/*
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
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,
- Depth depth, int* moves, MovePicker* mp, int master, bool pvNode);
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode);
private:
friend void poll(SearchStack ss[], int ply);
Thread threads[MAX_THREADS];
SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX];
- Lock MPLock;
+ Lock MPLock, WaitLock;
#if !defined(_MSC_VER)
pthread_cond_t WaitCond;
- pthread_mutex_t WaitLock;
#else
HANDLE SitIdleEvent[MAX_THREADS];
#endif
// Step 6. Razoring
+ // Maximum depth for razoring
const Depth RazorDepth = 4 * OnePly;
- inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * d); }
+
+ // 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
// evaluation of the position is more than NullMoveMargin below beta.
const Value NullMoveMargin = Value(0x200);
+ // Maximum depth for use of dynamic threat detection when null move fails low
+ const Depth ThreatDepth = 5 * OnePly;
+
// Step 9. Internal iterative deepening
+ // Minimum depth for use of internal iterative deepening
const Depth IIDDepthAtPVNodes = 5 * OnePly;
const Depth IIDDepthAtNonPVNodes = 8 * OnePly;
- // Internal iterative deepening margin. At Non-PV nodes
- // we do an internal iterative deepening
- // search when the static evaluation is at most IIDMargin below beta.
+ // At Non-PV nodes we do an internal iterative deepening search
+ // when the static evaluation is at most IIDMargin below beta.
const Value IIDMargin = Value(0x100);
- // Search depth at iteration 1
- const Depth InitialDepth = OnePly;
-
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
+ // Step 11. Decide the new search depth
- // If the TT move is at least SingleReplyMargin better then the
- // remaining ones we will extend it.
- const Value SingleReplyMargin = Value(0x20);
+ // 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];
- /// Lookup tables initialized at startup
+ // Minimum depth for use of singular extension
+ const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly;
+ const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly;
- // Reduction lookup tables and their getter functions
- int8_t PVReductionMatrix[64][64]; // [depth][moveNumber]
- int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber]
+ // If the TT move is at least SingularExtensionMargin better then the
+ // remaining ones we will extend it.
+ const Value SingularExtensionMargin = Value(0x20);
- 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)]; }
+ // Step 12. Futility pruning
- // Futility lookup tables and their getter functions
+ // 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 * 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; }
+
+ // Step 14. Reduced search
+
+ int ReductionLevel = 2; // 0 = most aggressive reductions, 7 = minimum reductions
- /// Variables initialized by UCI options
+ // Reduction lookup tables (initialized at startup) and their getter functions
+ int8_t PVReductionMatrix[8][64][64]; // [depth][moveNumber]
+ int8_t NonPVReductionMatrix[8][64][64]; // [depth][moveNumber]
- // Depth limit for use of dynamic threat detection
- Depth ThreatDepth;
+ inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; }
+ inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; }
+
+ // Common adjustments
+
+ // Search depth at iteration 1
+ const Depth InitialDepth = OnePly;
+
+ // Easy move margin. An easy move candidate must be at least this much
+ // better than the second best move.
+ const Value EasyMoveMargin = Value(0x200);
// Last seconds noise filtering (LSN)
const bool UseLSNFiltering = true;
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
- // 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];
- // Iteration counters
+ /// 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, MaxSearchTime;
+ int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
- bool AbortSearch, Quit;
- bool AspirationFailLow;
+ bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
// Show current line?
bool ShowCurrentLine;
bool UseLogFile;
std::ofstream LogFile;
- // MP related variables
+ // Multi-threads related variables
Depth MinimumSplitDepth;
int MaxThreadsPerSplitPoint;
ThreadsManager TM;
- // 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 root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
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);
void ponderhit();
void wait_for_stop_or_ponderhit();
void init_ss_array(SearchStack ss[]);
+ void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value);
#if !defined(_MSC_VER)
void *init_thread(void *threadID);
int perft(Position& pos, Depth depth)
{
+ StateInfo st;
Move move;
int sum = 0;
- MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
+ MovePicker mp(pos, MOVE_NONE, depth, H);
// If we are at the last ply we don't need to do and undo
// the moves, just to count them.
CheckInfo ci(pos);
while ((move = mp.get_next_move()) != MOVE_NONE)
{
- StateInfo st;
pos.do_move(move, st, ci, pos.move_is_check(move, ci));
sum += perft(pos, depth - OnePly);
pos.undo_move(move);
int maxNodes, int maxTime, Move searchMoves[]) {
// Initialize global search variables
- StopOnPonderhit = AbortSearch = Quit = false;
- AspirationFailLow = false;
+ StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
+ MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0;
NodesSincePoll = 0;
+ TM.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);
if (bookMove != MOVE_NONE)
{
if (PonderSearch)
}
}
- TM.resetNodeCounters();
-
+ // Reset loseOnTime flag at the beginning of a new game
if (button_was_pressed("New Game"))
- loseOnTime = false; // Reset at the beginning of a new game
+ loseOnTime = false;
// 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") * OnePly;
+ MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
+ ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
+ MultiPV = get_option_value_int("MultiPV");
+ Chess960 = get_option_value_bool("UCI_Chess960");
+ 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
{
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());
}
// Wake up sleeping threads
}
}
- if (PonderingEnabled)
+ if (get_option_value_bool("Ponder"))
{
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.
+ // LSN filtering. Used only for developing purposes, disabled by default
if ( UseLSNFiltering
&& loseOnTime)
{
return !Quit;
}
+// init_reduction_tables() is called by init_search() and initializes
+// the tables used by LMR.
+static void init_reduction_tables(int8_t pvTable[64][64], int8_t nonPvTable[64][64], int pvInhib, int nonPvInhib)
+{
+ double pvBase = 1.001 - log(3.0) * log(16.0) / pvInhib;
+ double nonPvBase = 1.001 - log(3.0) * log(4.0) / nonPvInhib;
-/// 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);
+ double pvRed = pvBase + log(double(i)) * log(double(j)) / pvInhib;
+ double nonPVRed = nonPvBase + log(double(i)) * log(double(j)) / nonPvInhib;
+
+ pvTable[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0);
+ nonPvTable[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
}
+}
+
+// init_search() is called during startup. It initializes various lookup tables
+void init_search() {
+
+ // Init reduction lookup tables
+ for (int i = 0; i < 8; i++)
+ init_reduction_tables(PVReductionMatrix[i], NonPVReductionMatrix[i], int(4 * pow(1.3, i)), int(2 * pow(1.3, i)));
// Init futility margins array
- for (int i = 0; i < 14; i++) // i == depth (OnePly = 2)
+ for (int i = 0; i < 16; 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
+ // FIXME: test using log instead of BSR
+ FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j;
}
// Init futility move count array
Position p(pos);
SearchStack ss[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
+ // Print RootMoveList startup scoring to the standard output,
+ // so to output information also for iteration 1.
+ cout << "info depth " << 1
+ << "\ninfo depth " << 1
<< " score " << value_to_string(rml.get_move_score(0))
<< " time " << current_search_time()
<< " nodes " << TM.nodes_searched()
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);
}
+
+ // Choose optimum reduction level
+ ReductionLevel = 2;
+
+ if (UseTimeManagement)
+ {
+ int level = int(floor(log(float(MaxSearchTime) / current_search_time()) / log(2.0) + 1.0));
+ ReductionLevel = Min(Max(level, 0), 7);
+ }
else
{
- alpha = - VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ //FIXME
}
- // 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, rml, &alpha, &beta);
// Write PV to transposition table, in case the relevant entries have
// been overwritten during the search.
//Save info about search result
ValueByIteration[Iteration] = value;
- // Drop the easy move if it differs from the new best move
+ // Drop the easy move if differs from the new best move
if (ss[0].pv[0] != EasyMove)
EasyMove = MOVE_NONE;
&& abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100)
stopSearch = true;
- // Stop search early if one move seems to be much better than the rest
+ // Stop search early if one move seems to be much better than the others
int64_t nodes = TM.nodes_searched();
if ( Iteration >= 8
&& EasyMove == ss[0].pv[0]
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))
ss[0].pv[0] = rml.get_move(0);
ss[0].pv[1] = MOVE_NONE;
}
+
+ assert(ss[0].pv[0] != MOVE_NONE);
+
cout << "bestmove " << ss[0].pv[0];
+
if (ss[0].pv[1] != MOVE_NONE)
cout << " ponder " << ss[0].pv[1];
StateInfo st;
p.do_move(ss[0].pv[0], st);
- LogFile << "\nPonder move: " << move_to_san(p, ss[0].pv[1]) << endl;
+ LogFile << "\nPonder move: "
+ << move_to_san(p, ss[0].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[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
+ EvalInfo ei;
+ 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();
+
+ // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME)
+ // Step 2. Check for aborted search (omitted at root, because we do not initialize root node)
+ // 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
+ if (!isCheck)
+ ss[0].eval = evaluate(pos, ei, 0);
+ else
+ ss[0].eval = VALUE_NONE; // HACK because we do not initialize root node
- while (1) // Fail low loop
+ // 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.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();
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);
+
+ // Step 11. Decide the new search depth
depth = (Iteration - 2) * OnePly + InitialDepth;
ext = extension(pos, move, true, 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;
+ // Full depth PV search, done on first move or after a fail high
value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
}
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 * OnePly
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move))
{
- ss[0].reduction = pv_reduction(depth, RootMoveNumber - MultiPV + 1);
+ ss[0].reduction = pv_reduction(depth, i - MultiPV + 2);
if (ss[0].reduction)
{
+ // Reduced depth non-pv search using alpha as upperbound
value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0);
doFullDepthSearch = (value > alpha);
}
}
+ // Step 15. Full depth search
if (doFullDepthSearch)
{
+ // Full depth non-pv search using alpha as upperbound
ss[0].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+ // 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);
}
}
+ // 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));
-
- 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, ss, 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
break;
// Remember beta-cutoff and searched nodes counts for this move. The
- // info is used to sort the root moves at the next iteration.
+ // info is used to sort the root moves for 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);
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
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;
-
- if (UseLogFile)
- {
- ValueType type = (value >= beta ? VALUE_TYPE_LOWER
- : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
+ // Print information to the standard output
+ print_pv_info(pos, ss, alpha, beta, value);
- 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;
}
{
cout << "info multipv " << j + 1
<< " score " << value_to_string(rml.get_move_score(j))
- << " depth " << ((j <= i)? Iteration : Iteration - 1)
+ << " depth " << (j <= i ? Iteration : Iteration - 1)
<< " time " << current_search_time()
<< " nodes " << TM.nodes_searched()
<< " nps " << nps()
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;
}
// 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
+ if ( depth >= SingularExtensionDepthAtPVNodes
&& tte
&& move == tte->move()
&& ext < OnePly
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
// if the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
- if ( depth >= 3*OnePly
+ if ( depth >= 3 * OnePly
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
&& !AbortSearch
&& !TM.thread_should_stop(threadID)
&& TM.split(pos, ss, ply, &alpha, beta, &bestValue,
- depth, &moveCount, &mp, threadID, true))
+ depth, mateThreat, &moveCount, &mp, threadID, true))
break;
}
Value rbeta = beta - razor_margin(depth);
Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
if (v < rbeta)
- return v; //FIXME: Logically should be: return (v + razor_margin(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
// 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
- && refinedValue - futility_margin(depth, 0) >= beta)
+ // the score by more than futility_margin(depth) if we do a null move.
+ if ( allowNullmove
+ && depth < RazorDepth
+ && !isCheck
+ && !value_is_mate(beta)
+ && ok_to_do_nullmove(pos)
+ && refinedValue >= beta + futility_margin(depth, 0))
return refinedValue - futility_margin(depth, 0);
// Step 8. Null move search with verification search
{
ss[ply].currentMove = MOVE_NULL;
- pos.do_null_move(st);
-
// Null move dynamic reduction based on depth
int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0);
if (refinedValue - beta > PawnValueMidgame)
R++;
+ pos.do_null_move(st);
+
nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
pos.undo_null_move();
if (nullValue >= beta)
{
+ // Do not return unproven mate scores
+ if (nullValue >= value_mate_in(PLY_MAX))
+ nullValue = beta;
+
if (depth < 6 * OnePly)
- return beta;
+ return nullValue;
// Do zugzwang verification search
Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
if (v >= beta)
- return beta;
+ 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
// Loop through all legal moves until no moves remain or a beta cutoff occurs
// 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[ply], beta);
CheckInfo ci(pos);
while ( bestValue < beta
// 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
+ if ( depth >= SingularExtensionDepthAtNonPVNodes
&& tte
&& move == tte->move()
&& !excludedMove // Do not allow recursive single-reply search
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
continue;
// Value based pruning
- Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); //FIXME: We are ignoring condition: depth >= 3*OnePly, BUG??
+ Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly
futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount)
+ H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
&& !AbortSearch
&& !TM.thread_should_stop(threadID)
&& TM.split(pos, ss, ply, NULL, beta, &bestValue,
- depth, &moveCount, &mp, threadID, false))
+ depth, mateThreat, &moveCount, &mp, threadID, false))
break;
}
// splitting, we don't have to repeat all this work in sp_search(). 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.
- // FIXME: We are currently ignoring mateThreat flag here
void sp_search(SplitPoint* sp, int threadID) {
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
- ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
newDepth = sp->depth - OnePly + ext;
// Update current move
// 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.
- // FIXME: We are ignoring mateThreat flag!
void sp_search_pv(SplitPoint* sp, int threadID) {
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
newDepth = sp->depth - OnePly + ext;
// Update current move
if (PonderSearch)
return;
- bool stillAtFirstMove = RootMoveNumber == 1
+ bool stillAtFirstMove = FirstRootMove
&& !AspirationFailLow
&& t > MaxSearchTime + ExtraSearchTime;
int t = current_search_time();
PonderSearch = false;
- bool stillAtFirstMove = RootMoveNumber == 1
+ bool stillAtFirstMove = FirstRootMove
&& !AspirationFailLow
&& t > MaxSearchTime + ExtraSearchTime;
}
+ // 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, SearchStack ss[], Value alpha, Value beta, Value value) {
+
+ 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));
+
+ LogFile << pretty_pv(pos, current_search_time(), Iteration,
+ TM.nodes_searched(), value, type, ss[0].pv) << endl;
+ }
+ }
+
+
// init_thread() is the function which is called when a new thread is
// launched. It simply calls the idle_loop() function with the supplied
// threadID. There are two versions of this function; one for POSIX
DWORD WINAPI init_thread(LPVOID threadID) {
TM.idle_loop(*(int*)threadID, NULL);
- return NULL;
+ return 0;
}
#endif
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
// Initialize global locks
lock_init(&MPLock, NULL);
+ lock_init(&WaitLock, NULL);
+
+#if !defined(_MSC_VER)
+ pthread_cond_init(&WaitCond, NULL);
+#else
+ for (i = 0; i < MAX_THREADS; i++)
+ SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
+#endif
// Initialize SplitPointStack locks
for (i = 0; i < MAX_THREADS; i++)
lock_init(&(SplitPointStack[i][j].lock), NULL);
}
-#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
-
// 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)
for (int i = 0; i < MAX_THREADS; i++)
for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
lock_destroy(&(SplitPointStack[i][j].lock));
+
+ lock_destroy(&WaitLock);
+ lock_destroy(&MPLock);
}
bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply,
Value* alpha, const Value beta, Value* bestValue,
- Depth depth, int* moves, MovePicker* mp, int master, bool pvNode) {
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) {
assert(p.is_ok());
assert(sstck != NULL);
splitPoint->stopRequest = false;
splitPoint->ply = ply;
splitPoint->depth = depth;
+ splitPoint->mateThreat = mateThreat;
splitPoint->alpha = pvNode ? *alpha : beta - 1;
splitPoint->beta = beta;
splitPoint->pvNode = pvNode;
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);
projects / stockfish / blobdiff