X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=0358cd24297c8326e850832eac86c9c7b59e02be;hp=0b4125fcdd6ccf05279c848c1257eed89c042343;hb=3e739f883fb766f965ed434507c9c8fbcf18a855;hpb=8e45e70e55c42c4750ccb729dcd49cdaafe5af44 diff --git a/src/search.cpp b/src/search.cpp index 0b4125fc..0358cd24 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -65,7 +65,7 @@ namespace { // Razoring and futility margin based on depth const int razor_margin[4] = { 483, 570, 603, 554 }; - Value futility_margin(Depth d) { return Value(200 * d); } + Value futility_margin(Depth d) { return Value(150 * d); } // Futility and reductions lookup tables, initialized at startup int FutilityMoveCounts[2][16]; // [improving][depth] @@ -168,7 +168,8 @@ namespace { Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); void update_pv(Move* pv, Move move, Move* childPv); - void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt); + void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, Value bonus); + void update_opponent_stats(const Position& pos, Stack* ss, Value bonus); void check_time(); } // namespace @@ -213,6 +214,7 @@ void Search::clear() { { th->history.clear(); th->counterMoves.clear(); + th->fromTo.clear(); } Threads.main()->previousScore = VALUE_INFINITE; @@ -549,6 +551,7 @@ namespace { assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(DEPTH_ZERO < depth && depth < DEPTH_MAX); + assert(!(PvNode && cutNode)); Move pv[MAX_PLY+1], quietsSearched[64]; StateInfo st; @@ -634,9 +637,23 @@ namespace { ss->currentMove = ttMove; // Can be MOVE_NONE // If ttMove is quiet, update killers, history, counter move on TT hit - if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove)) - update_stats(pos, ss, ttMove, depth, nullptr, 0); + if (ttValue >= beta && ttMove) + { + int d = depth / ONE_PLY; + + if (!pos.capture_or_promotion(ttMove)) + { + Value bonus = Value(d * d + 2 * d - 2); + update_stats(pos, ss, ttMove, nullptr, 0, bonus); + } + // Extra penalty for a quiet TT move in previous ply when it gets refuted + if ((ss-1)->moveCount == 1 && !pos.captured_piece_type()) + { + Value penalty = Value(d * d + 4 * d + 1); + update_opponent_stats(pos, ss, -penalty); + } + } return ttValue; } @@ -728,8 +745,8 @@ namespace { // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode - && depth >= 2 * ONE_PLY && eval >= beta + && (ss->staticEval >= beta - 35 * (depth / ONE_PLY - 6) || depth >= 13 * ONE_PLY) && pos.non_pawn_material(pos.side_to_move())) { ss->currentMove = MOVE_NULL; @@ -799,13 +816,12 @@ namespace { } // Step 10. Internal iterative deepening (skipped when in check) - if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) + if ( depth >= 6 * ONE_PLY && !ttMove && (PvNode || ss->staticEval + 256 >= beta)) { - Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4); ss->skipEarlyPruning = true; - search(pos, ss, alpha, beta, d, true); + search(pos, ss, alpha, beta, 3 * depth / 4 - 2 * ONE_PLY, cutNode); ss->skipEarlyPruning = false; tte = TT.probe(posKey, ttHit); @@ -814,7 +830,6 @@ namespace { moves_loop: // When in check search starts from here - Square prevSq = to_sq((ss-1)->currentMove); const CounterMoveStats* cmh = (ss-1)->counterMoves; const CounterMoveStats* fmh = (ss-2)->counterMoves; const CounterMoveStats* fmh2 = (ss-4)->counterMoves; @@ -823,7 +838,7 @@ moves_loop: // When in check search starts from here CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc improving = ss->staticEval >= (ss-2)->staticEval - || ss->staticEval == VALUE_NONE + /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */ ||(ss-2)->staticEval == VALUE_NONE; singularExtensionNode = !rootNode @@ -873,9 +888,9 @@ moves_loop: // When in check search starts from here && moveCount >= FutilityMoveCounts[improving][depth]; // Step 12. Extend checks - if ( givesCheck - && ( moveCount == 1 - || (!moveCountPruning && pos.see_sign(move) >= VALUE_ZERO))) + if ( givesCheck + && !moveCountPruning + && pos.see_sign(move) >= VALUE_ZERO) extension = ONE_PLY; // Singular extension search. If all moves but one fail low on a search of @@ -914,24 +929,31 @@ moves_loop: // When in check search starts from here if (moveCountPruning) continue; + predictedDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO); + // Countermoves based pruning - if ( depth <= 4 * ONE_PLY + if ( predictedDepth < 3 * ONE_PLY && move != ss->killers[0] && (!cmh || (*cmh )[moved_piece][to_sq(move)] < VALUE_ZERO) && (!fmh || (*fmh )[moved_piece][to_sq(move)] < VALUE_ZERO) && (!fmh2 || (*fmh2)[moved_piece][to_sq(move)] < VALUE_ZERO || (cmh && fmh))) continue; - predictedDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO); - // Futility pruning: parent node if ( predictedDepth < 7 * ONE_PLY - && ss->staticEval + futility_margin(predictedDepth) + 256 <= alpha) + && ss->staticEval + 256 + 200 * predictedDepth / ONE_PLY <= alpha) continue; - // Prune moves with negative SEE at low depths - if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO) - continue; + // Prune moves with negative SEE at low depths and below a decreasing + // threshold at higher depths. + if (predictedDepth < 8 * ONE_PLY) + { + Value see_v = predictedDepth < 4 * ONE_PLY ? VALUE_ZERO + : -PawnValueMg * 2 * int(predictedDepth - 3 * ONE_PLY); + + if (pos.see_sign(move) < see_v) + continue; + } } // Speculative prefetch as early as possible @@ -954,36 +976,43 @@ moves_loop: // When in check search starts from here // re-searched at full depth. if ( depth >= 3 * ONE_PLY && moveCount > 1 - && !captureOrPromotion) + && (!captureOrPromotion || moveCountPruning)) { Depth r = reduction(improving, depth, moveCount); - Value val = thisThread->history[moved_piece][to_sq(move)] - + (cmh ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO) - + (fmh ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO) - + (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO); - - // Increase reduction for cut nodes - if (!PvNode && cutNode) - r += 2 * ONE_PLY; - - // Decrease reduction for moves that escape a capture. Filter out - // castling moves, because they are coded as "king captures rook" and - // hence break make_move(). Also use see() instead of see_sign(), - // because the destination square is empty. - else if ( type_of(move) == NORMAL - && type_of(pos.piece_on(to_sq(move))) != PAWN - && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO) - r -= 2 * ONE_PLY; - - // Decrease/increase reduction for moves with a good/bad history - int rHist = (val - 10000) / 20000; - r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY); + + if (captureOrPromotion) + r -= r ? ONE_PLY : DEPTH_ZERO; + else + { + Value val = thisThread->history[moved_piece][to_sq(move)] + + (cmh ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO) + + (fmh ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO) + + (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO) + + thisThread->fromTo.get(~pos.side_to_move(), move); + + // Increase reduction for cut nodes + if (cutNode) + r += 2 * ONE_PLY; + + // Decrease reduction for moves that escape a capture. Filter out + // castling moves, because they are coded as "king captures rook" and + // hence break make_move(). Also use see() instead of see_sign(), + // because the destination square is empty. + else if ( type_of(move) == NORMAL + && type_of(pos.piece_on(to_sq(move))) != PAWN + && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO) + r -= 2 * ONE_PLY; + + // Decrease/increase reduction for moves with a good/bad history + int rHist = (val - 8000) / 20000; + r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY); + } Depth d = std::max(newDepth - r, ONE_PLY); value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); - doFullDepthSearch = (value > alpha && r != DEPTH_ZERO); + doFullDepthSearch = (value > alpha && d != newDepth); } else doFullDepthSearch = !PvNode || moveCount > 1; @@ -1097,27 +1126,32 @@ moves_loop: // When in check search starts from here if (!moveCount) bestValue = excludedMove ? alpha : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()]; + else if (bestMove) + { + int d = depth / ONE_PLY; - // Quiet best move: update killers, history and countermoves - else if (bestMove && !pos.capture_or_promotion(bestMove)) - update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount); + // Quiet best move: update killers, history and countermoves + if (!pos.capture_or_promotion(bestMove)) + { + Value bonus = Value(d * d + 2 * d - 2); + update_stats(pos, ss, bestMove, quietsSearched, quietCount, bonus); + } + // Extra penalty for a quiet TT move in previous ply when it gets refuted + if ((ss-1)->moveCount == 1 && !pos.captured_piece_type()) + { + Value penalty = Value(d * d + 4 * d + 1); + update_opponent_stats(pos, ss, -penalty); + } + } // Bonus for prior countermove that caused the fail low else if ( depth >= 3 * ONE_PLY - && !bestMove - && !inCheck && !pos.captured_piece_type() && is_ok((ss-1)->currentMove)) { - Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + 2 * depth / ONE_PLY - 2); - if ((ss-2)->counterMoves) - (ss-2)->counterMoves->update(pos.piece_on(prevSq), prevSq, bonus); - - if ((ss-3)->counterMoves) - (ss-3)->counterMoves->update(pos.piece_on(prevSq), prevSq, bonus); - - if ((ss-5)->counterMoves) - (ss-5)->counterMoves->update(pos.piece_on(prevSq), prevSq, bonus); + int d = depth / ONE_PLY; + Value bonus = Value(d * d + 2 * d - 2); + update_opponent_stats(pos, ss, bonus); } tte->save(posKey, value_to_tt(bestValue, ss->ply), @@ -1377,11 +1411,33 @@ moves_loop: // When in check search starts from here } + // update_opponent_stats() updates countermoves for prior opponent move, i.e. + // (ss-1)->currentMove. Called for both capture and non-capture moves. + + void update_opponent_stats(const Position& pos, Stack* ss, Value bonus) { + + Square prevSq = to_sq((ss-1)->currentMove); + + CounterMoveStats* cmh = (ss-2)->counterMoves; + CounterMoveStats* fmh1 = (ss-3)->counterMoves; + CounterMoveStats* fmh2 = (ss-5)->counterMoves; + + if (cmh) + cmh->update(pos.piece_on(prevSq), prevSq, bonus); + + if (fmh1) + fmh1->update(pos.piece_on(prevSq), prevSq, bonus); + + if (fmh2) + fmh2->update(pos.piece_on(prevSq), prevSq, bonus); + } + + // update_stats() updates killers, history, countermove and countermove plus // follow-up move history when a new quiet best move is found. void update_stats(const Position& pos, Stack* ss, Move move, - Depth depth, Move* quiets, int quietsCnt) { + Move* quiets, int quietsCnt, Value bonus) { if (ss->killers[0] != move) { @@ -1389,24 +1445,24 @@ moves_loop: // When in check search starts from here ss->killers[0] = move; } - Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + 2 * depth / ONE_PLY - 2); - - Square prevSq = to_sq((ss-1)->currentMove); CounterMoveStats* cmh = (ss-1)->counterMoves; - CounterMoveStats* fmh = (ss-2)->counterMoves; + CounterMoveStats* fmh1 = (ss-2)->counterMoves; CounterMoveStats* fmh2 = (ss-4)->counterMoves; - Thread* thisThread = pos.this_thread(); + Color c = pos.side_to_move(); + Thread* thisThread = pos.this_thread(); thisThread->history.update(pos.moved_piece(move), to_sq(move), bonus); + thisThread->fromTo.update(c, move, bonus); if (cmh) { + Square prevSq = to_sq((ss-1)->currentMove); thisThread->counterMoves.update(pos.piece_on(prevSq), prevSq, move); cmh->update(pos.moved_piece(move), to_sq(move), bonus); } - if (fmh) - fmh->update(pos.moved_piece(move), to_sq(move), bonus); + if (fmh1) + fmh1->update(pos.moved_piece(move), to_sq(move), bonus); if (fmh2) fmh2->update(pos.moved_piece(move), to_sq(move), bonus); @@ -1415,29 +1471,17 @@ moves_loop: // When in check search starts from here for (int i = 0; i < quietsCnt; ++i) { thisThread->history.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); + thisThread->fromTo.update(c, quiets[i], -bonus); if (cmh) cmh->update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); - if (fmh) - fmh->update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); + if (fmh1) + fmh1->update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); if (fmh2) fmh2->update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); } - - // Extra penalty for a quiet TT move in previous ply when it gets refuted - if ((ss-1)->moveCount == 1 && !pos.captured_piece_type()) - { - if ((ss-2)->counterMoves) - (ss-2)->counterMoves->update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY - 1); - - if ((ss-3)->counterMoves) - (ss-3)->counterMoves->update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY - 1); - - if ((ss-5)->counterMoves) - (ss-5)->counterMoves->update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY - 1); - } } @@ -1573,16 +1617,16 @@ bool RootMove::extract_ponder_from_tt(Position& pos) pos.do_move(pv[0], st, pos.gives_check(pv[0], CheckInfo(pos))); TTEntry* tte = TT.probe(pos.key(), ttHit); - pos.undo_move(pv[0]); if (ttHit) { Move m = tte->move(); // Local copy to be SMP safe if (MoveList(pos).contains(m)) - return pv.push_back(m), true; + pv.push_back(m); } - return false; + pos.undo_move(pv[0]); + return pv.size() > 1; } void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves) {