X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=3f89c0400c24d2f54e9aee6fc52eac7a5f5cd56c;hp=31b6967c17ff008b97e6c939731a523232d92c17;hb=e7cfa5d020efb5a0ad2521afc7b886f3b2d3e6b3;hpb=d7022031130ef84b801e087c1804d0cf05bc369b diff --git a/src/search.cpp b/src/search.cpp index 31b6967c..3f89c040 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -71,16 +71,6 @@ namespace { 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] @@ -296,6 +286,7 @@ void Thread::search() { MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr); double timeReduction = 1.0; Color us = rootPos.side_to_move(); + bool failedLow; std::memset(ss-4, 0, 7 * sizeof(Stack)); for (int i = 4; i > 0; i--) @@ -305,7 +296,7 @@ void Thread::search() { beta = VALUE_INFINITE; if (mainThread) - mainThread->bestMoveChanges = 0, mainThread->failedLow = false; + mainThread->bestMoveChanges = 0, failedLow = false; size_t multiPV = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -346,24 +337,24 @@ void Thread::search() { // Age out PV variability metric if (mainThread) - mainThread->bestMoveChanges *= 0.517, mainThread->failedLow = false; + mainThread->bestMoveChanges *= 0.517, 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. for (RootMove& rm : rootMoves) rm.previousScore = rm.score; - size_t PVFirst = 0; - PVLast = 0; + size_t pvFirst = 0; + pvLast = 0; // MultiPV loop. We perform a full root search for each PV line - for (PVIdx = 0; PVIdx < multiPV && !Threads.stop; ++PVIdx) + for (pvIdx = 0; pvIdx < multiPV && !Threads.stop; ++pvIdx) { - if (PVIdx == PVLast) + if (pvIdx == pvLast) { - PVFirst = PVLast; - for (PVLast++; PVLast < rootMoves.size(); PVLast++) - if (rootMoves[PVLast].TBRank != rootMoves[PVFirst].TBRank) + pvFirst = pvLast; + for (pvLast++; pvLast < rootMoves.size(); pvLast++) + if (rootMoves[pvLast].tbRank != rootMoves[pvFirst].tbRank) break; } @@ -373,7 +364,7 @@ void Thread::search() { // Reset aspiration window starting size if (rootDepth >= 5 * ONE_PLY) { - Value previousScore = rootMoves[PVIdx].previousScore; + Value previousScore = rootMoves[pvIdx].previousScore; delta = Value(18); alpha = std::max(previousScore - delta,-VALUE_INFINITE); beta = std::min(previousScore + delta, VALUE_INFINITE); @@ -398,7 +389,7 @@ void Thread::search() { // and we want to keep the same order for all the moves except the // new PV that goes to the front. Note that in case of MultiPV // search the already searched PV lines are preserved. - std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.begin() + PVLast); + std::stable_sort(rootMoves.begin() + pvIdx, rootMoves.begin() + pvLast); // If search has been stopped, we break immediately. Sorting is // safe because RootMoves is still valid, although it refers to @@ -423,7 +414,7 @@ void Thread::search() { if (mainThread) { - mainThread->failedLow = true; + failedLow = true; Threads.stopOnPonderhit = false; } } @@ -438,10 +429,10 @@ void Thread::search() { } // Sort the PV lines searched so far and update the GUI - std::stable_sort(rootMoves.begin() + PVFirst, rootMoves.begin() + PVIdx + 1); + std::stable_sort(rootMoves.begin() + pvFirst, rootMoves.begin() + pvIdx + 1); if ( mainThread - && (Threads.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000)) + && (Threads.stop || pvIdx + 1 == multiPV || Time.elapsed() > 3000)) sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl; } @@ -471,7 +462,7 @@ void Thread::search() { && !Threads.stop && !Threads.stopOnPonderhit) { - const int F[] = { mainThread->failedLow, + const int F[] = { failedLow, bestValue - mainThread->previousScore }; int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1])); @@ -519,13 +510,25 @@ namespace { template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) { - // 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; + // Check if we have an upcoming move which draws by repetition, or + // if the opponent had an alternative move earlier to this position. + if ( pos.rule50_count() >= 3 + && alpha < VALUE_DRAW + && !rootNode + && pos.has_game_cycle(ss->ply)) + { + alpha = VALUE_DRAW; + if (alpha >= beta) + return alpha; + } + + // Dive into quiescence search when the depth reaches zero + if (depth < ONE_PLY) + return qsearch(pos, ss, alpha, beta); + assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(DEPTH_ZERO < depth && depth < DEPTH_MAX); @@ -578,17 +581,6 @@ namespace { beta = std::min(mate_in(ss->ply+1), beta); if (alpha >= beta) return alpha; - - // Check if there exists a move which draws by repetition, or an alternative - // earlier move to this position. - if ( pos.rule50_count() >= 3 - && alpha < VALUE_DRAW - && pos.has_game_cycle(ss->ply)) - { - alpha = VALUE_DRAW; - if (alpha >= beta) - return alpha; - } } assert(0 <= ss->ply && ss->ply < MAX_PLY); @@ -613,7 +605,7 @@ namespace { posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash tte = TT.probe(posKey, ttHit); ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; - ttMove = rootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0] + ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE; // At non-PV nodes we check for an early TT cutoff @@ -678,7 +670,7 @@ namespace { { tte->save(posKey, value_to_tt(value, ss->ply), b, std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), - MOVE_NONE, VALUE_NONE, TT.generation()); + MOVE_NONE, VALUE_NONE); return value; } @@ -719,7 +711,7 @@ namespace { : -(ss-1)->staticEval + 2 * Eval::Tempo; tte->save(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, - ss->staticEval, TT.generation()); + ss->staticEval); } // Step 7. Razoring (~2 Elo) @@ -751,7 +743,7 @@ namespace { && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225 && !excludedMove && pos.non_pawn_material(us) - && (ss->ply > thisThread->nmp_min_ply || us != thisThread->nmp_color)) + && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) { assert(eval - beta >= 0); @@ -773,17 +765,19 @@ namespace { if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; - if (abs(beta) < VALUE_KNOWN_WIN && (depth < 12 * ONE_PLY || thisThread->nmp_min_ply)) + if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 12 * ONE_PLY)) return nullValue; - // Do verification search at high depths. Disable null move pruning - // for side to move for the first part of the remaining search tree. - thisThread->nmp_min_ply = ss->ply + 3 * (depth-R) / 4 - 1; - thisThread->nmp_color = us; + assert(!thisThread->nmpMinPly); // Recursive verification is not allowed + + // Do verification search at high depths, with null move pruning disabled + // for us, until ply exceeds nmpMinPly. + thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4; + thisThread->nmpColor = us; Value v = search(pos, ss, beta-1, beta, depth-R, false); - thisThread->nmp_min_ply = 0; + thisThread->nmpMinPly = 0; if (v >= beta) return nullValue; @@ -832,8 +826,7 @@ namespace { if ( depth >= 8 * ONE_PLY && !ttMove) { - Depth d = 3 * depth / 4 - 2 * ONE_PLY; - search(pos, ss, alpha, beta, d, cutNode); + search(pos, ss, alpha, beta, depth - 7 * ONE_PLY, cutNode); tte = TT.probe(posKey, ttHit); ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; @@ -869,8 +862,8 @@ moves_loop: // When in check, search starts from here // Move List. As a consequence any illegal move is also skipped. In MultiPV // mode we also skip PV moves which have been already searched and those // of lower "TB rank" if we are in a TB root position. - if (rootNode && !std::count(thisThread->rootMoves.begin() + thisThread->PVIdx, - thisThread->rootMoves.begin() + thisThread->PVLast, move)) + if (rootNode && !std::count(thisThread->rootMoves.begin() + thisThread->pvIdx, + thisThread->rootMoves.begin() + thisThread->pvLast, move)) continue; ss->moveCount = ++moveCount; @@ -878,7 +871,7 @@ moves_loop: // When in check, search starts from here if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000) sync_cout << "info depth " << depth / ONE_PLY << " currmove " << UCI::move(move, pos.is_chess960()) - << " currmovenumber " << moveCount + thisThread->PVIdx << sync_endl; + << " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl; if (PvNode) (ss+1)->pv = nullptr; @@ -954,13 +947,11 @@ moves_loop: // When in check, search starts from here continue; // Prune moves with negative SEE (~10 Elo) - if ( lmrDepth < 8 - && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth))) + if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth))) continue; } - else if ( depth < 7 * ONE_PLY // (~20 Elo) - && !extension - && !pos.see_ge(move, -Value(CapturePruneMargin[depth / ONE_PLY]))) + else if ( !extension // (~20 Elo) + && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) continue; } @@ -993,7 +984,13 @@ moves_loop: // When in check, search starts from here Depth r = reduction(improving, depth, moveCount); if (captureOrPromotion) // (~5 Elo) + { + // Increase reduction by comparing opponent's stat score + if ((ss-1)->statScore >= 0) + r += ONE_PLY; + r -= r ? ONE_PLY : DEPTH_ZERO; + } else { // Decrease reduction if opponent's move count is high (~5 Elo) @@ -1156,9 +1153,10 @@ moves_loop: // When in check, search starts from here { // Quiet best move: update move sorting heuristics if (!pos.capture_or_promotion(bestMove)) - update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth)); + update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount, + stat_bonus(depth + (bestValue > beta + PawnValueMg ? ONE_PLY : DEPTH_ZERO))); else - update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth)); + update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth + ONE_PLY)); // Extra penalty for a quiet TT move in previous ply when it gets refuted if ((ss-1)->moveCount == 1 && !pos.captured_piece()) @@ -1177,7 +1175,7 @@ moves_loop: // When in check, search starts from here tte->save(posKey, value_to_tt(bestValue, ss->ply), bestValue >= beta ? BOUND_LOWER : PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, - depth, bestMove, ss->staticEval, TT.generation()); + depth, bestMove, ss->staticEval); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1274,7 +1272,7 @@ moves_loop: // When in check, search starts from here { if (!ttHit) tte->save(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, - DEPTH_NONE, MOVE_NONE, ss->staticEval, TT.generation()); + DEPTH_NONE, MOVE_NONE, ss->staticEval); return bestValue; } @@ -1373,7 +1371,7 @@ moves_loop: // When in check, search starts from here else // Fail high { tte->save(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, - ttDepth, move, ss->staticEval, TT.generation()); + ttDepth, move, ss->staticEval); return value; } @@ -1388,7 +1386,7 @@ moves_loop: // When in check, search starts from here tte->save(posKey, value_to_tt(bestValue, ss->ply), PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, - ttDepth, bestMove, ss->staticEval, TT.generation()); + ttDepth, bestMove, ss->staticEval); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1568,14 +1566,14 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { std::stringstream ss; TimePoint elapsed = Time.elapsed() + 1; const RootMoves& rootMoves = pos.this_thread()->rootMoves; - size_t PVIdx = pos.this_thread()->PVIdx; + size_t pvIdx = pos.this_thread()->pvIdx; size_t multiPV = std::min((size_t)Options["MultiPV"], rootMoves.size()); uint64_t nodesSearched = Threads.nodes_searched(); uint64_t tbHits = Threads.tb_hits() + (TB::RootInTB ? rootMoves.size() : 0); for (size_t i = 0; i < multiPV; ++i) { - bool updated = (i <= PVIdx && rootMoves[i].score != -VALUE_INFINITE); + bool updated = (i <= pvIdx && rootMoves[i].score != -VALUE_INFINITE); if (depth == ONE_PLY && !updated) continue; @@ -1584,7 +1582,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore; bool tb = TB::RootInTB && abs(v) < VALUE_MATE - MAX_PLY; - v = tb ? rootMoves[i].TBScore : v; + v = tb ? rootMoves[i].tbScore : v; if (ss.rdbuf()->in_avail()) // Not at first line ss << "\n"; @@ -1595,7 +1593,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { << " multipv " << i + 1 << " score " << UCI::value(v); - if (!tb && i == PVIdx) + if (!tb && i == pvIdx) ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : ""); ss << " nodes " << nodesSearched @@ -1678,16 +1676,16 @@ void Tablebases::rank_root_moves(Position& pos, Search::RootMoves& rootMoves) { { // Sort moves according to TB rank std::sort(rootMoves.begin(), rootMoves.end(), - [](const RootMove &a, const RootMove &b) { return a.TBRank > b.TBRank; } ); + [](const RootMove &a, const RootMove &b) { return a.tbRank > b.tbRank; } ); // Probe during search only if DTZ is not available and we are winning - if (dtz_available || rootMoves[0].TBScore <= VALUE_DRAW) + if (dtz_available || rootMoves[0].tbScore <= VALUE_DRAW) Cardinality = 0; } else { // Assign the same rank to all moves for (auto& m : rootMoves) - m.TBRank = 0; + m.tbRank = 0; } }