////
#include <cassert>
-#include <cmath>
#include <cstring>
-#if !defined(NO_PREFETCH)
-# include <xmmintrin.h>
-#endif
+#include <iostream>
-#include "movegen.h"
#include "tt.h"
// The main transposition table
TranspositionTable::TranspositionTable() {
- size = writes = 0;
+ size = 0;
entries = 0;
generation = 0;
}
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();
- }
- clear();
+ 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() {
}
-/// 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, Value statV, Value kingD) {
+ int c1, c2, c3;
TTEntry *tte, *replace;
uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
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();
- *tte = TTEntry(posKey32, v, t, d, m, generation, statV, kingD);
+ 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
+
+ // Replacing first entry is default and already set before entering for-loop
+ if (i == 0)
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, statV, kingD);
- writes++;
+ replace->save(posKey32, v, t, d, m, generation, statV, kingD);
}
}
-/// 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, pos.thread());
-
- 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], VALUE_NONE, VALUE_NONE);
- 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, pos.thread());
- 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))));
}
projects / stockfish / blobdiff