void read_uci_options();
bool available_thread_exists(int master) const;
bool thread_is_available(int slave, int master) const;
- bool thread_should_stop(int threadID) const;
+ bool cutoff_at_splitpoint(int threadID) const;
void wake_sleeping_thread(int threadID);
void idle_loop(int threadID, SplitPoint* sp);
};
- // RootMove struct is used for moves at the root at the tree. For each
- // root move, we store a score, a node count, and a PV (really a refutation
- // in the case of moves which fail low).
+ // RootMove struct is used for moves at the root at the tree. For each root
+ // move, we store two scores, a node count, and a PV (really a refutation
+ // in the case of moves which fail low). Value pvScore is normally set at
+ // -VALUE_INFINITE for all non-pv moves, while nonPvScore is computed
+ // according to the order in which moves are returned by MovePicker.
struct RootMove {
- RootMove() : mp_score(0), nodes(0) {}
+ RootMove() : nodes(0) { pvScore = nonPvScore = -VALUE_INFINITE; }
// RootMove::operator<() is the comparison function used when
// sorting the moves. A move m1 is considered to be better
- // than a move m2 if it has a higher score, or if the moves
- // have equal score but m1 has the higher beta cut-off count.
+ // than a move m2 if it has an higher pvScore, or if it has
+ // equal pvScore but m1 has the higher nonPvScore. In this way
+ // we are guaranteed that PV moves are always sorted as first.
bool operator<(const RootMove& m) const {
-
- return score != m.score ? score < m.score : mp_score <= m.mp_score;
+ return pvScore != m.pvScore ? pvScore < m.pvScore : nonPvScore <= m.nonPvScore;
}
Move move;
- Value score;
- int mp_score;
+ Value pvScore;
+ Value nonPvScore;
int64_t nodes;
Move pv[PLY_MAX_PLUS_2];
};
Move move(int moveNum) const { return moves[moveNum].move; }
Move move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; }
- int move_count() const { return count; }
- Value move_score(int moveNum) const { return moves[moveNum].score; }
- int64_t move_nodes(int moveNum) const { return moves[moveNum].nodes; }
- void add_move_nodes(int moveNum, int64_t nodes) { moves[moveNum].nodes += nodes; }
- void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; }
-
- void set_move_pv(int moveNum, const Move pv[]);
- void score_moves(const Position& pos);
+ int size() const { return count; }
+ Value pv_score(int moveNum) const { return moves[moveNum].pvScore; }
+ int64_t nodes(int moveNum) const { return moves[moveNum].nodes; }
+ void add_nodes(int moveNum, int64_t n) { moves[moveNum].nodes += n; }
+ void set_pv_score(int moveNum, Value v) { moves[moveNum].pvScore = v; }
+
+ void set_pv(int moveNum, const Move pv[]);
+ void set_non_pv_scores(const Position& pos);
void sort();
void sort_multipv(int n);
RootMoveList rml(pos, searchMoves);
// Handle special case of searching on a mate/stale position
- if (rml.move_count() == 0)
+ if (rml.size() == 0)
{
if (PonderSearch)
wait_for_stop_or_ponderhit();
cout << set960(pos.is_chess960()) // Is enough to set once at the beginning
<< "info depth " << 1
<< "\ninfo depth " << 1
- << " score " << value_to_uci(rml.move_score(0))
+ << " score " << value_to_uci(rml.pv_score(0))
<< " time " << current_search_time()
<< " nodes " << pos.nodes_searched()
<< " nps " << nps(pos)
H.clear();
init_ss_array(ss, PLY_MAX_PLUS_2);
pv[0] = pv[1] = MOVE_NONE;
- ValueByIteration[1] = rml.move_score(0);
+ ValueByIteration[1] = rml.pv_score(0);
Iteration = 1;
// Is one move significantly better than others after initial scoring ?
- if ( rml.move_count() == 1
- || rml.move_score(0) > rml.move_score(1) + EasyMoveMargin)
+ if ( rml.size() == 1
+ || rml.pv_score(0) > rml.pv_score(1) + EasyMoveMargin)
EasyMove = rml.move(0);
// Iterative deepening loop
// Stop search early if there is only a single legal move,
// we search up to Iteration 6 anyway to get a proper score.
- if (Iteration >= 6 && rml.move_count() == 1)
+ if (Iteration >= 6 && rml.size() == 1)
stopSearch = true;
// Stop search early when the last two iterations returned a mate score
// Stop search early if one move seems to be much better than the others
if ( Iteration >= 8
&& EasyMove == pv[0]
- && ( ( rml.move_nodes(0) > (pos.nodes_searched() * 85) / 100
+ && ( ( rml.nodes(0) > (pos.nodes_searched() * 85) / 100
&& current_search_time() > TimeMgr.available_time() / 16)
- ||( rml.move_nodes(0) > (pos.nodes_searched() * 98) / 100
+ ||( rml.nodes(0) > (pos.nodes_searched() * 98) / 100
&& current_search_time() > TimeMgr.available_time() / 32)))
stopSearch = true;
<< move_to_san(pos, pv[1]) // Works also with MOVE_NONE
<< endl;
}
- return rml.move_score(0);
+ return rml.pv_score(0);
}
while (1)
{
// Sort the moves before to (re)search
- rml.score_moves(pos);
+ rml.set_non_pv_scores(pos);
rml.sort();
// Step 10. Loop through all moves in the root move list
- for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
+ for (int i = 0; i < rml.size() && !AbortSearch; i++)
{
// This is used by time management
FirstRootMove = (i == 0);
// Step extra. Fail high loop
// If move fails high, we research with bigger window until we are not failing
// high anymore.
- value = - VALUE_INFINITE;
+ value = -VALUE_INFINITE;
while (1)
{
// We are failing high and going to do a research. It's important to update
// the score before research in case we run out of time while researching.
- rml.set_move_score(i, value);
+ rml.set_pv_score(i, value);
ss->bestMove = move;
extract_pv_from_tt(pos, move, pv);
- rml.set_move_pv(i, pv);
+ rml.set_pv(i, pv);
// Print information to the standard output
print_pv_info(pos, pv, alpha, beta, value);
break;
// Remember searched nodes counts for this move
- rml.add_move_nodes(i, pos.nodes_searched() - nodes);
+ rml.add_nodes(i, pos.nodes_searched() - nodes);
assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
assert(value < beta);
// Step 17. Check for new best move
if (value <= alpha && i >= MultiPV)
- rml.set_move_score(i, -VALUE_INFINITE);
+ rml.set_pv_score(i, -VALUE_INFINITE);
else
{
// PV move or new best move!
// Update PV
- rml.set_move_score(i, value);
+ rml.set_pv_score(i, value);
ss->bestMove = move;
extract_pv_from_tt(pos, move, pv);
- rml.set_move_pv(i, pv);
+ rml.set_pv(i, pv);
if (MultiPV == 1)
{
else // MultiPV > 1
{
rml.sort_multipv(i);
- for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
+ for (int j = 0; j < Min(MultiPV, rml.size()); j++)
{
cout << "info multipv " << j + 1
- << " score " << value_to_uci(rml.move_score(j))
+ << " score " << value_to_uci(rml.pv_score(j))
<< " depth " << (j <= i ? Iteration : Iteration - 1)
<< " time " << current_search_time()
<< " nodes " << pos.nodes_searched()
cout << endl;
}
- alpha = rml.move_score(Min(i, MultiPV - 1));
+ alpha = rml.pv_score(Min(i, MultiPV - 1));
}
} // PV move or new best move
threatMove = sp->threatMove;
mateThreat = sp->mateThreat;
goto split_point_start;
- } else {} // Hack to fix icc's "statement is unreachable" warning
+ }
+ else {} // Hack to fix icc's "statement is unreachable" warning
// Step 1. Initialize node and poll. Polling can abort search
ss->currentMove = ss->bestMove = threatMove = MOVE_NONE;
}
// Step 2. Check for aborted search and immediate draw
- if ( AbortSearch || ThreadsMgr.thread_should_stop(threadID)
- || pos.is_draw() || ply >= PLY_MAX - 1)
+ if ( AbortSearch
+ || ThreadsMgr.cutoff_at_splitpoint(threadID)
+ || pos.is_draw()
+ || ply >= PLY_MAX - 1)
return VALUE_DRAW;
// Step 3. Mate distance pruning
threatMove = (ss+1)->bestMove;
if ( depth < ThreatDepth
&& (ss-1)->reduction
+ && threatMove != MOVE_NONE
&& connected_moves(pos, (ss-1)->currentMove, threatMove))
return beta - 1;
}
// Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !ThreadsMgr.thread_should_stop(threadID))
+ && !ThreadsMgr.cutoff_at_splitpoint(threadID))
{
assert(move_is_ok(move));
continue;
}
- // Prune neg. see moves at low depths
+ // Prune moves with negative SEE at low depths
if ( predictedDepth < 2 * ONE_PLY
&& bestValue > value_mated_in(PLY_MAX)
&& pos.see_sign(move) < 0)
// Step extra. pv search (only in PV nodes)
// The first move in list is the expected PV
- if (!SpNode && PvNode && moveCount == 1)
+ if (PvNode && moveCount == 1)
value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, ply+1);
else
{
&& !captureOrPromotion
&& !dangerous
&& !move_is_castle(move)
- && !(ss->killers[0] == move || ss->killers[1] == move))
+ && ss->killers[0] != move
+ && ss->killers[1] != move)
{
ss->reduction = reduction<PvNode>(depth, moveCount);
+
if (ss->reduction)
{
alpha = SpNode ? sp->alpha : alpha;
alpha = sp->alpha;
}
- if (value > bestValue && !(SpNode && ThreadsMgr.thread_should_stop(threadID)))
+ if (value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID)))
{
bestValue = value;
if (value > alpha)
{
- if (SpNode && (!PvNode || value >= beta))
- sp->stopRequest = true;
-
if (PvNode && value < beta) // We want always alpha < beta
{
alpha = value;
+
if (SpNode)
sp->alpha = value;
}
+ else if (SpNode)
+ sp->betaCutoff = true;
if (value == value_mate_in(ply + 1))
ss->mateKiller = move;
&& bestValue < beta
&& ThreadsMgr.available_thread_exists(threadID)
&& !AbortSearch
- && !ThreadsMgr.thread_should_stop(threadID)
+ && !ThreadsMgr.cutoff_at_splitpoint(threadID)
&& Iteration <= 99)
ThreadsMgr.split<FakeSplit>(pos, ss, ply, &alpha, beta, &bestValue, depth,
threatMove, mateThreat, moveCount, &mp, PvNode);
// Step 20. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (!SpNode && !AbortSearch && !ThreadsMgr.thread_should_stop(threadID))
+ if (!SpNode && !AbortSearch && !ThreadsMgr.cutoff_at_splitpoint(threadID))
{
move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
Value bestValue, value, evalMargin, futilityValue, futilityBase;
bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
const TTEntry* tte;
+ Depth ttDepth;
Value oldAlpha = alpha;
ss->bestMove = ss->currentMove = MOVE_NONE;
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- // Decide whether or not to include checks
+ // 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.
isCheck = pos.is_check();
-
- Depth d;
- if (isCheck || depth >= -ONE_PLY)
- d = DEPTH_ZERO;
- else
- d = DEPTH_ZERO - ONE_PLY;
+ ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- if (!PvNode && tte && ok_to_use_TT(tte, d, beta, ply))
+ if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ply))
{
ss->bestMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ply);
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
- // queen promotions and checks (only if depth == 0 or depth == -ONE_PLY
- // and we are near beta) will be generated.
- MovePicker mp = MovePicker(pos, ttMove, d, H);
+ // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
+ // be generated.
+ MovePicker mp(pos, ttMove, depth, H);
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
// Update transposition table
ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, d, ss->bestMove, ss->eval, evalMargin);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
Square f1, t1, f2, t2;
Piece p;
- assert(move_is_ok(m1));
- assert(move_is_ok(m2));
-
- if (m2 == MOVE_NONE)
- return false;
+ assert(m1 && move_is_ok(m1));
+ assert(m2 && move_is_ok(m2));
// Case 1: The moving piece is the same in both moves
f2 = move_from(m2);
}
- // thread_should_stop() checks whether the thread should stop its search.
- // This can happen if a beta cutoff has occurred in the thread's currently
- // active split point, or in some ancestor of the current split point.
+ // cutoff_at_splitpoint() checks whether a beta cutoff has occurred in
+ // the thread's currently active split point, or in some ancestor of
+ // the current split point.
- bool ThreadsManager::thread_should_stop(int threadID) const {
+ bool ThreadsManager::cutoff_at_splitpoint(int threadID) const {
assert(threadID >= 0 && threadID < activeThreads);
SplitPoint* sp = threads[threadID].splitPoint;
- for ( ; sp && !sp->stopRequest; sp = sp->parent) {}
+ for ( ; sp && !sp->betaCutoff; sp = sp->parent) {}
return sp != NULL;
}
// Initialize the split point object
splitPoint.parent = masterThread.splitPoint;
splitPoint.master = master;
- splitPoint.stopRequest = false;
+ splitPoint.betaCutoff = false;
splitPoint.ply = ply;
splitPoint.depth = depth;
splitPoint.threatMove = threatMove;
moves[count].move = ss[0].currentMove = moves[count].pv[0] = cur->move;
moves[count].pv[1] = MOVE_NONE;
pos.do_move(cur->move, st);
- moves[count].score = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1);
+ moves[count].pvScore = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1);
pos.undo_move(cur->move);
count++;
}
// Score root moves using the standard way used in main search, the moves
// are scored according to the order in which are returned by MovePicker.
+ // This is the second order score that is used to compare the moves when
+ // the first order pv scores of both moves are equal.
- void RootMoveList::score_moves(const Position& pos)
+ void RootMoveList::set_non_pv_scores(const Position& pos)
{
Move move;
- int score = 1000;
- MovePicker mp = MovePicker(pos, MOVE_NONE, ONE_PLY, H);
+ Value score = VALUE_ZERO;
+ MovePicker mp(pos, MOVE_NONE, ONE_PLY, H);
while ((move = mp.get_next_move()) != MOVE_NONE)
for (int i = 0; i < count; i++)
if (moves[i].move == move)
{
- moves[i].mp_score = score--;
+ moves[i].nonPvScore = score--;
break;
}
}
// RootMoveList simple methods definitions
- void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
+ void RootMoveList::set_pv(int moveNum, const Move pv[]) {
int j;