X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=f598e3bf1318d4a57e7368d5e9b18a284f86e56b;hp=1dc97f5d71cb9d6e05ae3aabe6887a6ce4ebc617;hb=927f1b0bd30a5b2cfdcdf163f26f528738509064;hpb=02f96fcf5ec82ddf4b94f7992acdfb548a7a218c diff --git a/src/tt.cpp b/src/tt.cpp index 1dc97f5d..f598e3bf 100644 --- a/src/tt.cpp +++ b/src/tt.cpp @@ -24,9 +24,8 @@ #include #include +#include -#include "evaluate.h" -#include "movegen.h" #include "tt.h" // The main transposition table @@ -56,30 +55,33 @@ void TranspositionTable::set_size(size_t mbSize) { size_t newSize = 1024; - // 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)) + // Transposition table consists of clusters and each cluster consists + // of ClusterSize number of TTEntries. Each non-empty entry contains + // information of exactly one position and newSize is the number of + // clusters we are going to allocate. + while (2ULL * newSize * sizeof(TTCluster) <= (mbSize << 20)) newSize *= 2; - if (newSize != size) + if (newSize == size) + return; + + 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(); - } + std::cerr << "Failed to allocate " << mbSize + << " MB for transposition table." << std::endl; + exit(EXIT_FAILURE); } + clear(); } /// 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() { @@ -87,15 +89,15 @@ void TranspositionTable::clear() { } -/// 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, Value statV, Value kingD) { @@ -106,9 +108,9 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, 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->key() == posKey32) // Empty or overwrite old { - // Preserve any exsisting ttMove + // Preserve any existing ttMove if (m == MOVE_NONE) m = tte->move(); @@ -116,7 +118,8 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, return; } - if (i == 0) // replace would be a no-op in this common case + // Replacing first entry is default and already set before entering for-loop + if (i == 0) continue; c1 = (replace->generation() == generation ? 2 : 0); @@ -155,59 +158,3 @@ TTEntry* TranspositionTable::retrieve(const Key posKey) const { void TranspositionTable::new_search() { generation++; } - - -/// 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; - EvalInfo ei; - Value v; - Position p(pos, pos.thread()); - - for (int i = 0; pv[i] != MOVE_NONE; i++) - { - TTEntry *tte = retrieve(p.get_key()); - if (!tte || tte->move() != pv[i]) - { - v = (p.is_check() ? VALUE_NONE : evaluate(p, ei)); - store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[i], v, ei.kingDanger[pos.side_to_move()]); - } - p.do_move(pv[i], st); - } -} - - -/// TranspositionTable::extract_pv() builds a PV by adding moves from the -/// transposition table. We consider also failing high nodes and not only -/// VALUE_TYPE_EXACT nodes. This allow to always have a ponder move even -/// when we fail high at root and also a long PV to print that is important -/// for position analysis. - -void TranspositionTable::extract_pv(const Position& pos, Move bestMove, Move pv[], const int PLY_MAX) { - - const TTEntry* tte; - StateInfo st; - Position p(pos, pos.thread()); - int ply = 0; - - assert(bestMove != MOVE_NONE); - - pv[ply] = bestMove; - p.do_move(pv[ply++], st); - - 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; -}