Factor out pieceList updating code

The new Position methods add_piece, move_piece, and remove_piece
now manage the member variables pieceList, pieceCount, and index,
and 9 blocks of code in Position that used to manipulate those
data structures by hand now call the new methods.

There is a slightly slowdown (< 1%) on Clang and on perft,
but the cleanup compensates the little speed loss.

No functional change.

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

diff --git a/src/position.cpp b/src/position.cpp
index 5dc94a634d665b08e878931ac1b7bb38389da8fa..6d416276c651aeb69cbd420a6335f02e84512596 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -797,17 +797,8 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
       byTypeBB[capture] ^= capsq;
       byColorBB[them] ^= capsq;
 
       byTypeBB[capture] ^= capsq;
       byColorBB[them] ^= capsq;
 

-      // Update piece list, move the last piece at index[capsq] position and
-      // shrink the list.
-      //
-      // WARNING: This is a not reversible operation. When we will reinsert the
-      // captured piece in undo_move() we will put it at the end of the list and
-      // not in its original place, it means index[] and pieceList[] are not
-      // guaranteed to be invariant to a do_move() + undo_move() sequence.
-      Square lastSquare = pieceList[them][capture][--pieceCount[them][capture]];
-      index[lastSquare] = index[capsq];
-      pieceList[them][capture][index[lastSquare]] = lastSquare;
-      pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
+      // Update piece lists
+      remove_piece(capsq, them, capture);

 
       // Update material hash key and prefetch access to materialTable
       k ^= Zobrist::psq[them][capture][capsq];
 
       // Update material hash key and prefetch access to materialTable
       k ^= Zobrist::psq[them][capture][capsq];


@@ -853,10 +844,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
       board[from] = NO_PIECE;
       board[to] = pc;
 
       board[from] = NO_PIECE;
       board[to] = pc;
 

-      // Update piece lists, index[from] is not updated and becomes stale. This
-      // works as long as index[] is accessed just by known occupied squares.
-      index[to] = index[from];
-      pieceList[us][pt][index[to]] = to;
+      move_piece(from, to, us, pt);

   }
 
   // If the moving piece is a pawn do some special extra work
   }
 
   // If the moving piece is a pawn do some special extra work


@@ -882,19 +870,14 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
           byTypeBB[promotion] |= to;
           board[to] = make_piece(us, promotion);
 
           byTypeBB[promotion] |= to;
           board[to] = make_piece(us, promotion);
 

-          // Update piece lists, move the last pawn at index[to] position
-          // and shrink the list. Add a new promotion piece to the list.
-          Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]];
-          index[lastSquare] = index[to];
-          pieceList[us][PAWN][index[lastSquare]] = lastSquare;
-          pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE;
-          index[to] = pieceCount[us][promotion];
-          pieceList[us][promotion][index[to]] = to;
+          // Update piece lists and add a new promotion piece to the list
+          remove_piece(to, us, PAWN);
+          add_piece(to, us, promotion);

 
           // Update hash keys
           k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to];
           st->pawnKey ^= Zobrist::psq[us][PAWN][to];
 
           // Update hash keys
           k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to];
           st->pawnKey ^= Zobrist::psq[us][PAWN][to];

-          st->materialKey ^=  Zobrist::psq[us][promotion][pieceCount[us][promotion]++]
+          st->materialKey ^=  Zobrist::psq[us][promotion][pieceCount[us][promotion]-1]

                             ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]];
 
           // Update incremental score
                             ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]];
 
           // Update incremental score


@@ -984,14 +967,9 @@ void Position::undo_move(Move m) {
       byTypeBB[PAWN] |= to;
       board[to] = make_piece(us, PAWN);
 
       byTypeBB[PAWN] |= to;
       board[to] = make_piece(us, PAWN);
 

-      // Update piece lists, move the last promoted piece at index[to] position
-      // and shrink the list. Add a new pawn to the list.
-      Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]];
-      index[lastSquare] = index[to];
-      pieceList[us][promotion][index[lastSquare]] = lastSquare;
-      pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE;
-      index[to] = pieceCount[us][PAWN]++;
-      pieceList[us][PAWN][index[to]] = to;
+      // Update piece lists and add new pawn to the list
+      remove_piece(to, us, promotion);
+      add_piece(to, us, PAWN);

 
       pt = PAWN;
   }
 
       pt = PAWN;
   }


@@ -1017,10 +995,7 @@ void Position::undo_move(Move m) {
       board[to] = NO_PIECE;
       board[from] = make_piece(us, pt);
 
       board[to] = NO_PIECE;
       board[from] = make_piece(us, pt);
 

-      // Update piece lists, index[to] is not updated and becomes stale. This
-      // works as long as index[] is accessed just by known occupied squares.
-      index[from] = index[to];
-      pieceList[us][pt][index[from]] = from;
+      move_piece(to, from, us, pt);

   }
 
   if (capture)
   }
 
   if (capture)


@@ -1045,8 +1020,7 @@ void Position::undo_move(Move m) {
       board[capsq] = make_piece(them, capture);
 
       // Update piece list, add a new captured piece in capsq square
       board[capsq] = make_piece(them, capture);
 
       // Update piece list, add a new captured piece in capsq square

-      index[capsq] = pieceCount[them][capture]++;
-      pieceList[them][capture][index[capsq]] = capsq;
+      add_piece(capsq, them, capture);

   }
 
   // Finally point our state pointer back to the previous state
   }
 
   // Finally point our state pointer back to the previous state


@@ -1250,8 +1224,7 @@ void Position::put_piece(Piece p, Square s) {
   PieceType pt = type_of(p);
 
   board[s] = p;
   PieceType pt = type_of(p);
 
   board[s] = p;

-  index[s] = pieceCount[c][pt]++;
-  pieceList[c][pt][index[s]] = s;
+  add_piece(s, c, pt);

 
   byTypeBB[ALL_PIECES] |= s;
   byTypeBB[pt] |= s;
 
   byTypeBB[ALL_PIECES] |= s;
   byTypeBB[pt] |= s;

diff --git a/src/position.h b/src/position.h
index 512313921458cae7d843214644026f2d7399fe25..1da49c10ca5e7d65264c3d2c12b114d6d4849809 100644 (file)
--- a/src/position.h
+++ b/src/position.h
@@ -194,6 +194,9 @@ private:
   // Helper functions
   void do_castle(Square kfrom, Square kto, Square rfrom, Square rto);
   Bitboard hidden_checkers(Square ksq, Color c) const;
   // Helper functions
   void do_castle(Square kfrom, Square kto, Square rfrom, Square rto);
   Bitboard hidden_checkers(Square ksq, Color c) const;

+  void remove_piece(Square s, Color c, PieceType pt);
+  void add_piece(Square s, Color c, PieceType pt);
+  void move_piece(Square from, Square to, Color c, PieceType pt);

 
   // Computing hash keys from scratch (for initialization and debugging)
   Key compute_key() const;
 
   // Computing hash keys from scratch (for initialization and debugging)
   Key compute_key() const;


@@ -414,4 +417,27 @@ inline Thread* Position::this_thread() const {
   return thisThread;
 }
 
   return thisThread;
 }
 

+inline void Position::add_piece(Square s, Color c, PieceType pt) {
+  index[s] = pieceCount[c][pt]++;
+  pieceList[c][pt][index[s]] = s;
+}
+
+inline void Position::move_piece(Square from, Square to, Color c, PieceType pt) {
+  // index[from] is not updated and becomes stale. This works as long
+  // as index[] is accessed just by known occupied squares.
+  index[to] = index[from];
+  pieceList[c][pt][index[to]] = to;
+}
+
+inline void Position::remove_piece(Square s, Color c, PieceType pt) {
+  // WARNING: This is not a reversible operation. If we remove a piece in
+  // do_move() and then replace it in undo_move() we will put it at the end of
+  // the list and not in its original place, it means index[] and pieceList[]
+  // are not guaranteed to be invariant to a do_move() + undo_move() sequence.
+  Square lastSquare = pieceList[c][pt][--pieceCount[c][pt]];
+  index[lastSquare] = index[s];
+  pieceList[c][pt][index[lastSquare]] = lastSquare;
+  pieceList[c][pt][pieceCount[c][pt]] = SQ_NONE;
+}
+

 #endif // #ifndef POSITION_H_INCLUDED
 #endif // #ifndef POSITION_H_INCLUDED