X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=04cd7357c336af960f6b8ae8ee26bec2db79cd79;hp=375c00a67308fbc934e7cad2fe569f5a780468f3;hb=8c4f0ffa1d1cc6952874ee30fff9f826646b1aeb;hpb=9ca4359f3691305fc5e3306c3084c83557ce09c0
diff --git a/src/tt.cpp b/src/tt.cpp
index 375c00a6..04cd7357 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
@@ -17,142 +18,118 @@
along with this program. If not, see .
*/
+#include // For std::memset
+#include
+#include
-////
-//// Includes
-////
-
-#include
-#include
-
+#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
-////
-TranspositionTable::TranspositionTable() {
-
- size = 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.
+ clusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
-void TranspositionTable::set_size(size_t mbSize) {
+ free(mem);
+ mem = malloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1);
- size_t newSize = 1024;
-
- // Transposition table consists of clusters and
- // each cluster consists of ClusterSize number of TTEntries.
- // Each non-empty entry contains information of exactly one position.
- // newSize is the number of clusters we are going to allocate.
- while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20))
- newSize *= 2;
-
- 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);
}
-}
-
-/// 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 received?
-
-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 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.
+/// 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 existing 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) // Replacing first entry is default and already set before entering for-loop
- 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);
+
+ 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::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::probe(const Key key, bool& found) const {
-TTEntry* TranspositionTable::retrieve(const Key posKey) const {
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
- uint32_t posKey32 = posKey >> 32;
- TTEntry* tte = first_entry(posKey);
+ for (int i = 0; i < ClusterSize; ++i)
+ if (!tte[i].key16 || tte[i].key16 == key16)
+ {
+ if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+ tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
- for (int i = 0; i < ClusterSize; i++, tte++)
- if (tte->key() == posKey32)
- return tte;
+ return found = (bool)tte[i].key16, &tte[i];
+ }
- return NULL;
+ // 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::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.
+/// TranspositionTable::hashfull() returns an approximation of the hashtable
+/// occupation during a search. The hash is x permill full, as per UCI protocol.
-void TranspositionTable::new_search() {
- generation++;
+int TranspositionTable::hashfull() const {
+
+ int cnt = 0;
+ for (int i = 0; i < 1000 / ClusterSize; i++)
+ {
+ const TTEntry* tte = &table[i].entry[0];
+ for (int j = 0; j < ClusterSize; j++)
+ if ((tte[j].genBound8 & 0xFC) == generation8)
+ cnt++;
+ }
+ return cnt;
}