X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=fbe6b2c052fa3fee50e7f98bcf37639134e438a1;hp=216964ab43d5434678695f1f9c88d076cb084243;hb=b8e6f83cfb913fa079edd3690a8720f09eb7b388;hpb=56273fca1edc51ffa0efc73715609f428c000c97 diff --git a/src/search.cpp b/src/search.cpp index 216964ab..fbe6b2c0 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -45,7 +45,6 @@ namespace Search { Color RootColor; Time::point SearchTime; StateStackPtr SetupStates; - Value Contempt[2]; // [bestValue > VALUE_DRAW] } using std::string; @@ -58,16 +57,16 @@ namespace { const bool FakeSplit = false; // Different node types, used as template parameter - enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; + enum NodeType { Root, PV, NonPV }; // Dynamic razoring margin based on depth - inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); } + inline Value razor_margin(Depth d) { return Value(512 + 16 * d); } // Futility lookup tables (initialized at startup) and their access functions int FutilityMoveCounts[2][32]; // [improving][depth] inline Value futility_margin(Depth d) { - return Value(100 * int(d)); + return Value(100 * d); } // Reduction lookup tables (initialized at startup) and their access function @@ -86,7 +85,7 @@ namespace { GainsStats Gains; MovesStats Countermoves, Followupmoves; - template + template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode); template @@ -130,8 +129,8 @@ void Search::init() { { double pvRed = 0.00 + log(double(hd)) * log(double(mc)) / 3.00; double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; - Reductions[1][1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); - Reductions[0][1][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); + Reductions[1][1][hd][mc] = int8_t( pvRed >= 1.0 ? pvRed * int(ONE_PLY) : 0); + Reductions[0][1][hd][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed * int(ONE_PLY) : 0); Reductions[1][0][hd][mc] = Reductions[1][1][hd][mc]; Reductions[0][0][hd][mc] = Reductions[0][1][hd][mc]; @@ -186,9 +185,9 @@ void Search::think() { RootColor = RootPos.side_to_move(); TimeMgr.init(Limits, RootPos.game_ply(), RootColor); - DrawValue[0] = DrawValue[1] = VALUE_DRAW; - Contempt[0] = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns - Contempt[1] = (Options["Contempt Factor"] + 12) * PawnValueEg / 100; + int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns + DrawValue[ RootColor] = VALUE_DRAW - Value(cf); + DrawValue[~RootColor] = VALUE_DRAW + Value(cf); if (RootMoves.empty()) { @@ -338,10 +337,7 @@ namespace { // high/low anymore. while (true) { - bestValue = search(pos, ss, alpha, beta, depth * ONE_PLY, false); - - DrawValue[ RootColor] = VALUE_DRAW - Contempt[bestValue > VALUE_DRAW]; - DrawValue[~RootColor] = VALUE_DRAW + Contempt[bestValue > VALUE_DRAW]; + bestValue = search(pos, ss, alpha, beta, depth * ONE_PLY, false); // Bring the best move to the front. It is critical that sorting // is done with a stable algorithm because all the values but the @@ -447,12 +443,11 @@ namespace { // repeat all this work again. We also don't need to store anything to the hash // table here: This is taken care of after we return from the split point. - template + template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) { - const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot); - const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot); - const bool RootNode = (NT == Root || NT == SplitPointRoot); + const bool RootNode = NT == Root; + const bool PvNode = NT == PV || NT == Root; assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); @@ -625,7 +620,7 @@ namespace { pos.do_null_move(st); (ss+1)->skipNullMove = true; nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -beta+1, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode); + : - search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode); (ss+1)->skipNullMove = false; pos.undo_null_move(); @@ -641,7 +636,7 @@ namespace { // Do verification search at high depths ss->skipNullMove = true; Value v = depth-R < ONE_PLY ? qsearch(pos, ss, beta-1, beta, DEPTH_ZERO) - : search(pos, ss, beta-1, beta, depth-R, false); + : search(pos, ss, beta-1, beta, depth-R, false); ss->skipNullMove = false; if (v >= beta) @@ -673,7 +668,7 @@ namespace { { ss->currentMove = move; pos.do_move(move, st, ci, pos.gives_check(move, ci)); - value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); + value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); pos.undo_move(move); if (value >= rbeta) return value; @@ -683,12 +678,12 @@ namespace { // Step 10. Internal iterative deepening (skipped when in check) if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) && !ttMove - && (PvNode || ss->staticEval + Value(256) >= beta)) + && (PvNode || ss->staticEval + 256 >= beta)) { Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d, true); + search(pos, ss, alpha, beta, d, true); ss->skipNullMove = false; tte = TT.probe(posKey); @@ -788,7 +783,7 @@ moves_loop: // When in check and at SpNode search starts from here Value rBeta = ttValue - int(depth); ss->excludedMove = move; ss->skipNullMove = true; - value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); + value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; @@ -823,7 +818,7 @@ moves_loop: // When in check and at SpNode search starts from here if (predictedDepth < 7 * ONE_PLY) { futilityValue = ss->staticEval + futility_margin(predictedDepth) - + Value(128) + Gains[pos.moved_piece(move)][to_sq(move)]; + + 128 + Gains[pos.moved_piece(move)][to_sq(move)]; if (futilityValue <= alpha) { @@ -888,13 +883,13 @@ moves_loop: // When in check and at SpNode search starts from here if (SpNode) alpha = splitPoint->alpha; - value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); + value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); // Research at intermediate depth if reduction is very high if (value > alpha && ss->reduction >= 4 * ONE_PLY) { Depth d2 = std::max(newDepth - 2 * ONE_PLY, ONE_PLY); - value = -search(pos, ss+1, -(alpha+1), -alpha, d2, true); + value = -search(pos, ss+1, -(alpha+1), -alpha, d2, true); } doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO); @@ -912,7 +907,7 @@ moves_loop: // When in check and at SpNode search starts from here value = newDepth < ONE_PLY ? givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) : -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); } // For PV nodes only, do a full PV search on the first move or after a fail @@ -922,7 +917,7 @@ moves_loop: // When in check and at SpNode search starts from here value = newDepth < ONE_PLY ? givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -alpha, newDepth, false); + : - search(pos, ss+1, -beta, -alpha, newDepth, false); // Step 17. Undo move pos.undo_move(move); @@ -936,12 +931,11 @@ moves_loop: // When in check and at SpNode search starts from here alpha = splitPoint->alpha; } - // Finished searching the move. If Signals.stop is true, the search - // was aborted because the user interrupted the search or because we - // ran out of time. In this case, the return value of the search cannot - // be trusted, and we don't update the best move and/or PV. + // Finished searching the move. If a stop or a cutoff occurred, the return + // value of the search cannot be trusted, and we return immediately without + // updating best move, PV and TT. if (Signals.stop || thisThread->cutoff_occurred()) - return value; // To avoid returning VALUE_INFINITE + return VALUE_ZERO; if (RootNode) { @@ -994,10 +988,14 @@ moves_loop: // When in check and at SpNode search starts from here && Threads.available_slave(thisThread) && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD) { - assert(bestValue < beta); + assert(bestValue > -VALUE_INFINITE && bestValue < beta); thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, depth, moveCount, &mp, NT, cutNode); + + if (Signals.stop || thisThread->cutoff_occurred()) + return VALUE_ZERO; + if (bestValue >= beta) break; } @@ -1006,21 +1004,22 @@ moves_loop: // When in check and at SpNode search starts from here if (SpNode) return bestValue; + // Following condition would detect a stop or a cutoff set only after move + // loop has been completed. But in this case bestValue is valid because we + // have fully searched our subtree, and we can anyhow save the result in TT. + /* + if (Signals.stop || thisThread->cutoff_occurred()) + return VALUE_DRAW; + */ + // Step 20. Check for mate and stalemate // All legal moves have been searched and if there are no legal moves, it - // must be mate or stalemate. Note that we can have a false positive in - // case of Signals.stop or thread.cutoff_occurred() are set, but this is - // harmless because return value is discarded anyhow in the parent nodes. - // If we are in a singular extension search then return a fail low score. - // A split node has at least one move - the one tried before to be split. + // must be mate or stalemate. If we are in a singular extension search then + // return a fail low score. if (!moveCount) return excludedMove ? alpha : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()]; - // If we have pruned all the moves without searching return a fail-low score - if (bestValue == -VALUE_INFINITE) - bestValue = alpha; - TT.store(posKey, value_to_tt(bestValue, ss->ply), bestValue >= beta ? BOUND_LOWER : PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, @@ -1043,7 +1042,7 @@ moves_loop: // When in check and at SpNode search starts from here template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { - const bool PvNode = (NT == PV); + const bool PvNode = NT == PV; assert(NT == PV || NT == NonPV); assert(InCheck == !!pos.checkers()); @@ -1128,7 +1127,7 @@ moves_loop: // When in check and at SpNode search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = bestValue + Value(128); + futilityBase = bestValue + 128; } // Initialize a MovePicker object for the current position, and prepare @@ -1514,19 +1513,17 @@ void Thread::idle_loop() { activePosition = &pos; - switch (sp->nodeType) { - case Root: - search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); - break; - case PV: - search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); - break; - case NonPV: - search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); - break; - default: + if (sp->nodeType == NonPV) + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); + + else if (sp->nodeType == PV) + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); + + else if (sp->nodeType == Root) + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); + + else assert(false); - } assert(searching);