X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=c7d2efd40da46bb6189e834fea0bee051ae2f182;hp=1d5bc5f7c844edae9337c367510e01ae60401ae2;hb=5f426d8667feda65eaf1eca699f629d31e170d43;hpb=581b92e4a70b99fa5a22f7a1a38f2c8d2099769f diff --git a/src/search.cpp b/src/search.cpp index 1d5bc5f7..c7d2efd4 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -335,7 +335,7 @@ void Thread::search() { // for match (TC 60+0.6) results spanning a wide range of k values. PRNG rng(now()); double floatLevel = Options["UCI_LimitStrength"] ? - Utility::clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) : + std::clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) : double(Options["Skill Level"]); int intLevel = int(floatLevel) + ((floatLevel - int(floatLevel)) * 1024 > rng.rand() % 1024 ? 1 : 0); @@ -508,7 +508,7 @@ void Thread::search() { { double fallingEval = (318 + 6 * (mainThread->bestPreviousScore - bestValue) + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 825.0; - fallingEval = Utility::clamp(fallingEval, 0.5, 1.5); + fallingEval = std::clamp(fallingEval, 0.5, 1.5); // If the bestMove is stable over several iterations, reduce time accordingly timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.92 : 0.95; @@ -520,7 +520,7 @@ void Thread::search() { totBestMoveChanges += th->bestMoveChanges; th->bestMoveChanges = 0; } - double bestMoveInstability = 1 + totBestMoveChanges / Threads.size(); + double bestMoveInstability = 1 + 2 * totBestMoveChanges / Threads.size(); double totalTime = rootMoves.size() == 1 ? 0 : Time.optimum() * fallingEval * reduction * bestMoveInstability; @@ -597,7 +597,7 @@ namespace { Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; Value bestValue, value, ttValue, eval, maxValue, probCutBeta; - bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture; + bool formerPv, givesCheck, improving, didLMR, priorCapture; bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularQuietLMR; Piece movedPiece; @@ -644,6 +644,7 @@ namespace { assert(0 <= ss->ply && ss->ply < MAX_PLY); (ss+1)->ply = ss->ply + 1; + (ss+1)->ttPv = false; (ss+1)->excludedMove = bestMove = MOVE_NONE; (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; Square prevSq = to_sq((ss-1)->currentMove); @@ -653,9 +654,7 @@ namespace { // 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. - if (rootNode) - (ss+4)->statScore = 0; - else + if (!rootNode) (ss+2)->statScore = 0; // Step 4. Transposition table lookup. We don't want the score of a partial @@ -663,14 +662,15 @@ namespace { // position key in case of an excluded move. excludedMove = ss->excludedMove; posKey = excludedMove == MOVE_NONE ? pos.key() : pos.key() ^ make_key(excludedMove); - tte = TT.probe(posKey, ttHit); - ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; + tte = TT.probe(posKey, ss->ttHit); + ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0] - : ttHit ? tte->move() : MOVE_NONE; - ttPv = PvNode || (ttHit && tte->is_pv()); - formerPv = ttPv && !PvNode; + : ss->ttHit ? tte->move() : MOVE_NONE; + if (!excludedMove) + ss->ttPv = PvNode || (ss->ttHit && tte->is_pv()); + formerPv = ss->ttPv && !PvNode; - if ( ttPv + if ( ss->ttPv && depth > 12 && ss->ply - 1 < MAX_LPH && !priorCapture @@ -679,11 +679,11 @@ namespace { // thisThread->ttHitAverage can be used to approximate the running average of ttHit thisThread->ttHitAverage = (TtHitAverageWindow - 1) * thisThread->ttHitAverage / TtHitAverageWindow - + TtHitAverageResolution * ttHit; + + TtHitAverageResolution * ss->ttHit; // At non-PV nodes we check for an early TT cutoff if ( !PvNode - && ttHit + && ss->ttHit && tte->depth() >= depth && ttValue != VALUE_NONE // Possible in case of TT access race && (ttValue >= beta ? (tte->bound() & BOUND_LOWER) @@ -748,7 +748,7 @@ namespace { if ( b == BOUND_EXACT || (b == BOUND_LOWER ? value >= beta : value <= alpha)) { - tte->save(posKey, value_to_tt(value, ss->ply), ttPv, b, + tte->save(posKey, value_to_tt(value, ss->ply), ss->ttPv, b, std::min(MAX_PLY - 1, depth + 6), MOVE_NONE, VALUE_NONE); @@ -776,7 +776,7 @@ namespace { improving = false; goto moves_loop; } - else if (ttHit) + else if (ss->ttHit) { // Never assume anything about values stored in TT ss->staticEval = eval = tte->eval(); @@ -798,7 +798,7 @@ namespace { else ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo; - tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); + tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); } // Step 7. Razoring (~1 Elo) @@ -807,8 +807,9 @@ namespace { && eval <= alpha - RazorMargin) return qsearch(pos, ss, alpha, beta); - improving = (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval - || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval; + improving = (ss-2)->staticEval == VALUE_NONE + ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE + : ss->staticEval > (ss-2)->staticEval; // Step 8. Futility pruning: child node (~50 Elo) if ( !PvNode @@ -823,7 +824,7 @@ namespace { && (ss-1)->statScore < 22977 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ttPv + 182 + && ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ss->ttPv + 182 && !excludedMove && pos.non_pawn_material(us) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) @@ -879,14 +880,14 @@ namespace { // there and in further interactions with transposition table cutoff depth is set to depth - 3 // because probCut search has depth set to depth - 4 but we also do a move before it // so effective depth is equal to depth - 3 - && !( ttHit - && tte->depth() >= depth - 3 + && !( ss->ttHit + && tte->depth() >= depth - 3 && ttValue != VALUE_NONE && ttValue < probCutBeta)) { // if ttMove is a capture and value from transposition table is good enough produce probCut // cutoff without digging into actual probCut search - if ( ttHit + if ( ss->ttHit && tte->depth() >= depth - 3 && ttValue != VALUE_NONE && ttValue >= probCutBeta @@ -897,6 +898,8 @@ namespace { assert(probCutBeta < VALUE_INFINITE); MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory); int probCutCount = 0; + bool ttPv = ss->ttPv; + ss->ttPv = false; while ( (move = mp.next_move()) != MOVE_NONE && probCutCount < 2 + 2 * cutNode) @@ -928,7 +931,7 @@ namespace { if (value >= probCutBeta) { // if transposition table doesn't have equal or more deep info write probCut data into it - if ( !(ttHit + if ( !(ss->ttHit && tte->depth() >= depth - 3 && ttValue != VALUE_NONE)) tte->save(posKey, value_to_tt(value, ss->ply), ttPv, @@ -937,17 +940,14 @@ namespace { return value; } } + ss->ttPv = ttPv; } - // Step 11. Internal iterative deepening (~1 Elo) - if (depth >= 7 && !ttMove) - { - search(pos, ss, alpha, beta, depth - 7, cutNode); - - tte = TT.probe(posKey, ttHit); - ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; - ttMove = ttHit ? tte->move() : MOVE_NONE; - } + // Step 11. If the position is not in TT, decrease depth by 2 + if ( PvNode + && depth >= 6 + && !ttMove) + depth -= 2; moves_loop: // When in check, search starts from here @@ -1122,6 +1122,11 @@ moves_loop: // When in check, search starts from here && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move))) extension = 1; + // Last captures extension + else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg + && pos.non_pawn_material() <= 2 * RookValueMg) + extension = 1; + // Castling extension if ( type_of(move) == CASTLING && popcount(pos.pieces(us) & ~pos.pieces(PAWN) & (to_sq(move) & KingSide ? KingSide : QueenSide)) <= 2) @@ -1153,7 +1158,6 @@ moves_loop: // When in check, search starts from here // re-searched at full depth. if ( depth >= 3 && moveCount > 1 + 2 * rootNode + 2 * (PvNode && abs(bestValue) < 2) - && (!rootNode || thisThread->best_move_count(move) == 0) && ( !captureOrPromotion || moveCountPruning || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha @@ -1162,13 +1166,6 @@ moves_loop: // When in check, search starts from here { Depth r = reduction(improving, depth, moveCount); - // Decrease reduction at non-check cut nodes for second move at low depths - if ( cutNode - && depth <= 10 - && moveCount <= 2 - && !ss->inCheck) - r--; - // Decrease reduction if the ttHit running average is large if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024) r--; @@ -1178,7 +1175,7 @@ moves_loop: // When in check, search starts from here r++; // Decrease reduction if position is or has been on the PV (~10 Elo) - if (ttPv) + if (ss->ttPv) r -= 2; if (moveCountPruning && !formerPv) @@ -1190,7 +1187,7 @@ moves_loop: // When in check, search starts from here // Decrease reduction if ttMove has been singularly extended (~3 Elo) if (singularQuietLMR) - r -= 1 + formerPv; + r--; if (!captureOrPromotion) { @@ -1207,7 +1204,7 @@ moves_loop: // When in check, search starts from here // hence break make_move(). (~2 Elo) else if ( type_of(move) == NORMAL && !pos.see_ge(reverse_move(move))) - r -= 2 + ttPv - (type_of(movedPiece) == PAWN); + r -= 2 + ss->ttPv - (type_of(movedPiece) == PAWN); ss->statScore = thisThread->mainHistory[us][from_to(move)] + (*contHist[0])[movedPiece][to_sq(move)] @@ -1237,7 +1234,7 @@ moves_loop: // When in check, search starts from here r++; } - Depth d = Utility::clamp(newDepth - r, 1, newDepth); + Depth d = std::clamp(newDepth - r, 1, newDepth); value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); @@ -1385,8 +1382,17 @@ moves_loop: // When in check, search starts from here if (PvNode) bestValue = std::min(bestValue, maxValue); + // If no good move is found and the previous position was ttPv, then the previous + // opponent move is probably good and the new position is added to the search tree. + if (bestValue <= alpha) + ss->ttPv = ss->ttPv || ((ss-1)->ttPv && depth > 3); + // Otherwise, a counter move has been found and if the position is the last leaf + // in the search tree, remove the position from the search tree. + else if (depth > 3) + ss->ttPv = ss->ttPv && (ss+1)->ttPv; + if (!excludedMove && !(rootNode && thisThread->pvIdx)) - tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv, + tte->save(posKey, value_to_tt(bestValue, ss->ply), ss->ttPv, bestValue >= beta ? BOUND_LOWER : PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, depth, bestMove, ss->staticEval); @@ -1415,7 +1421,7 @@ moves_loop: // When in check, search starts from here Move ttMove, move, bestMove; Depth ttDepth; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool ttHit, pvHit, givesCheck, captureOrPromotion; + bool pvHit, givesCheck, captureOrPromotion; int moveCount; if (PvNode) @@ -1445,13 +1451,13 @@ moves_loop: // When in check, search starts from here : DEPTH_QS_NO_CHECKS; // Transposition table lookup posKey = pos.key(); - tte = TT.probe(posKey, ttHit); - ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; - ttMove = ttHit ? tte->move() : MOVE_NONE; - pvHit = ttHit && tte->is_pv(); + tte = TT.probe(posKey, ss->ttHit); + ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; + ttMove = ss->ttHit ? tte->move() : MOVE_NONE; + pvHit = ss->ttHit && tte->is_pv(); if ( !PvNode - && ttHit + && ss->ttHit && tte->depth() >= ttDepth && ttValue != VALUE_NONE // Only in case of TT access race && (ttValue >= beta ? (tte->bound() & BOUND_LOWER) @@ -1466,7 +1472,7 @@ moves_loop: // When in check, search starts from here } else { - if (ttHit) + if (ss->ttHit) { // Never assume anything about values stored in TT if ((ss->staticEval = bestValue = tte->eval()) == VALUE_NONE) @@ -1485,7 +1491,7 @@ moves_loop: // When in check, search starts from here // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) { - if (!ttHit) + if (!ss->ttHit) tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->staticEval); @@ -1529,6 +1535,10 @@ moves_loop: // When in check, search starts from here { assert(type_of(move) != ENPASSANT); // Due to !pos.advanced_pawn_push + // moveCount pruning + if (moveCount > 2) + continue; + futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))]; if (futilityValue <= alpha) @@ -1545,7 +1555,9 @@ moves_loop: // When in check, search starts from here } // Do not search moves with negative SEE values - if ( !ss->inCheck && !pos.see_ge(move)) + if ( !ss->inCheck + && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move)) + && !pos.see_ge(move)) continue; // Speculative prefetch as early as possible @@ -1564,6 +1576,12 @@ moves_loop: // When in check, search starts from here [pos.moved_piece(move)] [to_sq(move)]; + if ( !captureOrPromotion + && moveCount + && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold + && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold) + continue; + // Make and search the move pos.do_move(move, st, givesCheck); value = -qsearch(pos, ss+1, -beta, -alpha, depth - 1); @@ -1691,8 +1709,8 @@ moves_loop: // When in check, search starts from here else captureHistory[moved_piece][to_sq(bestMove)][captured] << bonus1; - // 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])) + // Extra penalty for a quiet early move that was not a TT move or main killer move in previous ply when it gets refuted + if ( ((ss-1)->moveCount == 1 + (ss-1)->ttHit || ((ss-1)->currentMove == (ss-1)->killers[0])) && !pos.captured_piece()) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -bonus1); @@ -1835,12 +1853,15 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { { bool updated = rootMoves[i].score != -VALUE_INFINITE; - if (depth == 1 && !updated) + if (depth == 1 && !updated && i > 0) continue; - Depth d = updated ? depth : depth - 1; + Depth d = updated ? depth : std::max(1, depth - 1); Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore; + if (v == -VALUE_INFINITE) + v = VALUE_ZERO; + bool tb = TB::RootInTB && abs(v) < VALUE_MATE_IN_MAX_PLY; v = tb ? rootMoves[i].tbScore : v; @@ -1938,7 +1959,7 @@ void Tablebases::rank_root_moves(Position& pos, Search::RootMoves& rootMoves) { if (RootInTB) { // Sort moves according to TB rank - std::sort(rootMoves.begin(), rootMoves.end(), + std::stable_sort(rootMoves.begin(), rootMoves.end(), [](const RootMove &a, const RootMove &b) { return a.tbRank > b.tbRank; } ); // Probe during search only if DTZ is not available and we are winning