X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=e8a316c96b7ae5831cb32737ec0df38eb72300b8;hp=49dae31d70ffb5b634709e339c7815d8d5e5184d;hb=b89733b46c9267f61ac41c48204557483658435b;hpb=6f1475b6fcd3e3728d800e622ab7a22265fb8ca4

diff --git a/src/tt.cpp b/src/tt.cpp
index 49dae31d..e8a316c9 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2009 Marco Costalba
+  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, 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
@@ -25,14 +25,15 @@
 #include <cassert>
 #include <cmath>
 #include <cstring>
+#if defined(__i386__) || defined(_M_IX86) || defined(_X86_)
+#  include <xmmintrin.h>
+#endif
 
 #include "movegen.h"
 #include "tt.h"
 
-
-/// This is the number of TTEntry slots for each position
-static const int ClusterSize = 4;
-
+// The main transposition table
+TranspositionTable TT;
 
 ////
 //// Functions
@@ -54,22 +55,20 @@ TranspositionTable::~TranspositionTable() {
 /// TranspositionTable::set_size sets the size of the transposition table,
 /// measured in megabytes.
 
-void TranspositionTable::set_size(unsigned mbSize) {
-
-  assert(mbSize >= 4 && mbSize <= 4096);
+void TranspositionTable::set_size(size_t mbSize) {
 
-  unsigned newSize = 1024;
+  size_t newSize = 1024;
 
   // We store a cluster of ClusterSize number of TTEntry for each position
   // and newSize is the maximum number of storable positions.
-  while ((2 * newSize) * ClusterSize * (sizeof(TTEntry)) <= (mbSize << 20))
+  while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20))
       newSize *= 2;
 
   if (newSize != size)
   {
       size = newSize;
       delete [] entries;
-      entries = new TTEntry[size * ClusterSize];
+      entries = new TTCluster[size];
       if (!entries)
       {
           std::cerr << "Failed to allocate " << mbSize
@@ -88,7 +87,17 @@ void TranspositionTable::set_size(unsigned mbSize) {
 
 void TranspositionTable::clear() {
 
-  memset(entries, 0, size * ClusterSize * sizeof(TTEntry));
+  memset(entries, 0, size * sizeof(TTCluster));
+}
+
+
+/// TranspositionTable::first_entry returns a pointer to the first
+/// entry of a cluster given a position. The low 32 bits of the key
+/// are used to get the index in the table.
+
+inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
+
+  return entries[uint32_t(posKey) & (size - 1)].data;
 }
 
 
@@ -112,10 +121,7 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
   {
       if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
       {
-          // Do not overwrite when new type is VALUE_TYPE_EVAL
-          if (tte->key() && t == VALUE_TYPE_EVAL)
-              return;
-
+          // Preserve any exsisting ttMove
           if (m == MOVE_NONE)
               m = tte->move();
 
@@ -144,7 +150,7 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
 TTEntry* TranspositionTable::retrieve(const Key posKey) const {
 
   uint32_t posKey32 = posKey >> 32;
-  TTEntry *tte = first_entry(posKey);
+  TTEntry* tte = first_entry(posKey);
 
   for (int i = 0; i < ClusterSize; i++, tte++)
       if (tte->key() == posKey32)
@@ -154,15 +160,31 @@ TTEntry* TranspositionTable::retrieve(const Key posKey) const {
 }
 
 
-/// TranspositionTable::first_entry returns a pointer to the first
-/// entry of a cluster given a position. The low 32 bits of the key
-/// are used to get the index in the table.
+/// TranspositionTable::prefetch looks up the current position in the
+/// transposition table and load it in L1/L2 cache. This is a non
+/// blocking function and do not stalls the CPU waiting for data
+/// to be loaded from RAM, that can be very slow. When we will
+/// subsequently call retrieve() the TT data will be already
+/// quickly accessible in L1/L2 CPU cache.
+#if !(defined(__i386__) || defined(_M_IX86) || defined(_X86_))
+void TranspositionTable::prefetch(const Key) const {}
+#else
 
-inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
+void TranspositionTable::prefetch(const Key posKey) const {
+
+#if defined(__INTEL_COMPILER) || defined(__ICL)
+   // This hack prevents prefetches to be optimized away by
+   // Intel compiler. Both MSVC and gcc seems not affected.
+   __asm__ ("");
+#endif
 
-  return entries + ((uint32_t(posKey) & (size - 1)) * ClusterSize);
+   char const* addr = (char*)first_entry(posKey);
+  _mm_prefetch(addr, _MM_HINT_T2);
+  _mm_prefetch(addr+64, _MM_HINT_T2); // 64 bytes ahead
 }
 
+#endif
+
 /// 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
@@ -187,7 +209,9 @@ void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
 
   for (int i = 0; pv[i] != MOVE_NONE; i++)
   {
-      store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
+      TTEntry *tte = retrieve(p.get_key());
+      if (!tte || tte->move() != pv[i])
+          store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
       p.do_move(pv[i], st);
   }
 }
@@ -199,27 +223,26 @@ void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
 /// will often get single-move PVs when the search stops while failing high,
 /// and a single-move PV means that we don't have a ponder move.
 
-void TranspositionTable::extract_pv(const Position& pos, Move pv[]) {
-
-  int ply;
-  Position p(pos);
-  StateInfo st[100];
-
-  for (ply = 0; pv[ply] != MOVE_NONE; ply++)
-      p.do_move(pv[ply], st[ply]);
+void TranspositionTable::extract_pv(const Position& pos, Move pv[], const int PLY_MAX) {
 
-  bool stop;
   const TTEntry* tte;
-  for (stop = false, tte = retrieve(p.get_key());
-       tte && tte->move() != MOVE_NONE && !stop;
-       tte = retrieve(p.get_key()), ply++)
+  StateInfo st;
+  Position p(pos);
+  int ply = 0;
+
+  // Update position to the end of current PV
+  while (pv[ply] != MOVE_NONE)
+      p.do_move(pv[ply++], st);
+
+  // Try to add moves from TT while possible
+  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)
   {
-      if (!move_is_legal(p, tte->move()))
-          break;
       pv[ply] = tte->move();
-      p.do_move(pv[ply], st[ply]);
-      for (int j = 0; j < ply; j++)
-          if (st[j].key == p.get_key()) stop = true;
+      p.do_move(pv[ply++], st);
   }
   pv[ply] = MOVE_NONE;
 }