X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=40dca0d3b2524b221d14f0d2a7fccf2049d3a64a;hp=4cc19c5901b7079bcc8a12c2f055b8413e641c5b;hb=98cd8239cc351f337132bb8cf08be728580c078d;hpb=2550c6383b4646d64ab431cbb573991353ed7a2e diff --git a/src/tt.cpp b/src/tt.cpp index 4cc19c59..40dca0d3 100644 --- a/src/tt.cpp +++ b/src/tt.cpp @@ -1,7 +1,7 @@ /* 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) 2008-2012 Marco Costalba, Joona Kiiski, 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 @@ -17,200 +17,125 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - -#include -#include #include +#include +#include "bitboard.h" #include "tt.h" +TranspositionTable TT; // Our global transposition table -//// -//// Functions -//// - -/// Constructor +TranspositionTable::TranspositionTable() { -TranspositionTable::TranspositionTable(unsigned mbSize) { - - size = 0; - generation = 0; - writes = 0; - entries = 0; - set_size(mbSize); + size = generation = 0; + entries = NULL; } - -/// Destructor - TranspositionTable::~TranspositionTable() { delete [] entries; } -/// TranspositionTable::set_size sets the size of the transposition table, -/// measured in megabytes. +/// TranspositionTable::set_size() sets the size of the transposition table, +/// measured in megabytes. Transposition table consists of a power of 2 number of +/// TTCluster and each cluster consists of ClusterSize number of TTEntries. Each +/// non-empty entry contains information of exactly one position. + +void TranspositionTable::set_size(size_t mbSize) { -void TranspositionTable::set_size(unsigned mbSize) { + size_t newSize = 1ULL << msb((mbSize << 20) / sizeof(TTCluster)); - assert(mbSize >= 4 && mbSize <= 4096); + if (newSize == size) + return; - unsigned newSize = 1024; + size = newSize; + delete [] entries; + entries = new (std::nothrow) TTCluster[size]; - // We store a cluster of 4 TTEntry for each position and newSize is - // the maximum number of storable positions - for ( ; newSize * 4 * (sizeof(TTEntry)) <= (mbSize << 20); newSize *= 2); - newSize /= 2; - if (newSize != size) + if (!entries) { - size = newSize; - delete [] entries; - entries = new TTEntry[size * 4]; - if (!entries) - { std::cerr << "Failed to allocate " << mbSize - << " MB for transposition table." - << std::endl; + << "MB for transposition table." << std::endl; exit(EXIT_FAILURE); - } - clear(); } + + clear(); // Operator new is not guaranteed to initialize memory to zero } -/// TranspositionTable::clear overwrites the entire transposition table -/// with zeroes. It is called whenever the table is resized, or when the +/// TranspositionTable::clear() overwrites the entire transposition table +/// with zeroes. It is called whenever the table is resized, or when the /// user asks the program to clear the table (from the UCI interface). -/// Perhaps we should also clear it when the "ucinewgame" command is recieved? void TranspositionTable::clear() { - memset(entries, 0, size * 4 * sizeof(TTEntry)); + memset(entries, 0, size * sizeof(TTCluster)); } -/// TranspositionTable::store writes a new entry containing a position, -/// a value, a value type, a search depth, and a best move to the -/// transposition table. The transposition table is organized in clusters -/// of four TTEntry objects, and when a new entry is written, it replaces -/// the least valuable of the four entries in a cluster. A TTEntry t1 is -/// considered to be more valuable than a TTEntry t2 if t1 is from the -/// current search and t2 is from a previous search, or if the depth of t1 -/// is bigger than the depth of t2. A TTEntry of type VALUE_TYPE_EVAL -/// never replaces another entry for the same position. +/// TranspositionTable::store() writes a new entry containing position key and +/// valuable information of current position. The lowest order bits of position +/// key are used to decide on which cluster the position will be placed. +/// When a new entry is written and there are no empty entries available in cluster, +/// it replaces the least valuable of entries. A TTEntry t1 is considered to be +/// more valuable than a TTEntry t2 if t1 is from the current search and t2 is from +/// a previous search, or if the depth of t1 is bigger than the depth of t2. + +void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move m) { -void TranspositionTable::store(const Position &pos, Value v, Depth d, - Move m, ValueType type) { + int c1, c2, c3; TTEntry *tte, *replace; + uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key inside the cluster - tte = replace = first_entry(pos); - for (int i = 0; i < 4; i++, tte++) + tte = replace = first_entry(posKey); + + for (int i = 0; i < ClusterSize; i++, tte++) { - if (!tte->key() || tte->key() == pos.get_key()) // empty or overwrite old - { - // Do not overwrite position entry when VALUE_TYPE_EVAL - if ( tte->key() - && type == VALUE_TYPE_EVAL) - return; - - if (m == MOVE_NONE) - m = tte->move(); - - *tte = TTEntry(pos.get_key(), v, type, d, m, generation); - return; - } - else if (i == 0) // replace would be a no-op in this common case - continue; - - int c1 = (replace->generation() == generation ? 2 : 0); - int c2 = (tte->generation() == generation ? -2 : 0); - int c3 = (tte->depth() < replace->depth() ? 1 : 0); - - if (c1 + c2 + c3 > 0) - replace = tte; + if (!tte->key() || tte->key() == posKey32) // Empty or overwrite old + { + // Preserve any existing ttMove + if (m == MOVE_NONE) + m = tte->move(); + + tte->save(posKey32, v, t, d, m, generation); + return; + } + + // Implement replace strategy + c1 = (replace->generation() == generation ? 2 : 0); + c2 = (tte->generation() == generation || tte->type() == BOUND_EXACT ? -2 : 0); + c3 = (tte->depth() < replace->depth() ? 1 : 0); + + if (c1 + c2 + c3 > 0) + replace = tte; } - *replace = TTEntry(pos.get_key(), v, type, d, m, generation); - writes++; + replace->save(posKey32, v, t, d, m, generation); } -/// TranspositionTable::retrieve looks up the current position in the -/// transposition table. Returns a pointer to the TTEntry or NULL -/// if position is not found. +/// TranspositionTable::probe() looks up the current position in the +/// transposition table. Returns a pointer to the TTEntry or NULL if +/// position is not found. -TTEntry* TranspositionTable::retrieve(const Position &pos) const { +TTEntry* TranspositionTable::probe(const Key posKey) const { - TTEntry *tte = first_entry(pos); + uint32_t posKey32 = posKey >> 32; + TTEntry* tte = first_entry(posKey); - for (int i = 0; i < 4; i++, tte++) - { - if (tte->key() == pos.get_key()) + for (int i = 0; i < ClusterSize; i++, tte++) + if (tte->key() == posKey32) return tte; - } + return NULL; } -/// TranspositionTable::first_entry returns a pointer to the first -/// entry of a cluster given a position. - -inline TTEntry* TranspositionTable::first_entry(const Position &pos) const { - - return entries + (int(pos.get_key() & (size - 1)) << 2); -} - /// TranspositionTable::new_search() is called at the beginning of every new -/// search. It increments the "generation" variable, which is used to +/// search. It increments the "generation" variable, which is used to /// distinguish transposition table entries from previous searches from /// entries from the current search. void TranspositionTable::new_search() { - generation++; - writes = 0; } - - -/// TranspositionTable::insert_pv() is called at the end of a search -/// iteration, and inserts the PV back into the PV. This makes sure the -/// old PV moves are searched first, even if the old TT entries have been -/// overwritten. - -void TranspositionTable::insert_pv(const Position &pos, Move pv[]) { - - StateInfo st; - Position p(pos); - - for (int i = 0; pv[i] != MOVE_NONE; i++) - { - store(p, VALUE_NONE, Depth(-127*OnePly), pv[i], VALUE_TYPE_NONE); - p.do_move(pv[i], st); - } -} - - -/// TranspositionTable::full() returns the permill of all transposition table -/// entries which have received at least one write during the current search. -/// It is used to display the "info hashfull ..." information in UCI. - -int TranspositionTable::full() { - - double N = double(size) * 4.0; - return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N)))); -} - - -/// Constructors - -TTEntry::TTEntry() { -} - -TTEntry::TTEntry(Key k, Value v, ValueType t, Depth d, Move m, - int generation) : - key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)), - value_(int16_t(v)), depth_(int16_t(d)) {}