X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=73fc8a55fef18d57212ff4bf0deaf7a87ffa846f;hp=ffeb511095da93cd4e0d125402c018fdf434ced4;hb=c8459b18ba2d6ddc76d6db90d6eab346ed682e69;hpb=00e34a758f2ca170986550a1f8f25dfe691ca511 diff --git a/src/search.cpp b/src/search.cpp index ffeb5110..73fc8a55 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -80,7 +80,7 @@ namespace { // History and stats update bonus, based on depth int stat_bonus(Depth d) { - return d > 14 ? 73 : 6 * d * d + 229 * d - 215; + return std::min((6 * d + 229) * d - 215 , 2000); } // Add a small random component to draw evaluations to avoid 3-fold blindness @@ -173,7 +173,7 @@ namespace { void Search::init() { for (int i = 1; i < MAX_MOVES; ++i) - Reductions[i] = int(21.9 * std::log(i)); + Reductions[i] = int((21.9 + std::log(Threads.size()) / 2) * std::log(i)); } @@ -591,13 +591,13 @@ namespace { bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularQuietLMR, noLMRExtension; Piece movedPiece; - int moveCount, captureCount, quietCount; + int moveCount, captureCount, quietCount, bestMoveCount; // Step 1. Initialize node ss->inCheck = pos.checkers(); priorCapture = pos.captured_piece(); Color us = pos.side_to_move(); - moveCount = captureCount = quietCount = ss->moveCount = 0; + moveCount = bestMoveCount = captureCount = quietCount = ss->moveCount = 0; bestValue = -VALUE_INFINITE; maxValue = VALUE_INFINITE; @@ -790,7 +790,6 @@ namespace { else { // In case of null move search use previous static eval with a different sign - // and addition of two tempos if ((ss-1)->currentMove != MOVE_NULL) ss->staticEval = eval = evaluate(pos); else @@ -1125,7 +1124,8 @@ moves_loop: // When in check, search starts here return singularBeta; // If the eval of ttMove is greater than beta we try also if there is another - // move that pushes it over beta, if so also produce a cutoff. + // move that pushes it over beta, if so the position also has probably multiple + // moves giving fail highs. We will then reduce the ttMove (negative extension). else if (ttValue >= beta) { ss->excludedMove = move; @@ -1133,7 +1133,7 @@ moves_loop: // When in check, search starts here ss->excludedMove = MOVE_NONE; if (value >= beta) - return beta; + extension = -2; } } @@ -1146,7 +1146,14 @@ moves_loop: // When in check, search starts here // Check extensions else if ( givesCheck && depth > 6 - && abs(ss->staticEval) > Value(100)) + && abs(ss->staticEval) > 100) + extension = 1; + + // Quiet ttMove extensions + else if ( PvNode + && move == ttMove + && move == ss->killers[0] + && (*contHist[0])[movedPiece][to_sq(move)] >= 10000) extension = 1; // Add extension to new depth @@ -1179,7 +1186,9 @@ moves_loop: // When in check, search starts here { Depth r = reduction(improving, depth, moveCount, rangeReduction > 2); - if (PvNode) + // Decrease reduction if on the PV (~2 Elo) + if ( PvNode + && bestMoveCount <= 3) r--; // Decrease reduction if the ttHit running average is large (~0 Elo) @@ -1222,11 +1231,10 @@ moves_loop: // When in check, search starts here // Decrease/increase reduction for moves with a good/bad history (~30 Elo) r -= ss->statScore / 14721; - // In general we want to cap the LMR depth search at newDepth. But if - // reductions are really negative and movecount is low, we allow this move - // to be searched deeper than the first move in specific cases (note that - // this may lead to hidden double extensions if newDepth got it own extension - // before). + // In general we want to cap the LMR depth search at newDepth. But if reductions + // are really negative and movecount is low, we allow this move to be searched + // deeper than the first move (this may lead to hidden double extensions if + // newDepth got its own extension before). int deeper = r >= -1 ? 0 : noLMRExtension ? 0 : moveCount <= 5 ? 1 @@ -1307,9 +1315,11 @@ moves_loop: // When in check, search starts here for (Move* m = (ss+1)->pv; *m != MOVE_NONE; ++m) rm.pv.push_back(*m); - // We record how often the best move has been changed in each - // iteration. This information is used for time management and LMR - if (moveCount > 1) + // We record how often the best move has been changed in each iteration. + // This information is used for time management and LMR. In MultiPV mode, + // we must take care to only do this for the first PV line. + if ( moveCount > 1 + && !thisThread->pvIdx) ++thisThread->bestMoveChanges; } else @@ -1331,7 +1341,10 @@ moves_loop: // When in check, search starts here update_pv(ss->pv, move, (ss+1)->pv); if (PvNode && value < beta) // Update alpha! Always alpha < beta + { alpha = value; + bestMoveCount++; + } else { assert(value >= beta); // Fail high @@ -1490,7 +1503,6 @@ moves_loop: // When in check, search starts here } else // In case of null move search use previous static eval with a different sign - // and addition of two tempos ss->staticEval = bestValue = (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval; @@ -1700,8 +1712,8 @@ moves_loop: // When in check, search starts here PieceType captured = type_of(pos.piece_on(to_sq(bestMove))); bonus1 = stat_bonus(depth + 1); - bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus - : std::min(bonus1, stat_bonus(depth)); // smaller bonus + bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus + : stat_bonus(depth); // smaller bonus if (!pos.capture_or_promotion(bestMove)) {