Introduce namespace Pawns

And retire old struct PawnTable along the same lines
of previous patch.

No functional change.

src/evaluate.cpp

@@ -37,7 +37,7 @@ namespace {
 
     // Pointers to material and pawn hash table entries
     Material::Entry* mi;
-    PawnEntry* pi;
+    Pawns::Entry* pi;
 
     // attackedBy[color][piece type] is a bitboard representing all squares
     // attacked by a given color and piece type, attackedBy[color][0] contains
@@ -405,7 +405,7 @@ Value do_evaluate(const Position& pos, Value& margin) {
   }
 
   // Probe the pawn hash table
-  ei.pi = pos.this_thread()->pawnTable.probe(pos);
+  ei.pi = Pawns::probe(pos, th->pawnsTable);
   score += ei.pi->pawns_value();
 
   // Initialize attack and king safety bitboards

src/pawns.cpp

@@ -80,18 +80,116 @@ namespace {
 
   #undef S
   #undef V
+
+  template<Color Us>
+  Score evaluate_pawns(const Position& pos, Bitboard ourPawns,
+                       Bitboard theirPawns, Pawns::Entry* e) {
+
+    const Color Them = (Us == WHITE ? BLACK : WHITE);
+
+    Bitboard b;
+    Square s;
+    File f;
+    Rank r;
+    bool passed, isolated, doubled, opposed, chain, backward, candidate;
+    Score value = SCORE_ZERO;
+    const Square* pl = pos.piece_list(Us, PAWN);
+
+    // Loop through all pawns of the current color and score each pawn
+    while ((s = *pl++) != SQ_NONE)
+    {
+        assert(pos.piece_on(s) == make_piece(Us, PAWN));
+
+        f = file_of(s);
+        r = rank_of(s);
+
+        // This file cannot be half open
+        e->halfOpenFiles[Us] &= ~(1 << f);
+
+        // Our rank plus previous one. Used for chain detection
+        b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
+
+        // Flag the pawn as passed, isolated, doubled or member of a pawn
+        // chain (but not the backward one).
+        chain    =   ourPawns   & adjacent_files_bb(f) & b;
+        isolated = !(ourPawns   & adjacent_files_bb(f));
+        doubled  =   ourPawns   & forward_bb(Us, s);
+        opposed  =   theirPawns & forward_bb(Us, s);
+        passed   = !(theirPawns & passed_pawn_mask(Us, s));
+
+        // Test for backward pawn
+        backward = false;
+
+        // If the pawn is passed, isolated, or member of a pawn chain it cannot
+        // be backward. If there are friendly pawns behind on adjacent files
+        // or if can capture an enemy pawn it cannot be backward either.
+        if (   !(passed | isolated | chain)
+            && !(ourPawns & attack_span_mask(Them, s))
+            && !(pos.attacks_from<PAWN>(s, Us) & theirPawns))
+        {
+            // We now know that there are no friendly pawns beside or behind this
+            // pawn on adjacent files. We now check whether the pawn is
+            // backward by looking in the forward direction on the adjacent
+            // files, and seeing whether we meet a friendly or an enemy pawn first.
+            b = pos.attacks_from<PAWN>(s, Us);
+
+            // Note that we are sure to find something because pawn is not passed
+            // nor isolated, so loop is potentially infinite, but it isn't.
+            while (!(b & (ourPawns | theirPawns)))
+                Us == WHITE ? b <<= 8 : b >>= 8;
+
+            // The friendly pawn needs to be at least two ranks closer than the
+            // enemy pawn in order to help the potentially backward pawn advance.
+            backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
+        }
+
+        assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns));
+
+        // A not passed pawn is a candidate to become passed if it is free to
+        // advance and if the number of friendly pawns beside or behind this
+        // pawn on adjacent files is higher or equal than the number of
+        // enemy pawns in the forward direction on the adjacent files.
+        candidate =   !(opposed | passed | backward | isolated)
+                   && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != 0
+                   &&  popcount<Max15>(b) >= popcount<Max15>(attack_span_mask(Us, s) & theirPawns);
+
+        // Passed pawns will be properly scored in evaluation because we need
+        // full attack info to evaluate passed pawns. Only the frontmost passed
+        // pawn on each file is considered a true passed pawn.
+        if (passed && !doubled)
+            e->passedPawns[Us] |= s;
+
+        // Score this pawn
+        if (isolated)
+            value -= IsolatedPawnPenalty[opposed][f];
+
+        if (doubled)
+            value -= DoubledPawnPenalty[opposed][f];
+
+        if (backward)
+            value -= BackwardPawnPenalty[opposed][f];
+
+        if (chain)
+            value += ChainBonus[f];
+
+        if (candidate)
+            value += CandidateBonus[relative_rank(Us, s)];
+    }
+
+    return value;
+  }
 }
 
+namespace Pawns {
 
-/// PawnTable::probe() takes a position object as input, computes a PawnEntry
+/// probe() takes a position object as input, computes a Entry object, and returns
-/// object, and returns a pointer to it. The result is also stored in a hash
+/// a pointer to it. The result is also stored in a hash table, so we don't have
-/// table, so we don't have to recompute everything when the same pawn structure
+/// to recompute everything when the same pawn structure occurs again.
-/// occurs again.
 
-PawnEntry* PawnTable::probe(const Position& pos) {
+Entry* probe(const Position& pos, Table& entries) {
 
   Key key = pos.pawn_key();
-  PawnEntry* e = entries[key];
+  Entry* e = entries[key];
 
   // If e->key matches the position's pawn hash key, it means that we
   // have analysed this pawn structure before, and we can simply return
@@ -118,112 +216,11 @@ PawnEntry* PawnTable::probe(const Position& pos) {
 }
 
 
-/// PawnTable::evaluate_pawns() evaluates each pawn of the given color
+/// Entry::shelter_storm() calculates shelter and storm penalties for the file
-
-template<Color Us>
-Score PawnTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
-                                Bitboard theirPawns, PawnEntry* e) {
-
-  const Color Them = (Us == WHITE ? BLACK : WHITE);
-
-  Bitboard b;
-  Square s;
-  File f;
-  Rank r;
-  bool passed, isolated, doubled, opposed, chain, backward, candidate;
-  Score value = SCORE_ZERO;
-  const Square* pl = pos.piece_list(Us, PAWN);
-
-  // Loop through all pawns of the current color and score each pawn
-  while ((s = *pl++) != SQ_NONE)
-  {
-      assert(pos.piece_on(s) == make_piece(Us, PAWN));
-
-      f = file_of(s);
-      r = rank_of(s);
-
-      // This file cannot be half open
-      e->halfOpenFiles[Us] &= ~(1 << f);
-
-      // Our rank plus previous one. Used for chain detection
-      b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
-
-      // Flag the pawn as passed, isolated, doubled or member of a pawn
-      // chain (but not the backward one).
-      chain    =   ourPawns   & adjacent_files_bb(f) & b;
-      isolated = !(ourPawns   & adjacent_files_bb(f));
-      doubled  =   ourPawns   & forward_bb(Us, s);
-      opposed  =   theirPawns & forward_bb(Us, s);
-      passed   = !(theirPawns & passed_pawn_mask(Us, s));
-
-      // Test for backward pawn
-      backward = false;
-
-      // If the pawn is passed, isolated, or member of a pawn chain it cannot
-      // be backward. If there are friendly pawns behind on adjacent files
-      // or if can capture an enemy pawn it cannot be backward either.
-      if (   !(passed | isolated | chain)
-          && !(ourPawns & attack_span_mask(Them, s))
-          && !(pos.attacks_from<PAWN>(s, Us) & theirPawns))
-      {
-          // We now know that there are no friendly pawns beside or behind this
-          // pawn on adjacent files. We now check whether the pawn is
-          // backward by looking in the forward direction on the adjacent
-          // files, and seeing whether we meet a friendly or an enemy pawn first.
-          b = pos.attacks_from<PAWN>(s, Us);
-
-          // Note that we are sure to find something because pawn is not passed
-          // nor isolated, so loop is potentially infinite, but it isn't.
-          while (!(b & (ourPawns | theirPawns)))
-              Us == WHITE ? b <<= 8 : b >>= 8;
-
-          // The friendly pawn needs to be at least two ranks closer than the
-          // enemy pawn in order to help the potentially backward pawn advance.
-          backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
-      }
-
-      assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns));
-
-      // A not passed pawn is a candidate to become passed if it is free to
-      // advance and if the number of friendly pawns beside or behind this
-      // pawn on adjacent files is higher or equal than the number of
-      // enemy pawns in the forward direction on the adjacent files.
-      candidate =   !(opposed | passed | backward | isolated)
-                 && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != 0
-                 &&  popcount<Max15>(b) >= popcount<Max15>(attack_span_mask(Us, s) & theirPawns);
-
-      // Passed pawns will be properly scored in evaluation because we need
-      // full attack info to evaluate passed pawns. Only the frontmost passed
-      // pawn on each file is considered a true passed pawn.
-      if (passed && !doubled)
-          e->passedPawns[Us] |= s;
-
-      // Score this pawn
-      if (isolated)
-          value -= IsolatedPawnPenalty[opposed][f];
-
-      if (doubled)
-          value -= DoubledPawnPenalty[opposed][f];
-
-      if (backward)
-          value -= BackwardPawnPenalty[opposed][f];
-
-      if (chain)
-          value += ChainBonus[f];
-
-      if (candidate)
-          value += CandidateBonus[relative_rank(Us, s)];
-  }
-
-  return value;
-}
-
-
-/// PawnEntry::shelter_storm() calculates shelter and storm penalties for the file
 /// the king is on, as well as the two adjacent files.
 
 template<Color Us>
-Value PawnEntry::shelter_storm(const Position& pos, Square ksq) {
+Value Entry::shelter_storm(const Position& pos, Square ksq) {
 
   const Color Them = (Us == WHITE ? BLACK : WHITE);
 
@@ -253,11 +250,11 @@ Value PawnEntry::shelter_storm(const Position& pos, Square ksq) {
 }
 
 
-/// PawnEntry::update_safety() calculates and caches a bonus for king safety. It is
+/// Entry::update_safety() calculates and caches a bonus for king safety. It is
 /// called only when king square changes, about 20% of total king_safety() calls.
 
 template<Color Us>
-Score PawnEntry::update_safety(const Position& pos, Square ksq) {
+Score Entry::update_safety(const Position& pos, Square ksq) {
 
   kingSquares[Us] = ksq;
   castleRights[Us] = pos.can_castle(Us);
@@ -283,5 +280,7 @@ Score PawnEntry::update_safety(const Position& pos, Square ksq) {
 }
 
 // Explicit template instantiation
-template Score PawnEntry::update_safety<WHITE>(const Position& pos, Square ksq);
+template Score Entry::update_safety<WHITE>(const Position& pos, Square ksq);
-template Score PawnEntry::update_safety<BLACK>(const Position& pos, Square ksq);
+template Score Entry::update_safety<BLACK>(const Position& pos, Square ksq);
+
+} // namespace Pawns

src/pawns.h

@@ -24,31 +24,30 @@
 #include "position.h"
 #include "types.h"
 
-const int PawnTableSize = 16384;
+namespace Pawns {
 
-/// PawnEntry is a class which contains various information about a pawn
+/// Pawns::Entry contains various information about a pawn structure. Currently,
-/// structure. Currently, it only includes a middle game and an end game
+/// it only includes a middle game and end game pawn structure evaluation, and a
-/// pawn structure evaluation, and a bitboard of passed pawns. We may want
+/// bitboard of passed pawns. We may want to add further information in the future.
-/// to add further information in the future. A lookup to the pawn hash
+/// A lookup to the pawn hash table (performed by calling the probe function)
-/// table (performed by calling the probe method in a PawnTable object)
+/// returns a pointer to an Entry object.
-/// returns a pointer to a PawnEntry object.
 
-class PawnEntry {
+struct Entry {
 
-  friend struct PawnTable;
+  Score pawns_value() const { return value; }
-
+  Bitboard pawn_attacks(Color c) const { return pawnAttacks[c]; }
-public:
+  Bitboard passed_pawns(Color c) const { return passedPawns[c]; }
-  Score pawns_value() const;
+  int file_is_half_open(Color c, File f) const { return halfOpenFiles[c] & (1 << int(f)); }
-  Bitboard pawn_attacks(Color c) const;
+  int has_open_file_to_left(Color c, File f) const { return halfOpenFiles[c] & ((1 << int(f)) - 1); }
-  Bitboard passed_pawns(Color c) const;
+  int has_open_file_to_right(Color c, File f) const { return halfOpenFiles[c] & ~((1 << int(f+1)) - 1); }
-  int file_is_half_open(Color c, File f) const;
-  int has_open_file_to_left(Color c, File f) const;
-  int has_open_file_to_right(Color c, File f) const;
 
   template<Color Us>
-  Score king_safety(const Position& pos, Square ksq);
+  Score king_safety(const Position& pos, Square ksq)  {
+
+    return kingSquares[Us] == ksq && castleRights[Us] == pos.can_castle(Us)
+         ? kingSafety[Us] : update_safety<Us>(pos, ksq);
+  }
 
-private:
   template<Color Us>
   Score update_safety(const Position& pos, Square ksq);
 
@@ -66,50 +65,10 @@ private:
   Score kingSafety[COLOR_NB];
 };
 
+typedef HashTable<Entry, 16384> Table;
 
-/// The PawnTable class represents a pawn hash table. The most important
+Entry* probe(const Position& pos, Table& entries);
-/// method is probe, which returns a pointer to a PawnEntry object.
 
-struct PawnTable {
-
-  PawnEntry* probe(const Position& pos);
-
-  template<Color Us>
-  static Score evaluate_pawns(const Position& pos, Bitboard ourPawns,
-                              Bitboard theirPawns, PawnEntry* e);
-
-  HashTable<PawnEntry, PawnTableSize> entries;
-};
-
-
-inline Score PawnEntry::pawns_value() const {
-  return value;
-}
-
-inline Bitboard PawnEntry::pawn_attacks(Color c) const {
-  return pawnAttacks[c];
-}
-
-inline Bitboard PawnEntry::passed_pawns(Color c) const {
-  return passedPawns[c];
-}
-
-inline int PawnEntry::file_is_half_open(Color c, File f) const {
-  return halfOpenFiles[c] & (1 << int(f));
-}
-
-inline int PawnEntry::has_open_file_to_left(Color c, File f) const {
-  return halfOpenFiles[c] & ((1 << int(f)) - 1);
-}
-
-inline int PawnEntry::has_open_file_to_right(Color c, File f) const {
-  return halfOpenFiles[c] & ~((1 << int(f+1)) - 1);
-}
-
-template<Color Us>
-inline Score PawnEntry::king_safety(const Position& pos, Square ksq) {
-  return kingSquares[Us] == ksq && castleRights[Us] == pos.can_castle(Us)
-       ? kingSafety[Us] : update_safety<Us>(pos, ksq);
 }
 
 #endif // !defined(PAWNS_H_INCLUDED)

src/position.cpp

@@ -918,7 +918,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   }
 
   // Prefetch pawn and material hash tables
-  prefetch((char*)thisThread->pawnTable.entries[st->pawnKey]);
+  prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
   prefetch((char*)thisThread->materialTable[st->materialKey]);
 
   // Update incremental scores

src/thread.h

@@ -112,7 +112,7 @@ public:
   Eval::Table evalTable;
   Material::Table materialTable;
   Endgames endgames;
-  PawnTable pawnTable;
+  Pawns::Table pawnsTable;
   size_t idx;
   int maxPly;
   Mutex mutex;