X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Ftt.cpp;h=25f1cd03f67cfd22024a55e1d67d13fd48f92aec;hb=c794c8c8016dfdc8360c9d5ab74dffa9d93d9277;hp=555f3c6d0e501fc262036eb5c412083ab642fcf2;hpb=cab8b788465c34f5fc3d3caeeaee098c1ea185fe;p=stockfish
diff --git a/src/tt.cpp b/src/tt.cpp
index 555f3c6d..25f1cd03 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,7 +1,8 @@
/*
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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -17,243 +18,101 @@
along with this program. If not, see .
*/
+#include // For std::memset
+#include
-////
-//// Includes
-////
-
-#include
-#include
-#include
-#if !defined(NO_PREFETCH)
-# include
-#endif
-
-#include "movegen.h"
+#include "bitboard.h"
#include "tt.h"
-// The main transposition table
-TranspositionTable TT;
+TranspositionTable TT; // Our global transposition table
-////
-//// Functions
-////
-TranspositionTable::TranspositionTable() {
-
- size = writes = 0;
- entries = 0;
- generation = 0;
-}
-
-TranspositionTable::~TranspositionTable() {
-
- delete [] entries;
-}
+/// TranspositionTable::resize() sets the size of the transposition table,
+/// measured in megabytes. Transposition table consists of a power of 2 number
+/// of clusters and each cluster consists of ClusterSize number of TTEntry.
+void TranspositionTable::resize(size_t mbSize) {
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+ size_t newClusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
-void TranspositionTable::set_size(size_t mbSize) {
+ if (newClusterCount == clusterCount)
+ return;
- size_t newSize = 1024;
+ clusterCount = newClusterCount;
- // 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;
+ free(mem);
+ mem = malloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1);
- if (newSize != size)
+ if (!mem)
{
- 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);
}
+
+ table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
+ clear();
}
-/// TranspositionTable::clear overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// TranspositionTable::clear() overwrites the entire transposition table
+/// with zeros. 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 * 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;
+ std::memset(table, 0, clusterCount * sizeof(Cluster));
}
-/// 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.
+/// TranspositionTable::probe() looks up the current position in the transposition
+/// table. It returns true and a pointer to the TTEntry if the position is found.
+/// Otherwise, it returns false and a pointer to an empty or least valuable TTEntry
+/// to be replaced later. The replace value of an entry is calculated as its depth
+/// minus 8 times its relative age. TTEntry t1 is considered more valuable than
+/// TTEntry t2 if its replace value is greater than that of t2.
-void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m) {
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
- TTEntry *tte, *replace;
- uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 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
+ for (int i = 0; i < ClusterSize; ++i)
+ if (!tte[i].key16 || tte[i].key16 == key16)
{
- // Preserve any exsisting ttMove
- if (m == MOVE_NONE)
- m = tte->move();
+ if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+ tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
- *tte = TTEntry(posKey32, v, t, d, m, generation);
- return;
+ return found = (bool)tte[i].key16, &tte[i];
}
- 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(posKey32, v, t, d, m, generation);
- writes++;
+ // Find an entry to be replaced according to the replacement strategy
+ TTEntry* replace = tte;
+ for (int i = 1; i < ClusterSize; ++i)
+ // Due to our packed storage format for generation and its cyclic
+ // nature we add 259 (256 is the modulus plus 3 to keep the lowest
+ // two bound bits from affecting the result) to calculate the entry
+ // age correctly even after generation8 overflows into the next cycle.
+ if ( replace->depth8 - ((259 + generation8 - replace->genBound8) & 0xFC) * 2
+ > tte[i].depth8 - ((259 + generation8 - tte[i].genBound8) & 0xFC) * 2)
+ replace = &tte[i];
+
+ return found = false, replace;
}
-/// TranspositionTable::retrieve 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 {
-
- uint32_t posKey32 = posKey >> 32;
- TTEntry* tte = first_entry(posKey);
-
- for (int i = 0; i < ClusterSize; i++, tte++)
- if (tte->key() == posKey32)
- return tte;
-
- return NULL;
-}
-
-
-/// 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 {
+/// TranspositionTable::hashfull() returns an approximation of the hashtable
+/// occupation during a search. The hash is x permill full, as per UCI protocol.
-#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
+int TranspositionTable::hashfull() const {
- 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++)
+ int cnt = 0;
+ for (int i = 0; i < 1000 / ClusterSize; 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);
+ const TTEntry* tte = &table[i].entry[0];
+ for (int j = 0; j < ClusterSize; j++)
+ if ((tte[j].genBound8 & 0xFC) == generation8)
+ cnt++;
}
-}
-
-
-/// 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))));
+ return cnt;
}