template <bool Fake>
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);
+ Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode);
private:
friend void poll();
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, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
+ Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
template <NodeType PvNode>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID);
+ Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
template <NodeType PvNode>
void sp_search(SplitPoint* sp, int threadID);
void poll();
void ponderhit();
void wait_for_stop_or_ponderhit();
- void init_ss_array(SearchStack* ss);
+ void init_ss_array(SearchStack* ss, int size);
void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value);
#if !defined(_MSC_VER)
Value id_loop(const Position& pos, Move searchMoves[]) {
- Position p(pos);
+ Position p(pos, pos.thread());
SearchStack ss[PLY_MAX_PLUS_2];
Move EasyMove = MOVE_NONE;
Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
// Initialize
TT.new_search();
H.clear();
- init_ss_array(ss);
+ init_ss_array(ss, PLY_MAX_PLUS_2);
ValueByIteration[1] = rml.get_move_score(0);
p.reset_ply();
Iteration = 1;
// Step 5. Evaluate the position statically
// At root we do this only to get reference value for child nodes
if (!isCheck)
- ss->eval = evaluate(pos, ei, 0);
+ ss->eval = evaluate(pos, ei);
// Step 6. Razoring (omitted at root)
// Step 7. Static null move pruning (omitted at root)
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, false, 0);
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth);
}
else
{
ss->reduction = reduction<PV>(depth, i - MultiPV + 2);
if (ss->reduction)
{
+ assert(newDepth-ss->reduction >= OnePly);
+
// Reduced depth non-pv search using alpha as upperbound
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction);
+ doFullDepthSearch = (value > alpha);
+ }
+
+ // The move failed high, but if reduction is very big we could
+ // face a false positive, retry with a less aggressive reduction,
+ // 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);
doFullDepthSearch = (value > alpha);
}
+ ss->reduction = Depth(0); // Restore original reduction
}
// Step 15. Full depth search
if (doFullDepthSearch)
{
// Full depth non-pv search using alpha as upperbound
- ss->reduction = Depth(0);
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
// 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, false, 0);
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth);
}
}
// search<>() is the main search function for both PV and non-PV nodes
template <NodeType PvNode>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth,
- bool allowNullmove, int threadID, Move excludedMove) {
+ Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
assert(pos.ply() > 0 && pos.ply() < PLY_MAX);
- assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(pos.thread() >= 0 && pos.thread() < TM.active_threads());
Move movesSearched[256];
EvalInfo ei;
StateInfo st;
const TTEntry* tte;
- Move ttMove, move;
+ Key posKey;
+ Move ttMove, move, excludedMove;
Depth ext, newDepth;
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific
bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
bool mateThreat = false;
int moveCount = 0;
+ int threadID = pos.thread();
int ply = pos.ply();
refinedValue = bestValue = value = -VALUE_INFINITE;
oldAlpha = alpha;
// We don't want the score of a partial search to overwrite a previous full search
// TT value, so we use a different position key in case of an excluded move exists.
- Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
+ excludedMove = ss->excludedMove;
+ posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
tte = TT.retrieve(posKey);
ttMove = (tte ? tte->move() : MOVE_NONE);
ei.kingDanger[pos.side_to_move()] = tte->king_danger();
}
else
- ss->eval = evaluate(pos, ei, threadID);
+ ss->eval = evaluate(pos, ei);
refinedValue = refine_eval(tte, ss->eval, ply); // Enhance accuracy with TT value if possible
update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
&& !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), threadID);
+ Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, Depth(0));
if (v < rbeta)
// Logically we should return (v + razor_margin(depth)), but
// surprisingly this did slightly weaker in tests.
// We're betting that the opponent doesn't have a move that will reduce
// the score by more than futility_margin(depth) if we do a null move.
if ( !PvNode
- && allowNullmove
+ && !ss->skipNullMove
&& depth < RazorDepth
&& refinedValue >= beta + futility_margin(depth, 0)
&& !isCheck
// at least beta. Otherwise we do a null move if static value is not more than
// NullMoveMargin under beta.
if ( !PvNode
- && allowNullmove
+ && !ss->skipNullMove
&& depth > OnePly
&& refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)
&& !isCheck
R++;
pos.do_null_move(st);
+ (ss+1)->skipNullMove = true;
- 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);
+ nullValue = depth-R*OnePly < OnePly ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, Depth(0))
+ : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*OnePly);
+ (ss+1)->skipNullMove = false;
pos.undo_null_move();
if (nullValue >= beta)
nullValue = beta;
// Do zugzwang verification search at high depths
- if ( depth < 6 * OnePly
- || search<NonPV>(pos, ss, alpha, beta, depth-5*OnePly, false, threadID) >= beta)
+ if (depth < 6 * OnePly)
+ return nullValue;
+
+ ss->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss, alpha, beta, depth-5*OnePly);
+ ss->skipNullMove = false;
+
+ 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, false, threadID);
+
+ ss->skipNullMove = true;
+ search<PvNode>(pos, ss, alpha, beta, d);
+ ss->skipNullMove = false;
+
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, false, threadID, move);
+ ss->excludedMove = move;
+ ss->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss, b - 1, b, depth / 2);
+ ss->skipNullMove = false;
+ ss->excludedMove = MOVE_NONE;
if (v < ttValue - SingularExtensionMargin)
ext = OnePly;
// Step extra. pv search (only in PV nodes)
// The first move in list is the expected PV
if (PvNode && moveCount == 1)
- value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, threadID);
+ value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0))
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
else
{
// Step 14. Reduced depth search
if (ss->reduction)
{
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);
+ value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0))
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
doFullDepthSearch = (value > alpha);
}
assert(newDepth - OnePly >= OnePly);
ss->reduction = OnePly;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction);
doFullDepthSearch = (value > alpha);
}
ss->reduction = Depth(0); // Restore original reduction
// Step 15. Full depth search
if (doFullDepthSearch)
{
- 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);
+ value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, Depth(0))
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
// 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 = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0), threadID)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, threadID);
+ value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -beta, -alpha, Depth(0))
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
}
}
&& !TM.thread_should_stop(threadID)
&& Iteration <= 99)
TM.split<FakeSplit>(pos, ss, &alpha, beta, &bestValue, depth,
- mateThreat, &moveCount, &mp, threadID, PvNode);
+ mateThreat, &moveCount, &mp, PvNode);
}
// Step 19. Check for mate and stalemate
// less than OnePly).
template <NodeType PvNode>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) {
+ Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
assert(depth <= 0);
assert(pos.ply() > 0 && pos.ply() < PLY_MAX);
- assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(pos.thread() >= 0 && pos.thread() < TM.active_threads());
EvalInfo ei;
StateInfo st;
Move ttMove, move;
- Value staticValue, bestValue, value, futilityBase, futilityValue;
+ Value staticValue, bestValue, value, futilityBase;
bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
const TTEntry* tte = NULL;
int moveCount = 0;
int ply = pos.ply();
Value oldAlpha = alpha;
+ Value futilityValue = VALUE_INFINITE;
- TM.incrementNodeCounter(threadID);
+ TM.incrementNodeCounter(pos.thread());
ss->init(ply);
// Check for an instant draw or maximum ply reached
ei.kingDanger[pos.side_to_move()] = tte->king_danger();
}
else
- staticValue = evaluate(pos, ei, threadID);
+ staticValue = evaluate(pos, ei);
if (!isCheck)
{
return bestValue;
}
- if (bestValue > alpha)
+ if (PvNode && bestValue > alpha)
alpha = bestValue;
// If we are near beta then try to get a cutoff pushing checks a bit further
&& !move_is_promotion(move)
&& !pos.move_is_passed_pawn_push(move))
{
+ // Can only decrease from previous move because of
+ // MVV ordering so we don't need to recheck.
+ if (futilityValue < alpha)
+ continue;
+
futilityValue = futilityBase
+ pos.endgame_value_of_piece_on(move_to(move))
+ (move_is_ep(move) ? PawnValueEndgame : Value(0));
// Make and search the move
pos.do_move(move, st, ci, moveIsCheck);
- value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-OnePly, threadID);
+ value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-OnePly);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
int moveCount;
value = -VALUE_INFINITE;
- Position pos(*sp->pos);
+ Position pos(*sp->pos, threadID);
CheckInfo ci(pos);
int ply = pos.ply();
SearchStack* ss = sp->sstack[threadID] + 1;
{
Value localAlpha = sp->alpha;
Depth d = newDepth - ss->reduction;
- value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID)
- : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, d, true, threadID);
+ value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0))
+ : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, d);
doFullDepthSearch = (value > localAlpha);
}
ss->reduction = OnePly;
Value localAlpha = sp->alpha;
- value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID);
+ value = -search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction);
doFullDepthSearch = (value > localAlpha);
}
ss->reduction = Depth(0); // Restore original reduction
if (doFullDepthSearch)
{
Value localAlpha = sp->alpha;
- value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID)
- : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID);
+ value = newDepth < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0))
+ : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth);
// 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 > localAlpha && value < sp->beta)
- value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), threadID)
- : - search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID);
+ value = newDepth < OnePly ? -qsearch<PV>(pos, ss+1, -sp->beta, -sp->alpha, Depth(0))
+ : - search<PV>(pos, ss+1, -sp->beta, -sp->alpha, newDepth);
}
// Step 16. Undo move
}
- // init_ss_array() does a fast reset of the first entries of a SearchStack array
+ // init_ss_array() does a fast reset of the first entries of a SearchStack
+ // array and of all the excludedMove and skipNullMove entries.
- void init_ss_array(SearchStack* ss) {
+ void init_ss_array(SearchStack* ss, int size) {
- for (int i = 0; i < 3; i++, ss++)
+ for (int i = 0; i < size; i++, ss++)
{
- ss->init(i);
- ss->initKillers();
+ ss->excludedMove = MOVE_NONE;
+ ss->skipNullMove = false;
+
+ if (i < 3)
+ {
+ ss->init(i);
+ ss->initKillers();
+ }
}
}
template <bool Fake>
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) {
+ MovePicker* mp, bool pvNode) {
assert(p.is_ok());
assert(*bestValue >= -VALUE_INFINITE);
assert(*bestValue <= *alpha);
assert(*alpha < beta);
assert(beta <= VALUE_INFINITE);
assert(depth > Depth(0));
- assert(master >= 0 && master < ActiveThreads);
+ assert(p.thread() >= 0 && p.thread() < ActiveThreads);
assert(ActiveThreads > 1);
+ int master = p.thread();
+
lock_grab(&MPLock);
// If no other thread is available to help us, or if we have too many
continue;
// Find a quick score for the move
- init_ss_array(ss);
+ init_ss_array(ss, PLY_MAX_PLUS_2);
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), 0);
+ moves[count].score = -qsearch<PV>(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0));
moves[count].pv[0] = cur->move;
moves[count].pv[1] = MOVE_NONE;
pos.undo_move(cur->move);
projects / stockfish / blobdiff