/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <cassert>
#include <cmath>
#include <cstring>
+#include <exception>
#include <iostream>
#include <sstream>
#include "book.h"
#include "evaluate.h"
-#include "history.h"
#include "movegen.h"
#include "movepick.h"
#include "notation.h"
// Futility lookup tables (initialized at startup) and their access functions
Value FutilityMargins[16][64]; // [depth][moveNumber]
- int FutilityMoveCounts[32]; // [depth]
+ int FutilityMoveCounts[2][32]; // [improving][depth]
inline Value futility_margin(Depth d, int mn) {
}
// Reduction lookup tables (initialized at startup) and their access function
- int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
+ int8_t Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
- template <bool PvNode> inline Depth reduction(Depth d, int mn) {
+ template <bool PvNode> inline Depth reduction(bool i, Depth d, int mn) {
- return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
+ return (Depth) Reductions[PvNode][i][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
}
size_t PVSize, PVIdx;
TimeManager TimeMgr;
int BestMoveChanges;
Value DrawValue[COLOR_NB];
- History H;
+ HistoryStats History;
+ GainsStats Gains;
+ CountermovesStats Countermoves;
template <NodeType NT>
- Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
template <NodeType NT, bool InCheck>
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
void id_loop(Position& pos);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta);
- bool yields_to_threat(const Position& pos, Move move, Move threat);
- bool prevents_threat(const Position& pos, Move move, Move threat);
+ bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta);
+ bool allows(const Position& pos, Move first, Move second);
+ bool refutes(const Position& pos, Move first, Move second);
string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
+ class stop : public std::exception {};
+
struct Skill {
Skill(int l) : level(l), best(MOVE_NONE) {}
~Skill() {
{
double pvRed = log(double(hd)) * log(double(mc)) / 3.0;
double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
- Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
- Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
+ Reductions[1][1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
+ Reductions[0][1][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
+
+ Reductions[1][0][hd][mc] = Reductions[1][1][hd][mc];
+ Reductions[0][0][hd][mc] = Reductions[0][1][hd][mc];
+
+ if (Reductions[0][0][hd][mc] > 2 * ONE_PLY)
+ Reductions[0][0][hd][mc] += ONE_PLY;
}
// Init futility margins array
// Init futility move count array
for (d = 0; d < 32; d++)
- FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(double(d), 2.0));
+ {
+ FutilityMoveCounts[1][d] = int(3.001 + 0.3 * pow(double(d), 1.8));
+ FutilityMoveCounts[0][d] = d < 5 ? FutilityMoveCounts[1][d]
+ : 3 * FutilityMoveCounts[1][d] / 4;
+ }
}
/// Search::perft() is our utility to verify move generation. All the leaf nodes
/// up to the given depth are generated and counted and the sum returned.
-size_t Search::perft(Position& pos, Depth depth) {
-
- // At the last ply just return the number of legal moves (leaf nodes)
- if (depth == ONE_PLY)
- return MoveList<LEGAL>(pos).size();
+static size_t perft(Position& pos, Depth depth) {
StateInfo st;
size_t cnt = 0;
CheckInfo ci(pos);
+ const bool leaf = depth == 2 * ONE_PLY;
- for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
+ for (MoveList<LEGAL> it(pos); *it; ++it)
{
- pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci));
- cnt += perft(pos, depth - ONE_PLY);
- pos.undo_move(ml.move());
+ pos.do_move(*it, st, ci, pos.move_gives_check(*it, ci));
+ cnt += leaf ? MoveList<LEGAL>(pos).size() : ::perft(pos, depth - ONE_PLY);
+ pos.undo_move(*it);
}
-
return cnt;
}
+size_t Search::perft(Position& pos, Depth depth) {
+ return depth > ONE_PLY ? ::perft(pos, depth) : MoveList<LEGAL>(pos).size();
+}
/// Search::think() is the external interface to Stockfish's search, and is
/// called by the main thread when the program receives the UCI 'go' command. It
static PolyglotBook book; // Defined static to initialize the PRNG only once
RootColor = RootPos.side_to_move();
- TimeMgr.init(Limits, RootPos.startpos_ply_counter(), RootColor);
+ TimeMgr.init(Limits, RootPos.game_ply(), RootColor);
if (RootMoves.empty())
{
RootMoves.push_back(MOVE_NONE);
sync_cout << "info depth 0 score "
- << score_to_uci(RootPos.in_check() ? -VALUE_MATE : VALUE_DRAW)
+ << score_to_uci(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
<< sync_endl;
goto finalize;
}
- if (Options["OwnBook"] && !Limits.infinite)
+ if (Options["OwnBook"] && !Limits.infinite && !Limits.mate)
{
Move bookMove = book.probe(RootPos, Options["Book File"], Options["Best Book Move"]);
if (Options["Contempt Factor"] && !Options["UCI_AnalyseMode"])
{
int cf = Options["Contempt Factor"] * PawnValueMg / 100; // From centipawns
- cf = cf * MaterialTable::game_phase(RootPos) / PHASE_MIDGAME; // Scale down with phase
+ cf = cf * Material::game_phase(RootPos) / PHASE_MIDGAME; // Scale down with phase
DrawValue[ RootColor] = VALUE_DRAW - Value(cf);
DrawValue[~RootColor] = VALUE_DRAW + Value(cf);
}
else
DrawValue[WHITE] = DrawValue[BLACK] = VALUE_DRAW;
- if (Options["Use Search Log"])
+ if (Options["Write Search Log"])
{
Log log(Options["Search Log Filename"]);
- log << "\nSearching: " << RootPos.to_fen()
+ log << "\nSearching: " << RootPos.fen()
<< "\ninfinite: " << Limits.infinite
<< " ponder: " << Limits.ponder
<< " time: " << Limits.time[RootColor]
<< std::endl;
}
- Threads.wake_up();
+ // Reset the threads, still sleeping: will be wake up at split time
+ for (size_t i = 0; i < Threads.size(); i++)
+ Threads[i]->maxPly = 0;
+
+ Threads.sleepWhileIdle = Options["Idle Threads Sleep"];
// Set best timer interval to avoid lagging under time pressure. Timer is
// used to check for remaining available thinking time.
- if (Limits.use_time_management())
- Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16,
- TimerResolution)));
- else if (Limits.nodes)
- Threads.set_timer(2 * TimerResolution);
- else
- Threads.set_timer(100);
+ Threads.timer->msec =
+ Limits.use_time_management() ? std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)) :
+ Limits.nodes ? 2 * TimerResolution
+ : 100;
+
+ Threads.timer->notify_one(); // Wake up the recurring timer
id_loop(RootPos); // Let's start searching !
- Threads.set_timer(0); // Stop timer
- Threads.sleep();
+ Threads.timer->msec = 0; // Stop the timer
+ Threads.sleepWhileIdle = true; // Send idle threads to sleep
- if (Options["Use Search Log"])
+ if (Options["Write Search Log"])
{
Time::point elapsed = Time::now() - SearchTime + 1;
finalize:
+ // When search is stopped this info is not printed
+ sync_cout << "info nodes " << RootPos.nodes_searched()
+ << " time " << Time::now() - SearchTime + 1 << sync_endl;
+
// When we reach max depth we arrive here even without Signals.stop is raised,
- // but if we are pondering or in infinite search, we shouldn't print the best
- // move before we are told to do so.
+ // but if we are pondering or in infinite search, according to UCI protocol,
+ // we shouldn't print the best move before the GUI sends a "stop" or "ponderhit"
+ // command. We simply wait here until GUI sends one of those commands (that
+ // raise Signals.stop).
if (!Signals.stop && (Limits.ponder || Limits.infinite))
- RootPos.this_thread()->wait_for_stop_or_ponderhit();
+ {
+ Signals.stopOnPonderhit = true;
+ RootPos.this_thread()->wait_for(Signals.stop);
+ }
// Best move could be MOVE_NONE when searching on a stalemate position
sync_cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], RootPos.is_chess960())
void id_loop(Position& pos) {
- Stack ss[MAX_PLY_PLUS_2];
+ Stack stack[MAX_PLY_PLUS_3], *ss = stack+2; // To allow referencing (ss-2)
int depth, prevBestMoveChanges;
Value bestValue, alpha, beta, delta;
- bool bestMoveNeverChanged = true;
- memset(ss, 0, 4 * sizeof(Stack));
+ std::memset(ss-2, 0, 5 * sizeof(Stack));
+ (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
+
depth = BestMoveChanges = 0;
- bestValue = delta = -VALUE_INFINITE;
- ss->currentMove = MOVE_NULL; // Hack to skip update gains
+ bestValue = delta = alpha = -VALUE_INFINITE;
+ beta = VALUE_INFINITE;
+
TT.new_search();
- H.clear();
+ History.clear();
+ Gains.clear();
+ Countermoves.clear();
PVSize = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
// MultiPV loop. We perform a full root search for each PV line
for (PVIdx = 0; PVIdx < PVSize; PVIdx++)
{
- // Set aspiration window default width
- if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN)
+ // Reset aspiration window starting size
+ if (depth >= 5)
{
delta = Value(16);
- alpha = RootMoves[PVIdx].prevScore - delta;
- beta = RootMoves[PVIdx].prevScore + delta;
- }
- else
- {
- alpha = -VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE);
+ beta = std::min(RootMoves[PVIdx].prevScore + delta, VALUE_INFINITE);
}
// Start with a small aspiration window and, in case of fail high/low,
// research with bigger window until not failing high/low anymore.
while (true)
{
- // Search starts from ss+1 to allow referencing (ss-1). This is
- // needed by update gains and ss copy when splitting at Root.
- bestValue = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+ try {
+ bestValue = search<Root>(pos, ss, alpha, beta, depth * ONE_PLY, false);
+ } catch (stop&) {}
// Bring to front the best move. It is critical that sorting is
// done with a stable algorithm because all the values but the first
// we want to keep the same order for all the moves but the new
// PV that goes to the front. Note that in case of MultiPV search
// the already searched PV lines are preserved.
- sort<RootMove>(RootMoves.begin() + PVIdx, RootMoves.end());
+ std::stable_sort(RootMoves.begin() + PVIdx, RootMoves.end());
// Write PV back to transposition table in case the relevant
// entries have been overwritten during the search.
if (Signals.stop)
return;
- // In case of failing high/low increase aspiration window and
- // research, otherwise exit the loop.
- if (bestValue > alpha && bestValue < beta)
- break;
-
- // Give some update (without cluttering the UI) before to research
- if (Time::now() - SearchTime > 3000)
+ // When failing high/low give some update (without cluttering
+ // the UI) before to research.
+ if ( (bestValue <= alpha || bestValue >= beta)
+ && Time::now() - SearchTime > 3000)
sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
- if (abs(bestValue) >= VALUE_KNOWN_WIN)
+ // In case of failing low/high increase aspiration window and
+ // research, otherwise exit the loop.
+ if (bestValue <= alpha)
{
- alpha = -VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ alpha = std::max(bestValue - delta, -VALUE_INFINITE);
+
+ Signals.failedLowAtRoot = true;
+ Signals.stopOnPonderhit = false;
}
else if (bestValue >= beta)
- {
- beta += delta;
- delta += delta / 2;
- }
+ beta = std::min(bestValue + delta, VALUE_INFINITE);
+
else
- {
- Signals.failedLowAtRoot = true;
- Signals.stopOnPonderhit = false;
+ break;
- alpha -= delta;
- delta += delta / 2;
- }
+ delta += delta / 2;
assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
}
// Sort the PV lines searched so far and update the GUI
- sort<RootMove>(RootMoves.begin(), RootMoves.begin() + PVIdx + 1);
- sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
+ std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1);
+
+ if (PVIdx + 1 == PVSize || Time::now() - SearchTime > 3000)
+ sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
}
// Do we need to pick now the sub-optimal best move ?
if (skill.enabled() && skill.time_to_pick(depth))
skill.pick_move();
- if (Options["Use Search Log"])
+ if (Options["Write Search Log"])
{
+ RootMove& rm = RootMoves[0];
+ if (skill.best != MOVE_NONE)
+ rm = *std::find(RootMoves.begin(), RootMoves.end(), skill.best);
+
Log log(Options["Search Log Filename"]);
- log << pretty_pv(pos, depth, bestValue, Time::now() - SearchTime, &RootMoves[0].pv[0])
+ log << pretty_pv(pos, depth, rm.score, Time::now() - SearchTime, &rm.pv[0])
<< std::endl;
}
- // Filter out startup noise when monitoring best move stability
- if (depth > 2 && BestMoveChanges)
- bestMoveNeverChanged = false;
+ // Do we have found a "mate in x"?
+ if ( Limits.mate
+ && bestValue >= VALUE_MATE_IN_MAX_PLY
+ && VALUE_MATE - bestValue <= 2 * Limits.mate)
+ Signals.stop = true;
// Do we have time for the next iteration? Can we stop searching now?
if (Limits.use_time_management() && !Signals.stopOnPonderhit)
if ( depth >= 12
&& !stop
&& PVSize == 1
- && ( (bestMoveNeverChanged && pos.captured_piece_type())
- || Time::now() - SearchTime > (TimeMgr.available_time() * 40) / 100))
+ && bestValue > VALUE_MATED_IN_MAX_PLY
+ && ( RootMoves.size() == 1
+ || Time::now() - SearchTime > (TimeMgr.available_time() * 20) / 100))
{
Value rBeta = bestValue - 2 * PawnValueMg;
- (ss+1)->excludedMove = RootMoves[0].pv[0];
- (ss+1)->skipNullMove = true;
- Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY);
- (ss+1)->skipNullMove = false;
- (ss+1)->excludedMove = MOVE_NONE;
+ ss->excludedMove = RootMoves[0].pv[0];
+ ss->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss, rBeta - 1, rBeta, (depth - 3) * ONE_PLY, true);
+ ss->skipNullMove = false;
+ ss->excludedMove = MOVE_NONE;
if (v < rBeta)
stop = true;
// here: This is taken care of after we return from the split point.
template <NodeType NT>
- Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {
const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
assert(PvNode || (alpha == beta - 1));
assert(depth > DEPTH_ZERO);
- Move movesSearched[64];
+ Move quietsSearched[64];
StateInfo st;
const TTEntry *tte;
- SplitPoint* sp;
+ SplitPoint* splitPoint;
Key posKey;
Move ttMove, move, excludedMove, bestMove, threatMove;
Depth ext, newDepth;
Value bestValue, value, ttValue;
Value eval, nullValue, futilityValue;
- CheckType givesCheck;
- bool inCheck, pvMove, singularExtensionNode;
+ bool inCheck, givesCheck, pvMove, singularExtensionNode, improving;
bool captureOrPromotion, dangerous, doFullDepthSearch;
- int moveCount, playedMoveCount;
+ int moveCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
- moveCount = playedMoveCount = 0;
- inCheck = pos.in_check();
+ inCheck = pos.checkers();
if (SpNode)
{
- sp = ss->sp;
- bestMove = sp->bestMove;
- threatMove = sp->threatMove;
- bestValue = sp->bestValue;
+ splitPoint = ss->splitPoint;
+ bestMove = splitPoint->bestMove;
+ threatMove = splitPoint->threatMove;
+ bestValue = splitPoint->bestValue;
tte = NULL;
ttMove = excludedMove = MOVE_NONE;
ttValue = VALUE_NONE;
- assert(sp->bestValue > -VALUE_INFINITE && sp->moveCount > 0);
+ assert(splitPoint->bestValue > -VALUE_INFINITE && splitPoint->moveCount > 0);
- goto split_point_start;
+ goto moves_loop;
}
+ moveCount = quietCount = 0;
bestValue = -VALUE_INFINITE;
ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
+ ss->futilityMoveCount = 0;
(ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
if (PvNode && thisThread->maxPly < ss->ply)
thisThread->maxPly = ss->ply;
+ if (Signals.stop || thisThread->cutoff_occurred())
+ throw stop();
+
if (!RootNode)
{
// Step 2. Check for aborted search and immediate draw
- if (Signals.stop || pos.is_draw<true, PvNode>() || ss->ply > MAX_PLY)
+ if (pos.is_draw() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
// Step 3. Mate distance pruning. Even if we mate at the next move our score
&& tte
&& tte->depth() >= depth
&& ttValue != VALUE_NONE // Only in case of TT access race
- && ( PvNode ? tte->type() == BOUND_EXACT
- : ttValue >= beta ? (tte->type() & BOUND_LOWER)
- : (tte->type() & BOUND_UPPER)))
+ && ( PvNode ? tte->bound() == BOUND_EXACT
+ : ttValue >= beta ? (tte->bound() & BOUND_LOWER)
+ : (tte->bound() & BOUND_UPPER)))
{
TT.refresh(tte);
ss->currentMove = ttMove; // Can be MOVE_NONE
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
+ {
ss->staticEval = ss->evalMargin = eval = VALUE_NONE;
+ goto moves_loop;
+ }
else if (tte)
{
- // Following asserts are valid only in single thread condition because
- // TT access is always racy and its contents cannot be trusted.
- assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
- assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE || Threads.size() > 1);
-
- ss->staticEval = eval = tte->static_value();
- ss->evalMargin = tte->static_value_margin();
-
- if (eval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race
+ // Never assume anything on values stored in TT
+ if ( (ss->staticEval = eval = tte->eval_value()) == VALUE_NONE
+ ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE)
eval = ss->staticEval = evaluate(pos, ss->evalMargin);
// Can ttValue be used as a better position evaluation?
if (ttValue != VALUE_NONE)
- if ( ((tte->type() & BOUND_LOWER) && ttValue > eval)
- || ((tte->type() & BOUND_UPPER) && ttValue < eval))
+ if ( ((tte->bound() & BOUND_LOWER) && ttValue > eval)
+ || ((tte->bound() & BOUND_UPPER) && ttValue < eval))
eval = ttValue;
}
else
// Update gain for the parent non-capture move given the static position
// evaluation before and after the move.
- if ( (move = (ss-1)->currentMove) != MOVE_NULL
- && (ss-1)->staticEval != VALUE_NONE
+ if ( !pos.captured_piece_type()
&& ss->staticEval != VALUE_NONE
- && !pos.captured_piece_type()
+ && (ss-1)->staticEval != VALUE_NONE
+ && (move = (ss-1)->currentMove) != MOVE_NULL
&& type_of(move) == NORMAL)
{
Square to = to_sq(move);
- H.update_gain(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
+ Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
}
- // Step 6. Razoring (is omitted in PV nodes)
+ // Step 6. Razoring (skipped when in check)
if ( !PvNode
&& depth < 4 * ONE_PLY
- && !inCheck
&& eval + razor_margin(depth) < beta
&& ttMove == MOVE_NONE
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
return v;
}
- // Step 7. Static null move pruning (is omitted in PV nodes)
+ // Step 7. Static null move pruning (skipped when in check)
// We're betting that the opponent doesn't have a move that will reduce
// the score by more than futility_margin(depth) if we do a null move.
if ( !PvNode
&& !ss->skipNullMove
&& depth < 4 * ONE_PLY
- && !inCheck
- && eval - FutilityMargins[depth][0] >= beta
+ && eval - futility_margin(depth, (ss-1)->futilityMoveCount) >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
+ && abs(eval) < VALUE_KNOWN_WIN
&& pos.non_pawn_material(pos.side_to_move()))
- return eval - FutilityMargins[depth][0];
+ return eval - futility_margin(depth, (ss-1)->futilityMoveCount);
// Step 8. Null move search with verification search (is omitted in PV nodes)
if ( !PvNode
&& !ss->skipNullMove
&& depth > ONE_PLY
- && !inCheck
&& eval >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
&& pos.non_pawn_material(pos.side_to_move()))
if (eval - PawnValueMg > beta)
R += ONE_PLY;
- pos.do_null_move<true>(st);
+ pos.do_null_move(st);
(ss+1)->skipNullMove = true;
nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R);
+ : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R, !cutNode);
(ss+1)->skipNullMove = false;
- pos.do_null_move<false>(st);
+ pos.undo_null_move();
if (nullValue >= beta)
{
if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta;
- if (depth < 6 * ONE_PLY)
+ if (depth < 12 * ONE_PLY)
return nullValue;
// Do verification search at high depths
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, alpha, beta, depth-R);
+ Value v = search<NonPV>(pos, ss, alpha, beta, depth-R, false);
ss->skipNullMove = false;
if (v >= beta)
if ( depth < 5 * ONE_PLY
&& (ss-1)->reduction
&& threatMove != MOVE_NONE
- && yields_to_threat(pos, (ss-1)->currentMove, threatMove))
- return beta - 1;
+ && allows(pos, (ss-1)->currentMove, threatMove))
+ return alpha;
}
}
- // Step 9. ProbCut (is omitted in PV nodes)
+ // Step 9. ProbCut (skipped when in check)
// If we have a very good capture (i.e. SEE > seeValues[captured_piece_type])
// and a reduced search returns a value much above beta, we can (almost) safely
// prune the previous move.
if ( !PvNode
&& depth >= 5 * ONE_PLY
- && !inCheck
&& !ss->skipNullMove
- && excludedMove == MOVE_NONE
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
Value rbeta = beta + 200;
assert((ss-1)->currentMove != MOVE_NONE);
assert((ss-1)->currentMove != MOVE_NULL);
- MovePicker mp(pos, ttMove, H, pos.captured_piece_type());
+ MovePicker mp(pos, ttMove, History, pos.captured_piece_type());
CheckInfo ci(pos);
while ((move = mp.next_move<false>()) != MOVE_NONE)
{
ss->currentMove = move;
pos.do_move(move, st, ci, pos.move_gives_check(move, ci));
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth);
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
pos.undo_move(move);
if (value >= rbeta)
return value;
}
}
- // Step 10. Internal iterative deepening
+ // Step 10. Internal iterative deepening (skipped when in check)
if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY)
&& ttMove == MOVE_NONE
- && (PvNode || (!inCheck && ss->staticEval + Value(256) >= beta)))
+ && (PvNode || ss->staticEval + Value(256) >= beta))
{
- Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
+ Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
ss->skipNullMove = true;
- search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d);
+ search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d, true);
ss->skipNullMove = false;
tte = TT.probe(posKey);
ttMove = tte ? tte->move() : MOVE_NONE;
}
-split_point_start: // At split points actual search starts from here
+moves_loop: // When in check and at SpNode search starts from here
+
+ Square prevMoveSq = to_sq((ss-1)->currentMove);
+ Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first,
+ Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second };
- MovePicker mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta);
+ MovePicker mp(pos, ttMove, depth, History, countermoves, ss);
CheckInfo ci(pos);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
+ improving = ss->staticEval >= (ss-2)->staticEval
+ || ss->staticEval == VALUE_NONE
+ ||(ss-2)->staticEval == VALUE_NONE;
+
singularExtensionNode = !RootNode
&& !SpNode
&& depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY)
&& ttMove != MOVE_NONE
&& !excludedMove // Recursive singular search is not allowed
- && (tte->type() & BOUND_LOWER)
+ && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
// Step 11. Loop through moves
if (!pos.pl_move_is_legal(move, ci.pinned))
continue;
- moveCount = ++sp->moveCount;
- sp->mutex.unlock();
+ moveCount = ++splitPoint->moveCount;
+ splitPoint->mutex.unlock();
}
else
moveCount++;
{
Signals.firstRootMove = (moveCount == 1);
- if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 2000)
+ if (thisThread == Threads.main() && Time::now() - SearchTime > 3000)
sync_cout << "info depth " << depth / ONE_PLY
<< " currmove " << move_to_uci(move, pos.is_chess960())
<< " currmovenumber " << moveCount + PVIdx << sync_endl;
givesCheck = pos.move_gives_check(move, ci);
dangerous = givesCheck
|| pos.is_passed_pawn_push(move)
- || type_of(move) == CASTLE
- || ( captureOrPromotion // Entering a pawn endgame?
- && type_of(pos.piece_on(to_sq(move))) != PAWN
- && type_of(move) == NORMAL
- && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- - PieceValue[MG][pos.piece_on(to_sq(move))] == VALUE_ZERO));
+ || type_of(move) == CASTLE;
// Step 12. Extend checks and, in PV nodes, also dangerous moves
if (PvNode && dangerous)
ext = ONE_PLY;
- else if (givesCheck && (givesCheck == DISCO_CHECK || pos.see_sign(move) >= 0))
+ else if (givesCheck && pos.see_sign(move) >= 0)
ext = ONE_PLY / 2;
// Singular extension search. If all moves but one fail low on a search of
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
if (value < rBeta)
- ext = rBeta >= beta ? ONE_PLY + ONE_PLY / 2 : ONE_PLY;
+ ext = ONE_PLY;
}
// Update current move (this must be done after singular extension search)
&& !captureOrPromotion
&& !inCheck
&& !dangerous
- && move != ttMove
- && (bestValue > VALUE_MATED_IN_MAX_PLY || ( bestValue == -VALUE_INFINITE
- && alpha > VALUE_MATED_IN_MAX_PLY)))
+ /* && move != ttMove Already implicit in the next condition */
+ && bestValue > VALUE_MATED_IN_MAX_PLY)
{
// Move count based pruning
if ( depth < 16 * ONE_PLY
- && moveCount >= FutilityMoveCounts[depth]
- && (!threatMove || !prevents_threat(pos, move, threatMove)))
+ && moveCount >= FutilityMoveCounts[improving][depth]
+ && (!threatMove || !refutes(pos, move, threatMove)))
{
if (SpNode)
- sp->mutex.lock();
+ splitPoint->mutex.lock();
continue;
}
// Value based pruning
// We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth,
// but fixing this made program slightly weaker.
- Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
+ Depth predictedDepth = newDepth - reduction<PvNode>(improving, depth, moveCount);
futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount)
- + H.gain(pos.piece_moved(move), to_sq(move));
+ + Gains[pos.piece_moved(move)][to_sq(move)];
if (futilityValue < beta)
{
- if (SpNode)
- sp->mutex.lock();
+ bestValue = std::max(bestValue, futilityValue);
+ if (SpNode)
+ {
+ splitPoint->mutex.lock();
+ if (bestValue > splitPoint->bestValue)
+ splitPoint->bestValue = bestValue;
+ }
continue;
}
// Prune moves with negative SEE at low depths
- if ( predictedDepth < 2 * ONE_PLY
- && givesCheck != DISCO_CHECK
+ if ( predictedDepth < 4 * ONE_PLY
&& pos.see_sign(move) < 0)
{
if (SpNode)
- sp->mutex.lock();
+ splitPoint->mutex.lock();
continue;
}
+
+ // We have not pruned the move that will be searched, but remember how
+ // far in the move list we are to be more aggressive in the child node.
+ ss->futilityMoveCount = moveCount;
}
+ else
+ ss->futilityMoveCount = 0;
// Check for legality only before to do the move
- if (!pos.pl_move_is_legal(move, ci.pinned))
+ if (!RootNode && !SpNode && !pos.pl_move_is_legal(move, ci.pinned))
{
moveCount--;
continue;
}
- pvMove = PvNode ? moveCount == 1 : false;
+ pvMove = PvNode && moveCount == 1;
ss->currentMove = move;
- if (!SpNode && !captureOrPromotion && playedMoveCount < 64)
- movesSearched[playedMoveCount++] = move;
+ if (!SpNode && !captureOrPromotion && quietCount < 64)
+ quietsSearched[quietCount++] = move;
// Step 14. Make the move
pos.do_move(move, st, ci, givesCheck);
&& !pvMove
&& !captureOrPromotion
&& !dangerous
- && ss->killers[0] != move
- && ss->killers[1] != move)
+ && move != ttMove
+ && move != ss->killers[0]
+ && move != ss->killers[1])
{
- ss->reduction = reduction<PvNode>(depth, moveCount);
+ ss->reduction = reduction<PvNode>(improving, depth, moveCount);
+
+ if (!PvNode && cutNode)
+ ss->reduction += ONE_PLY;
+
+ if (move == countermoves[0] || move == countermoves[1])
+ ss->reduction = std::max(DEPTH_ZERO, ss->reduction-ONE_PLY);
+
Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
- alpha = SpNode ? sp->alpha : alpha;
+ if (SpNode)
+ alpha = splitPoint->alpha;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
ss->reduction = DEPTH_ZERO;
// Step 16. Full depth search, when LMR is skipped or fails high
if (doFullDepthSearch)
{
- alpha = SpNode ? sp->alpha : alpha;
+ if (SpNode)
+ alpha = splitPoint->alpha;
+
value = newDepth < ONE_PLY ?
givesCheck ? -qsearch<NonPV, true>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
: -qsearch<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
}
// Only for PV nodes do a full PV search on the first move or after a fail
value = newDepth < ONE_PLY ?
givesCheck ? -qsearch<PV, true>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
: -qsearch<PV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);
// Step 17. Undo move
pos.undo_move(move);
// Step 18. Check for new best move
if (SpNode)
{
- sp->mutex.lock();
- bestValue = sp->bestValue;
- alpha = sp->alpha;
+ splitPoint->mutex.lock();
+ bestValue = splitPoint->bestValue;
+ alpha = splitPoint->alpha;
}
- // Finished searching the move. If Signals.stop is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we don't update the best move and/or PV.
- if (Signals.stop || thisThread->cutoff_occurred())
- return value; // To avoid returning VALUE_INFINITE
-
if (RootNode)
{
RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move);
if (value > bestValue)
{
- bestValue = value;
- if (SpNode) sp->bestValue = value;
+ bestValue = SpNode ? splitPoint->bestValue = value : value;
if (value > alpha)
{
- bestMove = move;
- if (SpNode) sp->bestMove = move;
+ bestMove = SpNode ? splitPoint->bestMove = move : move;
- if (PvNode && value < beta)
+ if (PvNode && value < beta) // Update alpha! Always alpha < beta
+ alpha = SpNode ? splitPoint->alpha = value : value;
+ else
{
- alpha = value; // Update alpha here! Always alpha < beta
- if (SpNode) sp->alpha = value;
- }
- else // Fail high
- {
- if (SpNode) sp->cutoff = true;
+ assert(value >= beta); // Fail high
+
+ if (SpNode)
+ splitPoint->cutoff = true;
+
break;
}
}
// Step 19. Check for splitting the search
if ( !SpNode
- && depth >= Threads.min_split_depth()
- && bestValue < beta
- && Threads.available_slave_exists(thisThread))
+ && depth >= Threads.minimumSplitDepth
+ && Threads.available_slave(thisThread)
+ && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD)
{
- bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, &bestMove,
- depth, threatMove, moveCount, mp, NT);
+ assert(bestValue < beta);
+
+ thisThread->split<FakeSplit>(pos, ss, alpha, beta, &bestValue, &bestMove,
+ depth, threatMove, moveCount, &mp, NT, cutNode);
if (bestValue >= beta)
break;
}
// If we have pruned all the moves without searching return a fail-low score
if (bestValue == -VALUE_INFINITE)
- {
- assert(!playedMoveCount);
-
bestValue = alpha;
- }
- if (bestValue >= beta) // Failed high
+ TT.store(posKey, value_to_tt(bestValue, ss->ply),
+ bestValue >= beta ? BOUND_LOWER :
+ PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
+ depth, bestMove, ss->staticEval, ss->evalMargin);
+
+ // Quiet best move: update killers, history and countermoves
+ if ( bestValue >= beta
+ && !pos.is_capture_or_promotion(bestMove)
+ && !inCheck)
{
- TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth,
- bestMove, ss->staticEval, ss->evalMargin);
-
- if (!pos.is_capture_or_promotion(bestMove) && !inCheck)
+ if (ss->killers[0] != bestMove)
{
- if (bestMove != ss->killers[0])
- {
- ss->killers[1] = ss->killers[0];
- ss->killers[0] = bestMove;
- }
-
- // Increase history value of the cut-off move
- Value bonus = Value(int(depth) * int(depth));
- H.add(pos.piece_moved(bestMove), to_sq(bestMove), bonus);
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = bestMove;
+ }
- // Decrease history of all the other played non-capture moves
- for (int i = 0; i < playedMoveCount - 1; i++)
- {
- Move m = movesSearched[i];
- H.add(pos.piece_moved(m), to_sq(m), -bonus);
- }
+ // Increase history value of the cut-off move and decrease all the other
+ // played non-capture moves.
+ Value bonus = Value(int(depth) * int(depth));
+ History.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus);
+ for (int i = 0; i < quietCount - 1; i++)
+ {
+ Move m = quietsSearched[i];
+ History.update(pos.piece_moved(m), to_sq(m), -bonus);
}
+
+ if (is_ok((ss-1)->currentMove))
+ Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, bestMove);
}
- else // Failed low or PV search
- TT.store(posKey, value_to_tt(bestValue, ss->ply),
- PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER,
- depth, bestMove, ss->staticEval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
const bool PvNode = (NT == PV);
assert(NT == PV || NT == NonPV);
- assert(InCheck == pos.in_check());
+ assert(InCheck == !!pos.checkers());
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
const TTEntry* tte;
Key posKey;
Move ttMove, move, bestMove;
- Value bestValue, value, ttValue, futilityValue, futilityBase;
- CheckType givesCheck;
- bool enoughMaterial, evasionPrunable, fromNull;
+ Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
+ bool givesCheck, evasionPrunable;
Depth ttDepth;
+ // To flag BOUND_EXACT a node with eval above alpha and no available moves
+ if (PvNode)
+ oldAlpha = alpha;
+
ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
- fromNull = (ss-1)->currentMove == MOVE_NULL;
// Check for an instant draw or maximum ply reached
- if (pos.is_draw<false, false>() || ss->ply > MAX_PLY)
+ if (pos.is_draw() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
- // Transposition table lookup. At PV nodes, we don't use the TT for
- // pruning, but only for move ordering.
- posKey = pos.key();
- tte = TT.probe(posKey);
- ttMove = tte ? tte->move() : MOVE_NONE;
- ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
-
// Decide whether or not to include checks, this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
: DEPTH_QS_NO_CHECKS;
+
+ // Transposition table lookup
+ posKey = pos.key();
+ tte = TT.probe(posKey);
+ ttMove = tte ? tte->move() : MOVE_NONE;
+ ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
+
if ( tte
&& tte->depth() >= ttDepth
&& ttValue != VALUE_NONE // Only in case of TT access race
- && ( PvNode ? tte->type() == BOUND_EXACT
- : ttValue >= beta ? (tte->type() & BOUND_LOWER)
- : (tte->type() & BOUND_UPPER)))
+ && ( PvNode ? tte->bound() == BOUND_EXACT
+ : ttValue >= beta ? (tte->bound() & BOUND_LOWER)
+ : (tte->bound() & BOUND_UPPER)))
{
ss->currentMove = ttMove; // Can be MOVE_NONE
return ttValue;
{
ss->staticEval = ss->evalMargin = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
- enoughMaterial = false;
}
else
{
- if (fromNull)
+ if (tte)
{
- ss->staticEval = bestValue = -(ss-1)->staticEval;
- ss->evalMargin = VALUE_ZERO;
- }
- else if (tte)
- {
- assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
-
- ss->staticEval = bestValue = tte->static_value();
- ss->evalMargin = tte->static_value_margin();
-
- if (ss->staticEval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race
+ // Never assume anything on values stored in TT
+ if ( (ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE
+ ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE)
ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
}
else
alpha = bestValue;
futilityBase = ss->staticEval + ss->evalMargin + Value(128);
- enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg;
}
// 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 >= DEPTH_QS_CHECKS) will
// be generated.
- MovePicker mp(pos, ttMove, depth, H, to_sq((ss-1)->currentMove));
+ MovePicker mp(pos, ttMove, depth, History, to_sq((ss-1)->currentMove));
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
if ( !PvNode
&& !InCheck
&& !givesCheck
- && !fromNull
&& move != ttMove
- && enoughMaterial
&& type_of(move) != PROMOTION
&& !pos.is_passed_pawn_push(move))
{
if (futilityValue < beta)
{
- if (futilityValue > bestValue)
- bestValue = futilityValue;
-
+ bestValue = std::max(bestValue, futilityValue);
continue;
}
- // Prune moves with negative or equal SEE
+ // Prune moves with negative or equal SEE and also moves with positive
+ // SEE where capturing piece loses a tempo and SEE < beta - futilityBase.
if ( futilityBase < beta
- && depth < DEPTH_ZERO
- && pos.see(move) <= 0)
+ && pos.see(move, beta - futilityBase) <= 0)
+ {
+ bestValue = std::max(bestValue, futilityBase);
continue;
+ }
}
// Detect non-capture evasions that are candidate to be pruned
- evasionPrunable = !PvNode
- && InCheck
+ evasionPrunable = InCheck
&& bestValue > VALUE_MATED_IN_MAX_PLY
&& !pos.is_capture(move)
&& !pos.can_castle(pos.side_to_move());
if ( !PvNode
&& (!InCheck || evasionPrunable)
&& move != ttMove
- && givesCheck != DISCO_CHECK
&& type_of(move) != PROMOTION
&& pos.see_sign(move) < 0)
continue;
return mated_in(ss->ply); // Plies to mate from the root
TT.store(posKey, value_to_tt(bestValue, ss->ply),
- PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER,
+ PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
ttDepth, bestMove, ss->staticEval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// check_is_dangerous() tests if a checking move can be pruned in qsearch()
- bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta)
+ bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta)
{
Piece pc = pos.piece_moved(move);
Square from = from_sq(move);
}
- // yields_to_threat() tests whether the move at previous ply yields to the so
- // called threat move (the best move returned from a null search that fails
- // low). Here 'yields to' means that the move somehow made the threat possible
- // for instance if the moving piece is the same in both moves.
+ // allows() tests whether the 'first' move at previous ply somehow makes the
+ // 'second' move possible, for instance if the moving piece is the same in
+ // both moves. Normally the second move is the threat (the best move returned
+ // from a null search that fails low).
- bool yields_to_threat(const Position& pos, Move move, Move threat) {
+ bool allows(const Position& pos, Move first, Move second) {
- assert(is_ok(move));
- assert(is_ok(threat));
- assert(color_of(pos.piece_on(from_sq(threat))) == ~pos.side_to_move());
+ assert(is_ok(first));
+ assert(is_ok(second));
+ assert(color_of(pos.piece_on(from_sq(second))) == ~pos.side_to_move());
+ assert(color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move());
- Square mfrom = from_sq(move);
- Square mto = to_sq(move);
- Square tfrom = from_sq(threat);
- Square tto = to_sq(threat);
+ Square m1from = from_sq(first);
+ Square m2from = from_sq(second);
+ Square m1to = to_sq(first);
+ Square m2to = to_sq(second);
- // The piece is the same or threat's destination was vacated by the move
- if (mto == tfrom || tto == mfrom)
+ // The piece is the same or second's destination was vacated by the first move
+ if (m1to == m2from || m2to == m1from)
return true;
- // Threat moves through the vacated square
- if (between_bb(tfrom, tto) & mfrom)
+ // Second one moves through the square vacated by first one
+ if (between_bb(m2from, m2to) & m1from)
return true;
- // Threat's destination is defended by the move's piece
- Bitboard matt = pos.attacks_from(pos.piece_on(mto), mto, pos.pieces() ^ tfrom);
- if (matt & tto)
+ // Second's destination is defended by the first move's piece
+ Bitboard m1att = pos.attacks_from(pos.piece_on(m1to), m1to, pos.pieces() ^ m2from);
+ if (m1att & m2to)
return true;
- // Threat gives a discovered check through the move's checking piece
- if (matt & pos.king_square(pos.side_to_move()))
+ // Second move gives a discovered check through the first's checking piece
+ if (m1att & pos.king_square(pos.side_to_move()))
{
- assert(between_bb(mto, pos.king_square(pos.side_to_move())) & tfrom);
+ assert(between_bb(m1to, pos.king_square(pos.side_to_move())) & m2from);
return true;
}
}
- // prevents_threat() tests whether a move is able to defend against the so
- // called threat move (the best move returned from a null search that fails
- // low). In this case will not be pruned.
+ // refutes() tests whether a 'first' move is able to defend against a 'second'
+ // opponent's move. In this case will not be pruned. Normally the second move
+ // is the threat (the best move returned from a null search that fails low).
- bool prevents_threat(const Position& pos, Move move, Move threat) {
+ bool refutes(const Position& pos, Move first, Move second) {
- assert(is_ok(move));
- assert(is_ok(threat));
- assert(!pos.is_capture_or_promotion(move));
- assert(!pos.is_passed_pawn_push(move));
+ assert(is_ok(first));
+ assert(is_ok(second));
- Square mfrom = from_sq(move);
- Square mto = to_sq(move);
- Square tfrom = from_sq(threat);
- Square tto = to_sq(threat);
+ Square m1from = from_sq(first);
+ Square m2from = from_sq(second);
+ Square m1to = to_sq(first);
+ Square m2to = to_sq(second);
// Don't prune moves of the threatened piece
- if (mfrom == tto)
+ if (m1from == m2to)
return true;
// If the threatened piece has value less than or equal to the value of the
// threat piece, don't prune moves which defend it.
- if ( pos.is_capture(threat)
- && ( PieceValue[MG][pos.piece_on(tfrom)] >= PieceValue[MG][pos.piece_on(tto)]
- || type_of(pos.piece_on(tfrom)) == KING))
+ if ( pos.is_capture(second)
+ && ( PieceValue[MG][pos.piece_on(m2from)] >= PieceValue[MG][pos.piece_on(m2to)]
+ || type_of(pos.piece_on(m2from)) == KING))
{
// Update occupancy as if the piece and the threat are moving
- Bitboard occ = pos.pieces() ^ mfrom ^ mto ^ tfrom;
- Piece piece = pos.piece_on(mfrom);
+ Bitboard occ = pos.pieces() ^ m1from ^ m1to ^ m2from;
+ Piece pc = pos.piece_on(m1from);
// The moved piece attacks the square 'tto' ?
- if (pos.attacks_from(piece, mto, occ) & tto)
+ if (pos.attacks_from(pc, m1to, occ) & m2to)
return true;
// Scan for possible X-ray attackers behind the moved piece
- Bitboard xray = (attacks_bb< ROOK>(tto, occ) & pos.pieces(color_of(piece), QUEEN, ROOK))
- | (attacks_bb<BISHOP>(tto, occ) & pos.pieces(color_of(piece), QUEEN, BISHOP));
+ Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(pc), QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(m2to, occ) & pos.pieces(color_of(pc), QUEEN, BISHOP));
// Verify attackers are triggered by our move and not already existing
- if (xray && (xray ^ (xray & pos.attacks_from<QUEEN>(tto))))
+ if (unlikely(xray) && (xray & ~pos.attacks_from<QUEEN>(m2to)))
return true;
}
// Don't prune safe moves which block the threat path
- if ((between_bb(tfrom, tto) & mto) && pos.see_sign(move) >= 0)
+ if ((between_bb(m2from, m2to) & m1to) && pos.see_sign(first) >= 0)
return true;
return false;
string uci_pv(const Position& pos, int depth, Value alpha, Value beta) {
std::stringstream s;
- Time::point elaspsed = Time::now() - SearchTime + 1;
+ Time::point elapsed = Time::now() - SearchTime + 1;
size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size());
int selDepth = 0;
for (size_t i = 0; i < Threads.size(); i++)
- if (Threads[i].maxPly > selDepth)
- selDepth = Threads[i].maxPly;
+ if (Threads[i]->maxPly > selDepth)
+ selDepth = Threads[i]->maxPly;
for (size_t i = 0; i < uciPVSize; i++)
{
<< " seldepth " << selDepth
<< " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
<< " nodes " << pos.nodes_searched()
- << " nps " << pos.nodes_searched() * 1000 / elaspsed
- << " time " << elaspsed
+ << " nps " << pos.nodes_searched() * 1000 / elapsed
+ << " time " << elapsed
<< " multipv " << i + 1
<< " pv";
void RootMove::extract_pv_from_tt(Position& pos) {
- StateInfo state[MAX_PLY_PLUS_2], *st = state;
- TTEntry* tte;
+ StateInfo state[MAX_PLY_PLUS_3], *st = state;
+ const TTEntry* tte;
int ply = 0;
Move m = pv[0];
do {
pv.push_back(m);
- assert(pos.move_is_legal(pv[ply]));
+ assert(MoveList<LEGAL>(pos).contains(pv[ply]));
+
pos.do_move(pv[ply++], *st++);
tte = TT.probe(pos.key());
&& pos.is_pseudo_legal(m = tte->move()) // Local copy, TT could change
&& pos.pl_move_is_legal(m, pos.pinned_pieces())
&& ply < MAX_PLY
- && (!pos.is_draw<true, true>() || ply < 2));
+ && (!pos.is_draw() || ply < 2));
pv.push_back(MOVE_NONE); // Must be zero-terminating
void RootMove::insert_pv_in_tt(Position& pos) {
- StateInfo state[MAX_PLY_PLUS_2], *st = state;
- TTEntry* tte;
+ StateInfo state[MAX_PLY_PLUS_3], *st = state;
+ const TTEntry* tte;
int ply = 0;
- Value v, m;
do {
tte = TT.probe(pos.key());
if (!tte || tte->move() != pv[ply]) // Don't overwrite correct entries
- {
- if (pos.in_check())
- v = m = VALUE_NONE;
- else
- v = evaluate(pos, m);
+ TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], VALUE_NONE, VALUE_NONE);
- TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], v, m);
- }
+ assert(MoveList<LEGAL>(pos).contains(pv[ply]));
- assert(pos.move_is_legal(pv[ply]));
pos.do_move(pv[ply++], *st++);
} while (pv[ply] != MOVE_NONE);
void Thread::idle_loop() {
- // Pointer 'sp_master', if non-NULL, points to the active SplitPoint
- // object for which the thread is the master.
- const SplitPoint* sp_master = splitPointsCnt ? curSplitPoint : NULL;
+ // Pointer 'this_sp' is not null only if we are called from split(), and not
+ // at the thread creation. So it means we are the split point's master.
+ SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL;
- assert(!sp_master || (sp_master->master == this && is_searching));
+ assert(!this_sp || (this_sp->masterThread == this && searching));
- // If this thread is the master of a split point and all slaves have
- // finished their work at this split point, return from the idle loop.
- while (!sp_master || sp_master->slavesMask)
+ while (true)
{
- // If we are not searching, wait for a condition to be signaled
- // instead of wasting CPU time polling for work.
- while ( do_sleep
- || do_exit
- || (!is_searching && Threads.use_sleeping_threads()))
+ // If we are not searching, wait for a condition to be signaled instead of
+ // wasting CPU time polling for work.
+ while ((!searching && Threads.sleepWhileIdle) || exit)
{
- if (do_exit)
+ if (exit)
{
- assert(!sp_master);
+ assert(!this_sp);
return;
}
- // Grab the lock to avoid races with Thread::wake_up()
+ // Grab the lock to avoid races with Thread::notify_one()
mutex.lock();
- // If we are master and all slaves have finished don't go to sleep
- if (sp_master && !sp_master->slavesMask)
+ // If we are master and all slaves have finished then exit idle_loop
+ if (this_sp && !this_sp->slavesMask)
{
mutex.unlock();
break;
// Do sleep after retesting sleep conditions under lock protection, in
// particular we need to avoid a deadlock in case a master thread has,
- // in the meanwhile, allocated us and sent the wake_up() call before we
- // had the chance to grab the lock.
- if (do_sleep || !is_searching)
+ // in the meanwhile, allocated us and sent the notify_one() call before
+ // we had the chance to grab the lock.
+ if (!searching && !exit)
sleepCondition.wait(mutex);
mutex.unlock();
}
// If this thread has been assigned work, launch a search
- if (is_searching)
+ if (searching)
{
- assert(!do_sleep && !do_exit);
+ assert(!exit);
Threads.mutex.lock();
- assert(is_searching);
- SplitPoint* sp = curSplitPoint;
+ assert(searching);
+ assert(activeSplitPoint);
+ SplitPoint* sp = activeSplitPoint;
Threads.mutex.unlock();
- Stack ss[MAX_PLY_PLUS_2];
+ Stack stack[MAX_PLY_PLUS_3], *ss = stack+2; // To allow referencing (ss-2)
Position pos(*sp->pos, this);
- memcpy(ss, sp->ss - 1, 4 * sizeof(Stack));
- (ss+1)->sp = sp;
+ std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));
+ ss->splitPoint = sp;
sp->mutex.lock();
- assert(sp->activePositions[idx] == NULL);
+ assert(activePosition == NULL);
- sp->activePositions[idx] = &pos;
+ activePosition = &pos;
- if (sp->nodeType == Root)
- search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
- else if (sp->nodeType == PV)
- search<SplitPointPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
- else if (sp->nodeType == NonPV)
- search<SplitPointNonPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
- else
- assert(false);
+ try {
+ switch (sp->nodeType) {
+ case Root:
+ search<SplitPointRoot>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
+ break;
+ case PV:
+ search<SplitPointPV>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
+ break;
+ case NonPV:
+ search<SplitPointNonPV>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
+ break;
+ default:
+ assert(false);
+ }
- assert(is_searching);
+ assert(searching);
+ }
+ catch (stop&) {
+ sp->mutex.lock(); // Exception is thrown out of lock
+ }
- is_searching = false;
- sp->activePositions[idx] = NULL;
+ searching = false;
+ activePosition = NULL;
sp->slavesMask &= ~(1ULL << idx);
sp->nodes += pos.nodes_searched();
- // Wake up master thread so to allow it to return from the idle loop in
- // case we are the last slave of the split point.
- if ( Threads.use_sleeping_threads()
- && this != sp->master
+ // Wake up master thread so to allow it to return from the idle loop
+ // in case we are the last slave of the split point.
+ if ( Threads.sleepWhileIdle
+ && this != sp->masterThread
&& !sp->slavesMask)
{
- assert(!sp->master->is_searching);
- sp->master->wake_up();
+ assert(!sp->masterThread->searching);
+ sp->masterThread->notify_one();
}
// After releasing the lock we cannot access anymore any SplitPoint
// unsafe because if we are exiting there is a chance are already freed.
sp->mutex.unlock();
}
+
+ // If this thread is the master of a split point and all slaves have finished
+ // their work at this split point, return from the idle loop.
+ if (this_sp && !this_sp->slavesMask)
+ {
+ this_sp->mutex.lock();
+ bool finished = !this_sp->slavesMask; // Retest under lock protection
+ this_sp->mutex.unlock();
+ if (finished)
+ return;
+ }
}
}
nodes = RootPos.nodes_searched();
// Loop across all split points and sum accumulated SplitPoint nodes plus
- // all the currently active slaves positions.
+ // all the currently active positions nodes.
for (size_t i = 0; i < Threads.size(); i++)
- for (int j = 0; j < Threads[i].splitPointsCnt; j++)
+ for (int j = 0; j < Threads[i]->splitPointsSize; j++)
{
- SplitPoint& sp = Threads[i].splitPoints[j];
+ SplitPoint& sp = Threads[i]->splitPoints[j];
sp.mutex.lock();
Bitboard sm = sp.slavesMask;
while (sm)
{
- Position* pos = sp.activePositions[pop_lsb(&sm)];
- nodes += pos ? pos->nodes_searched() : 0;
+ Position* pos = Threads[pop_lsb(&sm)]->activePosition;
+ if (pos)
+ nodes += pos->nodes_searched();
}
sp.mutex.unlock();
projects / stockfish / blobdiff