Revert previous patch

Revert the previous patch about move generation, as it unexpectedly
changed the bench. Better to take the time to understand the issue.

Bench: 4191632

diff --git a/src/movegen.cpp b/src/movegen.cpp
index c3c149b700b697a507667c0f7db40502263a1815..5049613617ac5eb304385fa82f40fc073dbed66f 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -175,19 +175,19 @@ namespace {
   }
 
 
-  template<Color Us, PieceType Pt, bool Checks>
-  ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
+  template<PieceType Pt, bool Checks>
+  ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard piecesToMove, Bitboard target) {
 
     static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");
 
-    Bitboard bb = pos.pieces(Us, Pt);
+    Bitboard bb = piecesToMove & pos.pieces(Pt);
 
     while (bb)
     {
         Square from = pop_lsb(bb);
 
         Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;
-        if (Checks && (Pt == QUEEN || !(pos.blockers_for_king(~Us) & from)))
+        if constexpr (Checks)
             b &= pos.check_squares(Pt);
 
         while (b)
@@ -204,11 +204,10 @@ namespace {
     static_assert(Type != LEGAL, "Unsupported type in generate_all()");
 
     constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantiations
-    const Square ksq = pos.square<KING>(Us);
-    Bitboard target;
-    
-    if (Type == EVASIONS && more_than_one(pos.checkers()))
-        goto kingMoves; // Double check, only a king move can save the day
+    Bitboard target, piecesToMove = pos.pieces(Us);
+
+    if(Type == QUIET_CHECKS)
+        piecesToMove &= ~pos.blockers_for_king(~Us);
 
     switch (Type)
     {
@@ -220,7 +219,7 @@ namespace {
             target = ~pos.pieces();
             break;
         case EVASIONS:
-            target = between_bb(ksq, lsb(pos.checkers()));
+            target = between_bb(pos.square<KING>(Us), lsb(pos.checkers()));
             break;
         case NON_EVASIONS:
             target = ~pos.pieces(Us);
@@ -228,22 +227,19 @@ namespace {
     }
 
     moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
-    moveList = generate_moves<Us, KNIGHT, Checks>(pos, moveList, target);
-    moveList = generate_moves<Us, BISHOP, Checks>(pos, moveList, target);
-    moveList = generate_moves<Us,   ROOK, Checks>(pos, moveList, target);
-    moveList = generate_moves<Us,  QUEEN, Checks>(pos, moveList, target);
+    moveList = generate_moves<KNIGHT, Checks>(pos, moveList, piecesToMove, target);
+    moveList = generate_moves<BISHOP, Checks>(pos, moveList, piecesToMove, target);
+    moveList = generate_moves<  ROOK, Checks>(pos, moveList, piecesToMove, target);
+    moveList = generate_moves< QUEEN, Checks>(pos, moveList, piecesToMove, target);
 
-kingMoves:
-    if (!Checks || pos.blockers_for_king(~Us) & ksq)
+    if (Type != QUIET_CHECKS && Type != EVASIONS)
     {
-        Bitboard b = attacks_bb<KING>(ksq) & (Type == EVASIONS ? ~pos.pieces(Us) : target);
-        if (Checks)
-            b &= ~attacks_bb<QUEEN>(pos.square<KING>(~Us));
-
+        Square ksq = pos.square<KING>(Us);
+        Bitboard b = attacks_bb<KING>(ksq) & target;
         while (b)
             *moveList++ = make_move(ksq, pop_lsb(b));
 
-        if ((Type == QUIETS || Type == NON_EVASIONS) && pos.can_castle(Us & ANY_CASTLING))
+        if ((Type != CAPTURES) && pos.can_castle(Us & ANY_CASTLING))
             for (CastlingRights cr : { Us & KING_SIDE, Us & QUEEN_SIDE } )
                 if (!pos.castling_impeded(cr) && pos.can_castle(cr))
                     *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(cr));
@@ -257,8 +253,6 @@ kingMoves:
 
 /// <CAPTURES>     Generates all pseudo-legal captures plus queen and checking knight promotions
 /// <QUIETS>       Generates all pseudo-legal non-captures and underpromotions (except checking knight)
-/// <EVASIONS>     Generates all pseudo-legal check evasions when the side to move is in check
-/// <QUIET_CHECKS> Generates all pseudo-legal non-captures giving check, except castling
 /// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
 ///
 /// Returns a pointer to the end of the move list.
@@ -266,8 +260,8 @@ kingMoves:
 template<GenType Type>
 ExtMove* generate(const Position& pos, ExtMove* moveList) {
 
-  static_assert(Type != LEGAL, "Unsupported type in generate()");
-  assert((Type == EVASIONS) == (bool)pos.checkers());
+  static_assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS, "Unsupported type in generate()");
+  assert(!pos.checkers());
 
   Color us = pos.side_to_move();
 
@@ -278,11 +272,62 @@ ExtMove* generate(const Position& pos, ExtMove* moveList) {
 // Explicit template instantiations
 template ExtMove* generate<CAPTURES>(const Position&, ExtMove*);
 template ExtMove* generate<QUIETS>(const Position&, ExtMove*);
-template ExtMove* generate<EVASIONS>(const Position&, ExtMove*);
-template ExtMove* generate<QUIET_CHECKS>(const Position&, ExtMove*);
 template ExtMove* generate<NON_EVASIONS>(const Position&, ExtMove*);
 
 
+/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures giving check,
+/// except castling. Returns a pointer to the end of the move list.
+template<>
+ExtMove* generate<QUIET_CHECKS>(const Position& pos, ExtMove* moveList) {
+
+  assert(!pos.checkers());
+
+  Color us = pos.side_to_move();
+  Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us) & ~pos.pieces(PAWN);
+
+  while (dc)
+  {
+     Square from = pop_lsb(dc);
+     PieceType pt = type_of(pos.piece_on(from));
+
+     Bitboard b = attacks_bb(pt, from, pos.pieces()) & ~pos.pieces();
+
+     if (pt == KING)
+         b &= ~attacks_bb<QUEEN>(pos.square<KING>(~us));
+
+     while (b)
+         *moveList++ = make_move(from, pop_lsb(b));
+  }
+
+  return us == WHITE ? generate_all<WHITE, QUIET_CHECKS>(pos, moveList)
+                     : generate_all<BLACK, QUIET_CHECKS>(pos, moveList);
+}
+
+
+/// generate<EVASIONS> generates all pseudo-legal check evasions when the side
+/// to move is in check. Returns a pointer to the end of the move list.
+template<>
+ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
+
+  assert(pos.checkers());
+
+  Color us = pos.side_to_move();
+  Square ksq = pos.square<KING>(us);
+
+  // Generate evasions for king
+  Bitboard b = attacks_bb<KING>(ksq) & ~pos.pieces(us);
+  while (b)
+      *moveList++ = make_move(ksq, pop_lsb(b));
+
+  if (more_than_one(pos.checkers()))
+      return moveList; // Double check, only a king move can save the day
+
+  // Generate blocking interpositions or captures of the checking piece
+  return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList)
+                     : generate_all<BLACK, EVASIONS>(pos, moveList);
+}
+
+
 /// generate<LEGAL> generates all the legal moves in the given position
 
 template<>