X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=0a53225abba9a81c8018edd10765b11c8dca00b9;hp=4f5a3480ef00c68270d38647a14d3f68df511e85;hb=6ae30e7cb10cf5b673aa6998d495b1527a43478d;hpb=2b6bc70f7bf266602a3ca59abb606699bdf544c8 diff --git a/src/search.cpp b/src/search.cpp index 4f5a3480..0a53225a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -119,7 +119,6 @@ namespace { inline Move get_move_pv(int moveNum, int i) const; inline int64_t get_move_cumulative_nodes(int moveNum) const; inline int move_count() const; - Move scan_for_easy_move() const; inline void sort(); void sort_multipv(int n); @@ -527,23 +526,36 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, << " moves to go: " << movesToGo << std::endl; - // We're ready to start thinking. Call the iterative deepening loop function - // - // FIXME we really need to cleanup all this LSN ugliness - if (!loseOnTime) + // LSN filtering. Used only for developing purpose. Disabled by default. + if ( UseLSNFiltering + && loseOnTime) { - Value v = id_loop(pos, searchMoves); - loseOnTime = ( UseLSNFiltering - && myTime < LSNTime - && myIncrement == 0 - && v < -LSNValue); + // Step 2. If after last move we decided to lose on time, do it now! + while (SearchStartTime + myTime + 1000 > get_system_time()) + ; // wait here } - else + + // We're ready to start thinking. Call the iterative deepening loop function + Value v = id_loop(pos, searchMoves); + + // LSN filtering. Used only for developing purpose. Disabled by default. + if (UseLSNFiltering) { - loseOnTime = false; // reset for next match - while (SearchStartTime + myTime + 1000 > get_system_time()) - ; // wait here - id_loop(pos, searchMoves); // to fail gracefully + // Step 1. If this is sudden death game and our position is hopeless, + // decide to lose on time. + if ( !loseOnTime // If we already lost on time, go to step 3. + && myTime < LSNTime + && myIncrement == 0 + && movesToGo == 0 + && v < -LSNValue) + { + loseOnTime = true; + } + else if (loseOnTime) + { + // Step 3. Now after stepping over the time limit, reset flag for next match. + loseOnTime = false; + } } if (UseLogFile) @@ -685,7 +697,11 @@ namespace { IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0)); Iteration = 1; - Move EasyMove = rml.scan_for_easy_move(); + // Is one move significantly better than others after initial scoring ? + Move EasyMove = MOVE_NONE; + if ( rml.move_count() == 1 + || rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin) + EasyMove = rml.get_move(0); // Iterative deepening loop while (Iteration < PLY_MAX) @@ -802,7 +818,6 @@ namespace { if (stopSearch) { - //FIXME: Implement fail-low emergency measures if (!PonderSearch) break; else @@ -1106,7 +1121,14 @@ namespace { return alpha; // Transposition table lookup. At PV nodes, we don't use the TT for - // pruning, but only for move ordering. + // pruning, but only for move ordering. This is to avoid problems in + // the following areas: + // + // * Repetition draw detection + // * Fifty move rule detection + // * Searching for a mate + // * Printing of full PV line + // tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); @@ -1143,7 +1165,7 @@ namespace { // To verify this we do a reduced search on all the other moves but the ttMove, // if result is lower then TT value minus a margin then we assume ttMove is the // only one playable. It is a kind of relaxed single reply extension. - if ( depth >= 4 * OnePly + if ( depth >= 8 * OnePly && move == ttMove && ext < OnePly && is_lower_bound(tte->type()) @@ -1153,8 +1175,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Depth d = Max(Min(depth / 2, depth - 4 * OnePly), OnePly); - Value excValue = search(pos, ss, ttValue - SingleReplyMargin, d, ply, false, threadID, ttMove); + Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, ttMove); // If search result is well below the foreseen score of the ttMove then we // assume ttMove is the only one realistically playable and we extend it. @@ -1446,7 +1467,7 @@ namespace { // To verify this we do a reduced search on all the other moves but the ttMove, // if result is lower then TT value minus a margin then we assume ttMove is the // only one playable. It is a kind of relaxed single reply extension. - if ( depth >= 4 * OnePly + if ( depth >= 8 * OnePly && !excludedMove // do not allow recursive single-reply search && move == ttMove && ext < OnePly @@ -1457,13 +1478,12 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Depth d = Max(Min(depth / 2, depth - 4 * OnePly), OnePly); - Value excValue = search(pos, ss, ttValue - SingleReplyMargin, d, ply, false, threadID, ttMove); + Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, ttMove); // If search result is well below the foreseen score of the ttMove then we // assume ttMove is the only one realistically playable and we extend it. if (excValue < ttValue - SingleReplyMargin) - ext = (depth >= 8 * OnePly) ? OnePly : ext + OnePly / 2; + ext = OnePly; } } @@ -2119,7 +2139,7 @@ namespace { moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0); pos.undo_move(moves[count].move); moves[count].pv[0] = moves[count].move; - moves[count].pv[1] = MOVE_NONE; // FIXME + moves[count].pv[1] = MOVE_NONE; count++; } sort(); @@ -2170,28 +2190,6 @@ namespace { } - // RootMoveList::scan_for_easy_move() is called at the end of the first - // iteration, and is used to detect an "easy move", i.e. a move which appears - // to be much bester than all the rest. If an easy move is found, the move - // is returned, otherwise the function returns MOVE_NONE. It is very - // important that this function is called at the right moment: The code - // assumes that the first iteration has been completed and the moves have - // been sorted. This is done in RootMoveList c'tor. - - Move RootMoveList::scan_for_easy_move() const { - - assert(count); - - if (count == 1) - return get_move(0); - - // moves are sorted so just consider the best and the second one - if (get_move_score(0) > get_move_score(1) + EasyMoveMargin) - return get_move(0); - - return MOVE_NONE; - } - // RootMoveList::sort() sorts the root move list at the beginning of a new // iteration.