X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=d087cc38f77e2cad94feb67940ccc26c37f06189;hp=5ca5c237d82f7ec38974b56944b267c5c688a76b;hb=ca7d4e9ac7b5ca74be8aa807fbdf139b2a0860ab;hpb=0fcda095df1caa860e8e3f3a714d5545ec9dc122
diff --git a/src/tt.h b/src/tt.h
index 5ca5c237..d087cc38 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -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) 2015-2019 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
@@ -17,158 +18,86 @@
along with this program. If not, see .
*/
-#if !defined(TT_H_INCLUDED)
+#ifndef TT_H_INCLUDED
#define TT_H_INCLUDED
-#include
-
-#include "move.h"
+#include "misc.h"
#include "types.h"
-/// A simple fixed size hash table used to store pawns and material
-/// configurations. It is basically just an array of Entry objects.
-/// Without cluster concept or overwrite policy.
-
-template
-class SimpleHash {
-
- SimpleHash(const SimpleHash&);
- SimpleHash& operator=(const SimpleHash&);
-
-public:
- SimpleHash() {
-
- entries = new (std::nothrow) Entry[HashSize];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << HashSize * sizeof(Entry)
- << " bytes for material hash table." << std::endl;
- exit(EXIT_FAILURE);
- }
- memset(entries, 0, HashSize * sizeof(Entry));
- }
-
- virtual ~SimpleHash() { delete [] entries; }
-
- Entry* find(Key key) const { return entries + ((uint32_t)key & (HashSize - 1)); }
-
-protected:
- Entry* entries;
-};
-
-
-/// The TTEntry class is the class of transposition table entries
-///
-/// A TTEntry needs 128 bits to be stored
-///
-/// bit 0-31: key
-/// bit 32-63: data
-/// bit 64-79: value
-/// bit 80-95: depth
-/// bit 96-111: static value
-/// bit 112-127: margin of static value
-///
-/// the 32 bits of the data field are so defined
+/// TTEntry struct is the 10 bytes transposition table entry, defined as below:
///
-/// bit 0-15: move
-/// bit 16-20: not used
-/// bit 21-22: value type
-/// bit 23-31: generation
-
-class TTEntry {
-
-public:
- void save(uint32_t k, Value v, ValueType t, Depth d, Move m, int g, Value statV, Value statM) {
-
- key32 = (uint32_t)k;
- move16 = (uint16_t)m;
- valueType = (uint8_t)t;
- generation8 = (uint8_t)g;
- value16 = (int16_t)v;
- depth16 = (int16_t)d;
- staticValue = (int16_t)statV;
- staticMargin = (int16_t)statM;
- }
- void set_generation(int g) { generation8 = (uint8_t)g; }
-
- uint32_t key() const { return key32; }
- Depth depth() const { return Depth(depth16); }
- Move move() const { return Move(move16); }
- Value value() const { return Value(value16); }
- ValueType type() const { return ValueType(valueType); }
- int generation() const { return generation8; }
- Value static_value() const { return Value(staticValue); }
- Value static_value_margin() const { return Value(staticMargin); }
+/// key 16 bit
+/// move 16 bit
+/// value 16 bit
+/// eval value 16 bit
+/// generation 5 bit
+/// pv node 1 bit
+/// bound type 2 bit
+/// depth 8 bit
+
+struct TTEntry {
+
+ Move move() const { return (Move )move16; }
+ Value value() const { return (Value)value16; }
+ Value eval() const { return (Value)eval16; }
+ Depth depth() const { return (Depth)depth8 + DEPTH_OFFSET; }
+ bool is_pv() const { return (bool)(genBound8 & 0x4); }
+ Bound bound() const { return (Bound)(genBound8 & 0x3); }
+ void save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev);
private:
- uint32_t key32;
+ friend class TranspositionTable;
+
+ uint16_t key16;
uint16_t move16;
- uint8_t valueType;
- uint8_t generation8;
- int16_t value16;
- int16_t depth16;
- int16_t staticValue;
- int16_t staticMargin;
+ int16_t value16;
+ int16_t eval16;
+ uint8_t genBound8;
+ uint8_t depth8;
};
-/// This is the number of TTEntry slots for each cluster
-const int ClusterSize = 4;
-
-/// TTCluster consists of ClusterSize number of TTEntries.
-/// Size of TTCluster must not be bigger than a cache line size.
-/// In case it is less, it should be padded to guarantee always aligned accesses.
-
-struct TTCluster {
- TTEntry data[ClusterSize];
-};
+/// A TranspositionTable consists of a power of 2 number of clusters and each
+/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
+/// contains information of exactly one position. The size of a cluster should
+/// divide the size of a cache line size, to ensure that clusters never cross
+/// cache lines. This ensures best cache performance, as the cacheline is
+/// prefetched, as soon as possible.
+class TranspositionTable {
-/// The transposition table class. This is basically just a huge array
-/// containing TTCluster objects, and a few methods for writing new entries
-/// and reading new ones.
+ static constexpr int CacheLineSize = 64;
+ static constexpr int ClusterSize = 3;
-class TranspositionTable {
+ struct Cluster {
+ TTEntry entry[ClusterSize];
+ char padding[2]; // Align to a divisor of the cache line size
+ };
- TranspositionTable(const TranspositionTable&);
- TranspositionTable& operator=(const TranspositionTable&);
+ static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
public:
- TranspositionTable();
- ~TranspositionTable();
- void set_size(size_t mbSize);
+ ~TranspositionTable() { free(mem); }
+ void new_search() { generation8 += 8; } // Lower 3 bits are used by PV flag and Bound
+ TTEntry* probe(const Key key, bool& found) const;
+ int hashfull() const;
+ void resize(size_t mbSize);
void clear();
- void store(const Key posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD);
- TTEntry* retrieve(const Key posKey) const;
- void new_search();
- TTEntry* first_entry(const Key posKey) const;
- void refresh(const TTEntry* tte) const;
+
+ // The 32 lowest order bits of the key are used to get the index of the cluster
+ TTEntry* first_entry(const Key key) const {
+ return &table[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
+ }
private:
- size_t size;
- TTCluster* entries;
- uint8_t generation; // To properly compare, size must be smaller then TT stored value
+ friend struct TTEntry;
+
+ size_t clusterCount;
+ Cluster* table;
+ void* mem;
+ uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
};
extern TranspositionTable TT;
-
-/// TranspositionTable::first_entry returns a pointer to the first
-/// entry of a cluster given a position. The lowest order bits of the key
-/// are used to get the index of the cluster.
-
-inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
-
- return entries[((uint32_t)posKey) & (size - 1)].data;
-}
-
-
-/// TranspositionTable::refresh updates the 'generation' value of the TTEntry
-/// to avoid aging. Normally called after a TT hit, before to return.
-
-inline void TranspositionTable::refresh(const TTEntry* tte) const {
-
- const_cast(tte)->set_generation(generation);
-}
-
-#endif // !defined(TT_H_INCLUDED)
+#endif // #ifndef TT_H_INCLUDED