Avoid to calculate reduction for each move

[stockfish] / src / tt.h

diff --git a/src/tt.h b/src/tt.h
index c570761bdec0fd91120fe99a28b1b18f562c7bcc..5d0df726239cabb66cb13628ac3523e9fb676c9c 100644 (file)
--- a/src/tt.h
+++ b/src/tt.h
@@ -36,12 +36,12 @@
 
 /// The TTEntry class is the class of transposition table entries
 ///
-/// A TTEntry needs 128 bits to be stored
+/// A TTEntry needs 96 bits to be stored
 ///
-/// bit    0-63: key
-/// bit   64-95: data
-/// bit  96-111: value
-/// bit 112-127: depth
+/// bit  0-31: key
+/// bit 32-63: data
+/// bit 64-79: value
+/// bit 80-95: depth
 ///
 /// the 32 bits of the data field are so defined
 ///
@@ -54,11 +54,11 @@ class TTEntry {
 
 public:
   TTEntry() {}
-  TTEntry(Key k, Value v, ValueType t, Depth d, Move m, int generation)
+  TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation)
         : key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
           value_(int16_t(v)), depth_(int16_t(d)) {}
 
-  Key key() const { return key_; }
+  uint32_t key() const { return key_; }
   Depth depth() const { return Depth(depth_); }
   Move move() const { return Move(data & 0x1FFFF); }
   Value value() const { return Value(value_); }
@@ -66,13 +66,27 @@ public:
   int generation() const { return (data >> 23); }
 
 private:
-  Key key_;
+  uint32_t key_;
   uint32_t data;
   int16_t value_;
   int16_t depth_;
 };
 
-/// The transposition table class.  This is basically just a huge array
+
+/// This is the number of TTEntry slots for each position
+const int ClusterSize = 5;
+
+/// Each group of ClusterSize number of TTEntry form a TTCluster
+/// that is indexed by a single position key. Cluster is padded
+/// to a cache line size so to guarantee always aligned accesses.
+
+struct TTCluster {
+  TTEntry data[ClusterSize];
+  char cache_line_padding[64 - sizeof(TTEntry[ClusterSize])];
+};
+
+
+/// The transposition table class. This is basically just a huge array
 /// containing TTEntry objects, and a few methods for writing new entries
 /// and reading new ones.
 
@@ -85,16 +99,26 @@ public:
   void clear();
   void store(const Key posKey, Value v, ValueType type, Depth d, Move m);
   TTEntry* retrieve(const Key posKey) const;
+  void prefetch(const Key posKey) const;
   void new_search();
   void insert_pv(const Position& pos, Move pv[]);
+  void extract_pv(const Position& pos, Move pv[], const int PLY_MAX);
   int full() const;
 
 private:
   inline TTEntry* first_entry(const Key posKey) const;
 
-  unsigned size, writes;
-  TTEntry* entries;
+  // Be sure 'writes' is at least one cache line away
+  // from read only variables.
+  unsigned char pad_before[64 - sizeof(unsigned)];
+  unsigned writes; // heavy SMP read/write access here
+  unsigned char pad_after[64];
+
+  unsigned size;
+  TTCluster* entries;
   uint8_t generation;
 };
 
+extern TranspositionTable TT;
+
 #endif // !defined(TT_H_INCLUDED)