Re-add "Cache line aligned TT"

[stockfish] / src / tt.cpp

diff --git a/src/tt.cpp b/src/tt.cpp
index fa0d39de00db423202eab55e5d2e82d0f94ebd4a..271b98b74009eaf8f7e5e6601c5225c33a5be7f5 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
@@ -34,22 +34,24 @@ void TranspositionTable::set_size(size_t mbSize) {
 
   assert(msb((mbSize << 20) / sizeof(TTEntry)) < 32);
 
-  uint32_t size = 1 << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize]));
+  uint32_t size = ClusterSize << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize]));
 
-  if (clusterMask == size - 1)
+  if (hashMask == size - ClusterSize)
       return;
 
-  clusterMask = size - 1;
-  delete [] entries;
-  entries = new (std::nothrow) TTEntry[size * ClusterSize];
+  hashMask = size - ClusterSize;
+  free(mem);
+  mem = malloc(size * sizeof(TTEntry) + CACHE_LINE_SIZE - 1);
 
-  if (!entries)
+  if (!mem)
   {
       std::cerr << "Failed to allocate " << mbSize
                 << "MB for transposition table." << std::endl;
       exit(EXIT_FAILURE);
   }
 
+  // Align table start address to a cache line
+  for (char* c = (char*)mem; unsigned(table = (TTEntry*)(c)) % CACHE_LINE_SIZE; c++) {}
   clear(); // Operator new is not guaranteed to initialize memory to zero
 }
 
@@ -60,7 +62,7 @@ void TranspositionTable::set_size(size_t mbSize) {
 
 void TranspositionTable::clear() {
 
-  memset(entries, 0, (clusterMask + 1) * sizeof(TTEntry[ClusterSize]));
+  memset(table, 0, (hashMask + ClusterSize) * sizeof(TTEntry));
 }