void idle_loop(int threadID, SplitPoint* sp);
template <bool Fake>
- void split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
+ void split(const Position& pos, SearchStack* ss, Value* alpha, const Value beta, Value* bestValue,
Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, int master, bool pvNode);
private:
Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
template <NodeType PvNode>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
+ Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
template <NodeType PvNode>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply, int threadID);
+ Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID);
template <NodeType PvNode>
void sp_search(SplitPoint* sp, int threadID);
template <NodeType PvNode>
Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous);
- void init_node(SearchStack* ss, int ply, int threadID);
void update_pv(SearchStack* ss, int ply);
void sp_update_pv(SearchStack* pss, SearchStack* ss, int ply);
bool connected_moves(const Position& pos, Move m1, Move m2);
bool value_is_mate(Value value);
bool move_is_killer(Move m, SearchStack* ss);
bool ok_to_do_nullmove(const Position& pos);
- bool ok_to_prune(const Position& pos, Move m, Move threat);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
+ bool connected_threat(const Position& pos, Move m, Move threat);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack* ss);
H.clear();
init_ss_array(ss);
ValueByIteration[1] = rml.get_move_score(0);
+ p.reset_ply();
Iteration = 1;
// Is one move significantly better than others after initial scoring ?
alpha = -VALUE_INFINITE;
// Full depth PV search, done on first move or after a fail high
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 1, false, 0);
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, 0);
}
else
{
if (ss->reduction)
{
// Reduced depth non-pv search using alpha as upperbound
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1, true, 0);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0);
doFullDepthSearch = (value > alpha);
}
}
{
// Full depth non-pv search using alpha as upperbound
ss->reduction = Depth(0);
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, 1, true, 0);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0);
// If we are above alpha then research at same depth but as PV
// to get a correct score or eventually a fail high above beta.
if (value > alpha)
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 1, false, 0);
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, 0);
}
}
template <NodeType PvNode>
Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth,
- int ply, bool allowNullmove, int threadID, Move excludedMove) {
+ bool allowNullmove, int threadID, Move excludedMove) {
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
- assert(ply >= 0 && ply < PLY_MAX);
+ assert(pos.ply() > 0 && pos.ply() < PLY_MAX);
assert(threadID >= 0 && threadID < TM.active_threads());
Move movesSearched[256];
bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
bool mateThreat = false;
int moveCount = 0;
+ int ply = pos.ply();
refinedValue = bestValue = value = -VALUE_INFINITE;
oldAlpha = alpha;
- if (depth < OnePly)
- return qsearch<PvNode>(pos, ss, alpha, beta, Depth(0), ply, threadID);
+ // Step 1. Initialize node and poll. Polling can abort search
+ TM.incrementNodeCounter(threadID);
+ ss->init(ply);
+ (ss + 2)->initKillers();
- // Step 1. Initialize node and poll
- // Polling can abort search.
- init_node(ss, ply, threadID);
+ if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
+ {
+ NodesSincePoll = 0;
+ poll();
+ }
// Step 2. Check for aborted search and immediate draw
if (AbortSearch || TM.thread_should_stop(threadID))
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value rbeta = beta - razor_margin(depth);
- Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
+ Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, Depth(0), threadID);
if (v < rbeta)
// Logically we should return (v + razor_margin(depth)), but
// surprisingly this did slightly weaker in tests.
pos.do_null_move(st);
- nullValue = -search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*OnePly, ply+1, false, threadID);
-
+ nullValue = depth-R*OnePly < OnePly ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
+ : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*OnePly, false, threadID);
pos.undo_null_move();
if (nullValue >= beta)
return nullValue;
// Do zugzwang verification search
- Value v = search<NonPV>(pos, ss, alpha, beta, depth-5*OnePly, ply, false, threadID);
+ Value v = search<NonPV>(pos, ss, alpha, beta, depth-5*OnePly, false, threadID);
if (v >= beta)
return nullValue;
} else {
&& (PvNode || (!isCheck && ss->eval >= beta - IIDMargin)))
{
Depth d = (PvNode ? depth - 2 * OnePly : depth / 2);
- search<PvNode>(pos, ss, alpha, beta, d, ply, false, threadID);
+ search<PvNode>(pos, ss, alpha, beta, d, false, threadID);
ttMove = ss->pv[ply];
tte = TT.retrieve(posKey);
}
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
Value b = ttValue - SingularExtensionMargin;
- Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2, ply, false, threadID, move);
+ Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2, false, threadID, move);
if (v < ttValue - SingularExtensionMargin)
ext = OnePly;
{
// Move count based pruning
if ( moveCount >= futility_move_count(depth)
- && ok_to_prune(pos, move, ss->threatMove)
+ && !(ss->threatMove && connected_threat(pos, move, ss->threatMove))
&& bestValue > value_mated_in(PLY_MAX))
continue;
// Step extra. pv search (only in PV nodes)
// The first move in list is the expected PV
if (PvNode && moveCount == 1)
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, ply+1, false, threadID);
+ value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, threadID);
else
{
// Step 14. Reduced depth search
ss->reduction = reduction<PvNode>(depth, moveCount);
if (ss->reduction)
{
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, ply+1, true, threadID);
+ Depth d = newDepth - ss->reduction;
+ value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true, threadID);
+
doFullDepthSearch = (value > alpha);
}
// if the move fails high again then go with full depth search.
if (doFullDepthSearch && ss->reduction > 2 * OnePly)
{
+ assert(newDepth - OnePly >= OnePly);
+
ss->reduction = OnePly;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, ply+1, true, threadID);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID);
doFullDepthSearch = (value > alpha);
}
}
if (doFullDepthSearch)
{
ss->reduction = Depth(0);
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, ply+1, true, threadID);
+ value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, true, threadID);
// Step extra. pv search (only in PV nodes)
// Search only for possible new PV nodes, if instead value >= beta then
// parent node fails low with value <= alpha and tries another move.
if (PvNode && value > alpha && value < beta)
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, ply+1, false, threadID);
+ value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, threadID);
}
}
&& TM.available_thread_exists(threadID)
&& !AbortSearch
&& !TM.thread_should_stop(threadID))
- TM.split<FakeSplit>(pos, ss, ply, &alpha, beta, &bestValue, depth,
+ TM.split<FakeSplit>(pos, ss, &alpha, beta, &bestValue, depth,
mateThreat, &moveCount, &mp, threadID, PvNode);
}
// less than OnePly).
template <NodeType PvNode>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta,
- Depth depth, int ply, int threadID) {
+ Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) {
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
assert(depth <= 0);
- assert(ply >= 0 && ply < PLY_MAX);
+ assert(pos.ply() > 0 && pos.ply() < PLY_MAX);
assert(threadID >= 0 && threadID < TM.active_threads());
EvalInfo ei;
bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
const TTEntry* tte = NULL;
int moveCount = 0;
+ int ply = pos.ply();
Value oldAlpha = alpha;
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
- init_node(ss, ply, threadID);
-
- // After init_node() that calls poll()
- if (AbortSearch || TM.thread_should_stop(threadID))
- return Value(0);
+ TM.incrementNodeCounter(threadID);
+ ss->init(ply);
+ // Check for an instant draw or maximum ply reached
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
// Make and search the move
pos.do_move(move, st, ci, moveIsCheck);
- value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-OnePly, ply+1, threadID);
+ value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-OnePly, threadID);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
Position pos(*sp->pos);
CheckInfo ci(pos);
+ int ply = pos.ply();
SearchStack* ss = sp->sstack[threadID] + 1;
isCheck = pos.is_check();
{
// Move count based pruning
if ( moveCount >= futility_move_count(sp->depth)
- && ok_to_prune(pos, move, ss->threatMove)
+ && !(ss->threatMove && connected_threat(pos, move, ss->threatMove))
&& sp->bestValue > value_mated_in(PLY_MAX))
{
lock_grab(&(sp->lock));
if (ss->reduction)
{
Value localAlpha = sp->alpha;
- value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1, true, threadID);
+ value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID);
doFullDepthSearch = (value > localAlpha);
}
{
ss->reduction = OnePly;
Value localAlpha = sp->alpha;
- value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1, true, threadID);
+ value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID);
doFullDepthSearch = (value > localAlpha);
}
}
{
ss->reduction = Depth(0);
Value localAlpha = sp->alpha;
- value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, sp->ply+1, true, threadID);
+ value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID);
if (PvNode && value > localAlpha && value < sp->beta)
- value = -search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth, sp->ply+1, false, threadID);
+ value = -search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID);
}
// Step 16. Undo move
if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta
sp->alpha = value;
- sp_update_pv(sp->parentSstack, ss, sp->ply);
+ sp_update_pv(sp->parentSstack, ss, ply);
}
}
}
lock_release(&(sp->lock));
}
- // init_node() is called at the beginning of all the search functions
- // (search() qsearch(), and so on) and initializes the
- // search stack object corresponding to the current node. Once every
- // NodesBetweenPolls nodes, init_node() also calls poll(), which polls
- // for user input and checks whether it is time to stop the search.
-
- void init_node(SearchStack* ss, int ply, int threadID) {
-
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < TM.active_threads());
-
- TM.incrementNodeCounter(threadID);
-
- if (threadID == 0)
- {
- NodesSincePoll++;
- if (NodesSincePoll >= NodesBetweenPolls)
- {
- poll();
- NodesSincePoll = 0;
- }
- }
- ss->init(ply);
- (ss + 2)->initKillers();
- }
-
// update_pv() is called whenever a search returns a value > alpha.
// It updates the PV in the SearchStack object corresponding to the
// current node.
}
- // ok_to_prune() tests whether it is safe to forward prune a move. Only
- // non-tactical moves late in the move list close to the leaves are
- // candidates for pruning.
+ // connected_threat() tests whether it is safe to forward prune a move or if
+ // is somehow coonected to the threat move returned by null search.
- bool ok_to_prune(const Position& pos, Move m, Move threat) {
+ bool connected_threat(const Position& pos, Move m, Move threat) {
assert(move_is_ok(m));
- assert(threat == MOVE_NONE || move_is_ok(threat));
+ assert(threat && move_is_ok(threat));
assert(!pos.move_is_check(m));
assert(!pos.move_is_capture_or_promotion(m));
assert(!pos.move_is_passed_pawn_push(m));
Square mfrom, mto, tfrom, tto;
- // Prune if there isn't any threat move
- if (threat == MOVE_NONE)
- return true;
-
mfrom = move_from(m);
mto = move_to(m);
tfrom = move_from(threat);
// Case 1: Don't prune moves which move the threatened piece
if (mfrom == tto)
- return false;
+ return true;
// Case 2: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune move which defend it.
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
|| pos.type_of_piece_on(tfrom) == KING)
&& pos.move_attacks_square(m, tto))
- return false;
+ return true;
// Case 3: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
if ( piece_is_slider(pos.piece_on(tfrom))
&& bit_is_set(squares_between(tfrom, tto), mto)
&& pos.see_sign(m) >= 0)
- return false;
+ return true;
- return true;
+ return false;
}
// Initialize SplitPointStack locks
for (i = 0; i < MAX_THREADS; i++)
for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
- {
- SplitPointStack[i][j].parent = NULL;
lock_init(&(SplitPointStack[i][j].lock), NULL);
- }
// Will be set just before program exits to properly end the threads
AllThreadsShouldExit = false;
// Wait for thread termination
for (int i = 1; i < MAX_THREADS; i++)
- while (threads[i].state != THREAD_TERMINATED);
+ while (threads[i].state != THREAD_TERMINATED) {}
// Now we can safely destroy the locks
for (int i = 0; i < MAX_THREADS; i++)
// split() returns.
template <bool Fake>
- void ThreadsManager::split(const Position& p, SearchStack* ss, int ply, Value* alpha,
- const Value beta, Value* bestValue, Depth depth, bool mateThreat,
- int* moveCount, MovePicker* mp, int master, bool pvNode) {
+ void ThreadsManager::split(const Position& p, SearchStack* ss, Value* alpha, const Value beta,
+ Value* bestValue, Depth depth, bool mateThreat, int* moveCount,
+ MovePicker* mp, int master, bool pvNode) {
assert(p.is_ok());
- assert(ply > 0 && ply < PLY_MAX);
assert(*bestValue >= -VALUE_INFINITE);
assert(*bestValue <= *alpha);
assert(*alpha < beta);
// Initialize the split point object
splitPoint->parent = threads[master].splitPoint;
splitPoint->stopRequest = false;
- splitPoint->ply = ply;
splitPoint->depth = depth;
splitPoint->mateThreat = mateThreat;
splitPoint->alpha = *alpha;
init_ss_array(ss);
pos.do_move(cur->move, st);
moves[count].move = cur->move;
- moves[count].score = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
+ moves[count].score = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 0);
moves[count].pv[0] = cur->move;
moves[count].pv[1] = MOVE_NONE;
pos.undo_move(cur->move);