X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=92d2c75ed2c6fd5a3ff3b89d376e60c704c048f4;hp=ba80ccdfde93ba1ab4ec97ed68d74e69fe929613;hb=bfcfaf71018b3aed274ebd544a10c4508718e7de;hpb=c02613860a3836bb85da25ae2fed9f1351ba27a5 diff --git a/src/search.cpp b/src/search.cpp index ba80ccdf..92d2c75e 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -125,9 +125,6 @@ namespace { const bool UseIIDAtPVNodes = true; const bool UseIIDAtNonPVNodes = false; - // Use null move driven internal iterative deepening? - bool UseNullDrivenIID = false; - // Internal iterative deepening margin. At Non-PV moves, when // UseIIDAtNonPVNodes is true, we do an internal iterative deepening search // when the static evaluation is at most IIDMargin below beta. @@ -152,6 +149,16 @@ namespace { // evaluation of the position is more than NullMoveMargin below beta. const Value NullMoveMargin = Value(0x300); + //Null move search refutes move when Nullvalue >= Beta - Delta. Index is depth + //in full plies. Last index is 9+. + const Value NullMoveDeltaMidgame[] = + { Value(-8), Value( 6), Value(-15), Value( 9), Value(21), + Value(34), Value(54), Value( 59), Value(61), Value(61) }; + + const Value NullMoveDeltaEndgame[] = + { Value( 6), Value( 0), Value(-13), Value(-9), Value(-35), + Value(12), Value(24), Value( 9), Value( 5), Value( 5) }; + // Pruning criterions. See the code and comments in ok_to_prune() to // understand their precise meaning. const bool PruneEscapeMoves = false; @@ -259,8 +266,6 @@ namespace { Depth depth, int ply, int threadID); void sp_search(SplitPoint *sp, int threadID); void sp_search_pv(SplitPoint *sp, int threadID); - void init_search_stack(SearchStack& ss); - void init_search_stack(SearchStack ss[]); void init_node(const Position &pos, SearchStack ss[], int ply, int threadID); void update_pv(SearchStack ss[], int ply); void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply); @@ -324,6 +329,24 @@ History H; // Should be made local? SearchStack EmptySearchStack; +// SearchStack::init() initializes a search stack. Used at the beginning of a +// new search from the root. +void SearchStack::init(int ply) { + + pv[ply] = pv[ply + 1] = MOVE_NONE; + currentMove = threatMove = MOVE_NONE; + reduction = Depth(0); + currentMoveCaptureValue = Value(0); +} + +void SearchStack::initKillers() { + + mateKiller = MOVE_NONE; + for (int i = 0; i < KILLER_MAX; i++) + killers[i] = MOVE_NONE; +} + + //// //// Functions //// @@ -411,7 +434,6 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move, if (UseLogFile) LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app); - UseNullDrivenIID = get_option_value_bool("Null driven IID"); UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)"); UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)"); @@ -588,7 +610,8 @@ void init_threads() { } // Init also the empty search stack - init_search_stack(EmptySearchStack); + EmptySearchStack.init(0); + EmptySearchStack.initKillers(); } @@ -640,8 +663,11 @@ namespace { // Initialize TT.new_search(); H.clear(); - init_search_stack(ss); - + for (int i = 0; i < 3; i++) + { + ss[i].init(i); + ss[i].initKillers(); + } ValueByIteration[0] = Value(0); ValueByIteration[1] = rml.get_move_score(0); Iteration = 1; @@ -1171,7 +1197,6 @@ namespace { Value approximateEval = quick_evaluate(pos); bool mateThreat = false; - bool nullDrivenIID = false; bool isCheck = pos.is_check(); // Null move search @@ -1182,26 +1207,19 @@ namespace { && ok_to_do_nullmove(pos) && approximateEval >= beta - NullMoveMargin) { + //Calculate correct delta. Idea and tuning from Joona Kiiski. + ScaleFactor factor[2] = { SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL }; + Phase phase = pos.game_phase(); + int i = Min(depth / OnePly, 9); + Value delta = scale_by_game_phase(NullMoveDeltaMidgame[i], NullMoveDeltaEndgame[i], phase, factor); + ss[ply].currentMove = MOVE_NULL; StateInfo st; pos.do_null_move(st); int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction - Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); - - // Check for a null capture artifact, if the value without the null capture - // is above beta then mark the node as a suspicious failed low. We will verify - // later if we are really under threat. - if ( UseNullDrivenIID - && nullValue < beta - && depth > 6 * OnePly - &&!value_is_mate(nullValue) - && ttMove == MOVE_NONE - && ss[ply + 1].currentMove != MOVE_NONE - && pos.move_is_capture(ss[ply + 1].currentMove) - && pos.see(ss[ply + 1].currentMove) + nullValue >= beta) - nullDrivenIID = true; + Value nullValue = -search(pos, ss, -(beta-delta-1), depth-R*OnePly, ply+1, false, threadID); pos.undo_null_move(); @@ -1209,7 +1227,7 @@ namespace { { /* Do not return unproven mates */ } - else if (nullValue >= beta) + else if (nullValue >= beta - delta) { if (depth < 6 * OnePly) return beta; @@ -1226,10 +1244,8 @@ namespace { // low score (which will cause the reduced move to fail high in the // parent node, which will trigger a re-search with full depth). if (nullValue == value_mated_in(ply + 2)) - { mateThreat = true; - nullDrivenIID = false; - } + ss[ply].threatMove = ss[ply + 1].currentMove; if ( depth < ThreatDepth && ss[ply - 1].reduction @@ -1259,22 +1275,6 @@ namespace { search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); ttMove = ss[ply].pv[ply]; } - else if (nullDrivenIID) - { - // The null move failed low due to a suspicious capture. Perhaps we - // are facing a null capture artifact due to the side to move change - // and this position should fail high. So do a normal search with a - // reduced depth to get a good ttMove to use in the following full - // depth search. - Move tm = ss[ply].threatMove; - - assert(tm != MOVE_NONE); - assert(ttMove == MOVE_NONE); - - search(pos, ss, beta, depth/2, ply, false, threadID); - ttMove = ss[ply].pv[ply]; - ss[ply].threatMove = tm; - } // Initialize a MovePicker object for the current position, and prepare // to search all moves: @@ -1990,34 +1990,6 @@ namespace { } - // init_search_stack() initializes a search stack at the beginning of a - // new search from the root. - void init_search_stack(SearchStack& ss) { - - ss.pv[0] = MOVE_NONE; - ss.pv[1] = MOVE_NONE; - ss.currentMove = MOVE_NONE; - ss.threatMove = MOVE_NONE; - ss.reduction = Depth(0); - for (int j = 0; j < KILLER_MAX; j++) - ss.killers[j] = MOVE_NONE; - } - - void init_search_stack(SearchStack ss[]) { - - for (int i = 0; i < 3; i++) - { - ss[i].pv[i] = MOVE_NONE; - ss[i].pv[i+1] = MOVE_NONE; - ss[i].currentMove = MOVE_NONE; - ss[i].threatMove = MOVE_NONE; - ss[i].reduction = Depth(0); - for (int j = 0; j < KILLER_MAX; j++) - ss[i].killers[j] = MOVE_NONE; - } - } - - // init_node() is called at the beginning of all the search functions // (search(), search_pv(), qsearch(), and so on) and initializes the search // stack object corresponding to the current node. Once every @@ -2037,13 +2009,9 @@ namespace { NodesSincePoll = 0; } } - ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE; - ss[ply+2].mateKiller = MOVE_NONE; - ss[ply].threatMove = MOVE_NONE; - ss[ply].reduction = Depth(0); - ss[ply].currentMoveCaptureValue = Value(0); - for (int j = 0; j < KILLER_MAX; j++) - ss[ply+2].killers[j] = MOVE_NONE; + + ss[ply].init(ply); + ss[ply+2].initKillers(); if(Threads[threadID].printCurrentLine) print_current_line(ss, ply, threadID);