Reformat eval_init()

Move more code into eval_init, removing some
clutter in the main routine.

Write eval_init only from "our" point of view
(do not init the attackedBy[Them] bitboards).

Add mobilityArea to the evalinfo

A few edits while being there

tested for non-regression at STC
http://tests.stockfishchess.org/tests/view/587fab230ebc5915193f77d9
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 39585 W: 7183 L: 7094 D: 25308

Non functional change.

src/evaluate.cpp

@@ -73,6 +73,11 @@ namespace {
   // by the evaluation functions.
   struct EvalInfo {
 
+    Material::Entry* me;
+    Pawns::Entry* pe;
+    Bitboard pinnedPieces[COLOR_NB];
+    Bitboard mobilityArea[COLOR_NB];
+
     // attackedBy[color][piece type] is a bitboard representing all squares
     // attacked by a given color and piece type (can be also ALL_PIECES).
     Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
@@ -106,17 +111,13 @@ namespace {
     // a white knight on g5 and black's king is on g8, this white knight adds 2
     // to kingAdjacentZoneAttacksCount[WHITE].
     int kingAdjacentZoneAttacksCount[COLOR_NB];
-
-    Bitboard pinnedPieces[COLOR_NB];
-    Material::Entry* me;
-    Pawns::Entry* pi;
   };
 
   #define V(v) Value(v)
   #define S(mg, eg) make_score(mg, eg)
 
-  // MobilityBonus[PieceType][attacked] contains bonuses for middle and end
+  // MobilityBonus[PieceType][attacked] contains bonuses for middle and end game,
-  // game, indexed by piece type and number of attacked squares in the MobilityArea.
+  // indexed by piece type and number of attacked squares in the mobility area.
   const Score MobilityBonus[][32] = {
     {}, {},
     { S(-75,-76), S(-56,-54), S( -9,-26), S( -2,-10), S(  6,  5), S( 15, 11), // Knights
@@ -231,23 +232,35 @@ namespace {
   void eval_init(const Position& pos, EvalInfo& ei) {
 
     const Color  Them = (Us == WHITE ? BLACK : WHITE);
+    const Square Up   = (Us == WHITE ? NORTH : SOUTH);
     const Square Down = (Us == WHITE ? SOUTH : NORTH);
+    const Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB: Rank7BB | Rank6BB);
 
     ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
-    Bitboard b = ei.attackedBy[Them][KING];
-    ei.attackedBy[Them][ALL_PIECES] |= b;
-    ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
-    ei.attackedBy2[Us] = ei.attackedBy[Us][PAWN] & ei.attackedBy[Us][KING];
 
-    // Init king safety tables only if we are going to use them
+    // Find our pawns on the first two ranks, and those which are blocked
-    if (pos.non_pawn_material(Us) >= QueenValueMg)
+    Bitboard b = pos.pieces(Us, PAWN) & (shift<Down>(pos.pieces()) | LowRanks);
+
+    // Squares occupied by those pawns, by our king, or controlled by enemy pawns
+    // are excluded from the mobility area.
+    ei.mobilityArea[Us] = ~(b | pos.square<KING>(Us) | ei.pe->pawn_attacks(Them));
+
+    // Initialise the attack bitboards with the king and pawn information
+    b = ei.attackedBy[Us][KING] = pos.attacks_from<KING>(pos.square<KING>(Us));
+    ei.attackedBy[Us][PAWN] = ei.pe->pawn_attacks(Us);
+
+    ei.attackedBy2[Us]            = b & ei.attackedBy[Us][PAWN];
+    ei.attackedBy[Us][ALL_PIECES] = b | ei.attackedBy[Us][PAWN];
+
+    // Init our king safety tables only if we are going to use them
+    if (pos.non_pawn_material(Them) >= QueenValueMg)
     {
-        ei.kingRing[Them] = b | shift<Down>(b);
+        ei.kingRing[Us] = b | shift<Up>(b);
-        ei.kingAttackersCount[Us] = popcount(b & ei.attackedBy[Us][PAWN]);
+        ei.kingAttackersCount[Them] = popcount(b & ei.pe->pawn_attacks(Them));
-        ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
+        ei.kingAdjacentZoneAttacksCount[Them] = ei.kingAttackersWeight[Them] = 0;
     }
     else
-        ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
+        ei.kingRing[Us] = ei.kingAttackersCount[Them] = 0;
   }
 
 
@@ -255,8 +268,8 @@ namespace {
   // color and type.
 
   template<bool DoTrace, Color Us = WHITE, PieceType Pt = KNIGHT>
-  Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility,
+  Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility) {
-                        const Bitboard* mobilityArea) {
+
     const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
     const Color Them = (Us == WHITE ? BLACK : WHITE);
     const Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
@@ -294,14 +307,14 @@ namespace {
                    | ei.attackedBy[Them][BISHOP]
                    | ei.attackedBy[Them][ROOK]);
 
-        int mob = popcount(b & mobilityArea[Us]);
+        int mob = popcount(b & ei.mobilityArea[Us]);
 
         mobility[Us] += MobilityBonus[Pt][mob];
 
         if (Pt == BISHOP || Pt == KNIGHT)
         {
             // Bonus for outpost squares
-            bb = OutpostRanks & ~ei.pi->pawn_attacks_span(Them);
+            bb = OutpostRanks & ~ei.pe->pawn_attacks_span(Them);
             if (bb & s)
                 score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)];
             else
@@ -318,7 +331,7 @@ namespace {
 
             // Penalty for pawns on the same color square as the bishop
             if (Pt == BISHOP)
-                score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
+                score -= BishopPawns * ei.pe->pawns_on_same_color_squares(Us, s);
 
             // An important Chess960 pattern: A cornered bishop blocked by a friendly
             // pawn diagonally in front of it is a very serious problem, especially
@@ -342,16 +355,16 @@ namespace {
                 score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
 
             // Bonus when on an open or semi-open file
-            if (ei.pi->semiopen_file(Us, file_of(s)))
+            if (ei.pe->semiopen_file(Us, file_of(s)))
-                score += RookOnFile[!!ei.pi->semiopen_file(Them, file_of(s))];
+                score += RookOnFile[!!ei.pe->semiopen_file(Them, file_of(s))];
 
-            // Penalize when trapped by the king, even more if the king cannot castle
+            // Penalty when trapped by the king, even more if the king cannot castle
             else if (mob <= 3)
             {
                 Square ksq = pos.square<KING>(Us);
 
                 if (   ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
-                    && !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
+                    && !ei.pe->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
                     score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
             }
         }
@@ -369,13 +382,13 @@ namespace {
         Trace::add(Pt, Us, score);
 
     // Recursively call evaluate_pieces() of next piece type until KING is excluded
-    return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility, mobilityArea);
+    return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility);
   }
 
   template<>
-  Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
+  Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*) { return SCORE_ZERO; }
   template<>
-  Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*, const Bitboard*) { return SCORE_ZERO; }
+  Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*) { return SCORE_ZERO; }
 
 
   // evaluate_king() assigns bonuses and penalties to a king of a given color
@@ -400,12 +413,12 @@ namespace {
     int kingDanger;
 
     // King shelter and enemy pawns storm
-    Score score = ei.pi->king_safety<Us>(pos, ksq);
+    Score score = ei.pe->king_safety<Us>(pos, ksq);
 
     // Main king safety evaluation
     if (ei.kingAttackersCount[Them])
     {
-        // Find the attacked squares which are defended only by the king...
+        // Find the attacked squares which are defended only by our king...
         undefended =   ei.attackedBy[Them][ALL_PIECES]
                     &  ei.attackedBy[Us][KING]
                     & ~ei.attackedBy2[Us];
@@ -427,20 +440,15 @@ namespace {
                     -   7 * mg_value(score) / 5 - 5;
 
         // Analyse the enemy's safe queen contact checks. Firstly, find the
-        // undefended squares around the king reachable by the enemy queen...
+        // undefended squares around our king reachable by the enemy queen...
         b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
 
-        // ...and keep squares supported by another enemy piece
+        // ...and keep squares supported by another enemy piece.
         kingDanger += QueenContactCheck * popcount(b & ei.attackedBy2[Them]);
 
-        // Analyse the safe enemy's checks which are possible on next move...
+        // Analyse the safe enemy's checks which are possible on next move
         safe  = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
 
-        // ... and some other potential checks, only requiring the square to be
-        // safe from pawn-attacks, and not being occupied by a blocked pawn.
-        other = ~(   ei.attackedBy[Us][PAWN]
-                  | (pos.pieces(Them, PAWN) & shift<Up>(pos.pieces(PAWN))));
-
         b1 = pos.attacks_from<ROOK  >(ksq);
         b2 = pos.attacks_from<BISHOP>(ksq);
 
@@ -448,12 +456,18 @@ namespace {
         if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
             kingDanger += QueenCheck;
 
-        // For other pieces, also consider the square safe if attacked twice,
+        // For minors and rooks, also consider the square safe if attacked twice,
-        // and only defended by a queen.
+        // and only defended by our queen.
         safe |=  ei.attackedBy2[Them]
                & ~(ei.attackedBy2[Us] | pos.pieces(Them))
                & ei.attackedBy[Us][QUEEN];
 
+        // Some other potential checks are also analysed, even from squares
+        // currently occupied by the opponent own pieces, as long as the square
+        // is not attacked by our pawns, and is not occupied by a blocked pawn.
+        other = ~(   ei.attackedBy[Us][PAWN]
+                  | (pos.pieces(Them, PAWN) & shift<Up>(pos.pieces(PAWN))));
+
         // Enemy rooks safe and other checks
         if (b1 & ei.attackedBy[Them][ROOK] & safe)
             kingDanger += RookCheck;
@@ -476,7 +490,7 @@ namespace {
         else if (b & other)
             score -= OtherCheck;
 
-        // Compute the king danger score and subtract it from the evaluation
+        // Transform the kingDanger units into a Score, and substract it from the evaluation
         if (kingDanger > 0)
             score -= make_score(std::min(kingDanger * kingDanger / 4096,  2 * int(BishopValueMg)), 0);
     }
@@ -611,7 +625,7 @@ namespace {
     Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
     Score score = SCORE_ZERO;
 
-    b = ei.pi->passed_pawns(Us);
+    b = ei.pe->passed_pawns(Us);
 
     while (b)
     {
@@ -719,10 +733,10 @@ namespace {
     // Since SpaceMask[Us] is fully on our half of the board...
     assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
 
-    // ...count safe + (behind & safe) with a single popcount
+    // ...count safe + (behind & safe) with a single popcount.
     int bonus = popcount((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
     bonus = std::min(16, bonus);
-    int weight = pos.count<ALL_PIECES>(Us) - 2 * ei.pi->open_files();
+    int weight = pos.count<ALL_PIECES>(Us) - 2 * ei.pe->open_files();
 
     return make_score(bonus * weight * weight / 18, 0);
   }
@@ -824,8 +838,8 @@ Value Eval::evaluate(const Position& pos) {
   Score score = pos.psq_score() + ei.me->imbalance();
 
   // Probe the pawn hash table
-  ei.pi = Pawns::probe(pos);
+  ei.pe = Pawns::probe(pos);
-  score += ei.pi->pawns_score();
+  score += ei.pe->pawns_score();
 
   // We have taken into account all cheap evaluation terms.
   // If score exceeds a threshold return a lazy evaluation.
@@ -834,27 +848,11 @@ Value Eval::evaluate(const Position& pos) {
       return pos.side_to_move() == WHITE ? lazy : -lazy;
 
   // Initialize attack and king safety bitboards
-  ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
-  ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.square<KING>(WHITE));
-  ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.square<KING>(BLACK));
   eval_init<WHITE>(pos, ei);
   eval_init<BLACK>(pos, ei);
 
-  // Pawns blocked or on ranks 2 and 3 will be excluded from the mobility area
-  Bitboard blockedPawns[] = {
-    pos.pieces(WHITE, PAWN) & (shift<SOUTH>(pos.pieces()) | Rank2BB | Rank3BB),
-    pos.pieces(BLACK, PAWN) & (shift<NORTH>(pos.pieces()) | Rank7BB | Rank6BB)
-  };
-
-  // Do not include in mobility area squares protected by enemy pawns, or occupied
-  // by our blocked pawns or king.
-  Bitboard mobilityArea[] = {
-    ~(ei.attackedBy[BLACK][PAWN] | blockedPawns[WHITE] | pos.square<KING>(WHITE)),
-    ~(ei.attackedBy[WHITE][PAWN] | blockedPawns[BLACK] | pos.square<KING>(BLACK))
-  };
-
   // Evaluate all pieces but king and pawns
-  score += evaluate_pieces<DoTrace>(pos, ei, mobility, mobilityArea);
+  score += evaluate_pieces<DoTrace>(pos, ei, mobility);
   score += mobility[WHITE] - mobility[BLACK];
 
   // Evaluate kings after all other pieces because we need full attack
@@ -876,7 +874,7 @@ Value Eval::evaluate(const Position& pos) {
               - evaluate_space<BLACK>(pos, ei);
 
   // Evaluate position potential for the winning side
-  score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
+  score += evaluate_initiative(pos, ei.pe->pawn_asymmetry(), eg_value(score));
 
   // Evaluate scale factor for the winning side
   ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
@@ -892,7 +890,7 @@ Value Eval::evaluate(const Position& pos) {
   {
       Trace::add(MATERIAL, pos.psq_score());
       Trace::add(IMBALANCE, ei.me->imbalance());
-      Trace::add(PAWN, ei.pi->pawns_score());
+      Trace::add(PAWN, ei.pe->pawns_score());
       Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
       if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
           Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)