X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=cb5af5c85905620a1537d06a7339ce6bca17176f;hp=26791809f8890bb6aed2e492838b9a9473b2aaf2;hb=573f0e364ff4c1e5928be2ca947f65c5d4e177d5;hpb=e7cfa5d020efb5a0ad2521afc7b886f3b2d3e6b3

diff --git a/src/tt.cpp b/src/tt.cpp
index 26791809..cb5af5c8 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,30 +22,34 @@
 
 #include "bitboard.h"
 #include "misc.h"
+#include "thread.h"
 #include "tt.h"
 #include "uci.h"
 
 TranspositionTable TT; // Our global transposition table
 
-/// TTEntry::save saves a TTEntry
-void TTEntry::save(Key k, Value v, Bound b, Depth d, Move m, Value ev) {
+/// TTEntry::save() populates the TTEntry with a new node's data, possibly
+/// overwriting an old position. Update is not atomic and can be racy.
 
-  assert(d / ONE_PLY * ONE_PLY == d);
+void TTEntry::save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev) {
 
   // Preserve any existing move for the same position
-  if (m || (k >> 48) != key16)
+  if (m || (uint16_t)k != key16)
       move16 = (uint16_t)m;
 
-  // Overwrite less valuable entries
-  if (  (k >> 48) != key16
-      || d / ONE_PLY > depth8 - 4
-      || b == BOUND_EXACT)
+  // Overwrite less valuable entries (cheapest checks first)
+  if (b == BOUND_EXACT
+      || (uint16_t)k != key16
+      || d - DEPTH_OFFSET > depth8 - 4)
   {
-      key16     = (uint16_t)(k >> 48);
+      assert(d > DEPTH_OFFSET);
+      assert(d < 256 + DEPTH_OFFSET);
+
+      key16     = (uint16_t)k;
+      depth8    = (uint8_t)(d - DEPTH_OFFSET);
+      genBound8 = (uint8_t)(TT.generation8 | uint8_t(pv) << 2 | b);
       value16   = (int16_t)v;
       eval16    = (int16_t)ev;
-      genBound8 = (uint8_t)(TT.generation8 | b);
-      depth8    = (int8_t)(d / ONE_PLY);
   }
 }
 
@@ -58,19 +60,20 @@ void TTEntry::save(Key k, Value v, Bound b, Depth d, Move m, Value ev) {
 
 void TranspositionTable::resize(size_t mbSize) {
 
-  clusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
+  Threads.main()->wait_for_search_finished();
 
-  free(mem);
-  mem = malloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1);
+  aligned_large_pages_free(table);
+
+  clusterCount = mbSize * 1024 * 1024 / sizeof(Cluster);
 
-  if (!mem)
+  table = static_cast<Cluster*>(aligned_large_pages_alloc(clusterCount * sizeof(Cluster)));
+  if (!table)
   {
       std::cerr << "Failed to allocate " << mbSize
                 << "MB for transposition table." << std::endl;
       exit(EXIT_FAILURE);
   }
 
-  table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
   clear();
 }
 
@@ -82,28 +85,29 @@ void TranspositionTable::clear() {
 
   std::vector<std::thread> threads;
 
-  for (size_t idx = 0; idx < Options["Threads"]; idx++)
+  for (size_t idx = 0; idx < Options["Threads"]; ++idx)
   {
-      threads.push_back(std::thread([this, idx]() {
+      threads.emplace_back([this, idx]() {
 
           // Thread binding gives faster search on systems with a first-touch policy
-          if (Options["Threads"] >= 8)
+          if (Options["Threads"] > 8)
               WinProcGroup::bindThisThread(idx);
 
           // Each thread will zero its part of the hash table
-          const size_t stride = clusterCount / Options["Threads"],
-                       start  = stride * idx,
+          const size_t stride = size_t(clusterCount / Options["Threads"]),
+                       start  = size_t(stride * idx),
                        len    = idx != Options["Threads"] - 1 ?
                                 stride : clusterCount - start;
 
           std::memset(&table[start], 0, len * sizeof(Cluster));
-      }));
+      });
   }
 
-  for (std::thread& th: threads)
+  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
@@ -114,26 +118,26 @@ void TranspositionTable::clear() {
 TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
   TTEntry* const tte = first_entry(key);
-  const uint16_t key16 = key >> 48;  // Use the high 16 bits as key inside the cluster
+  const uint16_t key16 = (uint16_t)key;  // Use the low 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].key16 == key16 || !tte[i].depth8)
       {
-          if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
-              tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
+          tte[i].genBound8 = uint8_t(generation8 | (tte[i].genBound8 & (GENERATION_DELTA - 1))); // Refresh
 
-          return found = (bool)tte[i].key16, &tte[i];
+          return found = (bool)tte[i].depth8, &tte[i];
       }
 
   // 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)
+      // nature we add GENERATION_CYCLE (256 is the modulus, plus what
+      // is needed to keep the unrelated lowest n bits from affecting
+      // the result) to calculate the entry age correctly even after
+      // generation8 overflows into the next cycle.
+      if (  replace->depth8 - ((GENERATION_CYCLE + generation8 - replace->genBound8) & GENERATION_MASK)
+          >   tte[i].depth8 - ((GENERATION_CYCLE + generation8 -   tte[i].genBound8) & GENERATION_MASK))
           replace = &tte[i];
 
   return found = false, replace;
@@ -146,12 +150,9 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 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;
+  for (int i = 0; i < 1000; ++i)
+      for (int j = 0; j < ClusterSize; ++j)
+          cnt += table[i].entry[j].depth8 && (table[i].entry[j].genBound8 & GENERATION_MASK) == generation8;
+
+  return cnt / ClusterSize;
 }