X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=c6b294a00cad8fd5aeb1eae1bf673b53b3f4026a;hp=e140a0ba10ec5fa2183b506b68750a4dcbc39289;hb=d44ac0a4850f389ee2fdb8812104150c323d9ec2;hpb=fd12e8cb239180607559bb805e233f7ea704a67c diff --git a/src/tt.cpp b/src/tt.cpp index e140a0ba..c6b294a0 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2013 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 @@ -17,241 +17,106 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - -#include -#include #include -#include +#include -#include "movegen.h" +#include "bitboard.h" #include "tt.h" -// The main transposition table -TranspositionTable TT; +TranspositionTable TT; // Our global transposition table -//// -//// Functions -//// -TranspositionTable::TranspositionTable() { - - size = writes = 0; - entries = 0; - generation = 0; -} - -TranspositionTable::~TranspositionTable() { - - delete [] entries; -} +/// TranspositionTable::set_size() sets the size of the transposition table, +/// measured in megabytes. Transposition table consists of a power of 2 number +/// of clusters and each cluster consists of ClusterSize number of TTEntry. +void TranspositionTable::set_size(size_t mbSize) { -/// TranspositionTable::set_size sets the size of the transposition table, -/// measured in megabytes. + assert(msb((mbSize << 20) / sizeof(TTEntry)) < 32); -void TranspositionTable::set_size(unsigned mbSize) { + uint32_t size = ClusterSize << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize])); - assert(mbSize >= 4 && mbSize <= 4096); + if (hashMask == size - ClusterSize) + return; - unsigned newSize = 1024; + hashMask = size - ClusterSize; + free(mem); + mem = malloc(size * sizeof(TTEntry) + CACHE_LINE_SIZE - 1); - // We store a cluster of ClusterSize number of TTEntry for each position - // and newSize is the maximum number of storable positions. - while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20)) - newSize *= 2; - - if (newSize != size) + if (!mem) { - size = newSize; - delete [] entries; - entries = new TTCluster[size]; - if (!entries) - { - std::cerr << "Failed to allocate " << mbSize - << " MB for transposition table." << std::endl; - Application::exit_with_failure(); - } - clear(); + std::cerr << "Failed to allocate " << mbSize + << "MB for transposition table." << std::endl; + exit(EXIT_FAILURE); } + + table = (TTEntry*)((uintptr_t(mem) + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 1)); + clear(); // Operator new is not guaranteed to initialize memory to zero } -/// TranspositionTable::clear overwrites the entire transposition table +/// 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 * sizeof(TTCluster)); -} - - -/// TranspositionTable::first_entry returns a pointer to the first -/// entry of a cluster given a position. The low 32 bits of the key -/// are used to get the index in the table. - -inline TTEntry* TranspositionTable::first_entry(const Key posKey) const { - - return entries[uint32_t(posKey) & (size - 1)].data; + memset(table, 0, (hashMask + ClusterSize) * sizeof(TTEntry)); } -/// 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. 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, ValueType t, Depth d, Move m) { +void TranspositionTable::store(const Key key, Value v, Bound t, Depth d, Move m, Value statV, Value kingD) { + int c1, c2, c3; TTEntry *tte, *replace; - uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key + uint32_t key32 = key >> 32; // Use the high 32 bits as key inside the cluster + + tte = replace = first_entry(key); - tte = replace = first_entry(posKey); - for (int i = 0; i < ClusterSize; i++, tte++) + for (unsigned i = 0; i < ClusterSize; i++, tte++) { - if (!tte->key() || tte->key() == posKey32) // empty or overwrite old + if (!tte->key() || tte->key() == key32) // Empty or overwrite old { - // Do not overwrite when new type is VALUE_TYPE_EVAL - if (tte->key() && t == VALUE_TYPE_EVAL) - return; - + // Preserve any existing ttMove if (m == MOVE_NONE) m = tte->move(); - *tte = TTEntry(posKey32, v, t, d, m, generation); + tte->save(key32, v, t, d, m, generation, statV, kingD); 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); + // 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(posKey32, v, t, d, m, generation); - writes++; + replace->save(key32, v, t, d, m, generation, statV, kingD); } -/// 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 Key posKey) const { +TTEntry* TranspositionTable::probe(const Key key) const { - uint32_t posKey32 = posKey >> 32; - TTEntry* tte = first_entry(posKey); + TTEntry* tte = first_entry(key); + uint32_t key32 = key >> 32; - for (int i = 0; i < ClusterSize; i++, tte++) - if (tte->key() == posKey32) + for (unsigned i = 0; i < ClusterSize; i++, tte++) + if (tte->key() == key32) return tte; return NULL; } - - -/// TranspositionTable::prefetch looks up the current position in the -/// transposition table and load it in L1/L2 cache. This is a non -/// blocking function and do not stalls the CPU waiting for data -/// to be loaded from RAM, that can be very slow. When we will -/// subsequently call retrieve() the TT data will be already -/// quickly accessible in L1/L2 CPU cache. - -void TranspositionTable::prefetch(const Key posKey) const { - -#if defined(__INTEL_COMPILER) || defined(__ICL) - // This hack prevents prefetches to be optimized away by the - // Intel compiler. Both MSVC and gcc seems not affected. - __asm__ (""); -#endif - - char const* addr = (char*)first_entry(posKey); - _mm_prefetch(addr, _MM_HINT_T2); - _mm_prefetch(addr+64, _MM_HINT_T2); // 64 bytes ahead -} - - -/// TranspositionTable::new_search() is called at the beginning of every new -/// 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.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]); - p.do_move(pv[i], st); - } -} - - -/// TranspositionTable::extract_pv() extends a PV by adding moves from the -/// transposition table at the end. This should ensure that the PV is almost -/// always at least two plies long, which is important, because otherwise we -/// will often get single-move PVs when the search stops while failing high, -/// and a single-move PV means that we don't have a ponder move. - -void TranspositionTable::extract_pv(const Position& pos, Move pv[]) { - - int ply; - Position p(pos); - StateInfo st[100]; - - for (ply = 0; pv[ply] != MOVE_NONE; ply++) - p.do_move(pv[ply], st[ply]); - - bool stop; - const TTEntry* tte; - for (stop = false, tte = retrieve(p.get_key()); - tte && tte->move() != MOVE_NONE && !stop; - tte = retrieve(p.get_key()), ply++) - { - if (!move_is_legal(p, tte->move())) - break; - pv[ply] = tte->move(); - p.do_move(pv[ply], st[ply]); - for (int j = 0; j < ply; j++) - if (st[j].key == p.get_key()) stop = true; - } - pv[ply] = MOVE_NONE; -} - - -/// 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() const { - - double N = double(size) * ClusterSize; - return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N)))); -}