/*
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) 2008-2010 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
#include <cassert>
#include <cmath>
#include <cstring>
+#if defined(__i386__) || defined(_M_IX86) || defined(_X86_)
+# include <xmmintrin.h>
+#endif
+#include "movegen.h"
#include "tt.h"
+// The main transposition table
+TranspositionTable TT;
////
//// Functions
////
-/// Constructor
+TranspositionTable::TranspositionTable() {
-TranspositionTable::TranspositionTable(unsigned mbSize) {
-
- size = 0;
- generation = 0;
- writes = 0;
+ size = writes = 0;
entries = 0;
- set_size(mbSize);
+ generation = 0;
}
-
-/// Destructor
-
TranspositionTable::~TranspositionTable() {
delete [] entries;
/// 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 <= 1024);
+ 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.
+ while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20))
+ newSize *= 2;
- // 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)
{
- size = newSize;
- delete [] entries;
- entries = new TTEntry[size * 4];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << mbSize
- << " MB for transposition table."
- << std::endl;
- exit(EXIT_FAILURE);
- }
- clear();
+ 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();
}
}
/// TranspositionTable::clear overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// 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::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. 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
+/// 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.
+/// 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 Position &pos, Value v, Depth d,
- Move m, ValueType type) {
TTEntry *tte, *replace;
+ uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
- 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
- {
- 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 exsisting ttMove
+ if (m == MOVE_NONE)
+ m = tte->move();
+
+ *tte = TTEntry(posKey32, v, t, 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;
}
- *replace = TTEntry(pos.get_key(), v, type, d, m, generation);
+ *replace = TTEntry(posKey32, v, t, d, m, generation);
writes++;
}
/// transposition table. Returns a pointer to the TTEntry or NULL
/// if position is not found.
-TTEntry* TranspositionTable::retrieve(const Position &pos) const {
+TTEntry* TranspositionTable::retrieve(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.
+/// 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(__i386__) || defined(_M_IX86) || defined(_X86_))
+void TranspositionTable::prefetch(const Key) const {}
+#else
-inline TTEntry* TranspositionTable::first_entry(const Position &pos) const {
+void TranspositionTable::prefetch(const Key posKey) const {
- return entries + (int(pos.get_key() & (size - 1)) << 2);
+#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
+/// search. It increments the "generation" variable, which is used to
/// distinguish transposition table entries from previous searches from
/// entries from the current search.
/// 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.
+/// 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[]) {
+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);
+ 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::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.
+/// 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.
-int TranspositionTable::full() {
+void TranspositionTable::extract_pv(const Position& pos, Move pv[], const int PLY_MAX) {
- double N = double(size) * 4.0;
- return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
+ 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;
}
-/// Constructors
+/// 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 {
-TTEntry::TTEntry() {
+ double N = double(size) * ClusterSize;
+ return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
}
-
-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)) {}
projects / stockfish / blobdiff