X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=82d8bb9dfa96d97cf25022c760202360d0a685b0;hp=676427f704234642ad84d440afc448ace1fcc66e;hb=cc9d503ddea998890112efd08fae3705f2727e37;hpb=220ef1d27d9cd006a30b07ab726999c8181d10f0 diff --git a/src/search.cpp b/src/search.cpp index 676427f7..82d8bb9d 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; @@ -596,7 +596,7 @@ namespace { Key posKey; Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; - Value bestValue, value, ttValue, eval, maxValue, probcutBeta; + Value bestValue, value, ttValue, eval, maxValue, probCutBeta; bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture; bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularQuietLMR; @@ -794,11 +794,7 @@ namespace { else { if ((ss-1)->currentMove != MOVE_NULL) - { - int bonus = -(ss-1)->statScore / 512; - - ss->staticEval = eval = evaluate(pos) + bonus; - } + ss->staticEval = eval = evaluate(pos); else ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo; @@ -811,8 +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 @@ -871,7 +868,7 @@ namespace { } } - probcutBeta = beta + 176 - 49 * improving; + probCutBeta = beta + 176 - 49 * improving; // Step 10. ProbCut (~10 Elo) // If we have a good enough capture and a reduced search returns a value @@ -879,21 +876,27 @@ namespace { if ( !PvNode && depth > 4 && abs(beta) < VALUE_TB_WIN_IN_MAX_PLY + // if value from transposition table is lower than probCutBeta, don't attempt probCut + // 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 && ttValue != VALUE_NONE - && ttValue < probcutBeta)) + && 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 && tte->depth() >= depth - 3 && ttValue != VALUE_NONE - && ttValue >= probcutBeta + && ttValue >= probCutBeta && ttMove && pos.capture_or_promotion(ttMove)) - return probcutBeta; + return probCutBeta; - assert(probcutBeta < VALUE_INFINITE); - MovePicker mp(pos, ttMove, probcutBeta - ss->staticEval, &captureHistory); + assert(probCutBeta < VALUE_INFINITE); + MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory); int probCutCount = 0; while ( (move = mp.next_move()) != MOVE_NONE @@ -915,16 +918,17 @@ namespace { pos.do_move(move, st); // Perform a preliminary qsearch to verify that the move holds - value = -qsearch(pos, ss+1, -probcutBeta, -probcutBeta+1); + value = -qsearch(pos, ss+1, -probCutBeta, -probCutBeta+1); // If the qsearch held, perform the regular search - if (value >= probcutBeta) - value = -search(pos, ss+1, -probcutBeta, -probcutBeta+1, depth - 4, !cutNode); + if (value >= probCutBeta) + value = -search(pos, ss+1, -probCutBeta, -probCutBeta+1, depth - 4, !cutNode); pos.undo_move(move); - if (value >= probcutBeta) + if (value >= probCutBeta) { + // if transposition table doesn't have equal or more deep info write probCut data into it if ( !(ttHit && tte->depth() >= depth - 3 && ttValue != VALUE_NONE)) @@ -936,15 +940,11 @@ namespace { } } - // 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 @@ -1119,12 +1119,6 @@ moves_loop: // When in check, search starts from here && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move))) extension = 1; - // Passed pawn extension - else if ( move == ss->killers[0] - && pos.advanced_pawn_push(move) - && pos.pawn_passed(us, to_sq(move))) - extension = 1; - // Last captures extension else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg && pos.non_pawn_material() <= 2 * RookValueMg) @@ -1132,7 +1126,7 @@ moves_loop: // When in check, search starts from here // Castling extension if ( type_of(move) == CASTLING - && popcount(pos.pieces(us) & ~pos.pieces(PAWN) & (to_sq(move) & KingSide ? KingSide : QueenSide)) <= 3) + && popcount(pos.pieces(us) & ~pos.pieces(PAWN) & (to_sq(move) & KingSide ? KingSide : QueenSide)) <= 2) extension = 1; // Late irreversible move extension @@ -1245,7 +1239,7 @@ 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);