#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, Depth depth, Value alpha, Value beta);
}
size_t candidates_size() const { return candidates; }
- bool time_to_pick(Depth 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);
}
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
+
+ // 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.
+
+ // 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);
+
+ // 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
+
for (size_t i = 0; i < Threads.size(); ++i)
Threads[i]->maxPly = 0;
RootPos.this_thread()->wait_for(Signals.stop);
}
- 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;
}
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;
assert(PvNode || (alpha == beta - 1));
assert(depth > DEPTH_ZERO);
- PVEntry pv;
- 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 ( !PvNode
+ // 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
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;
}
&& !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);
// For PV nodes only, do a full PV search on the first move or after a fail
// 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)))) {
- pv.pv[0] = MOVE_NONE;
- (ss+1)->pv = &pv;
+ 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);
{
rm.score = value;
rm.pv.resize(1);
- for (int i = 0; (ss+1)->pv && i < MAX_PLY && (ss+1)->pv->pv[i] != MOVE_NONE; ++i)
- rm.pv.push_back((ss+1)->pv->pv[i]);
+
+ 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 (NT == PV) {
- ss->pv->update(move, (ss+1)->pv);
- if (SpNode)
- splitPoint->ss->pv->update(move, (ss+1)->pv);
- }
+ 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;
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
- PVEntry pv;
+ Move pv[MAX_PLY+1];
StateInfo st;
const TTEntry* tte;
Key posKey;
bool givesCheck, evasionPrunable;
Depth ttDepth;
- if (PvNode) {
- // To flag BOUND_EXACT a node with eval above alpha and no available moves
- oldAlpha = alpha;
-
- (ss+1)->pv = &pv;
- ss->pv->pv[0] = MOVE_NONE;
+ if (PvNode)
+ {
+ 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;
ttMove = tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
- if ( !PvNode
+ if ( !PvNode
&& tte
&& tte->depth() >= ttDepth
&& ttValue != VALUE_NONE // Only in case of TT access race
if (value > alpha)
{
- if (PvNode)
- ss->pv->update(move, &pv);
+ 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
{
}
+ // 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)
{
{
bool updated = (i <= PVIdx);
- if (depth == 1 && !updated)
+ if (depth == ONE_PLY && !updated)
continue;
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 / 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";
StateInfo state[MAX_PLY], *st = state;
const TTEntry* tte;
- int idx = 0;
+ size_t idx = 0;
- for (; idx < int(pv.size()); ++idx) {
+ for ( ; idx < pv.size(); ++idx)
+ {
tte = TT.probe(pos.key());
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[idx]));
+
pos.do_move(pv[idx], *st++);
}
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