/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008 Marco Costalba
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
- Glaurung is distributed in the hope that it will be useful,
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
////
#include <cassert>
-#include <cstdio>
#include <fstream>
#include <iostream>
#include <sstream>
/// Types
+ // The BetaCounterType class is used to order moves at ply one.
+ // Apart for the first one that has its score, following moves
+ // normally have score -VALUE_INFINITE, so are ordered according
+ // to the number of beta cutoffs occurred under their subtree during
+ // the last iteration.
+
+ struct BetaCounterType {
+
+ BetaCounterType();
+ void clear();
+ void add(Color us, Depth d, int threadID);
+ void read(Color us, int64_t& our, int64_t& their);
+
+ int64_t hits[THREAD_MAX][2];
+ };
+
+
// The RootMove class is used for moves at the root at the tree. For each
// root move, we store a score, a node count, and a PV (really a refutation
// in the case of moves which fail low).
Value score;
int64_t nodes, cumulativeNodes;
Move pv[PLY_MAX_PLUS_2];
+ int64_t ourBeta, theirBeta;
};
public:
RootMoveList(Position &pos, Move searchMoves[]);
- Move get_move(int moveNum) const;
- Value get_move_score(int moveNum) const;
- void set_move_score(int moveNum, Value score);
- void set_move_nodes(int moveNum, int64_t nodes);
+ inline Move get_move(int moveNum) const;
+ inline Value get_move_score(int moveNum) const;
+ inline void set_move_score(int moveNum, Value score);
+ inline void set_move_nodes(int moveNum, int64_t nodes);
+ inline void set_beta_counters(int moveNum, int64_t our, int64_t their);
void set_move_pv(int moveNum, const Move pv[]);
- Move get_move_pv(int moveNum, int i) const;
- int64_t get_move_cumulative_nodes(int moveNum) const;
- int move_count() const;
+ inline Move get_move_pv(int moveNum, int i) const;
+ inline int64_t get_move_cumulative_nodes(int moveNum) const;
+ inline int move_count() const;
Move scan_for_easy_move() const;
- void sort();
+ inline void sort();
void sort_multipv(int n);
private:
// Depth limit for selective search:
Depth SelectiveDepth = 7*OnePly;
+ // Use dynamic LMR?
+ const bool UseDynamicLMR = false;
+
// Use internal iterative deepening?
const bool UseIIDAtPVNodes = true;
const bool UseIIDAtNonPVNodes = false;
// when the static evaluation is at most IIDMargin below beta.
const Value IIDMargin = Value(0x100);
- // Use easy moves?
- const bool UseEasyMove = true;
-
// Easy move margin. An easy move candidate must be at least this much
// better than the second best move.
const Value EasyMoveMargin = Value(0x200);
bool UseQSearchFutilityPruning = true;
bool UseFutilityPruning = true;
- // Margins for futility pruning in the quiescence search, at frontier
- // nodes, and at pre-frontier nodes:
- Value FutilityMargin0 = Value(0x80);
- Value FutilityMargin1 = Value(0x100);
- Value FutilityMargin2 = Value(0x300);
+ // Margins for futility pruning in the quiescence search, and at frontier
+ // and near frontier nodes
+ Value FutilityMarginQS = Value(0x80);
+ Value FutilityMargins[6] = { Value(0x100), Value(0x200), Value(0x250),
+ Value(0x2A0), Value(0x340), Value(0x3A0) };
// Razoring
+ const bool RazorAtDepthOne = false;
Depth RazorDepth = 4*OnePly;
Value RazorMargin = Value(0x300);
+ // Last seconds noise filtering (LSN)
+ bool UseLSNFiltering = false;
+ bool looseOnTime = false;
+ int LSNTime = 4 * 1000; // In milliseconds
+ Value LSNValue = Value(0x200);
+
// Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
Depth CheckExtension[2] = {OnePly, OnePly};
Depth SingleReplyExtension[2] = {OnePly / 2, OnePly / 2};
Depth PawnEndgameExtension[2] = {OnePly, OnePly};
Depth MateThreatExtension[2] = {Depth(0), Depth(0)};
- // Search depth at iteration 1:
+ // Search depth at iteration 1
const Depth InitialDepth = OnePly /*+ OnePly/2*/;
// Node counters
int NodesSincePoll;
int NodesBetweenPolls = 30000;
- // Iteration counter:
+ // Iteration counters
int Iteration;
+ BetaCounterType BetaCounter;
// Scores and number of times the best move changed for each iteration:
Value ValueByIteration[PLY_MAX_PLUS_2];
int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
- // MultiPV mode:
+ // MultiPV mode
int MultiPV = 1;
// Time managment variables
int SearchStartTime;
int MaxNodes, MaxDepth;
int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
- Move BestRootMove, PonderMove, EasyMove;
+ Move EasyMove;
int RootMoveNumber;
bool InfiniteSearch;
bool PonderSearch;
/// Functions
- void id_loop(const Position &pos, Move searchMoves[]);
+ Value id_loop(const Position &pos, Move searchMoves[]);
Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml);
Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta,
Depth depth, int ply, int threadID);
Depth depth, int ply, int threadID);
void sp_search(SplitPoint *sp, int threadID);
void sp_search_pv(SplitPoint *sp, int threadID);
- void init_search_stack(SearchStack ss[]);
void init_node(const Position &pos, SearchStack ss[], int ply, int threadID);
void update_pv(SearchStack ss[], int ply);
void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply);
bool connected_moves(const Position &pos, Move m1, Move m2);
- Depth extension(const Position &pos, Move m, bool pvNode, bool check,
- bool singleReply, bool mateThreat);
+ bool value_is_mate(Value value);
+ bool move_is_killer(Move m, const SearchStack& ss);
+ Depth extension(const Position &pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
bool ok_to_do_nullmove(const Position &pos);
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d);
+ bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
+ bool ok_to_history(const Position &pos, Move m);
+ void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount);
+ void update_killers(Move m, SearchStack& ss);
bool fail_high_ply_1();
int current_search_time();
bool thread_is_available(int slave, int master);
bool idle_thread_exists(int master);
bool split(const Position &pos, SearchStack *ss, int ply,
- Value *alpha, Value *beta, Value *bestValue, Depth depth,
- int *moves, MovePicker *mp, Bitboard dcCandidates, int master,
- bool pvNode);
+ Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
+ MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
void wake_sleeping_threads();
#if !defined(_MSC_VER)
History H; // Should be made local?
+// The empty search stack
+SearchStack EmptySearchStack;
+
+
+// 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);
+ currentMoveCaptureValue = Value(0);
+}
+
+void SearchStack::initKillers() {
+
+ mateKiller = MOVE_NONE;
+ for (int i = 0; i < KILLER_MAX; i++)
+ killers[i] = MOVE_NONE;
+}
+
////
//// Functions
////
-/// think() is the external interface to Glaurung's search, and is called when
+/// think() is the external interface to Stockfish's search, and is called when
/// the program receives the UCI 'go' command. It initializes various
/// search-related global variables, and calls root_search()
-void think(const Position &pos, bool infinite, bool ponder, int time,
- int increment, int movesToGo, int maxDepth, int maxNodes,
- int maxTime, Move searchMoves[]) {
-
- // Look for a book move:
- if(!infinite && !ponder && get_option_value_bool("OwnBook")) {
- Move bookMove;
- if(get_option_value_string("Book File") != OpeningBook.file_name()) {
- OpeningBook.close();
- OpeningBook.open("book.bin");
- }
- bookMove = OpeningBook.get_move(pos);
- if(bookMove != MOVE_NONE) {
- std::cout << "bestmove " << bookMove << std::endl;
- return;
- }
+void 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[]) {
+
+ // Look for a book move
+ if (!infinite && !ponder && get_option_value_bool("OwnBook"))
+ {
+ Move bookMove;
+ if (get_option_value_string("Book File") != OpeningBook.file_name())
+ {
+ OpeningBook.close();
+ OpeningBook.open("book.bin");
+ }
+ bookMove = OpeningBook.get_move(pos);
+ if (bookMove != MOVE_NONE)
+ {
+ std::cout << "bestmove " << bookMove << std::endl;
+ return;
+ }
}
- // Initialize global search variables:
+ // Initialize global search variables
Idle = false;
SearchStartTime = get_system_time();
- BestRootMove = MOVE_NONE;
- PonderMove = MOVE_NONE;
EasyMove = MOVE_NONE;
- for(int i = 0; i < THREAD_MAX; i++) {
- Threads[i].nodes = 0ULL;
- Threads[i].failHighPly1 = false;
+ for (int i = 0; i < THREAD_MAX; i++)
+ {
+ Threads[i].nodes = 0ULL;
+ Threads[i].failHighPly1 = false;
}
NodesSincePoll = 0;
InfiniteSearch = infinite;
Problem = false;
ExactMaxTime = maxTime;
- // Read UCI option values:
+ // Read UCI option values
TT.set_size(get_option_value_int("Hash"));
- if(button_was_pressed("Clear Hash"))
- TT.clear();
- PonderingEnabled = get_option_value_int("Ponder");
+ if (button_was_pressed("Clear Hash"))
+ TT.clear();
+
+ 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[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
+
SingleReplyExtension[1] = Depth(get_option_value_int("Single Reply Extension (PV nodes)"));
- SingleReplyExtension[0] =
- Depth(get_option_value_int("Single Reply 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)"));
-
- LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
- LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
- ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
+ SingleReplyExtension[0] = Depth(get_option_value_int("Single Reply 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)"));
+
+ LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
+ LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
+ ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
SelectiveDepth = get_option_value_int("Selective Plies") * 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);
-
- UseQSearchFutilityPruning =
- get_option_value_bool("Futility Pruning (Quiescence Search)");
- UseFutilityPruning =
- get_option_value_bool("Futility Pruning (Main Search)");
-
- FutilityMargin0 =
- value_from_centipawns(get_option_value_int("Futility Margin 0"));
- FutilityMargin1 =
- value_from_centipawns(get_option_value_int("Futility Margin 1"));
- FutilityMargin2 =
- value_from_centipawns(get_option_value_int("Futility Margin 2"));
+ if (UseLogFile)
+ LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
+
+ UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
+ UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
+
+ FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)"));
+ int fmScale = get_option_value_int("Futility Margin Scale Factor (Main Search)");
+ for (int i = 0; i < 6; i++)
+ FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly;
RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin"));
+ UseLSNFiltering = get_option_value_bool("LSN filtering");
+ LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
+ LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));
+
MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
- MaxThreadsPerSplitPoint =
- get_option_value_int("Maximum Number of Threads per Split Point");
+ MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
read_weights(pos.side_to_move());
int newActiveThreads = get_option_value_int("Threads");
- if(newActiveThreads != ActiveThreads) {
- ActiveThreads = newActiveThreads;
- init_eval(ActiveThreads);
- }
-
- // Write information to search log file:
- if(UseLogFile) {
- LogFile << "Searching: " << pos.to_fen() << '\n';
- LogFile << "infinite: " << infinite << " ponder: " << ponder
- << " time: " << time << " increment: " << increment
- << " moves to go: " << movesToGo << '\n';
+ if (newActiveThreads != ActiveThreads)
+ {
+ ActiveThreads = newActiveThreads;
+ init_eval(ActiveThreads);
}
// Wake up sleeping threads:
wake_sleeping_threads();
- for(int i = 1; i < ActiveThreads; i++)
- assert(thread_is_available(i, 0));
+ for (int i = 1; i < ActiveThreads; i++)
+ assert(thread_is_available(i, 0));
// Set thinking time:
- if(!movesToGo) { // Sudden death time control
- if(increment) {
- MaxSearchTime = time / 30 + increment;
- AbsoluteMaxSearchTime = Max(time / 4, increment - 100);
- }
- else { // Blitz game without increment
- MaxSearchTime = time / 40;
- AbsoluteMaxSearchTime = time / 8;
- }
+ int myTime = time[side_to_move];
+ int myIncrement = increment[side_to_move];
+
+ 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 = time / 2;
- AbsoluteMaxSearchTime = Min(time / 2, time - 500);
- }
- else {
- MaxSearchTime = time / Min(movesToGo, 20);
- AbsoluteMaxSearchTime = Min((4 * time) / movesToGo, time / 3);
- }
+ else // (x moves) / (y minutes)
+ {
+ if (movesToGo == 1)
+ {
+ MaxSearchTime = myTime / 2;
+ AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500);
+ } else {
+ MaxSearchTime = myTime / Min(movesToGo, 20);
+ AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
+ }
}
- if(PonderingEnabled) {
- MaxSearchTime += MaxSearchTime / 4;
- MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
+
+ if (PonderingEnabled)
+ {
+ MaxSearchTime += MaxSearchTime / 4;
+ MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
}
// Fixed depth or fixed number of nodes?
MaxDepth = maxDepth;
- if(MaxDepth)
- InfiniteSearch = true; // HACK
+ if (MaxDepth)
+ InfiniteSearch = true; // HACK
MaxNodes = maxNodes;
- if(MaxNodes) {
- NodesBetweenPolls = Min(MaxNodes, 30000);
- InfiniteSearch = true; // HACK
+ if (MaxNodes)
+ {
+ NodesBetweenPolls = Min(MaxNodes, 30000);
+ InfiniteSearch = true; // HACK
}
else
- NodesBetweenPolls = 30000;
+ NodesBetweenPolls = 30000;
+
+
+ // Write information to search log file:
+ if (UseLogFile)
+ LogFile << "Searching: " << pos.to_fen() << std::endl
+ << "infinite: " << infinite
+ << " ponder: " << ponder
+ << " time: " << myTime
+ << " increment: " << myIncrement
+ << " moves to go: " << movesToGo << std::endl;
+
// We're ready to start thinking. Call the iterative deepening loop
// function:
- id_loop(pos, searchMoves);
+ if (!looseOnTime)
+ {
+ Value v = id_loop(pos, searchMoves);
+ looseOnTime = ( UseLSNFiltering
+ && myTime < LSNTime
+ && myIncrement == 0
+ && v < -LSNValue);
+ }
+ else
+ {
+ looseOnTime = false; // reset for next match
+ while (SearchStartTime + myTime + 1000 > get_system_time())
+ ; // wait here
+ id_loop(pos, searchMoves); // to fail gracefully
+ }
- if(UseLogFile)
- LogFile.close();
+ if (UseLogFile)
+ LogFile.close();
- if(Quit) {
- OpeningBook.close();
- stop_threads();
- quit_eval();
- exit(0);
+ if (Quit)
+ {
+ OpeningBook.close();
+ stop_threads();
+ quit_eval();
+ exit(0);
}
-
Idle = true;
}
/// objects.
void init_threads() {
+
volatile int i;
+
#if !defined(_MSC_VER)
pthread_t pthread[1];
#endif
- for(i = 0; i < THREAD_MAX; i++)
- Threads[i].activeSplitPoints = 0;
+ for (i = 0; i < THREAD_MAX; i++)
+ Threads[i].activeSplitPoints = 0;
// Initialize global locks:
lock_init(&MPLock, NULL);
pthread_mutex_init(&WaitLock, NULL);
pthread_cond_init(&WaitCond, NULL);
#else
- for(i = 0; i < THREAD_MAX; i++)
- SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
+ for (i = 0; i < THREAD_MAX; i++)
+ SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
#endif
- // All threads except the main thread should be initialized to idle state:
- for(i = 1; i < THREAD_MAX; i++) {
- Threads[i].stop = false;
- Threads[i].workIsWaiting = false;
- Threads[i].idle = true;
- Threads[i].running = false;
+ // All threads except the main thread should be initialized to idle state
+ for (i = 1; i < THREAD_MAX; i++)
+ {
+ Threads[i].stop = false;
+ Threads[i].workIsWaiting = false;
+ Threads[i].idle = true;
+ Threads[i].running = false;
}
- // Launch the helper threads:
- for(i = 1; i < THREAD_MAX; i++) {
+ // Launch the helper threads
+ for(i = 1; i < THREAD_MAX; i++)
+ {
#if !defined(_MSC_VER)
- pthread_create(pthread, NULL, init_thread, (void*)(&i));
+ pthread_create(pthread, NULL, init_thread, (void*)(&i));
#else
- {
DWORD iID[1];
CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID);
- }
#endif
- // Wait until the thread has finished launching:
- while(!Threads[i].running);
+ // Wait until the thread has finished launching:
+ while (!Threads[i].running);
}
+
+ // Init also the empty search stack
+ EmptySearchStack.init(0);
+ EmptySearchStack.initKillers();
}
/// helper threads exit cleanly.
void stop_threads() {
+
ActiveThreads = THREAD_MAX; // HACK
Idle = false; // HACK
wake_sleeping_threads();
AllThreadsShouldExit = true;
- for(int i = 1; i < THREAD_MAX; i++) {
- Threads[i].stop = true;
- while(Threads[i].running);
+ for (int i = 1; i < THREAD_MAX; i++)
+ {
+ Threads[i].stop = true;
+ while(Threads[i].running);
}
destroy_split_point_stack();
}
/// the current search.
int64_t nodes_searched() {
+
int64_t result = 0ULL;
- for(int i = 0; i < ActiveThreads; i++)
- result += Threads[i].nodes;
+ for (int i = 0; i < ActiveThreads; i++)
+ result += Threads[i].nodes;
return result;
}
// been consumed, the user stops the search, or the maximum search depth is
// reached.
- void id_loop(const Position &pos, Move searchMoves[]) {
+ Value id_loop(const Position &pos, Move searchMoves[]) {
+
Position p(pos);
SearchStack ss[PLY_MAX_PLUS_2];
// Initialize
TT.new_search();
H.clear();
- init_search_stack(ss);
-
+ for (int i = 0; i < 3; i++)
+ {
+ ss[i].init(i);
+ ss[i].initKillers();
+ }
ValueByIteration[0] = Value(0);
ValueByIteration[1] = rml.get_move_score(0);
Iteration = 1;
EasyMove = rml.scan_for_easy_move();
// Iterative deepening loop
- while(!AbortSearch && Iteration < PLY_MAX) {
-
- // Initialize iteration
- rml.sort();
- Iteration++;
- BestMoveChangesByIteration[Iteration] = 0;
- if(Iteration <= 5)
- ExtraSearchTime = 0;
-
- std::cout << "info depth " << Iteration << std::endl;
-
- // Search to the current depth
- ValueByIteration[Iteration] = root_search(p, ss, rml);
-
- // Erase the easy move if it differs from the new best move
- if(ss[0].pv[0] != EasyMove)
- EasyMove = MOVE_NONE;
-
- Problem = false;
-
- if(!InfiniteSearch) {
- // Time to stop?
- bool stopSearch = false;
-
- // Stop search early if there is only a single legal move:
- if(Iteration >= 6 && rml.move_count() == 1)
- stopSearch = true;
-
- // Stop search early when the last two iterations returned a mate
- // score:
- if(Iteration >= 6
- && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100
- && 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 = 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)))
- 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);
-
- // 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)
- stopSearch = true;
-
- if(stopSearch) {
- if(!PonderSearch)
- break;
- else
- StopOnPonderhit = true;
- }
- }
+ while (!AbortSearch && Iteration < PLY_MAX)
+ {
+ // Initialize iteration
+ rml.sort();
+ Iteration++;
+ BestMoveChangesByIteration[Iteration] = 0;
+ if (Iteration <= 5)
+ ExtraSearchTime = 0;
- // Write PV to transposition table, in case the relevant entries have
- // been overwritten during the search:
- TT.insert_pv(p, ss[0].pv);
+ std::cout << "info depth " << Iteration << std::endl;
- if(MaxDepth && Iteration >= MaxDepth)
- break;
+ // Search to the current depth
+ ValueByIteration[Iteration] = root_search(p, ss, rml);
+
+ // Erase the easy move if it differs from the new best move
+ if (ss[0].pv[0] != EasyMove)
+ EasyMove = MOVE_NONE;
+
+ Problem = false;
+
+ if (!InfiniteSearch)
+ {
+ // Time to stop?
+ bool stopSearch = false;
+
+ // Stop search early if there is only a single legal move:
+ if (Iteration >= 6 && rml.move_count() == 1)
+ stopSearch = true;
+
+ // Stop search early when the last two iterations returned a mate score
+ if ( Iteration >= 6
+ && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100
+ && 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 = 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)))
+ 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);
+
+ // 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)
+ stopSearch = true;
+
+ if (stopSearch)
+ {
+ if (!PonderSearch)
+ break;
+ else
+ StopOnPonderhit = true;
+ }
+ }
+ // Write PV to transposition table, in case the relevant entries have
+ // been overwritten during the search:
+ TT.insert_pv(p, ss[0].pv);
+
+ if (MaxDepth && Iteration >= MaxDepth)
+ break;
}
rml.sort();
// If we are pondering, we shouldn't print the best move before we
// are told to do so
- if(PonderSearch)
- wait_for_stop_or_ponderhit();
+ if (PonderSearch)
+ wait_for_stop_or_ponderhit();
else
- // Print final search statistics
- std::cout << "info nodes " << nodes_searched() << " nps " << nps()
- << " time " << current_search_time()
- << " hashfull " << TT.full() << std::endl;
-
- // Print the best move and the ponder move to the standard output:
+ // Print final search statistics
+ std::cout << "info nodes " << nodes_searched()
+ << " nps " << nps()
+ << " time " << current_search_time()
+ << " hashfull " << TT.full() << std::endl;
+
+ // Print the best move and the ponder move to the standard output
+ if (ss[0].pv[0] == MOVE_NONE)
+ {
+ ss[0].pv[0] = rml.get_move(0);
+ ss[0].pv[1] = MOVE_NONE;
+ }
std::cout << "bestmove " << ss[0].pv[0];
- if(ss[0].pv[1] != MOVE_NONE)
- std::cout << " ponder " << ss[0].pv[1];
+ if (ss[0].pv[1] != MOVE_NONE)
+ std::cout << " ponder " << ss[0].pv[1];
+
std::cout << std::endl;
- if(UseLogFile) {
- UndoInfo u;
- LogFile << "Nodes: " << nodes_searched() << '\n';
- LogFile << "Nodes/second: " << nps() << '\n';
- LogFile << "Best move: " << move_to_san(p, ss[0].pv[0]) << '\n';
- p.do_move(ss[0].pv[0], u);
- LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1]) << '\n';
- LogFile << std::endl;
+ if (UseLogFile)
+ {
+ if (dbg_show_mean)
+ dbg_print_mean(LogFile);
+
+ if (dbg_show_hit_rate)
+ dbg_print_hit_rate(LogFile);
+
+ StateInfo st;
+ LogFile << "Nodes: " << nodes_searched() << std::endl
+ << "Nodes/second: " << nps() << std::endl
+ << "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl;
+
+ p.do_move(ss[0].pv[0], st);
+ LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1])
+ << std::endl << std::endl;
}
+ return rml.get_move_score(0);
}
// and prints some information to the standard output.
Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml) {
- Value alpha = -VALUE_INFINITE, beta = VALUE_INFINITE, value;
+
+ Value alpha = -VALUE_INFINITE;
+ Value beta = VALUE_INFINITE, value;
Bitboard dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
- // Loop through all the moves in the root move list:
- for(int i = 0; i < rml.move_count() && !AbortSearch; i++) {
- int64_t nodes;
- Move move;
- UndoInfo u;
- Depth ext, newDepth;
-
- RootMoveNumber = i + 1;
- FailHigh = false;
-
- // Remember the node count before the move is searched. The node counts
- // are used to sort the root moves at the next iteration.
- nodes = 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);
- if(current_search_time() >= 1000)
- std::cout << "info currmove " << move
- << " currmovenumber " << i + 1 << std::endl;
-
- // Decide search depth for this move:
- ext = extension(pos, move, true, pos.move_is_check(move), false, false);
- newDepth = (Iteration-2)*OnePly + ext + InitialDepth;
-
- // Make the move, and search it.
- pos.do_move(move, u, dcCandidates);
-
- if(i < MultiPV) {
- value = -search_pv(pos, ss, -beta, VALUE_INFINITE, newDepth, 1, 0);
- // If the value has dropped a lot compared to the last iteration,
- // set the boolean variable Problem to true. This variable is used
- // for time managment: When Problem is true, we try to complete the
- // current iteration before playing a move.
- Problem = (Iteration >= 2 &&
- value <= ValueByIteration[Iteration-1] - ProblemMargin);
- if(Problem && StopOnPonderhit)
- StopOnPonderhit = false;
- }
- else {
- value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
- if(value > alpha) {
- // Fail high! Set the boolean variable FailHigh to true, and
- // re-search the move with a big window. The variable FailHigh is
- // used for time managment: We try to avoid aborting the search
- // prematurely during a fail high research.
- FailHigh = true;
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
- }
- }
+ // Loop through all the moves in the root move list
+ for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
+ {
+ int64_t nodes;
+ Move move;
+ StateInfo st;
+ Depth ext, newDepth;
- pos.undo_move(move, u);
+ RootMoveNumber = i + 1;
+ FailHigh = false;
- // Finished searching the move. If AbortSearch is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we break out of the loop without updating the best
- // move and/or PV:
- if(AbortSearch)
- break;
+ // Remember the node count before the move is searched. The node counts
+ // are used to sort the root moves at the next iteration.
+ nodes = nodes_searched();
- // Remember the node count for this move. The node counts are used to
- // sort the root moves at the next iteration.
- rml.set_move_nodes(i, nodes_searched() - nodes);
+ // Reset beta cut-off counters
+ BetaCounter.clear();
- assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+ // 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);
+ if (current_search_time() >= 1000)
+ std::cout << "info currmove " << move
+ << " currmovenumber " << i + 1 << std::endl;
- if(value <= alpha && i >= MultiPV)
- rml.set_move_score(i, -VALUE_INFINITE);
- else {
- // New best move!
-
- // Update PV:
- rml.set_move_score(i, value);
- update_pv(ss, 0);
- rml.set_move_pv(i, ss[0].pv);
-
- if(MultiPV == 1) {
- // We record how often the best move has been changed in each
- // iteration. This information is used for time managment: When
- // the best move changes frequently, we allocate some more time.
- if(i > 0)
- BestMoveChangesByIteration[Iteration]++;
-
- // Print search information to the standard output:
- std::cout << "info depth " << Iteration
- << " score " << value_to_string(value)
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
- for(int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
- std::cout << ss[0].pv[j] << " ";
- std::cout << std::endl;
-
- if(UseLogFile)
- LogFile << pretty_pv(pos, current_search_time(), Iteration,
- nodes_searched(), value, ss[0].pv)
- << std::endl;
-
- alpha = value;
-
- // Reset the global variable Problem to false if the value isn't too
- // far below the final value from the last iteration.
- if(value > ValueByIteration[Iteration - 1] - NoProblemMargin)
- Problem = false;
+ // Decide search depth for this move
+ bool dangerous;
+ ext = extension(pos, move, true, pos.move_is_capture(move), pos.move_is_check(move), false, false, &dangerous);
+ newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
+
+ // Make the move, and search it
+ pos.do_move(move, st, dcCandidates);
+
+ if (i < MultiPV)
+ {
+ value = -search_pv(pos, ss, -beta, VALUE_INFINITE, newDepth, 1, 0);
+ // If the value has dropped a lot compared to the last iteration,
+ // set the boolean variable Problem to true. This variable is used
+ // for time managment: When Problem is true, we try to complete the
+ // current iteration before playing a move.
+ Problem = (Iteration >= 2 && value <= ValueByIteration[Iteration-1] - ProblemMargin);
+
+ if (Problem && StopOnPonderhit)
+ StopOnPonderhit = false;
}
- else { // MultiPV > 1
- rml.sort_multipv(i);
- for(int j = 0; j < Min(MultiPV, rml.move_count()); j++) {
- int k;
- std::cout << "info multipv " << j + 1
- << " score " << value_to_string(rml.get_move_score(j))
- << " depth " << ((j <= i)? Iteration : Iteration - 1)
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
- for(k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
- std::cout << rml.get_move_pv(j, k) << " ";
- std::cout << std::endl;
- }
- alpha = rml.get_move_score(Min(i, MultiPV-1));
+ else
+ {
+ value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+ if (value > alpha)
+ {
+ // Fail high! Set the boolean variable FailHigh to true, and
+ // re-search the move with a big window. The variable FailHigh is
+ // used for time managment: We try to avoid aborting the search
+ // prematurely during a fail high research.
+ FailHigh = true;
+ value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+ }
+ }
+
+ pos.undo_move(move);
+
+ // Finished searching the move. If AbortSearch is true, the search
+ // was aborted because the user interrupted the search or because we
+ // ran out of time. In this case, the return value of the search cannot
+ // be trusted, and we break out of the loop without updating the best
+ // move and/or PV:
+ if (AbortSearch)
+ break;
+
+ // Remember the node count for this move. The node counts are used to
+ // sort the root moves at the next iteration.
+ rml.set_move_nodes(i, nodes_searched() - nodes);
+
+ // Remember the beta-cutoff statistics
+ int64_t our, their;
+ BetaCounter.read(pos.side_to_move(), our, their);
+ rml.set_beta_counters(i, our, their);
+
+ assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+
+ if (value <= alpha && i >= MultiPV)
+ rml.set_move_score(i, -VALUE_INFINITE);
+ else
+ {
+ // New best move!
+
+ // Update PV
+ rml.set_move_score(i, value);
+ update_pv(ss, 0);
+ rml.set_move_pv(i, ss[0].pv);
+
+ if (MultiPV == 1)
+ {
+ // We record how often the best move has been changed in each
+ // iteration. This information is used for time managment: When
+ // the best move changes frequently, we allocate some more time.
+ if (i > 0)
+ BestMoveChangesByIteration[Iteration]++;
+
+ // Print search information to the standard output:
+ std::cout << "info depth " << Iteration
+ << " score " << value_to_string(value)
+ << " time " << current_search_time()
+ << " nodes " << nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
+ std::cout << ss[0].pv[j] << " ";
+
+ std::cout << std::endl;
+
+ if (UseLogFile)
+ LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv)
+ << std::endl;
+
+ alpha = value;
+
+ // Reset the global variable Problem to false if the value isn't too
+ // far below the final value from the last iteration.
+ if (value > ValueByIteration[Iteration - 1] - NoProblemMargin)
+ Problem = false;
+ }
+ else // MultiPV > 1
+ {
+ rml.sort_multipv(i);
+ for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
+ {
+ int k;
+ std::cout << "info multipv " << j + 1
+ << " score " << value_to_string(rml.get_move_score(j))
+ << " depth " << ((j <= i)? Iteration : Iteration - 1)
+ << " time " << current_search_time()
+ << " nodes " << nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
+ std::cout << rml.get_move_pv(j, k) << " ";
+
+ std::cout << std::endl;
+ }
+ alpha = rml.get_move_score(Min(i, MultiPV-1));
+ }
}
- }
}
return alpha;
}
Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta,
Depth depth, int ply, int threadID) {
+
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
+ if (depth < OnePly)
+ return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
- Value oldAlpha = alpha;
-
- if(AbortSearch || thread_should_stop(threadID))
- return Value(0);
+ init_node(pos, ss, ply, threadID);
- if(depth < OnePly)
- return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
+ // After init_node() that calls poll()
+ if (AbortSearch || thread_should_stop(threadID))
+ return Value(0);
- init_node(pos, ss, ply, threadID);
+ if (pos.is_draw())
+ return VALUE_DRAW;
- if(pos.is_draw())
- return VALUE_DRAW;
+ EvalInfo ei;
- if(ply >= PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ if (ply >= PLY_MAX - 1)
+ return evaluate(pos, ei, threadID);
// Mate distance pruning
+ Value oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
beta = Min(value_mate_in(ply+1), beta);
- if(alpha >= beta)
- return alpha;
+ if (alpha >= beta)
+ return alpha;
- // Transposition table lookup. At PV nodes, we don't use the TT for
+ // Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- Value ttValue;
- Depth ttDepth;
- Move ttMove = MOVE_NONE;
- ValueType ttValueType;
-
- TT.retrieve(pos, &ttValue, &ttDepth, &ttMove, &ttValueType);
+ const TTEntry* tte = TT.retrieve(pos);
+ Move ttMove = (tte ? tte->move() : MOVE_NONE);
- // Internal iterative deepening.
- if(UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly) {
- search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
- ttMove = ss[ply].pv[ply];
+ // Go with internal iterative deepening if we don't have a TT move
+ if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly)
+ {
+ search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
+ ttMove = ss[ply].pv[ply];
}
// Initialize a MovePicker object for the current position, and prepare
- // to search all moves:
- MovePicker mp = MovePicker(pos, true, ttMove, ss[ply].mateKiller,
- ss[ply].killer1, ss[ply].killer2, depth);
+ // to search all moves
+ MovePicker mp = MovePicker(pos, true, ttMove, ss[ply], depth);
+
Move move, movesSearched[256];
int moveCount = 0;
Value value, bestValue = -VALUE_INFINITE;
Bitboard dcCandidates = mp.discovered_check_candidates();
- bool mateThreat =
- MateThreatExtension[1] > Depth(0)
- && pos.has_mate_threat(opposite_color(pos.side_to_move()));
+ Color us = pos.side_to_move();
+ bool isCheck = pos.is_check();
+ bool mateThreat = pos.has_mate_threat(opposite_color(us));
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
- while(alpha < beta && !thread_should_stop(threadID)
- && (move = mp.get_next_move()) != MOVE_NONE) {
- UndoInfo u;
- Depth ext, newDepth;
- bool singleReply = (pos.is_check() && mp.number_of_moves() == 1);
+ while ( alpha < beta
+ && (move = mp.get_next_move()) != MOVE_NONE
+ && !thread_should_stop(threadID))
+ {
+ assert(move_is_ok(move));
+
+ bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
- assert(move_is_ok(move));
movesSearched[moveCount++] = ss[ply].currentMove = move;
- ss[ply].currentMoveCaptureValue = move_is_ep(move)?
- PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ if (moveIsCapture)
+ ss[ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ else
+ ss[ply].currentMoveCaptureValue = Value(0);
- // Decide the new search depth.
- ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat);
- newDepth = depth - OnePly + ext;
+ // Decide the new search depth
+ bool dangerous;
+ Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
+ Depth newDepth = depth - OnePly + ext;
- // Make and search the move.
- pos.do_move(move, u, dcCandidates);
+ // Make and search the move
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
- if(moveCount == 1)
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
- else {
- if(depth >= 2*OnePly && ext == Depth(0) && moveCount >= LMRPVMoves
- && !moveIsCapture && !move_promotion(move)
- && !moveIsPassedPawnPush && !move_is_castle(move)
- && move != ss[ply].killer1 && move != ss[ply].killer2) {
- ss[ply].reduction = OnePly;
- value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true,
- threadID);
+ if (moveCount == 1) // The first move in list is the PV
+ value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
+ 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.
+ if ( depth >= 2*OnePly
+ && moveCount >= LMRPVMoves
+ && !dangerous
+ && !moveIsCapture
+ && !move_promotion(move)
+ && !move_is_castle(move)
+ && !move_is_killer(move, ss[ply]))
+ {
+ ss[ply].reduction = OnePly;
+ value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true, threadID);
}
- else value = alpha + 1;
- if(value > alpha) {
- ss[ply].reduction = Depth(0);
- value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
- if(value > alpha && value < beta) {
- if(ply == 1 && RootMoveNumber == 1)
- // When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
- // time managment: We don't want to stop the search early in
- // such cases, because resolving the fail high at ply 1 could
- // result in a big drop in score at the root.
- Threads[threadID].failHighPly1 = true;
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1,
- threadID);
- Threads[threadID].failHighPly1 = false;
+ else
+ value = alpha + 1; // Just to trigger next condition
+
+ if (value > alpha) // Go with full depth non-pv search
+ {
+ ss[ply].reduction = Depth(0);
+ value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
+ if (value > alpha && value < beta)
+ {
+ // When the search fails high at ply 1 while searching the first
+ // move at the root, set the flag failHighPly1. This is used for
+ // time managment: We don't want to stop the search early in
+ // such cases, because resolving the fail high at ply 1 could
+ // result in a big drop in score at the root.
+ if (ply == 1 && RootMoveNumber == 1)
+ Threads[threadID].failHighPly1 = true;
+
+ // A fail high occurred. Re-search at full window (pv search)
+ value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
+ Threads[threadID].failHighPly1 = false;
}
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// 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;
- }
- // If we are at ply 1, and we are searching the first root move at
- // ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration:
- if(Iteration >= 2 &&
- -value <= ValueByIteration[Iteration-1] - ProblemMargin)
- Problem = true;
+ 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;
+ }
+ // If we are at ply 1, and we are searching the first root move at
+ // ply 0, set the 'Problem' variable if the score has dropped a lot
+ // (from the computer's point of view) since the previous iteration:
+ if ( ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ Problem = true;
}
// Split?
- if(ActiveThreads > 1 && bestValue < beta && depth >= MinimumSplitDepth
- && Iteration <= 99 && idle_thread_exists(threadID)
- && !AbortSearch && !thread_should_stop(threadID)
- && split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
- &moveCount, &mp, dcCandidates, threadID, true))
- break;
+ if ( ActiveThreads > 1
+ && bestValue < beta
+ && depth >= MinimumSplitDepth
+ && Iteration <= 99
+ && idle_thread_exists(threadID)
+ && !AbortSearch
+ && !thread_should_stop(threadID)
+ && split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
+ &moveCount, &mp, dcCandidates, threadID, true))
+ break;
}
// All legal moves have been searched. A special case: If there were
// no legal moves, it must be mate or stalemate:
- if(moveCount == 0) {
- if(pos.is_check())
- return value_mated_in(ply);
- else
- return VALUE_DRAW;
- }
+ if (moveCount == 0)
+ return (isCheck ? value_mated_in(ply) : VALUE_DRAW);
// If the search is not aborted, update the transposition table,
- // history counters, and killer moves. This code is somewhat messy,
- // and definitely needs to be cleaned up. FIXME
- if(!AbortSearch && !thread_should_stop(threadID)) {
- if(bestValue <= oldAlpha)
- TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE,
- VALUE_TYPE_UPPER);
- else if(bestValue >= beta) {
+ // history counters, and killer moves.
+ if (AbortSearch || thread_should_stop(threadID))
+ return bestValue;
+
+ if (bestValue <= oldAlpha)
+ TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
+
+ else if (bestValue >= beta)
+ {
+ BetaCounter.add(pos.side_to_move(), depth, threadID);
Move m = ss[ply].pv[ply];
- if(pos.square_is_empty(move_to(m)) && !move_promotion(m) &&
- !move_is_ep(m)) {
- for(int i = 0; i < moveCount - 1; i++)
- if(pos.square_is_empty(move_to(movesSearched[i]))
- && !move_promotion(movesSearched[i])
- && !move_is_ep(movesSearched[i]))
- H.failure(pos.piece_on(move_from(movesSearched[i])),
- movesSearched[i]);
-
- H.success(pos.piece_on(move_from(m)), m, depth);
-
- if(m != ss[ply].killer1) {
- ss[ply].killer2 = ss[ply].killer1;
- ss[ply].killer1 = m;
- }
+ if (ok_to_history(pos, m)) // Only non capture moves are considered
+ {
+ update_history(pos, m, depth, movesSearched, moveCount);
+ update_killers(m, ss[ply]);
}
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
- }
- else
- TT.store(pos, value_to_tt(bestValue, ply), depth, ss[ply].pv[ply],
- VALUE_TYPE_EXACT);
}
+ else
+ TT.store(pos, value_to_tt(bestValue, ply), depth, ss[ply].pv[ply], VALUE_TYPE_EXACT);
return bestValue;
}
Value search(Position &pos, SearchStack ss[], Value beta, Depth depth,
int ply, bool allowNullmove, int threadID) {
+
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
+ if (depth < OnePly)
+ return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
- if(AbortSearch || thread_should_stop(threadID))
- return Value(0);
+ init_node(pos, ss, ply, threadID);
- if(depth < OnePly)
- return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
+ // After init_node() that calls poll()
+ if (AbortSearch || thread_should_stop(threadID))
+ return Value(0);
- init_node(pos, ss, ply, threadID);
+ if (pos.is_draw())
+ return VALUE_DRAW;
- if(pos.is_draw())
- return VALUE_DRAW;
+ EvalInfo ei;
- if(ply >= PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ if (ply >= PLY_MAX - 1)
+ return evaluate(pos, ei, threadID);
// Mate distance pruning
- if(value_mated_in(ply) >= beta)
- return beta;
- if(value_mate_in(ply+1) < beta)
- return beta-1;
+ if (value_mated_in(ply) >= beta)
+ return beta;
+
+ if (value_mate_in(ply + 1) < beta)
+ return beta - 1;
// Transposition table lookup
- bool ttFound;
- Value ttValue;
- Depth ttDepth;
- Move ttMove = MOVE_NONE;
- ValueType ttValueType;
-
- ttFound = TT.retrieve(pos, &ttValue, &ttDepth, &ttMove, &ttValueType);
- if(ttFound) {
- ttValue = value_from_tt(ttValue, ply);
- if(ttDepth >= depth
- || ttValue >= Max(value_mate_in(100), beta)
- || ttValue < Min(value_mated_in(100), beta)) {
- if((is_lower_bound(ttValueType) && ttValue >= beta) ||
- (is_upper_bound(ttValueType) && ttValue < beta)) {
- ss[ply].currentMove = ttMove;
- return ttValue;
- }
- }
+ const TTEntry* tte = TT.retrieve(pos);
+ Move 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);
}
Value approximateEval = quick_evaluate(pos);
bool mateThreat = false;
+ bool isCheck = pos.is_check();
// Null move search
- if(!pos.is_check() && allowNullmove && ok_to_do_nullmove(pos)
- && approximateEval >= beta - NullMoveMargin) {
- UndoInfo u;
- Value nullValue;
-
- ss[ply].currentMove = MOVE_NULL;
- pos.do_null_move(u);
- nullValue = -search(pos, ss, -(beta-1), depth-4*OnePly, ply+1, false,
- threadID);
- pos.undo_null_move(u);
-
- if(nullValue >= beta) {
- if(depth >= 6 * OnePly) { // Do zugzwang verification search
- Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
- if(v >= beta)
- return beta;
+ if ( allowNullmove
+ && depth > OnePly
+ && !isCheck
+ && !value_is_mate(beta)
+ && ok_to_do_nullmove(pos)
+ && approximateEval >= beta - NullMoveMargin)
+ {
+ ss[ply].currentMove = MOVE_NULL;
+
+ StateInfo st;
+ pos.do_null_move(st);
+ int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction
+
+ Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
+
+ pos.undo_null_move();
+
+ if (value_is_mate(nullValue))
+ {
+ /* Do not return unproven mates */
+ }
+ else if (nullValue >= beta)
+ {
+ if (depth < 6 * OnePly)
+ return beta;
+
+ // Do zugzwang verification search
+ Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
+ if (v >= beta)
+ return beta;
+ } 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
+ // move which was reduced. If a connection is found, return a fail
+ // low score (which will cause the reduced move to fail high in the
+ // parent node, which will trigger a re-search with full depth).
+ if (nullValue == value_mated_in(ply + 2))
+ mateThreat = true;
+
+ ss[ply].threatMove = ss[ply + 1].currentMove;
+ if ( depth < ThreatDepth
+ && ss[ply - 1].reduction
+ && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
+ return beta - 1;
}
- else
- return beta;
- }
- 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
- // move which was reduced. If a connection is found, return a fail
- // low score (which will cause the reduced move to fail high in the
- // parent node, which will trigger a re-search with full depth).
- if(nullValue == value_mated_in(ply+2))
- mateThreat = true;
- ss[ply].threatMove = ss[ply+1].currentMove;
- if(depth < ThreatDepth && ss[ply-1].reduction &&
- connected_moves(pos, ss[ply-1].currentMove, ss[ply].threatMove))
- return beta - 1;
- }
}
- // Razoring:
- else if(depth < RazorDepth && approximateEval < beta - RazorMargin &&
- evaluate(pos, ei, threadID) < beta - RazorMargin) {
- Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
- if(v < beta)
- return v;
+ // Null move search not allowed, try razoring
+ else if ( !value_is_mate(beta)
+ && approximateEval < beta - RazorMargin
+ && depth < RazorDepth
+ && (RazorAtDepthOne || depth > OnePly)
+ && ttMove == MOVE_NONE
+ && !pos.has_pawn_on_7th(pos.side_to_move()))
+ {
+ Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
+ if ( (v < beta - RazorMargin - RazorMargin / 4)
+ || (depth <= 2*OnePly && v < beta - RazorMargin)
+ || (depth <= OnePly && v < beta - RazorMargin / 2))
+ return v;
}
- // Internal iterative deepening
- if(UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
- evaluate(pos, ei, threadID) >= beta - IIDMargin) {
- search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
- ttMove = ss[ply].pv[ply];
+ // Go with internal iterative deepening if we don't have a TT move
+ if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
+ evaluate(pos, ei, threadID) >= beta - IIDMargin)
+ {
+ search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
+ ttMove = ss[ply].pv[ply];
}
// Initialize a MovePicker object for the current position, and prepare
// to search all moves:
- MovePicker mp = MovePicker(pos, false, ttMove, ss[ply].mateKiller,
- ss[ply].killer1, ss[ply].killer2, depth);
+ MovePicker mp = MovePicker(pos, false, ttMove, ss[ply], depth);
+
Move move, movesSearched[256];
int moveCount = 0;
- Value value, bestValue = -VALUE_INFINITE, futilityValue = VALUE_NONE;
+ Value value, bestValue = -VALUE_INFINITE;
Bitboard dcCandidates = mp.discovered_check_candidates();
- bool isCheck = pos.is_check();
- bool useFutilityPruning =
- UseFutilityPruning && depth < SelectiveDepth && !isCheck;
+ Value futilityValue = VALUE_NONE;
+ bool useFutilityPruning = UseFutilityPruning
+ && depth < SelectiveDepth
+ && !isCheck;
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
- while(bestValue < beta && !thread_should_stop(threadID)
- && (move = mp.get_next_move()) != MOVE_NONE) {
- UndoInfo u;
- Depth ext, newDepth;
+ while ( bestValue < beta
+ && (move = mp.get_next_move()) != MOVE_NONE
+ && !thread_should_stop(threadID))
+ {
+ assert(move_is_ok(move));
+
bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
- assert(move_is_ok(move));
movesSearched[moveCount++] = ss[ply].currentMove = move;
- // Decide the new search depth.
- ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat);
- newDepth = depth - OnePly + ext;
+ // Decide the new search depth
+ bool dangerous;
+ Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
+ Depth newDepth = depth - OnePly + ext;
// Futility pruning
- if(useFutilityPruning && ext == Depth(0) && !moveIsCapture &&
- !moveIsPassedPawnPush && !move_promotion(move)) {
-
- if(moveCount >= 2 + int(depth)
- && ok_to_prune(pos, move, ss[ply].threatMove, depth))
- continue;
-
- if(depth < 3 * OnePly && approximateEval < beta) {
- if(futilityValue == VALUE_NONE)
- futilityValue = evaluate(pos, ei, threadID)
- + ((depth < 2 * OnePly)? FutilityMargin1 : FutilityMargin2);
- if(futilityValue < beta) {
- if(futilityValue > bestValue)
- bestValue = futilityValue;
- continue;
+ if ( useFutilityPruning
+ && !dangerous
+ && !moveIsCapture
+ && !move_promotion(move))
+ {
+ // History pruning. See ok_to_prune() definition
+ if ( moveCount >= 2 + int(depth)
+ && ok_to_prune(pos, move, ss[ply].threatMove, depth))
+ continue;
+
+ // Value based pruning
+ if (depth < 7 * OnePly && approximateEval < beta)
+ {
+ if (futilityValue == VALUE_NONE)
+ futilityValue = evaluate(pos, ei, threadID)
+ + FutilityMargins[int(depth)/2 - 1]
+ + 32 * (depth & 1);
+
+ if (futilityValue < beta)
+ {
+ if (futilityValue > bestValue)
+ bestValue = futilityValue;
+ continue;
+ }
}
- }
}
- // Make and search the move.
- pos.do_move(move, u, dcCandidates);
-
- if(depth >= 2*OnePly && ext == Depth(0) && moveCount >= LMRNonPVMoves
- && !moveIsCapture && !move_promotion(move) && !moveIsPassedPawnPush
- && !move_is_castle(move)
- && move != ss[ply].killer1 && move != ss[ply].killer2) {
- ss[ply].reduction = OnePly;
- value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true,
- threadID);
+ // Make and search the move
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
+
+ // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // if the move fails high will be re-searched at full depth.
+ if ( depth >= 2*OnePly
+ && moveCount >= LMRNonPVMoves
+ && !dangerous
+ && !moveIsCapture
+ && !move_promotion(move)
+ && !move_is_castle(move)
+ && !move_is_killer(move, ss[ply]))
+ {
+ // LMR dynamic reduction
+ Depth R = UseDynamicLMR
+ && moveCount >= 2 * LMRNonPVMoves
+ && depth > 7*OnePly ? 2*OnePly : OnePly;
+
+ ss[ply].reduction = R;
+ value = -search(pos, ss, -(beta-1), newDepth-R, ply+1, true, threadID);
}
else
- value = beta;
- if(value >= beta) {
- ss[ply].reduction = Depth(0);
- value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
+ value = beta; // Just to trigger next condition
+
+ if (value >= beta) // Go with full depth non-pv search
+ {
+ ss[ply].reduction = Depth(0);
+ value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// New best move?
- if(value > bestValue) {
+ if (value > bestValue)
+ {
bestValue = value;
- if(value >= beta)
- update_pv(ss, ply);
- if(value == value_mate_in(ply + 1))
- ss[ply].mateKiller = move;
+ if (value >= beta)
+ update_pv(ss, ply);
+
+ if (value == value_mate_in(ply + 1))
+ ss[ply].mateKiller = move;
}
// Split?
- if(ActiveThreads > 1 && bestValue < beta && depth >= MinimumSplitDepth
- && Iteration <= 99 && idle_thread_exists(threadID)
- && !AbortSearch && !thread_should_stop(threadID)
- && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
- &mp, dcCandidates, threadID, false))
+ if ( ActiveThreads > 1
+ && bestValue < beta
+ && depth >= MinimumSplitDepth
+ && Iteration <= 99
+ && idle_thread_exists(threadID)
+ && !AbortSearch
+ && !thread_should_stop(threadID)
+ && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
+ &mp, dcCandidates, threadID, false))
break;
}
// All legal moves have been searched. A special case: If there were
- // no legal moves, it must be mate or stalemate:
- if(moveCount == 0) {
- if(pos.is_check())
- return value_mated_in(ply);
- else
- return VALUE_DRAW;
- }
+ // no legal moves, it must be mate or stalemate.
+ if (moveCount == 0)
+ return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
// If the search is not aborted, update the transposition table,
- // history counters, and killer moves. This code is somewhat messy,
- // and definitely needs to be cleaned up. FIXME
- if(!AbortSearch && !thread_should_stop(threadID)) {
- if(bestValue < beta)
- TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE,
- VALUE_TYPE_UPPER);
- else {
- Move m = ss[ply].pv[ply];
+ // history counters, and killer moves.
+ if (AbortSearch || thread_should_stop(threadID))
+ return bestValue;
- if(pos.square_is_empty(move_to(m)) && !move_promotion(m) &&
- !move_is_ep(m)) {
- for(int i = 0; i < moveCount - 1; i++)
- if(pos.square_is_empty(move_to(movesSearched[i]))
- && !move_promotion(movesSearched[i])
- && !move_is_ep(movesSearched[i]))
- H.failure(pos.piece_on(move_from(movesSearched[i])),
- movesSearched[i]);
- H.success(pos.piece_on(move_from(m)), m, depth);
-
- if(m != ss[ply].killer1) {
- ss[ply].killer2 = ss[ply].killer1;
- ss[ply].killer1 = m;
- }
+ if (bestValue < beta)
+ TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
+ else
+ {
+ BetaCounter.add(pos.side_to_move(), depth, threadID);
+ Move m = ss[ply].pv[ply];
+ if (ok_to_history(pos, m)) // Only non capture moves are considered
+ {
+ update_history(pos, m, depth, movesSearched, moveCount);
+ update_killers(m, ss[ply]);
}
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
- }
}
+ assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
+
return bestValue;
}
Value qsearch(Position &pos, SearchStack ss[], Value alpha, Value beta,
Depth depth, int ply, int threadID) {
- Value staticValue, bestValue, value;
- EvalInfo ei;
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
- if(AbortSearch || thread_should_stop(threadID))
- return Value(0);
-
init_node(pos, ss, ply, threadID);
- if(pos.is_draw())
- return VALUE_DRAW;
+ // After init_node() that calls poll()
+ if (AbortSearch || thread_should_stop(threadID))
+ return Value(0);
+
+ if (pos.is_draw())
+ return VALUE_DRAW;
- // Evaluate the position statically:
- staticValue = evaluate(pos, ei, threadID);
+ // Transposition table lookup, only when not in PV
+ TTEntry* tte = NULL;
+ bool pvNode = (beta - alpha != 1);
+ if (!pvNode)
+ {
+ tte = TT.retrieve(pos);
+ if (tte && ok_to_use_TT(tte, depth, beta, ply))
+ {
+ assert(tte->type() != VALUE_TYPE_EVAL);
- if(ply == PLY_MAX - 1) return staticValue;
+ return value_from_tt(tte->value(), ply);
+ }
+ }
+
+ // Evaluate the position statically
+ EvalInfo ei;
+ Value staticValue;
+ bool isCheck = pos.is_check();
+
+ if (isCheck)
+ staticValue = -VALUE_INFINITE;
+
+ else if (tte && tte->type() == VALUE_TYPE_EVAL)
+ {
+ // Use the cached evaluation score if possible
+ assert(tte->value() == evaluate(pos, ei, threadID));
+ assert(ei.futilityMargin == Value(0));
+
+ staticValue = tte->value();
+ ei.futilityMargin = Value(0); // manually initialize futilityMargin
+ }
+ else
+ staticValue = evaluate(pos, ei, threadID);
+
+ if (ply == PLY_MAX - 1)
+ return evaluate(pos, ei, threadID);
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
- if(pos.is_check())
- bestValue = -VALUE_INFINITE;
- else {
- bestValue = staticValue;
- if(bestValue >= beta)
+ Value bestValue = staticValue;
+
+ if (bestValue >= beta)
+ {
+ // Update transposition table before to leave
+ TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT);
return bestValue;
- if(bestValue > alpha)
- alpha = bestValue;
}
+ else if (!isCheck && !tte && ei.futilityMargin == 0)
+ {
+ // Store the score to avoid a future costly evaluation() call
+ TT.store(pos, value_to_tt(bestValue, ply), Depth(-127*OnePly), MOVE_NONE, VALUE_TYPE_EVAL);
+ }
+
+ if (bestValue > alpha)
+ alpha = bestValue;
// 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) will be generated.
- MovePicker mp = MovePicker(pos, false, MOVE_NONE, MOVE_NONE, MOVE_NONE,
- MOVE_NONE, depth);
+ MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth);
Move move;
int moveCount = 0;
Bitboard dcCandidates = mp.discovered_check_candidates();
- bool isCheck = pos.is_check();
+ Color us = pos.side_to_move();
+ bool enoughMaterial = pos.non_pawn_material(us) > RookValueMidgame;
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
- while(alpha < beta && ((move = mp.get_next_move()) != MOVE_NONE)) {
- UndoInfo u;
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
-
+ while ( alpha < beta
+ && (move = mp.get_next_move()) != MOVE_NONE)
+ {
assert(move_is_ok(move));
moveCount++;
ss[ply].currentMove = move;
// Futility pruning
- if(UseQSearchFutilityPruning && !isCheck && !moveIsCheck &&
- !move_promotion(move) && !moveIsPassedPawnPush &&
- beta - alpha == 1 &&
- pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame) {
- Value futilityValue =
- staticValue
- + Max(pos.midgame_value_of_piece_on(move_to(move)),
- pos.endgame_value_of_piece_on(move_to(move)))
- + FutilityMargin0
- + ei.futilityMargin;
- if(futilityValue < alpha) {
- if(futilityValue > bestValue)
- bestValue = futilityValue;
- continue;
- }
+ if ( UseQSearchFutilityPruning
+ && enoughMaterial
+ && !isCheck
+ && !pvNode
+ && !move_promotion(move)
+ && !pos.move_is_check(move, dcCandidates)
+ && !pos.move_is_passed_pawn_push(move))
+ {
+ Value futilityValue = staticValue
+ + Max(pos.midgame_value_of_piece_on(move_to(move)),
+ pos.endgame_value_of_piece_on(move_to(move)))
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0))
+ + FutilityMarginQS
+ + ei.futilityMargin;
+
+ if (futilityValue < alpha)
+ {
+ if (futilityValue > bestValue)
+ bestValue = futilityValue;
+ continue;
+ }
}
- // Don't search captures and checks with negative SEE values.
- if(!isCheck && !move_promotion(move) &&
- pos.midgame_value_of_piece_on(move_from(move)) >
- pos.midgame_value_of_piece_on(move_to(move)) &&
- pos.see(move) < 0)
- continue;
+ // Don't search captures and checks with negative SEE values
+ if ( !isCheck
+ && !move_promotion(move)
+ && (pos.midgame_value_of_piece_on(move_from(move)) >
+ pos.midgame_value_of_piece_on(move_to(move)))
+ && pos.see(move) < 0)
+ continue;
// Make and search the move.
- pos.do_move(move, u, dcCandidates);
- value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
- pos.undo_move(move, u);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
+ Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// New best move?
- if(value > bestValue) {
- bestValue = value;
- if(value > alpha) {
- alpha = value;
- update_pv(ss, ply);
- }
- }
+ if (value > bestValue)
+ {
+ bestValue = value;
+ if (value > alpha)
+ {
+ alpha = value;
+ update_pv(ss, ply);
+ }
+ }
}
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate:
- if(pos.is_check() && moveCount == 0) // Mate!
- return value_mated_in(ply);
+ if (pos.is_check() && moveCount == 0) // Mate!
+ return value_mated_in(ply);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
+ // Update killers only for good check moves
+ Move m = ss[ply].currentMove;
+ if (alpha >= beta && ok_to_history(pos, m)) // Only non capture moves are considered
+ {
+ // Wrong to update history when depth is <= 0
+ update_killers(m, ss[ply]);
+ }
return bestValue;
}
// care of after we return from the split point.
void sp_search(SplitPoint *sp, int threadID) {
+
assert(threadID >= 0 && threadID < ActiveThreads);
assert(ActiveThreads > 1);
SearchStack *ss = sp->sstack[threadID];
Value value;
Move move;
- int moveCount = sp->moves;
bool isCheck = pos.is_check();
- bool useFutilityPruning =
- UseFutilityPruning && sp->depth < SelectiveDepth && !isCheck;
+ bool useFutilityPruning = UseFutilityPruning
+ && sp->depth < SelectiveDepth
+ && !isCheck;
+
+ while ( sp->bestValue < sp->beta
+ && !thread_should_stop(threadID)
+ && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
+ {
+ assert(move_is_ok(move));
- while(sp->bestValue < sp->beta && !thread_should_stop(threadID)
- && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) {
- UndoInfo u;
- Depth ext, newDepth;
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
-
- assert(move_is_ok(move));
lock_grab(&(sp->lock));
- sp->moves++;
- moveCount = sp->moves;
+ int moveCount = ++sp->moves;
lock_release(&(sp->lock));
ss[sp->ply].currentMove = move;
// Decide the new search depth.
- ext = extension(pos, move, false, moveIsCheck, false, false);
- newDepth = sp->depth - OnePly + ext;
+ bool dangerous;
+ Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, false, false, &dangerous);
+ Depth newDepth = sp->depth - OnePly + ext;
// Prune?
- if(useFutilityPruning && ext == Depth(0) && !moveIsCapture
- && !moveIsPassedPawnPush && !move_promotion(move)
- && moveCount >= 2 + int(sp->depth)
- && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
+ if ( useFutilityPruning
+ && !dangerous
+ && !moveIsCapture
+ && !move_promotion(move)
+ && moveCount >= 2 + int(sp->depth)
+ && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
continue;
// Make and search the move.
- pos.do_move(move, u, sp->dcCandidates);
- if(ext == Depth(0) && moveCount >= LMRNonPVMoves
- && !moveIsCapture && !move_promotion(move) && !moveIsPassedPawnPush
- && !move_is_castle(move)
- && move != ss[sp->ply].killer1 && move != ss[sp->ply].killer2) {
- ss[sp->ply].reduction = OnePly;
- value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1,
- true, threadID);
+ StateInfo st;
+ pos.do_move(move, st, sp->dcCandidates);
+
+ // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // if the move fails high will be re-searched at full depth.
+ if ( !dangerous
+ && moveCount >= LMRNonPVMoves
+ && !moveIsCapture
+ && !move_promotion(move)
+ && !move_is_castle(move)
+ && !move_is_killer(move, ss[sp->ply]))
+ {
+ ss[sp->ply].reduction = OnePly;
+ value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, true, threadID);
}
else
- value = sp->beta;
- if(value >= sp->beta) {
- ss[sp->ply].reduction = Depth(0);
- value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true,
- threadID);
+ value = sp->beta; // Just to trigger next condition
+
+ if (value >= sp->beta) // 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, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- if(thread_should_stop(threadID))
- break;
+ if (thread_should_stop(threadID))
+ break;
// New best move?
lock_grab(&(sp->lock));
- if(value > sp->bestValue && !thread_should_stop(threadID)) {
- sp->bestValue = value;
- if(sp->bestValue >= sp->beta) {
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- for(int i = 0; i < ActiveThreads; i++)
- if(i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
- sp->finished = true;
+ if (value > sp->bestValue && !thread_should_stop(threadID))
+ {
+ sp->bestValue = value;
+ if (sp->bestValue >= sp->beta)
+ {
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
+ for (int i = 0; i < ActiveThreads; i++)
+ if (i != threadID && (i == sp->master || sp->slaves[i]))
+ Threads[i].stop = true;
+
+ sp->finished = true;
}
}
lock_release(&(sp->lock));
// If this is the master thread and we have been asked to stop because of
// a beta cutoff higher up in the tree, stop all slave threads:
- if(sp->master == threadID && thread_should_stop(threadID))
- for(int i = 0; i < ActiveThreads; i++)
- if(sp->slaves[i])
- Threads[i].stop = true;
+ if (sp->master == threadID && thread_should_stop(threadID))
+ for (int i = 0; i < ActiveThreads; i++)
+ if (sp->slaves[i])
+ Threads[i].stop = true;
sp->cpus--;
sp->slaves[threadID] = 0;
// after we return from the split point.
void sp_search_pv(SplitPoint *sp, int threadID) {
+
assert(threadID >= 0 && threadID < ActiveThreads);
assert(ActiveThreads > 1);
SearchStack *ss = sp->sstack[threadID];
Value value;
Move move;
- int moveCount = sp->moves;
- while(sp->alpha < sp->beta && !thread_should_stop(threadID)
- && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) {
- UndoInfo u;
- Depth ext, newDepth;
+ while ( sp->alpha < sp->beta
+ && !thread_should_stop(threadID)
+ && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
+ {
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
assert(move_is_ok(move));
- ss[sp->ply].currentMoveCaptureValue = move_is_ep(move)?
- PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ if (moveIsCapture)
+ ss[sp->ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ else
+ ss[sp->ply].currentMoveCaptureValue = Value(0);
lock_grab(&(sp->lock));
- sp->moves++;
- moveCount = sp->moves;
+ int moveCount = ++sp->moves;
lock_release(&(sp->lock));
ss[sp->ply].currentMove = move;
// Decide the new search depth.
- ext = extension(pos, move, true, moveIsCheck, false, false);
- newDepth = sp->depth - OnePly + ext;
+ bool dangerous;
+ Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, false, false, &dangerous);
+ Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
- pos.do_move(move, u, sp->dcCandidates);
- if(ext == Depth(0) && moveCount >= LMRPVMoves && !moveIsCapture
- && !move_promotion(move) && !moveIsPassedPawnPush
- && !move_is_castle(move)
- && move != ss[sp->ply].killer1 && move != ss[sp->ply].killer2) {
- ss[sp->ply].reduction = OnePly;
- value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1,
- true, threadID);
+ StateInfo st;
+ pos.do_move(move, st, sp->dcCandidates);
+
+ // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // if the move fails high will be re-searched at full depth.
+ if ( !dangerous
+ && moveCount >= LMRPVMoves
+ && !moveIsCapture
+ && !move_promotion(move)
+ && !move_is_castle(move)
+ && !move_is_killer(move, ss[sp->ply]))
+ {
+ ss[sp->ply].reduction = OnePly;
+ value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, true, threadID);
}
else
- value = sp->alpha + 1;
- if(value > sp->alpha) {
- ss[sp->ply].reduction = Depth(0);
- value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true,
- threadID);
- if(value > sp->alpha && value < sp->beta) {
- if(sp->ply == 1 && RootMoveNumber == 1)
- // When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
- // time managment: We don't want to stop the search early in
- // such cases, because resolving the fail high at ply 1 could
- // result in a big drop in score at the root.
- Threads[threadID].failHighPly1 = true;
- value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth,
- sp->ply+1, threadID);
- Threads[threadID].failHighPly1 = false;
+ value = sp->alpha + 1; // Just to trigger next condition
+
+ if (value > sp->alpha) // Go with full depth non-pv search
+ {
+ ss[sp->ply].reduction = Depth(0);
+ value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID);
+
+ if (value > sp->alpha && value < sp->beta)
+ {
+ // When the search fails high at ply 1 while searching the first
+ // move at the root, set the flag failHighPly1. This is used for
+ // time managment: We don't want to stop the search early in
+ // such cases, because resolving the fail high at ply 1 could
+ // result in a big drop in score at the root.
+ if (sp->ply == 1 && RootMoveNumber == 1)
+ Threads[threadID].failHighPly1 = true;
+
+ value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, sp->ply+1, threadID);
+ Threads[threadID].failHighPly1 = false;
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- if(thread_should_stop(threadID))
- break;
+ if (thread_should_stop(threadID))
+ break;
// New best move?
lock_grab(&(sp->lock));
- if(value > sp->bestValue && !thread_should_stop(threadID)) {
- sp->bestValue = value;
- if(value > sp->alpha) {
- sp->alpha = value;
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- if(value == value_mate_in(sp->ply + 1))
- ss[sp->ply].mateKiller = move;
- if(value >= sp->beta) {
- for(int i = 0; i < ActiveThreads; i++)
- if(i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
- sp->finished = true;
- }
+ if (value > sp->bestValue && !thread_should_stop(threadID))
+ {
+ sp->bestValue = value;
+ if (value > sp->alpha)
+ {
+ sp->alpha = value;
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
+ if (value == value_mate_in(sp->ply + 1))
+ ss[sp->ply].mateKiller = move;
+
+ if(value >= sp->beta)
+ {
+ for(int i = 0; i < ActiveThreads; i++)
+ if(i != threadID && (i == sp->master || sp->slaves[i]))
+ Threads[i].stop = true;
+
+ sp->finished = true;
+ }
}
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration:
- if(Iteration >= 2 &&
- -value <= ValueByIteration[Iteration-1] - ProblemMargin)
- Problem = true;
+ // (from the computer's point of view) since the previous iteration.
+ if ( sp->ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ Problem = true;
}
lock_release(&(sp->lock));
}
lock_grab(&(sp->lock));
// If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads:
- if(sp->master == threadID && thread_should_stop(threadID))
- for(int i = 0; i < ActiveThreads; i++)
- if(sp->slaves[i])
- Threads[i].stop = true;
+ // a beta cutoff higher up in the tree, stop all slave threads.
+ if (sp->master == threadID && thread_should_stop(threadID))
+ for (int i = 0; i < ActiveThreads; i++)
+ if (sp->slaves[i])
+ Threads[i].stop = true;
sp->cpus--;
sp->slaves[threadID] = 0;
lock_release(&(sp->lock));
}
+ /// The BetaCounterType class
+
+ BetaCounterType::BetaCounterType() { clear(); }
+
+ void BetaCounterType::clear() {
+
+ for (int i = 0; i < THREAD_MAX; i++)
+ hits[i][WHITE] = hits[i][BLACK] = 0ULL;
+ }
+
+ void BetaCounterType::add(Color us, Depth d, int threadID) {
+
+ // Weighted count based on depth
+ hits[threadID][us] += int(d);
+ }
+
+ void BetaCounterType::read(Color us, int64_t& our, int64_t& their) {
+
+ our = their = 0UL;
+ for (int i = 0; i < THREAD_MAX; i++)
+ {
+ our += hits[i][us];
+ their += hits[i][opposite_color(us)];
+ }
+ }
+
/// The RootMove class
if (score != m.score)
return (score < m.score);
- return nodes <= m.nodes;
+ return theirBeta <= m.theirBeta;
}
/// The RootMoveList class
if (includeMove)
{
// Find a quick score for the move
- UndoInfo u;
+ StateInfo st;
SearchStack ss[PLY_MAX_PLUS_2];
moves[count].move = mlist[i].move;
moves[count].nodes = 0ULL;
- pos.do_move(moves[count].move, u);
+ pos.do_move(moves[count].move, st);
moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE,
Depth(0), 1, 0);
- pos.undo_move(moves[count].move, u);
+ pos.undo_move(moves[count].move);
moves[count].pv[0] = moves[i].move;
moves[count].pv[1] = MOVE_NONE; // FIXME
count++;
moves[moveNum].cumulativeNodes += nodes;
}
+ inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
+ moves[moveNum].ourBeta = our;
+ moves[moveNum].theirBeta = their;
+ }
+
void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
int j;
for(j = 0; pv[j] != MOVE_NONE; j++)
}
- // init_search_stack() initializes a search stack at the beginning of a
- // new search from the root.
-
- void init_search_stack(SearchStack ss[]) {
- for(int i = 0; i < 3; i++) {
- ss[i].pv[i] = MOVE_NONE;
- ss[i].pv[i+1] = MOVE_NONE;
- ss[i].currentMove = MOVE_NONE;
- ss[i].mateKiller = MOVE_NONE;
- ss[i].killer1 = MOVE_NONE;
- ss[i].killer2 = MOVE_NONE;
- ss[i].threatMove = MOVE_NONE;
- ss[i].reduction = Depth(0);
- }
- }
-
-
// 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
}
}
- ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE;
- ss[ply+2].mateKiller = MOVE_NONE;
- ss[ply+2].killer1 = ss[ply+2].killer2 = MOVE_NONE;
- ss[ply].threatMove = MOVE_NONE;
- ss[ply].reduction = Depth(0);
- ss[ply].currentMoveCaptureValue = Value(0);
+ ss[ply].init(ply);
+ ss[ply+2].initKillers();
if(Threads[threadID].printCurrentLine)
print_current_line(ss, ply, threadID);
// Case 4: The destination square for m2 is attacked by the moving piece
// in m1:
- if(pos.piece_attacks_square(t1, t2))
+ if(pos.piece_attacks_square(pos.piece_on(t1), t1, t2))
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1:
}
+ // value_is_mate() checks if the given value is a mate one
+ // eventually compensated for the ply.
+
+ bool value_is_mate(Value value) {
+
+ assert(abs(value) <= VALUE_INFINITE);
+
+ return value <= value_mated_in(PLY_MAX)
+ || value >= value_mate_in(PLY_MAX);
+ }
+
+
+ // move_is_killer() checks if the given move is among the
+ // killer moves of that ply.
+
+ bool move_is_killer(Move m, const SearchStack& ss) {
+
+ const Move* k = ss.killers;
+ for (int i = 0; i < KILLER_MAX; i++, k++)
+ if (*k == m)
+ return true;
+
+ return false;
+ }
+
+
// extension() decides whether a move should be searched with normal depth,
// or with extended depth. Certain classes of moves (checking moves, in
- // particular) are searched with bigger depth than ordinary moves.
+ // particular) are searched with bigger depth than ordinary moves and in
+ // any case are marked as 'dangerous'. Note that also if a move is not
+ // extended, as example because the corresponding UCI option is set to zero,
+ // the move is marked as 'dangerous' so, at least, we avoid to prune it.
+
+ Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check,
+ bool singleReply, bool mateThreat, bool* dangerous) {
+
+ assert(m != MOVE_NONE);
- Depth extension(const Position &pos, Move m, bool pvNode,
- bool check, bool singleReply, bool mateThreat) {
Depth result = Depth(0);
+ *dangerous = check || singleReply || mateThreat;
+
+ if (check)
+ result += CheckExtension[pvNode];
+
+ if (singleReply)
+ result += SingleReplyExtension[pvNode];
- if(check)
- result += CheckExtension[pvNode];
- if(singleReply)
- result += SingleReplyExtension[pvNode];
- if(pos.move_is_pawn_push_to_7th(m))
- result += PawnPushTo7thExtension[pvNode];
- if(pos.move_is_passed_pawn_push(m))
- result += PassedPawnExtension[pvNode];
- if(mateThreat)
- result += MateThreatExtension[pvNode];
- if(pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame
- && (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- - pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
- && !move_promotion(m))
- result += PawnEndgameExtension[pvNode];
- if(pvNode && pos.move_is_capture(m)
- && pos.type_of_piece_on(move_to(m)) != PAWN && pos.see(m) >= 0)
- result += OnePly/2;
+ if (mateThreat)
+ result += MateThreatExtension[pvNode];
+
+ if (pos.type_of_piece_on(move_from(m)) == PAWN)
+ {
+ if (pos.move_is_pawn_push_to_7th(m))
+ {
+ result += PawnPushTo7thExtension[pvNode];
+ *dangerous = true;
+ }
+ if (pos.move_is_passed_pawn_push(m))
+ {
+ result += PassedPawnExtension[pvNode];
+ *dangerous = true;
+ }
+ }
+
+ if ( capture
+ && 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))
+ && !move_promotion(m)
+ && !move_is_ep(m))
+ {
+ result += PawnEndgameExtension[pvNode];
+ *dangerous = true;
+ }
+
+ if ( pvNode
+ && capture
+ && pos.type_of_piece_on(move_to(m)) != PAWN
+ && pos.see(m) >= 0)
+ {
+ result += OnePly/2;
+ *dangerous = true;
+ }
return Min(result, OnePly);
}
tto = move_to(threat);
// Case 1: Castling moves are never pruned.
- if(move_is_castle(m))
- return false;
+ if (move_is_castle(m))
+ return false;
// Case 2: Don't prune moves which move the threatened piece
- if(!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
- return false;
+ if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
+ return false;
// Case 3: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune move which defend it.
- if(!PruneDefendingMoves && threat != MOVE_NONE
- && (piece_value_midgame(pos.piece_on(tfrom))
- >= piece_value_midgame(pos.piece_on(tto)))
- && pos.move_attacks_square(m, tto))
+ if ( !PruneDefendingMoves
+ && threat != MOVE_NONE
+ && pos.move_is_capture(threat)
+ && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
+ || pos.type_of_piece_on(tfrom) == KING)
+ && pos.move_attacks_square(m, tto))
return false;
// Case 4: Don't prune moves with good history.
- if(!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
- return false;
+ if (!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
+ return false;
// Case 5: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
- if(!PruneBlockingMoves && threat != MOVE_NONE
- && piece_is_slider(pos.piece_on(tfrom))
- && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0)
- return false;
+ if ( !PruneBlockingMoves
+ && threat != MOVE_NONE
+ && piece_is_slider(pos.piece_on(tfrom))
+ && bit_is_set(squares_between(tfrom, tto), mto)
+ && pos.see(m) >= 0)
+ return false;
return true;
}
+ // ok_to_use_TT() returns true if a transposition table score
+ // can be used at a given point in search.
+
+ bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
+
+ Value v = value_from_tt(tte->value(), ply);
+
+ return ( tte->depth() >= depth
+ || v >= Max(value_mate_in(100), beta)
+ || v < Min(value_mated_in(100), beta))
+
+ && ( (is_lower_bound(tte->type()) && v >= beta)
+ || (is_upper_bound(tte->type()) && v < beta));
+ }
+
+
+ // ok_to_history() returns true if a move m can be stored
+ // in history. Should be a non capturing move nor a promotion.
+
+ bool ok_to_history(const Position& pos, Move m) {
+
+ return !pos.move_is_capture(m) && !move_promotion(m);
+ }
+
+
+ // update_history() registers a good move that produced a beta-cutoff
+ // in history and marks as failures all the other moves of that ply.
+
+ void update_history(const Position& pos, Move m, Depth depth,
+ Move movesSearched[], int moveCount) {
+
+ H.success(pos.piece_on(move_from(m)), m, depth);
+
+ for (int i = 0; i < moveCount - 1; i++)
+ {
+ assert(m != movesSearched[i]);
+ if (ok_to_history(pos, movesSearched[i]))
+ H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]);
+ }
+ }
+
+
+ // 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) {
+
+ 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;
+ }
+
// fail_high_ply_1() checks if some thread is currently resolving a fail
// high at ply 1 at the node below the first root node. This information
// is used for time managment.
// search.
void poll() {
- int t, data;
- static int lastInfoTime;
- t = current_search_time();
+ static int lastInfoTime;
+ int t = current_search_time();
// Poll for input
- data = Bioskey();
- if(data) {
- char input[256];
- if(fgets(input, 255, stdin) == NULL)
- strcpy(input, "quit\n");
- if(strncmp(input, "quit", 4) == 0) {
- AbortSearch = true;
- PonderSearch = false;
- Quit = true;
- }
- else if(strncmp(input, "stop", 4) == 0) {
- AbortSearch = true;
- PonderSearch = false;
- }
- else if(strncmp(input, "ponderhit", 9) == 0)
- ponderhit();
- }
+ if (Bioskey())
+ {
+ // We are line oriented, don't read single chars
+ std::string command;
+ if (!std::getline(std::cin, command))
+ command = "quit";
- // Print search information
- if(t < 1000)
- lastInfoTime = 0;
- else if(lastInfoTime > t)
- // HACK: Must be a new search where we searched less than
- // NodesBetweenPolls nodes during the first second of search.
- lastInfoTime = 0;
- else if(t - lastInfoTime >= 1000) {
- lastInfoTime = t;
- lock_grab(&IOLock);
- std::cout << "info nodes " << nodes_searched() << " nps " << nps()
- << " time " << t << " hashfull " << TT.full() << std::endl;
- lock_release(&IOLock);
- if(ShowCurrentLine)
- Threads[0].printCurrentLine = true;
+ if (command == "quit")
+ {
+ AbortSearch = true;
+ PonderSearch = false;
+ Quit = true;
+ }
+ else if(command == "stop")
+ {
+ AbortSearch = true;
+ PonderSearch = false;
+ }
+ else if(command == "ponderhit")
+ ponderhit();
}
+ // Print search information
+ if (t < 1000)
+ lastInfoTime = 0;
+
+ else if (lastInfoTime > t)
+ // HACK: Must be a new search where we searched less than
+ // NodesBetweenPolls nodes during the first second of search.
+ lastInfoTime = 0;
+ else if (t - lastInfoTime >= 1000)
+ {
+ lastInfoTime = t;
+ lock_grab(&IOLock);
+ if (dbg_show_mean)
+ dbg_print_mean();
+
+ if (dbg_show_hit_rate)
+ dbg_print_hit_rate();
+
+ std::cout << "info nodes " << nodes_searched() << " nps " << nps()
+ << " time " << t << " hashfull " << TT.full() << std::endl;
+ lock_release(&IOLock);
+ if (ShowCurrentLine)
+ Threads[0].printCurrentLine = true;
+ }
// Should we stop the search?
- if(!PonderSearch && Iteration >= 2 &&
- (!InfiniteSearch && (t > AbsoluteMaxSearchTime ||
- (RootMoveNumber == 1 &&
- t > MaxSearchTime + ExtraSearchTime) ||
- (!FailHigh && !fail_high_ply_1() && !Problem &&
- t > 6*(MaxSearchTime + ExtraSearchTime)))))
- AbortSearch = true;
+ if (PonderSearch)
+ return;
- if(!PonderSearch && ExactMaxTime && t >= ExactMaxTime)
- AbortSearch = true;
+ bool overTime = t > AbsoluteMaxSearchTime
+ || (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime)
+ || ( !FailHigh && !fail_high_ply_1() && !Problem
+ && t > 6*(MaxSearchTime + ExtraSearchTime));
- if(!PonderSearch && Iteration >= 3 && MaxNodes
- && nodes_searched() >= MaxNodes)
- AbortSearch = true;
+ if ( (Iteration >= 3 && (!InfiniteSearch && overTime))
+ || (ExactMaxTime && t >= ExactMaxTime)
+ || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
+ AbortSearch = true;
}
void ponderhit() {
int t = current_search_time();
PonderSearch = false;
- if(Iteration >= 2 &&
+ if(Iteration >= 3 &&
(!InfiniteSearch && (StopOnPonderhit ||
t > AbsoluteMaxSearchTime ||
(RootMoveNumber == 1 &&
// splitPoint->cpus becomes 0), split() returns true.
bool split(const Position &p, SearchStack *sstck, int ply,
- Value *alpha, Value *beta, Value *bestValue,
- Depth depth, int *moves,
+ Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode) {
+
assert(p.is_ok());
assert(sstck != NULL);
assert(ply >= 0 && ply < PLY_MAX);
projects / stockfish / blobdiff