X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=66843515e4ddc332ddae523814fd52099d399533;hp=639c5bc55bf9a1d6d676d29bf2678ed80241cccf;hb=7b4f9c37cb859ba6258ba90d11358879c0b2c57d;hpb=9fff27220917d706988185cbd847e3f355a7fe09 diff --git a/src/search.cpp b/src/search.cpp index 639c5bc5..66843515 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -2,7 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -85,10 +85,10 @@ namespace { return d > 17 ? 0 : 29 * d * d + 138 * d - 134; } - // Add a small random component to draw evaluations to keep search dynamic + // Add a small random component to draw evaluations to keep search dynamic // and to avoid 3fold-blindness. Value value_draw(Depth depth, Thread* thisThread) { - return depth < 4 ? VALUE_DRAW + return depth < 4 ? VALUE_DRAW : VALUE_DRAW + Value(2 * (thisThread->nodes.load(std::memory_order_relaxed) % 2) - 1); } @@ -187,6 +187,7 @@ void Search::clear() { Time.availableNodes = 0; TT.clear(); Threads.clear(); + Tablebases::init(Options["SyzygyPath"]); // Free up mapped files } @@ -387,7 +388,7 @@ void Thread::search() { if (rootDepth >= 5 * ONE_PLY) { Value previousScore = rootMoves[pvIdx].previousScore; - delta = Value(18); + delta = Value(20); alpha = std::max(previousScore - delta,-VALUE_INFINITE); beta = std::min(previousScore + delta, VALUE_INFINITE); @@ -401,9 +402,11 @@ void Thread::search() { // Start with a small aspiration window and, in the case of a fail // high/low, re-search with a bigger window until we don't fail // high/low anymore. + int failedHighCnt = 0; while (true) { - bestValue = ::search(rootPos, ss, alpha, beta, rootDepth, false); + Depth adjustedDepth = std::max(ONE_PLY, rootDepth - failedHighCnt * ONE_PLY); + bestValue = ::search(rootPos, ss, alpha, beta, adjustedDepth, false); // Bring the best move to the front. It is critical that sorting // is done with a stable algorithm because all the values but the @@ -436,12 +439,17 @@ void Thread::search() { if (mainThread) { + failedHighCnt = 0; failedLow = true; Threads.stopOnPonderhit = false; } } else if (bestValue >= beta) + { beta = std::min(bestValue + delta, VALUE_INFINITE); + if (mainThread) + ++failedHighCnt; + } else break; @@ -484,10 +492,8 @@ void Thread::search() { && !Threads.stop && !Threads.stopOnPonderhit) { - const int F[] = { failedLow, - bestValue - mainThread->previousScore }; - - int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1])); + double fallingEval = (306 + 119 * failedLow + 6 * (mainThread->previousScore - bestValue)) / 581.0; + fallingEval = std::max(0.5, std::min(1.5, fallingEval)); // If the bestMove is stable over several iterations, reduce time accordingly timeReduction = 1.0; @@ -501,7 +507,7 @@ void Thread::search() { // Stop the search if we have only one legal move, or if available time elapsed if ( rootMoves.size() == 1 - || Time.elapsed() > Time.optimum() * bestMoveInstability * improvingFactor / 581) + || Time.elapsed() > Time.optimum() * bestMoveInstability * fallingEval) { // If we are allowed to ponder do not stop the search now but // keep pondering until the GUI sends "ponderhit" or "stop". @@ -591,7 +597,7 @@ namespace { if ( Threads.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) - return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) + return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : value_draw(depth, pos.this_thread()); // Step 3. Mate distance pruning. Even if we mate at the next move our score @@ -675,6 +681,10 @@ namespace { TB::ProbeState err; TB::WDLScore wdl = Tablebases::probe_wdl(pos, &err); + // Force check of time on the next occasion + if (thisThread == Threads.main()) + static_cast(thisThread)->callsCnt = 0; + if (err != TB::ProbeState::FAIL) { thisThread->tbHits.fetch_add(1, std::memory_order_relaxed); @@ -936,6 +946,10 @@ moves_loop: // When in check, search starts from here && pos.see_ge(move)) extension = ONE_PLY; + // Extension if castling + else if (type_of(move) == CASTLING) + extension = ONE_PLY; + // Calculate new depth for this move newDepth = depth - ONE_PLY + extension; @@ -1171,9 +1185,12 @@ moves_loop: // When in check, search starts from here 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()) - update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted + if ( (ss-1)->moveCount == 1 + || ((ss-1)->currentMove == (ss-1)->killers[0] && (ss-1)->killers[0])) + if (!pos.captured_piece()) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + } // Bonus for prior countermove that caused the fail low else if ( (depth >= 3 * ONE_PLY || PvNode) @@ -1379,21 +1396,15 @@ moves_loop: // When in check, search starts from here if (value > alpha) { + bestMove = move; + if (PvNode) // Update pv even in fail-high case update_pv(ss->pv, move, (ss+1)->pv); if (PvNode && value < beta) // Update alpha here! - { alpha = value; - bestMove = move; - } - else // Fail high - { - tte->save(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, - ttDepth, move, ss->staticEval); - - return value; - } + else + break; // Fail high } } } @@ -1404,7 +1415,8 @@ moves_loop: // When in check, search starts from here return mated_in(ss->ply); // Plies to mate from the root tte->save(posKey, value_to_tt(bestValue, ss->ply), - PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, + bestValue >= beta ? BOUND_LOWER : + PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, ttDepth, bestMove, ss->staticEval); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);