X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=151b71f58df6ac789a87ac200b543169a6fe5c6b;hp=11173e0a1243511e24618f82a4def19a67f925dd;hb=29b5842da8d5477c0aea924cfd364c9e619456a2;hpb=a71209868bdd8361d0607acf7725f70e9d1f2019
diff --git a/src/tt.cpp b/src/tt.cpp
index 11173e0a..151b71f5 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) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 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
@@ -17,7 +18,7 @@
along with this program. If not, see .
*/
-#include
+#include // For std::memset
#include
#include "bitboard.h"
@@ -26,22 +27,21 @@
TranspositionTable TT; // Our global transposition table
-/// TranspositionTable::set_size() sets the size of the transposition table,
+/// 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) {
- assert(msb((mbSize << 20) / sizeof(TTEntry)) < 32);
+ size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(Cluster));
- uint32_t size = ClusterSize << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize]));
-
- if (hashMask == size - ClusterSize)
+ if (newClusterCount == clusterCount)
return;
- hashMask = size - ClusterSize;
+ clusterCount = newClusterCount;
+
free(mem);
- mem = calloc(size * sizeof(TTEntry) + CACHE_LINE_SIZE - 1, 1);
+ mem = calloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1, 1);
if (!mem)
{
@@ -50,72 +50,68 @@ void TranspositionTable::set_size(size_t mbSize) {
exit(EXIT_FAILURE);
}
- table = (TTEntry*)((uintptr_t(mem) + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 1));
+ table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
}
/// TranspositionTable::clear() overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// 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).
void TranspositionTable::clear() {
- std::memset(table, 0, (hashMask + ClusterSize) * sizeof(TTEntry));
+ std::memset(table, 0, clusterCount * sizeof(Cluster));
}
-/// TranspositionTable::probe() looks up the current position in the
-/// transposition table. Returns a pointer to the TTEntry or NULL if
-/// position is not found.
+/// 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.
-const TTEntry* TranspositionTable::probe(const Key key) const {
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
- const TTEntry* tte = first_entry(key);
- uint32_t key32 = key >> 32;
-
- for (unsigned i = 0; i < ClusterSize; ++i, tte++)
- if (tte->key() == key32)
- return tte;
-
- return NULL;
-}
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
+ 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
-/// 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.
+ return found = (bool)tte[i].key16, &tte[i];
+ }
-void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m, Value statV, Value evalM) {
+ // 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 * ONE_PLY
+ > tte[i].depth8 - ((259 + generation8 - tte[i].genBound8) & 0xFC) * 2 * ONE_PLY)
+ replace = &tte[i];
+
+ return found = false, replace;
+}
- int c1, c2, c3;
- TTEntry *tte, *replace;
- uint32_t key32 = key >> 32; // Use the high 32 bits as key inside the cluster
- tte = replace = first_entry(key);
+/// Returns an approximation of the hashtable occupation during a search. The
+/// hash is x permill full, as per UCI protocol.
- for (unsigned i = 0; i < ClusterSize; ++i, tte++)
+int TranspositionTable::hashfull() const
+{
+ int cnt = 0;
+ for (int i = 0; i < 1000 / ClusterSize; i++)
{
- if (!tte->key() || tte->key() == key32) // Empty or overwrite old
- {
- if (!m)
- m = tte->move(); // Preserve any existing ttMove
-
- replace = tte;
- break;
- }
-
- // Implement replace strategy
- c1 = (replace->generation() == generation ? 2 : 0);
- c2 = (tte->generation() == generation || tte->bound() == BOUND_EXACT ? -2 : 0);
- c3 = (tte->depth() < replace->depth() ? 1 : 0);
-
- if (c1 + c2 + c3 > 0)
- replace = tte;
+ const TTEntry* tte = &table[i].entry[0];
+ for (int j = 0; j < ClusterSize; j++)
+ if ((tte[j].genBound8 & 0xFC) == generation8)
+ cnt++;
}
-
- replace->save(key32, v, b, d, m, generation, statV, evalM);
+ return cnt;
}