#include "tt.h"
#include "uci.h"
+#ifdef SYZYGY
+#include "syzygy/tbprobe.h"
+#endif
+
namespace Search {
volatile SignalsType Signals;
Position RootPos;
Time::point SearchTime;
StateStackPtr SetupStates;
+ int TBCardinality;
+ uint64_t TBHits;
+ bool RootInTB;
+ bool TB50MoveRule;
+ Depth TBProbeDepth;
+ Value TBScore;
}
using std::string;
void id_loop(Position& pos);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
+ void update_pv(Move* pv, Move move, Move* childPv);
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);
+ string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta);
struct Skill {
Skill(int l, size_t rootSize) : level(l),
}
size_t candidates_size() const { return candidates; }
- bool time_to_pick(int depth) const { return depth == 1 + level; }
+ bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; }
Move pick_move();
int level;
void Search::think() {
TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move());
+ TBHits = TBCardinality = 0;
+ RootInTB = false;
int cf = Options["Contempt"] * PawnValueEg / 100; // From centipawns
DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf);
sync_cout << "info depth 0 score "
<< UCI::format_value(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
<< sync_endl;
-
- goto finalize;
}
+ else
+ {
+#ifdef SYZYGY
+ // Check Tablebases at root
+ int piecesCnt = RootPos.total_piece_count();
+ TBCardinality = Options["SyzygyProbeLimit"];
+ TBProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
+ if (TBCardinality > Tablebases::TBLargest)
+ {
+ TBCardinality = Tablebases::TBLargest;
+ TBProbeDepth = 0 * ONE_PLY;
+ }
+ TB50MoveRule = Options["Syzygy50MoveRule"];
+
+ if (piecesCnt <= TBCardinality)
+ {
+ TBHits = RootMoves.size();
+
+ // If the current root position is in the tablebases then RootMoves
+ // contains only moves that preserve the draw or win.
+ RootInTB = Tablebases::root_probe(RootPos, TBScore);
+
+ if (RootInTB)
+ {
+ TBCardinality = 0; // Do not probe tablebases during the search
- // Reset the threads, still sleeping: will wake up at split time
- for (size_t i = 0; i < Threads.size(); ++i)
- Threads[i]->maxPly = 0;
+ // It might be a good idea to mangle the hash key (xor it
+ // with a fixed value) in order to "clear" the hash table of
+ // the results of previous probes. However, that would have to
+ // be done from within the Position class, so we skip it for now.
- Threads.timer->run = true;
- Threads.timer->notify_one(); // Wake up the recurring timer
+ // Optional: decrease target time.
+ }
+ else // If DTZ tables are missing, use WDL tables as a fallback
+ {
+ // Filter out moves that do not preserve a draw or win
+ RootInTB = Tablebases::root_probe_wdl(RootPos, TBScore);
- id_loop(RootPos); // Let's start searching !
+ // Only probe during search if winning
+ if (TBScore <= VALUE_DRAW)
+ TBCardinality = 0;
+ }
+
+ if (!RootInTB)
+ {
+ TBHits = 0;
+ }
+ else if (!TB50MoveRule)
+ {
+ TBScore = TBScore > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1
+ : TBScore < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
+ : TBScore;
+ }
+ }
+#endif
- Threads.timer->run = false; // Stop the timer
+ for (size_t i = 0; i < Threads.size(); ++i)
+ Threads[i]->maxPly = 0;
-finalize:
+ Threads.timer->run = true;
+ Threads.timer->notify_one(); // Wake up the recurring timer
- // When search is stopped this info is not printed
- sync_cout << "info nodes " << RootPos.nodes_searched()
- << " time " << Time::now() - SearchTime + 1 << sync_endl;
+ id_loop(RootPos); // Let's start searching !
+
+ Threads.timer->run = false;
+ }
// When we reach the maximum depth, we can arrive here without a raise of
// Signals.stop. However, if we are pondering or in an infinite search,
RootPos.this_thread()->wait_for(Signals.stop);
}
- // Best move could be MOVE_NONE when searching on a stalemate position
- sync_cout << "bestmove " << UCI::format_move(RootMoves[0].pv[0], RootPos.is_chess960())
- << " ponder " << UCI::format_move(RootMoves[0].pv[1], RootPos.is_chess960())
- << sync_endl;
+ sync_cout << "bestmove " << UCI::format_move(RootMoves[0].pv[0], RootPos.is_chess960());
+
+ if (RootMoves[0].pv.size() > 1)
+ std::cout << " ponder " << UCI::format_move(RootMoves[0].pv[1], RootPos.is_chess960());
+
+ std::cout << sync_endl;
}
void id_loop(Position& pos) {
Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
- int depth;
+ Depth depth;
Value bestValue, alpha, beta, delta;
std::memset(ss-2, 0, 5 * sizeof(Stack));
- depth = 0;
+ depth = DEPTH_ZERO;
BestMoveChanges = 0;
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
multiPV = std::max(multiPV, skill.candidates_size());
// Iterative deepening loop until requested to stop or target depth reached
- while (++depth < MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
+ while (++depth < DEPTH_MAX && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
{
// Age out PV variability metric
BestMoveChanges *= 0.5;
for (PVIdx = 0; PVIdx < std::min(multiPV, RootMoves.size()) && !Signals.stop; ++PVIdx)
{
// Reset aspiration window starting size
- if (depth >= 5)
+ if (depth >= 5 * ONE_PLY)
{
delta = Value(16);
alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE);
// high/low anymore.
while (true)
{
- bestValue = search<Root, false>(pos, ss, alpha, beta, depth * ONE_PLY, false);
+ bestValue = search<Root, false>(pos, ss, alpha, beta, depth, 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
// Sort the PV lines searched so far and update the GUI
std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1);
- if ( !Signals.stop
- && ( PVIdx + 1 == std::min(multiPV, RootMoves.size())
- || Time::now() - SearchTime > 3000))
+ if (Signals.stop)
+ sync_cout << "info nodes " << RootPos.nodes_searched()
+ << " time " << Time::now() - SearchTime << sync_endl;
+
+ else if ( PVIdx + 1 == std::min(multiPV, RootMoves.size())
+ || Time::now() - SearchTime > 3000)
sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
}
if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit)
{
// Take some extra time if the best move has changed
- if (depth > 4 && multiPV == 1)
+ if (depth > 4 * ONE_PLY && multiPV == 1)
TimeMgr.pv_instability(BestMoveChanges);
// Stop the search if only one legal move is available or all
assert(PvNode || (alpha == beta - 1));
assert(depth > DEPTH_ZERO);
- Move quietsSearched[64];
+ Move pv[MAX_PLY+1], quietsSearched[64];
StateInfo st;
const TTEntry *tte;
SplitPoint* splitPoint;
ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
- // At PV nodes we check for exact scores, whilst at non-PV nodes we check for
- // a fail high/low. The biggest advantage to probing at PV nodes is to have a
- // smooth experience in analysis mode. We don't probe at Root nodes otherwise
- // we should also update RootMoveList to avoid bogus output.
- if ( !RootNode
+ // At non-PV nodes we check for a fail high/low. We don't probe at PV nodes
+ if ( !PvNode
&& tte
&& tte->depth() >= depth
&& ttValue != VALUE_NONE // Only in case of TT access race
- && ( PvNode ? tte->bound() == BOUND_EXACT
- : ttValue >= beta ? (tte->bound() & BOUND_LOWER)
- : (tte->bound() & BOUND_UPPER)))
+ && (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
+ : (tte->bound() & BOUND_UPPER)))
{
ss->currentMove = ttMove; // Can be MOVE_NONE
return ttValue;
}
+#ifdef SYZYGY
+ // Step 4a. Tablebase probe
+ if ( !RootNode
+ && pos.total_piece_count() <= TBCardinality
+ && ( pos.total_piece_count() < TBCardinality || depth >= TBProbeDepth )
+ && pos.rule50_count() == 0)
+ {
+ int found, v = Tablebases::probe_wdl(pos, &found);
+
+ if (found)
+ {
+ TBHits++;
+
+ if (TB50MoveRule) {
+ value = v < -1 ? -VALUE_MATE + MAX_PLY + ss->ply
+ : v > 1 ? VALUE_MATE - MAX_PLY - ss->ply
+ : VALUE_DRAW + 2 * v;
+ }
+ else
+ {
+ value = v < 0 ? -VALUE_MATE + MAX_PLY + ss->ply
+ : v > 0 ? VALUE_MATE - MAX_PLY - ss->ply
+ : VALUE_DRAW;
+ }
+
+ TT.store(posKey, value_to_tt(value, ss->ply), BOUND_EXACT,
+ std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), MOVE_NONE, VALUE_NONE);
+
+ return value;
+ }
+ }
+#endif
+
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
{
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
- Depth R = (3 + depth / 4 + std::min(int(eval - beta) / PawnValueMg, 3)) * ONE_PLY;
+ Depth R = (3 + depth / 4 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
pos.do_null_move(st);
(ss+1)->skipNullMove = true;
Signals.firstRootMove = (moveCount == 1);
if (thisThread == Threads.main() && Time::now() - SearchTime > 3000)
- sync_cout << "info depth " << depth
+ sync_cout << "info depth " << depth / ONE_PLY
<< " currmove " << UCI::format_move(move, pos.is_chess960())
<< " currmovenumber " << moveCount + PVIdx << sync_endl;
}
+ if (PvNode)
+ (ss+1)->pv = NULL;
+
ext = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
&& !ext
&& pos.legal(move, ci.pinned))
{
- Value rBeta = ttValue - int(2 * depth);
+ Value rBeta = ttValue - 2 * depth / ONE_PLY;
ss->excludedMove = move;
ss->skipNullMove = true;
value = search<NonPV, false>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
// high (in the latter case search only if value < beta), otherwise let the
// parent node fail low with value <= alpha and to try another move.
if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta))))
+ {
+ (ss+1)->pv = pv;
+ (ss+1)->pv[0] = MOVE_NONE;
+
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, false>(pos, ss+1, -beta, -alpha, newDepth, false);
+ }
+
// Step 17. Undo move
pos.undo_move(move);
if (moveCount == 1 || value > alpha)
{
rm.score = value;
- rm.extract_pv_from_tt(pos);
+ rm.pv.resize(1);
+
+ assert((ss+1)->pv);
+
+ for (Move* m = (ss+1)->pv; *m != MOVE_NONE; ++m)
+ rm.pv.push_back(*m);
// We record how often the best move has been changed in each
// iteration. This information is used for time management: When
{
bestMove = SpNode ? splitPoint->bestMove = move : move;
+ if (PvNode && !RootNode) // Update pv even in fail-high case
+ update_pv(SpNode ? splitPoint->ss->pv : ss->pv, move, (ss+1)->pv);
+
if (PvNode && value < beta) // Update alpha! Always alpha < beta
alpha = SpNode ? splitPoint->alpha = value : value;
else
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
+ Move pv[MAX_PLY+1];
StateInfo st;
const TTEntry* tte;
Key posKey;
bool givesCheck, evasionPrunable;
Depth ttDepth;
- // To flag BOUND_EXACT a node with eval above alpha and no available moves
if (PvNode)
- oldAlpha = alpha;
+ {
+ oldAlpha = alpha; // To flag BOUND_EXACT when eval above alpha and no available moves
+ (ss+1)->pv = pv;
+ ss->pv[0] = MOVE_NONE;
+ }
ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
ttMove = tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
- if ( tte
+ if ( !PvNode
+ && tte
&& tte->depth() >= ttDepth
&& ttValue != VALUE_NONE // Only in case of TT access race
- && ( PvNode ? tte->bound() == BOUND_EXACT
- : ttValue >= beta ? (tte->bound() & BOUND_LOWER)
- : (tte->bound() & BOUND_UPPER)))
+ && (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
+ : (tte->bound() & BOUND_UPPER)))
{
ss->currentMove = ttMove; // Can be MOVE_NONE
return ttValue;
if (value > alpha)
{
+ if (PvNode) // Update pv even in fail-high case
+ update_pv(ss->pv, move, (ss+1)->pv);
+
if (PvNode && value < beta) // Update alpha here! Always alpha < beta
{
alpha = value;
}
+ // update_pv() adds current move and appends child pv[]
+
+ void update_pv(Move* pv, Move move, Move* childPv) {
+
+ for (*pv++ = move; childPv && *childPv != MOVE_NONE; )
+ *pv++ = *childPv++;
+ *pv = MOVE_NONE;
+ }
+
// update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
// of a quiet move.
// Increase history value of the cut-off move and decrease all the other
// played quiet moves.
- Value bonus = Value(4 * int(depth) * int(depth));
+ Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
History.update(pos.moved_piece(move), to_sq(move), bonus);
for (int i = 0; i < quietsCnt; ++i)
{
// requires that all (if any) unsearched PV lines are sent using a previous
// search score.
- string uci_pv(const Position& pos, int depth, Value alpha, Value beta) {
+ string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta) {
std::stringstream ss;
Time::point elapsed = Time::now() - SearchTime + 1;
{
bool updated = (i <= PVIdx);
- if (depth == 1 && !updated)
+ if (depth == ONE_PLY && !updated)
continue;
- int d = updated ? depth : depth - 1;
+ Depth d = updated ? depth : depth - ONE_PLY;
Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore;
+ bool tb = RootInTB;
+ if (tb)
+ {
+ if (abs(v) >= VALUE_MATE - MAX_PLY)
+ tb = false;
+ else
+ v = TBScore;
+ }
+
if (ss.rdbuf()->in_avail()) // Not at first line
ss << "\n";
- ss << "info depth " << d
+ ss << "info depth " << d / ONE_PLY
<< " seldepth " << selDepth
<< " multipv " << i + 1
- << " score " << (i == PVIdx ? UCI::format_value(v, alpha, beta) : UCI::format_value(v))
+ << " score " << ((!tb && i == PVIdx) ? UCI::format_value(v, alpha, beta) : UCI::format_value(v))
<< " nodes " << pos.nodes_searched()
<< " nps " << pos.nodes_searched() * 1000 / elapsed
+ << " tbhits " << TBHits
<< " time " << elapsed
<< " pv";
- for (size_t j = 0; RootMoves[i].pv[j] != MOVE_NONE; ++j)
+ for (size_t j = 0; j < RootMoves[i].pv.size(); ++j)
ss << " " << UCI::format_move(RootMoves[i].pv[j], pos.is_chess960());
}
} // namespace
-/// RootMove::extract_pv_from_tt() builds a PV by adding moves from the TT table.
-/// We also consider both failing high nodes and BOUND_EXACT nodes here to
-/// ensure that we have a ponder move even when we fail high at root. This
-/// results in a long PV to print that is important for position analysis.
-
-void RootMove::extract_pv_from_tt(Position& pos) {
-
- StateInfo state[MAX_PLY], *st = state;
- const TTEntry* tte;
- 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 - 1]));
-
- 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));
-
- pv.push_back(MOVE_NONE); // Must be zero-terminating
-
- while (--ply) pos.undo_move(pv[ply - 1]);
-}
-
-
/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
/// inserts the PV back into the TT. This makes sure the old PV moves are searched
/// first, even if the old TT entries have been overwritten.
StateInfo state[MAX_PLY], *st = state;
const TTEntry* tte;
- int idx = 0; // Ply starts from 1, we need to start from 0
+ size_t idx = 0;
- do {
+ for ( ; idx < pv.size(); ++idx)
+ {
tte = TT.probe(pos.key());
if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries
assert(MoveList<LEGAL>(pos).contains(pv[idx]));
- pos.do_move(pv[idx++], *st++);
-
- } while (pv[idx] != MOVE_NONE);
+ pos.do_move(pv[idx], *st++);
+ }
while (idx) pos.undo_move(pv[--idx]);
}
dbg_print();
}
- if (Limits.use_time_management() && !Limits.ponder)
+ // An engine may not stop pondering until told so by the GUI
+ if (Limits.ponder)
+ return;
+
+ if (Limits.use_time_management())
{
bool stillAtFirstMove = Signals.firstRootMove
&& !Signals.failedLowAtRoot
projects / stockfish / blobdiff