/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include "lock.h"
#include "san.h"
#include "search.h"
+#include "timeman.h"
#include "thread.h"
#include "tt.h"
#include "ucioption.h"
namespace {
/// Types
+ enum NodeType { NonPV, PV };
+ // Set to true to force running with one thread.
+ // Used for debugging SMP code.
+ const bool FakeSplit = false;
// 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
int active_threads() const { return ActiveThreads; }
void set_active_threads(int newActiveThreads) { ActiveThreads = newActiveThreads; }
void incrementNodeCounter(int threadID) { threads[threadID].nodes++; }
- void incrementBetaCounter(Color us, Depth d, int threadID) { threads[threadID].betaCutOffs[us] += unsigned(d); }
- void print_current_line(SearchStack ss[], int ply, int threadID);
void resetNodeCounters();
- void resetBetaCounters();
int64_t nodes_searched() const;
- void get_beta_counters(Color us, int64_t& our, int64_t& their) const;
bool available_thread_exists(int master) const;
bool thread_is_available(int slave, int master) const;
bool thread_should_stop(int threadID) const;
void wake_sleeping_threads();
void put_threads_to_sleep();
- void idle_loop(int threadID, SplitPoint* waitSp);
- bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
- const Value futilityValue, Depth depth, int* moves, MovePicker* mp, int master, bool pvNode);
+ void idle_loop(int threadID, SplitPoint* sp);
+
+ template <bool Fake>
+ void split(const 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:
friend void poll();
int ActiveThreads;
volatile bool AllThreadsShouldExit, AllThreadsShouldSleep;
Thread threads[MAX_THREADS];
- SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX];
- Lock MPLock, IOLock;
+ Lock MPLock, WaitLock;
#if !defined(_MSC_VER)
pthread_cond_t WaitCond;
- pthread_mutex_t WaitLock;
#else
HANDLE SitIdleEvent[MAX_THREADS];
#endif
struct RootMove {
- RootMove() { nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; }
+ RootMove() : mp_score(0), nodes(0) {}
// 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 a higher score, or if the moves
- // have equal score but m1 has the higher node count.
+ // have equal score but m1 has the higher beta cut-off count.
bool operator<(const RootMove& m) const {
- return score != m.score ? score < m.score : theirBeta <= m.theirBeta;
+ return score != m.score ? score < m.score : mp_score <= m.mp_score;
}
Move move;
Value score;
- int64_t nodes, cumulativeNodes, ourBeta, theirBeta;
+ int mp_score;
+ int64_t nodes;
Move pv[PLY_MAX_PLUS_2];
};
Value get_move_score(int moveNum) const { return moves[moveNum].score; }
void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; }
Move get_move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; }
- int64_t get_move_cumulative_nodes(int moveNum) const { return moves[moveNum].cumulativeNodes; }
+ int64_t get_move_nodes(int moveNum) const { return moves[moveNum].nodes; }
+ void score_moves(const Position& pos);
- void set_move_nodes(int moveNum, int64_t nodes);
- void set_beta_counters(int moveNum, int64_t our, int64_t their);
+ void add_move_nodes(int moveNum, int64_t nodes) { moves[moveNum].nodes += nodes; }
void set_move_pv(int moveNum, const Move pv[]);
void sort();
void sort_multipv(int n);
};
- /// Constants
+ // 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 {};
- // Search depth at iteration 1
- const Depth InitialDepth = OnePly;
+ std::ostream& operator<< (std::ostream& os, const set960& m) {
- // Use internal iterative deepening?
- const bool UseIIDAtPVNodes = true;
- const bool UseIIDAtNonPVNodes = true;
+ os.iword(0) = int(m);
+ return os;
+ }
- // Internal iterative deepening margin. At Non-PV moves, when
- // UseIIDAtNonPVNodes is true, we do an internal iterative deepening
- // search when the static evaluation is at most IIDMargin below beta.
- const Value IIDMargin = Value(0x100);
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
+ /// Adjustments
+
+ // Step 6. Razoring
+
+ // Maximum depth for razoring
+ const Depth RazorDepth = 4 * ONE_PLY;
+
+ // Dynamic razoring margin based on depth
+ inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); }
+
+ // Step 8. Null move search with verification search
// Null move margin. A null move search will not be done if the static
// evaluation of the position is more than NullMoveMargin below beta.
const Value NullMoveMargin = Value(0x200);
- // If the TT move is at least SingleReplyMargin better then the
- // remaining ones we will extend it.
- const Value SingleReplyMargin = Value(0x20);
+ // Maximum depth for use of dynamic threat detection when null move fails low
+ const Depth ThreatDepth = 5 * ONE_PLY;
- // Depth limit for razoring
- const Depth RazorDepth = 4 * OnePly;
+ // Step 9. Internal iterative deepening
- /// Lookup tables initialized at startup
+ // Minimum depth for use of internal iterative deepening
+ const Depth IIDDepth[2] = { 8 * ONE_PLY /* non-PV */, 5 * ONE_PLY /* PV */};
- // Reduction lookup tables and their getter functions
- int8_t PVReductionMatrix[64][64]; // [depth][moveNumber]
- int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber]
+ // 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
- inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
- inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+ // Extensions. Configurable UCI options
+ // Array index 0 is used at non-PV nodes, index 1 at PV nodes.
+ Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
+ Depth PassedPawnExtension[2], 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);
- // Futility lookup tables and their getter functions
+ // Step 12. Futility pruning
+
+ // Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
- int32_t FutilityMarginsMatrix[14][64]; // [depth][moveNumber]
+
+ // Futility lookup tables (initialized at startup) and their getter functions
+ int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber]
int FutilityMoveCountArray[32]; // [depth]
- inline Value futility_margin(Depth d, int mn) { return Value(d < 7*OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); }
- inline int futility_move_count(Depth d) { return d < 16*OnePly ? FutilityMoveCountArray[d] : 512; }
+ inline Value futility_margin(Depth d, int mn) { return Value(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; }
- /// Variables initialized by UCI options
+ // Step 14. Reduced search
- // Depth limit for use of dynamic threat detection
- Depth ThreatDepth;
+ // Reduction lookup tables (initialized at startup) and their getter functions
+ int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber]
- // Last seconds noise filtering (LSN)
- const bool UseLSNFiltering = true;
- const int LSNTime = 4000; // In milliseconds
- const Value LSNValue = value_from_centipawns(200);
- bool loseOnTime = false;
+ template <NodeType PV>
+ inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; }
- // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
- Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
- Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
+ // Common adjustments
+
+ // Search depth at iteration 1
+ const Depth InitialDepth = ONE_PLY;
- // Iteration counters
+ // Easy move margin. An easy move candidate must be at least this much
+ // better than the second best move.
+ const Value EasyMoveMargin = Value(0x200);
+
+
+ /// Global variables
+
+ // Iteration counter
int Iteration;
// Scores and number of times the best move changed for each iteration
int MultiPV;
// Time managment variables
- int RootMoveNumber;
- int SearchStartTime;
- int MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
+ int SearchStartTime, MaxNodes, MaxDepth, ExactMaxTime;
bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
- bool AbortSearch, Quit;
- bool AspirationFailLow;
-
- // Show current line?
- bool ShowCurrentLine;
+ bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
+ TimeManager TimeMgr;
// Log file
bool UseLogFile;
std::ofstream LogFile;
- // MP related variables
+ // Multi-threads related variables
Depth MinimumSplitDepth;
int MaxThreadsPerSplitPoint;
- ThreadsManager TM;
+ ThreadsManager ThreadsMgr;
- // Node counters, used only by thread[0] but try to keep in different
- // cache lines (64 bytes each) from the heavy SMP read accessed variables.
+ // 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.
int NodesSincePoll;
int NodesBetweenPolls = 30000;
// History table
History H;
- /// Functions
+ /// Local functions
Value id_loop(const Position& pos, Move searchMoves[]);
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta);
- Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
- Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
- Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
+ Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
+
+ template <NodeType PvNode>
+ 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>
void sp_search(SplitPoint* sp, int threadID);
- void sp_search_pv(SplitPoint* sp, int threadID);
- void init_node(SearchStack ss[], int ply, int threadID);
- void update_pv(SearchStack ss[], int ply);
- void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply);
+
+ template <NodeType PvNode>
+ Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous);
+
bool connected_moves(const Position& pos, Move m1, Move m2);
bool value_is_mate(Value value);
- bool move_is_killer(Move m, const SearchStack& ss);
- Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*);
- bool ok_to_do_nullmove(const Position& pos);
- bool ok_to_prune(const Position& pos, Move m, Move threat);
+ Value value_to_tt(Value v, int ply);
+ Value value_from_tt(Value v, int ply);
+ bool move_is_killer(Move m, SearchStack* ss);
bool ok_to_use_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, SearchStack& ss);
+ void update_killers(Move m, SearchStack* ss);
void update_gains(const Position& pos, Move move, Value before, Value after);
int current_search_time();
+ std::string value_to_uci(Value v);
int nps();
void poll();
void ponderhit();
void wait_for_stop_or_ponderhit();
- void init_ss_array(SearchStack ss[]);
+ void init_ss_array(SearchStack* ss, int size);
+ void print_pv_info(const Position& pos, Move pv[], Value alpha, Value beta, Value value);
+ void insert_pv_in_tt(const Position& pos, Move pv[]);
+ void extract_pv_from_tt(const Position& pos, Move bestMove, Move pv[]);
#if !defined(_MSC_VER)
void *init_thread(void *threadID);
/// init_threads(), exit_threads() and nodes_searched() are helpers to
/// give accessibility to some TM methods from outside of current file.
-void init_threads() { TM.init_threads(); }
-void exit_threads() { TM.exit_threads(); }
-int64_t nodes_searched() { return TM.nodes_searched(); }
+void init_threads() { ThreadsMgr.init_threads(); }
+void exit_threads() { ThreadsMgr.exit_threads(); }
+int64_t nodes_searched() { return ThreadsMgr.nodes_searched(); }
+
+
+/// init_search() is called during startup. It initializes various lookup tables
+
+void init_search() {
+
+ int d; // depth (ONE_PLY == 2)
+ int hd; // half depth (ONE_PLY == 1)
+ int mc; // moveCount
+
+ // Init reductions array
+ for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++)
+ {
+ double pvRed = 0.33 + log(double(hd)) * log(double(mc)) / 4.5;
+ 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);
+ }
+
+ // Init futility margins array
+ for (d = 1; d < 16; d++) for (mc = 0; mc < 64; mc++)
+ FutilityMarginsMatrix[d][mc] = 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] = 3 + (1 << (3 * d / 8));
+}
/// perft() is our utility to verify move generation is bug free. All the legal
int perft(Position& pos, Depth depth)
{
- Move move;
+ MoveStack mlist[256];
+ StateInfo st;
+ Move m;
int sum = 0;
- MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
+
+ // Generate all legal moves
+ MoveStack* last = generate_moves(pos, mlist);
// If we are at the last ply we don't need to do and undo
// the moves, just to count them.
- if (depth <= OnePly) // Replace with '<' to test also qsearch
- {
- while (mp.get_next_move()) sum++;
- return sum;
- }
+ if (depth <= ONE_PLY)
+ return int(last - mlist);
// Loop through all legal moves
CheckInfo ci(pos);
- while ((move = mp.get_next_move()) != MOVE_NONE)
+ for (MoveStack* cur = mlist; cur != last; cur++)
{
- StateInfo st;
- pos.do_move(move, st, ci, pos.move_is_check(move, ci));
- sum += perft(pos, depth - OnePly);
- pos.undo_move(move);
+ 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;
}
/// search-related global variables, and calls root_search(). It returns false
/// when a quit command is received during the search.
-bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
- int time[], int increment[], int movesToGo, int maxDepth,
- int maxNodes, int maxTime, Move searchMoves[]) {
+bool think(const Position& pos, bool infinite, bool ponder, int time[], int increment[],
+ int movesToGo, int maxDepth, int maxNodes, int maxTime, Move searchMoves[]) {
// Initialize global search variables
- StopOnPonderhit = AbortSearch = Quit = false;
- AspirationFailLow = false;
+ StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
NodesSincePoll = 0;
+ ThreadsMgr.resetNodeCounters();
SearchStartTime = get_system_time();
ExactMaxTime = maxTime;
MaxDepth = maxDepth;
// Look for a book move, only during games, not tests
if (UseTimeManagement && get_option_value_bool("OwnBook"))
{
- Move bookMove;
if (get_option_value_string("Book File") != OpeningBook.file_name())
OpeningBook.open(get_option_value_string("Book File"));
- bookMove = OpeningBook.get_move(pos);
+ Move bookMove = OpeningBook.get_move(pos, get_option_value_bool("Best Book Move"));
if (bookMove != MOVE_NONE)
{
if (PonderSearch)
}
}
- TM.resetNodeCounters();
-
- if (button_was_pressed("New Game"))
- loseOnTime = false; // Reset at the beginning of a new game
-
// Read UCI option values
TT.set_size(get_option_value_int("Hash"));
if (button_was_pressed("Clear Hash"))
TT.clear();
- bool PonderingEnabled = get_option_value_bool("Ponder");
- MultiPV = get_option_value_int("MultiPV");
-
- CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
- CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
-
+ CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
+ CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
SingleEvasionExtension[1] = Depth(get_option_value_int("Single Evasion Extension (PV nodes)"));
SingleEvasionExtension[0] = Depth(get_option_value_int("Single Evasion Extension (non-PV nodes)"));
-
PawnPushTo7thExtension[1] = Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)"));
PawnPushTo7thExtension[0] = Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)"));
+ PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
+ PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
+ PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
+ PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
+ MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
+ MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
+
+ MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * ONE_PLY;
+ MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
+ MultiPV = get_option_value_int("MultiPV");
+ UseLogFile = get_option_value_bool("Use Search Log");
- PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
- PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
-
- PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
- PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
-
- MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
- MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
-
- ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
-
- Chess960 = get_option_value_bool("UCI_Chess960");
- ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
- UseLogFile = get_option_value_bool("Use Search Log");
if (UseLogFile)
LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
- MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
- MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
-
read_weights(pos.side_to_move());
// Set the number of active threads
int newActiveThreads = get_option_value_int("Threads");
- if (newActiveThreads != TM.active_threads())
+ if (newActiveThreads != ThreadsMgr.active_threads())
{
- TM.set_active_threads(newActiveThreads);
- init_eval(TM.active_threads());
- // HACK: init_eval() destroys the static castleRightsMask[] array in the
- // Position class. The below line repairs the damage.
- Position p(pos.to_fen());
- assert(pos.is_ok());
+ ThreadsMgr.set_active_threads(newActiveThreads);
+ init_eval(ThreadsMgr.active_threads());
}
// Wake up sleeping threads
- TM.wake_sleeping_threads();
+ ThreadsMgr.wake_sleeping_threads();
// Set thinking time
- int myTime = time[side_to_move];
- int myIncrement = increment[side_to_move];
+ int myTime = time[pos.side_to_move()];
+ int myIncrement = increment[pos.side_to_move()];
if (UseTimeManagement)
- {
- if (!movesToGo) // Sudden death time control
- {
- if (myIncrement)
- {
- MaxSearchTime = myTime / 30 + myIncrement;
- AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
- }
- else // Blitz game without increment
- {
- MaxSearchTime = myTime / 30;
- AbsoluteMaxSearchTime = myTime / 8;
- }
- }
- else // (x moves) / (y minutes)
- {
- if (movesToGo == 1)
- {
- MaxSearchTime = myTime / 2;
- AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
- }
- else
- {
- MaxSearchTime = myTime / Min(movesToGo, 20);
- AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
- }
- }
+ TimeMgr.init(myTime, myIncrement, movesToGo, pos.startpos_ply_counter());
- if (PonderingEnabled)
- {
- MaxSearchTime += MaxSearchTime / 4;
- MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
- }
- }
-
- // Set best NodesBetweenPolls interval
+ // Set best NodesBetweenPolls interval to avoid lagging under
+ // heavy time pressure.
if (MaxNodes)
NodesBetweenPolls = Min(MaxNodes, 30000);
else if (myTime && myTime < 1000)
else
NodesBetweenPolls = 30000;
- // Write information to search log file
+ // Write search information to log file
if (UseLogFile)
LogFile << "Searching: " << pos.to_fen() << endl
<< "infinite: " << infinite
<< " increment: " << myIncrement
<< " moves to go: " << movesToGo << endl;
- // LSN filtering. Used only for developing purpose. Disabled by default.
- if ( UseLSNFiltering
- && loseOnTime)
- {
- // Step 2. If after last move we decided to lose on time, do it now!
- while (SearchStartTime + myTime + 1000 > get_system_time())
- /* wait here */;
- }
-
// We're ready to start thinking. Call the iterative deepening loop function
- Value v = id_loop(pos, searchMoves);
-
- if (UseLSNFiltering)
- {
- // Step 1. If this is sudden death game and our position is hopeless,
- // decide to lose on time.
- if ( !loseOnTime // If we already lost on time, go to step 3.
- && myTime < LSNTime
- && myIncrement == 0
- && movesToGo == 0
- && v < -LSNValue)
- {
- loseOnTime = true;
- }
- else if (loseOnTime)
- {
- // Step 3. Now after stepping over the time limit, reset flag for next match.
- loseOnTime = false;
- }
- }
+ id_loop(pos, searchMoves);
if (UseLogFile)
LogFile.close();
- TM.put_threads_to_sleep();
+ ThreadsMgr.put_threads_to_sleep();
return !Quit;
}
-/// init_search() is called during startup. It initializes various lookup tables
-
-void init_search() {
-
- // Init our reduction lookup tables
- for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
- for (int j = 1; j < 64; j++) // j == moveNumber
- {
- double pvRed = 0.5 + log(double(i)) * log(double(j)) / 6.0;
- double nonPVRed = 0.5 + log(double(i)) * log(double(j)) / 3.0;
- PVReductionMatrix[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0);
- NonPVReductionMatrix[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
- }
-
- // Init futility margins array
- for (int i = 0; i < 14; i++) // i == depth (OnePly = 2)
- for (int j = 0; j < 64; j++) // j == moveNumber
- {
- FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j; // FIXME: test using log instead of BSR
- }
-
- // Init futility move count array
- for (int i = 0; i < 32; i++) // i == depth (OnePly = 2)
- FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8));
-}
-
-
-// SearchStack::init() initializes a search stack. Used at the beginning of a
-// new search from the root.
-void SearchStack::init(int ply) {
-
- pv[ply] = pv[ply + 1] = MOVE_NONE;
- currentMove = threatMove = MOVE_NONE;
- reduction = Depth(0);
- eval = VALUE_NONE;
-}
-
-void SearchStack::initKillers() {
-
- mateKiller = MOVE_NONE;
- for (int i = 0; i < KILLER_MAX; i++)
- killers[i] = MOVE_NONE;
-}
-
namespace {
// id_loop() is the main iterative deepening loop. It calls root_search
Value id_loop(const Position& pos, Move searchMoves[]) {
- Position p(pos);
+ Position p(pos, pos.thread());
SearchStack ss[PLY_MAX_PLUS_2];
+ Move pv[PLY_MAX_PLUS_2];
+ Move EasyMove = MOVE_NONE;
+ Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- // searchMoves are verified, copied, scored and sorted
+ // Moves to search are verified, copied, scored and sorted
RootMoveList rml(p, searchMoves);
// Handle special case of searching on a mate/stale position
if (PonderSearch)
wait_for_stop_or_ponderhit();
- return pos.is_check()? -VALUE_MATE : VALUE_DRAW;
+ return pos.is_check() ? -VALUE_MATE : VALUE_DRAW;
}
- // Print RootMoveList c'tor startup scoring to the standard output,
- // so that we print information also for iteration 1.
- cout << "info depth " << 1 << "\ninfo depth " << 1
- << " score " << value_to_string(rml.get_move_score(0))
+ // Print RootMoveList startup scoring to the standard output,
+ // so to output information also for iteration 1.
+ cout << set960(p.is_chess960()) // Is enough to set once at the beginning
+ << "info depth " << 1
+ << "\ninfo depth " << 1
+ << " score " << value_to_uci(rml.get_move_score(0))
<< " time " << current_search_time()
- << " nodes " << TM.nodes_searched()
+ << " nodes " << ThreadsMgr.nodes_searched()
<< " nps " << nps()
<< " pv " << rml.get_move(0) << "\n";
// Initialize
TT.new_search();
H.clear();
- init_ss_array(ss);
+ init_ss_array(ss, PLY_MAX_PLUS_2);
+ pv[0] = pv[1] = MOVE_NONE;
ValueByIteration[1] = rml.get_move_score(0);
Iteration = 1;
// Is one move significantly better than others after initial scoring ?
- Move EasyMove = MOVE_NONE;
if ( rml.move_count() == 1
|| rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin)
EasyMove = rml.get_move(0);
while (Iteration < PLY_MAX)
{
// Initialize iteration
- rml.sort();
Iteration++;
BestMoveChangesByIteration[Iteration] = 0;
- if (Iteration <= 5)
- ExtraSearchTime = 0;
cout << "info depth " << Iteration << endl;
- // Calculate dynamic search window based on previous iterations
- Value alpha, beta;
-
+ // Calculate dynamic aspiration window based on previous iterations
if (MultiPV == 1 && Iteration >= 6 && abs(ValueByIteration[Iteration - 1]) < VALUE_KNOWN_WIN)
{
int prevDelta1 = ValueByIteration[Iteration - 1] - ValueByIteration[Iteration - 2];
alpha = Max(ValueByIteration[Iteration - 1] - AspirationDelta, -VALUE_INFINITE);
beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE);
}
- else
- {
- alpha = - VALUE_INFINITE;
- beta = VALUE_INFINITE;
- }
- // Search to the current depth
- Value value = root_search(p, ss, rml, alpha, beta);
+ // Search to the current depth, rml is updated and sorted, alpha and beta could change
+ value = root_search(p, ss, pv, rml, &alpha, &beta);
// Write PV to transposition table, in case the relevant entries have
// been overwritten during the search.
- TT.insert_pv(p, ss[0].pv);
+ insert_pv_in_tt(p, pv);
if (AbortSearch)
break; // Value cannot be trusted. Break out immediately!
//Save info about search result
ValueByIteration[Iteration] = value;
- // Drop the easy move if it differs from the new best move
- if (ss[0].pv[0] != EasyMove)
+ // Drop the easy move if differs from the new best move
+ if (pv[0] != EasyMove)
EasyMove = MOVE_NONE;
if (UseTimeManagement)
&& abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100)
stopSearch = true;
- // Stop search early if one move seems to be much better than the rest
- int64_t nodes = TM.nodes_searched();
+ // Stop search early if one move seems to be much better than the others
+ int64_t nodes = ThreadsMgr.nodes_searched();
if ( Iteration >= 8
- && EasyMove == ss[0].pv[0]
- && ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
- && current_search_time() > MaxSearchTime / 16)
- ||( rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100
- && current_search_time() > MaxSearchTime / 32)))
+ && EasyMove == pv[0]
+ && ( ( rml.get_move_nodes(0) > (nodes * 85) / 100
+ && current_search_time() > TimeMgr.available_time() / 16)
+ ||( rml.get_move_nodes(0) > (nodes * 98) / 100
+ && current_search_time() > TimeMgr.available_time() / 32)))
stopSearch = true;
// Add some extra time if the best move has changed during the last two iterations
if (Iteration > 5 && Iteration <= 50)
- ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2)
- + BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
+ TimeMgr.pv_unstability(BestMoveChangesByIteration[Iteration],
+ BestMoveChangesByIteration[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() > ((MaxSearchTime + ExtraSearchTime) * 80) / 128)
+ if (current_search_time() > (TimeMgr.available_time() * 80) / 128)
stopSearch = true;
if (stopSearch)
{
- if (!PonderSearch)
- break;
- else
+ if (PonderSearch)
StopOnPonderhit = true;
+ else
+ break;
}
}
break;
}
- rml.sort();
-
// If we are pondering or in infinite search, we shouldn't print the
// best move before we are told to do so.
if (!AbortSearch && (PonderSearch || InfiniteSearch))
wait_for_stop_or_ponderhit();
else
// Print final search statistics
- cout << "info nodes " << TM.nodes_searched()
+ cout << "info nodes " << ThreadsMgr.nodes_searched()
<< " nps " << nps()
- << " time " << current_search_time()
- << " hashfull " << TT.full() << endl;
+ << " time " << current_search_time() << endl;
// Print the best move and the ponder move to the standard output
- if (ss[0].pv[0] == MOVE_NONE)
+ if (pv[0] == MOVE_NONE)
{
- ss[0].pv[0] = rml.get_move(0);
- ss[0].pv[1] = MOVE_NONE;
+ pv[0] = rml.get_move(0);
+ pv[1] = MOVE_NONE;
}
- cout << "bestmove " << ss[0].pv[0];
- if (ss[0].pv[1] != MOVE_NONE)
- cout << " ponder " << ss[0].pv[1];
+
+ assert(pv[0] != MOVE_NONE);
+
+ cout << "bestmove " << pv[0];
+
+ if (pv[1] != MOVE_NONE)
+ cout << " ponder " << pv[1];
cout << endl;
if (dbg_show_hit_rate)
dbg_print_hit_rate(LogFile);
- LogFile << "\nNodes: " << TM.nodes_searched()
+ LogFile << "\nNodes: " << ThreadsMgr.nodes_searched()
<< "\nNodes/second: " << nps()
- << "\nBest move: " << move_to_san(p, ss[0].pv[0]);
+ << "\nBest move: " << move_to_san(p, pv[0]);
StateInfo st;
- p.do_move(ss[0].pv[0], st);
- LogFile << "\nPonder move: " << move_to_san(p, ss[0].pv[1]) << endl;
+ p.do_move(pv[0], st);
+ LogFile << "\nPonder move: "
+ << move_to_san(p, pv[1]) // Works also with MOVE_NONE
+ << endl;
}
return rml.get_move_score(0);
}
// root_search() is the function which searches the root node. It is
// similar to search_pv except that it uses a different move ordering
- // scheme and prints some information to the standard output.
+ // scheme, prints some information to the standard output and handles
+ // the fail low/high loops.
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta) {
+ Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
+ Value margins[2];
+ StateInfo st;
+ CheckInfo ci(pos);
int64_t nodes;
Move move;
- StateInfo st;
Depth depth, ext, newDepth;
- Value value;
- CheckInfo ci(pos);
- int researchCount = 0;
- bool moveIsCheck, captureOrPromotion, dangerous;
- Value alpha = oldAlpha;
- bool isCheck = pos.is_check();
+ Value value, alpha, beta;
+ bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
+ int researchCountFH, researchCountFL;
- // Evaluate the position statically
- EvalInfo ei;
- ss[0].eval = !isCheck ? evaluate(pos, ei, 0) : VALUE_NONE;
+ researchCountFH = researchCountFL = 0;
+ alpha = *alphaPtr;
+ beta = *betaPtr;
+ isCheck = pos.is_check();
+ depth = (Iteration - 2) * ONE_PLY + InitialDepth;
- while (1) // Fail low loop
+ // Step 1. Initialize node (polling is omitted at root)
+ ss->currentMove = ss->bestMove = MOVE_NONE;
+
+ // Step 2. Check for aborted search (omitted at root)
+ // Step 3. Mate distance pruning (omitted at root)
+ // Step 4. Transposition table lookup (omitted at root)
+
+ // Step 5. Evaluate the position statically
+ // At root we do this only to get reference value for child nodes
+ ss->eval = isCheck ? VALUE_NONE : evaluate(pos, margins);
+
+ // Step 6. Razoring (omitted at root)
+ // Step 7. Static null move pruning (omitted at root)
+ // Step 8. Null move search with verification search (omitted at root)
+ // Step 9. Internal iterative deepening (omitted at root)
+
+ // Step extra. Fail low loop
+ // We start with small aspiration window and in case of fail low, we research
+ // with bigger window until we are not failing low anymore.
+ while (1)
{
+ // Sort the moves before to (re)search
+ rml.score_moves(pos);
+ rml.sort();
- // Loop through all the moves in the root move list
+ // Step 10. Loop through all moves in the root move list
for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
{
- if (alpha >= beta)
- {
- // We failed high, invalidate and skip next moves, leave node-counters
- // and beta-counters as they are and quickly return, we will try to do
- // a research at the next iteration with a bigger aspiration window.
- rml.set_move_score(i, -VALUE_INFINITE);
- continue;
- }
-
- RootMoveNumber = i + 1;
+ // This is used by time management
+ FirstRootMove = (i == 0);
// Save the current node count before the move is searched
- nodes = TM.nodes_searched();
-
- // Reset beta cut-off counters
- TM.resetBetaCounters();
+ nodes = ThreadsMgr.nodes_searched();
// Pick the next root move, and print the move and the move number to
// the standard output.
- move = ss[0].currentMove = rml.get_move(i);
+ move = ss->currentMove = rml.get_move(i);
if (current_search_time() >= 1000)
cout << "info currmove " << move
- << " currmovenumber " << RootMoveNumber << endl;
+ << " currmovenumber " << i + 1 << endl;
- // Decide search depth for this move
moveIsCheck = pos.move_is_check(move);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- depth = (Iteration - 2) * OnePly + InitialDepth;
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+
+ // Step 11. Decide the new search depth
+ ext = extension<PV>(pos, move, captureOrPromotion, moveIsCheck, false, false, &dangerous);
newDepth = depth + ext;
+ // Step 12. Futility pruning (omitted at root)
+
+ // Step extra. Fail high loop
+ // If move fails high, we research with bigger window until we are not failing
+ // high anymore.
value = - VALUE_INFINITE;
- while (1) // Fail high loop
+ while (1)
{
-
- // Make the move, and search it
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
+ // Step extra. pv search
+ // We do pv search for first moves (i < MultiPV)
+ // and for fail high research (value > alpha)
if (i < MultiPV || value > alpha)
{
// Aspiration window is disabled in multi-pv case
if (MultiPV > 1)
alpha = -VALUE_INFINITE;
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+ // Full depth PV search, done on first move or after a fail high
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 1);
}
else
{
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
- // if the move fails high will be re-searched at full depth.
+ // Step 14. Reduced search
+ // if the move fails high will be re-searched at full depth
bool doFullDepthSearch = true;
- if ( depth >= 3*OnePly // FIXME was newDepth
+ if ( depth >= 3 * ONE_PLY
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move))
{
- ss[0].reduction = pv_reduction(depth, RootMoveNumber - MultiPV + 1);
- if (ss[0].reduction)
+ ss->reduction = reduction<PV>(depth, i - MultiPV + 2);
+ if (ss->reduction)
{
- value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0);
+ assert(newDepth-ss->reduction >= ONE_PLY);
+
+ // Reduced depth non-pv search using alpha as upperbound
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1);
doFullDepthSearch = (value > alpha);
}
+
+ // The move failed high, but if reduction is very big we could
+ // face a false positive, retry with a less aggressive reduction,
+ // if the move fails high again then go with full depth search.
+ if (doFullDepthSearch && ss->reduction > 2 * ONE_PLY)
+ {
+ assert(newDepth - ONE_PLY >= ONE_PLY);
+
+ ss->reduction = ONE_PLY;
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1);
+ doFullDepthSearch = (value > alpha);
+ }
+ ss->reduction = DEPTH_ZERO; // Restore original reduction
}
+ // Step 15. Full depth search
if (doFullDepthSearch)
{
- ss[0].reduction = Depth(0);
- value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+ // Full depth non-pv search using alpha as upperbound
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, 1);
+ // If we are above alpha then research at same depth but as PV
+ // to get a correct score or eventually a fail high above beta.
if (value > alpha)
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 1);
}
}
+ // Step 16. Undo move
pos.undo_move(move);
// Can we exit fail high loop ?
if (AbortSearch || value < beta)
break;
- // We are failing high and going to do a research. It's important to update score
- // before research in case we run out of time while researching.
+ // We are failing high and going to do a research. It's important to update
+ // the score before research in case we run out of time while researching.
rml.set_move_score(i, value);
- update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv, PLY_MAX);
- rml.set_move_pv(i, ss[0].pv);
-
- // Print search information to the standard output
- cout << "info depth " << Iteration
- << " score " << value_to_string(value)
- << ((value >= beta) ? " lowerbound" :
- ((value <= alpha)? " upperbound" : ""))
- << " time " << current_search_time()
- << " nodes " << TM.nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
- cout << ss[0].pv[j] << " ";
-
- cout << endl;
-
- if (UseLogFile)
- {
- ValueType type = (value >= beta ? VALUE_TYPE_LOWER
- : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
+ ss->bestMove = move;
+ extract_pv_from_tt(pos, move, pv);
+ rml.set_move_pv(i, pv);
- LogFile << pretty_pv(pos, current_search_time(), Iteration,
- TM.nodes_searched(), value, type, ss[0].pv) << endl;
- }
+ // Print information to the standard output
+ print_pv_info(pos, pv, alpha, beta, value);
// Prepare for a research after a fail high, each time with a wider window
- researchCount++;
- beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE);
+ *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE);
+ researchCountFH++;
} // End of fail high loop
if (AbortSearch)
break;
- // Remember beta-cutoff and searched nodes counts for this move. The
- // info is used to sort the root moves at the next iteration.
- int64_t our, their;
- TM.get_beta_counters(pos.side_to_move(), our, their);
- rml.set_beta_counters(i, our, their);
- rml.set_move_nodes(i, TM.nodes_searched() - nodes);
+ // Remember searched nodes counts for this move
+ rml.add_move_nodes(i, ThreadsMgr.nodes_searched() - nodes);
assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+ assert(value < beta);
+ // Step 17. Check for new best move
if (value <= alpha && i >= MultiPV)
rml.set_move_score(i, -VALUE_INFINITE);
else
// Update PV
rml.set_move_score(i, value);
- update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv, PLY_MAX);
- rml.set_move_pv(i, ss[0].pv);
+ ss->bestMove = move;
+ extract_pv_from_tt(pos, move, pv);
+ rml.set_move_pv(i, pv);
if (MultiPV == 1)
{
if (i > 0)
BestMoveChangesByIteration[Iteration]++;
- // Print search information to the standard output
- cout << "info depth " << Iteration
- << " score " << value_to_string(value)
- << ((value >= beta) ? " lowerbound" :
- ((value <= alpha)? " upperbound" : ""))
- << " time " << current_search_time()
- << " nodes " << TM.nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
- cout << ss[0].pv[j] << " ";
-
- cout << endl;
+ // Print information to the standard output
+ print_pv_info(pos, pv, alpha, beta, value);
- if (UseLogFile)
- {
- ValueType type = (value >= beta ? VALUE_TYPE_LOWER
- : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
-
- LogFile << pretty_pv(pos, current_search_time(), Iteration,
- TM.nodes_searched(), value, type, ss[0].pv) << endl;
- }
+ // Raise alpha to setup proper non-pv search upper bound
if (value > alpha)
alpha = value;
}
for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
{
cout << "info multipv " << j + 1
- << " score " << value_to_string(rml.get_move_score(j))
- << " depth " << ((j <= i)? Iteration : Iteration - 1)
+ << " score " << value_to_uci(rml.get_move_score(j))
+ << " depth " << (j <= i ? Iteration : Iteration - 1)
<< " time " << current_search_time()
- << " nodes " << TM.nodes_searched()
+ << " nodes " << ThreadsMgr.nodes_searched()
<< " nps " << nps()
<< " pv ";
cout << endl;
}
- alpha = rml.get_move_score(Min(i, MultiPV-1));
+ alpha = rml.get_move_score(Min(i, MultiPV - 1));
}
} // PV move or new best move
- assert(alpha >= oldAlpha);
+ assert(alpha >= *alphaPtr);
- AspirationFailLow = (alpha == oldAlpha);
+ AspirationFailLow = (alpha == *alphaPtr);
if (AspirationFailLow && StopOnPonderhit)
StopOnPonderhit = false;
}
// Can we exit fail low loop ?
- if (AbortSearch || alpha > oldAlpha)
+ if (AbortSearch || !AspirationFailLow)
break;
// Prepare for a research after a fail low, each time with a wider window
- researchCount++;
- alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE);
- oldAlpha = alpha;
+ *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE);
+ researchCountFL++;
} // Fail low loop
+ // Sort the moves before to return
+ rml.sort();
+
return alpha;
}
- // search_pv() is the main search function for PV nodes.
+ // search<>() is the main search function for both PV and non-PV nodes
- Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta,
- Depth depth, int ply, int threadID) {
+ template <NodeType PvNode>
+ Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) {
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(PvNode || alpha == beta - 1);
+ assert(ply > 0 && ply < PLY_MAX);
+ assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads());
Move movesSearched[256];
+ Value margins[2];
StateInfo st;
- const TTEntry* tte;
- Move ttMove, move;
+ const TTEntry *tte;
+ Key posKey;
+ Move ttMove, move, excludedMove, threatMove;
Depth ext, newDepth;
- Value oldAlpha, value;
- bool isCheck, mateThreat, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
+ Value bestValue, value, oldAlpha;
+ Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
+ bool isCheck, singleEvasion, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous;
+ bool mateThreat = false;
int moveCount = 0;
- Value bestValue = value = -VALUE_INFINITE;
+ int threadID = pos.thread();
+ refinedValue = bestValue = value = -VALUE_INFINITE;
+ oldAlpha = alpha;
- if (depth < OnePly)
- return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
+ // Step 1. Initialize node and poll. Polling can abort search
+ ThreadsMgr.incrementNodeCounter(threadID);
+ ss->currentMove = ss->bestMove = threatMove = MOVE_NONE;
+ (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE;
- // Step 1. Initialize node and poll
- // Polling can abort search.
- init_node(ss, ply, threadID);
+ if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
+ {
+ NodesSincePoll = 0;
+ poll();
+ }
// Step 2. Check for aborted search and immediate draw
- if (AbortSearch || TM.thread_should_stop(threadID))
- return Value(0);
+ if (AbortSearch || ThreadsMgr.thread_should_stop(threadID))
+ return VALUE_ZERO;
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
// Step 3. Mate distance pruning
- oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
beta = Min(value_mate_in(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.
+ 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 don't use the TT for pruning, but only for move ordering.
// This is to avoid problems in the following areas:
//
// * Fifty move rule detection
// * Searching for a mate
// * Printing of full PV line
- tte = TT.retrieve(pos.get_key());
- ttMove = (tte ? tte->move() : MOVE_NONE);
- // Step 5. Evaluate the position statically
- // At PV nodes we do this only to update gain statistics
- isCheck = pos.is_check();
- if (!isCheck)
+ if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
{
- EvalInfo ei;
- ss[ply].eval = evaluate(pos, ei, threadID);
- update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
- }
-
- // Step 6. Razoring (is omitted in PV nodes)
- // Step 7. Static null move pruning (is omitted in PV nodes)
- // Step 8. Null move search with verification search (is omitted in PV nodes)
+ // Refresh tte entry to avoid aging
+ TT.store(posKey, tte->value(), tte->type(), tte->depth(), ttMove, tte->static_value(), tte->static_value_margin());
- // Step 9. Internal iterative deepening
- if ( UseIIDAtPVNodes
- && depth >= 5*OnePly
- && ttMove == MOVE_NONE)
- {
- search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
- ttMove = ss[ply].pv[ply];
- tte = TT.retrieve(pos.get_key());
+ ss->bestMove = ttMove; // Can be MOVE_NONE
+ return value_from_tt(tte->value(), ply);
}
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
-
- // Initialize a MovePicker object for the current position
- mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
- MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
- CheckInfo ci(pos);
-
- while ( alpha < beta
- && (move = mp.get_next_move()) != MOVE_NONE
- && !TM.thread_should_stop(threadID))
+ // Step 5. Evaluate the position statically and
+ // update gain statistics of parent move.
+ isCheck = pos.is_check();
+ if (isCheck)
+ ss->eval = VALUE_NONE;
+ else if (tte)
{
- assert(move_is_ok(move));
-
- singleEvasion = (isCheck && mp.number_of_evasions() == 1);
- moveIsCheck = pos.move_is_check(move, ci);
- captureOrPromotion = pos.move_is_capture_or_promotion(move);
-
- // Step 11. Decide the new search depth
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
-
- // Singular extension search. We extend the TT move if its value is much better than
- // its siblings. 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.
- if ( depth >= 6 * OnePly
- && tte
- && move == tte->move()
- && ext < OnePly
- && is_lower_bound(tte->type())
- && tte->depth() >= depth - 3 * OnePly)
- {
- Value ttValue = value_from_tt(tte->value(), ply);
+ assert(tte->static_value() != VALUE_NONE);
- if (abs(ttValue) < VALUE_KNOWN_WIN)
- {
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
-
- if (excValue < ttValue - SingleReplyMargin)
- ext = OnePly;
- }
- }
-
- newDepth = depth - OnePly + ext;
-
- // Update current move (this must be done after singular extension search)
- movesSearched[moveCount++] = ss[ply].currentMove = move;
-
- // Step 12. Futility pruning (is omitted in PV nodes)
-
- // Step 13. Make the move
- pos.do_move(move, st, ci, moveIsCheck);
-
- // Step extra. pv search (only in PV nodes)
- // The first move in list is the expected PV
- if (moveCount == 1)
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
- else
- {
- // Step 14. Reduced search
- // if the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth >= 3*OnePly
- && !dangerous
- && !captureOrPromotion
- && !move_is_castle(move)
- && !move_is_killer(move, ss[ply]))
- {
- ss[ply].reduction = pv_reduction(depth, moveCount);
- if (ss[ply].reduction)
- {
- value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID);
- doFullDepthSearch = (value > alpha);
- }
- }
-
- // Step 15. Full depth search
- if (doFullDepthSearch)
- {
- ss[ply].reduction = Depth(0);
- value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
-
- // Step extra. pv search (only in PV nodes)
- if (value > alpha && value < beta)
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
- }
- }
-
- // Step 16. Undo move
- pos.undo_move(move);
-
- assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
-
- // Step 17. Check for new best move
- if (value > bestValue)
- {
- bestValue = value;
- if (value > alpha)
- {
- alpha = value;
- update_pv(ss, ply);
- if (value == value_mate_in(ply + 1))
- ss[ply].mateKiller = move;
- }
- }
-
- // Step 18. Check for split
- if ( TM.active_threads() > 1
- && bestValue < beta
- && depth >= MinimumSplitDepth
- && Iteration <= 99
- && TM.available_thread_exists(threadID)
- && !AbortSearch
- && !TM.thread_should_stop(threadID)
- && TM.split(pos, ss, ply, &alpha, beta, &bestValue, VALUE_NONE,
- depth, &moveCount, &mp, threadID, true))
- break;
- }
-
- // Step 19. Check for mate and stalemate
- // All legal moves have been searched and if there were
- // no legal moves, it must be mate or stalemate.
- if (moveCount == 0)
- return (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 (AbortSearch || TM.thread_should_stop(threadID))
- return bestValue;
-
- if (bestValue <= oldAlpha)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
-
- else if (bestValue >= beta)
- {
- TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
- move = ss[ply].pv[ply];
- if (!pos.move_is_capture_or_promotion(move))
- {
- update_history(pos, move, depth, movesSearched, moveCount);
- update_killers(move, ss[ply]);
- }
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
+ ss->eval = tte->static_value();
+ margins[pos.side_to_move()] = tte->static_value_margin();
+ refinedValue = refine_eval(tte, ss->eval, ply);
}
else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss[ply].pv[ply]);
-
- return bestValue;
- }
-
-
- // search() is the search function for zero-width nodes.
-
- Value search(Position& pos, SearchStack ss[], Value beta, Depth depth,
- int ply, bool allowNullmove, int threadID, Move excludedMove) {
-
- assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < TM.active_threads());
-
- Move movesSearched[256];
- EvalInfo ei;
- StateInfo st;
- const TTEntry* tte;
- Move ttMove, move;
- Depth ext, newDepth;
- Value bestValue, staticValue, nullValue, value, futilityValue, futilityValueScaled;
- bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
- bool mateThreat = false;
- int moveCount = 0;
- futilityValue = staticValue = bestValue = value = -VALUE_INFINITE;
-
- if (depth < OnePly)
- return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
-
- // Step 1. Initialize node and poll
- // Polling can abort search.
- init_node(ss, ply, threadID);
-
- // Step 2. Check for aborted search and immediate draw
- if (AbortSearch || TM.thread_should_stop(threadID))
- return Value(0);
-
- if (pos.is_draw() || ply >= PLY_MAX - 1)
- return VALUE_DRAW;
-
- // Step 3. Mate distance pruning
- if (value_mated_in(ply) >= beta)
- return beta;
-
- if (value_mate_in(ply + 1) < beta)
- return beta - 1;
-
- // 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 exsists.
- Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
-
- tte = TT.retrieve(posKey);
- ttMove = (tte ? tte->move() : MOVE_NONE);
-
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
- ss[ply].currentMove = ttMove; // Can be MOVE_NONE
- return value_from_tt(tte->value(), ply);
+ refinedValue = ss->eval = evaluate(pos, margins);
+ TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, margins[pos.side_to_move()]);
}
- // Step 5. Evaluate the position statically
- isCheck = pos.is_check();
-
- if (!isCheck)
- {
- if (tte && (tte->type() & VALUE_TYPE_EVAL))
- staticValue = value_from_tt(tte->value(), ply);
- else
- staticValue = evaluate(pos, ei, threadID);
+ // Save gain for the parent non-capture move
+ update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
- ss[ply].eval = staticValue;
- futilityValue = staticValue + futility_margin(depth, 0); //FIXME: Remove me, only for split
- staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible
- update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
- }
-
- // Step 6. Razoring
- if ( !value_is_mate(beta)
+ // Step 6. Razoring (is omitted in PV nodes)
+ if ( !PvNode
+ && depth < RazorDepth
&& !isCheck
- && depth < RazorDepth
- && staticValue < beta - (0x200 + 16 * depth)
- && ss[ply - 1].currentMove != MOVE_NULL
- && ttMove == MOVE_NONE
+ && refinedValue < beta - razor_margin(depth)
+ && ttMove == MOVE_NONE
+ && (ss-1)->currentMove != MOVE_NULL
+ && !value_is_mate(beta)
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
- Value rbeta = beta - (0x200 + 16 * depth);
- Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
+ Value rbeta = beta - razor_margin(depth);
+ Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, DEPTH_ZERO, ply);
if (v < rbeta)
- return v; //FIXME: Logically should be: return (v + 0x200 + 16 * depth);
+ // Logically we should return (v + razor_margin(depth)), but
+ // surprisingly this did slightly weaker in tests.
+ return v;
}
- // Step 7. Static null move pruning
+ // Step 7. Static null move pruning (is omitted in PV nodes)
// We're betting that the opponent doesn't have a move that will reduce
- // the score by more than fuility_margin(depth) if we do a null move.
- if ( !isCheck
- && allowNullmove
- && depth < RazorDepth
- && staticValue - futility_margin(depth, 0) >= beta)
- return staticValue - futility_margin(depth, 0);
-
- // Step 8. Null move search with verification search
+ // the score by more than futility_margin(depth) if we do a null move.
+ if ( !PvNode
+ && !ss->skipNullMove
+ && depth < RazorDepth
+ && !isCheck
+ && refinedValue >= beta + futility_margin(depth, 0)
+ && !value_is_mate(beta)
+ && pos.non_pawn_material(pos.side_to_move()))
+ return refinedValue - futility_margin(depth, 0);
+
+ // Step 8. Null move search with verification search (is omitted in PV nodes)
// When we jump directly to qsearch() we do a null move only if static value is
// at least beta. Otherwise we do a null move if static value is not more than
// NullMoveMargin under beta.
- if ( allowNullmove
- && depth > OnePly
+ if ( !PvNode
+ && !ss->skipNullMove
+ && depth > ONE_PLY
&& !isCheck
+ && refinedValue >= beta - (depth >= 4 * ONE_PLY ? NullMoveMargin : 0)
&& !value_is_mate(beta)
- && ok_to_do_nullmove(pos)
- && staticValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0))
+ && pos.non_pawn_material(pos.side_to_move()))
{
- ss[ply].currentMove = MOVE_NULL;
-
- pos.do_null_move(st);
+ ss->currentMove = MOVE_NULL;
// Null move dynamic reduction based on depth
- int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0);
+ int R = 3 + (depth >= 5 * ONE_PLY ? depth / 8 : 0);
// Null move dynamic reduction based on value
- if (staticValue - beta > PawnValueMidgame)
+ if (refinedValue - beta > PawnValueMidgame)
R++;
- nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
+ pos.do_null_move(st);
+ (ss+1)->skipNullMove = true;
+ nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO, ply+1)
+ : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY, ply+1);
+ (ss+1)->skipNullMove = false;
pos.undo_null_move();
if (nullValue >= beta)
{
- if (depth < 6 * OnePly)
- return beta;
+ // Do not return unproven mate scores
+ if (nullValue >= value_mate_in(PLY_MAX))
+ nullValue = beta;
+
+ if (depth < 6 * ONE_PLY)
+ return nullValue;
+
+ // Do verification search at high depths
+ ss->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss, alpha, beta, depth-R*ONE_PLY, ply);
+ ss->skipNullMove = false;
- // Do zugzwang verification search
- Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
if (v >= beta)
- return beta;
- } else {
+ return nullValue;
+ }
+ else
+ {
// The null move failed low, which means that we may be faced with
// some kind of threat. If the previous move was reduced, check if
// the move that refuted the null move was somehow connected to the
if (nullValue == value_mated_in(ply + 2))
mateThreat = true;
- ss[ply].threatMove = ss[ply + 1].currentMove;
+ threatMove = (ss+1)->bestMove;
if ( depth < ThreatDepth
- && ss[ply - 1].reduction
- && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
+ && (ss-1)->reduction
+ && connected_moves(pos, (ss-1)->currentMove, threatMove))
return beta - 1;
}
}
// Step 9. Internal iterative deepening
- if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
- !isCheck && ss[ply].eval >= beta - IIDMargin)
+ if ( depth >= IIDDepth[PvNode]
+ && ttMove == MOVE_NONE
+ && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin)))
{
- search(pos, ss, beta, depth/2, ply, false, threadID);
- ttMove = ss[ply].pv[ply];
+ Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
+
+ ss->skipNullMove = true;
+ search<PvNode>(pos, ss, alpha, beta, d, ply);
+ ss->skipNullMove = false;
+
+ ttMove = ss->bestMove;
tte = TT.retrieve(posKey);
}
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ // Expensive mate threat detection (only for PV nodes)
+ if (PvNode)
+ mateThreat = pos.has_mate_threat();
// Initialize a MovePicker object for the current position
- MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+ MovePicker mp = MovePicker(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta));
CheckInfo ci(pos);
+ ss->bestMove = MOVE_NONE;
+ singleEvasion = isCheck && mp.number_of_evasions() == 1;
+ futilityBase = ss->eval + margins[pos.side_to_move()];
+ singularExtensionNode = depth >= SingularExtensionDepth[PvNode]
+ && tte
+ && tte->move()
+ && !excludedMove // Do not allow recursive singular extension search
+ && (tte->type() & VALUE_TYPE_LOWER)
+ && tte->depth() >= depth - 3 * ONE_PLY;
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !TM.thread_should_stop(threadID))
+ && !ThreadsMgr.thread_should_stop(threadID))
{
assert(move_is_ok(move));
continue;
moveIsCheck = pos.move_is_check(move, ci);
- singleEvasion = (isCheck && mp.number_of_evasions() == 1);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
- ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
+ ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
- // Singular extension search. We extend the TT move if its value is much better than
- // its siblings. 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.
- if ( depth >= 8 * OnePly
- && tte
+ // 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.
+ if ( singularExtensionNode
&& move == tte->move()
- && !excludedMove // Do not allow recursive single-reply search
- && ext < OnePly
- && is_lower_bound(tte->type())
- && tte->depth() >= depth - 3 * OnePly)
+ && ext < ONE_PLY)
{
Value ttValue = value_from_tt(tte->value(), ply);
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
-
- if (excValue < ttValue - SingleReplyMargin)
- ext = OnePly;
+ Value b = ttValue - SingularExtensionMargin;
+ ss->excludedMove = move;
+ ss->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2, ply);
+ ss->skipNullMove = false;
+ ss->excludedMove = MOVE_NONE;
+ ss->bestMove = MOVE_NONE;
+ if (v < b)
+ ext = ONE_PLY;
}
}
- newDepth = depth - OnePly + ext;
+ newDepth = depth - ONE_PLY + ext;
// Update current move (this must be done after singular extension search)
- movesSearched[moveCount++] = ss[ply].currentMove = move;
+ movesSearched[moveCount++] = ss->currentMove = move;
- // Step 12. Futility pruning
- if ( !isCheck
- && !dangerous
+ // Step 12. Futility pruning (is omitted in PV nodes)
+ if ( !PvNode
&& !captureOrPromotion
- && !move_is_castle(move)
- && move != ttMove)
+ && !isCheck
+ && !dangerous
+ && move != ttMove
+ && !move_is_castle(move))
{
// Move count based pruning
if ( moveCount >= futility_move_count(depth)
- && ok_to_prune(pos, move, ss[ply].threatMove)
+ && !(threatMove && connected_threat(pos, move, threatMove))
&& bestValue > value_mated_in(PLY_MAX))
continue;
// Value based pruning
- Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); //FIXME: We are ignoring condition: depth >= 3*OnePly, BUG??
- futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount)
- + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
+ // 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));
if (futilityValueScaled < beta)
{
// Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Step 14. Reduced search
- // if the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth >= 3*OnePly
- && !dangerous
- && !captureOrPromotion
- && !move_is_castle(move)
- && !move_is_killer(move, ss[ply]))
+ // Step extra. pv search (only in PV nodes)
+ // The first move in list is the expected PV
+ if (PvNode && moveCount == 1)
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO, ply+1)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, ply+1);
+ else
{
- ss[ply].reduction = nonpv_reduction(depth, moveCount);
- if (ss[ply].reduction)
+ // 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)
+ && !move_is_killer(move, ss))
{
- value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID);
- doFullDepthSearch = (value >= beta);
+ ss->reduction = reduction<PvNode>(depth, moveCount);
+ if (ss->reduction)
+ {
+ Depth d = newDepth - ss->reduction;
+ value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO, ply+1)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, ply+1);
+
+ doFullDepthSearch = (value > alpha);
+ }
+
+ // The move failed high, but if reduction is very big we could
+ // face a false positive, retry with a less aggressive reduction,
+ // if the move fails high again then go with full depth search.
+ if (doFullDepthSearch && ss->reduction > 2 * ONE_PLY)
+ {
+ assert(newDepth - ONE_PLY >= ONE_PLY);
+
+ ss->reduction = ONE_PLY;
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, ply+1);
+ doFullDepthSearch = (value > alpha);
+ }
+ ss->reduction = DEPTH_ZERO; // Restore original reduction
}
- }
- // Step 15. Full depth search
- if (doFullDepthSearch)
- {
- ss[ply].reduction = Depth(0);
- value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
+ {
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO, ply+1)
+ : - 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 && value < beta)
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO, ply+1)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, ply+1);
+ }
}
// Step 16. Undo move
if (value > bestValue)
{
bestValue = value;
- if (value >= beta)
- update_pv(ss, ply);
+ if (value > alpha)
+ {
+ if (PvNode && value < beta) // We want always alpha < beta
+ alpha = value;
+
+ if (value == value_mate_in(ply + 1))
+ ss->mateKiller = move;
- if (value == value_mate_in(ply + 1))
- ss[ply].mateKiller = move;
+ ss->bestMove = move;
+ }
}
// Step 18. Check for split
- if ( TM.active_threads() > 1
+ if ( depth >= MinimumSplitDepth
+ && ThreadsMgr.active_threads() > 1
&& bestValue < beta
- && depth >= MinimumSplitDepth
- && Iteration <= 99
- && TM.available_thread_exists(threadID)
+ && ThreadsMgr.available_thread_exists(threadID)
&& !AbortSearch
- && !TM.thread_should_stop(threadID)
- && TM.split(pos, ss, ply, NULL, beta, &bestValue, futilityValue, //FIXME: SMP & futilityValue
- depth, &moveCount, &mp, threadID, false))
- break;
+ && !ThreadsMgr.thread_should_stop(threadID)
+ && Iteration <= 99)
+ ThreadsMgr.split<FakeSplit>(pos, ss, ply, &alpha, beta, &bestValue, depth,
+ threatMove, mateThreat, &moveCount, &mp, PvNode);
}
// Step 19. Check for mate and stalemate
- // All legal moves have been searched and if there were
+ // 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.
+ // If one move was excluded return fail low score.
if (!moveCount)
- return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
+ 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 (AbortSearch || TM.thread_should_stop(threadID))
+ if (AbortSearch || ThreadsMgr.thread_should_stop(threadID))
return bestValue;
- if (bestValue < beta)
- TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
- else
+ ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
+ move = (bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove);
+ TT.store(posKey, value_to_tt(bestValue, ply), vt, depth, move, ss->eval, margins[pos.side_to_move()]);
+
+ // Update killers and history only for non capture moves that fails high
+ if ( bestValue >= beta
+ && !pos.move_is_capture_or_promotion(move))
{
- TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
- move = ss[ply].pv[ply];
- TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
- if (!pos.move_is_capture_or_promotion(move))
- {
update_history(pos, move, depth, movesSearched, moveCount);
- update_killers(move, ss[ply]);
- }
-
+ update_killers(move, ss);
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// 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 OnePly).
+ // less than ONE_PLY).
- Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta,
- Depth depth, int ply, int threadID) {
+ template <NodeType PvNode>
+ Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) {
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(threadID >= 0 && threadID < TM.active_threads());
+ assert(ply > 0 && ply < PLY_MAX);
+ assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads());
- EvalInfo ei;
+ Value margins[2];
StateInfo st;
Move ttMove, move;
- Value staticValue, bestValue, value, futilityBase, futilityValue;
- bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
- const TTEntry* tte = NULL;
- int moveCount = 0;
- bool pvNode = (beta - alpha != 1);
+ Value bestValue, value, futilityValue, futilityBase;
+ bool isCheck, deepChecks, enoughMaterial, moveIsCheck, evasionPrunable;
+ const TTEntry* tte;
Value oldAlpha = alpha;
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
- init_node(ss, ply, threadID);
-
- // After init_node() that calls poll()
- if (AbortSearch || TM.thread_should_stop(threadID))
- return Value(0);
+ ThreadsMgr.incrementNodeCounter(pos.thread());
+ ss->bestMove = ss->currentMove = MOVE_NONE;
+ // Check for an instant draw or maximum ply reached
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
+ if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
{
- assert(tte->type() != VALUE_TYPE_EVAL);
-
- ss[ply].currentMove = ttMove; // Can be MOVE_NONE
+ ss->bestMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ply);
}
// Evaluate the position statically
if (isCheck)
- staticValue = -VALUE_INFINITE;
- else if (tte && (tte->type() & VALUE_TYPE_EVAL))
- staticValue = value_from_tt(tte->value(), ply);
- else
- staticValue = evaluate(pos, ei, threadID);
-
- if (!isCheck)
{
- ss[ply].eval = staticValue;
- update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
+ bestValue = futilityBase = -VALUE_INFINITE;
+ ss->eval = VALUE_NONE;
+ deepChecks = enoughMaterial = false;
}
+ else
+ {
+ if (tte)
+ {
+ assert(tte->static_value() != VALUE_NONE);
- // Initialize "stand pat score", and return it immediately if it is
- // at least beta.
- bestValue = staticValue;
+ margins[pos.side_to_move()] = tte->static_value_margin();
+ bestValue = tte->static_value();
+ }
+ else
+ bestValue = evaluate(pos, margins);
- if (bestValue >= beta)
- {
- // Store the score to avoid a future costly evaluation() call
- if (!isCheck && !tte && ei.futilityMargin[pos.side_to_move()] == 0)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE);
+ ss->eval = bestValue;
+ update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
- return bestValue;
- }
+ // 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, margins[pos.side_to_move()]);
+
+ return bestValue;
+ }
+
+ if (PvNode && bestValue > alpha)
+ alpha = bestValue;
- if (bestValue > alpha)
- alpha = bestValue;
+ // If we are near beta then try to get a cutoff pushing checks a bit further
+ deepChecks = (depth == -ONE_PLY && bestValue >= beta - PawnValueMidgame / 8);
- // If we are near beta then try to get a cutoff pushing checks a bit further
- bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8;
+ // Futility pruning parameters, not needed when in check
+ futilityBase = bestValue + FutilityMarginQS + margins[pos.side_to_move()];
+ enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
+ }
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
- // queen promotions and checks (only if depth == 0 or depth == -OnePly
+ // queen promotions and checks (only if depth == 0 or depth == -ONE_PLY
// and we are near beta) will be generated.
- MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H);
+ MovePicker mp = MovePicker(pos, ttMove, deepChecks ? DEPTH_ZERO : depth, H);
CheckInfo ci(pos);
- enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
- futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()];
- // Loop through the moves until no moves remain or a beta cutoff
- // occurs.
+ // Loop through the moves until no moves remain or a beta cutoff occurs
while ( alpha < beta
&& (move = mp.get_next_move()) != MOVE_NONE)
{
moveIsCheck = pos.move_is_check(move, ci);
- // Update current move
- moveCount++;
- ss[ply].currentMove = move;
-
// Futility pruning
- if ( enoughMaterial
+ if ( !PvNode
&& !isCheck
- && !pvNode
&& !moveIsCheck
&& move != ttMove
+ && enoughMaterial
&& !move_is_promotion(move)
&& !pos.move_is_passed_pawn_push(move))
{
futilityValue = futilityBase
+ pos.endgame_value_of_piece_on(move_to(move))
- + (move_is_ep(move) ? PawnValueEndgame : Value(0));
+ + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO);
if (futilityValue < alpha)
{
// Detect blocking evasions that are candidate to be pruned
evasionPrunable = isCheck
- && bestValue != -VALUE_INFINITE
+ && bestValue > value_mated_in(PLY_MAX)
&& !pos.move_is_capture(move)
&& pos.type_of_piece_on(move_from(move)) != KING
&& !pos.can_castle(pos.side_to_move());
// Don't search moves with negative SEE values
- if ( (!isCheck || evasionPrunable)
- && !pvNode
+ if ( !PvNode
+ && (!isCheck || evasionPrunable)
&& move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
continue;
+ // Update current move
+ ss->currentMove = move;
+
// Make and search the move
pos.do_move(move, st, ci, moveIsCheck);
- value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
+ value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-ONE_PLY, ply+1);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
if (value > alpha)
{
alpha = value;
- update_pv(ss, ply);
+ 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 (!moveCount && pos.is_check()) // Mate!
+ if (isCheck && bestValue == -VALUE_INFINITE)
return value_mated_in(ply);
// Update transposition table
- Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
- if (bestValue <= oldAlpha)
- {
- // If bestValue isn't changed it means it is still the static evaluation
- // of the node, so keep this info to avoid a future evaluation() call.
- ValueType type = (bestValue == staticValue && !ei.futilityMargin[pos.side_to_move()] ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
- }
- else if (bestValue >= beta)
- {
- move = ss[ply].pv[ply];
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
+ Depth d = (depth == DEPTH_ZERO ? DEPTH_ZERO : DEPTH_ZERO - ONE_PLY);
+ 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, d, ss->bestMove, ss->eval, margins[pos.side_to_move()]);
- // Update killers only for good checking moves
- if (!pos.move_is_capture_or_promotion(move))
- update_killers(move, ss[ply]);
- }
- else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss[ply].pv[ply]);
+ // Update killers only for checking moves that fails high
+ if ( bestValue >= beta
+ && !pos.move_is_capture_or_promotion(ss->bestMove))
+ update_killers(ss->bestMove, ss);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// 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>
void sp_search(SplitPoint* sp, int threadID) {
- assert(threadID >= 0 && threadID < TM.active_threads());
- assert(TM.active_threads() > 1);
+ assert(threadID >= 0 && threadID < ThreadsMgr.active_threads());
+ assert(ThreadsMgr.active_threads() > 1);
- Position pos(*sp->pos);
- CheckInfo ci(pos);
- SearchStack* ss = sp->sstack[threadID];
- Value value = -VALUE_INFINITE;
+ StateInfo st;
Move move;
+ Depth ext, newDepth;
+ Value value;
+ Value futilityValueScaled; // NonPV specific
+ bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
int moveCount;
- bool isCheck = pos.is_check();
- bool useFutilityPruning = sp->depth < 7 * OnePly //FIXME: sync with search
- && !isCheck;
-
- while ( lock_grab_bool(&(sp->lock))
- && sp->bestValue < sp->beta
- && !TM.thread_should_stop(threadID)
- && (move = sp->mp->get_next_move()) != MOVE_NONE)
+ value = -VALUE_INFINITE;
+
+ Position pos(*sp->pos, threadID);
+ CheckInfo ci(pos);
+ SearchStack* ss = sp->sstack[threadID] + 1;
+ isCheck = pos.is_check();
+
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ lock_grab(&(sp->lock));
+
+ while ( sp->bestValue < sp->beta
+ && (move = sp->mp->get_next_move()) != MOVE_NONE
+ && !ThreadsMgr.thread_should_stop(threadID))
{
- moveCount = ++sp->moves;
+ moveCount = ++sp->moveCount;
lock_release(&(sp->lock));
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- ss[sp->ply].currentMove = move;
+ // Step 11. Decide the new search depth
+ ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
+ newDepth = sp->depth - ONE_PLY + ext;
- // Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- Depth newDepth = sp->depth - OnePly + ext;
+ // Update current move
+ ss->currentMove = move;
- // Prune?
- if ( useFutilityPruning
+ // Step 12. Futility pruning (is omitted in PV nodes)
+ if ( !PvNode
+ && !captureOrPromotion
+ && !isCheck
&& !dangerous
- && !captureOrPromotion)
+ && !move_is_castle(move))
{
// Move count based pruning
if ( moveCount >= futility_move_count(sp->depth)
- && ok_to_prune(pos, move, ss[sp->ply].threatMove)
+ && !(sp->threatMove && connected_threat(pos, move, sp->threatMove))
&& sp->bestValue > value_mated_in(PLY_MAX))
+ {
+ lock_grab(&(sp->lock));
continue;
+ }
// Value based pruning
- Value futilityValueScaled = sp->futilityValue - moveCount * 8; //FIXME: sync with search
+ Depth predictedDepth = newDepth - reduction<NonPV>(sp->depth, moveCount);
+ futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move));
if (futilityValueScaled < sp->beta)
{
- if (futilityValueScaled > sp->bestValue) // Less then 1% of cases
- {
- lock_grab(&(sp->lock));
- if (futilityValueScaled > sp->bestValue)
- sp->bestValue = futilityValueScaled;
- lock_release(&(sp->lock));
- }
+ lock_grab(&(sp->lock));
+
+ if (futilityValueScaled > sp->bestValue)
+ sp->bestValue = futilityValueScaled;
continue;
}
}
- // Make and search the move.
- StateInfo st;
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
- // if the move fails high will be re-searched at full depth.
+ // Step 14. Reduced search
+ // If the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
- if ( !dangerous
- && !captureOrPromotion
+ if ( !captureOrPromotion
+ && !dangerous
&& !move_is_castle(move)
- && !move_is_killer(move, ss[sp->ply]))
+ && !move_is_killer(move, ss))
{
- ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount);
- if (ss[sp->ply].reduction)
+ ss->reduction = reduction<PvNode>(sp->depth, moveCount);
+ if (ss->reduction)
{
- value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
- doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID));
- }
- }
-
- if (doFullDepthSearch) // Go with full depth non-pv search
- {
- ss[sp->ply].reduction = Depth(0);
- value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
- }
- pos.undo_move(move);
-
- assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
+ Value localAlpha = sp->alpha;
+ Depth d = newDepth - ss->reduction;
+ value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, DEPTH_ZERO, sp->ply+1)
+ : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, d, sp->ply+1);
- // New best move?
- if (value > sp->bestValue) // Less then 2% of cases
- {
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !TM.thread_should_stop(threadID))
- {
- sp->bestValue = value;
- if (sp->bestValue >= sp->beta)
- {
- sp->stopRequest = true;
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- }
+ doFullDepthSearch = (value > localAlpha);
}
- lock_release(&(sp->lock));
- }
- }
-
- /* Here we have the lock still grabbed */
-
- sp->cpus--;
- sp->slaves[threadID] = 0;
-
- lock_release(&(sp->lock));
- }
-
-
- // sp_search_pv() is used to search from a PV split point. This function
- // is called by each thread working at the split point. It is similar to
- // the normal search_pv() function, but simpler. Because we have already
- // probed the hash table and searched the first move before splitting, we
- // don't have to repeat all this work in sp_search_pv(). 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.
-
- void sp_search_pv(SplitPoint* sp, int threadID) {
-
- assert(threadID >= 0 && threadID < TM.active_threads());
- assert(TM.active_threads() > 1);
-
- Position pos(*sp->pos);
- CheckInfo ci(pos);
- SearchStack* ss = sp->sstack[threadID];
- Value value = -VALUE_INFINITE;
- int moveCount;
- Move move;
-
- while ( lock_grab_bool(&(sp->lock))
- && sp->alpha < sp->beta
- && !TM.thread_should_stop(threadID)
- && (move = sp->mp->get_next_move()) != MOVE_NONE)
- {
- moveCount = ++sp->moves;
- lock_release(&(sp->lock));
-
- assert(move_is_ok(move));
-
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
-
- ss[sp->ply].currentMove = move;
- // Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- Depth newDepth = sp->depth - OnePly + ext;
-
- // Make and search the move.
- StateInfo st;
- pos.do_move(move, st, ci, moveIsCheck);
-
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
- // if the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( !dangerous
- && !captureOrPromotion
- && !move_is_castle(move)
- && !move_is_killer(move, ss[sp->ply]))
- {
- ss[sp->ply].reduction = pv_reduction(sp->depth, moveCount);
- if (ss[sp->ply].reduction)
+ // The move failed high, but if reduction is very big we could
+ // face a false positive, retry with a less aggressive reduction,
+ // if the move fails high again then go with full depth search.
+ if (doFullDepthSearch && ss->reduction > 2 * ONE_PLY)
{
+ assert(newDepth - ONE_PLY >= ONE_PLY);
+
+ ss->reduction = ONE_PLY;
Value localAlpha = sp->alpha;
- value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
- doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID));
+ value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1);
+ doFullDepthSearch = (value > localAlpha);
}
+ ss->reduction = DEPTH_ZERO; // Restore original reduction
}
- if (doFullDepthSearch) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
Value localAlpha = sp->alpha;
- ss[sp->ply].reduction = Depth(0);
- value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID);
-
- if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID))
- {
- // If another thread has failed high then sp->alpha has been increased
- // to be higher or equal then beta, if so, avoid to start a PV search.
- localAlpha = sp->alpha;
- if (localAlpha < sp->beta)
- value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID);
- }
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, DEPTH_ZERO, sp->ply+1)
+ : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, sp->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 > localAlpha && value < sp->beta)
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -sp->beta, -sp->alpha, DEPTH_ZERO, sp->ply+1)
+ : - search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth, sp->ply+1);
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // New best move?
- if (value > sp->bestValue) // Less then 2% of cases
+ // Step 17. Check for new best move
+ lock_grab(&(sp->lock));
+
+ if (value > sp->bestValue && !ThreadsMgr.thread_should_stop(threadID))
{
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !TM.thread_should_stop(threadID))
+ sp->bestValue = value;
+
+ if (sp->bestValue > sp->alpha)
{
- sp->bestValue = value;
- if (value > sp->alpha)
- {
- // Ask threads to stop before to modify sp->alpha
- if (value >= sp->beta)
- sp->stopRequest = true;
+ if (!PvNode || value >= sp->beta)
+ sp->stopRequest = true;
+ if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta
sp->alpha = value;
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- if (value == value_mate_in(sp->ply + 1))
- ss[sp->ply].mateKiller = move;
- }
+ sp->parentSstack->bestMove = ss->bestMove = move;
}
- lock_release(&(sp->lock));
}
}
/* Here we have the lock still grabbed */
- sp->cpus--;
sp->slaves[threadID] = 0;
lock_release(&(sp->lock));
}
- // init_node() is called at the beginning of all the search functions
- // (search(), search_pv(), qsearch(), and so on) and initializes the
- // search stack object corresponding to the current node. Once every
- // NodesBetweenPolls nodes, init_node() also calls poll(), which polls
- // for user input and checks whether it is time to stop the search.
-
- void init_node(SearchStack ss[], int ply, int threadID) {
-
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < TM.active_threads());
-
- TM.incrementNodeCounter(threadID);
-
- if (threadID == 0)
- {
- NodesSincePoll++;
- if (NodesSincePoll >= NodesBetweenPolls)
- {
- poll();
- NodesSincePoll = 0;
- }
- }
- ss[ply].init(ply);
- ss[ply + 2].initKillers();
- TM.print_current_line(ss, ply, threadID);
- }
-
-
- // update_pv() is called whenever a search returns a value > alpha.
- // It updates the PV in the SearchStack object corresponding to the
- // current node.
-
- void update_pv(SearchStack ss[], int ply) {
-
- assert(ply >= 0 && ply < PLY_MAX);
-
- int p;
-
- ss[ply].pv[ply] = ss[ply].currentMove;
-
- for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++)
- ss[ply].pv[p] = ss[ply + 1].pv[p];
-
- ss[ply].pv[p] = MOVE_NONE;
- }
-
-
- // sp_update_pv() is a variant of update_pv for use at split points. The
- // difference between the two functions is that sp_update_pv also updates
- // the PV at the parent node.
-
- void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) {
-
- assert(ply >= 0 && ply < PLY_MAX);
-
- int p;
-
- ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove;
-
- for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++)
- ss[ply].pv[p] = pss[ply].pv[p] = ss[ply + 1].pv[p];
-
- ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE;
- }
-
-
// connected_moves() tests whether two moves are 'connected' in the sense
// that the first move somehow made the second move possible (for instance
// if the moving piece is the same in both moves). The first move is assumed
}
- // value_is_mate() checks if the given value is a mate one
- // eventually compensated for the ply.
+ // value_is_mate() checks if the given value is a mate one eventually
+ // compensated for the ply.
bool value_is_mate(Value value) {
}
- // move_is_killer() checks if the given move is among the
- // killer moves of that ply.
+ // 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.
+
+ Value value_to_tt(Value v, int ply) {
+
+ if (v >= value_mate_in(PLY_MAX))
+ return v + ply;
+
+ if (v <= value_mated_in(PLY_MAX))
+ return v - ply;
+
+ return v;
+ }
+
+
+ // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score from
+ // the transposition table to a mate score corrected for the current ply.
+
+ Value value_from_tt(Value v, int ply) {
+
+ if (v >= value_mate_in(PLY_MAX))
+ return v - ply;
+
+ if (v <= value_mated_in(PLY_MAX))
+ return v + ply;
+
+ return v;
+ }
+
+
+ // move_is_killer() checks if the given move is among the killer moves
- bool move_is_killer(Move m, const SearchStack& ss) {
+ bool move_is_killer(Move m, SearchStack* ss) {
- const Move* k = ss.killers;
- for (int i = 0; i < KILLER_MAX; i++, k++)
- if (*k == m)
- return true;
+ if (ss->killers[0] == m || ss->killers[1] == m)
+ return true;
return false;
}
// any case are marked as 'dangerous'. Note that also if a move is not
// extended, as example because the corresponding UCI option is set to zero,
// the move is marked as 'dangerous' so, at least, we avoid to prune it.
-
- Depth extension(const Position& pos, Move m, bool pvNode, bool captureOrPromotion,
- bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous) {
+ template <NodeType PvNode>
+ Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck,
+ bool singleEvasion, bool mateThreat, bool* dangerous) {
assert(m != MOVE_NONE);
- Depth result = Depth(0);
+ Depth result = DEPTH_ZERO;
*dangerous = moveIsCheck | singleEvasion | mateThreat;
if (*dangerous)
{
- if (moveIsCheck)
- result += CheckExtension[pvNode];
+ if (moveIsCheck && pos.see_sign(m) >= 0)
+ result += CheckExtension[PvNode];
if (singleEvasion)
- result += SingleEvasionExtension[pvNode];
+ result += SingleEvasionExtension[PvNode];
if (mateThreat)
- result += MateThreatExtension[pvNode];
+ 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];
+ result += PawnPushTo7thExtension[PvNode];
*dangerous = true;
}
if (pos.pawn_is_passed(c, move_to(m)))
{
- result += PassedPawnExtension[pvNode];
+ 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(0))
+ - pos.midgame_value_of_piece_on(move_to(m)) == VALUE_ZERO)
&& !move_is_promotion(m)
&& !move_is_ep(m))
{
- result += PawnEndgameExtension[pvNode];
+ result += PawnEndgameExtension[PvNode];
*dangerous = true;
}
- if ( pvNode
+ if ( PvNode
&& captureOrPromotion
&& pos.type_of_piece_on(move_to(m)) != PAWN
&& pos.see_sign(m) >= 0)
{
- result += OnePly/2;
+ result += ONE_PLY / 2;
*dangerous = true;
}
- return Min(result, OnePly);
- }
-
-
- // ok_to_do_nullmove() looks at the current position and decides whether
- // doing a 'null move' should be allowed. In order to avoid zugzwang
- // problems, null moves are not allowed when the side to move has very
- // little material left. Currently, the test is a bit too simple: Null
- // moves are avoided only when the side to move has only pawns left.
- // It's probably a good idea to avoid null moves in at least some more
- // complicated endgames, e.g. KQ vs KR. FIXME
-
- bool ok_to_do_nullmove(const Position& pos) {
-
- return pos.non_pawn_material(pos.side_to_move()) != Value(0);
+ return Min(result, ONE_PLY);
}
- // ok_to_prune() tests whether it is safe to forward prune a move. Only
- // non-tactical moves late in the move list close to the leaves are
- // candidates for pruning.
+ // 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.
- bool ok_to_prune(const Position& pos, Move m, Move threat) {
+ bool connected_threat(const Position& pos, Move m, Move threat) {
assert(move_is_ok(m));
- assert(threat == MOVE_NONE || move_is_ok(threat));
+ 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));
Square mfrom, mto, tfrom, tto;
- // Prune if there isn't any threat move
- if (threat == MOVE_NONE)
- return true;
-
mfrom = move_from(m);
mto = move_to(m);
tfrom = move_from(threat);
// Case 1: Don't prune moves which move the threatened piece
if (mfrom == tto)
- return false;
+ 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.
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
|| pos.type_of_piece_on(tfrom) == KING)
&& pos.move_attacks_square(m, tto))
- return false;
+ return true;
// Case 3: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
if ( piece_is_slider(pos.piece_on(tfrom))
&& bit_is_set(squares_between(tfrom, tto), mto)
&& pos.see_sign(m) >= 0)
- return false;
+ return true;
- return true;
+ return false;
}
|| v >= Max(value_mate_in(PLY_MAX), beta)
|| v < Min(value_mated_in(PLY_MAX), beta))
- && ( (is_lower_bound(tte->type()) && v >= beta)
- || (is_upper_bound(tte->type()) && v < beta));
+ && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta)
+ || ((tte->type() & VALUE_TYPE_UPPER) && v < beta));
}
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
- if (!tte)
- return defaultEval;
+ assert(tte);
Value v = value_from_tt(tte->value(), ply);
- if ( (is_lower_bound(tte->type()) && v >= defaultEval)
- || (is_upper_bound(tte->type()) && v < defaultEval))
+ if ( ((tte->type() & VALUE_TYPE_LOWER) && v >= defaultEval)
+ || ((tte->type() & VALUE_TYPE_UPPER) && v < defaultEval))
return v;
return defaultEval;
// update_killers() add a good move that produced a beta-cutoff
// among the killer moves of that ply.
- void update_killers(Move m, SearchStack& ss) {
+ void update_killers(Move m, SearchStack* ss) {
- if (m == ss.killers[0])
+ if (m == ss->killers[0])
return;
- for (int i = KILLER_MAX - 1; i > 0; i--)
- ss.killers[i] = ss.killers[i - 1];
-
- ss.killers[0] = m;
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = m;
}
if ( m != MOVE_NULL
&& before != VALUE_NONE
&& after != VALUE_NONE
- && pos.captured_piece() == NO_PIECE_TYPE
- && !move_is_castle(m)
- && !move_is_promotion(m))
+ && pos.captured_piece_type() == PIECE_TYPE_NONE
+ && !move_is_special(m))
H.set_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after));
}
}
+ // value_to_uci() converts a value to a string suitable for use with the UCI protocol
+
+ std::string value_to_uci(Value v) {
+
+ std::stringstream s;
+
+ if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY)
+ s << "cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to pawn = 100
+ else
+ s << "mate " << (v > 0 ? (VALUE_MATE - v + 1) / 2 : -(VALUE_MATE + v) / 2 );
+
+ return s.str();
+ }
+
// nps() computes the current nodes/second count.
int nps() {
int t = current_search_time();
- return (t > 0 ? int((TM.nodes_searched() * 1000) / t) : 0);
+ return (t > 0 ? int((ThreadsMgr.nodes_searched() * 1000) / t) : 0);
}
else if (t - lastInfoTime >= 1000)
{
lastInfoTime = t;
- lock_grab(&TM.IOLock);
if (dbg_show_mean)
dbg_print_mean();
if (dbg_show_hit_rate)
dbg_print_hit_rate();
- cout << "info nodes " << TM.nodes_searched() << " nps " << nps()
- << " time " << t << " hashfull " << TT.full() << endl;
-
- lock_release(&TM.IOLock);
-
- if (ShowCurrentLine)
- TM.threads[0].printCurrentLineRequest = true;
+ cout << "info nodes " << ThreadsMgr.nodes_searched() << " nps " << nps()
+ << " time " << t << endl;
}
// Should we stop the search?
if (PonderSearch)
return;
- bool stillAtFirstMove = RootMoveNumber == 1
+ bool stillAtFirstMove = FirstRootMove
&& !AspirationFailLow
- && t > MaxSearchTime + ExtraSearchTime;
+ && t > TimeMgr.available_time();
- bool noMoreTime = t > AbsoluteMaxSearchTime
+ bool noMoreTime = t > TimeMgr.maximum_time()
|| stillAtFirstMove;
if ( (Iteration >= 3 && UseTimeManagement && noMoreTime)
|| (ExactMaxTime && t >= ExactMaxTime)
- || (Iteration >= 3 && MaxNodes && TM.nodes_searched() >= MaxNodes))
+ || (Iteration >= 3 && MaxNodes && ThreadsMgr.nodes_searched() >= MaxNodes))
AbortSearch = true;
}
int t = current_search_time();
PonderSearch = false;
- bool stillAtFirstMove = RootMoveNumber == 1
+ bool stillAtFirstMove = FirstRootMove
&& !AspirationFailLow
- && t > MaxSearchTime + ExtraSearchTime;
+ && t > TimeMgr.available_time();
- bool noMoreTime = t > AbsoluteMaxSearchTime
+ bool noMoreTime = t > TimeMgr.maximum_time()
|| stillAtFirstMove;
if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit))
}
- // init_ss_array() does a fast reset of the first entries of a SearchStack array
+ // init_ss_array() does a fast reset of the first entries of a SearchStack
+ // array and of all the excludedMove and skipNullMove entries.
- void init_ss_array(SearchStack ss[]) {
+ void init_ss_array(SearchStack* ss, int size) {
- for (int i = 0; i < 3; i++)
+ for (int i = 0; i < size; i++, ss++)
{
- ss[i].init(i);
- ss[i].initKillers();
+ ss->excludedMove = MOVE_NONE;
+ ss->skipNullMove = false;
+ ss->reduction = DEPTH_ZERO;
+
+ if (i < 3)
+ ss->killers[0] = ss->killers[1] = ss->mateKiller = MOVE_NONE;
}
}
}
+ // print_pv_info() prints to standard output and eventually to log file information on
+ // the current PV line. It is called at each iteration or after a new pv is found.
+
+ void print_pv_info(const Position& pos, Move pv[], Value alpha, Value beta, Value value) {
+
+ cout << "info depth " << Iteration
+ << " score " << value_to_uci(value)
+ << (value >= beta ? " lowerbound" : value <= alpha ? " upperbound" : "")
+ << " time " << current_search_time()
+ << " nodes " << ThreadsMgr.nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (Move* m = pv; *m != MOVE_NONE; m++)
+ cout << *m << " ";
+
+ cout << endl;
+
+ if (UseLogFile)
+ {
+ ValueType t = value >= beta ? VALUE_TYPE_LOWER :
+ value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT;
+
+ LogFile << pretty_pv(pos, current_search_time(), Iteration,
+ ThreadsMgr.nodes_searched(), value, t, pv) << endl;
+ }
+ }
+
+
+ // insert_pv_in_tt() is called at the end of a search iteration, and inserts
+ // the PV back into the TT. This makes sure the old PV moves are searched
+ // first, even if the old TT entries have been overwritten.
+
+ void insert_pv_in_tt(const Position& pos, Move pv[]) {
+
+ StateInfo st;
+ TTEntry* tte;
+ Position p(pos, pos.thread());
+ Value margins[2];
+ Value v;
+
+ for (int i = 0; pv[i] != MOVE_NONE; i++)
+ {
+ tte = TT.retrieve(p.get_key());
+ if (!tte || tte->move() != pv[i])
+ {
+ v = (p.is_check() ? VALUE_NONE : evaluate(p, margins));
+ TT.store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[i], v, margins[pos.side_to_move()]);
+ }
+ p.do_move(pv[i], st);
+ }
+ }
+
+
+ // 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
+ // allow to always have a ponder move even when we fail high at root and also a
+ // long PV to print that is important for position analysis.
+
+ void extract_pv_from_tt(const Position& pos, Move bestMove, Move pv[]) {
+
+ StateInfo st;
+ TTEntry* tte;
+ Position p(pos, pos.thread());
+ int ply = 0;
+
+ assert(bestMove != MOVE_NONE);
+
+ pv[ply] = bestMove;
+ p.do_move(pv[ply++], st);
+
+ while ( (tte = TT.retrieve(p.get_key())) != NULL
+ && tte->move() != MOVE_NONE
+ && move_is_legal(p, tte->move())
+ && ply < PLY_MAX
+ && (!p.is_draw() || ply < 2))
+ {
+ pv[ply] = tte->move();
+ p.do_move(pv[ply++], st);
+ }
+ pv[ply] = MOVE_NONE;
+ }
+
+
// 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
void* init_thread(void *threadID) {
- TM.idle_loop(*(int*)threadID, NULL);
+ ThreadsMgr.idle_loop(*(int*)threadID, NULL);
return NULL;
}
DWORD WINAPI init_thread(LPVOID threadID) {
- TM.idle_loop(*(int*)threadID, NULL);
- return NULL;
+ ThreadsMgr.idle_loop(*(int*)threadID, NULL);
+ return 0;
}
#endif
threads[i].nodes = 0ULL;
}
- void ThreadsManager::resetBetaCounters() {
-
- for (int i = 0; i < MAX_THREADS; i++)
- threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL;
- }
-
int64_t ThreadsManager::nodes_searched() const {
int64_t result = 0ULL;
return result;
}
- void ThreadsManager::get_beta_counters(Color us, int64_t& our, int64_t& their) const {
-
- our = their = 0UL;
- for (int i = 0; i < MAX_THREADS; i++)
- {
- our += threads[i].betaCutOffs[us];
- their += threads[i].betaCutOffs[opposite_color(us)];
- }
- }
-
// idle_loop() is where the threads are parked when they have no work to do.
- // The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint
+ // 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* waitSp) {
+ void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) {
assert(threadID >= 0 && threadID < MAX_THREADS);
// master should exit as last one.
if (AllThreadsShouldExit)
{
- assert(!waitSp);
+ assert(!sp);
threads[threadID].state = THREAD_TERMINATED;
return;
}
// instead of wasting CPU time polling for work.
while (AllThreadsShouldSleep || threadID >= ActiveThreads)
{
- assert(!waitSp);
+ assert(!sp);
assert(threadID != 0);
threads[threadID].state = THREAD_SLEEPING;
#if !defined(_MSC_VER)
- pthread_mutex_lock(&WaitLock);
+ lock_grab(&WaitLock);
if (AllThreadsShouldSleep || threadID >= ActiveThreads)
pthread_cond_wait(&WaitCond, &WaitLock);
- pthread_mutex_unlock(&WaitLock);
+ lock_release(&WaitLock);
#else
WaitForSingleObject(SitIdleEvent[threadID], INFINITE);
#endif
threads[threadID].state = THREAD_SEARCHING;
if (threads[threadID].splitPoint->pvNode)
- sp_search_pv(threads[threadID].splitPoint, threadID);
+ sp_search<PV>(threads[threadID].splitPoint, threadID);
else
- sp_search(threads[threadID].splitPoint, threadID);
+ sp_search<NonPV>(threads[threadID].splitPoint, threadID);
assert(threads[threadID].state == THREAD_SEARCHING);
threads[threadID].state = THREAD_AVAILABLE;
}
- // If this thread is the master of a split point and all threads have
+ // 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 (waitSp != NULL && waitSp->cpus == 0)
+ int i = 0;
+ for ( ; sp && i < ActiveThreads && !sp->slaves[i]; i++) {}
+
+ if (i == ActiveThreads)
{
+ // 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));
+
assert(threads[threadID].state == THREAD_AVAILABLE);
threads[threadID].state = THREAD_SEARCHING;
#endif
// Initialize global locks
- lock_init(&MPLock, NULL);
- lock_init(&IOLock, NULL);
-
- // Initialize SplitPointStack locks
- for (i = 0; i < MAX_THREADS; i++)
- for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
- {
- SplitPointStack[i][j].parent = NULL;
- lock_init(&(SplitPointStack[i][j].lock), NULL);
- }
+ lock_init(&MPLock);
+ lock_init(&WaitLock);
#if !defined(_MSC_VER)
- pthread_mutex_init(&WaitLock, NULL);
pthread_cond_init(&WaitCond, NULL);
#else
for (i = 0; i < MAX_THREADS; i++)
SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
#endif
+ // 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;
#if !defined(_MSC_VER)
ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0);
#else
- DWORD iID[1];
- ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID) != NULL);
+ ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, NULL) != NULL);
#endif
if (!ok)
}
// Wait until the thread has finished launching and is gone to sleep
- while (threads[i].state != THREAD_SLEEPING);
+ while (threads[i].state != THREAD_SLEEPING) {}
}
}
// Wait for thread termination
for (int i = 1; i < MAX_THREADS; i++)
- while (threads[i].state != THREAD_TERMINATED);
+ while (threads[i].state != THREAD_TERMINATED) {}
// Now we can safely destroy the locks
for (int i = 0; i < MAX_THREADS; i++)
- for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
- lock_destroy(&(SplitPointStack[i][j].lock));
+ for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
+ lock_destroy(&(threads[i].splitPoints[j].lock));
+
+ lock_destroy(&WaitLock);
+ lock_destroy(&MPLock);
}
SplitPoint* sp;
- for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent);
+ for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {}
return sp != NULL;
}
// 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 (SplitPointStack[slave][localActiveSplitPoints - 1].slaves[master])
+ if (threads[slave].splitPoints[localActiveSplitPoints - 1].slaves[master])
return true;
return false;
// split() does the actual work of distributing the work at a node between
- // several threads at PV nodes. If it does not succeed in splitting the
+ // 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 false. If
- // splitting is possible, a SplitPoint object is initialized with all the
- // data that must be copied to the helper threads (the current position and
- // search stack, alpha, beta, the search depth, etc.), and we tell our
- // helper threads that they have been assigned work. This will cause them
- // to instantly leave their idle loops and call sp_search_pv(). When all
- // threads have returned from sp_search_pv (or, equivalently, when
- // splitPoint->cpus becomes 0), split() returns true.
-
- bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply,
- Value* alpha, const Value beta, Value* bestValue, const Value futilityValue,
- Depth depth, int* moves, MovePicker* mp, int master, bool pvNode) {
-
+ // 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 sp_search(). When all threads have returned from sp_search() then
+ // split() returns.
+
+ template <bool Fake>
+ void ThreadsManager::split(const Position& p, SearchStack* ss, int ply, Value* alpha,
+ const Value beta, Value* bestValue, Depth depth, Move threatMove,
+ bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode) {
assert(p.is_ok());
- assert(sstck != NULL);
- assert(ply >= 0 && ply < PLY_MAX);
+ assert(ply > 0 && ply < PLY_MAX);
assert(*bestValue >= -VALUE_INFINITE);
- assert( ( pvNode && *bestValue <= *alpha)
- || (!pvNode && *bestValue < beta ));
- assert(!pvNode || *alpha < beta);
+ assert(*bestValue <= *alpha);
+ assert(*alpha < beta);
assert(beta <= VALUE_INFINITE);
- assert(depth > Depth(0));
- assert(master >= 0 && master < ActiveThreads);
+ assert(depth > DEPTH_ZERO);
+ assert(p.thread() >= 0 && p.thread() < ActiveThreads);
assert(ActiveThreads > 1);
- SplitPoint* splitPoint;
+ int i, master = p.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)
- || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX)
+ || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
{
lock_release(&MPLock);
- return false;
+ return;
}
// Pick the next available split point object from the split point stack
- splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints];
+ SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++];
// Initialize the split point object
- splitPoint->parent = threads[master].splitPoint;
- splitPoint->stopRequest = false;
- splitPoint->ply = ply;
- splitPoint->depth = depth;
- splitPoint->alpha = pvNode ? *alpha : beta - 1;
- splitPoint->beta = beta;
- splitPoint->pvNode = pvNode;
- splitPoint->bestValue = *bestValue;
- splitPoint->futilityValue = futilityValue;
- splitPoint->master = master;
- splitPoint->mp = mp;
- splitPoint->moves = *moves;
- splitPoint->cpus = 1;
- splitPoint->pos = &p;
- splitPoint->parentSstack = sstck;
- for (int i = 0; i < ActiveThreads; i++)
- splitPoint->slaves[i] = 0;
-
- threads[master].splitPoint = splitPoint;
- threads[master].activeSplitPoints++;
+ splitPoint.parent = masterThread.splitPoint;
+ splitPoint.stopRequest = 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 = &p;
+ 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(threads[master].state != THREAD_AVAILABLE);
+ assert(masterThread.state != THREAD_AVAILABLE);
+
+ int workersCnt = 1; // At least the master is included
// Allocate available threads setting state to THREAD_BOOKED
- for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++)
+ 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;
- splitPoint->cpus++;
+ threads[i].splitPoint = &splitPoint;
+ splitPoint.slaves[i] = 1;
+ workersCnt++;
}
- assert(splitPoint->cpus > 1);
+ assert(Fake || workersCnt > 1);
// We can release the lock because slave threads are already booked and master is not available
lock_release(&MPLock);
// 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 (int i = 0; i < ActiveThreads; i++)
- if (i == master || splitPoint->slaves[i])
+ for (i = 0; i < ActiveThreads; i++)
+ if (i == master || splitPoint.slaves[i])
{
- memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 4 * sizeof(SearchStack));
+ memcpy(splitPoint.sstack[i], ss - 1, 4 * sizeof(SearchStack));
assert(i == master || threads[i].state == THREAD_BOOKED);
// 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
- // (i.e. when splitPoint->cpus == 0).
- idle_loop(master, splitPoint);
+ // 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, beta and bestValue, and return.
+ // finished. Update alpha and bestValue, and return.
lock_grab(&MPLock);
- if (pvNode)
- *alpha = splitPoint->alpha;
-
- *bestValue = splitPoint->bestValue;
- threads[master].activeSplitPoints--;
- threads[master].splitPoint = splitPoint->parent;
+ *alpha = splitPoint.alpha;
+ *bestValue = splitPoint.bestValue;
+ masterThread.activeSplitPoints--;
+ masterThread.splitPoint = splitPoint.parent;
lock_release(&MPLock);
- return true;
}
if (ActiveThreads == 1)
return;
- for (int i = 1; i < ActiveThreads; i++)
- assert(threads[i].state == THREAD_SLEEPING);
-
#if !defined(_MSC_VER)
pthread_mutex_lock(&WaitLock);
pthread_cond_broadcast(&WaitCond);
// This makes the threads to go to sleep
AllThreadsShouldSleep = true;
-
- // Reset flags to a known state.
- for (int i = 1; i < ActiveThreads; i++)
- {
- // This flag can be in a random state
- threads[i].printCurrentLineRequest = false;
- }
- }
-
- // print_current_line() prints _once_ the current line of search for a
- // given thread and then setup the print request for the next thread.
- // Called when the UCI option UCI_ShowCurrLine is 'true'.
-
- void ThreadsManager::print_current_line(SearchStack ss[], int ply, int threadID) {
-
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
-
- if (!threads[threadID].printCurrentLineRequest)
- return;
-
- // One shot only
- threads[threadID].printCurrentLineRequest = false;
-
- if (threads[threadID].state == THREAD_SEARCHING)
- {
- lock_grab(&IOLock);
- cout << "info currline " << (threadID + 1);
- for (int p = 0; p < ply; p++)
- cout << " " << ss[p].currentMove;
-
- cout << endl;
- lock_release(&IOLock);
- }
-
- // Setup print request for the next thread ID
- if (threadID + 1 < ActiveThreads)
- threads[threadID + 1].printCurrentLineRequest = true;
}
-
/// The RootMoveList class
// RootMoveList c'tor
StateInfo st;
bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
+ // Initialize search stack
+ init_ss_array(ss, PLY_MAX_PLUS_2);
+ ss[0].currentMove = ss[0].bestMove = MOVE_NONE;
+ ss[0].eval = VALUE_NONE;
+
// Generate all legal moves
MoveStack* last = generate_moves(pos, mlist);
continue;
// Find a quick score for the move
- init_ss_array(ss);
pos.do_move(cur->move, st);
+ ss[0].currentMove = cur->move;
moves[count].move = cur->move;
- moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
+ moves[count].score = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1);
moves[count].pv[0] = cur->move;
moves[count].pv[1] = MOVE_NONE;
pos.undo_move(cur->move);
sort();
}
+ // 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.
- // RootMoveList simple methods definitions
-
- void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) {
+ void RootMoveList::score_moves(const Position& pos)
+ {
+ Move move;
+ int score = 1000;
+ MovePicker mp = MovePicker(pos, MOVE_NONE, ONE_PLY, H);
- moves[moveNum].nodes = nodes;
- moves[moveNum].cumulativeNodes += nodes;
+ while ((move = mp.get_next_move()) != MOVE_NONE)
+ for (int i = 0; i < count; i++)
+ if (moves[i].move == move)
+ {
+ moves[i].mp_score = score--;
+ break;
+ }
}
- void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
-
- moves[moveNum].ourBeta = our;
- moves[moveNum].theirBeta = their;
- }
+ // RootMoveList simple methods definitions
void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
projects / stockfish / blobdiff