X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=a0097d135c2a9b5e8741df74f37a7fc0bc503e5d;hp=7dc92e80bceefb74d7a45ee7c639737aaf3044b4;hb=37e38639279bf58558b92932739da57e7c2e3bdc;hpb=30e8f0c9ada37eaf6a4730215c3d05a4c301ade8 diff --git a/src/material.cpp b/src/material.cpp index 7dc92e80..7e212461 100644 --- a/src/material.cpp +++ b/src/material.cpp @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -17,383 +18,202 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include -#include -#include -#include +#include // For std::memset #include "material.h" +#include "thread.h" - -//// -//// Local definitions -//// +using namespace std; namespace { - const Value BishopPairMidgameBonus = Value(100); - const Value BishopPairEndgameBonus = Value(100); - - Key KNNKMaterialKey, KKNNMaterialKey; - -} + // Polynomial material imbalance parameters + + constexpr int QuadraticOurs[][PIECE_TYPE_NB] = { + // OUR PIECES + // pair pawn knight bishop rook queen + {1438 }, // Bishop pair + { 40, 38 }, // Pawn + { 32, 255, -62 }, // Knight OUR PIECES + { 0, 104, 4, 0 }, // Bishop + { -26, -2, 47, 105, -208 }, // Rook + {-189, 24, 117, 133, -134, -6 } // Queen + }; -//// -//// Classes -//// + constexpr int QuadraticTheirs[][PIECE_TYPE_NB] = { + // THEIR PIECES + // pair pawn knight bishop rook queen + { 0 }, // Bishop pair + { 36, 0 }, // Pawn + { 9, 63, 0 }, // Knight OUR PIECES + { 59, 65, 42, 0 }, // Bishop + { 46, 39, 24, -24, 0 }, // Rook + { 97, 100, -42, 137, 268, 0 } // Queen + }; + // Endgame evaluation and scaling functions are accessed directly and not through + // the function maps because they correspond to more than one material hash key. + Endgame EvaluateKXK[] = { Endgame(WHITE), Endgame(BLACK) }; -/// See header for a class description. It is declared here to avoid -/// to include in the header file. + Endgame ScaleKBPsK[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame ScaleKQKRPs[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame ScaleKPsK[] = { Endgame(WHITE), Endgame(BLACK) }; + Endgame ScaleKPKP[] = { Endgame(WHITE), Endgame(BLACK) }; -class EndgameFunctions { + // Helper used to detect a given material distribution + bool is_KXK(const Position& pos, Color us) { + return !more_than_one(pos.pieces(~us)) + && pos.non_pawn_material(us) >= RookValueMg; + } -public: - EndgameFunctions(); - EndgameEvaluationFunctionBase* getEEF(Key key) const; - EndgameScalingFunctionBase* getESF(Key key, Color* c) const; + bool is_KBPsK(const Position& pos, Color us) { + return pos.non_pawn_material(us) == BishopValueMg + && pos.count(us) >= 1; + } -private: - void add(const std::string& keyCode, EndgameEvaluationFunctionBase* f); - void add(const std::string& keyCode, Color c, EndgameScalingFunctionBase* f); - Key buildKey(const std::string& keyCode); + bool is_KQKRPs(const Position& pos, Color us) { + return !pos.count(us) + && pos.non_pawn_material(us) == QueenValueMg + && pos.count(~us) == 1 + && pos.count(~us) >= 1; + } - struct ScalingInfo - { - Color col; - EndgameScalingFunctionBase* fun; - }; + /// imbalance() calculates the imbalance by comparing the piece count of each + /// piece type for both colors. + template + int imbalance(const int pieceCount[][PIECE_TYPE_NB]) { - std::map EEFmap; - std::map ESFmap; -}; + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + int bonus = 0; -//// -//// Functions -//// + // Second-degree polynomial material imbalance, by Tord Romstad + for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1) + { + if (!pieceCount[Us][pt1]) + continue; + int v = 0; -/// Constructor for the MaterialInfoTable class + for (int pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2) + v += QuadraticOurs[pt1][pt2] * pieceCount[Us][pt2] + + QuadraticTheirs[pt1][pt2] * pieceCount[Them][pt2]; -MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) { + bonus += pieceCount[Us][pt1] * v; + } - size = numOfEntries; - entries = new MaterialInfo[size]; - funcs = new EndgameFunctions(); - if (!entries || !funcs) - { - std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo)) - << " bytes for material hash table." << std::endl; - exit(EXIT_FAILURE); + return bonus; } - clear(); -} - - -/// Destructor for the MaterialInfoTable class -MaterialInfoTable::~MaterialInfoTable() { +} // namespace - delete [] entries; - delete funcs; -} +namespace Material { +/// Material::probe() looks up the current position's material configuration in +/// the material hash table. It returns a pointer to the Entry if the position +/// is found. Otherwise a new Entry is computed and stored there, so we don't +/// have to recompute all when the same material configuration occurs again. -/// MaterialInfoTable::clear() clears a material hash table by setting -/// all entries to 0. +Entry* probe(const Position& pos) { -void MaterialInfoTable::clear() { + Key key = pos.material_key(); + Entry* e = pos.this_thread()->materialTable[key]; - memset(entries, 0, size * sizeof(MaterialInfo)); -} + if (e->key == key) + return e; + std::memset(e, 0, sizeof(Entry)); + e->key = key; + e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL; -/// MaterialInfoTable::get_material_info() takes a position object as input, -/// computes or looks up a MaterialInfo object, and returns a pointer to it. -/// If the material configuration is not already present in the table, it -/// is stored there, so we don't have to recompute everything when the -/// same material configuration occurs again. + Value npm_w = pos.non_pawn_material(WHITE); + Value npm_b = pos.non_pawn_material(BLACK); + Value npm = Utility::clamp(npm_w + npm_b, EndgameLimit, MidgameLimit); -MaterialInfo* MaterialInfoTable::get_material_info(const Position& pos) { + // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME] + e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit)); - Key key = pos.get_material_key(); - int index = key & (size - 1); - MaterialInfo* mi = entries + index; + // Let's look if we have a specialized evaluation function for this particular + // material configuration. Firstly we look for a fixed configuration one, then + // for a generic one if the previous search failed. + if ((e->evaluationFunction = Endgames::probe(key)) != nullptr) + return e; - // If mi->key matches the position's material hash key, it means that we - // have analysed this material configuration before, and we can simply - // return the information we found the last time instead of recomputing it. - if (mi->key == key) - return mi; + for (Color c : { WHITE, BLACK }) + if (is_KXK(pos, c)) + { + e->evaluationFunction = &EvaluateKXK[c]; + return e; + } - // Clear the MaterialInfo object, and set its key - mi->clear(); - mi->key = key; + // OK, we didn't find any special evaluation function for the current material + // configuration. Is there a suitable specialized scaling function? + const auto* sf = Endgames::probe(key); - // A special case before looking for a specialized evaluation function - // KNN vs K is a draw. - if (key == KNNKMaterialKey || key == KKNNMaterialKey) + if (sf) { - mi->factor[WHITE] = mi->factor[BLACK] = 0; - return mi; + e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned + return e; } - // Let's look if we have a specialized evaluation function for this - // particular material configuration. First we look for a fixed - // configuration one, then a generic one if previous search failed. - if ((mi->evaluationFunction = funcs->getEEF(key)) != NULL) - return mi; - - else if ( pos.non_pawn_material(BLACK) == Value(0) - && pos.piece_count(BLACK, PAWN) == 0 - && pos.non_pawn_material(WHITE) >= RookValueEndgame) + // We didn't find any specialized scaling function, so fall back on generic + // ones that refer to more than one material distribution. Note that in this + // case we don't return after setting the function. + for (Color c : { WHITE, BLACK }) { - mi->evaluationFunction = &EvaluateKXK; - return mi; - } - else if ( pos.non_pawn_material(WHITE) == Value(0) - && pos.piece_count(WHITE, PAWN) == 0 - && pos.non_pawn_material(BLACK) >= RookValueEndgame) - { - mi->evaluationFunction = &EvaluateKKX; - return mi; - } - else if ( pos.pawns() == EmptyBoardBB - && pos.rooks() == EmptyBoardBB - && pos.queens() == EmptyBoardBB) - { - // Minor piece endgame with at least one minor piece per side, - // and no pawns. - assert(pos.knights(WHITE) | pos.bishops(WHITE)); - assert(pos.knights(BLACK) | pos.bishops(BLACK)); + if (is_KBPsK(pos, c)) + e->scalingFunction[c] = &ScaleKBPsK[c]; - if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2 - && pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2) - { - mi->evaluationFunction = &EvaluateKmmKm; - return mi; - } + else if (is_KQKRPs(pos, c)) + e->scalingFunction[c] = &ScaleKQKRPs[c]; } - // OK, we didn't find any special evaluation function for the current - // material configuration. Is there a suitable scaling function? - // - // The code below is rather messy, and it could easily get worse later, - // if we decide to add more special cases. We face problems when there - // are several conflicting applicable scaling functions and we need to - // decide which one to use. - Color c; - EndgameScalingFunctionBase* sf; - - if ((sf = funcs->getESF(key, &c)) != NULL) + if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) // Only pawns on the board { - mi->scalingFunction[c] = sf; - return mi; - } - - if ( pos.non_pawn_material(WHITE) == BishopValueMidgame - && pos.piece_count(WHITE, BISHOP) == 1 - && pos.piece_count(WHITE, PAWN) >= 1) - mi->scalingFunction[WHITE] = &ScaleKBPK; - - if ( pos.non_pawn_material(BLACK) == BishopValueMidgame - && pos.piece_count(BLACK, BISHOP) == 1 - && pos.piece_count(BLACK, PAWN) >= 1) - mi->scalingFunction[BLACK] = &ScaleKKBP; - - if ( pos.piece_count(WHITE, PAWN) == 0 - && pos.non_pawn_material(WHITE) == QueenValueMidgame - && pos.piece_count(WHITE, QUEEN) == 1 - && pos.piece_count(BLACK, ROOK) == 1 - && pos.piece_count(BLACK, PAWN) >= 1) - mi->scalingFunction[WHITE] = &ScaleKQKRP; - - else if ( pos.piece_count(BLACK, PAWN) == 0 - && pos.non_pawn_material(BLACK) == QueenValueMidgame - && pos.piece_count(BLACK, QUEEN) == 1 - && pos.piece_count(WHITE, ROOK) == 1 - && pos.piece_count(WHITE, PAWN) >= 1) - mi->scalingFunction[BLACK] = &ScaleKRPKQ; - - if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0)) - { - if (pos.piece_count(BLACK, PAWN) == 0) + if (!pos.count(BLACK)) { - assert(pos.piece_count(WHITE, PAWN) >= 2); - mi->scalingFunction[WHITE] = &ScaleKPsK; + assert(pos.count(WHITE) >= 2); + + e->scalingFunction[WHITE] = &ScaleKPsK[WHITE]; } - else if (pos.piece_count(WHITE, PAWN) == 0) + else if (!pos.count(WHITE)) { - assert(pos.piece_count(BLACK, PAWN) >= 2); - mi->scalingFunction[BLACK] = &ScaleKKPs; + assert(pos.count(BLACK) >= 2); + + e->scalingFunction[BLACK] = &ScaleKPsK[BLACK]; } - else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1) + else if (pos.count(WHITE) == 1 && pos.count(BLACK) == 1) { - mi->scalingFunction[WHITE] = &ScaleKPKPw; - mi->scalingFunction[BLACK] = &ScaleKPKPb; + // This is a special case because we set scaling functions + // for both colors instead of only one. + e->scalingFunction[WHITE] = &ScaleKPKP[WHITE]; + e->scalingFunction[BLACK] = &ScaleKPKP[BLACK]; } } - // Compute the space weight - if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= - 2*QueenValueMidgame + 4*RookValueMidgame + 2*KnightValueMidgame) - { - int minorPieceCount = pos.piece_count(WHITE, KNIGHT) - + pos.piece_count(BLACK, KNIGHT) - + pos.piece_count(WHITE, BISHOP) - + pos.piece_count(BLACK, BISHOP); - - mi->spaceWeight = minorPieceCount * minorPieceCount; - } - - // Evaluate the material balance - - int sign; - Value egValue = Value(0); - Value mgValue = Value(0); - - for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign) - { - // No pawns makes it difficult to win, even with a material advantage - if ( pos.piece_count(c, PAWN) == 0 - && pos.non_pawn_material(c) - pos.non_pawn_material(opposite_color(c)) <= BishopValueMidgame) - { - if ( pos.non_pawn_material(c) == pos.non_pawn_material(opposite_color(c)) - || pos.non_pawn_material(c) < RookValueMidgame) - mi->factor[c] = 0; - else - { - switch (pos.piece_count(c, BISHOP)) { - case 2: - mi->factor[c] = 32; - break; - case 1: - mi->factor[c] = 12; - break; - case 0: - mi->factor[c] = 6; - break; - } - } - } - - // Bishop pair - if (pos.piece_count(c, BISHOP) >= 2) - { - mgValue += sign * BishopPairMidgameBonus; - egValue += sign * BishopPairEndgameBonus; - } - - // Knights are stronger when there are many pawns on the board. The - // formula is taken from Larry Kaufman's paper "The Evaluation of Material - // Imbalances in Chess": - // http://mywebpages.comcast.net/danheisman/Articles/evaluation_of_material_imbalance.htm - mgValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16); - egValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16); - - // Redundancy of major pieces, again based on Kaufman's paper: - if (pos.piece_count(c, ROOK) >= 1) - { - Value v = Value((pos.piece_count(c, ROOK) - 1) * 32 + pos.piece_count(c, QUEEN) * 16); - mgValue -= sign * v; - egValue -= sign * v; - } - } - mi->mgValue = int16_t(mgValue); - mi->egValue = int16_t(egValue); - return mi; + // Zero or just one pawn makes it difficult to win, even with a small material + // advantage. This catches some trivial draws like KK, KBK and KNK and gives a + // drawish scale factor for cases such as KRKBP and KmmKm (except for KBBKN). + if (!pos.count(WHITE) && npm_w - npm_b <= BishopValueMg) + e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : + npm_b <= BishopValueMg ? 4 : 14); + + if (!pos.count(BLACK) && npm_b - npm_w <= BishopValueMg) + e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : + npm_w <= BishopValueMg ? 4 : 14); + + // Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder + // for the bishop pair "extended piece", which allows us to be more flexible + // in defining bishop pair bonuses. + const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = { + { pos.count(WHITE) > 1, pos.count(WHITE), pos.count(WHITE), + pos.count(WHITE) , pos.count(WHITE), pos.count(WHITE) }, + { pos.count(BLACK) > 1, pos.count(BLACK), pos.count(BLACK), + pos.count(BLACK) , pos.count(BLACK), pos.count(BLACK) } }; + + e->value = int16_t((imbalance(pieceCount) - imbalance(pieceCount)) / 16); + return e; } - -/// EndgameFunctions member definitions. This class is used to store the maps -/// of end game and scaling functions that MaterialInfoTable will query for -/// each key. The maps are constant and are populated only at construction, -/// but are per-thread instead of globals to avoid expensive locks. - -EndgameFunctions::EndgameFunctions() { - - KNNKMaterialKey = buildKey("KNNK"); - KKNNMaterialKey = buildKey("KKNN"); - - add("KPK", &EvaluateKPK); - add("KKP", &EvaluateKKP); - add("KBNK", &EvaluateKBNK); - add("KKBN", &EvaluateKKBN); - add("KRKP", &EvaluateKRKP); - add("KPKR", &EvaluateKPKR); - add("KRKB", &EvaluateKRKB); - add("KBKR", &EvaluateKBKR); - add("KRKN", &EvaluateKRKN); - add("KNKR", &EvaluateKNKR); - add("KQKR", &EvaluateKQKR); - add("KRKQ", &EvaluateKRKQ); - add("KBBKN", &EvaluateKBBKN); - add("KNKBB", &EvaluateKNKBB); - - add("KNPK", WHITE, &ScaleKNPK); - add("KKNP", BLACK, &ScaleKKNP); - add("KRPKR", WHITE, &ScaleKRPKR); - add("KRKRP", BLACK, &ScaleKRKRP); - add("KBPKB", WHITE, &ScaleKBPKB); - add("KBKBP", BLACK, &ScaleKBKBP); - add("KBPKN", WHITE, &ScaleKBPKN); - add("KNKBP", BLACK, &ScaleKNKBP); - add("KRPPKRP", WHITE, &ScaleKRPPKRP); - add("KRPKRPP", BLACK, &ScaleKRPKRPP); - add("KRPPKRP", WHITE, &ScaleKRPPKRP); - add("KRPKRPP", BLACK, &ScaleKRPKRPP); -} - -Key EndgameFunctions::buildKey(const std::string& keyCode) { - - assert(keyCode.length() > 0 && keyCode[0] == 'K'); - assert(keyCode.length() < 8); - - std::stringstream s; - bool upcase = false; - - // Build up a fen substring with the given pieces, note - // that the fen string could be of an illegal position. - for (size_t i = 0; i < keyCode.length(); i++) - { - if (keyCode[i] == 'K') - upcase = !upcase; - - s << char(upcase? toupper(keyCode[i]) : tolower(keyCode[i])); - } - s << 8 - keyCode.length() << "/8/8/8/8/8/8/8 w -"; - return Position(s.str()).get_material_key(); -} - -void EndgameFunctions::add(const std::string& keyCode, EndgameEvaluationFunctionBase* f) { - - EEFmap.insert(std::pair(buildKey(keyCode), f)); -} - -void EndgameFunctions::add(const std::string& keyCode, Color c, EndgameScalingFunctionBase* f) { - - ScalingInfo s = {c, f}; - ESFmap.insert(std::pair(buildKey(keyCode), s)); -} - -EndgameEvaluationFunctionBase* EndgameFunctions::getEEF(Key key) const { - - std::map::const_iterator it(EEFmap.find(key)); - return (it != EEFmap.end() ? it->second : NULL); -} - -EndgameScalingFunctionBase* EndgameFunctions::getESF(Key key, Color* c) const { - - std::map::const_iterator it(ESFmap.find(key)); - if (it == ESFmap.end()) - return NULL; - - *c = it->second.col; - return it->second.fun; -} +} // namespace Material