#include <iostream>
#include <sstream>
-#include "book.h"
#include "evaluate.h"
#include "movegen.h"
#include "movepick.h"
#include "notation.h"
+#include "rkiss.h"
#include "search.h"
#include "timeman.h"
#include "thread.h"
LimitsType Limits;
std::vector<RootMove> RootMoves;
Position RootPos;
- Color RootColor;
Time::point SearchTime;
StateStackPtr SetupStates;
- Value Contempt[2]; // [bestValue > VALUE_DRAW]
}
using std::string;
const bool FakeSplit = false;
// Different node types, used as template parameter
- enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
+ enum NodeType { Root, PV, NonPV };
// Dynamic razoring margin based on depth
inline Value razor_margin(Depth d) { return Value(512 + 16 * d); }
GainsStats Gains;
MovesStats Countermoves, Followupmoves;
- template <NodeType NT>
+ template <NodeType NT, bool SpNode>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
template <NodeType NT, bool InCheck>
void id_loop(Position& pos);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- void update_stats(Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
+ void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
struct Skill {
{
double pvRed = 0.00 + log(double(hd)) * log(double(mc)) / 3.00;
double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
- 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][1][hd][mc] = int8_t( pvRed >= 1.0 ? pvRed * int(ONE_PLY) : 0);
+ Reductions[0][1][hd][mc] = int8_t(nonPVRed >= 1.0 ? 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];
void Search::think() {
- static PolyglotBook book; // Defined static to initialize the PRNG only once
+ TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move());
- RootColor = RootPos.side_to_move();
- TimeMgr.init(Limits, RootPos.game_ply(), RootColor);
-
- DrawValue[0] = DrawValue[1] = VALUE_DRAW;
- Contempt[0] = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns
- Contempt[1] = (Options["Contempt Factor"] + 12) * PawnValueEg / 100;
+ int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns
+ DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf);
+ DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf);
if (RootMoves.empty())
{
goto finalize;
}
- if (Options["OwnBook"] && !Limits.infinite && !Limits.mate)
- {
- Move bookMove = book.probe(RootPos, Options["Book File"], Options["Best Book Move"]);
-
- if (bookMove && std::count(RootMoves.begin(), RootMoves.end(), bookMove))
- {
- std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), bookMove));
- goto finalize;
- }
- }
-
if (Options["Write Search Log"])
{
Log log(Options["Search Log Filename"]);
log << "\nSearching: " << RootPos.fen()
<< "\ninfinite: " << Limits.infinite
<< " ponder: " << Limits.ponder
- << " time: " << Limits.time[RootColor]
- << " increment: " << Limits.inc[RootColor]
+ << " time: " << Limits.time[RootPos.side_to_move()]
+ << " increment: " << Limits.inc[RootPos.side_to_move()]
<< " moves to go: " << Limits.movestogo
<< "\n" << std::endl;
}
for (size_t i = 0; i < Threads.size(); ++i)
Threads[i]->maxPly = 0;
- Threads.sleepWhileIdle = Options["Idle Threads Sleep"];
Threads.timer->run = true;
Threads.timer->notify_one(); // Wake up the recurring timer
id_loop(RootPos); // Let's start searching !
Threads.timer->run = false; // Stop the timer
- Threads.sleepWhileIdle = true; // Send idle threads to sleep
if (Options["Write Search Log"])
{
Value bestValue, alpha, beta, delta;
std::memset(ss-2, 0, 5 * sizeof(Stack));
- (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
depth = 0;
BestMoveChanges = 0;
// high/low anymore.
while (true)
{
- bestValue = search<Root>(pos, ss, alpha, beta, depth * ONE_PLY, false);
-
- DrawValue[ RootColor] = VALUE_DRAW - Contempt[bestValue > VALUE_DRAW];
- DrawValue[~RootColor] = VALUE_DRAW + Contempt[bestValue > VALUE_DRAW];
+ bestValue = search<Root, false>(pos, ss, alpha, beta, depth * ONE_PLY, false);
// Bring the best move to the front. It is critical that sorting
// is done with a stable algorithm because all the values but the
// repeat all this work again. We also don't need to store anything to the hash
// table here: This is taken care of after we return from the split point.
- template <NodeType NT>
+ template <NodeType NT, bool SpNode>
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);
- const bool RootNode = (NT == Root || NT == SplitPointRoot);
+ const bool RootNode = NT == Root;
+ const bool PvNode = NT == PV || NT == Root;
assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
}
else
{
- eval = ss->staticEval = evaluate(pos);
+ eval = ss->staticEval =
+ (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Eval::Tempo;
+
TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval);
}
&& ss->staticEval != VALUE_NONE
&& (ss-1)->staticEval != VALUE_NONE
&& (move = (ss-1)->currentMove) != MOVE_NULL
+ && move != MOVE_NONE
&& type_of(move) == NORMAL)
{
Square to = to_sq(move);
&& depth < 4 * ONE_PLY
&& eval + razor_margin(depth) <= alpha
&& ttMove == MOVE_NONE
- && abs(beta) < VALUE_MATE_IN_MAX_PLY
&& !pos.pawn_on_7th(pos.side_to_move()))
{
+ if ( depth <= ONE_PLY
+ && eval + razor_margin(3 * ONE_PLY) <= alpha)
+ return qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO);
+
Value ralpha = alpha - razor_margin(depth);
Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
if (v <= ralpha)
&& !ss->skipNullMove
&& depth >= 2 * ONE_PLY
&& eval >= beta
- && abs(beta) < VALUE_MATE_IN_MAX_PLY
&& pos.non_pawn_material(pos.side_to_move()))
{
ss->currentMove = MOVE_NULL;
// Null move dynamic reduction based on depth and value
Depth R = 3 * ONE_PLY
+ depth / 4
- + int(eval - beta) / PawnValueMg * ONE_PLY;
+ + (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY
+ : DEPTH_ZERO);
pos.do_null_move(st);
(ss+1)->skipNullMove = true;
nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
+ : - search<NonPV, false>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
(ss+1)->skipNullMove = false;
pos.undo_null_move();
if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta;
- if (depth < 12 * ONE_PLY)
+ if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN)
return nullValue;
// Do verification search at high depths
ss->skipNullMove = true;
Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta, DEPTH_ZERO)
- : search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
+ : search<NonPV, false>(pos, ss, beta-1, beta, depth-R, false);
ss->skipNullMove = false;
if (v >= beta)
{
ss->currentMove = move;
pos.do_move(move, st, ci, pos.gives_check(move, ci));
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
+ value = -search<NonPV, false>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
pos.undo_move(move);
if (value >= rbeta)
return value;
Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
ss->skipNullMove = true;
- search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d, true);
+ search<PvNode ? PV : NonPV, false>(pos, ss, alpha, beta, d, true);
ss->skipNullMove = false;
tte = TT.probe(posKey);
singularExtensionNode = !RootNode
&& !SpNode
&& depth >= 8 * ONE_PLY
+ && abs(beta) < VALUE_KNOWN_WIN
&& ttMove != MOVE_NONE
+ /* && ttValue != VALUE_NONE Already implicit in the next condition */
+ && abs(ttValue) < VALUE_KNOWN_WIN
&& !excludedMove // Recursive singular search is not allowed
&& (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
if ( singularExtensionNode
&& move == ttMove
&& !ext
- && pos.legal(move, ci.pinned)
- && abs(ttValue) < VALUE_KNOWN_WIN)
+ && pos.legal(move, ci.pinned))
{
- assert(ttValue != VALUE_NONE);
-
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
+ value = search<NonPV, false>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
if (move == countermoves[0] || move == countermoves[1])
ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+ // Decrease reduction for moves that escape a capture
+ if ( ss->reduction
+ && type_of(move) == NORMAL
+ && type_of(pos.piece_on(to_sq(move))) != PAWN
+ && pos.see(make_move(to_sq(move), from_sq(move))) < 0)
+ ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+
Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
if (SpNode)
alpha = splitPoint->alpha;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
+ value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d, true);
- // Research at intermediate depth if reduction is very high
+ // Re-search at intermediate depth if reduction is very high
if (value > alpha && ss->reduction >= 4 * ONE_PLY)
{
Depth d2 = std::max(newDepth - 2 * ONE_PLY, ONE_PLY);
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d2, true);
+ value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d2, true);
}
doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
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, !cutNode);
+ : - search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
}
// For PV nodes only, 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, false);
+ : - search<PV, false>(pos, ss+1, -beta, -alpha, newDepth, false);
// Step 17. Undo move
pos.undo_move(move);
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.
+ // Finished searching the move. If a stop or a cutoff occurred, the return
+ // value of the search cannot be trusted, and we return immediately without
+ // updating best move, PV and TT.
if (Signals.stop || thisThread->cutoff_occurred())
- return value; // To avoid returning VALUE_INFINITE
+ return VALUE_ZERO;
if (RootNode)
{
// Step 19. Check for splitting the search
if ( !SpNode
+ && Threads.size() >= 2
&& depth >= Threads.minimumSplitDepth
- && Threads.available_slave(thisThread)
+ && ( !thisThread->activeSplitPoint
+ || !thisThread->activeSplitPoint->allSlavesSearching)
&& thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD)
{
- assert(bestValue < beta);
+ assert(bestValue > -VALUE_INFINITE && bestValue < beta);
thisThread->split<FakeSplit>(pos, ss, alpha, beta, &bestValue, &bestMove,
depth, moveCount, &mp, NT, cutNode);
+
+ if (Signals.stop || thisThread->cutoff_occurred())
+ return VALUE_ZERO;
+
if (bestValue >= beta)
break;
}
if (SpNode)
return bestValue;
+ // Following condition would detect a stop or a cutoff set only after move
+ // loop has been completed. But in this case bestValue is valid because we
+ // have fully searched our subtree, and we can anyhow save the result in TT.
+ /*
+ if (Signals.stop || thisThread->cutoff_occurred())
+ return VALUE_DRAW;
+ */
+
// Step 20. Check for mate and stalemate
// All legal moves have been searched and if there are no legal moves, it
- // must be mate or stalemate. Note that we can have a false positive in
- // case of Signals.stop or thread.cutoff_occurred() are set, but this is
- // harmless because return value is discarded anyhow in the parent nodes.
- // If we are in a singular extension search then return a fail low score.
- // A split node has at least one move - the one tried before to be split.
+ // must be mate or stalemate. If we are in a singular extension search then
+ // return a fail low score.
if (!moveCount)
- return excludedMove ? alpha
- : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+ bestValue = excludedMove ? alpha
+ : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
- // If we have pruned all the moves without searching return a fail-low score
- if (bestValue == -VALUE_INFINITE)
- bestValue = alpha;
+ // Quiet best move: update killers, history, countermoves and followupmoves
+ else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
+ update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
TT.store(posKey, value_to_tt(bestValue, ss->ply),
bestValue >= beta ? BOUND_LOWER :
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
depth, bestMove, ss->staticEval);
- // Quiet best move: update killers, history, countermoves and followupmoves
- if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
- update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
-
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
return bestValue;
template <NodeType NT, bool InCheck>
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
- const bool PvNode = (NT == PV);
+ const bool PvNode = NT == PV;
assert(NT == PV || NT == NonPV);
assert(InCheck == !!pos.checkers());
bestValue = ttValue;
}
else
- ss->staticEval = bestValue = evaluate(pos);
+ ss->staticEval = bestValue =
+ (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Eval::Tempo;
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
// update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
// of a quiet move.
- void update_stats(Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
+ void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
if (ss->killers[0] != move)
{
StateInfo state[MAX_PLY_PLUS_6], *st = state;
const TTEntry* tte;
- int ply = 0;
- Move m = pv[0];
+ int ply = 1; // At root ply is 1...
+ Move m = pv[0]; // ...instead pv[] array starts from 0
+ Value expectedScore = score;
pv.clear();
do {
pv.push_back(m);
- assert(MoveList<LEGAL>(pos).contains(pv[ply]));
+ assert(MoveList<LEGAL>(pos).contains(pv[ply - 1]));
- pos.do_move(pv[ply++], *st++);
+ pos.do_move(pv[ply++ - 1], *st++);
tte = TT.probe(pos.key());
+ expectedScore = -expectedScore;
} while ( tte
+ && expectedScore == value_from_tt(tte->value(), ply)
&& pos.pseudo_legal(m = tte->move()) // Local copy, TT could change
&& pos.legal(m, pos.pinned_pieces(pos.side_to_move()))
&& ply < MAX_PLY
- && (!pos.is_draw() || ply < 2));
+ && (!pos.is_draw() || ply <= 2));
pv.push_back(MOVE_NONE); // Must be zero-terminating
- while (ply) pos.undo_move(pv[--ply]);
+ while (--ply) pos.undo_move(pv[ply - 1]);
}
StateInfo state[MAX_PLY_PLUS_6], *st = state;
const TTEntry* tte;
- int ply = 0;
+ int idx = 0; // Ply starts from 1, we need to start from 0
do {
tte = TT.probe(pos.key());
- if (!tte || tte->move() != pv[ply]) // Don't overwrite correct entries
- TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], VALUE_NONE);
+ if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries
+ TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[idx], VALUE_NONE);
- assert(MoveList<LEGAL>(pos).contains(pv[ply]));
+ assert(MoveList<LEGAL>(pos).contains(pv[idx]));
- pos.do_move(pv[ply++], *st++);
+ pos.do_move(pv[idx++], *st++);
- } while (pv[ply] != MOVE_NONE);
+ } while (pv[idx] != MOVE_NONE);
- while (ply) pos.undo_move(pv[--ply]);
+ while (idx) pos.undo_move(pv[--idx]);
}
{
// 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)
+ while (!searching || exit)
{
if (exit)
{
activePosition = &pos;
- 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:
+ if (sp->nodeType == NonPV)
+ search<NonPV, true>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
+
+ else if (sp->nodeType == PV)
+ search<PV, true>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
+
+ else if (sp->nodeType == Root)
+ search<Root, true>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
+
+ else
assert(false);
- }
assert(searching);
searching = false;
activePosition = NULL;
sp->slavesMask.reset(idx);
+ sp->allSlavesSearching = false;
sp->nodes += pos.nodes_searched();
// Wake up the 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
+ if ( this != sp->masterThread
&& sp->slavesMask.none())
{
assert(!sp->masterThread->searching);
// After releasing the lock we can't access any SplitPoint related data
// in a safe way because it could have been released under our feet by
- // the sp master. Also accessing other Thread objects is unsafe because
- // if we are exiting there is a chance that they are already freed.
+ // the sp master.
sp->mutex.unlock();
+
+ // Try to late join to another split point if none of its slaves has
+ // already finished.
+ if (Threads.size() > 2)
+ for (size_t i = 0; i < Threads.size(); ++i)
+ {
+ const int size = Threads[i]->splitPointsSize; // Local copy
+ sp = size ? &Threads[i]->splitPoints[size - 1] : NULL;
+
+ if ( sp
+ && sp->allSlavesSearching
+ && available_to(Threads[i]))
+ {
+ // Recheck the conditions under lock protection
+ Threads.mutex.lock();
+ sp->mutex.lock();
+
+ if ( sp->allSlavesSearching
+ && available_to(Threads[i]))
+ {
+ sp->slavesMask.set(idx);
+ activeSplitPoint = sp;
+ searching = true;
+ }
+
+ sp->mutex.unlock();
+ Threads.mutex.unlock();
+
+ break; // Just a single attempt
+ }
+ }
}
// If this thread is the master of a split point and all slaves have finished