Cache line aligned TT

[stockfish] / src / tt.cpp

diff --git a/src/tt.cpp b/src/tt.cpp
index 2445f79420692c870922e7c88e77906af3ff0144..998d73783be003e8deb2567695e51527a7657bf3 100644 (file)
--- 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) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2013 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
@@ -32,23 +32,25 @@ TranspositionTable TT; // Our global transposition table
 
 void TranspositionTable::set_size(size_t mbSize) {
 
-  size_t newSize = 1ULL << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize]));
+  assert(msb((mbSize << 20) / sizeof(TTEntry)) < 32);
 
-  if (newSize == size)
-      return;
+  uint32_t size = ClusterSize << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize]));
 
-  size = newSize;
-  delete [] entries;
-  entries = new (std::nothrow) TTEntry[size * ClusterSize];
+  if (hashMask == size - ClusterSize)
+      return;
 
-  if (!entries)
+  free(mem);
+  mem = malloc(size * sizeof(TTEntry) + (CACHE_LINE_SIZE - 1));
+  if (!mem)
   {
       std::cerr << "Failed to allocate " << mbSize
                 << "MB for transposition table." << std::endl;
       exit(EXIT_FAILURE);
   }
 
-  clear(); // Operator new is not guaranteed to initialize memory to zero
+  table = (TTEntry*)((size_t(mem) + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 1));
+  hashMask = size - ClusterSize;
+  clear(); // Newly allocated block of memory is not initialized
 }
 
 
@@ -58,7 +60,7 @@ void TranspositionTable::set_size(size_t mbSize) {
 
 void TranspositionTable::clear() {
 
-  memset(entries, 0, size * sizeof(TTEntry[ClusterSize]));
+  memset(table, 0, (hashMask + ClusterSize) * sizeof(TTEntry));
 }