X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=375c00a67308fbc934e7cad2fe569f5a780468f3;hp=a8aa1b6574604d48fb91a513a066e6dedbaec0ae;hb=9ca4359f3691305fc5e3306c3084c83557ce09c0;hpb=b056e5d40ab4e90530df53bb110bd74a41a8df07 diff --git a/src/tt.cpp b/src/tt.cpp index a8aa1b65..375c00a6 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) 2008-2010 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 @@ -23,11 +23,8 @@ //// #include -#include #include -#include -#include "movegen.h" #include "tt.h" // The main transposition table @@ -39,7 +36,7 @@ TranspositionTable TT; TranspositionTable::TranspositionTable() { - size = writes = 0; + size = 0; entries = 0; generation = 0; } @@ -53,14 +50,14 @@ TranspositionTable::~TranspositionTable() { /// TranspositionTable::set_size sets the size of the transposition table, /// measured in megabytes. -void TranspositionTable::set_size(unsigned mbSize) { +void TranspositionTable::set_size(size_t mbSize) { - assert(mbSize >= 4 && mbSize <= 4096); + size_t newSize = 1024; - unsigned newSize = 1024; - - // We store a cluster of ClusterSize number of TTEntry for each position - // and newSize is the maximum number of storable positions. + // Transposition table consists of clusters and + // each cluster consists of ClusterSize number of TTEntries. + // Each non-empty entry contains information of exactly one position. + // newSize is the number of clusters we are going to allocate. while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20)) newSize *= 2; @@ -83,7 +80,7 @@ void TranspositionTable::set_size(unsigned mbSize) { /// 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? +/// Perhaps we should also clear it when the "ucinewgame" command is received? void TranspositionTable::clear() { @@ -91,28 +88,19 @@ 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 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 +/// 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. A TTEntry of type VALUE_TYPE_EVAL -/// never replaces another entry for the same position. +/// 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 posKey, Value v, ValueType 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 @@ -121,28 +109,25 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, { if (!tte->key() || tte->key() == posKey32) // empty or overwrite old { - // Do not overwrite when new type is VALUE_TYPE_EV_LO - if (tte->key() && t == VALUE_TYPE_EV_LO) - return; - + // Preserve any existing ttMove if (m == MOVE_NONE) m = tte->move(); - *tte = TTEntry(posKey32, v, t, d, m, generation); + tte->save(posKey32, v, t, d, m, generation, statV, kingD); return; } - else if (i == 0) // replace would be a no-op in this common case + + if (i == 0) // Replacing first entry is default and already set before entering for-loop continue; - int c1 = (replace->generation() == generation ? 2 : 0); - int c2 = (tte->generation() == generation ? -2 : 0); - int c3 = (tte->depth() < replace->depth() ? 1 : 0); + c1 = (replace->generation() == generation ? 2 : 0); + c2 = (tte->generation() == generation ? -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, t, d, m, generation, statV, kingD); } @@ -163,96 +148,11 @@ 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. - -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++) - { - 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)))); }