Add struct destructors

Avoid explicitly freeing the objects.

Because d'tor involves file unmapping, some
care must be taken to avoid accidentaly destroy
the object (even temporarly), for instance when
reordering the list.

As a side effect, we can now restore the original
main.cpp, fully in sync with master branch.

src/main.cpp

@@ -41,13 +41,12 @@ int main(int argc, char* argv[]) {
   Search::init();
   Eval::init();
   Pawns::init();
+  Threads.init();
   Tablebases::init(Options["SyzygyPath"]);
   TT.resize(Options["Hash"]);
-  Threads.init();
 
   UCI::loop(argc, argv);
 
   Threads.exit();
-  Tablebases::free();
   return 0;
 }

src/syzygy/tbprobe.cpp

@@ -95,6 +95,8 @@ struct TBEntry {
         TBEntry_piece piece;
         TBEntry_pawn pawn;
     };
+
+    ~TBEntry();
 };
 
 struct DTZEntry_piece {
@@ -134,6 +136,8 @@ struct DTZEntry {
         DTZEntry_piece piece;
         DTZEntry_pawn pawn;
     };
+
+    ~DTZEntry();
 };
 
 const signed char OffdiagA1H8[] = {
@@ -468,6 +472,32 @@ public:
     }
 };
 
+TBEntry::~TBEntry()
+{
+    TBFile::unmap(data, mapping);
+
+    if (has_pawns)
+        for (File f = FILE_A; f <= FILE_D; ++f) {
+            free(pawn.file[f].precomp[0]);
+            free(pawn.file[f].precomp[1]);
+        }
+    else {
+        free(piece.precomp[0]);
+        free(piece.precomp[1]);
+    }
+}
+
+DTZEntry::~DTZEntry()
+{
+    TBFile::unmap(data, mapping);
+
+    if (has_pawns)
+        for (File f = FILE_A; f <= FILE_D; ++f)
+            free(pawn.file[f].precomp);
+    else
+        free(piece.precomp);
+}
+
 // Given a position with 6 or fewer pieces, produce a text string
 // of the form KQPvKRP, where "KQP" represents the white pieces if
 // mirror == false and the black pieces if mirror == true.
@@ -483,32 +513,6 @@ std::string file_name(const Position& pos, bool mirror)
     return mirror ? b + 'v' + w : w + 'v' + b;
 }
 
-void free_wdl_entry(TBEntry& entry)
-{
-    TBFile::unmap(entry.data, entry.mapping);
-
-    if (entry.has_pawns)
-        for (File f = FILE_A; f <= FILE_D; ++f) {
-            free(entry.pawn.file[f].precomp[0]);
-            free(entry.pawn.file[f].precomp[1]);
-        }
-    else {
-        free(entry.piece.precomp[0]);
-        free(entry.piece.precomp[1]);
-    }
-}
-
-void free_dtz_entry(DTZEntry& entry)
-{
-    TBFile::unmap(entry.data, entry.mapping);
-
-    if (entry.has_pawns)
-        for (File f = FILE_A; f <= FILE_D; ++f)
-            free(entry.pawn.file[f].precomp);
-    else
-        free(entry.piece.precomp);
-}
-
 void HashTable::insert(const std::vector<PieceType>& pieces)
 {
     StateInfo st;
@@ -1416,8 +1420,8 @@ int probe_dtz_table(const Position& pos, int wdl, int *success)
         // Enforce "Most Recently Used" (MRU) order for DTZ_list
         for (auto it = DTZ_list.begin(); it != DTZ_list.end(); ++it)
             if (it->keys[0] == key) {
-                DTZ_list.push_front(*it);
-                DTZ_list.erase(it);
+                // Move to front without deleting the element
+                DTZ_list.splice(DTZ_list.begin(),DTZ_list, it);
                 break;
             }
 
@@ -1470,10 +1474,7 @@ int probe_dtz_table(const Position& pos, int wdl, int *success)
             // Keep list size within 64 entries
             // FIXME remove it when we will know what we are doing
             if (DTZ_list.size() > 64)
-            {
-               free_dtz_entry(DTZ_list.back());
                DTZ_list.pop_back();
-            }
         }
     }
 
@@ -1881,24 +1882,13 @@ int probe_dtz(Position& pos, int *success)
 
 } // namespace
 
-void Tablebases::free()
+void Tablebases::init(const std::string& paths)
 {
-    for (auto& e : TB_entry)
-        free_wdl_entry(e);
-
-    for (auto& e : DTZ_list)
-        free_dtz_entry(e);
-
     DTZ_list.clear();
     TB_entry.clear();
     TBHash.clear();
 
     MaxCardinality = 0;
-}
-
-void Tablebases::init(const std::string& paths)
-{
-    Tablebases::free();
     TBPaths = paths;
 
     if (TBPaths.empty() || TBPaths == "<empty>")

src/syzygy/tbprobe.h

@@ -16,7 +16,6 @@ enum WDLScore {
 extern int MaxCardinality;
 
 void init(const std::string& paths);
-void free();
 WDLScore probe_wdl(Position& pos, int* success);
 bool root_probe(Position& pos, Search::RootMoves& rootMoves, Value& score);
 bool root_probe_wdl(Position& pos, Search::RootMoves& rootMoves, Value& score);