X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=f0783363e79766fc682dabbf42fc4d0d0cda9469;hp=548ea9143d37c48f3aeec316744803a797c13aa1;hb=f2681232e516da164196d7238482729da038ae1e;hpb=65c3bb8586eba11277f8297ef0f55c121772d82c diff --git a/src/search.cpp b/src/search.cpp index 548ea914..f0783363 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" @@ -63,16 +63,25 @@ 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 }; // Razor and futility margins - const int RazorMargin1 = 590; - const int RazorMargin2 = 604; + constexpr int RazorMargin[] = {0, 590, 604}; Value futility_margin(Depth d, bool improving) { return Value((175 - 50 * improving) * d / ONE_PLY); } + // Margin for pruning capturing moves: almost linear in depth + constexpr int CapturePruneMargin[] = { 0, + 1 * PawnValueEg * 1055 / 1000, + 2 * PawnValueEg * 1042 / 1000, + 3 * PawnValueEg * 963 / 1000, + 4 * PawnValueEg * 1038 / 1000, + 5 * PawnValueEg * 950 / 1000, + 6 * PawnValueEg * 930 / 1000 + }; + // Futility and reductions lookup tables, initialized at startup int FutilityMoveCounts[2][16]; // [improving][depth] int Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] @@ -101,7 +110,7 @@ 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); @@ -161,7 +170,7 @@ void Search::init() { Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0); // Increase reduction for non-PV nodes when eval is not improving - if (!imp && Reductions[NonPV][imp][d][mc] >= 2) + if (!imp && r > 1.0) Reductions[NonPV][imp][d][mc]++; } @@ -310,8 +319,8 @@ void Thread::search() { multiPV = std::min(multiPV, rootMoves.size()); int ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns - Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2) - : -make_score(ct, ct / 2)); + contempt = (us == WHITE ? make_score(ct, ct / 2) + : -make_score(ct, ct / 2)); // Iterative deepening loop until requested to stop or the target depth is reached while ( (rootDepth += ONE_PLY) < DEPTH_MAX @@ -344,20 +353,18 @@ void Thread::search() { // Reset aspiration window starting size if (rootDepth >= 5 * ONE_PLY) { + Value previousScore = rootMoves[PVIdx].previousScore; delta = Value(18); - alpha = std::max(rootMoves[PVIdx].previousScore - delta,-VALUE_INFINITE); - beta = std::min(rootMoves[PVIdx].previousScore + delta, VALUE_INFINITE); + alpha = std::max(previousScore - delta,-VALUE_INFINITE); + beta = std::min(previousScore + delta, VALUE_INFINITE); ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns - // Adjust contempt based on current bestValue (dynamic contempt) - int sign = (bestValue > 0) - (bestValue < 0); - ct += bestValue > 500 ? 70 : - bestValue < -500 ? -70 : - bestValue / 10 + sign * int(std::round(3.22 * log(1 + abs(bestValue)))); + // Adjust contempt based on root move's previousScore (dynamic contempt) + ct += int(std::round(48 * atan(float(previousScore) / 128))); - Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2) - : -make_score(ct, ct / 2)); + contempt = (us == WHITE ? make_score(ct, ct / 2) + : -make_score(ct, ct / 2)); } // Start with a small aspiration window and, in the case of a fail @@ -458,12 +465,12 @@ void Thread::search() { 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, 0.528) / 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 / 581) + || 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". @@ -494,7 +501,11 @@ 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); @@ -657,6 +668,7 @@ namespace { if (inCheck) { ss->staticEval = eval = VALUE_NONE; + improving = false; goto moves_loop; } else if (ttHit) @@ -681,7 +693,6 @@ namespace { } improving = ss->staticEval >= (ss-2)->staticEval - /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */ ||(ss-2)->staticEval == VALUE_NONE; if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move())) @@ -689,20 +700,13 @@ namespace { // Step 7. Razoring (skipped when in check) if ( !PvNode - && depth <= 2 * ONE_PLY) + && depth < 3 * ONE_PLY + && eval <= alpha - RazorMargin[depth / ONE_PLY]) { - if ( depth == ONE_PLY - && eval + RazorMargin1 <= alpha) - return qsearch(pos, ss, alpha, alpha+1); - - else if (eval + RazorMargin2 <= alpha) - { - Value ralpha = alpha - RazorMargin2; - Value v = qsearch(pos, ss, ralpha, ralpha+1); - - if (v <= ralpha) - return v; - } + 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) @@ -727,8 +731,9 @@ namespace { 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) @@ -745,8 +750,7 @@ 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; @@ -764,12 +768,12 @@ 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 - && probCutCount < depth / ONE_PLY - 3) + && probCutCount < 3) if (pos.legal(move)) { probCutCount++; @@ -781,15 +785,11 @@ namespace { 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); @@ -802,7 +802,7 @@ 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); @@ -819,9 +819,6 @@ 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 @@ -932,7 +929,7 @@ moves_loop: // When in check, search starts from here } else if ( depth < 7 * ONE_PLY && !extension - && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) + && !pos.see_ge(move, -Value(CapturePruneMargin[depth / ONE_PLY]))) continue; } @@ -1019,10 +1016,7 @@ 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 @@ -1032,10 +1026,7 @@ 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 @@ -1164,17 +1155,15 @@ 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; @@ -1183,7 +1172,7 @@ 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) @@ -1195,19 +1184,20 @@ 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(); @@ -1224,7 +1214,7 @@ 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; @@ -1279,7 +1269,7 @@ 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)) @@ -1302,13 +1292,13 @@ 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; @@ -1326,8 +1316,7 @@ 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); @@ -1360,7 +1349,7 @@ 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), @@ -1513,11 +1502,11 @@ 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(); - int elapsed = Time.elapsed(); + TimePoint elapsed = Time.elapsed(); TimePoint tick = Limits.startTime + elapsed; if (tick - lastInfoTime >= 1000) @@ -1543,7 +1532,7 @@ void MainThread::check_time() { string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { std::stringstream ss; - int elapsed = Time.elapsed() + 1; + TimePoint elapsed = Time.elapsed() + 1; const RootMoves& rootMoves = pos.this_thread()->rootMoves; size_t PVIdx = pos.this_thread()->PVIdx; size_t multiPV = std::min((size_t)Options["MultiPV"], rootMoves.size());