X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=8a66812a79c1eda84909dc20d09ead945a1c89de;hp=555f3c6d0e501fc262036eb5c412083ab642fcf2;hb=feeafb0a50556654e345a09d16529a5eb7715dc0;hpb=cab8b788465c34f5fc3d3caeeaee098c1ea185fe diff --git a/src/tt.cpp b/src/tt.cpp index 555f3c6d..8a66812a 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) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + 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 @@ -17,33 +17,18 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - -#include -#include #include -#if !defined(NO_PREFETCH) -# include -#endif +#include -#include "movegen.h" +#include "bitboard.h" #include "tt.h" -// The main transposition table -TranspositionTable TT; - -//// -//// Functions -//// +TranspositionTable TT; // Our global transposition table TranspositionTable::TranspositionTable() { - size = writes = 0; - entries = 0; - generation = 0; + size = generation = 0; + entries = NULL; } TranspositionTable::~TranspositionTable() { @@ -52,38 +37,36 @@ TranspositionTable::~TranspositionTable() { } -/// 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) { - size_t newSize = 1024; + size_t newSize = 1ULL << msb((mbSize << 20) / sizeof(TTCluster)); - // 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) + return; - if (newSize != size) + size = newSize; + delete [] entries; + entries = new (std::nothrow) TTCluster[size]; + + if (!entries) { - 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); } + + 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() { @@ -91,63 +74,54 @@ void TranspositionTable::clear() { } -/// 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; -} - +/// 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. -/// 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. - -void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m) { +void TranspositionTable::store(const Key posKey, Value v, Bound b, Depth d, Move m) { + int c1, c2, c3; TTEntry *tte, *replace; - uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key + uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key inside the cluster tte = replace = first_entry(posKey); + for (int i = 0; i < ClusterSize; i++, tte++) { - if (!tte->key() || tte->key() == posKey32) // empty or overwrite old + if (!tte->key()) + tte->save(posKey32, v, b, d, m, generation); + + if (tte->key() == posKey32) { - // Preserve any exsisting ttMove + // Preserve any existing ttMove if (m == MOVE_NONE) m = tte->move(); - *tte = TTEntry(posKey32, v, t, d, m, generation); + tte->update(v, b, 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); + // 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(posKey32, v, b, 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 Key posKey) const { +TTEntry* TranspositionTable::probe(const Key posKey) const { uint32_t posKey32 = posKey >> 32; TTEntry* tte = first_entry(posKey); @@ -160,100 +134,11 @@ TTEntry* TranspositionTable::retrieve(const Key posKey) const { } -/// 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. -#if defined(NO_PREFETCH) -void TranspositionTable::prefetch(const Key) const {} -#else - -void TranspositionTable::prefetch(const Key posKey) const { - -#if defined(__INTEL_COMPILER) || defined(__ICL) - // This hack prevents prefetches to be optimized away by - // 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 -} - -#endif - /// 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++) - { - TTEntry *tte = retrieve(p.get_key()); - if (!tte || tte->move() != pv[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[], const int PLY_MAX) { - - const TTEntry* tte; - StateInfo st; - Position p(pos); - int ply = 0; - - // Update position to the end of current PV - while (pv[ply] != MOVE_NONE) - p.do_move(pv[ply++], st); - - // Try to add moves from TT while possible - while ( (tte = retrieve(p.get_key())) != NULL - && tte->move() != MOVE_NONE - && move_is_legal(p, tte->move()) - && (!p.is_draw() || ply < 2) - && ply < PLY_MAX) - { - pv[ply] = tte->move(); - p.do_move(pv[ply++], st); - } - 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)))); }