X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=26791809f8890bb6aed2e492838b9a9473b2aaf2;hp=1dc97f5d71cb9d6e05ae3aabe6887a6ce4ebc617;hb=e7cfa5d020efb5a0ad2521afc7b886f3b2d3e6b3;hpb=02f96fcf5ec82ddf4b94f7992acdfb548a7a218c
diff --git a/src/tt.cpp b/src/tt.cpp
index 1dc97f5d..26791809 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
@@ -17,197 +18,140 @@
along with this program. If not, see .
*/
+#include // For std::memset
+#include
+#include
-////
-//// Includes
-////
-
-#include
-#include
-
-#include "evaluate.h"
-#include "movegen.h"
+#include "bitboard.h"
+#include "misc.h"
#include "tt.h"
+#include "uci.h"
-// The main transposition table
-TranspositionTable TT;
+TranspositionTable TT; // Our global transposition table
-////
-//// Functions
-////
+/// TTEntry::save saves a TTEntry
+void TTEntry::save(Key k, Value v, Bound b, Depth d, Move m, Value ev) {
-TranspositionTable::TranspositionTable() {
+ assert(d / ONE_PLY * ONE_PLY == d);
- size = 0;
- entries = 0;
- generation = 0;
-}
+ // Preserve any existing move for the same position
+ if (m || (k >> 48) != key16)
+ move16 = (uint16_t)m;
-TranspositionTable::~TranspositionTable() {
-
- delete [] entries;
+ // Overwrite less valuable entries
+ if ( (k >> 48) != key16
+ || d / ONE_PLY > depth8 - 4
+ || b == BOUND_EXACT)
+ {
+ key16 = (uint16_t)(k >> 48);
+ value16 = (int16_t)v;
+ eval16 = (int16_t)ev;
+ genBound8 = (uint8_t)(TT.generation8 | b);
+ depth8 = (int8_t)(d / ONE_PLY);
+ }
}
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+/// 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::set_size(size_t mbSize) {
+void TranspositionTable::resize(size_t mbSize) {
- size_t newSize = 1024;
+ clusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
- // 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();
- }
+ std::cerr << "Failed to allocate " << mbSize
+ << "MB for transposition table." << std::endl;
+ exit(EXIT_FAILURE);
}
-}
-
-/// 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?
-
-void TranspositionTable::clear() {
-
- memset(entries, 0, size * sizeof(TTCluster));
+ table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
+ 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
-/// 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::clear() initializes the entire transposition table to zero,
+// in a multi-threaded way.
-void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) {
+void TranspositionTable::clear() {
- int c1, c2, c3;
- TTEntry *tte, *replace;
- uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
+ std::vector threads;
- tte = replace = first_entry(posKey);
- for (int i = 0; i < ClusterSize; i++, tte++)
+ for (size_t idx = 0; idx < Options["Threads"]; idx++)
{
- if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
- {
- // Preserve any exsisting ttMove
- if (m == MOVE_NONE)
- m = tte->move();
-
- tte->save(posKey32, v, t, d, m, generation, statV, kingD);
- return;
- }
+ threads.push_back(std::thread([this, idx]() {
- if (i == 0) // replace would be a no-op in this common case
- continue;
+ // Thread binding gives faster search on systems with a first-touch policy
+ if (Options["Threads"] >= 8)
+ WinProcGroup::bindThisThread(idx);
- c1 = (replace->generation() == generation ? 2 : 0);
- c2 = (tte->generation() == generation ? -2 : 0);
- c3 = (tte->depth() < replace->depth() ? 1 : 0);
+ // Each thread will zero its part of the hash table
+ const size_t stride = clusterCount / Options["Threads"],
+ start = stride * idx,
+ len = idx != Options["Threads"] - 1 ?
+ stride : clusterCount - start;
- if (c1 + c2 + c3 > 0)
- replace = tte;
+ std::memset(&table[start], 0, len * sizeof(Cluster));
+ }));
}
- replace->save(posKey32, v, t, d, m, generation, statV, kingD);
-}
-
-/// 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::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++;
+ for (std::thread& th: threads)
+ th.join();
}
+/// 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.
-/// 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.
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
-void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
- 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])
+ for (int i = 0; i < ClusterSize; ++i)
+ if (!tte[i].key16 || tte[i].key16 == key16)
{
- 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);
- }
-}
-
+ if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+ tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
-/// 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.
+ return found = (bool)tte[i].key16, &tte[i];
+ }
-void TranspositionTable::extract_pv(const Position& pos, Move bestMove, Move pv[], const int PLY_MAX) {
+ // 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;
+}
- const TTEntry* tte;
- StateInfo st;
- Position p(pos, pos.thread());
- int ply = 0;
- assert(bestMove != MOVE_NONE);
+/// TranspositionTable::hashfull() returns an approximation of the hashtable
+/// occupation during a search. The hash is x permill full, as per UCI protocol.
- pv[ply] = bestMove;
- p.do_move(pv[ply++], st);
+int TranspositionTable::hashfull() const {
- 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)
+ int cnt = 0;
+ for (int i = 0; i < 1000 / ClusterSize; i++)
{
- pv[ply] = tte->move();
- p.do_move(pv[ply++], st);
+ const TTEntry* tte = &table[i].entry[0];
+ for (int j = 0; j < ClusterSize; j++)
+ if ((tte[j].genBound8 & 0xFC) == generation8)
+ cnt++;
}
- pv[ply] = MOVE_NONE;
+ return cnt;
}