Revert "Another PSQT tuning round"

At longer TC of 1'+0" patch fails:
Orig - Mod: 841 - 819 (-6 elo!)

Just before the release ;-)

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/evaluate.cpp

@@ -207,7 +207,6 @@ namespace {
 
   // Bonuses for enemy's safe checks
   const int QueenContactCheckBonus = 3;
-  const int DiscoveredCheckBonus   = 3;
   const int QueenCheckBonus        = 2;
   const int RookCheckBonus         = 1;
   const int BishopCheckBonus       = 1;
@@ -862,8 +861,7 @@ namespace {
         // value if the other side has a rook or queen.
         if (square_file(s) == FILE_A || square_file(s) == FILE_H)
         {
-            if (   pos.non_pawn_material(Them) <= KnightValueMidgame
-                && pos.piece_count(Them, KNIGHT) <= 1)
+            if (pos.non_pawn_material(Them) <= KnightValueMidgame)
                 ebonus += ebonus / 4;
             else if (pos.pieces(ROOK, QUEEN, Them))
                 ebonus -= ebonus / 4;

src/misc.cpp

@@ -58,7 +58,7 @@ using namespace std;
 /// Version number. If this is left empty, the current date (in the format
 /// YYMMDD) is used as a version number.
 
-static const string EngineVersion = "1.8 beta 2";
+static const string EngineVersion = "1.8";
 static const string AppName = "Stockfish";
 static const string AppTag  = "";
 

src/position.cpp

@@ -641,10 +641,10 @@ bool Position::move_is_check(Move m, const CheckInfo& ci) const {
       }
   }
 
-  // En passant capture with check?  We have already handled the case
+  // En passant capture with check ? We have already handled the case
   // of direct checks and ordinary discovered check, the only case we
-  // need to handle is the unusual case of a discovered check through the
-  // captured pawn.
+  // need to handle is the unusual case of a discovered check through
+  // the captured pawn.
   if (move_is_ep(m))
   {
       Square capsq = make_square(square_file(to), square_rank(from));

src/position.h

@@ -68,7 +68,7 @@ const int MaxGameLength = 220;
 
 struct CheckInfo {
 
-    CheckInfo(const Position&);
+    explicit CheckInfo(const Position&);
 
     Bitboard dcCandidates;
     Bitboard checkSq[8];

src/san.cpp

@@ -47,7 +47,7 @@ namespace {
     AMBIGUITY_BOTH
   };
 
-  const History H; // used as dummy argument for MovePicker c'tor
+  const History H; // Used as dummy argument for MovePicker c'tor
 
   Ambiguity move_ambiguity(const Position& pos, Move m);
   const string time_string(int milliseconds);
@@ -68,28 +68,25 @@ const string move_to_san(Position& pos, Move m) {
   assert(pos.is_ok());
   assert(move_is_ok(m));
 
-  Square from, to;
-  PieceType pt;
-
-  from = move_from(m);
-  to = move_to(m);
-  pt = type_of_piece(pos.piece_on(move_from(m)));
-
-  string san = "";
+  string san;
+  Square from = move_from(m);
+  Square to = move_to(m);
+  PieceType pt = type_of_piece(pos.piece_on(move_from(m)));
 
   if (m == MOVE_NONE)
       return "(none)";
   else if (m == MOVE_NULL)
       return "(null)";
-  else if (move_is_long_castle(m) || (int(to - from) == -2 && pt == KING))
+  else if (move_is_long_castle(m)  || (int(to - from) == -2 && pt == KING))
       san = "O-O-O";
-  else if (move_is_short_castle(m) || (int(to - from) == 2 && pt == KING))
+  else if (move_is_short_castle(m) || (int(to - from) ==  2 && pt == KING))
       san = "O-O";
   else
   {
       if (pt != PAWN)
       {
           san += piece_type_to_char(pt, true);
+
           switch (move_ambiguity(pos, m)) {
           case AMBIGUITY_NONE:
             break;
@@ -115,13 +112,13 @@ const string move_to_san(Position& pos, Move m) {
       san += square_to_string(move_to(m));
       if (move_is_promotion(m))
       {
-          san += '=';
+          san += "=";
           san += piece_type_to_char(move_promotion_piece(m), true);
       }
   }
-  // Is the move check?  We don't use pos.move_is_check(m) here, because
-  // Position::move_is_check doesn't detect all checks (not castling moves,
-  // promotions and en passant captures).
+
+  // The move gives check ? We don't use pos.move_is_check() here
+  // because we need to test for mate after the move is done.
   StateInfo st;
   pos.do_move(m, st);
   if (pos.is_check())
@@ -301,21 +298,21 @@ const string line_to_san(const Position& pos, Move line[], int startColumn, bool
   size_t maxLength = 80 - startColumn;
   Position p(pos, pos.thread());
 
-  for (int i = 0; line[i] != MOVE_NONE; i++)
+  for (Move* m = line; *m != MOVE_NONE; m++)
   {
-      moveStr = move_to_san(p, line[i]);
+      moveStr = move_to_san(p, *m);
       length += moveStr.length() + 1;
       if (breakLines && length > maxLength)
       {
-          s << '\n' << std::setw(startColumn) << ' ';
+          s << "\n" << std::setw(startColumn) << " ";
           length = moveStr.length() + 1;
       }
       s << moveStr << ' ';
 
-      if (line[i] == MOVE_NULL)
+      if (*m == MOVE_NULL)
           p.do_null_move(st);
       else
-          p.do_move(line[i], st);
+          p.do_move(*m, st);
   }
   return s.str();
 }
@@ -325,27 +322,31 @@ const string line_to_san(const Position& pos, Move line[], int startColumn, bool
 /// It is used to write search information to the log file (which is created
 /// when the UCI parameter "Use Search Log" is "true").
 
-const string pretty_pv(const Position& pos, int time, int depth,
-                       uint64_t nodes, Value score, ValueType type, Move pv[]) {
+const string pretty_pv(const Position& pos, int time, int depth, uint64_t nodes,
+                       Value score, ValueType type, Move pv[]) {
+
+  const uint64_t K = 1000;
+  const uint64_t M = 1000000;
+
   std::stringstream s;
 
   // Depth
   s << std::setw(2) << depth << "  ";
 
   // Score
-  s << ((type == VALUE_TYPE_LOWER)? ">" : ((type == VALUE_TYPE_UPPER)? "<" : " "));
-  s << std::setw(7) << score_string(score);
+  s << (type == VALUE_TYPE_LOWER ? ">" : type == VALUE_TYPE_UPPER ? "<" : " ")
+    << std::setw(7) << score_string(score);
 
   // Time
   s << std::setw(8) << time_string(time) << " ";
 
   // Nodes
-  if (nodes < 1000000ULL)
-    s << std::setw(8) << nodes << " ";
-  else if (nodes < 1000000000ULL)
-    s << std::setw(7) << nodes/1000ULL << 'k' << " ";
+  if (nodes < M)
+      s << std::setw(8) << nodes / 1 << " ";
+  else if (nodes < K * M)
+      s << std::setw(7) << nodes / K << "K ";
   else
-    s << std::setw(7) << nodes/1000000ULL << 'M' << " ";
+      s << std::setw(7) << nodes / M << "M ";
 
   // PV
   s << line_to_san(pos, pv, 30, true);
@@ -398,14 +399,17 @@ namespace {
   }
 
 
-  const string time_string(int milliseconds) {
+  const string time_string(int millisecs) {
+
+    const int MSecMinute = 1000 * 60;
+    const int MSecHour   = 1000 * 60 * 60;
 
     std::stringstream s;
     s << std::setfill('0');
 
-    int hours = milliseconds / (1000*60*60);
-    int minutes = (milliseconds - hours*1000*60*60) / (1000*60);
-    int seconds = (milliseconds - hours*1000*60*60 - minutes*1000*60) / 1000;
+    int hours = millisecs / MSecHour;
+    int minutes = (millisecs - hours * MSecHour) / MSecMinute;
+    int seconds = (millisecs - hours * MSecHour - minutes * MSecMinute) / 1000;
 
     if (hours)
         s << hours << ':';
@@ -421,7 +425,7 @@ namespace {
 
     if (v >= VALUE_MATE - 200)
         s << "#" << (VALUE_MATE - v + 1) / 2;
-    else if(v <= -VALUE_MATE + 200)
+    else if (v <= -VALUE_MATE + 200)
         s << "-#" << (VALUE_MATE + v) / 2;
     else
     {

src/search.cpp

@@ -282,7 +282,7 @@ namespace {
   /// Local functions
 
   Value id_loop(const Position& pos, Move searchMoves[]);
-  Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
+  Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
 
   template <NodeType PvNode>
   Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply);
@@ -296,8 +296,6 @@ namespace {
   template <NodeType PvNode>
   Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous);
 
-  void update_pv(SearchStack* ss);
-  void sp_update_pv(SearchStack* pss, SearchStack* ss);
   bool connected_moves(const Position& pos, Move m1, Move m2);
   bool value_is_mate(Value value);
   bool move_is_killer(Move m, SearchStack* ss);
@@ -314,7 +312,7 @@ namespace {
   void ponderhit();
   void wait_for_stop_or_ponderhit();
   void init_ss_array(SearchStack* ss, int size);
-  void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value);
+  void print_pv_info(const Position& pos, Move pv[], Value alpha, Value beta, Value value);
 
 #if !defined(_MSC_VER)
   void *init_thread(void *threadID);
@@ -364,16 +362,16 @@ void init_search() {
 }
 
 
-// SearchStack::init() initializes a search stack. Used at the beginning of a
-// new search from the root.
+// SearchStack::init() initializes a search stack entry.
+// Called at the beginning of search() when starting to examine a new node.
 void SearchStack::init() {
 
-  pv[0] = pv[1] = MOVE_NONE;
-  currentMove = threatMove = MOVE_NONE;
+  currentMove = threatMove = bestMove = MOVE_NONE;
   reduction = Depth(0);
   eval = VALUE_NONE;
 }
 
+// SearchStack::initKillers() initializes killers for a search stack entry
 void SearchStack::initKillers() {
 
   mateKiller = MOVE_NONE;
@@ -605,6 +603,7 @@ namespace {
 
     Position p(pos, pos.thread());
     SearchStack ss[PLY_MAX_PLUS_2];
+    Move pv[PLY_MAX_PLUS_2];
     Move EasyMove = MOVE_NONE;
     Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
 
@@ -634,6 +633,7 @@ namespace {
     TT.new_search();
     H.clear();
     init_ss_array(ss, PLY_MAX_PLUS_2);
+    pv[0] = pv[1] = MOVE_NONE;
     ValueByIteration[1] = rml.get_move_score(0);
     Iteration = 1;
 
@@ -665,11 +665,11 @@ namespace {
         }
 
         // Search to the current depth, rml is updated and sorted, alpha and beta could change
-        value = root_search(p, ss, rml, &alpha, &beta);
+        value = root_search(p, ss, pv, rml, &alpha, &beta);
 
         // Write PV to transposition table, in case the relevant entries have
         // been overwritten during the search.
-        TT.insert_pv(p, ss->pv);
+        TT.insert_pv(p, pv);
 
         if (AbortSearch)
             break; // Value cannot be trusted. Break out immediately!
@@ -678,7 +678,7 @@ namespace {
         ValueByIteration[Iteration] = value;
 
         // Drop the easy move if differs from the new best move
-        if (ss->pv[0] != EasyMove)
+        if (pv[0] != EasyMove)
             EasyMove = MOVE_NONE;
 
         if (UseTimeManagement)
@@ -700,7 +700,7 @@ namespace {
             // Stop search early if one move seems to be much better than the others
             int64_t nodes = TM.nodes_searched();
             if (   Iteration >= 8
-                && EasyMove == ss->pv[0]
+                && EasyMove == pv[0]
                 && (  (   rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
                        && current_search_time() > MaxSearchTime / 16)
                     ||(   rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100
@@ -743,18 +743,18 @@ namespace {
              << " hashfull " << TT.full() << endl;
 
     // Print the best move and the ponder move to the standard output
-    if (ss->pv[0] == MOVE_NONE)
+    if (pv[0] == MOVE_NONE)
     {
-        ss->pv[0] = rml.get_move(0);
-        ss->pv[1] = MOVE_NONE;
+        pv[0] = rml.get_move(0);
+        pv[1] = MOVE_NONE;
     }
 
-    assert(ss->pv[0] != MOVE_NONE);
+    assert(pv[0] != MOVE_NONE);
 
-    cout << "bestmove " << ss->pv[0];
+    cout << "bestmove " << pv[0];
 
-    if (ss->pv[1] != MOVE_NONE)
-        cout << " ponder " << ss->pv[1];
+    if (pv[1] != MOVE_NONE)
+        cout << " ponder " << pv[1];
 
     cout << endl;
 
@@ -768,12 +768,12 @@ namespace {
 
         LogFile << "\nNodes: " << TM.nodes_searched()
                 << "\nNodes/second: " << nps()
-                << "\nBest move: " << move_to_san(p, ss->pv[0]);
+                << "\nBest move: " << move_to_san(p, pv[0]);
 
         StateInfo st;
-        p.do_move(ss->pv[0], st);
+        p.do_move(pv[0], st);
         LogFile << "\nPonder move: "
-                << move_to_san(p, ss->pv[1]) // Works also with MOVE_NONE
+                << move_to_san(p, pv[1]) // Works also with MOVE_NONE
                 << endl;
     }
     return rml.get_move_score(0);
@@ -785,7 +785,7 @@ namespace {
   // scheme, prints some information to the standard output and handles
   // the fail low/high loops.
 
-  Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
+  Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
 
     EvalInfo ei;
     StateInfo st;
@@ -935,12 +935,12 @@ namespace {
                 // We are failing high and going to do a research. It's important to update
                 // the score before research in case we run out of time while researching.
                 rml.set_move_score(i, value);
-                update_pv(ss);
-                TT.extract_pv(pos, ss->pv, PLY_MAX);
-                rml.set_move_pv(i, ss->pv);
+                ss->bestMove = move;
+                TT.extract_pv(pos, move, pv, PLY_MAX);
+                rml.set_move_pv(i, pv);
 
                 // Print information to the standard output
-                print_pv_info(pos, ss, alpha, beta, value);
+                print_pv_info(pos, pv, alpha, beta, value);
 
                 // Prepare for a research after a fail high, each time with a wider window
                 *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE);
@@ -975,9 +975,9 @@ namespace {
 
                 // Update PV
                 rml.set_move_score(i, value);
-                update_pv(ss);
-                TT.extract_pv(pos, ss->pv, PLY_MAX);
-                rml.set_move_pv(i, ss->pv);
+                ss->bestMove = move;
+                TT.extract_pv(pos, move, pv, PLY_MAX);
+                rml.set_move_pv(i, pv);
 
                 if (MultiPV == 1)
                 {
@@ -988,7 +988,7 @@ namespace {
                         BestMoveChangesByIteration[Iteration]++;
 
                     // Print information to the standard output
-                    print_pv_info(pos, ss, alpha, beta, value);
+                    print_pv_info(pos, pv, alpha, beta, value);
 
                     // Raise alpha to setup proper non-pv search upper bound
                     if (value > alpha)
@@ -1061,7 +1061,7 @@ namespace {
     Depth ext, newDepth;
     Value bestValue, value, oldAlpha;
     Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific
-    bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
+    bool isCheck, singleEvasion, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous;
     bool mateThreat = false;
     int moveCount = 0;
     int threadID = pos.thread();
@@ -1246,7 +1246,7 @@ namespace {
         search<PvNode>(pos, ss, alpha, beta, d, ply);
         ss->skipNullMove = false;
 
-        ttMove = ss->pv[0];
+        ttMove = ss->bestMove;
         tte = TT.retrieve(posKey);
     }
 
@@ -1257,11 +1257,12 @@ namespace {
     // Initialize a MovePicker object for the current position
     MovePicker mp = MovePicker(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta));
     CheckInfo ci(pos);
-    bool singularExtensionNode =   depth >= SingularExtensionDepth[PvNode]
-                                && tte && tte->move()
-                                && !excludedMove // Do not allow recursive singular extension search
-                                && is_lower_bound(tte->type())
-                                && tte->depth() >= depth - 3 * OnePly;
+    singleEvasion = isCheck && mp.number_of_evasions() == 1;
+    singularExtensionNode =   depth >= SingularExtensionDepth[PvNode]
+                           && tte && tte->move()
+                           && !excludedMove // Do not allow recursive singular extension search
+                           && is_lower_bound(tte->type())
+                           && tte->depth() >= depth - 3 * OnePly;
 
     // Step 10. Loop through moves
     // Loop through all legal moves until no moves remain or a beta cutoff occurs
@@ -1274,7 +1275,6 @@ namespace {
       if (move == excludedMove)
           continue;
 
-      singleEvasion = (isCheck && mp.number_of_evasions() == 1);
       moveIsCheck = pos.move_is_check(move, ci);
       captureOrPromotion = pos.move_is_capture_or_promotion(move);
 
@@ -1410,10 +1410,10 @@ namespace {
               if (PvNode && value < beta) // This guarantees that always: alpha < beta
                   alpha = value;
 
-              update_pv(ss);
-
               if (value == value_mate_in(ply + 1))
                   ss->mateKiller = move;
+
+              ss->bestMove = move;
           }
       }
 
@@ -1442,22 +1442,20 @@ namespace {
     if (AbortSearch || TM.thread_should_stop(threadID))
         return bestValue;
 
-    if (bestValue <= oldAlpha)
-        TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
+    ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
+    move = (bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove);
+    TT.store(posKey, value_to_tt(bestValue, ply), f, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
 
-    else if (bestValue >= beta)
+    // Update killers and history only for non capture moves that fails high
+    if (bestValue >= beta)
     {
         TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
-        move = ss->pv[0];
-        TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
         if (!pos.move_is_capture_or_promotion(move))
         {
             update_history(pos, move, depth, movesSearched, moveCount);
             update_killers(move, ss);
         }
     }
-    else
-        TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]);
 
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
@@ -1488,7 +1486,7 @@ namespace {
     Value oldAlpha = alpha;
 
     TM.incrementNodeCounter(pos.thread());
-    ss->pv[0] = ss->pv[1] = ss->currentMove = MOVE_NONE;
+    ss->bestMove = ss->currentMove = MOVE_NONE;
     ss->eval = VALUE_NONE;
 
     // Check for an instant draw or maximum ply reached
@@ -1615,7 +1613,7 @@ namespace {
           if (value > alpha)
           {
               alpha = value;
-              update_pv(ss);
+              ss->bestMove = move;
           }
        }
     }
@@ -1627,19 +1625,13 @@ namespace {
 
     // Update transposition table
     Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
-    if (bestValue <= oldAlpha)
-        TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
-    else if (bestValue >= beta)
-    {
-        move = ss->pv[0];
-        TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
+    ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
+    TT.store(pos.get_key(), value_to_tt(bestValue, ply), f, d, ss->bestMove, ss->eval, ei.kingDanger[pos.side_to_move()]);
 
-        // Update killers only for good checking moves
-        if (!pos.move_is_capture_or_promotion(move))
-            update_killers(move, ss);
-    }
-    else
-        TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]);
+    // Update killers only for checking moves that fails high
+    if (    bestValue >= beta
+        && !pos.move_is_capture_or_promotion(ss->bestMove))
+        update_killers(ss->bestMove, ss);
 
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
@@ -1802,7 +1794,7 @@ namespace {
               if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta
                   sp->alpha = value;
 
-              sp_update_pv(sp->parentSstack, ss);
+              sp->parentSstack->bestMove = ss->bestMove = move;
           }
       }
     }
@@ -1814,40 +1806,6 @@ namespace {
     lock_release(&(sp->lock));
   }
 
-  // update_pv() is called whenever a search returns a value > alpha.
-  // It updates the PV in the SearchStack object corresponding to the
-  // current node.
-
-  void update_pv(SearchStack* ss) {
-
-    Move* src = (ss+1)->pv;
-    Move* dst = ss->pv;
-
-    *dst = ss->currentMove;
-
-    do
-        *++dst = *src;
-    while (*src++ != MOVE_NONE);
-  }
-
-
-  // sp_update_pv() is a variant of update_pv for use at split points. The
-  // difference between the two functions is that sp_update_pv also updates
-  // the PV at the parent node.
-
-  void sp_update_pv(SearchStack* pss, SearchStack* ss) {
-
-    Move* src = (ss+1)->pv;
-    Move* dst = ss->pv;
-    Move* pdst = pss->pv;
-
-    *dst = *pdst = ss->currentMove;
-
-    do
-        *++dst = *++pdst = *src;
-    while (*src++ != MOVE_NONE);
-  }
-
 
   // connected_moves() tests whether two moves are 'connected' in the sense
   // that the first move somehow made the second move possible (for instance
@@ -1948,7 +1906,7 @@ namespace {
 
     if (*dangerous)
     {
-        if (moveIsCheck && pos.see_sign(m)>= 0)
+        if (moveIsCheck && pos.see_sign(m) >= 0)
             result += CheckExtension[PvNode];
 
         if (singleEvasion)
@@ -2287,29 +2245,28 @@ namespace {
   // print_pv_info() prints to standard output and eventually to log file information on
   // the current PV line. It is called at each iteration or after a new pv is found.
 
-  void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value) {
+  void print_pv_info(const Position& pos, Move pv[], Value alpha, Value beta, Value value) {
 
     cout << "info depth " << Iteration
-         << " score " << value_to_string(value)
-         << ((value >= beta) ? " lowerbound" :
-            ((value <= alpha)? " upperbound" : ""))
+         << " score "     << value_to_string(value)
+         << (value >= beta ? " lowerbound" : value <= alpha ? " upperbound" : "")
          << " time "  << current_search_time()
          << " nodes " << TM.nodes_searched()
          << " nps "   << nps()
          << " pv ";
 
-    for (int j = 0; ss->pv[j] != MOVE_NONE && j < PLY_MAX; j++)
-        cout << ss->pv[j] << " ";
+    for (Move* m = pv; *m != MOVE_NONE; m++)
+        cout << *m << " ";
 
     cout << endl;
 
     if (UseLogFile)
     {
-        ValueType type =  (value >= beta  ? VALUE_TYPE_LOWER
-            : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
+        ValueType t = value >= beta  ? VALUE_TYPE_LOWER :
+                      value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT;
 
         LogFile << pretty_pv(pos, current_search_time(), Iteration,
-                             TM.nodes_searched(), value, type, ss->pv) << endl;
+                             TM.nodes_searched(), value, t, pv) << endl;
     }
   }
 

src/search.h

@@ -50,11 +50,11 @@ const int KILLER_MAX = 2;
 struct EvalInfo;
 
 struct SearchStack {
-  Move pv[PLY_MAX_PLUS_2];
   Move currentMove;
   Move mateKiller;
   Move threatMove;
   Move excludedMove;
+  Move bestMove;
   Move killers[KILLER_MAX];
   Depth reduction;
   Value eval;

src/tt.cpp

@@ -38,7 +38,7 @@ TranspositionTable TT;
 
 TranspositionTable::TranspositionTable() {
 
-  size = writes = 0;
+  size = overwrites = 0;
   entries = 0;
   generation = 0;
 }
@@ -100,6 +100,7 @@ void TranspositionTable::clear() {
 
 void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) {
 
+  int c1, c2, c3;
   TTEntry *tte, *replace;
   uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
 
@@ -115,18 +116,19 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
           tte->save(posKey32, v, t, d, m, generation, statV, kingD);
           return;
       }
-      else if (i == 0)  // replace would be a no-op in this common case
+
+      if (i == 0)  // replace would be a no-op in this common case
           continue;
 
-      int c1 = (replace->generation() == generation ?  2 : 0);
-      int c2 = (tte->generation() == generation ? -2 : 0);
-      int c3 = (tte->depth() < replace->depth() ?  1 : 0);
+      c1 = (replace->generation() == generation ?  2 : 0);
+      c2 = (tte->generation() == generation ? -2 : 0);
+      c3 = (tte->depth() < replace->depth() ?  1 : 0);
 
       if (c1 + c2 + c3 > 0)
           replace = tte;
   }
   replace->save(posKey32, v, t, d, m, generation, statV, kingD);
-  writes++;
+  overwrites++;
 }
 
 
@@ -155,7 +157,7 @@ TTEntry* TranspositionTable::retrieve(const Key posKey) const {
 void TranspositionTable::new_search() {
 
   generation++;
-  writes = 0;
+  overwrites = 0;
 }
 
 
@@ -185,20 +187,23 @@ 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[], const int PLY_MAX) {
+void TranspositionTable::extract_pv(const Position& pos, Move bestMove, Move pv[], const int PLY_MAX) {
 
   const TTEntry* tte;
   StateInfo st;
   Position p(pos, pos.thread());
   int ply = 0;
 
-  // Update position to the end of current PV
-  while (pv[ply] != MOVE_NONE)
-      p.do_move(pv[ply++], st);
+  assert(bestMove != MOVE_NONE);
 
-  // Try to add moves from TT while possible
+  pv[ply] = bestMove;
+  p.do_move(pv[ply++], st);
+
+  // Extract moves from TT when possible. We try hard to always
+  // get a ponder move, that's the reason of ply < 2 conditions.
   while (   (tte = retrieve(p.get_key())) != NULL
          && tte->move() != MOVE_NONE
+         && (tte->type() == VALUE_TYPE_EXACT || ply < 2)
          && move_is_legal(p, tte->move())
          && (!p.is_draw() || ply < 2)
          && ply < PLY_MAX)
@@ -211,11 +216,11 @@ void TranspositionTable::extract_pv(const Position& pos, Move pv[], const int PL
 
 
 /// TranspositionTable::full() returns the permill of all transposition table
-/// entries which have received at least one write during the current search.
+/// entries which have received at least one overwrite during the current search.
 /// It is used to display the "info hashfull ..." information in UCI.
 
 int TranspositionTable::full() const {
 
   double N = double(size) * ClusterSize;
-  return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
+  return int(1000 * (1 - exp(overwrites * log(1.0 - 1.0/N))));
 }

src/tt.h

@@ -110,15 +110,15 @@ public:
   TTEntry* retrieve(const Key posKey) const;
   void new_search();
   void insert_pv(const Position& pos, Move pv[]);
-  void extract_pv(const Position& pos, Move pv[], const int PLY_MAX);
+  void extract_pv(const Position& pos, Move bestMove, Move pv[], const int PLY_MAX);
   int full() const;
   TTEntry* first_entry(const Key posKey) const;
 
 private:
-  // Be sure 'writes' is at least one cache line away
+  // Be sure 'overwrites' is at least one cache line away
   // from read only variables.
   unsigned char pad_before[64 - sizeof(unsigned)];
-  unsigned writes; // heavy SMP read/write access here
+  unsigned overwrites; // heavy SMP read/write access here
   unsigned char pad_after[64];
 
   size_t size;