X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=7a8d3253048d2db2d7595493cb242692970f6d57;hp=a5b07d2f18c30185d2da0192076dd612578a0480;hb=62937d1007e0f97e629f376adca4f4ad738e95d1;hpb=1463881153a20690871086208eaf76f20041effb diff --git a/src/search.cpp b/src/search.cpp index a5b07d2f..7a8d3253 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -31,8 +31,8 @@ #include "movepick.h" #include "position.h" #include "search.h" -#include "timeman.h" #include "thread.h" +#include "timeman.h" #include "tt.h" #include "uci.h" #include "syzygy/tbprobe.h" @@ -63,12 +63,14 @@ namespace { enum NodeType { NonPV, PV }; // Sizes and phases of the skip-blocks, used for distributing search depths across the threads - const int SkipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 }; - const int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 }; + constexpr int SkipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 }; + constexpr int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 }; - // Razoring and futility margins - const int RazorMargin = 590; - Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); } + // Razor and futility margins + constexpr int RazorMargin[] = {0, 590, 604}; + Value futility_margin(Depth d, bool improving) { + return Value((175 - 50 * improving) * d / ONE_PLY); + } // Futility and reductions lookup tables, initialized at startup int FutilityMoveCounts[2][16]; // [improving][depth] @@ -98,7 +100,7 @@ namespace { template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning); - template + template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO); Value value_to_tt(Value v, int ply); @@ -288,7 +290,7 @@ void Thread::search() { std::memset(ss-4, 0, 7 * sizeof(Stack)); for (int i = 4; i > 0; i--) - (ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel + (ss-i)->contHistory = this->contHistory[NO_PIECE][0].get(); // Use as sentinel bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; @@ -325,7 +327,7 @@ void Thread::search() { // Age out PV variability metric if (mainThread) - mainThread->bestMoveChanges *= 0.505, mainThread->failedLow = false; + mainThread->bestMoveChanges *= 0.517, mainThread->failedLow = false; // Save the last iteration's scores before first PV line is searched and // all the move scores except the (new) PV are set to -VALUE_INFINITE. @@ -345,11 +347,10 @@ void Thread::search() { alpha = std::max(rootMoves[PVIdx].previousScore - delta,-VALUE_INFINITE); beta = std::min(rootMoves[PVIdx].previousScore + delta, VALUE_INFINITE); - // Adjust contempt based on current bestValue - ct = Options["Contempt"] * PawnValueEg / 100 // From centipawns - + (bestValue > 500 ? 50: // Dynamic contempt - bestValue < -500 ? -50: - bestValue / 10); + ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns + + // Adjust contempt based on current bestValue (dynamic contempt) + ct += int(std::round(48 * atan(float(bestValue) / 128))); Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2) : -make_score(ct, ct / 2)); @@ -444,21 +445,21 @@ void Thread::search() { const int F[] = { mainThread->failedLow, bestValue - mainThread->previousScore }; - int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1])); + int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1])); // If the bestMove is stable over several iterations, reduce time accordingly timeReduction = 1.0; for (int i : {3, 4, 5}) if (lastBestMoveDepth * i < completedDepth) - timeReduction *= 1.3; + timeReduction *= 1.25; // Use part of the gained time from a previous stable move for the current move - double unstablePvFactor = 1.0 + mainThread->bestMoveChanges; - unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.51) / timeReduction; + double bestMoveInstability = 1.0 + mainThread->bestMoveChanges; + bestMoveInstability *= std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction; // Stop the search if we have only one legal move, or if available time elapsed if ( rootMoves.size() == 1 - || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 605) + || Time.elapsed() > Time.optimum() * bestMoveInstability * improvingFactor / 581) { // If we are allowed to ponder do not stop the search now but // keep pondering until the GUI sends "ponderhit" or "stop". @@ -489,7 +490,11 @@ namespace { template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning) { - const bool PvNode = NT == PV; + // Use quiescence search when needed + if (depth < ONE_PLY) + return qsearch(pos, ss, alpha, beta); + + constexpr bool PvNode = NT == PV; const bool rootNode = PvNode && ss->ply == 0; assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); @@ -517,13 +522,6 @@ namespace { bestValue = -VALUE_INFINITE; maxValue = VALUE_INFINITE; - // Initialize statScore to zero for the childs of the current position. - // So statScore is shared between sibling positions and only the first sibling - // starts with statScore = 0. Later siblings start with the last calculated - // statScore of the previous sibling. This influences in LMR the reduction rules - // which based on the statScore of parent position. - (ss+1)->statScore = 0; - // Check for the available remaining time if (thisThread == Threads.main()) static_cast(thisThread)->check_time(); @@ -556,10 +554,17 @@ namespace { (ss+1)->ply = ss->ply + 1; ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; - ss->contHistory = &thisThread->contHistory[NO_PIECE][0]; + ss->contHistory = thisThread->contHistory[NO_PIECE][0].get(); (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; Square prevSq = to_sq((ss-1)->currentMove); + // Initialize statScore to zero for the grandchildren of the current position. + // So statScore is shared between all grandchildren and only the first grandchild + // starts with statScore = 0. Later grandchildren start with the last calculated + // statScore of the previous grandchild. This influences the reduction rules in + // LMR which are based on the statScore of parent position. + (ss+2)->statScore = 0; + // Step 4. Transposition table lookup. 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. @@ -594,7 +599,7 @@ namespace { else if (!pos.capture_or_promotion(ttMove)) { int penalty = -stat_bonus(depth); - thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty); + thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty; update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty); } } @@ -652,6 +657,7 @@ namespace { if (inCheck) { ss->staticEval = eval = VALUE_NONE; + improving = false; goto moves_loop; } else if (ttHit) @@ -675,19 +681,27 @@ namespace { ss->staticEval, TT.generation()); } + improving = ss->staticEval >= (ss-2)->staticEval + ||(ss-2)->staticEval == VALUE_NONE; + if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move())) goto moves_loop; // Step 7. Razoring (skipped when in check) - if ( !PvNode - && depth <= ONE_PLY - && eval + RazorMargin <= alpha) - return qsearch(pos, ss, alpha, alpha+1); + if ( !PvNode + && depth < 3 * ONE_PLY + && eval <= alpha - RazorMargin[depth / ONE_PLY]) + { + Value ralpha = alpha - (depth >= 2 * ONE_PLY) * RazorMargin[depth / ONE_PLY]; + Value v = qsearch(pos, ss, ralpha, ralpha+1); + if (depth < 2 * ONE_PLY || v <= ralpha) + return v; + } // Step 8. Futility pruning: child node (skipped when in check) if ( !rootNode && depth < 7 * ONE_PLY - && eval - futility_margin(depth) >= beta + && eval - futility_margin(depth, improving) >= beta && eval < VALUE_KNOWN_WIN) // Do not return unproven wins return eval; @@ -703,11 +717,12 @@ namespace { Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY; ss->currentMove = MOVE_NULL; - ss->contHistory = &thisThread->contHistory[NO_PIECE][0]; + ss->contHistory = thisThread->contHistory[NO_PIECE][0].get(); pos.do_null_move(st); - Value nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -beta+1) - : - search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true); + + Value nullValue = -search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true); + pos.undo_null_move(); if (nullValue >= beta) @@ -724,8 +739,7 @@ namespace { thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4; thisThread->nmp_odd = ss->ply % 2; - Value v = depth-R < ONE_PLY ? qsearch(pos, ss, beta-1, beta) - : search(pos, ss, beta-1, beta, depth-R, false, true); + Value v = search(pos, ss, beta-1, beta, depth-R, false, true); thisThread->nmp_odd = thisThread->nmp_ply = 0; @@ -743,31 +757,32 @@ namespace { { assert(is_ok((ss-1)->currentMove)); - Value rbeta = std::min(beta + 200, VALUE_INFINITE); + Value rbeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE); MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory); + int probCutCount = 0; - while ((move = mp.next_move()) != MOVE_NONE) + while ( (move = mp.next_move()) != MOVE_NONE + && probCutCount < 3) if (pos.legal(move)) { + probCutCount++; + ss->currentMove = move; - ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)]; + ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get(); assert(depth >= 5 * ONE_PLY); pos.do_move(move, st); - // Perform a preliminary search at depth 1 to verify that the move holds. - // We will only do this search if the depth is not 5, thus avoiding two - // searches at depth 1 in a row. - if (depth != 5 * ONE_PLY) - value = -search(pos, ss+1, -rbeta, -rbeta+1, ONE_PLY, !cutNode, true); + // Perform a preliminary qsearch to verify that the move holds + value = -qsearch(pos, ss+1, -rbeta, -rbeta+1); - // If the first search was skipped or was performed and held, perform - // the regular search. - if (depth == 5 * ONE_PLY || value >= rbeta) + // If the qsearch held perform the regular search + if (value >= rbeta) value = -search(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false); pos.undo_move(move); + if (value >= rbeta) return value; } @@ -776,7 +791,7 @@ namespace { // Step 11. Internal iterative deepening (skipped when in check) if ( depth >= 6 * ONE_PLY && !ttMove - && (PvNode || ss->staticEval + 256 >= beta)) + && (PvNode || ss->staticEval + 128 >= beta)) { Depth d = 3 * depth / 4 - 2 * ONE_PLY; search(pos, ss, alpha, beta, d, cutNode, true); @@ -793,9 +808,6 @@ moves_loop: // When in check, search starts from here MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &thisThread->captureHistory, contHist, countermove, ss->killers); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc - improving = ss->staticEval >= (ss-2)->staticEval - /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */ - ||(ss-2)->staticEval == VALUE_NONE; singularExtensionNode = !rootNode && depth >= 8 * ONE_PLY @@ -925,7 +937,7 @@ moves_loop: // When in check, search starts from here // Update the current move (this must be done after singular extension search) ss->currentMove = move; - ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)]; + ss->contHistory = thisThread->contHistory[movedPiece][to_sq(move)].get(); // Step 15. Make the move pos.do_move(move, st, givesCheck); @@ -993,10 +1005,7 @@ moves_loop: // When in check, search starts from here // Step 17. Full depth search when LMR is skipped or fails high if (doFullDepthSearch) - value = newDepth < ONE_PLY ? - givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha) - : -qsearch(pos, ss+1, -(alpha+1), -alpha) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false); // 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 @@ -1006,10 +1015,7 @@ moves_loop: // When in check, search starts from here (ss+1)->pv = pv; (ss+1)->pv[0] = MOVE_NONE; - value = newDepth < ONE_PLY ? - givesCheck ? -qsearch(pos, ss+1, -beta, -alpha) - : -qsearch(pos, ss+1, -beta, -alpha) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, false); + value = -search(pos, ss+1, -beta, -alpha, newDepth, false, false); } // Step 18. Undo move @@ -1138,17 +1144,15 @@ moves_loop: // When in check, search starts from here // qsearch() is the quiescence search function, which is called by the main // search function with depth zero, or recursively with depth less than ONE_PLY. - - template + template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { - const bool PvNode = NT == PV; + constexpr bool PvNode = NT == PV; assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(depth <= DEPTH_ZERO); assert(depth / ONE_PLY * ONE_PLY == depth); - assert(InCheck == bool(pos.checkers())); Move pv[MAX_PLY+1]; StateInfo st; @@ -1157,7 +1161,7 @@ moves_loop: // When in check, search starts from here Move ttMove, move, bestMove; Depth ttDepth; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool ttHit, givesCheck, evasionPrunable; + bool ttHit, inCheck, givesCheck, evasionPrunable; int moveCount; if (PvNode) @@ -1169,19 +1173,20 @@ moves_loop: // When in check, search starts from here (ss+1)->ply = ss->ply + 1; ss->currentMove = bestMove = MOVE_NONE; + inCheck = pos.checkers(); moveCount = 0; // Check for an immediate draw or maximum ply reached if ( pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) - return (ss->ply >= MAX_PLY && !InCheck) ? evaluate(pos) : VALUE_DRAW; + return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW; assert(0 <= ss->ply && ss->ply < MAX_PLY); // 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. - ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS + ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; // Transposition table lookup posKey = pos.key(); @@ -1198,7 +1203,7 @@ moves_loop: // When in check, search starts from here return ttValue; // Evaluate the position statically - if (InCheck) + if (inCheck) { ss->staticEval = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; @@ -1253,7 +1258,7 @@ moves_loop: // When in check, search starts from here moveCount++; // Futility pruning - if ( !InCheck + if ( !inCheck && !givesCheck && futilityBase > -VALUE_KNOWN_WIN && !pos.advanced_pawn_push(move)) @@ -1276,13 +1281,13 @@ moves_loop: // When in check, search starts from here } // Detect non-capture evasions that are candidates to be pruned - evasionPrunable = InCheck + evasionPrunable = inCheck && (depth != DEPTH_ZERO || moveCount > 2) && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.capture(move); // Don't search moves with negative SEE values - if ( (!InCheck || evasionPrunable) + if ( (!inCheck || evasionPrunable) && !pos.see_ge(move)) continue; @@ -1300,8 +1305,7 @@ moves_loop: // When in check, search starts from here // Make and search the move pos.do_move(move, st, givesCheck); - value = givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY) - : -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); + value = -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1334,7 +1338,7 @@ moves_loop: // When in check, search starts from here // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. - if (InCheck && bestValue == -VALUE_INFINITE) + if (inCheck && bestValue == -VALUE_INFINITE) return mated_in(ss->ply); // Plies to mate from the root tte->save(posKey, value_to_tt(bestValue, ss->ply), @@ -1389,7 +1393,7 @@ moves_loop: // When in check, search starts from here for (int i : {1, 2, 4}) if (is_ok((ss-i)->currentMove)) - (ss-i)->contHistory->update(pc, to, bonus); + (*(ss-i)->contHistory)[pc][to] << bonus; } @@ -1401,14 +1405,14 @@ moves_loop: // When in check, search starts from here CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory; Piece moved_piece = pos.moved_piece(move); PieceType captured = type_of(pos.piece_on(to_sq(move))); - captureHistory.update(moved_piece, to_sq(move), captured, bonus); + captureHistory[moved_piece][to_sq(move)][captured] << bonus; // Decrease all the other played capture moves for (int i = 0; i < captureCnt; ++i) { moved_piece = pos.moved_piece(captures[i]); captured = type_of(pos.piece_on(to_sq(captures[i]))); - captureHistory.update(moved_piece, to_sq(captures[i]), captured, -bonus); + captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus; } } @@ -1426,7 +1430,7 @@ moves_loop: // When in check, search starts from here Color us = pos.side_to_move(); Thread* thisThread = pos.this_thread(); - thisThread->mainHistory.update(us, move, bonus); + thisThread->mainHistory[us][from_to(move)] << bonus; update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus); if (is_ok((ss-1)->currentMove)) @@ -1438,7 +1442,7 @@ moves_loop: // When in check, search starts from here // Decrease all the other played quiet moves for (int i = 0; i < quietsCnt; ++i) { - thisThread->mainHistory.update(us, quiets[i], -bonus); + thisThread->mainHistory[us][from_to(quiets[i])] << -bonus; update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); } } @@ -1487,7 +1491,7 @@ void MainThread::check_time() { return; // When using nodes, ensure checking rate is not lower than 0.1% of nodes - callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024)) : 4096; + callsCnt = Limits.nodes ? std::min(1024, int(Limits.nodes / 1024)) : 1024; static TimePoint lastInfoTime = now();