X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=3f89c0400c24d2f54e9aee6fc52eac7a5f5cd56c;hp=93651cc047b466724bb959f1102a463f8c2257f3;hb=e7cfa5d020efb5a0ad2521afc7b886f3b2d3e6b3;hpb=b939788f9de55051e0dd43e5943a0cde0f2be14e diff --git a/src/search.cpp b/src/search.cpp index 93651cc0..3f89c040 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -71,16 +71,6 @@ namespace { return Value((175 - 50 * improving) * d / ONE_PLY); } - // Margin for pruning capturing moves: almost linear in depth - constexpr int CapturePruneMargin[] = { 0, - 1 * PawnValueEg * 1055 / 1000, - 2 * PawnValueEg * 1042 / 1000, - 3 * PawnValueEg * 963 / 1000, - 4 * PawnValueEg * 1038 / 1000, - 5 * PawnValueEg * 950 / 1000, - 6 * PawnValueEg * 930 / 1000 - }; - // Futility and reductions lookup tables, initialized at startup int FutilityMoveCounts[2][16]; // [improving][depth] int Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] @@ -296,6 +286,7 @@ void Thread::search() { MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr); double timeReduction = 1.0; Color us = rootPos.side_to_move(); + bool failedLow; std::memset(ss-4, 0, 7 * sizeof(Stack)); for (int i = 4; i > 0; i--) @@ -305,7 +296,7 @@ void Thread::search() { beta = VALUE_INFINITE; if (mainThread) - mainThread->bestMoveChanges = 0, mainThread->failedLow = false; + mainThread->bestMoveChanges = 0, failedLow = false; size_t multiPV = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -346,7 +337,7 @@ void Thread::search() { // Age out PV variability metric if (mainThread) - mainThread->bestMoveChanges *= 0.517, mainThread->failedLow = false; + mainThread->bestMoveChanges *= 0.517, failedLow = false; // Save the last iteration's scores before first PV line is searched and // all the move scores except the (new) PV are set to -VALUE_INFINITE. @@ -423,7 +414,7 @@ void Thread::search() { if (mainThread) { - mainThread->failedLow = true; + failedLow = true; Threads.stopOnPonderhit = false; } } @@ -471,7 +462,7 @@ void Thread::search() { && !Threads.stop && !Threads.stopOnPonderhit) { - const int F[] = { mainThread->failedLow, + const int F[] = { failedLow, bestValue - mainThread->previousScore }; int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1])); @@ -519,13 +510,25 @@ namespace { template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) { - // Use quiescence search when needed - if (depth < ONE_PLY) - return qsearch(pos, ss, alpha, beta); - constexpr bool PvNode = NT == PV; const bool rootNode = PvNode && ss->ply == 0; + // Check if we have an upcoming move which draws by repetition, or + // if the opponent had an alternative move earlier to this position. + if ( pos.rule50_count() >= 3 + && alpha < VALUE_DRAW + && !rootNode + && pos.has_game_cycle(ss->ply)) + { + alpha = VALUE_DRAW; + if (alpha >= beta) + return alpha; + } + + // Dive into quiescence search when the depth reaches zero + if (depth < ONE_PLY) + return qsearch(pos, ss, alpha, beta); + assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(DEPTH_ZERO < depth && depth < DEPTH_MAX); @@ -578,17 +581,6 @@ namespace { beta = std::min(mate_in(ss->ply+1), beta); if (alpha >= beta) return alpha; - - // Check if there exists a move which draws by repetition, or an alternative - // earlier move to this position. - if ( pos.rule50_count() >= 3 - && alpha < VALUE_DRAW - && pos.has_game_cycle(ss->ply)) - { - alpha = VALUE_DRAW; - if (alpha >= beta) - return alpha; - } } assert(0 <= ss->ply && ss->ply < MAX_PLY); @@ -678,7 +670,7 @@ namespace { { tte->save(posKey, value_to_tt(value, ss->ply), b, std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), - MOVE_NONE, VALUE_NONE, TT.generation()); + MOVE_NONE, VALUE_NONE); return value; } @@ -719,7 +711,7 @@ namespace { : -(ss-1)->staticEval + 2 * Eval::Tempo; tte->save(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, - ss->staticEval, TT.generation()); + ss->staticEval); } // Step 7. Razoring (~2 Elo) @@ -955,13 +947,11 @@ moves_loop: // When in check, search starts from here continue; // Prune moves with negative SEE (~10 Elo) - if ( lmrDepth < 8 - && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth))) + if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth))) continue; } - else if ( depth < 7 * ONE_PLY // (~20 Elo) - && !extension - && !pos.see_ge(move, -Value(CapturePruneMargin[depth / ONE_PLY]))) + else if ( !extension // (~20 Elo) + && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) continue; } @@ -1163,10 +1153,10 @@ moves_loop: // When in check, search starts from here { // Quiet best move: update move sorting heuristics if (!pos.capture_or_promotion(bestMove)) - update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth)); + update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount, + stat_bonus(depth + (bestValue > beta + PawnValueMg ? ONE_PLY : DEPTH_ZERO))); else - update_capture_stats(pos, bestMove, capturesSearched, captureCount, - stat_bonus(depth + (bestValue > beta + KnightValueMg ? ONE_PLY : DEPTH_ZERO))); + update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth + ONE_PLY)); // Extra penalty for a quiet TT move in previous ply when it gets refuted if ((ss-1)->moveCount == 1 && !pos.captured_piece()) @@ -1185,7 +1175,7 @@ moves_loop: // When in check, search starts from here tte->save(posKey, value_to_tt(bestValue, ss->ply), bestValue >= beta ? BOUND_LOWER : PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, - depth, bestMove, ss->staticEval, TT.generation()); + depth, bestMove, ss->staticEval); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1282,7 +1272,7 @@ moves_loop: // When in check, search starts from here { if (!ttHit) tte->save(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, - DEPTH_NONE, MOVE_NONE, ss->staticEval, TT.generation()); + DEPTH_NONE, MOVE_NONE, ss->staticEval); return bestValue; } @@ -1381,7 +1371,7 @@ moves_loop: // When in check, search starts from here else // Fail high { tte->save(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, - ttDepth, move, ss->staticEval, TT.generation()); + ttDepth, move, ss->staticEval); return value; } @@ -1396,7 +1386,7 @@ moves_loop: // When in check, search starts from here tte->save(posKey, value_to_tt(bestValue, ss->ply), PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, - ttDepth, bestMove, ss->staticEval, TT.generation()); + ttDepth, bestMove, ss->staticEval); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);