X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=44347f79f8b85ec1aee88b579c65c6f9d9b48908;hp=30f280728e274055d49771ceb2a413d5b91aa9dd;hb=5c4002aa827653a125130a0d01d0bb96dd2b8bae;hpb=1982fe25f817c29aef9dd156869a53e520ce3629 diff --git a/src/search.cpp b/src/search.cpp index 30f28072..44347f79 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -67,10 +67,10 @@ namespace { } // Reductions lookup table, initialized at startup - int Reductions[64]; // [depth or moveNumber] + int Reductions[MAX_MOVES]; // [depth or moveNumber] template Depth reduction(bool i, Depth d, int mn) { - int r = Reductions[std::min(d / ONE_PLY, 63)] * Reductions[std::min(mn, 63)] / 1024; + int r = Reductions[d / ONE_PLY] * Reductions[mn] / 1024; return ((r + 512) / 1024 + (!i && r > 1024) - PvNode) * ONE_PLY; } @@ -86,8 +86,8 @@ namespace { // Add a small random component to draw evaluations to avoid 3fold-blindness Value value_draw(Depth depth, Thread* thisThread) { - return depth < 4 ? VALUE_DRAW - : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1); + return depth < 4 * ONE_PLY ? VALUE_DRAW + : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1); } // Skill structure is used to implement strength limit @@ -147,7 +147,7 @@ namespace { void Search::init() { - for (int i = 1; i < 64; ++i) + for (int i = 1; i < MAX_MOVES; ++i) Reductions[i] = int(1024 * std::log(i) / std::sqrt(1.95)); } @@ -468,8 +468,10 @@ void Thread::search() { // Use part of the gained time from a previous stable move for the current move for (Thread* th : Threads) + { totBestMoveChanges += th->bestMoveChanges; - + th->bestMoveChanges = 0; + } double bestMoveInstability = 1 + totBestMoveChanges / Threads.size(); // Stop the search if we have only one legal move, or if available time elapsed @@ -582,8 +584,7 @@ namespace { assert(0 <= ss->ply && ss->ply < MAX_PLY); (ss+1)->ply = ss->ply + 1; - ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; - ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0]; + (ss+1)->excludedMove = bestMove = MOVE_NONE; (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; Square prevSq = to_sq((ss-1)->currentMove); @@ -605,15 +606,6 @@ namespace { : ttHit ? tte->move() : MOVE_NONE; ttPv = (ttHit && tte->is_pv()) || (PvNode && depth > 4 * ONE_PLY); - // if position has been searched at higher depths and we are shuffling, return value_draw - if (pos.rule50_count() > 36 - && ss->ply > 36 - && depth < 3 * ONE_PLY - && ttHit - && tte->depth() > depth - && pos.count() > 0) - return VALUE_DRAW; - // At non-PV nodes we check for an early TT cutoff if ( !PvNode && ttHit @@ -630,9 +622,8 @@ namespace { if (!pos.capture_or_promotion(ttMove)) update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth)); - // 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]) - && !pos.captured_piece()) + // Extra penalty for early quiet moves of the previous ply + if ((ss-1)->moveCount <= 2 && !pos.captured_piece()) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); } // Penalty for a quiet ttMove that fails low @@ -783,7 +774,7 @@ namespace { // 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->nmpMinPly = ss->ply + 3 * (depth-R) / (4 * ONE_PLY); thisThread->nmpColor = us; Value v = search(pos, ss, beta-1, beta, depth-R, false); @@ -910,8 +901,9 @@ moves_loop: // When in check, search starts from here && pos.legal(move)) { Value singularBeta = ttValue - 2 * depth / ONE_PLY; + Depth halfDepth = depth / (2 * ONE_PLY) * ONE_PLY; // ONE_PLY invariant ss->excludedMove = move; - value = search(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode); + value = search(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode); ss->excludedMove = MOVE_NONE; if (value < singularBeta) @@ -931,12 +923,21 @@ moves_loop: // When in check, search starts from here && (pos.blockers_for_king(~us) & from_sq(move) || pos.see_ge(move))) extension = ONE_PLY; + // Castling extension + else if (type_of(move) == CASTLING) + extension = ONE_PLY; + // Shuffle extension - else if(pos.rule50_count() > 14 && ss->ply > 14 && depth < 3 * ONE_PLY && PvNode) + else if ( PvNode + && pos.rule50_count() > 18 + && depth < 3 * ONE_PLY + && ss->ply < 3 * thisThread->rootDepth / ONE_PLY) // To avoid too deep searches extension = ONE_PLY; - // Castling extension - else if (type_of(move) == CASTLING) + // Passed pawn extension + else if ( move == ss->killers[0] + && pos.advanced_pawn_push(move) + && pos.pawn_passed(us, to_sq(move))) extension = ONE_PLY; // Calculate new depth for this move @@ -959,7 +960,8 @@ moves_loop: // When in check, search starts from here continue; // Reduced depth of the next LMR search - int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY; + int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO); + lmrDepth /= ONE_PLY; // Countermoves based pruning (~20 Elo) if ( lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1) @@ -1230,8 +1232,7 @@ moves_loop: // When in check, search starts from here Thread* thisThread = pos.this_thread(); (ss+1)->ply = ss->ply + 1; - ss->currentMove = bestMove = MOVE_NONE; - ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0]; + bestMove = MOVE_NONE; inCheck = pos.checkers(); moveCount = 0;