;
using std::endl;
-
-////
-//// Local definitions
-////
+using namespace Search;
namespace {
- // Types
- enum NodeType { NonPV, PV };
-
- // Set to true to force running with one thread.
- // Used for debugging SMP code.
+ // Set to true to force running with one thread. Used for debugging
const bool FakeSplit = false;
- // Fast lookup table of sliding pieces indexed by Piece
- const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
- inline bool piece_is_slider(Piece p) { return Slidings[p]; }
-
- // ThreadsManager class is used to handle all the threads related stuff in search,
- // init, starting, parking and, the most important, launching a slave thread at a
- // split point are what this class does. All the access to shared thread data is
- // done through this class, so that we avoid using global variables instead.
-
- class ThreadsManager {
- /* As long as the single ThreadsManager object is defined as a global we don't
- need to explicitly initialize to zero its data members because variables with
- static storage duration are automatically set to zero before enter main()
- */
- public:
- void init_threads();
- void exit_threads();
-
- int min_split_depth() const { return minimumSplitDepth; }
- int active_threads() const { return activeThreads; }
- void set_active_threads(int cnt) { activeThreads = cnt; }
-
- void read_uci_options();
- bool available_thread_exists(int master) const;
- bool thread_is_available(int slave, int master) const;
- bool cutoff_at_splitpoint(int threadID) const;
- void wake_sleeping_thread(int threadID);
- void idle_loop(int threadID, SplitPoint* sp);
-
- template <bool Fake>
- void split(Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
- Depth depth, Move threatMove, bool mateThreat, int moveCount, MovePicker* mp, bool pvNode);
-
- private:
- Depth minimumSplitDepth;
- int maxThreadsPerSplitPoint;
- bool useSleepingThreads;
- int activeThreads;
- volatile bool allThreadsShouldExit;
- Thread threads[MAX_THREADS];
- Lock mpLock, sleepLock[MAX_THREADS];
- WaitCondition sleepCond[MAX_THREADS];
- };
-
-
- // RootMove struct is used for moves at the root at the tree. For each root
- // move, we store two scores, a node count, and a PV (really a refutation
- // in the case of moves which fail low). Value pv_score is normally set at
- // -VALUE_INFINITE for all non-pv moves, while non_pv_score is computed
- // according to the order in which moves are returned by MovePicker.
+ // Different node types, used as template parameter
+ enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
+ // RootMove struct is used for moves at the root of 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). Score is normally set at -VALUE_INFINITE for
+ // all non-pv moves.
struct RootMove {
- RootMove();
- RootMove(const RootMove& rm) { *this = rm; }
- RootMove& operator=(const RootMove& rm);
-
- // RootMove::operator<() is the comparison function used when
- // sorting the moves. A move m1 is considered to be better
- // than a move m2 if it has an higher pv_score, or if it has
- // equal pv_score but m1 has the higher non_pv_score. In this
- // way we are guaranteed that PV moves are always sorted as first.
- bool operator<(const RootMove& m) const {
- return pv_score != m.pv_score ? pv_score < m.pv_score
- : non_pv_score < m.non_pv_score;
+ RootMove(){}
+ RootMove(Move m) {
+ nodes = 0;
+ score = prevScore = -VALUE_INFINITE;
+ pv.push_back(m);
+ pv.push_back(MOVE_NONE);
}
+ bool operator<(const RootMove& m) const { return score < m.score; }
+ bool operator==(const Move& m) const { return pv[0] == m; }
+
void extract_pv_from_tt(Position& pos);
void insert_pv_in_tt(Position& pos);
- std::string pv_info_to_uci(Position& pos, Depth depth, Value alpha, Value beta, int pvLine = 0);
int64_t nodes;
- Value pv_score;
- Value non_pv_score;
- Move pv[PLY_MAX_PLUS_2];
- };
-
-
- // RootMoveList struct is essentially a std::vector<> of RootMove objects,
- // with an handful of methods above the standard ones.
-
- struct RootMoveList : public std::vector<RootMove> {
-
- typedef std::vector<RootMove> Base;
-
- 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); }
-
- int bestMoveChanges;
+ Value score;
+ Value prevScore;
+ std::vector<Move> pv;
};
- // When formatting a move for std::cout we must know if we are in Chess960
- // or not. To keep using the handy operator<<() on the move the trick is to
- // embed this flag in the stream itself. Function-like named enum set960 is
- // used as a custom manipulator and the stream internal general-purpose array,
- // accessed through ios_base::iword(), is used to pass the flag to the move's
- // operator<<() that will use it to properly format castling moves.
- enum set960 {};
-
- std::ostream& operator<< (std::ostream& os, const set960& f) {
-
- os.iword(0) = int(f);
- return os;
- }
-
-
- // Overload operator << for moves to make it easier to print moves in
- // coordinate notation compatible with UCI protocol.
- std::ostream& operator<<(std::ostream& os, Move m) {
-
- bool chess960 = (os.iword(0) != 0); // See set960()
- return os << move_to_uci(m, chess960);
- }
-
-
- /// Adjustments
+ /// Constants
- // Step 6. Razoring
+ // Lookup table to check if a Piece is a slider and its access function
+ const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
+ inline bool piece_is_slider(Piece p) { return Slidings[p]; }
// Maximum depth for razoring
const Depth RazorDepth = 4 * ONE_PLY;
// Maximum depth for use of dynamic threat detection when null move fails low
const Depth ThreatDepth = 5 * ONE_PLY;
- // Step 9. Internal iterative deepening
-
// Minimum depth for use of internal iterative deepening
- const Depth IIDDepth[2] = { 8 * ONE_PLY /* non-PV */, 5 * ONE_PLY /* PV */};
+ const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY };
// At Non-PV nodes we do an internal iterative deepening search
// when the static evaluation is bigger then beta - IIDMargin.
const Value IIDMargin = Value(0x100);
- // Step 11. Decide the new search depth
-
- // Extensions. Configurable UCI options
- // Array index 0 is used at non-PV nodes, index 1 at PV nodes.
- Depth CheckExtension[2], PawnPushTo7thExtension[2], PassedPawnExtension[2];
- Depth PawnEndgameExtension[2], MateThreatExtension[2];
-
// Minimum depth for use of singular extension
- const Depth SingularExtensionDepth[2] = { 8 * ONE_PLY /* non-PV */, 6 * ONE_PLY /* PV */};
-
- // If the TT move is at least SingularExtensionMargin better then the
- // remaining ones we will extend it.
- const Value SingularExtensionMargin = Value(0x20);
-
- // Step 12. Futility pruning
+ const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY };
// Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
- // Futility lookup tables (initialized at startup) and their getter functions
- Value FutilityMarginsMatrix[16][64]; // [depth][moveNumber]
- int FutilityMoveCountArray[32]; // [depth]
+ // Futility lookup tables (initialized at startup) and their access functions
+ Value FutilityMargins[16][64]; // [depth][moveNumber]
+ int FutilityMoveCounts[32]; // [depth]
- inline Value futility_margin(Depth d, int mn) { return d < 7 * ONE_PLY ? FutilityMarginsMatrix[Max(d, 1)][Min(mn, 63)] : 2 * VALUE_INFINITE; }
- inline int futility_move_count(Depth d) { return d < 16 * ONE_PLY ? FutilityMoveCountArray[d] : 512; }
+ inline Value futility_margin(Depth d, int mn) {
- // Step 14. Reduced search
+ return d < 7 * ONE_PLY ? FutilityMargins[std::max(int(d), 1)][std::min(mn, 63)]
+ : 2 * VALUE_INFINITE;
+ }
- // Reduction lookup tables (initialized at startup) and their getter functions
- int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber]
+ inline int futility_move_count(Depth d) {
- template <NodeType PV>
- inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; }
+ return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES;
+ }
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
+ // Reduction lookup tables (initialized at startup) and their access function
+ int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
+ template <bool PvNode> inline Depth reduction(Depth d, int mn) {
- /// Namespace variables
+ return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
+ }
- // Book object
- Book OpeningBook;
+ // Easy move margin. An easy move candidate must be at least this much
+ // better than the second best move.
+ const Value EasyMoveMargin = Value(0x150);
- // Root move list
- RootMoveList Rml;
- // MultiPV mode
- int MultiPV;
+ /// Namespace variables
- // Time managment variables
- int SearchStartTime, MaxNodes, MaxDepth, ExactMaxTime;
- bool UseTimeManagement, InfiniteSearch, Pondering, StopOnPonderhit;
- bool FirstRootMove, StopRequest, QuitRequest, AspirationFailLow;
+ std::vector<RootMove> RootMoves;
+ size_t MultiPV, UCIMultiPV, PVIdx;
TimeManager TimeMgr;
-
- // Log file
- bool UseLogFile;
- std::ofstream LogFile;
-
- // Multi-threads manager object
- ThreadsManager ThreadsMgr;
-
- // Node counters, used only by thread[0] but try to keep in different cache
- // lines (64 bytes each) from the heavy multi-thread read accessed variables.
- bool SendSearchedNodes;
- int NodesSincePoll;
- int NodesBetweenPolls = 30000;
-
- // History table
+ int BestMoveChanges;
+ int SkillLevel;
+ bool SkillLevelEnabled, Chess960;
History H;
- /// Local functions
-
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
- template <NodeType PvNode, bool SpNode, bool Root>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply);
-
- template <NodeType PvNode>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply);
-
- template <NodeType PvNode>
- inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) {
+ /// Local functions
- return depth < ONE_PLY ? qsearch<PvNode>(pos, ss, alpha, beta, DEPTH_ZERO, ply)
- : search<PvNode, false, false>(pos, ss, alpha, beta, depth, ply);
- }
+ template <NodeType NT>
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
- template <NodeType PvNode>
- Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool mateThreat, bool* dangerous);
+ template <NodeType NT>
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
+ void id_loop(Position& pos);
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
- bool value_is_mate(Value value);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
- bool ok_to_use_TT_PV(const TTEntry* tte, Depth depth, Value alpha, Value beta, int ply);
+ bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply);
bool connected_threat(const Position& pos, Move m, Move threat);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
- void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
- void update_killers(Move m, Move killers[]);
- void update_gains(const Position& pos, Move move, Value before, Value after);
- void qsearch_scoring(Position& pos, MoveStack* mlist, MoveStack* last);
-
- int current_search_time();
- std::string value_to_uci(Value v);
- int nps(const Position& pos);
- void poll(const Position& pos);
- void wait_for_stop_or_ponderhit();
-
-#if !defined(_MSC_VER)
- void* init_thread(void* threadID);
-#else
- DWORD WINAPI init_thread(LPVOID threadID);
-#endif
-
-
- // MovePickerExt is an extended MovePicker used to choose at compile time
- // the proper move source according to the type of node.
- template<bool SpNode, bool Root> struct MovePickerExt;
-
- // In Root nodes use RootMoveList Rml as source. Score and sort the root moves
- // before to search them.
- template<> struct MovePickerExt<false, true> : public MovePicker {
-
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b), firstCall(true) {
- Move move;
- Value score = VALUE_ZERO;
-
- // Score root moves using the standard way used in main search, the moves
- // are scored according to the order in which are returned by MovePicker.
- // This is the second order score that is used to compare the moves when
- // the first order pv scores of both moves are equal.
- while ((move = MovePicker::get_next_move()) != MOVE_NONE)
- for (rm = Rml.begin(); rm != Rml.end(); ++rm)
- if (rm->pv[0] == move)
- {
- rm->non_pv_score = score--;
- break;
- }
-
- Rml.sort();
- rm = Rml.begin();
- }
-
- Move get_next_move() {
-
- if (!firstCall)
- ++rm;
- else
- firstCall = false;
-
- return rm != Rml.end() ? rm->pv[0] : MOVE_NONE;
- }
-
- RootMoveList::iterator rm;
- bool firstCall;
+ Move do_skill_level();
+ int elapsed_time(bool reset = false);
+ string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE);
+ void pv_info_to_log(Position& pos, int depth, Value score, int time, Move pv[]);
+ void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta);
+
+ // MovePickerExt class template 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> struct MovePickerExt : public MovePicker {
+
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b) {}
};
- // In SpNodes use split point's shared MovePicker object as move 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) {}
+ // In case of a SpNode we use split point's shared MovePicker object as moves source
+ template<> struct MovePickerExt<true> : public MovePicker {
- Move get_next_move() { return mp->get_next_move(); }
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
- RootMoveList::iterator rm; // Dummy, needed to compile
+ Move next_move() { return mp->next_move(); }
MovePicker* mp;
};
- // Default case, create and use a MovePicker object as source
- template<> struct MovePickerExt<false, 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) {}
-
- RootMoveList::iterator rm; // Dummy, needed to compile
- };
-
-} // namespace
+ // is_dangerous() checks whether a move belongs to some classes of known
+ // 'dangerous' moves so that we avoid to prune it.
+ FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
+ // Test for a pawn pushed to 7th or a passed pawn move
+ if (type_of(pos.piece_on(move_from(m))) == PAWN)
+ {
+ Color c = pos.side_to_move();
+ if ( relative_rank(c, move_to(m)) == RANK_7
+ || pos.pawn_is_passed(c, move_to(m)))
+ return true;
+ }
-////
-//// Functions
-////
+ // Test for a capture that triggers a pawn endgame
+ if ( captureOrPromotion
+ && type_of(pos.piece_on(move_to(m))) != PAWN
+ && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
+ - PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO)
+ && !is_special(m))
+ return true;
-/// init_threads(), exit_threads() and nodes_searched() are helpers to
-/// give accessibility to some TM methods from outside of current file.
+ return false;
+ }
-void init_threads() { ThreadsMgr.init_threads(); }
-void exit_threads() { ThreadsMgr.exit_threads(); }
+} // namespace
-/// init_search() is called during startup. It initializes various lookup tables
+/// Search::init() is called during startup to initialize various lookup tables
-void init_search() {
+void Search::init() {
int d; // depth (ONE_PLY == 2)
int hd; // half depth (ONE_PLY == 1)
{
double pvRed = log(double(hd)) * log(double(mc)) / 3.0;
double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
- ReductionMatrix[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
- ReductionMatrix[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
for (d = 1; d < 16; d++) for (mc = 0; mc < 64; mc++)
- FutilityMarginsMatrix[d][mc] = Value(112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45);
+ FutilityMargins[d][mc] = Value(112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45);
// Init futility move count array
for (d = 0; d < 32; d++)
- FutilityMoveCountArray[d] = int(3.001 + 0.25 * pow(d, 2.0));
+ FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(d, 2.0));
}
-/// 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.
+/// Search::perft() is our utility to verify move generation. All the leaf nodes
+/// up to the given depth are generated and counted and the sum returned.
-int64_t perft(Position& pos, Depth depth)
-{
- MoveStack mlist[MOVES_MAX];
- StateInfo st;
- Move m;
- int64_t sum = 0;
+int64_t Search::perft(Position& pos, Depth depth) {
- // Generate all legal moves
- MoveStack* last = generate<MV_LEGAL>(pos, mlist);
+ StateInfo st;
+ int64_t sum = 0;
- // If we are at the last ply we don't need to do and undo
- // the moves, just to count them.
- if (depth <= ONE_PLY)
- return int(last - mlist);
+ MoveList<MV_LEGAL> ml(pos);
- // Loop through all legal moves
- CheckInfo ci(pos);
- for (MoveStack* cur = mlist; cur != last; cur++)
- {
- m = cur->move;
- pos.do_move(m, st, ci, pos.move_is_check(m, ci));
- sum += perft(pos, depth - ONE_PLY);
- pos.undo_move(m);
- }
- return sum;
+ // At the last ply just return the number of moves (leaf nodes)
+ if (depth <= ONE_PLY)
+ return ml.size();
+
+ CheckInfo ci(pos);
+ for ( ; !ml.end(); ++ml)
+ {
+ pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci));
+ sum += perft(pos, depth - ONE_PLY);
+ pos.undo_move(ml.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 id_loop(). It returns false
-/// when a quit command is received during the search.
+/// Search::think() is the external interface to Stockfish's search, and is
+/// called by the main thread when the program receives the UCI 'go' command. It
+/// searches from RootPosition and at the end prints the "bestmove" to output.
+
+void Search::think() {
+
+ static Book book; // Defined static to initialize the PRNG only once
-bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[],
- int movesToGo, int maxDepth, int maxNodes, int maxTime, Move searchMoves[]) {
+ Position& pos = RootPosition;
+ Chess960 = pos.is_chess960();
+ elapsed_time(true);
+ TimeMgr.init(Limits, pos.startpos_ply_counter());
+ TT.new_search();
+ H.clear();
+ RootMoves.clear();
- // Initialize global search variables
- StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false;
- NodesSincePoll = 0;
- SearchStartTime = get_system_time();
- ExactMaxTime = maxTime;
- MaxDepth = maxDepth;
- MaxNodes = maxNodes;
- InfiniteSearch = infinite;
- Pondering = ponder;
- UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch;
+ // Populate RootMoves with all the legal moves (default) or, if a SearchMoves
+ // is given, with the subset of legal moves to search.
+ for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
+ if ( SearchMoves.empty()
+ || count(SearchMoves.begin(), SearchMoves.end(), ml.move()))
+ RootMoves.push_back(RootMove(ml.move()));
- // Look for a book move, only during games, not tests
- if (UseTimeManagement && Options["OwnBook"].value<bool>())
+ if (Options["OwnBook"].value<bool>())
{
- if (Options["Book File"].value<std::string>() != OpeningBook.name())
- OpeningBook.open(Options["Book File"].value<std::string>());
+ if (Options["Book File"].value<string>() != book.name())
+ book.open(Options["Book File"].value<string>());
- Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value<bool>());
- if (bookMove != MOVE_NONE)
- {
- if (Pondering)
- wait_for_stop_or_ponderhit();
+ Move bookMove = book.probe(pos, Options["Best Book Move"].value<bool>());
- cout << "bestmove " << bookMove << endl;
- return !QuitRequest;
+ if ( bookMove != MOVE_NONE
+ && count(RootMoves.begin(), RootMoves.end(), bookMove))
+ {
+ std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), bookMove));
+ goto finish;
}
}
- // Read UCI option values
+ // Read UCI options: GUI could change UCI parameters during the game
+ read_evaluation_uci_options(pos.side_to_move());
+ Threads.read_uci_options();
+
TT.set_size(Options["Hash"].value<int>());
if (Options["Clear Hash"].value<bool>())
{
TT.clear();
}
- CheckExtension[1] = Options["Check Extension (PV nodes)"].value<Depth>();
- CheckExtension[0] = Options["Check Extension (non-PV nodes)"].value<Depth>();
- PawnPushTo7thExtension[1] = Options["Pawn Push to 7th Extension (PV nodes)"].value<Depth>();
- PawnPushTo7thExtension[0] = Options["Pawn Push to 7th Extension (non-PV nodes)"].value<Depth>();
- PassedPawnExtension[1] = Options["Passed Pawn Extension (PV nodes)"].value<Depth>();
- PassedPawnExtension[0] = Options["Passed Pawn Extension (non-PV nodes)"].value<Depth>();
- PawnEndgameExtension[1] = Options["Pawn Endgame Extension (PV nodes)"].value<Depth>();
- PawnEndgameExtension[0] = Options["Pawn Endgame Extension (non-PV nodes)"].value<Depth>();
- MateThreatExtension[1] = Options["Mate Threat Extension (PV nodes)"].value<Depth>();
- MateThreatExtension[0] = Options["Mate Threat Extension (non-PV nodes)"].value<Depth>();
- MultiPV = Options["MultiPV"].value<int>();
- UseLogFile = Options["Use Search Log"].value<bool>();
+ UCIMultiPV = Options["MultiPV"].value<size_t>();
+ SkillLevel = Options["Skill Level"].value<int>();
- read_evaluation_uci_options(pos.side_to_move());
+ // Do we have to play with skill handicap? In this case enable MultiPV that
+ // we will use behind the scenes to retrieve a set of possible moves.
+ SkillLevelEnabled = (SkillLevel < 20);
+ MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV);
- // Set the number of active threads
- ThreadsMgr.read_uci_options();
- init_eval(ThreadsMgr.active_threads());
-
- // Wake up needed threads
- for (int i = 1; i < ThreadsMgr.active_threads(); i++)
- ThreadsMgr.wake_sleeping_thread(i);
-
- // Set thinking time
- int myTime = time[pos.side_to_move()];
- int myIncrement = increment[pos.side_to_move()];
- if (UseTimeManagement)
- TimeMgr.init(myTime, myIncrement, movesToGo, pos.startpos_ply_counter());
-
- // Set best NodesBetweenPolls interval to avoid lagging under
- // heavy time pressure.
- if (MaxNodes)
- NodesBetweenPolls = Min(MaxNodes, 30000);
- else if (myTime && myTime < 1000)
- NodesBetweenPolls = 1000;
- else if (myTime && myTime < 5000)
- NodesBetweenPolls = 5000;
- else
- NodesBetweenPolls = 30000;
+ if (Options["Use Search Log"].value<bool>())
+ {
+ Log log(Options["Search Log Filename"].value<string>());
+ log << "\nSearching: " << pos.to_fen()
+ << "\ninfinite: " << Limits.infinite
+ << " ponder: " << Limits.ponder
+ << " time: " << Limits.time
+ << " increment: " << Limits.increment
+ << " moves to go: " << Limits.movesToGo
+ << endl;
+ }
- // Write search information to log file
- if (UseLogFile)
+ for (int i = 0; i < Threads.size(); i++)
{
- std::string name = Options["Search Log Filename"].value<std::string>();
- LogFile.open(name.c_str(), std::ios::out | std::ios::app);
-
- LogFile << "Searching: " << pos.to_fen()
- << "\ninfinite: " << infinite
- << " ponder: " << ponder
- << " time: " << myTime
- << " increment: " << myIncrement
- << " moves to go: " << movesToGo << endl;
+ Threads[i].maxPly = 0;
+ Threads[i].wake_up();
}
- // We're ready to start thinking. Call the iterative deepening loop function
- Move ponderMove = MOVE_NONE;
- Move bestMove = id_loop(pos, searchMoves, &ponderMove);
+ // Set best timer interval to avoid lagging under time pressure. Timer is
+ // used to check for remaining available thinking time.
+ if (TimeMgr.available_time())
+ Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 8, 20)));
+ else
+ Threads.set_timer(100);
- // Print final search statistics
- cout << "info nodes " << pos.nodes_searched()
- << " nps " << nps(pos)
- << " time " << current_search_time() << endl;
+ // We're ready to start searching. Call the iterative deepening loop function
+ id_loop(pos);
- if (UseLogFile)
- {
- LogFile << "\nNodes: " << pos.nodes_searched()
- << "\nNodes/second: " << nps(pos)
- << "\nBest move: " << move_to_san(pos, bestMove);
+ // Stop timer and send all the slaves to sleep, if not already sleeping
+ Threads.set_timer(0);
+ Threads.set_size(1);
- StateInfo st;
- pos.do_move(bestMove, st);
- LogFile << "\nPonder move: "
- << move_to_san(pos, ponderMove) // Works also with MOVE_NONE
- << endl;
+ if (Options["Use Search Log"].value<bool>())
+ {
+ int e = elapsed_time();
- // Return from think() with unchanged position
- pos.undo_move(bestMove);
+ Log log(Options["Search Log Filename"].value<string>());
+ log << "Nodes: " << pos.nodes_searched()
+ << "\nNodes/second: " << (e > 0 ? pos.nodes_searched() * 1000 / e : 0)
+ << "\nBest move: " << move_to_san(pos, RootMoves[0].pv[0]);
- LogFile.close();
+ StateInfo st;
+ pos.do_move(RootMoves[0].pv[0], st);
+ log << "\nPonder move: " << move_to_san(pos, RootMoves[0].pv[1]) << endl;
+ pos.undo_move(RootMoves[0].pv[0]);
}
- // This makes all the threads to go to sleep
- ThreadsMgr.set_active_threads(1);
-
- // If we are pondering or in infinite search, we shouldn't print the
- // best move before we are told to do so.
- if (!StopRequest && (Pondering || InfiniteSearch))
- wait_for_stop_or_ponderhit();
+finish:
- // Could be both MOVE_NONE when searching on a stalemate position
- cout << "bestmove " << bestMove << " ponder " << ponderMove << endl;
+ // When we reach max depth we arrive here even without a StopRequest, but if
+ // we are pondering or in infinite search, we shouldn't print the best move
+ // before we are told to do so.
+ if (!Signals.stop && (Limits.ponder || Limits.infinite))
+ Threads.wait_for_stop_or_ponderhit();
- return !QuitRequest;
+ // Best move could be MOVE_NONE when searching on a stalemate position
+ cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], Chess960)
+ << " ponder " << move_to_uci(RootMoves[0].pv[1], Chess960) << endl;
}
// with increasing depth until the allocated thinking time has been consumed,
// user stops the search, or the maximum search depth is reached.
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) {
-
- SearchStack ss[PLY_MAX_PLUS_2];
- Value bestValues[PLY_MAX_PLUS_2];
- int bestMoveChanges[PLY_MAX_PLUS_2];
- int iteration, researchCountFL, researchCountFH, aspirationDelta;
- Value value, alpha, beta;
- Depth depth;
- Move bestMove, easyMove;
-
- // Moves to search are verified, scored and sorted
- Rml.init(pos, searchMoves);
-
- // Initialize FIXME move before Rml.init()
- TT.new_search();
- H.clear();
- memset(ss, 0, PLY_MAX_PLUS_2 * sizeof(SearchStack));
- alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- *ponderMove = bestMove = easyMove = MOVE_NONE;
- aspirationDelta = 0;
- iteration = 1;
- ss->currentMove = MOVE_NULL; // Hack to skip update_gains()
-
- // Handle special case of searching on a mate/stale position
- if (Rml.size() == 0)
- {
- cout << "info depth " << iteration << " score "
- << value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW)
- << endl;
-
- return MOVE_NONE;
- }
+ void id_loop(Position& pos) {
- // Send initial scoring (iteration 1)
- cout << set960(pos.is_chess960()) // Is enough to set once at the beginning
- << "info depth " << iteration
- << "\n" << Rml[0].pv_info_to_uci(pos, ONE_PLY, alpha, beta) << endl;
+ Stack ss[PLY_MAX_PLUS_2];
+ int depth, prevBestMoveChanges;
+ Value bestValue, alpha, beta, delta;
+ bool bestMoveNeverChanged = true;
+ Move skillBest = MOVE_NONE;
- // Is one move significantly better than others after initial scoring ?
- if ( Rml.size() == 1
- || Rml[0].pv_score > Rml[1].pv_score + EasyMoveMargin)
- easyMove = Rml[0].pv[0];
+ memset(ss, 0, 4 * sizeof(Stack));
+ depth = BestMoveChanges = 0;
+ bestValue = delta = -VALUE_INFINITE;
+ ss->currentMove = MOVE_NULL; // Hack to skip update gains
- // Iterative deepening loop
- while (++iteration <= PLY_MAX && (!MaxDepth || iteration <= MaxDepth) && !StopRequest)
+ // Handle the special case of a mate/stalemate position
+ if (RootMoves.empty())
{
- cout << "info depth " << iteration << endl;
-
- Rml.bestMoveChanges = researchCountFL = researchCountFH = 0;
- depth = (iteration - 1) * ONE_PLY;
+ cout << "info depth 0"
+ << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
- // Calculate dynamic aspiration window based on previous iterations
- if (MultiPV == 1 && iteration >= 6 && abs(bestValues[iteration - 1]) < VALUE_KNOWN_WIN)
- {
- int prevDelta1 = bestValues[iteration - 1] - bestValues[iteration - 2];
- int prevDelta2 = bestValues[iteration - 2] - bestValues[iteration - 3];
+ RootMoves.push_back(MOVE_NONE);
+ return;
+ }
- aspirationDelta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16);
- aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize
+ // Iterative deepening loop until requested to stop or target depth reached
+ while (!Signals.stop && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
+ {
+ // Save last iteration's scores before first PV line is searched and all
+ // the move scores but the (new) PV are set to -VALUE_INFINITE.
+ for (size_t i = 0; i < RootMoves.size(); i++)
+ RootMoves[i].prevScore = RootMoves[i].score;
- alpha = Max(bestValues[iteration - 1] - aspirationDelta, -VALUE_INFINITE);
- beta = Min(bestValues[iteration - 1] + aspirationDelta, VALUE_INFINITE);
- }
+ prevBestMoveChanges = BestMoveChanges;
+ BestMoveChanges = 0;
- // Start with a small aspiration window and, in case of fail high/low,
- // research with bigger window until not failing high/low anymore.
- while (true)
+ // MultiPV loop. We perform a full root search for each PV line
+ for (PVIdx = 0; PVIdx < std::min(MultiPV, RootMoves.size()); PVIdx++)
{
- // Search starting from ss+1 to allow calling update_gains()
- value = search<PV, false, true>(pos, ss+1, alpha, beta, depth, 0);
-
- // Write PV lines to transposition table, in case the relevant entries
- // have been overwritten during the search.
- for (int i = 0; i < Min(MultiPV, (int)Rml.size()); i++)
- Rml[i].insert_pv_in_tt(pos);
-
- // Value cannot be trusted. Break out immediately!
- if (StopRequest)
- break;
-
- assert(value >= alpha);
-
- // In case of failing high/low increase aspiration window and research,
- // otherwise exit the fail high/low loop.
- if (value >= beta)
+ // Set aspiration window default width
+ if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN)
{
- beta = Min(beta + aspirationDelta * (1 << researchCountFH), VALUE_INFINITE);
- researchCountFH++;
+ delta = Value(16);
+ alpha = RootMoves[PVIdx].prevScore - delta;
+ beta = RootMoves[PVIdx].prevScore + delta;
}
- else if (value <= alpha)
+ else
{
- AspirationFailLow = true;
- StopOnPonderhit = false;
-
- alpha = Max(alpha - aspirationDelta * (1 << researchCountFL), -VALUE_INFINITE);
- researchCountFL++;
+ alpha = -VALUE_INFINITE;
+ beta = VALUE_INFINITE;
}
- else
- break;
+
+ // Start with a small aspiration window and, in case of fail high/low,
+ // research with bigger window until not failing high/low anymore.
+ do {
+ // Search starts from ss+1 to allow referencing (ss-1). This is
+ // needed by update gains and ss copy when splitting at Root.
+ bestValue = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+
+ // Bring to front the best move. It is critical that sorting is
+ // done with a stable algorithm because all the values but the first
+ // and eventually the new best one are set to -VALUE_INFINITE and
+ // we want to keep the same order for all the moves but the new
+ // PV that goes to the front. Note that in case of MultiPV search
+ // the already searched PV lines are preserved.
+ sort<RootMove>(RootMoves.begin() + PVIdx, RootMoves.end());
+
+ // In case we have found an exact score and we are going to leave
+ // the fail high/low loop then reorder the PV moves, otherwise
+ // leave the last PV move in its position so to be searched again.
+ // Of course this is needed only in MultiPV search.
+ if (PVIdx && bestValue > alpha && bestValue < beta)
+ sort<RootMove>(RootMoves.begin(), RootMoves.begin() + PVIdx);
+
+ // Write PV back to transposition table in case the relevant
+ // entries have been overwritten during the search.
+ for (size_t i = 0; i <= PVIdx; i++)
+ RootMoves[i].insert_pv_in_tt(pos);
+
+ // If search has been stopped exit the aspiration window loop.
+ // Sorting and writing PV back to TT is safe becuase RootMoves
+ // is still valid, although refers to previous iteration.
+ if (Signals.stop)
+ break;
+
+ // 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 ((bestValue > alpha && bestValue < beta) || elapsed_time() > 2000)
+ pv_info_to_uci(pos, depth, alpha, beta);
+
+ // In case of failing high/low increase aspiration window and
+ // research, otherwise exit the fail high/low loop.
+ if (bestValue >= beta)
+ {
+ beta += delta;
+ delta += delta / 2;
+ }
+ else if (bestValue <= alpha)
+ {
+ Signals.failedLowAtRoot = true;
+ Signals.stopOnPonderhit = false;
+
+ alpha -= delta;
+ delta += delta / 2;
+ }
+ else
+ break;
+
+ assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
+
+ } while (abs(bestValue) < VALUE_KNOWN_WIN);
}
- // Collect info about search result
- bestMove = Rml[0].pv[0];
- bestValues[iteration] = value;
- bestMoveChanges[iteration] = Rml.bestMoveChanges;
+ // Skills: Do we need to pick now the best move ?
+ if (SkillLevelEnabled && depth == 1 + SkillLevel)
+ skillBest = do_skill_level();
+
+ if (Options["Use Search Log"].value<bool>())
+ pv_info_to_log(pos, depth, bestValue, elapsed_time(), &RootMoves[0].pv[0]);
- // Drop the easy move if differs from the new best move
- if (bestMove != easyMove)
- easyMove = MOVE_NONE;
+ // Filter out startup noise when monitoring best move stability
+ if (depth > 2 && BestMoveChanges)
+ bestMoveNeverChanged = false;
- if (UseTimeManagement && !StopRequest)
+ // Do we have time for the next iteration? Can we stop searching now?
+ if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement())
{
- // Time to stop?
- bool noMoreTime = false;
-
- // Stop search early when the last two iterations returned a mate score
- if ( iteration >= 6
- && abs(bestValues[iteration]) >= abs(VALUE_MATE) - 100
- && abs(bestValues[iteration-1]) >= abs(VALUE_MATE) - 100)
- noMoreTime = true;
-
- // Stop search early if one move seems to be much better than the
- // others or if there is only a single legal move. In this latter
- // case we search up to Iteration 8 anyway to get a proper score.
- if ( iteration >= 8
- && easyMove == bestMove
- && ( Rml.size() == 1
- ||( Rml[0].nodes > (pos.nodes_searched() * 85) / 100
- && current_search_time() > TimeMgr.available_time() / 16)
- ||( Rml[0].nodes > (pos.nodes_searched() * 98) / 100
- && current_search_time() > TimeMgr.available_time() / 32)))
- noMoreTime = true;
-
- // Add some extra time if the best move has changed during the last two iterations
- if (iteration > 5 && iteration <= 50)
- TimeMgr.pv_instability(bestMoveChanges[iteration], bestMoveChanges[iteration-1]);
-
- // 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.
- if (current_search_time() > (TimeMgr.available_time() * 80) / 128)
- noMoreTime = true;
-
- if (noMoreTime)
+ bool stop = false; // Local variable, not the volatile Signals.stop
+
+ // Take in account some extra time if the best move has changed
+ if (depth > 4 && depth < 50)
+ TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges);
+
+ // Stop search if most of available time is already consumed. We
+ // probably don't have enough time to search the first move at the
+ // next iteration anyway.
+ if (elapsed_time() > (TimeMgr.available_time() * 62) / 100)
+ stop = true;
+
+ // Stop search early if one move seems to be much better than others
+ if ( depth >= 10
+ && !stop
+ && ( bestMoveNeverChanged
+ || elapsed_time() > (TimeMgr.available_time() * 40) / 100))
+ {
+ Value rBeta = bestValue - EasyMoveMargin;
+ (ss+1)->excludedMove = RootMoves[0].pv[0];
+ (ss+1)->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth * ONE_PLY) / 2);
+ (ss+1)->skipNullMove = false;
+ (ss+1)->excludedMove = MOVE_NONE;
+
+ if (v < rBeta)
+ stop = true;
+ }
+
+ if (stop)
{
- if (Pondering)
- StopOnPonderhit = true;
+ // If we are allowed to ponder do not stop the search now but
+ // keep pondering until GUI sends "ponderhit" or "stop".
+ if (Limits.ponder)
+ Signals.stopOnPonderhit = true;
else
- break;
+ Signals.stop = true;
}
}
}
- *ponderMove = Rml[0].pv[1];
- return bestMove;
+ // When using skills swap best PV line with the sub-optimal one
+ if (SkillLevelEnabled)
+ {
+ if (skillBest == MOVE_NONE) // Still unassigned ?
+ skillBest = do_skill_level();
+
+ std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), skillBest));
+ }
}
// 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>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) {
+ template <NodeType NT>
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
+
+ const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
+ const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
+ const bool RootNode = (NT == Root || NT == SplitPointRoot);
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
- assert((Root || ply > 0) && ply < PLY_MAX);
- assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads());
+ assert(pos.thread() >= 0 && pos.thread() < Threads.size());
- Move movesSearched[MOVES_MAX];
+ Move movesSearched[MAX_MOVES];
int64_t nodes;
StateInfo st;
const TTEntry *tte;
Depth ext, newDepth;
ValueType vt;
Value bestValue, value, oldAlpha;
- Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
- bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous;
- bool mateThreat = false;
+ Value refinedValue, nullValue, futilityBase, futilityValue;
+ bool isPvMove, inCheck, singularExtensionNode, givesCheck;
+ bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount = 0, playedMoveCount = 0;
- int threadID = pos.thread();
+ Thread& thread = Threads[pos.thread()];
SplitPoint* sp = NULL;
refinedValue = bestValue = value = -VALUE_INFINITE;
oldAlpha = alpha;
- isCheck = pos.is_check();
+ inCheck = pos.in_check();
+ ss->ply = (ss-1)->ply + 1;
- if (SpNode)
+ // Used to send selDepth info to GUI
+ if (PvNode && thread.maxPly < ss->ply)
+ thread.maxPly = ss->ply;
+
+ // Step 1. Initialize node
+ if (!SpNode)
+ {
+ 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] = MOVE_NONE;
+ }
+ else
{
sp = ss->sp;
tte = NULL;
ttMove = excludedMove = MOVE_NONE;
threatMove = sp->threatMove;
- mateThreat = sp->mateThreat;
goto split_point_start;
}
- else if (Root)
- bestValue = alpha;
-
- // Step 1. Initialize node and poll. Polling can abort search
- ss->currentMove = ss->bestMove = threatMove = MOVE_NONE;
- (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE;
-
- if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
- {
- NodesSincePoll = 0;
- poll(pos);
- }
// Step 2. Check for aborted search and immediate draw
- if (( StopRequest
- || ThreadsMgr.cutoff_at_splitpoint(threadID)
- || pos.is_draw()
- || ply >= PLY_MAX - 1) && !Root)
+ if (( Signals.stop
+ || pos.is_draw<false>()
+ || ss->ply > PLY_MAX) && !RootNode)
return VALUE_DRAW;
// Step 3. Mate distance pruning
- alpha = Max(value_mated_in(ply), alpha);
- beta = Min(value_mate_in(ply+1), beta);
- if (alpha >= beta)
- return alpha;
+ if (!RootNode)
+ {
+ alpha = std::max(value_mated_in(ss->ply), alpha);
+ beta = std::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
- // TT value, so we use a different position key in case of an excluded move exists.
+ // TT value, so we use a different position key in case of an excluded move.
excludedMove = ss->excludedMove;
- posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
-
- tte = TT.retrieve(posKey);
- ttMove = tte ? tte->move() : MOVE_NONE;
-
- // At PV nodes we check for exact scores within (alha, beta) range, while
- // at non-PV nodes we check for and return a fail high/low. Biggest advantage
- // at probing at PV nodes is to have a smooth experience in analysis mode.
- if (!Root && tte && (PvNode ? ok_to_use_TT_PV(tte, depth, alpha, beta, ply) : ok_to_use_TT(tte, depth, beta, ply)))
+ posKey = excludedMove ? pos.exclusion_key() : pos.key();
+ tte = TT.probe(posKey);
+ ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
+
+ // 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. We don't probe at Root nodes otherwise
+ // we should also update RootMoveList to avoid bogus output.
+ if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
+ : can_return_tt(tte, depth, beta, ss->ply)))
{
TT.refresh(tte);
- ss->bestMove = ttMove; // Can be MOVE_NONE
- return value_from_tt(tte->value(), ply);
+ ss->bestMove = move = ttMove; // Can be MOVE_NONE
+ value = value_from_tt(tte->value(), ss->ply);
+
+ if ( value >= beta
+ && move
+ && !pos.is_capture_or_promotion(move)
+ && move != ss->killers[0])
+ {
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = move;
+ }
+ return value;
}
- // Step 5. Evaluate the position statically and
- // update gain statistics of parent move.
- if (isCheck)
+ // Step 5. Evaluate the position statically and update parent's gain statistics
+ if (inCheck)
ss->eval = ss->evalMargin = VALUE_NONE;
else if (tte)
{
ss->eval = tte->static_value();
ss->evalMargin = tte->static_value_margin();
- refinedValue = refine_eval(tte, ss->eval, ply);
+ refinedValue = refine_eval(tte, ss->eval, ss->ply);
}
else
{
TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin);
}
- // Save gain for the parent non-capture move
- update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
+ // Update gain for the parent non-capture move given the static position
+ // evaluation before and after the move.
+ if ( (move = (ss-1)->currentMove) != MOVE_NULL
+ && (ss-1)->eval != VALUE_NONE
+ && ss->eval != VALUE_NONE
+ && pos.captured_piece_type() == PIECE_TYPE_NONE
+ && !is_special(move))
+ {
+ Square to = move_to(move);
+ H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval);
+ }
// Step 6. Razoring (is omitted in PV nodes)
if ( !PvNode
&& depth < RazorDepth
- && !isCheck
- && refinedValue < beta - razor_margin(depth)
+ && !inCheck
+ && refinedValue + razor_margin(depth) < beta
&& ttMove == MOVE_NONE
- && !value_is_mate(beta)
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value rbeta = beta - razor_margin(depth);
- Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, DEPTH_ZERO, ply);
+ Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, DEPTH_ZERO);
if (v < rbeta)
// Logically we should return (v + razor_margin(depth)), but
// surprisingly this did slightly weaker in tests.
if ( !PvNode
&& !ss->skipNullMove
&& depth < RazorDepth
- && !isCheck
- && refinedValue >= beta + futility_margin(depth, 0)
- && !value_is_mate(beta)
+ && !inCheck
+ && refinedValue - futility_margin(depth, 0) >= beta
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX
&& pos.non_pawn_material(pos.side_to_move()))
return refinedValue - futility_margin(depth, 0);
if ( !PvNode
&& !ss->skipNullMove
&& depth > ONE_PLY
- && !isCheck
+ && !inCheck
&& refinedValue >= beta
- && !value_is_mate(beta)
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX
&& pos.non_pawn_material(pos.side_to_move()))
{
ss->currentMove = MOVE_NULL;
int R = 3 + (depth >= 5 * ONE_PLY ? depth / 8 : 0);
// Null move dynamic reduction based on value
- if (refinedValue - beta > PawnValueMidgame)
+ if (refinedValue - PawnValueMidgame > beta)
R++;
- pos.do_null_move(st);
+ pos.do_null_move<true>(st);
(ss+1)->skipNullMove = true;
- nullValue = -search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY, ply+1);
+ 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();
+ pos.do_null_move<false>(st);
if (nullValue >= beta)
{
// Do not return unproven mate scores
- if (nullValue >= value_mate_in(PLY_MAX))
+ if (nullValue >= VALUE_MATE_IN_PLY_MAX)
nullValue = beta;
if (depth < 6 * ONE_PLY)
// Do verification search at high depths
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, alpha, beta, depth-R*ONE_PLY, ply);
+ Value v = search<NonPV>(pos, ss, alpha, beta, depth-R*ONE_PLY);
ss->skipNullMove = false;
if (v >= beta)
// 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))
- mateThreat = true;
-
threatMove = (ss+1)->bestMove;
+
if ( depth < ThreatDepth
&& (ss-1)->reduction
&& threatMove != MOVE_NONE
}
}
- // 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, pos.captured_piece_type());
+ CheckInfo ci(pos);
+
+ while ((move = mp.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 || (!isCheck && ss->eval >= beta - IIDMargin)))
+ && (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, ply);
+ search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d);
ss->skipNullMove = false;
- ttMove = ss->bestMove;
- tte = TT.retrieve(posKey);
+ tte = TT.probe(posKey);
+ ttMove = tte ? tte->move() : MOVE_NONE;
}
- // Expensive mate threat detection (only for PV nodes)
- if (PvNode)
- mateThreat = pos.has_mate_threat();
-
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<SpNode> 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()
- && !excludedMove // Do not allow recursive singular extension search
+ && ttMove != MOVE_NONE
+ && !excludedMove // Recursive singular search is not allowed
&& (tte->type() & VALUE_TYPE_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
if (SpNode)
{
lock_grab(&(sp->lock));
bestValue = sp->bestValue;
+ moveCount = sp->moveCount;
+
+ assert(bestValue > -VALUE_INFINITE && moveCount > 0);
}
- // 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
- && !ThreadsMgr.cutoff_at_splitpoint(threadID))
+ && (move = mp.next_move()) != MOVE_NONE
+ && !thread.cutoff_occurred())
{
- assert(move_is_ok(move));
+ assert(is_ok(move));
+
+ if (move == excludedMove)
+ continue;
+
+ // At root obey the "searchmoves" option and skip moves not listed in Root
+ // Move List, as a consequence any illegal move is also skipped. In MultiPV
+ // mode we also skip PV moves which have been already searched.
+ if (RootNode && !count(RootMoves.begin() + PVIdx, RootMoves.end(), move))
+ continue;
+
+ // At PV and SpNode nodes we want all moves to be legal since the beginning
+ 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);
-
- // Save the current node count before the move is searched
+ Signals.firstRootMove = (moveCount == 1);
nodes = pos.nodes_searched();
- // If it's time to send nodes info, do it here where we have the
- // correct accumulated node counts searched by each thread.
- if (SendSearchedNodes)
- {
- SendSearchedNodes = false;
- cout << "info nodes " << nodes
- << " nps " << nps(pos)
- << " time " << current_search_time() << endl;
- }
-
- if (current_search_time() >= 1000)
- cout << "info currmove " << move
- << " currmovenumber " << moveCount << endl;
+ if (pos.thread() == 0 && elapsed_time() > 2000)
+ cout << "info depth " << depth / ONE_PLY
+ << " currmove " << move_to_uci(move, Chess960)
+ << " currmovenumber " << moveCount + PVIdx << endl;
}
- isPvMove = (PvNode && moveCount <= (Root ? MultiPV : 1));
- moveIsCheck = pos.move_is_check(move, ci);
- captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ isPvMove = (PvNode && moveCount <= 1);
+ captureOrPromotion = pos.is_capture_or_promotion(move);
+ givesCheck = pos.move_gives_check(move, ci);
+ dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion);
+ ext = DEPTH_ZERO;
- // Step 11. Decide the new search depth
- ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, mateThreat, &dangerous);
+ // Step 12. Extend checks and, in PV nodes, also dangerous moves
+ if (PvNode && dangerous)
+ ext = ONE_PLY;
- // Singular extension search. If all moves but one fail low on a search of (alpha-s, beta-s),
- // and just one fails high on (alpha, beta), then that move is singular and should be extended.
- // To verify this we do a reduced search on all the other moves but the ttMove, if result is
- // lower then ttValue minus a margin then we extend ttMove.
+ else if (givesCheck && pos.see_sign(move) >= 0)
+ ext = PvNode ? ONE_PLY : ONE_PLY / 2;
+
+ // Singular extension search. If all moves but one fail low on a search of
+ // (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
+ // is singular and should be extended. To verify this we do a reduced search
+ // on all the other moves but the ttMove, if result is lower than ttValue minus
+ // a margin then we extend ttMove.
if ( singularExtensionNode
- && move == tte->move()
- && ext < ONE_PLY)
+ && !ext
+ && move == ttMove
+ && pos.pl_move_is_legal(move, ci.pinned))
{
- Value ttValue = value_from_tt(tte->value(), ply);
+ Value ttValue = value_from_tt(tte->value(), ss->ply);
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value b = ttValue - SingularExtensionMargin;
+ Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2, ply);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
ss->bestMove = MOVE_NONE;
- if (v < b)
+ if (value < rBeta)
ext = ONE_PLY;
}
}
// Update current move (this must be done after singular extension search)
- ss->currentMove = move;
- newDepth = depth - (!Root ? ONE_PLY : DEPTH_ZERO) + ext;
+ 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
- && !isCheck
+ && !inCheck
&& !dangerous
&& move != ttMove
- && !move_is_castle(move))
+ && !is_castle(move)
+ && (bestValue > VALUE_MATED_IN_PLY_MAX || bestValue == -VALUE_INFINITE))
{
// Move count based pruning
if ( moveCount >= futility_move_count(depth)
- && !(threatMove && connected_threat(pos, move, threatMove))
- && bestValue > value_mated_in(PLY_MAX)) // FIXME bestValue is racy
+ && (!threatMove || !connected_threat(pos, move, threatMove)))
{
if (SpNode)
lock_grab(&(sp->lock));
// 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);
- futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount)
- + H.gain(pos.piece_on(move_from(move)), move_to(move));
+ Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
+ futilityValue = futilityBase + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move));
- if (futilityValueScaled < beta)
+ if (futilityValue < beta)
{
if (SpNode)
- {
lock_grab(&(sp->lock));
- if (futilityValueScaled > sp->bestValue)
- sp->bestValue = bestValue = futilityValueScaled;
- }
- else if (futilityValueScaled > bestValue)
- bestValue = futilityValueScaled;
continue;
}
// Prune moves with negative SEE at low depths
if ( predictedDepth < 2 * ONE_PLY
- && bestValue > value_mated_in(PLY_MAX)
&& pos.see_sign(move) < 0)
{
if (SpNode)
}
}
- // Step 13. Make the move
- pos.do_move(move, st, ci, moveIsCheck);
+ // Check for legality only before to do the move
+ if (!pos.pl_move_is_legal(move, ci.pinned))
+ {
+ moveCount--;
+ continue;
+ }
+ ss->currentMove = move;
if (!SpNode && !captureOrPromotion)
movesSearched[playedMoveCount++] = move;
- // Step extra. pv search (only in PV nodes)
- // The first move in list is the expected PV
- if (isPvMove)
+ // Step 14. Make the move
+ pos.do_move(move, st, ci, givesCheck);
+
+ // Step 15. Reduced depth search (LMR). If the move fails high will be
+ // re-searched at full depth.
+ if ( depth > 3 * ONE_PLY
+ && !isPvMove
+ && !captureOrPromotion
+ && !dangerous
+ && !is_castle(move)
+ && ss->killers[0] != move
+ && ss->killers[1] != move)
{
- // Aspiration window is disabled in multi-pv case
- if (Root && MultiPV > 1)
- alpha = -VALUE_INFINITE;
+ ss->reduction = reduction<PvNode>(depth, moveCount);
+ Depth d = newDepth - ss->reduction;
+ alpha = SpNode ? sp->alpha : alpha;
+
+ value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, ply+1);
+ doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
+ ss->reduction = DEPTH_ZERO;
}
else
- {
- // Step 14. Reduced depth search
- // If the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth >= 3 * ONE_PLY
- && !captureOrPromotion
- && !dangerous
- && !move_is_castle(move)
- && ss->killers[0] != move
- && ss->killers[1] != move)
- {
- ss->reduction = Root ? reduction<PvNode>(depth, moveCount - MultiPV + 1)
- : 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, ply+1);
-
- doFullDepthSearch = (value > alpha);
- }
- ss->reduction = DEPTH_ZERO; // Restore original reduction
- }
+ doFullDepthSearch = !isPvMove;
- // Step 15. Full depth search
- if (doFullDepthSearch)
- {
- alpha = SpNode ? sp->alpha : alpha;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, ply+1);
-
- // 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, ply+1);
- }
+ // Step 16. Full depth search, when LMR is skipped or fails high
+ if (doFullDepthSearch)
+ {
+ alpha = SpNode ? sp->alpha : alpha;
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
}
- // Step 16. Undo move
+ // Only for PV nodes do a full PV search on the first move or after a fail
+ // high, in the latter case search only if value < beta, otherwise let the
+ // parent node to fail low with value <= alpha and to try another move.
+ if (PvNode && (isPvMove || (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 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 (!Root && value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID)))
- {
- bestValue = value;
-
- if (SpNode)
- sp->bestValue = value;
-
- if (value > alpha)
- {
- if (PvNode && value < beta) // We want always alpha < beta
- {
- alpha = value;
-
- if (SpNode)
- sp->alpha = value;
- }
- else if (SpNode)
- sp->betaCutoff = true;
-
- if (value == value_mate_in(ply + 1))
- ss->mateKiller = move;
-
- ss->bestMove = move;
-
- if (SpNode)
- sp->parentSstack->bestMove = move;
- }
- }
-
- if (Root)
+ // Finished searching the move. If StopRequest is true, the search
+ // was aborted because the user interrupted the search or because we
+ // ran out of time. In this case, the return value of the search cannot
+ // be trusted, and we don't update the best move and/or PV.
+ if (RootNode && !Signals.stop)
{
- // To avoid to exit with bestValue == -VALUE_INFINITE
- if (value > bestValue)
- bestValue = value;
-
- // Finished searching the move. If StopRequest is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we break out of the loop without updating the best
- // move and/or PV.
- if (StopRequest)
- break;
+ RootMove& rm = *find(RootMoves.begin(), RootMoves.end(), move);
+ rm.nodes += pos.nodes_searched() - nodes;
- // Remember searched nodes counts for this move
- mp.rm->nodes += pos.nodes_searched() - nodes;
-
- // Step 17. Check for new best move
- if (!isPvMove && value <= alpha)
- mp.rm->pv_score = -VALUE_INFINITE;
- else
+ // PV move or new best move ?
+ if (isPvMove || value > alpha)
{
- // PV move or new best move!
-
- // Update PV
- ss->bestMove = move;
- mp.rm->pv_score = value;
- mp.rm->extract_pv_from_tt(pos);
+ rm.score = value;
+ rm.extract_pv_from_tt(pos);
// We record how often the best move has been changed in each
- // iteration. This information is used for time managment: When
+ // iteration. This information is used for time management: When
// the best move changes frequently, we allocate some more time.
if (!isPvMove && MultiPV == 1)
- Rml.bestMoveChanges++;
+ BestMoveChanges++;
+ }
+ else
+ // 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.
+ rm.score = -VALUE_INFINITE;
- // Inform GUI that PV has changed, in case of multi-pv UCI protocol
- // requires we send all the PV lines properly sorted.
- Rml.sort_multipv(moveCount);
+ }
- for (int j = 0; j < Min(MultiPV, (int)Rml.size()); j++)
- cout << Rml[j].pv_info_to_uci(pos, depth, alpha, beta, j) << endl;
+ if (value > bestValue)
+ {
+ bestValue = value;
+ ss->bestMove = move;
- // Update alpha. In multi-pv we don't use aspiration window, so
- // set alpha equal to minimum score among the PV lines.
- if (MultiPV > 1)
- alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score; // FIXME why moveCount?
- else if (value > alpha)
- alpha = value;
+ if ( PvNode
+ && value > alpha
+ && value < beta) // We want always alpha < beta
+ alpha = value;
- } // PV move or new best move
+ if (SpNode && !thread.cutoff_occurred())
+ {
+ sp->bestValue = value;
+ sp->ss->bestMove = move;
+ sp->alpha = alpha;
+ sp->is_betaCutoff = (value >= beta);
+ }
}
- // Step 18. Check for split
- if ( !Root
- && !SpNode
- && depth >= ThreadsMgr.min_split_depth()
- && ThreadsMgr.active_threads() > 1
+ // Step 19. Check for split
+ if ( !SpNode
+ && depth >= Threads.min_split_depth()
&& bestValue < beta
- && ThreadsMgr.available_thread_exists(threadID)
- && !StopRequest
- && !ThreadsMgr.cutoff_at_splitpoint(threadID))
- ThreadsMgr.split<FakeSplit>(pos, ss, ply, &alpha, beta, &bestValue, depth,
- threatMove, mateThreat, moveCount, &mp, PvNode);
+ && Threads.available_slave_exists(pos.thread())
+ && !Signals.stop
+ && !thread.cutoff_occurred())
+ bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, depth,
+ threatMove, moveCount, &mp, NT);
+ }
+
+ // 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. Note that we can have a false positive in
+ // case of StopRequest or thread.cutoff_occurred() are set, but this is
+ // harmless because return value is discarded anyhow in the parent nodes.
+ // If we are in a singular extension search then return a fail low score.
+ if (!moveCount)
+ return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
+
+ // If we have pruned all the moves without searching return a fail-low score
+ if (bestValue == -VALUE_INFINITE)
+ {
+ assert(!playedMoveCount);
+
+ bestValue = alpha;
}
- // Step 19. 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 : isCheck ? value_mated_in(ply) : VALUE_DRAW;
-
- // Step 20. Update tables
- // If the search is not aborted, update the transposition table,
- // history counters, and killer moves.
- if (!SpNode && !StopRequest && !ThreadsMgr.cutoff_at_splitpoint(threadID))
+ // Step 21. Update tables
+ // Update transposition table entry, killers and history
+ if (!SpNode && !Signals.stop && !thread.cutoff_occurred())
{
move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
: bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT;
- TT.store(posKey, value_to_tt(bestValue, ply), vt, depth, move, ss->eval, ss->evalMargin);
+ TT.store(posKey, value_to_tt(bestValue, ss->ply), vt, depth, move, ss->eval, ss->evalMargin);
- // Update killers and history only for non capture moves that fails high
+ // Update killers and history for non capture cut-off moves
if ( bestValue >= beta
- && !pos.move_is_capture_or_promotion(move))
+ && !pos.is_capture_or_promotion(move)
+ && !inCheck)
{
- update_history(pos, move, depth, movesSearched, playedMoveCount);
- update_killers(move, ss->killers);
+ if (move != ss->killers[0])
+ {
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = move;
+ }
+
+ // Increase history value of the cut-off move
+ Value bonus = Value(int(depth) * int(depth));
+ H.add(pos.piece_on(move_from(move)), move_to(move), bonus);
+
+ // Decrease history of all the other played non-capture moves
+ for (int i = 0; i < playedMoveCount - 1; i++)
+ {
+ Move m = movesSearched[i];
+ H.add(pos.piece_on(move_from(m)), move_to(m), -bonus);
+ }
}
}
if (SpNode)
{
// Here we have the lock still grabbed
- sp->slaves[threadID] = 0;
+ sp->is_slave[pos.thread()] = false;
sp->nodes += pos.nodes_searched();
lock_release(&(sp->lock));
}
return bestValue;
}
+
// qsearch() is the quiescence search function, which is called by the main
// search function when the remaining depth is zero (or, to be more precise,
// less than ONE_PLY).
- template <NodeType PvNode>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) {
+ template <NodeType NT>
+ Value qsearch(Position& pos, Stack* 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);
assert(depth <= 0);
- assert(ply > 0 && ply < PLY_MAX);
- assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads());
+ assert(pos.thread() >= 0 && pos.thread() < Threads.size());
StateInfo st;
Move ttMove, move;
Value bestValue, value, evalMargin, futilityValue, futilityBase;
- bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
+ bool inCheck, enoughMaterial, givesCheck, evasionPrunable;
const TTEntry* tte;
Depth ttDepth;
+ ValueType vt;
Value oldAlpha = alpha;
ss->bestMove = ss->currentMove = MOVE_NONE;
+ ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
- if (pos.is_draw() || ply >= PLY_MAX - 1)
+ 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
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
- isCheck = pos.is_check();
- ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
+ inCheck = pos.in_check();
+ ttDepth = (inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- tte = TT.retrieve(pos.get_key());
+ tte = TT.probe(pos.key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ply))
+ if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply))
{
ss->bestMove = ttMove; // Can be MOVE_NONE
- return value_from_tt(tte->value(), ply);
+ return value_from_tt(tte->value(), ss->ply);
}
// Evaluate the position statically
- if (isCheck)
+ if (inCheck)
{
bestValue = futilityBase = -VALUE_INFINITE;
ss->eval = evalMargin = VALUE_NONE;
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)
{
if (!tte)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
return bestValue;
}
if (PvNode && bestValue > alpha)
alpha = bestValue;
- // Futility pruning parameters, not needed when in check
futilityBase = ss->eval + evalMargin + FutilityMarginQS;
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
}
// 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
- while ( alpha < beta
- && (move = mp.get_next_move()) != MOVE_NONE)
+ while ( bestValue < beta
+ && (move = mp.next_move()) != MOVE_NONE)
{
- assert(move_is_ok(move));
+ assert(is_ok(move));
- moveIsCheck = pos.move_is_check(move, ci);
+ givesCheck = pos.move_gives_check(move, ci);
// Futility pruning
if ( !PvNode
- && !isCheck
- && !moveIsCheck
+ && !inCheck
+ && !givesCheck
&& move != ttMove
&& enoughMaterial
- && !move_is_promotion(move)
- && !pos.move_is_passed_pawn_push(move))
+ && !is_promotion(move)
+ && !pos.is_passed_pawn_push(move))
{
futilityValue = futilityBase
- + pos.endgame_value_of_piece_on(move_to(move))
- + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO);
+ + PieceValueEndgame[pos.piece_on(move_to(move))]
+ + (is_enpassant(move) ? PawnValueEndgame : VALUE_ZERO);
- if (futilityValue < alpha)
+ if (futilityValue < beta)
{
if (futilityValue > bestValue)
bestValue = futilityValue;
+
continue;
}
+
+ // Prune moves with negative or equal SEE
+ if ( futilityBase < beta
+ && depth < DEPTH_ZERO
+ && pos.see(move) <= 0)
+ continue;
}
// Detect non-capture evasions that are candidate to be pruned
- evasionPrunable = isCheck
- && bestValue > value_mated_in(PLY_MAX)
- && !pos.move_is_capture(move)
+ evasionPrunable = !PvNode
+ && inCheck
+ && bestValue > VALUE_MATED_IN_PLY_MAX
+ && !pos.is_capture(move)
&& !pos.can_castle(pos.side_to_move());
// Don't search moves with negative SEE values
if ( !PvNode
- && (!isCheck || evasionPrunable)
+ && (!inCheck || evasionPrunable)
&& move != ttMove
- && !move_is_promotion(move)
+ && !is_promotion(move)
&& pos.see_sign(move) < 0)
continue;
// Don't search useless checks
if ( !PvNode
- && !isCheck
- && moveIsCheck
+ && !inCheck
+ && givesCheck
&& move != ttMove
- && !pos.move_is_capture_or_promotion(move)
+ && !pos.is_capture_or_promotion(move)
&& ss->eval + PawnValueMidgame / 4 < beta
&& !check_is_dangerous(pos, move, futilityBase, beta, &bestValue))
{
continue;
}
- // Update current move
+ // Check for legality only before to do the move
+ if (!pos.pl_move_is_legal(move, ci.pinned))
+ continue;
+
ss->currentMove = move;
// Make and search the move
- pos.do_move(move, st, ci, moveIsCheck);
- value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-ONE_PLY, ply+1);
+ pos.do_move(move, st, ci, givesCheck);
+ value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth-ONE_PLY);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
if (value > bestValue)
{
bestValue = value;
- if (value > alpha)
- {
+ ss->bestMove = move;
+
+ if ( PvNode
+ && value > alpha
+ && value < beta) // We want always alpha < beta
alpha = value;
- ss->bestMove = move;
- }
}
}
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
- if (isCheck && bestValue == -VALUE_INFINITE)
- return value_mated_in(ply);
+ if (inCheck && bestValue == -VALUE_INFINITE)
+ return value_mated_in(ss->ply);
// Update transposition table
- ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin);
+ move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
+ vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
+ : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT;
+
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, move, ss->eval, evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
}
- // qsearch_scoring() scores each move of a list using a qsearch() evaluation,
- // it is used in RootMoveList to get an initial scoring.
- void qsearch_scoring(Position& pos, MoveStack* mlist, MoveStack* last) {
-
- SearchStack ss[PLY_MAX_PLUS_2];
- StateInfo st;
-
- memset(ss, 0, 4 * sizeof(SearchStack));
- ss[0].eval = ss[0].evalMargin = VALUE_NONE;
-
- for (MoveStack* cur = mlist; cur != last; cur++)
- {
- ss[0].currentMove = cur->move;
- pos.do_move(cur->move, st);
- cur->score = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1);
- pos.undo_move(cur->move);
- }
- }
-
-
- // check_is_dangerous() tests if a checking move can be pruned in qsearch().
- // bestValue is updated only when returning false because in that case move
- // will be pruned.
+ // check_is_dangerous() tests if a checking move can be pruned in qsearch().
+ // bestValue is updated only when returning false because in that case move
+ // will be pruned.
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bestValue)
{
from = move_from(move);
to = move_to(move);
- them = opposite_color(pos.side_to_move());
+ them = flip(pos.side_to_move());
ksq = pos.king_square(them);
kingAtt = pos.attacks_from<KING>(ksq);
pc = pos.piece_on(from);
newAtt = pos.attacks_from(pc, to, occ);
// Rule 1. Checks which give opponent's king at most one escape square are dangerous
- b = kingAtt & ~pos.pieces_of_color(them) & ~newAtt & ~(1ULL << to);
+ b = kingAtt & ~pos.pieces(them) & ~newAtt & ~(1ULL << to);
if (!(b && (b & (b - 1))))
return true;
// Rule 2. Queen contact check is very dangerous
- if ( type_of_piece(pc) == QUEEN
+ if ( type_of(pc) == QUEEN
&& bit_is_set(kingAtt, to))
return true;
// Rule 3. Creating new double threats with checks
- b = pos.pieces_of_color(them) & newAtt & ~oldAtt & ~(1ULL << ksq);
+ b = pos.pieces(them) & newAtt & ~oldAtt & ~(1ULL << ksq);
while (b)
{
victimSq = pop_1st_bit(&b);
- futilityValue = futilityBase + pos.endgame_value_of_piece_on(victimSq);
+ futilityValue = futilityBase + PieceValueEndgame[pos.piece_on(victimSq)];
// Note that here we generate illegal "double move"!
if ( futilityValue >= beta
bool connected_moves(const Position& pos, Move m1, Move m2) {
Square f1, t1, f2, t2;
- Piece p;
+ Piece p1, p2;
+ Square ksq;
- assert(m1 && move_is_ok(m1));
- assert(m2 && move_is_ok(m2));
+ assert(is_ok(m1));
+ assert(is_ok(m2));
// Case 1: The moving piece is the same in both moves
f2 = move_from(m2);
return true;
// Case 3: Moving through the vacated square
- if ( piece_is_slider(pos.piece_on(f2))
+ p2 = pos.piece_on(f2);
+ if ( piece_is_slider(p2)
&& bit_is_set(squares_between(f2, t2), f1))
return true;
// Case 4: The destination square for m2 is defended by the moving piece in m1
- p = pos.piece_on(t1);
- if (bit_is_set(pos.attacks_from(p, t1), t2))
+ p1 = pos.piece_on(t1);
+ if (bit_is_set(pos.attacks_from(p1, t1), t2))
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1
- if ( piece_is_slider(p)
- && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2)
- && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2))
+ ksq = pos.king_square(pos.side_to_move());
+ if ( piece_is_slider(p1)
+ && bit_is_set(squares_between(t1, ksq), f2))
{
- // discovered_check_candidates() works also if the Position's side to
- // move is the opposite of the checking piece.
- Color them = opposite_color(pos.side_to_move());
- Bitboard dcCandidates = pos.discovered_check_candidates(them);
-
- if (bit_is_set(dcCandidates, f2))
+ Bitboard occ = pos.occupied_squares();
+ clear_bit(&occ, f2);
+ if (bit_is_set(pos.attacks_from(p1, t1, occ), ksq))
return true;
}
return false;
}
- // 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);
- }
-
-
// value_to_tt() adjusts a mate score from "plies to mate from the root" to
- // "plies to mate from the current ply". Non-mate scores are unchanged.
- // The function is called before storing a value to the transposition table.
+ // "plies to mate from the current ply". Non-mate scores are unchanged. The
+ // function is called before storing a value to the transposition table.
Value value_to_tt(Value v, int ply) {
- if (v >= value_mate_in(PLY_MAX))
+ if (v >= VALUE_MATE_IN_PLY_MAX)
return v + ply;
- if (v <= value_mated_in(PLY_MAX))
+ if (v <= VALUE_MATED_IN_PLY_MAX)
return v - ply;
return v;
Value value_from_tt(Value v, int ply) {
- if (v >= value_mate_in(PLY_MAX))
+ if (v >= VALUE_MATE_IN_PLY_MAX)
return v - ply;
- if (v <= value_mated_in(PLY_MAX))
+ if (v <= VALUE_MATED_IN_PLY_MAX)
return v + ply;
return v;
}
- // 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 mateThreat, bool* dangerous) {
-
- assert(m != MOVE_NONE);
-
- Depth result = DEPTH_ZERO;
- *dangerous = moveIsCheck | mateThreat;
-
- if (*dangerous)
- {
- if (moveIsCheck && pos.see_sign(m) >= 0)
- result += CheckExtension[PvNode];
-
- if (mateThreat)
- result += MateThreatExtension[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_promotion(m)
- && !move_is_ep(m))
- {
- result += PawnEndgameExtension[PvNode];
- *dangerous = true;
- }
-
- if ( PvNode
- && captureOrPromotion
- && pos.type_of_piece_on(move_to(m)) != PAWN
- && pos.see_sign(m) >= 0)
- {
- result += ONE_PLY / 2;
- *dangerous = true;
- }
-
- return Min(result, ONE_PLY);
- }
-
-
// connected_threat() tests whether it is safe to forward prune a move or if
- // is somehow coonected to the threat move returned by null search.
+ // is somehow connected to the threat move returned by null search.
bool connected_threat(const Position& pos, Move m, Move threat) {
- assert(move_is_ok(m));
- assert(threat && move_is_ok(threat));
- assert(!pos.move_is_check(m));
- assert(!pos.move_is_capture_or_promotion(m));
- assert(!pos.move_is_passed_pawn_push(m));
+ assert(is_ok(m));
+ assert(is_ok(threat));
+ assert(!pos.is_capture_or_promotion(m));
+ assert(!pos.is_passed_pawn_push(m));
Square mfrom, mto, tfrom, tto;
return true;
// Case 2: 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 ( 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)
+ // value of the threatening piece, don't prune moves which defend it.
+ if ( pos.is_capture(threat)
+ && ( PieceValueMidgame[pos.piece_on(tfrom)] >= PieceValueMidgame[pos.piece_on(tto)]
+ || type_of(pos.piece_on(tfrom)) == KING)
&& pos.move_attacks_square(m, tto))
return true;
}
- // ok_to_use_TT() returns true if a transposition table score
- // can be used at a given point in search. There are two versions
- // one to be used in non-PV nodes and one in PV nodes where we look
- // for an exact score that falls between (alha, beta) boundaries.
+ // can_return_tt() returns true if a transposition table score can be used to
+ // cut-off at a given point in search.
- bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
+ bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply) {
Value v = value_from_tt(tte->value(), ply);
return ( tte->depth() >= depth
- || v >= Max(value_mate_in(PLY_MAX), beta)
- || v < Min(value_mated_in(PLY_MAX), beta))
+ || v >= std::max(VALUE_MATE_IN_PLY_MAX, beta)
+ || v < std::min(VALUE_MATED_IN_PLY_MAX, beta))
&& ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta)
|| ((tte->type() & VALUE_TYPE_UPPER) && v < beta));
}
- bool ok_to_use_TT_PV(const TTEntry* tte, Depth depth, Value alpha, Value beta, int ply) {
- Value v = value_from_tt(tte->value(), ply);
-
- return tte->depth() >= depth
- && tte->type() == VALUE_TYPE_EXACT
- && tte->move() != MOVE_NONE
- && v < beta
- && v > alpha;
- }
-
-
- // refine_eval() returns the transposition table score if
- // possible otherwise falls back on static position evaluation.
+ // refine_eval() returns the transposition table score if possible, otherwise
+ // falls back on static position evaluation.
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
}
- // update_history() registers a good move that produced a beta-cutoff
- // in history and marks as failures all the other moves of that ply.
-
- void update_history(const Position& pos, Move move, Depth depth,
- Move movesSearched[], int moveCount) {
- Move m;
- Value bonus = Value(int(depth) * int(depth));
-
- H.update(pos.piece_on(move_from(move)), move_to(move), bonus);
-
- for (int i = 0; i < moveCount - 1; i++)
- {
- m = movesSearched[i];
-
- assert(m != move);
-
- H.update(pos.piece_on(move_from(m)), move_to(m), -bonus);
- }
- }
-
-
- // update_killers() add a good move that produced a beta-cutoff
- // among the killer moves of that ply.
-
- void update_killers(Move m, Move killers[]) {
-
- if (m != killers[0])
- {
- killers[1] = killers[0];
- killers[0] = m;
- }
- }
+ // current_search_time() returns the number of milliseconds which have passed
+ // since the beginning of the current search.
+ int elapsed_time(bool reset) {
- // update_gains() updates the gains table of a non-capture move given
- // the static position evaluation before and after the move.
+ static int searchStartTime;
- void update_gains(const Position& pos, Move m, Value before, Value after) {
+ if (reset)
+ searchStartTime = system_time();
- if ( m != MOVE_NULL
- && before != VALUE_NONE
- && after != VALUE_NONE
- && pos.captured_piece_type() == PIECE_TYPE_NONE
- && !move_is_special(m))
- H.update_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after));
+ return system_time() - searchStartTime;
}
- // 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) {
+ 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) / 2 : -(VALUE_MATE + v) / 2 );
-
- return s.str();
- }
-
-
- // current_search_time() returns the number of milliseconds which have passed
- // since the beginning of the current search.
-
- int current_search_time() {
-
- return get_system_time() - SearchStartTime;
- }
+ s << " score mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
+ s << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
- // nps() computes the current nodes/second count
-
- int nps(const Position& pos) {
-
- int t = current_search_time();
- return (t > 0 ? int((pos.nodes_searched() * 1000) / t) : 0);
+ 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
- // search.
-
- void poll(const Position& pos) {
-
- static int lastInfoTime;
- int t = current_search_time();
-
- // Poll for input
- if (input_available())
- {
- // We are line oriented, don't read single chars
- std::string command;
-
- if (!std::getline(std::cin, command))
- command = "quit";
-
- if (command == "quit")
- {
- // Quit the program as soon as possible
- Pondering = false;
- QuitRequest = StopRequest = true;
- return;
- }
- else if (command == "stop")
- {
- // Stop calculating as soon as possible, but still send the "bestmove"
- // and possibly the "ponder" token when finishing the search.
- Pondering = false;
- StopRequest = true;
- }
- else if (command == "ponderhit")
- {
- // The opponent has played the expected move. GUI sends "ponderhit" if
- // we were told to ponder on the same move the opponent has played. We
- // should continue searching but switching from pondering to normal search.
- Pondering = false;
+ // pv_info_to_uci() sends search info to GUI. UCI protocol requires to send all
+ // the PV lines also if are still to be searched and so refer to the previous
+ // search score.
- if (StopOnPonderhit)
- StopRequest = true;
- }
- }
+ void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta) {
- // Print search information
- if (t < 1000)
- lastInfoTime = 0;
+ int t = elapsed_time();
+ int selDepth = 0;
- else if (lastInfoTime > t)
- // HACK: Must be a new search where we searched less than
- // NodesBetweenPolls nodes during the first second of search.
- lastInfoTime = 0;
+ for (int i = 0; i < Threads.size(); i++)
+ if (Threads[i].maxPly > selDepth)
+ selDepth = Threads[i].maxPly;
- else if (t - lastInfoTime >= 1000)
+ for (size_t i = 0; i < std::min(UCIMultiPV, RootMoves.size()); i++)
{
- lastInfoTime = t;
-
- if (dbg_show_mean)
- dbg_print_mean();
-
- if (dbg_show_hit_rate)
- dbg_print_hit_rate();
-
- // Send info on searched nodes as soon as we return to root
- SendSearchedNodes = true;
- }
-
- // Should we stop the search?
- if (Pondering)
- return;
-
- bool stillAtFirstMove = FirstRootMove
- && !AspirationFailLow
- && t > TimeMgr.available_time();
-
- bool noMoreTime = t > TimeMgr.maximum_time()
- || stillAtFirstMove;
-
- if ( (UseTimeManagement && noMoreTime)
- || (ExactMaxTime && t >= ExactMaxTime)
- || (MaxNodes && pos.nodes_searched() >= MaxNodes)) // FIXME
- StopRequest = true;
- }
-
-
- // 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
- // "bestmove" before the GUI sends it a "stop" or "ponderhit" command.
- // We simply wait here until one of these commands is sent, and return,
- // after which the bestmove and pondermove will be printed.
-
- void wait_for_stop_or_ponderhit() {
-
- std::string command;
+ bool updated = (i <= PVIdx);
- while (true)
- {
- // Wait for a command from stdin
- if (!std::getline(std::cin, command))
- command = "quit";
+ if (depth == 1 && !updated)
+ continue;
- if (command == "quit")
- {
- QuitRequest = true;
- break;
- }
- else if (command == "ponderhit" || command == "stop")
- break;
+ int d = (updated ? depth : depth - 1);
+ Value v = (updated ? RootMoves[i].score : RootMoves[i].prevScore);
+ std::stringstream s;
+
+ for (int j = 0; RootMoves[i].pv[j] != MOVE_NONE; j++)
+ s << " " << move_to_uci(RootMoves[i].pv[j], Chess960);
+
+ cout << "info depth " << d
+ << " seldepth " << selDepth
+ << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
+ << " nodes " << pos.nodes_searched()
+ << " nps " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0)
+ << " time " << t
+ << " multipv " << i + 1
+ << " pv" << s.str() << endl;
}
}
- // init_thread() is the function which is called when a new thread is
- // launched. It simply calls the idle_loop() function with the supplied
- // threadID. There are two versions of this function; one for POSIX
- // threads and one for Windows threads.
+ // pv_info_to_log() writes human-readable search information to the log file
+ // (which is created when the UCI parameter "Use Search Log" is "true"). It
+ // uses the two below helpers to pretty format time and score respectively.
-#if !defined(_MSC_VER)
+ string time_to_string(int millisecs) {
- void* init_thread(void* threadID) {
+ const int MSecMinute = 1000 * 60;
+ const int MSecHour = 1000 * 60 * 60;
- ThreadsMgr.idle_loop(*(int*)threadID, NULL);
- return NULL;
- }
+ int hours = millisecs / MSecHour;
+ int minutes = (millisecs % MSecHour) / MSecMinute;
+ int seconds = ((millisecs % MSecHour) % MSecMinute) / 1000;
-#else
+ std::stringstream s;
- DWORD WINAPI init_thread(LPVOID threadID) {
+ if (hours)
+ s << hours << ':';
- ThreadsMgr.idle_loop(*(int*)threadID, NULL);
- return 0;
+ s << std::setfill('0') << std::setw(2) << minutes << ':'
+ << std::setw(2) << seconds;
+ return s.str();
}
-#endif
-
-
- /// The ThreadsManager class
-
+ string score_to_string(Value v) {
- // read_uci_options() updates number of active threads and other internal
- // parameters according to the UCI options values. It is called before
- // to start a new search.
+ std::stringstream s;
- void ThreadsManager::read_uci_options() {
+ if (v >= VALUE_MATE_IN_PLY_MAX)
+ s << "#" << (VALUE_MATE - v + 1) / 2;
+ else if (v <= VALUE_MATED_IN_PLY_MAX)
+ s << "-#" << (VALUE_MATE + v) / 2;
+ else
+ s << std::setprecision(2) << std::fixed << std::showpos
+ << float(v) / PawnValueMidgame;
- maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value<int>();
- minimumSplitDepth = Options["Minimum Split Depth"].value<int>() * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"].value<bool>();
- activeThreads = Options["Threads"].value<int>();
+ return s.str();
}
+ void pv_info_to_log(Position& pos, int depth, Value value, int time, Move pv[]) {
- // idle_loop() is where the threads are parked when they have no work to do.
- // The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint
- // object for which the current thread is the master.
-
- void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) {
-
- assert(threadID >= 0 && threadID < MAX_THREADS);
+ const int64_t K = 1000;
+ const int64_t M = 1000000;
- int i;
- bool allFinished = false;
-
- while (true)
- {
- // Slave threads can exit as soon as AllThreadsShouldExit raises,
- // master should exit as last one.
- if (allThreadsShouldExit)
- {
- assert(!sp);
- threads[threadID].state = THREAD_TERMINATED;
- return;
- }
-
- // If we are not thinking, wait for a condition to be signaled
- // instead of wasting CPU time polling for work.
- while ( threadID >= activeThreads || threads[threadID].state == THREAD_INITIALIZING
- || (useSleepingThreads && threads[threadID].state == THREAD_AVAILABLE))
- {
- assert(!sp || useSleepingThreads);
- assert(threadID != 0 || useSleepingThreads);
-
- if (threads[threadID].state == THREAD_INITIALIZING)
- threads[threadID].state = THREAD_AVAILABLE;
-
- // Grab the lock to avoid races with wake_sleeping_thread()
- lock_grab(&sleepLock[threadID]);
-
- // If we are master and all slaves have finished do not go to sleep
- for (i = 0; sp && i < activeThreads && !sp->slaves[i]; i++) {}
- allFinished = (i == activeThreads);
-
- if (allFinished || allThreadsShouldExit)
- {
- lock_release(&sleepLock[threadID]);
- break;
- }
-
- // Do sleep here after retesting sleep conditions
- if (threadID >= activeThreads || threads[threadID].state == THREAD_AVAILABLE)
- cond_wait(&sleepCond[threadID], &sleepLock[threadID]);
-
- lock_release(&sleepLock[threadID]);
- }
-
- // If this thread has been assigned work, launch a search
- if (threads[threadID].state == THREAD_WORKISWAITING)
- {
- assert(!allThreadsShouldExit);
-
- threads[threadID].state = THREAD_SEARCHING;
-
- // Here we call search() with SplitPoint template parameter set to true
- SplitPoint* tsp = threads[threadID].splitPoint;
- Position pos(*tsp->pos, threadID);
- SearchStack* ss = tsp->sstack[threadID] + 1;
- ss->sp = tsp;
-
- if (tsp->pvNode)
- search<PV, true, false>(pos, ss, tsp->alpha, tsp->beta, tsp->depth, tsp->ply);
- else
- search<NonPV, true, false>(pos, ss, tsp->alpha, tsp->beta, tsp->depth, tsp->ply);
-
- assert(threads[threadID].state == THREAD_SEARCHING);
-
- threads[threadID].state = THREAD_AVAILABLE;
-
- // Wake up master thread so to allow it to return from the idle loop in
- // case we are the last slave of the split point.
- if (useSleepingThreads && threadID != tsp->master && threads[tsp->master].state == THREAD_AVAILABLE)
- wake_sleeping_thread(tsp->master);
- }
-
- // If this thread is the master of a split point and all slaves have
- // finished their work at this split point, return from the idle loop.
- for (i = 0; sp && i < activeThreads && !sp->slaves[i]; i++) {}
- allFinished = (i == activeThreads);
-
- if (allFinished)
- {
- // Because sp->slaves[] is reset under lock protection,
- // be sure sp->lock has been released before to return.
- lock_grab(&(sp->lock));
- lock_release(&(sp->lock));
-
- // In helpful master concept a master can help only a sub-tree, and
- // because here is all finished is not possible master is booked.
- assert(threads[threadID].state == THREAD_AVAILABLE);
-
- threads[threadID].state = THREAD_SEARCHING;
- return;
- }
- }
- }
+ StateInfo state[PLY_MAX_PLUS_2], *st = state;
+ Move* m = pv;
+ string san, padding;
+ size_t length;
+ std::stringstream s;
+ s << std::setw(2) << depth
+ << std::setw(8) << score_to_string(value)
+ << std::setw(8) << time_to_string(time);
- // init_threads() is called during startup. It launches all helper threads,
- // and initializes the split point stack and the global locks and condition
- // objects.
+ if (pos.nodes_searched() < M)
+ s << std::setw(8) << pos.nodes_searched() / 1 << " ";
- void ThreadsManager::init_threads() {
+ else if (pos.nodes_searched() < K * M)
+ s << std::setw(7) << pos.nodes_searched() / K << "K ";
- int i, arg[MAX_THREADS];
- bool ok;
+ else
+ s << std::setw(7) << pos.nodes_searched() / M << "M ";
- // Initialize global locks
- lock_init(&mpLock);
+ padding = string(s.str().length(), ' ');
+ length = padding.length();
- for (i = 0; i < MAX_THREADS; i++)
+ while (*m != MOVE_NONE)
{
- lock_init(&sleepLock[i]);
- cond_init(&sleepCond[i]);
- }
-
- // Initialize splitPoints[] locks
- for (i = 0; i < MAX_THREADS; i++)
- for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
- lock_init(&(threads[i].splitPoints[j].lock));
-
- // Will be set just before program exits to properly end the threads
- allThreadsShouldExit = false;
-
- // Threads will be put all threads to sleep as soon as created
- activeThreads = 1;
+ san = move_to_san(pos, *m);
- // All threads except the main thread should be initialized to THREAD_INITIALIZING
- threads[0].state = THREAD_SEARCHING;
- for (i = 1; i < MAX_THREADS; i++)
- threads[i].state = THREAD_INITIALIZING;
-
- // Launch the helper threads
- for (i = 1; i < MAX_THREADS; i++)
- {
- arg[i] = i;
-
-#if !defined(_MSC_VER)
- pthread_t pthread[1];
- ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0);
- pthread_detach(pthread[0]);
-#else
- ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL);
-#endif
- if (!ok)
+ if (length + san.length() > 80)
{
- cout << "Failed to create thread number " << i << endl;
- exit(EXIT_FAILURE);
+ s << "\n" + padding;
+ length = padding.length();
}
- // Wait until the thread has finished launching and is gone to sleep
- while (threads[i].state == THREAD_INITIALIZING) {}
- }
- }
-
-
- // exit_threads() is called when the program exits. It makes all the
- // helper threads exit cleanly.
-
- void ThreadsManager::exit_threads() {
+ s << san << ' ';
+ length += san.length() + 1;
- allThreadsShouldExit = true; // Let the woken up threads to exit idle_loop()
-
- // Wake up all the threads and waits for termination
- for (int i = 1; i < MAX_THREADS; i++)
- {
- wake_sleeping_thread(i);
- while (threads[i].state != THREAD_TERMINATED) {}
+ pos.do_move(*m++, *st++);
}
- // Now we can safely destroy the locks
- for (int i = 0; i < MAX_THREADS; i++)
- for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
- lock_destroy(&(threads[i].splitPoints[j].lock));
-
- lock_destroy(&mpLock);
-
- // Now we can safely destroy the wait conditions
- for (int i = 0; i < MAX_THREADS; i++)
- {
- lock_destroy(&sleepLock[i]);
- cond_destroy(&sleepCond[i]);
- }
- }
-
-
- // cutoff_at_splitpoint() checks whether a beta cutoff has occurred in
- // the thread's currently active split point, or in some ancestor of
- // the current split point.
-
- bool ThreadsManager::cutoff_at_splitpoint(int threadID) const {
-
- assert(threadID >= 0 && threadID < activeThreads);
-
- SplitPoint* sp = threads[threadID].splitPoint;
-
- for ( ; sp && !sp->betaCutoff; sp = sp->parent) {}
- return sp != NULL;
- }
-
-
- // thread_is_available() checks whether the thread with threadID "slave" is
- // available to help the thread with threadID "master" at a split point. An
- // obvious requirement is that "slave" must be idle. With more than two
- // threads, this is not by itself sufficient: If "slave" is the master of
- // some active split point, it is only available as a slave to the other
- // threads which are busy searching the split point at the top of "slave"'s
- // split point stack (the "helpful master concept" in YBWC terminology).
-
- bool ThreadsManager::thread_is_available(int slave, int master) const {
-
- assert(slave >= 0 && slave < activeThreads);
- assert(master >= 0 && master < activeThreads);
- assert(activeThreads > 1);
-
- if (threads[slave].state != THREAD_AVAILABLE || slave == master)
- return false;
+ while (m != pv)
+ pos.undo_move(*--m);
- // Make a local copy to be sure doesn't change under our feet
- int localActiveSplitPoints = threads[slave].activeSplitPoints;
-
- // No active split points means that the thread is available as
- // a slave for any other thread.
- if (localActiveSplitPoints == 0 || activeThreads == 2)
- return true;
-
- // Apply the "helpful master" concept if possible. Use localActiveSplitPoints
- // that is known to be > 0, instead of threads[slave].activeSplitPoints that
- // could have been set to 0 by another thread leading to an out of bound access.
- if (threads[slave].splitPoints[localActiveSplitPoints - 1].slaves[master])
- return true;
-
- return false;
+ Log l(Options["Search Log Filename"].value<string>());
+ l << s.str() << endl;
}
- // available_thread_exists() tries to find an idle thread which is available as
- // a slave for the thread with threadID "master".
+ // When playing with strength handicap choose best move among the MultiPV set
+ // using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen.
- bool ThreadsManager::available_thread_exists(int master) const {
+ Move do_skill_level() {
- assert(master >= 0 && master < activeThreads);
- assert(activeThreads > 1);
+ assert(MultiPV > 1);
- for (int i = 0; i < activeThreads; i++)
- if (thread_is_available(i, master))
- return true;
+ static RKISS rk;
- return false;
- }
+ // PRNG sequence should be not deterministic
+ for (int i = abs(system_time() % 50); i > 0; i--)
+ rk.rand<unsigned>();
+ // RootMoves are already sorted by score in descending order
+ size_t size = std::min(MultiPV, RootMoves.size());
+ int variance = std::min(RootMoves[0].score - RootMoves[size - 1].score, PawnValueMidgame);
+ int weakness = 120 - 2 * SkillLevel;
+ int max_s = -VALUE_INFINITE;
+ Move best = MOVE_NONE;
- // split() does the actual work of distributing the work at a node between
- // several available threads. If it does not succeed in splitting the
- // node (because no idle threads are available, or because we have no unused
- // split point objects), the function immediately returns. If splitting is
- // possible, a SplitPoint object is initialized with all the data that must be
- // copied to the helper threads and we tell our helper threads that they have
- // been assigned work. This will cause them to instantly leave their idle loops and
- // call search().When all threads have returned from search() then split() returns.
-
- template <bool Fake>
- void ThreadsManager::split(Position& pos, SearchStack* ss, int ply, Value* alpha,
- const Value beta, Value* bestValue, Depth depth, Move threatMove,
- bool mateThreat, int moveCount, MovePicker* mp, bool pvNode) {
- assert(pos.is_ok());
- assert(ply > 0 && ply < PLY_MAX);
- assert(*bestValue >= -VALUE_INFINITE);
- assert(*bestValue <= *alpha);
- assert(*alpha < beta);
- assert(beta <= VALUE_INFINITE);
- assert(depth > DEPTH_ZERO);
- assert(pos.thread() >= 0 && pos.thread() < activeThreads);
- assert(activeThreads > 1);
-
- int i, master = pos.thread();
- Thread& masterThread = threads[master];
-
- lock_grab(&mpLock);
-
- // If no other thread is available to help us, or if we have too many
- // active split points, don't split.
- if ( !available_thread_exists(master)
- || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
+ // Choose best move. For each move score we add two terms both dependent on
+ // weakness, one deterministic and bigger for weaker moves, and one random,
+ // then we choose the move with the resulting highest score.
+ for (size_t i = 0; i < size; i++)
{
- lock_release(&mpLock);
- return;
- }
+ int s = RootMoves[i].score;
- // Pick the next available split point object from the split point stack
- SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++];
-
- // Initialize the split point object
- splitPoint.parent = masterThread.splitPoint;
- splitPoint.master = master;
- splitPoint.betaCutoff = false;
- splitPoint.ply = ply;
- splitPoint.depth = depth;
- splitPoint.threatMove = threatMove;
- splitPoint.mateThreat = mateThreat;
- splitPoint.alpha = *alpha;
- splitPoint.beta = beta;
- splitPoint.pvNode = pvNode;
- splitPoint.bestValue = *bestValue;
- splitPoint.mp = mp;
- splitPoint.moveCount = moveCount;
- splitPoint.pos = &pos;
- splitPoint.nodes = 0;
- splitPoint.parentSstack = ss;
- for (i = 0; i < activeThreads; i++)
- splitPoint.slaves[i] = 0;
-
- masterThread.splitPoint = &splitPoint;
-
- // If we are here it means we are not available
- assert(masterThread.state != THREAD_AVAILABLE);
-
- int workersCnt = 1; // At least the master is included
-
- // Allocate available threads setting state to THREAD_BOOKED
- for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
- if (thread_is_available(i, master))
- {
- threads[i].state = THREAD_BOOKED;
- threads[i].splitPoint = &splitPoint;
- splitPoint.slaves[i] = 1;
- workersCnt++;
- }
-
- assert(Fake || workersCnt > 1);
+ // Don't allow crazy blunders even at very low skills
+ if (i > 0 && RootMoves[i-1].score > s + EasyMoveMargin)
+ break;
- // We can release the lock because slave threads are already booked and master is not available
- lock_release(&mpLock);
+ // This is our magic formula
+ s += ( weakness * int(RootMoves[0].score - s)
+ + variance * (rk.rand<unsigned>() % weakness)) / 128;
- // Tell the threads that they have work to do. This will make them leave
- // their idle loop. But before copy search stack tail for each thread.
- for (i = 0; i < activeThreads; i++)
- if (i == master || splitPoint.slaves[i])
+ if (s > max_s)
{
- memcpy(splitPoint.sstack[i], ss - 1, 4 * sizeof(SearchStack));
-
- assert(i == master || threads[i].state == THREAD_BOOKED);
-
- threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop()
-
- if (useSleepingThreads && i != master)
- wake_sleeping_thread(i);
+ max_s = s;
+ best = RootMoves[i].pv[0];
}
-
- // Everything is set up. The master thread enters the idle loop, from
- // which it will instantly launch a search, because its state is
- // THREAD_WORKISWAITING. We send the split point as a second parameter to the
- // idle loop, which means that the main thread will return from the idle
- // loop when all threads have finished their work at this split point.
- idle_loop(master, &splitPoint);
-
- // We have returned from the idle loop, which means that all threads are
- // finished. Update alpha and bestValue, and return.
- lock_grab(&mpLock);
-
- *alpha = splitPoint.alpha;
- *bestValue = splitPoint.bestValue;
- masterThread.activeSplitPoints--;
- masterThread.splitPoint = splitPoint.parent;
- pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
-
- lock_release(&mpLock);
- }
-
-
- // wake_sleeping_thread() wakes up the thread with the given threadID
- // when it is time to start a new search.
-
- void ThreadsManager::wake_sleeping_thread(int threadID) {
-
- lock_grab(&sleepLock[threadID]);
- cond_signal(&sleepCond[threadID]);
- lock_release(&sleepLock[threadID]);
- }
-
-
- /// RootMove and RootMoveList method's definitions
-
- RootMove::RootMove() {
-
- nodes = 0;
- pv_score = non_pv_score = -VALUE_INFINITE;
- pv[0] = MOVE_NONE;
+ }
+ return best;
}
- RootMove& RootMove::operator=(const RootMove& rm) {
-
- const Move* src = rm.pv;
- Move* dst = pv;
-
- // Avoid a costly full rm.pv[] copy
- do *dst++ = *src; while (*src++ != MOVE_NONE);
-
- nodes = rm.nodes;
- pv_score = rm.pv_score;
- non_pv_score = rm.non_pv_score;
- return *this;
- }
// extract_pv_from_tt() builds a PV by adding moves from the transposition table.
// We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This
StateInfo state[PLY_MAX_PLUS_2], *st = state;
TTEntry* tte;
int ply = 1;
+ Move m = pv[0];
- assert(pv[0] != MOVE_NONE && move_is_legal(pos, pv[0]));
+ assert(m != MOVE_NONE && pos.is_pseudo_legal(m));
- pos.do_move(pv[0], *st++);
+ pv.clear();
+ pv.push_back(m);
+ pos.do_move(m, *st++);
- while ( (tte = TT.retrieve(pos.get_key())) != NULL
+ while ( (tte = TT.probe(pos.key())) != NULL
&& tte->move() != MOVE_NONE
- && move_is_legal(pos, tte->move())
+ && pos.is_pseudo_legal(tte->move())
+ && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces())
&& ply < PLY_MAX
- && (!pos.is_draw() || ply < 2))
+ && (!pos.is_draw<false>() || ply < 2))
{
- pv[ply] = tte->move();
- pos.do_move(pv[ply++], *st++);
+ pv.push_back(tte->move());
+ pos.do_move(tte->move(), *st++);
+ ply++;
}
- pv[ply] = MOVE_NONE;
+ pv.push_back(MOVE_NONE);
do pos.undo_move(pv[--ply]); while (ply);
}
+
// insert_pv_in_tt() is called at the end of a search iteration, and inserts
// the PV back into the TT. This makes sure the old PV moves are searched
// first, even if the old TT entries have been overwritten.
Value v, m = VALUE_NONE;
int ply = 0;
- assert(pv[0] != MOVE_NONE && move_is_legal(pos, pv[0]));
+ assert(pv[ply] != MOVE_NONE && pos.is_pseudo_legal(pv[ply]));
do {
- k = pos.get_key();
- tte = TT.retrieve(k);
+ k = pos.key();
+ tte = TT.probe(k);
- // Don't overwrite exsisting correct entries
+ // Don't overwrite existing correct entries
if (!tte || tte->move() != pv[ply])
{
- v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m));
+ v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m));
TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m);
}
pos.do_move(pv[ply], *st++);
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 and eventually writes the info
- // to a log file. It is called at each iteration or after a new pv is found.
+} // namespace
- std::string RootMove::pv_info_to_uci(Position& pos, Depth depth, Value alpha, Value beta, int pvLine) {
- std::stringstream s, l;
- Move* m = pv;
+/// Thread::idle_loop() is where the thread is parked when it has no work to do.
+/// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object
+/// for which the thread is the master.
- while (*m != MOVE_NONE)
- l << *m++ << " ";
-
- s << "info depth " << depth / ONE_PLY
- << " seldepth " << int(m - pv)
- << " multipv " << pvLine + 1
- << " score " << value_to_uci(pv_score)
- << (pv_score >= beta ? " lowerbound" : pv_score <= alpha ? " upperbound" : "")
- << " time " << current_search_time()
- << " nodes " << pos.nodes_searched()
- << " nps " << nps(pos)
- << " pv " << l.str();
-
- if (UseLogFile && pvLine == 0)
- {
- ValueType t = pv_score >= beta ? VALUE_TYPE_LOWER :
- pv_score <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT;
+void Thread::idle_loop(SplitPoint* sp) {
- LogFile << pretty_pv(pos, current_search_time(), depth / ONE_PLY, pv_score, t, pv) << endl;
- }
- return s.str();
- }
+ while (true)
+ {
+ // If we are not searching, wait for a condition to be signaled
+ // instead of wasting CPU time polling for work.
+ while ( do_sleep
+ || do_terminate
+ || (Threads.use_sleeping_threads() && !is_searching))
+ {
+ assert((!sp && threadID) || Threads.use_sleeping_threads());
+ if (do_terminate)
+ {
+ assert(!sp);
+ return;
+ }
- void RootMoveList::init(Position& pos, Move searchMoves[]) {
+ // Grab the lock to avoid races with Thread::wake_up()
+ lock_grab(&sleepLock);
- MoveStack mlist[MOVES_MAX];
- Move* sm;
+ // If we are master and all slaves have finished don't go to sleep
+ if (sp && Threads.split_point_finished(sp))
+ {
+ lock_release(&sleepLock);
+ break;
+ }
- clear();
- bestMoveChanges = 0;
+ // Do sleep after retesting sleep conditions under lock protection, in
+ // particular we need to avoid a deadlock in case a master thread has,
+ // in the meanwhile, allocated us and sent the wake_up() call before we
+ // had the chance to grab the lock.
+ if (do_sleep || !is_searching)
+ cond_wait(&sleepCond, &sleepLock);
- // Generate all legal moves and score them
- MoveStack* last = generate<MV_LEGAL>(pos, mlist);
- qsearch_scoring(pos, mlist, last);
+ lock_release(&sleepLock);
+ }
- // Add each move to the RootMoveList's vector
- for (MoveStack* cur = mlist; cur != last; cur++)
- {
- // If we have a searchMoves[] list then verify cur->move
- // is in the list before to add it.
- for (sm = searchMoves; *sm && *sm != cur->move; sm++) {}
+ // If this thread has been assigned work, launch a search
+ if (is_searching)
+ {
+ assert(!do_terminate);
+
+ // Copy split point position and search stack and call search()
+ Stack ss[PLY_MAX_PLUS_2];
+ SplitPoint* tsp = splitPoint;
+ Position pos(*tsp->pos, threadID);
+
+ memcpy(ss, tsp->ss - 1, 4 * sizeof(Stack));
+ (ss+1)->sp = tsp;
+
+ if (tsp->nodeType == Root)
+ search<SplitPointRoot>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ else if (tsp->nodeType == PV)
+ search<SplitPointPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ else if (tsp->nodeType == NonPV)
+ search<SplitPointNonPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ else
+ assert(false);
- if (searchMoves[0] && *sm != cur->move)
- continue;
+ assert(is_searching);
- RootMove rm;
- rm.pv[0] = cur->move;
- rm.pv[1] = MOVE_NONE;
- rm.pv_score = Value(cur->score);
- push_back(rm);
- }
- sort();
+ is_searching = false;
+
+ // Wake up master thread so to allow it to return from the idle loop in
+ // case we are the last slave of the split point.
+ if ( Threads.use_sleeping_threads()
+ && threadID != tsp->master
+ && !Threads[tsp->master].is_searching)
+ Threads[tsp->master].wake_up();
+ }
+
+ // If this thread is the master of a split point and all slaves have
+ // finished their work at this split point, return from the idle loop.
+ if (sp && Threads.split_point_finished(sp))
+ {
+ // Because sp->is_slave[] is reset under lock protection,
+ // be sure sp->lock has been released before to return.
+ lock_grab(&(sp->lock));
+ lock_release(&(sp->lock));
+ return;
+ }
}
+}
-} // namespace
+
+/// do_timer_event() is called by the timer thread when the timer triggers. It
+/// is used to print debug info and, more important, to detect when we are out of
+/// available time and so stop the search.
+
+void do_timer_event() {
+
+ static int lastInfoTime;
+ int e = elapsed_time();
+
+ if (system_time() - lastInfoTime >= 1000 || !lastInfoTime)
+ {
+ lastInfoTime = system_time();
+
+ dbg_print_mean();
+ dbg_print_hit_rate();
+ }
+
+ if (Limits.ponder)
+ return;
+
+ bool stillAtFirstMove = Signals.firstRootMove
+ && !Signals.failedLowAtRoot
+ && e > TimeMgr.available_time();
+
+ bool noMoreTime = e > TimeMgr.maximum_time()
+ || stillAtFirstMove;
+
+ if ( (Limits.useTimeManagement() && noMoreTime)
+ || (Limits.maxTime && e >= Limits.maxTime)
+ /* missing nodes limit */ ) // FIXME
+ Signals.stop = true;
+}
projects / stockfish / blobdiff